United States

Department of Agriculture

Forest Service

Southern

Research Station

General Technical

Report SRS-75

Southern Forest Science:

Past, Present, and Future

H. Michael Rauscher and Kurt Johnsen, Editors

ence: Past, Present, and Future

2004
BACK

COVER

PHOTOS

(left to right):

FRONT

COVER

PHOTOS

(left to right):

Since the 1930s,

survey crews have

been collecting

information about

forest conditions

on thousands of

permanent plots

established on

public and private

land—their results

form the basis of

economic forecasts

of timber markets,

public land

management

policies, and

incentives for

afforestation on

private lands.

(Photo by

M. Ward)

In early global

change research

at the Duke

Forest in Durham,

NC, chambers

were constructed

to measure the

effects of acid

rain and ozone

on loblolly pines.

(Photo by M.

Schoeneberger)

As they did in

reforestation

efforts a century

ago, disease

resistant seedlings

continue to play an

important role in

the sustainability

of southern

forests. (SRS

photo)

The Bent Creek

Experimental

Forest, known for

its work on oak

regeneration,

also conducts

research on bears

and other species

in mountain

landscapes.

(SRS photo)

Divers estimate

abundance of

trout in a study

of fish habitat in

the Southern

Appalachians.

(Photo by

P. Flebbe)

The Macon Fire

Laboratory in

Georgia has a long

history of providing solutions on

wildfire control,

prescribed burning, and smoke

management—

solutions that will

come into play

again as more and

more southerners

leave cities and

suburbs and move

into the wildland

urban interface.

(SRS photo)

Researchers

who are located

on university

campuses often

serve in adjunct

faculty positions

and as advisors

for graduate

students. (Photo

by D. Dwinell)

Since the 1930s,

the weirs at the

Coweeta Hydrologic Laboratory

have provided

long-term data

on the effects of

natural events and

human activities,

with early studies

on clearcutting,

mountain farming,

grazing, and road

building giving

way to later

research on air

pollution, insect

infestations,

and prescribed

burning. (SRS

photo)

When introduced

insect pests

threaten forests,

researchers often

find solutions by

combining new

study results

with techniques

learned from old

enemies like the

southern pine

beetles. (Photo

by B. Lea)

Mycorrhiza is a

beneficial fungus

that has been

found to promote

root formation

and tree growth

on sites disturbed

by mining and

other commercial

activities. (SRS

photo)

After Hurricane

Hugo scored a

direct hit on the

wetlands and

flatlands of South

Carolina in 1989,

artificial cavities

served as temporary shelters

for critically

low populations

of red-cockaded

woodpeckers.

(SRS photo)

Declining frog and

toad populations

sometimes are cited

as “early warning

signs” of adverse

changes in the

environment.

Whether such

changes result from

local disturbance or

from global climate

change, the unique

vocalizations of

amphibians may hold

the ecological key.

Here, a field scientist

calibrates a froglogger (an automated

recording device to

detect changes

in the amphibian

populations of a

southern wetland.

(Photo by Z. Hoyle)

AUTHORS H. Michael Rauscher, Forester, U.S. Department of Agriculture

Forest Service, Southern Research Station, Asheville, NC 28806; and

Kurt Johnsen, Supervisory Plant Physiologist and Project Leader,

U.S. Department of Agriculture Forest Service, Southern Research

Station, Research Triangle Park, NC 27709.
Southern Forest Science:

Past, Present, and Future

H. Michael Rauscher and Kurt Johnsen, Editors

October 2004

Southern Research Station

P.O. Box 2680

Asheville, NC 28802

List of Figures .......................................................................................................................................................... v

List of Tables .......................................................................................................................................................... ix

Foreword ¬ Pete Roussopoulos and Steering Committee ...................................................................... x

Looking Back

Chapter 1. A History of Southern Forest Science, Management,

and Sustainability Issues ¬ H. Michael Rauscher .................................................................................3

Chapter 2. Southern Forests: Yesterday, Today, and Tomorrow ¬ R. Neil Sampson .............. 5

Chapter 3. Southern Forest Resource Conditions and Management Practices

from 1900-1950: Benefits of Research ¬ James P. Barnett ..........................................................15

Chapter 4. Southern Forest Resource Conditions and Management Practices from

1950-2000: Benefits of Research ¬ Jacek P. Siry.............................................................................23

Chapter 5. The Southern Forest Resource Assessment: What We Learned ¬

David N. Wear and John G. Greis .............................................................................................................33

Productivity

Chapter 6. Productivity ¬ Thomas R. Fox and Ray R. Hicks, Jr. ....................................................47

Chapter 7. Silviculture and Management Strategies Applicable to Southern

Hardwoods ¬ Ray R. Hicks, Jr., William H. Conner, Robert C. Kellison, and David Van Lear ... 51

Chapter 8. The Evolution of Pine Plantation Silviculture in the Southern

United States ¬ Thomas R. Fox, Eric J. Jokela, and H. Lee Allen .....................................................63

Chapter 9. Reproduction Cutting Methods for Naturally Regenerated

Pine Stands in the South ¬ James M. Guldin .....................................................................................83

Chapter 10. The Role of Genetics and Tree Improvement in Southern

Forest Productivity ¬ R.C. Schmidtling, T.L. Robison, S.E. McKeand, R.J. Rousseau,

H.L. Allen, and B. Goldfarb ........................................................................................................................97

Chapter 11. Forest Mensuration with Remote Sensing: A Retrospective

and a Vision for the Future ¬ Randolph H. Wynne .........................................................................109

Forest Health

Chapter 12. Healthy Forests in the South: Challenges for the 21st Century ¬

Theodor D. Leininger and Gregory A. Reams.......................................................................................119

Chapter 13. Restoration of Southern Ecosystems ¬ John A. Stanturf,

Emile S. Gardiner, Kenneth Outcalt, William H. Conner, and James M. Guldin ...........................123

Chapter 14. Understanding and Controlling Nonnative Forest Pests in the South ¬

Kerry O. Britton, Donald A. Duerr II, and James H. Miller .............................................................133

Chapter 15. Advances in the Control and Management of the Southern

Pine Bark Beetles ¬ T. Evan Nebeker ...................................................................................................155

Chapter 16. The Impact and Control of Major Southern Forest Diseases ¬

A. Dan Wilson, Theodor D. Leininger, William J. Otrosina, L. David Dwinell,

and Nathan M. Schiff ................................................................................................................................161

Chapter 17. Monitoring the Sustainability of the Southern Forest ¬

Gregory A. Reams, Neil Clark, and James Chamberlain....................................................................179

iii

Contents
Water and Soils

Chapter 18. Water and Soils ¬ Carl C. Trettin ..................................................................................191

Chapter 19. Influences of Management of Southern Forests on Water Quantity

and Quality ¬ Ge Sun, Mark Riedel, Rhett Jackson, Randy Kolka, Devendra Amatya,

and Jim Shepard ........................................................................................................................................195

Socioeconomic

Chapter 20. Policy, Uses, and Values ¬ H. Ken Cordell .................................................................227

Chapter 21. Forest Values and Attitudes in the South: Past and Future

Research ¬ Michael A. Tarrant and R. Bruce Hull IV .......................................................................231

Chapter 22. Nonindustrial Forest Landowner Research: A Synthesis and New

Directions ¬ Gregory S. Amacher, M. Christine Conway, and J. Sullivan ....................................241

Chapter 23. Recreation and Nontimber Forest Products ¬

H. Ken Cordell and James L. Chamberlain ...........................................................................................253

Chapter 24. Timber Market Research, Private Forests, and Policy Rhetoric ¬

David N. Wear and Jeffrey P. Prestemon ...............................................................................................289

Biodiversity

Chapter 25. Biodiversity and Southern Forests ¬ Eric T. Linder ...............................................303

Chapter 26. Population Viability as a Measure of Forest Sustainability ¬

Eric T. Linder, Nathan A. Klaus, and David A. Buehler .....................................................................307

Chapter 27. Responses of Southeastern Amphibians and Reptiles to Forest

Management: A Review ¬ Kevin R. Russell, T. Bentley Wigley, William M. Baughman,

Hugh G. Hanlin, and W. Mark Ford .......................................................................................................319

Chapter 28. Monitoring Tree Species Diversity over Large Spatial and

Temporal Scales ¬ James F. Rosson, Jr., and Clifford C. Amundsen ..............................................335

Chapter 29. Population Growth and the Decline of Natural Southern Yellow

Pine Forests ¬ David B. South and Edward R. Buckner ...................................................................347

Climate Change

Chapter 30. Overview of Global Climate Change and Carbon Sequestration ¬

Kurt Johnsen ...............................................................................................................................................361

Chapter 31. Implications of Global Climate Change for Southern Forests: Can

We Separate Fact from Fiction? ¬ Hermann Gucinski, Ron Neilson, and Steve McNulty .... 365

Chapter 32. Carbon Sequestration in Loblolly Pine Plantations: Methods,

Limitations, and Research Needs for Estimating Storage Pools ¬ Kurt Johnsen,

Bob Teskey, Lisa Samuelson, John Butnor, David Sampson, Felipe Sanchez, Chris Maier,

and Steve McKeand ...................................................................................................................................373

Chapter 33. Forest Carbon Trends in the Southern United States ¬

Robert A. Mickler, James E. Smith, and Linda S. Heath ....................................................................383

Southern Forest Science:

Past, Present, and Future

Contents, continued

iv
v

List of Figures

Page

Figure 5.1—The region addressed by the Southern Forest Resource Assessment

(Wear and Greis 2002a). .............................................................................................................33

Figure 5.2—Removals by destination product, southwide, all species, 1952 to 1996

(Wear and Greis 2002a). .............................................................................................................36

Figure 5.3—Population, in millions, for the United States and for the 13 States in the

assessment area (Wear and Greis 2002a). ...............................................................................37

Figure 5.4—Forecast percent change in annual softwood harvest levels, 1995–

2040, by survey unit of the Forest Inventory and Analysis Program of the U.S.

Department of Agriculture Forest Service (Wear and Greis 2002a). .................................. 38

Figure 5.5—Percent of forest cover by county, 1992 (Wear and Greis 2002a). ..................... 39

Figure 5.6—Forest area in the Southern United States, 1630 to 1999 (Wear and

Greis 2002a). ................................................................................................................................39

Figure 5.7—Forecast of the area timberland by forest types, 1995 to 2040 (Wear

and Greis 2002a). .........................................................................................................................39

Figure 5.8—Number of terrestrial vertebrates in Southern States listed as

endangered (Wear and Greis 2002a). .......................................................................................41

Figure 5.9—Distribution of mussel species by aquatic fauna provinces (Wear

and Greis 2002a). .........................................................................................................................42

Figure 8.1—Number of acres of pine plantations in the Southern United States from

1952 to 1999 (data from U.S. Department of Agriculture 1988, Wear and Greis 2002)..... 64

Figure 8.2—Estimated total yield and pulpwood rotation age in pine plantations

in the Southern United States from 1940 through 2010. ...................................................... 64

Figure 8.3—Estimated contributions of intensive management practices to productivity

in pine plantations in the Southern United States from 1940 through 2010. ..................... 64

Figure 8.4—Growth increases in southern pine plantations due to tree improvement

practices in the Southern United States (adapted from Li and others 1997, Todd

and others 1995). .........................................................................................................................67

Figure 8.5—Effect of competition control on growth of loblolly pine at age 8

(adapted from Miller and others 1995). ...................................................................................70

Figure 8.6—Growth response of loblolly and slash pine on a variety of soil types

following midrotation application of nitrogen (N) and phosphorus (P) fertilizer

(adapted from North Carolina State Forest Nutrition Cooperative 1997). ........................ 71

Figure 8.7—Relationship between leaf area index and growth rate in southern

pine plantations. ..........................................................................................................................75

Figure 8.8—Performance of loblolly pine families [identifications are (A) 07–56,

(B) 08–59, and (C) 01–64] as site quality increases (adapted from McKeand and

others 1997)..................................................................................................................................75

Figure 8.9—Integration of rooted cuttings and somatic embryogenesis into a clonal

forestry program for southern pines in the United States. ...................................................76

Figure 9.1—Trends in forest area occupied by forest type and year, 1952–96

(Sheffield and Dickson 1998). .....................................................................................................83

continued
List of Figures, (continued)

Page

Figure 9.2—The strip clearcutting method demonstrated in a loblolly-shortleaf

pine stand, Crossett Experimental Forest, near Crossett, AR. Photo courtesy of

James M. Guldin 2003. ................................................................................................................85

Figure 9.3—The seed tree reproduction cutting method applied operationally

in a loblolly-shortleaf pine stand managed by forest industry, Ashley County, AR.

Photo courtesy of James M. Guldin 1984..................................................................................87

Figure 9.4—The shelterwood reproduction cutting method applied in a research

study on the Escambia Experimental Forest, near Brewton, AL. Photo courtesy

of James M. Guldin 1982. ............................................................................................................88

Figure 9.5—The group selection method in application to longleaf pine in a Farm

Forestry Forty demonstration on the Escambia Experimental Forest, near

Brewton, AL. Photo courtesy of James M. Guldin 1982.........................................................89

Figure 9.6—Stand structure in a stand under management using the selection

method, Good Farm Forestry Forty demonstration, Crossett Experimental Forest,

near Crossett, AR. Photo courtesy of James M. Guldin 1984................................................89

Figure 9.7—Diameter distributions of the Good Forty and the Poor Forty on the

Crossett Experimental Forest in the first 35 years of the demonstration—

(A) Good Forty in 1937, 1951, and 1971; (B) Poor Forty in 1937, 1951, and 1971. ............... 90

Figure 14.1—Amount of defoliation by the European gypsy moth 1940–2003. .................. 139

Figure 14.2—Logistic spread model for invasive nonnative plants. ..................................... 143

Figure 15.1—Diagram of adults, gallery patterns, and attack sites of the southern

pine bark beetle guild (Ips vulses, I. grandicollis, I. calligraphus, Dendroctonus

frontalis, and D. terebrans). Painting by Richard Kleifoth in 1964, Southern Forest

Research Institute, Jasper, TX; photo by Dr. Ronald Billings in 1981, Texas Forest

Service, Lufkin, TX. ..................................................................................................................156

Figure 16.1—Live oak injured by heavy tree-clearing equipment at a residential

building site in Austin, TX, providing entry points (infection courts) for introduction

of the oak wilt fungus into the living sapwood by insect vectors. Photo by

A. Dan Wilson. ............................................................................................................................162

Figure 16.2—Zone lines observed in decayed wood of sugar maple colonized by

Daldinia concentrica, mycosymbiont of Xiphydria maculata woodwasp larvae.

These antagonistic interactions form between the decay zones of xylariaceous wood

decay fungi around woodwasp galleries, and represent areas delimiting their territory

defended by the production of dark inhibitory compounds. Photo by A. Dan Wilson. .... 169

Figure 17.1—An interpenetrating pattern for a five-panel design. No element has

another member from the same panel as an immediate neighbor. There is one plot

per hexagon (Roesch and Reams 1999). ................................................................................. 182

Figure 17.2—Number of nontimber forest products enterprises by county for seven

Southern States..........................................................................................................................185

Figure 19.1—Provinces of the Bailey ecoregion and annual runoff of the Southern

United States. .............................................................................................................................196

Figure 19.2—Seasonal distribution of streamflow from four representative forested

watersheds across the Southern United States: (A) Arkansas mountains, (B) North

Carolina Coastal Plain, (C) Texas shrubland, and (D) Georgia Piedmont

(PPT= precipitation; PET= potential evapotranspiration). ............................................... 198

Southern Forest Science:

Past, Present, and Future

List of Figures, continued

vi
continued

List of Figures, (continued)

Page

Figure 19.3—Annual streamflow responses to repeated harvesting of mixed

hardwood forest (watershed 18 at Coweeta Hydrologic Laboratory) (adapted

from Swank and others 1988). .................................................................................................. 199

Figure 19.4—Cumulative sediment yield measured at one Appalachian watershed at

Coweeta Hydrologic Laboratory (A) in one of the first-order streams below a logging

road during the first 32 months after treatment, and (B) in the ponding basin of the

second-order stream (Swank and others 2001)...................................................................... 204

Figure 19.5—Predicted long-term annual water yield response to forest removal

at a 4-km resolution. Values are displayed at a 30-m land use/landcover resolution. ....... 216

Figure 26.1—Habitat potential for the chestnut-sided warbler on the Cherokee

National Forest under five management alternatives over a 60-year time horizon. ........ 312

Figure 28.1—Spatial distribution of clearcut timberland in Mississippi. Each dot

represents 500 ha of clearcut timberland, harvested between 1977 and 1994. During

this period, 1.6 million ha were clearcut. ................................................................................ 341

Figure 28.2—Mean species richness per sample unit for Mississippi, by survey

year, for all sample units. The error bars represent 2 standard errors of means. ........... 341

Figure 28.3—Mean species richness per sample unit for Mississippi, by survey

year, for sample units that had no evidence of harvesting disturbance during the

four survey measurements. The error bars represent 2 standard errors of means. ....... 341

Figure 29.1—The conversion of forested land to other land uses in the United

States from 1982 to 1997 (U.S. Department of Agriculture, Forest Service 2001). .......... 347

Figure 29.2—Actual and predicted decline of natural southern yellow pine

timberland in the South (U.S. Department of Agriculture, Forest Service 1988;

Wear and Greis 2002).................................................................................................................348

Figure 29.3—Increases in oak-hickory, oak-pine, and pine plantation stands from

1953 to 1997 (U.S. Department of Agriculture, Forest Service 2001). ............................... 348

Figure 29.4—Acreage of naturally regenerated longleaf-slash pine, loblollyshortleaf pine, and oak-hickory forests in the Eastern United States in 1997 by

ownership class (U.S. Department of Agriculture, Forest Service 2001). ......................... 351

Figure 29.5—The afforestation of nonforested land to timberland in the United

States from 1982 to 1997 (U.S. Department of Agriculture, Forest Service 2001). .......... 351

Figure 29.6—The amount of land in pine stands and amount of natural regeneration

(age class 1 to 5 years) for five southern yellow pines. ......................................................... 352

Figure 29.7—Acreage of natural even-aged pine stands by species and 5-year age

classes. The number on each graph represents the ratio obtained by dividing the

number of acres in the 0- to 10-year age class by the number of acres in age class

41 to 50 years. .............................................................................................................................354

Figure 31.1—The reconstructed Earth surface air temperature record for the past

millennium (http://www.ipcc.ch/present/graphics/2001syr/ppt/05.16.ppt). ........................ 367

Figure 31.2—Predicted change in water supply stress defined as the ratio of the

2025 demand and supply divided by the 1990 ratio of demand and supply. Higher

stress is the result of both increasing demand (population pressure) and the

changed supply (climate driven) (McNulty and others 2004). ............................................. 369

List of Figures, continued

vii
continued

List of Figures, (continued)

Page

Figure 32.1—(A) standing biomass and (B) annual biomass production for fertilized

trees from the Southeast Tree Research and Education Site located in North

Carolina. The stand was established in 1985 and data are from 1995, 3 years after

fertilization commenced. ...........................................................................................................374

Figure 32.2—Stem biomass estimates obtained by applying six independently

derived biomass equations for two tree size or tree age classes. Confidence intervals

(CI) of 95 percent are shown for each size class. ................................................................... 375

Figure 32.3—Standing volume estimates, using two growth-and-yield equations,

for 10-year-old loblolly pine stand trees grown for the last 5 years under four

treatments: control (C), irrigation (I), fertilization (F), and irrigation plus fertilization

(IF). Treatments are described in Albaugh and others (1988). ........................................... 375

Figure 32.4—Relationship between litterfall, estimated leaf area index (LAI),

and nondestructive measures using a LI-COR LAI-2000 from the Southeast Tree

Research and Education Site. ..................................................................................................376

Figure 32.5—Taproots excavated from a 20-year-old plantation in South Carolina,

showing the variation in root morphology. Photos by Lance Kress.................................... 377

Figure 32.6—Relationship between aboveground biomass and coarse root biomass

across sites. Note: All estimates are via biomass sampling except those for the

Williamsburg site, where stem volumes were estimated using a volume equation and

converted to carbon values as described in text and value was adjusted to add branch

and leaf carbon using Baldwin and others (1997). Southeast Tree Research and

Education Site (SETRES) estimates are via Albaugh and others (1998); Bainbridge,

GA, from Samuelson and others (in press); Williamsburg, Co., SC; Duke Forest,

NC, from Ralston (1973); and Clemson, SC, from Van Lear and others (1984, 1995). ..... 378

Figure 32.7—Percent soil carbon (C), by soil profile depth, over time, for stands

from the long-term site productivity experiment located in the Croatan National

Forest in coastal North Carolina. The previous stand was harvested and the new

stand planted in year zero. .......................................................................................................379

Figure 33.1—Aboveground carbon (C) density (Mg C/ha) for forested lands in 1997

in the Southern United States. ................................................................................................389

Figure 33.2—Mean net annual tree growth 1953–97 in terms of carbon (C) density

(Mg C/ha/year) for forested lands in the Southern United States...................................... 389

Figure 33.3—Estimated total aboveground forest carbon (C) stock for

(A) Southcentral and (B) Southeastern States 1953–97. Total C mass (Mt) is for all

productive forest land within each State. Aboveground C includes that in live and

dead trees, understory vegetation, down dead wood, and the forest floor......................... 390

Figure 33.4—Estimated mean annual change in aboveground forest carbon stock

1953–97. Estimates are for productive forest land................................................................ 391

Figure 33.5—Estimated mean annual change of carbon in the harvested products

categories 1953–97. ....................................................................................................................391

Figure 33.6—Estimated annual net primary production [g carbon (C) m2/year]

for all forest types using the Hadley2Sul climate scenario for (A) 2000, (B) 2050,

and (C) 2100. ...............................................................................................................................392

Southern Forest Science:

Past, Present, and Future

List of Figures, continued

viii
ix

List of Tables

Page

Table 2.1—1980–99 population by State, southern region, and nationally with

2004 projection. ............................................................................................................................12

Table 4.1—Intensively managed planted pine growth and yield data (wood volume)

for medium sites and 25-year rotation. .....................................................................................25

Table 4.2—Extent of intensive forest management practices in the South. .........................27

Table 4.3—Growth rates (wood volume) for intensively managed planted pine

(MIC 5) and SRTS-FIA forest management types.................................................................28

Table 8.1—Growth rates of pines throughout the World. ........................................................73

Table 13.1—Longleaf pine restoration prescription depends upon site type and the

condition of the overstory and understory. ............................................................................ 126

Table 14.1—Examples of intentionally introduced invasive nonnative weeds.................... 135

Table 16.1—Global class membership (identity) of aroma profiles for sapwood cores

of selected southern hardwoods based on electrical aroma signatures obtained from

the 32-sensor array of the Aromascan A32S. ......................................................................... 168

Table 16.2—Determinations of global class memberships (identity) of aroma profiles

for four Armillaria spp. based on electronic aroma signature comparisons with an

Armillaria reference library database obtained from the 32-sensor array of the

Aromascan A32S. .......................................................................................................................168

Table 16.3—Symbiotic insect-wood decay fungi pest complexes that cause synergistic

defect losses of hardwood lumber volume in southern and eastern hardwood species. .. 170

Table 17.1—The degree to which the FHM and FIA programs are currently

addressing the criteria and indicators of the Montreal Process as specified in the

1995 Santiago Agreement. .......................................................................................................183

Table 19.1—Hydrologic characteristics of eight major physiographic regions in the

Southern United States. ...........................................................................................................197

Table 26.1—Habitat variables and descriptions used to construct chestnut-sided

warbler model. ............................................................................................................................311

Table 29.1—Changes in timberland area over a 44-year period for selected species

in the United States. ..................................................................................................................349

Table 29.2—Acres of southern yellow pines in the Eastern United States during

the 1990s, number of Forest Inventory and Analysis survey plots (data generated

from Forest Inventory Mapmaker Version 1.0: run Oct 15, 2001), and the authors’

predicted decline in natural stands for the mid-21st century. ............................................... 352

Table 29.3—Inventory of Table Mountain pine growing stock by diameter class for

two periods. .................................................................................................................................355

Table 32.1—Site mean, mean square error, and estimated sample size needed, by

soil profile depth, to detect 10-percent differences between treatment means for root

biomass (A) and percent soil carbon (B). ................................................................................ 379

Table 33.1—Mean aboveground carbon density of productive southern forests

(timberlands) by forest type and carbon pool, 1997. ............................................................. 387

Table 33.2—Mean aboveground tree carbon mass of southern forests by forest type

and ownership classifications, 1997. ........................................................................................ 388

Table 33.3—Hadley 2000, 2050, and 2100 minimum, maximum, and average net

primary production for all forest types. ................................................................................. 391
Foreword

Forest science, like any science, is a continuous process. Research scientists

collaborate in a largely informal, world-wide network to produce new knowledge—

most frequently in the form of peer-reviewed articles—published in the scientific

literature. It is difficult, even for those working in some area of forest science, to be

aware of and understand the impact of this steady accumulation of theoretical and

practical knowledge. For nonscientists, keeping up with forest science knowledge is

indeed a daunting task.

It is equally difficult to appreciate the career-long contributions to forest science

knowledge of the many, many dedicated researchers in the South we must thank for

painstakingly building the level of understanding of ecosystems and their management

that we have attained today. Research scientists are usually rewarded individually for

their particular contributions. However, the collective effort of that broad and deep

community of scientists who have worked at universities, at State research centers,

in private industry, and at Federal agencies for nearly a century is seldom formally

recognized. It is the aggregate effort of these men and women in all fields of southern

forest science that we have to thank for the huge improvement in our understanding

and management skill.

This book was produced as a way to recognize and celebrate that contribution.

It was produced to highlight the summits of knowledge that we have attained. It was

produced to point out the marvelous results generated by the scientific method applied

over a long period of time by dedicated, and often brilliant, forest scientists. Finally, it

was produced in recognition that access to knowledge and the ability to use it wisely

have always been the hallmarks of successful individuals, organizations, and nations.

As we celebrate the first centennial of Forest Service stewardship, we gratefully

dedicate this work to all who have toiled to advance the frontier of knowledge about

southern forests and their management.

Peter J. Roussopoulos

Director, Southern Research Station

U.S. Department of Agriculture, Forest Service

Asheville, North Carolina

Southern Forest Science:

Past, Present, and Future

x
Looking Back
Southern Forest Science:

Past, Present, and Future

Looking Back

2

Chapter 1. A History of Southern Forest Science,

Management, and Sustainability Issues. ............................................ 3

Chapter 2. Southern Forests:

Yesterday, Today, and Tomorrow. ................................. 5

Chapter 3. Southern Forest Resource

Conditions and Management Practices from

1900–1950: Benefits of Research. ....................... 15

Chapter 4. Southern Forest Resource

Conditions and Management Practices from

1950–2000: Benefits of Research. ....................... 23

Chapter 5. The Southern Forest Resource Assessment:

What We Learned. ................................................................. 33
3

Chapter 1.

A History

of Southern Forest Science,

Management, and Sustainability Issues

T

he 13 Southern States from Virginia to

Texas have a combined area of approximately

500 million acres. Our understanding of the

complex cultural and ecological history of this

large region is still evolving. It may be fair to say

that until recently, our view of the native peoples

of the South and the landscape in which they lived

derived chiefly from reports provided by the few

European explorers who traveled through this

region between A.D. 1500 and A.D. 1700. Their

factual descriptions were accurate, but their

understanding of the native cultures and ecology

was limited and this led to erroneous conclusions

(Owen 2002).

Native Americans have lived in the South

for about 10,000 years. Early estimates of preEuropean population density, which were based

on early English accounts, are now thought to be

much too low (Carroll and others 2002). It is now

believed that there were 1.5 to 2 million members

of the Mississippian cultures living in the region in

the year 1500. Diseases introduced by the Spanish

explorers in the next 100 years greatly reduced

the size of this population and resulted in the

collapse of the Mississippian culture by 1600

(Carroll and others 2002). It is now thought that

approximately two-thirds of the Native American

population in the South was eliminated (Owen

2002). As a result, the large areas that had been

used for farming and fire-managed forest lands

throughout the South changed between 1600 and

1700 from “a mosaic of open pine and hardwood

woodlands, prairies, meadows, and oak or pine

savannas in a variety of successional stages”

(Carroll and others 2002) to a forest that was

much denser in both its overstory and understory

(Owen 2002). It was this rapidly revegetating,

dense forest with a large proportion of remnant

old growth that the Europeans interpreted as

pristine wilderness largely untouched by

human hands. This limited understanding

of the ecological dynamics of the pre-European

South found its way into our history books and

has resulted in a distorted popular vision of what

the natural southern forest ecosystem was and

should be today.

The second chapter “Southern Forests:

Yesterday, Today, and Tomorrow” by R. Neil

Sampson focuses on the events that most strongly

affected the land, forests, and people of the South

between 1900 and the present. Until about 1880,

European settlement and forest exploitation

tended to be concentrated on flat lands adjacent

to rivers. Thus we learn that a map of forest

conditions in the South at that time clearly

indicates the patterns of rivers, which show up

as areas where all of the merchantable pine had

been cut. The coming of the railroad opened up

the interior South to economical forest harvesting,

mining, and agriculture. The railroad was the key

to getting products to market profitably. Between

1860 and 1920, 90 million acres of mature longleaf

pine (Pinus palustris Mill.) stands were harvested

(Barnett 2004). Land was cheap and plentiful, and

this led to large-scale land speculation, timber

exploitation, and finally resale of the denuded land

to farmers. Large areas of marginal land, thus,

came into cultivation or were used for grazing and

then slowly abandoned as the soil was eroded and

its fertility depleted. Copper and iron smelters

sprung up in many areas of the South, and their

acid fumes and fuel needs denuded thousands of

acres of land. These deplorable conditions brought

about the rise of the conservation movement

around 1900; purchasing of unwanted land by

the public to create the first national forests

in the East; creation of the U.S. Department

of Agriculture Forest Service and State forestry

agencies; and the beginning of scientifically

based forest management.

The third chapter “Southern Forest Resource

Conditions and Management Practices from

1900–1950: Benefits of Research” by James

P. Barnett tells the story of forest science

H. Michael Rauscher1

1

 Forester, U.S. Department of Agriculture Forest Service,

Southern Research Station, Asheville, NC 28806.
Southern Forest Science:

Past, Present, and Future

Looking Back

4

during the first half of the 20th century. The most

urgent needs between 1900 and 1930 were the

reforestation of the millions of acres of cutover

forest land and the control of wildfire on that

land. In 1900 we had little scientific knowledge

about reforestation. By 1933 when the Civilian

Conservation Corps (CCC) was established

to provide employment to some 3 million men,

our reforestation knowledge and technology

had advanced far enough so that we could

use this manpower effectively in the first major

effort to tackle our Nation’s huge forest and soil

conservation needs. “With only a handful of

professional foresters and despite little technical

support and primitive working conditions, forestry

in the South has made tremendous gains” (Barnett

2004). This first half century of achievement in

forest science provided the basic knowledge that

forest managers have used to make the South’s

Coastal Plain the most productive timber growing

region in the world and to restore the mountain

South’s deciduous hardwood forests, which have

great ecological importance.

The story of forest science in the South

continues in the fourth chapter, “Southern

Forest Resource Conditions and Management

Practices from 1950–2000: Benefits of Research,”

by Jacek P. Siry. The basic knowledge of forest

management developed earlier was refined and,

most importantly, implemented on a very large

scale between 1950 and 2000. This chapter

tells the story of the South’s distinctive system

of intensive planted pine management. Hardwood

forests occupy more than half of the region’s

forest land, and management of hardwoods has

received substantial research effort. However,

there has been less research and investment in

hardwood management than in pine management

because hardwood management has been less

profitable than pine management (Siry 2004).

In the 1950s, southern pines were managed

primarily in natural stands and with low intensity.

Even after the large CCC reforestation campaign,

only 2 million acres had been planted in pine

forests while 7 million acres were still classified

as nonstocked and in need of reforestation (Siry

2004). By 1997, however, there were 30 million

acres of pine plantations in the South. Pine

management was intensifying rapidly and

productivity was increasing continuously. By 2040,

the area in planted pine is expected to expand to

54 million acres, mostly as a result of reforestation

of abandoned agricultural land (Wear and Greis

2004). The South’s planted and natural pine

forests represent < 3 percent of global conifer

forest cover, and yet the region supplies nearly 19

percent of global industrial softwood harvests

(Siry 2004). No other region or country in the

world supplies more softwood timber than the U.S.

South. This impressive success story is not widely

known or appreciated by the people in the United

States. It should be pointed out that the 30 million

acres of pine plantations is still much less than the

90 million acres of longleaf pine forest in the South

in 1900.

In the last quarter century, timber harvesting

and development of land for urban uses has

increased substantially in the South, leading

to questions about the health, productivity, and

sustainability of the South’s forests (Wear and

Greis 2004). The Southern Forest Resource

Assessment was initiated in 1999 to address

these concerns (Wear and Greis 2002). The final

chapter entitled “The Southern Forest Resource

Assessment: What We Learned” by David N.

Wear and John G. Greis is a summary of the

findings of this assessment.

LITERATURE CITED

Barnett, James P. 2004. The impact of research on southern

forest resource conditions and management practices:

1900–1950. In: Rauscher, H. Michael; Johnsen, Kurt, eds.

Southern forest science: past, present, and future. Gen.

Tech. Rep. SRS–75. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southern Research Station:

15–22.

Carroll, Wayne D.; Kapeluck, Peter R.; Harper, Richard A.; Van

Lear, David H. 2002. Background paper: historical overview

of the southern forest landscape and associated resources.

In: Wear, David N.; Greis, John G., eds. Southern forest

resource assessment. Gen. Tech. Rep. SRS–53. Asheville,

NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station: 583–605. Chapter 24.

Owen, Wayne. 2002. The history of native plant communities in

the South. In: Wear, David N.; Greis, John G., eds. Southern

forest resource assessment. Gen. Tech. Rep. SRS–53.

Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southern Research Station: 47–61. Chapter 2.

Siry, Jacek P. 2004. The impact of research on southern forest

resource conditions and management practices: 1950–2000.

In: Rauscher, H. Michael; Johnsen, Kurt, eds. Southern

forest science: past, present, and future. Gen. Tech. Rep.

SRS–75. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southern Research Station: 23–31.

Wear, David N.; Greis, John G. 2004. The southern forest

resource assessment: what we learned. In: Rauscher, H.

Michael; Johnsen, Kurt, eds. Southern forest science: past,

present, and future. Gen. Tech. Rep. SRS–75. Asheville, NC:

U.S. Department of Agriculture, Forest Service, Southern

Research Station: 33–44.

Wear, David N.; Greis, John G., eds. 2002. Southern forest

resource assessment. Gen. Tech. Rep. SRS–53. Asheville,

NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 645 p.
5

Chapter 2.

Southern Forests:

Yesterday, Today, and Tomorrow

R. Neil Sampson1

Abstract—In the 20th century, southern forests

changed dramatically. Those changes pale,

however, when compared to what happened to

the people of the region. In addition to growing

over fourfold in numbers, the South’s population

has urbanized, globalized, and intellectualized in

100 years. Rural and isolated in the 19th

 century,

they are today urban and cosmopolitan. One result

has been a complete change in the approach to

forestry. No longer an industrial process harvesting

what nature has grown, it is now a scientifically

based management process that produces a

wide variety of goods and services. Thus what

is happening in today’s southern forest is unlike

anything that would have been imagined 100

years ago. A large part of that is due to the

advances in forest science and its wholesale

adoption by industrial corporations, nonindustrial

forest owners, and public agencies.

As the human population has grown and

urbanized, however, a new threat to forest

management has arisen. Urban pressures not

only convert land from forest to other uses, they

also pressure forest managers to eliminate practices

that offend the sensibilities of urban people. This

“proximity pressure” threatens to take far more

forest out of sustainable management than actual

land use conversion will take. In some southern

areas, it may eliminate forest management entirely

in the coming century.

Forest science is, thus, challenged to find new

ways to manage forests and communicate the

values of that management in ways acceptable

to urban neighbors. If they do not, they will face

the reality that knowing how to manage a forest

well is of little value unless there are forests where

management can occur.

INTRODUCTION

T

he story of the southern forests is a rich one,

told in many ways by many people. This brief

review will touch on three aspects of that

story—land, forests, and people. It will feature

two snapshots in time—1900 and 2000—spanning

a century of great change to illustrate insights

that could be of some value as we enter this 21st

century. The main events that shaped the land,

forests, and people of the South in the last century

are well known. They include:

• The decline of agriculture and mining in the

region, and the legacies these activities left

behind on the land

• The movement of the timber industry to

the region

• The development of professional forestry

and land management

• The creation and growth of the U.S.

Department of Agriculture Forest Service

(Forest Service), the National Forest System,

and the State forestry agencies

• The rise of the conservation movement

with its new agencies and programs

• Two World Wars and the accompanying surges

of demand for natural resources

• Population growth and associated urbanization

As this history unfolds, it reveals changes of

such magnitude that, had they been foretold by

scholars in 1900, those good people would have no

doubt been made a laughingstock. As we enter the

21st century, we ask ourselves whether it is possible

that changes of similar magnitude lie in store for

the region. If so, we can only speculate as to what

those new situations may be and how people and

organizations may need to respond to them.

1

 President, The Sampson Group, Inc., Alexandria, VA 22310.
Southern Forest Science:

Past, Present, and Future

Looking Back

6

THE PAST—LAND, FORESTS,

AND PEOPLE IN 1900

T

he South consists of 13 Southern States

running in a broad band from Virginia to

Texas, with a total area of just over half a

billion acres. That size has not changed markedly

in the last century, and is perhaps the only

common statistic between then and now.

Everything else is different.

According to U.S. census figures, there were

around 21 million people living in the region in

1900. That same source shows that somewhere

around 60 percent of all Americans were living in

rural areas at the time and it is clear that the

South was overwhelmingly rural (U.S. Census

Bureau 1990).

And the region’s inhabitants were clearly

“southern,” often insulated from more than local

influence by the limits of the communication and

transportation systems of the day. For example,

as late as 1936, one author describes the people in

the Tennessee Valley in this way:

The people . . . are hospitable, proud,

salty, independent, illiterate by modern

standards, and desperately poor. They

are poor because many of their ancient

crafts have lapsed or because in the highly

specialized economy of today the exchange

value of these crafts is low (Chase 1936).

Land and forest statistics were few in 1900,

and estimates of the forest resource, for example,

were little more than educated guesses. In

1896, Chief Fernow of the U.S. Department of

Agriculture (USDA), Division of Forestry had

this to say: “There are no forestry statistics in

existence. Even the census figures referring to the

lumber industry are avowedly imperfect and based

on partial returns. The data given, therefore, are

only approximations and must be taken with that

reserve” (Fernow 1896). For the South, Fernow

suggested that somewhere around 50 percent of

the region still retained its forest cover. If he was

correct, that would mean somewhere in the range

of 250 million acres of forest at that time. He

estimated the annual national timber harvest at

somewhere around 40 billion board feet, with the

South contributing about 25 percent. By 1900,

however, it was estimated that the South was

producing more lumber than any other region,

and by 1919 it was said to be producing around 37

percent of the national total (Williams 1989).

Longleaf (Pinus palustris Mill.) and shortleaf

(P. echinata Mill.) pine were the most important

commercial species of the day, and Fernow had this

to say about loblolly (P. taeda L.): “It is the ‘old

field’ pine of the Southern States. Thus far it

has been of much less importance as a source

of lumber than the other Southern pines.”

He also noted that, among the oaks, white oak

(Quercus alba L.) had been the type most

harvested, being used “almost exclusively for

construction and cooperage.” “Black walnut,”

he wrote, “once common in the rich bench lands

of the Mississippi Basin has been so largely

cut as almost to have disappeared from market

quotations” (Fernow 1896).

The pattern of forest harvest was telling.

In an 1880 map of forest conditions of the South,

the pattern of rivers and streams was clearly

defined, shown as regions from which all of the

merchantable pine had been cut (Williams 1989).

The high value of the waterways for floating heavy

logs to market made those areas the first to be cut

over. In the swamps where the highly valued

cypress (Taxodium spp.) was found, the trees

were girdled and killed so that they would lose

enough sap to float, then harvested from boats

or by men wading in the water, to be skidded to a

rafting point by “pull boats” that plied along

channels that were blasted into the swamp to give

a central access route to which the logs could be

cable-skidded. With these methods, two things

happened: cypress harvest rose to around 1 billion

board feet per year by 1905, and the species was

virtually cut out by 1913 (Williams 1989).

Forest conservation and management were

virtually nonexistent. In many areas, trees were

free for the asking, and public land could be taken

for free or nearly free, as well. Private speculators

were buying land for $1.25 an acre, estimating that

it would yield from 6 to 12 thousand board feet

per acre (Williams 1989). For the most part, the

valuable pine trees were utilized only to the lowest

branch, with the remainder left to rot or burn.

Other major southern forest products were the

rosin and turpentine that were produced almost

entirely by distilling the gum of southern pines.

At the turn of the century, these were produced

by tapping trees and collecting the resulting sap.

By 1920, much of it was coming from the steam

distillation of the old stumps left behind by

early logging. Today, these products come as

a byproduct of the process of pulping to turn

pine trees into paper products (U.S. Department

of Agriculture, Forest Service 1988).

For farmers in 1900, getting rid of trees so they

could plow the land was the important concern,

and valleys filled with smoke testified to the
7

widespread use of fire as a primary land clearing

tool (Plair and Spillers 1960). Any lumber

company that employed a technical forester for

his knowledge of forest management would have

been laughed out of the woods. You didn’t need a

college degree to swing an axe or wrestle floating

logs out of a swamp.

Technology was coming into the woods rapidly,

cutting costs, increasing output, and expanding the

logger’s reach across the landscape. Oxen skidding

was slow and expensive, so wherever possible, it

was being supplemented or replaced by splash

dams, dynamited channels, pull boats, and other

forms of water transport. Where the land was

dry, railroads expanded rapidly to access valuable

pine timber. Much of that technology was highly

damaging to the environment, but those concerns

were many decades from being effectively voiced.

It was a time of “cut out and get out” to maximize

the profits from land speculation.

For the lumber companies, the last profits from

the land often came from selling it to would-be

farmers, and many set up real estate offices to

promote the virtues of farming on the cutover

lands. But the soils were often sandy or swampy,

and while a few farmers succeeded on the better

lands, many simply played out their money and

abandoned the place (Williams 1989). By 1920,

it was estimated that 30 million acres of cutover

forest showed little prospect of restocking or

helping the region recover its resource strength

(Williams 1989).

Thus the forest legacy in the early parts of

the 20th century was one of cutover pine lands,

a depleted cypress resource, and high-graded

hardwood forests. As timber harvesting and

agricultural land clearing continued, the region’s

forest acreage declined, reaching a low some time

around 1920 (U.S. Department of Agriculture,

Forest Service 1988). Adding to the region’s forest

woes was the chestnut blight {Cryphonectria

parasitica (Murrill) Barr [formerly Endothia

parasitica (Murrill) Anderson & Anderson]}.

The killer fungus reached Virginia in 1912 and

by 1920 had largely eliminated one of the most

valuable species in the southern hardwood forests

(Yarnell 1998).

Equally significant to the region’s landscapes,

agriculture was undergoing major change.

King cotton was under siege by the boll weevil

(Anthonomus grandis grandis), and crops

were rapidly vanishing from hillside soils where

cultivation had exposed susceptible soils to rapid

erosion. A 1911 soil survey of Fairfield County,

SC, for example, determined that 90,000 acres

of formerly cultivated land should be classified as

rough gullied land as a result of erosion (Bennett

1939). Those gullies, common across the region’s

sloping lands, were beginning to be a major

topic of concern. Hugh Hammond Bennett, who

would become the national leader in a new soil

conservation movement, wrote the following

about the soil erosion situation in the South:

A much lighter rain than formerly now

turns the Tennessee River red with wash

from the red lands of its drainage basin.

Added to the severe impoverishment of a

tremendous area of land throughout this

great valley, and its extensions southward

into Georgia and Alabama and northward

into Virginia, are the gullied areas, which

are severely impaired or completely

ruined by erosion ravines that finger out

through the numerous hill slopes and even

many undulating valley areas. Field after

field has been abandoned to brush, and

the destruction continues (Bennett and

Chapline 1928).

In other places, the environmental effects

of industry were plainly evident. In eastern

Tennessee and northern Georgia, the acid fumes

from copper and iron smelting killed thousands

of acres of forest (Yarnell 1998). Stuart Chase

(1936) describes one such scene in Tennessee:

The road curved around the crest and

Ducktown rose before us – a little village

and a huge smelter perched on a hill. In a

great circle about the smelter, measuring

perhaps ten miles in diameter, every living

thing had been destroyed by the sulphur

fumes. These were bad lands without

the balance and natural composure

of a desert.

The picture that emerges from this long

look back is pretty grim. Across the southern

landscape, the evidence of land misuse would have

been appalling to today’s eyes. But the beginnings

of the conservation movement were taking root,

and the warnings were beginning to be heard

across the land. In some respects, those warnings

sound overly alarmist today, but then they were a

wake-up call. There was much talk of a “timber

famine,” for example. How wrong was Pinchot

(1910) when he wrote:

Chapter 2.

 Yesterday, Today, and Tomorrow
Southern Forest Science:

Past, Present, and Future

Looking Back

8

The figures cited are, however, sufficiently

reliable to make it certain that the United

States has already crossed the verge of a

timber famine so severe that its blighting

effects will be felt in every household in

the land.

Or what about Bennett, who testified in

Congress (1935) that the soil erosion surveys

conducted by the Department of Agriculture

. . . revealed 51,465,097 acres of land

essentially destroyed by wind or water

erosion insofar as having further use for

crop production, except for occasional

patches. Most of this had been cultivated,

and once was good soil.2

The timber famine, of course, never

materialized, nor did millions of acres of American

land turn into sterile desert. Does this indicate

that the warnings were false, or does it indicate

that an awakened citizenry could address land

management problems and effectively correct

destructive trends before they continued to

disaster? There is ample evidence, I think, to

support the latter view. Pioneers like Pinchot

and Bennett, along with dozens of others in public

service and private business, created the climate

of public concern needed to support new public

policies, agencies, programs, and expenditures.

The increase in scientific knowledge through

research and practice provided new tools to

combat land waste. Private citizens, seeing that

the future of their life’s investments, whether in a

family farm or an industrial corporation, required

a more sustainable approach to land management,

often led the way in experimentation.

LAND MANAGEMENT COMES

TO THE SOUTH

A

s the 20th century dawned, a major national

conservation movement was beginning to

emerge. Slowly in many places and with many

faces, it began to address the serious resource

problems of America. Nowhere was this more

evident, or more needed, than in the South.

From the time of his work on the Biltmore

Estate in the 1890s, and also after he became Chief

of USDA’s Division of Forestry in 1898, Gifford

Pinchot was intent on changing the manner in

which private lumber companies were managing

the Nation’s forests. Within weeks after taking

over the USDA job, he issued Circular 21,

which launched an ambitious program of

technical assistance to the companies. Secretary

of Agriculture Wilson noted that, under this new

approach, Federal technicians would provide

advice and “the private owners will pay the

expenses of Department agents who give

instructions.” Many companies accepted the

offer, sending cash and offering free transportation

and board to Federal agents who would come and

help them (Steen 1976).

One example was the Kirby Lumber Company,

which owned 1.2 million acres that contained about

80 percent of all the longleaf pine forest in Texas.

A 50-man team from the Bureau of Forestry

worked to gather data for a plan that contained

recommendations on minimum tree size for

logging, which trees to leave as a seed source,

a timber marking plan, and a fire protection

plan. This focus on assisting private landowners

continued for only a decade or so, displaced

not so much by failures in the program as by

the enormous workload placed on the newly

named Forest Service when the National Forest

System was created under its management in

1905 (Steen 1976).

The administration of the forest reserves was

transferred to the Forest Service, and the 1911

Weeks Act opened the way for the purchase of

the lands that became the national forests of the

South. These actions were largely the result of

political action by citizens’ organizations. Chief

among these actors was the American Forestry

Association (AFA), which had been founded in

1875 and counted virtually all of the top national

forestry officials in its leadership. Also critical

in the political wars were organizations like the

American Civic Association and the General

Federation of Women’s Clubs. There was powerful

opposition to the use of Federal funds for the

purchase of forest reserves, and only the

persistent and growing power of citizen’s groups

could overcome it (Clepper 1975). Land purchases

under the Weeks Act started immediately after

the law was enacted. In 1912, 287.7 thousand

acres were approved for purchase at an average

price of $5.65 per acre (Clepper 1975). The

purchases continued across the region into the

late 1930s, leading to the current system of

national forests, comprising some 12.3 million

acres in the region (U.S. Department of

Agriculture, Forest Service 2000).

2

 Bennett, H.H. 1935. Statement presented before

Subcommittee of House Committee on Public Lands,

March 20, 1935.
9

The Weeks Act and later the Clarke-McNary

Act spurred great growth in the cooperation

between the Forest Service and the State

forestry agencies. By the 1920s, thousands

of landowners were receiving technical forestry

advice from State service foresters, supported

by a combination of Federal and State

cooperative funds.

During this same period (1903 to 1928), Hugh

Bennett was conducting soil surveys throughout

the Southern States, and his warnings about the

extent and danger of soil erosion were attracting

increasing attention. Finally in 1929, Congress

appropriated $160,000 for soil erosion studies

and Bennett was placed in charge of the work

(Sampson 1981).

THE NEW DEAL’S CONSERVATION DECADE

T

he 1930s brought enormous change to the

forestry and land conservation programs

of the United States. It was a time of great

environmental and social stress. Thousands

of displaced people, jobless and destitute, fled

damaged farm and forest lands to seek work

in cities, where there were few opportunities

following the stock market crash of 1929. For

President Franklin D. Roosevelt, the challenge

seemed twofold—economic recovery and

environmental repair. His proposal, in 1933, for

a Civilian Conservation Corps (CCC) to provide

needed employment and tackle the forest and soil

conservation needs of the Nation, was passed into

law by Congress after only 10 days (Sampson and

DeCoster 1997). Young men were put to work for

$30 a month in salary, half of which was to be sent

home to their families. In addition, they were

provided room, board, uniforms, and medical care.

In its 9 years of existence, some 3 million

CCC men were provided with work and

training, for a total cost of some $2.5 billion

(Zimmerman 1976). Some of their impressive

forestry accomplishments included the

construction of more than 1,300 fire lookout

towers, almost 40,000 miles of telephone lines,

over 50,000 miles of roads and trails, 1.25 billion

trees planted, and over 2 million man-days of

fire fighting. Many of the campground facilities,

lodges, and recreational sites developed by the

CCC remain in use today.

In 1934, as the first national soil erosion

surveys were being completed, dust from the

drought-stricken Great Plains darkened skies

in Washington, DC, and a new national soil

conservation program was born (Sampson 1981).

Although spared much of the Dust Bowl damage

(except in Oklahoma and Texas), the South was the

focal point of much of the new activity because of

the widespread damage caused by gullying. As the

new Soil Conservation Service was moved into

USDA in 1935, it was given supervision of over 450

CCC camps that provided the manpower needed

to address soil and water conservation problems.

The CCC boys attacked gullies with little more

than shovels and axes and, in the process,

demonstrated that this serious erosion could

be halted (Sampson 1985).

To help facilitate the local work of soil and

water conservation, a new form of local special

Government was created—the soil conservation

district. As with many other innovations, it saw its

first implementation in the South as Brown Creek

District in North Carolina became the first to be

formed (Sampson 1985).

Another influential venture of the period was

started in 1927 when the AFA set out to raise

money for an educational campaign on forest fire

prevention and control aimed at the rural people

of the South. Known officially as the Southern

Forestry Educational Project, it was launched

in Florida, Georgia, and Mississippi with the

purchase and outfitting of five trucks. Each truck

had an electric generator to power a motion

picture projector and carried two men—a lecturer

and a projector operator. Movies produced by

the USDA and the AFA were shown in thousands

of rural towns and were often the first motion

pictures seen by many of the residents. At the

end of the first year of operation, it was estimated

that the trucks had traveled 78,000 miles into

94 counties and reached 700,000 people (Clepper

1975). By the time it was closed down in 1931, it

was estimated that the “Dixie Crusaders,” as the

teams had begun to be called, had reached some 3

million people in the 3 Southern States and South

Carolina, which had been added to the program

(Clepper 1975).

While these were only a few of the activities

underway, what also emerged in the 1930s was

a new framework of Federal and State policy

in regard to forests. In general, it emphasized

the protection of forests from wildfire and the

protection of wildlife from overharvesting. It

promoted the management of forests, farmlands,

and wildlife with methods based on scientific

principles and carried out most of its activities

through a variety of cooperative arrangements

that often involved several Federal, State, and

local agencies (MacCleery 1992).

Chapter 2.

 Yesterday, Today, and Tomorrow
Southern Forest Science:

Past, Present, and Future

Looking Back

10

While there were many achievements of this

new policy approach, one of the more notable was

the dramatic reduction in annual wildfire area. By

the end of the 1930s, cooperative fire suppression

programs were beginning to be more effective, and

wildfires, which had burned as much as 50 million

acres a year, began a decline that lasted through

the 1970s (MacCleery 1992). Another important

cooperative achievement was the dramatic

increase in tree planting programs.

TREE PLANTING—PUBLIC AND PRIVATE

P

lanned reforestation through tree planting

had started in the South early in the 1900s

through the work of pioneering landowners

such as Henry Hardtner of Louisiana, who planted

about 27,000 acres to southern pines under a 1913

contract, and the Goodyears of Bogalusa, who

planted some 15,000 acres (Williams 1989). But

these were the exceptions, not the rule, and it

was not until the 1924 Clarke-McNary Act that

authorized Federal cost-sharing support for

State tree seed and nursery programs as well

as increased educational and technical assistance

to landowners, that the program was able to gain

real momentum (Zimmerman 1976).

While the forest products industry, with its

future hinging on new tree crops, was the most

aggressive tree planter, public programs have

played an important role in spurring private

landowners to reforest their land. Recent

increases in tree planting have been as significant

as those produced by the CCC in the 1930s.

(Moulton and Hernandez 1999). In 1936 through

the creation of the Agricultural Adjustment

Administration, Congress authorized cost

sharing with private landowners for conservation

purposes. Included in those purposes was

tree planting for reforestation, windbreaks,

and shelterbelts.

But in midcentury, the appraisal of the Forest

Service was still that tree planting was a major

national need. Citing more than 114 million acres

(23 percent of the commercial forest area) as being

nonstocked or poorly stocked, the Agency said that

tree planting was one of the most effective ways of

getting that vast acreage into production and

keeping it productive (U.S. Department of

Agriculture, Forest Service 1958).

In 1956, the first version of a conservation

reserve—the Soil Bank—was enacted to help

reduce crop surpluses through conversion of

cropland into grass or trees. Under the program,

USDA cost shared tree planting and paid land

rental for 10 years. In 1985, a similar program—

the Conservation Reserve Program—was

launched. It is still in effect, and by 1992 it was

estimated that more than 2.5 million acres of trees

had resulted. The South has taken full advantage

of these programs. Over the last 20 years, from 65

to 82 percent of the tree planting in the United

States has occurred in the South (Moulton and

Hernandez 1999).

CONSERVATION CHALLENGE SHIFTS GEARS

T

his rapid overview of the changes in forests,

land, and people of the South over the last

century has shown that an early concern for

the mismanagement of rural lands, including

forests, led to a major conservation revolution.

By 2000, the science of forest management

had progressed far enough so that it could

be concerned with more than timber supply.

It could aspire to produce sustainable forests—

forest ecosystems that remain productive and

intact over centuries, continuing to produce a

full variety of economic and environmental goods

and services—because of the management and

care of skilled hands.

During that century of change, virtually

everything has changed. The amount of total

forest in the South is now around 214 million

acres (Smith and Sheffield 2000). If the 1896

rough estimate was accurate, that’s a reduction of

some 20 to 50 million acres. More comparable data

suggest that, since 1952 when the first reliable

surveys were taken, the area of timberland has

declined from 204.5 to 201 million acres in 2000

(Powell and others 1993, Smith and Sheffield

2000). While that acreage change was modest,

the amount of timber growing on the land has

increased significantly. Softwood timber volumes

rose from 60.5 to 105 million cubic feet in the

region, while hardwood timber volumes rose

from 88 to 152 million cubic feet (Powell and

others 1993, Smith and Sheffield 2000). Thus

on a similar area, the amount of standing timber

almost doubled, signaling a major achievement

for forest management and conservation over

the past half century.

Today, southern pines produce merchantable

timber in < 25 years in many places. The

efficiency of timber utilization is extremely high,

and logs with 2-inch tops are being sent to the

mill in some places. As a result, fewer acres of

forest are harvested to obtain a similar amount

of useful product.
11

High-flotation machines move through pine

plantations, thinning out excess trees and sending

them off to market without leaving soil ruts—

in places without leaving a mark to show they

have passed. Riparian buffers and streamside

management zones protect the most productive

habitats on the landscape and, as a result, plants

and critters great and small share the forest with

commercial timbering operations.

The forest products industry, once noted

primarily for its cut-and-run strategies, is today

the largest single employer of professional

foresters (Society of American Foresters 2001)

and a leader in defining and applying the

principles of sustainable forest management

(AF&PA 2001). There is much to be learned,

but the science and art of forest management

has clearly matured significantly.

The revolution in U.S. forestry has been

compared with the transition made thousands of

years ago by agriculture—from a foraging activity

that simply harvested what nature had provided

to a cropping activity involving planting, tending,

and harvesting (Sedjo 1991).

Now, however, a new conservation question

has emerged as a result of the enormous land

use changes in the 20th century, and it may be the

most challenging that the forestry profession has

faced to date. That question, in short, is: “How

much forest will be available for sustainable forest

management in the future?” We may know how to

manage the land, but if manageable land is not

available, that skill is of little value.

There are, perhaps, three aspects to this

threat to the future of forests and forestry in the

South. First is the direct conversion of forest land

to other uses. No longer is agriculture the major

consumer of forest land as it was in the past.

Today, it is urban development that moves land

out of forest production (U.S. Department of

Agriculture, Natural Resources Conservation

Service 2001). The amount of land converted is

fairly modest. Between 1992 and 1997, it amounted

to about 1 million acres in the Nation according to

the USDA’s National Resource Inventories. Given

the increases in forest productivity and efficiency

that have emerged from forest science in the latter

decades of the 1900s, that loss alone is probably

not terribly significant.

But it is not just the loss of forest land, it is the

pattern of that loss that leads to the second aspect

of the change. Forests are being increasingly

fragmented, and that has both environmental and

economic consequences. From an environmental

point of view, habitats may become disconnected,

making normal movements of plants, animals,

and genotypes more difficult. Those that become

isolated may find it more difficult to thrive, or

even survive. From an economic standpoint, every

forestry operation becomes more expensive as

forest tract size declines and, at some point, the

prices received for forest products go down as well

(Thorne and Sundquist 2001). All of these effects

make forest production increasingly marginal and,

at some point, landowners simply give up on using

the forest as a production asset and either hold it

as an amenity or sell it to the highest bidder.

Either way, the area available for sustainable

forest management is diminished.

Finally, however, is the third aspect of the

pressure—the one that may be most difficult

to identify and quantify. This can be labeled

proximity pressure and it works like this—as

urban populations move into a rural area, the

opposition to rural land uses is almost certain

to rise. For farmers, it is the objection of urban

citizens to the smells of livestock or the dust and

noise of farm operations. For forest managers,

it is opposition to the sight of a clearcut harvest,

the weight of log trucks on local roads, or the

pressure of land taxes that respond to potential

land sale value rather than forest production

values (Sampson and DeCoster 1997). The

pressures can be either direct or indirect, but they

are cumulative. They make continued production

seem risky, and when landowners decide that there

is little or no future for production agriculture or

forestry in their area, that decision becomes selffulfilling. Long-term investments such as tree

planting or timber stand improvement are no

longer made, and even the most conscientious

landowners become land speculators—waiting

to turn their life’s work and investment into cash

for retirement.

As landowners reduce their forest management,

either through land sales or simply slowing down,

they produce less wood for local mills and less

work for local contractors. At some point, usually

when a market downturn makes things even more

difficult, those mills close or those contractors

decide to move or go out of the business. In

return, the remaining landowners who are still

trying to manage their forests find their economic

opportunities diminishing, either through reduced

market competition, reduced availability of

contractors, or the total lack of one or the other.

Chapter 2.

 Yesterday, Today, and Tomorrow
Southern Forest Science:

Past, Present, and Future

Looking Back

12

Table 2.1—1980–99 population by State, southern region, and nationally with 2004 projection

State 1980 1990 1999 2004 Change 1980–99

number percent

Alabama 3,893,267 4,040,587 4,385,470 4,591,457 492,203 13

Arkansas 2,284,614 2,350,725 2,568,170 2,725,840 283,556 12

Florida 9,744,073 12,937,926 15,018,424 16,085,294 5,274,351 54

Georgia 5,462,825 6,478,216 7,698,381 8,429,990 2,235,556 41

Kentucky 3,660,129 3,685,296 3,965,923 4,099,292 305,794 8

Louisiana 4,205,883 4,219,973 4,394,632 4,450,485 188,749 4

Mississippi 2,519,711 2,573,216 2,774,493 2,905,761 254,782 10

North Carolina 5,879,261 6,628,637 7,590,605 8,060,154 1,711,344 29

Oklahoma 3,024,740 3,145,585 3,361,437 3,478,481 336,697 11

South Carolina 3,121,614 3,486,703 3,855,261 4,019,194 733,647 24

Tennessee 4,585,757 4,877,185 5,485,923 5,818,327 900,166 20

Texas 14,218,841 16,986,510 19,989,393 21,714,566 5,770,552 41

Virginia 5,345,266 6,187,358 6,884,125 7,296,332 1,538,859 29

Southern region 67,945,981 77,597,917 87,972,237 93,675,173 20,026,256 29

National 225,169,362 247,051,601 270,361,877 282,490,898 45,192,515 20

The result is a continued downward spiral in

the local opportunity to own and manage forest

land for sustained production.

To some observers, that may sound like a

scenario limited to the heavily populated areas of

the Northeast but not likely to concern the rural

South. The facts, however, are that the South is

becoming increasingly urbanized, and as a result,

the future of forestry is dubious in many areas.

Look, for example, at table 2.1, taken from U.S.

Census figures and projections for 1980 to 2004.

Note that between 1980 and 1999, the population

of the region rose by 20 million. That means that

between 1980 and 2000—a period of 20 years—as

many new people moved into the South as the total

population of the region in 1900! So now there are

some 90 million in the 13-State area—almost onethird of the Nation’s population.

But how can we assess this population change in

terms of its implications for production forestry?

To address this question, we developed maps of

the South using a Virginia Department of Forestry

study published in 1997 that analyzed that State’s

commercial forest in terms of its availability for

future forest production (Liu and Scrivani 1997).

They found that while the amount of forested land

in Virginia has been relatively stable for the last

quarter-century, the future of forestry on much

of that land is likely to be greatly different from

its past. Population growth, urban and suburban

sprawl, and changes in forest ownership have

caused some 20 percent of the State’s forests to

be doubtful in terms of future timber production.

The basis for assessing population pressures

came from research by Wear and others indicating

that the probability of sustainable management

approaches zero at 150 people per square mile

(psm); that there is a 25-percent chance at 70 psm;

a 50-percent chance at 45 psm; and a 75-percent

chance at 20 psm.3 Using those thresholds, we

utilized a new population density analysis

produced by Oak Ridge National Laboratory to do

a coarse-screen analysis of the likely impacts of

the current population densities on future forest

management (Dobson and others 2000). We

combined these data with a national coarse-scale

map of land ownership and land cover to identify

where forest cover was likely to coincide with

increased population density and where private

lands were most involved. The results indicate that

significant areas of the South are at risk of losing

the ability to manage forest lands for production

forestry. That conclusion has been fortified by the

Southern Forest Resource Assessment, which

forecasts that urbanization will continue to expand

in the South at the rate of around 1.1 million acres

per year until 2020 (Wear and Greis 2002).

3

 Wear, D.N.; Liu, R.; Foreman, M. 1996. The effects of

population growth on timber management and inventories

in Virginia. [Number of pages unknown]. On file with:

Southern Research Station, Forestry Sciences Laboratory,

3041 Cornwallis Road, Research Triangle Park, NC 27709.
13

NEW APPROACHES TO NEW REALITIES

I

f there is to be a healthy, viable, sustainable

forest resource in the South through the 21st

century, what does it need? And how can forest

science contribute to that need? There may be

several ways:

1. Help define and promote sustainable forestry

in all its different expressions

There are many programs emerging to

promote sustainable forestry. Most will,

it appears, have some sort of certification

linkage, where the land management is

audited by an independent third party and

some sort of product mark tells consumers

that the wood products they purchase

have come from a sustainably managed

forest. This is a new movement, marked

by a full share of controversy and

complication as different systems compete

to win the attention of both forest owners

and the public. My advice—do not get

caught in the competition. It, in itself,

is healthy, as it forces all the systems to

seek improvement. Encourage all these

systems so that a forest landowner,

whether they are a small private owner or

a large corporate owner, can find a system

that fits their needs. When the end result

is better forest management, the name

of the system that brought it about

is inconsequential.

2. Help find ways to reach urban audiences

and help them appreciate the value of

well-managed forests as part of the urbanwildland infrastructure

We must quit thinking of urban areas

as one thing and rural areas as another

(Gordon and others, in press). There

is a continuum of places that make up a

landscape, and without the rural aspects,

the value of many landscapes as a human

habitat is reduced. But unless urban

people value rural landscapes, including

rural forests, those rural landscapes will

disappear under the invisible pressures

we have discussed.

3. Bring new forest management techniques

into the urban-wildland intermix

Urban people will appreciate and tolerate

forest management more when that forest

management is sensitive to their lifestyle

needs. No longer can forest managers

handle their land as if nobody is watching.

The truth is, most places, lots of people

are watching. And they are not uncritical.

They expect forest managers to create

situations, views, and environmental

impacts that are acceptable. And the

definition of “acceptable” is somewhat

fluid. Expectations rise.

So forest science cannot rest on the many

laurels it has created in the 20th century.

The questions coming up are equally, if not

more, difficult, and the public pressure to

“get it right” will steadily increase. The

amount of good forest land available for

sustainable management is decreasing

while the need for forest products and

services—both timber and nontimber—

is rising. The margin for error is declining.

The need for a vibrant, growing forest

science in the South has never

been higher.

LITERATURE CITED

AF&PA. 2001. SFI 2001 6th annual progress report on the

sustainable forestry initiative (SFI)SM program. Washington,

DC. [Not paged].

Bennett, H.H. 1939. Soil conservation. New York: McGrawHill. 993 p.

Bennett, H.H.; Chapline, W.R. 1928. Soil erosion: a national

menace. USDA Circ. 33. Washington, DC: U.S. Department

of Agriculture. 36 p.

Chase, Stuart. 1936. Rich land, poor land. New York:

Whittlesey House. 361 p.

Clepper, Henry. 1975. Crusade for conservation: the centennial

history of the American Forestry Association. Washington,

DC: American Forests. 92 p.

Dobson, Jerome E.; Bright, Edward A.; Coleman, Phillip R.

[and others]. 2000. LandScan: a global population database

for estimating populations at risk. Photogrammetric

Engineering & Remote Sensing. LXVI (7). [Not paged].

Fernow, B.E. 1896. Facts and figures regarding our forest

resources briefly stated. USDA Circ. 11. Washington, DC:

U.S. Department of Agriculture. 8 p.

Gordon, John C.; Sampson, R. Neil; Berry, Joyce K. [In press].

The challenge of maintaining working forests at the WUI.

Gainesville, FL: University of Florida.

Liu, R.; Scrivani, J.A. 1997. Virginia forest land assessment.

Charlottesville, VA: Virginia Department of Forestry. 18 p.

+ appendices.

MacCleery, Douglas W. 1992. American forests: a history of

resiliency and recovery. FS–540. Washington, DC: U.S.

Department of Agriculture, Forest Service. 58 p.

Pinchot, Gifford. 1967. The fight for conservation. Seattle:

University of Washington Press. 152 p.

Chapter 2.

 Yesterday, Today, and Tomorrow
Southern Forest Science:

Past, Present, and Future

Looking Back

14

Plair, T.B.; Spillers, A.R. 1960. Forestry on the farm. In:

Clepper, Henry; Meyer, Arthur B., eds. American forestry:

six decades of growth. Washington, DC: Society of American

Foresters: 240–250.

Powell, Douglas S.; Faulkner, Joanne L.; Darr, David R. [and

others]. 1993. Forest resources of the United States, 1992.

Gen. Tech. Rep. RM–234. Ft. Collins, CO: U.S. Department

of Agriculture, Forest Service, Rocky Mountain Forest and

Range Experiment Station. [Number of pages unknown].

Sampson, R. Neil. 1981. Farmland or wasteland: a time

to choose. Emmaus, PA: Rodale Press. 422 p.

Sampson, R. Neil. 1985. For love of the land. League City,

TX: National Association of Conservation Districts. 338 p.

Sampson, R. Neil; DeCoster, Lester A. 1997. Public programs

for private forestry: a reader on programs and options.

Washington, DC: American Forests. 100 p.

Sedjo, Roger. 1991. Forest resources: resilient and serviceable.

In: Frederick, Kenneth D.; Sedjo, Roger A., eds. America’s

renewable resources: historical trends and current

challenges. Washington, DC: Resources for the Future:

81–120.

Smith, W. Brad; Sheffield, Raymond M. 2000. A brief overview

of the forest resources of the United States, 1997. An

overview of the 1997 RPA data. www.fs.fed.us. [Date

accessed unknown].

Society of American Foresters. 2001. Membership profile,

2001. Bethesda, MD. [Not paged].

Steen, Harold K. 1976. The U.S. Forest Service: a history.

Seattle: University of Washington Press. 356 p.

Thorne, S.; Sundquist, D. 2001. New Hampshire’s vanishing

forests: conversion, fragmentation and parcelization of

forests in the Granite State. Report of the New Hampshire

Forest Land Base Study. Concord, NH: Society for the

Protection of New Hampshire Forests. 153 p.

U.S. Census Bureau. 1990. 1990 census of population

and housing. Washington, DC: U.S. Census Bureau.

www.census.gov. [Date accessed unknown].

U.S. Department of Agriculture, Forest Service. 1958.

Timber resources for America’s future. For. Resour.

Rep. 14. Washington, DC. 713 p.

U.S. Department of Agriculture, Forest Service. 1988.

The South’s fourth forest: alternatives for the future.

For. Resour. Rep. 24. Washington, DC. 512 p.

U.S. Department of Agriculture, Forest Service. 2000. 1997

RPA: assessment of the Nation’s forests. Washington, DC.

[Number of pages unknown].

U.S. Department of Agriculture, Natural Resources

Conservation Service. 2001. Summary report: 1997 national

resources inventory. Washington, DC. www.nrcs.usda.gov.

[Date accessed unknown].

Wear, David N.; Greis, John G., eds. 2002. Southern forest

resource assessment: summary report. Gen. Tech. Rep.

SRS–54. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southern Research Station. 103 p. http://

www.srs.fs.fed.us/sustain/report/summry/summary.pdf.

[Date accessed unknown].

Williams, Michael. 1989. Americans and their forests: a

historical geography. Cambridge: Cambridge University

Press. 599 p.

Yarnell, Susan L. 1998. The Southern Appalachians: a history

of the landscape. Gen. Tech. Rep. SRS–18. Asheville, NC:

U.S. Department of Agriculture, Forest Service, Southern

Research Station. 45 p.

Zimmerman, Elliot. 1976. A historical summary of State and

private forestry in the U.S. Forest Service. Washington, DC:

U.S. Department of Agriculture, Forest Service, State and

Private Forestry. 119 p.
15

Chapter 3.

Southern Forest Resource

Conditions and Management Practices from

1900–1950: Benefits of Research

James P. Barnett1

Abstract—The vast harvest of the native forests

of the South in the 19th and early 20th centuries

created a great need for reforestation and

silvicultural knowledge. An emphasis on forestry

research that changed the face of the South

began with the establishment of the Southern

and Appalachian Forest Experiment Stations in

1921. Working under primitive conditions, early

researchers provided the information that was

used to restore the southern forests. A key to this

success was the interaction and cooperation of

workers in universities, State service, Federal

service, and forest industry.

INTRODUCTION

A

lthough southern pines were the basis for the

oldest forest industry in America, the forests

of the Southern United States were little

influenced by humans until the mid-19th century.

Longleaf pine (Pinus palustris Mill.) was the

focus of the early lumber business in the South—

primarily for export. A decline in the supply of

longleaf pine in the Carolinas was noted about

1860. However, intensive harvesting of this species

continued to spread westward across the South

throughout the early 1900s. As the harvesting

of the 90 million acres of mature longleaf stands

moved westward, the development of railroad

logging continued to increase the efficiency of

harvesting. Thus it is not surprising that in the

west gulf region the supply of seed trees became

insufficient to regenerate the species. Across the

southern Coastal Plain, loblolly pine (P. taeda L.)

began to naturally regenerate cutover longleaf

pine sites. However, many millions of acres of

forest land in both the mountains and Coastal

Plains had already been converted to agriculture.

Much of this land was found to be unsuitable for

row crops and was abandoned. Other large areas

of cutover lands that were not converted to

agriculture needed reforestation. This cutover

land was considered by many as open rangeland

and was heavily grazed by cattle and hogs.

These activities further increased the difficulty

of reforestation. The rebuilding of the forest

resource had become a major challenge as

well as a silvicultural opportunity.

This chapter describes the initiation and the

scope of forest research in the South through the

World War II era. Because there is a great deal

of information about the postwar period, it is

necessary to limit the scope of the paper to the

earliest part of the period. The objectives of

the paper are to provide a sense of the research

environment during the period, to describe the

major scientific accomplishments of the period,

and to identify some of the scientists who

contributed to these accomplishments.

THE NEED FOR MANAGEMENT

G

eorge W. Vanderbilt was early to recognize

the need for reforestation of cutover land,

and hired Gifford Pinchot as a forester for

his Biltmore Estate near Asheville, NC. Dr. Carl

Schenck, who replaced Pinchot in 1885, established

the first scientifically based forestry school in

this country on the Biltmore Estate. Through

his school and influence, Dr. Schenck became

one of the founders of modern American forest

management, and the Biltmore Forest School

became known as the cradle of scientific forestry

in America.

Northern investors came into the South

following the Civil War. Late in the 1880s, they

purchased land inexpensively and built mills

for processing timber. For example, the Great

Southern Lumber Company in Bogalusa, LA, ran

four 8-foot band saws at full speed for more than

two decades, producing 1 million board feet of

lumber every 24 hours (Kerr 1958).

Late in the post-Civil War period while lumber

production in the South was at an all-time high,

a few farsighted individuals began to work on

a reforestation program that would provide for

a continuing forest resource. In 1913, Henry

Hardtner, who became known as the “father of

forestry in the South,” established plots on the

first reforestation reserve in Urania, LA, to 1

 Chief Silviculturist, U.S. Department of Agriculture Forest

Service, Southern Research Station, Pineville, LA 71360.
Southern Forest Science:

Past, Present, and Future

Looking Back

16

support and guide pine reforestation (Wheeler

1963). Hardtner, as President of the Urania

Lumber Company, placed 25,719 acres of his

cutover forest lands under a reforestation contract

with the State of Louisiana. It was Hardtner’s

belief that cutover lands offered long-term

opportunities for profit (Maunder 1963). William

G. Greeley, Chief Forester of the U.S. Forest

Service, remarked that even by 1920 neither

foresters nor lumbermen had any real concept

of the reproductive vigor of logged-over forests,

or of how the growth rate was increasing as young

trees replaced old forests (Maunder 1963). In

recognition of this situation, a Cut-Over Land

Conference of the South held in New Orleans in

1917 promoted the sensible use of cutover lands

in which forestry, farming, and grazing all had

a place in the economic use of forest lands.

ESTABLISHMENT OF RESEARCH PROGRAMS

T

he need for additional research was becoming

apparent in 1915 when Samuel T. Dana of the

U.S. Forest Service, in an effort to identify

problems that needed study, established large

plots on Hardtner’s reserve. In 1917, the Yale

School of Forestry started sending its graduating

classes to Urania for 3 months of practical

training. This program continued for several

decades. Students under the direction of Professor

H.H. Chapman established longleaf pine thinning

and fire plots as well as other related studies

(Wheeler 1963). The early results of Chapman’s

Urania studies were summarized in “Factors

Determining Natural Regeneration of Longleaf

Pine on Cutover Lands in LaSalle Parish,

Louisiana” (Chapman 1926).

In 1921, the Forest Service of the U.S.

Department of Agriculture established the

Southern and Appalachian Forest Experiment

Stations at New Orleans, LA, and Asheville, NC,

respectively. The Southern Forest Experiment

Station (Southern Station) was primarily

responsible for research in the southern pine

types (from South Carolina to east Texas), and

the Appalachian Forest Experiment Station

(Appalachian Station) for the mountain hardwood

types. The two research stations employed about

two-thirds of the professional foresters working

in the Southern United States. Although these

foresters (Forbes, Hine, Shivery, Hadley,

and Wyman of the Southern Station and

Frothingham, McCarthy, Korstian, and Haasis

of the Appalachian Station) worked under

primitive conditions and with annual budgets

of < $20,000 per station, they accomplished

some remarkable things. A few other pioneering

researchers joined the stations in the midtwenties, but little expansion of the program

occurred until Congressional passage of the

McSweeney-McNary Forest Research Act of

1928. Passage of this act signaled a general

appreciation of the need for forestry research

efforts to deal with the many problems resulting

from the large-scale harvesting of the native

forests of the Southern United States.

Prior to World War II, there was little forestry

research in the South apart from the programs

established by the Federal Government. Notable

exceptions were programs at the Biltmore

Estate at Asheville, NC, and the Yale School

of Forestry’s training program at Urania, LA.

Forestry programs at other universities in the

South were just being established.

SUCCESSES OF EARLY RESEARCH

Reforestation

B

y conservative estimate, 13 million acres

(about 10 percent) of southern forest land

were in need of planting as late as 1954

(Wakeley 1954). The technology needed to

undertake this massive effort was developed

in the 1920s and 1930s with meager resources.

Reforestation research began to flourish when

Philip Wakeley arrived at the Southern Station

in 1924 and was assigned to the Bogalusa, LA,

substation, which was supported by the Great

Southern Lumber Company. Following a visit to

the thriving forestry project of the Urania Lumber

Company, the Great Southern Lumber Company

had initiated an historic planting program in 1920.

The company planted 800 acres with loblolly pine

seeds sown on ridges made with mule and plow.

The success of this first large-scale commercial

planting was the impetus for experimentation and

observation that resulted in greatly improved

technology (Heyward 1963b).

With help from Great Southern Lumber

Company personnel, Philip Wakeley developed

successful nursery production and outplanting

techniques. Wakeley’s collaborative research

with Mary Nelson, Plant Physiologist, of the

Southern Station (Nelson 1938) and Lela Barton

of the Boyce Thompson Institute (Barton 1928)

was critical to development of the needed

understanding of pine seed testing, treating, and

storing technology. J.K. Johnson, Great Southern

Lumber Company forester and one of the Nation’s

first industrial foresters, supplied the labor and

planting stock for many of the experiments. An
17

outstanding result was the publication “Artificial

Reforestation in the Southern Pine Region,” which

has guided pine planting for the entire South

since the Civilian Conservation Corps (CCC)

days (Wakeley 1935a). This 1935 publication

became the basis of an expanded version “Planting

the Southern Pines,” which was published after

the war and became the primer for reforestation

in the South (Wakeley 1954).

Reforestation research was transferred from

Bogalusa to Alexandria, LA, during the CCC

period with establishment of the Forest Service’s

Stuart Nursery at nearby Pollock. With the help

of CCC crews, nearly two-thirds of a million

seedlings were outplanted in research tests on the

Palustris Experimental Forest and surrounding

Kisatchie National Forest (Wakeley and Barnett,

in press).

A colorful individual who made a unique

contribution to the development of reforestation

technology was F.O. (Red) Bateman, Chief Ranger

of the Great Southern Lumber Company. Bateman

had no formal training, but between 1921 and

1936, he made notable contributions to early firefighting practice and fire suppression work. He

also developed the details of the first successful

large-scale nursery and associated planting

technology for the southern pines (Wakeley

1941, 1976). Wakeley (1976) said he was “one

of the greatest silviculturists the South has

known” and “thousands of acres of Great

Southern’s plantations, and in a real sense,

most of the pine plantations in the South, stand

as a monument to his genius.”

In cases where some remnant seedlings or

stands remained, the research R.R. Reynolds

conducted at the Crossett Experimental Forest

provided management guidelines for the use of

uneven-aged and selection methods. This research

program became recognized nationally and

was an early example of a partnership between

forest industry and Government research

(Reynolds 1951).

Fire

The effect of fire in forests was a matter

of great interest and controversy among early

foresters. In 1916, results of observations in

Henry Hardtner’s reserve were published

in the Louisiana Conservation Commission

biennial report (Wheeler 1963). The findings

are summarized as follows: (1) fires occurring

from December 1 to March 1 are not destructive

to longleaf pine; (2) fire will kill shortleaf pine

(P. echinata Mill.) seedlings < 4 years of age,

but not after that age; and (3) although longleaf

seedlings will survive a fire, they will not survive

damage by hogs.

Based on his observations at Urania, Professor

Chapman of Yale advocated the use of fire in

longleaf stands. He stated that fire controlled

brown-spot needle disease (Mycosphaerella

dearnessii Barr.) and promoted early height

growth (Wakeley and Barnett, in press). Research

station researchers did not agree with Chapman’s

conclusions. The Southern Station’s study of

a 1928 wildfire in an 800-acre longleaf pine

plantation of the Great Southern Lumber

Company indicated that brown-spot would quickly

reinvade longleaf plantations, but that Chapman

was correct in his contention that fire benefited

initiation of longleaf pine seedling growth.

Professor Chapman’s research changed the

prevailing opinion that all fire was bad. Chapman

strongly supported the use of fire in longleaf pine

reforestation and management, stating that “. . .

prohibition of use of controlled fire will effectively

exterminate this species in the region described”

(Chapman 1941).

During the 1930s, other fire studies resulted in

a tentative fire danger meter for the longleaf-slash

pine (P. elliottii Engelm.) type. George Waltner,

sociologist, and Dr. John Shea, psychologist, were

contracted to study the forest fire-starting motives

of local residents (Wheeler 1963). Dr. Shea

reported that many of those who started fires

craved excitement in “an environment otherwise

barren of emotional outlets” (Kerr 1958).

Forest Survey

Early surveys of forest resources were

mandated by Congress. In 1930, Congress

appropriated funds to begin a forest survey of

the southern hardwood region. “The Trees of the

Bottom Lands of the Mississippi River Delta

Region,” by John Putman and Henry Bull (1932),

was issued as the first in the Southern Station’s

Occasional Paper series. This publication was well

received and later led to the establishment of the

station’s bottomland hardwood research center

at Stoneville, MS.

The Southern Forest Survey was authorized by

the McSweeney-McNary Act and began in 1931.

I.F. “Cap” Eldredge assumed direction of this

survey at the Southern Station and significant

resources were allocated to the work. Beginning in

1934, a series of releases established the value of

the effort. New releases were eagerly awaited, and

Chapter 3.

 1900–1950: Benefits of Research
Southern Forest Science:

Past, Present, and Future

Looking Back

18

these became the basis for the pulp industry’s

move into the South (Wheeler 1963). By the end

of 1942, the Southern Forest Survey had “gridironed the States from South Carolina and part

of Tennessee south and west to the western

boundaries of the southern trees, and 53 releases

had been issued, which in turn were reworked into

formal State reports issued from the Government

Printing Office” (Wakeley and Barnett, in press).

This was a tremendous task (more than 215 million

acres were inventoried) and its results provided

the basis for the development of forest industry

across the South.

Hardwood Management

Early hardwood research was focused at the

Appalachian Station’s Bent Creek Experimental

Forest, which was established in 1925 on a portion

of land that the Forest Service purchased from

George Vanderbilt. Most of the land purchased

from Vanderbilt became the Pisgah National

Forest, but a portion was set aside for the

experimental forest. Earl Frothingham and F.W.

Haasis assumed responsibility for experimental

tests established by Pinchot and Schenck on

Vanderbilt’s Biltmore Estate. Jesse Buell

arrived in the mid-1920s and initiated studies to

determine how the cutover areas of the Southern

Appalachians could be managed. Buell published

information dealing with silvicultural practices

needed to manage hardwoods, and with Margaret

Abell published reports of methods for estimating

future volumes of Appalachian hardwoods and

the effect of fire on hardwood quality (Buell 1928,

Buell and Abell 1935). Fire was found to play a

significant role in the introduction of heart rot in

hardwoods (Haig 1946). Margaret S. Abell, for

many years the only woman to be employed as

a professional forester by the Forest Service,

was stationed at Bent Creek during the 1930s.

There was little other hardwoods research in

the South before the World War II period. The

Southern Station was not allowed to conduct

hardwood research before late 1928 when the

State of Louisiana provided $5,000 for the salary

and expenses of G.H. Lentz of New York State

College of Forestry, assisted by John Putman,

to begin an economic survey of the hardwood

situation in Louisiana.

Insects and Diseases

In 1925, the Bureau of Entomology established

a small insectary at Bent Creek in the Appalachian

Station and assigned R.A. St. George to breed and

observe generation after generation of such

“public enemies” as the southern pine beetle

(Dendroctonus frontalis Zimmermann). T.E.

Snyder of the Southern Station began to publish

information about the influence of environmental

factors on the development of southern pine beetle

populations in the mid-1930s (Snyder 1935).

At Bogalusa, Wakeley (1935b) worked out

the life history of the Nantucket pine tip moth

(Rhyacionia frustrana Comstock) in 1927–28,

a significant accomplishment since he had little

entomological training.

Brown-spot needle blight was a major disease

affecting longleaf pine seedlings in nurseries and

after outplanting. At the suggestion of Dr. Carl

Hartley of the Bureau of Plant Industry in

Washington, DC, Wakeley initiated a study

evaluating the use of the fungicide Bordeaux as a

potential control. The tests were very successful,

and a Bordeaux mixture became the standard

spray treatment for brown-spot. The assignment

of Paul V. Siggers to the Southern Station in 1928

to conduct research on brown-spot needle blight

and fusiform rust (Cronartium quercuum

f. sp. fusiforme) began a period of significant

accomplishment. His research culminated in

papers such as “The Brown-Spot Needle Blight

of Longleaf Pine” (Siggers 1932) and “Weather

and Outbreaks of the Fusiform Rust of Southern

Pines” (Siggers 1949). Siggers (1940) also

proposed the name “little-leaf disease of pines”

for the diseased condition of shortleaf pine in

northcentral Alabama.

The valuable chestnut [Castanea dentata

(Marsh.) Borkh.] was eliminated from the

Appalachian forests by the blight caused by

Endothia parasitica (Murrill) Anderson

& Anderson. The blight swept southward

and westward into the forests of the Southern

Appalachian Mountains in the 1920s effectively

eliminating the species from these forests

(Frothingham 1924). Studies were established to

determine how long the dead trees would be useful

as sources of tannin and pulpwood. It was found

that their insect-and-disease-resistant wood would

ordinarily be useful for about 30 years after death

of the trees (Haig 1946).

Products

An early problem experienced in the use of

second-growth lumber was the rapid development

of a blue stain fungus that greatly reduced the

value of unseasoned (not kiln dried) lumber.

Ralph Lindgren reported in 1928 and 1929 that
19

treatment of lumber with ethyl mercuric chloride

eliminated the blue stain problem (Wheeler 1963).

Lindgren’s accomplishment had a great impact

on the forest products industry. Within 2 years,

the results were applied in over 200 pine and

hardwood mills across the country and were being

put into use abroad (Lindgren and Verrall 1950).

Another early effort focused on improvements

to chipping for resin production in the naval stores

industry. Len Wyman was assigned to a substation

in Stark, FL, in 1921. Wyman’s work changed the

gum naval stores industry across the South. He

worked effectively with industry to reduce the size

of the chipping streak. This reduction resulted in

a substantial saving in labor and in tree mortality

and also increased considerably the length of time

a tree could be worked (Wakeley and Barnett, in

press). To increase production of gum naval stores

for war needs, the station intensified experiments

with chemical stimulation, and in a few years

again revolutionized naval stores techniques by

introducing developments in this field. As oldgrowth stands suitable for chipping were cut, the

stumps resulting from harvesting were distilled

for naval stores products (Kerr 1958).

In 1937, the South had a total of 38 pulpmills

in operation or under construction. Much of the

credit for the rapid expansion of pulping southern

wood goes to Dr. Charles Herty (Heyward 1963a).

Herty served as head of the Department of

Chemistry at the University of North Carolina and

was elected president of the American Chemical

Society in 1915. He became enthralled with the

prospect of producing newsprint from southern

pines and established a laboratory (Industrial

Committee of Savannah, Inc.) in Savannah, GA,

to evaluate pulping technology. He traveled widely

to promote the use of second-growth timber as a

source of pulp for newsprint. His showmanship

and genius for publicity developed confidence

in the potential to produce paper from southern

pine pulp.

Mensuration and Statistics

One of the earliest studies undertaken by

the Southern Station made use of temporary

sample plots in even-aged, second-growth stands

throughout the South. The data obtained were

compiled into normal volume, stand, and yield

tables for unmanaged second-growth loblolly,

shortleaf, longleaf, and slash pines. The tables

were published in 1929 as Miscellaneous

Publication 50 of the U.S. Department of

Agriculture (U.S. Department of Agriculture,

Forest Service 1929). They were used widely and

contributed greatly to an understanding of the

growth potential of the four principal southern

pines and the practical forest management of the

pine types (Wakeley and Barnett, in press). This

publication was long out of print and copies were

virtually museum pieces when it was reprinted as

a result of customer demand in the 1970s.

A number of spacing and thinning studies were

established with both pines and hardwoods. Early

on, there was no replication in these or any other

studies. Nevertheless, they did begin to provide

good management guidelines. With the assignment

of Roy Chapman to the Southern Station in 1927,

practical statistical techniques began to be more

widely applied. Chapman was assigned to train

under Francis X. Schumacher for 3 years and

developed a friendship with R.A. (later Sir Ronald)

Fisher, one of the founders of modern statistics,

whose published works and personal advice did

much to shape Chapman’s and the station’s

scientific direction (Wakeley and Barnett,

in press).

Genetics and Tree Improvement

In 1922, Professor H.H. Chapman published

his remarkable treatise on studies establishing the

existence of a natural hybrid between longleaf and

loblolly pine, Sonderegger pine (P. x sondereggeri

H.H. Chapm.) (Chapman 1922). He named the

hybrid after V.H. Sonderegger, who was then

Louisiana State Forester.

In 1929, Wakeley performed the first controlled

hybridization of southern pines, a cross of longleaf

and slash pine (Wakeley 1981). He also established

the first provenance test of southern pine. Planted

in 1926–27 and remeasured at 15 years of age,

loblolly pine from four different seed sources

showed a striking range in wood production

(Wakeley 1944). Because of the detailed original

descriptions, the 23 acres of these early

experimental plantings became a valuable asset

in forest genetics research. This research was

aggressively pursued by a number of organizations

after World War II and in 1954 led to the founding

of the Southern Institute of Forest Genetics on

the Harrison Experimental Forest.

Watersheds

H.G. Meginnis reported to the Southern Station

in 1929 and began work in an erosion control

program. The effort was centered in northern

Mississippi where 35 percent of two counties was

covered with gullies as much as 100 feet deep

Chapter 3.

 1900–1950: Benefits of Research
Southern Forest Science:

Past, Present, and Future

Looking Back

20

(Wakeley and Barnett, in press). Meginnis

quantified erosion and runoff by soil type,

compared use of planted pines and other species

for erosion control, and applied litter and organic

matter to paired watersheds. His research

established the protocols used across the South

for managing eroded soils and restoring

productivity (Meginnis 1933).

Charles Hursh began work at the Appalachian

Station in 1926 and led research dealing with

erosion control and methods of stabilizing road

banks and abandoned agricultural land. In

1932, plots were established at the Bent Creek

Experimental Forest near Asheville, NC, to study

surface runoff from five representative types of

forested or agricultural cover, and an infiltrometer

was used successfully with artificial rainfall.

These studies led to recognition of the need to

establish complete watershed instrumentation

to provide for continuous measurements of stream

flow and precipitation. As a result, the Coweeta

Experimental Forest was established near

Franklin, NC, in 1933. Appalachian Station

Director C.L. Forsling required a period of

standardization of the gauged watersheds. An

intensive program of weir construction began in

1934, and a network of 56 standard rain gauges,

numerous ground-water wells, and meteorological

stations was created. By 1939, calibration of

watersheds had progressed enough so that

experimentation could begin (Stickney and others

1994). Early studies documented the harmful

effects of mountain farming, woodland grazing,

and unrestricted logging on soil and water

resources (Douglass and Hoover 1988).

Forest Economics

In July 1929, the Southern Station began

work in forest economics, having received a

special appropriation of $22,800 from Congress

for initiating investigations of financial aspects

of timber growing in the southern pine region.

E.L. Demmon, Director, in summarizing the

early evaluations in “Economics of Our Southern

Forests,” stated that the value of forest resources

in the South greatly exceeded that of any other

agricultural crop (Demmon 1937).

The War Years

During the early to mid-1940s, younger men

left for military service and older ones spread

themselves thin to make measurements and

consolidate gains. Many experimental forest

areas were closed, and most regular research

was postponed for the duration of the war. The

stations had major programs for gathering

information about supplies, output, and

requirements of forest products for defense

for the War Production Board. The stations also

assisted war agencies in establishing cork oak

(Quercus sober L.) plantations, developing Russian

dandelion (Taraxacum kok-saghyz Rodin) and

goldenrod (Oligoneuron Small) plants for rubber

production, freeing airfields of undesirable

vegetation, measuring infiltration rates of soils

in connection with airfield drainage, camouflaging

military installations, evaluating priority requests

for logging and milling equipment, improving

fire protection of critical areas, and controlling

termites and decay in wood structures

(Wheeler 1963).

At the end of World War II (1946), the

boundaries of the two stations were realigned.

The Southern Station assumed responsibility for

research in Tennessee and relinquished Georgia

and Florida (South Carolina had already been

transferred to the Appalachian Station) to the

newly formed Southeastern Forest Experiment

Station (formerly the Appalachian Forest

Experiment Station).

SIGNIFICANCE OF THIS RESEARCH

With only a handful of professional foresters,

and despite little technical support and

primitive working conditions, forestry in the

South has made tremendous gains. Researchers

developed reforestation techniques, studied and

began to understand the role of fire in forests,

began surveys of the southern forests that led to

development and expansion of forest industries,

and learned how to control important insect

pests and diseases. They also developed an

understanding of the importance of the use

of statistical design and the value of tree

improvement, developed methods for controlling

soil erosion, and improved the efficiency of

producing forest products. In < 20 years, they

provided the basic management guidelines that

have resulted in great progress in the restoration

of the South’s forest lands. In more recent

decades, forestry research has refined this

knowledge and filled gaps in it. Researchers

continue to build on the strong scientific

understanding provided by those who preceded

them. As a result, our restored southern forest

lands are now a primary economic resource in

all Southern States.
21

LESSONS LEARNED

H

ow did our early research professionals with

limited resources accomplish so much in a

relatively short period of time? Dedication,

cooperation, and teamwork were characteristics

of the early research program. Not only did the

individuals support each other’s efforts, they

developed excellent relationships with scientists

in universities and other agencies, as well

as with foresters in forest industry and State

organizations dedicated to solving problems

common to all organizations. Wakeley and

Barnett (in press) quote a passage in Macaulay’s

“Horatius” that describes their attitude:

For Romans in Rome’s quarrel

Spared neither goods nor gold

Nor son nor wife nor limb nor life

In the brave days of old.

Then none was for the party.

Then all were for the State.

Then the rich man helped the poor

And the poor man loved the great.

Then lands were fairly portioned.

Then spoils were fairly sold.

The Romans were like brothers

In the brave days of old!

CONCLUSIONS

T

he South’s forests were largely overexploited

during the early 1900s. Vast areas had been

converted to agriculture and then abandoned

or were harvested and not regenerated. The

knowledge needed for the restoration of these

forests was sorely lacking. The establishment of

the Southern and Appalachian Stations in 1921

provided the impetus to develop the scientific

base for this restoration effort. An important

component of this effort was interaction and

cooperation with those in universities and forest

industry that had the same intense motivation

to restore the southern forest lands.

ACKNOWLEDGMENTS

I

 wish to express my respect for Philip C.

Wakeley. His counsel to me early in my career,

keen observations of nature, and dedication to

forest science has been an inspiration to me during

my research endeavors. I have drawn heavily

from Wakeley’s document “A Biased History of

the Southern Forest Experiment Station Through

Fiscal Year 1933,” which is now in press, for this

historical perspective of the initiation of forestry

research in the South.

My thanks to Dr. Anna Burns of Louisiana

State University at Alexandria and Drs. Ron

Schmidtling, Cal Meier, and David Loftis of the

Southern Research Station for constructive peer

reviews of early drafts of the manuscript.

LITERATURE CITED

Barton, L.V. 1928. Hastening the germination of southern

pine seeds. Journal of Forestry. 26: 774–785.

Buell, Jesse H. 1928. What can be done with Southern

Appalachian cut-over areas? Southern Lumberman.

133(1734): 211–212.

Buell, Jesse H.; Abell, Margaret S. 1935. A method for

estimating future volumes of partially cut stands in the

Southern Appalachians. Tech. Note 11. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Appalachian

Forest Experiment Station. 76 p.

Chapman, H.H. 1922. A new hybrid pine (Pinus palustris x

Pinus taeda). Journal of Forestry. 20: 729–734.

Chapman, H.H. 1926. Factors determining natural

reproduction of longleaf pine on cutover lands in LaSalle

Parish, Louisiana. Bull. 16. New Haven, CT: Yale University

School of Forestry. 44 p.

Chapman, H.H. 1941. Note on the history of a stand of pine

timber at Urania, LA. Journal of Forestry. 39: 951–952.

Demmon, E.L. 1937. Economics of our southern forests. Occas.

Pap. 59. New Orleans: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station. 10 p.

Douglass, J.E.; Hoover, M.D. 1988. History of Coweeta. In:

Swank, W.T.; Crossley, D.A., Jr. Ecological studies: forest

hydrology and ecology at Coweeta. New York: SpringerVerlag: 18–31. Vol. 66.

Frothingham, E.H. 1924. Some silvicultural aspects of the

chestnut blight situation. Journal of Forestry. 22: 861–872.

Haig, I.T. 1946. Anniversary report 1921-1946, twenty-five

years of forest research of the Appalachian Forest

Experiment Station. Asheville, NC: U.S. Department

of Agriculture, Forest Service, Southeastern Forest

Experiment Station. 71 p.

Heyward, Frank. 1963a. Charles Herty—Mr. pulp and paper.

Forests & People. 13(1): 28–29.

Heyward, Frank. 1963b. Col. W.H. Sullivan—Paul Bunyan

of Louisiana forestry. Forests & People. 13(1): 20.

Kerr, Ed. 1958. History of forestry in Louisiana. Baton Rouge,

LA: Louisiana Forestry Commission, Office of the State

Forester. 55 p.

Lindgren, R.M.; Verrall, A.F. 1950. Fungus control in

unseasoned forest products. Forest Farmer. 9(5): 53–54.

Maunder, Edwood. 1963. Henry Hardtner signs the first

reforestation contract. Forests & People. 13(1): 56–57,

124–125.

Meginnis, H.G. 1933. Tree planting to reclaim gullied lands

in the South. Journal of Forestry. 31: 649–656.

Chapter 3.

 1900–1950: Benefits of Research
Southern Forest Science:

Past, Present, and Future

Looking Back

22

Nelson, Mary L. 1938. Preliminary investigations on dry, cold

storage of southern pine seed. Occas. Pap. 78. New Orleans:

U.S. Department of Agriculture, Forest Service, Southern

Forest Experiment Station. 19 p.

Putman, J.A.; Bull, H. 1932. The trees of the bottom lands

of the Mississippi River Delta region. Occas. Pap. 27. New

Orleans: U.S. Department of Agriculture, Forest Service,

Southern Forest Experiment Station. 207 p.

Reynolds, R.R. 1951. Guide to the Crossett Experimental

Forest. New Orleans: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station. 65 p.

Siggers, P.V. 1932. The brown-spot needle blight of longleaf

pine seedlings. Journal of Forestry. 30: 579–593.

Siggers, P.V. 1940. The little-leaf disease of pines. South. For.

Notes. 31. New Orleans: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station. 2 p.

Siggers, P.V. 1949. Weather and outbreaks of the fusiform

rust of southern pines. Journal of Forestry. 47: 802–806.

Snyder, T.E. 1935. The Ips engraver beetles in the South.

South. For. Notes 18. New Orleans: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment

Station: 1–2.

Stickney, Patricia L.; Swift, Lloyd W.; Swank, Wayne T. 1994.

Annotated bibliography of publications on watershed

management and ecological studies at Coweeta Hydrologic

Laboratory, 1934–1994. Gen. Tech. Rep. SE–86. Asheville,

NC: U.S. Department of Agriculture, Forest Service,

Southeastern Forest Experiment Station. 115 p.

U.S. Department of Agriculture, Forest Service. 1929. Volume,

yield, and stand tables for second-growth southern pines.

Misc. Publ. 50. Washington, DC: U.S. Department of

Agriculture, Forest Service. 202 p.

Wakeley, Philip C. 1935a. Artificial reforestation in the

southern pine region. Tech. Bull. 492. Washington, DC:

U.S. Department of Agriculture, Forest Service. 115 p.

Wakeley, Philip C. 1935b. Notes on the life cycle of the

Nantucket tip moth Rhyacionia frustrana Comst. in

southeastern Louisiana. Occas. Pap. 45. New Orleans:

U.S. Department of Agriculture, Forest Service, Southern

Forest Experiment Station. 8 p.

Wakeley, Philip C. 1941. F.O. Bateman. Journal of Forestry.

39: 950.

Wakeley, Philip C. 1944. Geographic seed source of loblolly

pine seed. Journal of Forestry. 42: 23–33.

Wakeley, Philip C. 1954. Planting the southern pines.

Agric. Monogr. 18. Washington, DC: U.S. Department

of Agriculture, Forest Service. 233 p.

Wakeley, Philip C. 1976. F.O. (Red) Bateman, pioneer

silviculturist. Journal of Forest History. 20(2): 91–99.

Wakeley, Philip C. 1981. Silvicultural research—a perspective.

In: Barnett, J.P., ed. Proceedings of the first biennial

southern silvicultural research conference. Gen. Tech.

Rep. SO–34. New Orleans: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station:1–5.

Wakeley, Philip C.; Barnett, James P. [In press]. Early forestry

research in the South: a personal history. Gen. Tech. Rep.

Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southern Research Station.

Wheeler, Philip R. 1963. The coming of forest research.

Forests & People. 13(1): 66–67, 96, 98–101, 110–111.
23

Chapter 4.

Southern Forest Resource

Conditions and Management Practices from

1950–2000: Benefits of Research

Jacek P. Siry1

Abstract—Over the past five decades, research

progress and implementation have been the

leading factors supporting the rapid development

of southern forestry. The South has become

the leading timber-supplying region in the United

States, taking advantage of a large accumulation

of growing stock and a substantial investment

in intensive, research-based management

treatments. This chapter focuses primarily on

intensive management of planted pine forests.

Plantations commonly receive high levels of all

inputs and are major beneficiaries of research

advances. High plantation growth rates are

essential if our increasing demand for wood is to

be met and if harvest pressure on the remaining

natural forests is to be reduced.

INTRODUCTION

D

uring the first half of the 20th century,

forest researchers established the basic

management guidelines for forest

management in the South. They developed

reforestation techniques, learned how to control

forest fires, carried out surveys of southern forest

resources, learned how to protect forests from

insects and diseases, developed soil protection

techniques, and introduced new technologies that

greatly increased the efficiency of wood products

manufacturing. These achievements were essential

not only for restoring southern forests but also

for making possible their future expansion.

During the second half of the 20th century,

these basic forest management guidelines were

refined on the basis of new knowledge, and more

importantly, many of them were implemented

on a very large scale in the South. Although

this chapter provides a brief overview of major

advances in forestry research, it focuses on

research related to management of planted pine

(Pinus spp.). Research findings have

influenced planted pine management in the

South in important ways.

Over the past five decades, the South has

experienced rapid growth in planted pine area

and productivity. These gains were made possible

in part by research that paved the way for the

development and widespread application of new

technologies including genetic improvement and

application of fertilizers and herbicides. Today

the South is the leading U.S. regional and global

supplier of softwood timber. Extensive forest

management that emphasized the exploitation

of existing resources has been abandoned in the

South and has been replaced by an intensive,

primarily softwood-producing industry propelled

by implementation of research.

OVERVIEW OF SOUTHERN FOREST

RESEARCH AND MANAGEMENT: 1950–2000

T

he contributions to southern forestry

made by forest scientists employed by the

U.S. Department of Agriculture Forest

Service (Forest Service), forestry schools and

departments, forest industries, and other forestry

organizations during the past half-century were

enormous. Scientists developed knowledge and

technologies that constituted an essential basis

for rapid gains in the production of timber and

nontimber goods. Extensive cooperation among

scientists at various organizations and the

combination of research and implementation

made possible by Federal, State, and industrial

programs were of great importance in the

development of southern forestry. The following

brief overview of major research advances in

southern forestry is based largely on Johnston’s

(1989) record of a great history of forestry

research in the South.

Growing demand for wood and research in

forest products manufacturing were important

factors in increasing utilization of southern forests.

Research led to the development of technology for

producing kraft pulps from the wood of southern

pines, and the availability of this technology

resulted in the rapid expansion of the southern

1

 Assistant Professor, University of Georgia, D.B. Warnell pulp and paper industry. New technologies

School of Forest Resources, Athens, GA 30602.
Southern Forest Science:

Past, Present, and Future

Looking Back

24

created new uses for southern pines, increasing

their commercial value and leading to the rapid

development of wood-manufacturing industries.

For example, the development of plywood

technology for southern pines in the 1960s was

followed by the development of a variety of panel

products, such as fiberboard, particleboard, and

oriented strand board. Research also improved

sawmilling efficiency by developing new

equipment and cutting practices that increased

lumber yields, especially from small logs. New

equipment for logging operations, such as tree

harvesters and machines for in-woods chipping,

was also developed.

Increasing demand for small wood coincided

with the exhaustion of convenient supplies from

natural forests and encouraged the development

of pine plantation programs at a time when

land was abundant. Planting programs required

large quantities of good seedlings, effective

site-preparation methods, and protection from

fires, pests, and diseases. Research provided

the knowledge needed to secure seed sources,

establish productive tree nurseries, develop

effective planting methods, and protect forests.

Fire research, for example, helped reduce area

burned and damage caused by wildfire while it

demonstrated the value of controlled burning.

The area burned by wildfire averaged 38 million

acres per year from 1931 to 1935; this was reduced

to about 2 million acres per year by the mid-1960s

(Southern Forest Resources Analysis Committee

1969). This progress permitted large gains in

timber growth and encouraged investment in

timber growing.

Timber management research has always been

important in the South. Forest scientists developed

guidelines for the management of all major species

and forest types in the region. Research provided

better knowledge of silvicultural practices,

vegetation control, soils and fertilizers, and

nutrient cycling. Scientists developed and used

models for analyzing timber growth, yields, and

effects of thinning and other management

practices. Economic research identified promising

investment opportunities and needs, stimulating

the development of intensive pine management.

By demonstrating that even small owners can

benefit from intensified management, economic

research helped establish a number of forest

assistance programs. Further, researchers

analyzed present and future timber supply

conditions. Biometric and economic research

combined with advanced forest surveys provided

better information about forest inventory,

growth, mortality, and utilization, helping guide

investments in land acquisition and intensive

management to support industrial expansion.

Hardwood forests, which cover more than

half of the South’s forest land, also attracted

substantial research efforts. Research provided

guidelines for regeneration and culture of

hardwood forests in both natural and planted

stands. Plantations of cottonwood (Populus spp.),

sycamore (Platanus occidentalis L.), and yellowpoplar (Liriodendron tulipifera L.) have shown

much promise of increased productivity. But there

has been much less research and investment in

hardwood management than in pine management

(Hicks and others 2001, Kellison 2001). One reason

for this is that hardwoods have been in ample

supply, and returns from managing them actively

have generally been insufficient to justify widely

applied intensive silviculture.

Research produced hardwood pulp technology,

however, and the availability of this technology

has fostered increased utilization of southern

hardwoods and has provided incentives for

expanded research in their silviculture and natural

regeneration. As available hardwood inventories

dwindle and hardwood prices and management

returns increase, more research effort and

applications can be expected. Trials of early

silvicultural interventions in natural hardwood

stands show promise of providing substantial

and profitable growth increases (North Carolina

State Hardwood Research Cooperative 2001).

Finally, growing demand for forest recreation

and wildlife stirred considerable research

interest in these areas. For example, scientists

investigated the impact of intensive forest

management practices on recreation opportunities

and developed guidelines for use of thinning and

prescribed burning to improve the quality and

increase the availability of wildlife habitat.

Growing environmental concerns led to expanded

investigation of the impact of forest management

practices on water quality and to the development

of best management practices.

Substantial research efforts had a great impact

on the character of southern forests. In the 1950s,

southern forests were managed primarily with

low intensity in natural stands. More than 7 million

acres of the region’s timberland were nonstocked

and in need of regeneration. Only 2 million

acres were in planted pine forests. The area

planted in pine had expanded to about 30 million
25

acres by 1997, along with rapidly intensifying

management and increasing productivity

(Smith and others 2001).

Planted pine management has changed

southern forestry dramatically. While the South

accounts for only 40 percent of the Nation’s forest

land area and 22 percent of its softwood growing

stock, it supplies 64 percent of all softwood

harvested in the United States. Today, the South’s

pine plantations account for nearly 19 percent of

the world’s area of fast-grown industrial wood

plantations. While the region’s planted and natural

pine forests represent < 3 percent of global

conifer forest cover, they supply nearly 19 percent

of global industrial softwood roundwood harvests

(Food and Agriculture Organization of the United

Nations 2002, Smith and others 2001). No other

region or country in the world supplies more

softwood timber than the U.S. South.

INTENSIVE PLANTED PINE MANAGEMENT

IN THE 1990S

P

ine plantations are managed much more

intensively now than they were formerly,

when management consisted primarily of

site preparation and planting. Today’s intensive

management relies heavily on the widespread

application of research-based approaches

such as the planting of genetically improved

seedlings and the application of fertilizers and

herbicides. The management of industrial pine

plantations is a particularly good example of

the contribution of intensive management

technologies to greater growth because such

management involves high levels of all inputs

and because industrial plantations benefit

greatly from research advances.

The results of a forest industry management

survey2 were used to estimate current operational

results of intensive management of planted

pine. The survey was designed by the American

Forest and Paper Association’s Resource Planning

Act (RPA) Task Group and was used to collect

data about industry land and management

practices for use in the 2000 RPA Timber

Assessment. The survey covered the 13 Southern

States and collected data on tree planting,

genetic improvement, control of vegetation

and stocking, nutrition, thinning, harvest age,

and the management of future stands on leased

and company-owned forest land. Participating

companies accounted for 16.3 million acres of

planted pine, or about 90 percent of pine plantation

area in forest industry ownership in the region.

The survey provided the basis for the

development of five management intensity classes

(MIC) for planted pine (Siry and others 2001).

MIC 1 represents traditional management

consisting only of site preparation and planting.

MIC 2 represents low intensity that involves site

preparation and planting of genetically improved

seedlings. MIC 3 describes moderate intensity

with fertilizer application. MIC 4 stands for high

intensity in which herbicide use is added to MIC 3

treatments. Finally, MIC 5 represents very high

intensity, with multiple applications of fertilizers

and herbicides.

Table 4.1 presents total and average annual

yields of merchantable wood for planted pine on

medium-quality sites at age 25. Total yields range

from about 2,700 cubic feet per acre for MIC 1

to nearly 4,600 cubic feet per acre for MIC 5

(Siry and others 2001). These total yields translate

into average annual growth rates ranging from

109 cubic feet per acre for MIC 1 to 183 cubic feet

per acre for MIC 5. These data show that very

intensive management can produce almost

70 percent more volume than traditional

management produces.

2

 Goetzl, A. 1998. AF&PA southern forest management

intensity survey: data summary and survey results.

[Number of pages unknown]. On file with: American

Forest and Paper Association, 1111 Nineteenth Street,

NW, Suite 800, Washington, DC20036.

Table 4.1—Intensively managed planted pine growth

and yield data (wood volume) for medium sites and

25-year rotation

Management Total wood Average annual

intensity class yield at age 25 growth rate

ft3/ac ft3/ac/yr

MIC 1 - traditional 2,716 109

MIC 2 - genetics 3,135 125

MIC 3 - MIC 2 + F 3,433 137

MIC 4 - MIC 3 + H 4,033 161

MIC 5 - MIC 4 + 2nd

 F and H 4,587 183

MIC 1 = site preparation and planting; MIC 2 = site preparation

and planting of genetically improved seedlings; MIC 3 = moderate

intensity with fertilizer application; MIC 4 = high intensity in which

herbicide use is added to MIC 3 treatments; MIC 5 = very high

intensity with multiple applications of fertilizers and herbicides;

F = fertilization; H = herbicide application.

Chapter 4.

 1950–2000: Benefits of Research
Southern Forest Science:

Past, Present, and Future

Looking Back

26

INTENSIVE TIMBER GROWING METHODS

Genetic Improvement

T

he forest industry survey indicates that use of

genetically improved growing stock increases

wood volume by about 15 percent, or nearly

420 cubic feet per acre at age 25. Such increases

were made possible by genetic research and

industrial tree improvement programs that

began in the South as early as the 1950s.

Genetic improvement of pines was focused

on site adaptability, disease tolerance, growth

rates, tree form, and wood quality (Zobel 1974).

Rapidly expanding planting programs demanded

large quantities of pine seed, and this demand

stimulated the establishment of seed orchards.

Most tree improvement effort was directed at

slash (Pinus elliottii Engelm.) and loblolly pine

(P. taeda L.), but some emphasis was also put

on longleaf pine (P. palustris Mill.). Continued

interest in genetic improvement has resulted

in the establishment of industry-university

cooperative tree improvement programs at

Texas Agricultural and Mechanical University,

the University of Florida, and North Carolina

State University. Hardwood tree improvement

work began after the work on pines started and

later subsided. Very few hardwood plantations

were established.

The 42 years of loblolly pine improvement

studies carried out by the North Carolina

State University-Industry Cooperative Tree

Improvement Program have yielded 7- to 12-

percent volume increases in trees grown from

first-generation seed orchards (Zobel and

Talbert 1984). Second-generation tree breeding

produced wood volume gains of 17 to 30 percent

over unimproved seeds (Li and others 1998).

Genetically improved trees also display improved

stem quality and fusiform rust (Cronartium

quercuum f. sp. fusiforme) infection rates that

are reduced by as much as 25 percent. The history

of tree improvement research in the South is

summarized in Zobel and Sprague (1993).

Fertilization

Pine fertilization research trials were

established in the South as early as the mid-1940s.

Foresters, however, showed little interest in this

work until 20 years later, when remedial

fertilization of slash pine forests growing on

phosphorus-deficient sites produced spectacular

responses (Pritchett and Comerford 1982). On

such sites, phosphorus fertilization resulted in

great volume and value gains, as phosphorus

shortages virtually precluded the establishment of

viable pine plantations. Volume gains were as high

as 50 cubic feet per acre per year for up to 20

years in response to a single phosphorus addition

at or near planting.

Growing interest in forest fertilization led in the

late 1960s to the establishment of industry-funded

research cooperatives at the University of Florida

and North Carolina State University. The Florida

program focused on slash pine and the North

Carolina program on loblolly pine. Both programs

researched possibilities of increasing growth by

applying fertilizers and developed technologies

for operational use of fertilizers in forestry.

Fertilizers are now applied at planting, at

young ages, and in midrotation. Two of the most

commonly supplied nutrients are phosphorus and

nitrogen. Fertilization at planting is frequently

aimed at ameliorating phosphorus deficiencies,

while applications in established stands usually

supply additional nitrogen and phosphorus.

Operational data from the forest industry survey

indicate that midrotation applications of 25 pounds

per acre of phosphorus and 200 pounds per acre

of nitrogen increase yield by 400 cubic feet per

acre, or 15 percent per application, for a 25-year

rotation. To date, fertilizers are applied almost

exclusively in intensively managed pine

plantations; they have been used very little

in hardwood stands.

Scientists have moved to investigate

interactions of fertilization with other silvicultural

treatments that may influence nutrient availability,

the effects of applications of nutrients such as

potassium and boron, and interactions between

nutrient additions and tree resistance to pests

and diseases (Allen 1983, Ballard 1984). Presently,

research focuses on developing more integrated

approaches to site nutrient management

(Allen 2001).

Herbicide Application

The largest problem in intensive pine culture in

the South is the difficulty of controlling hardwoods

that invade pine sites (Waldstad 1976). Natural

succession, when accompanied by reduced fire

frequency and increased pine harvesting, favors

hardwood development. Hardwood competition

can overtop young pines and greatly reduce the

availability of moisture, nutrients, and sunlight to

pine trees, resulting in higher seedling mortality

and slower growth (Clason 1993, Glover and

Zutter 1993).
27

Foresters did not initially consider herbaceous

competition a major impediment to pine growth,

so early forest herbicide research focused on

control of hardwoods in pine stands (Gjerstad

and Barber 1987). Research developed rules for

herbicide selection, dosage, timing, and application

methods. In the 1980s, research trials indicated

that herbaceous vegetation does compete with

young pine seedlings and that its elimination can

increase survival and growth rates of young pines

(Creighton and others 1987, Lauer and others

1993, Yeiser and Williams 1996, Zutter and Miller

1998). This has led to the development of

approaches for controlling both woody and

herbaceous vegetation.

The forest industry survey indicates that

control of vegetation has the largest impact on

wood volume growth. In MIC 4, woody plant

treatment in year 1 increased yield by about 600

cubic feet per acre at age 25. In MIC 5, herbicides

were applied twice; herbaceous plant treatment

at planting was followed by woody plant treatment

in year 3. These applications increased yield by as

much as 750 cubic feet per acre at age 25, or by

nearly 28 percent over untreated stands.

Herbicides are used for site preparation before

stand establishment, release from hardwood and

herbaceous competition in young stands, and

timber stand improvement in midrotation.

Herbicide treatments gain popularity because

they are cheaper, more effective, and easier to

apply than others. To date, herbicide research

and applications have been limited primarily to

intensively managed southern pines, but there

is growing interest in herbicide applications in

hardwood forests. Fitzgerald (1980) provides

an historical overview of herbicide research

and use in forestry.

RETURNS FROM INTENSIVE MANAGEMENT

While intensive management can greatly

increase pine growth and yield, investment

returns will largely determine how widely it

will be applied and how intensive it will become.

The costs of genetically improved seedlings,

herbicides, fertilizers, and other treatments

increase the total management costs per acre.

However, production rates may increase

sufficiently to decrease average production

costs and justify increased investment in timber

management. Real rates of return for planted pine

management now vary from nearly 10 percent

(MIC 1) to 12 percent (MIC 5) (Siry and others

2001). Net present values and soil expectation

values also indicate that intensive management

offers attractive returns—values associated with

very intensive management (MIC 5) are more

than 1.6 times higher than returns associated with

traditional management (MIC 1). The increased

returns reflect higher production values resulting

from increases in timber volume and quality.

These returns are sufficient to justify investment

in improved timber management practices on a

large scale.

EXTENT OF INTENSIVE FOREST

MANAGEMENT PRACTICES

F

orest Service, Forest Inventory and Analysis

(FIA) data spanning from 1982 to 1999 show

increases in rates of harvesting, planting and

natural regeneration, timber stand improvement,

and chemical application in the South (Siry 2002).

Intensive management is practiced primarily in

planted pine forests, where most planting, site

preparation, fertilizer and herbicide use, and

thinning occur. The FIA data also indicate that

natural pine, oak (Quercus spp.)-pine, and upland

and bottomland hardwood forests are managed

with considerably lower intensity.

Several authors have presented survey

information that shows what forest management

practices are employed, and how extensively they

are employed, by important owner groups in the

South (Moffat and others 1998, Siry and Cubbage

2001, Siry and others 2001). Table 4.2 summarizes

this information and information provided by other

sources that are described subsequently.

Table 4.2—Extent of intensive forest management

practices in the South

Management Forest land

Forest type treatment area

million acres

Planted pine Genetic

 improvement 26

 Fertilization 11

 Herbicide use 11+

Natural pine Some practices 6

Oak-pine such as fertili- 3

Upland hardwood zation and/or 5

Bottomland thinning were

 hardwood or will be used 3

Chapter 4.

 1950–2000: Benefits of Research
Southern Forest Science:

Past, Present, and Future

Looking Back

28

In the South, only about 4 million acres of pine

plantations were established under management

consisting only of site preparation and planting

of seedlings that were not genetically improved.

Pine plantations on 26 million acres were

established using genetically improved seedlings.

Today, virtually all seedlings of pine species

planted in the South are genetically improved

(Li and others 1998).

Data collected by the North Carolina State

Forest Nutrition Cooperative (2001) indicate that

almost 1.6 million acres of southern pine stands

were fertilized in 2000. Since 1969 slightly more

than 11 million acres have been fertilized in the

South. This area is estimated to exceed the sum

of forest acreage fertilized in the rest of the world.

While midrotation fertilization is most common,

the area fertilized at planting and at young tree

ages is increasing. If current planting trends

continue and pine plantations are fertilized at least

twice throughout the rotation, then the area on

which fertilizers are applied will at least double.

It is difficult to obtain reliable information

about the extent of herbicide use. However,

herbicides have a long history of use in pine

management, and it is clear that they are

employed widely in the South. Pesticide-use

patterns (Michael 2000) indicate that nearly

1 percent of forest land in the United States

is treated annually. If these patterns hold for

herbicide use in the South, approximately

2 million acres of southern forest land receive

herbicide treatments each year.

Natural pine, oak-pine, and hardwood stands

are often managed custodially on an even-aged

basis and receive no treatments. Management

at higher levels of intensity, which includes the

application of treatments such as fertilization or

thinning of even-aged stands to promote growth

and quality, is limited. Survey results indicate

that only about 6 million acres of existing natural

pine forests have received or are scheduled to

receive such treatments. Following harvesting,

natural pine forests are often replanted with pine

seedlings and managed more intensively. Growthpromoting treatments have been applied on or

are planned for 3 million acres of oak-pine forests

and 8 million acres of hardwood forests.

EFFECTS OF INTENSIVE FOREST

MANAGEMENT PRACTICES

T

able 4.3 compares the growth rate of very

intensively managed planted pine (MIC 5)

with empirical rates used in the Subregional

Timber Supply (SRTS) model, which analyzes and

forecasts southern timber supply conditions (Abt

and others 2000). The empirical growth-and-yield

estimates employed are based on FIA data. Across

all sites, management intensities, and owners in

the South, growth of planted pine averages 94

cubic feet per acre per year for a 25-year rotation

(Abt and others 2000, Siry and others 1999).

Industrial yields are from about 15 percent (for

MIC 1) to 95 percent (for MIC 5) above current

SRTS model values for average sites at age 25.

This implies that very intensive planted pine

management (MIC 5) has the potential to double

recently observed production rates. Very

intensively managed pine plantations (MIC 5)

can grow more than twice as fast as natural pine

stands, which grow at an average rate of 72 cubic

feet per acre per year.

An analysis based on FIA data indicates that

average annual pine growth in the South (for

planted and natural stands combined) increased

by 22 percent from the mid-1980s to the mid-1990s

(Siry and Bailey 2003). This increase added about

26 million tons per year to the region’s softwood

production. The analysis also indicates that pine

growth increases are positively correlated with

the area of intensively managed pine plantations.

Table 4.3—Growth rates (wood volume) for

intensively managed planted pine (MIC 5)

and SRTS-FIA forest management types

Average annual

Management type growth rate

ft3/ac/yr

Planted pine (MIC 5) 183

SRTS-FIAa

Planted pine 94

Natural pine 72

Oak-pine 51

Upland hardwood 42

Bottomland hardwood 42

MIC 5 = very high intensity with multiple applications of

fertilizers and herbicides; SRTS = Subregional Timber

Supply model; FIA = Forest Inventory and Analysis.

a

 SRTS-FIA data are average values for all site indexes.
29

From the mid-1980s to the mid-1990s, planted

pine area increased by 7 million acres to about

30 million acres while natural pine area decreased

by 5 million acres to 33.5 million acres.

Growth rates for oak-pine and hardwood forests

are substantially lower than those for planted

pine. Oak-pine growth rates average about 51

cubic feet per acre per year for 60-year rotations.

Growth rates for hardwood forests are still lower,

averaging 42 cubic feet per acre per year for 60-

year rotations. Growth rates in very intensively

managed pine plantations (MIC 5) are nearly

3.6 times as great as average oak-pine growth

rates and nearly 4.4 times as great as average

upland and bottomland hardwood growth rates.

Intensively managed plantations of hybrid poplars

and other hardwood species grow rapidly, but

their area is very small.

DISCUSSION AND CONCLUSIONS

P

lanted pine forests account only for about

15 percent of southern timberland but for

a much greater share of softwood growth

and harvests. The SRTS model indicates that

pine plantations now account for about 56 percent

of total softwood growth in the South (Prestemon

and Abt 2002). The model indicates that pine

plantations will overtake natural pine forests

in supplying softwood timber between 2000

and 2005 as planted trees mature and reach

merchantable size. Within a decade, harvests

from pine plantations will amount to nearly a

third of total softwood and hardwood timber

production in the South.

The ability of pine plantations to supply the

majority of softwood harvests is a clear indication

of their great relevance for sustainable wood

supply and conservation of the remaining natural

forests. Since the area of commercial timberland

is expected to remain relatively stable, existing

forests will have to be utilized more intensively

to satisfy timber demand. Intensive management

of planted pine makes it possible to grow more

wood on less land. Plantation success means

that harvesting pressure on natural forests, oldgrowth forests, and environmentally sensitive

areas will be reduced as timber demand is met

primarily by wood grown on plantations. This

creates new opportunities for conservation of

the natural forests.

Ever-increasing demands for wood and

other forest products and services imply that

the productivity of pine plantations will have to

continue to grow. Progress made in recent years

indicates that this is entirely possible. Today’s

challenge is to develop approaches that combine

various intensive management treatments in

ways that generate the maximum returns in

an environmentally responsible manner.

More frequent and more widespread application

of fertilizers and herbicides could increase

productivity substantially. Nearly half of the

South’s forest acreage would benefit from timber

stand improvement, including herbicide use

(Waldstad 1976). Nutrient-deficient sites are also

widespread, and even sites previously thought

not to be nutrient deficient can benefit from

fertilization (Allen 2001). There is also abundant

evidence that appropriate repeated fertilizer

applications produce additional response from

forest stands (Ballard 1984). For example, annual

fertilization and multiple applications of herbicides

resulting in total control of competing vegetation

on loblolly pine research sites in Georgia produced

annual growth rates ranging from 325 to 490 cubic

feet per acre (Borders and Bailey 2001). Such

growth rates are about twice as high as current

rates in intensively managed industrial pine

plantations (MIC 5).

Genetic improvement of trees appears to hold

the greatest long-term promise. Although realized

genetic-related gains in wood volume have not

averaged more than 30 percent to date, the best

second-generation loblolly families have shown

volume increases of up to 66 percent and improved

stem straightness, wood quality, and resistance to

diseases (Li and others 1998). Continuing progress

in breeding technologies, including controlled mass

pollination and vegetative propagation (rooted

cutting and tissue culture), and eventually genetic

engineering of trees, promises even greater gains

in wood volume and quality. The limits of such

gains are today largely unknown.

Over the past five decades, forest research

has developed powerful new timber-growing

technologies. The use of genetically improved

seedlings, fertilizers, and herbicides in intensively

managed pine plantations now results in growth

rates that are nearly twice as high as those

associated with traditional management consisting

of site preparation and planting. Wider and more

intensive application of growth technologies now

in use could double or triple the current

production levels for intensively managed pine.

Such increases will be essential for sustaining and

expanding southern timber harvests while limiting

pressures on the remaining natural forests.

Chapter 4.

 1950–2000: Benefits of Research
Southern Forest Science:

Past, Present, and Future

Looking Back

30

ACKNOWLEDGMENTS

I

 thank James Barnett, Jerry Michael, Mike

Rauscher, and two anonymous reviewers for

their helpful comments.

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Southern Forest Resources Analysis Committee. 1969. The

South’s third forest-how it can meet future demands. [Place

of publication unknown]: Southern Forest Resources

Analysis Committee. 111 p.

Waldstad, J. 1976. Weed control for better southern pine

management. Weyerhaeuser For. Pap. 15. Hot Springs,

AR: Weyerhaeuser Company, Southern Forestry Research

Center. 44 p.

Yeiser, J.; Williams, R. 1996. Planted loblolly pine survival and

growth responses to herbaceous vegetation control.

Southern Journal of Applied Forestry. 20(1): 53–57.

Zobel, B. 1974. Increasing productivity of forest lands through

better trees. The S.J. Hall lectureship in industrial forestry.

Berkeley, CA: University of California, School of Forestry

and Conservation. 20 p.

Zobel, B.; Sprague, J. 1993. A forestry revolution: the history

of tree improvement in the Southern United States. Durham,

NC: Carolina Academic Press. 160 p.

Zobel, B.; Talbert, J. 1984. Applied forest tree improvement.

New York: John Wiley. 505 p.

Zutter, B.; Miller, J. 1998. Eleventh-year response of loblolly

pine and competing vegetation control to woody and

herbaceous plant control on a Georgia flatwoods site.

Southern Journal of Applied Forestry. 22(2): 88–95.

Chapter 4.

 1950–2000: Benefits of Research

33

Chapter 5.

The Southern Forest Resource Assessment:

What We Learned

David N. Wear

and John G. Greis1

Abstract—The Southern Forest Resource

Assessment was initiated in the spring of 1999

to address broad questions concerning the status,

trends, and possible future of southern forests.

The overall objective of the assessment was to

develop a thorough and objective description

of forest conditions and trends in the South, and

to present it in a way that would help the public

understand a complex and dynamic resource.

Findings of the assessment highlight the forces of

change at work in southern forests and potential

ecological and economic implications.

INTRODUCTION

T

he forests of the Southeastern United

States are diverse and dynamic. They

have been utilized heavily since European

settlement, and their current condition reflects

a long history of land use. At the beginning of

the 20th century, a 100-year period of intensive

agricultural exploitation gave way to a period

of forest recovery and growth. In the last quarter

of the 20th century, however, timber harvesting

and land development for urban uses increased

substantially. As a result, questions have emerged

regarding the health, productivity, and ultimately

the sustainability of the South’s forests and the

benefits they provide.

The Southern Forest Resource Assessment

(SFRA) was initiated in the spring of 1999 to

address broad questions about the status, trends,

and potential future of southern forests (fig. 5.1).

The assessment was chartered by southern offices

of the U.S. Department of Agriculture Forest

Service, the U.S. Environmental Protection

Agency, the U.S. Fish and Wildlife Service, and

the Tennessee Valley Authority; and it was

conducted in collaboration with State agencies

represented by the Southern Group of State

Foresters and the Southeastern Association of

Fish and Wildlife Agencies.

Approximately 89 percent of the South’s forests

are held by private owners. The assessment was,

thus, a somewhat unusual undertaking, one in

which Government agencies evaluated the status

and future of a largely private sector of the

economy. For this reason, the assessment was

chartered as an information-gathering activity.

The overall objective of the assessment was to

develop a thorough and objective description of

forest conditions and trends in the South, and to

present this description in a way that would help

the public understand a complex and dynamic

resource situation. This role, i.e., monitoring

change at a broad scale and describing cumulative

change, has been described by the National

Research Council (1998) as a logical and important

role for Government in the area of private forestry.

1 Research Forester and Project Leader, U.S. Department

of Agriculture Forest Service, Southern Research Station,

Research Triangle Park, NC 27709; and State and Private

Forestry Environmental Program Specialist, U.S.

Department of Agriculture Forest Service, Southern

Region, Atlanta, GA 30367, respectively.

Figure 5.1—The

region addressed

by the Southern

Forest Resource

Assessment (Wear

and Greis 2002a).
Southern Forest Science:

Past, Present, and Future

Looking Back

34

A descriptive assessment such as the SFRA

can be used to highlight the major dynamics and

uncertainties at play within a region’s forested

ecosystems, thereby focusing public discourse

on the changes affecting these systems and on

associated policy issues. Because the assessment

has only recently been completed, it is too early

to examine its effectiveness on such terms. In this

chapter, we (1) examine the process that was used

to structure and to conduct the assessment, (2)

discuss the major findings of the assessment,

and (3) examine the implications of these findings

for the conduct of forestry and forest science in

the South.

ASSESSMENT PROCESS

T

he SFRA can be viewed as an exercise in what

Lee (1993) has called “civic science.” It was

designed to be accessible to the public and to

utilize considerable amounts of public input in the

definition of issues, scope, analysis protocols, and

review of outputs. It was designed to provide the

public with a platform of current knowledge and

data upon which to discuss and debate current

and future issues regarding the South’s forests.

Defining the Questions

The first step in conducting the assessment

was to define the set of questions that would be

addressed. This was done by employing an

approach utilized in the Southern Appalachian

Assessment (Southern Appalachian Man and

the Biosphere 1996). Initial sets of concerns

were drafted by a group of about 75 experts

from participating Government agencies using a

workshop format and organized around 4 broad

topic areas: (1) social-economic, (2) terrestrial

ecosystems, (3) water and aquatic ecosystems,

and (4) forest conditions and health. These

concerns were then summarized into an initial

set of questions that provided a framework for

organizing public input.

To gather public input on the initial questions,

two public workshops were conducted at each of

five locations in the South. At each location, one

workshop was conducted in the afternoon and

the other in the evening. After presenting the

audience with an overview of the project’s

objectives and general design, the group was

divided into four separate sessions, each

concentrating on one of four broad topic areas.

In each of these sessions, the participants

were encouraged to raise any concerns and

issues that they felt needed to be addressed

by the assessment, and these were recorded and

compiled. The initial questions were also posted

on the SFRA Web site, and public comments

were taken by mail and email.

The comments were then compiled using

content-analysis software and were posted on

the SFRA Web site. The assessment leaders

then developed a preliminary set of questions

that would address public concerns to the extent

practical and consistent with overall objectives.

Each of these questions was linked to the set of

major concerns (labeled subpoints) on which the

question was based. The questions summarized

input from more than 700 participants, and the

subpoints recorded the details of the major points

summarized by the question. These preliminary

questions and subpoints were posted on the SFRA

Web site and were again reviewed by the public.

The additional review input was used to further

refine the questions.

Conducting the Analysis

Each question defined the objective of an

analysis of a resource or social issue related

to southern forests. An individual scientist or

analyst was selected by the SFRA planning team

to conduct the analysis for each question. These

individuals, who were called question managers,

constituted the assessment team. The team was

convened for an initial meeting with the objective

of assessing the feasibility of and methods for

addressing each question. Because of the potential

for overlap of the analyses, question managers

discussed their questions and approaches in

groups organized by broad categories. Members

of the public participated in these discussions

and provided input regarding the question

managers’ interpretation of the questions and

their proposed approaches.

Following the initial assessment team meeting,

question managers prepared study plans that

were posted on the SFRA Web site. These

were also subject to public review and were

eventually finalized. Analysis of the questions

then commenced. Each question manager had the

latitude to consult with various colleagues or to

build a research team to conduct the work. During

the course of the analysis, two assessment team

meetings were held to discuss progress, share

data, and to coordinate work to the extent possible.

These meetings were also open to the public and

were structured in a way that allowed the team to

conduct its business and to solicit public input and

reactions to the team’s efforts.
35

Preliminary findings were not discussed in open

assessment team meetings. This was consistent

with a policy that findings would not be released

without careful peer review. A closed meeting of

the assessment team was held in January 2001 to

discuss preliminary findings and to improve the

coordination of analyses of related questions.

Reviewing the Results

Answers to the questions were drafted as

separate reports and summarized in a summary

report, which compiled and synthesized major

findings from the separate reports. These findings

were then evaluated using a peer-review process

patterned after standard approaches utilized

by scientific journals. For each report, a number

of experts (peers) were selected to review and

comment on the accuracy and adequacy of the

response. These experts were selected from a set

of candidates provided by members of the public,

by agency representatives on the planning team,

and by the question managers themselves. A

single-blind peer-review procedure was employed;

i.e., the identities of the reviewers were kept

confidential in order to obtain candid remarks on

the reports. Reviews were compiled and returned

to the authors of each report for consideration as

they revised their chapters. The assessment

coleaders managed the peer-review process,

including evaluation of responses to reviews

by the authors.

After the individual chapters were revised to

address comments raised through peer review,

they were released as draft reports. The draft

reports (including the draft summary report)

were published via the SFRA Web site, and the

draft summary report was printed for distribution

upon request (Wear and Greis 2001).

Draft reports were reviewed over a 90-day

comment period. Comments were taken via a

threaded message board organized by individual

reports on the SFRA Web site and through the

mail. As public comments were received, they were

classified by specific points raised, were organized

by chapter, and were distributed to authors.

Comments were used to revise reports and to

identify additional relevant data and research

that had a bearing on the assessment questions.

Final products of the assessment include a

technical report that addresses the individual

questions (Wear and Greis 2002b) and the final

summary report (Wear and Greis 2002a). They

also include all data used in the analyses and

complete documentation of data sources and

analyses. The availability of data and

documentation is intended to enable the public

to conduct followup analysis and to replicate the

work conducted within the assessment. The data

could also provide a benchmark for future

updating of assessment findings.

ASSESSMENT FINDINGS

T

he full suite of assessment findings is

contained in the 23 technical reports that

constitute the chapters of the SFRA technical

report (Wear and Greis 2002b). The following

sections summarize the major findings described

in the SFRA summary report.

FORCES OF CHANGE

We evaluated the forces of change that have

reshaped and continue to reshape forests in

five categories: (1) land markets, (2) timber

markets, (3) social institutions, (4) biological

factors, and (5) physical factors. While each of

these areas defines important mechanisms of

change, it is clear that they interact in their effects

on southern forests. In each area, we examined the

history and status of these changes and, where

possible, explicitly projected potential changes.

Land Markets

From 1700 to 1930, land clearing for agriculture

and timber production completely restructured

southern ecosystems. Clearing for agriculture

greatly diminished the area of forested wetlands,

especially in the Mississippi River Alluvial Valley.

Agricultural uses reached their zenith in the late

19th century. Wholesale land abandonment then

set the stage for a long period of forest

reestablishment and growth.

Since the 1940s, there has been little net

change in forest area in the South. Current forest

area is 214 million acres, or about 91 percent of

that recorded in 1907. However, there have been

large offsetting changes: forest land has been

converted to urban and agricultural uses in some

places, and agricultural land has been converted

to forest in others.

Forecasting models indicate that 12 million

forest acres will be lost to urbanization between

1992 and 2020. An additional 19 million acres are

forecast to be developed between 2020 and 2040.

Forecasts also indicate conversion of 10 million

acres from agricultural land to forest between

1992 and 2020 and conversion of another 15 million

acres by 2040. Most forest loss is expected to be

Chapter 5.

What We Learned
Southern Forest Science:

Past, Present, and Future

Looking Back

36

Removals volume (billion cubic feet)

12

10

8

6

4

2

0

Year

1952 1954 1958 1963 1967 1972 1976 1986 1991 1996

Saw logs

Veneer logs

Pulpwood

Fuelwood

All other products

concentrated in the eastern part of the South;

forest gains are expected to be concentrated

in the west.

Timber Markets

Between 1952 and 1996, the South’s timber

production more than doubled. Its share of U.S.

production increased from 41 to 58 percent, and

its share of world production increased from

6.3 to 15.8 percent. The region now produces

more timber than any other country in the

world (fig. 5.2).

The South produces a great variety of timber

products, including softwood saw logs (28 percent

of the region’s wood output), softwood pulpwood

(25 percent), and hardwood pulpwood (16 percent).

Since 1952, hardwood pulpwood has experienced

the greatest increase in product share, growing

from 3 to 16 percent of output.

Models of timber markets forecast that timber

production in the United States will increase by

about one-third between 1995 and 2040. Nearly

all of this growth will come from the South, where

production is forecast to increase by 56 percent

for softwoods and 47 percent for hardwoods.

Social Institutions

Laws, regulations, and Government programs

are frameworks within which forests are managed.

The current income tax code has mixed impacts on

long-term investments in forestry, and inheritance

taxes encourage owners to liquidate or split up

forest properties.

Forest incentive programs that subsidize the

planting of trees have had a long and successful

history in the South. More recent programs focus

on multiple values obtained from forests.

Direct regulation of forestry is limited in the

rural South. However, in areas that are becoming

more urbanized, a proliferation of local regulations

has markedly affected land use and forest

management. The number of such regulations

nearly doubled between 1992 and 2000.

Funding of forest incentive programs is likely

to vary depending on State and Federal priorities.

The expansion of local regulations appears to

be closely linked to population growth and

urbanization. The number of regulations affecting

forest treatments will likely continue to expand

in high-growth areas.

Biological Factors

Native plant diseases and insects affecting

pines have become problematic for forest

managers in the South as the species composition

and configuration of pine forests has changed.

Southern pine beetle (Dendroctonus frontalis

Zimmermann) and fusiform rust (Cronartium

quercuum f. sp. fusiforme) are economically

significant pests.

Nonnative diseases and insects have altered

and continue to alter southern forests, especially

hardwood forests. Chestnut blight {Cryphonectria

parasitica (Murrill) Barr [formerly Endothia

parasitica (Murrill) Anderson & Anderson]}

removed an important canopy species beginning in

the 1930s. Several other species-specific diseases

have been introduced to the South. These include

dogwood anthracnose (Discula destructiva),

oak wilt [Ceratocystis fagacearum (T.W. Bretz)

J. Hunt], and butternut canker (Sirococcus

clavigignenti-juglandacearum). Among the

nonnative insects that have been introduced are

the gypsy moth (Lymantria dispar Linnaeus),

balsam woolly adelgid (Adelges piceae Ratzeburg),

and hemlock adelgid (Adelges tsugae Annand).

Nonnative trees, shrubs, vines, birds, and

mammals are also having large impacts on

southern ecosystems.

The southern pine beetle is expected to

continue to cause substantial economic damage

and ecological change in the South, especially on

heavily stocked nonindustrial private and aging

public forests. Multiple nonnative diseases and

insects affecting hardwoods will continue to

spread from the North. Expansion of urban

areas is likely to increase the spread of nonnative

plants and animals and to affect native plant and

wildlife communities.

Figure 5.2—Removals by destination product, southwide,

all species, 1952 to 1996 (Wear and Greis 2002a).
37

300

250

200

150

100

50

0

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Assessment area United States

Population (milion)

Year

Physical Factors

Many southern forest types are fire adapted,

and exclusion of fire has altered their species

composition, flammability, and management.

The reintroduction and continued use of fire

will present challenges as concerns related to

urbanization and air pollution become more

important. The ambient environment influences

forest growth and vigor. Ozone pollution is forecast

to increase by 20 to 50 percent between 1990 and

2025, and growth reductions in southern pines

are expected as a result. Future changes in

temperatures could positively or negatively

affect forest growth and species ranges depending

on the extent of the change and the availability

of moisture. Acid deposition is expected to

significantly impact the region’s forests only

in the Southern Appalachians.

SOUTHERN FOREST CONDITIONS

We also examined the current status and

potential future of various aspects of forest

conditions and the services and direct

benefits that forests provide. We examined

southern forest conditions from four different

perspectives: (1) social and economic systems;

(2) forest area and condition; (3) terrestrial

ecosystems; and (4) water quality, wetlands,

and aquatic ecosystems.

Social and Economic Systems

Social context—The population of the South

has grown faster than the national average (fig.

5.3). As a result, the share of the U.S. population

residing in the South has increased to more than

32 percent. Although population growth occurred

largely in urban areas through 1980, it has now

spread across nearly all southern counties.

The South’s population has also become more

urban. These changes are reflected in values that

have shifted away from a strong commodity

orientation to a more biocentric view.

The South’s population is forecast to continue

growing, both absolutely and in relation to that

of the United States as a whole, thus putting

increasing pressure on forests, especially in

urbanizing areas.

People and forests—Comparisons of the

distribution of population and forests indicate

areas in which access to forests and their benefits

is especially limited. These areas are concentrated

in Florida, in northern Virginia and northern

Kentucky, and along interstate highway corridors

I-85 from Raleigh, NC, to Atlanta, GA; I-65 from

Birmingham, AL, to Nashville, TN; and I-81 from

Chattanooga, TN, to Wytheville, VA.

Forecasts for the period 1992 to 2020 indicate

that there will be outward growth and increased

human impacts on forests surrounding urban

centers such as Atlanta, Nashville, and Charlotte

and along the Atlantic and gulf coasts. These

wildland-urban interfaces have effects on many

forest values.

Wood products—With expansion in forest

production has come an expansion in jobs and

income derived from the wood products industry.

In 1997, timber harvests led to more than 700,000

jobs in the wood products sector and more than

$118 billion in total industry output. Total

economic impacts of these activities were about

2.2 million jobs (5.5 percent of total jobs) and

$251 billion of total industry output (7.5 percent

of industry output).

Timber harvesting and management of timber

production are prevalent in all parts of the region

but are especially concentrated on the Atlantic

and Gulf Coastal Plains.

It is predicted that timber production will

increase most in areas to the north and west of the

traditional timber production core of the South—

that is, into Tennessee, North Carolina, Arkansas,

and western Virginia (fig. 5.4).

Increases in timber harvests are not expected

to deplete inventories, but there is considerable

variability among States and forest types.

Softwood inventories are forecast to increase

gradually between 1995 and 2040. Hardwood

inventories are forecast to expand between 1995

and 2025, but to fall slightly between 2025 and

Figure 5.3—Population, in millions, for the United States and for

the 13 States in the assessment area (Wear and Greis 2002a).

Chapter 5.

What We Learned
Southern Forest Science:

Past, Present, and Future

Looking Back

38

Change in percent

-50 – 6

6 – 66

66 – 146

146 – 258

258 – 453

2040. This reflects forecasts that show hardwood

removals exceeding growth regionally by about

2025, and sooner in some States.

Recreation—Southern forests provide

opportunities for a broad array of recreational

activities. Driven by a growing population and

changes in income and other demographics,

recreational uses of all types have increased.

Recreation is an important source of employment

and income in the South. In 1997, tourism based on

outdoor recreation contributed between 0.64 and

2.88 percent of southern jobs. Recreation-based

tourism on public lands represented 56 percent

of this contribution. Much private land is

unavailable for public recreation, and the trend

is toward less access. Consequently, there is

considerable pressure for increased recreational

use of public lands.

Given current land ownership patterns, there

appears to be limited capacity to expand forestbased recreational opportunities in the South.

Recreational activities on public land are expected

to be increasingly congested, and competition

among various recreation groups will increase.

Quality of life—Forests contribute to quality

of life in several ways. They provide for production

of wealth by supplying wood products and

recreational opportunities, they protect and

enhance environmental quality, and they meet

aesthetic needs.

Changes in the use of forests will affect the

quality of life for local residents. Predicted

increases in harvesting in areas outside the

production core of the South may generate

increased wealth for some persons, but loss of

aesthetic and environmental benefits for others.

This will probably lead to debate about forest uses

in local areas.

Forest Area and Conditions

Forest area and ownership—The South now

has more than 214 million acres of forest land

(fig. 5.5), 60 percent of the total in 1630 and 91

percent of the total in 1907 (fig. 5.6). Forest area

has been relatively stable since the 1970s. Eleven

percent of timberland (21.4 million acres) is

managed by various Government agencies.

The remaining 89 percent is privately owned.

Twenty-two percent of private timberland is

owned by forest industry, 21 percent by farmers,

12 percent by other corporations, and 45 percent

by other individuals.

Ownership is changing with a decrease in forest

industry ownership between the 1980s and 1990s

and an increase in other corporate ownership,

including ownership by timber investment

management organizations.

Total area of forest land is forecast to decline by

only 2 percent between 1995 and 2040. Preliminary

results of the most recent forest inventories

indicate that decreases in forest industry

ownership are continuing.

Broad forest types—While total forest area has

remained relatively constant, the distribution of

forest types changed from the 1950s to the 1990s.

The area of upland forest increased gradually.

The area of lowland hardwood forest declined

somewhat between the 1950s and 1970s but has

leveled off. The area of naturally regenerated

pine stands decreased by about half as the result

of natural succession to upland hardwoods,

harvesting of the pine component, or conversion

to nonforest uses or planted stands following

harvesting. The area in planted pine increased

from about 2 million acres in 1953 to 32 million

acres in 1999. In the 1980s and 1990s, pine

plantations were established on land that

previously supported hardwood or mixed pinehardwood forests (47 percent), natural pine forests

(28 percent), and agricultural fields (25 percent).

The area of pine plantations is forecast to

increase by 67 percent to 54 million acres in 2040

(fig. 5.7). Areas of all other forest types are

Figure 5.4—Forecast percent change in annual softwood

harvest levels, 1995–2040, by survey unit of the Forest

Inventory and Analysis Program of the U.S. Department

of Agriculture Forest Service (Wear and Greis 2002a).
39

Percent forest cover

0 – 20

21 – 40

41 – 60

61 – 80

81 – 100

400

350

300

250

200

150

100

50

1630 1907 1938 1953 1963 1982 1989 1999

Year

Area (million acres)

0

20

40

60

80

100

120

Timberland (million acres)

Planted

pine

Natural

pine

Mixed

oak-pine

Upland

hardwood

Lowland

hardwood

Agriculture

1995 2020 2040

Forest types

expected to decline gradually over this period.

Forests of all types will be lost to urban uses and

gains in acreage in planted pine will come mainly

from planting of agricultural fields.

Landscape structure—Satellite images of forest

cover in the early 1990s indicate areas where

forest is highly contiguous. These areas include

the Blue Ridge Mountains, the Cumberland

Plateau, the Allegheny Mountains, the OzarkOuachita Highlands region, and some coastal

areas. Areas where forest cover is highly

fragmented include the Piedmont, central

Tennessee, and the Ridge and Valley ecoregion.

Population growth and other factors are

expected to make Piedmont forests especially

susceptible to increased fragmentation

through 2040.

Forest inventory—Southern forests accumulated

considerable volumes of timber between the

1950s and 1990s. Inventory grew from 148 to 256

billion cubic feet, reflecting rapid growth of stands

established since the 1930s. Recent inventories

indicate a general slowing in the rate of

accumulation for hardwoods and a leveling off

of accumulation for softwoods.

Forecasts indicate that softwood growth will

overtake and exceed removals by a slight margin

in the next few years. As a result, softwood

inventories are predicted to increase steadily

Figure 5.5—Percent of forest cover by county,

1992 (Wear and Greis 2002a).

Figure 5.6—Forest area in the Southern United States,

1630 to 1999 (Wear and Greis 2002a).

Figure 5.7—Forecast of the area timberland by forest

types, 1995 to 2040 (Wear and Greis 2002a).

Chapter 5.

What We Learned
Southern Forest Science:

Past, Present, and Future

Looking Back

40

between 1995 and 2040. Hardwood removals

are expected to outstrip growth by about 2025.

Hardwood inventories are forecast to peak

in about 2025 and then decline to levels just

exceeding current ones by 2040.

Timberland productivity—Intensive

management has increased southern timber yields.

Yields associated with high-intensity management

can be 65 percent greater than those associated

with standard site preparation and planting, and

more than double the yields from naturally

regenerated forests.

Future productivity is a key determinant

of both future forest conditions and future of

timber market conditions. For example, models

suggest that if anticipated productivity gains

were not realized, more pine plantations would be

established to supply timber products. The effects

of climate change, other environmental change,

and pest-related mortality on productivity are

less certain.

Terrestrial Ecosystems

Abundant forest communities—Upland

hardwood and pine forest types remain plentiful

in the South but are subject to several health

problems. Southern pine beetle has had a greater

economic impact than any forest pest over the

past 30 years. The chain of forest changes begun

by the chestnut blight continues; the latest of these

changes may be a disease complex called oak

decline, which is especially severe in the Southern

Appalachians and the Ozarks.

Southern pine beetle will continue to be an

economically important pest of pine forests.

Epidemics are likely where pines have been

planted outside of their natural range and in

the absence of active management. Spillover

epidemics from public land may continue to be

a problem in the South. The complex of nonnative

insects and diseases affecting hardwoods has

the potential to restructure forests, especially

in the northern part of the region.

Rare forest communities—Many concerns

about southern wildlife and plant species focus

on rare forest communities. Fourteen critically

endangered communities have lost more than

98 percent of their habitat since European

settlement. Most of these communities are in

seven classes: (1) old growth; (2) spruce-fir (Picea

spp.-Abies spp.); (3) wetlands, bog complexes, and

pocosins; (4) bottomland and flood plain forests;

(5) glades, barrens, and prairies; (6) longleaf pine

(Pinus palustris Mill.) forests; and (7) Atlantic

white-cedar [Chamaecyparis thyoides (L.)

B.S.P.] swamps.

Two of the seven classes—old-growth and

spruce-fir forests—are found largely on public

land. The remainder are generally in private

ownership, so their future depends on the

decisions of numerous owners. Spruce-fir appears

to be under the greatest stress—stress caused

mainly by air pollution and a nonnative insect.

Remnant longleaf pine forests are threatened

by land development and fire exclusion.

Effects of land use changes—Urbanization

affects bird populations by fragmenting

or eliminating habitat and by increasing

disturbances. Nonnative animals, for example,

feral cats, dogs, and pigs, influence wildlife

through predation, displacement of native

species, and habitat modification.

Predicted changes in land use may affect bird

species most adversely in the Piedmont, where

population declines are anticipated for neotropical

migrants and forest interior specialists.

Effects of forest management—Forest

management can have important implications

for wildlife. Impacts depend on specific site

conditions and the management practices

employed. Broader landscape patterns can

influence mobile wildlife species. Fragmentation

effects of certain practices are likely to be lower

in heavily forested areas than in areas where

urban and agricultural uses predominate such

as the Piedmont, Interior Low Plateau, and

Mississippi Alluvial Plain. Effects of landscape

configuration and forest management may be

especially important for some species, especially

certain amphibians. Across the South, more

species are threatened by increased isolation

of shrub-scrub and grassland habitats than

are affected by scarcity or fragmentation of

mature forests.

The ultimate future challenge for forest

management is to support the array of grassland,

shrub-scrub, and mature forest species occurring

within the same landscapes.

Wildlife species of concern—Of the 1,208

vertebrate species known to exist in the South,

132 are considered to be of conservation concern

and 28 are classified as critically imperiled.

The South is the center of amphibian biodiversity

in the United States. Fifty-four amphibians

are classified as species of concern, and 19 are

critically imperiled. Areas where the concentration
41

8

23

5

10

11

7

6

13 11

11

26

15

15

of endangered species is high include the Southern

Appalachians, the Atlantic and Eastern gulf coast

flatwoods, the gulf coast marsh and prairie, and

peninsular Florida (fig. 5.8). Loss of habitat is

the primary cause of species endangerment.

Habitat protection will be difficult in view

of the rapid urbanization forecast for the South.

Forestry operations can have impacts on certain

amphibians, especially those that depend on both

wet and upland habitats.

Conservation issues—Public land is relatively

scarce in the South (11 percent of forest acreage)

but plays an important role in conservation of

specific forest types and wildlife species. More

often, the management of private land determines

the future of imperiled species and rare forest

communities. Effective conservation often

requires collaboration, giving rise to multipleowner consortiums.

Although scarce, public land has unique

ecological value because it can provide a

dependable supply of interior forest habitat and

older forests. In areas that are becoming urban,

public tracts can serve as anchors for conservation

strategies pursued by multiple owners. The

effective reintroduction of fire to many forest

ecosystems will remain a critical forest

conservation challenge.

Water Quality, Wetlands, and

Aquatic Ecosystems

Water quality—About 30 percent of the South

has relatively good water quality, 36 percent has

moderate water-quality problems, and 15 percent

has serious water-quality problems. The leading

causes of water-quality impairment have been

siltation, pathogens, and nutrients. Of the 11 major

sources of water-quality impairment, agriculture

and urbanization have ranked highest, with

silviculture ranking next to last. When properly

implemented, best management practices

(BMP) are effective in controlling pollution from

silvicultural activities. Twelve of the thirteen

Southern States have monitored BMP compliance

and reported results. Because different States

employ different survey methods, regional trends

cannot be identified. However, consistency among

States is improving; six States have adopted

similar procedures since 1997.

As timber production increases in the South,

effective BMP implementation will become even

more crucial for protecting water quality.

Wetlands—Approximately 32.6 million acres

of forested wetlands occur in 10 Southern States

(those that constitute the assessment area minus

Virginia, Texas, and Oklahoma). These wetlands

account for 64 percent of the total forested wetland

area in the conterminous United States. Losses

of forested wetlands have been quite widespread,

but have been noticeably concentrated in the

Mississippi Alluvial Valley and the Coastal Plain

of the Carolinas. Rates of loss have declined since

the 1970s, but impacts and functional changes

continue to occur.

Land management practices and urbanization

are expected to continue to alter the function of

wetlands. Wetland restoration efforts will continue,

but their likelihood of success is not clear. Forest

management practices will play an important role

in the persistence of certain amphibian species.

Aquatic species of concern—The South supports

a great diversity of aquatic species. Several

hundred species of concern are found among

the amphibians, mussels, crustaceans, fish, snails,

and aquatic insects of the region. Especially high

numbers of mussel, fish, and amphibian species

are critically imperiled as a result of modification

to aquatic and wetland habitats (fig. 5.9).

For many mussels and certain other species,

declines will continue because of the effects of

essentially irreversible actions such as dam

construction, agricultural conversions, and the

introduction of nonnative species. Many aquatic

species of concern are narrow endemics. The

effects of development and management activities

may be disproportionately large for the small

areas they occupy.

Figure 5.8—Number of terrestrial vertebrates in Southern

States listed as endangered (Wear and Greis 2002a).

Chapter 5.

What We Learned
Southern Forest Science:

Past, Present, and Future

Looking Back

42

North Atlantic

South Atlantic

Florida

Cumberland

Apalachicola

Mobile

Mississippi

Ozark

Sabine

Central Texas

5 5 3

7

49

43

60

30

9

22

4

Rio Grande

DISCUSSION

T

he findings of the assessment led us to some

broad observations regarding the present and

future status of southern forests.

1. The South is an economically, culturally, and

ecologically complex region, and a number of

forces of change are affecting its forests.

2. Urbanization presents a substantial threat

to the extent, condition, and health of forests.

Of the various forces of change, urbanization

will have the most direct, immediate, and

permanent effects on the extent, condition,

and health of forests.

3. The population of the South is growing,

and the social context of forest management

is changing. These changes have implications

for the nature of values and demands that

people place on forests as well as on the uses

of forests.

4. Total forest area will remain stable, but

subregional and compositional changes

will continue. We forecast little net change

in the total area of forests between 1995

and 2040. Losses of forest area to urban

uses are expected to be offset by shifts from

agricultural to forest uses. Urban development

is forecast to be concentrated in eastern

areas, while afforestation of agricultural

land is expected to take place largely in the

western part of the South. Overall, the

southern region will experience a westward

shift in its forest area.

5. Timber production is forecast to expand,

but it is not expected to deplete forest

inventories below current levels. Between

1995 and 2040, softwood outputs will expand

by 56 percent and hardwood outputs by 47

percent. Softwood inventories will continue

to expand throughout that period. Hardwood

inventories will expand until 2025 and then

decline slightly between 2025 and 2040.

6. Investment in pine plantations is forecast to

expand to meet increased softwood demand.

This will have implications for the ecological

characteristics of southern forests. Pine

plantations enhance timber productivity. For

example, planted forests accounted for only

15 percent of timberland, but they contributed

35 percent of annual softwood removals

during the 1980s and 1990s. Increases in pine

plantation acreage could also result in varying

ecological changes, depending on stand origin

and management. These effects are better

documented at the forest stand level than

at a broader landscape scale.

7. Changing patterns of land use and harvesting

will have important effects on the lives of

the people of the South. The wood products

industry now accounts for about 6 percent

of jobs and 8 percent of income in the region.

In some rural parts of the South, these

percentages are much higher and forestrelated industry has represented more than

half of the local base economy. Forests also

contribute to the quality of life in the region

by providing opportunities for recreation,

visual backdrops, and environmental quality.

Forecasts of increasing timber harvests

imply more jobs in the wood products sector.

However, abrupt changes in forest conditions

could lead to increased costs for some people,

increased benefits for others, and increased

debate over forest uses in areas outside the

traditional production core of the South.

8. Southern forests have proved to be resilient,

but some components are scarce and are,

therefore, at risk. Through the 20th century,

the South has recovered from a largely

cutover, exhausted, and eroded condition

to become one of the most productive forest

regions in the world. However, there are

reasons for concern. Among these are the

presence of numerous imperiled animal

species (28 terrestrial vertebrates are

critically imperiled) and increasingly rare Figure 5.9—Distribution of mussel species by aquatic

fauna provinces (Wear and Greis 2002a).
43

forest communities (14 communities have

been reduced to < 2 percent of their area

at the time of European settlement).

9. To borrow the adage from economics, scarcity

defines value. The rare forest communities

in the South have disproportionately high

ecological value. Thus, much concern about

biodiversity is focused on these relatively

small shares of the forest landscape.

Subregions of Concern

The assessment also allowed us to define where

change and the potential implications of change

are focused within the South. In particular, we

identified three areas in the region where concerns

regarding forest sustainability may be especially

high. These are (1) the Southern Appalachians, (2)

the Piedmont, and (3) the Lower Atlantic and Gulf

Coastal Plains. In the following discussion, these

regions are considered individually.

Southern Appalachians—This region will be

influenced by a combination of human, biological,

and physical factors over the next two decades.

Population growth and land use changes will

increase the human presence in many forests.

Demands for forest-based recreation are focused

on the Southern Appalachians, and increased

competition among recreation user groups is

anticipated. A complex of forest health issues is

affecting all forest types in this region and has the

potential to restructure forest ecosystems there.

Piedmont—The Piedmont, from Virginia to

Georgia, is expected to lose more forest area than

any other part of the South. This heavily forested

region already has a very low ratio of interior

forest to total forest, indicating a high degree of

forest fragmentation. Fragmentation is likely to

continue with growth of populations in urban

counties and interspersed rural counties.

Consequently, wildlife habitats will be altered for

certain neotropical migrant and other important

bird species. Because populations will grow and

forest area will decline, we also expect an

increasing scarcity of forest-based recreational

opportunities for city dwellers.

Lower Atlantic and Gulf Coastal Plains—

Coastal flatwoods areas are forecast to lose much

of their forest area to urban development. Forest

loss combined with intensified forest management

could have cumulative negative effects on coastal

wetlands, both through direct wetland loss and

through modification of hydrological regimes. The

flatwoods, one of two areas in the South with the

highest concentrations of endangered animal and

plant species, contain many imperiled amphibians,

crustaceans, and reptiles. These problems are of

especially great concern in the Florida Panhandle.

Implications of the Assessment for

Forest Research

At the conclusion of an effort such as the SFRA,

it is important to consider what we were unable to

do. In contrast to most bioregional assessments

conducted in the United States to date, which have

been motivated by a crisis of one sort or another

(Gordon 1999), the SFRA can be viewed as an

“anticipatory assessment” (Johnson and others

1999). It was intended to provide a complement

of information to illuminate a dynamic resource

situation and illustrate critical areas before an

actual crisis erupted.

The assessment was successful in describing

several emerging issues that could affect the

sustainability of the South’s forests, but more

information is needed to better identify problems

and potential solutions. Each technical chapter

of the assessment identifies research needs,

and eight broad areas of investigation were

highlighted. The following are some key areas

of uncertainty:

• The effects of population growth on forest

ecosystems

• The influence of changing market and other

values on land use and management choices

• The determinants of overall forest

productivity for all benefits

• Forecasts of changes in ecological structure

and functions

• Broadening the scale of forest research to

better address questions at regional levels

• The role of fire in forests and the effective

use of fire

• The influence of changing forest structure,

and especially the influence of pine

plantations, on ecosystem function and wildlife

• Developing new forest management

strategies for a variety of settings

A finding from the assessment as a whole is

the inability to fully link findings into an

integrated multidisciplinary analysis of forest

ecosystems. The assessment highlights the fact

Chapter 5.

What We Learned
Southern Forest Science:

Past, Present, and Future

Looking Back

44

that fundamental knowledge in various disciplines

cannot yet be readily integrated to address the full

complexity of a dynamic and highly diverse region.

Such an analysis would, for example, allow

us to directly evaluate the impacts of expanded

demand for wood products on the distribution

and condition of wetlands and subsequently on

the distribution and persistence of related species.

Our inability to make these causal links reflects a

shortcoming of ecosystem and resource science

in general that is at its root the result of the form

of scientific investigation. This defines an

important challenge for the South’s forest

research community.

LITERATURE CITED

Gordon, John C. 1999. History and assessments: punctuated

nonequilibrium. In: Johnson, K.N.; Swanson, F.; Herring, M.;

Greene, S., eds. Bioregional assessments: science at the

crossroads of management and policy. Washington, DC:

Island Press: 43–54.

Johnson, K.N.; Swanson, F.; Herring, M.; Greene, S. 1999.

Bioregional assessments: science at the crossroads of

management and policy. Washington, DC: Island Press.

398 p.

Lee, K. 1993. Compass and gyroscope. Washington, DC:

Island Press. [Not paged].

National Research Council. 1998. Forested landscapes in

perspective: prospects and opportunities for sustainable

management of America’s non-Federal forests. Washington,

DC: National Academy Press. 229 p.

Southern Appalachian Man and the Biosphere Cooperative

(SAMAB). 1996. The Southern Appalachian assessment:

summary report. Rep. 1 of 5. Atlanta: U.S. Department

of Agriculture, Forest Service, Southern Region. 118 p.

Wear, David N.; Greis, John G. 2002a. Southern forest resource

assessment. Gen. Tech. Rep. SRS–53. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southern

Research Station. 635 p.

Wear, David N.; Greis, John G. 2002b. Southern forest resource

assessment: summary report. Gen. Tech. Rep. SRS–54.

Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southern Research Station. 103 p.
Productivity
Southern Forest Science:

Past, Present, and Future

Productivity

46

Chapter 6. Productivity................................................................. 47

Chapter 7. Silviculture and

Management Strategies Applicable to

Southern Hardwoods. .......................................................... 51

Chapter 8. The Evolution of

Pine Plantation Silviculture

in the Southern United States. ........................................................... 63

Chapter 9.

Reproduction Cutting Methods

for Naturally Regenerated Pine Stands in the South. ................. 83

Chapter 10.

The Role of

Genetics and Tree Improvement

in Southern Forest Productivity. ........................................................ 97

Chapter 11.

Forest Mensuration with Remote Sensing:

a Retrospective and a Vision for the Future............................... 109
47

Chapter 6.

Productivity

T

he South is blessed with abundant and

diverse forest resources. Today, forests

cover approximately 215 million acres in

the South, which represents 29 percent of the

forest land in the United States (Conner and

Hartsell 2002). Maintaining the productivity

of these forests is essential to the economic,

environmental, and social well being of the South

and the Nation. The forest products industry

ranks among the top industries in most Southern

States and is the largest industry in several. The

wood products sector contributed 770,000 direct

jobs and over $120 billion in total industry output

in 1997 (Abt and others 2002).

The diversity of forest ecosystems in the South

is also large, ranging from mixed, mesophytic

hardwood forests of the Southern Appalachians,

to the planted pine forests of the Coastal Plain

and Piedmont, to the bottomland hardwood

forests along major rivers throughout the region.

In 1999 there were 65 million acres of upland

hardwood forests, 30 million acres of lowland

hardwoods, 29 million acres of mixed pinehardwood forests, 33 million acres of natural

pine, and 30 million acres of pine plantations

in the South excluding Kentucky (Conner and

Hartsell 2002). These forests provide a wide

variety of goods and services other than timber,

including a diverse range of habitat for wildlife,

recreational opportunities, and clean air and

water. These goods and services contribute

to an improved quality of life for an increasing

population that has become more urbanized.

Modern forest management regimes must

provide these noncommodity benefits.

Management practices have been developed

and refined for each of the major forest types in

the South since the advent of scientific forestry at

the Biltmore Estate led by the work of Olmstead,

Pinchot, and Schenck in the 1890s. Although

tremendous strides have been made in the

management of most forest types, progress has

been uneven. Economic factors associated with

the development of southern pine-based pulp and

paper industry, which started in the 1920s and

1930s, fostered the development of pine plantation

management using an agronomic approach.

The work of research scientists and practicing

foresters in the U.S. Department of Agriculture

Forest Service (Forest Service), southern forestry

schools and universities, State forestry agencies,

and private industry in pine tree improvement

and intensive silvicultural practices has greatly

improved the productivity of southern pine

plantations. Similar but less sustained efforts

were periodically directed toward intensive

management of plantation hardwoods, generally

with mixed results. The research efforts directed

toward the management of natural hardwood,

pine, and mixed hardwood-pine stands have been

less concerted than that associated with intensive

pine plantation silviculture. However, individual

research programs within the Forest Service

and at several southern forestry schools have

maintained a strong and consistent focus on these

forest types. Most notable are the Forest Service

research units at Bent Creek and Coweeta focused

on upland hardwoods, the program at Mississippi

State University on silviculture of bottomland

hardwoods, the industry-sponsored Hardwood

Research Cooperative at North Carolina State

University, which has strong programs in both

upland and bottomland hardwoods, and the Forest

Service Research Work Unit at Crossett, AR, that

has developed uneven-aged silvicultural systems

for southern pines.

Six chapters are included in this section on

productivity. Three of these chapters review and

highlight the progress made on silviculture of the

major forest types in the South. This is followed

by a chapter on the history and accomplishments

of tree improvement programs in both southern

pine and hardwoods. The final chapter discusses

the links that exist between silviculture and

remote sensing, specifically focusing on the use

of remote sensing as a mensurational technique.

Thomas R. Fox and

Ray R. Hicks, Jr.1

1

 Associate Professor of Forestry, Virginia Polytechnic

Institute and State University, Department of Forestry,

Blacksburg, VA 24061; and Professor of Forestry, West

Virginia University, Division of Forestry, Morgantown, WV

26506, respectively.
Southern Forest Science:

Past, Present, and Future

Productivity

48

The second chapter of this section “Silviculture

and Management Strategies Applicable to

Southern Hardwoods” by Ray R. Hicks, Jr.,

William H. Conner, Robert C. Kellison, and David

Van Lear addresses the management of upland

and bottomland hardwood forests in the South.

Hardwoods comprise a significant component of

the southern landscape. Some southern forests are

dominated by hardwoods, such as the mesophytic

forests of the Southern Appalachians and the

bottomland stands that border all the major river

systems of the South. In addition, hardwoods form

a significant component of many southern pine

stands. Hardwoods play an important ecological

and economic role in southern forests. They

provide ecological and habitat diversity, valuable

lumber and veneer, and fiber for pulp and paper.

The authors first summarize the physiographic,

edaphic, and climatic factors that characterize the

various types of hardwood forests in the South.

They then address the land use history and

ownership patterns and the role these forces

play in determining the type of hardwood stands

that exist and their influence on objectives of

ownership. Emphasis is placed on our improved

understanding of the role of fire in hardwood

forests and how the extent and frequency of

fires, both historical and current, influence the

composition and structure of hardwood forests.

A detailed description of the silvicultural

techniques for regenerating and culturing the

commercially valuable species of hardwoods is

then presented. The authors also discuss how

silvicultural practices in hardwood stands are

complicated because many hardwood stands

occur on sites that are difficult to operate

equipment and contain a diversity of species

that vary greatly in stumpage value. These

factors, along with the fact that most hardwood

stands occur on small, privately owned tracts,

contribute to the fact that most hardwood stands

are not actively managed and have historically

been exploited and high-graded.

The third chapter in this section “The

Evolution of Pine Plantation Silviculture in

the Southern United States” by Thomas R.

Fox, Eric J. Jokela, and H. Lee Allen reviews

the historical development of intensive southern

pine silviculture. The acreage in pine plantations

has increased significantly over the last 50 years

from < 2 million acres in 1952 to 32 million acres

in 1999 (Wear and Greis 2002). More remarkable

is the significant increase in per-acre productivity

that has accompanied the rapid expansion of pine

plantations. Mean annual increment of pine

plantations has more than doubled, and rotation

lengths have been cut by more than 50 percent.

Although planted pine accounts for only 15

percent of the total forest land base in the South,

it accounts for 35 percent of the annual harvest

volume (Wear and Greis 2002).

The authors of this chapter highlight the

changes in pine plantation silviculture that

have occurred since 1950. The contributions to

improved plantation yields of tree improvement,

improved nursery practices, site preparation,

competition control, fertilization, growth-and-yield

modeling, and land classification are presented on

a decade-by-decade basis. Current state-of-the-art

silvicultural practices involving integrated, sitespecific, rotation-long silvicultural manipulations

are discussed. A vision of the future presented

by the authors includes clonal deployment of

elite genotypes produced through somatic

embryogenesis and managed on a site-specific

basis to optimize growth rates and financial

returns in an environmentally sustainable manner.

Precision silviculture of pine plantations in the 21st

century in the South will embrace the advances

coming out of precision agriculture. The role that

cooperative research and technology transfer had

in the successful development of intensive pine

plantation silviculture is emphasized throughout

the chapter. The take-home message from the

authors is that no one single organization had

the financial or intellectual resources required

to develop the needed silvicultural technology

in the past. As the level of complexity of pine

plantation silviculture increases in the future,

concerted, cooperative research efforts will

continue to be needed.

The fourth chapter in this section

“Reproduction Cutting Methods for Naturally

Regenerated Pine Stands in the South” by James

M. Guldin, discusses management practices in

natural pine and mixed pine-hardwood stands.

Although the acreage in pine plantations has

increased significantly over the last 50 years, the

author correctly points out that a large percentage

of forest land in the South will remain in natural

stands. There are currently 62 million acres of

natural pine or mixed pine-hardwood forests in

the South (Wear and Greis 2002). These stands

must be managed using classical silvicultural

practices that establish and maintain productive,

healthy forests that provide a variety of goods and

services required by society. Natural regeneration

is frequently the only option financially available
49

to nonindustrial landowners. Longer rotations

required to produce large-diameter pine trees

and other multiple-use benefits associated with

them, such as aesthetics and wildlife habitat, may

not be feasible in plantation systems. Certain

landowners and segments of the general public

may reject the clearcut and plant approach

required in plantation silviculture. Regulatory

requirements, including best management

practices in all Southern States, prohibit

clearcutting in streamside management zones.

Management prescriptions involving natural

regeneration that avoids high-grading and

protects water quality must be developed for

these sensitive, high-quality sites.

The author reviews silvicultural practices that

establish and maintain naturally regenerated pine

and pine-hardwood mixtures. He discusses both

even-aged and uneven-aged reproduction cutting

methods, including seed tree and shelterwood

systems and group and single-tree selection.

He illustrates how both even-aged and unevenaged systems can be effective in southern pine

stands depending upon which species are present,

the site preparation practices, and the manner

that required intermediate treatments, such as

release, are employed to assure adequate seedling

establishment and rapid stand development. The

importance of residual overstory basal area, timing

of harvests to take advantage of cone crops and

seed production, appropriate site preparation to

create suitable seed beds, control of competing

vegetation, and control of stand density are

emphasized as key components of a successful

natural regeneration system in southern pine.

The fifth chapter in this section “The Role

of Genetics and Tree Improvement in Southern

Forest Productivity” by R.C. Schmidtling, T.L.

Robison, S.E. McKeand, R.J. Rousseau, H.L.

Allen, and B. Goldfarb documents the impacts that

tree improvement activities have had in the South

over the last 50 years. The contributions of applied

tree improvement to the increased productivity of

southern pine stands are recognized throughout

the world as one of the major success stories of

modern forestry. Beginning with the pioneering

work of Wakeley on seed source variation in

southern pine in the 1920s, research on tree

improvement in southern pines has progressed to

the point where loblolly pine (Pinus taeda L.) is

today probably the most domesticated and best

understood conifer in the world. Again, hardwood

species have received less attention in the South

than have pines. However, interest in hardwoods

has recently increased because of work in the

developing field of forest biotechnology. Hardwood

species, most notably those in the genera Populus

and Eucalyptus, are proving to be much easier

to study and manipulate through tissue culture,

genetic mapping, and genetic engineering

techniques than conifers. Hardwoods will

probably serve as model systems where

the gains in biotechnology are first realized

in forestry.

The authors of this chapter provide a thorough

review of the history of forest tree improvement

in the South from its infancy in the 1920s. They

include a discussion of both southern pine and

hardwood tree improvement programs. They

illustrate how the observations and efforts of

practicing foresters played an important role

during the early phases of tree improvement.

These initial efforts were superseded by

well-coordinated, sophisticated, cooperative

research programs involving Federal and State

Governments, universities, and private industry.

Today approximately 1 billion southern pine

seedlings are planted annually, nearly all of

them the product of tree improvement programs.

The authors discuss the productivity gains made

using first-generation slash (Pinus elliottii

Engelm.) and loblolly pine. Gains are estimated

to be 15 to 20 percent over unimproved, natural

populations. Additional gains will be made

from the deployment of advanced generation

material from elite populations through

techniques such as open-pollinated single-family

block plantings, and full-sib deployment using

control mass pollination. Clonal forestry looms

on the horizon as an opportunity to exploit the

full genetic potential of various commercial

species through the development of tissue culture

techniques, such as rooted cuttings and somatic

embryogenesis. The science of genomics will

provide improved tools such as marker-aided

selection that will increase the efficiency of tree

improvement programs. The authors conclude

with a cautionary note on the need to conserve

long-term genetic diversity while managing for

short-term productivity gains.

The final chapter in this section, “Forest

Mensuration with Remote Sensing: A

Retrospective with a Vision for the Future,”

by Randolph H. Wynne, discusses the role

of remote sensing as a tool that practicing

foresters can use to improve forest productivity.

As management practices intensify, foresters

require more detailed information upon which

Chapter 6.

 Productivity
Southern Forest Science:

Past, Present, and Future

Productivity

50

to base their decisions. Forestry is moving toward

the agricultural model of intensive, site-specific

management that can be broadly characterized

as precision forestry. Information from digital

remote sensing can be quickly integrated

into a forester’s decision process to develop

sophisticated, fully integrated rotation-long

management regimes that best meet landowner

objectives. Although forest management

at this level of intensity is often associated

with the desire to optimize financial returns,

sophisticated management scenarios are needed

by any forester attempting to meet the competing

demands placed on forest resources today.

For example, meeting the needs for aesthetics,

recreation, wildlife habitat, water quality,

endangered species, wilderness, and timber

production is a much more complicated task

than simply optimizing growth and associated

financial returns from timber management.

The chapter begins with a retrospective

discussion of remote sensing, which reviews

the long use of aerial photos to improve forest

management. A section on timber volume

estimation using aerial photos is then presented.

This section explains how tree and stand

properties such as stand density, tree height,

crown dimensions, and crown cover can be

obtained from conventional aerial photos and

used to create photo volume tables. Historically,

the variation in stand-volume estimates based

on aerial photos was too high (often exceeding

25 percent) to be of great value for many uses.

The most widespread use of remotely sensed

data in forestry has been, and continues to be,

to stratify and map stands, calculate land area,

and simplify navigation. The value of aerial photos

as a navigation tool used by foresters to increase

the efficiency of their day-to-day activities in the

woods should not be overlooked. The author then

discusses new developments in remote sensing

and computer technologies, and explains how they

are being used to improve volume estimates of

stands. The developing tool of lidar (light detecting

and ranging), which uses an airborne laser to

accurately estimate canopy height, crown density,

and stand density is discussed. Lidar-based

measurements are proving to be more accurate

and less biased than conventional photo-based

estimates of tree and stand parameters. The

author is optimistic that the high cost of cost data

acquired with these new techniques will decrease

and that the combination of decreasing cost and

increasing efficiency will improve the cost/benefit

ratio of this technology. The chapter concludes

with a discussion of how remote sensing utilizing

these new techniques and tools will be an integral

component of the new precision forestry paradigm.

LITERATURE CITED

Abt, K.L.; Winter, S.A.; Huggett, R.J., Jr. 2002. Local economic

impacts of forests. In: Wear, David N.; Greis, John G., eds.

Southern forest resource assessment. Gen. Tech. Rep. SRS–

53. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southern Research Station: 239–267.

Conner, R.C.; Hartsell, A.J. 2002. Forest area and conditions.

In: Wear, David N.; Greis, John G., eds. Southern forest

resource assessment. Gen. Tech. Rep. SRS–53. Asheville,

NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station: 357–401.

Wear, David N.; Greis, John G., eds. 2002. Southern forest

resource assessment. Gen. Tech. Rep. SRS–53. Asheville,

NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 635 p.
51

Chapter 7.

Silviculture and Management Strategies Applicable to

Southern Hardwoods

Ray R. Hicks, Jr., William

H. Conner, Robert C. Kellison,

and David Van Lear1

Abstract—Southern hardwood forests stretch

from the Virginias to Florida and from the midAtlantic to Missouri. They can generally be

grouped into upland forests and bottomland

forests. The upland hardwood forests of the

southern region are usually associated with the

mountainous topography of the Appalachians and

Ozarks. Bottomland hardwoods are found along

the floodplains of larger rivers in the Atlantic and

Gulf Coastal Plains, including the Mississippi River

floodplain. Southern hardwood forests are owned

by a variety of governmental and private owners,

but the vast majority of owners are nonindustrial

private individuals. These owners seldom engage

in intensive forest management, often exploiting

the resource. The silvicultural systems applicable

to the management of hardwoods are the same

as those recommended for pines, but in hardwood

management, reliance on natural regeneration is

more common than use of plantation silviculture.

Oak species are very important in the southern

hardwood forests, and lack of oak regeneration

in present-day forests is a major concern. Lack

of fire and the resurgence of white-tailed deer

throughout the southern region are proposed as

reasons for poor oak regeneration. Many stands,

either due to their stage of development or

neglect, are in need of intermediate management

operations such as thinning and improvement

cutting. Crop-tree management is a method that

is particularly useful in southern hardwoods. It

was concluded that although hardwoods make

up a significant part of the southern forest

resource, they are generally managed with less

intensity than pines, and hardwood management

is an opportunity area for the South in the future.

INTRODUCTION

I

n this chapter, we discuss the silviculture

and management of upland and bottomland

hardwoods in the Southeastern United States.

We begin by briefly describing the physiographic,

edaphic, and climatic conditions for each forest

type. Land use history and ownership patterns

are then discussed because these factors are

important in determining what types of stands

occur and the objectives of landowners. Finally we

describe the appropriate silvicultural techniques

for regenerating and culturing the commercially

valuable species in each management type.

Upland Hardwoods

The southern upland hardwoods occur

extensively in the Southern Appalachians,

on the Cumberland Plateau, and in the Ozark

region. A diverse array of hardwood species is

represented by genera such as Acer, Carya,

Fraxinus, Liquidambar, Liriodendron, Prunus,

and Quercus. The southern upland hardwoods

include pine-hardwood mixtures in the Piedmont

and southern Coastal Plains, but by far the most

commercially significant upland hardwoods in

the South occur in the Southern Appalachian

region. For purposes of this discussion, the

Southern Appalachian region includes the hilly or

mountainous area west and north of the Piedmont

and south of the glaciated portion of Pennsylvania.

Using Fenneman’s (1938) classification, this region

is termed the “Appalachian Highlands,” and

contains parts of the Blue Ridge, Ridge and Valley,

and Appalachian Plateau physiographic provinces.

The Appalachian Highlands are classified as being

in the Eastern Broadleaf Forest Province (Bailey

1996). The climate is continental and part of

the Humid Temperate Domain (Bailey 1996).

Rainfall is favorable for plant growth and is

well distributed throughout the year. Highest

precipitation rates occur in the southern Blue

1

 Professor of Forestry, West Virginia University, Morgantown,

WV 26506; Professor of Forestry, Baruch Institute of Coastal

Ecology and Forest Science, Clemson University, Georgetown,

SC 29442; Professor Emeritus, North Carolina State

University, Raleigh, NC 27695; and Professor of Forestry,

Clemson University, Clemson, SC 29634, respectively.
Southern Forest Science:

Past, Present, and Future

Productivity

52

Ridge of the Carolinas and north Georgia, where

annual precipitation averages 60 to 80 inches

per year (Hicks 1998). Across most of the region,

annual precipitation averages 40 to 50 inches. The

geology of the Appalachian Highlands region is

predominantly sedimentary. Sandstones of the

Pennsylvanian period cap the highest mountains

throughout the Appalachian Plateau Province,

and limestones and shales predominate in the

sharply folded Ridge and Valley Province. The

Blue Ridge is composed primarily of metamorphic

rock substrates with some igneous intrusions

and small areas with sedimentary rock. At

higher elevations of the southern Blue Ridge,

Precambrian rock outcrops can be found. Faulting,

folding, and geologic weathering have interacted

with the geologic materials to produce the

complex, steep, and rocky terrain found in

the Appalachian Highlands.

Deciduous hardwood species predominate in

the Appalachian Highlands. These include several

oaks (Quercus spp.), hickories (Carya spp.),

maples (Acer spp.), yellow-poplar (Liriodendron

tulipifera L.), black cherry (Prunus serotina

Ehrh.), and American beech (Fagus grandifolia

Ehrh.). The area was also a prime range for

American chestnut [Castanea dentata (Marsh.)

Borkh.], a species that was all but eliminated by

the chestnut blight {Cryphonectria parasitica

(Murrill) Barr [formerly Endothia parasitica

(Murrill) Anderson & Anderson]} during the early

part of the 20th century. Braun (1950) classified a

substantial portion of the Appalachian Highlands

as being in the oak-chestnut forest region. Most

of the forests of the Appalachian Highlands are

second growth, resulting from previous logging

and fires or from revegetation of abandoned fields.

Bottomland Hardwoods

Southern bottomland hardwoods occur mainly

in the broad, Lowland Coastal Plain Province of

the Atlantic Plain physiographic division and the

gulf lowlands (Fenneman 1938) extending from

the eastern tip of Pennsylvania south along the

Atlantic coast and west along the gulf coast to

the Rio Grande River. They also occur north

along the Mississippi River floodplain to southern

Illinois and to some extent along all the major

and minor rivers east of the Great Plains (Hodges

1995). Despite the dense tree cover and the

difficulty of clearing land, this ecosystem was

the first in the Southern United States to be

converted to agricultural crops. It was taken for

agricultural use because it occupied level terrain

with inherently fertile soils. The Coastal Plain is

underlain by alluvial and marine sediments of

mostly Cretaceous, Tertiary, and Quaternary

age. Sediments were laid down in various onshore,

nearshore, and offshore environments (Stanturf

and Schoenholtz 1998). Annual precipitation in

the major alluvial floodplains ranges from 48 to

64 inches and is generally greater during the

warm season (Kellison and others 1998, Muller

and Grymes 1998). The amount of rainfall

received, however, is not a reliable indicator of the

magnitude and duration of the flooding that can

occur. Upstream precipitation in large watersheds

(some cover hundreds of thousands of acres) has a

larger impact on downstream flooding than local

precipitation does (Kellison and others 1998).

Bottomland forests are extremely diverse,

including more than 70 tree species (Putnam and

others 1960) of which 40 are of commercial value

(Hosner 1962). Angiosperms predominate, but a

few gymnosperms occur. A number of tree species

are common throughout southern bottomlands;

these include red maple (A. rubrum L.),

water hickory [C. aquatica (Michx. f.) Nutt.],

sugarberry (Celtis laevigata Willd.), persimmon

(Diospyros virginiana L.), green ash (Fraxinus

pennsylvanica Marsh.), sweetgum (Liquidambar

styraciflua L.), swamp chestnut oak (Q. michauxii

Nutt.), water oak (Q. nigra L.), American

elm (Ulmus americana L.), and baldcypress

[Taxodium distichum (L.) Rich.] (Kellison and

others 1998). Bottomland hardwood forests occur

in the portions of the floodplain that are free from

flooding for most of the year. These areas support

the most diverse forests and sustain excellent

growth (Smith 1995). Areas that are flooded for

extended periods every year have fewer species,

which have evolved special adaptations to these

conditions (McKevlin and others 1998). Growth

rates in the more flooded areas can be high, but

they are highly variable (Conner 1994, Conner

and Buford 1998, Megonigal and others 1997).

The quality and composition of bottomland

forests have been influenced dramatically by past

timber harvesting, agricultural use, grazing, and

uncontrolled fires. The overall result of these

influences has been a general degradation of

composition and quality, even though volumes

are increasing (Hodges 1995).

Pre-European Forests

Both upland and bottomland hardwood

forests of the Southeastern United States were

manipulated by Native Americans for thousands

of years prior to the advent of Europeans (Carroll

and others 2002). Native Americans used fire for

many purposes. They controlled the composition
53

and pattern of vegetation by frequently burning

the southern landscape. They burned to manage

wildlife habitat, ease travel, expose acorns and

chestnuts, improve visibility, encourage fruiting,

prepare their fields for planting, and to facilitate

hunting and defense (Bonnicksen 2000, Pyne

and others 1996, Williams 1989). Frequent lowintensity burning by Native Americans created a

southern landscape of prairies, fields, savannas,

woodlands, and dense forests. The southern

hardwood forest was hardly a dense, old-growth

landscape at the time of European discovery.

The myth of low-impact management by Native

Americans may have been reinforced by the fact

that the major European occupation of interior

America came after native populations had been

devastated by diseases introduced by earlier

European immigrants.

Some areas were burned on an annual basis

and, if burning continued over long periods,

became prairies or balds. Other areas, such as

north-facing coves in the Southern Appalachians

and frequently flooded bottomland forests, burned

infrequently. Between these two extremes were

forest communities that burned at varying

intervals, thus creating a mosaic of forest

conditions throughout the South. In the hardwood

forests of the South, anthropogenic fires were

complemented by occasional lightning-ignited

fires (Carroll and others 2002).

Post-European Effects

The European settlers who displaced the

Native Americans from the upland forests

continued to burn the forest frequently to

encourage forage production for their livestock

(Pyne and others 1996). However with the advent

of steam power for harvesting and processing

of timber, wide-scale logging and the slash it

produced created a different type of fire regime.

High-intensity, stand-replacement fires ignited

by sparks from locomotives followed logging and

burned vast acreages of upland forests from the

late 1880s though the early 1930s (Brose and

others 2001).

Fire protection efforts begun early in the 20th

century gradually became more effective and

allowed the forests to develop—for the first time in

millennia—in the absence of fire. However decades

of fire exclusion had unintended consequences.

The development of dense understories and

midstories of shade-tolerant shrubs and trees is

now a major contributor to the oak regeneration

problem. In other areas, rhododendron

(Rhododendron maximum L.) and mountain

laurel (Kalmia latifolia L.) thickets have become

so dense and expansive that the species diversity

of cove forests is threatened. Because of these

problems, there is renewed interest in using

prescribed fire as a management tool in upland

hardwood forests (Yaussy 2000).

Villages of early European colonists were

almost always located along major streams.

A rice culture developed, first in the vicinity of

Charleston, SC, and then elsewhere along the

Southeastern U.S. coast. On the fringes of the

rice paddies and beyond, corn, wheat, and cotton

supplanted hardwood forests.

Following attempts to control water flow in

the major alluvial floodplains, first by private

enterprise and then by public agencies, especially

the U.S. Army Corps of Engineers, the forests

were increasingly cleared for agricultural crops.

Only about half of the original bottomland forests

remained by the 1930s. From the 1930s to the

1980s, the bottomland forest area was further

reduced from 11.8 to 4.3 million acres as a result of

drainage and clearing for agriculture.2 Conversion

was especially rapid during the 1960s and 1970s

when the price for farm crops, especially soybeans,

reached unprecedented levels.

Land Ownership Characteristics

The majority of hardwood forest land (upland

and bottomland) is in the hands of nonindustrial

private forest (NIPF) ownership (MacCleery

1990), although a substantial portion of the Blue

Ridge and Allegheny Highlands is in national

forests and parks. The motivation for forest

activity for most nonindustrial forest landowners

appears to be income, although most of these

owners do not rank commercial forest production

as the number one reason for holding land (Egan

and Jones 1993).

It is possible to combine commercial timber

operations with forest stand improvement through

application of appropriate silviculture in southern

hardwoods. The development of new markets for

smaller diameter and lower grade materials has

enhanced the opportunity for producing revenue

from heretofore noncommercial stands.

Unfortunately, however, the type of timber

harvesting often being practiced on NIPF lands

amounts to high-grading of one type or another.

Chapter 7.

Southern Hardwoods

2

 Allen, J.A.; Kennedy, H.E., Jr. 1989. Bottomland hardwood

reforestation in the Lower Mississippi Valley. [Not paged]. On

file with: Southern Research Station, Southern Hardwoods

Laboratory, P.O. Box 227, Stoneville, MS 38776.
Southern Forest Science:

Past, Present, and Future

Productivity

54

Forest landowners share certain attributes

that help to explain their behavior. Many are older

and have lived during times when much of today’s

forest land was in fields, a condition that they

worked hard to preserve. In addition, many

people, accustomed to the practices of the past,

believe that “timbering” is a once-in-a-lifetime

affair. Thus many owners fail to see the value

of managing their forest land.

It is incumbent on foresters who interact

with landowners to begin their association by

explaining what planned forest management

means and what is and is not possible. Owners

need to understand that even with relatively

small tracts, it is possible to spread the income

out over time while enhancing the future health,

productivity, and value of the forest. It may be

difficult to convince owners of such facts, since

foresters are going against beliefs that have been

years in the making. Owners may find it difficult to

accept the fact that many second-growth forests

are even-aged, and the larger trees are not older,

but simply faster growing.

SILVICULTURE OF UPLAND HARDWOODS

O

aks, as a group, constitute the most significant

hardwood forest resource in the southern

uplands. Oaks, however, are losing their

position in many upland forests, being replaced by

aggressive species such as red maple and yellowpoplar (Abrams 1998, Brose and others 2001).

Exclusion of periodic, low-intensity surface fires

from the hardwood forests of the Appalachian

Highlands in the early decades of the 20th century

has changed the character of these forests. Oaks

thrive under a regime of periodic disturbance by

surface fires (Brose and others 1999, Van Lear and

Brose 2001). Because young oaks invest heavily in

root development at the expense of height, they

are at a competitive disadvantage with aggressive

species like yellow-poplar and red maple,

especially on above-average sites. However, when

surface fires kill the aboveground portion of trees,

the resulting seedling sprouts of oaks have a

distinct advantage over their competitors. In the

absence of periodic surface fires, oaks do not

maintain a position of dominance in the advance

regeneration pool. Thus as wind, ice, or partial

harvesting disturbs the upper canopy, other

species in the advance regeneration pool are

poised to dominate.

This chapter uses concepts from Hicks’

(1998) book “Ecology and Management of

Central Hardwood Forests” to describe the

silvicultural methods that are appropriate to

most upland hardwood stands. It is our goal to

demonstrate that properly designed commercial

harvests can utilize silviculturally sound concepts,

and to provide descriptions of relevant silvicultural

methods and their application to NIPF stands.

We also hope to discourage the use of loose terms

such as “selective cutting,” and to encourage

foresters to develop a vocabulary that is

appropriate and descriptive of the practices being

recommended. Finally we want to stress that in

hardwood stands, it is often necessary to apply

several silvicultural methods simultaneously, and

that management of hardwood stands must remain

adaptable to changing market conditions, natural

occurrences such as insect and disease outbreaks,

and changing social pressures.

Most silviculture and forest management

texts emphasize “traditional” approaches based

on German methods that were developed for use in

relatively simple coniferous ecosystems. Although

a great deal of research on hardwood management

has been conducted in North America, the

information that has been produced must be

presented in a form that is useful to managers.

Silvicultural methods can generally be grouped

into treatments that are used to tend existing

stands (intermediate operations) and those that

are aimed at regenerating new stands. Hardwood

silviculture differs markedly from pine silviculture

in both areas. Topographic considerations,

economic factors, and the abundance of natural

regeneration usually prevent the application of

plantation silviculture for upland hardwood

management. Also, hardwoods almost always

occur in mixed species stands in which

commercially valuable trees are intermingled with

trees of lower value. The objective of management

is to work in concert with the natural ecosystem

processes to favor the regeneration, growth, and

quality of desirable trees. Intermediate cuttings

that are most appropriate to hardwoods are crown

thinning, improvement cutting, and crop-tree

management. Among regeneration systems, those

that are most appropriate to hardwoods are

clearcutting, the shelterwood method, and related

two-age systems. All of the foregoing create evenaged or two-age stands. The single-tree selection

system and variations such as group selection will

work well if the objective is to grow shade-tolerant

species in multiage stands. However, none of the

shade-tolerant commercial species in the

southern forest region provide viable

management opportunities.
55

Intermediate Operations

Crown thinning—The crown-thinning method is

defined by Smith (1986) as thinning that involves

the removal of trees in the upper strata of the

canopy to favor desirable trees in the same canopy

range. In crown thinning, the focus is on the better

trees (crop trees) that are to be provided with

additional growing space and resources. As with

all thinning methods, crown thinning is applied

at the stand level where residual stocking targets

are an important consideration. Crown thinning

seems particularly applicable to fully stocked or

overstocked mixed oak or mixed mesophytic

hardwood stands on above-average sites. Although

species such as northern red oak (Q. rubra L.)

are capable of responding to release at age 50

and older, appropriate candidate stands of shadeintolerant species such as yellow-poplar and

black cherry should be treated earlier than oaks.

Care should be given to residual stand density,

understory composition, and stem wounding of

residual trees. Excessive thinning can induce

epicormic branching of residuals or release

undesirable midstory or understory species, or

both. Sonderman and Rast (1988) recommend

thinnings of moderate-to-light intensity in mixed

oak stands in order to minimize branch-related

defects that typically result from heavier thinnings

in such stands. Residual stand density should be

maintained at a level above the “B” line and below

the “A” line defined by Gingrich (1967).

Improvement cutting—Smith (1986) defines

improvement cutting as cuttings done in stands

past the sapling stage for the purpose of improving

composition and quality by removing trees of

undesirable species, form, or condition from the

main canopy. Unlike crown thinning and crop-tree

management, the focus of improvement cutting

is on the “undesirable trees.” Improvement cutting

is widely applicable to southern upland hardwood

stands. It is appropriate for use in mixed oak, oakhickory, and mixed mesophytic hardwood stands.

The silvical characteristics of the species present

should be a prime consideration, but improvement

cutting can generally be applied to stands well

beyond age 50. Depending on the owner’s

objectives, species typically targeted for removal

can include red maple, American beech, hickories,

blackgum (Nyssa sylvatica Marsh.), scarlet oak

(Q. coccinea Muenchh.), and black locust (Robinia

pseudoacacia L.) in addition to poor-quality

individuals of more favored species. Improvement

cutting is widely applicable to current upland

hardwood stands because of the age and current

composition of many such stands, although

marketing of trees removed may be difficult. Many

upland hardwood stands have a past history of

high-grading (Nyland 1992) which may limit the

number of desirable trees available to leave in the

residual stand. At some point, it becomes advisable

to regenerate severely impoverished stands rather

than apply intermediate management to them.

Crop-tree management—Crop-tree management

is a technique that focuses on “individual” trees

that have the potential to develop into high-value

crop trees. Perkey and others (1993) emphasize

that crop-tree value should be defined by

the landowner’s objectives. The two phases

in crop-tree management are assessment and

enhancement. Generally the assessment phase

involves the selection of trees that have the

potential for meeting the objectives defined by

the landowner. Enhancement consists of activities

that foster the attainment of those objectives. For

example, if timber management was the objective,

trees of desirable species with good stem quality

and capable of responding to release would be

selected as crop trees. The enhancement operation

would release crop trees by removing some of the

trees that compete with them for sunlight, water,

and nutrients. The recommended method for

releasing crop trees is the “crown-touching”

method described by Lamson and others (1988).

To apply this method, the crop-tree crown is

divided into four quadrants (sides) and one

determines whether the tree is free-to-grow

on each of these sides. A three-sided release

has been recommended by Lamson and others

(1990) for use in younger stands. For older

stands or for species with a tendency toward

epicormic branching, a two-sided release is

more appropriate. Cutting, girdling, or the use

of herbicides (Miller 1984) can accomplish release

of the crop tree. The advantages of crop-tree

management are:

1. It permits crop-tree designation to fit

landowner objectives

2. It is simple to apply and fits well with

NIPF needs

3. It provides for an even flow of forest products

over time

4. It allows for continuous forest cover until

crop trees are harvested

5. Management efforts are concentrated on trees

with the highest potential for future gain

Crop-tree management has disadvantages:

1. It does not provide for regeneration after

removal of crop trees

Chapter 7.

Southern Hardwoods
Southern Forest Science:

Past, Present, and Future

Productivity

56

2. Sometimes removal of low-grade interfering

trees may not be a commercial operation and

thus may constitute a cost to the landowner

However generally speaking, crop-tree

management like improvement cutting is a widely

applicable method that is appropriate to many

mixed hardwood stands. The earlier the crop-tree

enhancement can be applied to a stand, the longer

the effect can benefit the crop trees. However,

there are risks in attempting to assess crop trees

and potential competitors at early ages.

Silvicultural Systems and

Regeneration Methods

When a harvest is planned, an assessment

should be made to determine how the stand

would be regenerated. The information needed

includes: (1) condition and size-class distribution

of overstory trees by species; (2) quantity and

condition of understory trees (desired initial and

advanced reproduction); (3) kind and amount

of competing vegetation; and (4) regeneration

method, e.g., seeds, seedlings, or stump and

root sprouts (Nyland 1996).

Clearcutting—In the clearcutting method,

the overstory is completely removed in a single

operation. The method is designed to regenerate

even-aged, single-cohort stands, and generally

favors relatively shade-intolerant species.

Clearcutting mimics large-scale disturbances

such as the fires and windstorms that have had a

historic role in the creation of southern hardwood

stands. In order to provide conditions that qualify

as a clearcut, openings must be at least 1 to 2

acres in size (Sander 1992). In the southern

uplands, clearcutting promotes regeneration of

fast-growing, exploitive species such as yellowpoplar, sweetgum, and pines. On poorer sites

(south- and west-facing slopes and ridges),

clearcutting is effective in regenerating oaks.

On the best sites in the Southern Appalachians

(oak site index greater than 70), clearcutting

favors yellow-poplar, often resulting in pure

stands of that species. Successful regeneration

can be delayed after clearcutting by the rapid

development of competing vegetation such as

ferns, brambles, and herbaceous species, as well

as woody perennials such as sassafras [Sassafras

albidum (Nutt.) Nees], dogwood (Cornus florida

L.), rhododendron, and grapevine (Vitis spp.). In

most cases, commercial woody species ultimately

prevail, but other factors such as heavy browsing

by white-tailed deer (Odocoileus virginianus)

can delay the regeneration process even further.

The early successional communities produced by

clearcutting provide exceptionally good habitat

for wildlife in the Southern Appalachians where

maturing second-growth forests dominate the

landscape (Harlow and others 1997).

Although clearcutting is a reliable way

to regenerate a variety of hardwoods, many

landowners regard it with disfavor. For a short

time (1 to 10 years, depending on site quality), it

produces a bare landscape that is not aesthetically

acceptable to most owners. In addition, in the

case of NIPF ownership, the property is often

relatively small. A small owner who wants to

attract a buyer for his or her timber may find it

necessary to cut most or all of the timber at one

time. This creates an undesirable situation in

which income is produced only at very long

intervals and the aesthetic value of the property

is compromised for a long period. Conversely for

larger ownership, clearcuts up to 20 to 30 acres

might represent a relatively small percentage

of their land base.

Shelterwood method—The shelterwood

method is an even-aged management system

that involves development of a standing crop of

regeneration through a series of partial removals

of the overstory (Smith 1986). In a three-cut

shelterwood, the cuts are: (1) a preparatory

cutting, designed to improve the quality and vigor

of the residuals; (2) a seed cutting, designed to

encourage regeneration; and (3) a removal cutting,

designed to remove the overstory. The two-cut

variation of the method eliminates the preparatory

cutting and is appropriate where most of the trees

in the current stand are of the desired species.

The shelterwood method is often recommended

for regenerating species that are intermediate in

shade tolerance, such as oaks (Loftis 1990, 1993).

A shelterwood-burn technique developed

by Brose and others (1999) takes advantage of

basic differences between germination and root

development strategies of oaks and many of their

competitors to enhance the competitive position

of oak regeneration on good sites. A few years

after the initial shelterwood cut, a moderately

hot growing-season burn is run through the

developing advance regeneration to favor the

oak reproduction. The reduction in competing

vegetation by burning and the vigorous

resprouting by oak reproduction shortens

the time the shelterwood method requires.

In the absence of fire, it may take 10 to 20

years to complete the shelterwood regeneration

process, and this represents a longer commitment

on the part of landowners and managers than

they may be willing to make. Deer browsing can

become a significant problem when applying the
57

shelterwood method, since deer often selectively

browse species that are desired as regeneration.

Two-aged system—Leave-tree (deferment)

cutting is receiving increasing attention for

regeneration of southern upland and bottomland

hardwoods. Implementation of the practice

includes leaving 20 to 30 square feet per acre of

basal area until the end of the following rotation

in combination with the regeneration that develops

in the openings created by partial harvesting of

the parent stand. As opposed to the shelterwood

system, where the residual overstory trees are

removed to allow the regeneration to develop,

leave-tree cutting maintains the overstory trees

until the end of the rotation. At that time, the

residual trees are removed together with about

75 percent of the basal area of the regenerated

stand. The cycle is repeated in the next rotation

and, thus, an overstory is present during all

stages of stand development.

An additional benefit of this system is that

a mixture of crop trees can be retained for the

next rotation. Some of the trees might be selected

for their timber value, and some for wildlife and

other values. This system is equivalent to the

“high forests with reserves” of European forestry

(Matthews 1989). A major disadvantage of twoage systems is the vulnerability of leave trees

to damage by windthrow, lightning strikes, and

epicormic shoot development.

Selection system—The single-tree selection

system is designed to develop a multicohort

(all-age) stand of shade-tolerant species. In

practice, however, it may be impractical to achieve

this goal because it requires frequent stand entry

and because the smallest diameter classes may

not develop in the shade of trees of the larger

diameter classes. Proper application of the

selection system involves establishing several

criteria, which include a residual basal area target,

largest-tree-to-grow, a “q” factor, and a cutting

cycle length (Smith and Lamson 1982). Single-tree

selection is complex to apply, requires long-term

commitment, and requires the presence of

commercial species that are shade tolerant. In

the Southern Appalachians, it may be applicable

only in high-elevation stands that contain sugar

maple (A. saccharum Marsh.). Because

it has these limitations, professional foresters

rarely apply the system.

Modifications of this method involve cutting

trees in small groups or patches. These “group

selection” systems may be more appropriate

in the southern upland hardwoods than singletree selection, although group selection, like

single-tree selection, requires repeated entry

into the stand. One of the common mistakes

made by both foresters and landowners is to

refer to “selective cutting” (cutting some trees

and leaving others) as a legitimate silvicultural

activity. The similarity between the terms

“selective cutting” and “selection system”

is unfortunate and leads to confusion.

SILVICULTURE OF BOTTOMLAND

HARDWOODS

B

ottomland hardwood forests are made up

of an extremely heterogeneous mixture of

species except in permanently flooded swamps

and newly formed lands and old fields. Thirteen

bottomland forest types are recognized by the

Society of American Foresters (Eyre 1980). The

U.S. Department of Agriculture Forest Service

recognizes only two bottomland hardwood types

for inventory purposes: oak-gum-cypress and

elm-ash-cottonwood. The following discussion of

silvicultural information draws heavily on Hodges

(1995) and the chapter by Kellison and others

(1998) in the book “Southern Forest Wetlands:

Ecology and Management” (Messina and Conner

1998). Other primary sources include McKelvin

(1992) and Kellison and Young (1997) who have

compiled the findings of scientists regarding

regeneration of bottomland hardwood forests.

Mixed hardwoods in the major alluvial

floodplains generally have been logged one

to several times since Dutch settlers (Heavrin

1981) built the first sawmill in the United States

in 1633. Loggers have usually removed only the

best and largest trees while leaving the smallest

and least valuable trees to form the new stand.

This form of timber harvesting, commonly known

as selective harvesting, is in reality high-grading,

a practice that should be condemned by foresters.

This degenerative practice is not to be confused

with the silviculturally sound selection system,

in which the desired tree species mix of all size

classes is maintained.

Diameter-limit cutting, improperly applied, is

another form of high-grading. The principle is to

harvest only those trees above a certain size, such

as those 14 inches in diameter at breast height,

and leave the remainder to develop into the

succeeding stand. The assumption is that the

small trees will grow into large trees of good

quality in perpetuity. The problem is that natural

stands of timber do not perpetuate themselves

by like-producing-like. The openings created by

removal of the larger trees will be occupied by the

Chapter 7.

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Southern Forest Science:

Past, Present, and Future

Productivity

58

expanding crowns of the edge trees or by shadetolerant understory trees that are already in place.

The succeeding trees decrease the value of the

stand for timber production and wildlife habitat

with each partial harvest. In alluvial floodplains,

cherrybark oak (Q. falcata var. pagodifolia

Ell.) would likely be succeeded by green ash;

green ash would be replaced by sugarberry;

and boxelder (A. negundo L.) and American

hornbeam (Carpinus caroliniana Walt.) would

finally supplant sugarberry. Generations of

selective, incomplete harvests have reduced many

bottomland hardwood stands to a poorly stocked,

low-value condition.

The proper management procedure for

major alluvial floodplain forests is to control the

undesirable trees at the same time desired ones

are harvested, and to maintain natural patterns

and cycles of water flow (Kellison and others

1988). Fortunately, the practices best suited for

accomplishing these goals are also those best

suited for timber production, wildlife management,

and maintenance of the flora and fauna associated

with the alluvial forest.

Stands that have been harvested repeatedly

often contain two, but rarely more than three

age groups, with each age group dating to a

previous harvest. Even though the species

composition of the older age classes is usually

desirable, a high component of the trees is

culls with no timber value. Conversely, a high

component of the youngest age class of timber

is usually of poor species composition, resulting

from the development of shade-tolerant trees

in the understory of the residual crown classes.

However, many of these stands, especially those

occupying sites of high soil quality, are worthy

of timber stand improvement, in which the

undesirable trees are controlled to release the

desirable trees in the intermediate crown class.

Even-Aged Systems

Experience has shown that stands occupying

major alluvial floodplains will regenerate following

complete harvesting of the timber in a single entry

(clearcutting) or in two entries (shelterwood

cutting). The regeneration from such harvested

stands of trees less than about 100 years old will

be largely from stump and root sprouts (Mader

1990). Stands of an older age class and those with

altered hydrology will largely regenerate from

seed in place at the time of harvest or transported

to the site by wind, water, and fauna. The types

of even-aged regeneration systems having

application to major alluvial floodplains are

clearcutting, patch clearcutting, shelterwood

cutting, and seed-tree cutting.

Clearcutting—Clearcutting of hardwood forests

that have the propensity to regenerate themselves

from stump and root sprouts reduces species

succession almost to the pioneering sere. It is only

one stage short of a catastrophic event such as a

hurricane in which stump and root sprouting of

merchantable timber is severely limited because

of windthrow and perhaps two stages short of

a cleared bottomland field where all initial

regeneration must be from seeds or planting.

In spite of its lack of aesthetic appeal,

clearcutting is often the best way to regenerate

hardwoods, especially degraded or impoverished

stands. The regeneration will largely be from

advanced reproduction and sprouts, but seedling

reproduction will form a part of the succeeding

stand in patches where sprout or advanced

reproduction is absent. Seedling reproduction

has little chance of developing into the succeeding

stand if it occurs 3 or more years after sprout

development. Species succession of advanced

reproduction and sprouts proceeds much as it does

with seedling reproduction, with shade-intolerant

species showing fastest initial growth.

Opposition to clearcutting often results from

the visual impact of the treatment and from

wildlife considerations. We recommend that

the size of clearcuts not exceed 20 acres. This

maintains the silvicultural benefits of clearcutting

while minimizing the adverse aesthetic effects.

Additionally, it is desirable that (1) the harvested

area should be configured to the landscape with

scalloped edges; (2) declining, overmature, or

hollow trees should be left standing for wildlife

purposes (approximately 2 per acre); and (3)

dead and downed trees should be left on site for

associated flora and fauna.

Patch clearcutting—This system is a variation of

clearcutting, with the size of the treated area being

the major difference. The configuration implied is

noncontiguous patches or strips. Areas of about 5

acres are usually considered optimum. Smaller

areas are adversely affected by edge trees,

the influence of which extends into the opening

about the distance of the height of the dominant

trees. The edge trees limit the growth of shadeintolerant species at the expense of shadetolerant ones.

A significant limitation of patch clearcutting

is that it requires frequent stand entry, which

eventually results in many small patches. The

small patches create innumerable problems in
59

stand management and inventory, and they are

poorly suited for forest interior-dwelling birds

and certain other fauna (Sietz and Segers 1993).

Shelterwood cutting—When the shelterwood

system is applied to bottomland hardwoods, best

results are obtained when the overstory canopy

is reduced to about 50 percent of its original cover.

This level of reduction allows sufficient sunlight

to reach the ground to promote seedling and

sprout reproduction.

Experience has shown that clearcutting and

shelterwood cutting initially give rise to similar

types of reproduction, but that the intolerant

species under a shelterwood will start to decline

if the overstory trees are not removed within 5 to

10 years. Shelterwood cuts can help buffer against

rising water tables in areas where the soil water

table has risen as a result of altered hydrology.

In some situations, the shelterwood system is

advocated for the regeneration of oaks, especially

cherrybark oak. Shelterwood cutting is not

always essential for oak regeneration in alluvial

floodplains because species such as water oak and

willow oak (Q. phellos L.) can regenerate equally

well with or without a partial overstory stand

(Leach and Ryan 1987). In deeper water systems,

such as muck swamps, shelterwood systems

appear to be no more effective in developing

the desired reproduction than clearcut systems

(McKevlin and others 1998).

Seed-tree cutting—The prescription for seedtree cutting is to leave four to eight seed trees

per acre while removing all other overstory and

understory trees. The theory is that seeds from

the leave trees will be disseminated over the

area, helping to ensure success in regeneration.

However seed trees are usually a wasted effort in

alluvial floodplains because most heavily harvested

hardwood stands regenerate successfully from

sprouts, from seeds buried in the duff, and from

seeds disseminated by water, wind, and fauna.

The primary reason for leaving such trees is

for wildlife, ecological, and aesthetic values.

Uneven-Aged Systems

Stands of trees of widely different ages can

be maintained by the selection system in which

harvesting, regeneration, and intermediate stand

treatments are applied at the same time. Stands

are entered at intervals of from 1 year to perhaps

every 10 years. Each cutting removes financially

mature and high-risk trees, adjusts stand density

to create room for the best trees to grow, and

makes space for new reproduction. A specific

stand structure is achieved by leaving the desired

basal area levels in several diameter classes.

Single-tree selection—This is the system often

advocated by the opponents of clearcutting or

shelterwood cutting. The ecological basis of the

system is sound, but the application is so difficult

that, in practice, the exercise often approximates

a selective or diameter-limit cut.

Group selection—This variant of single-tree

selection involves removal of groups of trees of

similar age, size, or species on an area usually

not exceeding 0.25 acres. Care must be taken to

remove undesirable as well as desirable trees.

Group selection differs from patch clearcutting

in that it employs small openings and frequent

entries to promote a multiaged stand of shadetolerant species. The necessity to enter the stand

repeatedly at short intervals may make it

impractical to implement the practice.

Two-aged system—We have discussed this

method previously in connection with upland

hardwoods. The method is similarly applicable

to bottomland hardwoods and has the advantage

on wet sites of requiring relatively few entries.

Plantation Management and Restoration

Procedures have been developed for

establishing hardwood plantations on alluvial

floodplains (Malac and Herren 1979). Industrial

foresters have focused on developing eastern

cottonwood (Populus deltoides Bartr. ex Marsh.)

and sycamore (Platanus occidentalis L.)

plantations. Eastern cottonwood has shown more

promise than other species in the Mississippi

River Delta, but sycamore—and to some extent

sweetgum, green ash, water oak, and willow oak—

have proven more adaptable than cottonwood

to some of the other alluvial floodplains of the

South. About 125,000 acres of commercial

hardwood plantations currently exist in southern

bottomlands. Despite successes on the floodplains,

with growth rates of 3 to 4 cords per acre per year

at rotations of 15 to 18 years, the trend is to

establish hardwood plantations outside of the

alluvial floodplains. The causes for this shift

in site location include environmental concerns

and the difficulty of managing and harvesting

the resource in areas with episodic flooding.

Few industrial forestry organizations are willing

to invest in plantation forestry in alluvial

floodplains when there is significant uncertainty

about the implications of the Clean Water Act

for such operations.

Floodplain forest restoration efforts have been

limited, and most have focused on reestablishment

of forest cover for timber, stream protection, or

Chapter 7.

Southern Hardwoods
Southern Forest Science:

Past, Present, and Future

Productivity

60

wildlife habitat values (King and Keeland 1999,

Stanturf and others 1998b). Typically forest

managers have tended to increase the numbers

of certain preferred tree species in the stands

(Chambers and others 1987). In the past 10

to 15 years there has been a preference for

planting oaks (Haynes and others 1995, King

and Keeland 1999), and this practice could result

in a greater occurrence of oak regionally than

was typical of presettlement forests (The Nature

Conservancy 1992). More recently, greater

emphasis has been given to planting a wider

variety of bottomland species (Allen and others

2001, King and Keeland 1999).

Several of the largest reforestation efforts

today are in areas of the Lower Mississippi

River Valley, including parts of the Yazoo National

Wildlife Refuge, the Tensas National Wildlife

Refuge, and the Ouachita Wildlife Management

Area, and on privately owned land enrolled in the

Wetland Reserve Program. About 193,000 acres

have been seeded or planted, with the potential of

494,000 acres being returned to forest by the year

2005 (King and Keeland 1999). Many of the areas

being reforested are on poorly drained lands

cleared for agricultural crops in the 1960s and

1970s and abandoned later because of substandard

crop yields and limited accessibility. Reforestation

and restoration efforts are proving successful in

reestablishing bottomland hardwood species that

may provide commercial timber and wildlife

habitat (Allen and Kennedy 1989, Clewell and

Lea 1990, Haynes and Moore 1988).

Various forest establishment techniques have

been used, including direct seeding of oaks and

planting of seedlings or cuttings of several

bottomland species (Stanturf and others 1998a).

Although direct seeding is about half the cost of

planting seedlings (Bullard and others 1992), the

technique is reliable only for oaks and, to a lesser

degree, other large-seeded species such as pecan

[Carya illinoensis (Wangenh,) K. Koch]. Smaller

seeds are more susceptible to damage by heat

and dry soil. Allen (1990), who compared

4- to 8-year-old stands in the Yazoo National

Wildlife Refuge, concluded that planting of tree

seedlings was more effective than direct seeding in

establishing wildlife habitat quickly. He reported

extensive drought-caused mortality of newly

germinated seeds, even though there was effective

invasion of light-seeded species, especially

sweetgum, green ash, and American elm.

CONCLUSIONS

B

ecause of the ownership characteristics, age

and composition of stands, and the silvical

characteristics of the species present, many

hardwood stands in the South are appropriately

managed by means of intermediate cuttings

(notably improvement cutting and crop-tree

management). The method of harvest regulation

that seems most appropriate to hardwood stands is

volume regulation, since it is more compatible with

partial cutting methods.

Selecting the method of regeneration is more

troublesome. Shelterwood methods, or some

modification of them, are often recommended for

regenerating oaks. If prescribed fire is an option,

it is possible to favor oak regeneration on better

upland sites by employing a shelterwoodburn method.

Clearcutting is an effective way to regenerate

a variety of hardwood species (generally shadeintolerant ones) in both upland and bottomland

forests, while group selection can be used to

regenerate and maintain multiaged hardwood

stands. Plantation silviculture of bottomland

species like cottonwood, sweetgum, and American

sycamore has been successful, but plantations

of upland hardwoods have had limited success.

Maintaining an adaptive strategy to take

advantage of bumper crops of advance

regeneration and to capture value from market

changes is important in hardwood management.

As long as certain rules are followed, such as

matching harvesting with periodic growth,

avoiding high-grading, and providing for

regeneration, southern hardwoods can be

managed sustainably.

The array of premium-grade hardwoods in

the eastern deciduous forest is second to none

in the world (Hicks 1998). The timber from genera

such as Acer, Juglans, Prunus, and Quercus is in

demand for furniture in every developed country.

Therefore the future will be to manage for

premium-grade timber while using the residual

for fiber products. The challenge will be for

professional foresters to convince landowners,

public officials, and environmental advocates to

embrace the practice of proper timber harvesting

on a region-wide scale. Failure to implement

proper silviculture will result in continuation of the

high-grading that has been normal practice since

the inception of timber harvesting in the eastern

deciduous forest. High-quality saw logs and veneer

logs are among the most profitable markets for

hardwoods, but a limitation to the strategy of

managing hardwoods exclusively for premium-
61

grade logs is that it could reduce the emphasis on

hardwood fiber production. This will force many

North American pulp and paper companies to

rely on offshore suppliers for their wood, and

eventually for their pulp. As North American pulp

and paper manufacturing plants become obsolete

from lack of capital investment, they may relocate

closer to the source of the raw material.

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landscape. Gen. Tech. Rep. NE–274. Radnor, PA: U.S.

Department of Agriculture, Forest Service, Northeastern

Forest Experiment Station. 129 p.
63

Chapter 8.

The Evolution of

Pine Plantation Silviculture

in the Southern United States

Thomas R. Fox, Eric J.

Jokela, and H. Lee Allen1

Abstract—In the 1950s, vast acreages of cutover

forest land and degraded agricultural land existed

in the South. Less than 2 million acres of southern

pine plantations existed at that time. By the end

of the 20th century, there were 32 million acres of

southern pine plantations in the Southern United

States, and this region is now the woodbasket

of the world. The success story that is southern

pine forestry was facilitated by the application of

research results generated through cooperative

work of the U.S. Department of Agriculture Forest

Service, southern forestry schools, State forestry

agencies, and forest industry. This chapter reviews

the contributions of applied silvicultural research

in land classification, tree improvement, nursery

management, site preparation, weed control, and

fertilization to plantation forestry in the South.

These practices significantly increased productivity

of southern pine plantations. Plantations established

in the 1950s and 1960s that produced < 90 cubic

feet per acre per year have been replaced by

plantations established in the 1990s that are

producing > 400 cubic feet per acre per year.

Southern pine plantations are currently among

the most intensively managed forests in the world.

Growth of plantations managed using modern,

integrated, site-specific silvicultural regimes rivals

that of plantations of fast-growing nonnative

species in the Southern Hemisphere. Additional

gains in productivity are likely as clonal forestry

is implemented in the South. Advances in forest

biotechnology will significantly increase growth

and quality of future plantations. It appears likely

that the South will remain one of the major

wood-producing regions of the world.

INTRODUCTION

P

ine (Pinus spp.) plantation silviculture in the

Southern United States is one of the major

success stories for forestry in the world.

In 1952, there were only 1.8 million acres of pine

plantations in the South (fig. 8.1), containing 658

million cubic feet of timber (U.S. Department

of Agriculture, Forest Service 1988). At the turn

of the 21st century, there are 32 million acres of

pine plantations in the South that contain 23.9

billion cubic feet of timber (Wear and Greis 2002).

Perhaps more remarkable is the significant

increase in productivity that occurred during

this period (fig. 8.2). Mean annual increment of

pine plantations has more than doubled, and

rotation lengths have been cut by > 50 percent.

The success of pine plantation silviculture has

turned the South into the woodbasket of the

United States (Schultz 1997).

These remarkable changes in the last 60 years

were the result of a variety of factors that came

together at the end of World War II. Economic

factors, including a declining agricultural economy

coupled with a rapidly expanding pulp and paper

industry based on southern pine, combined to

provide the impetus for the large increase in

southern pine plantations. The success of this

effort was due in large part to the cooperative

research and technology transfer efforts of many

organizations, including the U.S. Department of

Agriculture Forest Service (Forest Service), State

forestry agencies, forestry programs at southern

universities, and forest industry.

The objectives of this chapter are to describe

the evolution of southern pine plantation

silviculture over the last 50 years and to outline

our view of the current state of the art of pine

plantation silviculture in the South. Rather than

present an exhaustive review of the literature,

1

 Associate Professor of Forestry, Virginia Polytechnic Institute

and State University, Department of Forestry, Blacksburg, VA

24061; Professor of Forestry, University of Florida, School of

Forest Resources and Conservation, Gainesville, FL 32611;

and C.A. Schenck Distinguished Professor of Forestry, North

Carolina State University, Department of Forestry, Raleigh,

NC 27695, respectively.
Southern Forest Science:

Past, Present, and Future

Productivity

64

0

5

10

15

20

25

30

35

1952 1962 1970 1977 1985 1999

Plantation area

(million acres)

Year

0

50

100

150

200

250

1940 1950 1960 1970 1980 1990 2000 2010

Total yield (tons per acre)

0

10

20

30

40

50

60

Rotation age (years)

Total yield Pulpwood rotation age

Year

0

50

100

150

200

250

1940 1950 1960 1970 1980 1990 2000 2010

Establishment period

Volume at harvest

(tons per acre)

Clonal and biotech

Tree improvement

Weed control

Fertilization

Site preparation

Planting

Natural stand

we will highlight what we believe are the major

advances during the last 50 years and illustrate

their contribution to the productivity gains that

have been observed during this time (fig. 8.3). As

part of this, we hope to demonstrate the significant

contributions that applied coop-erative research

has made to this success story.

SETTING THE STAGE FOR PLANTATION

FORESTRY IN THE SOUTH

C

learing of forests for crop production occurred

throughout the Coastal Plain and Piedmont

from the colonial period until the beginning

of the Civil War (Williams 1989). In Virginia > 25

million acres, or 47 percent of the total land area

in the State, had been cleared by 1860. Soil erosion

was a serious problem associated with production

of cotton and tobacco, which were the most

important agricultural crops throughout the

South (Bennett 1939). Declining soil productivity

due to erosion, accompanied by low prices for cash

crops and pest problems such as the boll weevil

(Anthonomus grandis grandis), caused large

amounts of agricultural land to be abandoned

throughout the South between the end of the

Civil War and World War II.

The South has been an important source of

timber and forest products since colonial times

(Williams 1989). Other than timber for local use,

the first major products from southern forests

were naval stores from longleaf pine (P. palustris

Mill.) and ship timbers from live oak (Quercus

virginiana Miller) (Butler 1998, Williams 1989).

Figure 8.1—Number of

acres of pine plantations

in the Southern United

States from 1952 to

1999 (data from U.S.

Department of

Agriculture 1988,

Wear and Greis 2002).

Figure 8.2—Estimated

total yield and pulpwood

rotation age in pine

plantations in the

Southern United States

from 1940 through 2010.

Figure 8.3—Estimated

contributions of intensive

management practices to

productivity in pine

plantations in the

Southern United States

from 1940 through 2010.
65

The production of lumber in the South increased

gradually following the Civil War and more

dramatically beginning in the 1880s and 1890s,

when available timber in the Lake States was

depleted. Between 1890 and 1920, the South was

the major lumber-producing region in the country.

Production peaked at approximately 140 billion

board feet in 1909, when the South produced 46

percent of all timber cut in the United States

(Williams 1989). After 1909, lumber production

declined gradually until the start of the Great

Depression in 1929, when production fell sharply.

The discovery by Charles Herty that acceptable

pulp and paper could be made from southern

pine had a dramatic impact on southern forestry

beginning in the 1930s (Reed 1995). A rapid

increase in the pulp production in the South

followed this discovery (Josephson and Hair 1956).

Numerous pulp and paper mills were constructed

throughout the South during the 1930s, increasing

the demand for smaller diameter southern pine

timber. Pulp and paper companies purchased large

tracts of timberland during this period to provide

pulpwood for these new facilities (Williams 1989).

At the start of the 20th century, almost no effort

was devoted to reforestation following timber

harvest (Williams 1989). Destructive fires often

followed logging, killing much of the natural

regeneration that might otherwise have become

established on many cutover tracts. During the

1920s, the Forest Service recognized the need

for large-scale tree planting in the South and

began a research program to address reforestation

issues. The first large-scale planting of southern

pine occurred between 1920 and 1925 when the

Great Southern Lumber Company planted

approximately 7,000 acres near Bogalusa, LA

(Wakeley 1954). During the 1920s, the Forest

Service also began its reforestation program in

the South with the planting of 10,000 acres in the

Sumter National Forest in South Carolina. During

the 1930s, the Civilian Conservation Corps planted

> 1.5 million acres across the South. The success

of these early efforts demonstrated the feasibility

of establishing pine plantations.

THE ADVENT OF PLANTATION FORESTRY

A

t the end of World War II, the legacy of

abusive agricultural practices that had

degraded soil productivity to the point where

crop production was no longer profitable, coupled

with exploitative timber harvesting without

provision for regeneration, left the South with a

substantial acreage of land requiring reforestation.

Commenting on the situation in the 1950s,

Wahlenberg (1960) stated, “Much land suitable

for loblolly pine that has been made unproductive

through heavy cutting, wildfire, natural

catastrophe, or abandonment of agriculture is in

need of planting.” Wakeley (1954) estimated that

there were 13 million acres of land requiring

planting in the South in 1950.

Tree planting in the South, which had nearly

ceased during World War II, rapidly increased in

the years immediately following the war (U.S.

Department of Agriculture, Forest Service 1988).

A large percentage of this planting occurred on

farmland associated with the Soil Bank Program

of the 1950s. The successful reforestation of

abandoned and degraded agricultural land

illustrated the conservation value of trees and

their role in reducing soil erosion and improving

water quality (Bennett 1939). The rapid expansion

of the pulp and paper industry in the South during

the 1930s increased the demand for pine pulpwood

and stimulated planting on forest industry land.

By this time, the superior growth and yield of

pine plantations relative to naturally regenerated

stands had become evident. For example, the

original plantations established by Great Southern

Lumber Company clearly showed the potential

value of fully stocked plantations compared to the

poorly stocked naturally regenerated stands that

were the norm at the time (Wakeley 1954).

NURSERY PRACTICES AND

SEEDLING HANDLING

A

rtificially regenerating the large

acreages found in the South required an

abundant supply of high-quality seedlings. A

concerted research effort of the Forest Service on

reforestation in the South began in the 1920s and

culminated with the publication of Agricultural

Monograph 18 “Planting the Southern Pine”

(Wakeley 1954). This classic publication provided

foresters detailed information on seed collection

and processing, seedling production, and planting

practices needed to successfully establish southern

pine plantations. With its publication, the stage

was set for the rapid expansion of southern

pine seedling production. In 1950, the Forest

Service, the Soil Conservation Service, the

Tennessee Valley Authority, and all States in

the South operated forest nurseries to produce

pine seedlings for reforestation activities on

public and private land (U.S. Department of

Agriculture, Forest Service 1949). Many industrial

organizations also began to establish or expand

nurseries to meet their seedling needs at this time.

Chapter 8.

 Pine Plantation Silviculture
Southern Forest Science:

Past, Present, and Future

Productivity

66

Wakeley (1954) developed a widely used

grading system for southern pine seedlings based

on seedling height, root-collar diameter, and stem

and needle characteristics that were correlated

with seedling survival. However, seedling survival

was a continuing problem throughout the South

during the 1950s, 1960s, and 1970s (Dierauf 1982).

Although many of the factors affecting seedling

survival, such as weather, insects, and disease,

were thought to be difficult to control, the problem

received considerable attention because of the

relative scarcity and high cost of genetically

improved seed. The formation of the Auburn

Southern Forest Nursery Management

Cooperative in 1970 highlights the importance

placed on improving nursery practices and

seedling quality. Root characteristics of seedlings,

including root:shoot ratio and the number of firstorder lateral roots, were demonstrated to be

important factors affecting seedling performance

(Carlson 1986). Improved nursery practices, such

as sowing seed by size class and single family

groups, reducing nursery bed density, top pruning,

root pruning, increasing nitrogen (N) fertilization,

and mycorrhizal inoculation, were incorporated

into standard operating procedures at most pine

seedling nurseries, substantially improving the

size and quality of the seedlings produced (Mexal

and South 1991). Although seedling survival is

still probably best correlated with root-collar

diameter (South 2000), physiological criteria such

as root growth potential were also developed to

better evaluate seedling quality (Johnson and

Cline 1991). Proper care and handling of seedlings

during lifting and transport to the planting site

were found to be the critical factors ensuring

initial survival and growth of seedlings (Dierauf

1982, U.S. Department of Agriculture 1989). The

use of refrigerated vans for seedling storage and

transport, now widespread throughout the South,

was probably the single most important factor

in making certain that seedlings arrive at the

planting site in good condition. Improved survival

and growth also occurred when larger seedlings

were planted deeper and earlier in the season;

i.e., prior to December (South 2000). Today,

improved nursery practices, together with

proper care and handling of seedlings during

transport, storage, and planting, have increased

survival rates for planted seedlings to levels

commonly > 90 percent.

Tree Improvement and Genetic Gain

A major limitation on seedling production in

the 1950s was the absence of reliable supplies of

high-quality seed from desirable sources (Squillace

1989). Geographic variation in seed sources was

known to affect growth of southern pine, with local

sources outgrowing more distant sources (Wakeley

1944). Therefore, use of local seed, collected within

100 miles of the planting site, was recommended

for reforestation (McCall 1939). At that time, most

seed was obtained from cones collected from trees

felled during logging of natural stands (Wakeley

1954). In order to provide a more consistent

supply of cones, seed production areas were often

established in natural stands containing good

phenotypes (Goddard 1958).

The seed orchard concept was proposed as

early as the late 1920s as means of producing

genetically improved seed (Bates 1928). The high

cost of establishing and managing seed orchards

was initially a major obstacle to their widespread

use (Perry and Wang 1958), because it was not

widely accepted that genetic improvement through

selection and breeding would lead to significant

gains in the growth of southern pine (Wakeley

1954). This view began to change in the 1950s

as evidence supporting the value of genetic

improvement in forest trees started to emerge

(Lindquist 1948, Schreiner 1950). The value

of genetically improved seed was finally

recognized when it was demonstrated that the

costs associated with seed orchards could be

economically justified (Perry and Wang 1958).

Bruce Zobel, on behalf of the Texas Forest

Service and in cooperation with 14 forest

products companies, formed the first tree

improvement program in the South (Zobel and

Talbert 1984). The formation of this industryuniversity-Government applied research

cooperative was a major event in southern pine

plantation forestry. The future success of southern

pine plantation forestry was in large part a direct

result of the applied research conducted through

cooperative programs at universities throughout

the South. Additional tree improvement research

cooperatives were soon founded at the University

of Florida in 1953 and North Carolina State

University in 1956 (Southern Industrial Forest

Research Council 1999).

The seed orchard concept quickly gained favor

and became the preferred method of producing

southern pine seed (Zobel and others 1958). The

first southern pine seed orchard was established

by the Texas Forest Service in 1952 to produce

drought-hardy loblolly pine (P. taeda L.) (Zobel

1953). Industrial members of the University of

Florida Cooperative Forest Genetics Research

Program began establishing slash pine (P. elliottii

Engelm. var. elliottii) seed orchards in 1953 (Wang
67

0

10

20

30

40

50

60

Percent volume gain value

compared to natural population

First

generation

Natural Second

generation

Open pollinated

Control

pollinated

and Perry 1957). By 1987, > 9,700 acres of seed

orchards had been established in the South, and

> 85 percent of the trees planted in the South

originated from improved seed produced in seed

orchards (Squillace 1989).

Tree improvement programs in the South

focused primarily on improving volume growth,

tree form, disease resistance, and wood quality

(Dorman 1976, Zobel and Talbert 1984). Because of

the length of time required for tree breeding and

testing, the gains in wood production due to tree

improvement were not fully realized for several

decades (Todd and others 1995, Zobel and Talbert

1984). Seed from first-generation seed orchards

became available in large quantities in the 1960s

and early 1970s. When these plantations matured

in the 1980s, they produced 8 to 12 percent more

volume per acre at harvest than trees grown

from wild seed (Squillace 1989). The increased

financial value of plantations established with

first-generation improved seed probably exceeded

20 percent when gains from other traits such as

stem straightness, disease resistance, and wood

density were included (fig. 8.4) (Todd and others

1995). Continued breeding and testing led to the

development of second-generation orchards in

1980s. Second-generation seed orchards currently

produce more than 50 percent of the seed in

the South. It is estimated that volume growth

in current plantations will be 14 to 23 percent

greater than in plantations established using firstgeneration material (fig. 8.4) (Li and others 1997).

MECHANICAL SITE PREPARATION

B

efore the 1950s, planting was generally

limited to old fields and grassy savannas

that originated on cutover sites following

frequent wildfires. Most cutover pine sites in the

South were regenerated after harvest by leaving

six to eight seed trees per acre (Duzan 1980).

Unfortunately many of these stands failed to

regenerate pine adequately due to competition

from hardwoods. The inconsistent results

obtained with natural regeneration led to trials

with clearcutting and planting. Foresters faced

considerable obstacles in their attempt to convert

these natural stands of mixed pine and hardwoods

to plantations after harvest. Lack of markets for

low-grade hardwoods often led to poor utilization

that left large numbers of nonmerchantable stems

and heavy logging slash on the site. This inhibited

planting and, coupled with the rapid regrowth of

hardwoods, led to poor survival and growth of

seedlings planted in the rough.

Initially, little site preparation was done because

of the cost (Shoulders 1957). However, the need

for site preparation was highlighted by the failure

of many plantations established on cutover sites,

which was in stark contrast to the success of

plantations established on old agricultural fields

and grassy savannas. The old-field effect on

improved survival and growth was attributed to

various factors, including low levels of competing

hardwood vegetation, improved soil physical

properties, and improved soil fertility due to

residual fertilizer and lime. Therefore, the aim

of site preparation was to re-create these oldfield conditions on cutover sites using various

mechanical means such as anchor chaining,

chopping, burning, root raking, shearing, and

disking. Mechanical site preparation practices

often evolved more rapidly through trial and

error by field foresters and equipment

manufacturers than through formal research

and development efforts.

The most consistent thread in the

development of site preparation practices

on upland cutover sites in the South was the

need to control competing hardwood vegetation

(Haines and others 1975). Roller-drum choppers

were introduced as a site preparation tool

in the middle 1950s and quickly gained

popularity. Chopping, especially when followed

by prescribed fire, reduced logging slash and

residual nonmerchantable stems and, thus,

improved access to the site for planting (Balmer

and Little 1978). However, chopping did not

effectively control competing hardwood

vegetation. Disk harrows were first employed

in the late 1950s to provide soil tillage similar to

that found in old fields and to control hardwood

sprouting. However, the level of hardwood

control achieved following harrowing was often

Figure 8.4—Growth increases in southern pine

plantations due to tree improvement practices in the

Southern United States (adapted from Li and others

1997, Todd and others 1995).

Chapter 8.

 Pine Plantation Silviculture
Southern Forest Science:

Past, Present, and Future

Productivity

68

disappointing (Duzan 1980). The intensity of

mechanical site preparation continued to increase

during the 1960s and 1970s in pursuit of the

desired old-field conditions, culminating in the

widespread use of shearing, windrowing, and

broadcast disking as the standard practice

throughout much of the Piedmont and upper

Coastal Plain (Haines and others 1975, Wells and

Crutchfield 1974). Large bulldozers were used in

this three-pass system. Residual stems and stumps

were first sheared near the groundline using a KG

blade. The slash and logging debris were raked

into piles and windrows. Unless great care was

taken, the forest floor and topsoil were often raked

into the piles and windrows along with the slash.

The area was then broadcast disked with a large

harrow. In many cases, the windrows and piles

were then burned after the debris dried. The

improved survival and early growth of seedlings

planted on these intensively prepared sites,

coupled with the greatly reduced hardwood

sprouting, suggested that foresters had finally

achieved the holy grail of site preparation—

turning cutover sites into old fields.

Foresters in the lower Coastal Plain faced a

different set of problems than their counterparts

in the Piedmont. In addition to the concerns with

the control of competing vegetation, the presence

of poorly drained soils with high seasonal water

tables greatly affected survival and growth of

planted seedlings. The widespread conversion of

swamps into productive agricultural lands through

intensive drainage clearly demonstrated the value

of removing excess water from wet sites for crop

production (Wooten and Jones 1955). The first

large-scale drainage project for forestry in the

South occurred in the Hofmann Forest in eastern

North Carolina in the late 1930s. By the 1950s the

improved growth of loblolly and slash pine planted

adjacent to drainage canals was clearly evident

(Maki 1960, Miller and Maki 1957, Schlaudt 1955).

The phenomenal growth response of planted

pines following drainage reported in a number

of studies, ranging from 80 percent to almost

1,300 percent (Terry and Hughes 1975), led to the

widespread drainage of forested wetlands in the

Atlantic and Gulf Coastal Plain in the late 1960s

and early 1970s. Large draglines were used to

construct sophisticated drainage systems including

primary, secondary, and third-stage ditches that

removed excess water and, thus, improved access,

reduced soil disturbance during harvesting, and

improved survival and growth of planted seedlings

(Terry and Hughes 1978).

As on upland sites, reducing logging debris

and controlling competing hardwood vegetation

were major objectives of site preparation on wet

soils in the Coastal Plain. Chopping, burning,

KG shearing, windrowing, and root-raking

practices evolved much as they had on upland

sites. However, seasonally high water tables and

flooding limited the survival and growth of planted

seedlings on poorly drained soils, even when

harrowing was combined with intensive debris

clearing (Cain 1978). Even on drained sites,

reduced evapotranspiration rates in young

plantations led to extended periods when the soils

were saturated during the winter, which decreased

seedling survival and growth (Burton 1971).

The improved growth of seedlings on elevated

microtopography with improved soil aeration

(McKee and Shoulders 1970) led to the

development of bedding in the Coastal Plain.

The first bedding was done with fire plows

modified to produce a raised planting site for

seedlings (Bethume 1963, Smith 1966). Specialized

bedding plows were introduced in the 1960s,

and bedding soon became the standard site

preparation practice on poorly drained soils,

based on the superior growth observed on bedded

compared to flat-planted sites (McKee and

Shoulders 1974, Terry and Hughes 1975, Wells

and Crutchfield 1974). Because slash interferes

with bedding and decreases the quality and height

of the beds, intensive land clearing, often involving

KG shearing and windrowing, was usually

conducted on sites requiring bedding to ensure

that quality beds were formed (Duzan 1980).

Effective bedding treatments improved surface

soil tillage and soil aeration, and reduced shrub

competition. In some cases double bedding, using

two passes of the bedding plow, was required to

achieve the conditions needed to ensure superior

survival and growth of planted seedlings.

CONCERN OVER SUSTAINABILITY AND

ENVIRONMENTAL IMPACTS OF INTENSIVELY

MANAGED PLANTATIONS

T

he intensity of site preparation conducted in

both the Piedmont and the Coastal Plain to

simulate old-field conditions soon generated

concern about long-term site productivity. A report

by Keeves (1966) on second-rotation productivity

declines in radiata pine (P. radiata D. Don) on

intensively prepared sites in Australia, apparently

caused by heavy windrowing, stimulated great

interest in the South. Subsequent work with

radiata pine in New Zealand confirmed that
69

windrowing on sandy soils induced severe nutrient

deficiencies that would degrade site quality

(Ballard 1978). Foresters throughout the South

observed the wavy height growth pattern in

windrowed plantations where trees adjacent to

the windrows were considerably taller than trees

between the windrows. A large windrow effect

on growth of loblolly pine was documented in the

North Carolina Piedmont (Fox and others 1989,

Glass 1976). Windrowing decreased site index by

11 feet in this loblolly pine plantation. As in New

Zealand and Australia, it was demonstrated that

declines in growth observed on windrowed sites

were caused by nutrient deficiencies due to

displacement of the forest floor and topsoil from

the interior of the stand to the windrows (Morris

and others 1983, Vitousek and Matson 1985).

These observations led to the search for

alternative, less intensive site preparation

treatments that would maintain site quality

(Burger and Kluender 1982, Tippin 1978).

Nutrient losses associated with intensive

whole-tree harvesting also generated much

concern during this period. Nutrient budget

calculations seemed to suggest that wholetree harvesting would deplete soil nutrient

reserves, particularly such elements as calcium,

and consequently degrade site quality (Ballard

and Gessel 1983, Mann and others 1988).

Numerous studies comparing conventional boleonly harvests with whole-tree harvests were

installed in response to this concern. Longterm analysis of these studies eventually revealed

that whole-tree harvesting had no detrimental

effects on soil nutrient levels or site productivity

on most sites if the slash and logging debris were

left on site (Johnson and Todd 1998). Where

excessive soil disturbance during harvest and site

preparation did have negative effects, ameliorative

treatments such as soil tillage and fertilization

restored productivity in nearly all cases (Fox 2000,

Nambiar 1996).

Because long-term site productivity was

closely tied with organic matter and N availability,

harvesting and site preparation treatments were

modified during the 1980s to leave as much organic

matter on site as possible. The goal was to obtain

the amount of soil tillage required to achieve

acceptable seedling survival while leaving most

of the logging slash and forest floor on site (Morris

and Lowery 1988). The link between improved

harvest utilization and site preparation led to

more integrated harvesting and site preparation

regimes (Burger and Kluender 1982). In the

Piedmont, the desire to minimize soil disturbance

during site preparation, concerns over nutrient

losses and long-term site productivity, and

the availability of newly developed herbicides

that effectively controlled hardwood sprouts

combined to shift most of the site preparation

from mechanical to chemical treatments. In the

Coastal Plain, mechanical treatments were

modified so that sites could still be bedded with

larger amounts of slash and logging debris left

on site. V-blades were developed that pushed

aside logging debris and cleared a path for

bedding plows without removing organic matter

and nutrients from the site. Also, larger bedding

plows were developed that cut through thick root

mats and residual slash while still creating wellformed beds that elevate seedlings above high

water tables, thus reducing the need for

windrowing on poorly drained sites.

The impacts of intensive forest management

on water quality have long been an important

issue in the South. The large amount of bare soil

exposed following harvest and site preparation

often led to increased erosion on steeply sloping

land in the Piedmont (Nutter and Douglass

1978). The work of Coile and Schumaker (1964)

demonstrated the correlation between topsoil

depth and site quality in the Piedmont. Given

the degraded site quality in most of the Piedmont

caused by the past agricultural practices,

additional losses of topsoil by erosion following

harvest and site preparation were a concern.

There were also concerns about the offsite

environmental impacts of intensive harvesting and

site preparation. Increased erosion and movement

of sediment that increased turbidity in streams

became a major issue with the amendment of the

Federal Water Pollution Control Act in 1972, which

for the first time regulated forestry activities as

nonpoint sources of pollution. Best Management

Practices (BMP) were developed in all the

Southern States in response to this legislation

to minimize soil erosion and offsite movement

of sediment from forestry activities (Cubbage

and others 1990). These BMPs have proven to

be very effective at reducing nonpoint sources of

pollution from forestry activities when properly

implemented (Aust and others 1996). Although

voluntary in most States, compliance with BMPs is

uniformly high today in forestry operations across

the South (Ellefson and others 2001).

Chapter 8.

 Pine Plantation Silviculture
Southern Forest Science:

Past, Present, and Future

Productivity

70

0

5

10

15

20

25

30

35

40

45

Check Woody Herb Total

Total volume (tons per acre)

Competition control (herbicides)

CONTROLLING COMPETING VEGETATION

T

he detrimental effects of hardwood

competition on growth and yield of southern

pines were recognized from the earliest

days of plantation forestry (Cain and Mann

1980, Clason 1978, Duzan 1980). One of the main

objectives of site preparation was to create oldfield conditions where hardwood competition

was absent. However, chemical site preparation

was not widely used during this period, generally

because the poor utilization during harvest

required mechanical methods to provide

acceptable access to the site (Lowery and

Gjerstad 1991). Unfortunately on most cutover

sites, mechanical site preparation alone did not

effectively control hardwood sprouting. In the

absence of follow-up release treatments, many

plantations turned into low-quality hardwood

stands with scattered, poorly growing pines

(Duzan 1980). During the 1960s and 1970s,

2,4,5-T was widely used to release young pine

plantations from competing hardwoods, because

it was inexpensive to apply and effective on many

species of hardwoods, and pines were resistant

to the herbicide (Lowry and Gjerstad 1991).

The registration of 2,4,5-T for forestry uses

was cancelled in 1979. At that time, both hardwood

release treatments and chemical site preparation

essentially ceased for a number of years in the

South. However, concerns about sustainability

of the long-term productivity of sites that were

intensively prepared mechanically, and concerns

about hardwood sprouting on less intensively

prepared sites, fostered the search for herbicides

that could replace 2,4,5-T (Fitzgerald 1982).

The Auburn University Silvicultural Herbicide

Cooperative was formed in 1980 to identify and

test herbicides suitable for use in forestry.

Numerous trials were established to evaluate

herbicide efficacy and document the growth

response of pines following herbicide application.

Several alternative herbicides such as glyphosate

(Roundup®, Accord®), hexazinone (Velpar®),

imazapyr (Arsenal®), sulfometuron methyl

(Oust®), and triclopyr (Garlon®) were soon

registered for forestry uses. The newer

compounds were more environmentally benign,

with low mammalian and fish toxicity, rapid

degradation, and minimal offsite movement

(Neary and others 1993). Hardwood control

in pine plantations using these newer herbicides

was generally more successful than previous

treatments with herbicides such as 2,4,5-T

(Minogue and others 1991).

The use of herbicides for site preparation

began to increase as results from studies of the

newer herbicides revealed that these compounds

effectively controlled hardwood sprouting

(Fitzgerald 1982, Miller and others 1995) and,

thus, increased pine growth (fig. 8.5). Chemical

site preparation expanded rapidly when it was

discovered that similar or better growth occurred

at a lower cost on chemically prepared sites

compared to mechanically prepared sites (Knowe

and others 1992). By the 1990s, chemical site

preparation had replaced mechanical site

preparation on most upland sites (Lowery and

Gjerstad 1991) and is currently the dominant

form of site preparation in the Piedmont and

upper Coastal Plain.

Although the effect of hardwood competition

on pine growth was well documented (Cain and

Mann 1980, Clason 1978), the effect of herbaceous

vegetation in young pine stands was not well

known in the 1960s, because herbicides that

effectively controlled grasses and other

herbaceous vegetation without damaging pine

seedlings were not available. However, mechanical

weeding experiments in young pine plantations

showed that height growth of seedlings increased

significantly following control of grass and

herbaceous vegetation (Terry and Hughes 1975).

With the advent of newer herbicides such as

hexazinone in the 1970s that effectively controlled

herbaceous weeds without damaging young pine

seedlings, large and consistent growth responses

following herbicide applications were widely

observed (Fitzgerald 1976, Holt and others 1973,

Nelson and others 1981). By the late 1980s, it

was clear that herbaceous weed control had a

long-term impact on pine growth (fig. 8.5) (Glover

and others 1989, Smethurst and Nambiar 1989).

Control of herbaceous weeds during the first

growing season was soon a widespread practice

in pine plantations throughout the South (Minogue

and others 1991). Figure 8.5—Effect of competition control on growth of loblolly

pine at age 8 (adapted from Miller and others 1995).
71

0

2

4

6

8

10

12

14

16

18

0 100 200 300

N rate (pounds per acre)

Volume response

(tons per acre)

Loblolly (+ 50 pounds per acre P)

Loblolly (no phosphorus)

Slash (+ 50 pounds per acre P)

Slash (no phosphorus)

Slash

ACCELERATING GROWTH BY FERTILIZATION

E

ven though a considerable body of research on

forest soil fertility, tree nutrition, and response

to fertilizers existed showing that growth

increases following fertilization were possible

(Walker 1960), forest fertilization did not develop

as an operational silvicultural practice until the

1960s. Operational deployment was hampered by

an inability to accurately identify sites and stands

that consistently responded to fertilization. A

major breakthrough occurred with the discovery

of spectacular growth responses in slash pine

following phosphorus (P) additions on poorly

drained clay soils, locally called gumbo clay, in

the flatwoods of Florida (Laird 1972, Pritchett

and others 1961). Volume gains of up to 5 tons per

acre per year over 15 to 20 years were observed

on similar soils throughout the Coastal Plain

(Jokela and others 1991a). The long-term growth

response following P fertilization on these gumbo

clays translated into 5- to 15-foot increases in site

index. When foresters learned to identify these

P-deficient sites and prescribe appropriate

fertilizer applications, fertilization emerged as

an operational treatment (Beers and Johnstono

1974, Terry and Hughes 1975). Typically, optimal

growth responses were achieved on these sites

when approximately 50 pounds per acre of

elemental P was added at the time of planting

(Jokela and others 1991a).

Results from fertilizer trials on other soil

types in the Coastal Plain and Piedmont were

encouraging, but they remained somewhat

inconsistent (Pritchett and Smith 1975). This

inconsistency limited further expansion of forest

fertilization programs. The Cooperative Research

in Forest Fertilization (CRIFF) Program at the

University of Florida and the North Carolina State

Forest Fertilization Cooperative were formed

in 1967 and 1970, respectively, to address this

problem. Researchers in these two programs

and the Forest Service worked to identify reliable

diagnostic techniques to identify sites and stands

that responded to fertilization. Diagnostic

techniques including soil classification, soil and

foliage testing, visual symptoms, and greenhouse

and field trials were developed to help foresters

decide whether or not to fertilize (Comerford

and Fisher 1984; Wells and others 1973, 1986).

The soil classification system developed by the

CRIFF Program proved to be an effective tool

for determining the likelihood of obtaining an

economic growth response following fertilization

and was adopted widely (Fisher and Garbett

1980). Critical foliar concentrations for N and P

were identified for slash and loblolly pine that

were well correlated with growth response

following fertilization (Comerford and Fisher

1984, Wells and others 1973).

Field trials conducted by both the North

Carolina State Forest Fertilization Cooperative

and the CRIFF Program, initiated in the 1970s

and 1980s, revealed that growth of most of the

slash and loblolly pine plantations in the South

were limited by the availability of both N and

P (Allen 1987, Fisher and Garbett 1980, Gent

and others 1986, Jokela and Stearns-Smith

1993, North Carolina State Forest Nutrition

Cooperative 1997). This work confirmed that a

large and consistent growth response following

midrotation fertilization with N (150 to 200

pounds per acre) and P (25 to 50 pounds per acre)

occurred on the majority of soil types (fig. 8.6).

Growth response following N plus P fertilization

averaged 75 cubic feet per acre per year on poorly

drained soils and 69 cubic feet per acre per year

on well-drained soils, which represents a growth

increase of approximately 25 percent (North

Carolina State Forest Nutrition Cooperative

1997). These responses have typically lasted for

at least 6 to 10 years, depending on soil type,

fertilizer rates, and stand conditions. Based

on these results, the number of acres of southern

pine plantations receiving midrotation fertilization

with N and P increased from 15,000 acres annually

in 1988 to approximately 975,000 acres in

2000 (North Carolina State Forest Nutrition

Cooperative 2001). By the end of 2000, > 11.1

million acres of southern pine plantations had

been fertilized in the United States since 1969.

Figure 8.6—Growth response of loblolly and slash pine

on a variety of soil types following midrotation application

of nitrogen (N) and phosphorus (P) fertilizer (adapted from

North Carolina State Forest Nutrition Cooperative 1997).

Chapter 8.

 Pine Plantation Silviculture
Southern Forest Science:

Past, Present, and Future

Productivity

72

DEVELOPMENT OF FOREST

SITE CLASSIFICATION

S

ite quality is perhaps the single most

important factor affecting growth and yield

of plantations. Merchantable yield tends to

increase in an exponential fashion as site quality

increases. This relationship became more

important in the early 1950s as management

shifted from natural stands to plantations because

the financial returns from the investment in

plantation forestry were insufficient on poorquality sites. Unfortunately in the early years

of plantation forestry in the South, it was often

difficult to assess the quality of many sites

scheduled for planting because they were cutover

and poorly stocked (Coile 1960). This led to a large

effort in the 1950s and 1960s to correlate soil

properties, understory vegetation characteristics,

geology, and landform with forest site quality

(Carmean 1975). Soil properties such as drainage

class, depth to the subsoil, and texture of the

topsoil and subsoil were correlated with loblolly

and slash pine site index (Barnes and Ralston

1955, Coile and Schumaker 1964). The Coile

system of land classification was widely used by

industrial landowners throughout the South to

identify and prioritize sites suitable for planting

(Coile 1960, Thornton 1960).

The need for detailed soil information increases

as management practices become more intensive

(Stone 1975). Growth responses to silvicultural

treatments such as drainage, site preparation,

fertilization, thinning, and weed control were

found to be strongly affected by soil properties

(Fox 1991). For example, growth response to P

fertilization was large and sustained on poorly

drained Ultisols in the lower Coastal Plain, but

was small and inconsistent on sandy Spodosols

in the same landscape (Comerford and others

1983). Soil properties were also found to strongly

influence the efficacy and offsite movement of

herbicides, such as hexazinone, and had to be

taken into account to develop appropriate

prescriptions (Lowery and Gjerstad 1991).

Equipment limitations and the potential for

erosion, compaction, and puddling during harvest

and site preparation were also affected by soil

type (Morris and Campbell 1991).

Specialized soil classification programs

were developed to provide managers with the

information needed to make silvicultural decisions

in intensively managed plantations. The CRIFF

system was created to identify soils most likely to

be nutrient deficient based on soil morphological

properties (Fisher and Garbett 1980). Many

organizations initiated detailed soil mapping

programs to provide foresters with site-specific

information on soil properties considered

important for intensive forest management

(Campbell 1978, Thornton 1960). These soil

surveys were developed specifically for forestry

purposes and have generally proven more useful

than the multipurpose soil maps produced by the

Natural Resources Conservation Service (Morris

and Campbell 1991).

The development of sophisticated Geographic

Information Systems during the 1990s provided

a powerful tool to assist with the implementation

of intensive silvicultural regimes. Spatial analysis

of the growth responses to silvicultural practices

on different soil types enables foresters to make

detailed silvicultural recommendations on a sitespecific basis. Use of Global Positioning Systems

allowed foresters to very accurately determine

their exact location. Armed with these tools,

foresters are now able to make detailed

silvicultural prescriptions on a site-by-site basis.

These site-specific prescriptions are a great

improvement over the general recommendations

previously used.

REALIZING THE GROWTH POTENTIAL

OF SOUTHERN PINE

When planted in the Southern Hemisphere,

slash and loblolly pine were found to grow

significantly faster than in their natural

range (Sedjo and Botkin 1997). Foresters in the

South were puzzled by this phenomenon, and

over the years numerous explanations were put

forward to explain the observed differences in

growth potential between the two regions. For

example, climatic differences, especially lower

nighttime temperatures leading to lower

respiration rates, were often proposed as

explanations for the differences (Harms and

others 1994). In addition, diseases endemic to

the Southern United States, such as fusiform rust

[Cronartium quercuum (Berk.) Miyabe ex Shirai

f. sp. fusiforme (Hedge. & N. Hunt) Burdsall & G.

Snow] and those caused by root pathogens, were

not found in the Southern Hemisphere.

It was also noted that plantation management

practices in the Southern Hemisphere were

usually more intensive than those in the Southern

United States (Evans 1992). Complete removal

of weeds, especially during the first few years of

the rotation, was a standard practice. Fertilizers

were used to correct nutrient deficiencies

throughout the rotation. This was in contrast

to the operational silvicultural practices used in
73

the Southern United States through the 1980s

that focused on reducing costs per acre. Early

herbicide applications, whether for chemical

site preparation, herbaceous weed control, or

hardwood release, usually did not completely

control competing vegetation. Even though

growth response was found to be proportional

to the amount of competing vegetation controlled

(Burkhart and Sprinz 1984, Liu and Burkhart

1994), operational herbicide treatments were

usually based on application rates that achieved

a threshold level of control at the lowest cost.

Similarly, fertilization treatments were generally

limited to a single application during the rotation

to minimize costs (Allen 1987). Perhaps more

importantly, silvicultural treatments were

generally applied as individual, isolated treatments

rather than as part of an integrated system.

Notable in this respect for many organizations

was the debate over the relative value of genetic

improvement and silvicultural treatments for

increasing stand productivity. In the Southern

Hemisphere, it was recognized early on that to

achieve high levels of productivity in southern

pine plantations, genetics and silvicultural factors

must be considered as equal components of an

integrated management system.

Several forward-looking research projects

established during the 1980s provided direct

evidence of the growth potential of intensively

managed southern pine within its native

range. Most notable among these were studies

established by the Plantation Management

Research Cooperative at the University of

Georgia and the Intensive Management Practices

Assessment Center at the University of Florida.

Empirical results from these studies demonstrated

spectacular growth responses of both slash and

loblolly pine following complete and sustained

weed control in combination with repeated

fertilization (Borders and Bailey 2001, Colbert and

others 1990, Neary and others 1990, Pienaar and

Shiver 1993). These results demonstrated that the

growth potential of southern pines was not being

achieved in most operational plantations in the

South, and that growth rates rivaling those in the

Southern Hemisphere could be achieved in the

South through intensive management (table 8.1).

PREDICTING GROWTH AND YIELD IN

SOUTHERN PINE PLANTATIONS

T

hroughout the 1950s and early 1960s,

forest managers were forced to rely on

yield predictions developed for natural stands.

Miscellaneous Publication 50 (U.S. Department

of Agriculture, Forest Service 1929) was the

most widely used source of southern pine volume

predictions at that time. However, it was soon

apparent that stand growth and yield in

plantations differed fundamentally from that

in natural stands. Growth-and-yield models for

southern pine plantations began to appear in

the 1960s in response to the need for improved

growth-and-yield information (Bennett 1970,

Bennett and others 1959, Burkhart 1971, Clutter

1963, Coile and Schumaker 1964). Initially,

plantation growth-and-yield models were wholestand models that simply predicted current stand

yield (Bennett 1970, Bennett and others 1959).

However, more sophisticated models were soon

developed that were able to predict total yield

as well as the diameter distribution of the stand

(Bennett and Clutter 1968, Burkhart and Strub

1974, Smalley and Bailey 1974). These diameter

distribution models, although more complicated

and data intensive, proved to be substantially

more useful tools for forest managers, because

volume of specific products could be estimated

which provided a more accurate estimate of

stand value. In the 1970s, distance-dependent

individual-tree growth models were developed

that incorporated the effects of neighboring

competing trees on growth (Daniels and Burkhart

1975). Distance-dependent tree growth models

should provide better estimates of the impact of

silvicultural practices such as thinning. However,

it has generally been found that diameter

distribution models give results very similar

to those of individual-tree growth models in

most cases with less effort and lower cost

(Clutter and others 1983).

Table 8.1—Growth rates of pines throughout

the Worlda

Location Species Age MAI

years ft3/ac/yr

Costa Rica Pinus caribaea 8 449

New Zealand P. radiata 25 457

Brazil P. taeda 15 429

South Africa P. taeda 22 412

Australia P. taeda 20 302

United States

Florida P. elliottii 20 207

Georgia P. taeda 14 374

MAI = mean annual increment.

a

 Data from Arnold (1995), Evans (1992), Borders and Bailey

(2001), Yin and others (1998).

Chapter 8.

 Pine Plantation Silviculture
Southern Forest Science:

Past, Present, and Future

Productivity

74

Growth-and-yield research in the South

was enhanced tremendously by the work of the

Plantation Management Research Cooperative

that formed at the University of Georgia in 1976

and the Virginia Polytechnic Institute and State

University Growth and Yield Cooperative that

formed in 1979. These two programs have

produced sophisticated and very accurate models

of growth and yield in southern pine plantations.

Models have been developed that accurately

predict the impact of silvicultural practices such

as site preparation (Bailey and others 1982,

Clutter and others 1984), thinning (Amateis and

others 1989, Cao and others 1982), fertilization

(Amateis and others 2000, Bailey and others 1989),

and the impact of hardwood competition on stand

structure and yield (Burkhart and Sprinz 1984,

Liu and Burkhart 1994). Modern growth-andyield models, whether individual tree growth

models or diameter distribution models, can

accurately predict stand-level timber production

in intensively managed pine plantations with a

remarkable degree of precision (Pienaar and

Rheney 1995).

As plantations replaced natural stands,

foresters strove to create a fully regulated forest

that optimized financial returns from the overall

land base under management (Davis 1966). The

introduction of linear programming as a forest

planning tool in the 1960s was a major advance

in this effort (Chappelle 1966, Curtis 1962, Leak

1964). Improvements in computers in the 1960s

made it possible to use linear programming

techniques to solve realistically sized forest

harvest scheduling problems for the first time

(Clutter and others 1983). The development of

the MAX-MILLION linear programming-based

harvest scheduling program (Clutter 1968)

fundamentally changed pine plantation

management throughout the South. For the

first time organizations were able to use this

technique to manage timberland in an organized

and quantitative manner that optimized the

present value of future cash flows. Forest

managers were also able to use these harvest

planning tools to predict the financial returns

from alternative silvicultural regimes that

improved plantation growth. It was soon widely

recognized that increased survival and growth

of plantations resulting from improved genetics,

site preparation, weed control, fertilization, and

density management could significantly increase

the financial returns from forest management.

This realization was the driving factor in the

widespread implementation of intensive

silviculture that occurred in the 1980s and

1990s. The descendants of these original harvest

scheduling models have been revised and

improved to the point where they are now able to

solve the extremely complex harvest scheduling

problems presented by the adjacency and harvest

block size restrictions now imposed on industrial

plantations in the South (Van Deusen 1999).

CURRENT STATE-OF-THE-ART: INTEGRATED,

SITE-SPECIFIC SILVICULTURE

M

anagement of southern pine plantations

in the United States is being transformed

from a relatively extensive system of

planting coupled with isolated individual

treatments to a much more intensive system in

which genetic and site resources are manipulated

in concert to optimize stand productivity.

Heretofore, site quality was viewed as a static

property, and individual treatments were applied

in isolation with little understanding of their

interactions and synergies. Today, management is

moving toward a more fully integrated approach in

which improved genotypes are matched to specific

soil types, and silvicultural treatments, including

site preparation, weed control, and fertilization,

are integrated to maintain optimal water and

nutrient availability throughout the rotation (Allen

and others 1990, Neary and others 1990). With

this approach, site quality is no longer fixed, but

can be improved greatly by proper management.

In the past, most silvicultural decisions were

based primarily on the results of empirical field

trials. An important feature of current state-ofthe-art silvicultural regimes is that they are

now based on both empirical results and an

understanding of the physiological processes

controlling forest productivity. It is now widely

recognized, not only by research scientists

but also by operational foresters, that forest

productivity is determined by the ability of the

forest to capture incoming solar radiation and

convert it to stemwood biomass (Cannell 1989).

Productivity of southern pine plantations is related

to stand leaf area (fig. 8.7), which is controlled

by the genetic potential of the trees and the

availability of light, water, and nutrients (McCrady

and Jokela 1998, Vose and Allen 1991, Vose and

others 1994). Recent research has shown that

nutrient availability, rather than availability

of light or water, most strongly affects leaf

area development and, consequently, controls

productivity on most sites in the South (Albaugh

and others 1998, Colbert and others 1990,

Dalla-Tea and Jokela 1991).
75

Leaf area index

Annual volume growth

Nutrients

Water

Genotype

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40

Site mean volume (tons per acre)

Family mean volume

(tons per acre)

Increasing site quality

A

B

C

In intensively managed plantations, interactions

among silvicultural treatments and genetics are

now recognized. There are also large differences

in growth efficiency among families of both loblolly

and slash pine, and these differences can now be

exploited to improve stand productivity (Li and

others 1991, McCrady and Jokela 1998, Samuelson

2000). The combined effect on growth potential

that results from the use of improved genotypes

and intensive silviculture appears to be at least

additive (McKeand and others 1997). Recent

results from progeny tests demonstrated that

the growth of some better families increased

more than the growth of poorer families as site

quality or silvicultural inputs, or both, increased

(fig. 8.8). Foresters are now using this information

to deploy better genotypes to higher quality sites

that will be managed more intensively.

Foresters now modify silvicultural practices to

take advantage of interactions among treatments

based on a better understanding of their impacts

on site resource availability (Allen and others

1999). As an example, both chemical site

preparation and disking treatments are used to

control competing hardwoods. Although disking

also improves soil physical properties, it is likely

that the combined growth response following

disking coupled with herbicide treatment would be

less than additive. Therefore, chemical treatments

are now substituted for mechanical treatments on

sites where hardwood competition is a severe

problem. In contrast, the growth response

following fertilization coupled with herbicide

control of competing hardwoods might be more

than additive since hardwoods responding to

fertilizer compete more vigorously with the pine

crop tree for light and water (Borders and Bailey

2001, Swindel and others 1988). Weed control plus

fertilization is the most widespread treatment

used to accelerate growth in pine plantations in

the South (Albaugh and others 1998, Colbert and

others 1990, Jokela and others 2000). Fertilization

regimes have been developed that enable foresters

to match nutrient supply with the demand of the

stand. Depending on the soil type, various types

and amounts of fertilizer may be added four or

more times during a 20-year rotation to augment

native soil fertility and maintain high nutrient

availability. These fertilizer applications are

coordinated with site preparation treatments

and weed control as needed during the rotation to

ameliorate soil physical limitations and eliminate

competition for soil water and nutrients, thus

insuring optimal growing conditions for the

designated crop trees throughout the rotation.

Current growth rates in intensively managed

plantations in the South may exceed 350 cubic

feet per acre per year (Borders and Bailey 2001),

which puts them on par with fast-growing

plantations in other parts of the World (table 8.1).

These intensively managed plantations offer

landowners attractive financial returns (Yin and

Sedjo 2001, Yin and others 1998). Although the

costs associated with intensive management are

higher, financial returns from such plantations

are higher because the growth rates are much

greater and the rotation lengths shorter. General

realization of this fact is causing a paradigm shift

in the philosophy of forest landowners in the

South. Current management of pine plantations

is moving away from the traditional focus on

minimizing cost per acre to a new emphasis on

decreasing cost per ton of wood produced. Because

wood costs are usually the single largest cost in

pulp, lumber, and engineered wood production,

minimizing wood cost through intensive

management may be the best way for forest

industry in the South to remain competitive in

global markets.

Figure 8.8—Performance of loblolly pine families

[identifications are (A) 07–56, (B) 08–59, and

(C) 01–64] as site quality increases (adapted

from McKeand and others 1997).

Figure 8.7—Relationship between leaf area index

and growth rate in southern pine plantations.

Chapter 8.

 Pine Plantation Silviculture
Southern Forest Science:

Past, Present, and Future

Productivity

76

Tissue culture

plantlets

Clonal

hedges

Clonal

outplantings Clones selected

Cryopreservation

Embryogenic tissue

Rooted

cuttings

THE FUTURE: CLONAL FORESTRY AND

THE PROMISE OF BIOTECHNOLOGY

B

ecause of the continued increase in the world’s

populations, demand for forest products is

increasing, while large amounts of forest

land are being lost to other land uses such as

urbanization (Wear and Greis 2002) or degraded

(Food and Agriculture Organization of the United

Nations 1997). In addition, timber harvesting in

native forests in many parts of the world is being

restricted. The use of intensively managed

plantations for timber production will have to

increase in the future to meet the increasing

demand for wood and fiber and still reserve

large areas of native forests for conservation

and preservation uses (Sedjo and Botkin 1997).

Implementing integrated site-specific

silvicultural management regimes that optimize

water and nutrient availability throughout the

rotation will remain the paradigm of plantation

forestry in the future. However, at some point the

growth response to some silvicultural treatments

will probably level off. Once a site is weed-free,

no additional growth gains are likely from

additional herbicide application until the weeds

grow back. Current management regimes are

approaching this level of competition control

in some plantations (Yin and others 1998).

However, the future of fertilization may be

somewhat different. As growth rates of forest

stands increase, the demand for nutrients will also

increase. The nutrient supply in most forest soils is

not high enough to meet these increased demands.

Current fertilization regimes focus on maintaining

N and P supply. It is likely that as growth rates

and nutrient demand increase, deficiencies of

nutrients other than N and P will develop in the

South as they have in other parts of the World

(Evans 1992, Gonçalves and Benedetti 2000, Jokela

and others 1991b, Will 1985). Fertilization regimes

in the South will have to be modified to supply

both macronutrients and micronutrients in a

manner that matches nutrient demand of the

stand throughout the rotation. Mechanistic models

of soil nutrient supply, tree demand, and uptake

are being developed for southern pines so that

fertilizer regimes can be optimized for specific

soil types across the region. Significant growth

increases in the future are likely to occur

from this more sophisticated management

of nutrient availability.

The potential gains in future plantations

through genetic manipulation of southern pine

are large. At the turn of the 21st century, most

plantations were still planted with open-pollinated,

half-sib families. Many organizations are moving

toward the use of seed produced by controlled

pollination of elite parents, because this can

increase growth significantly (fig. 8.4). One

drawback of controlled pollination is the additional

expense and time required to produce this seed.

Consequently, the quantity of control-pollinated

seed now available is not sufficient to meet

large-scale reforestation needs. To overcome

this obstacle, rooted cuttings are being used to

multiply the limited number of seedlings available

from controlled pollination (Foster and others

2000). This technology is widely used in other

parts of the world with species such as radiata pine

and eucalyptus (Eucalyptus spp.) and will soon be

operational with southern pine in the United

States.

Clonal forestry holds the greatest promise

for increasing the productivity of southern pine

plantations in the near term. Clonal forestry

relies on vegetative propagation procedures

to mass produce identical copies of selected

individual trees that possess excellent genetic

potential (Gleed and others 1995). Clonal

eucalyptus plantations are widely planted in

the Southern Hemisphere and have dramatically

improved productivity (Arnold 1995). Growth

rates exceeding 600 cubic feet per acre per

year have been documented in clonal eucalyptus

plantations in Brazil (Evans 1992). In addition,

clones with specific wood properties have been

developed to optimize pulp production. The

technology to mass produce clones of southern

pine is still under development and includes the

use of rooted cuttings and somatic embryogenesis.

In the near term, it is likely that some combination

of somatic embryogenesis and rooted cuttings

will prove to be the most economical and efficient

way to produce adequate numbers of southern

pine clones (fig. 8.9). Based on results from clonal

Figure 8.9—Integration of rooted cuttings and somatic

embryogenesis into a clonal forestry program for southern

pines in the United States.
77

plantations in other parts of the world, it will

likely be possible to increase productivity of

southern pine plantations by at least 50 percent

by deploying appropriate clones to specific soil

types and then implementing integrated, intensive

silvicultural regimes. Mean annual increments

> 500 cubic feet per acre per year may soon be

within our reach on selected sites in the South.

In the longer term, prospects for new

developments in forest biotechnology are

bright. Research is revealing the genetic basis

of disease resistance, wood formation, and growth

in southern pine. Molecular markers are being

developed that will substantially increase the

efficiency of conventional tree breeding programs

because they will no longer have to rely on

phenotypic expression of desired traits in longterm field trials (Williams and Byram 2001). The

use of molecular markers is particularly valuable

with complex traits that have low heritability,

which is usually the case in southern pine.

Genetic engineering accomplished by directly

introducing foreign DNA into trees has been

reported in a number of species, including radiata

pine and hybrid poplar (Bauer 1997). The potential

for this technology to dramatically improve wood

properties, disease resistance, and growth rates

of forest trees has been reported widely in both

the technical and popular press. Unfortunately,

although the first successful transgenic trees were

produced in the 1980s (Fillatti and others 1987),

it remains difficult to produce transgenic trees,

especially the southern pines. Numerous hurdles

remain to be overcome before the promise of

genetic engineering in trees is fulfilled (Sederoff

1999). Even with the concerted research efforts

currently underway in this area, it seems likely

that several decades will elapse before transgenic

trees are a feature of operational southern

pine plantations.

CONCLUSIONS

M

anagement practices in southern pine

plantations have undergone a dramatic

evolution over the last 50 years. By applying

research results to operational plantations,

foresters have more than doubled the productivity

of operational southern pine plantations over this

period (fig. 8.3). For example, older management

practices that produced plantations with growth

rates of < 90 cubic feet per acre per year have

been replaced by new practices that create stands

that are currently producing 400 cubic feet per

acre per year on some sites. Pine plantations in

the South are among the most intensively

managed forests in the world (Schultz 1997).

Site-specific, integrated management regimes

that incorporate the genetic gains available from

tree improvement along with silvicultural practices

that optimize resource availability throughout the

rotation are now the norm. Growth rates in many

pine plantations in the South are now approaching

those in the Southern Hemisphere. Additional

gains in productivity are likely as management

regimes are refined further. In the near term,

implementation of clonal forestry holds the

greatest promise to dramatically increase

productivity in southern pine plantations.

As a result, the South is likely to remain

the woodbasket of the United States for the

foreseeable future.

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83

Year

1952 1962 1970 1977 1985 1996

Forest area (million ha)

0

5

10

15

20

25

30

35

Upland hardwood

Natural pine

Lowland hardwood

Pine plantation

Oak-pine

Chapter 9.

Reproduction Cutting Methods

for Naturally Regenerated Pine Stands in the South

James M. Guldin1

Abstract—It is projected that plantations will

make up 25 percent of the South’s forest land

area by the year 2040. Thus the remaining

75 percent of that area will consist of naturally

regenerated pine, pine-hardwood, and hardwood

stands. Naturally regenerated pines can be

managed successfully by even-aged and unevenaged silvicultural systems when the reproduction

cutting method is properly planned and executed,

and when there is timely application of site

preparation, release, and intermediate treatments

to ensure seedling establishment and development.

Attention to residual basal area, seed production,

preparation of suitable seedbeds, control of

competing vegetation, and timely density control

are important to the successful management

of naturally regenerated stands.

INTRODUCTION

I

n the last half of the 20th century, the practice

of silviculture in southern pine (Pinus spp.)

stands has focused on one silvicultural

system—clearcutting and planting. This focus

has been made possible by two great advances

during that time: (1) the development of

genetically improved planting stock and (2)

the advent of herbicide technology for control

of unwanted vegetation in planted stands. The

silvicultural system of clearcutting, planting, and

associated herbicide treatments has come to define

intensive forest management. Forest industry,

nonindustrial private forest (NIPF) landowners,

and Government agencies have all employed

variations of this prescription, and as a result

the area in plantations in the South has gone

from virtually none to roughly 12.5 million ha

(31 million acres) in the last 50 years (fig. 9.1).

This silvicultural system has become popular

because of the large total merchantable volume

of wood and wood fiber that can be obtained. In

1995, plantations occupied 15 percent of the forest

land in the South but provided 35 percent of the

harvested volume (Wear and Greis 2002). By 2040,

pine plantations will occupy approximately 20

million ha (50 million acres), or 25 percent of the

southern forest area. This will represent roughly

half of the projected pine-dominated forest area

at that time (Wear and Greis 2002).

On the other hand, these data also imply that by

2040, 75 percent of the South’s forest land will not

be in plantations, but rather in stands of naturally

regenerated origin. Currently more than half of

the area in the South’s pine-dominated forest

types is managed by methods other than intensive

plantation culture. Some of this area will not be

managed at all in a professional sense; it will

simply be allowed to grow as it will and will

be high-graded when an operable commercial

harvest becomes feasible. But other areas are,

and will continue to be, managed using classical

silvicultural practices that establish and maintain

1

 Supervisory Ecologist and Project Leader, U.S.

Department of Agriculture Forest Service, Southern

Research Station, Monticello, AR 71656.

Figure 9.1—Trends in forest area occupied by

forest type and year, 1952–96 (Sheffield and

Dickson 1998).
Southern Forest Science:

Past, Present, and Future

Productivity

84

naturally regenerated pine stands. Specifically,

these include even-aged reproduction cutting

methods, such as the seed tree and shelterwood

methods, and uneven-aged reproduction cutting

methods, such as the group selection and single

tree selection methods.

Management of naturally regenerated stands

will have four prominent areas of application

in the decades to come. The first of these is in

management of the forest land owned by NIPF

landowners. Many NIPF landowners choose

not to employ clearcutting on their land, because

clearcutting requires a large capital investment

in stand establishment. Plantation establishment

costs can quickly exceed $500/ha ($200 per acre),

especially if intensive site preparation includes

applications of chemicals and fertilizer (Dubois and

others 2001). While such costs are easily borne by

large companies, they are often difficult for NIPF

owners of small properties to justify. Management

prescriptions that rely on natural regeneration can

be adapted to make stand establishment costs very

low, although the tradeoff is that it takes longer

to develop trees of merchantable size. However,

many NIPF landowners find this acceptable,

especially in light of the multiple management

objectives they often seek, within which the

aesthetic disadvantages associated with

clearcutting do not fit.

The second prominent area of application is in

management of large-diameter pine trees and the

higher unit value that sawtimber brings relative to

pulpwood when trees are harvested. For example,

during the past 10 years in Louisiana, prices of

softwood sawtimber averaged from 3.2 to 5.4 times

those of pine pulpwood on an equivalent weight

basis (Louisiana Department of Agriculture and

Forestry 2002a, 2002b). In multiple-use settings,

management of stands to large tree size

can produce aesthetic, wildlife, and other

benefits sought by a landowner. Finally, a part

of the South’s forest industry will continue to

concentrate on the manufacture of high-quality

dimension lumber, the best source of which

is high-quality trees of sawtimber size.

The third area of application is within

streamside management zones (SMZs), often

among the most productive sites in a forested

ownership. Clearcutting is generally avoided in

SMZs, because it has adverse effects on water

quality and aquatic systems. High-grading or

selective cutting is often used to capture standing

volume of desired species found in SMZs,

but experience shows that such practices are

neither sustainable nor grounded in sound

silvicultural practice. One sensible approach

to the management of SMZs is to employ

management prescriptions that naturally

regenerate desired species while maintaining

forest cover within the SMZs.

Finally managers of public forest land in the

South, especially those who manage national forest

lands, are increasingly seeking alternatives to

clearcutting (Guldin and Loewenstein 1999). This

trend has its origins in the fact that the public does

not like the appearance of clearcutting on public

lands. But it also is seen in modern approaches

to management of Government lands by means

of silvicultural prescriptions designed to retain

or restore forest stand conditions that benefit

underrepresented plant and animal communities,

such as the pine-bluestem habitat restoration in

the western Ouachita Mountains (Stanturf and

others 2004).

Research and practical experience suggest

that both even-aged and uneven-aged reproduction

cutting methods can be used in southern forest

stands, depending on forest type, prevailing

economic and ecological conditions, and ownership

(Burns 1983). It is likely that the range of potential

applications will grow wider rather than narrower

as a wider variety of practitioners employ a

wider variety of these methods on a wider variety

of ownerships.

THE ECOLOGICAL BASIS OF NATURALLY

REGENERATED PINE STANDS

R

eproduction cutting methods that rely on

natural regeneration emulate a continuum of

intensity of natural disturbance. Clearcutting,

with its total removal of all overstory vegetation,

approximates the most severe stand-replacement

disturbances, such as the main path of a tornado

or the flare-up of a canopy-destroying wildfire. But

few ecological conditions in nature are so severe

that all living trees are removed. More commonly,

some trees remain following disturbance, and

they provide seed to reforest the disturbed area.

Reproduction cutting methods that rely on natural

regeneration imitate this dynamic directly.

The even-aged seed tree and shelterwood

methods approximate disturbance events

sufficiently severe that a new regeneration cohort

is established across the entire stand. They differ

in the number of residual trees remaining on the

site and in the provision of shelter by residual

trees. In the seed tree method, few overstory

trees remain, and microecological conditions for
85Chapter 9. Reproduction Cutting Methods

seedlings are essentially the same as if the area

were clearcut. In the shelterwood method, more

overstory trees remain, and their presence slightly

ameliorates the microecological condition for

developing seedlings.

The uneven-aged methods approximate

disturbance events that open up only part of a

stand. Thus the new regeneration cohort will be

found only in those portions of the stand within

which the openings are found, rather than across

the entire stand. The group selection method

emulates disturbance events such as beetle

spots or locally heavy windstorms that remove

small groups of overstory trees within a stand;

regeneration then occurs in that group opening.

The single tree selection method imitates the

smallest scale of disturbance, that of the mortality

of one or two mature trees. This creates a small

opening marginally sufficient for development of

a very small cohort of regeneration, provided that

the species being managed is sufficiently tolerant

of shade to develop. Thus the entire gradient of

natural disturbance events, from severe events

that give rise to continuous regeneration cohorts

across the stand to localized events that give

rise to discontinuous regeneration cohorts within

the stand, are reflected in the reproduction

cutting methods used to naturally regenerate

managed stands.

EVEN-AGED REPRODUCTION

CUTTING METHODS

Clearcutting Method

T

he clearcutting method can be applied in a

manner that relies on natural regeneration

rather than on planted seedlings to reforest

the clearcut site (Langdon 1981, Smith 1986a).

However the circumstances under which the

practice will succeed are highly specialized.

One common approach is to configure the

clearcut opening so that trees from adjacent

stands can naturally seed all parts of the harvested

site (fig. 9.2). The more risky practice in southern

pines, clearcutting using seed-in-place (Smith

1986a), relies on the harvest of trees at the point

in the growing season when cones are mature

but not yet opened. Harvest will disperse those

cones across the site, and the warm temperature

regimes that result from clearcutting promote

cone scale reflexion and seed dispersal (Shelton

and Cain 2001). This method can succeed only

if many conditions are concurrently met. Cones

must be present and contain viable seed, harvest

must occur within a 1-month window prior to the

autumnal seed fall, seedbed conditions must

be adequate within the slash resulting from the

harvest, seed must remain present and viable

Figure 9.2—The strip clearcutting method demonstrated in a

loblolly-shortleaf pine stand, Crossett Experimental Forest, near

Crossett, AR. Photo courtesy of James M. Guldin 2003.
Southern Forest Science:

Past, Present, and Future

Productivity

86

until germination occurs, and seedlings must

become established and must develop properly.

The major difficulty is that there is no room for

accident or error, since there is no residual seed

source in the event that the initial cohort does not

become established.

Seed Tree Method

In the seed tree method, a small number of

trees are retained on the site after harvest as a

source of seed for the harvested area. Seed trees

should be distributed uniformly across the site in

such a way that the entire area of the harvested

stand is within an acceptable dispersal distance

of one or more of the residual seed trees. A

reasonable estimate for the number of seed trees

depends on tree size, but it is not unusual to

reserve 10 to 25 pine seed trees/ha (4 to 10 trees

per acre), with a corresponding residual basal

area from 1 to 3 m2

/ha (5 to 15 square feet per

acre). The harvest that takes all but the seed trees

is called the seed cut, and the subsequent harvest

that removes the seed trees is called the removal

cut (Smith 1986a).

Professional application of the seed tree

method bears little resemblance to retention of

seed trees under the old seed tree laws. Those

laws, which mandated retention of a few trees/ha

after harvest, had the effect of leaving the poorest

phenotypes of marginal size to reforest the site.

Many attributes of interest to foresters, such as

cone production, straightness, and branchiness,

are highly inherited traits, and trees that display

such attributes are likely to pass them along.

Thus proper application of the seed tree method

dictates the retention of trees with good form,

acceptable branch characteristics, and evidence

of past seed production. These attributes are

easier to determine in some species than others.

For example, in shortleaf pine (P. echinata Mill.),

cones tend to persist for a number of years

after seeds are shed (Lawson 1990), whereas

loblolly pine (P. taeda L.) tends to drop its cones

after seed fall (Baker and Langdon 1990). In

shortleaf pine stands, marking crews can use

this information about cone persistence to help

determine which trees to retain.

The biggest limitation on the effective use of

the seed tree method is the production of seed by

the parent tree. Of the four major southern pines,

the seed tree method works best in application

to loblolly pine, especially in the west gulf region

where abundant seeds are produced with great

regularity (Cain and Shelton 2001). Adequate seed

production translates to adequate seed fall and

the likelihood of effective catch of seed by the site.

Unfortunately, seed production in longleaf pine

(P. palustris Mill.) is highly periodic, and use

of the seed tree method is rarely successful

with this species. One way to compensate for

erratic cone production is to plan to retain seed

trees for a long period of time, in the hope of

continued recruitment into the regeneration

cohort. Empirical evidence suggests that the

seed tree method can also be made to work in

shortleaf pine, which falls between loblolly and

longleaf in periodicity of seed fall (Guldin and

Loewenstein 1999).

As seed fall from seed trees becomes marginal,

the need for effective site preparation increases.

One main element of site preparation is the

creation of a suitable seedbed. This, for southern

pines, generally means the scarification of the

forest floor to expose mineral soil. Typically, the

logging activity associated with a seed tree

harvest provides sufficient scarification for

acceptable establishment of seedlings during

bumper seed crops (Baker and others 1996).

If seed crops are marginal, supplemental

scarification may be required. However, no

amount of supplemental scarification will help

if seed crops are a failure. As a result, early

detection of impending seed crops is important

to help schedule the amount of site preparation

necessary to ensure acceptable seedling

establishment. Since pine cones take 2 years

to develop, one can get an early estimate of

cone production expected for given autumn by

inspecting tree crowns for conelets in the spring of

the previous year. While this approach offers only

a rough prediction of adequate to bumper crops,

one can easily see when a cone failure is imminent.

That information can then be used to schedule or

defer site preparation treatments in the summer

or autumn immediately prior to seed fall.

When properly applied, the seed tree method

has a number of advantages. Enough residual

trees should be retained to allow an operable

harvest of the parent trees 5 to 10 years after

the seed cut. That operable harvest can also

provide a desirable precommercial thinning in

the regeneration cohort, by felling the seed trees

amidst the regeneration and by the passage of

the equipment used to harvest and skid the felled

logs to the logging deck.

An outstanding example of the seed tree

method in application to southern pines exists in

the loblolly-shortleaf pine type in the upper west

Gulf Coastal Plain (Zeide and Sharer 2000) (fig.

9.3). No southern pine is easier to regenerate
87

naturally than loblolly pine, which dominates this

forest type; seed crops that are adequate or better

occur 15 years in 20 in mature loblolly-shortleaf

pine stands (Cain and Shelton 2001). For a number

of decades, the silvicultural guidelines for a major

industrial forestry landowner in the region called

for use of the seed tree method, leaving 2.3 to 4.5

m2/ha (10 to 20 square feet per acre) of basal area

of trees with good form and with diameter at

breast height of 40 to 50 cm (16 to 20 inches).2 The

seed trees were usually taken in a removal cut 3 to

5 years later, which produced an operable harvest

of from 2.9 to 8.8 m3/ha (500 to 1,500 board feet per

acre) of saw logs. Removal of the seed trees also

thinned the excessive pine regeneration that was

common in this forest type. The first commercial

thinning occurred between the ages of 17 and 20

years, leaving about 16 m2

/ha (70 square feet per

acre). The next thinning, at age 25, included some

small saw logs, and subsequent thinnings on a 5-

year cycle averaged 11.7 m3/ha (2,000 board feet

per acre) in each thinning. The final seed cut

produced between 29.2 and 40.8 m3/ha (5,000 to

7,000 board feet per acre). Thus growth for the

rotation averaged > 1.75 m3/ha (300 board feet

per acre) annually. Late-rotation thinning also

released the crowns of the seed trees, which

increased cone and seed production. Regularly

scheduled prescribed fires on a 3- to 5-year cycle,

coupled with hardwood control on a 5- to 10-year

cycle, promoted visibility within the stand that

enhanced subsequent thinning treatments, and if

carried through the end of the rotation, reduced

the need for intensive site preparation in the

subsequent rotation.

Shelterwood Method

The shelterwood method is similar to the seed

tree method in that residual trees are retained

to reforest the site after harvesting occurs, but

more trees are retained. In his description of the

shelterwood method, Smith (1986a) includes three

specific elements: (1) the preparatory cut, (2) the

seed cut, and (3) the removal cut.

The preparatory cut removes competitors of

future seed trees, which then expand their crowns

and root systems, thereby enhancing the potential

for cone development. In southern pines, the laterotation thinning commonly conducted in pine

sawtimber stands generally fulfills the intent of

the preparatory cut. During the seed cut, 35 to 75

pines/ha (15 to 30 trees per acre), having 4.5 to 9.0

m2

/ha (20 to 40 square feet per acre) of basal area,

are selected for retention. Favorable traits for

residual pines include stem form, windfirmness,

and evidence of past seed production. The removal

cut harvests the seed trees after the new stand has

developed past the point of risk from seedlingrelated mortality.

One operational advantage of the shelterwood

over the seed tree method in southern pines is that

the volume of the residual trees in the shelterwood

is greater than that of the seed tree method and is,

thus, more likely to attract interest from loggers

during the removal cut. Conversely, if carelessly

done, logging during the removal cut can adversely

affect stem density of the regeneration, especially

at higher residual basal areas. Depending on

management objectives, the final harvest may be

deferred for half or more of the rotation length,

resulting in a two-aged stand; this method is

referred to as an irregular shelterwood (Helms

1998, Smith 1986a).

2

 Lovett, Ernest. 2003. Letter dated September 29 to

James M. Guldin. On file with: Arkansas Forestry Sciences

Laboratory, 114 Chamberlin Forestry Building, University

of Arkansas at Monticello, Monticello, AR 71656.

Figure 9.3—The seed tree reproduction cutting method

applied operationally in a loblolly-shortleaf pine stand

managed by forest industry, Ashley County, AR. Photo

courtesy of James M. Guldin 1984.

Chapter 9.

 Reproduction Cutting Methods
Southern Forest Science:

Past, Present, and Future

Productivity

88

Under traditional application of the

shelterwood method, microclimatic ecological

conditions are ameliorated relative to those found

in fully open conditions; e.g., see Valigura and

Messina 1993. Thus one reason to apply the

shelterwood method is to moderate conditions that

might be too harsh for seedlings to survive under a

clearcut or a seed tree prescription. As a practical

matter, the shelterwood method is popular for

species in which seed production is erratic or

unreliable; the added numbers of seed trees

that remain in the shelterwood often make the

difference between adequate stocking and lessthan-adequate stocking.

Among the most prominent examples of

the shelterwood method in southern pines is

the experience with longleaf pine in southern

Alabama (fig. 9.4). Longleaf pine has the deserved

reputation of being the most difficult of the

southern pines to regenerate naturally, but clever

research has identified the practices needed to

naturally regenerate the species using the

shelterwood method (Boyer 1979, Croker and

Boyer 1975). First, seed production in longleaf

is optimal when the seed cut retains 6.9 to 9.2 m2

/

ha (30 to 40 square feet per acre) of basal area

(Maple 1977). Fewer trees result in fewer cones

per unit area, and more trees do not enhance cone

production. Second, prescribed fires are essential

to control brown-spot needle blight (Mycosphaerella dearnessii Barr.) and, thereby, to release

seedlings from the grass stage (Boyer 1979).

Third, seedling mortality is highest beneath the

crowns of residual trees, because the buildup of

pine straw promotes prescribed fires sufficiently

intense to kill them. All of these factors have led

scientists to conclude that the need for available

growing space, the need for frequent prescribed

fire, the optimal development of cones in the

canopy, and the ability to store seedlings

in a seedling bank beneath the overstory of

longleaf pine could be achieved using the

shelterwood method.

UNEVEN-AGED REPRODUCTION

CUTTING METHODS

P

revailing wisdom suggests that uneven-aged

reproduction cutting methods, especially the

single tree selection method, are best for

shade-tolerant species (Smith 1986a). As a result,

the use of uneven-aged silviculture to manage

shade-intolerant species such as the southern

pines is often criticized. But historical experience

suggests that the method can work with pines,

subject to certain considerations. The Dauerwald,

among the first applications of uneven-aged

silviculture, was imposed in plantations of Scots

pine (P. sylvestris L.) on poor sites in Germany

(Troup 1952); some of its attributes still apply

to current uneven-aged methods (Guldin 1996).

Pearson (1950) applied a selection method to

ponderosa pine (P. ponderosa Laws.) stands on

the Fort Valley Experimental Forest in Arizona,

thus laying the groundwork for contemporary

application of that method in the American West

(Becker and Corse 1997).

In the South, the best long-term uneven-aged

dataset comes from the Good and Poor Farm

Forestry Forties of the Crossett Experimental

Forest (CEF) in southern Arkansas. Established

in mixed loblolly-shortleaf pine stands on the

west Gulf Coastal Plain in 1937, the Good and

Poor Farm Forestry Forties have yielded data

that were summarized after four decades (Baker

1986, Reynolds and others 1984). Other long-term

examples are the quarter-century summary from

the Farm Forestry Forties at Mississippi State

University (Farrar and others 1989) and the 33-

Figure 9.4—The shelterwood reproduction cutting method

applied in a research study on the Escambia Experimental

Forest, near Brewton, AL. Photo courtesy of James M.

Guldin 1982.
89

year record from the University of Arkansas’s

Hope Farm Woodland at Hope, AR (Farrar and

others 1984). Empirical evidence suggests that

the selection method can be made to work with

longleaf pine in the lower Coastal Plain of Florida

and Alabama (Farrar 1996), and with shortleaf

pine in the Interior Highlands of Arkansas and

Oklahoma (Guldin and Loewenstein 1999, Lawson

1986). In short, the selection method can be

adapted to southern pines if attention is paid

to marking, regeneration, and stand structure

(Guldin and Baker 1998).

The general experience with uneven-aged

silviculture in intolerant pines would lead one

to suspect that group selection, with its larger

openings (fig. 9.5), would be more effective than

single tree selection, with its minimal canopy

opening. Certainly some evidence suggests

that in longleaf pine, group selection may be an

effective reproduction cutting method (Brockway

and Outcalt 1998, Farrar 1996, Farrar and Boyer

1991). On the other hand, Russ Reynolds, the

scientist who pioneered the research at CEF, did

not distinguish specifically between single tree

selection and group selection; he spoke instead of

using whatever size of openings was indicated by

local stand conditions (fig. 9.6). Whether group

selection or single tree selection is preferred, a

number of considerations should receive special

attention when selection methods are applied

to southern pines: initial stand conditions,

regeneration, developmental dynamics, application

of marking rules, and residual stand structure.

Initial Stand Conditions

Circumstantial evidence suggests that early

20th century southern pine stands were largely

even-aged before they were high-graded.

Loblolly pine was known as old-field pine,

and early photographs show that virgin upland

pine-hardwood stands in the west gulf region

had an open understory (Reynolds 1980).

Figure 9.5—The group selection method in application to

longleaf pine in a Farm Forestry Forty demonstration on the

Escambia Experimental Forest, near Brewton, AL. Photo

courtesy of James M. Guldin 1982.

Figure 9.6—Stand structure in a stand under management using the selection method,

Good Farm Forestry Forty demonstration, Crossett Experimental Forest, near Crossett, AR.

Photo courtesy of James M. Guldin 1984.

Chapter 9.

 Reproduction Cutting Methods
Southern Forest Science:

Past, Present, and Future

Productivity

90

D.b.h. class (cm)

10 20 30 40 50 60 70

Pine density (trees/ha)

0

20

40

60

80

1937

1951

1971

(B)

(A)

D.b.h. class (cm) 

10 20 30 40 50 60 70

Pine density (trees/ha)

0

20

40

60

80

1937

1951

1971

Similarly, virgin shortleaf pines in the Ouachita

Mountains grew in open forest consisting of widely

spaced overstory trees and little undergrowth

(Smith 1986b).

Naturally occurring loblolly-shortleaf pine

stands in the west gulf region originated after

the first cutting of virgin forest in the early 1900s.

In 1915, the Crossett Lumber Company, which

owned the virgin forest land that would later

become the CEF, harvested the area using a

38-cm (15-inch) stump limit cut, which was

roughly equivalent to a 30-cm (12-inch) diameter

limit cut. Between 1915 and 1934, no deliberate

management was undertaken. The area supported

occasional harvest of small hardwoods for chemical

distillation and periodically was subject to arson

fires. The company leased the 680-ha (1,680-acre)

tract to the U.S. Department of Agriculture Forest

Service (Forest Service) in 1934 for establishment

of the CEF. While the company was interested in

research information on management of secondgrowth forests, they also thought that Forest

Service research staff could help prevent arson

or control the resulting fires (Reynolds 1980).

Thus the use of uneven-aged silviculture in

southern pines originated as a result of selective

cutting. In 1937, the CEF Forties were stocked

with scattered residual overstory trees that had

survived the 30-cm (12-inch) diameter limit cutting

in 1915, and the second-growth seedlings, saplings,

and poles that seeded in after the cut and grew

until 1937. On average, the stands were about

40 percent stocked by then (Reynolds 1969). The

diameter distribution of the pine component in the

CEF Good and Poor Forties in 1937 showed the

reverse J-shaped curve typical of uneven-aged

structure (fig. 9.7). This description of selective

cutting and its effects on stand conditions at

CEF was typical of that in the region; the stands

in the Farm Forestry Forties and Hope Farm

Woodland demonstrations had a similar history

and initial condition. Because the stands in these

demonstrations were relatively understocked

when the selection method was initially applied

to them, their rapid recovery to fully stocked

conditions under the selection method shows that

uneven-aged silviculture is a powerful tool for

bringing understocked or cutover stands

to full stocking within a short time (Baker and

Bishop 1986; Farrar and others 1984, 1989).

Additional research illustrates not only the

speed of the recovery, but also the degree of

understocking from which recovery can occur.

Baker and Shelton (1998a, 1998c) reported

that stands with 20- to 30-percent stocking

could develop acceptable stocking and basal

area within 15 years, provided that competing

vegetation is controlled with herbicide application.

These threshold levels are lower than previously

thought, and lower than threshold levels in the

long-term demonstrations.

This suggests a strategy for implementing

uneven-aged silviculture in southern pines across a

forested ownership in the public or private sector.

If the ownership supports both fully stocked evenaged stands and stands that for one reason or

another are understocked, the best approach

would be to convert the understocked stands

rather than the fully stocked even-aged stands. Figure 9.7—Diameter distributions of the Good Forty and the

Poor Forty on the Crossett Experimental Forest in the first 35

years of the demonstration—(A) Good Forty in 1937, 1951,

and 1971; (B) Poor Forty in 1937, 1951, and 1971.
91

Regeneration

The importance of regeneration in these

demonstrations is poorly documented for two

reasons. First, there is no record of regeneration

development in the 20- to 40-year period between

the initial high-grading and demonstration

establishment. Second, because regeneration

was so abundant, the scientists who established

the demonstrations paid little attention to it.

Reynolds (1959, 1969) reported that pine

regeneration was established as a result of

removal of poorer hardwoods of large and medium

size, continuing fire protection, and control of

small hardwood stems. He also noted that pine

seedlings, saplings, and poles typically are found

in small openings and often directly under highcrowned larger stems. This is apparent in the

diameter distributions of the Good and Poor

Forties during the first 20 years of management

(fig. 9.7). The continued ingrowth into the 10-cm

(4-inch) class during this period resulted from

recruitment of saplings from the smaller

diameter classes.

Thus obtaining regeneration and promoting

its development through the seedling and sapling

classes are critical for successful uneven-aged

management (Shelton and Cain 2000). The initial

cohort of reproduction should be established or

released at the first cutting-cycle harvest in order

to meet two goals: (1) the need for reproduction

cutting to result in regeneration, and (2) the

need to establish three or more distinct age classes

in the uneven-aged stand (Helms 1998). If the

establishment of the initial regeneration cohort

is delayed, the conversion period will be

correspondingly lengthened.

Residual Basal Area

In southern pines, regeneration establishment

and development are strongly related to the basal

area of the merchantable component of the stand.

Data from the CEF and elsewhere suggest that

uneven-aged stands can be managed successfully

within a range of residual basal area from 10 to

17 m2

/ha (45 to 75 square feet per acre) (Baker

and others 1996; Farrar 1996; Farrar and others

1984, 1989). At residual basal area levels < 10 m2/

ha (45 square feet per acre), the overstory is

understocked and growth will not be optimal

(although such stands can be rehabilitated to

optimal production easily, as discussed earlier).

At residual basal areas > 17 m2

/ha (75 square

feet per acre) at the end of the cutting cycle,

regeneration development is adversely affected.

The residual basal area target immediately

after harvest must be established in conjunction

with the expected length of the cutting cycle,

the expected growth of the residual stand, and

the upper basal area limit for the species. For

example, basal area growth of uneven-aged

loblolly-shortleaf pine stands at CEF is 0.5 to 0.7

m2

/ha (2 to 3 square feet per acre) annually. If a 5-

year cutting cycle is planned, the target residual

basal area immediately after the cutting cycle

harvest must, therefore, be 14 to 15 m2/ha (60 to

65 square feet per acre), so that stand basal area

does not exceed 17 m2/ha (75 square feet per acre)

at the end of the cutting cycle. Longer cutting

cycles require lower residual basal area levels.

Thus managing for the proper residual basal

area is an important element of uneven-aged

silviculture. This is one reason why structural

regulation using the basal area, maximum

diameter, and q-ratio or the BDq method (Baker

and others 1996, Farrar 1996, Marquis 1978)

has become popular. The CEF experience and

other work suggest that BDq is more than an

alphabetical ranking; this order reflects the

priority for implementation (Baker and others

1996, Farrar 1996). The importance of

maintenance of stand structure is based on

obtaining the appropriate basal area; retaining

a specified maximum diameter class or a given

q is much less important (Guldin and Baker 1998).

Developmental Dynamics

By definition, uneven-aged stands have

three or more distinct regeneration cohorts;

so, if one begins with an even-aged stand or an

understocked stand, conversion to an uneven-aged

structure is a long-term proposition. A minimum

of two cutting-cycle harvests will be needed to

recruit two additional cohorts of regeneration,

and a third cutting-cycle harvest will be needed

to avoid suppressing this new regeneration,

especially with shade-intolerant southern pines.

For the 5- to 7-year cutting cycles used for loblollyshortleaf pine stands at CEF and elsewhere,

it will be 20 to 30 years before even-aged or

understocked stands are minimally reconfigured

to uneven-aged structure. For species such as

shortleaf pine in the Interior Highlands, where

7- to 10-year cutting cycles are common, the

conversion period will be 30 to 40 years. These

estimates are confirmed in data from the CEF

Good and Poor Forties, where the time from

high-grading harvests in 1915 to initial

development of full stocking was 36 years.

Chapter 9.

 Reproduction Cutting Methods
Southern Forest Science:

Past, Present, and Future

Productivity

92

Marking Rules

When conducting a cutting-cycle harvest in an

uneven-aged southern pine stand, the guidance

given to field crews can be summarized by a simple

rule: cut the worst trees and leave the best (Baker

and others 1996; Farrar 1996; Farrar and others

1984, 1989; Guldin 1996; Reynolds 1959, 1969).

When stands have developed an uneven-aged

structure through time, tree size generally

becomes correlated with age across the diameter

distribution (Baker and others 1996). Marking a

percentage of the poorest trees in each diameter

class improves the average tree quality within

each class, and over time only the best trees of

highest quality attain the largest size. As a result,

one attribute of the selection method is that

over time, it produces large sawtimber that has

high quality.

In stands being converted from even-aged

to uneven-aged structure, size is not correlated

with age, because the smaller trees may be of the

same age as the larger trees. This means that most

trees in the left-hand tail of a normal bell-shaped

diameter distribution may in fact be the worst

trees in the stand. Strict adherence to the rule of

cutting the worst and leaving the best may result

in an effect similar to thinning from below, where

most of the smaller trees are removed. This is

preferable to retaining poorer trees in smaller

size classes at the expense of better trees in larger

classes simply to achieve a target structure. If

the best trees are being retained below the

maximum diameter and are retained in a manner

that allows development of subordinate stems

and newly established regeneration cohorts, a

perfectly balanced stand structure is immaterial.

Marking crews need guidance in judging

whether an intermediate tree in the pulpwood

size class can respond to release if it is allowed

to remain in the stand. Reynolds (1959) noted

that loblolly pine in the west gulf region could

respond to release, even at advanced age. Baker

and Shelton (1998b) observed that if a loblolly pine

had a 20-percent live crown ratio and good apical

dominance, it should satisfactorily respond to

release, even if it developed in the lower crown

classes of fully stocked, uneven-aged stands for up

to 40 years; anecdotal evidence for longleaf pine is

similar. Different standards would probably apply

for other southern pine species and for trees from

lower crown classes in even-aged stands.

To a certain extent, the group selection

approach to management of uneven-aged

stands violates the rule of cutting the worst

trees and leaving the best. Group selection

usually prescribes cutting of all trees, best and

worst, if they are within the group. The degree

of conflict depends on how the groups are located.

If groups are identified independently of density

or stocking, for example, by systematically

installing groups of similar size and shape

according to a predetermined pattern, the

opportunity to cut the worst and leave the best

is seriously compromised. Conversely, if groups

are established in understocked portions of the

stand, without regard for size, shape, or pattern

of group opening, the number of best trees that

must be cut will be reduced. Group selection

with reserves (Helms 1998) is probably the best,

though least often prescribed, method to minimize

conflicts with the “cut the worst and leave the

best” axiom, provided that reserved trees within

the group are the best trees and do not adversely

affect regeneration establishment or development.

OTHER ELEMENTS

A

dditional silvicultural considerations are

important in the management of naturally

regenerated stands by even-aged or unevenaged methods.

Seedbed preparation is critical. Southern

pine seeds germinate best on exposed mineral

soil. In southern pine types that produce prolific

seed crops, such as the loblolly-shortleaf pine

type in the west gulf region, the scarification

associated with logging provides enough exposure

of mineral soil to promote establishment of

regeneration. For other species, such as longleaf

pine, supplemental mineral soil scarification is

often recommended. Prescribed burning can

also be used to prepare seedbeds.

The relative competitive abilities of pines

and hardwoods after a harvest dictate that

foresters must pay attention to relative growth

rates and intervene if necessary. After a seed

cut or cutting-cycle harvest, the intent is to allow

pine seed to germinate on exposed mineral soil,

become established, and be free to develop.

However, hardwoods cut during harvest or

subsequent site preparation will sprout and

quickly outgrow seed-origin pines. Similarly,

under certain circumstances grasses and other

herbaceous plants may become sufficiently dense

to impede pine seedling development, and control

of grasses may also be necessary. Therefore site

preparation or release treatments are often an

integral part of effective silvicultural prescriptions

for natural regeneration.
93

For example, competing hardwoods, as well

as nonnatives such as privet (Ligustrum vulgare

L.) and honeysuckle (Lonicera japonica Thunb.),

commonly inhibit the development of pine

regeneration (Shelton and Cain 2000). Given

the slow rates of height growth of pine seedlings

and the competition provided by hardwood sprouts

and invasive nonnative plant species, herbicides

are critically important in managing stands of

naturally regenerated pines, and may be more

important to the establishment and development

of naturally regenerated pine seedlings than

to the survival and development of planted pine

seedlings. The use of herbicides has in fact

been an element of every successful long-term

demonstration of uneven-aged silviculture in

southern pines, including the successful practical

experience of which the author is aware. Periodic

control of hardwoods by applying herbicides at

roughly 10-year intervals was an element of

uneven-aged silvicultural prescriptions at CEF

(Baker 1986). Farrar and others (1984) noted that

deficits in the smaller diameter classes in unevenaged stands were due in part to the failure of

recruitment from regeneration to pulpwood-size

classes, which was attributable to hardwood

competition and the presence of privet. Farrar

and others (1989) reported that control of

hardwoods by cutting, girdling, or herbicide

treatments occurred in the past on the unevenaged Mississippi State Farm Forestry Forties, and

was recommended in the future for all hardwood

stems > 1.0 cm (0.4 inch) in diameter. Prescribed

fire and herbicides were used in much the same

way in stands regenerated using the shelterwood

method on the Escambia Experimental Forest

(Croker and Boyer 1975). Their use has been

recommended in industrial seed tree silvicultural

guidelines for south Arkansas and north Louisiana

(see footnote 2 and Zeide and Sharer 2000).

Prescribed fire, which does not kill larger

hardwoods, probably cannot completely eliminate

the need for herbicides in naturally regenerated

stands, especially in uneven-aged stands.

Finally control of regeneration density is

fundamental to the successful application of

natural regeneration in managed stands.

Regeneration development in loblolly pine is

improved by early precommercial thinnings to

control stem density (Cain 1995). Nevertheless

regeneration density will always be less uniformly

distributed in naturally regenerated stands than in

successfully established planted stands. Industry

foresters in the west gulf region observed a longterm average rate of understocking of 7 percent of

the stand area in managing naturally regenerated

stands (see footnote 2). Invariably, one of the

challenges in managing naturally regenerated

stands is the likelihood of damage to regeneration

when conducting removal cuts or subsequent

cutting-cycle harvests. In situations where

regeneration is far in excess of desired density,

such logging-related precommercial thinning

may actually be desirable. However, the situation

is more critical when regeneration density is

marginal prior to the removal cut or to subsequent

cutting-cycle harvests. Careful supervision of

logging operations is needed in such situations.

SUMMARY

S

uccessful use of natural regeneration in

managing southern pines depends on a

number of factors. The establishment and

development of pine regeneration is critical.

Prescriptions must leave a sufficient number

of seed trees to adequately regenerate the site

during an average or better seed year. Sites

must be properly prepared to be receptive to pine

seed, and timing of harvests and site preparation

must optimize the establishment and development

of regeneration.

In even-aged stands, late-rotation thinnings

or preparatory cutting is recommended to expand

crowns of future seed trees and to promote

cone production. The seed cut must create an

appropriate balance of residual trees and seed

production capacity per tree to ensure adequate

seed fall, and site preparation must be timed

to that seed crop. In uneven-aged stands, the

first cutting-cycle harvest must be heavy enough

not only to create conditions suitable for the

establishment of regeneration, but also to prevent

suppression of regeneration before the second

cutting-cycle harvest occurs. Subsequent cuttingcycle harvests must continue this developmental

pattern. Regardless of system, herbicides will

almost certainly be needed to control competing

vegetation and enable young pine cohorts to

develop successfully.

Experience and research suggests that all

four major southern pines can be managed using

one or more of the even-aged or uneven-aged

reproduction cutting methods that rely on natural

regeneration. Certainly some forest types, such as

the mixed loblolly-shortleaf pine type in the west

gulf region, are amenable to any of the even-aged

and uneven-aged prescriptions, whereas in other

forest types, such as longleaf pine, the range of

available options is perhaps narrower and requires

Chapter 9.

 Reproduction Cutting Methods
Southern Forest Science:

Past, Present, and Future

Productivity

94

greater care in application. Each of the systems

must be implemented in a manner that takes

into account the silvical characteristics of the

species in question. Choosing which method to

use in a particular forest type depends on proper

application of available research and experience

with the desired species in specific situations.

Overall, these methods present feasible and

economically viable alternatives to clearcutting

and planting for public land managers, forest

industry foresters, and NIPF landowners

in the South.

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Troup, R.S. 1952. Silvicultural systems. 2d ed. London:

Oxford University Press. 216 p.

Valigura, Richard; Messina, Michael G. 1993. Evaluation

of potential evaporation as a means to infer loblolly pine

seedling physiological response to a given microclimate.

Forest Ecology and Management. 67: 241–255.

Wear, David N.; Greis, John G., eds. 2002. The southern forest

resource assessment: summary report. Gen. Tech. Rep.

SRS-54. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southern Research Station. 103 p.

http://www.srs.fs.fed.us/sustain/report/summry/

summary.pdf. [Date accessed: May 10, 2003].

Zeide, Boris; Sharer, David. 2000. Good forestry at a glance: a

guide for managing even-aged loblolly pine stands. Arkansas

For. Resour. Cent. Ser. 003. Fayetteville AR: University of

Arkansas, Division of Agriculture, Arkansas Agricultural

Experiment Station. 19 p.

Chapter 9.

 Reproduction Cutting Methods

97

Chapter 10.

The Role of

Genetics and Tree Improvement

in Southern Forest Productivity

R.C. Schmidtling, T.L. Robison,

S.E. McKeand, R.J. Rousseau,

H.L. Allen, and B. Goldfarb1

Abstract—Because of space limitations, a

thorough discussion of the rich history of tree

improvement in the Southeastern United States

cannot be totally accomplished in this forum.

However, a synopsis of key program highlights

and the people who forged and directed these

programs is presented, together with a discussion

of current and future work. This discussion covers

improvement programs for both southern pines

and hardwoods. Comparisons of and contrasts

between these two types of programs are

discussed and punctuated by the reasons for

successes and failures. Today, southern pine tree

improvement programs are on the cutting edge

of genetic technology, moving from openpollinated seed to clonal programs encompassing

molecular genetic features. Programs for southern

hardwoods generally are much less advanced,

because there are several limiting factors unique

to hardwoods and because hardwood fiber is

available at low cost.

INTRODUCTION

C

onsumption of forest products is expected

to continue its rapid increase during the

21st century. In contrast, the land base

used for wood production is expected to decline

because of population pressures, environmental

concerns, lack of adequate management by many

landowners, and the divesture of lands deemed

nonstrategic. Even today, removals equal or

exceed growth rates in some areas (Wear and

Greis 2002). However, models indicate that the

potential productivity of forests in many regions

can be much higher than is currently realized

(Allen 2000, Bergh and others 1998, Sampson

and Allen 1999). With investments in appropriate

management systems, growth rates > 25 m3/ha/

year for pines are biologically possible and

can be financially attractive for a broad range

of site types in temperate, subtropical, and

tropical regions.

In the early days of southern forestry,

vast areas were clearcut with little or no regard

for regeneration. Natural regeneration was

satisfactory in some areas but totally lacking in

others. Very little planting occurred before the

Civilian Conservation Corps began wide-scale

planting during the Great Depression. Wakeley

(1944) estimated that < 500 acres of southern

pines had been artificially regenerated

successfully before 1920.

Historically, the practice of silviculture

focused on controlling the composition, quantity,

and structure of forest vegetation and the

maintenance of site quality. As forest plantations

have become important sources of fiber, fuel,

and structural material, this custodial role has

given way to active intervention to improve both

plant and soil resources. Forest managers are

recognizing that intensive plantation silviculture

requires active management of both biotic

and abiotic resources to optimize production.

Silvicultural treatments including soil tillage,

vegetation control, fertilization, fire, and thinning

can dramatically affect soil resources. The key

1

 Chief Geneticist (now Emeritus), U.S. Department of

Agriculture Forest Service, Southern Research Station,

Saucier, MS 39574; Research Scientist, MeadWestvaco,

Wickliffe, KY 42087; Professor of Forestry, North Carolina

State University, Raleigh, NC 27695; Central Forest Research

Leader, MeadWestvaco, Wickliffe, KY 42087; and Geneticists,

North Carolina State University Forest Tree Improvement

Cooperative, Raleigh, NC 27695, respectively.
Southern Forest Science:

Past, Present, and Future

Productivity

98

to optimizing fiber production is to deploy the

best genetic material available and to provide

sufficient resources to allow the full genetic

potential to be realized.

SOUTHERN PINE TREE IMPROVEMENT

Early Work

B

efore 1920, little was known about how

seed source might affect forest plantation

productivity in the United States. Since

well before the turn of the 20th century, the

importance of geographic seed source was known

for European species. In this country, native seed

collections for an extensive study of Douglas-fir

[Pseudotsuga menziesii (Mirb.) Franco] were

initiated in 1912 (Kaufman 1961), and testing of

ponderosa pine (Pinus ponderosa Laws.) seed

sources in northern Idaho and Colorado began

in 1916. Inspired by some of Luther Burbank’s

work with walnut (Juglans spp.) hybrids, James

G. Eddy started the Eddy Tree Breeding Station

(which later became the Institute of Forest

Genetics) at Placerville, CA, in 1925.

Although Chapman (1922) identified the

first natural southern pine hybrid [longleaf pine

(P. palustris Mill.) x loblolly pine (P. taeda L.)],

the history of southern tree improvement began

with Phil Wakeley, who came into the region

in 1924. His undaunted drive led him to complete

a monumental amount of research in basic

silviculture, and his manual “Planting the

Southern Pines” (Wakeley 1954) is still in use.

Although he had little training in genetics, he was

aware of seed source effects and in 1926 installed

an important loblolly pine provenance test near

Bogalusa, LA. This test was one of the first to

clearly demonstrate genetic differences in a

southern pine. The magnitude of the seed-source

effect in southern pines was unknown before

Wakeley published age-15 data indicating that

growth and disease resistance varied widely

among geographic races of loblolly pine (Wakeley

1944). Wakeley is also credited with creating the

first artificial southern pine hybrid in 1929, a cross

between longleaf and slash (P. elliottii Engelm.)

pines (Dorman 1951).

Other early work included a large openpollinated progeny test of loblolly pine installed

in 1934 by A.L. McKinney and L.E. Chaiken

of the U.S. Department of Agriculture Forest

Service, Appalachian Station [now part of the

U.S. Department of Agriculture Forest Service

(Forest Service), Southern Research Station].

Substantial inherent differences were noted before

the planting was flooded by the Santee-Cooper

Power Project (Kaufman 1961).

In 1941, Mitchell, Dorman, and Schopmeyer,

working at the research station in Lake City,

FL, started selecting slash and longleaf pine for

high gum yield. Open- and controlled-pollinated

seedlings from these selections were used to

establish the first progeny tests in southern pines

demonstrating the existence of individual tree

genetic variation.

Around 1949, L.T. Easly (1953), a forester

with Westvaco, gave some high school students

permission to collect cones from one of his sawlog operations and sell them to the State nursery.

The students later told him that they preferred

short, scrubby trees with lots of cones on them,

rather than the sawtimber he was cutting. Aware

of Dorman‘s work, Easly concluded that the

dysgenic selection would result in poor-quality

trees because of the student’s preferred collecting

methods. This prompted him to establish the first

seed production areas in loblolly pine, which he

referred to as orchards.

In 1951, the Southern Forest Tree

Improvement Committee was formed to foster

research and development in forest genetics and

tree improvement. It has continued to be a guiding

force in forest genetics and tree improvement

research and technology transfer to the present

day. According to Kaufman (1961), two events

provided the impetus for the rapid expansion of

genetics and tree improvement in the 1950s. The

first was the influence of several prominent

foresters who attended the World Forestry

Congress in Helsinki in 1949, where they became

aware of the tremendous progress being made by

tree breeders in Europe. The 1950 meeting of the

Appalachian Section of the Society of American

Foresters was devoted to tree improvement. The

second event was an exchange of correspondence

beginning in the fall of 1949 between the Forestry

Relations Division of the Tennessee Valley

Authority (TVA) and the Forest Service’s

Southern Forest Experiment Station on the

possibility of establishing a regional seed-source

research program. The result was the first

Southern Forest Tree Improvement Conference

held in Atlanta, GA, in January of 1951. The

organizers were surprised when > 80 people

attended. Since then, the conferences have been
99Chapter 10. Genetics and Tree Improvement

held every other year. The proceedings of the

conferences are major sources of information

in genetics and tree improvement, as is evident

in the literature cited for the present chapter.2

One product of the first conference was the

establishment of a subcommittee, headed by Phil

Wakeley, to install the Southwide Southern Pine

Seed Source Study (SSPSSS), one of the most

comprehensive provenance tests ever established.

The results from Wakeley’s (1944) first test

were dramatic, but the study was planted only

at Bogalusa, LA. The local seed source from

Livingston Parish, LA, was clearly the best not

only for growth but also for disease resistance.

The SSPSSS, on the other hand, was much

more comprehensive. It was a very large

undertaking, involving many cooperators across

the Southeastern United States who collected

seed and provided planting sites. All four major

southern pine species were included—loblolly,

slash, longleaf, and shortleaf (P. echinata Mill.)

pines. A total of 128 plantations were established,

including seed from and plantations in 16 States,

ranging from New Jersey and Pennsylvania south

to Florida and west to Texas, Oklahoma, and

Missouri (Wakeley 1961).

The results of the SSPSSS and some other

more limited provenance tests showed that the

local seed source was not always the best source.

Seed sources from warmer climates tended to

grow faster than local sources, if the warmer

climate sources were not moved to areas with

climates greatly unlike those where they

originated. Unlike the other southern pines,

loblolly has important east-west differences.

Seed sources from west of the Mississippi River

are slower growing but more resistant to disease

and tolerant of drought than sources from east of

the Mississippi. Sources from just east of the river,

centered at Livingston Parish, LA, combine the

rust resistance of the western sources with the

faster growth of the eastern sources. Results of

this study led to large-scale transfers of seed to

increase productivity. Disease-resistant Livingston

Parish, LA, seed was widely planted in locations

to the east. For example, much of this seed was

planted in Georgia, where disease had caused

losses in productivity. Fast-growing coastal

Carolina seed sources have been planted

extensively in Arkansas, where they outgrow

the local sources.

It was assumed, based on the loblolly results,

that east-west differences would be important

in longleaf and shortleaf pines, because they

also occur on both sides of the Mississippi River.

Recent analysis has shown that this is not so, and

the latest seed-movement guidelines (Schmidtling

2001) stress the importance of minimum

temperatures in seed transfer considerations

for these two species.

Wise use of information about geographic

variation has resulted in large increases in

southern pine productivity. Further increases

have been realized through breeding. Forest tree

breeding in the South started in earnest with the

formation of the tree improvement cooperatives

in the 1950s, with the main emphasis on pines.

The first cooperatives evolved in the early 1950s

out of research programs at the University of

Florida (headed by T.O. Perry) and at the Texas

Forest Service (headed by Bruce Zobel). Zobel

moved to North Carolina State University in

1956 to form the third and the largest of the tree

improvement cooperatives that exist today.

Current Status

Productivity improvements from genetics have

helped to make investments in intensive forestry

very profitable throughout the world. In regions

such as the Southeastern United States, managers

of facilities for wood-based manufacturing facilities

have realized that their future depends upon a

reliable, ecologically sustainable, and economically

affordable supply of wood. Plantations of

genetically improved forest trees are critical to

maintaining this supply. In the South, > 1 billion

loblolly pine seedlings are planted each year,

and nearly every seedling is a product of a tree

improvement program. Because of the economies

of scale, even modest genetic gains are worth

millions of dollars to industrial landowners, and

the small landowner benefits as well. Even

through only one generation of improvement,

gains have been substantial. For first-generation

loblolly pine and slash pine, volume, stem quality,

and disease resistance have been improved, and

the gain in harvest value is estimated to be 15 to 20

percent over unimproved trees (Hodge and others

1989, Talbert and others 1985). Estimates from

the second generation of improvement in loblolly

pine are even more encouraging. Additional

2

 Copies of proceedings of the Southern Forest Tree

Improvement Conferences are available from the National

Technical Information Service, 5285 Port Royal Rd.,

Springfield, VA 22161, 800-553-6847 or 703-605-6000, fax

703-605-6900, orders@ntis.gov.
Southern Forest Science:

Past, Present, and Future

Productivity

100

productivity gains over the first generation

average 7 percent for unrogued orchards to 18

percent for rogued orchards, and improvement in

quality should dramatically exceed what was seen

in the first generation (Li and others 1999).

Because of the substantial improvements

in forest productivity from both genetics and

silvicultural manipulation (Allen 2000, McKeand

and others 1997), the options available to foresters

have increased greatly. Combining a thorough

knowledge of soil productivity and optimal

silvicultural techniques with use of the most

advanced genetic material will dramatically

increase productivity. It is estimated that 20 to

30 percent more wood can be produced per hectare

by utilizing the most responsive families from the

first-generation programs in conjunction with the

best site preparation and nutrition management

practices (McKeand and others 1997). Even

greater gains are expected when the best secondgeneration families are deployed to the best

sites (Li and others 1999).

Deployment options for further increasing

the genetic quality of planting stock are also

being pursued. Mass production of selected fullsib families (Bramlett 1997) will have significant

impact on forest productivity, especially in

areas where additional selection intensity for

environmental concerns such as cold tolerance

is necessary. Because more genetic gain can be

realized if the best full-sib families are used for

regeneration (Li and others 1999), foresters will

have more options for increasing productivity and

profitability. Limitations to utilizing the best fullsib families are the cost-efficient production of

seed and the bulking of these families with

vegetative propagation. Pollination methods

for mass-producing full-sib seedlings are being

developed in the South (Bramlett 1997, Goldfarb

and others 1997) and have been used successfully

in other pine regeneration programs around the

world (Balocchi 1997, Carson 1996, Walker and

others 1996).

A breeding program is the backbone of any

deployment program, and to sustain genetic gains

through time, the breeding program must be of

sufficient size and diversity to provide new and

improved genotypes. A general trend has been

to supplement traditional mainline breeding

populations with intensively managed and

selected elite breeding populations (Cotterill

1989, McKeand and Bridgwater 1998, White

1993, White and others 1993). In the elite

populations, financial benefits can be realized

in the short term by breeding only the very best

genotypes. Fewer trees are bred, so breeding

generations cycle faster, and the gain per year

is dramatically increased.

These elite, intensively managed breeding

populations are complements to, and not

replacements for, larger breeding populations

where the long-term management of genetic

resources is a primary objective. Tree breeders

have a unique responsibility and opportunity

compared to other plant and animal breeders.

Most forest tree species remain as wild

undomesticated populations, and those few

species that are being bred have only been

domesticated in the past few years. Forest trees

generally have very high levels of genetic variation

compared to other plants and animals (Hamrick

and others 1992), and this variation is the

foundation of the successful efforts to improve

productivity through genetics.

SOUTHERN HARDWOOD

TREE IMPROVEMENT

Early Work

E

arly studies in the South concentrated on

establishing geographic variation patterns

in growth and wood properties by means of

provenance trials and sample collections from

widely distributed natural stands. The earliest

studies in the South date from the spring of 1936,

when the forestry division of the TVA became

involved in this work. This program included

the breeding of walnuts (Juglans spp.), hickories

(Carya spp.), chestnuts (Castanea spp.), oaks

(Quercus spp.), honey locust (Gleditsia

triacanthos L.), black locust (Robinia

pseudoacacia L.), and persimmon (Diospyros

virginiana L.) as a means of combining high

productivity and quality of nuts, acorns, or other

fruits with desirable timber quality (Schreiner

1938, Wakeley 1975). In the 1950s and early 1960s,

trials of yellow-poplar (Liriodendron tulipifera L.)

(Farmer and others 1967, Kellison 1965, Lotti 1955,

Thorbjornsen 1961), sweetgum (Liquidambar

styraciflua L.) (Webb 1964), and eastern

cottonwood (Populus deltoides Bartr. ex Marsh.)

(Farmer and Wilcox 1966, Maisenhelder 1961)

were established. At this time, the Forest Service

initiated a tree improvement program to help

mitigate a shortage in timber resources in the

United States expected in the mid-1980s (Tibbs

and Windham 1999). Studies soon followed for

other hardwood species, including northern red

oak (Q. rubra L.) (Gall and Taft 1973), cherrybark

oak (Q. falcata var. pagodifolia Ell.) (Randall

1973), and sycamore (Platanus occidentalis L.)
101

(Land 1981, Webb and others 1973). By 1983 at

least 27 hardwood species had been considered for

tree improvement, and collections had been made

for most of these (Purnell and Kellison 1983).

Unlike southern pines, no one species or small

group of species is suited to the various site types

throughout the South, because hardwoods are very

site specific. Understanding site specificity is

essential to understanding and realizing genetic

gain in hardwoods. However, the absence of

economy of scale greatly limits the ability to

develop a viable genetic program for most

hardwood species.

Three early programs stood out for their

longevity and contributions to hardwood genetics.

These programs were established by the Forest

Service, Southern Forest Experiment Station;

the North Carolina State University Hardwood

Research Cooperative (HRC); and the Texas

Forest Service. The Southern Forest Experiment

Station’s program of hardwood tree improvement

began in the early 1960s at the Southern

Hardwoods Laboratory located in Stoneville,

MS. Sweetgum, cherrybark oak, sycamore, and

eastern cottonwood were studied initially, and

other species added in the late 1970s and early

1980s just prior to the closing of the hardwood

project in 1982 (Ferguson and others 1977, Mohn

and others 1970). Eastern cottonwood, probably

the most intensively studied hardwood species in

the South, was the subject of testing from 1965

through 1980. Early tests indicated that local

sources were superior to earlier introductions of

European hybrids (Maisenhelder 1970). Testing

eventually resulted in the release of the first and

only certified genetically superior cottonwood

clones in the country (Land 1974). Subsequently,

collections were made from natural stands

throughout the lower Mississippi River Valley,

from coastal areas from North Carolina to

Texas, and from other programs as far north as

Minnesota. Large clonal tests were established

with industry and university cooperators in

Arkansas, Illinois, Kentucky, Louisiana, and

Mississippi. Clones suitable for use in various

portions of the Mississippi River Valley were

identified, and data collected on vegetative

propagation, controlled pollination, disease

resistance, crown architecture, and selection

strategies provided excellent information

for industry and university programs to build

upon (Cooper and Ferguson 1979; Cooper and

Filer 1976, 1977; McKnight 1970). In general,

clones originating up to 200 miles south of the

plantation sites grew faster and had greater

leaf rust resistance than local clones. Many

of the cottonwood clones developed at Stoneville

remain the backbone of plantation and breeding

programs today.

Hardwood cooperatives were organized

somewhat later than the pine cooperatives. The

HRC began in 1963 with a combined program

of intensive tree improvement and less intensive

management of natural stands (Young 1996).

Sweetgum, sycamore, yellow-poplar, green ash

(Fraxinus pennsylvanica Marsh.), and water oak/

willow oak (Q. nigra L./Q. phellos L.) received

most of the attention during the early years

because of their commercial importance across a

majority of the Southern United States. Initially, a

selection index was used to identify phenotypically

superior trees, which were then grafted into clone

banks and seed orchards with the oaks established

in seedling seed orchards. In 1972, region-wide

progeny testing was initiated by the HRC (Anon.

1999). Open-pollinated seed from phenotypically

average or better than average sweetgum,

sycamore, water oak, willow oak, and black walnut

(J. nigra L.) were collected from natural stands

throughout the South. The modified selection

scheme was used because the index system proved

inadequate for identifying genotypically superior

southern hardwoods in natural stands (Purnell

and Kellison 1983).

In 1971, the Texas Forest Service’s

Western Gulf Forest Tree Improvement

Program formally added the Hardwood

Cooperative Tree Improvement Program to

their existing pine program (Byram and Lowe

1995). To date, 17 species-site trials and 188 openpollinated progeny tests have been established

with nearly 1,500 families (Byram and others

2000). After 20 years, sycamore, sweetgum, and

green ash tests indicated that family differences

were significant, but there were neither consistent

provenance effects nor any meaningful genotype x

environment interactions for hardwood species in

the southern Coastal Plain (Byram and others

1998). A slight indication was found that sources

from the western edge of the species range are

slower growing. Families that performed well

across the region could be identified as early

as age 5 or 10.

Current Status

A survey of State tree improvement personnel

indicated that most Southern States currently

have hardwood tree improvement programs, and

almost half are active members of one of the two

hardwood cooperatives. Arkansas, Louisiana,

Chapter 10.

Genetics and Tree Improvement
Southern Forest Science:

Past, Present, and Future

Productivity

102

Mississippi, and Texas benefit from their affiliation

with the Western Gulf Forest Tree Improvement

Program. North Carolina and South Carolina are

currently members of the HRC. Sycamore and

sweetgum are of primary importance in both

programs, but other species have been added.

Justification for research on a particular species

sometimes results more from its importance

to wildlife than from its importance to fiber

production. Federal cost-sharing programs,

e.g., the Conservation Reserve Program, drive

planting of southern bottomland hardwoods on

nonindustrial private land almost entirely. Demand

is high now for hardwood seed to support Federal

cost-share programs (Byram and others 2000),

and if these programs are expanded through

the extension of eligibility to additional lands,

hardwood planting could increase substantially,

and demand for improved seedlings would

correspondingly increase.

Tree improvement efforts on Federal land

in the South have shifted dramatically over

the last 15 years. This is mainly because new laws

have reduced the number of acres harvested and

have subsequently reduced the number of acres

planted annually. As rotations have lengthened

and management programs have become less

intensive, pine improvement programs are no

longer justified for Federal lands (Tibbs and

Windham 1999). Under current policy, only

northern red oak and white oak (Q. alba L.) will

have artificial regeneration programs, and these

will rely on seedling seed orchards. Hardwood

species that are difficult to maintain or are

threatened by introduced pests such as American

chestnut [Castanea dentata (Marsh.) Borkh.],

butternut (J. cinerea L.), and dogwood (Cornus

florida L.) receive special attention (Tibbs and

Windham 1999) as gene conservation becomes a

major focus of more programs (McCutchan 1999).

The University of Tennessee and the Georgia

Forestry Commission are partners with the Forest

Service in these projects.

Genetic improvement of eastern cottonwood is

probably more advanced than that of any species

in the South. Ease of vegetative propagation,

abundant seed production, and established

techniques for controlled pollination have enabled

programs to make significant advancements.

Clones developed by the Southern Forest

Experiment Station and the Texas Forest Service

form the basis for several current programs,

including the interspecific hybridization programs

in the Pacific Northwest and around the world.

Westvaco (now MeadWestvaco) probably has had

the most consistent cottonwood program since the

closure of the Stoneville project. Both clone and

progeny tests were established throughout

the 1980s. These were aimed at increasing

realized gains, establishing a genetically diverse

deployment population, and constructing a viable

breeding population. Today, fiber farms (irrigated

and fertilized plantation systems) are being

investigated as a source of hardwood fiber for

various southern mills. Improvement programs

are targeting these sites for their specific needs.

The U.S. Department of Energy (DOE) is

currently sponsoring research to develop Populus

clones for the Southeast as part of their Biomass

Fuels Program (Land and others 2000). Breeding

and testing programs are active at Mississippi

State University. New seed collections have been

made from throughout Southeastern United

States and clone tests have been established in

Missouri (MeadWestvaco), Florida (University

of Florida), Alabama (Boise Cascade), and North

Carolina (International Paper).

Venture companies are exploring the

possibilities for commercializing transformation

products in a number of species. The Southeast

will also benefit from work being accomplished

at the Tree Genetic Engineering Research

Cooperative at Oregon State University and the

Poplar Molecular Genetics Cooperative at the

University of Washington, especially in the genus

Populus. The most exciting effort to date is the

genomic sequencing work that is being done with

Populus, which is being funded through the DOE

(Anon. 2002). This effort is already developing

projects aimed at increasing production of

hemicellulose and auxin.

Unlike southern pine tree improvement,

hardwood tree improvement has generally lacked

a unified approach or the benefits of having a

single-species focus. McKnight recognized this

in 1975 when he characterized hardwood tree

improvement as a “haphazard thing, a searching

for meaning and direction.” These words are

still accurate when summarizing hardwood tree

improvement efforts in not only the Southeast

but throughout the United States. Numerous

programs have been intensive at times only to

be closed when demand lessens, when research

dollars tighten, when raw material costs decrease,

or when the perception of a hardwood shortage is

replaced by problems of greater importance. This

wavering has limited gains, mainly because it has

necessitated the rebuilding of testing and breeding

populations, something that has been avoided in
103Chapter 10. Genetics and Tree Improvement

the continuous pine tree improvement programs

of the South. Several major factors contribute to

the unique aspects of hardwood tree improvement;

these include the number of species, their site

sensitivity, and their infrequent occurrence in

even-aged monospecific stands (Land 1975).

As with past programs, current hardwood

programs face a lack of long-term funding because

hardwood furnish is perceived to be low in cost and

accessible even though numerous southern mills

are reaching further for their hardwood fiber

supply. Even though large amounts of hardwood

fiber are needed to sustain these mills, little has

been invested in research to develop low-cost

hardwood fiber sources that would provide

substantially higher yields than natural stands

do, and in less time. Industry funding has become

even more restricted with the recent downturn

in the paper industry. The funding crunch is also

affecting long-term cooperatives through mergers

and the capitalization of the supporting land base

that is thought to be nonstrategic to a specific

mill. Today’s industrial programs are faced with

a need to develop plantation schemes that will

meet return-on-investment demands and build

programs focused on one or two species that

are adapted over a range of sites throughout

the South.

THE FUTURE OF TREE IMPROVEMENT

IN THE SOUTH

M

any new tools are available to aid in

efficiently manipulating the genes of

forest trees. While traditional methods

of quantitative genetics have been very

effective, they can be enhanced with emerging

technologies. There are exciting new possibilities

for improvement through advances in

biotechnology that allow incorporation of genes

for traits such as herbicide resistance, insect

resistance, increased cold tolerance, modified

lignin, and growth. A requisite first step to

applying biotechnology to plantations is the ability

to vegetatively propagate selected clones. Rooted

cuttings of many hardwood species and fewer

conifers have been used in intensive forestry

practices for decades and in a few situations

for centuries. Classic examples include willows

(Salix spp.), poplars, and sugi (Cryptomeria

japonica D. Don), which has been clonally

propagated for > 1,000 years and used in

plantation forestry in Japan since around A.D.

1400 (Toda 1974). Unfortunately, most conifers

and certain recalcitrant hardwoods have not been

clonally propagated successfully. The primary

obstacle to success is maturation. As seedlings of

these species that are difficult to root mature, they

undergo many morphological and physiological

changes. One important trait that changes is the

ability of severed stems to form adventitious roots.

For these species, rooting of cuttings collected

from very juvenile seedlings will often be high

(> 80 percent), but rooting success of cuttings

from open-grown trees typically drops to almost

zero over a period of 2 to 10 years.

In many species, juvenility (the ability to form

adventitious roots and rapid growth of rooted

cuttings) can be maintained for several years

through severe pruning (hedging) of stock plants

to produce cuttings for rooting (Goldfarb and

others 1997, Rowe and others 2002). Cuttings can

be rooted at high frequencies even when taken

from hedged loblolly pine that is several years

old (Cooney and Goldfarb 1999). Rooted cuttings

of this type grow as rapidly as seedlings from the

same families (Frampton and others 2000, Stelzer

and others 1998).

Other strategies exist for maintaining juvenility

until clones can be selected and multiplied. One

strategy employs establishing clone trials from

stock plants while maintaining juvenility of the

stock plants through selection age. A possible

modification could include establishment of clones

as axillary shoot cultures and maintaining the

cultures at temperatures that are low but above

freezing to delay maturation.

A second strategy being pursued consists of

initiating somatic embryogenic cultures from

candidate seeds. The cultures would be divided

to generate somatic seedlings for clonal field tests

while the remaining portions of the culture would

be placed in liquid nitrogen for cryopreservation.

When superior clones have been selected,

preserved cultures could be recovered, multiplied,

and used to generate somatic seedlings for

reforestation. For the southern pines, all of these

steps have been achieved, but there are limitations

in the efficiencies of each step in the process.

Also at this time, only a relatively low percentage

of genotypes (families and clones) can be

successfully propagated through all the steps.

Ultimately, the strategy most likely to be

employed widely will be the one with the lowest

cost per genetic gain delivered. Both technologies,

though possible on a research scale, still require

further development on an operational scale, so it

is difficult to precisely predict gains and costs.

Perhaps the ideal system would comprise elements

of both technologies. That is, clones would be
Southern Forest Science:

Past, Present, and Future

Productivity

104

started as embryogenic cultures, cryopreserved,

and clonally tested with somatic seedlings.

Once selected, a moderate number of somatic

seedlings could be turned into stock plants for

large-scale, low-cost production of rooted cuttings

for reforestation stock. Despite technological

and strategic uncertainties, it appears likely

that research advances in recent years, together

with the potential genetic gains available and

the widespread interest of many industrial

landowners, will result in the development

of some clonal system for the southern pines

in the near future.

A third strategy, which may only be applicable

to certain species, utilizes alternative explant

sources from mature trees to initiate cultures.

Pioneering work at the University of Georgia

(Sommer and Brown 1980, Sommer and others

1985) has led to the propagation of mature trees

via staminate inflorescence tissues (Merkle and

others 1997). Sweetgum propagation has been an

ongoing project at the University of Georgia since

the mid-1970s. The development and refinement

of asexual propagation techniques for sweetgum

has been ongoing at North Carolina State

University since the mid-1990s. Efforts have

focused on optimizing the collection of cuttings,

storage methods, basal auxin treatments, and

transplanting times (Anon. 1998, 1999, 2000;

Rieckermann 1995; Robison and others 1999).

Recent success in both rooting and survival

of sweetgum, however, has been tempered by

poor shoot growth following rooting (Anon. 2001,

Gocke and others 2001). Sweetgum would be more

widely adaptable for use on southern sites than

more easily propagated Populus, Salix, or

Eucalyptus species.

True clonal forestry as is practiced with

Eucalyptus species in many tropical countries

(Zobel and others 1987), and with Populus species

in temperate regions (e.g., Li and Wyckoff 1993,

Stettler and others 1988), provides additional gains

not possible through conventional breeding. When

specific clones of any age tree can be propagated,

the full genetic potential of the population can

be utilized. Because no sexual recombination

occurs when clones are propagated, there is no

opportunity for specific gene combinations to be

lost. If maturation can be reversed or at least

arrested, clonal forestry for southern pines and

recalcitrant hardwoods will likely become a reality.

Productivity increases from clonal forestry have

often been dramatic. The best clones of E. grandis

(Hill ex Maiden) in Brazil produce 70 m3

/ha/year,

whereas unimproved seedlings produce only

half this much volume (Zobel and others 1987).

Similar benefits for hybrid poplars in the Pacific

Northwest of the United States have also been

realized. The best clones from hybrid crosses of

P. trichocarpa x P. deltoides produce yields that

are > 100 percent better than those produced

by average seedlings (Stettler and others 1988).

As clonal forestry becomes practical in more

species, breeding will adapt from a population

improvement approach to one that will capture

heterosis by producing individual elite genotypes

(Tuskan 1997).

Multiplication of specific full-sib families

that have demonstrated proven performance

has become operational with Pinus radiata D.

Don and has had major economic impact on

plantation programs in New Zealand, Australia,

and Chile (Balocchi 1997). Several companies in

the Southeastern United States are actively

pursuing a similar strategy for the southern pines.

Deployment of genetically improved planting

stock is the only opportunity breeders have to

directly impact forest productivity. The number

of methods to affect the type of propagule that

will be deployed has increased and will continue

to increase with the help of molecular genetics.

Already molecular geneticists and breeders have

collaborated to identify genes that are important

in controlling economically important traits. In

loblolly pine, for example, major genes for disease

resistance (Wilcox and others 1996), specific

gravity of wood (Groover and others 1994), and

volume production (Kaya and others 1996) have

been identified using DNA markers that are

associated with the locus or loci controlling the

economic trait.

Using marker-trait associations effectively

is not straightforward (Bradshaw 1996, Johnson

and others 2000, O’Malley and McKeand 1994,

Williams and Byram 2001, Wu and others 2000).

Marker-assisted selection will likely supplement

traditional selection methods in some elite

breeding programs. However, molecular markers

are expensive, and determining the marker-trait

association with field trials is even more expensive.

It is very likely that markers associated with

desirable traits in one parent will have different

associations in other parents. Only if linkage

disequilibrium is common in a population will

marker-trait association be the same in each

member of the population (O’Malley and McKeand

1994), and it is unlikely that this situation is

common (Strauss and others 1992). In the future,
105Chapter 10. Genetics and Tree Improvement

if the investment is made to map genotypes

of all parents in an elite breeding program, the

incremental cost of using the markers for selection

in both breeding and deployment populations

could be reduced. Again this promising technology

awaits improvement in cost efficiency (Johnson

and others 2000).

Molecular geneticists’ greatest contribution to

tree improvement may be a better understanding

of the processes of wood formation and growth.

With knowledge about processes such as lignin

biosynthesis (e.g., MacKay and others 1997),

molecular geneticists hope to manipulate the

process to make pulping more efficient (e.g.,

Dimmel and others 2001). Genetic engineering, or

the insertion of foreign genes into the genome of a

desirable clone, has been realized in forestry. In

species in which tissue culture via organogenesis

or embryogenesis is feasible, insertion of genes

has great potential. One of the major factors that

will hamper hardwood molecular biology programs

is the lack of highly sophisticated conventional

breeding programs for most species.

Advances in mapping and transformation

have been more rapid in hardwoods than in the

pines because of their relative ease of culture

and manipulation. Indeed, various Populus species

and sweetgum have become model species for

industrial and cooperative biotechnology

programs. This is even more evident with the

recent announcement of a project to sequence a

Populus clone (Anon. 2002). Development of

molecular resistance to more environmentally

friendly herbicides would reduce establishment

and early rotation maintenance costs that have

plagued hardwood plantations. This possibility

has tremendous potential, and transgenic tests

throughout the United States are providing

insights into it. While this trait alone would allow

for a tremendous increase in hardwood plantation

acreage in the South, the addition of other

characteristics, such as reduced lignin content,

would provide even more impetus.

It is unlikely that transformed [genetically

modified (GM)] trees will be widely deployed

until the negative public perception of their use

can be changed. This issue is likely to be a serious

impediment to tree improvement in general.

Recent attacks by bioterrorists have resulted

in the destruction of transformed trees, vehicles,

laboratory buildings, and ordinary selected trees

in a tree improvement program (Kaiser 2001,

Service 2001). Most of the June 2002 issue of

“Nature Biotechnology” (volume 20, number 6)

was devoted to various aspects of the use of

GM crops.

CONCLUSIONS

G

enetic tree improvement and plantation

management has had and will continue to

have a positive impact on forestry and forest

management worldwide. The demand for forest

products will continue to increase, and intensive

management will be needed to meet this demand.

Plantation management of fiber farms can also

alleviate pressure on ecologically sensitive forests

and provide year-round accessibility to wood. Tree

improvement can best promote the conservation

of forest ecosystems by providing high-yielding,

adaptable planting stock for these fiber farms.

Tree breeders must be cautious in the use of

the genetic resources in breeding populations. The

rich genetic variation in most tree improvement

programs is an endowment that must be skillfully

managed. Fortunately, breeders have learned to

manage populations both for short-term financial

benefit and long-term conservation of genetic

variation. The future of tree improvement for

both pines and hardwoods is bright, with more

challenges, more available tools, and more

opportunities for gain than ever before.

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109

Chapter 11.

Forest Mensuration with Remote Sensing:

A Retrospective and a Vision for the Future

Randolph H. Wynne1

Abstract—Remote sensing, while occasionally

oversold, has clear potential to reduce the overall

cost of traditional forest inventories. Perhaps most

important, some of the information needed for

more intensive, rather than extensive, forest

management is available from remote sensing.

These new information needs may justify increased

use—and the increased cost—of remote sensing.

Organization of the United Nations 1997). Much

of this loss resulted from the conversion of forest

land to nonforest uses such as agriculture, pasture,

or development. Environmental regulations

and the desire to preserve native forests to

maintain biodiversity further restrict harvesting

of forest products. For example, harvest of timber

from the national forests in the United States

decreased from 12.0 billion board feet in 1989 to

3.5 billion board feet in 1997 as the focus of the

U.S. Department of Agriculture Forest Service

shifted from timber production toward wilderness

preservation, protection of habitat for threatened

and endangered species, watershed protection and

restoration, and recreation (U.S. Department of

Agriculture, Forest Service 1998).

Industry Trends Affecting Remote Sensing

Many forest industry trends will affect the

future of remote sensing in forestry. Some of

the most important are as follows:

• Smith and others (2003) note that industrial

forest landowners have moved from an

exclusive emphasis on supplying fiber toward

a view of forest land as a biological asset that

must be managed financially. If this is true,

additional information inputs, such as remote

sensing, that increase financial returns might

well be justified.

• As noted earlier, industrial forest management

is increasing in its intensity, partly because

there has been an effective decrease in the

amount of public land available for active

management. It can make economic sense

to spend more for information about the

forest resource if the additional expenditure

decreases the overall cost of inputs, particularly

in the establishment and early growth phases.

• Information available from digital remote

sensing can now be combined with other

digital geospatial information to provide

a complete scheduling picture from site

preparation to harvest scheduling within

an organization.

1 Associate Professor, Virginia Polytechnic Institute and State

University, Department of Forestry, College of Natural

Resources, Blacksburg, VA 24061.

INTRODUCTION

Forestry Information Needs of the 21st Century:

Increasing Demand and a Changing Landscape

D

emand for forest products is expected to

increase rapidly during the 21st century.

Population growth and economic development

that increase the per capita consumption of forest

products drive this trend. Global population, now

approximately 6 billion, is estimated to increase

by 900 million each decade for the next 50 years

(Food and Agriculture Organization of the

United Nations 1997). Most of this increase will

occur in developing nations. Level of economic

development strongly affects the demand for

forest products. Worldwide income measured as

gross domestic product increased by 109 percent

between 1970 and 1994 (Food and Agriculture

Organization of the United Nations 1997). Gross

domestic product is estimated to rise from $20

trillion in 1990 to $69 trillion in 2030, with the most

dramatic increases occurring in the developing

nations (World Bank 1992).

Although the demand for forest products

is increasing, global forest area is decreasing.

Between 1985 and 1995, the area of the world’s

forests decreased by 180 million ha, an annual

loss of 18 million ha (Food and Agriculture
Southern Forest Science:

Past, Present, and Future

Productivity

110

Chapter Overview

Remote sensing has been actively integrated

into forest inventory and management systems

for more than half a century. The methods used

now are still effective, but there is much potential

for increased use of remote sensing both for

traditional inventory purposes and to provide

the information necessary to increase forest

productivity. This chapter starts with a

retrospective view of photo mensuration, and

this is followed by a brief discussion of lidar

remote sensing, one of the more promising

new technologies for collecting data for forest

inventory and monitoring. The discussion of lidar

remote sensing is followed by an example that

shows how information obtained by remote

sensing could increase productivity and, thus,

justify increased expenditure for information.

The chapter closes with a brief discussion of

barriers that must be overcome before remote

sensing data are transformed into information

directly useful to foresters.

WHERE WE HAVE BEEN: PHOTO

MENSURATION

V

ertical aerial photographs, while used in

forestry since the late 1920s (particularly in

Quebec and Ontario, Canada) (Spurr 1960),

have been commonly used by foresters in the

United States since the 1940s (e.g., Lund and

others 1997). Forestry applications of aerial

photography have been diverse, covering most

aspects of the private and public goods provided

by forests. However, a primary driver for forest

photogrammetry has been forest mensuration,

classically defined as “the determination of

dimensions, form, weight, growth, volume, and

age of trees, individually or collectively, and of

the dimensions of their products” (Helms 1998).

Substantial effort has gone into ways of using

photographs as a means of determining volume

by species accurately, precisely, and at the lowest

possible cost. This effort has been reasonably

successful, but applications of aerial cruising

(e.g., Avery 1978) are becoming significantly

less common in the United States, although

quite common elsewhere (e.g., Canada).

There are several possible reasons for the

decline of photographic mensuration. These

can be summarized as follows:

1. The precision of photographically derived

volume estimates is not as high as that of

field-derived volume estimates.

2. Photographic interpretation and

photogrammetry require specialized skills

that are increasingly being supplanted by

other ones, such as skills in the use of

Geographic Information Systems (GIS), in

accredited forestry programs (Sader and

Vermillion 2000). This is occurring despite

results from the most recent survey of desired

entry-level competency and skill requirements

which show that more entry-level forestry

positions require knowledge of aerial photos

(68 percent) than GIS (43 percent) (Brown

and Lassoie 1998).

3. In much of the United States, forest land

parcel size is steadily decreasing and

accessibility increasing, thus decreasing

the economic justification for (or even the

feasibility of) photo mensuration.

4. Research in forestry remote sensing now

focuses on actual and potential applications of

newer airborne and spaceborne sensors, such

as radar, lidar, and high-resolution digital

optical sensors.

5. Wide use of medium-resolution spaceborne

sensors such as the Landsat Multispectral

Scanner and Thematic Mapper that are

inherently digital has led to an expectation

of ever more automated approaches to

information extraction. Most algorithms in

operational use are based almost entirely on

the use of discriminant functions to categorize

the brightness value vector from each pixel,

even though this approach makes use only of

hue. Hue is just one of the nine commonly

identified elements of image interpretation,

the others being shape, size, pattern, texture,

association, shadows, resolution, and site

(Olson 1960).

6. The actual or perceived benefits of using

photos for inventory may be less than the

costs incurred.

The last of these points is the most important,

since we can assume that forest managers and

scientists are obtaining the information needed

without widespread use of ordinary photography.

However, demands on forests are increasing, and

the information required to sustainably manage

forests in the face of this demand must also

increase. Foresters are being asked to increase

production of wood and fiber on an everdecreasing land base while maintaining the

important supplies of public goods (viable fish
111

and wildlife populations, clean water, and

recreational opportunities) that well-managed

forests have always provided. To meet this

challenge, forest managers will require new

types of information, and remote sensing will

help to supply these. If remote sensing fills our

requirements, we will need to evaluate previous

successes and failures and work to improve the

match between information that can be objectively

and accurately derived from remotely sensed

data and the information needed for forest

management (Wynne and others 2000).

Aerial Cruising

Aerial (photo) volume tables have been

constructed for both individual trees and stands

(Avery 1978). All are based on total tree height

and visible crown diameter for individual trees.

For stands, volume tables use stand height and

percent crown closure at a minimum; many also

include visible crown diameter classes. These

tables use visible crown diameter as a surrogate

for stem diameter and percent crown closure as

a surrogate for basal area or stem density.

Tree heights are typically measured by

stereoscopic parallax methods that employ

a parallax bar or wedge and large-scale

photographs. Shadow lengths can be used where

terrain is level and stands are relatively open.

While the accuracy of these measurements varies,

on 1 inch = 20 chains photography, the average

difference between ground- and photo-measured

tree heights (with well-trained interpreters)

is typically about 1 foot (Spurr 1960).

Visible crown diameter is measured with either

a micrometer wedge or a dot-type scale. It can be

argued that crown diameter is more accurately

measured on large-scale photographs than on the

ground, but measurements made on photographs

are not directly comparable to those made on

the ground because in photographs (1) only the

dominant overstory trees are visible, and (2) the

edges of any particular crown are obscured by

the crowns of adjacent trees. For these reasons,

photo-derived visible crown diameters are always

underestimates of actual crown diameter. Even

given these limitations, however, photo-measured

visible crown diameter is often better correlated

with actual tree and stand volume than fieldmeasured crown diameter, because it is a measure

of the tree’s functional growing space (Spurr

1960). Measurement consistency varies widely

with conditions, but can be expected to be on

the order of 3 to 4 feet two times out of three on

1:12,000 photos (Paine 1981), which is why

most volume tables are based on 3- to 5-foot

diameter classes.

Percent (overstory) crown cover is the most

subjective of the three direct forest measurements

made from aerial photographs. It can simply be

ocularly estimated or (more commonly) ocularly

estimated with the aid of crown density scales. It

usually is an overestimate of actual crown cover,

because small canopy gaps are often not visible

and shadows are often treated as trees. When

typical forestry photo scales are used, standard

errors do not exceed 10 percent, but the bias of an

individual interpreter commonly ranges from 5 to

10 percent (Spurr 1960).

However, volume estimates derived by using

stand photo volume tables are too imprecise for

many uses, as standard errors of the estimate are

likely to exceed 25 percent (Spurr 1960). While

standard error can be reduced by increasing the

number of samples, stand photo volume tables

are also biased, requiring double sampling with

regression using matched field- and photomeasured plots (e.g., Paine 1981). This casts

doubt on the economic feasibility of photo

mensuration for the smaller tracts that are

increasingly common.

To summarize, timber volume can be estimated

from aerial photographs. Bias exists because

(1) a vertical aerial photographs image-only

portions of the crowns of dominant overstory

trees; and (2) subjectivity, particularly in crown

closure estimation, leads to interpreter-specific

bias. The latter bias also leads to unacceptably

high standard errors of the estimate. Substantial

training that is increasingly hard to obtain is

required to make accurate direct tree and stand

measurements based on aerial photographs. All

these factors combined make the use of aerial

inventory cost-effective primarily for large,

relatively inaccessible areas.

Stratification

At this point one might reasonably ask why

acquisition of photography is still so routine in

many organizations charged with managing forest

lands. The answer is, in part, that photos are used

for more than just aerial timber cruising. Other

uses include forest mapping for management

planning, stress detection, forest area estimation,

and land navigation, particularly in remote and

infrequently mapped areas. These uses, however,

are often secondary in comparison to the routine

Chapter 11.

 Forest Mensuration with Remote Sensing
Southern Forest Science:

Past, Present, and Future

Productivity

112

use of photos to stratify timber cruises.

Stratification refers to “the subdivision of a

population into strata (subpopulations) before

sampling, each of which is more homogeneous

for the variable being measured than the

population as a whole” (Helms 1998).The

advantages of stratification include (1) more

precise estimation of the population mean

(given properly constructed strata), (2) separate

estimates for each subpopulation, and (3) reduced

costs (Avery 1978, Avery and Burkhart 2002). As

Avery and Burkhart note (2002), photographs are

commonly used in stratified sampling to measure

area, allocate field samples by volume classes, and

plan fieldwork. For many organizations, photo

acquisition can be justified by stratified sampling

alone. This stratified sampling not only improves

precision and reduces cost, but also changes

the flow of information within an organization,

with the result that there is a two-way flow

between field personnel and the organization’s

information systems.

WHERE WE ARE GOING: THE

EXAMPLE OF LIDAR

L

idar, or light detecting and ranging, sensors

are the optical equivalent of radar. They use

a light (laser) beam, rather than a microwave

radar beam, to obtain measurements of the speed,

altitude, and range of a target (Helms 1998).

Most of the current small-footprint (< 1 m) laser

altimeters can record the time (and sometimes

intensity) of at least two returns, which often

correspond to the top of the canopy and the

ground. Many times, however, only one return

is recorded, and it may correspond to vegetation,

the ground, or some cultural feature. Sophisticated

processing algorithms utilizing neighborhood

approaches can usually identify the bulk of the

nonground returns, thus making it possible to

create a bare-earth digital elevation model (DEM)

with suitable interpolation techniques. Once a

DEM has been created, the first returns can be

interpolated to produce a canopy height model, a

representation of the vertical distance from any

arbitrary point on the forest floor to the topmost

part of the canopy above that point. Over forested

areas, the canopy height model provides canopy

height at any point imaged. The canopy height

model differs from photogrammetrically derived

tree height in one important way—the canopy

height model is a continuous representation of

the canopy surface, rather than the height at any

one point. It should be noted that canopy height

models can be derived photogrammetrically, but

many automated image-correlation algorithms

function comparatively poorly over tree canopies.

From this canopy height model, and sometimes

in conjunction with coregistered optical data

(Gougeon and others 2001, McCombs and others

2003, Popescu and others 2004) tree, or more

typically stand, volume can be determined using

direct measurements corresponding to those made

from photographs, namely total height, visible

crown diameter, and percent crown closure

and or stem counts. Some of the same problems

associated with direct measurements from

photographs also pertain to lidar. These are as

follows: (1) lidar sensors measure the distance

only to the crowns of overstory vegetation;

(2) direct measurements from lidar tend to be

biased (e.g., Nilsson 1996); and (3) lidar data are

very expensive unless some economy of scale is

realized. However, there are two substantial

benefits. Firstly, the data seem to be very

amenable to processing by automated techniques

(at least for conifers), which increases objectivity

and thus precision. Secondly, when direct

measurements are used in empirical models to

estimate either field-measured, e.g., total height,

or derived parameters, e.g., volume or basal area,

stand-level predictions are unbiased (Means and

others 2000, Naesset 2002).

Again, stand volume tables require measures of

height, percent crown cover, and sometimes crown

diameter. Lidar-based estimates of volume require

similar measurements. Determination of individual

tree heights using lidar data requires identifying

individual overstory stems, usually through a local

maximum approach that presumes that the highest

point in a local neighborhood corresponds to the

top of a tree. Although this technique is effective,

errors of omission or commission can occur with

improper window size. Popescu and others (2002)

used the height of each cell in the canopy height

model to set the size of a variable window based

on tree height, making possible the successful

prediction (R2

 = 90 percent and 85 percent,

respectively) of maximum height and mean height

of dominant stems (diameter at breast height

> 5 inches) even on very small 0.017-ha (0.04-acre)

plots of common southeastern conifer species. As

plot size increases, the need to measure individual

trees decreases, and the percentage of variance

explained increases. For example, Means and

others (2000) used lidar-derived variables—

without identifying individual trees—to explain
113

93 percent of the variance in height on 0.25-ha

(0.6-acre) stands of Douglas-fir [Pseudotsuga

menziesii (Mirb.) Franco].

Percent crown cover is particularly easy to

calculate using lidar data; it is simply the number

of vegetation (nonground) returns above a certain

height divided by the total number of returns.

Crown diameter, however, has been a little more

difficult to determine, as it requires accurate stem

identification as well as a way of distinguishing one

crown from the adjacent one. There is substantial

ongoing work in this area, but Popescu (2002)

determined crown diameter for each identified

tree by (1) fitting a 4-degree polynomial with least

squares using singular value decomposition in

both the horizontal and vertical dimensions of

the canopy height model, (2) identifying critical

points for each of the two fitted functions based

on the first and second derivatives of a threepoint Lagrangian interpolation, and (3) averaging

the distance between critical points on the two

perpendicular profiles. For southern pines, this

technique explained 62 to 63 percent of the

variance in crown diameter for the dominant

trees on 0.017-ha plots (Popescu and others 2002).

Like photos, then, lidar canopy height models

can serve as the base data from which important

variables can be measured; namely, visible crown

diameter, percent crown closure or stem count,

and total height. In addition, variables unique to

canopy height models, particularly those relating

to the distribution of heights within any one grid

cell or plot perimeter, have been successfully used

as independent variables in models employed to

estimate plot- or stand-level parameters (e.g.,

Means and others 2000, Popescu and others 2002).

Examples of this type of variable include the

percent crown cover or height at a specific

height percentile.

Volume has been successfully calculated for

conifers by use of lidar-derived measures of

height, crown closure, stem density, and/or

crown diameter, or of variables relating to the

distribution of heights within a particular grid cell.

Popescu and others (2004) was able to explain > 80

percent of the variance in volume on small (0.017-

ha, 0.04-acre), heterogeneous southern pine plots

in Virginia’s Appomattox-Buckingham State

Forest using average (per plot) crown diameter

obtained by applying a lidar-derived canopy height

model as the only independent variable. Means

and others (2000) were able to explain 97 percent

of the variance in 0.25-ha (0.6-acre) Douglas-fir

plots in the H.J. Andrews Experimental Forest

using the 80th and 0th percentile of height (the

height greater than the given percentage of lidar

first returns) and the 20th percentile of crown cover

(proportion of first returns below the given

percentage of total height). Many other studies

have been similarly successful in estimating

volume for coniferous plots or stands on the basis

of lidar data.

Lidar-based forest measurements, while based

on many of the same principles as photo-based

measurements, such as using crown diameter

as a surrogate for stem diameter, are typically

more accurate and less biased than photo-based

measurements. As with aerial photographs, bias

exists because laser altimeters see only portions

of the crowns of dominant overstory trees.

However, increased levels of automation have

led to substantial reductions in both interpreterspecific bias and the need for specialized training.

Furthermore, lidar canopy height models afford

the characterization of the whole population,

rather than just a sample, of the dominant

overstory trees in a specific area of interest.

However, lidar data are still quite expensive for

small areas on a per-unit basis, so lidar-based

inventory, like photo analog inventory, is costeffective primarily for large and/or relatively

inaccessible areas. This description hardly

characterizes the typical southern forest

landscape, which is dominated by the holdings

of nonindustrial private forest landowners.

THE LIKELY FUTURE NEED FOR ADDITIONAL

REMOTELY SENSED DATA

T

he most commonly used standard for all

remotely estimated forest measurements

is field inventory, which typically employs

remotely sensed data only for stratification. Thus

in order to be widely accepted and used, remotely

derived estimates of important forest biophysical

parameters must have the same level of precision

and accuracy as field-derived measurements,

and be less expensive than they are. The lack of

widespread adoption of these new technologies

is de facto proof that this standard has not yet

been met. As with all technological innovation,

however, the cost per unit of information derived

from remotely sensed data will continue to

decrease, thus increasing their potential use for

traditional inventory needs as a tradeoff with

field costs. Another factor to be considered is that

increasing forest productivity will require more

remotely sensed data. Organizations will be willing

to spend more for information if this expenditure

results in increased productivity.

Chapter 11.

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Past, Present, and Future

Productivity

114

JUSTIFYING INCREASED USE OF

REMOTELY SENSED DATA: THE EXAMPLE

OF INTENSIVE (AND/OR SITE-SPECIFIC)

FOREST MANAGEMENT

M

ost of the preceding discussion has focused

on traditional assessment and inventory,

an ongoing need whose importance is not

likely to diminish in the near future. However,

inventories using existing remote sensing

technologies suffer, on the whole, from being

more expensive and less accurate than field

inventory for the small tracts that are coming

to dominate the southern forest landscape.

Thus they are not widely used in most instances.

However, traditional assessment and inventory

is only part of a larger picture of forestry

information needs—needs that are likely to

become urgent as management for increased

production intensifies on some private tracts

and the demands for multiple uses continue to

drive public forest management. The following

discussion addresses the potential effect of more

intensive management of portions of the private

land base on the future of forestry remote sensing.

Partially as a result of increased demand, and

partially as a consequence of effective reductions

in the land base resulting from (1) permanent

land use conversion, (2) changes in public land

management priorities, and (3) changes in

the motivations and attitudes of nonindustrial

private forest landowners, forest managers are

increasingly being called upon to produce more

wood or fiber from less land with shorter rotations.

This challenge is being met with silvicultural

tools that have agricultural analogs, such as site

preparation, nutrient management, release from

competition, and improved genetic stocks. The

agricultural model can be pushed even farther

as management intensifies; it can be argued that

intensive forest management is as suited for

precision forestry as intensive farm management

is suited for precision agriculture. Mulla’s (1997)

definition of precision agriculture is as follows:

Precision agriculture is an approach for

subdividing fields into small homogeneous

management zones where fertilizer,

herbicide, seed, irrigation, drainage, or

tillage are custom-managed according to

the unique mean characteristics of the

management zone.

Precision forestry is analogous to precision

agriculture in that traditional management units

(forest stands are analogous to agricultural fields)

must be subdivided for specific prescription of

silvicultural treatments; e.g., site preparation,

fertilization, and release from competition.

However, there are some important differences

between precision agriculture and precision

forestry. Forest stands are typified by the

(1) important array of public goods provided,

such as clean water, wildlife habitat, carbon

storage, and recreational opportunities; (2) much

longer rotations required; (3) widespread use of

helicopters for spraying; (4) species; (5) minimal

use of irrigation; and (5) general lack of effective

yield monitoring at the time of harvest. This

last difference cannot be seen as problematic

for precision forestry, as many experts (e.g.,

Pierce and Nowak 1999) agree that yield-based

determination of preharvest spatial variability

is a temporary solution, to be replaced by the use

of remote sensing technologies. Given the relative

importance and degree of development of forestry

applications of remote sensing, precision forestry

should not need to evolve through the yieldmonitoring stage. Furthermore, precision forestry

subsumes precision silviculture, precision

inventory, precision growth and yield, and

precision harvest scheduling, creating a complete

information pathway. Remote sensing and related

geospatial information technologies provide the

inventory information necessary to (1) define the

treatment unit for each silvicultural prescription

and (2) provide the within-stand measurements

of forest biophysical parameters necessary for

growth-and-yield models and related harvest

scheduling models.

Landowner records usually provide information

on stand type, age, initial stocking density, and

site preparation. Required parameters suited to

remote estimation include leaf area index, current

stem density, crown diameter, height, and species

or species group. The last is especially helpful

for timing and/or locating need for release from

competition. Foliar nutrients can also be assessed

using airborne hyperspectral, or, potentially,

tailored handheld instruments (e.g., Bortolot and

Wynne 2003), though such approaches have so far

not been cost-effective when compared with lab

analysis of foliar samples.

The relative need for and cost:benefit ratio of

remotely sensed and precisely located in situ data

must drive both the research in and the adoption

of appropriate technologies. Furthermore within

the wide variety of remotely sensed data that are

well suited for precision forestry applications,

researchers must find the best combination of
115

spectral resolution, spatial resolution, and canopy

height information for estimating each required

parameter. Data types include but are not limited

to (1) canopy height models derived from lidar or

digital photogrammetry, (2) high spatial-resolution

optical data, (3) moderate-resolution multispectral

data, and (4) hyperspectral data at a variety of

spatial resolutions. Research being carried out

by Government, industry, nongovernmental

organizations, and universities is providing the

base for improved integration of remote sensing

in forest management. However, the gap between

remote sensing research and accessible, useful

information is still too large.

FROM DATA TO APPLICATIONS

I

t has been said that production forestry

organizations make or lose money near the

bottom rungs of the organizational ladder,

not at the top (Smith and others 2003). Most field

foresters have substantial experience with aerial

photographs but have neither the time for nor

the interest in processing images from digital

remotely sensed data. In many cases, given the

widespread use of and familiarity with aerial

photographs in forestry, digital images can be

subjectively analyzed for the wide variety of

applications mentioned in this chapter. However,

it can be argued that this model limits the potential

utility of remote sensing to forestry, as it may not

provide any net increase in information. The kinds

of sensors that will help facilitate a net increase in

forestry information derived from remotely sensed

data include laser altimeters and hyperspectral

scanners. The data these sensors yield will only be

suited, in their raw form, for use by image analysts

or other experts in the same field. Field foresters

generally do not have the experience to qualify

as experts in image analysis. They “require

information, not images . . . .” (Oderwald and

Wynne 2000).

The National Research Council, in their

recent study on “Transforming Remotely Sensed

Data into Information and Applications” (2001),

identified three gaps that must be bridged

to develop effective civilian applications of

remote sensing:

1. The gap between raw data and the

information needed by end users

2. The gap in communication and understanding

between end users and those with remote

sensing technical experience and training

3. The financial gap between data acquisition

and usable applications

While these identified gaps apply across the

spectrum of end users, they are particularly

relevant for forestry. The report goes on to make

the following recommendations, which are also

quite pertinent to forestry:

1. Publicly available studies identifying the full

range of short-term and long-term costs and

benefits of remote sensing applications should

be carried out by a full range of public and

private stakeholders.

2. Cognate Federal Agencies should help fund

and foster a wide variety of remote sensing

training materials and courses.

3. Staff exchanges should occur between

remote sensing users and producers.

4. Graduate fellowships and research

assistantships should be sponsored by land

grant, sea grant, and agricultural extension

programs to encourage work at agencies that

use remote sensing data.

5. Federal agencies need to expand their support

for applied remote sensing research.

6. Formal mechanisms should be established to

enable applications users to advise private and

public sector providers on their requirements.

7. Data preservation is important and should be

routinely addressed by all data providers.

8. Internationally recognized formats, standards,

and protocols should be used whenever

possible to facilitate data exchange and ease

of use.

It is evident from the foregoing that forestry

is not the only application area where there is a

large gap between obtaining remote sensing data

and translating the data into useful information.

It is evident that concrete recommendations for

bridging this gap have been made. As a community

of forest scientists and managers, it is our

responsibility to identify information needs of the

future, and to make sure that adequate methods

of meeting these needs can be made available.

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Precision agriculture: spatial and temporal variability in

environmental quality. [Location of publisher unknown]:

John Wiley. [Number of pages unknown].

Naesset, E. 2002. Predicting forest stand characteristics

with airborne scanning laser using a practical two-stage

procedure and field data. Remote Sensing of Environment.

80: 88–99.

National Research Council. 2001. Transforming remote sensing

data into information and applications. Washington, DC:

National Academy Press. 75 p.

Nilsson, M. 1996. Estimation of tree heights and stand volume

using an airborne lidar system. Remote Sensing of the

Environment. 56: 1–7.

Oderwald, R.G.; Wynne, R.H. 2000. Field applications for

statistical data and techniques. Journal of Forestry. 98(6):

58–60.

Olson, C.E., Jr. 1960. Elements of photographic interpretation

common to several sensors. Photogrammetric Engineering.

26(4): 651–656.

Paine, D.P. 1981. Aerial photography and image interpretation

for resource management. New York: John Wiley. 571 p.

Pierce, F.J.; Nowak, P. 1999. Aspects of precision agriculture.

Advances in Agronomy. 67: 1–85.

Popescu, S.C. 2002. Estimating plot-level forest biophysical

parameters using small-footprint airborne lidar

measurements. Blacksburg, VA: Virginia Polytechnic

Institute and State University, College of Natural

Resources. 155 p.

Popescu, S.C.; Wynne, R.H.; Nelson, R.F. 2002. Estimating

plot-level tree heights with lidar: local filtering with a

canopy-height based variable window size. Computers

and Electronics in Agriculture. 37: 71–95.

Popescu, S.C.; Wynne, R.H.; Nelson, R.F. 2003. Measuring

individual tree crown diameter with lidar and assessing its

influence on estimating forest volume and biomass. Canadian

Journal of Remote Sensing. 29(5): 564–577.

Popescu, S.C.; Wynne, R.H.; Scriviani, J.A. 2004. Fusion of

small footprint lidar and multispectral data to estimate plotlevel volume and biomass in deciduous and pine forests in

Virginia, U.S.A. Forest Science. 50(4): 551–565.

Sader, S.A; Vermillion, S. 2000. Remote sensing education:

an updated survey. Journal of Forestry. 98(4): 31–37.

Smith, J.L.; Clutter, M.; Keefer, B.; Ma, Z. 2003. Special

commentary: the future of digital remote sensing for

production forestry organizations. Forest Science. 49(3):

455–456.

Spurr, S.H. 1960. Photogrammetry and photo-interpretation

with a section on applications to forestry. New York:

Ronald Press. 472 p.

U.S. Department of Agriculture, Forest Service. 1998.

Changing economics of the national forest timber sale

program. Washington, DC. [Number of pages unknown].

World Bank. 1992. World development report 1992:

development and the environment. Oxford: Oxford

University Press. [Number of pages unknown].

Wynne, R.H.; Oderwald, R.G.; Reams, G.A.; Scriviani,

J.A. 2000. Optical remote sensing for forest area

estimation. Journal of Forestry. 8–14.
Forest Health
Southern Forest Science:

Past, Present, and Future

Forest Health

118

Chapter 12.

Healthy Forests in the South:

Challenges for the 21st Century. ..................................................... 119

Chapter 13.

Restoration of Southern Ecosystems. ................................... 123

Chapter 14. Understanding and Controlling

Nonnative Forest Pests in the South. ................... 133

Chapter 15.

Advances in the Control and Management of the

Southern Pine Bark Beetles........................................... 155

Chapter 16. The Impact and Control of

Major Southern Forest Diseases. ............................ 161

Chapter 17. Monitoring the

Sustainability of the Southern Forest. ................. 179
119

Chapter 12.

Healthy Forests in the South:

Challenges for the 21st Century

T

he health of forests in the Southeastern

United States, as elsewhere in the country,

is tied closely to the history of human

presence on the land and the use and abuse of

its abundant natural resources. In his discussion

of the relationship between forest condition and

the Native American presence in the Southeast,

Rauscher (this book) makes two points. Firstly,

the forests of 500 years ago are believed to have

been very different from the forests of today.

Forests were more open, and their condition

was maintained by Native American fires.

Secondly, once Native American populations

were significantly reduced by disease, the forests

began to change, becoming more dense and

stratified. It is clear that few, if any, plants,

animals, or microbes from other continents were

present in North America before it was settled

by Europeans. Whereas large segments of Native

American populations were wiped out by foreign

diseases within 100 years of European settlement

on the continent, the effect of this settlement on

Native American vegetation was less immediate,

beginning in earnest in the middle to late 1800s,

and continuing today.

The condition of precolonial southeastern

forests and the changes to plant community

structure that resulted from harvesting and

the introduction of nonnative plants, animals,

and microbes have been well summarized

(Owen 2002). Owen (2002) lists several nonnative

diseases, insects, and plants—including chestnut

blight {Cryphonectria parasitica (Murrill) Barr

[formerly Endothia parasitica (Murrill) Anderson

& Anderson]}, Dutch elm disease [Ophiostoma

ulmi (Buisman) Nannf.], butternut canker

[Sirococcus clavigignenti-juglandacearum

(N.B. Nair, Kostichka & Kuntz)], white pine blister

rust [Cronartium ribicola (J.C. Fisch)], gypsy

moth (Lymantria dispar L.), balsam woolly

adelgid [Adelges piceae (Ratzeburg)], Japanese

honeysuckle (Lonicera japonica Thunb.),

and cogon grass [Imperata cylindrica (L.)

Beauv.]—that have altered southeastern forests

considerably and which continue to affect the

biology of these forests. Those interested in

learning more about these and other introduced

pathogens, insects, and plants may start with

volumes by Tainter and Baker (1996), Anon.

(1985), and Miller (2003).

Much of the research and management effort

of foresters, plant pathologists, entomologists,

and weed scientists during the 20th century

was directed to learning the bionomics of

nonnative species, trying to contain their spread,

and restoring ecosystems altered by their

presence. Unfortunately, there have been few

successes in controlling the advance of, and

the damage caused by, most introduced species;

and so the next generation of scientists and forest

land managers will face growing challenges.

In addition, forest health concerns in the South

have expanded over the last several decades

to include native and nonnative invasive insects,

pathogens, and plants; disease complexes;

urbanization; forest fragmentation; air pollutant

effects; and increased risk of wildfire. Recently

discovered nonnative insects, such as the Asian

longhorned beetle [Anoplophora glabripennis

(Motschulsky)] and the emerald ash borer

[Agrilus planipennis (Fairmaire)], as well as

the recently discovered nonnative disease sudden

oak death (Phytophthora ramorum Werres), while

not currently known to be in southeastern forests,

present a threat to our forests because they are

known to damage tree species endemic to the

Southeast. Continued novel research and the

development of new monitoring techniques offer

the best hope for restoring and maintaining the

health of southeastern forests.

In the opening years of the 21st century, as in

those of the 20th century, concern about the health

of the Nation’s forests has influenced policy at the

highest levels of the Federal Government. The

Healthy Forest Initiative, announced in August

Theodor D. Leininger

and Gregory A. Reams1

1

 Research Plant Pathologist and Project Leader, and

Mathematical Statistician and Project Leader, U.S.

Department of Agriculture Forest Service, Southern

Research Station, Stoneville, MS 38776 and Research

Triangle Park, NC 27709, respectively.
Southern Forest Science:

Past, Present, and Future

Forest Health

120

2002 by President George W. Bush, directed

Federal agencies to develop administrative and

legislative measures that will help reduce the

threat of catastrophic wildfire to America’s forests

and rangelands (Anon. 2003a). The U.S. House

of Representatives responded by passing H.R.

1904, the Healthy Forests Restoration Act of

2003. While the Administration’s intent was

to allow greater flexibility in dealing with

emergency situations, especially wildfires,

through a reduction in complex procedures and

by providing for more rapid decisionmaking,

forest preservationists were concerned that

revised rules would lead to indiscriminate

clearcutting of the national forests.

As was the case 100 years ago, foresters and

forest health professionals were thrust into the

midst of controversy and given the opportunity

to inform intelligent and rational discussion.

The Healthy Forests Restoration Act of 2003

was signed into law on December 3, 2003 at which

time it fell primarily to Federal scientists and

managers, especially within the U.S. Department

of Agriculture Forest Service (Forest Service),

to develop the means of carrying out the act’s

requirements. In addition to addressing the

reduction of “risks to communities, municipal

water supplies, and some at-risk Federal lands

from catastrophic wildfires,” the act also seeks

to “promote systematic information gathering

to address the impact of insect infestations on

forest and rangeland health” and “to improve the

capacity to detect insect and disease infestations

at an early stage, particularly with respect to

hardwood forests” (Anon. 2003b).

Title IV of the act addresses insect infestations

and specifically mentions the need to

assist land managers in the development

of treatments and strategies to improve

forest health and reduce the susceptibility

of forest ecosystems to severe infestations

of bark beetles, including Southern pine

beetles, hemlock woolly adelgids, emerald

ash borers, red oak borers, and white oak

borers on Federal lands and State and

private lands; and to disseminate the

results of such information gathering,

treatments, and strategies.

Ten of the thirteen States served by the

Southern Research Station are mentioned

in connection with epidemic outbreaks of the

southern pine beetle (Dendroctonus frontalis

Zimmermann), a subject addressed by T. Evan

Nebeker in this book, and Arkansas is cited as

having an unprecedented outbreak of the red

oak borer [Enaphalodes rufulus (Haldeman)].

Most interesting in the legislation is language

urging the development of a system that will give

forest managers early warning of catastrophic

environmental threats to forests, thereby

increasing the likelihood that such threats

can be isolated and treated before they get out

of control; and to “prevent epidemics, such as the

American chestnut blight in the first half of the

twentieth century, that could be environmentally

and economically devastating to forests” (Anon.

2003b). Clearly, social and political forces in the

United States are keenly interested in forest

health issues of stand management, wildfire

suppression, and outbreaks of native and

nonnative insects, diseases, and invasive weeds;

all of which present tremendous challenges

and opportunities to forest health professionals

in the 21st century.

The development of appropriate research and

management responses begins by asking the right

questions, so that needs can be determined based

on the most important and immediate resource

management concerns. Forest Service Research

and Development asked the right questions in the

report “Great Issues, New Solutions: A Summary

of Forest Service Research Addressing the

Four Great Issues,” which was a response to the

Healthy Forests Initiative. In the report, members

of the Forest Service Research and Development

staff in Washington, DC, enumerated the

successes and ongoing research and development

of scientists in the Agency’s six research stations,

Forest Products Laboratory, and Institute of

Tropical Forestry (Anon. 2003c). They also asked

questions that range from the more general, such

as, “How do nonnative species invasions affect

community structure, trophic interactions, and

disease dynamics?” and “How do microbial

organisms affect the environment?” to the quite

specific, such as, where changes have been nearly

irreversible, e.g., American chestnut [Castanea

dentata (Marsh.) Borkh.], “How can we reestablish

‘native’ hybrids to restore forest values?” and

“How do insects and pathogens affect fuel

dynamics and flammability?” Some questions

concern the management of ecosystems.

Examples of these are, “How do natural and

human disturbance processes and their

interactions impact and shape ecosystems?”

“How do fire, insects, and disease affect long-term

productivity and carbon dynamics of ecosystems?”

“How can we restore and maintain the health and

productivity of disturbed ecosystems?” and “What

is the potential for management intervention?”
121

Other questions relate to monitoring capabilities.

Examples of these are, “Can we develop a quick

response capability that provides essential

scientific knowledge to help managers isolate new

invasive species before they become established?”

and “What methods can be developed to monitor

and assess noxious weed impacts?” These, and a

host of other related questions, will drive much of

the work of forestry researchers and managers

at the beginning of the 21st century.

Chapters in this section of our book address

some of the more pressing issues of forest and

ecosystem restoration, nonnative invasive pests,

and native insects and diseases in ever-changing

climatological, social, and political environments.

The second chapter “Restoration of Southern

Ecosystems” by John Stanturf, Emile Gardiner,

Kenneth Outcalt, William Conner, and James

Guldin presents an overview of restoration efforts

in four ecologically varied and socially valued

southern forest types. The authors observe that

methods for restoration are more advanced for

bottomland hardwoods and longleaf pine (Pinus

palustris Mill.) forests than for deepwater swamp

and shortleaf pine (P. echinata Mill.) forests.

Bottomland hardwood restoration occurs mostly

on private land; restoration of deepwater swamps

and shortleaf pine forests occurs mostly on public

land; and both private and public landowners are

working to restore longleaf pine. Ownership has

implications for the economics of forest land

restoration. For example, current Federal

programs that provide large easement payments,

such as the Wetlands Reserve Program, are

expensive and probably justified on poor sites. On

better sites, restoration might pay for itself, with

only cost sharing needed to establish the forest.

Stanturf, Gardiner, Outcalt, Conner, and Guldin

emphasize that forests are resilient and that forest

habitats will develop whether or not we intervene.

The best we can do is to establish initial conditions

that foster development of a forest appropriate to

the site and present conditions. Attempts at recreating ancient forests are likely to fail, because

the conditions under which such forests developed

cannot be replicated.

The third chapter of this section “Understanding and Controlling Nonnative Forest Pests

in the South” by Kerry O. Britton, Donald A.

Duerr, II, and James H. Miller discusses nonnative

diseases, insects, and plants that have caused

drastic changes in southeastern forest ecosystems

and have cost a lot of money for management,

containment, and research. The authors discuss

the biological basis for the invasiveness of

nonnative pests and what can be done about these

pests. Included at the end of the discussion is a

listing of Internet Web sites that are examples of a

form of late 20th-century technology transfer that

will undoubtedly endure, and be improved upon, in

the current century.

The fourth chapter “Advances in the Control

and Management of the Southern Pine Bark

Beetles” by T. Evan Nebeker addresses recent

advances in the control and management

of native southern pine bark beetles and the

outlook for future management. Nebeker also

refers to several Web sites as examples of ways

entomologists are distributing critically needed

information about bark beetles and methods for

controlling them. One of the changes Nebeker

forecasts is that forest resource protection of the

future will be aimed more at prevention of damage

through the development and use of hazard- and

risk-rating expert systems.

The fifth chapter “The Impact and Control

of Major Southern Forest Diseases” by A. Dan

Wilson, Theodor D. Leininger, William J. Otrosina,

L. David Dwinell, and Nathan M. Schiff discusses

the ongoing work to discover novel control

methods for several hardwood and coniferous

diseases that continue to beset forests of the

Southeast. Tree diseases continue to present

challenges for pathologists and forest managers

even as we enter the second century after

the father of forest pathology, Robert Hartig,

wrote the first forest pathology textbook in 1874

(Tainter and Baker 1996). One of the findings of

the Southern Forest Resource Assessment (Wear

and Greis 2002) was that more forest land in the

eastern part of the southeastern region will be

converted to pine plantations, while new hardwood

forests will be created on former agricultural land

in the western portion of the region. Management

of these forests that lack diversity of tree species,

as well as third- and fourth-growth natural

stands, will present many challenges to forest

health researchers and forest managers. These

challenges will need to be overcome in the midst

of changing climatological and sociopolitical

environments that will mean understanding and

addressing dynamic ecological variables with

smaller budgets and fewer people.

The sixth chapter “Monitoring the

Sustainability of the Southern Forest” by Gregory

A. Reams, Neil Clark, and James Chamberlain

discusses how monitoring efforts have been

modified and implemented to specifically address

Chapter 12.

 Healthy Forests in the South
Southern Forest Science:

Past, Present, and Future

Forest Health

122

the evolving forest health concerns in the

South, which now include native and nonnative

invasive insects, pathogens, plants, plant-disease

complexes, urbanization, fragmentation, air

pollutant effects, and wildfire risk. Significant

adaptations to the Forest Service’s Forest

Inventory and Analysis (FIA) sampling design

have been made to accommodate monitoring

needs of the Forest Health Monitoring (FHM)

Program. These needs include the requirement to

provide for early detection monitoring to evaluate

status and change in forest conditions. To provide

this function, FHM detection monitoring is now

integrated with the new continuous (annual)

forest inventory design currently being

implemented by FIA.

The FIA Program has been in place since the

1930s and has reported changes in forested acres,

forest type, growth, mortality, and harvest by

State on a 6- to 10-year cycle since the program’s

inception. The current modifications to the FIA

and FHM Programs are an outgrowth of the

National Acid Precipitation Assessment Program

(NAPAP) and the National Vegetation Survey

(NVS). Both NAPAP and NVS employed FIA

field plots in their surveys of acid rain and ozone

impacts on forests. The use of FIA plots to do

forest health monitoring under NAPAP led to

the formation of FHM.

Initial FHM objectives focused on air pollution

impacts on forests. However, since the early 1990s

the program has expanded analysis and reporting

capabilities to include criteria and indicators of

sustainable forest management as identified in the

Montreal Process. Specifically, FHM addresses

conservation of biodiversity, maintenance of forest

ecosystem health, and maintenance of soil and

water resources by sampling additional indicators

of forest health on an annual subset of FIA ground

plots. The forest health indicators include crown

condition, ozone injury, lichen communities, down

woody debris, vegetation diversity and structure,

and soil condition.

Detection monitoring data are used as

an early warning system to decide whether

implementation of evaluation monitoring is

warranted to determine the extent, severity, and

causes of undesirable changes. The development

of novel and adaptive sampling techniques is also

part of the FHM Program. Risk-based sampling

is being used for early detection of sudden oak

death and emerald ash borer. Eventually, riskbased and adaptive sampling techniques will

become universal elements of any large-scale

early detection program.

LITERATURE CITED

Anon. 1985. Insects of eastern forests. Misc. Publ. 1426.

Washington, DC: U.S. Department of Agriculture, Forest

Service. 608 p.

Anon.. 2003a. Cabinet officials report progress on President

Bush’s healthy forests initiative. Release 0177.03, May 20,

2003. Washington, DC: U.S. Department of Agriculture,

U.S. Department of the Interior, and U.S. Department of

Commerce. 3 p.

Anon. 2003b. Great issues, new solutions: a summary of Forest

Service research addressing the four great issues. Draft.

Washington, DC: U.S. Department of Agriculture. 40 p.

Anon. 2003c. Healthy Forests Restoration Act of 2003. http://

thomas.loc.gov/cgi-bin/query. [Date accessed: June 19].

Miller, James H. 2003. Nonnative invasive plants of southern

forests: a field guide for identification and control. Gen.

Tech. Rep. SRS–62. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southern Research Station.

93 p.

Owen, Wayne. 2002. The history of native plant communities in

the South. In: Wear, David N.; Greis, John G., eds. Southern

forest resource assessment. Gen. Tech. Rep. SRS–53.

Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southern Research Station: 47–61. Chapter 2.

Tainter, Frank. H.; Baker, Fred A. 1996. Principles of forest

pathology. New York: John Wiley. 805 p.

Wear, David N.; Greis, John G., eds. 2002. Southern forest

resource assessment. Gen. Tech. Rep. SRS–53. Asheville,

NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 635 p.
123

Chapter 13.

Restoration

of Southern Ecosystems

John A. Stanturf, Emile S.

Gardiner, Kenneth Outcalt,

William H. Conner, and

James M. Guldin1

Abstract—Restoration of the myriad communities

of bottomland hardwood and wetland forests

and of the diverse communities of fire-dominated

pine forests is the subject of intense interest in

the Southern United States. Restoration practice

is relatively advanced for bottomland hardwoods

and longleaf pine (Pinus palustris Mill.), and less so

for swamps and shortleaf pine (P. echinata Mill.).

Most bottomland hardwood restoration is taking

place on private land, while restoration of swamps

and shortleaf pine occurs mostly on public land.

Both public and private landowners are involved

in the restoration of longleaf pine. Proper matching

of species to site is critical to successful restoration

of bottomland hardwoods. Techniques for longleaf

pine restoration include the reintroduction of

growing-season fire and the planting of longleaf

pine seedlings and understory species. Safely

reintroducing growing-season fire, however, may

require initial manipulation of other vegetation

by mechanical or chemical means to reduce

built-up fuels.

INTRODUCTION

F

orest cover has declined globally, from an

estimated 6 billion ha of “original” forest

extent (that prevailing during most of the

past 10,000 years) to the present 3.87 billion ha

(Food and Agriculture Organization of the United

Nations 2001, Krishnaswamy and Hanson 1999).

Global assessments have identified changing land

use, increasing demand for fiber, and exogenous

stresses such as global climate change and air

pollution as the factors causing loss of forest

cover or degradation of forest condition. Many

forests in the South are being subjected to similar

disturbances and stresses. Restoration of the

myriad communities of bottomland hardwood

and wetland forests and the diverse communities

of fire-dominated pine forests is the subject of

intense interest in the Southern United States,

as well as in other parts of the world (Parrotta

1992, Stanturf and Madsen 2002).

Our objective is to present an overview

of the restoration of four ecologically varied and

socially valuable U.S. forest types: bottomland

hardwoods, swamps, Coastal Plain longleaf pine

(Pinus palustris Mill.), and Interior Highland

shortleaf pine forests (P. echinata Mill.).

Restoration practice is relatively advanced for

bottomland hardwoods and longleaf pine, and

less so for swamps and shortleaf pine. Bottomland

hardwood restoration is taking place mostly on

private land. Restoration of swamps and shortleaf

pine is occurring mostly on public land, while both

public and private landowners are attempting

to restore longleaf pine.

RESTORATION PRACTICES

Bottomland Hardwood Forests

R

estoration of bottomland hardwoods occurs

mostly in the Lower Mississippi Alluvial

Valley (LMAV), predominantly in three

States: Louisiana, Mississippi, and Arkansas

(Stanturf and others 2000). The loss of bottomland

hardwood forests has been more widespread in

the LMAV than elsewhere in the United States.

Clearing for agriculture reduced forest cover, and

flood control projects drastically changed regional

and local hydrologic cycles. Deforestation and

1

 Forest Soil Scientist and Project Leader, U.S. Department

of Agriculture Forest Service, Southern Research Station,

Athens, GA 30602; Research Forester, U.S. Department

of Agriculture Forest Service, Southern Research Station,

Stoneville, MS 38776; Research Ecologist, U.S. Department

of Agriculture Forest Service, Southern Research Station,

Athens, GA 30602; Professor, Baruch Forest Science

Institute, Clemson University, Georgetown, SC 29442;

and Research Forest Ecologist and Project Leader, U.S.

Department of Agriculture Forest Service, Southern

Research Station, Hot Springs, AR 71901, respectively.
Southern Forest Science:

Past, Present, and Future

Forest Health

124

drainage resulted in a loss of critical wildlife and

fish habitat and reduced floodwater retention

(MacDonald and others 1979, Sharitz 1992, U.S.

Department of the Interior 1988).

The dominant goal of all restoration programs

in the LMAV has been to create wildlife habitat

and improve or protect the quality of surface

water (Haynes and others 1995, King and Keeland

1999, Newling 1990). Afforestation of small areas

(usually no more than 100 ha) within a matrix of

active agriculture is typical. Although we know

how to afforest many sites (Stanturf and others

1998), recent experience with the Wetlands

Reserve Program in Mississippi illustrates the

difficulty of applying this knowledge broadly

(Stanturf and others 2001).

Afforestation is a process in which something

can go wrong at any of several steps. Proper

matching of species to site is critical to successful

restoration (Baker 1977, Baker and Broadfoot

1979, Broadfoot 1976, Dicke and Toliver 1987,

Groninger and others 2000, Krinard and Johnson

1985, Stine and others 1995). Availability of

planting stock, however, probably has the greatest

influence on the assignment of species to sites.

Provenance and family within provenance may

account for differences in survival and growth of

common species (Dicke and Toliver 1987, Greene

and others 1991, Jokela and Mohn 1976, Land

1983). Few foresters in the LMAV specify seed

source constraints in purchasing agreements.

This lack of quality control, or use of uncertified

seed, could potentially reduce establishment

success, productivity, and forest health.

Bare-root seedlings were used to stock 64

percent of afforestation area to 1997, with direct

seeding applied on 29 percent of the afforestation

area (King and Keeland 1999). Descriptions of

direct seeding techniques are readily available

(Allen and others 2001). Suitable techniques

for collecting and storing seed of bottomland

hardwood species are well documented (Bonner

and others 1994).

Site preparation is used to condition the seed or

seedling bed; decrease competing or undesirable

vegetation, such as nonnative pests; reduce

herbivore habitat; improve nutrient availability;

and improve access for the planting operation

(Baker and Blackmon 1978; Kennedy 1981, 1993).

Site preparation can increase survival and improve

early growth of hardwood planting stock (Baker

and Blackmon 1978, Ezell and Catchot 1998,

Russell and others 1998). Contractors use

crews of both hand and machine planters, but

differences between the operational rates of

establishment success of the two methods are

unknown (Russell and others 1998). Observations

indicate that either method can be effective if

properly supervised (Gardiner and others 2002,

Michelak and others 2002).

Swamp Forests

Deepwater swamps, primarily baldcypresswater tupelo [Taxodium distichum (L.) Rich.-

Nyssa aquatica L.], pondcypress-swamp tupelo

[T. distichum var. nutans (Ait.) Sweet-N. sylvatica

var. biflora (Walt.) Sarg.], or Atlantic white-cedar

[Chamaecyparis thyoides (L.) B.S.P.] swamps,

are freshwater systems with standing water for

most or all of the year (Johnson 1990, Little and

Garrett 1990, Wilhite and Toliver 1990). Other

deepwater swamp types include cypress domes

and depressional swamps such as the Okefenokee

and Dismal Swamps. Large-scale commercial

logging of swamp forests did not begin until the

late 1800s (Davis 1975, Frost 1987, Little 1950).

The introduction of the pullboat, and later the

overhead-cableway skidder, enabled loggers to

penetrate deeper into swamps and increased the

amount of timber harvested. Although declining

in area (Dahl 2000), there remain about 2 million

ha of this forest type, mostly in second-growth

timber (Kennedy 1982). There is less experience

in the restoration of deepwater swamps than in

the restoration of bottomland hardwoods (Mitsch

and Gosselink 1993).

Although there has been little success in

planting tupelo (DeBell and others 1982), better

results have been obtained with Atlantic whitecedar (McCoy and others 1999, Phillips and

others 1993) and baldcypress. Planting of cypress

began in the 1950s with good success (Peters and

Holcombe 1951). Rathborne Lumber Company

planted nearly 1 million baldcypress seedlings on

cutover land in Louisiana with 80 to 95 percent

survival (Rathborne 1951). The Soil Conservation

Service, however, experienced severe herbivory,

and they recommended suspension of planting

cypress until some means of controlling nutria

(Myocastor coypus Molina) is developed (Blair

and Langlinais 1960). Nutria damage to newly

planted seedlings remains a serious problem

(Brantley and Platt 1992, Conner 1988, Myers

and others 1995), and nutria may also damage

mature trees (Hesse and others 1996).

Planting of seedlings may be necessary to

restore deepwater swamps because natural

regeneration is unreliable in such areas (Conner

1988, Conner and others 1986, Hamilton 1984,
125

Hook and others 1967, Kennedy 1982, Smith

1995). Planting 1-year-old baldcypress seedlings

at least 1 m tall and larger than 1.25 cm at the

root collar improves early survival and growth

(Faulkner and others 1986). Planting in the late

fall and winter is recommended so that seedlings

become established during periods of low water

(Mattoon 1915). Even when baldcypress is planted

in permanent standing water, its height growth

averages 20 to 30 cm/year when there are no

herbivory problems (Conner 1988, Conner and

Flynn 1989). Tree shelters generally increase the

chances of survival of planted seedlings, but they

do not prevent all herbivory (McLeod 2000).

A simple technique for planting seedlings

in standing water has been tested successfully

(Conner 1995, Conner and Flynn 1989,

Funderburk 1995, McLeod and others 1996).

This technique involves root pruning, or trimming

off the lateral roots and cutting the taproot to

approximately 20 cm. When this is done, the

planter can grasp the seedling at the root collar

and push it into the sediment until his or her hand

hits the sediment. This method has worked well in

trials with baldcypress and water tupelo, but not

as well with green ash (Fraxinus pennsylvanica

Marsh.) and swamp tupelo.

Longleaf Pine Forests

Longleaf pine was once the most prevalent

pine type in the South, dominating as much as

25 million ha (Stout and Marion 1993). Burning

of understory vegetation by Native Americans

augmented the natural understory fire regime

of longleaf forests (Abrahamson and Hartnett

1990, Christensen 1981, Robbins and Myers

1992, Ware and others 1993). Longleaf, however,

was not well adapted to the forms of disturbance

that accompanied European settlement (Frost

1993, Wahlenberg 1946). Logging, wildfires,

and conversion to other pines or urban areas

reduced longleaf pine to < 5 percent of its original

area (Kelly and Bechtold 1990, Outcalt and

Sheffield 1996).

Because of past history, an array of potential

sites for longleaf restoration is available in

various conditions (Outcalt and Sheffield 1996).

This includes an estimated 0.5 to 0.8 million ha

with intact longleaf overstory and understory

(Noss 1989). Other areas with little or no longleaf

in the overstory have understories that range from

those having most of the native species to those

that are devoid of species typical of the longleaf

ecosystem (Outcalt 2000). This range of overstory

and understory conditions exists across the

spectrum of longleaf sites, from dry sandhills to

wet savannas. Effective restoration techniques

depend on the site type and current condition

of the overstory and understory (table 13.1).

Generally, techniques include reintroducing

growing-season fire and planting longleaf pine

seedlings and understory species. Safely

reintroducing fire during the growing season,

however, may require initial manipulation of other

vegetation by mechanical or chemical means to

reduce built-up fuels.

Fire suppression has allowed understory shrubs

and hardwoods to expand significantly on many

longleaf sites. Prescribed burning during the

dormant season was introduced on public lands

and larger private holdings to reduce fuel buildup,

but often had no effect on the well-developed

midstory. Reintroducing growing-season fires

will adjust structure and relative composition,

thereby reestablishing normal function. In the

South, growing-season burning of stands with

an intact longleaf overstory should be limited to

the period from March to July, and late burning

(into September) avoided because longleaf

pine is then susceptible to fire-caused mortality

(Robbins and Myers 1992). Nevertheless,

reintroducing growing-season fires into xeric

longleaf communities that have not been burned

for a long time usually causes some mortality of

large trees from 1 to 3 years after the first burn.

The exact cause of this is unknown, but mortality

seems to be related to smoldering combustion of

the excessive litter buildup around the base of

larger stems. Several closely spaced dormant

season burns should be used to reduce litter

buildup prior to any growing-season burning.

Caution should be exercised, however, where

slopes > 15 percent are burned frequently,

because significant erosion can result when

mineral soil is exposed in such terrain.

On many sites, supplemental treatments can

accelerate restoration of red-cockaded woodpecker

(Picoides borealis Vieillot) colonies or forest

cover at the urban interface zone. Mechanical

treatments (chain saw felling, girdling, or

chipping onsite) can rid stands of midstory

hardwoods (Provencher and others 2001). Such

treatments can be followed with a prescribed

burn to stimulate grasses and forbs and control

hardwood sprouts. Midstory material left onsite

should be allowed to decay before the first

prescribed burn. Fuel is often sparse in areas

dominated by scrub oak, so these areas are often

Chapter 13.

 Restoration
Southern Forest Science:

Past, Present, and Future

Forest Health

126

difficult to burn. Mechanical treatments with a

small single-drum chopper with no offset can be

used to knock over and compress the oaks into a

ground layer that will carry a prescribed burn

after curing.

Restoration is more rapid if burning is

supplemented by use of an herbicide such as

hexazinone (applied at a rate of 2 kg/ha of active

ingredient); desired results can be obtained with

one herbicide application and one burn (Brockway

and Outcalt 2000). This treatment is effective at

topkilling midstory hardwoods with only shortterm reductions in understory grasses and forbs

on sandhills sites (Brockway and others 1998),

although cover of desirable woody species may

be reduced for a period. However, herbicide need

be applied only once; periodic prescribed burns

will maintain the understory condition.

Longleaf seedlings can be bare-root or

container, and can be planted by hand or by

machine (Barnett and McGilvray 1997, Barnett

and others 1990). Site preparation, other than that

outlined above, should be avoided to preserve the

understory. A planter with a small scalper blade

attached can boost bare-root seedling survival

if grass cover is > 60 percent (Outcalt 1995).

Acceptable survival can be obtained with container

seedlings and no site preparation other than

burning, although survival may be increased by

hexazinone application on areas with heavy scrub

oak competition.

The understory is best restored simultaneously

with replanting of longleaf seedlings to take

advantage of the reduced competition and ease

of operability. The critical factor is reestablishment

of the grass component because of its important

role as a fuel source for ecosystem maintenance.

Table 13.1—Longleaf pine restoration prescription depends upon site type and the condition of the

overstory and understory

Overstory and understory condition

Longleaf overstory, woody Other species in overstory, Former longleaf site, no

Site type midstory and understory understory intact overstory or understory

Xeric and Reduce fuel loads with dormant Chop and burn scrub oak; Remove other trees; chop

sub-xeric season burns, introduce summer remove slash pine;e

 plant and burn;g plant longleaf;

sandhills burnsa

 to invigorate grasses;b longleaf;f no or minimal site planth or direct seed wiregrass;i

consider mechanicalc or preparation; introduce roll in; plant wiregrass plugs

chemicald treatments summer burns under longleaf overstory;

introduce summer burns

Flatwoods Reduce fuel loads with dormant Reduce fuel loads, remove other Remove other trees; chop

and wet season burns, introduce summer pines; chop, reduce logging and burn; plant longleaf;

lowlands burns on short intervalsj slash; plant longleaf; introduce plant or direct seed wiregrass;

summer burns introduce summer burns

Uplands Reduce fuel loads with dormant Reduce fuel loads; remove other Remove other trees; chop

season burns, remove other overstory pine, plant longleaf; and burn; plant longleaf;

pines; introduce summer introduce summer burns plant or direct seed wiregrass;

burns;k

 consider mechanical introduce summer burns

or chemical treatmentsl

a

 Glitzenstein and others (1995).

b

 Greenberg and Simons (1999).

c

 Provencher and others (2001).

d

 Brockway and Outcalt (2000).

e

 Outcalt and Lewis (1990).

f

 Barnett and others 1990).

g

 Burns and Hebb (1972).

h

 Outcalt and others (1999).

i Hattenbach and others (1998).

j

 Waldrop and others (1987).

k

 Boyer (1990).

l

 Boyer (1991).
127

Most work to date has focused on the eastern

portion of the range and reestablishment of

wiregrass (Aristida beyrichiana Trin. & Rupr.)

(Means 1997, Outcalt and others 1999, Seamon

1998). Wiregrass also can be established by

planting plugs under an existing longleaf overstory

in the spring, in strips spaced about 1 m apart.

Fertilizer applied only to the wiregrass in the

second- or third-growing season will stimulate

growth (Outcalt and others 1999). Wiregrass also

can be directly seeded between rows of trees in

plantations (Hattenbach and others 1998). Other

native grasses can be included in seed mixes.

Pineywoods dropseed [Sporobolus junceus (P.

Beauv.) Kunth.], like wiregrass, will produce seed

following burning. In addition to selected common

species such as dwarf huckleberry [Gaylussacia

dumosa (Andrews) A. Gray.] that do not reinvade

or survive, some rare species will probably have

to be reintroduced (Glitzenstein and others 1998,

Walker 1998).

Shortleaf Pine Forests

Shortleaf pine in the Ouachita Mountains

also evolved with fire (Foti and Glenn 1991).

Fire return intervals before European settlement

were from 2 to 40 years, but today fire has been

severely suppressed in this forest type (Foti and

Glenn 1991). Throughout the 1970s and 1980s,

efforts to recover the endangered red-cockaded

woodpecker in the Ouachita Mountains had been

largely unsuccessful, despite evidence that it once

inhabited the region. Managers realized that the

decline of the bird was related to decline in

suitable habitat, and restoration of the shortleafbluestem community became a priority. Roughly

63,000 ha of the Ouachita National Forest were

allocated to restoration of pine savanna (U.S.

Department of Agriculture, Forest Service 1996).

Restoration of shortleaf pine savanna requires

several changes in management. First, sawtimber

rotation is lengthened from 70 to 80 to 120 years,

which allows longer retention of suitable cavity

trees for the woodpecker and results in larger and

higher quality pine sawtimber at harvest. Second,

the pine component is subjected to a low thinning

to reduce overstory basal area. This provides

more light and promotes herbaceous growth; a

side benefit is a lowered susceptibility to southern

pine beetle (Dendroctonus frontalis Zimmermann)

attack. Third, the hardwood midstory component,

which developed in the 60-year period of fire

exclusion, must be removed. Fourth, periodic

prescribed burns are reintroduced on a 3- to 5-

year cycle to reestablish the native prairie flora.

Rootstocks and seed for these woodland savanna

plants are still viable in the area, and no special

effort other than reintroduction of burning is

needed for their reestablishment. Finally, artificial

cavities are installed in some of the pines for

immediate use by the red-cockaded woodpecker.

DISCUSSION

D

espite the handicap of incomplete knowledge,

attempts to restore native forests abound.

Spencer (1995) drew three lessons from

efforts to create woodlands in the United

Kingdom. These accurately portray the state of

the art of restoration ecology applied to forests:

• Forests are amazingly resilient, and functioning

forest habitat will develop whether or not we

intervene, given sufficient time.

• Attempts at re-creating ancient forests are

doomed to fail because the conditions under

which they developed cannot be replicated.

• We can at best design and implement the

proper initial conditions that will foster

development of a forest appropriate to

the site and present climate.

The economics of private land restoration will

increase in importance. Current Federal programs

that provide large easement payments, such as

the Wetlands Reserve Program, are expensive

and probably justified on poor sites. On better

sites, restoration might pay its own way, with

only cost sharing needed to establish the forest.

Landowners could derive periodic income from

timber production and other nontimber products,

including ecological services such as carbon

sequestration.

Restoration forests could sequester vast

amounts of carbon. Baldcypress, for example, can

live longer than a thousand years and attain net

primary productivity values as great as 20 t/ha/

year (Conner and Buford 1998). Biofuels produced

from cottonwood (Populus spp.) or willow (Salix

spp.) would not only sequester carbon in soil

organic matter but would have the further carbonoffset benefit of replacing fossil fuels (Stanturf

and Madsen 2002).

Attention to the effects of restoration at

landscape scales is highlighting the need to

consider how restored forests will be managed,

and raises the question of the degree to which

natural disturbance regimes can be incorporated

into forest management. In the shortleaf pine

restoration program, for example, efforts are

concentrated on establishing restored conditions

over the full extent of the landscape, primarily

Chapter 13.

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Southern Forest Science:

Past, Present, and Future

Forest Health

128

for the benefit of the red-cockaded woodpecker.

But sustainability of this habitat type in the long

term requires that some portion of the landscape

should be managed in age classes of 30 years and

younger, which are not useful as nesting habitat

for the endangered woodpecker.

The forest that results from restoration or

rehabilitation may never recover to the original

state for all functions (Bradshaw 1997, Harrington

1999). We accept as restoration any endpoint

within the natural range of managed forests

where self-renewal processes operate (Stanturf

and Madsen 2002, Stanturf and others 2001). This

approach offers a broader context for restoration

on private land, and landowners with management

objectives other than preservation are able to

contribute to ecosystem restoration (Stanturf

and Madsen 2002, Stanturf and others 2001).

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Chapter 13.

 Restoration

133

Chapter 14.

Understanding and Controlling

Nonnative Forest Pests in the South

Kerry O. Britton,

Donald A. Duerr II,

and James H. Miller1

Abstract—Invasive nonnative forest pests are

multiplying and spreading in every forest type

in the Southern United States. The costs of

controlling these pests have become extremely

high, and the damage they cause to ecosystem

composition, structure, and function continues

to increase. Plants imported for potential release

for forage, crops, soil reclamation, and ornamental

purposes are not evaluated for invasiveness.

Insect pests and diseases arrive in infested nursery

stock, wood products, pallets, and dunnage,

in spite of our regulatory system, which has been

overburdened by the rapid increase in international

trade. The biological basis for the invasiveness

of nonnative pests and possible means for dealing

with them are discussed.

INTRODUCTION

N

onnative insects, pathogens, and plants

continue to flow into the United States, as

they have for the past 500 years (Committee

on the Scientific Basis for Predicting the Invasive

Potential of Nonindigenous Plants and Plant

Pests in the United States 2002). With global

trade comes a mixing of once-separated

organisms, often with harmful effects on their

new natural systems and substantial costs for

mitigation. Invasive nonnative pests pose major

challenges. We are challenged to (1) detect and

minimize entries, (2) detect critical outbreaks

and mobilize rapid responses, (3) monitor existing

invasive populations and apply integrated pest

management (IPM) programs, and (4) disseminate

information about the nature of the problem of

invasive pests and possible means of its solution.

Executive Order 13112, issued in 1999, established

the National Invasive Species Council, comprised

of the heads of eight Federal Agencies. This

Executive order defined an invasive species as

a species that is (1) nonnative (or alien) to the

ecosystem under consideration, and (2) whose

introduction causes or is likely to cause economic

or environmental harm or harm to human

health. The council finalized in 2001 a “National

Management Plan: Meeting the Invasive Species

Challenge,” which is aimed at coordinating

offensive and defensive efforts among the

Government Agencies, nongovernmental

organizations, and the public. New national

initiatives in all elements of an IPM approach to

invasive species are planned and specified, with

actual regulatory and policy changes anticipated,

as appropriations become available. This chapter

addresses the biological and social bases for the

current predicament, identifies the most damaging

invasive pests, gives recommendations for their

control, and formulates initiatives required for

the defense of our native forests.

1

 National Pathologist, U.S. Department of Agriculture

Forest Service, Forest Health Protection, Arlington, VA 22201;

Entomologist, U.S. Department of Agriculture Forest Service,

Forest Health Protection, Asheville, NC 28804; and Plant

Ecologist, U.S. Department of Agriculture Forest Service,

Southern Research Station, Auburn, AL 36849, respectively.
Southern Forest Science:

Past, Present, and Future

Forest Health

134

Economic and Ecological Effects

Invasive nonnative pests cost the United States

an estimated $137 billion per year (Pimentel

and others 2000). This figure does not include

the costs of species extinctions. Of the 958 listed

threatened and endangered species, 57 percent

are at risk primarily because of competition with

and predation by invasive nonnatives (Reichard

and White 2001). It is difficult or impossible to

accurately and objectively determine the cost

of species extinctions or of less severe damage

to species and habitats. For this reason, natural

resource losses are more difficult to estimate

than agricultural losses. Forest product industries,

although they represent only a small part of total

forest value, are easier to evaluate economically.

National losses in traditional forest products due

to nonnative invasive insects and pathogens were

estimated at $4.2 billion per year (Pimentel and

others 2000). It has been estimated that 360

nonnative insects have become established in

American forests (Liebhold and others 1995).

Data specific to southern forests are scarce,

especially for invasive nonnative weeds. Although

no comprehensive figures specific to forestry

losses due to nonnative weeds are available, the

State of Florida has compiled some impressive

statistics for invasive nonnative weeds in wetlands.

Their control costs for melaleuca (Melaleuca spp.

L.) alone are $3 to $6 million per year and for

purple loosestrife (Lythrum salicaria L.) $45

million per year. Florida spends $14.5 million

per year to control Hydrilla spp. L.C. Rich., and

still estimates losses in recreation values for just

two lakes at $10 million per year (Pimentel and

others 2000).

Since European settlement, nonnative

forest pests have changed the composition and

function of eastern forests in important ways.

For example, as early as 1864, American chestnut

[Castanea dentata (Marsh.) Borkh.] trees were

being eliminated from the Southern Appalachian

Mountains, although the cause was not

discovered until 1932. Ink disease, caused by

the nonnative pathogen Phytophthora cinnamomi

Rands, virtually eliminated American chestnut

in valleys and coves and gradually was extending

upslope when chestnut blight [Cryphonectria

parasitica (Murrill) Barr] arrived and removed

the remaining trees, which occupied drier ridges

(Crandall and others 1945, Hansen 1999). P.

cinnamomi continues to impact southern forests,

causing littleleaf disease of shortleaf pine (Pinus

echinata Mill.), root rot on Fraser fir [Abies fraseri

(Pursh) Poir.] Christmas trees, a decline syndrome

in loblolly pine (P. taeda L.), and hundreds of other

hosts. This same fungus killed 79 percent of the

flora in the forests of Western Australia (Weste

and Marks 1987) and was recently cited as causing

an oak (Quercus spp. L.) mortality epicenter in

Mexico (Tainter and others 1999).

The oak component in Kentucky, Virginia, and

North Carolina is under attack from the advancing

front of gypsy moth [Lymantria dispar (L.)].

The same forests may soon be threatened by a new

species of Phytophthora now causing sudden oak

death (Phytophthora ramorum Werres, de Cock &

Man in’t Veld) in parts of California. An outbreak

of this disease in Oregon is being eradicated, but

pathologists are conducting surveys to determine

whether other, undetected outbreaks may exist.

Beech bark disease (Neonectria galligena),

dogwood anthracnose (Discula destructiva

Redlin), and butternut canker (Sirococcus

clavigignenti-juglandacearum) have reduced

host populations as they spread through the

understory. Adelgids [Adelges piceae (Ratzeburg)]

attacking balsam fir [Abies balsamea (L.) Mill.]

are causing losses of rare and threatened species

dependent upon the special habitat associated

with the fir (Alsop and Laughlin 1991). Similar

losses are anticipated in hemlock forest types

(Tsuga spp. Carr.) as the hemlock woolly adelgid

[Adelges tsugae (Annand)] spreads south.

The threats posed by diseases and insect

pests have long been recognized by the forestry

community. In contrast, invasive nonnative forest

plants are more insidious and have received far

less attention from foresters. Although weeds

cause losses roughly equivalent to those caused

by insects and diseases in agricultural systems

(Pimentel 1993), the frequent reliance of nonnative

plants on disturbance as an entrée to invasion

has led to the expectation that such invasions,

therefore, are less significant in forests. However,

this expectation has proven to be false for two

reasons. First, a number of invasive weeds

establish successfully without disturbance.

Among them are garlic mustard [Alliaria

petiolata (Bieb.) Cavara & Grande], oriental

bittersweet (Celastrus orbiculatus Thunb.),

and melaleuca. Second, forests are subject to

frequent disturbances of various origins. Invasive

nonnative plants often proliferate after harvests,

fire, windthrow, or hurricanes, which create gaps

of disturbed habitat. The increasing occupation

of forests by nonnative plants has also been

linked to increasing anthropogenic disturbance

(Stapanian and others 1998). Such plants inhibit

regeneration of native plants and reduce forest
135

growth and yield. Invasive nonnative weeds

can alter ecosystems by changing nutrient

cycling, geomorphology and physical structure

of the site, drainage patterns and water flow,

sedimentation rates, and disturbance regimes.

They displace native flora by competition,

and thus alter wildlife habitat (D’Antonio 2001,

Reichard and White 2001).

Pathways

Many invasive forest plants were intentionally

introduced as ornamentals or forage crops (table

14.1), often as a result of Government-sponsored

plant introduction programs (Mack and Lonsdale

2001). Some of these plants are still being sold as

nursery stock. Herbaceous weeds are more likely

to have been introduced as seed contaminants or

in soil used as ballast (Reichard and White 2001).

In contrast, most nonnative insects and

pathogens were introduced unintentionally as

contaminants on nursery stock (U.S. Congress

Office of Technology Assessment 1993). The

sudden oak death pathogen probably arrived

on infected rhododendron (Rhododendron spp.)

nursery stock. Its origin is unknown. The

American strains of this pathogen cause only small

leafspots and twig blight on rhododendron and

many other hosts, but cause lethal cankers on oaks

in coastal regions surrounding the San Francisco

Bay (Rizzo and others 2002). Species killed by

the pathogen include coast live oak (Q. agrifolia

Nee), tanoak [Lithocarpus densiflorus (Hook.

& Arn.) Rehd.], and California black oak (Q.

kelloggii Newb.). Nursery sanitation practices

and fungicide applications can sometimes mask

infection, particularly in the case of Phytophthora

species, and may allow infected material to pass

inspection. Sometimes an import host is only

slightly susceptible to a disease but may harbor

the nonnative pathogen, as infected Chinese

chestnut (Castanea mollissima Blume) probably

harbored chestnut blight. The associated pathogen

is unnoticed on the resistant host, but under

particularly favorable conditions may sporulate

and spread to more susceptible native species.

Nurseries with overhead irrigation systems

often provide this ideal environment.

Another common source of nonnative insects

and pathogens has been the trade in wood

and wood products (U.S. Congress Office of

Technology Assessment 1993). In the United

States, 35 percent of all softwood consumed is

imported, and up to 70 percent of all international

cargo arrives supported by solid wood packing

material. The recent arrival of the Asian

longhorned beetle [Anoplophora glabripennis

(Motschulsky)] in solid wood packing material

has focused attention on this previously loosely

regulated pathway. In addition to established

populations in New York and Chicago, the beetles

have been intercepted in 26 warehouse locations

in 12 other States. Solid wood packing material

is usually constructed of poor-quality wood,

often from trees damaged or killed by pests.

Bark remnants increase the likelihood of pest

association, and boards with bark attached can

be hidden in middle layers of products such as

wooden spools. One study found 2,500 live insects

in 29 short log bolts used to brace granite blocks

in metal containers (Allen 2001).

The particularly invasive nature of many

nonnative forest pests first became apparent near

the close of the 19th century. Over the past 100

years, plant pathologists, entomologists, and weed

scientists have developed a broadly applicable

concept of IPM. In this chapter, we will describe a

few important nonnative forest pathogens, insect

pests, and invasive plants, and will discuss their

entry pathways, control strategies, and ecological

and environmental impacts. We will apply the

lessons learned from these examples to develop

recommendations for a more proactive IPM

approach to preventing future invasions.

Chapter 14.

 Nonnative Forest Pests in the South

Table 14.1—Examples of intentionally introduced

invasive nonnative weeds

Common name Scientific name

Melaleuca Melaleuca

Australian pine Pinus nigra Arnold

Japanese climbing fern Lygodium japonicum (Thunb.

Ex Murr.) Sw.

Old World climbing fern L. microphyllum (Car.) R. Br.

Kudzu Pueraria montana (Lour.) Merr.

Mile-a-minute weed Ipomoea cairica (L.) Sweet

Tree-of-heaven Ailanthus altissima (P. Mill.)

Swingle

Oriental bittersweet Celastrus orbiculata Thunb.

Silktree or mimosa Albizia julibrissin Durazz.

Chinaberrytree Melia azedarach L.

Winged burning bush Euonymus alata (Thunb.) Sieb.

Bush honeysuckle Lonicera spp. L.

Cogongrass Imperata cylindrica (L.) Beauv.

Chinese silvergrass Miscanthus sinensis Anderss.

Chinese privet Ligustrum sinense Lour.

Tallowtree Triadica sebifera (L.) Small

Chinese wisteria Wisteria sinensis (Sims) DC.

Japanese honeysuckle Lonicera japonica Thunb.
Southern Forest Science:

Past, Present, and Future

Forest Health

136

INVASIVE NONNATIVE FOREST PATHOGENS

N

onnative pathogens are presumably more

disruptive than native pathogens because

they have not coevolved with their new host.

Therefore, the host lacks resistance genes, unless

some generalized response to attack provides

adequate protection against the new pest.

Chestnut blight, dogwood anthracnose, and

Dutch elm disease [Ophiostoma ulmi (Buisman)

Nannf.] will be used here to provide examples

of such “unnatural” interactions.

Chestnut Blight

In 1904, H.W. Merkel, Chief Forester of the

New York Zoological Society, noticed that chestnut

trees in the Bronx were dying. At first, recent

droughts were suspected as the cause, but later

a fungus, now called Cryphonectria parasitica

(Murrill) Barr, was discovered killing the bark

and cambial layers of American chestnut. Oriental

chestnuts (Castanea spp.) were unaffected, and

asymptomatic nursery stock is believed to have

provided the initial inoculum for this epidemic.

Despite every effort to quarantine, remove, and

burn infected trees and to protect the uninfected

trees with fungicidal sprays, the fungus spread

within 40 years throughout the range of American

chestnut. Because this is a nonsystemic bark

disease, the roots of chestnut survive and produce

coppice, but the sprouts eventually become

diseased. The fungus is a weaker pathogen but

can survive on oak; e.g., live (Q. virginiana Mill.),

post (Q. stellata Wangenh.), scarlet (Q. coccinea

Munchh.), and white (Q. alba L.), as well as

oriental chestnut. Thus there is no hope of the

disease ever dying out for lack of host material

(Anagnostakis 1987, Liebhold and others 1995).

Two separate avenues of research have been

taken to reduce the impact of chestnut blight:

(1) hypovirulence and (2) resistance breeding.

Hypovirulence is a debilitating disease of the

fungus, caused by infection by hypoviruses. In

the 1950s, researchers in Italy noted that cankers

appeared to be callusing over and healing due

to hypoviruses. Italian chestnut (C. sativa Miller)

recovered and remains a viable crop today. In the

United States, unfortunately, greater diversity

exists in vegetative compatibility (v-c) groups of

the fungus than is found in Europe. Cryphonectria

parasitica strains in the United States are less

likely than European strains to fuse mycelium and

exchange the virus. Much effort has been directed

at getting the virus into the recalcitrant strains.

Recently researchers succeeded in getting

synthetic DNA coding for viruslike ribonucleic

acid particles into the DNA of uninfected strains.

It is hoped that the synthetic genes will eventually

spread through sexual reproduction into all

v-c groups, thus promoting the spread of

the hypovirulence.

Early attempts to incorporate Asian resistance

genes into American chestnut by crossbreeding

gave disappointing results. The hybrids

often resembled the Asian species rather

than the majestic American parent, because of

backcrossing to the Asian parent. The American

Chestnut Foundation (ACF’s) has selected thirdgeneration backcrosses, containing 94 percent

American chestnut genes and possessing varying

levels of resistance. Their results indicate that

some individuals have resistance genes acquired

from the American parents as well. The time and

cost required to identify resistant progeny could

be reduced greatly by the use of marker-assisted

selection for the resistance trait. The ACF hybrids

were developed mainly from three Chinese

cultivars. The ACF intention now is to broaden

their breeding program by incorporating more

Chinese sources of resistance and outcrossing to

locally adapted American parents (Hebard and

others 2000).

Dogwood Anthracnose

The cause of dogwood anthracnose is a fungus

named Discula destructiva Redlin. The details of

introduction and origin are not precisely known,

but the lack of genetic diversity in the pathogen

points to a recent introduction (Daughtrey and

others 1996). The relative resistance of Chinese

dogwood (Cornus kousa Hatch) suggests that the

fungus has Asian origins. In addition, the disease

was first detected in North America almost

simultaneously near two port cities, on opposite

coasts, shortly after trade with China was

reopened in 1975. Features of pathogen biology,

forest history, and the silvical characteristics

of the tree all help explain the severe damage

caused by this disease.

The fungus produces only asexual spores,

but these grow in great numbers in pustules with

a slimy matrix, mostly on the underside of the

leaf. They are well adapted to spread in splashing

rain. The wet period necessary for infections is

unusually long (24 to 48 hours), which partially

explains why the disease is more severe in the

mountains, at higher elevations, on north-facing

slopes, and near streams and waterfalls where

moist conditions are common. Wet periods within

2 weeks of each other were needed to maintain

epidemic development, whereas dry periods of a
137

month or more greatly reduced the infection rate

(Britton 1993). These requirements greatly slowed

the spread of the fungus as it reached the southern

edge of the Appalachians.

Eastern flowering dogwood (C. florida L.), the

main host in southern forests, is a rapid colonizer

of gaps, and its population probably expanded

greatly after the demise of chestnut and as a

consequence of logging activity in the early 20th

century. This shade-tolerant species persisted

after gap closure, surviving under as little as 2

percent ambient light in the photosynthetically

active range (Chellemi and Britton 1992). Trees

growing in these conditions had few carbohydrate

reserves and could not withstand the stress of

repeated defoliation when a susceptible population

and environmental conditions favorable for

epidemic disease development coincided.

Since it was first reported in the southern

region in 1986, anthracnose has spread into

277 counties (Anderson and others 1994; U.S.

Department of Agriculture, Forest Service 1999).

The epidemic is now spreading West more than

South or East and is generating much concern in

Michigan, Indiana, Ohio, and Missouri. Flowering

dogwood impact plots in western North Carolina,

where the climate is very favorable for the

disease, have incurred 56 percent mortality since

1991 (http://fhpr8.srs.fs.fed.us/2001Conditions/

index.html). Disease severity today is much

greater at the epidemic front than behind it, for

several reasons: (1) the dry weather experienced

recently in the South has probably reduced the

number of secondary disease cycles occurring each

year, (2) the loss of so many dogwoods growing

in microsites optimal for fungal development

reduced the inoculum load for the surviving trees,

(3) survivors are growing on sites less favorable

for fungal development, and (4) survivors may

possess some genetic resistance.

No economically feasible control measures

have been found to protect dogwood in forest

environments. A 10-point program for reducing

disease severity was developed for landscape

trees. The main goal of the program is to improve

tree vigor and thus reduce disease impact

(Bailey and Brown 1991). The 10 points are:

1. Select healthy trees to plant.

2. Purchase trees from a reputable nursery;

do not transplant trees from the wild.

3. Select good planting sites to promote rapid

foliage drying.

4. Use proper planting techniques.

5. Prune and destroy deadwood and leaves

yearly, and prune trunk sprouts in the fall.

6. Water weekly in the morning during drought;

do not wet foliage.

7. Maintain a 4- to 6-inch deep mulch around

trees; do not use dogwood chips as mulch.

8. Fertilize according to soil analysis.

9. Use proper insecticides and fungicides

where appropriate.

10. Avoid mechanical and chemical injury to trees.

Hybrids of C. florida x C. kousa resistant

to anthracnose were developed at Rutgers

University. Selections from resistant C. florida

survivors at Mt. Catoctin National Park were

propagated and tested by the University of

Tennessee and entered the market in 2002.

Dutch Elm Disease

The story of Dutch elm disease [Ophiostoma

ulmi (Buisman) Nannf.] clearly illustrates a weak

link in the defensive cordon of our quarantine

regulations. Current U.S. regulations prevent

entry only of pests that are (1) not present in

the United States; or (2) present, but of limited

distribution, and subject to an active eradication/

control program.

To be effective, inspectors must be able to find

and identify new invaders before they enter and

become established. Unfortunately, the necessary

taxonomic information did not exist in the case of

Dutch elm disease. A new invader arrived and was

mistakenly assumed to be the original Dutch elm

disease fungus, which had become widespread

and consequently not subject to regulation.

The new invader was much more aggressive

than the first Dutch elm disease species. Thus

there have been two separate epidemics of this

vascular wilt in North America, Europe, and Asia.

The original causal fungus, Ophiostoma ulmi

(Buisman) Nannf., was probably of Himalayan

origin and reached the Netherlands by way of

the Dutch East Indies (Brasier 1990). It was

introduced from there into North America

in the 1930s.

The second, visually similar species, O. novoulmi Brasier, was not discovered in the American

Midwest until after it began killing elms in

Britain that had survived the original epidemic.

The second epidemic was traced to elm logs

shipped from North America in the 1960s.

Chapter 14.

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Southern Forest Science:

Past, Present, and Future

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138

In Britain alone, O. novo-ulmi killed 30 million

elm trees. Hundreds of millions of elms (Ulmus

spp. L.) in the United States were lost to the new

fungus (Brasier 2001). Gene flow between the

two species has been demonstrated using

molecular techniques, and this gene flow

brings advantageous O. ulmi genes for

heterogeneity of v-c groups (and subsequent

protection from debilitating viruses) into the

more pathogenic O. novo-ulmi (Brasier 2001).

All North American elm species, and

particularly the historically significant street

tree U. americana L., are susceptible to Dutch

elm disease. The spores are carried from tree

to tree by Hylurgopinus rufipes (Eichhoff), a

native elm bark beetle, in the northern tier of the

United States and Canada. In the South, Scolytus

multistriatus (Marsham), the smaller European

elm bark beetle, is the more common vector. The

beetles become infested with spores as they feed

on dying elms, and when they emerge as adults

they spread the spores to healthy trees while

feeding in twig crotches. The fungus spreads

within the tree by spores transported in the xylem,

and by mycelial growth through other tissues.

Leaves on infected branches wilt, curl, turn yellow,

and die. Sometimes the tree dies within a few

weeks, its vascular tissue plugged with fungal

mycelium, tyloses, and gums. This is particularly

true in cases where the fungus has spread through

root grafts. In other cases, the tree may die one

limb at a time over a period of a year or more

(Haugen 2001). The cost of removal of dead elms

is estimated at $100 million per year (Pimentel

and others 2000). Although U. americana was not

planted as widely in the South as in the Northern

United States, it is gradually losing its place in

southern landscapes, as well as in native forests.

Control measures for Dutch elm disease are

most successful when adopted communitywide.

Rapid sanitation of dead branches and dying

trees greatly reduces populations of the beetle

vectors. Prunings must be destroyed prior to

beetle emergence. Insecticides can also be used

to reduce vector populations. Root grafts between

diseased and healthy trees should be broken with a

vibratory plow or a trenching machine. Trenching

should be done prior to the removal of diseased

trees to prevent the drawing of inoculum across

root grafts from diseased roots to the transpiring

healthy tree (Haugen 2001). Santamour and

Bentz (1995) list five varieties of Dutch elm

disease-resistant U. americana: (1) Princeton

elm, (2) American Liberty, (3) Independence,

(4) Valley Forge, and (5) New Harmony. Other

nonnative Ulmus species and some hybrids

are also resistant to Dutch elm disease.

Injection or infusion of fungicides is used as

a preventive measure only for high-value trees.

Since the treatment must be repeated every

1 to 3 years, depending on the fungicide used,

damage to the tree in creating injection ports

is also a significant factor in overall tree health.

Stipes and Fraedrich (2001) suggest that injections

rise in priority relative to other control options

when other factors, such as poor sanitation

practices and community objections to insecticidal

sprays, contribute to the development of plentiful

inoculum. Fungicide injection improves the success

of sanitation pruning and has the advantage of

localizing control chemicals within the tree, as

opposed to insecticidal sprays, which are subject

to drift and possible nontarget effects. Again there

are no economically feasible control measures

suitable for use in the forest environment.

INVASIVE NONNATIVE FOREST INSECTS

N

onnative insects have had a profound

effect on southern forests. Over 70 species

of nonnative forest insects are currently

established throughout the Southeastern United

States. Because these pests have rapid dispersal

rates and high reproductive capacities, it is

necessary to detect new ones quickly and then

apply effective eradication programs based on

IPM before they become established and cause

further damage. This portion of the present

chapter will focus on several of the more

destructive nonnative insects which have past,

present, or potential future impacts on Southern

U.S. forests.

Gypsy Moth

The gypsy moth [Lymantria dispar (L.)] is

one of the most serious pests of hardwood trees in

the Eastern United States. In most years, millions

of acres are defoliated by the gypsy moth (fig.

14.1), and the costs of damage and control run into

tens of millions of dollars annually. Useful general

information about the gypsy moth can be found

in the “Forest Insect & Disease Leaflet 162” for

gypsy moth (McManus and others 1989) and

in the book “Insects of Eastern Forests” (U.S.

Department of Agriculture, Forest Service 1985).

The gypsy moth is native to Europe and

was introduced into the United States in 1869

by a French scientist living in Boston. The first

outbreak occurred in 1889. The gypsy moth has

spread to all or parts of 17 States, mostly in the

Northeast and the Great Lakes region, as well
139

0

2

4

6

8

10

12

14

Year

Defoliation (million acres)

19401944

1949

1954

1959

1964

1969

1974

1979

1984

1989

1994

1999

2003

as to the District of Columbia. In the Southeast,

the current advancing front runs eastwest

across northern North Carolina then slants

northwest through southwestern Virginia and

eastern Kentucky.

The gypsy moth life cycle has four stages:

(1) egg, (2) larva, (3) pupa, and (4) adult (moth

stage). Only the larvae damage trees and shrubs.

Gypsy moth egg masses are most often laid on

branches and trunks of trees, but egg masses may

be found in any sheltered location. Egg masses

are buff-colored when first laid, but may bleach

out during the winter months. The hatching of

gypsy moth eggs coincides with the budding of

most hardwood trees, from early spring through

mid-May. Larvae are dispersed naturally by

the wind and artificially on cars and recreational

vehicles, firewood, household goods, and other

personal possessions. The larvae feed until early

July before pupating. Adult females do not fly.

Gypsy moth larvae prefer hardwoods, but

may feed on several hundred different species

of trees and shrubs (for a list of host plants,

see http://www.gypsymoth.ento.vt.edu/vagm/

index.html). When gypsy moth populations are

dense, the larvae feed on almost all vegetation.

In the Eastern United States, the gypsy moth’s

main ecological effect is on oaks and in oakdominated hardwood forests.

The effects of defoliation depend primarily

on the amount of foliage removed, the condition

of the tree at the time it is defoliated, the number

of consecutive defoliations, available soil moisture,

and the species of the host. If < 50 percent of

their crown is defoliated, most hardwoods will

experience only a slight reduction in radial growth.

If > 50 percent of their crown is defoliated, most

hardwoods will produce a second flush of foliage

by midsummer. Healthy trees can usually

withstand one or two consecutive defoliations

of > 50 percent. Trees that have been weakened

by previous defoliation or that have been subjected

to other stresses, such as drought, frequently die

after a single defoliation of > 50 percent.

Natural controls, including introduced insect

parasites and predators, fungal and virus diseases,

and adverse weather conditions, help control the

gypsy moth. A number of tactics have the potential

to minimize damage by gypsy moth and to contain

gypsy moth populations at levels considered

tolerable. These tactics include monitoring

gypsy moth populations, maintaining the health

and vigor of trees, discouraging gypsy moth

survival, treating with Bacillus thuringiensis

var. kurstaki, disrupting mating with pheromone

flakes containing disparlure, treating with gypsy

moth nuclear polyhedrosis virus, treating with

diflubenzuron, and mass trapping. The tactic

or combination of tactics used depends on the

condition of the site and of the tree or stand and

the level of the gypsy moth population. Tactics

suggested for homeowners, such as removing

egg masses, placing burlap bands around boles,

or spraying individually affected trees, are

usually too labor intensive for managers to

use in forest stands.

The gypsy moth infestation spreads at an

average rate of 21 km/year along its border to

the west and south. In 1999 following a successful

pilot project initiated in 1992, the U.S. Department

of Agriculture Forest Service (Forest Service),

along with State and Federal cooperators,

implemented the National Gypsy Moth Slow

the Spread (STS) project across the 1,200-mile

gypsy moth frontier from North Carolina through

Figure 14.1—Amount

of defoliation by the

European gypsy

moth 1940–2003.

Chapter 14.

 Nonnative Forest Pests in the South
Southern Forest Science:

Past, Present, and Future

Forest Health

140

northern Michigan. The goal of the STS project is

to use novel IPM strategies to reduce the rate of

gypsy moth spread into uninfested areas. The STS

project significantly decreases the new territory

invaded by the gypsy moth each year and protects

forests, forest-based industries, urban and rural

parks, and private property. Estimated spread

rates declined from 20 to 40 km/year to 5 to 14 km/

year after STS control and eradication methods

were employed in an STS project in the central

Appalachians. The average rate of gypsy moth

spread was 26.5 km/year before 1990 and 8.6 km/

year after 1990 (Sharov and Liebhold 1998). More

information on the spread of gypsy moth and the

STS project may be found on the STS Web site:

http://www.gmsts.org/operations.

Although gypsy moth has been present in

the United States for > 100 years, it is difficult

to explain and predict the extent of the changes

it causes in forest vegetation. A major concern

is the potential loss of economically significant

and ecologically dominant oak species. Most

studies of forest compositional changes after

gypsy moth defoliation indicate that less

susceptible species will dominate the forest.

Hemlock Woolly Adelgid

The hemlock woolly adelgid [Adelges tsugae

(Annand)] has been in the United States since

1924 (McClure 1994). This serious pest of

eastern hemlock [T. canadensis (L.) Carriere]

and Carolina hemlock (T. caroliniana Engelmann)

is a native of Asia. Through 2001, hemlock woolly

adelgid infestations have been found in > 150

counties in Connecticut, Delaware, Massachusetts,

Maryland, New Jersey, New York, North Carolina,

Pennsylvania, Rhode Island, Virginia, and West

Virginia. In 2001 alone, 20 additional counties were

found to have infestations. At present, hemlock

woolly adelgid cannot be controlled in the vast

majority of forest settings.

Hemlock woolly adelgid is a sucking insect

with an extremely complicated life cycle. Four

forms each complete six life stages, some of

which develop wings and migrate to feed on

spruce. Successful reproduction on spruce has

not been observed in North America (Salom

1996b). The forms most damaging to hemlock are

wingless and remain on hemlock all year round.

White cottony sacks at the base of the needles

are good evidence of hemlock woolly adelgid

infestation. These sacks resemble the tips of

cotton swabs. They are present throughout the

year, but are most prominent in early spring.

When immature nymphs and adults suck sap

from their twigs, trees lose vigor and drop needles

prematurely. If uncontrolled, the adelgid can kill

a tree in a single year. The widespread hemlock

mortality that the hemlock woolly adelgid causes

is alarming, in view of the importance of hemlock

trees to the ecosystems in which they occur.

Application of insecticides is currently

recommended for controlling hemlock woolly

adelgid in areas where this is feasible (Salom

1996b). Infested trees are drenched with botanical

oils and or soaps, or systemic insecticide

(imidacloprid) is injected into the trees and

or the soil beneath them.

Several native predators feed on the hemlock

woolly adelgid, but none of them reduces adelgid

populations enough to help the current situation.

Two nonnative predators, Pseudoscymnus tsugae

Sasaji and McClure (a ladybird beetle native to

Japan) and Laricobius nigrinus (Fender) (a beetle

native to the Pacific Northwest), hold promise

for biological control of hemlock woolly adelgid

infestations. Under certain circumstances, releases

of these predators are a feasible and effective

control option (McClure and others 2001).

Balsam Woolly Adelgid

Introduced from Central Europe around

1900, the balsam woolly adelgid [Adelges piceae

(Ratzeburg)] is considered a serious pest of forest,

seed production, landscape, and Christmas trees

(Salom 1996a). First discovered in Brunswick, ME,

in 1908, the balsam woolly adelgid was found in

the Southern Appalachian Mountains in the 1950s

and has spread to all fir stands in the region since

that time. The pest has also found its way into the

Pacific Northwest. In the Eastern United States,

the adelgid feeds on balsam fir and Fraser fir.

Very extensive stands of Fraser and balsam fir

have been killed throughout much of these species’

range in the East. Because the adelgid does not

attack Fraser fir until the trees approach maturity,

and because some mature trees escape attack long

enough to produce seeds, young Fraser fir trees

still exist in their natural range. However, by the

mid-1980s, this insect had significantly altered all

of the mature Fraser fir-red spruce (Picea rubens

Sarg.) forest type in the Southern Appalachians.

The balsam woolly adelgid life stages include

the egg, three nymphal stages, and female adults.

There are no males; females reproduce by

parthenogenesis. They are wingless, oval,

purplish-black insects about 0.8 mm in length,

and are covered with secretions of waxy threads
141

that appear as a dense white wool mass. A female

is capable of laying 200 eggs or more in a cluster

near her body. The first-instar crawlers, reddish

brown and about 0.4 mm in length, are the only

stage of the insect capable of moving and

dispersing. Once the crawler finds a suitable

feeding location, it inserts its tubelike mouth

parts into the bark of the host and remains there

for the rest of its life. The second and third instars

are about 0.5 to 0.65 mm in length, respectively,

and closely resemble the adult.

The balsam woolly adelgid generally

concentrates either on the outer portions of tree

crowns or on the main stem and large branches.

Crown infestations are characterized by abnormal

drooping of the current shoots and gouting of

the outer twigs. The crown becomes increasingly

thin, and dieback may occur. Persistent crown

infestation can kill a tree over a number of years.

Stem infestations usually cause greater damage

and mortality. Conspicuous white woolly masses

characteristic of stem attack can give the lower

bole a whitewashed appearance in the most severe

cases. The tree responds to feeding by adelgids

in an allergic manner that causes swelling of

the sapwood, gouting of the twigs, and increased

heartwood formation in the sapwood—a condition

called rotholz or redwood. This abnormal

growth of sapwood tissue inhibits water flow

within the tree.

In forest situations, silvicultural and

management techniques can be used to reduce

balsam woolly adelgid populations and damage

(Salom 1996a). Tree stress may be minimized

by thinning overstocked stands, by fertilizing

nutrient-poor sites, and by replanting or

encouraging more tolerant trees and varieties.

There are many different varieties and crosses

of Fraser fir, and some varieties are more tolerant

of balsam woolly adelgid. A hazard-rating system

was developed to aid in management decisions.

The main variables used in the system are site

elevation, soil moisture regime, percent balsam

fir by basal area, total basal area of balsam fir,

and stand age. In general, lower elevation dry sites

with > 40 percent balsam fir at an older age (45

years of age or more) are most susceptible. Trees

between 25 and 45 years of age are moderately

susceptible, and trees < 25 years old are least

susceptible. In Christmas tree plantations in which

only a few trees are infested, it should suffice

to rogue and burn those trees. Chemical control

can be used effectively on ornamental trees, seed

production trees, and Christmas trees (Day and

others 2001). Several insecticides are available for

use in spraying infested bark and foliage. When

feasible, the cutting and removal of infested trees

is effective. Cut trees must be wrapped in tarps to

ensure that adelgids do not fall off the trees as

they are being removed.

Beech Scale and Beech Bark Disease

Beech bark disease (Neonectria galligena)

is one of the more recent problems to plague

Eastern U.S. forests. Beech bark disease refers

to a complex consisting of a sap-feeding scale

insect and at least two species of Nectria fungi

(McCullough and others 2001). Beech scale

(Cryptococcus fagisuga Lind. = C. fagi Baer.)

was accidentally introduced into Nova Scotia

in 1890 on ornamental beech trees from Europe.

The scale and associated fungi have spread since

that time, and the current range in the United

States includes most of New England, northern

Pennsylvania, and northeastern West Virginia.

Localized infestations of beech scale have been

discovered in Virginia, North Carolina, Tennessee,

and Ohio (McCullough and others 2001). The

overall effect of this insect-disease complex

is the mortality of roughly 50 percent of the

beech (Fagus spp.) trees > 8 inches in diameter

(Houston and O’Brien 1983). The resulting forest

has a few residual large beech trees and stands

of many small trees, often root sprouts from

susceptible trees, which are frequently defective.

Beech scale insects are yellow, soft bodied,

and 0.5 to 1.0 mm long as adults. They feed

on American beech (F. grandifolia Ehrh.) and

European beech (F. sylvatica L.). Adult scales are

legless and wingless and have only rudimentary

antennae. Reproduction is parthenogenic. This

type of reproduction allows for rapid population

growth. Beech scale has one generation per year.

Immature scales, called crawlers, have functional

antennae and are mobile. Crawlers are spread by

wind, birds, and people moving infested wood.

When a crawler finds a suitable feeding location

on a host tree, it inserts its long, tubelike stylet

into the bark and begins to suck sap. It then molts

to the second crawler stage, which has no legs

and is immobile. These produce a white wax that

eventually covers their bodies. Thus when trees

are heavily infested with beech scale, they appear

to be covered by white wool. The small wounds

produced by the beech scale’s feeding allow the

Nectria fungi to invade the infested trees

(Houston 1994).

Crawlers that fall from trees or are washed

off by precipitation usually die. Severely cold

weather (-35 °F) that persists for a few days

Chapter 14.

 Nonnative Forest Pests in the South
Southern Forest Science:

Past, Present, and Future

Forest Health

142

may kill beech scale, but such weather conditions

probably never occur in the Southeast. A small

ladybird beetle [Chilocorus stigma (Say)] feeds

on this scale and is common throughout most

of the Eastern United States, but this predator

does not reduce scale populations enough to

control infestations.

Although the scale feeding alone weakens trees,

mortality usually does not occur until the trees

have been invaded by Nectria fungi. This invasion

typically occurs after 3 to 6 years of scale feeding.

Most large-diameter beech trees in areas where

beech bark disease becomes established are killed.

Beech is a very important source of food and

habitat for many wildlife species and areas with

large beech components may change dramatically

as a result of beech bark disease. Some trees

are partially resistant to beech bark disease,

and a very few are completely resistant. Trees

with smoother bark appear to be more resistant,

probably because the scales prefer to feed where

bark is rough (Houston 1997).

The only control is removal of the trees most

heavily infested with beech scale or Nectria fungi.

Resistant trees should be identified and retained.

After it is cut, beech often regenerates by prolific

root sprouting. This is undesirable because the

sprouts form dense thickets, have little value to

wildlife, and eventually increase susceptibility to

more beech bark disease infestations. Herbicide

control of beech root sprouts is, therefore, often

necessary. Increasing the diversity of forest stands

in which beech is present will reduce the risks and

spread rate of the disease. Care should also be

taken to avoid transporting infested firewood

or logs to uninfested areas.

Asian Longhorned Beetle

The Asian longhorned beetle [Anoplophora

glabripennis (Motschulsky)] was discovered in

New York City in 1996 and in Chicago in 1998.

Tunneling by the beetle larvae girdles tree

stems and branches, impeding water and nutrient

transport within the attacked tree. Repeated

attacks lead to dieback of the tree crown and,

eventually, death of the tree (U.S. Department

of Agriculture, Forest Service and Animal and

Plant Health Inspection Service 1999). The Asian

longhorned beetle probably traveled to the United

States inside solid wood packing material from

China. The beetle has been intercepted at ports

and found in warehouses throughout the United

States, although New York City and Chicago

remain the only two areas where infestations of

live trees have been found. Since 1996, > 7,000

trees in the two cities have been killed by the

beetle, or cut down and destroyed to stop the

beetle’s spread. Most of the trees lost were highly

valued urban trees that provided shade, wildlife

habitat, aesthetic value, and benefits for clean

water and air. The Asian longhorned beetle has

had an economic impact in the tens of millions

of dollars.

The Asian longhorned beetle is also a serious

pest in China where it kills hardwood trees. In

the United States, the beetle prefers maple species

(Acer spp.), including boxelder (A. negundo L.),

Norway (A. platanoides L.), red (A. rubrum L.),

silver (A. saccharinum L.), sugar (A. saccharum

Marsh.), and sycamore (A. pseudoplatanus L.)

maples. A complete list of host trees in the United

States has not been determined. An updated list

is available at http://www.na.fs.fed.us/spfo/alb/

index.htm. Because not all hosts are known and

because the beetle has been restricted to urban

forests thus far, it is difficult to predict its potential

effects on natural forests. It appears, however, that

Asian longhorned beetle may have the potential to

irrevocably alter many eastern forest ecosystems.

There is usually one generation of Asian

longhorned beetle per year, although the life

cycle may take as long as 2 years. Adult beetles

are usually present from May to October, but they

can be found earlier in spring or later in fall if

temperatures are warm. Adults typically stay on

the trees from which they emerge, but they may

disperse short distances to a new host to feed and

reproduce. Adult females chew oval to round egglaying sites in the bark of the tree and place a

single egg in each. Each female is capable of laying

30 to 70 eggs. These hatch in 10 to 15 days, and

the larvae tunnel under the bark and deep into

the wood where they eventually pupate. Emerging

adults create a perfectly round exit hole threeeighths inch in diameter. Adult beetles are 1 to 1.4

inches long and have striking white marks against

a jet black body. The antennae are longer than

the body and have black and white bands.

Currently the only effective means to eliminate

Asian longhorned beetle is to remove infested

trees and destroy them by chipping or burning.

To prevent further spread of the insect,

quarantines have been established to avoid the

transportation of infested trees, branches, and

wood from the area. Early detection of infestations

and rapid treatment response are crucial to

successful eradication of the beetle. Early
143

Lag phase

Exponential

spread phase

Maximum

occupation

detection is difficult, time consuming, and costly,

and to be effective, it must involve tree climbers

and surveyors in bucket trucks. Since 2000,

unattacked potential host trees have been injected

with the systemic insecticide imidacloprid as a

preventive treatment. Researchers are assessing

the biological control potential of a variety of the

beetles’ natural enemies in Asia.

INVASIVE NONNATIVE FOREST PLANTS

M

illions of acres of forest land in the Southeast

are being increasingly occupied by nonnative

invasive plants, which are also termed exotic

weeds. Their range, infestations, and damage are

continually expanding. All Federal parks and

forest lands in the Southeast have nonnative

infestations (Hamel and Shade 1985, Hester 1991).

The actual infested acreage, spread rates, and

damage estimates are still unknown, although this

information is essential for planning containment

and eradication strategies and programs (U.S.

Congress Office of Technology Assessment 1993).

The Forest Service and State partners have

initiated a cooperative survey of 42 invasive

nonnative plants within the region and another

20 species in Florida; however, it will take

several years to collect initial data (for a list,

see “Nonnative Invasive Plants of Southern

Forests” at http://www.srs.fs.usda.gov/fia/manual/

Nonnative_Invasive_Plants_of_Southern_Forests.pdf).

Invasive plants are able to outcompete native

species. They reproduce rapidly because of the

absence of predators from their native ecosystems,

and eventually form dense infestations that

exclude most other plants, except certain other

nonnatives (Randall and Marinelli 1996). Other

reasons for their invasiveness are that they are

naturally robust plants or have been made so

through plant breeding efforts; that most are

perennials with tough roots or rhizomes; that

many are still being sold as ornamentals and some

are widely planted for wildlife use and soil

stabilization; that most produce abundant seeds

or spores that are spread widely by birds,

wind, and water; and that their seeds or tubers

persist in the soil (Randall and Marinelli 1996).

It remains unclear what percentage of nonnative

plants arriving in the Southeastern United States

become invasive. One problem in determining this

is the nature of invasive plant spread, which can

be characterized by a short-to-lengthy lag phase

preceding an exponential spread phase (fig. 14.2).

In many species, e.g., kudzu, tallowtree, wisterias,

etc., the lag phase can be very protracted and can

mask eventual problems. This spread function also

explains why eradication is most possible during

the early lag phase.

Occupation and infestations by nonnative

pest plants decrease forest productivity,

threaten forest health and sustainability, and

limit biodiversity and wildlife habitat in the

Southeast (Wear and Greis 2002). Alterations

to ecosystem structure, functions, and processes

are occurring, but study of these effects has

just begun (Ehrenfeld and others 2001). Some

invasives, such as cogongrass [Imperata

cylindrica (L.) Beauv.], can alter natural fire

regimes and increase risk of wildfire occurrence

and damage (Lippincott 2000). Nonnative plant

“biological pollution” is one of the greatest threats

to biodiversity across the southern landscape,

attacking our highly valued nature preserves and

recreational lands. Adjoining croplands, home

sites, pastures, and wetlands contain invasive plant

species that will eventually affect forests. These

nonnative invaders (often called nonindigenous,

alien, or noxious weeds) include trees, shrubs,

vines, grasses, and forbs. In all there are about

70 infestation-forming, terrestrial plant species

invading forests and their edges in the temperate

parts of the Southeast. Thirty of these are

discussed briefly here to provide a general

sense of identifying characteristics, common

pathways of introduction, mechanisms of

invasiveness, ecosystem effects, and range

of current occupation. Not discussed here are

the approximately 70 tropical and subtropical

nonnative species currently invading

south Florida.

Figure14.2—Logistic spread model for invasive nonnative plants.

Chapter 14.

 Nonnative Forest Pests in the South
Southern Forest Science:

Past, Present, and Future

Forest Health

144

Invasive Nonnative Trees

Nonnative tree species hinder management

of forests, rights-of-way, and natural areas

by replacing native plants. This dramatically

alters habitat and may alter important natural

processes. Almost all of the invasive nonnative

trees are hardwoods. Some presently occur as

scattered trees, while others form dense stands.

Most spread widely by prolific seed production

and animal dispersal, while existing infestations

increase by abundant root sprouting.

Tree-of-heaven or ailanthus [Ailanthus

altissima (P. Mill.) Swingle] was introduced to

North America as an ornamental in 1784 from

Europe, although it originates in Eastern China

(Miller 1990). A short-lived species with no timber

value, ailanthus grows up to 80 feet tall with

long, pinnately compound leaves, slightly fissured

gray bark, and large terminal clusters of greenish

flowers in early summer. Flowers and other

parts of the plant have a strong odor. It is a

dioecious species and spreads by seeds from

female trees. It is shade intolerant, flood

intolerant, and allelopathic. Ailanthus establishes

after disturbance and increases by root sprouts,

often forming dense thickets that displace native

vegetation. It occurs throughout the Southeast

and is most abundant in Kentucky, Virginia,

and Tennessee.

Silktree or mimosa (Albizia julibrissin Durazz.)

was introduced as an ornamental from Asia in

1745. It is a leguminous tree, 30 to 50 feet tall.

It has feathery, pinnately compound, deciduous

leaves, smooth light brown bark, and showy pink

spring and summer blossoms, yielding abundant

dangling seedpods that persist into winter. The

seedpods float, which aids in long-distance spread

along waterways, and seeds remain viable for

many years. Infestations are spreading along

rights-of-way, fencerows, and riparian zones,

and are encroaching into adjoining forested areas

after disturbance, especially into pine plantations.

Partially shade tolerant, mimosa invades the

forest midstory and replaces native shrubs by

root sprouting. It is becoming increasingly

common along roadsides throughout the Southeast

and is most abundant in Mississippi, Alabama,

and Georgia.

Princesstree or paulownia [Paulownia

tomentosa (Thunb.) Sieb. & Zucc. ex Steud.]

was introduced from East Asia in the early 1800s.

It is grown as an ornamental and in scattered

plantations for speculative production of highvalued wood for export to Japan. It has large

heart-shaped leaves with fuzzy hairs on both sides,

and in early spring produces showy pale violet

flowers that yield clusters of pecan-shaped

capsules, each filled with thousands of tiny winged

seeds. Paulownia reproduces by abundant seeds

and root sprouts, replacing native vegetation,

including young trees that might otherwise reach

the overstory. It is shade intolerant and invades

after disturbance. This deciduous tree grows

to 60 feet tall. Because it sprouts rapidly, it often

obscures scenic vistas along roadsides. It occurs

throughout the Southeast and is presently most

abundant in central Tennessee and Virginia.

Chinaberrytree (Melia azedarach L.) is another

Asian introduction. This traditional ornamental

is commonly found around old home sites. It

grows to about 50 feet tall and is spread by birds,

which disperse its seeds. It has lacy, bipinnately

compound dark green leaves and produces pale

blue flowers in spring. The flowers yield round

yellow fruit that persist during winter. Infestations

spread by means of abundant seeding and root

sprouting along rights-of-way to adjoining land

that has been disturbed. Because it is somewhat

shade tolerant, it is increasing in the midstory

of pine plantations in parts of the South. The fruit

are poisonous to humans and livestock but have

potential use as natural pesticides. Chinaberry

is common throughout the Southeast and is most

abundant in Arkansas, Louisiana, Mississippi,

Alabama, and Georgia.

Tallowtree or popcorn tree [Triadica sebifera

(L.) Small, formerly Sapium sebiferum (L.) Roxb.]

is a shade-tolerant tree that grows to 50 feet tall.

It has light green heart-shaped leaves that turn

scarlet in the fall, long drooping flowers in spring,

and bundles of white, waxy, popcornlike seeds that

remain attached to the tree in fall and winter. The

abundant seeds are spread by birds and on water.

Tallowtree is a prolific root sprouter and forms

monospecific stands (Bruce and others 1997).

It was introduced from China to the U.S. gulf coast

in the early 1900s, and the U.S. Department of

Agriculture encouraged its use as a seed oil crop

from 1920 to 1940. Tallowtree is still being sold

and planted and is thought to be the most rapidly

invading tree species in the region. Tallowtree

seedlings are shade tolerant and yet grow rapidly

in full sun (Jones and McLeod 1990). Its waxy

seeds were traditionally used to make candles,

and it has current value as a honey plant for

beekeeping and limited pulpwood use. It forms

dense stands, and because it tolerates flooding,

tallowtree replaces bottomland hardwood

reproduction and understory plants in wetland
145

forests throughout the Coastal Plain (Jones and

Sharitz 1989). It is also spreading into upland

forests from widespread ornamental plantings.

It occurs in all the Southern States except

Oklahoma, Kentucky, and Virginia, and there

are severe infestations in coastal areas of Texas,

Louisiana, Mississippi, and Alabama.

Invasive Nonnative Shrubs

Invasive nonnative shrubs often occur with

invasive tree species and present similar problems.

Herbicide control options are similar to those for

trees, but foliar sprays are often more effectively

used against shrubs than against trees. All of the

most common invasive shrubs are abundant seed

producers, and their fruits are often consumed

and spread by birds.

Chinese privet (Ligustrum sinense Lour.) and

European privet (L. vulgare L.) are shade-tolerant

tall shrubs or small trees growing to about 30 feet

in height. These common southern ornamental

shrubs were introduced from China and Europe

in the early to mid-1800s and have already become

some of the most severely invasive species. They

form dense stands in the understory of bottomland

hardwood forests and exclude most native plants

and replacement reproduction. These privets

are also increasing in upland forests, fencerows,

rights-of-way, and special habitats throughout the

region. They drastically alter habitat and critical

wetland processes. Both species have leafy

stems with opposite leaves < 1 inch long. Chinese

privet is semievergreen, and European privet is

deciduous, but the two species are nearly identical

in all other respects. Both have showy clusters of

small white flowers in spring that yield drooping

clusters of small, spherical, dark purple berries

during fall and winter. Birds spread seed very

effectively, but privet stands also increase in

density by stem and root sprouts. Both species

occur throughout the Southeast.

Multiflora rose (Rosa multiflora Thunb. ex

Murr.) is an erect-to-arching shrubby rose growing

to about 10 feet tall and taller when it climbs into

trees. The recurved thorny stems have pinnately

compound leaves with 3 to 7 leaflets. White rose

flowers are produced in many clusters in spring,

and red rose hips, which are spread by birds,

appear in fall to winter. Sprouts and runners

that root consolidate and expand infestations.

The species was introduced from Japan and Korea

in the 1860s as an ornamental. Later, Government

programs encouraged its planting for use as living

fences for livestock containment and as wildlife

habitat. Infestations have been confined to

pastures but are now extending into forest edges

and interior forests, including wetlands. The

species occurs throughout the Southern and

Eastern United States.

Bush honeysuckles—Amur honeysuckle

[Lonicera maackii (Rupr.) Herder], Morrow’s

honeysuckle (L. morrowii Gray), tatarian

honeysuckle (L. tatarica L.), and sweet breath

of spring (L. fragrantissima Lindl. and Paxton)—

are generally deciduous multistemmed shrubs 6 to

16 feet tall with arching branches. The leaves are

distinctly opposite, usually oval to oblong in shape,

and range in length from 1 to 3 inches. Fragrant,

tubular flowers occur in pairs from May to June

and are creamy white in most species, but turn

yellow or pink to crimson in varieties of tatarian

honeysuckle. Red-to-orange berries in pairs are

abundant on plants in fall to winter, and seeds

are long lived in the soil. All were introduced

from Asia in the 1700s and 1800s as ornamentals

and wildlife plants. They are widely invading and

forming exclusive understory layers in lowland

and upland forests, replacing most native plants

and preventing regeneration of native trees. Most

alarming is the increased occupation of wetlands.

These invasive species occur everywhere in the

Southeast except Louisiana and Florida and are

most abundant in Kentucky and Virginia.

Autumn olive (Elaeagnus umbellata Thunb.)

is a deciduous, bushy shrub growing to 20 feet

tall. It has alternate leaves that are dark green

above and silvery beneath. It produces abundant

spherical red berries with silvery scales in the fall.

Introduced from China and Japan, and still widely

planted for wildlife habitat, reclamation of strip

mines, and shelterbelts, autumn olive is being

spread rapidly and widely by birds and other

animals. It is becoming a scattered understory

shrub in open forests throughout the Southeast,

to the detriment of native trees and shrubs.

Silverthorn or thorny olive (E. pungens Thunb.)

is a popular ornamental evergreen bushy shrub

with long limber shoots projecting to 20 feet when

supported by tree limbs. It has alternate leaves,

which in spring are silver and scaly on both

top and bottom and which by midsummer have

become dark green above and silvery beneath.

Thorns are widely scattered on its branches and

are subtended by brown-scaled red fruit that

appear in spring. The fruit are consumed and

widely dispersed by wildlife, which results in

scattered infestations. This widely planted

ornamental shrub was introduced from China

and Japan. A shade-tolerant species, it replaces

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native understory vegetation and prevents natural

tree regeneration. It occurs in all Southeastern

States except Texas, Oklahoma, and Arkansas.

Winged burning bush [Euonymus alata

(Thunb.) Sieb.] is a shade-tolerant, deciduous,

bushy shrub up to 12 feet tall with opposite leaves

along stems with four corky wings. Introduced

from Northeast Asia in the 1860s, it is still widely

planted as an ornamental. In fall, the leaves turn

bright red, while orange fruit appear as stemmed

pairs in leaf axils. Birds and animals are attracted

to the fruit and spread seed widely. E. alata is

increasingly invading forests, pastures, and

prairies. It forms dense stands that exclude

native plants and eventually stop native tree

regeneration. This problem is spreading in

Oklahoma, Kentucky, Tennessee, Virginia,

Georgia, North Carolina, and South Carolina.

Invasive Nonnative Vines

Nonnative vines are among the most

troublesome invaders because they often form

the densest infestations, making control efforts

difficult, especially the application of herbicide.

Many of these vines overtop even mature forests

and often form mixed infestations with nonnative

trees and shrubs.

Japanese honeysuckle (L. japonica Thunb.),

the most prevalent invasive nonnative vine, is a

shade-tolerant, climbing and trailing woody vine

with semievergreen, opposite leaves. Paired white

to yellow flowers in early summer yield blackish

berries in fall and winter. Introduced from Japan

in 1806, it is the most widespread and invasive

nonnative plant species. It occupies multiple strata

in lowland and upland forests, replaces native

vines, and alters habitat and ecosystem processes.

Japanese honeysuckle is sold as an ornamental

and has some value for erosion control. It is also

planted and cultured in wildlife food plots and

sustains deer herds during winter. It occurs

throughout the Southeast and is spread by

widely rambling vines that root at nodes,

as well as by bird-dispersed fruits.

Kudzu [Pueraria montana (Lour.) Merr.,

formerly P. lobata (Willd.) Ohwi] is a woody

leguminous vine with lobed trifoliate leaves.

It is spread by vines rooting at nodes and by

animal- and water-dispersed seeds. Introduced

as an ornamental from Japan in 1876, kudzu was

planted extensively for erosion control and forage

in Government-sponsored programs from 1920

to 1950. It forms dense infestations that exclude

native plants, halting forest productivity and

changing habitat on millions of acres of land.

Kudzu is increasingly invading riparian habitat

along rivers and streams by means of floating

seedpods. Hydrologic impacts from this mode

of spread are anticipated. Kudzu has become a

popular southern icon and provides some raw

material for folk art. The Forest Service has

initiated a biocontrol program for kudzu

(Britton and others 2002).

Oriental or Asian bittersweet (Celastrus

orbiculatus Thunb.) is an attractive but very

invasive vine with elliptic to rounded deciduous

leaves 2 to 3 inches broad and long, alternating

along a woody vine with drooping branches.

Clusters of scarlet fruit appear in fall and remain

during winter at most leaf axils. The fruits are

widely spread by birds. Oriental bittersweet was

introduced from Asia in 1736. The showy berries

are used as home decorations in winter, and these

decorations contribute to spread when discarded.

Oriental bittersweet colonizes disturbed forests

and along forest edges, spreading into interior

forests, forming expanding thickets, and

decreasing plant diversity. It is invading from

the Northeast and is not yet found in Oklahoma,

Texas, Louisiana, or Mississippi. American

bittersweet (C. scandens L.) has flowers and

fruit only in terminal clusters and does not

form extensive infestations.

Air yam (Dioscorea bulbifera L.) and Chinese

yam (D. oppositifolia L., formerly D. batatas

Dcne.) are twining and sprawling vines with heartshaped leaves and small dangling, yamlike tubers

(bulbils) at leaf axils in mid-to-late summer. These

tubers drop and form new plants. Although the

vines are deciduous, they grow rapidly and can

cover small trees in one growing season. Native

Dioscorea species do not produce “air potatoes,”

nor do they form infestations that cover trees.

Chinese yam is from Asia, and air yam is from

Africa. Both were introduced as possible food

sources in the 1800s, but are now cultured for

ornamental or medicinal use and are often spread

by unsuspecting gardeners. Once established,

these vines colonize persistently because the

prolific bulbils form new plants as they scatter

downslope. The vines expand throughout the

understory to form exclusive infestations. Their

distribution is scattered throughout the Southeast,

with air yam occurring mostly in the southern Gulf

Coastal Plain and Chinese yam more common in

the Appalachians.
147

Wintercreeper or climbing euonymus

[Euonymus fortunei (Turcz.) Hand.-Maz.] is a

trailing, climbing, or shrubby evergreen plant

with opposite, thick, dark green or green-white

variegated leaves. It is shade tolerant, spreads to

form a dense ground cover, and climbs by aerial

roots. Abundant reddish-hulled orange fruit

appear in fall and are widely spread by birds.

Introduced from Asia as an ornamental ground

cover and still widely planted, E. fortunei

continues to form dense exclusive infestations

that decrease diversity, hinder access, and alter

habitat. It occurs in Kentucky, Virginia, Tennessee,

Mississippi, Alabama, Georgia, North Carolina,

and South Carolina.

Japanese climbing fern [Lygodium japonicum

(Thunb. Ex Murr.) Sw.] is a viney deciduous fern

with lacy, finely divided leaves and green-toorange-to-black wiry stems that climb and twine

over shrubs and trees. Native to Asia and tropical

Australia, it was introduced to North America

from Japan as an ornamental and is often spread

by unsuspecting gardeners. It is one of three

species of climbing ferns in the Southeast.

The American climbing fern [L. palmatum

(Bernh.) Sw.] and Old World climbing fern [L.

microphyllum (Cav.) R. Br.], another nonnative

which grows in Florida, have once-divided leaves.

All are perennial plants that grow from creeping

rhizomes and are spread by wind-dispersed

spores. Dispersal of spores from nonnative species

results in rapid spread and widely scattered dense

infestations that cover native herbs, shrubs, and

eventually trees. L. japonicum is invading from

the South to the North and has yet to arrive in

Oklahoma, Tennessee, or Kentucky.

Chinese wisteria [Wisteria sinensis (Sims) DC.]

and Japanese wisteria [W. floribunda (Willd.) DC.]

are woody, leguminous vines with long pinnately

compound leaves and showy spring flowers.

They spread by adventitious rooting and are less

commonly dispersed by seeds. These traditional

southern porch vines were introduced from Asia

in the early 1800s. They usually spread slowly,

although more rapidly near rivers and streams.

They form dense infestations mainly around old

home sites, often in mixtures with other nonnative

plants. Both hinder reforestation and commonly

occur as scattered patches throughout the

Southeast. The native or naturalized American

wisteria [W. frutescens (L.) Poir.] does not

form dense infestations.

Nonnative Invasive Grasses

Nonnative grasses spread along highway rightsof-way and then into adjoining forest lands. Most

nonnative grasses are highly flammable and

increase fire intensity. Intense fires tend to kill

plants with which the grasses occur and thus

facilitate the spread of the grasses after wildfire

or prescribed burns. Wildland firefighters and

forest home sites are subjected to increased risks

where nonnative grasses form heavy infestations.

Repeated applications of herbicides are required

for control.

Cogongrass [Imperata cylindrica (L.)

Beauv.] is a dense, erect perennial grass. Its

wide yellowish green leaves have off-center

midveins and finely sawtoothed margins. It was

introduced from Southeast Asia in the early 1900s,

first accidentally and then intentionally for soil

stabilization and use as forage. It has been rated

as the world’s seventh worst weed (Holm and

others 1979). It spreads by windblown seeds in

early summer and by rhizome movement in

fill dirt along highways, often yielding circular

infestations. This grass is highly flammable.

It is mostly shade tolerant. Dense infestations

increasingly occupy forest openings, open forests,

and rights-of-way in the Southern Gulf Coast

States and eventually exclude most native plants.

Forest regeneration is hampered and habitat

destroyed. This process is hastened by burning

(Lippincott 2000). Cogongrass is spreading

northward from the Gulf Coast States and had

not reached North Carolina, Tennessee, Virginia,

Kentucky, Arkansas, or Oklahoma as of 2001.

Nepalese browntop [Microstegium vimineum

(Trin.) A. Camus] is an annual grass. Stems are

from 1 to 3 feet long with alternate, lanceolate

leaves to 4 inches long. It forms dense mats and

consolidates occupation and spreads by prolific

seed production in late summer. Seed remain

viable for 1 to 5 years. This shade-tolerant

weed is native to temperate and tropical Asia

and was first collected near Knoxville, TN, in

1919. It increasingly occupies creek banks, flood

plains, forest roadsides and trails, damp fields,

and swamps. It spreads into adjoining forests,

where it forms exclusive infestations and displaces

most, if not all, native understory plants. It occurs

throughout the Southeast except in Oklahoma.

Chinese silvergrass (Miscanthus sinensis

Anderss.) is a densely clumped perennial grass

with upright to arching long, slender leaves with

whitish upper midveins. It can grow to a height of

5 to 10 feet. Silvery to pinkish loose plumes appear

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in fall. Viability of the seed is unpredictable.

Native to Eastern Asia, M. sinensis has been

planted in all States for landscaping, recently

using sterile cultivars. It is spreading from

older fertile plants in all States except Arkansas,

Oklahoma, and Texas. Still widely sold and planted

as an ornamental, it is highly flammable. It forms

dense infestations along rights-of-way and in

disturbed upland forests, excluding native

vegetation and altering habitat.

Invasive Nonnative Forbs and Subshrubs

Forbs are broadleaf herbaceous plants,

while subshrubs are semiwoody. They are

usually treated with foliar herbicide sprays

or pulled by hand.

Garlic mustard [Alliaria petiolata (Bieb.)

Cavara & Grande] is an aptly named biennial

herb; all parts of the plant have a garlic odor. It

grows in small-to-extensive colonies under forest

canopies. In the first year, the plant appears as a

basal rosette of leaves that remain green during

winter. In the second year, stems emerge and

grow, becoming 2 to 4 feet tall. Leaves are broadly

arrow-point shaped with wavy margins. The

flowers form in terminal clusters, and each flower

has four white petals. Introduced originally as a

medicinal herb from Europe in the 1800s, garlic

mustard is displacing native forest understory

plants and drastically altering habitat. This species

produces prolific seed that can lie dormant in the

soil for 2 to 6 years, building large seed banks.

Germination occurs only in spring under favorable

conditions. A biocontrol program has been started

at Cornell University (Blossey and others 2001).

Garlic mustard is invading from the Northeast and

has yet to arrive in Florida, Alabama, Mississippi,

Louisiana, or Texas.

Shrubby lespedeza (Lespedeza bicolor

Turcz.) and Chinese lespedeza [L. cuneata (Dum.-

Cours.) G. Don] were both introduced from Japan.

Shrubby lespedeza is a shade-tolerant bushy

legume that grows up to 10 feet tall. It has three

leaflets and produces small purple-pink peatype

flowers with white centers. Chinese lespedeza is a

semiwoody plant up to 3 feet tall with many small,

three-leaflet leaves feathered along erect, whitish

stems. It forms tiny cream-colored flowers during

summer. Both species produce abundant singleseeded legumes, but dispersal mechanisms are

poorly understood. They have been planted

extensively for wildlife food and soil stabilization.

They are still planted for quail food, and plants

often invade surrounding forests, replacing

native plants throughout the Southeast.

Invasive Plant Control

The most effective and efficient strategy

for control is early detection and effective early

treatment of initial invaders. Any successful effort

to combat and contain invasive nonnative plants

requires an integrated vegetation management

approach (Miller 2003, Tennessee Exotic Pest

Plant Council 1996). Integrated programs

incorporate all effective control methods, which

may include (1) preventive measures, i.e., legal

controls such as quarantines, border inspections,

and embargoes; (2) biocontrol by means of natural

predators and diseases; (3) herbicide technology;

(4) prescribed fire; (5) livestock overgrazing; and

(6) mechanical and manual removal. Preventive

measures and biocontrol programs are best

organized on a regional basis. Biocontrol agents

are largely unavailable now, and although projects

to identify such agents are underway, it will take

years to develop them (Simberloff and Stilling

1996). Only through careful and precise research

and development can effective biocontrol agents

that minimize impacts on nontarget organisms

be identified.

Current treatment options for specific areas

usually involve herbicides, prescribed fire, grazing,

and mechanical or manual removal. Fire, grazing,

and mechanical cutting treatments usually control

only the aboveground plant parts, reducing their

height but suppressing the plants only temporarily.

Manual treatment usually involves grubbing or

pulling plants. This is very labor intensive and

is practical only where plants and infestations

are small. Thus manual treatment has limited

but effective application in special habitats,

such as recreational trails or nature preserves,

and as a rapid means of first-sight elimination.

Mowers, chain saws, and brush cutters remove

aboveground plant parts, while leaving roots and

rhizomes. Tree shears, root rakes, and harrows

can cut and dislodge woody and rhizomatous

plants, but leave soil bare for probable reinvasion

and possible erosion if it is not rapidly stabilized

with native plants. Nonetheless, these soildisturbing techniques can start reclamation

programs when multispecies infestations of

invasive woody plants are encountered.

Herbicide treatments often can be more

easily and effectively applied following these

other treatments. Herbicide treatments also

minimize soil disturbance and leave the soil

seed bank in place to reestablish native plants.

Carefully planned and executed herbicide

applications can specifically target nonnative

plants and minimize impacts to native plants
149

(Miller 2003) (http://www.invasive.org/weeds.cfm

and http://www.srs.fs.usda.gov/pubs/gtr/

gtr_srs062). Well-developed applicator-directed

techniques for selective control of nonnative

trees and shrubs are tree injection and girdle

treatments, basal sprays and wipes, cut-stem

applications, and foliar-directed sprays (U.S.

Department of Agriculture, Forest Service 1994).

Directed treatments of nonnative vines and forbs

usually involve foliar sprays applied with backpack

sprayers. For treating extensive inaccessible

infestations, broadcast applications of sprays and

pellets using helicopter and tractor-mounted

systems may be required. Yet even in broadcast

treatments, the use of carefully timed selective

herbicides can safeguard native plants. If the

treatment is to be safe and effective, herbicide

applicators must read, understand, and follow the

herbicide label and its prohibitions before and

during use. Continued surveillance and followup

treatments are often required to control nonnative

plant infestations.

Site Rehabilitation after Nonnative

Plant Control

The rehabilitation phase is the most essential

final part of an eradication and reclamation

program. Fast-growing native plants that will

outcompete any surviving nonnative plants must

be planted or released. Native plant seeds and

seedlings are becoming increasingly available

(http://plant-materials.nrcs.usda.gov/). If the

soil seed bank remains intact, native plant

communities may naturally reclaim many areas

after nonnative plants are controlled. Constant

surveillance, treatment of new unwanted

arrivals, and rehabilitation of current infestations

are the necessary steps in managing nonnative

plant invasions.

CONCLUSIONS

We have learned much that can help us

control invasive nonnatives in the future.

An important point is that the cost of

controlling nonnative invasives increases greatly

the longer control measures are deferred. This

suggests that the best approach might be to find

ways to improve our ability to prevent invasions or

to control invasions before they become crises.

Prevention

The entry and spread of invasive organisms

could be stopped by effective legal and policy

barriers. Such barriers could range from Federal,

State, and county laws that prohibit importation

to sanitation of equipment and vehicles before

they leave infested zones.

It is helpful to examine opportunities to

prevent intentional and unintentional introductions

separately. Most invasive nonnative plants have

been imported intentionally, in ignorance of their

potential invasiveness. Yet, plant exploration and

international seed exchange continues. Present

regulations only examine incoming plant material

for the presence of insect pests and pathogens or

contamination with listed noxious weed seed. A

system to test invasiveness of plant introductions

was developed in Australia in the 1990s and has

been helpful in addressing the problem (Mack

and others 2000). Several such systems have

been proposed (Reichard 2001).

Prevention of spread also requires examining

the Internet sales of nonnative plants and animals.

This remote means of mail order shipments of

nonnative organisms will only increase the global

problem. Retail sales within the United States

of even federally listed noxious weeds like

I. cylindrica persist with unproven sterility

of cultivars being sold. Only a rapid phasing out

of the sale of known invasive nonnative plants will

halt the spread through commercial networks.

Unintentional introductions require a different

approach. Inspection processes developed for

agricultural products have inherent weaknesses

in preventing the importation of forest pests.

International trade agreements specify that

import regulations will only address pests known

to be present on the commodity in the exporting

country, and for which a risk assessment has been

performed. Provisional regulations can be adopted

when insufficient data about the pest exist, but

the risk assessment process must be initiated.

The mitigation measures must be those that

protect our resources with the minimum

disruption of trade. Crop plants are similar the

world over, and it is generally known which pests

pose problems. When pests of natural ecosystems

are considered, the major difficulty is in knowing

which ones might prove invasive.

Biological and ecological characteristics of the

pests themselves may render them particularly

effective as nonnative invasives. Among these

high-risk characteristics are a cryptic nature,

which helps them avoid early detection, and

extended diapause or dormant periods, which

help them survive transit and quarantine. Other

characteristics can also increase the probability

of pest establishment. Asexual reproduction,

for example, reduces the minimum population

size needed to establish the pest in a new land.

The presence of related hosts, usually at least

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in the same genus as the original host, increases

the risk that a pest will be successful. Importation

in association with host material, such as nursery

stock or seed, makes establishment much more

likely. Additional factors suggested by Pimentel

and others (2000) as contributing to pest

invasiveness include a lack of natural enemies,

an ability to switch to a new host, an ability

to be an effective predator in the new ecosystem,

the availability of suitable habitats, and high

adaptability to novel conditions.

Unfortunately, the supposition that we will

know or should know in advance which pests

to study, assess as risks, and quarantine has

not been borne out by historical experience with

any introduced forest pest. Information about

the biology and distribution of known pests could

possibly be shared more effectively across

international borders. However, only a small

percentage of the insects and microbes that

inhabit forest ecosystems have even been

described to date (Campbell 2001). A different

approach may be needed to regulate importation

of articles likely to contain forest pests.

The present policy of the United States is

that imported articles are “innocent until proven

guilty.” This has also been called the dirty list

approach; it requires study of particular articles

to prove that they pose an unacceptable risk.

In contrast, the inverse policy of “when in doubt,

keep it out,” or clean list approach, requires study

of particular articles to prove they are safe,

prior to importation. This is a more conservative

approach, but for all the reasons given above,

it may be more appropriate to introduction

pathways for forest pests. Studies to develop

environmentally friendly and economically feasible

standard treatments for major import pathways

might prove a better investment than continuing

to develop regulations on a country-by-country

and pest-by-pest basis.

Detection and Monitoring

Detecting early entry is a main defense against

unintentionally introduced harmful organisms.

Improved detection technology is needed to reduce

risk, as the sheer volume of international trade

has overwhelmed the present regulatory system.

Advances in molecular technology, such as realtime microarrays, which can test for the presence

of up to 30,000 organisms in 15 minutes, need to

be adapted for implementation on a broad scale.

The expense of installing such systems at all ports

of entry may seem exorbitant today because this

technology is new. But as this technology becomes

more widely used, its application to this critical

interface may become economically feasible.

Again, such technology is only effective against

known pests. Monitoring is the basis for effective

control and containment programs, both for

targeting efforts where the organisms are

located and for judging the effectiveness of

control measures.

Control, Containment, or Management

Early detection can make it possible to

eradicate invasive pests in specific circumstances.

If eradication efforts prove ineffective, the next

control efforts should be an attempt to provide

containment; i.e., to stop the spread. Containment

efforts can protect adjoining forests, counties, and

States. At present, individual landowners must

defend their properties through their own control

activities. Sometimes interagency cooperation

could be useful. An example of this is the

interagency weed team concept U.S. Department

of Agriculture, Animal and Plant Health

Inspection Service developed to promote prompt

eradication across land ownerships. Control

methods include cultural methods, pesticide

applications, sanitation, physical and mechanical

control, and biological control. When invasive

organisms cannot be completely controlled or

eradicated, then cost:benefit or similar analyses

are used to choose which infestations should be

managed to minimize ecological degradation,

human hazards, and economic loss.

Restoration

Unless affected forest ecosystems can be

made more resistant, they will probably be

reinvaded. It may be impossible to restore an

affected ecosystem to its prior condition because

of the residual influence of the pest infestation

and because the ecosystem lacks resiliency. At

present, it appears feasible only to establish

plant components that are resistant to nonnative

invasive organisms and leave it to natural

processes, such as plant succession, to complete

the process.

Research

The current situation with nonnative invasive

organisms shows clearly that inadequate research

has been applied and applied too late. The recent

discovery that interspecific hybridization can

occur when nonnative pathogens or nonnative

and native pathogens meet (Spiers and Hopcroft

1994), highlights the urgency of further research.
151

Sometimes such interactions can result in new

host ranges (Brasier and others 1999, Newcomb

and others 2000) or increased aggressiveness

(Brasier 2001). Only through research and

technology development for each of the key

elements of IPM and successful implementation

of proven strategies may current invasions be

halted and future invasions be prevented. Because

our resources are limited, and the supply of

invasive pests is virtually unlimited, landscapelevel analyses should be used to learn which

ecosystems are most at risk and to prioritize

control efforts. Also, methods for screening plant

introductions must be developed (Committee on

the Scientific Basis for Predicting the Invasive

Potential of Nonindigenous Plants and Plant

Pests in the United States 2002).

Education and Extension

Informed individuals are needed to combat

the invasive nonnative problem. Much of the

problem from invasive organisms is perpetuated

and exacerbated by an unaware and poorly

informed populace. Our Federal Government was

designed to react slowly to broad swells of concern

raised by the constituency to the attention of its

leaders. Managers can only react when they

perceive the threat and have the resources, and

the citizen consumer will stop spreading nonnative

organisms when they are made aware of the

dangers. Public education programs might be

more successful if we inform the traveling public,

in advance of their foreign travel, of the threat to

our natural resources from smuggling forbidden

products. Once they have made their purchases

and packed them away in their suitcases, the

option to ignore this issue is much more tempting.

Similarly, a proactive “plant natives”

program (http://plant-materials.nrcs.usda.gov)

might be easier to promote than the negative

message “Don’t buy nonnative pest plants.”

Beneficial characteristics of native plants, such as

better adaptation to local climate, less irrigation

requirements, and the joys of restoring natural

ecosystems in your own backyard should be

stressed in homeowner education programs.

In fact, many Government land management

agencies could set a good example by making

improvements in their own landscape designs

in this regard. The problem of fighting invasive

nonnative pests seems overwhelming, but the

war must be won one battle at a time.

ACKNOWLEDGMENTS

T

he authors gratefully acknowledge the

editorial reviews provided by Johnny

Randall, Steve Oak, and Bill McDonald.

We also appreciate the assistance of Erwin

Chambliss and Sherry Trickel, who helped

prepare the manuscript.

RELEVANT WEB SITES

Asian Longhorned Beetle

h

ttp://www.na.fs.fed.us/spfo/alb/index.htm

http://www.aphis.usda.gov/lpa/issues/alb/

alb.htm

http://www.uvm.edu/albeetle/

Balsam Woolly Adelgid

http://fhpr8.srs.fs.fed.us/idotis/insects/bwa.html

http://www.ext.vt.edu/departments/entomology/

factsheets/balwoade.html

http://fhpr8.srs.fs.fed.us/hosf/bwa.htm

Beech Bark Disease

http://www.na.fs.fed.us/spfo/pubs/fidls/beechbark/

fidl-beech.htm

http://www.invasive.org/symposium/houston.html

Chestnut Blight

www.ppws.vt.edu/griffin/accf.html

http://www.apsnet.org/online/feature/chestnut

http://www.forestpests.org/southern/Diseases/

chsntblt.htm

http://www.forestpests.org/southern/

http://www.srs.fs.fed.us/pubs/rpc/1999-03/

rpc_99mar_33.htm

Dogwood Anthracnose

http://www.na.fs.fed.us/spfo/pubs/howtos/

ht_dogwd/ht_dog.htm

http://fhpr8.srs.fs.fed.us/pubs.html

Dutch Elm Disease

http://www.na.fs.fed.us/spfo/pubs/howtos/ht_ded/

ht_ded.htm

http://www.fs.fed.us/na/morgantown/fhp/palerts/

ded/elm.htm

http://www.ext.nodak.edu/extnews/askext/treeshr/

1423.htm

Chapter 14.

 Nonnative Forest Pests in the South
Southern Forest Science:

Past, Present, and Future

Forest Health

152

Nonnative Plants

http://www.se-eppc.org/

http://www.aphis.usda.gov/ppq/weeds/

(Federal Noxious Weed Program)

http://www.nrcs.usda.gov/technical/invasive.html

(Natural Resources Conservation Service’s Web

sites related to invasive plants)

http://tncweeds.ucdavis.edu/handbook.html

(The Nature Conservancy’s Weed Methods

Control Handbook)

General Nonnative Forest Species Information

http://www.pestalert.org/

http://spfnic.fs.fed.us/exfor/

http://www.forestryimages.org/ (for forest

health images)

http://www.ceris.purdue.edu/napis/ (National

Agricultural Pest Information System Web site)

http://www.invasivespecies.gov/

http://www.invasive.org (photos of invasive

nonnative species)

General Web Site

http://www.issg.org/database/welcome/

(Global Invasive Species Database)

Gypsy Moth

http://na.fs.fed.us/wv/gmdigest/

http://www.gmsts.org/operations (Slow-the-Spread

Web site)

http://www.gypsymoth.ento.vt.edu/vagm/

index.html

http://www.fs.fed.us/ne/morgantown/4557/gmoth/

Hemlock Woolly Adelgid

http://www.fs.fed.us/na/morgantown/fhp/hwa/

hwasite.html

http://www.ento.vt.edu/~sharov/hwa/

Sources of Native Plants for Reclamation

http://www.plant-materials.nrcs.usda.gov/

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155

Chapter 15.

Advances in the Control and Management of the

Southern Pine Bark Beetles

T. Evan Nebeker1

Abstract—Management of members of the

southern pine bark beetle guild, which consists

of five species, is a continually evolving process.

A number of management strategies and tactics

have remained fairly constant over time as new

ones are being added. These basic practices

include doing nothing, direct control, and

indirect control. This chapter focuses primarily

on the latter two. Emphasis is given to recent

and possible future management strategies

that may become part of our overall programs.

The World Wide Web will play a key role

in the distribution of information about the

management of the southern pine bark beetles.

INTRODUCTION

F

ive species make up the guild of insects

known as the southern pine bark beetles.

They include the southern pine beetle

(SPB) (Dendroctonus frontalis Zimmermann),

black turpentine beetle (BTB) [D. terebrans

(Olivier)], small southern pine engraver

(fourspined engraver) [Ips avulsus (Eichhoff)],

fivespined engraver [I. grandicollis (Eichhoff)],

and the sixspined engraver [I. calligraphus

(Germar)] (fig. 15.1). The SPB was responsible,

in presettlement forests, for periodic

perturbations that maintained uneven-aged

forests and a diversity of plant species.

These outbreaks were beneficial events in

normally functioning southern pine ecosystems.

However, the SPB is now viewed as a pest

because an economic value is placed on pine and

because intensive management of pine forests

has caused beetle populations to interfere

with efforts to achieve management

objectives (Nebeker 2003).

Because of its history, aggressive behavior,

and reproductive potential, SPB causes more

concern than the other bark beetles of the

Southeastern United States. Although Ips spp.

have been associated with tree mortality, they

are generally considered a less-aggressive species.

Ips prefer host material that is stressed due to a

moisture deficit, slash from harvesting operations,

or windthrown material. It is essential to recognize

that not just one species kills our pines. However,

during periods of drought, as in 1999 and 2000,

Ips beetles attacked and killed considerable areas

of pine. These events increased public awareness

of the impact Ips can have. During that same

period, SPB populations were low across the

region, especially west of the Mississippi River,

where they were at record lows with zero

or near zero attacks reported. The reason for

this apparent anomaly is unknown. One could

hypothesize that SPB populations were so low

because Ips populations displaced them during

tree colonization. Another possibility is that the

drought altered suitable habitat for SPB

population development by limiting or changing

resource availability. The question as to why

the SPB population has been at such a low

level during this period remains unanswered

at this point. Further efforts are needed to

understand the dynamics of insect biology

during suboutbreak periods.

SURVEY AND DETECTION

F

oresters and entomologists have long relied

on ground observations, aerial surveys, and

aerial photography to locate southern pine

bark beetle infestations. Some progress has

been made in this area over the past decade. For

example, SPB spots can now be detected remotely

(Carter and others 1998). Carter and others (1998)

indicate that individual trees with foliage ranging

from yellow to brown and classified as heavily

damaged by the SPB were easily located in 675-

and 698-nm reflectance images. Statistically, mild

chlorosis in recently infested pines was detected

by a normalized difference vegetation index

(NDVI) derived from 840- and 698-nm imagery.

However, this was not easily resolved visually

in the NDVI images. Detection of infestations 1

 Professor, Mississippi State University, Department of

Entomology and Plant Pathology, Mississippi State, MS 39762.
Southern Forest Science:

Past, Present, and Future

Forest Health

156

now depends entirely on the capability to detect

small decreases in leaf chlorophyll content. Thus,

it is expected that the increased reflectance near

700 nm that is characteristic of early, damageinduced chlorosis would be resolved more easily in

pine plantations, which are even aged and have low

species diversity. Interest in these methods will

increase as technology improves and satellites with

high-image resolution enter commercial service.

Global positioning systems (GPS) have

increased the efficiency with which SPB spots

can be located on the ground. Capturing the

GPS locations of spots during aerial surveys

has made it easier for ground crews to locate

and evaluate infestations. The use of GPS also

helps workers determine whether they are

observing new infestations or infestations that

were identified previously. This is helpful when one

is trying to determine the total number of spots

detected during the year.

The use of aerial videography is a relatively

new technology. Current uses include aerial

surveys to detect SPB spots and the development

of hazard ratings for the SPB. Matthews (1998)

states that aerial videography at 1,000 feet

aboveground level (AGL) proved to be adequate

for SPB hazard rating. Because of the resolution

limits of video, missions must be flown at about

1,000 feet AGL if individual trees in dense forests

are to be detected. There is an added convenience

in that the video can be analyzed in an office or

laboratory; traditional spotters located spots on

sketch maps while flying 500 to 1,000 feet AGL.

Oliveria observed that electronic sketchmapping has been developed to assist in plotting

the locations of infestations during aerial surveys.2

Selected backdrops (maps or aerial photos) of the

survey area can be loaded into a laptop computer.

The computer is linked to an onboard GPS system

and a touch-sensitive screen. During the survey

flight, the computer uses the GPS to display the

proper backdrop while indicating the plane’s

location relative to the ground. The spotter plots

observed infestations by touching their locations

on the display screen. The data are downloaded

into a Geographic Information System (GIS)

Program, and maps with spot coordinates

are produced.

MANAGEMENT

I

ntegrated pest management (IPM), integrated

forest pest management (IFPM), forest health

protection (FHP), forest health (FH), and

forest resource protection (FRP) have slightly

different philosophies, but they all have the goal

of protecting and sustaining forest resources

(Nebeker 2003). Ecosystem management also

has much to offer, but sometimes fails to include

consideration of pest problems (Boyce and Haney

1997). Continuing changes in our society and

individual views of how forest resources are to be

utilized or not utilized directly impact management

options. For example, some view certain forest

conditions as threatening or unhealthy, while

others see the same conditions as healthy or

just the natural course of events. The potential

for forest fire can be seen in this way. These

differing points of view are based on individual

Figure 15.1—Diagram of adults, gallery patterns, and attack sites

of the southern pine bark beetle guild (Ips vulsus, I. grandicollis,

I. calligraphus, Dendroctonus frontalis, and D. terebrans). Painting

by Richard Kleifoth in 1964, Southern Forest Research Institute,

Jasper, TX; photo by Dr. Ronald Billings in 1981, Texas Forest

Service, Lufkin, TX. 2

 Personal communication. 2001. Forrest Oliveria, Field Office

Representative, Forest Health Protection, 2500 Shreveport

Highway, Pineville, LA 71360.
157Chapter 15. Southern Pine Bark Beetles

or organizational agendas (Allen 1994, Boyce and

Haney 1997). Reconciling different points of view

is one of the most difficult tasks we face in the

protection of our natural resources.

The Expanded Southern Pine Beetle Research

and Application Program and the IFPM Program

were administered by the U.S. Department of

Agriculture Forest Service (Forest Service)

out of Pineville, LA, during the 1970s and 1980s.

These programs provided an opportunity to gain

a great deal of new information concerning the

SPB, as well as for Ips and BTB. The technology

transfer efforts associated with these programs

provided a structure for getting pest management

information into the hands of users as quickly as

possible. Efforts such as these have shown that

communication and distribution of information

are critical for control and management purposes.

Recently an extremely useful tool for the

management of bark beetles has been evolving on

the World Wide Web (WWW). Financial resources

have become a limiting factor in providing printed

material for distribution, and the Web has

developed into an outstanding addition to that end.

The Web site (http://whizlab.isis.vt.edu/servlet/sf/

spbicc/) of the Southern Pine Beetle Internet

Control Center (SPBICC) has become a source

for SPB information, control strategies, research,

and other ongoing activities. This site also

supports communication among persons whose

work involves southern pine bark beetles. For

example, CONTACT _Con-49F8B1C38C Steve

Clark (U.S. Department of Agriculture Forest

Service, Lufkin, TX) has summarized an IPM

Program for the SPB that can be accessed on the

SPBICC at http://whizlab.isis.vt.edu/servlet/sf/

spbicc/page.html?name=spb_IPM. This program

draws together currently available approaches and

new investigations. Appropriate links are included

to provide additional information about the various

control and management options. Information

about SPB activity is posted on the SPBICC

site as it becomes available. Another site,

http://bugwood.org/, contains valuable information

about bark beetles and related insects. It also

presents a wealth of related information about

FH and FHP issues. One can also refer to

numerous Web sites at universities, follow the

appropriate links, and find needed information.

An example of a university site having links to

useful sites is http://msstate.edu/~nebekers/.

The WWW has become an extremely useful tool

for communication and technology transfer. With

such information, informed decisions can be made

and appropriate strategies can be followed.

We have, for a number of years, recognized

various management strategies and tactics that

are available when dealing with bark beetles.

One option is to do nothing. If we take this

approach, we can expect history to be repeated:

we can expect periodic outbreaks as a result of

population fluctuations, and we can expect that the

amount of pine mortality in our forests will reflect

past trends. However, with increases in acreage of

host type, we might predict proportional increases

in bark beetle activity and tree mortality.

Prevention is another management strategy

we are beginning to understand. To prevent losses

to southern pine bark beetles, we must follow a

few guiding principles (Nebeker and Hedden

1984). These principles include (1) matching the

tree species to the right site—trees planted on

the wrong sites seldom have the vigor necessary

to deter or withstand attack; (2) controlling stand

density—if a stand’s basal area exceeds the site

index, then the stand should be thinned to the

appropriate level; (3) promptly salvaging all

lightning-struck, logging-damaged, diseased, and

high-risk trees, and harvesting overmature trees

when pest activity is low; (4) planting trees only

in their natural range—planting pines outside

their range and offsite causes additional stress

that increases their susceptibility to attack;

(5) minimizing site and stand disturbances—

exercising care in use of heavy equipment, road

layout, culvert location, and other construction

projects since changes in drainage result in tree

stress; and (6) harvesting all mature trees at,

or shortly after, rotation age. The use of good

silvicultural practices reduces the likelihood of

insect attack. Good silviculture can reduce losses

from SPB (Belanger and Malac 1980).

Hazard rating and thinning have tremendous

practical value but have not been fully utilized.

Hazard-rating systems have been developed for

most subregions of the South (Mason and others

1985). They identify the combinations of site and

stand conditions commonly associated with SPB

infestations. They also identify the conditions

under which SPB is most likely to occur and

where the greatest amount of damage would be

expected. Hazard ratings do not predict when,

or if, an attack will occur, but they do provide

information that managers should find useful in

identifying and ranking locations or stands that

warrant consideration for increased surveillance,

preventive treatment, accelerated suppression

action, or postdamage appraisal (Hicks and

others 1987). Most hazard-rating systems include

variables that can be altered silviculturally.
Southern Forest Science:

Past, Present, and Future

Forest Health

158

High-hazard stands can be converted to mediumhazard or low-hazard stands through silvicultural

treatments that alter parameters such as stand

density, basal area, or radial growth.

Thinning, like hazard rating, has often been

overlooked as a method of reducing the amount

of suitable habitat for the SPB during periods

of low populations. Thinning has the potential of

affecting the overall population dynamics of the

SPB when applied over the landscape. Numerous

studies have indicated that thinning is useful in

reducing the susceptibility and suitability of stands

to SPB attack (Brown and others 1987; Nebeker

and Hedden 1984; Nebeker and Hodges 1983,

1985; Nebeker and others 1985). Traugott

(2000) indicated that it is important to thin at

the appropriate time for the following reasons:

(1) to retain high-quality trees, (2) to receive

an intermediate income, (3) to enhance wildlife

habitat, and (4) to maintain the health and vigor

of the stand and, thus, reduce the severity of

losses caused by southern pine bark beetles.

In 2001, the Forest Service allocated funds

to cooperating State agencies for southern pine

bark beetle prevention work. Prior to this, funds

had been allocated only for suppression. The move

to initiate prevention efforts came as a result of

Forest Service efforts to develop nationwide risk

maps and to utilize these maps in setting priorities

for addressing problems associated with changing

FH conditions. FHP (Forest Service) strives

to reduce impacts of insects and diseases by

implementing pest suppression and prevention

projects on national forests and on other Federal,

State, and tribal lands. SPB risk can be reduced

by early detection and rapid control of spots,

which reduces additional mortality caused by

spot growth. Thinning helps maintain vigorous,

healthy stands resulting in a reduction of habitat

for attack and spot growth. It is hoped that

practitioners of FRP will welcome this movement

toward prevention rather than relying only on

suppression strategies and tactics.

Under circumstances in which prevention

is not the management strategy of choice, there

are other options. They include both direct and

indirect methods of control and management that

are available or evolving. Direct control measures

result in immediate mortality to the bark beetle

population. There are four basic direct control

tactics: (1) salvage—infested trees and an

appropriate buffer strip (uninfested trees) are

sold, cut, and removed; (2) cut and leave—infested

trees are felled toward the center of the spot to

allow for maximum exposure of the infested

portion of the bole to the sun; (3) cut, pile, and

burn—infested trees are felled, pushed into a

pile, and burned; and (4) cut and spray—trees

are felled, and their boles are sprayed with an

approved insecticide. It appears, however, that

it may not be possible to use insecticides to control

pine bark beetles in the future. Only lindane

and chlorpyrifos are now registered for use

in forest operations. Lindane is registered but

is not presently available with a label for forestry

use. Existing supplies of lindane are disappearing,

or have disappeared, and the product will be

discontinued within the next few years. However,

the manufacturer of a chlorpyrifos-based

compound has consented to maintain a forestry

registration and is reregistering its product.

The manufacturer will not initiate production

of the forestry-labeled product until they can

determine that there is a demand for it. Also,

chlorpyrifos is now a restricted-use pesticide

and can be purchased and applied only by

certified applicators or persons under their

supervision. Other compounds, such as bifenthrin,

are being studied as possible alternatives. Direct

control tactics other than insecticides will be

recommended when immediate mortality to the

bark beetle population is the goal. Cut, pile, and

burn methods will have limited use because of

their cost and the problems associated with smoke.

New approaches to managing bark beetles

are always being investigated. For example,

verbenone, an antiaggregation compound,

has been registered in North Carolina, South

Carolina, Mississippi, and Georgia and can be used

to suppress SPB. Specialized training is necessary

to ensure that the product is used correctly.

A Web site, http://everest.ento.vt.edu/~salom/

Workshop/workshop.html, has been established for

those interested in following this effort. Other

strategies and tactics are also being investigated

to suppress bark beetle populations by the use of

various compounds that have been found to repel

or attract bark beetles, but have not yet been

registered for use.

BIOLOGICAL CONTROL

C

onsideration of biological control in relation

to the southern pine bark beetles has largely

been ignored, especially in relation to intensive

pine plantation management systems. Pine trees

grown in a monoculture usually create a forest that

has less plant and animal diversity than a natural

pine forest. In such settings plant diversity is low,

and nectar sources for the parasites of bark

beetles are limited. Hence, the community
159

of SPB natural enemies is potentially reduced

in pine plantations and is therefore less likely

to be effective against SPB populations in such

settings. In addition, direct control techniques

recommended for controlling bark beetles are

aimed at killing or disrupting the colonization

process, and these techniques also damage

natural enemy communities.

Research has discovered that supplemental

feeding of SPB parasitoids increases their egg

production and longevity (Stephen and Browne

1999). This suggests that providing food for

parasitoids can increase parasitism of SPB.

A new product has been developed for application

to boles and crowns of pines infested with SPB

(Stephen and Browne 2000). The use of this new

product should conserve and promote parasitoid

populations and increase their effectiveness.

It is important to maintain communities

of natural enemies. Simple things, such as not

cutting trees vacated (used and abandoned) by

SPB when implementing direct control tactics

is a good strategy. Many of the natural enemies

do not complete their life cycle until after the SPB

has vacated the tree. Vacated trees also provide

nesting habitat for woodpeckers that prey on

bark beetles. Our society has emphasized and will

continue to emphasize the need for protecting the

environment and the need for increasing species

diversity whenever possible. Hence, there is a

need to expand our efforts in the area of biological

control, concentrating on methods that increase

biodiversity without harming the environment.

It may be possible in the future to plant flowers

in or near pine stands to provide nectar that will

increase the life span of adult parasites associated

with the southern pine bark beetle guild.

As we learn more about the nutritional

requirements of the natural enemies of SPB, we

must also understand their population dynamics.

Progress has been made in this area. For example,

it has been hypothesized (Turchin and others 1999)

that SPB outbreaks are controlled by a delayed

density-dependent response from natural enemies.

Augmenting natural populations of predators,

parasitoids, and competitors may accelerate the

decline of SPB epidemics. In addition, massrearing techniques are being developed for one of

the key predators of the SPB, the checkered clerid

beetle [Thanasimus dubius (F.)].3 Releasing a

mass-reared predator would be another option

in attempting to manage bark beetle populations.

Recently, new mortality agents have been

discovered in association with the SPB. Sikorowski

and others (1996) were the first to discover and

describe virus and viruslike particles in SPB

adults from Mississippi and Georgia. It is believed

that this is the first record of viruses associated

with SPB and Dendroctonus (Coleoptera:

Scolytidae) in general. Sikorowski and others

(1996) hypothesize that viruses associated with

SPB may be an important means of naturally

controlling SPB populations and useful in

explaining population cycles. Future research

will examine this hypothesis.

CONCLUSIONS

I

t is anticipated that there will be major

advances in survey and detection in the

future. These advances will involve the use

of remotely sensed data obtained from satellites

and various other platforms. High-resolution

imaging systems are in place or are planned,

and accompanying techniques to identify key

features on the landscape, such as SPB spots,

will become another part of our detection system.

Processing imagery of large landscapes will

become automated and increase our efficiency

in identifying the boundaries of infestations.

FRP of the future will be aimed more and

more at prevention. Initial steps have already

been taken through the development of hazardand risk-rating systems. These systems identify

areas that are likely to be attacked by bark

beetles. This information then becomes part

of the decisionmaking process by identifying the

areas that should be treated first to reduce the

hazard. Hazard-rating information can then be

used in connection with other criteria specified in

a forest management plan to make a final decision.

Hazard-rating systems provide various options

for reducing hazard through silvicultural means

and become part of a prevention management

program. Various decision-support systems that

can help us deal with southern pine bark beetles

can be accessed through the SPBICC.

We may soon be unable to use any insecticides

in our forests. At present, there is effectively only

one insecticide labeled for forest uses, and there

are no new insecticides on the horizon. Hence

we will be dependent on the other direct tactics,

such as salvage or cut-and-leave operations,

when trying to suppress southern pine bark

beetle populations. The practicality of salvage

3

 Personal communication. 2002. John D. Reeve, Assistant

Professor, Department of Zoology, Southern Illinois University,

Carbondale, IL 62901–6501.

Chapter 15.

Southern Pine Bark Beetles
Southern Forest Science:

Past, Present, and Future

Forest Health

160

and cut-and-leave tactics is limited by the difficulty

or impossibility of finding markets for salvaged

trees. Because of these limitations, more and more

emphasis will be placed on prevention tactics.

There is hope that new approaches may prove

useful. These include the use of antiaggregation

compounds that disrupt the bark beetle

colonization process. The WWW will be a useful

tool for distributing information concerning

this approach and other developments in the

management of bark beetle populations. New

paradigms will influence our decisionmaking

process, especially as our understanding of

ecological processes improves and helps us

to identify and document the key factors

regulating bark beetle populations.

We stand at an interesting point in history,

one at which we have become much more aware

of the environment around us. We have an

increased desire to participate in resource

management processes that limit adverse

environmental change. Such processes include

efforts to restore and rehabilitate forests and

to conserve our natural resources.

ACKNOWLEDGMENTS

I

 wish to thank Gerald Baker, Gary Lawrence,

 and Michael Caprio of the Department

 of Entomology and Plant Pathology,

Mississippi State University, for their reviews

and suggestions. Approved for publication

as BC10100 of the Mississippi Agricultural

and Forestry Experiment Station, Mississippi

State University.

LITERATURE CITED

Allen, D.C. 1994. Healthy forestry–healthy forests: a

balancing act. Journal of Forestry. 92(11): 60.

Belanger, R.P.; Malac, B.F. 1980. Silviculture can reduce

losses from the southern pine beetle. Agric. Handb. 576.

[Washington, DC]: U.S. Department of Agriculture. 17 p.

Boyce, M.S.; Haney, A., eds. 1997. Ecosystem management:

applications for sustainable forest and wildlife resources.

New Haven, CT and London: Yale University Press. 392 p.

Brown, M.W.; Nebeker, T.E.; Honea, C.R. 1987. Thinning

increases loblolly pine vigor and resistance to bark beetles.

Southern Journal of Applied Forestry. 11(1): 28–31.

Carter, G.A.; Seal, M.R.; Haley, T. 1998. Airborne detection

of southern pine beetle damage using key spectral bands.

Canadian Journal of Forest Research. 28: 1040–1045.

Hicks, R.R.; Coster, J.E.; Mason, G.N. 1987. Forest insect

hazard rating. Journal of Forestry. 85(10): 20–25.

Mason, G.N.; Lorio, P.L.; Belanger, R.P.; Nettleton, W.A. 1985.

Rating the susceptibility of stands to southern pine beetle

attack. Agric. Handb. 645. [Washington, DC]: U.S.

Department of Agriculture. 31 p.

Matthews, J.S. 1998. Pest management strategies for Longhorn

Army Ammunition Plant and an assessment of aerial

videography for hazard rating pine stands for southern pine

beetle infestations. [Place of publication unknown]: Stephen

F. Austin State University. 91 p. M.S. thesis.

Nebeker, T.E. 2003. Integrated forest pest management. In:

Integrated pest management: current and future strategies.

Council for agricultural science and technology. Task Force

Rep. 140. [Place of publication unknown]: [Publisher

unknown]: 111–116.

Nebeker, T.E.; Hedden, R.L. 1984. Integrated forest pest

management in pine stands (6 + yrs.)—insects. In:

Branham, S.J.; Hertel, G.D., eds. Proceedings: Integrated

forest pest management symposium. Ames, IA: Council for

Agricultural Science and Technology: 116–125.

Nebeker, T.E.; Hodges, J.D. 1983. Influence of forestry

practices on host-susceptibility to bark beetles. Zeitschrift

Fur Angewandte Entomol. 96(2): 194–208.

Nebeker, T.E.; Hodges, J.D. 1985. Thinning and harvesting

practices to minimize site and stand disturbance and

susceptibility to bark beetle and disease attack. In:

Branham, S.J.; Thatcher, R.C., eds. Proceedings of a

symposium on integrated pest management research.

Gen. Tech. Rep. SO–56. New Orleans: U.S. Department

of Agriculture, Forest Service, Southern Forest

Experiment Station: 263–271.

Nebeker, T.E.; Hodges, J.D.; Karr, B.L.; Moehring, D.M.

1985. Thinning practices in southern pines–with pest

management recommendations. Tech. Bull. 1703. [Place

of publication unknown]: U.S. Department of Agriculture,

Forest Service. 36 p.

Sikorowski, P.P.; Lawrence, A.M.; Nebeker, T.E.; Price, T.S.

1996. Virus and virus-like particles found in southern pine

beetle adults in Mississippi and Georgia. Mississippi Agric.

For. Exp. Stn. Tech. Bull. 212. [Place of publication

unknown]: [Publisher unknown]. 9 p.

Stephen, F.P.; Browne, L.E. 1999. Using nutrient sources

to enhance parasitoid survival and oviposition [Abstract].

In: Biological control of bark beetles: Proceedings, western

forest insect and disease work conference. [Place of

publication unknown]: [Publisher unknown]. [Number

of pages unknown].

Stephen, F.P.; Browne, L.E. 2000. Application of EliminadeTM

parasitoid food to boles and crowns of pines (Pinaceae)

infested with Dendroctonus frontalis (Coleoptera:

Scolytidae). Canadian Journal of Entomology. 132: 983–985.

Traugott, T. 2000. Are my pine trees ready to thin? Mississippi

State Univ. Ext. Serv. Publ. 2260. [Place of publication

unknown]: [Publisher unknown]. 7 p.

Turchin, P.; Taylor, A.D.; Reeve, J.D. 1999. Dynamical

role of predators in population cycles of a forest insect:

an experimental test. Science. 285: 1068–1071.
161

Chapter 16.

The Impact and Control of

Major Southern Forest Diseases

A. Dan Wilson, Theodor

D. Leininger, William J.

Otrosina, L. David Dwinell,

and Nathan M. Schiff 1

Abstract—A variety of forest health issues,

concerns, and events have rapidly changed

southern forests and plantations in the past

two decades. These factors have strongly

impacted the ways we manage forest pests in

the Southern United States. This trend will no

doubt continue to shape forest pest management

in the future. The major issues and events of

concern include changing forest conditions,

urbanization, multiresource issues, increased

harvesting, forest fragmentation, expanding human

populations, pesticide bans, expansions of native

and nonnative pests into new regions, emergence

of new damaging insect-disease complexes, and

reduced resources to manage these problems.

The effects of some of these factors on forest

health priorities and specific pest-suppression

practices are discussed in relation to some major

hardwood and conifer diseases in southern forests.

The ways in which these pests are influencing

southern forest management priorities and

practices and the progress that past and present

pest-suppression research has made toward

solving some of these pest-suppression problems

also are discussed.

INTRODUCTION

T

he preceding two decades have brought a

barrage of new developments that are shaping

the evolution of forest management practices

with regard to forest health issues and disease

suppression in southern forests. Some of the more

important developments impacting forest health

management in the South include: (1) legislative

bans on the use of many pesticides and chemical

controls formerly used to manage forest pests;

(2) continued introductions of nonnative pests to

which many of our endemic tree species have

little resistance; (3) expansion in distributions and

outbreaks of important native pests into previously

unaffected areas; (4) occurrence of new synergistic

forest pest complexes previously unrecognized

as important to forest management decisions;

(5) nationwide reductions in the research work

force (forest pathologists) available to study

and develop new pest suppression technologies;

(6) drastic reductions in forest management and

pest-suppression activities on Federal lands;

(7) inadequate approaches to regional pest

problems as a result of overemphasis of theoretical

research approaches, e.g., modeling systems and

disease forecasting, instead of improvements in

direct, applied approaches to disease suppression;

and (8) the existence of new emerging endemic

diseases such as bacterial leaf scorch (Xylella

fastidiosa Wells and others) that are causing

widespread damage previously unrecorded in

commercially important fiber- and lumberproducing tree species (Billings 2000, Britton

and others 1998). The impact of these issues

and events on disease suppression and forest

management decisions in general will be treated

in the following discussions relevant to individual

major hardwood and conifer diseases that occur in

the southern region.

1

 Principal Research Pathologist, Research Plant

Pathologist, and Principal Research Entomologist,

U.S. Department of Agriculture Forest Service, Southern

Research Station, Stoneville, MS, 38776; and Supervisory

Research Pathologist and Principal Research Pathologist,

U.S. Department of Agriculture Forest Service, Southern

Research Station, Athens, GA 30602, respectively.
Southern Forest Science:

Past, Present, and Future

Forest Health

162

MAJOR HARDWOOD DISEASES

Oak Wilt in Urban Forests

U

rban forests are becoming increasingly

important components to be considered in the

development of forest management objectives

as cities and municipalities continue to encroach on

natural forest stands. Protection of tree resources

in urban areas is becoming more important, not

only because urban trees have commercial lumber

value or provide habitat and food for wildlife,

but because their aesthetic value contributes

significantly to property values. A good example

of this trend has been demonstrated by the impact

of oak wilt, caused by Ceratocystis fagacearum

(T.W. Bretz) J. Hunt, on urban forestry. Within

the last 20 years, oak wilt has caused increasingly

devastating losses to valuable urban and suburban

trees within and near metropolitan areas of Texas

in the South and within major cities in Minnesota,

Wisconsin, Iowa, and Illinois in the Midwest

(Wilson 2001).

Tree mortality in urban areas causes economic

losses in several ways. Reductions in landscape

aesthetics resulting from tree mortality can

significantly lower property values. The death

of a single large urban live oak in Texas can result

in a loss of as much as $20,000 in property value

(Dewers 1971). It is not uncommon for landowners

in Austin, TX, to sell their property once oak wilt

has been diagnosed on their land in order to avoid

the investment loss associated with the reduction

in property value. Losing valuable shade trees

can substantially increase utility bills (cooling

costs) for homeowners. Tree removal costs

also can be significant when they involve large

trees. Finally, replacement costs associated with

replanting trees adds to the final expense of losing

valuable landscape trees. The consequences of

increases in oak wilt incidence in valuable urban

trees have resulted in accelerated economic losses

now estimated to have exceeded $1 billion over an

area of at least 61 of 254 counties in Texas alone

(Wilson 2001).

The rise in oak wilt incidence in urban areas

has been attributed in part to increases in home

construction and landscape improvement activities

associated with urban development. Austin, TX,

with over 10,000 live oaks (Quercus fusiformis

Small and Q. virginiana Miller) killed by oak

wilt in the last 20 years, may be the most heavily

affected city in the United States. Residual trees

often sustain considerable damage during initial

tree clearing of land prior to home construction.

Heavy equipment frequently scrapes and removes

bark from trees, creating infection courts for the

introduction of oak wilt inoculum by insect vectors

(fig. 16.1). Tree wounding also occurs when trees

are pruned by landowners during times when

insect vector activity is high. When such trees

become infected, they initiate infection foci from

which new oak wilt infection centers develop and

spread by root-graft transmission. The storage of

oak wilt and bark beetle-infested firewood in piles

near residences provides both inoculum and insect

vectors by which wounded trees may become

infected. An increase in incidence of oak wilt

in natural stands has also contributed to a higher

incidence in urban areas. Oak wilt incidence

increased in many natural oak stands during

the first half of the 20th century in the Eastern

United States when Dutch elm disease, caused by

Ophiostoma ulmi (Buisman) Nannf. and O. novoulmi Brasier, and chestnut blight {Cryphonectria

parasitica (Murrill) Barr [formerly Endothia

parasitica (Murrill) Anderson & Anderson]}

caused changes in stand composition by removing

dominant species that were largely replaced by

red oak species susceptible to oak wilt (Wilson

2001). The increased incidence of oak wilt in

natural stands has since been closely linked to

changes in forest management practices such

as high-grade harvesting, preferential thinning, Figure 16.1—Live oak injured by heavy tree-clearing equipment

at a residential building site in Austin, TX, providing entry points

(infection courts) for introduction of the oak wilt fungus into

the living sapwood by insect vectors. Photo by A. Dan Wilson.
163Chapter 16. Major Southern Forest Diseases

overgrazing, and fire suppression that favor

reduced species diversity and increase the number

of susceptible red oaks in stands.

The Texas Forest Service administers the

Texas Oak Wilt Suppression Project (TOWSP)

with funding and technical assistance provided by

a combination of U.S. Department of Agriculture

Forest Service (Forest Service) funds and

matching funds provided by the State of Texas.

This has been among the very few cooperative

(State) disease suppression programs in the

country that have received Federal assistance

since 1995 (Wilson 2001). A recent addition

occurred when the sudden oak death pathogen,

Phytophthora ramorum Werres, was first

discovered in the United States (California) in

1995, and Federal funds were appropriated for

research and suppression beginning in 2003.

TOWSP personnel coordinate the efforts of local

governments and private citizens to detect and

control oak wilt. The project’s goals are to educate

the public, locate disease centers, provide technical

and cost-sharing assistance in suppressing the

fungus, and monitor suppression treatments to

control spread.

Recent improvements in oak wilt management

have resulted from modifications of existing

control strategies, empirical advances arising

from experiences gained during implementation of

suppression programs, and research developments

of new suppression technologies. Trenching, the

practice of mechanically cutting root connections

between healthy trees in advance of the visible

expanding edge of infection centers to control

root transmission of the oak wilt fungus, has

been recommended for many years (Himelick

and Fox 1961) and has long been the cornerstone

and primary means of suppressing the spread

of oak wilt in the United States (Wilson 2001).

In Texas, the fungus spreads primarily through

interconnected root systems, creating infection

foci with radial expansion rates that sometimes

exceed 31 m/year. In attempts to stop the advance

of infection, cooperators in the TOWSP began

cutting barrier trenches in 1988. The TOWSP

installed over 762,000 linear m of trench around

almost 4,000 infection centers detected in central

Texas by 2000 (Wilson 2001). This represented

treatment of about 44 percent of confirmed centers

detected, but < 10 percent of infection centers

likely to exist statewide. Trenching was about

67 percent successful in stopping the spread of

encircled infection centers by 1994 (Billings and

others 2001). Since 1994, 76 percent of trenches

have had no breakouts. This improvement was

attributed to installation of deeper trenches (up

to 1.8 m) and improved trench placement. The

majority of trench breakouts that occurred within

the first 3 years after trench installation were

due to improper trench placement or insufficient

trench depth that failed to sever preexisting root

grafts. Breakouts that occurred 3 or more years

after trench installation were more likely to result

from the formation of new root grafts across

the trench by fusions of new adventitious roots

arising in the loose, trench-backfill soil from

roots previously severed by trenching (Wilson

and Lester 2002). During the first several years

following trench installation, an abundance

of small adventitious roots commonly formed

from roots severed in the loose backfill soil by

trenching. These roots provided opportunities

for initiation of new root-graft connections across

trenches in subsequent years.

A recent oak wilt suppression research

study, conducted by a Forest Service scientist,

investigated the effectiveness of trench insert

materials in preventing trench breakouts initiated

by root grafting across the trench. These results

indicated that trench inserts did not significantly

reduce or stop root transmission during the first

3 years following trench installation, but that

the use of water-permeable inserts effectively

improved the performance of trenches beyond

the third post-trenching year, when trenches

are still normally effective, and extended trench

longevity indefinitely (Wilson and Lester 2002).

Water-impermeable materials, however,

sometimes promoted trench breakouts by their

tendency to redirect root growth around these

barriers, leading to the development of new rootgraft connections and associated oak wilt root

transmission across the trench. Water-permeable

inserts were more effective root barriers because

they did not direct root growth from the point

of root contact. The additional minimal cost of

trench inserts above trenching costs is justified

in urban and rural homestead sites where

valuable landscape trees require more protection,

and additional retrenching costs are avoided.

Assuming that trench depth and placement

problems are now solved through experiences

gained by the TOWSP, this improved method

of oak wilt suppression should greatly increase

trench effectiveness, and could potentially save

Texas landowners (alone) hundreds of millions of

dollars in tree removal costs and property value

depreciations if this control is vigorously

implemented by the TOWSP.
Southern Forest Science:

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164

The trenching research also confirmed

that applications of the systemic fungicide

propiconazole (Alamo©) by high-volume bole

injections, used by the TOWSP until 1997, are

ineffective in preventing root transmission of the

oak wilt pathogen in individual trees, despite the

high sensitivity of the fungus to this fungicide

(Wilson and Forse 1997). The sporadic and

undependable effectiveness of propiconazole was

attributed to the predominately upward mobility

of the fungicide, which precluded root treatment

when the fungicide was injected into the lower

bole. As previously applied, only a small fixed

proportion of the injected active ingredient moved

down into the root system by vapor phase activity.

City arborists partially compensated for this by

increasing the dosage of the fungicide from 3 to

10 ml/L or higher, thus increasing the amount of

active ingredient moving down into the roots by

vapor phase activity. However, previous research

indicated that soil-drench applications of the

fungicide at the tree dripline immediately prior

to challenge inoculations provided more effective

treatment (better coverage) and more protection

of root systems, because the fungicide is applied

and taken up at the distal ends of roots near root

apices, thus allowing more complete and thorough

distribution throughout the entire root system

(Wilson and Lester 1995).

The combined effect of using the improved

trenching methods (cultural control) with trench

inserts to prevent root transmission of oak wilt,

together with the increased effectiveness of soilapplied fungicide treatments, should significantly

advance efforts to suppress oak wilt disease in

semievergreen live oaks in Texas and in deciduous

oak species affected by this malady in other States.

If these controls are implemented, they could

potentially save landowners hundreds of millions

of dollars in tree removal costs and property value

depreciations in Texas, and substantially greater

savings in other areas of the United States

affected by this disease.

Hardwood Plantation Diseases

Hardwood tree species have been grown in

plantations throughout the Southeastern United

States for more than 50 years, although the total

acreage in hardwood plantations is much less

than that in softwood species. Since the early

1990s, market conditions and new approaches

to environmental issues have led to changes in

cultural methods for growing hardwoods and

the planting of many more acres of hardwoods.

Fiber-farming technology has allowed industrial

growers to plant bottomland hardwood species

on upland sites where rapid growth is fostered

by irrigation and liquid fertilization, a method

referred to as fertigation. This cultural

method allows year-round harvesting, whereas

wintertime harvesting in natural bottomland

stands is limited by wet soil conditions and

associated environmental concerns. In the Lower

Mississippi River Alluvial Valley (LMRAV) and

other areas in the Southeast, agricultural land

is being afforested in response to changing

agricultural markets and increasing interest

in ecosystem restoration (Stanturf and others

2000). Fiber farming and large-scale afforestation

present unique challenges and opportunities to

growers and pest management professionals.

American sycamore (Platanus occidentalis L.)

has good commercial value because of its rapid

growth and excellent pulping qualities for the

production of paper products. Sycamore is

commonly used in afforestation efforts. During

the early and mid-1970s, sycamore decline was

the main problem of concern to sycamore

producers in the Southeastern United States.

Surveys conducted in the 1970s, focusing on leaf

scorch, dieback, and cankers, found a complex of

diseases associated with sycamore decline. These

included canker stain, caused by Ceratocystis

fimbriata (Ellis & Halst.) F. platani J. M. Walter;

Botryosphaeria canker, caused by Botryosphaeria

rhodina (Cooke) Arx; and anthracnose, attributed

to two conidial stages of Apiognomonia veneta

(Sacc. & Speg.) Höhn (Filer and others 1975).

Leaf scorching occurred in all locations surveyed.

Leaves were described as scorched, eventually

turning completely brown, but not shedding

prematurely. These symptoms are common for

bacterial leaf scorch, a disease caused by Xylella

fastidiosa Wells and others (Leininger and others

1999, Sherald and Kostka 1992), but which was

attributed in the 1970s to late-summer symptoms

of anthracnose caused by fungi, particularly

species of Colletotrichum (McGarity 1976).

Tree diseases caused by X. fastidiosa were

considered hard to diagnose in the past because

diagnosticians were unfamiliar with the pathogen

and no diagnostic tools were available to detect

it. Symptoms were easily confused with those of

other biotic and abiotic factors such as moisture

stress and herbicide damage. The presence of

the bacterium in trees previously was difficult

to confirm using routine laboratory techniques

because of its fastidious nature (Sherald and

Kostka 1992). The advent of enzyme-linked

immunosorbent assays (ELISA) has made
165

diagnosis of X. fastidiosa infections in plants

routine, and has facilitated the detection of

bacterial leaf scorch in sycamore throughout the

Southeast. Polymerase chain reaction is also being

used to detect this bacterium in plants. Recent

visual surveys and ELISA testing of sycamore

plantations across the Southeast showed that

bacterial leaf scorch caused severe dieback,

decline, and mortality to sycamore saplings

growing on sites with or without irrigation (Britton

and others 1998). Initially, necrotic zones appear

along the midrib and main veins of leaves by late

July of the second growing season. Severe

marginal leaf scorching in foliage throughout

individual crowns and the entire stand is common

by the third year. Branch and top dieback occurs in

50 percent or more of a stand and some mortality

may occur by the fifth year. In severe cases,

premature salvage harvests are justified because

of concerns that stands will not contain sufficient

volume at the normal pulpwood rotation age

to pay for the additional carrying cost. Research

is currently underway to identify sycamore

genotypes that are tolerant to bacterial leaf scorch

disease (Chang and others 2002).

Many of the same hardwood species used in

fiber farming also are used for afforesting former

agricultural fields. These include several oak

species, eastern cottonwood (Populus deltoides

Bartr. ex Marsh.), American sycamore, and

green ash (Fraxinus pennsylvanica Marsh.).

Forest restoration through afforestation is just

beginning on a large scale in the LMRAV, and

many successful planting and cultural methods are

in use (Stanturf and others 2000). Development of

new management methods for controlling insect

and disease pests in these monocultural plantation

settings is badly needed. Cherrybark oak (Q.

falcata var. pagodifolia Ell.) seedlings growing

in nursery beds are susceptible to leaf injury and

stunting from Cylindrocladium scoparium Morg.

(Smyly and Filer 1977). Newly emerged hardwood

seedlings of many species are susceptible to

damage from soil-borne fungi such as species of

Fusarium, Rhizoctonia, and Pythium that cause

damping-off (Filer and Cordell 1983). Insect and

disease management guides for oaks (Solomon

and others 1997), sycamore (Leininger and others

1999), cottonwood (Morris and others 1975),

and ash (Solomon and others 1993) will aid in

diagnosing many problems, especially in older

stands. However, disease problems in nurseries

and on stored and newly planted seedlings will

require research and development of new control

methods, especially since traditional controls such

as methyl bromide have been eliminated. Concern

for the surrounding environment is likely to lead

to the development of biological and chemical

controls that minimize long-term effects on

ecosystems adjacent to plantations.

Declines of Oaks and Other Hardwoods

Decline disease syndromes, commonly called

declines, have been described by Manion and

Lachance (1992) as a progressive interaction of

abiotic events and biological factors or agents that

eventually can lead to individual tree death and

widespread forest mortality, depending on the

severity of the decline event. Declining trees

typically have been predisposed by abiotic factors

such as site index, soil type, and climate change,

although biotic factors such as old age or genotype

also can be predisposing factors. Actual decline

is triggered or incited by biotic or abiotic factors

such as drought, flooding, insect defoliation, or air

pollution. Trees that are already in a weakened

physiological state are weakened further, and

in this condition may die. They may recover,

perhaps to succumb later to other stresses.

Biological agents, for example, wood-boring

insects, phytophagous insects, wood decay fungi,

and bacteria can quickly colonize a physiologically

weakened tree and contribute to its final demise.

Declines occur periodically and are often triggered

by climatic extremes. For example, a report by

Ammon and others (1989) summarized 26 decline

events during the previous 140 years, and many

of these were brought on by periods of drought.

The most recent Forest Service report of forest

insect and disease conditions in the United States

(U.S. Department of Agriculture, Forest Service

2002) lists several Southeastern States in which

forests are experiencing oak decline as a result

of severe summer drought from 1998 to 2000.

A drought-induced decline of red oaks in the

Ozark and Ouachita Mountains of central

Arkansas reportedly covers hundreds of thousands

of acres and is associated with extraordinarily

high numbers of red oak borers [Enaphalodes

rufulus (Haldeman)] as a contributing factor

in the decline (U.S. Department of Agriculture,

Forest Service 2002). The Forest Service report

also describes oak declines in the Appalachian

Mountains of Virginia, North Carolina, Georgia,

and in Tennessee, where white oaks were

especially affected. During the summer of 2000,

many Nuttall (Q. nuttallii Palmer), willow (Q.

phellos L.), and water (Q. nigra L.) oaks began

declining in the Dewey-Wills Wildlife Management

Area in east-central Louisiana because of the 1998

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166

to 2000 drought. To date, nearly 6,000 acres of red

oaks have been affected, and the decline includes

attacks by the red oak borer and bacterial

wetwood infections. In west-central Mississippi

during the late spring of 2001, about 2,000 acres

of plantation-grown eastern cottonwood trees

were severely defoliated by a notodontid moth

[Gluphisia septentrionis (Walker)]; again, the 1998

to 2000 drought was believed to be a predisposing

factor in this decline. Defoliation by the common

Gluphisia was followed by cottonwood leaf beetle

(Chrysomela scripta F.) defoliations on the second

flush of leaves in 2001, further weakening the

trees. This pest of Populus species, which is

common in the Northeastern United States

and Southeastern Canada, defoliated the same

cottonwood trees in late spring 2002; lower

boles were also infected with bacterial wetwood.

Decline diseases involving climate may

be of particular concern for future southern

forests if predictions of extremes in atmospheric

temperature and precipitation resulting

from increased greenhouse gases hold true.

Anthropogenic inputs of gases such as carbon

dioxide, methane, and oxides of nitrogen into the

atmosphere have been increasing for some time

above apparently normal historic levels (Ning and

Abdollahi 1999). Some research suggests that

these increased gas concentrations are affecting

global surface temperatures by altering the

amount of solar energy reflected off the Earth’s

surface, resulting in the greenhouse effect (Ning

and Abdollahi 1999). Various hypotheses and

process models attempt to explain possible climate

changes and the subsequent effects to natural and

man-made ecosystems (National Assessment

Synthesis Team 2000). If there are major

systematic changes occurring in the climate,

they will likely give rise to more numerous

decline-related insect and disease problems.

Root and Butt Rots

Root and butt rots are the most serious cause

of lumber cull and degrade in southern forests.

All southern hardwood species are affected, and

the loss in terms of hardwood timber volume

amounts to millions of board feet annually. The

lower bole has always been of most concern to

hardwood forest managers because these are the

most valuable logs in the tree and the logs most

likely to be wounded by harvest equipment, by

logs pulled on skidder tracks, and by falling trees.

During most of the 20th century, forest managers

have tried to suppress root and butt rots in

southern hardwood stands by preventing the

creation of wound scars by which most decay fungi

gain entry into the tree. During the first half of

the last century, much effort went into controlling

wounds caused by fires. At least 80 percent of

lower bole decays in bottomland hardwoods were

attributed to fire scars during that period (Toole

1960). Protection of the lower bole is still of prime

concern in avoiding wounding. However, because

fires are rarely a problem in hardwood forests

today, this concern has largely shifted from fire

wound management to management of logging

wounds in residual trees caused by heavy

harvesting equipment during precommercial

thinning and partial commercial cuts. As demand

for hardwood lumber volume increases in the

future, management of root and butt rots in

hardwoods will slowly begin to move away from

the tolerance approach, or a willingness to live

with and allow for a certain amount of cull losses

by increasing cut volume, to a more preemptive

approach based on detecting these microbes in

standing trees and adjusting harvest schedules

to reduce losses. This approach will require the

capability of detecting incipient decay in standing

trees and determining the specific causes of decay.

However, new technology and decay models will

have to be developed to provide the necessary

knowledge and detection capabilities before this

approach becomes feasible.

At least 30 fungi are known to contribute

to root and butt rots in southern hardwoods,

but only a relatively few species cause most

of the damage. The root and butt rot fungi

most frequently encountered in most southern

hardwood stands include Pleurotus ostreatus

(Jacq.:Fr.); Ganoderma lucidum (W. Curt.:Fr.);

Hericium erinaceus (Bull.:Fr.) P.; Armillaria

tabescens (Scop.) Den.; Inonotus dryadeus

(Pers.:Fr.) Mu.; and Laetiporus sulphureus

(Bull.:Fr.) Mu. Other species that are important

to a lesser extent in individual hardwood species

include Inonotus hispidus (Bull.:Fr.) P. and

Tyromyces fissilis (Berk. & Curt.) Donk,

Lentinus tigrinus (Bull.:Fr.) Fr., Phellinus

igniarius (L.:Fr.) Quél, Trametes versicolor

(L.:Fr.) Pil., Rigidoporus lineatus (Pers.)

Ryv., R. ulmarius (Sowerby:Fr.) Imazeki in Ito,

Tomentella spp. (Pat.), and the ascomycete

Kretzschmaria deusta (Hoffm.:Fr.) P. Martin (=

Hypoxylon deustum (Hoffm.:Fr.) Grev.). The rate

of decay development within hardwoods varies

with the specific wood decay fungus present and

the host species involved (Toole 1959). Thus, decay

volume models must account for host species,

decay fungi, and log taper equations of individual
167

hardwood species when predicting future lumber

volume losses.2 This information would be

necessary for making stand harvesting decisions.

Also, a portable, inexpensive, easily used detection

device would be necessary to identify the presence

and extent of damage by specific decay fungi in

standing trees during routine stand evaluations

by timber cruisers for the purpose of planning

future harvest schedules.

The development of new technologies and

methodologies for mitigating losses by wood decay

fungi and other microbes causing defect losses in

standing timber has been an active field of interest

in recent years (Wilson and Lester 1997). Forest

managers and cruisers responsible for monitoring

forest stands are primarily interested in methods

and criteria for minimizing losses in lumber

volume and optimizing production in commercial

forests. A major challenge facing forest managers

is that of establishing policies and procedures

for making management decisions to deal with

defect losses including decay, discoloration, and

structural alterations in the properties of wood

caused by microorganisms in the sapwood and

heartwood of standing timber. Most estimates

indicate that at least 30 percent of the total lumber

volume available in many southern hardwood

stands is degraded or rendered unmerchantable

by lumber defects caused by these pests. Defects

in logs of standing trees can lead to significant

economic losses ranging from reduced lumber

production volume per acre to reduced lumber

value (grade), degrade to pulpwood status with

no merchantable lumber, and ultimately total loss

with no commercial value available for salvage.

The most significant challenges to be addressed

in relation to defect volume losses in lumber

production are to find ways of detecting defect in

logs of standing trees and to determine when to

cut individual trees that have log defects in order

to optimize production on an individual tree basis.

The methods used over the past 50 years to detect

the presence of log defects in standing trees by

cruisers of most commercial lumber producers

have involved “sounding” the wood (butt log) by

striking it with a hard object to locate hollows

in the lower bole. This archaic method is useful

only to detect advanced defect in standing trees

because trees with incipient or even intermediate

stages of defect usually cannot be distinguished

from healthy trees. Unfortunately, detecting

advanced defect is of little value, because it only

serves to identify unmerchantable trees. Also,

it occurs long after the decision should have been

made to harvest the tree and avoid the high level

of cull losses associated with the development of

defect to advanced stages.

Previous strategies for managing defects in

southern hardwoods involved simply accepting

the defect losses caused by microbes and insects

by removing the cull volume as the logs were

processed at the mill. With the growing demand

for quality lumber volume in the United States,

new technologies are now needed with the

capability of detecting defects in logs of standing

trees at incipient stages before significant damage

reduces the resulting lumber value in individual

trees. New methods and technologies under

development, such as electronic aroma detection

by conductive polymer analysis (CPA) of volatile

metabolites released from microbial log-degrading

pests, will allow preharvest field detection of log

defects using a portable detector (Wilson and

Lester 1997). This will be much more effective

than older methods in optimizing lumber yields

because it will prevent cull losses by allowing

detection and control of the problem long before

significant damage occurs. Early detection of these

defect-causing microbes in standing trees is useful

for predicting future potential damage because the

damage potential is species-specific and thus the

future depreciated value of individual trees can

be estimated by using decay models coupled

with fungi-specific decay expansion constants

in different hosts. An integral part of this early

detection system is the identification of the

specific microbe(s) present, because the rate

of development, type of damage, and location

of defect volume depends on the particular pest

present. Several applications of this technology

are being developed. For example, CPA recently

was used to distinguish the aroma signatures of

sapwood cores (host woods) from southern

hardwood species (table 16.1). Technology also has

been developed to identify forest pathogens and

wood decay fungi in vitro and in wood samples,

and to distinguish between different Armillaria

species for disease diagnosis (table 16.2). Hostand fungi-specific decay-volume models based on

log-taper equations of individual hardwood species

also are under development with the objective of

predicting future lumber volume losses for

planning and establishing future harvest schedules

for individual hardwood stands (see footnote 2).

2

 Wilson, A. Dan. 2002. Wood decay volume models. [Not

paged]. Unpublished data. On file with: Southern Research

Station, P.O. Box 227, Stoneville, MS 38776.

Chapter 16.

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168

Insect-Wood Decay Pest Complexes

Of all the pests that reduce hardwood lumber

production, none are more important than the

wood decay fungi and the hardwood borers. Those

capable of acting together in symbiotic complexes

are even more damaging. Recent Forest Service

research at the Southern Hardwoods Laboratory

in Stoneville, MS, has been aimed at identifying

and quantifying losses caused by important insect

and disease pests that are causing substantial

reductions in hardwood lumber production and

value. This work has revealed new, previously

unknown woodwasp-wood decay fungi complexes

capable, in some cases, of causing considerable

damage to logs in standing trees, ultimately

reducing hardwood lumber value. These wood

decay fungi are mycosymbionts of a peculiar

group of insects, the woodwasps (Hymenoptera:

Siricoidea), with larval stages that bore through

the wood of stressed and weakened hardwood

trees and cause significant damage by forming

galleries and vectoring (transmitting) wood decay

fungi in the process (Gilbertson 1984, Smith 1979).

Like most wood-feeding insects, woodwasps must

live in symbiotic relationships with wood decaying

microbes because they are incapable of digesting

cellulose. The decay fungi are carried in special

glands (mycangia) at the base of the abdomen near

Table 16.1—Global class membership (identity) of aroma profiles for sapwood cores of selected southern

hardwoods based on electrical aroma signatures obtained from the 32-sensor array of the Aromascan A32S

 Global class membershipa

Sapwood cores A. rubrumb C. caroliniana C. laevigata L. styraciflua P. deltoides P. occidentalis

 - - - - - - - - - - - - - - - - - - - - - - - - - - - percent - - - - - - - - - - - - - - - - - - - - - - - - - - -

Acer rubrum 98.0 0.0 0.0 0.0 0.0 0.0

Carpinus caroliniana 0.0 99.2 0.0 0.0 0.0 0.0

Celtis laevigata 0.0 0.0 91.3 3.8 0.0 0.0

Liquidambar styraciflua 0.0 0.0 3.7 96.7 0.0 0.0

Populus deltoides 0.0 0.0 0.0 0.0 98.8 0.0

Platanus occidentalis 0.0 0.0 0.0 0.0 1.5 99.3

a

 Percentage global class membership (relatedness) of sapwood core aroma profiles based on comparison against reference database

for southern hardwoods. Data only list comparisons between aroma signatures of sapwood cores from these six hardwood species.

b Mean global class membership for 10 replications per treatment.

Table 16.2—Determinations of global class memberships (identity)

of aroma profiles for four Armillaria spp. based on electronic aroma

signature comparisons with an Armillaria reference library database

obtained from the 32-sensor array of the Aromascan A32S

Global class membershipa

Armillaria spp. A. gallicab A. mellea A. ostoyae A. tabescens

- - - - - - - - - - - - - - - - percent - - - - - - - - - - - - - - - -

A. gallica 100.0 0.0 0.0 0.0

A. mellea 0.0 99.2 8.7 0.0

A. ostoyae 0.0 0.0 91.3 0.0

A. tabescens 0.0 0.8 0.0 100.0

a

 Percentage global class membership (relatedness) of Armillaria aroma profiles based

on comparison against reference database for these four Armillaria species. Data only

list comparisons between aroma signatures of these four Armillaria species. b Mean global class membership for 10 replications per treatment.
169

the ovipositor in female woodwasps. The adult

female woodwasp stores inoculum of the wood

decay fungus in these mycangial glands, which

are connected directly to the oviduct that passes

through the ovipositor. The decay fungus is

injected into the wood with the eggs during

oviposition. The fungus then grows rapidly and

produces extracellular cellulases, which digest the

wood for larval consumption (Kukor and Martin

1983). When the eggs hatch, the larvae begin

boring through the decayed wood, consuming

nutrients both from the decayed wood and the

mycelium of the fungus itself. The larvae cannot

consume and digest the wood until it is decayed

by the enzymes of the fungus. The larvae produce

extensive galleries throughout the rotting wood,

eventually pupate in the wood, and emerge as

adults making round exit holes. The wood is

decayed far beyond these borer galleries in all

directions. Most of these fungi grow very rapidly

through the wood, and the wood is decayed

almost completely over several years as both

the cellulose (wood fibers) and lignin are digested

by extracellular enzymes (Wilson and Schiff 2003).

Thus, all of these fungi are physiological white

rotters. The actions of these two pests together

result in synergistic damage to and economic loss

of merchantable hardwood lumber volume. The

decay fungi also produce discoloration in the wood

(a type of stain called zone lines) that further

degrade lumber value. The zone lines, produced

within decaying wood in association with these

wood decay fungi complexes, are a result of

somatic antagonism (SA) between different strains

of the wood decay fungi competing for the same

wood substrate (Wilson and Schiff 2000a). Zone

lines that form in wood as SA interactions between

xylariaceous fungi represent areas delimiting

their territory around decay zones (fig. 16.2).

The wood becomes riddled with all three types of

damage (borer galleries, decay, and discoloration

of wood) until the entire branch or bole becomes

unmerchantable. This is a perennial process

in which the damage may be compounded by

repeated infestations of branches and boles

by subsequent generations of the woodwasp.

Two major groups of woodwasps can affect

hardwood lumber production. The large, siricid

woodwasps (Siricidae: subfamily Tremicinae)

attack predominantly oaks, sugarberry (Celtis

laevigata Willd.), beech (Fagus grandifolia Ehrh.),

and other bottomland hardwood species. Smith

and Schiff (2002) provide a review and keys to the

siricid woodwasps of the Eastern United States.

These tremecine woodwasps vector predominantly

basidiomycetous wood decay fungi. The two most

common species are Tremex columba (Linnaeus)

and Eriotremex formosanus (Matsumura). The

smaller xiphydriid woodwasps attack mostly

maples, elms, and upland hardwood species.

They carry ascomycetous wood decay fungi that

form spores in microscopic sacks (asci) inside of

perithecia embedded in black stromatic tissues

that develop on the surface of the wood. The

woodwasp family (Xiphydriidae) has 22 described

genera, approximately 100 species, and a

worldwide distribution (Smith 1978). The family

is represented in the United States by a single

genus, Xiphydria, with 10 described native

species. Hitherto, we have isolated the

mycosymbionts from 6 of the 10 native xiphydriid

Figure 16.2—Zone lines observed in decayed wood of sugar

maple colonized by Daldinia concentrica, mycosymbiont of

Xiphydria maculata woodwasp larvae. These antagonistic

interactions form between the decay zones of xylariaceous

wood decay fungi around woodwasp galleries, and represent

areas delimiting their territory defended by the production of

dark inhibitory compounds. Photo by A. Dan Wilson.

Chapter 16.

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170

woodwasps known in North America, including X.

abdominalis Say, X. decem Smith & Schiff, X.

hicoriae Rohwer, X. maculata Say, X. scafa Smith,

and X. tibialis Say (Smith 1976, 1979). The known

wood decaying fungal symbionts of tremicine and

xiphydriid woodwasps in southern and eastern

hardwoods of the United States are summarized

in table 16.3. All of these mycosymbionts are

xylariaceous fungi (Ascomycotina: Xylariaceae),

which are known for their ability to cause white

rots in hardwood species. They are closely related

to Hypoxylon species that commonly attack

and rapidly decay weakened hardwood trees.

It was recently discovered that most of these

mycosymbionts are Xylaria species not previously

known to be symbionts with woodwasps (Wilson

and Schiff 2000b). These fungi do not usually form

the sexual stage in culture, which has hindered

identification to species.

Xiphydriid woodwasps oviposit primarily into

the axils of living hardwood branches, causing

extensive decay and galleries in this area. This

eventually weakens the limb which may then

be broken by wind or ice accumulation. The decay

can extend into the sapwood of the bole through

the remaining branch stub after the limb falls off.

Xiphydriid larvae continue to bore and develop

in the fallen limb on the ground. Larvae produce

galleries throughout the wood until the following

spring, pupate, and emerge as adults (Solomon

1995). Adults mate (optionally) and oviposit their

eggs once again into the axils of living branches or

into dead limbs on the ground to complete the

cycle. Most woodwasp species seem to be fairly

host-specific, often attacking only one or two

hardwood species, although a few species such

as X. tibialis have a number of hardwood hosts.

There also appears to be high fidelity in the

symbiotic association between woodwasp species

and their fungal symbiont. All woodwasp species

examined hitherto apparently depend only

on a single mycosymbiont for food and

cellulose decomposition.3

Woodwasp-wood decay fungi complexes have

been found in every major hardwood species.

Thus, these pest complexes are potentially

significant sources of log defects in all hardwood

stands. The occurrence of a new, nonnative siricid

woodwasp [Eriotremex formosanus (Matsumura)]

in hardwood forests of the Southern United

States is of considerable concern because this

pest has spread from Georgia to Texas since its

introduction into the United States in infested

wooden shipping crates brought back by the

Table 16.3—Symbiotic insect-wood decay fungi pest complexes that cause synergistic defect losses

of hardwood lumber volume in southern and eastern hardwood species

Woodwasp Fungal symbiont Major tree hosts Common names Referencesa

Siricidae

Eriotremex formosanus Basidiomycete Quercus phellos Willow oak Unpublished data

Tremex columba Cerrena unicolor Fagus grandifolia American beech Stillwell 1964, 1965

Celtis laevigata Sugarberry Unpublished data

Xiphidriidae

Xiphydria abdominalis Xylaria sp. Tilia americana Basswood Wilson and Schiff 2000b

X. decemb Xylaria sp. Betula nigra River birch Wilson and Schiff 2000b

X. hicoriae Daldinia sp.c Carya ovata Shagbark hickory Wilson and Schiff 2000b

X. maculata D. concentrica Acer saccharum Sugar maple Wilson and Schiff 2000b

T. americana Basswood Wilson and Schiff 2000b

X. mellipes Daldinia sp. B. papyrifera Paper birch Unpublished data

X. scafa Xylaria sp. Carpinus caroliniana American hornbeam Wilson and Schiff 2000b

X. tibialis Xylaria sp. A. saccharum Sugar maple Wilson and Schiff 2000b

C. caroliniana American hornbeam Wilson and Schiff 2000b

a

 References refer to source(s) that reported the symbiotic association and/or new hosts of the woodwasp-wood decay

fungus complex.

b A new species (Smith and Schiff 2001).

c

 The mycosymbiont of Xiphydria hicoriae was tentatively identified as a Daldinia species based on superficial observations

of culture morphology of a single mycangial strain isolated from only one female woodwasp.

3

 Personal communication. 2002. A. Dan Wilson, Principal

Research Pathologist, and Nathan Mark Schiff, Research

Entomologist, Southern Research Station, P.O. Box 227,

Stoneville, MS 38776.
171

military from Southeast Asia after the Vietnam

War in the early 1970s (Smith 1996). Recent decay

tests in vitro have demonstrated that the wood

decay fungus vectored by this woodwasp has

the potential to rapidly decay sapwood in many

eastern hardwoods (Wilson and Schiff 2003).

This fungus does not fruit readily on its oak

hosts or in vitro. This makes identification

difficult because the teleomorph or sexual stage

contains key taxonomic characters required for

identification. Perhaps these symbiotic fungi

do not normally produce sexual fruiting bodies

because they are regularly carried to appropriate

tree hosts by their woodwasp vector and,

therefore, do not have to expend energy to

produce a metabolically costly fruiting body for

sporulation and wind dispersal in order to survive.

This is why the extensive damage caused by these

pests often goes unnoticed until the tree is cut.

These wood decay fungi are rarely visible on the

outer surface of trees, and adult emergence holes

of the woodwasps look similar to those of other

hardwood borers. Consequently, the extent to

which these pests are damaging southern oak

forests is not known, although preliminary results

with wood decay studies in vitro indicate that

the mycosymbiont of E. formosanus and those

of xiphydriid woodwasps can cause substantial

white rots in eastern hardwoods after only 1 year

(Wilson and Schiff 2003). We do not yet understand

the importance of the role woodwasps play in the

dispersal of wood decay fungi, the impact they

have on forest health, or the effects that nonnative

pests such as E. formosanus and its symbiont will

have on lumber defect losses, hardwood timber

salvage, and forest decomposition cycles. Further

research is needed to elucidate the roles played

by these new pest complexes that are invading

our southern forests so that appropriate control

strategies can be developed. These insect-disease

pest complexes will likely receive increasing

attention in the future as forest managers become

more aware of their existence, their potential

to cause damage, and their long-term impact

on lumber production in hardwood forests.

MAJOR CONIFER DISEASES

T

he total land area in pine plantations now

exceeds 25 million acres in the Southern

United States (Belanger and others 2000).

The area is expected to more than double by the

year 2030. This valuable resource continues to

expand primarily on private lands, which furnish

the vast majority of timber products obtained from

southern forests (U.S. Department of Agriculture,

Forest Service 1988). The majority of these

plantations are more than 10 years of age. Loblolly

pine (Pinus taeda L.) and slash pine (P. elliottii

Engelm. var. elliottii) are the two most planted

and economically important pine species in the

South. The importance of southern forests and

plantations as the major suppliers of renewable

wood products in the United States continues to

increase as production in Western States declines

because of changing public land management

policies which are placing less emphasis on forest

commodity production in that region. The South is

well suited to take on this role because of the rapid

tree growth and production possible in southern

forests, the wide diversity of wood products that

can be produced, the responsiveness of southern

pines to intensive culture and even-aged

silvicultural systems, and the abundance of lowrelief sites allowing fully mechanized harvesting

(Blakeslee 1997).

Although relatively few pathogens have had

major impacts on pine production in southern

plantations and forests, the diseases caused by

these pathogens have caused very significant

losses in pulpwood and sawtimber production.

Fortunately, there also have been significant

advances within the past two decades in the

development of management strategies to

reduce losses to most major pine diseases.

These advances have often taken into

consideration changes in pathogen adaptations

to suppression strategies, environmental

conditions, host genetics, and legislative

constraints on management alternatives.

Fusiform Rust

Fusiform rust continues to be recognized

as the most damaging disease of southern pine

forests and plantations. The causal agent,

Cronartium quercuum (Berk.) Miyabe ex Shirai

f. sp. fusiforme (Hedge. & N. Hunt) Burdsall & G.

Snow, occurs in a broad band across the Southern

States and is prevalent in the most productive

high-quality loblolly and slash pine sites in this

region (Anderson and others 1986). Fusiform rust

incidence has increased dramatically within the

last 30 years, especially in intensively cultured

stands and in afforestation areas, where 47.9

million acres of former agricultural lands have

been converted into pine stands and plantations

(Starkey and others 1997). Annual losses to the

disease have been estimated at $35 million in

five Southeastern States (Schmidt 1998). Forest

managers throughout the South are concerned

about this disease because it affects stocking,

Chapter 16.

 Major Southern Forest Diseases
Southern Forest Science:

Past, Present, and Future

Forest Health

172

product quantity, and product quality. Fusiform

rust management in many areas is highly

integrated into land management activities. For

example, pine fertilization is frequently delayed

by managers until after the trees are 5 years

of age to reduce infection during the most

vulnerable years (Blakeslee 1997).

The development of genetic resistance in

planting stock has been the major disease

management strategy used to reduce the incidence

and severity of fusiform rust. The efforts of many

forest pathologists over the past 40 years have

brought genetic resistance to the forefront as an

effective routine tool for managing this disease.

The absence of a genetic linkage between rust

resistance and tree growth rate has allowed the

simultaneous development of genetically superior

fast-growing trees with enhanced fusiform rust

resistance. The genetic resistance approach

generally has reduced pine mortality and disease

severity in many sites, but some problems have

been encountered as a consequence of the wide

geographical variation in the genetics of the

fungus, which has apparently given rise to

strain-specific resistance, variations in pathogen

virulence, and perhaps pathogen adaptations

to host-resistance genes (Powers and Matthews

1979). Consequently, fungal strains in some

areas eventually overcome resistance. Previously,

pine breeders have attempted to stay ahead of

the rust fungus by constantly producing and

rotating new resistant pine growing stock to

avoid genetic changes in the fungus that occur

when pine selections are grown for too many

rotations in the field. However, a new strategy

involves the production of breeding lines that

minimize rust damage, not prevent infection

entirely, to avoid putting selection pressure

on the fungus to produce new virulent strains,

but maintain low-virulent strains to which pines

are tolerant (Walkinshaw and Barnett 1995).

Nevertheless, development of fusiform rust

resistance has translated directly to increased

economic value because the disease affects both

the quantity and quality of timber produced

(Cubbage and Wagner 2000).

Alternative approaches to fusiform rust

suppression have been helpful in shaping efforts

to develop integrated programs to manage this

disease. The development of predictive models has

been useful for identifying the relative hazard or

susceptibility of sites to rust damage based on site

and stand characteristics (Anderson and others

1986, Borders and Bailey 1986, Froelich and Snow

1986, Starkey and others 1997); and for predicting

preharvest rust-associated mortality (Devine

and Clutter 1985, Geron and Hafley 1988).

Other models have emphasized the importance

of preventing rust during stand establishment

(during the first 5 years) when the potential

impact of rust infection is the greatest (Nance

and others 1985). Triadimefon (Bayleton) seed

treatments followed by protective foliar sprays

have helped reduce the incidence of rust in

the early stages of stand development (Hare

and Snow 1983). The selective thinning of trees

with moderate-to-severe stem girdling caused

by rust galls is an effective means of reducing

losses to fusiform rust and greatly improves

the quality of trees in residual stands (Belanger

and others 2000).

Recent research has utilized molecular

techniques to study population structure,

cellular, and biological aspects of the pathogen

to determine genetic variation, identify the genetic

mechanism of fungus-induced gall formation in

pine hosts, locate rust-resistance genes in pine

host genomes, and define cellular resistance

responses (Covert and others 1977, Roberds

and others 1997, Wilcox and others 1996). This

information will ultimately be useful in developing

new genetic engineering strategies for creating

more resistant pines by taking advantage of new

knowledge of host-pathogen interactions at the

molecular level.

Pitch Canker

Pitch canker is a disease of pines caused by

Fusarium circinatum Nirenberg et O’Donnell

[= F. subglutinans (Wollenweber & Rienking)

P. E. Nelson, Toussoun & Marasas f. sp. pini

Correll and others]. The disease derives its name

from the induction of copious pitch flow associated

with cankers of pines. The classic symptom is a

bleeding, resinous canker of the main stem or

trunk, terminals, large branches, shoots, and

exposed roots. The canker is usually sunken and

the bark is retained, while the wood beneath the

canker is deeply resin-soaked. Dieback in the

crown results from cankers forming on the

branches or shoots. As the branches or shoots are

girdled by the fungus, the needles turn yellow to

reddish brown; later they turn grayish brown to

dark gray. It may take several years, however, for

a canker to girdle the main stem. The pitch-soaked

wood is a diagnostic character useful in separating

pitch cankers from most other maladies of pines

(Dwinell and others 1985). The symptoms of pitch

canker frequently vary by pine host and

management practices. In southern pines, trunk

cankers are common on Virginia (P. virginiana
173

Mill.), longleaf (P. palustris Mill.), and eastern

white (P. strobus L.) pines. Dieback is common

on slash, loblolly, shortleaf (P. echinata Mill.), sand

[P. clausa (Chapm. ex Engelm.) Vasey ex Sarg.],

and pond (P. serotina Michx.) pines. Trunk cankers

on slash pine are common in seed orchards and

are usually associated with the use of tree shakers

for cone removal. Cankers on exposed roots

can be found on slash pine in seed orchards and

other pines in landscape plantings (Dwinell and

others 1985).

Pitch canker is an incomplete descriptive name

for the range of damage caused by F. circinatum.

The pathogen infects a variety of vegetative and

reproductive pine tissues at different stages of

maturity and produces a diversity of symptoms.

Damage to pines by this fungus includes growth

suppression, stem deformation, and tree mortality.

The pitch canker fungus also causes mortality of

female flowers and mature cones, and deteriorates

seeds of several pine species. Dwinell and

Fraedrich (1997) isolated F. circinatum from

the surface and interior of immature shortleaf

pine cones from a North Carolina seed orchard.

They concluded that interior contamination

by F. circinatum was not correlated with necrotic

regions, caused primarily by insects, on the cone

surface. The mode of entry of the pitch canker

fungus into cones is unknown. Entire slash pine

seedlots and entire longleaf pine seed-crops have

been lost as a consequence of contamination by

F. circinatum, which resulted in low seed viability

and germination (Dwinell and others 1985).

Current research is aimed at determining whether

the pathogen is primarily on the seed surface or

infects the embryo. Contamination of seed in

longleaf and shortleaf pines is mostly on the seed

surface (Dwinell and Fraedrich 1997, Fraedrich

and Dwinell 1997). The fungus appears to be

primarily external (Dwinell 1999). There is little

empirical data linking seed contamination by F.

circinatum with seedling cankers that occur in

nursery beds and on outplanted sites. The major

result of seed contamination by the pitch canker

fungus is preemergence and postemergence

damping-off (Dwinell 1999, Dwinell and Fraedrich

2000). In addition, pitch canker occurs in bare-root

and container nurseries. Diseased pine seedlings

show chlorotic or reddish brown needles and

wilting. Pitch-soaked lesions usually occur at

or near the soil line, but occasionally are found

in the region of the cotyledonary node (Barnard

and Blakeslee 1980). The pitch canker fungus

has been associated with late-season mortality in

longleaf pine nurseries (Carey and Kelley 1994).

Fraedrich and Dwinell (1997) concluded that

F. circinatum is a wound pathogen of longleaf

pine seedlings. Any fresh wound, regardless of

cause or location, provides an infection court for

the pathogen. Insects can create wounds that can

be infected by airborne spores of the pathogen

or serve as vectors. In the Southeastern United

States, the deodar weevil (Pissodes nemorensis

Germar) creates wounds that may become infected

by airborne spores of the pathogen (Blakeslee

and others 1978). Recent unpublished research

indicates that the Nantucket pine tip moth

[Rhyacionia frustrana (Comstock)] may not be

associated with pitch canker in loblolly pine.4

 In

slash pine seed orchards, main stem cankers often

develop after injury caused by mechanical cone

harvesters. Also, injuries caused by wind and

hail may serve as entry points. Hurricanes and

tornadoes, in particular, have contributed to the

intensification of the disease in some seed orchards

(Dwinell and others 1985). The involvement

of insects, interactions with other pine diseases,

and numerous biotic and abiotic factors can

influence the incidence and severity of infections

by F. circinatum.

Annual mortality due to pitch canker in

the Southeastern United States has been low.

Southern pines, particularly loblolly, pond, and

shortleaf pines, usually recover from outbreaks

of shoot dieback (Barrows-Broaddus and Dwinell

1985, Kuhlman and others 1982). From 1945 to

1973, limited outbreaks of pitch canker were noted

in the Southeastern United States, but the disease

was not considered to be economically important.

In 1974, a shoot dieback identified as pitch canker

reached epidemic proportions on slash pine in

Florida plantations and seed orchards, and on

loblolly pine in North Carolina and Mississippi

seed orchards (Dwinell and others 1985). These

outbreaks spawned considerable research on pitch

canker. Over the last three decades, pitch canker

outbreaks in the South have occurred sporadically

in time and place. Pitch canker has also evolved

from a regional problem to one of national and

international importance (Dwinell 1999). Because

each outbreak has its own unique history, no

specific management strategy has been developed

to reduce or eliminate the threat of pitch canker

disease. An integrated management approach,

including chemical control, biocontrol, genetic

selection for resistance, and altered cultural

Chapter 16.

 Major Southern Forest Diseases

4

 Personal communication. 2002. L David Dwinell, Principal

Research Pathologist (retired), Southern Research Station,

320 Green Street, Athens, GA 30602.
Southern Forest Science:

Past, Present, and Future

Forest Health

174

practices should be considered for specific hosts

and growing conditions (Dwinell and others 1985).

External contamination of pine seeds can be

reduced or eliminated by appropriate seed

treatments (Dwinell 1999, Dwinell and Fraedrich

2000). Because wounds serve as infection courts

for F. circinatum, understanding the cause or

causes of the wounding is tantamount to managing

pitch canker (Dwinell and others 1985). In cases

where the wounding agent is an insect, chemical

control may reduce disease intensification.

However, regulations on the use of chemical

pesticides have severely limited this option.

Biocontrol organisms have been ineffective

(Barrows-Broaddus and others 1985). Variation

in the incidence of pitch canker is common among

clones within seed orchards, suggesting that

genetic selection for resistance is possible

(Barrows-Broaddus and Dwinell 1985, Dwinell

and others 1985).

Annosus Root Disease

The fungal root pathogen Heterobasidion

annosum (Fr.) Bref. is an economically important

pest of temperate conifers worldwide and a

powerful ecological force that can affect stand

structure and composition. Currently, H. annosum

S and P biological species in North America are

genetically distinct entities, but have not yet been

elevated to species status (Niemla and Korhonen

1998). Virtually no gene flow occurs between the

North American S and P groups, despite their

close proximity and overlapping host niches

(Otrosina and others 1992, 1993). At this time,

only the P biological species of H. annosum is

known to occur east of the Mississippi River

in the United States.

The most crucial stage in the disease cycle

of this pathogen is the entry of the fungus into

the stand through freshly cut stump surfaces.

These cut surfaces provide a suitable niche in

which airborne basidiospores can germinate and

subsequently bring about mycelial colonization of

the stump and root wood. Direct infection of roots

through root wounds or possibly unwounded roots

can occur in southern pines such as slash pine

(Hendrix and Kuhlman 1964) and in Abies species

(Garbelotto and others 1999). Once present in a

stand, infection spreads from stumps to healthy

trees via root contacts or grafts, creating everwidening mortality centers. The fungus derives

its nutrition from the enzymatic decomposition of

woody tissues, particularly lignin and to a lesser

extent cellulose, resulting in a physiological white

rot. Thus, wood rotted by H. annosum has a

characteristic delaminated appearance, and later

becomes lighter to almost white as the lignin is

removed from cellulosic wood fibers. Infected

trees are subject to windthrow as a result of

these structural changes in decayed wood.

Roots infected by the fungus in living trees

become highly resinous in advance of the invasion

front containing active mycelia. Resin production

is a physiological, host-defense response of the

tree to invasion and may slow and sometimes

contain the advance of the infection. The

production of resinous compounds in response to

infection is metabolically very costly in terms of

expended energy and may result in the weakening

of the tree over time. The expense of energy for

host defense in response to extensive root infection

by H. annosum predisposes conifers to attack by

bark beetles and other root diseases (Alexander

and others 1981, Schowalter and Filip 1993). The

fungus can persist saprotrophically in the highly

resinous stumps and stump roots in longleaf pine

for at least 7 years after thinning, providing

inoculum potential to infect healthy residual

trees via root grafts and contacts (Otrosina

and others 2002). Mortality is a dramatic effect

of H. annosum root disease, but growth reduction

usually results from sublethal infections. Because

root disease infection in trees is invisible until

very advanced stages, considerable growth

increment loss can occur in affected stands

without significant mortality (Alexander 1989,

Alexander and others 1981). On the other hand,

slash and loblolly pines may be able to sustain

considerable root infection before growth

reduction occurs (Bradford and others 1978,

Froelich and others 1977).

Considerable research has been done

regarding risk assessment with respect to

H. annosum root disease in the Southeastern

United States. Edaphic factors are important

elements associated with occurrence and hazard

associated with this disease. Sites classified

as high risk have well-drained soils containing

sand, low organic matter, and low water table

(Alexander 1989). These edaphic risk factors have

been used to develop hazard-rating maps (Anon.

1999). While these maps provide correlations

between certain soil types and H. annosum root

disease, there is little information available to

explain why or how soil factors affect disease

development. Soil type affects factors such as

water stress, microbial activity, aeration, and

root habit, and root configuration can affect the

root-infection processes.
175

Control of H. annosum root disease is achieved

primarily through prevention. The most effective

means to date is the prophylactic application of

powdered borax formulations to freshly cut stump

surfaces. Borax is toxic to basidiospores and

conidia of H. annosum (Hodges 1970). Prevention

and control is achieved only if borax applications

are timely, ideally within a few hours after tree

cutting. Technology that automates application

of powdered borax by devices that attach to feller

buncher equipment is now under development

(Karsky 1999). Another avenue for H. annosum

root disease control is through silvicultural

management. Research by Ross (1973) revealed

that thermal inactivation of basidiospores is

achieved when stump surfaces reach > 35° C,

resulting in no stump colonization. These

temperatures are common during the summer

months south of 34° N. latitude and form the basis

for the recommendation that southern pine stands

south of this latitude be thinned in the summer.

On the other hand, high temperature may not be

the sole factor responsible for lowering rates of

stump infection. Some research suggests that

microbial synergy at the stump surface may be

affected by high temperatures on stump surfaces,

since the fungus could be reisolated from surface

sterilized and inoculated wood bolts at

temperatures up to 40° C (Gooding 1964).

Less emphasis has been given to H. annosum

root disease control in recent years. Preventive

measures such as application of borax after

thinning are becoming less common. While some

data suggest that mortality of trees planted in

severely infested sites is minimal up to 22 years

after planting (Kuhlman 1986), multiple stand

entries and thinning without the proper preventive

measures, combined with longer rotation lengths,

will increase the importance of this disease in

coniferous forests in the Southern United States.

Such a scenario exists in certain longleaf pine

stands where H. annosum root disease results in

significant and steady mortality beginning when

trees are about 40 years of age. Longleaf pine has

been regarded as highly tolerant to this disease,

but various factors such as degraded soils, root

damage by equipment, and lengthened prescribed

fire regimes have resulted in increased mortality

due to H. annosum and other root pathogens in

these stands. Thus, long-term goals of managing

longleaf pine on a 75- to 120-year rotation for redcockaded woodpecker [Picoides borealis (Vieillot)]

habitat, stand restoration, and seed production can

be thwarted if appropriate caution is not exercised

regarding root disease (Otrosina and others

1999, 2002). More comprehensive information on

H. annosum root disease in North America and

Europe is presented in Otrosina and Scharpf

(1989) and Woodward and others (1998).

ACKNOWLEDGMENTS

T

he authors thank Evan Nebeker, Frank

Tainter, and Steve Meadows for reviewing

the manuscript.

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179

Chapter 17.

Monitoring the

Sustainability of the Southern Forest

Gregory A. Reams,

Neil Clark, and

James Chamberlain1

Abstract—The ecological and economic

sustainability of southern forests is being

questioned because there are many competing

uses for these forests and because there are large

regional shifts in forest land use. To adequately

understand the state of our forests and their use

with respect to sustainability, several significant

changes have been made in programs of the

U.S. Department of Agriculture Forest Service’s

Forest Inventory and Analysis (FIA) and Forest

Health Monitoring Research Work Units. These

changes are enabling these units to better assess

the status of and sustainability of our forests. The

FIA Program has replaced the 70-year-old periodic

forest survey sampling design with a continuous

annual sampling program. The new sampling

design provides for continuous monitoring and

reporting, with the emphasis on current status

and trends in forest resources and many of

the criteria and indicators of sustainable forest

management as identified by the Montreal

Process. The program is a collaborative partnership

among the Southern State forestry agencies and

the U.S. Department of Agriculture Forest Service,

Southern Research Station. The process used to

develop the new annual forest inventory program

has provided the opportunity to build stronger

partnerships with State forestry agencies,

universities, nongovernmental organizations, and

the forest industry. These new and renewed

partnerships are of considerable value in defining,

interpreting, and reporting on criteria and indicators

related to sustainable forestry. Recent collaborative

research has produced methods for estimating

forest area and area change from satellite imagery,

initiatives on how to quantify and report nontimber

forest products, and potential uses of remote

sensing instruments for on-plot measurements;

e.g., global positioning system units, lasers, and

camera systems.

INTRODUCTION

T

he ecological and economic sustainability

of our Nation’s forests is being questioned.

The definition of forest sustainability is

not fixed. As knowledge of forest processes

and uses expands, conceptions and components

of sustainability will change. At a minimum,

sustainability must include both ecological and

human dimensions: underlying ecological integrity

of soil, water, atmosphere, biological diversity and

productivity must relate to human needs for food,

water, health, shelter, fuel, and culture. The U.S.

Department of Agriculture Forest Service (Forest

Service), Forest Inventory and Analysis (FIA) and

Forest Health Monitoring (FHM) Programs have

been expanding their roles to include analyses of

biological diversity and productivity as influenced

by soil, water, and atmospheric composition. For

example, in the past decade these two programs

have been modified to provide the monitoring

data and analyses required for the investigation

of environmental concerns about air pollutant

impacts and effects of climate change on forests.

Concern over perceived and real trends in

forest resource conditions has led to numerous

requests for improvement in the quantity, quality,

and timeliness of information about forests and

enhanced access to this information. To address

these concerns, FIA and FHM contribute data

and analyses to a variety of national and global

assessments. The FIA and FHM data address

at least 38 of the 67 criteria and indicators of

sustainability for reporting under the Montreal

Process. FIA and FHM data are essential

to those who produce reports required by

the Resources Planning Act (RPA) and are

increasingly employed to support regional

resource assessments used as a basis for forest

planning. In response to these needs, FIA

and FHM have implemented an annual forest

inventory and monitoring program nationwide.

1

 Mathematical Statistician and Project Leader, U.S.

Department of Agriculture Forest Service, Southern Research

Station, Research Triangle Park, NC 27709; Research Forester

and Research Forest Products Technologist, U.S. Department

of Agriculture Forest Service, Southern Research Station,

Blacksburg, VA 24060, respectively.
Southern Forest Science:

Past, Present, and Future

Forest Health

180

THE FIA MISSION

T

he FIA Program has been in continuous

operation since 1930. It is the only consistent,

credible program that provides forest data

for all public and private land within the United

States. The program reports on the current status

of and trends in forest area, in species composition,

in tree size, volume, growth and mortality, and

in harvest removals. The FIA and FHM Programs

provide additional information on attributes

considered to be indicators of forest health. The

FIA Program also collects and reports information

on wood production and utilization rates by

various products, and on forest land ownership.

The FIA Program provides the most objective

and scientifically defensible information available

about the extent of forests, change in forest area,

change in tree species composition, and rates

of tree regeneration, growth, mortality,

and harvesting.

This information is used to help formulate

State and Federal policy decisions, including

international reporting; serve as a starting point

for more intensive studies on key ecosystem

processes; formulate business plans that are

economically and ecologically sustainable;

and inform the public about the health and

sustainability of the Nation’s forests.

Historically, the FIA Program has

reinventoried each State’s forests at intervals

of about 10 years. Prior to the annual inventory,

FIA had established that (1) forest land remains

the predominant land use in the South, (2) the

forest land base in the South has been stable

for several decades, (3) the pine component

of the South’s forest is moving steadily toward

more planted and fewer natural stands, (4) fears

of a southern pine growth decline related to air

pollutants have abated, and (5) growth rates on

forest industry lands have continued to increase

over the last four decades. The annual inventory

program enables FIA to identify changes in

trends much more quickly than the previous

decadal scale design allowed.

FOREST HEALTH MONITORING MISSION

T

he purpose of FHM is to make statements

about the status of and trends in the health

of forest ecosystems in the United States.

The FHM Program was established in 1991 to

address environmental concerns about how natural

factors such as insects, disease, and extreme

weather events, and anthropogenic stresses

such as air pollutants, climate change, population

growth, and nonnative species affect forests.

The National Acid Precipitation Assessment

Program (NAPAP) Forest Response Program of

the mid-1980s was in many ways a precursor of the

FHM Program. During the mid-1980s there was

increased concern that many forests in the United

States were exposed to acidic deposition and other

pollutants and that these regionally distributed

pollutants might be damaging forests (Barnard

and others 1990). Suspected declines in either

the productivity or health of southern pines,

red spruce, and sugar maple have been attributed

to causes of this kind. Many of the policy and

research questions asked by NAPAP are similar

to those addressed by the current FHM Program.

The FHM Program covers all forested lands

through a partnership involving the Forest

Service, State Foresters, and other State and

Federal Agencies and academic groups. The

FHM Program uses data from ground plots and

ground surveys, aerial surveys, and other biotic

and abiotic data sources to address forest health

and sustainability issues. There is one key

difference between FHM as implemented in

the United States and similar monitoring efforts

for Western Europe. Efforts in Europe have opted

for onsite monitoring of pollutants and weather

variables, while efforts in the United States have

relied on the monitoring of bioindicator plants and

other variables to monitor the effects of natural

and anthropogenic stresses. A key example is

that of monitoring the potential impact of ozone.

It is known that high levels of ozone do not injure

plants unless their stomata are open. High ozone

and temperatures often occur at the same time,

and these episodes often occur when stomata

are closed. Thus, FHM has opted to monitor

bioindicator species that are sufficiently sensitive

to specific pollutants. This allows for assignment

of injury to specific causes and for more accurate

estimation of the spatial distribution of injury.

The FHM Program is implemented through

five major activities. (1) Detection monitoring

uses nationally standardized ground and aerial

surveys to evaluate the status of and change

in forest conditions. (2) Evaluation monitoring

determines the extent, severity, and causes of

undesirable changes in forest health identified

through detection monitoring. (3) Research

on monitoring techniques creates sampling

designs and analytical techniques used to develop

bioindicators of forest health, provide early

detection of invasive species, and devise methods

for monitoring urban and riparian forests. (4)

Intensive site monitoring enhances understanding

of cause-effect relationships by linking the current
181

status of and trends in surveyed attributes and

bioindicators to process-level studies of specific

issues such as calcium depletion and carbon

cycling. (5) Analysis and reporting produces

peer-reviewed publications about analysis and

interpretation of sampled populations and reports

on forest health at national and regional levels.

Since 1999, the FHM ground plot network used

for detection monitoring has been integrated with

the more intensively sampled forest inventory

network maintained by the FIA Program.

Currently, FIA has one plot per 6,000 acres, and

FHM has one plot per 96,000 acres. Also, FIA

has adopted annual survey methods similar to

those used in the FHM Program. The merger of

the FIA and FHM plot networks and increased

coordination of survey methods enable both

programs to produce annual estimates of forest

area, forest inventory, and bioindicators of forest

health. Moreover, the FHM (phase 3) field plots

expand the suite of attributes sampled. The FHM

attribute list now includes tree crown conditions,

cover and diversity of lower vegetation (shrubs,

forbs, grasses, and vines), soils, lichen diversity

(as an indicator of air quality), indicator plants

for ozone presence, and coarse woody debris. This

expanded sampling provides data that can be used

to estimate forest carbon and forest fire fuel loads.

Readers are encouraged to visit http://fia.fs.fed.us/

library.htm#manuals for a thorough explanation

of all FHM indicators.

The assessment of forest health should be

based on definable criteria. The Forest Service’s

monitoring programs have adopted the Montreal

Process and criteria and indicators for evaluating

forest health and conditions to provide information

for sustainable forest management.

Some of the challenges and concepts that

must be considered in integrating and redesigning

inventory and monitoring programs are discussed

in the following section.

DESIGNING AN INVENTORY AND

MONITORING SYSTEM

I

n designing an inventory and monitoring

system, it is important to recognize that

definitions of sustainability change over time

and vary according to location and interests.

Changes in forest type and condition have

accelerated, and the rapid pace of change likely

will continue in the South. The combination of real

change, introduction of new sampled attributes,

and definitional changes over time calls for a

resilient and simple sampling frame. This goal

Chapter 17.

 Sustainability of the Southern Forest

is very different from the situation in most

inventories, in which the sampling strategy is

directly tied to the need to efficiently estimate

one or two closely related attributes of interest.

Fortunately for the continuity of FIA inventory

work, the types of measurement data that were

used to estimate forest resources 30 years ago

remain equally useful today. Nevertheless, a

dominant consideration in planning a long-term

monitoring program is the inevitability that a

highly efficient sample design, one that optimizes

on one or very few resources of interest, will go

out of date. Examples in forest inventory work

include the use of overly detailed stratification and

variable probability of selection based on volume

or value per unit area. Design features that involve

complex sample structure create potentially

serious difficulties, whereas an equal-probability

design permits greater adaptability and flexibility.

To minimize sample design obsolescence, structure

should be employed sparingly and with awareness

of its undesirable effects. Variable probability

sampling designs and other complex sampling

schemes are less amenable to the multiple and

changing objectives that long-term monitoring

designs must address, and therefore should be

avoided (Overton and Stehman 1996).

Simplicity is desirable for many reasons. It is

not only that sample elements will change over

time (as when forest plots become parking lots);

it is also that overall objectives change. Another

reason for simplicity is the growing recognition

that data collected by federally funded monitoring

programs should be accessible to the public at

large (Cowling 1992). With a relatively simple

sample design, it is more likely that valid results

and conclusions can be reached by various public

users of the databases.

The simplicity and resiliency needs of the

southern FIA Program have resulted in the use

of an equal-probability systematic sample design

(Roesch and Reams 1999). The new annualized

sample design employs five annual panels,

whereby plots measured in year one will be

remeasured in year six (fig. 17.1). The southern

FIA Program has historically used a completely

overlapping single-panel design for periodic

inventories and is implementing a similar design

in its annual surveys (Reams and Van Deusen

1999). To transition from the single-panel periodic

survey measured once every 10 years to an annual

survey, FIA subpaneled the periodic plot list into

five panels. Panels represent a sample in which the

same elements (plots in this case) are measured on
Southern Forest Science:

Past, Present, and Future

Forest Health

182

1 2 3 4 5

1

1

1

1

1 1

1 2 1

2 3

3

4

5 4

5

5

5

5

4

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4

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4

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Figure 17.1—An interpenetrating pattern for a five-panel

design. No element has another member from the same

panel as an immediate neighbor. There is one plot per

hexagon (Roesch and Reams 1999).

two or more occasions. Panel designs permit

studies of individual change and therefore allow

for the accounting of gross change that would be

masked in a nonoverlapping design. In southern’s

FIA Program, the use of a panel design is largely

due to the importance of estimating gross changes

in growth, mortality, and removals.

Once the new five-panel design is fully

implemented, the increased flexibility in inventory

estimation techniques will be realized. Annualized

estimates like the simple moving average that

is very similar to the periodic estimates are

providing the foundation of first-generation

annual inventory estimates (Roesch and Reams

1999). There are circumstances in which the

5-year moving average will overestimate or

underestimate current inventory. These situations

are most obvious when there is either an abrupt

shift in inventory or a strong trend in the attribute

of interest. For example, if a hurricane occurred

during the measurement of panel 3, inventory

estimates based on a 5-year moving average

would overestimate inventory in the affected

areas. In such a case, prior panels must be

dropped from the estimation process, and only

panels measured after the hurricane can be used

for inventory estimation (Reams and others 1999).

The time-series nature of the annual survey

provides increased flexibility in inventory

estimation. Several new approaches have been

presented by the scientific community and are

being considered for possible implementation.

These estimation methods include mixed

estimation (Van Deusen 1996), updating using

individual tree growth models (McRobert

and others 2000), and imputation (Reams

and Van Deusen 1999).

SUSTAINABILITY ASSESSMENTS

T

he past decade has seen increased concern

among natural resource managers, the science

community, and the public at large over the

current status of and emerging trends in forests

at international, national, and regional scales.

As a result, large-scale assessments of forest

sustainability related to one or more major

public policy themes or initiatives are becoming

increasingly necessary (Reams and others 1999).

FIA data, analyses, and interpretations provide

the basic information for all types of large-scale

forest assessments within the United States. The

FIA data also provide the basic inputs used to

model future forest distribution and composition,

and the availability of forest resources (Wear and

Greis 2002).

Sustainability has at least five elements (Floyd

and others 2001). These include (1) maintaining

resources over time, (2) a concern for future

generations, (3) an estimate of future needs,

(4) knowledge of current rates of resource use and

rates of regeneration, and (5) a widely accepted

view of some appropriate level of resource use.

In an effort to monitor forest sustainability

as it is defined by the Montreal Process, the

Forest Service has identified seven criteria of

sustainability with many measurable indicators

for each criterion. A criterion is a category of

conditions or processes by which sustainable

forest management may be assessed. A criterion is

characterized by a set of related indicators, which

are monitored periodically to assess change. An

indicator is a quantitative or qualitative variable

that can be measured or described, and which,

when observed periodically, demonstrates trends.

The seven criteria of forest sustainability are

(1) conservation of biodiversity; (2) maintenance

of the productive capacity of forest ecosystems;

(3) maintenance of forest ecosystem health

and vitality; (4) conservation and maintenance

of soil and water resources; (5) maintenance

of forest contribution to global carbon cycles;

(6) maintenance and enhancement of long-term

multiple socioeconomic benefits; and (7) legal,

institutional, and economic framework.

The degree to which the FHM and FIA

Programs address the ecological criteria and

indicators defined in the Montreal Process and

agreed upon in the 1995 Santiago Agreement are

displayed in table 17.1. The FIA and FHM

Programs provide a significant level of information
183

Table 17.1—The degree to which the FHM and FIA programs are currently addressing the criteria

and indicators of the Montreal Process as specified in the 1995 Santiago Agreementa

Criterion Indicator Measurement FHM and FIAb

Biological diversity

 Ecosystem diversity Areal extent of forest types Percent total forest ***

Percent nonprotected—

by forest type and age class *

Percent protected—

by forest type and age class *

Fragmentation of forest types ***

 Species diversity Forest-dependent species Total number—

no. of forest-dependent species **P

Status of risk species—

no. of breeding populations *

 Genetic diversity Proportion of former range ?

Population levels of

representative species—

species/diverse habitat/ *

 total range

Productive capacity Timber production—

area and net area available;

population estimate is coarser

than those provided by FIA ***

Total growing stock— Plantations—

merchant and nonmerchant area/growing stock, native

 available and exotic species ***

Annual removal wood products—

compared to sustainable volume *

Ecosystem health Insects and disease ***

 and vitality— Competition from exotics **P

 based on area Abiotic stressors Fire ***

 and percent Storms ***

 forest affected Flooding ***

Salination ***

Management/use Land clearance ***

Domestic animals *

Air pollutants S, N, O3, etc. **P

UV-B ?

Biological indicators of Epiphytes ***

key processes— Insects *

nutrient cycling, Fauna *

 reproduction, etc. Vegetation communities **P

Soil resources— Physical properties Erosion ***

based on area and/ Compaction **

or percent Other physical properties ***

Chemical properties Organic matter ***

Nutrients ***

Toxins **

Protective functions—

watersheds, floods,

 avalanche, riparian **

continued

Chapter 17.

 Sustainability of the Southern Forest
Southern Forest Science:

Past, Present, and Future

Forest Health

184

Table 17.1—The degree to which the FHM and FIA programs are currently addressing the criteria

and indicators of the Montreal Process as specified in the 1995 Santiago Agreementa (continued)

Criterion Indicator Measurement FHM and FIAb

Water resources— Stream flow and timing *

based on historical Biological diversity *

patterns Physical properties Temperature *

Sediments *

Chemical properties pH *

Dissolved oxygen *

Electrical conductivity *

Global carbon cycles— Total ecosystem biomass/

contributed by forests carbon pool—

e.g., forest type, age class, etc. **

Sequestration/release of carbon Standing biomass **

Coarse woody debris **P

Peat *

Soils ***

Forest products *

FHM = Forest Health Monitoring; FIA = Forest Inventory and Analysis; S = sulfur; N = nitrogen; O3 = ozone; UV-B = ultraviolet-B. a

 Criteria six and seven and corresponding indicators are not included because the FIA and FHM Programs are not designed to

sample and report these measures.

b * = techniques for measurement or estimation developed in other programs; ** = techniques for measurement or estimation under

development in FIA/FHM Programs; **P = techniques for measurement or estimation under development and tested in regional FIA/

FHM pilot studies; *** = techniques for measurement or estimation developed in FIA/FHM Programs and implemented nationally; ? =

unknown whether regional monitoring methods exist.

for the first five criteria, but very little for criteria

six and seven. Criteria six and seven are not listed

in table 17.1.

FIA and FHM data will continue to provide the

basic information at the forest area, plot, and tree

level for all types of regional, national, and

international forest assessments. The Heinz

Center report on the state of the Nation’s

ecosystems (Heinz Center 2002), national resource

assessments such as RPA (Powell and others

1993), the recently completed Southern

Appalachian Assessment (Southern Appalachian

Man and the Biosphere 1996), and the monitoring

of forest carbon stocks (Heath and Birdsey 1997)

rely heavily, and in many cases exclusively, on FIA

and FHM data to describe and estimate current

forest conditions and trends.

Well-planned and executed annual survey

systems can provide the basic baseline and

monitoring information to address the many

scientific questions regarding societal issue-driven

assessments of sustainability. Annual inventories

that are cost-effective, publicly trusted, and

provide unbiased information about forest

resource trends, are requisites for the

development of sound policy.

PRODUCTS OUTPUT REPORTS

F

IA and FHM field-plot systems provide

the inventory data used to estimate current

volume and volume changes induced by

removals and mortality. FIA also conducts

canvasses of primary wood-using facilities.

This component of the FIA Program complements

the field survey by providing independent

estimates of removals. Primary mills are those

that process roundwood in stem length, log, bolt,

or chip form directly from the woods. Examples

of industrial roundwood products are saw logs,

pulpwood, veneer logs, poles, and logs used to

make composite board products. Mills producing

products from residues generated at primary and

secondary processors are not canvassed. Trees

chipped in the woods are included in the estimate

of timber drain only if they are delivered to a

primary domestic manufacturer (Johnson 1998).

This timber products output (TPO) information

is used to track trends in industrial production

by mill type and by product mixes across mills.

Typical mill types include pulp mills, sawmills,

veneer mills, composite panel mills, and other

industrial mills; e.g., those that produce charcoal,

excelsior, logs for log homes, shavings, and
185

0

1 – 10

11 – 20

21 – 50

 51 – 100

101+ 

 No data 

Number of enterprises

firewood. The TPO information is often used

by industry analysts to estimate current rates

of demand.

In addition to timber, hundreds of plants,

fungi, and microorganisms are being collected

and harvested for personal and commercial use.

These nontimber forest products (NTFP) are

harvested from within and on the edges of forests.

They may include fungi, moss, lichen, herbs, vines,

shrubs, or trees. Many different parts of plants are

harvested, including roots, tubers, leaves, bark,

twigs and branches, fruit, sap and resin, and wood.

NTFPs can be classified into four major product

categories: (1) culinary, (2) wood based, (3) floral

and decorative, and (4) medicinal and dietary

supplements (Chamberlain and others 1998, 2002).

To date, inventory and monitoring of NTFPs

have been limited because there has been no

legislative mandate for such activities. However,

there is increasing awareness that NTFPs should

be recognized as renewable resources, managed

scientifically, and collected on a sustainable basis.

Forest managers have identified a number of

critical problems hindering efforts to improve

forest management for NTFPs. These problems

include (1) lack of baseline information on the

distribution, abundance, condition, and rates

of change for NTFP populations of interest;

(2) lack of knowledge about the biology and

ecology of the flora from which these products

originate; (3) diversity of the products and of

the collectors; (4) lack of market knowledge;

and (5) insufficient personnel and resources

to assign to NTFP management.

Emerging policies could

significantly change how the Forest

Service addresses NTFPs. A new bill

would require the Secretary of

Agriculture to determine sustainable

harvest methods and harvest levels for

these products and to establish methods

to ensure that revenues are returned to

the local units from which they were

generated. Implementation of this bill

may require tracking the distribution,

abundance, condition, removals, and final

markets of NTFPs.

In anticipation of these new reporting

requirements, a study has been initiated

to determine the importance of NTFP

industry throughout the South. The lack

of knowledge about the role of this industry

in rural communities hinders efforts to

allocate resources to improve management.

This study is an initial effort to define the overall

industry, identify obstacles to the collection of

data needed to estimate the volume and value

of NTFPs, and formulate protocols for regular

monitoring of output from the varied segments

of this industry.

Assessments of NTFP outputs have never been

undertaken in the South. For the most part, lists of

enterprises that could be contacted and surveyed

do not exist. We are able to utilize some lists, such

as those of ginseng dealers in each State. For the

most part, we are starting from scratch to develop

a framework that will allow for regular contact

with NTFP enterprises. On a regional basis, this

requires canvassing county agriculture agents to

get their estimates of the numbers of enterprises

within their geographic areas of responsibility.

County agents are asked to estimate the number

of firms that deal in four segments of the NTFP

industry; i.e., medicinal, edible, floral, and

specialty wood. Figure 17.2 presents the

perceptions of county agents in 7 of the 13

Southern States.

To undertake assessments of the output by

State will require identifying and contacting

enterprises in each county. To assess the

challenges of undertaking NTFP assessments

at this level, the project is carrying out a pilot

Figure 17.2—Number of nontimber forest products

enterprises by county for seven Southern States.

Chapter 17.

 Sustainability of the Southern Forest
Southern Forest Science:

Past, Present, and Future

Forest Health

186

study in western North Carolina. Leads to

enterprises are being obtained through initial

contacts with local experts. We expect this

project to produce a sample frame of NTFP

enterprises that will allow for regular monitoring

of enterprises in western North Carolina. This

work will provide insights that can be used to

extend monitoring of NTFPs to other States.

REMOTE SENSING

T

he 1998 Farm Bill that required the merger

of FIA and FHM survey activities into an

annual inventory and monitoring program

also requested that FIA and FHM make fuller

use of remote sensing technology. Nationally, FIA

and FHM are transitioning to the use of satellite

imagery to estimate and map forest area, and area

change. Studies completed in cooperation with

the Virginia Department of Forestry and Virginia

Polytechnic Institute and State University found

that satellite-based methods provide forest area

estimates comparable to those produced by the

traditional FIA photo-based method (Wayman

and others 2001). Wynne and others (2000) cite

several reasons for making a transition to greater

reliance on satellite-based remote sensing:

(1) the long-term viability of the National Aerial

Photography Program is in question; (2) satellite

imagery provides an opportunity for more

frequent updates; (3) certain analyses important

for forest inventory, such as spectral change

detection to improve removal estimates, can be

performed more easily; and (4) a spatially explicit

enumeration of the entire landscape can be

produced in a more automated fashion. This map

can be used to estimate the sizes of strata.

The use of remote sensing technology to

collect on-plot measurements is being investigated.

Given the intensive data needs mentioned

previously, field collection is time consuming and

costly. Increasingly on-plot remote sensors are

being used and developed to reduce collection time

and increase the precision of measurements for

some variables.

Active and passive remote sensors are being

used to locate forest plots, precisely locate and

map objects with geographic coordinates, and

collect data on many quantitative variables.

FIA uses global positioning systems (GPS)

(Hofmann-Wellenhof and others 2001, Kaplan

1996) to locate plot centers.

Other on-plot inventory applications include

ultrasonic or laser rangefinders (Fairweather

1994, Liu and others 1995). These tools are used

to map locations of objects, e.g., trees, subplots,

etc., and determine distances, e.g., plot radii or

limiting distances, with much greater accuracy

and speed than GPS. These rangefinders can

be combined with clinometers or angle gauges

to obtain other dimensional information, e.g.,

diameters, heights, stem form, etc. (Clark 2000,

Fairweather 1994, Williams and others 1999).

Other applications of on-plot remote sensors

in forestry include using charge-coupled device

(CCD) cameras to quantify understory and

biomass (Ramachandran and others 2000, TerMikaelian and Parker 2000); using CCD cameras

to record stand structure, regeneration, and

scenic beauty (Rudis and others 1998); using light

meters, densitometers, and digital hemispherical

cameras in canopy closure and regeneration

studies (Comeau and others 1998); using radio

frequency identification for tagging wildlife (Mans

and Eradus 1999) and trees (Wilson, in press);

and using remote sensors in wildlife monitoring

(Demarais and others 2000).

Though these sensors exist and are finding

application in forestry, most of them are

prototypes and are still in the development

process. The following improvements will

make these devices standard equipment for

inventory foresters:

• Confluence of sensors (GPS, camera,

distance, etc.) and processing (numerical

methods, models, optimizations) within

Geographic Information Systems for rapid

solution of problems

• Automated processes allowing the flow of many

observation data stream inputs into models,

analysis, and onward to the final report

• Advances from hand-held computers to

portable data assistants (Kerns and others, in

press) to wearable computers (Baber and

others 2001)

• Reduced power consumption

• Increased data storage

• Capability for wireless transmission of data

from woods to office

• Creation of weatherproof, durable instruments

• Reduced instrument costs

• Improved filters for interference, i.e., light,

humidity, sound

• Easier operation
187

• Improved means of validation

• Revitalization of sampling methods previously

underutilized due to previously impractical

data needs (Osawa and Kurachi 1997)

The southern FIA Program will continue to

take advantage of new technologies where they

aid in meeting the objectives of accurate and

cost-effective data collection. The exploration,

expansion, modification, and development

of on-plot remote sensing systems will be

required in order to achieve the objectives

of FIA in the future.

SUMMARY OF INVENTORY AND

MONITORING ENHANCEMENTS

I

n the 1998 report of the Second Blue Ribbon

Panel on FIA and the 1999 Farm Bill, a number

of enhancements were suggested to:

• Improve and expand information on ecosystems

and noncommodity values

• Recognize and identify ownership, regulatory,

and social impacts on forest productivity

• Integrate the FIA and FHM Programs

• Implement the use of satellite imagery for

estimation and mapping of forested ecosystems

• Produce the most current resource

data possible

• Implement a uniform approach on

all ownerships

• Increase consistency and compatibility among

FIA units

• Enhance coordination between FIA and

public agencies

• Improve service to all groups

In response to these needs, FIA and FHM

have introduced improvements in their sampling

programs and have designed pilot studies for

undersampled populations such as urban and

riparian areas and noncommodity values. Since

1999, the FHM ground-plot network used for

detection monitoring has been integrated with

the more intensively sampled forest inventory

network maintained by the FIA Program.

A study has been initiated to better understand

the importance of NTFP industry throughout

the South. The FIA Program has initiated a

national ownership survey to identify and quantify

the ownership, regulatory, and social impacts

on forest productivity. An annual survey is

now being implemented consistently across

ownerships, with the cooperation of State and

Federal partner agencies. Nationally, FIA and

FHM are transitioning to the use of satellite

imagery to estimate and map forest area and

area change. The national compatibility of data

collection, database production, estimation, and

reporting is ultimately leading to improved service

to all of FIA’s partner and customer groups.

LITERATURE CITED

Baber, C.; Cross, J.; Woolley, S.I.; Gaffney, V.L. 2001. Wearable

computing for field archaeology. In: IEEE fifth international

symposium on wearable computers. [Location of publisher

unknown]: [Publisher unknown]: 169–171.

Barnard, J.E.; Lucier, A.A.; Brooks, R.T. [and others]. 1990.

Changes in forest health and productivity in the United

States and Canada. NAPAP Rep. 16. [Washington, DC]:

[National Acid Precipitation Assessment Program].

[Number of pages unknown].

Chamberlain, J.L.; Bush, R.J.; Hammett, A.L. 1998. Nontimber

forest products: the other forest products. Forest Products

Journal. 48(10): 2–12.

Chamberlain, J.L.; Bush, R.J.; Hammett, A.L.; Araman, P.A.

2002. Eastern national forests: managing for nontimber

products. Journal of Forestry. 100(1): 8–14.

Clark, N.A. 2000. Initial results from a video-laser rangefinder

device. In Proceedings, 3rd southern forestry GIS conference.

[Location of publisher unknown]: [Publisher unknown].

D1. 6 p.

Comeau, P.G.; Gendron, F.; Letchford, T. 1998. A comparison

of several methods for estimating light under a paper birch

mixed wood stand. Canadian Journal of Forest Research.

28: 1843–1850.

Cowling, E.B. 1992. Challenges at the interface between

ecological and environmental monitoring: imperatives for

research and public policy. In: McKenzie, D.H.; Hyatt, D.E.;

McDonald, V.J., eds. Ecological indicators. London: Elsevier

Applied Science: 1461–1480.

Demarais, S.W.; McKinley, S.W.; Jacboson, H.A. 2000. Using

infrared-triggered cameras to survey white-tailed deer in

Mississippi. [Location of publisher unknown]: Mississippi

State University, Forest and Wildlife Research Center,

Research Advances. 5(3). 4 p.

Fairweather, S.E. 1994. Field tests of the Criterion 400 for

hardwood tree diameter measurements. Compiler. 12(1):

27–29.

Floyd, D.W.; Vonhof, S.L.; Seyfang, H.E. 2001. Forest

sustainability: a discussion guide for professional resource

managers. Journal of Forestry. 99(2): 8–27.

Heath, L.S.; Birdsey, R.A. 1997. A model for estimating the

US forest carbon budget. In: Birdsey, R.; Mickler, R.;

Sandberg, D. [and others], eds. USDA Forest Service

global change research program highlights: 1991–95. Gen.

Tech. Rep. NE–237. Radnor, PA: U.S. Department of

Agriculture, Forest Service, Northeastern Forest

Experiment Station: 107–109.

Heinz Center (H. John Heinz III Center for Science,

Economics, and the Environment). 2002. The state of

the Nation’s ecosystems. Cambridge, UK: Cambridge

University Press. 276 p.

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Hofmann-Wellenhof, B.; Lichtenegger, H.; Collins, J. 2001.

Global positioning system: theory and practice. 5th ed. rev.

New York: Springer-Verlag. 370 p.

Johnson, T.G. 1998. The Southeast’s timber industry—an

assessment of timber product output and use, 1995. Resour.

Bull. SRS–24. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southern Research Station.

24 p.

Kaplan, E.D., ed. 1996. Understanding GPS: principles and

applications. Boston: Artech House. 554 p.

Kerns, R.R.; Burk, T.E.; Bauer, M.E. 2001. Taking GIS/

remote sensing into the field. In: Proceedings of the first

international precision forestry symposium. Seattle:

University of Washington, College of Forest ResourcesPrecision Forestry Cooperative. D1. 24 p.

Liu, C.J.; Huang, X.; Eichenberger, J.K. 1995. Preliminary

test results of a prototype of Criterion. Southern Journal

of Applied Forestry. 19(2): 65–71.

Mans, B.J.; Eradus, W. 1999. Future developments on devices

for animal radiofrequency identification. Computers and

Electronics in Agriculture. (24)1–2: 109–117.

McRoberts, R.E.; Holdaway, M.R.; Lessard, V.C. 2000.

Comparing the STEMS and AFIS growth models with

respect to uncertainty of predictions. In: Hansen, M.; Burk,

T., eds. Proceedings of the IUFRO conference: integrated

tools for natural resource inventories in the 21st century.

Gen. Tech. Rep. NC–212. St. Paul, MN: U.S. Department

of Agriculture, Forest Service, North Central Research

Station: 207–213.

Osawa, A.; Kurachi, N. 1997. A light-weight CCD camera

technique for estimating three-dimensional distribution

of foliage density in tree crowns. Ecoscience. 4: 183–190.

Overton, W.S.; Stehman, S.V. 1996. Desirable design

characteristics for long-term monitoring of ecological

variables. Environmental and Ecological Statistics.

3: 349–361.

Powell, D.S.; Faulkner, J.L.; Darr, D.R. [and others]. 1993.

Forest resources of the United States, 1992. Gen. Tech. Rep.

RM–234. Fort Collins, CO: U.S. Department of Agriculture,

Forest Service, Rocky Mountain Forest and Range

Experiment Station. [Number of pages unknown].

Ramachandran, B.; Arvanitis, L.; Moore, S. 2000. Vegetation

monitoring and quantification. In: Proceedings, 3rd southern

forestry GIS conference. [Location of publisher unknown]:

[Publisher unknown]. D1. 23 p.

Reams, G.A.; Roesch, F.A.; Cost, N.D. 1999. Annual forest

inventory: cornerstone of sustainability in the South. Journal

of Forestry. 97(12): 21–26.

Reams, G.A; Van Deusen, P.C. 1999. The southern annual forest

inventory system. Journal of Agricultural, Biological, and

Environmental Statistics. 4(4): 346–360.

Roesch, F.A.; Reams, G.A. 1999. Analytical alternatives for an

annual inventory system. Journal of Forestry. 97(12): 33–37.

Rudis, V.A.; Thill, R.E.; Gramann, J.H. [and others]. 1998.

Understory structure by season following uneven-aged

reproduction cutting: a comparison of selected measures

2 and 6 years after treatment. Forest Ecology and

Management. 114: 309–320.

Southern Appalachian Man and the Biosphere. 1996. The

Southern Appalachian assessment terrestrial technical

report. Rep. 5 of 5. Atlanta: U.S. Department of Agriculture,

Forest Service, Southern Region. 288 p.

Ter-Mikaelian, M.T.; Parker, W.C. 2000. Estimating biomass

of white spruce seedlings with vertical photo imagery.

New Forests. 20(2): 145–162.

Van Deusen, P.C. 1996. Incorporating predictions into an annual

forest inventory. Canadian Journal of Forest Research. 26:

1709–1713.

Wayman, J.P.; Wynne, R.H.; Scrivani, J.A.; Reams, G.A. 2001.

Landsat TM-based forest area estimation using iterative

guided spectral class rejection. Photogrammetric

Engineering & Remote Sensing. 67(10): 1155–1166.

Wear, David N.; Greis, John G. 2002. The southern forest

resource assessment: summary report. Gen. Tech. Rep.

SRS–54. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southern Research Station. 103 p.

Wilson, D. 2001. Passive sensing for precision forestry

applications. In: Proceedings of the first international

precision forestry symposium. Seattle: University of

Washington, College of Forest Resources-Precision

Forestry Cooperative. D1. 24 p.

Williams, M.S.; Cormier, K.L.; Briggs, R.G.; Martinez, D.L.

1999. Evaluation of the Barr & Stroud FP15 and Criterion

400 laser dendrometers for measuring upper stem diameters

and heights. Forest Science. 45(1): 53–61.

Wynne, R.H.; Oderwald, R.G.; Reams, G.A.; Scrivani, J.A. 2000.

Optical remote sensing for forest area estimation. Journal of

Forestry. 98(5): 31–36.
Water and Soils
Southern Forest Science:

Past, Present, and Future

Water and Soils

190

Chapter 18.

Water and Soils.......................................................................... 191

Chapter 19.

Influences of Management of Southern Forests on

Water Quantity and Quality. ....................................... 195
191

Chapter 18.

Water and Soils

I

n the second chapter, Ge Sun and others discuss

the effects of management of southern forests

on water quantity and quality. Their thorough

review of water quality and quantity research

in the South provides valuable insights. This

research has shown that the greatest changes

in streamwater yield or ground-water table occur

immediately following forest land disturbances.

The overall water-quantity impact of silvicultural

operations is much less on wetlands than in

areas having greater relief and shallow soils.

Silvicultural practices in the South cause relatively

minor water-quality problems. Roads managed

without regard to best management practices

(BMP) are the major source of sedimentation

from forestry operations. Studies of the

cumulative effects of land use changes on water

quality are lacking. The capability of existing

computer modeling tools to describe the forest

hydrologic processes and provide practical

guidance in designing forest BMPs is limited.

The research discussed by Sun and others

is very closely related to the study of forest soils,

and I think it appropriate to say a little about

work in soil science in the South.

ADVANCES AND CHALLENGES

IN FOREST SOIL SCIENCE

I

t wasn’t until the early 1900s that linkages

between soils and silviculture were recognized,

and the forest soils discipline was established

(Wilde 1946). By the late 1930s, the forest was

recognized as a system consisting of aboveground

and belowground components. In the words of

Wilde, “An understanding of the forest lies just

as much below as above the ground line.” Organic

matter was known to be a critical component of

the soil, affecting fertility, moisture retention

properties, and the rooting environment. Studies

of the factors affecting soil organic matter

turnover and the role of organisms were well

known. The early forest soil scientists established

that soil quality could be affected by silvicultural

practices, especially harvesting and fire. It was

well understood that careless harvesting caused

reductions in soil organic matter, increased bulk

density to the detriment of rooting, and promoted

erosion. Fire was known to effect soil fertility,

especially when hot fires followed a harvesting

operation. Woodland grazing was very common,

and it was recognized that this grazing reduced

soil organic matter, altered the nutrient cycle

balance within the forest, and increased erosion.

Soil management was a well-established

concept by the early 1930s. In the silvicultural

context, soil management included the application

of practices to conserve soil organic matter,

maintain nutrient cycles and organic matter,

and enhance fertility. The biggest factor driving

the development of soil management practices

was the challenge of restoring millions of acres

of degraded agricultural lands to forest. Much

of this land occurred in the Southeastern United

States, and was the basis for many of the national

forests that were established during that period.

The need to reforest large acreages across a

diverse landscape led to the recognition of species

suitability, which was an early precursor to the

considerable body of soil-site research that was

to emerge in the 1960s to 1970s.

The tremendous advances in forest

productivity that have been realized in the

Southeastern United States are a testament

to the effectiveness of the soil management

practices that are based on a large body of

forest soils research. The relationships of

species to site conditions were recognized early

on, and eventually led to the development of

formal classification systems and the design of

forest soil or site surveys. Those systems also

facilitated the application of soil management

prescriptions across the region. These approaches

were embraced by the forest products industry

in the Southeast, which used soil and site

inventories as a basis for harvest scheduling,

site preparation prescriptions, fertilization, and

weed control prescriptions.

Carl C. Trettin1

1

 Soil Scientist and Project Leader, U.S. Department of

Agriculture Forest Service, Southern Research Station,

Charleston, SC 29414.
Southern Forest Science:

Past, Present, and Future

Water and Soils

192

Major advances in forest soil science occurred

in the areas of fertilization, water management,

and site preparation (Bernier and Winget 1975,

Stone 1984, Youngberg 1978, Youngberg and

Davey 1970). Given that the soils of the

Southeastern United States are old, highly

weathered, and generally abused, development

of fertilization prescriptions was fundamental

to the reforestation efforts and for improving

site productivity. As a result, prescriptions for

nitrogen and phosphorus fertilization are now

routine across the region. Similarly, the site

preparation techniques developed to ameliorate

certain soil conditions and reduce vegetative

competition also represent an important advance

in soil management. Bedding is perhaps the best

example of these techniques. The use of elevated

planting beds improves aeration and moisture

conditions and tends to concentrate nutrients

in the rooting zone. Water management

prescriptions evolved when it was recognized

that water regimes could be manipulated to

reduce potential soil damage during forest

operations, improve regeneration, and sustain

productivity and water quality.

Research in the Southeastern United States

produced major advances made in the fields

of soil biology and soil chemistry. A prominent

example is Marx’s research on mycorrhizae (Marx

and Bryan 1975), which has widely influenced

nursery practices, stand regeneration, and fertility

management. The various “acid rain” research

programs also made considerable contributions

to the understanding of soil biology and chemical

processes. That work provided the basis for

detailed investigations on nutrient cycling,

soil acidification, and organic matter dynamics.

Understanding the different sensitivities among

forest types, e.g., high-elevation spruce-fir vs.

Piedmont mixed hardwoods, has provided the

basis for improved environmental management.

The impacts of silvicultural practices on

the soil have been explored extensively.

Considerations about the effects of harvesting,

site preparation, or water management on soil

quality were based on concerns about sustaining

the productive capacity of the site. Research

usually showed that such operations significantly

affected soil characteristics, e.g., soil bulk density

and organic matter decomposition rate, during the

immediate posttreatment period. However, such

short-term effects are rarely linked to changes

in site productivity and impact studies are rarely

sustained beyond 2 to 3 years. Tools for

interpreting short-term effects over the long

term, i.e, rotation, have not been developed.

The concept of riparian buffer zones

acknowledges the fundamental linkages between

soil and hydrologic processes. Effective design

and implementation of buffer zones depends on

understanding the ameliorative goal (i.e., sediment

removal, reduction in nitrate concentration), and

biogeochemical and hydrologic processes. This

would not be possible without the advances in soil

and hydrologic sciences. The application of this

information and concept has been extensive,

affecting the design of BMPs and the evolution

of ecological engineering as a discipline. The

ability to manage natural systems or engineer

biological systems, e.g., constructed wetlands,

to achieve particular outcomes is fundamental

to sustaining healthy forests.

Now and in the next few decades,

the maintenance of productivity will be the

most important challenge. As the acreage of

commercially available forest land declines, there

will be a need to produce even greater biomass on

the remaining land. Therefore, it will be necessary

to develop more intensive fertilization and water

management prescriptions. Similarly, advances

in the production and use of genetically improved

stock may necessitate a parallel effort to optimize

fertility and moisture regimes. Questions about

impacts of land management on the soil remain.

For example, fire effects are still under study.

Considerable work remains to be done before

we understand sufficiently the role of roots in

soil biogeochemical processes and the associated

interactions with plant productivity.

How will a changing environment affect the

region’s forest soils? Climate change may involve

altered thermal and moisture regimes; How will

this affect the sustainability of the resource?

The southern forests are being fragmented by

suburban development (Wear and Greis 2002).

What are the implications for soil and water

resources? Clearly, most of the forest soils in

the Southeastern United States have been

disturbed, and have changed over the past 200

years. If we knew more about the history of that

process, it would be easier to anticipate the future.

Unfortunately, there is virtually no basis for

assessing the long-term changes in forest soils

in the Southeastern States. An exception is

the work on the Calhoun Experimental Forest
193

over the past 40 years, which highlights the

importance of being able to assess long-term

change (Richter and Markewitz 2001). It is clear

from that work, and the numerous short-term

impact studies, that long-term soils studies are

needed to provide the basis for sustainable

management. The U.S. Department of Agriculture

Forest Service’s experimental forest network

could be used to address soil and water science

questions over time and across most of the major

forest types in North America.

Perhaps the most difficult challenge will

be the development of spatially explicit, processbased forest soil simulation models that will

allow the consideration of management

alternatives at the landscape scale. As forest

resource management moves into the realm of

precision agriculture, better information is going

to be needed to optimize both economic and

noncommodity values. At present, most processbased forest soil simulation models are based

on data for uplands and cannot be applied directly

to the complex mosaic of upland, wetland, and

aquatic resources at the landscape scale. Models

provide a means for synthesizing data, providing

interpretations, and identifying important

knowledge gaps. Improving the quality and

applicability of forest soil and hydrology models

will enhance our ability to provide interpretations

at the spatial and temporal scales that are

appropriate to major issues and questions.

The models will also provide the basis for

quantifying the uncertainties associated with

our interpretations.

LITERATURE CITED

Armson, K.A. 1970. Soils, roots, and foresters. In: Youngberg,

C.T.; Davey, C.B. Tree growth and forest soils: Proceedings,

3rd North American forest soils conference. Corvallis, OR:

Oregon State University Press: 513–522.

Bernier, B.; Winget, C.H., eds. 1975. Forest soils and forest land

management. Proceedings, 4th North American forest soils

conference. [Place of publication unknown]: [Publisher

unknown]. 675 p.

Marx, D.H.; Bryan, W.C. 1975. The significance of

mycorrhizae to forest trees. In: Bernier, B.; Winget, C.H.,

eds. Proceedings, 4th North American forest soils conference.

[Place of publication unknown]: [Publisher unknown]:

107–117.

Richter, D.D., Jr.; Markewitz, D. 2001. Understanding soil

change. Cambridge, United Kingdom: Cambridge University

Press. 255 p.

Stone, E.L., ed. 1984. Forest soils and treatment impacts.

Proceedings, 6th North American forest soils conference.

[Knoxville, TN]: [University of Tennessee]. 454 p.

Wear, D.N.; Greis, J.G., eds. 2002. Southern forest resource

assessment. Gen. Tech. Rep. SRS–53. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southern

Research Station. 635 p.

Wilde, S.A. 1946. Forest soils and forest growth. Waltham,

MA: Chronica Botanica Co. 241 p.

Youngberg, C.T.; Davey, C.B., eds. 1970. Tree growth and

forest soils. Proceedings, 3rd North American forest soils

conference. Corvallis, OR: Oregon State University Press.

527 p.

Youngberg, C.T., ed. 1978. Forest soils and land use.

Proceedings, 5th North American forest soils conference.

Ft. Collins, CO: Colorado State University. 623 p.

Chapter 18.

Water and Soils

195

Chapter 19.

Influences of Management of Southern Forests on

Water Quantity and Quality

Ge Sun, Mark Riedel,

Rhett Jackson,Randy

Kolka, Devendra Amatya,

and Jim Shepard1

Abstract—Water is a key output of southern

forests and is critical to other processes, functions,

and values of forest ecosystems. This chapter

synthesizes published literature about the effects

of forest management practices on water quantity

and water quality across the Southern United

States region. We evaluate the influences of forest

management at different temporal and spatial

scales, and we recognize the heterogeneity of

forest ecosystems; e.g., wetlands and uplands in

the South. Hydrologic models that were developed

specifically for southeastern forests were reviewed.

We conclude that the greatest streamwater yield

or ground-water table changes occur immediately

following forest land disturbances. The overall

water-quantity impact of silvicultural operations

on wetlands is much less than in areas having

greater relief and shallow soils. Water quality from

forested watersheds is the best when compared

to that from other land uses. Silvicultural practices

in the South caused relatively minor water-quality

problems. Roads without best management

practices (BMP) are the major source of

sedimentation. Studies on the cumulative effects

of land use changes on water quality are lacking.

Exiting computer modeling tools are useful but

limited in describing the forest hydrologic processes

and providing practical guidance in designing forest

BMPs. Recommendations to future research

on forestry BMPs and forest hydrology in general

are proposed.

INTRODUCTION

Water is a key output of southern forests

and is critical to other processes, functions,

and values of forest ecosystems. Most of the

drinking water in the South comes from forested

watersheds. Much of our current understanding of

the linkages between southern forest management

and water quantity and quality is derived from

long-term watershed-scale experiments conducted

in more than 140 small watersheds in various

physiographic regions in the 13 Southern States

(Chang 2002). This chapter synthesizes published

literature about the effects of forest management

on water quantity and water quality across the

region. We evaluate the influences of forest

management at different temporal and spatial

scales. We recognize the heterogeneity of forest

ecosystem, e.g., wetlands and uplands, as affected

by climate, geology, and topography. We identify

sensitive regions and discuss the effects of

management activities on the timing of hydrologic

responses across the physiographic regions of

the South. We scale up information derived from

experiments at field and watershed scales to

the regional level. Forest management practices

examined in this chapter include harvesting, site

preparation, bedding, surface drainage, road

building, fertilizer and herbicide applications, and

fire management. A review of regional hydrologic

characteristics across nine physiographic regions

is used as a framework to contrast effects of

various management practices on key waterquantity and water-quality variables. Hydrologic

models that were developed specifically for

southeastern forests are reviewed.

1

 Research Hydrologist, U.S. Department of Agriculture

Forest Service, Southern Research Station, Raleigh,

NC 27606; Research Hydrologist, U.S. Department of

Agriculture Forest Service, Southern Research Station,

Otto, NC 28763; Associate Professor, University of Georgia,

Warnell School of Forest Resources, Athens, GA 30602;

Research Soil Scientist, U.S. Department of Agriculture

Forest Service, North Central Research Station, Grand

Rapids, MN 55744; Research Hydrologist, U.S. Department

of Agriculture Forest Service, Southern Research Station,

Charleston, SC 29414; and Sustainable Forestry Program

Manager, National Council for Air and Stream

Improvement, Newberry, FL 32669, respectively.
Southern Forest Science:

Past, Present, and Future

Water and Soils

196

Central Appalachian

Broadleaf Forest–Coniferous

Forest–Meadow

Eastern Broadleaf

Forest (Oceanic)

Eastern Broadleaf

Forest (Continental)

Ozark Broadleaf

Forest–Meadow

Ouachita Mixed

Forest–Meadow

Southeastern Mixed

Forest

Outer Coastal Plain Mixed Forest

Lower Mississippi Riverine Forest

Prairie Parkland (Subtropical)

Ecoregion 

provinces

 23 – 200

 200 – 400

 400 – 600

 600 – 800

 800 – 1000

1000 – 1200

1200 – 1400

Runoff (mm/year) 

Recommendations for future research on forestry

best management practices (BMP) and forest

hydrology in general are proposed.

CLIMATE, TOPOGRAPHY, AND HYDROLOGY

C

limate, underlying geology, and topography

are the major factors that dictate regional

hydrologic patterns, soil development, and

forest structure and functions. Any attempts

to project the impacts of management practices

on hydrology must consider these factors as a

background. Most southern forests are located

in the climate system described as humid forest

climate with cool winters and warm-to-hot

summers (Muller and Grymes 1998). However,

topography and elevation in the Southern United

States alter this pattern greatly and result in a

variety of hydrologic conditions (Daniels and

others 1973).

The South can be described in various ways

to facilitate characterization of forest hydrologic

conditions in the region and forces that drive them.

Bailey’s ecoregion classification system is useful

in this connection (Bailey 1995) (fig. 19.1). Bailey

describes 10 major provinces that intersect with

the southern geographic region, and each of these

provinces has its unique hydrologic characteristics

as affected by climate, topography, soils, and

vegetation. We use nine major ecoregion provinces

that support forest ecosystems as a spatial

framework for describing the general hydrology in

the South. We refer to information obtained from

regional long-term hydrometeorological databases

(Wolock and McCabe 1999) in discussing total

annual runoff amount, runoff:precipitation ratio,

and seasonal distribution of runoff (table 19.1).

Seasonal dynamics of stream runoff

depend on the balances of precipitation input,

evapotranspiration (ET) loss, and soil moisture

storage capacity. Long-term monthly hydrologic

data from four forest sites show that both climate

(precipitation and potential ET) and topography

(upland vs. flatland) are critical in determining

the seasonal distribution of streamflow (figs. 19.2A

through 19.2D). Across the Southeastern United

States, potential ET is generally higher than

precipitation in annual total, and in summer, but

lower in other seasons. Therefore, streamflow is

highest in winter and lowest in summer. Flatlands

have much lower total flow than hilly uplands in

summer. Variations of hydrologic characteristics

described define all aspects of the water quantity

and quality responses to management and design

of BMPs (table 19.1).

Figure 19.1—

Provinces of the

Bailey ecoregion

and annual runoff

of the Southern

United States.
197Chapter 19. Water Quantity and Quality

Table 19.1—Hydrologic characteristics of eight major physiographic regions in the Southern United States

Physiographic Forest management

province Topography Climate and hydrology concerns

Outer Coastal Plain Poorly drained flat High precipitation (PPT) (> 1200 Impacts on forested

Mixed Forest lands with elevation mm/year) and warm temperatures, wetland hydroperiod and

< 100 m above high evapotransipration (ET) (> 65 water quality; artificial

sea level percent of PPT), variable runoff amount surface drainage essential

(300–800 mm/year), low runoff ratio

(< 30 percent in most of area) and slowmoving streams

Southern Mixed Covers upper Coastal PPT (1200–1400 mm/year) moderate Sedimentation caused by

Forest Plain and Piedmont, runoff amount (200–800 mm/year) new forest disturbance

elevation 100–300 m and runoff ratio (20–60 percent) and historical land uses;

channel erosion common

Central Appalachian Steep hillslopes at PPT (1100–2000 mm/year), high runoff Sedimentation caused

Broadleaf Forest— high elevations (400–1200 mm/year) and runoff ratio by new forest road

Coniferous Forest— (300–2000 m) (> 50 percent); low ET due to low construction and historical

Meadow (Blue air temperature land uses; fish habitat

Ridge)

Eastern Broadleaf Rugged topography PPT (1000–1600 mm/year), high runoff Sedimentation caused

Forest (Oceanic) with elevation 300– ratios > 40 percent by hardwood forest

800 m; long, narrow harvesting

valleys and ridges

Eastern Broadleaf Dendritic drainage with PPT decreases from 1400 to 1000 Sedimentation caused by

Forest (Continental) winding narrow-crested mm/year northward, runoff amount road and harvesting

(Cumberland Plateau) ridges and deep, narrow (500–700 mm/year) and ratios operations

valleys; elevation (35–45 percent) decline westward

100–400 m

Lower Mississippi Alluvial plains, elevation PPT (1200–1500 mm/year) with a Harvesting impacts on

Riverine Forest < 50 m decreasing south-north gradient; low wetland water quality

runoff amount (450–550 mm/year) and site productivity

and runoff ratio (< 35 percent)

Ouachita Mixed Forest— Rugged topography Precipitation decreasing northwestward Effects of forestry activities

Meadow and Ozark with relief over 300 m from1500 to 400 mm/year with runoff on water quality and

Broadleaf Forest— and narrow valleys (400–550 mm/year) and runoff ratio (> site productivity

Meadow and floodplains 45 percent)highest at high elevations in

the Ouachita and Boston Mountains

Prairie Parkland Flat, with elevation Low but variable precipitation decreases Water shortage, intensive

(Subtropical) < 5 m in the Coastal dramatically westward (700–1100 mm/ pine forest management

Plain to 500 m in the year); high ET, low runoff (50–300 mm/ effects on sedimentation

western Great Plains year) and runoff ratio (5–25 percent)
Southern Forest Science:

Past, Present, and Future

Water and Soils

198

(C)

Jan

Feb

March

April

May

June

July

Aug

Sept

Oct

Nov

Dec

0

50

100

150

200 PPT

PET

Runoff

Sept

March

0

50

100

150

200

Jan

Feb

April

May

June

July

Aug

Oct

Nov

Dec

PPT

PET

Runoff

(A)

Streamflow(mm/month)

Month

March

0

50

100

150

200

Jan

Feb

April

May

June

July

Aug

Sept

Oct

Nov

Dec

(B)

PPT

PET

Runoff

Streamflow (mm/month)

100

150

200

0

50

Jan

Feb

March

April

May

June

July

Aug

Sept

Oct

Nov

Dec

PPT

PET

Runoff

(D)

Month

WATER-QUANTITY IMPACTS

Water quantity or water yield refers not only

to total waterflow volume on an annual basis

but also to the timing of flow over shorter

periods, as in the case of seasonal flow patterns

or peak flow rates. For forested wetlands, the

most important hydrologic variable is hydroperiod,

the number of days when surface water is present

per year. Hydroperiod, which is affected both by

precipitation and by ET, controls the chemical and

biological processes of wetlands. The fluctuation

of the water table reflects the change in soil water

storage that is roughly the difference between

precipitation and ET and runoff. Because the

hydrologic characteristics of uplands differ

from those of wetlands, and because the forest

management practices employed on uplands

differ from those employed on wetlands, we

discuss the effects of management on water

quality for uplands and for wetlands separately.

Water-Quantity Impacts: Uplands

Harvesting—Without exception, experiments

at Coweeta Hydrologic Laboratory (Coweeta)

showed that forest harvesting in the Appalachian

Mountains by clearcuts or partial cuts resulted

in increased streamflow (Swank and others 1988).

Clearcuts caused water yield to increase by 26

to 41 cm, or 28 to 65 percent of control during

the first year after harvest (Douglass and Swank

1972, Swank and others 2001). Harvesting riparian

vegetation resulted in a 12-percent increase in

daily discharge on average and a nearly complete

loss of diurnal variation in discharge (Dunford

and Fletcher 1947). Douglass and Swank (1972)

quantified the annual response of water yield to

harvesting as a function of tree species, aspects

and elevations of the watersheds, solar energy

received, and basal area removed.

A paired watershed approach similar to the one

developed at Coweeta was used to study effects

of pine forest management on stormflow and soil

loss in the Ouachita Mountains of Oklahoma and

Arkansas in the 1980s (Scoles and others 1994).

Small-watershed experiments in this region

showed that (1) clearcutting increased annual

stormflow volume by 100 mm, or 40 percent, and

increased the number of stormflow events the first

year after harvesting as a result of reduction of

ET, however, subsoiling, a practice of breaking

down large forest soil pores, reversed this

response; (2) stormflow and peak flows under

flood-producing conditions (high rainfall, wet soils)

were not affected by forest removal; (3) peak flows

Figure 19.2—Seasonal distribution of streamflow from four representative

forested watersheds across the Southern United States: (A) Arkansas mountains,

(B) North Carolina Coastal Plain, (C) Texas shrubland, and (D) Georgia Piedmont

(PPT= precipitation; PET= potential evapotranspiration).
199

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Posttreatment (years)

Actual minus predicted streamflow (cm)

First

Second

First

Second

Treatment

tended to increase as harvest intensity increased.

However, the differences were not large enough

to be statistically important. Harvesting had the

most influence on peak flows during late summer

and early fall, when storms were generally small.

Blackburn and others (1985) reported

hydrology and water-quality changes following

clearcut timber harvesting in nine small gauged

watersheds in eastern Texas. Three watersheds

were clearcut, sheared, windrowed, and burned;

three were clearcut and drum chopped; and three

were left untreated as controls. During the first

year following harvesting, stormflow averaged 147

mm for the intensively site-prepared watersheds,

84 mm for the chopped watersheds, and 25 mm

for the controls. Stormflow in the second through

fourth years following harvesting was less than

half that measured in the first year.

With natural regeneration of plants, the

increases in water yield declined logarithmically

each year after the initial treatment (Swank and

Helvey 1970, Swank and others 1988) (fig. 19.3).

Depending on the history of forests, water yield

recovered 30 to 50 years after harvesting in the

Appalachian region (Swift and Swank 1981).

At Coweeta, the water-yield increases on the

treatment watersheds decreased at a rate of

approximately 2 mm per 1-percent increase in

regenerative forest cover (Hibbert 1966). Trimble

and Weirich (1987) derived similar conclusions

from correlations between historic hydrology and

reforestation data (1919 to 1967) for large basins

(2820 to 19 450 km2

) across the Piedmont regions.

They found that reforestation reduced water yield

in the Piedmont region, with the most significant

reductions in water yield occurring in dry years.

Over large heterogeneous basins, 10- to 28-percent

increases in forest cover were correlated with

reductions in annual water yield of 30 mm (4

percent) to 100 mm (21 percent). Small changes

of water yield resulting from modest land use

conversion, while not observable on first-order

and second-order watersheds, were additive in the

downstream direction and resulted in significant

water-yield reductions for the encompassing

larger basins.

Increases in water yield that result from

forest harvesting are not distributed equally over

the seasons. It was estimated that approximately

60 percent of the observed increase in water

yield resulting from deciduous tree harvesting

occurred in the late summer (July) to early winter

(November) period. The majority of this increase

occurred during the normally low-flow months

of August, September, and October (Douglass

and Swank 1972).

Conversion from deciduous to coniferous—

At Coweeta, conversion of broadleaf deciduous

forests to eastern pines reduced streamflow by 20

percent (Swank and Douglas 1974). The magnitude

Figure 19.3—Annual

streamflow responses to

repeated harvesting of mixed

hardwood forest (watershed

13 at Coweeta Hydrologic

Laboratory) (adapted from

Swank and others 1988).

Chapter 19.

Water Quantity and Quality
Southern Forest Science:

Past, Present, and Future

Water and Soils

200

of yield reduction is sensitive to precipitation,

with greater reductions occurring during

relatively wet years. Two factors are chiefly

responsible for the observed reductions in

streamflow. First, the interception capacity and

subsequent evaporative losses of the white pine

(Pinus strobus L.) stands can be twice those of

 the mixed hardwood communities they replaced

(Swank and Vose 1994). Second, most of the

precipitation occurring at Coweeta falls during

low-volume, low-intensity rainfall events. Under

these conditions, large amounts of precipitation

can be intercepted by the evergreen tree canopy

and can evaporate. Thus, conversion from mixed

deciduous to coniferous species has a significant

impact on water yield.

Although monthly water yield was always

reduced after conversion from hardwoods

to pines, the reduction was most pronounced

during December to April when the differences

of ecosystem ET (especially from interception

losses) between the two forest types were the

largest (Swank and others 1988).

Conversion from forest to grass—Conversion

of 80 percent of a forested watershed with low

tree density to Kentucky 31 fescue grass (Festuca

L.) did not cause immediate increase in water yield

at Coweeta (Hibbert 1966). A fertilized, highly

vigorous, and productive grass system (> 1 m in

height) could have used as much water as a forest.

However, grass decline resulted in increased total

annual water yield and baseflow, especially during

the winter seasons. Flow frequency analysis

suggested that dense grass or recolonizing forest

might use more water than natural mature

hardwoods during the summer growing season

(Burt and Swank 1992). Stormflow frequency also

increased as a result of forest conversion to grass.

Conversion from forest to mountain grazing—

Although conversion from forest to grazing

increased total water yield, the impacts of

grazing on infiltration and ultimately peak flow

rates were the most significant effects of the

hydrologic changes. Before grazing, 102 mm

of effective precipitation produced a maximum

peak discharge of approximately 1.15 m3

/s/km2.

After grazing, it generated a peak discharge

of approximately 28.7 m3

/s/km2 (Johnson 1952).

Hydrologic impacts of the mountain grazing were

no longer detectable after 4 years of regrowth.

Conversion from forest to farmland—

Researchers at Coweeta conducted experiments

that combined forest removal practices with land

use change. These experiments were designed to

investigate the effects of typical land use practices

in the Southern Appalachians on water yield and

quality. For example, one 9-ha watershed was

converted to an operational mountain farm by

removing the forest and allowing farmers to utilize

local agricultural practices including row cropping

and unregulated grazing (Johnson and Kovner

1956). Following the treatment, annual water yield

from the watershed increased 22 cm (Bosch and

Hewlett 1982).

Water-Quantity Impacts: Wetlands

Wetland hydrology is extremely dynamic,

involving complex interactions of surface water

and ground water. Wetland hydrology research in

the Southern United States is relatively new (Sun

and others 2001). Most studies of the hydrologic

impacts on southern forested wetlands have

been conducted in the last two decades. Wetland

hydrologic processes are ground-water driven.

This review focuses on water-table responses

to forest management practices. We review

hydrologic impacts by wetland types because

each wetland type has unique hydrologic features

and responses.

Bottomlands—Harvesting of bottomland forests

usually has little long-term effect on hydroperiod

if BMPs are employed (Lockaby and others

1997a) or alternative harvesting methods, e.g.,

helicopters, are used (Perison 1997, Rapp and

others 2001). The most common hydrologic change

following harvesting of bottomlands is elevation

of the water table (Aust and Lea 1992, Lockaby

and others 1997b, Perison 1997, Wang 1996). This

“watering-up” is attributed to these: (1) reduction

of canopy interception and plant transpiration, (2)

reduction of soil saturated hydraulic conductivity

and increase of bulk density if harvesting sites are

severely disturbed, and (3) increase of surface

water storage and blocking of surface and

subsurface drainage. However, one exceptional

response has been reported: the water table in

dark-colored organic soils dropped 20 to 40 cm

during the postharvest period (Lockaby and

others 1994). The causes of this unique response

are not well understood. The water-table effects

of forest harvesting on flood plains are most

pronounced during the first two growing seasons

(Lockaby and others 1997b, Wang 1996).

Depressional wetlands (cypress domes and

Carolina bays)—Many depressional wetlands

that are seasonally dry and isolated from streams

or rivers are present in the Southeastern United

States, and especially in Florida and on the
201

Atlantic Coastal Plain (Tiner and others 2002).

Examples are cypress domes (ponds), Carolina

bays, and pocosin wetlands of different sizes. They

are important habitats for reptiles and amphibians

(Russell and others 2002). Many of the small

isolated wetlands are imbedded in intensively

managed plantations. Isolated wetlands have

similar hydrologic characteristics. They receive

water and nutrient inputs mainly from

precipitation, and lose water through the ET

process. Physical and chemical interactions with

surrounding uplands and deeper aquifers vary

depending on local geology, but usually are minor

as a consequence of the generally flat topography

and the presence of thick fine-textured layers

beneath the shallow surficial aquifer.

A hydrologic impact study at a 42-ha

northcentral Florida site consisting of a mosaic

of cypress ponds/pine flatwoods (Bliss and

Comerford 2002, Crownover and others 1995, Sun

and others 2000b) suggests that tree removals

from isolated wetlands and surrounding uplands

caused the water table to rise and runoff to

increase. Harvesting of wetlands and surrounding

uplands, and harvesting of wetlands alone, raised

the level of the water table by as much as 100 cm.

This effect on the water table was greatest during

the first dry growing season. It was not significant

subsequently; and in fact, the water table was

somewhat lower than the control in the subsequent

relatively wet years. The hydrologic regime at

this site appeared to recover within 5 years. A

retrospective 25-year study on a similar landscape

in the Coastal Plain of Georgia suggests that the

hydrologic impacts of harvesting pine plantations

on cypress wetlands are inconclusive (Batzer

and others 2000).

Wet flats and pocosins—Wet flats and pocosins

occur on broad interstream divides on poorly

drained soils. Wet flats occurring on higher

elevations are better drained than pocosins, which

develop thick organic layers. Most of the wet pine

flats and pocosins have been intensively managed

for timber production. Forest harvesting practices

generally result in short-term water-table rise and

an increase in runoff. A long-term watershed-scale

(48 to 64 ha) study on a cypress-pine flatwoods

landscape at the Bradford Forest in northern

Florida showed that “maximum” disturbance

caused a 15-cm or 150-percent increase in water

yield and the “minimum” disturbance resulted in

only an insignificant increase (3 cm) in water yield.

Water table rose significantly for both treatments,

especially during the drought months (Riekerk

1989b). In the sixth year after treatment, runoff

from the maximum disturbance watershed was

still significantly 65 percent higher than the

predicted value from a regression equation. The

ground-water tables in both disturbance sites

remained higher than the control. Hydrologic

changes (water table and runoff) were most

pronounced in dry years. These findings were

consistent with those of other experimental and

modeling studies (Sun and others 1998a) in the

region. Williams and Lipscomb (1981) found a

water-table rise of 15 to 35 cm after partial cutting

in a coastal pine forest on sandy soils. However,

Rodriguez (1981) concluded that clearcutting

a wet savanna watershed did not significantly

alter the watershed hydrology.

Harvesting under wetland conditions, such as

those encountered on wet pine flats, can alter soil

hydrologic properties (e.g., hydraulic conductivity,

macropores) by soil compaction, rutting, and

puddling (Greacen and Sands 1980). The physical

property changes affect subsurface flow and

water-table depth. Soil compaction, rutting,

and puddling become greater with increased soil

wetness, clay content, and traffic (Green and

others 1983). However, Aust and others (1995)

found that skidding altered the hydrology of

poorly and very poorly drained soils less than

it altered that of moderately well-drained or

somewhat poorly drained soils. This suggests

that lateral subsurface water movement is an

important factor in hydrologic impacts on wet

pine flats, especially for fine-textured soils.

A field-scale study on wet pine flats in South

Carolina has examined the effects of wet-weather

harvesting, dry-weather harvesting, and bedding

on hydrology and site productivity (Preston 1996,

Xu and others 2002). Two site preparation levels

(nonbed and bed) were randomly assigned to both

dry-weather and wet-weather harvested plots,

and an additional level of preparation (moleplow

plus bed) was applied only in the wet-weather

harvested plots. Dry-weather harvesting raised

the water table 14 cm, and wet-weather harvesting

raised it 21 cm. The response differences were

largest (> 10 cm) during the growing seasons

from May to October. Churning and deep rutting

affected the water table significantly in wetharvesting areas, but not in the dry-harvesting

areas. Bedding lowered water tables initially in

both areas, but the dry-harvesting site recovered

within 2 years after replanting. Bulk density,

macroporosity, and hydraulic conductivity

were significantly affected by all levels of wetharvesting disturbance. Dry-weather harvesting

Chapter 19.

Water Quantity and Quality
Southern Forest Science:

Past, Present, and Future

Water and Soils

202

also altered those soil physical properties. The

degree and extent of impacts were much greater

for wet-weather harvesting than dry-weather

harvesting (Xu and others 2002). Overall, the

study suggests that change in water-table depth

resulted from change in vegetation, and not from

soil changes caused by harvest traffic. Similar

changes in soil physical properties followed

harvesting and regeneration in a wet pine-flat

site in North Carolina, where soil macroporosity

was reduced by half within a 200-cm profile

(Blanton and others 1998).

Artificial drainage is used to increase

operability and forest productivity on poorly

drained soils in the Coastal Plain. Hydrologic

effects of ditching vary depending on soil

characteristics and the stage of vegetation

development. Campbell and Hughes (1991)

reported that free drainage in pine plantations

on pocosins lowered the water table 30 to 60 cm

during wet seasons. Standing water was

minimized, but soil saturation was maintained

and there was less fluctuation in the water table.

Drainage did not change the basic hydrologic cycle

or convert wetlands to uplands. A retrospective

study in Virginia found that ditching significantly

lowered the water table in pine plantations from

0 to 3 years old on wet flats during wet seasons

when the water table was close to the soil surface

(Andrews 1993). However, the ditching effect was

dramatically reduced during the growing season at

stand age 23. On Pomona sand in Florida, ditching

affected water-table levels up to 45 m from the

ditch (2 m deep and 3 m wide) for high and average

water-table conditions (80 cm from surface)

(Segal and others 1986). Hughes and others

(1990) reported that flow volumes and seasonal

hydrographs for a 16-year-old plantation,

unditched natural timber, fully stocked pine

plantations, a mixed plantation and naturally

regenerated watershed, and a ditched natural

stand did not differ. Simulation by the

DRAINMOD hydrologic model suggested

that ditch spacing had major effects on the

composition of runoff from forest lands but

caused limited change in total flow volume

(Skaggs and others 1991).

Many field- to watershed-scale experiments

and modeling studies have been conducted

to determine how artificial drainage affects

waterflow quantity and quality on the North

Carolina Coastal Plain and to test various

controlled drainage methods (Amatya and

Skaggs 2001; Amatya and others 1996, 2000, 2002;

Chescheir and others 2001; McCarthy and others

1991, 1992). Amatya and others (1997a) describe

the 5-year hydrology of a 340-ha drained forested

pocosin watershed in eastern North Carolina that

had heterogeneous soils and underwent changes

in vegetation in different fields during the study

period. Total annual outflows from the watershed

varied from 29 percent of the rainfall during the

driest year, when most of the trees present were

mature, to as much as 53 percent during a year

of normal rainfall after about a third of the trees

were harvested. Average annual ET, estimated

as the difference between the gross rainfall and

outflow, was 58 percent of the gross rainfall. Flow

rates per unit area were consistently higher from

a smaller harvested block (82 ha) of the watershed

than from the whole watershed, partially as a

consequence of routing effects in ditches and

canals in the whole watershed. In an ongoing large

watershed (2950 ha) study of cumulative impacts

of management practices on the North Carolina

coast, the runoff:rainfall (R:R) ratio varied from

15 to 32 percent as rainfall varied from 960 to 1410

mm. The forested watershed generally yielded no

outflows in summer, when ET demands were high,

except during periods when large tropical storms

brought the water table to the surface. Annual

ET, which was estimated as R:R, averaged 970 mm

over 5 years. Heath (1975) gave a similar annual

water-budget estimate for pocosins—1300 mm for

precipitation, 910 mm for ET, 369 mm for runoff,

and 13 mm for seepage. Accumulated data suggest

that drainage of forested wet flats and forested

pocosin wetlands has rather less impact on runoff

than might be surmised. Peak flow rates for

free-drained lands are higher than those for

nondrained or control-drained areas (Amatya

and others 1996).

WATER-QUALITY IMPACTS

I

n the United States, the best water comes from

forested watersheds (Binkley 2001, Binkley and

Brown 1993), even when forests are managed

primarily for timber production (Binkley and

others 1999). Many forest management practices,

including timber harvesting, site preparation,

prescribed burning, and the application of

chemicals (insecticides and fertilizers), have the

potential to degrade water quality. The impacts

of forest management on water quality in the

Southern United States have been summarized

in review papers by Riekerk and others (1989a),

Shepard (1994), Walbridge and Lockaby (1994),

Lockaby and others (1997a), Lockaby and others

(1999), and most recently by Fulton and West
203

(2002). Effects of forest management on the

water quality in upland and wetland landscapes

are discussed separately.

Water-Quality Impacts: Uplands

Riekerk and others (1989) synthesized findings

of studies of silvicultural nonpoint-source pollution

in uplands of the South. They noted that sediment

production during silvicultural operations was

low in the mountains and lower Coastal Plains,

but high in the Piedmont and upper Coastal

Plains. Nutrient export in the Piedmont and

upper Coastal Plains was elevated, and rates

of nutrient export were controlled by the degree

of soil disturbance and the recovery rate of

the vegetation. Nutrient exports in the lower

Coastal Plains were not much affected by

silvicultural operations.

Harvesting Impacts on Streamwater

Chemistry—Change of streamwater chemistry

is one important signature of ecosystem response

to watershed disturbance. The impacts of forest

harvesting on water chemistry and nutrient export

were reported in a number of papers based on

studies conducted at Coweeta (Douglass and

Swank 1975, Johnson and Swank 1973, Swank and

Swank 1981, Swank and Vose 1994, Swank and

others 2001).

Johnson and Swank (1973) analyzed longterm water-chemistry responses for calcium (Ca),

magnesium (Mg), potassium (K), and sodium (Na).

They found that clearcutting treatments did not

cause substantial losses of Ca, Mg, K, and Na over

the duration of experimental record.

Converting hardwoods to white pine at Coweeta

not only reduced water yield but also altered

streamwater quality (Swank and Vose 1994).

During the 20 years following initial treatment,

streamwater solutes in the pine watersheds and

the mixed hardwood control watersheds were

generally similar. However, flow weighted mean

nitrate-N (NO3

-N) concentrations increased

slightly, 0.1 mg/L, while sulphate ion (SO4

2-)

concentrations increased nearly threefold. Johnson

and Swank (1973) reported that reductions in the

losses of Ca, Mg, K, and Na were 2.3, 1.7, 4.4, and

1.2 kg/ha/year, averaged over both watersheds;

and Swank and Vose (1994) reported that the rates

of reduction were unchanged 20 years later.

Swank and others (2001) contrasted the

long-term water-chemistry records of a grazing

and clearcut watershed with those of a control

watershed. Increases in nutrient export occurred

following harvesting with the largest, though

relatively small, losses—1.3 kg/ha NO3

-N, 2.4 kg/

haK, 2.7 kg/ha Na, 3.2 kg/ha Ca, 1.4 kg/ha Mg, 0.4

kg/ha sulphur and 2.1 kg/ha chlorine—occurring

during the third year following treatment. Export

increases were frequently lower than background

rates of atmospheric deposition. As in other

studies, the nutrient losses returned to baseline

levels within a few years after treatment.

However, a second phase of increased NO3-N

losses started 14 years after treatment, and this

effect had not been observed in other studies.

It was hypothesized that mortality and shifts

in species composition, nutrient releases from

decomposition, elevated soil nitrogen (N)

transformation, and reductions in soil carbon

(C):N ratio could have contributed to the elevated

NO3

-N export.

Harvesting Impacts on Sediment—Long-term

effects of forest road construction and harvesting

on watershed sediment loading were studied at

Coweeta (Swank and others 2001). Prior to

construction of a forest access road (~3 km)

and cutting, sediment yield averaged 0.23 metric

ton/ha/year while that from a control watershed

averaged 0.1 metric ton/ha/year. Most of the

logging was completed with a cable yarding

system; tractor skidding was restricted to a 9-ha

area where slopes were under 20 percent. Road

construction and harvesting resulted in significant

increases in water yield and soil loss. Over the

period of monitoring, the rate of soil loss increased

by a factor of 3.5. The majority of the measured

sediment resulted from road erosion. The average

sediment yield was about 340 metric tons/ha/year

or 50 percent above the pretreatment level at the

end of this 15-year experiment (fig. 19.4).

Harvesting trees without disturbing the

soil generally did not increase sediment levels

in runoff in the South, but mechanical site

preparation with shearing and windrowing of

debris generated significant sediment pollution

(Ursic 1986). However, this was not the case in

a study that compared the hydrologic responses

to clearcutting with skidders and logging with a

cable yard on a hilly upland site in the southern

Coastal Plain in north Mississippi (Ursic 1991b).

In the latter study, skidder harvesting increased

sediment slightly (by 0.12 metric ton/ha/year),

while cable harvesting increased sediment sixfold

(3.3 metric tons/ha/year) over the first 5 years.

Subsurface flow was critical in elevated channel

erosion and deposition in forested landscapes on

unconsolidated formations in the Coastal Plain

Chapter 19.

Water Quantity and Quality
Southern Forest Science:

Past, Present, and Future

Water and Soils

204 600

500

400

300

200

100

0

1975 1977 1979 1981 1983 1985 1987 1989

(B)

Cumulative sediment yield

(metric tons)

April July Nov April July Nov April July Nov

80

60

40

20

0

Cumulative sediment yield

(metric tons)

Logging activities

Two major storm events

Road construction

(A)

Predicted

Measured

1976 1978 1977

(Ursic 1991b). Another study, which employed

16 small mature loblolly pine (P. taeda L.)

plantation watersheds on the upper Coastal Plain

in Tennessee, also indicated the importance of

channel erosion on sediment loading (Ursic 1991a).

This study suggested that harvesting of trees

growing on previously degraded lands had limited

effects (< 0.093-metric ton/ha/year increase) on

sediment loading, usually within 4 years.

Mechanical disturbance of the forest floor

during harvesting and site preparation is generally

supposed to reduce soil productivity and increase

soil erosion. One might expect that soil structure

and site hydrology would be affected by increased

disturbance intensity. However, a recent study

at a Piedmont site in Alabama found that surface

runoff was lower at a clearcut and bedded site than

it was at a site that was clearcut but not bedded

(Grace and Carter 2001). Bedding produced

additional surface roughness and storage.

Although this was a small-scale study, it

demonstrated the uncertainty of hydrologic

responses to current silvicultural practices.

Scoles and others (1994) described a 15-year

study of hydrology and water quality on gauged

watersheds in the Ouachita Mountains of Arkansas

and Oklahoma. They noted threefold-to-twentyfold

increases in soil erosion following selection

harvesting and clearcutting. However, the amount

was still low, about one-thirtieth of the loss from

cropland, and recovery to baseline conditions

occurred in the first 5 years of the 35-year

rotation. Most erosion occurred during a few large

storms each year, and 90 percent of annual stream

sediment came from roads. Projected sediment

delivery to streams in the Ouachitas as a result

of harvesting, site preparation, and erosion from

roads was about 0.16 metric ton/ha/year.

Lawson (1985) reported that sediment losses

in undisturbed pine forests in the Ouachita

Mountains, Ozark Plateaus, and Boston Mountains

averaged < 0.02 metric ton/ha/year. Maximum

sediment losses of 0.13 metric ton/ha/year were

observed during the first year following clearcut

timber harvesting. Recovery to preharvest levels

of sediment production occurred within 3 years.

Harvesting Impacts on Stream Temperatures—

Forest harvesting along streams usually results

in increased stream temperatures (Swift 1973,

1982; Wooldridge and Stern 1979). Swift and

Messer (1971) monitored stream temperatures

in treatment and control watersheds. On the

watersheds that were harvested completely,

summer stream temperatures increased from

an average of 19 o

C to more than 23 oC. The most

intensive treatments raised temperatures by

more than 7 oC. Water temperatures in streams

with uncut streamside or riparian vegetation

did not increase. Also, temperatures in the

impacted streams returned to pretreatment

levels when regeneration of riparian vegetation

provided shading. The temperature increases

significantly altered streamwater quality, in that

water temperatures were raised above levels

suitable for the native trout populations (Swift

and Messer 1971).

Swift (1973) investigated the effectiveness of

preserving a 12-m buffer of streamside vegetation

in mitigating potential streamwater temperature

impacts of forest harvesting on a small, mountain

watershed. The stream flowed through alternating

cut and uncut riparian zones. Water temperature

rapidly increased by up to 6 oC as the stream

flowed through a 900-m cut area. It then decreased

by approximately 1 oC as the stream flowed

through an 800-m uncut riparian area, and

increased again as it passed through a 200-m

Figure 19.4—Cumulative sediment yield measured at

one Appalachian watershed at Coweeta Hydrologic

Laboratory (A) in one of the first-order streams

below a logging road during the first 32 months

after treatment, and (B) in the ponding basin of the

second-order stream (Swank and others 2001).
205

cut area. The stream’s temperature eventually

stabilized to normal (12.8 oC) when the stream

passed through two forested sections of a total

of 2100 m. The alternating network of cut and

uncut riparian areas limited maximum water

temperatures to < 20 oC, a temperature above

which trout habitat is impaired.

Swift (1982) reported long-term impacts

of cable logging on streamwater temperatures.

In the first 2 years following cable logging,

average summer streamwater (38 percent shaded)

temperatures increased 3.3 oC. Regeneration of

streamside trees by stump and root sprouting

increased streamside leaf biomass to 78 percent

of the pretreatment condition within 3 years

following treatment. Subsequent temperature

increases averaged 1.2 oC. Minimum temperatures

were elevated only in the first year of treatment,

whereas daily temperature range (maximum –

minimum) was elevated during the 5 years of the

study. Swift (1982) predicted that the increase

in streamwater temperature would decrease at

a rate of 0.3 oC per year, and that streamwater

temperature would ultimately return to

pretreatment levels.

Harvesting Impacts on Biota—Williams and

others (2002) investigated the effects of timber

harvesting on physical stream features and

regional fish and macroinvertebrate assemblages

during a 3-year period in six hydrologically

variable streams (basin area 1517 to 3428 ha)

in the Ouachita Mountains, AR. Most of the

variations in fish assemblages were explained by

drainage basin differences, and both basin and

year-of-sampling influenced macroinvertebrate

assemblages. Williams and others (2002) argue

that the lack of logging effects on biota may

be due to the scale of the study, timing of the

sampling, and high levels of natural variability

in the streams.

Forest conversions—The conversion of cove

hardwood to mountain grazing at Coweeta

resulted in decreased water quality. Peak

concentrations of sediment during stormflow

events were up to three times higher than

expected as the clay fraction of the suspended

load significantly increased beyond pretreatment

conditions (Johnson 1952).

Converting hardwoods to blue fescue grass

at Coweeta (see water-quantity sections also)

required spot applications of herbicides to

suppress competition. Erosion of the stream

channel margin occurred after the first herbicide

application. When herbicides were applied

a second time, a 10-foot buffer of grass along

the channel was left unsprayed. Atrazine was

detected in the streamwater following storm

events for 4 months after the herbicide

treatments. The largest concentration of atrazine,

ranging from 24 to 34 parts per billion, occurred

immediately after application. Following the

second treatment, a sustained, background

concentration (4 parts per billion) of atrazine

existed in the streamwater for 3 months. No

detectable atrazine was found 3 months after

the last application (Douglass and others 1969).

Forest road construction—Much of the road

research at Coweeta was conducted in conjunction

with forest harvesting experiments and was

designed to identify methods that would reduce

sedimentation from access roads for timber

harvesting operations. A comprehensive summary

of these experiments and their results is given

by Swift (1988) and Swift and Burns (1999).

Hursh (1935, 1939, 1942) reported that soil loss

from forest roads could be reduced significantly

by mulching or vegetating the adjacent cut-andfill slopes. Several best construction methods

employing bioengineering techniques to stabilize

slopes were identified. Use of these methods

significantly reduced sedimentation following

road construction.

As a part of research on exploitive logging at

Coweeta, loggers were allowed to construct roads

in a typical fashion. This included the construction

of skid trails directly upslope, from roads, and

adjacent to and within streams (Swift 1985). These

practices resulted in the loss of 408 m3

 of soil/km

of road constructed (Lieberman and Hoover

1948b). Sediment delivery to streams was high,

and turbidity peaked at 5700 parts per million

(Lieberman and Hoover 1948a), significantly

reducing downstream aquatic fauna (Tebo 1955).

Road erosion became so severe that the roads had

to be closed and stabilized. It was concluded that

the sedimentation observed in the stream resulted

almost exclusively from road erosion and not from

other forest harvesting activities (Swift 1988).

Swift (1988) found that soil loss potentials

were highest immediately after road construction

at Coweeta. The pulses of soil loss after road

construction were triggered by intense rainfall

events. Soil losses from bare roadbeds were eight

times those from graveled roadways. The erosion

rates declined in the ensuing 6 months; however,

losses from the bare soil were still six times

Chapter 19.

Water Quantity and Quality
Southern Forest Science:

Past, Present, and Future

Water and Soils

206

greater than those from the gravel treatments.

The largest losses were from roads that received

frequent traffic. When logging trucks were

present, losses of soil from roads surfaced with

thin layers of rock were similar to those from

bare-soil roads. Surfacing with large (20 cm)

crushed stones afforded the most protection

against erosion; however, this stone was deemed

too coarse for many vehicular operations. Medium

(15 cm) crushed rock provided roadbed protection

similar to that obtained with the 20-cm stone but

at a significantly reduced cost. Rates of erosion

from roadbeds of fine (5 cm) crushed rock were

similar to those for bare-soil roads. Seeding of the

roadbeds and cut-and-fill slopes of lightly traveled

roads reduced erosion rates to 50 percent of those

for bare-soil conditions (Swift 1984a).

Swift (1984b) monitored rates of erosion from

roadbeds, cut slopes, and fill slopes along a series

of road treatments (Swift 1984a). Although soil

losses from all surfaces were high during heavy

rains, rates of erosion from bare cut-and-fill slopes

that made up half of the road prism accounted for

70 to 80 percent of the total soil losses from the

sites. Graveling of the roadbed reduced soil losses

to < 20 percent of those for the bare-soil condition.

A combined treatment that consisted of vegetating

the cut-and-fill slopes and graveling the roadbeds

reduced total erosion rates to < 10 percent of

those for the pretreatment condition. Despite

these improvements, the net loss of soil from the

entire roadway was 20 times greater than that

estimated for undisturbed forest (Swift 1984b).

Fertilization—Binkley and others (1999) and

National Council for Air and Stream Improvement

(1999d) reviewed world literature about response

of streamwater chemistry to forest fertilization in

upland and wetland forest ecosystems. They found

that forest fertilization usually results in elevated

N and phosphorus (P) concentrations, especially

if pellets are deposited directly into streams and

ditches. However, maximum concentrations

of N were rarely above drinking water-quality

standards, and elevated concentrations were

short-lived (weeks to months). Elevated

concentrations were typically one-tenth of

those observed in agriculture. Highest N

concentrations were observed with repeated

applications, and when ammonium nitrate rather

than urea was used. No evidence of effects on

aquatic organisms was found, but few studies

included such an assessment.

In the South, it is common to fertilize with N

and P to increase tree growth. In a study on the

North Carolina Coastal Plain, fertilization resulted

in elevated concentrations of ammonium as much

as 3.8 mg/L, total N as much as 9.3 mg/L, total

phosphate (PO4

-P) as much as 0.18 mg/L,

orthophosphate as much as 0.1 mg/L, and urea as

much as 1.2 mg/L measured at the field (27 ha)

edges (Campbell 1989). After 3 weeks of

treatment, concentrations of all ions returned to

pretreatment levels. Concentration of NO3-N

ranged from 0 to 1.2 mg/L during the 60-day

monitoring period. Segal and others (1986) and

Riekerk (1989b) reported similar findings for

studies in the Coastal Plain. Information about

effects of fertilization on water quality in other

physiographic regions can be found in National

Council for Air and Stream Improvement (1999d).

Fertilization of forest lands has rarely caused NO3-

N concentration in streams to exceed the U.S.

Environmental Protection Agency (EPA) drinking

water standard of 10 mg/L, especially when care

has been taken in applying the fertilizer.

Prescribed Fires—In the Southern United States,

about 1 million ha of forest land is subjected to

prescribed burning annually to reduce fuel loads,

enhance stand health, and release preferred forest

species from competition (Clinton and others 2000,

Richter and others 1982, Vose and Swank 1993).

The negative impacts of this practice on forest

communities include reduction of total ecosystem

N as a result of volatilization and leaching (Knoepp

and Swank 1993) and a potential increase of

sediment loading (Knoepp and Swank 1993, Vose

and others 1999). The magnitude of effects of this

practice varies greatly and depends on fuels, soil

properties, topography, climate, weather, and fire

frequency and intensity (Richter and others 1982).

Ursic (1969) described effects of prescribed

burning on hydrology and water quality in

two abandoned fields in Mississippi. Stormflow

during the first year increased 48 percent in

one catchment, and stormflow increased in the

second and third years also. Treatment of the

second catchment, which had a fragipan, did not

change the volume of stormflow but significantly

increased peak discharges and overland flow.

During the first year, sediment production

increased from 0.11 to 1.9 metric tons/ha in

the first catchment and 7.5 metric tons/ha

in the other. Sediment production dropped

to < 0.56 metric ton/ha the third year.
207

Douglas and Van Lear (1983) reported

responses of nutrient and sediment export to

prescribed burning at a Piedmont site in the

Clemson Experimental Forest, SC. Four loblolly

pine watersheds were burned twice at 18-month

intervals. The first burn took place in March and

the second in September. The prescribed burns

did not change water quality of the streams.

Clinton and others (2000) summarized the

results of four experiments that examined stream

nitrate (NO3-N) responses to forest fires in the

Nantahala National Forest in western North

Carolina. A fell-and-burn fire (Jacob’s Branch)

and two stand-replacement fires (Wine Spring

Creek and Hickory Branch) were implemented

to improve degraded xeric oak (Quercus spp.)-pine

forests. The fourth (Joyce Kilmer) fire was an

arson-related wildfire, burning the understory in

an old-growth mesic and xeric forest. The Jacob’s

Branch and Joyce Kilmer fires occurred in the fall,

and the fires on Wine Spring Creek and Hickory

Branch were spring burns. Stream nitrate was

elevated by 0.03 mg/L for 8 months following

the burn on Jacob’s Branch and by 0.06 mg/L

for 6 weeks following the Joyce Kilmer fire. There

was no stream NO3-N response at the two spring

burn sites. Clinton and others surmised that N

released during the spring burns was immobilized

by vegetation uptake, but that N released during

the fall burns was not.

Neary and Currier (1982) monitored stream

chemistry [NO3-N, ammonium nitrogen (NH4-N),

PO4-P, Na, K, Ca, and Mg] and total suspended

solids for five streams burned by wildfire in

the Blue Ridge Mountains of South Carolina.

Increases in streamwater nitrate, NO3-N,

were attributed to fertilizer applications.

Elevated concentrations of NO3-N and PO4-P

in streamwater occurred mostly during

stormflow events, and mean concentrations

were not significantly higher than those observed

on undisturbed watersheds. Concentrations of

anions Na, K, Ca, and Mg ranged from 12 to 82

percent above background levels during the

monitoring period.

Forest fires can burn significant amounts of

the understory canopy, litter, and duff layers of

forests, leaving forest soils unprotected against

raindrop impact. The combustion of forest litter

and plants in high-intensity forest fires can create

and concentrate petroleum-based compounds

that induce water repellency in forest soils.

This reduces infiltration and increases runoff

and soil erosion, especially in the forests of the

Western United States (Tiedemann and others

1979, Wolgemuth 2001, Wright and Bailey 1982).

However, Wolgemuth (2001) found that forests

treated with prescribed fires had erosion rates

lower than unburned forests had during

subsequent fire events on chaparral watersheds

in southern California.

The literature suggests that fire generally has

less effect on sediment loading in the Southern

United States than it has in the Western United

States (Goebell and others 1967, Marion and Ursic

1992, Shahlee and others 1991, Swift and others

1993, Van Lear and Danielovich 1988, Van Lear

and Waldrop 1986). Increased soil erosion

following fires is frequently associated with

forest floor disturbances caused by mechanical

site preparation during fire controlling activities.

Similarly, operationally disturbed sites and

especially skid trails have been found to be more

susceptible to erosion following fires (Ursic 1970,

Van Lear and others 1985). However, it must be

noted that most fire research in the Southern

Appalachians has involved fires of low-to-moderate

intensity (Swift and others 1993, Van Lear and

Waldrop 1989).

Pesticides—Pesticides have been increasingly

used in the South to control insects and unwanted

vegetation. These organic substances have

the potential to pollute water by aerial drift,

decomposition, leaching and adsorption, and

transport by subsurface flows. Substantial effort

has been made to discover the fate of applied

forestry pesticides (Michael and Neary 1990;

Neary 1983; Neary and Michael 1996; Neary and

others 1985, 1993; U.S. Department of Agriculture,

Forest Service 1994). The literature suggests that

the risk of long-term contamination from pesticide

application is low when care is taken. Residues

are not persistent and do not bioaccumulate.

When herbicides are not applied directly to

streams or when buffer strips are used, peak

residue concentrations are generally low (< 500

parts per billion), and residue levels in surface

runoff are < 36 parts per billion for ground

application and < 130 parts per billion for aerial

applications (Riekerk and others 1989). Most

herbicides used in modern silviculture are of

low toxicity to aquatic and terrestrial organisms,

and thus pose little hazard to wildlife.

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208

Insect outbreaks—Insect defoliation was

responsible for the increased stream nitrate

concentration in several watersheds at Coweeta

(Swank and others 1981). For example, a sudden

rise of nitrate concentrations from 0.5 to 0.75 mg/L

in one watershed was caused by a widespread

outbreak of the locust stem borer (Ecdytolopha

insiticiana Zeller) in black locust (Robinia

pseudoacacia L.) (Swank and Crossley 1988).

Cumulative effects—Multiple forest operations

that may or may not be separated in space and

time can have cumulative effects on water quality.

Bolstad and Swank (1997) analyzed the cumulative

effects of land use practices separated in both

space and time along the Coweeta Creek in the

Appalachians. They found that water quality

degraded from the creek’s headwaters to the

watershed mouth. The water quality at the

confluence of two forested subwatersheds was

very good. However, averaged stormflow turbidity,

conductance, NO3

-N, NH4-N, temperature, total

coliform, fecal coliform, and streptococci counts

increased by factors ranging from three (turbidity)

to eight (total coliform) as the stream flowed

through the residential and agricultural lands to

its mouth. The increases in these water-quality

parameters were strongly and positively

correlated with numerous measures of human

impacts including percent nonforest land, paved

road density, paved road length, building

frequency, and building density.

Water-Quality Impacts: Wetlands

Studies of the effects of forest management

on wetland forest water quality and geochemical

balances in the Southern United States are

summarized in Shepard (1994), Walbridge and

Lockaby (1994), Lockaby and others (1997a), and

Lockaby and others (1999). Major findings from

these papers and other recent publications are

discussed below by type of management practices.

Drainage—Drainage usually does not alter

water quality greatly. Williams and Askew (1988)

reported a small increase in suspended sediments

from newly built ditches at a pocosin site in South

Carolina and concluded that establishment of pine

plantations did not have to harm water quality.

Lebo and Herrmann (1998) found that harvesting

of loblolly pine plantations increased outflow and

slightly increased nutrient concentrations. For a 3-

year period after harvesting, increases in annual

outflow, N export, and P export were 111 to 164

mm, 2.1 to 2.2 kg N/ha/year, and 0.12 to 0.36 kg P/

ha/year, respectively, compared with baseline

levels. The baseline values for total N and P

loading ranged from 2.7 to 3.4 kg N/ha/year and

0.09 to 0.29 kg P/ha/year, respectively. Outflow

and nutrient concentrations returned to baseline

levels within 2 to 3 years. These relatively small

temporary increases in annual nutrient exports

associated with harvesting and site preparation

can be considered in the context of 30- to 50-year

rotations for loblolly pine in coastal North

Carolina. On that basis, they represent an

increase of 4 to 7 percent above baseline levels.

In a large drained watershed (2950 ha) with

mixed land uses in eastern North Carolina, ranges

of measured total N concentrations at the field

edges were 0.5 to 15 mg/L for the organic soils and

0.3 to 5.0 mg/L for the mineral soils. The annual

total N loading varied from about 4.8 kg/ha to as

much as 26.6 kg/ha, with an average of 14 kg/ha.

Most of the total N was in organic form. It

appears that the variation in nutrient loading

attributable only to soil can be as great as that

caused by forest harvesting.

Harvesting—In wetands, forest harvesting

followed by site preparation activities has the

potential to disturb the surface soils, alter surface

and subsurface flow paths, increase water yield,

and accelerate nutrient cycling rates, and thus

affect onsite and offsite water quality. Riekerk

(1985) found that clearcutting a pine-cypress

flatwoods resulted in significant increases in pH,

suspended sediment, and total N, K, and Ca

during the first year after harvest. Fisher (1981)

described the effects of clearcutting and site

preparation on the hydrology and water quality

of a pine flatwoods site in western Florida. Runoff

volume was increased during the first year, but by

the second year most water-quality parameters

had returned to near background levels. The

impact of silvicultural operations was less on

the level, sandy site than in areas having more

relief and shallow soils (Fisher 1981).

There are over 12 million ha of bottomland

hardwoods forest in the Southern United States.

A series of harvesting experiments have been

conducted to examine their ecological responses

to timber harvesting (Aust and others 1991,

1997; Lockby and others 1994, 1997b; Messina

and others 1997; Wang 1996). These experiments

indicate that onsite effects of harvesting flood

plain forests are minor because the site

disturbance is not great, because water movement

is slow and because harvesting causes an increase

in surface roughness for sediment and nutrient
209

retention (Aust and others 1991, Rapp and others

2001). The treatment effects in these studies

were often overwritten by seasonal flooding

events (Perison 1997).

Prescribed fires—Controlled burning in the

Atlantic and Gulf Coastal Plain reduces the risk of

wildfire, controls certain tree pathogens, improves

wildlife habitat, and restores desired ecosystems.

For these reasons, the use of controlled burning

is very common. However, few data are available

on the effects of this management tool on the

hydrology and water quality of wetlands. One

exception is a 3-year paired watershed study

conducted at the Santee Experimental Forest in

eastern South Carolina (Richter and others 1982,

1983). The treatment and control watersheds were

about 160 and 200 ha in area, respectively, and had

first-order perennial streams. Dominant soils were

Aquults (high water table), and the watersheds

were covered by natural stands of loblolly pine.

Burns prescribed for twenty 7.1-ha compartments

were administered during winters and summers.

It was concluded that periodic prescribed fires in

these southeastern Coastal Plain pine forests are

not likely to have great impacts on onsite or offsite

water quality (Richter and others 1982).

WATER QUALITY REGULATIONS,

AND DESIGN AND EFFECTIVENESS OF

FORESTRY BMPS

Federal and State Water-Quality Programs

T

here are many Federal and State programs

designed to protect water quality. The first

Federal water-quality regulation applicable

to forestry was included in the 1972 amendments

to the Federal Water Pollution Control Act

(commonly known as the Clean Water Act). This

statute introduced two new concepts in Federal

water-quality protection. First, its Section 208

required States to prepare area-wide (watershed

or regional) waste treatment management plans;

and second, it separated water pollution into

two categories: pollution for point and nonpoint

sources (Ice and others 1997).

Initially, the Clean Water Act was interpreted

as requiring States to prepare water-quality

management plans only for waters the States

identified as impaired. However, the successful

lawsuit NRCD vs. Train (1975) resulted in EPA

requiring area-wide programs statewide, not just

for areas with water pollution problems. In the

regulations developed following NRCD vs. Train,

EPA specified that States may develop nonpointsource control programs that prescribe

“Best Management Practices” (Rey 1977).

The EPA defined BMPs as

 . . . a practice or combination of practices,

that are determined by a state, or

designated area-wide planning agency,

after problem assessment, examination

of alternative practices, and appropriate

public participation, to be the most

effective, practicable (including

technological, economic, and institutional

considerations) means of preventing

or reducing the amount of pollution

generated by nonpoint sources to a level

compatible with water quality goals . . .

(Ice and others 1997).

Oregon was the only State that had a

silvicultural nonpoint-source control program

prior to 1972 (National Council for Air and

Stream Improvement 1999c). Florida and South

Carolina were among the first States to develop

BMPs; South Carolina published its first waterquality guidelines in 1976, and Florida began

developing its BMPs in 1976 (Greis 1979). The

1987 amendments to the Clean Water Act created

Section 319, which required States to develop and

implement programs to control nonpoint-source

pollution. This amendment stimulated States to

accelerate their efforts to develop silvicultural

BMPs, and many State programs began shortly

after 1987.

Total Maximum Daily Loads

Section 303(d) of the Clean Water Act requires

that States list waters that do not meet waterquality standards or that do not meet their

designated uses because of a particular pollutant

such as sediment, pathogens, nutrients, or

temperature. States must then develop a total

maximum daily load (TMDL) for each pollutant

causing impairment, specifically for each water

body. A TMDL is the maximum amount of a

pollutant that a water body can receive and still

meet water-quality standards and an allocation

of that amount among the pollutant’s sources.

It can be expressed as follows:

TMDL = Σ waste load allocation

+ Σ load allocation + margin of safety

Waste load allocations are point sources of

the pollutant, and load allocations are nonpoint

sources, including natural background levels

of pollutants such as sediment, nutrients, and

temperature. Although TMDLs were included

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210

in the 1972 Clean Water Act, it was not until the

late 1980s that lawsuits forced the EPA and States

to begin implementing the program. Hundreds

and sometimes thousands of water bodies were

listed in States. The total number listed in 2001

was over 40,000 (National Research Council 2001).

States are being required by court orders or by

EPA guidance to develop these TMDLs within 8 to

13 years, but the amount of effort required dwarfs

the budgets of State water-quality agencies.

Meeting these deadlines has become “. . . the most

pressing and significant regulatory water quality

challenge for the states since passage of the Clean

Water Act . . .” (National Research Council 2001).

Routine forest management has not yet

been affected by TMDL regulations. The

EPA is currently operating under regulations

promulgated in 1992, but revision of those

regulations is pending. Current EPA policy

recommends that States with approved forestry

BMP programs grant exemptions to enforceable

water-quality standards to forestry operators

who implement BMPs (Anon. 2000).

Federal Wetlands Regulations

Section 404 of the Clean Water Act regulates

the discharge of dredged and fill material into

“waters of the United States,” which include

wetlands adjacent to navigable waters, interstate

wetlands, and isolated intrastate wetlands that

could affect interstate or foreign commerce

(Guzy and Anderson 2001). The U.S. Army

Corps of Engineers (Corps) administers the

Section 404 program, and the EPA is responsible

for policymaking and oversight of the Corps’

management of the program. Those who conduct

activities that will result in the deposition of more

than a de minimis (threshold) amount of dredge

and fill material in wetlands must apply for a

permit from the Corps. Normal farming,

silvicultural and ranching activities such as

plowing, seeding, cultivating, minor drainage,

and harvesting for the production of food, fiber,

and forest products are exempted from this

regulation when they are part of established

operations (33 CFR 323.4). Other activities

exempt from the permit program are minor

drainage (that does not convert the site to upland),

maintenance of existing ditches, and building

of forest roads (subject to 15 BMPs).

In 1995, the EPA and Corps released to the

field a memorandum about “Application of Best

Management Practices to Mechanical Silvicultural

Site Preparation Activities for the Establishment

of Pine Plantations in the Southeast.” This

memorandum specified that a permit would

be required for mechanical site preparation

to establish pine on wetlands supporting

riverine bottomland hardwoods, white-cedar

[Chamaecyparis thyoides (L.) B.S.P.] swamps,

Carolina bays, low pocosins, and wet marl forests.

It also specified that other wetlands would

continue to be exempt from permitting as long

as six new BMPs were employed (Anon. 1996).

A more comprehensive description of wetlands

forestry regulations is found in Gaddis and

Cubbage (1998). A comprehensive treatment

of the entire Federal wetlands regulatory

program, and a discussion of litigation history,

is provided by Want (1998).

Design of BMPs

Generally, BMPs designed to protect water

quality fall into four categories: (1) those related

to riparian areas, (2) those related to disturbed

areas such as roads and landings, (3) those related

to wetlands, and (4) those related to harvesting

practices. In most Southeastern States, BMPs

are voluntary. In Virginia, however, loggers or

landowners must notify the State Forester at

the start of an activity, and the State Forester

can mandate corrective actions when a threat

to water quality is identified.

High BMP compliance rates are in the interest

of the forest industry because the EPA currently

accepts BMPs as appropriate and sufficient

mitigation to meet the requirements of the

TMDL program. If rates of BMP compliance

are not high, water-quality regulations may be

imposed. Another reason for employing BMPs

is the threat and reality of citizen lawsuits.

If runoff from a forestry operation causes waterquality problems for a downstream landowner,

the downstream landowner can sue for damages.

In such cases, the operator’s compliance with

BMPs is always a major issue.

Most nonpoint-source pollution caused by

silvicultural activities starts with exposure of bare

soil and soil disturbance. When raindrops strike

the ground, they detach and disperse soil particles.

Raindrops also compact surface soil, and this

compaction promotes overland flow that mobilizes

sediment and transports it to the stream system.

If fertilizers or pesticides have been applied to the

ground surface recently, then overland flow also

transports these chemicals to streams. Therefore,

most BMPs are designed to minimize the amount

and duration of bare soil and the hydraulic

connectivity of runoff from bare-soil areas

to streams.
211

The development of silvicultural BMPs over

the last 20 years has been based on forestry

research and basic principles of stream ecology.

Logger and forester experience, common sense,

and political negotiation have also factored into the

development of BMPs. Because soils, topography,

climate, and political environments vary from

State to State, the States have issued different

BMP prescriptions.

Riparian Areas

The term riparian area refers to a channeladjacent terrestrial area in which the presence

of the stream and high water tables are primary

influences on vegetation and soil development. In

turn, the vegetation affects channel conditions by

altering the microclimate and providing organic

inputs to the stream system. Most BMP guidelines

call for maintaining natural conditions in a portion

of the riparian areas adjacent to channel systems

to protect streamwater quality from potential

effects of upland management practices. These

riparian protection areas are described as riparian

zones, riparian management zones, buffers, filter

strips, and streamside management zones (SMZs)

in the BMP guidelines defined by different States

(Stringer and Thompson 2000). Riparian buffers

protect water quality by (a) stabilization of

stream banks, (b) filtration of overland flow and

adsorption of chemicals transported in overland

flow, (c) denitrification of shallow ground water,

and (d) maintenance of shade and organic debris

recruitment for channels.

Stringer and Thompson have published a

review of State guidelines on riparian zones.

Their findings are summarized: Most States in

the Southeast now specify (a) minimum allowable

distance between water bodies and the nearest

severe disturbance, e.g., roads or landings; and

(b) the allowable harvest within the riparian area

(Stringer and Thompson 2000). In most States, the

allowable distance between severe disturbance and

perennial water bodies (perennial streams and

lakes) increases as upland slope increases. This

is because the potential for surface runoff impacts

is greater with higher upland grades (Trimble and

Sartz 1957). Most States allow 25 to 50 percent

removal of the overstory within the perennial

riparian area (Stringer and Thompson 2000).

Generally, BMPs for intermittent streams are less

restrictive as they are considered to have less

potential nonpoint-source pollution impact than

perennial streams. In the Southeast, about onehalf of the States set a specific minimum distance

to the nearest disturbance, and about one-half

relate the distance to upland grade; however, these

allowable distances are generally narrower

than those for perennial water bodies. Allowable

harvest generally ranges from 75 to 100 percent

canopy removal. The effects of headwater area

forestry operations on water quality are poorly

understood. Most State BMPs do not explicitly

recommend SMZs for ephemeral streams. Most

States in the northern part of the Southeast also

have guidelines for forestry practices in areas near

coldwater streams that support trout. Generally,

BMPs for areas adjacent to coldwater streams are

more restrictive than those for areas adjacent to

perennial streams in terms of buffer width and

overstory removal within buffers.

Roads

Because logging roads create permanent areas

of bare and compacted soil, they are the principal

contributor of sediment from forestry activities

(Swank and others 2001). Road and landing

position in the landscape, the soil type and geology

present, and method of retirement ultimately

determine the magnitude of sediment flux to the

stream (Ketcheson and others 1999, Swift 1988).

Impacts of road runoff and sediment can be

reduced greatly by reducing or eliminating the

hydraulic connectivity of roads to streams. This

is done by routing water off roads at regular

intervals onto hillslope locations where flow can

be dispersed and reinfiltrated. Water bars, broadbased dips, and cross-drains are typical methods

by which road runoff is routed from roads onto

hillslopes (Cook and Hewlett 1979, Swift 1988).

Depending on slopes and native soils, surfacing

roads with gravel or rock can also reduce surface

erosion. A review of specific State guidelines

for BMPs related to roads and skid trails can

be found in Stringer and Thompson (2001).

The use of filter strips along roads also

mitigates the propagation of road sediment

through drainage networks and into streams.

While filter strips normally include natural

vegetation, their performance may be augmented

by using trees and woody slash material to form

brush barriers. Use of such materials reduced

distance of sediment movement by approximately

40 to 50 percent (Swift 1986). Natural forest litter

was also instrumental in inhibiting transport

at burned sites. Grass-covered sites on which

runoff was diverted through forest litter and

brush barriers provided the most resistance to

flow. Swift (1986) observed the distances traveled

by sediment from forest roads. He recommends

that the width of forest road buffers be designed

on the basis of land slope and the use or nonuse

of brush barriers.

Chapter 19.

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212

Grace (2000) studied the effectiveness of three

common treatments for controlling erosion from

cut-and-fill slopes of roads in the Talladega

National Forest, AL. The three treatments were

(1) native species vegetation mix, (2) nonnative

species vegetation mix, and (3) nonnative species

vegetation mix anchored with an erosion-control

mat. Surface runoff and sediment yield were

significantly reduced on both the cut-and-fill

slopes. The three control measures reduced

sediment production by 60 to 90 percent. The

erosion-control mat treatment was the most

effective of the three.

Clinton and Vose (2002) evaluated the

effectiveness of road paving in reducing the

delivery and transport of sediment from mountain

forest roads. Delivery and transport of sediment

were measured for four surface types: (1) 2-yearold pavement, (2) improved gravel, (3) improved

gravel with sediment control, and (4) unimproved

gravel. The paved road system generated the least

sediment while the unimproved road generated the

most. The distance of sediment transport away

from the roadbed was greater for the paved road

surface and decreased progressively for improved

gravel, improved gravel with sediment control, and

unimproved surfaces.

Appelboom and others (2002) evaluated the

effectiveness of four road management practices

(continuous roadside berms, noncontinuous

roadside berms, a graveled road surface, and a

nongraveled road surface) in reducing sediment

loading to ditches within a drained forested

watershed on the lower Coastal Plain of North

Carolina. They found the presence of access roads

under the four practices had little impact on

sediment loading at the watershed outlet when

comparing the sedimentation of drainage from

similar watersheds without access roads.

Wetlands

The Clean Water Act allows minor drainage for

forestry without a permit. However, such drainage

cannot connect wetlands to uplands. Thinning or

harvesting of overstory trees is allowed in most

wetlands. However, mechanical site preparation to

establish pine stands in certain wetland types is

prohibited by the Corps and EPA (Anon. 1996).

Most State BMP manuals do not provide much

guidance about ditches or drainage. However,

many individual forest management companies

have developed their own wetland BMPs, and

these often stipulate basal area or canopy

requirements for wetlands. Silvicultural practices

in and around wetlands, therefore, vary greatly

from landowner to landowner.

Harvesting and Site Preparation Practices

During harvesting, log decks and skid trails

become temporary areas of bare soils. As with

roads, the water-quality goal for managing these

areas is to limit their hydraulic connectivity to

streams. On any site, the number of log decks

should be minimized and their distance to streams

should be maximized. BMPs call for minimizing

the number of temporary stream crossings and

for using water bars to disperse runoff from

skid trails. Soil rutting should be avoided and

minimized. Equipment that exerts low ground

pressure is recommended for wet sites. Skid trails

on wet sites should be matted with a layer of limbs

and branches over which equipment will operate.

BMPs require that mechanical site preparation

(plowing, bedding, ripping) be done along contours

to impede overland flow and minimize erosion.

If debris is piled, it should be piled on contour

to act as an organic silt fence. Most BMP

recommendations preclude site preparation

fires on steep slopes and call for cool fires that

do not eliminate the duff layer, which is crucial

in the prevention of surface erosion.

Effectiveness of BMPs

The National Association of State Foresters

(NASF) tracks State BMP program performance.

In its fourth survey, NASF (2001) reported that

all 50 States have developed forestry BMPs. This

is an improvement since NASF’s 1990 survey,

when only 38 States had BMPs. The national rate

of BMP implementation is 86 percent. Half of the

22 States that monitor BMP implementation had

overall BMP implementation rates of more than

90 percent (average 94 percent). A few States

reported implementation rates below 80 percent.

In addition to monitoring implementation, many

States have also conducted assessments of BMP

effectiveness. These investigations have found

that BMPs are highly effective in protecting

water quality during forestry operations (Adams

and others 1995, Keim and Schoenholtz 1999,

Kochenderfer and others 1997, Vowell 2001,

Williams and others 1999). However, different

States use different methods to survey the

effectiveness of BMPs.

Sediment and Flow

In a study conducted on a watershed triplet

in eastern Kentucky, Arthur and others (1998)

found that clearcutting without BMPs increased
213

suspended sediment loads by a factor of 30 in the

17 months during and following treatment and that

clearcutting with BMPs increased sediment loads

by a factor of 14 during this period. The effect of

clearcutting on sediment fluxes disappeared after

5 years. The increase in load was attributable

partly to increases in water yield (138 percent

without BMPs and 123 percent with BMPs,

respectively, in the first 17 months after harvest),

but was attributable mostly to increases in

suspended sediment concentrations. Most of

the streamflow effect also disappeared within

5 years of treatment, although some flow effect

was detectable when the study was completed 9

years after harvest.

Wynn and others (2000) analyzed a watershed

triplet in eastern Virginia. They found that

median storm total suspended sediment (TSS)

concentrations increased by a factor of eight after

clearcutting without BMPs. After site preparation,

median storm TSS concentrations in the no-BMP

watershed were 13 times as great as they had been

prior to harvest. In the watershed in which BMPs

were employed, there was no increase in TSS

when TSS was converted for climatic variations

observed in the control.

Using a cross-landscape comparison of firstorder watersheds with complete randomized

block design, Keim and Schoenholtz (1999)

compared water quality for four treatments:

(1) unrestricted harvest, (2) SMZs with cable

thinning, (3) no-harvest SMZs, and (4) reference.

Harvesting was group selection of hardwood

species on Mississippi loessal bluffs with steep

slopes with highly erodable soils. Grab sample

and machine-composited TSS concentrations

were higher in the watersheds with unrestricted

harvest and with cable-thinned SMZs than in the

references. TSS concentrations in the no-harvest

SMZ watersheds were not different from these in

references. Keim and Schoenholtz concluded that

BMPs should focus on eliminating machine traffic

within 10 m of streams.

Nutrients

Arthur and others (1998) found that mean

nitrate concentrations rose from < 1 mg/L to

almost 5 mg/L in the first 3 years after harvesting.

The nitrate pulse was similar in no-BMP and in

BMP watersheds. Concentrations of PO4

3-, K+,

Ca2+, Mg2+, Na+, SO4

2-, and alkalinity did not

respond detectably to harvesting. Wynn and

others (2000) observed a similar pulse of NO3

-

from their no-BMP watershed but not from their

BMP watershed. They found that total P loadings

increased in the no-BMP watershed, but that this

was explained by P bound to sediment, and was

not soluble P.

The use of controlled drainage to improve

water quality has been studied in a poorly drained

loblolly pine plantation on the North Carolina

Coastal Plain. Amatya and others (1998) reported

that controlled drainage with a raised weir at

the field outlets reduced annual export of TSS,

NO3

+NO2-N, and total Kjeldahl N by as much

as 57 percent, 16 percent, and 45 percent,

respectively, by reducing drainage volume and

peak flow rates. The annual total P and NH4-N

loadings were also reduced by 7 to 72 percent.

Amatya and others (2002) examined the effects

of controlled drainage with a raised weir and an

orifice on water quality. The authors reported that

this system reduced flow volume and peak rates,

and sediment and P loading, but had limited

effects on other water-quality parameters.

Water Temperature

Changes in surface water temperatures as

a result of forest harvesting activities conducted

in riparian areas can have dramatic effects on

aquatic biota (Wallace 1988, Webster and others

1988). Shading provided by trees in forested

riparian areas cools aquatic habitats and

moderates temperature fluctuations by insulation

(Swift and Messer 1971). Intensive harvesting

of riparian areas has been shown to increase

maximum daily stream temperatures from

5 to 10 o

C (Lynch and others 1985).

Because harvesting in riparian areas increases

water temperatures and affects aquatic biota,

BMPs have been designed to minimize changes in

water temperature. BMPs have been developed

that allow some overstory removal (generally ~

25 to 50 percent) within riparian areas of perennial

streams. Although many studies have shown

stream temperature effects following intensive

harvesting near streams (National Council for

Air and Stream Improvement 2000), few have

been designed to test the efficiency of these BMPs

in moderating water temperature impacts of

harvesting in ripirain areas. Within unharvested

riparian areas, 15- to 30-m riparian buffer

widths provide 85 to 100 percent effectiveness

in mitigating increased solar radiation (National

Council for Air and Stream Improvement 2000).

Studies in northern Florida found no stream

temperature increases in harvested riparian areas

ranging from 10.6 to 60.9 m in width when 50

percent of the canopy was removed in the zone

and a stringer of trees was left along the stream

Chapter 19.

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Water and Soils

214

(Vowell 2001). At the Fernow Experimental

Forest in West Virginia, there were small (~1 oC)

increases in stream temperature following a

“light” removal of timber in a riparian zone 20 m

in width (Kochenderfer and Edwards 1990). At

Coweeta in North Carolina, the removal of 22

percent of the basal area had no effect on stream

temperature (Swift and Messer 1971). Thus,

the few studies of the effects of BMP design on

stream temperature in the Southeast do suggest

that 25 to 50 percent basal-area reductions within

the riparian area lead to little or no increase

in stream temperature.

Aquatic Biota

Forestry BMPs, especially those related to

riparian areas, have been designed to lessen the

impact of harvesting activities on water quality,

and protection of water quality is generally

considered to be a surrogate for the protection

of aquatic communities. Therefore, the condition

of aquatic communities has rarely been assessed

directly during BMP effectiveness studies.

Intensive forest harvesting or land clearing in

riparian areas increases insolation, raises stream

temperatures, increases flows, increases both

stream sediment and nutrient loads, and generally

leads to greater primary productivity and shifts

in faunal communities (Barton and others 2000,

Richards and Hollingsworth 2000, Wallace 1988).

In northern Florida, there were no changes

in habitat or stream condition index, which is

based on macroinvertebrate populations, when

50 percent of the riparian overstory was removed

and trees adjacent to the stream were not removed

(Vowell 2001). In South Carolina, studies indicate

that riparian BMPs, when implemented, have

little to no effect on stream habitat and

macroinvertebrate communities (Adams and

others 1995). However, when riparian BMPs are

not implemented or are implemented incorrectly,

stream habitat and macroinvertebrate populations

are affected negatively.

MODELING TOOLS FOR EVALUATING

THE EFFECTS OF FOREST MANAGEMENT

C

omputer models cannot replicate the complex

processes that take place in forests, but they

are powerful and effective tools in forest

management. If they are used properly, models

can help us understand the processes and

synthesize data at different scales, and may

be a cost-effective tool for answering “what-if ”

questions. Because the Coastal Plains and the

uplands have different hydrologic processes, we

classify the existing computer models as wetland

or upland models according to their applicability.

Only those models that were developed for

or have been applied to southern forest

ecosystems are reviewed.

DRAINLOB and DRAINWAT

The DRAINLOB model (McCarthy and others

1992) is a forest version of the DRAINMOD-based

models that were well tested for poorly drained

(ditched) conditions in North Carolina and around

the world. It is a physically based, lumped, and

field scale hydrologic model. Using approximate

analytical methods, the model predicts the full

daily forest hydrologic cycle including rainfall

interception, infiltration, subsurface drainage,

surface runoff, ET, and soil water storage based on

an hourly water balance conducted for a soil profile

at the midpoint between two parallel ditches. ET

is simulated using the Penman-Monteith method.

Subsurface drainage rate is computed using a

“table lookup” procedure that employs tabulated

results of numerical solutions to the nonlinear

Boussinesq equation. McCarthy and Skaggs (1992)

applied DRAINLOB to evaluate the long-term

water budget and hydrologic impacts of watermanagement practices for thinned and unthinned

regimes of a pine plantation. This model has been

modified to DRAINWAT by the addition of flow

routing algorithms, and subsequently applied

to forested watersheds with multiple fields and

ditches (Amtaya and others 1997b). Major outputs

from DRAINLOB and DRAINWAT include

ground-water level and total outflow at the field

edge and the watershed outlet on a daily basis.

FLATWOODS

The FLATWOODS model is classified as

a physically based, distributed, and watershedscale surface ground-water model (Sun and others

1998a). It was developed and tested specifically

to examine the hydrologic impacts of forest

harvesting in the heterogeneous cypress-pine

flatwoods landscape (Sun and others 1998b). The

model simulates the full daily hydrologic cycle of

each uniform segment or cell of a watershed and

links each cell with shallow ground-water flow.

The vertical unsaturated water flow is computed

using a simplified Darcy’s equation while the 2-D

lateral ground-water flow is simulated by the

standard ground-water flow equation with Dupuit

assumptions. ET is the sum of canopy interception,

soil and surface water evaporation, and tree

transpiration. Potential ET (PET) is computed

using the temperature-based Hamon’s PET model.

The interception is modeled as a function of leaf
215

area index (LAI), precipitation, and PET. Soil

and surface evaporation are modeled as a function

of LAI and ground-water level. Transpiration

consumes the rest of the PET, but is limited by soil

moisture status. Total outflow that is affected by

averaged ground-water table and saturated areas

is calculated using an empirical power function

derived from experimental data. Major outputs

from this model are total daily flow and distributed

ground-water levels. Because this model explicitly

simulates the ground-water fluxes, it has potential

applications to isolated wetland systems, e.g.,

Carolina bays, that are common in the Coastal

Plain in the South.

WETLANDS

WETLANDS (Mansell and others 2000) was

developed to simulate the dynamic linkages of

ground water and surface water in isolated

depressional wetlands, such as cypress swamps.

It is an altered form of the VS2DT model, a twodimensional water and solute transport model

for variably saturated media (Healy 1990).

Radial symmetry and cone-shape geometry was

assumed for the seasonally flooded wetland that

is surrounded by uplands. ET is estimated by

the Priestley-Taylor equation from a minimum

set of daily weather data. Water-table levels in

the wetland, lateral, and vertical water movement

are simulated by solving two coupled equations

simultaneously: the Richards equation and the

water-balance equation for the wetland-upland

system. Major model outputs are water-table

distribution across the wetland-upland continuum,

ET, and soil moisture dynamics.

PROSPER

PROSPER is a lumped parameter model that

was developed to estimate water stress for an

upland forest stand by describing the atmospheresoil-plant water-flow processes (Goldstein and

others 1974). As the major component of the

model, ET is modeled by a combined energy

balance-aerodynamic method. Soil water is

depleted by ET, and its movement between layers

is modeled by Darcy’s law and mass balance by

an approximate numerical solution. Major climate

data requirements for this model include daily

values of precipitation, air temperature, relative

humidity, solar radiation, and wind speed. Other

parameters include mean values of albedo; leaf

area of vegetation; typical resistance values

for water movement through soils, plants, and

atmosphere; soil hydraulic conductivity; and root

distribution. Major outputs from the model are

daily ET and soil water potential at different

soil layers. PROSPER has been used to examine

the hydrologic effects of forest conversions (Swift

and Swank 1975) and climate change (Vose and

Maass 1999).

ANSWERS (Forest Hydrology Version)

The ANSWERS model represents the

first generation of physically based, spatially

distributed, watershed-scale models that were

designed to simulate the effects of agricultural

BMPs on runoff and sediment loss from

agricultural watersheds (Beasley and Huggins

1981) on a storm event basis. Thomas and Beasley

(1986a) modified the original ANSWERS model

with the goal of giving forest managers a tool for

evaluating management practices (logging and

prescribed burning). Major modifications include

the addition of interflow components of seepage

and macropore or pipe flow at the surface soil

layer, alternation of the canopy interception

submodel, and estimation of initial soil moisture

distribution. Major input data requirements

include soil physical characteristics, topography

(digital elevation model), and rainfall intensity.

Major outputs are storm flow volumes and

storm hydrograph.

This event-based model has been validated

successfully on five upland watersheds in the

upper Coastal Plain in Mississippi (Thomas and

Beasley 1986b). However, unsatisfactory results

were reported when the model was tested on two

steep mountain watersheds at Coweeta in North

Carolina where soils and topography were believed

to be unique and baseflow rates are relatively

higher than those of the Piedmont watersheds.

PnET-II

The PnET-II model is a lumped-parameter,

monthly-time-step, generalized stand-level model

that describes the C and water dynamics of mature

forests (Aber and others 1995). It simulates both

C and water cycles in a forest ecosystem using

simplified algorithms that describe key biological

and hydrologic processes. This model has been

validated and modified for southern upland forest

ecosystems (Aber and others 1995, Liang and

others 2002), southern pines (McNulty and others

1996, Sun and others 2000a), and hardwoods

(Hanson and others 2003). It has been employed

to assess the potential effects of climate change on

forest hydrology at a regional scale (McNulty and

others 1996). Input parameters for vegetation, soil

and site locations, and climate may be derived

from the literature or measured at a local study

site. Stand-level vegetation parameters include

Chapter 19.

Water Quantity and Quality
Southern Forest Science:

Past, Present, and Future

Water and Soils

216

 0 – 50

 50 – 100

 100 – 150

 150 – 200

 200 – 250

 250 – 300

 300 – 350

 350 – 400

 400 – 450

mm/year

those regulating physiological and physical

processes such as photosynthesis, light

attenuation, foliar N concentration, plant and

soil respiration, and rainfall interception. Only

one soil parameter, soil water-holding capacity, is

required. Climate input variables include minimum

and maximum monthly air temperature, total

monthly photosynthetic active radiation, and total

monthly precipitation. The PnET-II model closely

integrates hydrology with the biological processes.

ET is defined as the sum of plant transpiration and

canopy interception. Transpiration is simulated as

a function of C absorbed during photosynthesis

and water-use efficiency. The model simulates

the C cycle by tracking absorbed C during

photosynthesis; allocation of C to foliage, wood,

and roots; and respiration from leaves, stems,

and roots. The hydrologic cycle is simulated by

the water-balance equation. Water that is not

subjected to ET eventually ends up as water yield.

Major model outputs include annual forest net

primary productivity, monthly and annual ET,

and water yield.

SCALING-UP WATERSHED HYDROLOGY

FOR REGIONAL ASSESSMENT

T

here have been several attempts to generalize

experimental results from small watersheds to

guide regional forest management. Douglass

and Swank (1972) and Douglass (1983) derived a

general empirical equation to estimate water-yield

response to forest management in the Appalachian

Mountains. However, the model does not include

precipitation as an independent variable, and thus

has limited applicability for other similar mountain

regions. Huff and others (1999) presented

empirical methods and a computer program for

evaluating water-yield impacts of proposed forest

or vegetation thinning over a large area. They

tested the system in the Central Sierra Mountains

in California and found that the size of the

management area has an important bearing on

water-yield response. It is not known how well the

modeling system works for the Southern United

States. Sun and others (2002) tested and modified

a conceptual catchment-scale ET model (Zhang

and others 2001) using forested watershed

hydrologic data from across the Southern United

States. A Geographic Information System (GIS)

was used to integrate regional databases for forest

cover, climate, topography, and predicted potential

ET at a 4-km resolution. The regional analysis

shows that hydrologic response, as represented

by water-yield increase, varies greatly across the

complex physiographic gradients in the Southern

United States (fig. 19.5).

Figure 19.5—Predicted long-term annual water yield response

to forest removal at a 4-km resolution. Values are displayed at

a 30-m land use/landcover resolution.
217

SUMMARY AND RECOMMENDATIONS

R

esearch findings regarding water-yield

responses to deforestation and aforestation

in the Southern United States are consistent

with those of studies conducted elsewhere (Bosh

and Hewlett 1982, Stednick 1996, Whitehead and

Robinson 1993). The greatest increases in water

yield occur immediately following harvesting.

As more tree cover is removed, the higher the

response of water yield and ground-water table

increases. The conversion of a forest to a cover

type that requires less water, such as agriculture,

grazing, and fodder production, significantly

increases water yield. Conversely, conversion

of a forest to another forest type that intercepts

more water, such as conversion from mixed oakhardwood to eastern white pine, significantly

reduces water yield. Regrowth or reforestation

increases the interception capacity and

consumptive use of water, thus reducing

streamwater yield. Large-scale forest

manipulation to increase water availability is not

practical due to water quality and other ecological

concerns. The overall water-quantity effect of

silvicultural operations is much less in wetlands

than in areas having greater relief and shallow

soils. Compared to hilly uplands, southern

wetlands on the Coastal Plains or large flood

plains have low ratios of runoff to precipitation

(< 40 percent). Hydrologic responses of wetlands

to tree removal are expected to be low because ET

is often near potential and because management

activities generally have only minor effects on ET.

Wet-weather harvesting in forest wetlands often

results in soil compaction, rutting, and churning,

but hydrologic responses to forest management

are much smaller than hydrologic responses to

vegetation changes. Hydrologic recovery appears

to be faster in wetlands than in uplands. Climate

gradient also influences the effects of timber

management on hydrology, because climate affects

the recovery of vegetation and the way in which

environmental conditions change as a result of

forest disturbances. Effects of harvesting in colder

and drier water regimes, such as those in the

Appalachian Mountains, may last longer simply

because it takes longer to establish a forest under

such conditions. Intensity of forest management

practices can also affect hydrologic responses.

Stormflow volumes and peak flow rates are

expected to increase when forests are cut heavily

or converted to other land uses, especially during

nongrowing seasons. Few studies have addressed

the relations between forest cover change and

stormflow relations. Such studies are important

in forest hydrology in the 21st century, when

urbanization activities have been intensifying.

Forest watersheds produce better water quality

than other land uses. Silvicultural practices in

the South cause relatively minor water-quality

problems. Forest removal, prescribed burning, and

chemical applications cause immediate responses

in water-chemistry concentration and loading, but

these effects diminish rather quickly. Reductions

in nutrient export occur following conversion of

grasses to forests. Reductions in forest standing

crop as a result of insect outbreaks also increase

nutrient export. The major water-quality concern

related to forestry activities is sedimentation. The

impact of forest harvesting on sediment yield is

directly related to harvesting methods and road

building. Foresters in modern times have been

improving their methods to protect water quality.

When BMPs are used, forest harvesting does

not necessarily cause stream sedimentation.

Numerous road construction practices that

minimize erosion and sedimentation have been

identified. The cumulative effects of upstream

land use conversion and changes in land use

composition over time on streamwater quality

can be mitigated by proper forest management.

Forestry BMPs have been seen as the best tools

for controlling nonpoint pollution and protecting

water quality. However, the riparian BMPs for the

Southern States are not based solely on the best

available knowledge; rather they are the product

of battles among forestry groups, environmental

groups, and policymakers within each State.

Our knowledge of the effects of existing BMPs

is imperfect, and we could probably design

better BMPs if our knowledge of these effects

were increased.

Recent studies show that sediment, nitrate

release, stream temperature, and biotic

response continue to be issues when BMPs

are implemented. Pesticide movement from

silvicultural operations remains largely unstudied.

Process-based studies are needed to develop

specific information on how, when, and where

silvicultural BMPs fail to provide adequate

protection of water quality. Models and regional

analyses are needed to evaluate how BMPs

perform at regional scales (National Council

for Air and Stream Improvement 1999b). A key

question in BMP development and TMDL

implementation is: How much nonpoint-source

pollution is too much? For instance, what are the

Chapter 19.

Water Quantity and Quality
Southern Forest Science:

Past, Present, and Future

Water and Soils

218

ecological thresholds for sediment and nitrate

concentrations, and how do these thresholds differ

for river and lake systems? Should we protect

ephemeral streams during forestry operations,

and how? In general, there is a need for research

on the linkages between hydrology, water quality,

and biological responses (National Council for Air

and Stream Improvement 1999a).

There have been few studies of the cumulative

effects of different land uses on hydrology and

water quality at a large basin scale. Such studies

(Trimble and Weirich 1987, Williams and others

2002), which are reviewed in this chapter, present

new views on the role of forests that may

contradict presumptions or results from

traditional small watershed-scale studies. With

the development of new technology, such as remote

sensing, GIS, and explicit regional hydrologic

and water-quality models, the roles of forests

and effectiveness of forestry BMPs in reducing

nonpoint pollution on complex large landscapes

can be evaluated.

Computer models are useful tools for

generalizing and scaling-up the findings from

individual studies and applying the knowledge

to management practices. Most of the existing

watershed-scale forest hydrology models lack

nutrient, soil erosion, and sediment transport

components. There is a need for research that will

produce physically based, distributed watershedscale models that couple hydrologic processes,

forest nutrient cycling, and soil erosion on forest

lands. The complexity of forested watershed

processes has limited progress in development

of such models (Band and others 2001, Zhang and

others 2002). We should recognize that distinct

hydrologic processes exist across the different

physiographic provinces in the South. Different

types of models in the South are needed. For

example, ground water-dominated systems in the

Coastal Plain require a model that can describe

ground water water-table dynamics, while those

upland systems dominated by overland flow

or subsurface unsaturated flow require models

that can describe hillslope processes. Several

models such as WEPP (Nearing 1989),

ANSWERS-2000 (Bouraoui and Dillaha 1996),

and SWAT (Arnold and others 1998) have been

widely used for modeling nonpoint pollution from

agricultural lands, but significant modification

and revisions are needed before they can be

applied to forest systems.

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Socioeconomic
Southern Forest Science:

Past, Present, and Future

Socioeconomic

226

Chapter 20.

Policy, Uses, and Values. ................................................... 227

Chapter 21.

Forest Values and Attitudes

in the South: Past and Future Research. ...................................... 231

Chapter 22.

Nonindustrial Forest Landowner

Research: A Synthesis and New Directions. ............................. 241

Chapter 23.

Recreation

and Nontimber Forest Products. .................................................... 253

Chapter 24.

Timber Market Research,

Private Forests, and Policy Rhetoric. .............................................. 289
227

Chapter 20.

Policy, Uses, and Values

T

he South has changed dramatically in the last

100 years. It was a rural, agrarian society; it

has now become a predominantly urban one.

This has changed forever the region’s forests and

their management, use, and protection. In 1900,

there were just over 20 million people living in

the South. By 2000, the South’s population was

almost 89 million, making the region now one

of the fastest growing in the country. Projections

by the U.S. Census Bureau indicate the region’s

population will continue to grow at a rate greater

than the national growth rate, reaching over 110

million by 2020. By the year 2000, 74 percent of

the region’s population was urban, and as much as

80 percent of the region’s population will be urban

by 2020 (Tarrant and others 2002). The population

of the South is now mostly concentrated along

the coast, in the Piedmont cities, e.g., Atlanta,

GA, Charlotte, NC, and Columbia, SC; in the

major cities of Texas, e.g., Austin, Dallas, and

Houston; and in Florida. In 1990, the South’s

rural population was concentrated in the Southern

Appalachians, parts of the Mississippi River Basin,

and the western Texas and Oklahoma Panhandle.

But, overall, the entire region experienced

a general decrease in rural residency between

1980 and 1990, a trend that continues today.

The future of the South’s forests will be

determined within the context of rapid population

growth and increasing urbanization. The Southern

Forest Resource Assessment forecasts that 12

million more acres of the region’s remaining forest

land will be lost to urbanization by 2020 (Wear and

Greis 2002). These trends make the management

of the remaining forests, and those we will have

in the future, extremely important.

Because we must deal with the growing human

pressures on forests, we must understand the

human dimension of forestry. In these chapters

of the book, we review research on forest values,

forest uses, and forest policy in the South over

the last several decades.

The chapter “Forest Values and Attitudes

in the South; Past and Future Research” by

Michael A. Tarrant and R. Bruce Hull, examines

public viewpoints on forests over the past 100

years. At the turn of the 20th century, most people

viewed forests as a resource for economic

growth—a means of livelihood. Forest utilization

was preeminent and concerns about protection

were just emerging. Today many southerners

put environmental protection and nonuse

values over economic values. This change in

attitudes is significant for forest policy and forest

management. Increasingly, public opinion and

the threat of challenges, such as in the courts,

have reoriented forest policy and management,

especially policy and management that relate to

public forests. Tarrant and Hull offer a vision of

forest science and management shaped to reflect

the changing values and attitudes of southerners.

They discuss (1) increasing pluralism and conflict,

(2) the need for more collaboration and citizen

science, (3) creation of politically viable indicators

of environmental quality, and (4) moving beyond

a preservation-intervention polarization.

In the chapter “Nonindustrial Forest

Landowner Research: A Synthesis and New

Directions” by Gregory S. Amacher, M. Christine

Conway, and J. Sullivan, an econometric

examination of nonindustrial forest landowners

is provided. Nonindustrial private forest (NIPF)

landowners own more than two-thirds of the

forest land in some Southern States. Because

of the importance of NIPF lands as a source

of wood supply, the behavior of these landowners

has been a frequent topic in forest economics,

rural sociology, and policy research. In this

chapter, the authors review the large amount of

research literature on the topic, and then propose

new directions for future research. An emphasis

has been on recent empirical work regarding

the economics of nonindustrial forest landowner

behavior. The majority of research undertaken

prior to the late 1980s involved identifying and

understanding factors that influence reforestation

H. Ken Cordell1

1

 Senior Scientist and Project Leader, U.S. Department

of Agriculture Forest Service, Southern Research

Station, Athens, GA 30602.
Southern Forest Science:

Past, Present, and Future

Socioeconomic

228

or harvesting decisions. More recently

researchers have studied a broader set of

issues, including the relationships between

nontimber ownership objectives and uses and

other ownership factors, such as bequests

and owner characterization. Another recent

emphasis has been spatial mapping of owner

decisionmaking and intentions. The authors

conclude with recommendations for future

research. They recommend that reservation

prices for various activities be studied as a way

of assessing likelihood of market entry, that the

influence of adjacent owners be studied, that

substitution between various types of land use

decisions be investigated, and that individual

ownership data be integrated further into spatial

landscape models and Geographic Information

System applications.

The chapter “Recreation and Nontimber

Forest Products” by H. Ken Cordell and James

L. Chamberlain reviews research conducted

in the South during the last five decades on

forest recreation and the gathering of nontimber

forest products (NTFP) for personal as well as

commercial uses. Research on forest recreation

has been voluminous; research on NTFPs much

less so. Forest recreation research had its

beginnings in the late 1950s within a few southern

universities and with two Federal Agencies—

the Forest Service and the Economic Research

Service. Much of the recreation research in

these early years emphasized identifying who

recreates, where they recreate, their impacts

on the resource, and whether recreation and

tourism can be used to address persistent

poverty in some areas of the South. Through the

1960s and 1970s, recreation research expanded

tremendously with greater participation among

universities and public agencies. Both practical

problems and advances in theory and methods

of research were addressed. Through the 1980s

and 1990s, many topics of management concern

and of science concern were studied as the need

for science-based information for recreation

management expanded.

Unlike recreation research, research on

NTFPs is relatively new in the South. NTFPs

are forest plant materials that may include fungi,

moss, lichens, herbs, vines, shrubs, trees, or parts

thereof. Only a modest amount of research dealing

with NTFPs has been undertaken over the last

50 years. Most of it has focused on describing

the varied uses of the forest plants, their site

requirements, and other botanical factors. Until

very recently, within the last decade, NTFPs

were not well recognized as a management

concern, nor as a recreational or commercial

pursuit. Much of the early research focused

on defining and understanding how people used

these products. Currently more university and

agency scientists are looking at various aspects

of nontimber forest products, from management,

recreational use, commercial use, and ecological

impact perspectives. The chapter ends with the

authors’ observations about future research that

needs to be carried out for improved management

of forests.

Another chapter “Timber Market Research,

Private Forests, and Policy Rhetoric” by David

N. Wear and Jeffrey Prestemon interprets the

workings or failings of timber markets as core

issues for the conservation movement in the

United States. The South is the only major

timber-producing region of the United States

where private forests dominate and where

free interaction between private buyers and

sellers determines timber prices and harvests.

Private owners currently control 89 percent

of timberland in the region; 20 percent is held

by the forest industry and 69 percent is held by

nonindustrial entities. Because the South is the

clearest example of private forest management,

it has provided a setting for evaluating core

assumptions regarding markets, market failure,

and conservation rhetoric. In this chapter, the

authors examine the history of research into

private timber management and the function of

private timber markets in the South. In particular,

they examine research into the behavior of private

owners and of private timber supply. They also

examine how this private forest land research

has been influenced by policy rhetoric about

forests in the United States.

The authors contend that the rhetoric

of timber famine led to the establishment of

forestry programs in the Federal Government

and to designation of national forests. Regulation

of forestry activities at the State level also was a

result in parts of the United States. The profession

and practice of forestry can also be linked to

urgent concerns regarding timber shortages in

the 19th century. Timber shortages can be viewed

as market failures caused by overharvesting

or a lack of information regarding overall timber

inventories. Overharvesting can be the result

of uncertainty about future timber demand and

prices, which gives landowners a strong incentive

to harvest early. Without information on overall
229

inventories, landowners cannot anticipate

oncoming shortages and so fail to recognize

the potential for additional returns from

delaying their harvests. Both cases would lead

to suboptimal harvesting over time. A related

concern regarding timber markets has been a

perceived failure of landowners to protect or invest

enough in the productive capacity of their forests.

But issues concerning the effectiveness of private

timber management and markets in providing a

sustainable timber supply have largely been

answered. The research emphasis now is shifting

to understanding how these markets work so

that the future extent and structure of the forests

of the South can better be predicted. Better

knowledge of how markets work will enhance

understanding of how human occupation

and utilization of forest lands will influence

ecosystem structure and function in the future.

LITERATURE CITED

Tarrant, Michael A.; Porter, Robert; Cordell, H. Ken. 2002.

Socio-demographics, values, and attitudes. In: Wear,

David N.; Greis, John G., eds. Southern forest resource

assessment. Gen. Tech. Rep. SRS–53. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southern

Research Station: 175–187.

Wear, David N.; Greis, John G., eds. 2002. Southern forest

resource assessment. Gen. Tech. Rep. SRS–53. Asheville,

NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 635 p.

Chapter 20.

 Policy, Uses, and Values

231

Chapter 21.

Forest Values and Attitudes

in the South: Past and Future Research

Michael A. Tarrant

and R. Bruce Hull IV1

Abstract—At the turn of the 20th century,

southerners favored economic utilization of

forests over environmental protection. Today with

few exceptions, southerners rate environmental

protection and noneconomic values as higher

priorities than economic uses of forests.

We consider a vision of forest science and

management that reflects the changing values

and attitudes of southerners. We highlight four

issues that we feel will help create such a vision:

(1) increasing pluralism and conflict, (2) more

collaboration and citizen science, (3) the need

for politically viable indicators of environmental

quality, and (4) the need to move beyond a

preservation-intervention polarization.

INTRODUCTION

O

ver the last 100 years, the forestry profession

has undergone a dramatic shift that, to a large

degree, reflects changes in public attitudes

about forests and their management (Bengston

and Fan 1999, Manning and others 1999, Rolston

and Coufal 1991, Steel and others 1994, Tarrant

and Cordell 1997, Tarrant and others 2002, Xu

and Bengston 1997). During the early and mid

20th century, forest management endorsed a

resource utilization philosophy that emphasized

the exploitation, use, and development of

resources, dominance of economic over

noneconomic values, and human control over

nature (Bengston 1994, Steel and others 1994).

This approach is probably best captured by the

still popular “greatest good for the greatest

number for the longest time” motto. It is also

reflected in the Multiple-Use Sustained-Yield

Act of 1960 (Public Law 86–517), in which the

economic utility of timber, mining, recreation,

and other uses was emphasized. In the last 40

years, there has been a growing recognition and

respect of noneconomic benefits, the rights of

nonhuman parts of nature, and the importance

of public involvement in management decisions.

This later era, which reflects ideas expressed

much earlier in the writings of Muir and Leopold

among others, has been characterized by the

Federal Land Policy and Management Act of

1976 (Public Law 94–579) and by recent U.S.

Department of Agriculture Forest Service

(Forest Service) Agency programs, such as

new perspectives and ecosystems management.

At the beginning of the 20th century, the South

was producing more lumber than any other region

of the country (Williams 1989). Despite some calls

for sustainable logging practices and protection

and rehabilitation of the forests at that time,

production continued without substantial changes

in practices for the next 20 to 30 years. As long

as there was money to be made, the public asked

few environmental questions (Clark 1984). It

was not until new technologies in transportation

and harvesting, new chemical processes, and tax

incentives introduced in the middle of the century

that these dominant opinions changed. For

example, the introduction of a severance tax

on lumber removed from the land paved the way

for extensive reforestation efforts that led to a

reduction in cutover forests. (However, it should

be noted that most of the harvested forests were

replenished with pine (Pinus spp.) species to

satisfy increasing demands for paper and

pulpwood.) Furthermore, new chemical processes

and other applications meant relatively cleaner

and more efficient utilization of forests in the

South and such utilization received much popular

support (Hansbrough 1963). The balance began

to shift again in the 1960s and throughout the

remainder of the 20th century following the

publication of books such as “Silent Spring”

1

Professor, University of Georgia, Daniel B. Warnell School

of Forest Resources, Athens, GA 30602; and Professor,

Virginia Polytechnic Institute and State University, College

of Natural Resources, Department of Forestry, Blacksburg,

VA 24061, respectively.
Southern Forest Science:

Past, Present, and Future

Socioeconomic

232

(Carson 1962) and the rise of environmental

organizations with concerns about air, land, and

water (Clark 1984). Today, the general public

seems to favor environmental conservation over

economic use, in part because of heightened

public interest and awareness of forest issues

and practices.

Questions about who has the authority to make

decisions about public forests and controls over

private forest land have increased the political

nature of forest management, shifting power

to a more diverse set of players and most notably

to the general public. For example, while public

forest managers have had decisionmaking

authority delegated to them by the public, that

public is increasingly demanding a greater level

of power in determining how forests are managed.

The public (often through special-interest groups)

is also seeking greater involvement in actions

limiting the freedom of private landowners to

manage forests, especially where environmental

impacts are likely.

Definitions and Theory

Before considering southerners’ values and

attitudes toward forests, the terms must first be

defined. A value is a relatively enduring concept

of the good, importance, or worth of an object.

Once a value is internalized, it becomes a standard

for guiding action and developing or maintaining

attitudes toward relevant objects (Rokeach 1973).

An attitude is a learned predisposition toward an

object, issue, or situation that is emotionally toned

(Cacioppo and others 1981, Fishbein and Ajzen

1975, Theodorson and Theodorson 1969). Attitudes

are more transient than values and describe the

extent to which individuals or groups find an

object or a behavior desirable.

Values and attitudes are considered important

because they are thought to influence (predispose)

future action. For example, by understanding the

values and attitudes that individuals or groups of

people, e.g., political constituents, special-interest

groups, activity-user groups, etc., hold toward

forests, planners and managers are better

equipped to deal with a range of natural resource

actions that include mitigating potential conflicts

among stakeholders; establishing new policies,

programs, and goals; and defining new planning

strategies (Bengston 1994, Decker and others

1989, Manfredo and others 1995, Manning and

others 1999, Purdy and Decker 1989, Tarrant and

others 1997a). Predicting and influencing support

for management actions is essential in successful

forest management. For example, disagreements

between groups holding conflicting attitudes and

values are likely to require special mediation if

decisions are to be implemented in the forest

rather than stalled in the courts.

Over the past few decades, the general public

has become increasingly aware of forestry and

environmental issues (Dunlap 1991, Dunlap and

Scarce 1991, Steel and Lovrich 1997, Steel and

others 1997) and increasingly supportive of

noneconomic values of forests (Bengston and

Fan 1999, Bourke and Luloff 1994, Jacobson and

others 1996, Manning and others 1999, Xu and

Bengston 1997). This has resulted in greater public

involvement in forest management decisions

(Fortman and Kusel 1990), and especially through

the proliferation of interest groups representing

the diversity of values held regarding appropriate

uses of natural resources. Indeed, it has been

argued that the core problem facing traditional

forestry is a need to adjust to changing social and

environmental values (Bengston 1994). Support

for a shift toward noneconomic values has also

been shown to exist among Forest Service

employees, especially newly appointed district

rangers (Cramer and others 1993).

Traditionally, the public has placed high

values on marketable commodities such as timber,

range, and minerals, and these values have the

characteristic of being easily measured using a

monetary scale. Increasingly, the public is placing

importance on noneconomic values. Various types

of forest values have been identified (see, for

example, Rolston and Caufal 1991) and broadly

include amenity values, e.g., lifestyle, scenery,

wildlife, and nature; environmental quality values,

e.g., air, soil, and water quality; ecological values,

e.g., habitat conservation, sustainability,

threatened and endangered species, and

biodiversity; public use values, e.g., subsistence,

recreation, and tourism; community values, e.g.,

property values, community identity and stability,

and sustainable economic development; and

spiritual values. The overriding social trend

in these forest values is the idea that humans

are inextricably linked to the natural resources

they depend upon.

Attitudes of note include public beliefs and

evaluations of specific forest management

activities and issues including ecosystems

management (Manning and others 1999, Reading

and others 1994, Tarrant and others 1997b),

management of nonindustrial private forest

(NIPF) land (Bourke and Luloff 1994), and roads

in national forests (Bengston and Fan 1999).
233

Forest Values and Attitude Research

in the South

Few empirical studies of public opinions about

forests were conducted prior to 1940, and we rely

on anecdotal evidence in the early popular and

scientific literature to draw tentative conclusions

about forest values in the South during the first 40

years of the 20th century. Prior to 1920, a majority

of the public favored exploitation of forests for

lumber (Williams 1989). A small, vocal, and

growing minority of easterners began to voice

concern about aesthetic and other noneconomic

values of natural lands. During this time, remote,

forested resorts were popular tourist destinations

of the upper classes; the idea of creating the Great

Smoky Mountains National Park was born; and

romantic and picturesque views of nature matured.

Technological advancements in the 1920s led to

new attitudes toward forest conservation and calls

for reforestation to heal the destruction and raping

of southern forests that had occurred since 1880

(Mobily and Hoskins 1956). However, even with

reforestation efforts beginning in the 1930s,

industrial capitalism (with a focus on resource

utilization and efficiency) continued to be a

dominant attitude of forest owners and the general

public in the South through the middle of the 20th

century. During and immediately following the

Depression period, few protests against the woodproducing industries were heard, as “communities

asked only that the [timber] companies bring them

fat payrolls” (Clark 1984).

The period from 1940 through at least the

1960s witnessed the emergence of multiple-use

management. Forests were no longer managed

for timber exclusively and the economic benefits

of other uses (range, recreation, mining, water,

etc.) were recognized. Public opinion surveys

conducted by the American Forest Products

Industries (AFPI) from 1941 to 1962 (Hansbrough

1963) showed that while southerners knew very

little about private forestry, most respondents

had a favorable impression of private forestry

practices; for example, more than 66 percent

expressed favorable attitudes toward the pulp

and paper industry. Their attitudes clearly reveal

a strong economic orientation; southerners valued

the forests as an industry, as being essential to

America’s growth, and as offering good career

opportunities. It was not until the 1970s that

attitudes and values of forests shifted toward

an ethic more inclusive of noneconomic values.

Studies conducted in the last 30 to 40 years in

the South show (1) a relative decline in utilitarian

and economic forest values among the general

public, (2) a concomitant increase in noneconomic

values and attitudes held by the general public,

and (3) a continued emphasis on economic values

of forests by NIPF owners (but with increasing

interest in noneconomic attributes of forests).

A theme emerging from work conducted in the

past decade is that southerners favor a balance

of environmental protection and economic

development in public and private forests,

but with a very strong tilt in favor of the

environment. For example, in a study conducted

in the Midsouth, Bliss and others (1994) found that

most respondents believe a mix of economics and

environment is necessary, but nearly three times

as many chose the environment over the economy

as chose the reverse. A balance of environmental

and economic values is also reported in studies

of NIPF owners in the Southeast (Brunson

and others 1996, Williams and others 1996), in

studies of North Carolinian (University of North

Carolina 1993) and South Carolinian (University

of South Carolina 1992) residents, and in studies

of residents of southern Appalachia (Cordell

and others 1996). Other work suggests that

southerners assign a higher priority to

environmental protection than to economic

utilization of forests (Bliss and others 1997,

Cordell and others 1996, Tarrant and others 2002).

Cordell and others (1996) found that responding

residents of southern Appalachia exhibited

proenvironmental values and attitudes that were

moderately stronger than the national average.

For example, more respondents were against

increasing timber harvesting on private land

(46.5 percent) than were in favor (35.8 percent)

and a much larger proportion were against

(72.1 percent) than were in favor of (17.6 percent)

timber harvesting on public lands. Furthermore,

most respondents supported harvesting of dead

and downed trees (70.0 percent), but were against

the use of fire as a management tool (59.3 percent)

and having a landscape consisting of “brown and

dead trees” (68.5 percent). Respondents also held

slightly stronger proenvironmental attitudes

toward protecting fish and wildlife, and on aquatic

and clean air issues, than toward forest practices.

Overall, these findings are consistent with an

emerging noneconomic orientation to forests.

However, since most respondents were not in favor

of using fire as a management tool (which could

include letting forests burn naturally) or having

a dead landscape (which could be a natural

occurrence), the public may have low knowledge

about many ecological processes or management

practices. Such gaps in knowledge about forest

Chapter 21.

 Forest Values and Attitudes
Southern Forest Science:

Past, Present, and Future

Socioeconomic

234

activities have been reported in other studies of

the South (see Bliss and others 1994, Hansbrough

1963, Tarrant and others 1997b).

Other studies also reveal a relatively high

level of environmental concern among southern

residents. A University of North Carolina (1993)

study reported that 48 percent of southern

respondents (vs. 43 percent of nonsoutherners)

felt that the environment had become worse in

the past 10 years, and 13 percent (vs. 19 percent

of nonsoutherners) felt that the environment

had improved. In a University of South Carolina

(1992) study, 81 percent of South Carolina

residents indicated that it was more acceptable

to maintain an acceptable level of water quality

than to increase the number of jobs in the State.

In other work, Bengston and Fan (1999) found that

the most strongly held attitudes about roads in

national forests were that they provided recreation

access and contributed to ecological damage.

Consistent with results from other regions of the

country, eastern (including southern) residents

rated commodity-related benefits of forests roads,

such as access for timber harvesting or mining,

less important than noneconomic values, such as

access for scenic viewing and recreation.

A few studies have examined the forest values

and attitudes of one special-interest group: NIPF

landowners. NIPF owners manage about 70

percent of the forest land in the South and 58

percent in the Nation as a whole, although many

do not depend on their forest cover for an income

(Jacobson and others 1996). Studies around the

country report a preference by NIPF owners

for environmental over economic objectives for

managing forests that is consistent with attitudes

of the general public (Bourke and Luloff 1994,

Brunson and others 1996). This ordering by NIPF

owners of environmental over economic values

may not be as strong in the South as in other

regions. In a study conducted in the Coastal

Plain of South Carolina, Jacobson and others

(1996) found that while over 75 percent of NIPF

owners supported nontimber benefits of forests,

commodity values ranked highest overall in

importance. When asked to identify their top three

reasons for managing forest land, timber value and

overall land value ranked much higher (42.1 and

37.8 percent, respectively, reporting these as one

of their top three choices) than nontimber reasons

such as improving water quality (5 percent) and

increasing nontimber revenues (10.2 percent).

Williams and others (1996) found that Arkansas

NIPF owners supported environmental protection

initiatives on private forests but also strongly

believed that private forest owners should have

a right to use their land in any fashion without

regulations. NIPF owners in the delta and

southwest regions of the State especially

emphasized a utilitarian approach to forests

(supporting their use for growing and selling

trees). Hodge and Southard (1992), however,

found Virginia forest owners to value scenery

and wildlife over commodity production. Similarly,

Birch (1997) found that noneconomic ownership

objectives ranked higher for many NIPF

landowners living in the South, especially the

increasing majority of people who own smaller

acreages. The rapid turnover of forest lands

in the South suggests that people with more

urban and more environmental conservation

orientations are becoming the new owners and

neighbors of southern forests (Hull and Stewart

2002). Interestingly, while most of the NIPF owner

respondents considered themselves to be “middle

of the road” environmentalists, the majority were

not familiar with the Endangered Species Act

or the Clean Water Act, suggesting that many

may lack information or be misinformed about

natural resources.

Current studies suggest that the general

public’s preferences for environmental protection

may be growing even stronger. In a survey of

southern residents, Tarrant and others (2002)

found that wood production was rated as the

least important of four listed values associated

with forests and clean air as the most important.

However, their work also showed that there were

some differences between views of public and

private forests. The provision of wood products

was not valued as low for private forests as for

public forests, and the provision of clean air was

not valued as high for private forests as for public

forests. These results suggest that southerners

hold stronger (more restrictive) values about

public than private forests; i.e., they believe

strongly that public forests should provide clean

air in preference to wood products, but do not

hold such restrictive values for private forests.

In the same study by Tarrant and others, forest

values were significantly influenced by age and

gender. For example, younger people (16 to 24

years) placed significantly less importance on

wood products and significantly more on heritage

values of private forests than did older people

(50+ years). For public forests, the younger

generation valued scenic beauty significantly

higher than did the older generation. Generally,

younger people attributed more noneconomic

values to forests than did older people. Males

were found to value private forests for wood
235

production significantly more than did females,

while females valued public forests for heritage

values significantly more than did males. Overall,

females demonstrated less support for commodity

values and more proenvironmental attitudes than

males. These findings are consistent with other

national and regional studies showing that younger

people and females are more likely to exhibit

proenvironmental orientations toward forests

than are individuals in other categories. Kellert

and Berry (1987) found gender to be the most

important demographic influence on forest wildlife

values. Men demonstrated significantly stronger

utilitarian and scientific beliefs, while women had

stronger moralistic and humanistic beliefs. Steel

and others (1994) reported that women have

higher proenvironmental values of forests than

do men and that younger persons have higher

proenvironmental values of forests than do

older persons.

Steel and Lovrich (1997) have argued that the

movement toward an environmental protection

approach to forests and forest management

in North America reflects a postindustrial

society in which “higher order” needs for

self-development and self-actualization have

supplanted “subsistence” needs that are satisfied

through material acquisition. Factors that have

contributed to this change include (1) a shift in

population from rural to urban areas and (2) an

increase in economic growth. An increasingly

urban population is thought to have a stronger

association with a biocentric orientation because

the physical connection between people and the

realities of natural resource systems has been

removed. Also economic growth in urban areas

may have created public desire for nonmaterial

uses (and, therefore, less resource extraction)

of natural systems (Steel and Lovrich 1997).

In the South, fairly rapid and large increases

in wealth and urbanization (along with higher

education levels) might help explain why

southerners have begun to favor environmental

protection over economic and utilitarian uses of

forests. Since 1980, the South’s population has

increased at a higher rate (14.16 percent) than

in the Nation (9.78 percent), with most of the

increase occurring in major urban areas such

as Atlanta, GA, Austin, TX, Dallas, TX, and

Miami, FL, and along the eastern coastline

(Tarrant and others 2002). In the South, the

population declined only in rural areas, including

the Southern Appalachians, the Mississippi

River Basin, and the western Texas and Oklahoma

Panhandle. Incomes have increased in the South,

with the highest gains in median household income

in the eastern half of the South, especially in major

cities, in the Carolinas, and along the Florida

coast. Income levels decreased in the Mississippi

River Basin, the Southern Appalachians, Texas,

and Oklahoma, and along the coast of Louisiana.

CONCLUSIONS

T

he purpose of this conclusion is to proffer

a vision of forest science and management

reflecting the changing attitudes and values

reviewed above. Gazing into a crystal ball can

be both empowering and sobering. The forestry

profession is empowered when it recognizes

that it is as much about conflict resolution,

communication, perceptions, and values as

it is about soil erosion, volume estimates, and

tree biology. Social science not only provides a

critical tool for forest management but it helps

professionals be much more sophisticated in

defining and solving forest management problems.

We are sobered, however, when we recognize that

we know very little about the social dynamics

of forest management and still struggle just

to ask relevant questions about this subject.

Below, we discuss four value-related issues we

expect to have profound implications for forest

science and management. These are (1) pluralism

and conflict—in the future, the conduct of debate

about matters of forest science and forest

management will be characterized by more

pluralism and more conflict; (2) more collaboration

and citizen science—the general public will have

more influence in matters formerly decided largely

by specialist professionals; (3) politically viable

indicators of environmental quality—those in

the social and natural sciences will need to

collaborate to develop politically viable indicators

of environmental quality; and (4) the preservationintervention dichotomy—forest science and

management need to move beyond the polarizing

preservation-conservation dichotomy.

Pluralism and Conflict

An increasingly pluralist society will increase

the diversity of stakeholders demanding and

deserving a place at the decisionmaking table.

Diversity springs from many sources. The

ethnicity of the South’s population is changing

and the increasing political power of groups that

formerly had little influence will likely affect the

management of forested lands. Migration from

rural to urban areas leaves many remote forested

areas without much political representation. While

this phenomenon is more characteristic of Western

Chapter 21.

 Forest Values and Attitudes
Southern Forest Science:

Past, Present, and Future

Socioeconomic

236

States, some Southern Appalachian and west

Texas counties are still losing population to fastgrowing urban and suburban counties. The result

is that State and Federal forestry agencies will be

redirected by legislators to favor the values and

concerns of urban and suburban constituents over

the needs of rural residents and industries.

Migration from urban to rural areas presents a

different set of challenges in that forests get new

neighbors and new owners. People are bypassing

traditional suburbs to live on small, forested

estates. Trends in forest ownership show more

and more people own smaller and smaller

holdings, so that a decade from now the average

forest landowner will own < 15 acres. These

owners have new ideas about forest management

and tend to be politically savvy and more insistent

on the use of formal mechanisms for making

decisions (Fortmann and Kusel 1990). Not only are

the owners and neighbors of forests different, but

so is the cast of professionals. More disciplines and

professions involve themselves in decisions about

forested areas. Planning, landscape architecture,

ecological economics, environmental engineering,

industrial ecology, conservation biology, and

restoration ecology are just a few of the disciplines

that now join with forestry and wildlife biology

in providing professional expertise and science

about forest land management issues.

One can debate whether urban values will

replace or evolve into rural values, and whether

hunting, timber harvesting, and other consumptive

activities will decline or increase, but we can state

with some confidence that the number and

diversity of views about what should happen

on forested lands will increase.

More Collaboration and Citizen Science

People are increasingly aware of the limitations

of positivist, bureaucratic, modernist science, and

decisionmaking approaches that seek optimal

solutions using unbiased information to maximize

the greatest good for the greatest number for the

longest time (Lee 1993, Stankey 2000). Science

is limited in what it can offer natural resource

management (Robertson and Hull 2001). The

uncertainty in future conditions provides just one

compelling example of this limitation. The world

and how it works is so utterly complex (chaotic and

changing) that relative to what might be known

about it, we now know very little, and we are not

likely to ever know all that much. Yearley (2000)

defines four levels of uncertainty. Conservation

decisions are and must be made at each level,

but the role of science in the decision differs

dramatically depending on the level of uncertainty.

At the first level of uncertainty, risk is estimated

and characterized through science with statistical

estimates of error, reliability, and precision. The

next level involves more uncertainty because the

system is not understood well enough so that its

properties can be quantified, but most of the main

parameters likely to affect the outcome are known.

For example, ecosystems are difficult to define

as ecologically significant units due to their

dynamism and their indefinite boundaries, but

we know that energy flows, population dynamics,

and keystone species are important parameters

for most ecosystems. The third type of uncertainty

is ignorance. In cases of ignorance, we don’t know

what we don’t know. In other words, we don’t even

know the main parameters; e.g., the impact of

global warming on forest productivity. Lastly,

indeterminacy is the highest level of uncertainty. It

is impossible to know or predict how some systems

will work because the system’s operation depends

in large part on human behavior that is likely to

change in the future and, thus, is entirely outside

the scope of scientific prediction. For example, this

is the case with estimations of the long-term health

and sustainability of humanized ecosystems in

which energy consumption, waste production,

tastes, and technological improvements in

efficiency are not only unknown but likely

to change in unanticipated ways.

Scientists find themselves in an awkward

position. On the one hand, the public asks for

policy formation and management decisions

based on the “best available science.” On the

other hand, there is declining public trust in

science, increased recognition of scientific

uncertainty, growing demand for scrutiny of

all decisions, and increased disenchantment

with any authority. Citizen science, which involves

and respects citizen concerns during key stages

of the knowledge generation process, is offered as

one possible response to these concerns (Fischer

2000, Shutkin 2000). Other responses call for a

less rigid, less self-conscious, and more adaptable

management approach that makes it easier for

scientists, managers, and the public to learn from

and adapt to changing situations as they emerge

(Holling 1978, Lee 1993, Norton 1998).

Politically Viable Indicators of

Environmental Quality

Indicators of environmental quality are used

prescriptively and descriptively. They describe

what is and prescribe conditions that should be.

These terms are important because (1) they direct
237

scientific inquiry, (2) they are used to set policy

goals and evaluate management outcomes,

and (3) they both inform and reflect public

perceptions and expectations of current and

possible environmental conditions. Indicators

of environmental quality are powerful tools

for environmental management (see Bergquist

and Bergquist 1999, Rapport and others 1995).

Indicators are the qualities of the environment

that science monitors; e.g., “acid” producing gases

for air quality, threatened and endangered species

for biodiversity loss, and site index for forest

productivity. Indicators trigger corrective

management action when they exceed some

negotiated level. Their use also enhances

accountability by providing measurable evidence

of progress towards agreed future conditions.

Developing indicators requires a sophisticated

combination of social and natural sciences. Social

sciences are necessary because effective indicators

must reflect the values, norms, and goals of the

society for which the environment is being

managed. They must reflect the qualities of

the environment that society cares about and is

willing to allocate its limited resources to maintain.

Natural sciences are necessary to make indicators

descriptively precise, reliable, and theoretically

rigorous representations of environmental

conditions. For example, when a community

decides that it wants to manage water quality, it

selects indicators of water quality, such as amount

of surface water retention and nutrient load, to

direct management and gauge success. These

indicators prescribe desired future conditions

(the community wants more water retention and

less nutrient load). The community could have

selected other indicators (ground-water pollution

or water turbidity) and, thus, prescribed different

future conditions.

The Environmental Monitoring for Public

Access and Community Tracking (EMPACT)

project at the U.S. Environmental Protection

Agency provides an important illustration of

this approach (http://www.epa.gov/empact/) as

do certification programs that develop and assess

indicators of sustainable forestry. The current

international Montreal Process on the Criteria and

Indicators for the Conservation and Sustainable

Management of Temperate and Boreal Forests

(http://www.mpci.org) represents one of the most

comprehensive efforts to integrate social and

biophysical indicators in addressing forest

management in the South and elsewhere. These

indicators of environmental quality must reflect an

increasingly diverse set of values being attributed

to forests. As illustrated by the first section of

this chapter, forests are valued as much more than

sources of water, wood, wildlife, recreation, timber,

and range. Indicators of forest quality that serve

as guides for management should reflect the

deeper symbolic meanings attributed to diverse,

sustainable, forest ecosystems as well as the

property value, community identity, and sense

of stability that living near forests provides.

The Preservation-Intervention Dichotomy

Preferences for management often polarize

around the role of humans in nature, and around

the extremes of preservation and intervention.

The preservationists have characterized the

interventionists as environmental rapists

promoting irresponsible development. They

argue that humans can only soil nature’s

goodness. The interventionists have characterized

the preservationists as privileged urbanites who

do not understand or value the role of human

culture in nature. They argue that humans

can improve upon nature’s randomness and

inefficiencies. Disagreements regarding the

appropriate role of humans in the natural

landscape are a key factor polarizing discussions

about natural resource management (Callicott

and others 1999, Dizard 1994, Hull and other

2001, Ingerson 1994, Senecah 1996).

Bioculturalism offers an alternative. It

encourages stakeholders to recognize human

society as an integral component of ecological

systems and seeks ways for people to interact

with and live sustainably in nature. Bioculturalism

is increasingly accepted by the international

conservation community, which has long

recognized the limited effectiveness of

preservation strategies that favor biological

diversity over cultural diversity (Droste and

others 1995, West and Brechin 1991, Zimmerer

and Young 1998). Another place to look for

inspiration and direction is in the innovative ideas

of contemporary bioculturalists such as William

Jordan, Frederick Turner, and Michael Pollan

(Jordan 1994, Pollan 1991, Turner 1994). These

three thought-provoking writers are among a

growing contingent of biocultural activists who

are designing creative approaches to the humannature relationship based on the belief that

humans can be artful agents of landscape

change. “Sunflower forests,” the biocolonization

of neighboring planets, and “the cultivation of a

new American garden” are among bioculturalists’

ideas for a better, more democratic, sustainable,

and desirable future.

Chapter 21.

 Forest Values and Attitudes
Southern Forest Science:

Past, Present, and Future

Socioeconomic

238

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Chapter 21.

 Forest Values and Attitudes

241

Chapter 22.

Nonindustrial Forest Landowner

Research: A Synthesis and New Directions

Gregory S. Amacher,

M. Christine Conway,

and J. Sullivan1

Abstract—In this chapter, we review recent

empirical work related to the economics of

nonindustrial forest landowner behavior, discuss

emerging problems involving these landowners,

and suggest topics for future research. Before

the late 1980s, most work in this area was aimed

at identifying variables affecting reforestation

or harvesting decisions. Recently, researchers

have studied a broader range of subjects, including

the relationship between nontimber preferences

and decisions, such as bequests, examination

of the influence of type of landowner on

decisionmaking, and use of landowner-level

responses in spatial landscape models. We

propose that future research characterize

reservation prices for various activities, evaluate

the extent to which a landowner’s behavior

influences that of adjacent landowners,

investigate the substitution between various

types of decisions, and integrate landowner-level

models into spatial landscape models.

INTRODUCTION

N

onindustrial private forest (NIPF) landowners

are an extremely important group of forest

owners, accounting for about 70 percent of

land ownership in many States. Not surprisingly,

the behavior of nonindustrial landowners has been

one of the most frequently visited topics in forest

economics, rural sociology, and policy research.

Several books and hundreds of papers have been

written about this subject, and there are several

good surveys of the early literature. The purpose

of this chapter is to review the voluminous recent

literature, and then propose new directions for

future research.

RECENT LITERATURE

N

onindustrial landowners are of interest to

forest economists because of their relatively

low timber productivity. Given that these

landowners control the majority of timberland

in the South and elsewhere in the United States,

the decisions they make are critical to future

timber supplies. Many landowners are reluctant

to invest capital in long-term ventures such as

timber production. The lack of insurance covering

such investments can also be a deterrent to timber

investment by landowners. Furthermore,

landowners are thought to place considerable

value on nontimber benefits associated with

standing forest stock. Much recent work has

been directed to explaining these preferences.

The Government has responded to timber

supply concerns by offering a variety of incentive

programs to landowners, most taking the form

of cost-share payments for reforestation efforts

following harvest, or incentives for afforestation

of lands held in other predominantly agricultural

uses. Most program funding has gone to southern

landowners, as detailed by Goodwin and

others (2002).

1

Associate Professor, Doctoral Candidate, and Associate

Professor, Virginia Polytechnic Institute and State University,

Department of Forestry, Blacksburg, VA 24061, respectively.
Southern Forest Science:

Past, Present, and Future

Socioeconomic

242

In this section, we discuss a core of recent

econometric studies. However, a word about our

literature review is needed before proceeding.

Early on, researchers attempted to identify

the most important determinants of landowner

harvesting and reforestation investment behavior.

As Government programs grew in scope,

researchers increasingly examined the decision

to participate in reforestation cost-share programs

or the decision to leave timber and land as

bequests. Twenty years ago researchers began to

believe that nonindustrial landowners view their

problem as one of maximizing utility rather than

one of maximizing profits (Binkley 1981, Boyd

1984, Hyberg and Holthausen 1989, Max and

Lehman 1988). It is this utility-oriented post mid1980s literature that we primarily concentrate

on here. Readers are referred to Boyd and

Hyde (1989) and Hyde and Newman (1991) for a

discussion of the earlier literature on nonindustrial

landowners, and to Pattanayak and others (2002)

for an excellent review of the timber supply

literature as it is related to NIPF landowners.

The behavior of private landowners is far

less predictable than industry behavior, because

of the multiobjective nature of their ownership and

the difference in time horizons for management

decisions. NIPF landowners may not always

respond to prices in the same way that forest

industry does; this makes predicting timber supply

from NIPF land quite difficult, as noted first by

Dennis (1989) and Newman and Wear (1993).

Newman and Wear estimated a restricted profit

function for NIPF and industrial landowners in

the Coastal Plain region of the Southeast. While

the two ownership groups were found to respond

similarly to input and output price changes, NIPF

owners differed from their industrial counterparts

with regard to the value attached to growing

stocks for the amenity values they provide.

As a result, Newman and Wear concluded that

NIPF landowners can be characterized as profit

maximizers, who have preferences for amenities.

Hultkrantz (1992) compared results from

econometrics studies in the United States and

Scandinavia during the 1980s, showing that

NIPF landowners respond to prices, costs, and

interest rates in a way that is consistent with profit

maximization. However, he also concludes that

it is necessary to determine what specific land,

ownership, and market factors drive the various

management decisions made by these landowners.

Nontimber management goals are thought to be

a major reason for private ownership of forest land

(Binkley 1981, Birch 1992, Boyd 1984, Conway and

others 2003, Hartman 1976, Newman and Wear

1993, Pattanayak and others 2002). Nonindustrial

owners do not typically own forest land primarily

for the purpose of producing timber (Alig and

others 1990, Hodges and Cubbage 1990, Marler

and Graves 1974). One explanation, noted by Alig

an others (1990), is the effect increasing wealth has

had on the desire to produce nontimber benefits.

Nevertheless, landowners often appear to have

an interest in joint production of timber and forest

amenities (Conway and others 2003, Egan 1997,

Kline and others 2000, Newman and Wear 1993,

Pattanayak and others 2002). Worrell and Irland

(1975) list difficulties NIPF landowners must

overcome if they are to produce timber and

amenities successfully. These include lack of

knowledge, incompatibility of nontimber and

timber production goals, and low-profit potential.

Public intervention is often viewed as necessary

to induce landowners to manage their land for

timber (Bell and others 1994, Boyd and Hyde

1989), and design of tax and incentive programs

has been an ongoing concern (Amacher 1997).

The U.S. Government has relied on incentives

much more than governments of other countries.

Many of these programs for reforestation date

from the 1930s (Goodwin and others 2002).

Recent incentives have taken the form of funds

for research, extension, and technical assistance,

as well as tax benefits and input subsidies

such as sharing of costs for tree planting

(deSteigeur 1984).

Landowner Harvesting Decisions

Harvest, reforestation, and program

participation decisions of landowners are often

explored by means of qualitative response models.

In these models, the probability that a landowner

will undertake some activity is related to prices,

costs, interest rates, physical land characteristics,

and landowner demographics and preferences.

Binkley (1981) modeled the harvest behavior of

NIPF landowners in New Hampshire. He found

that stumpage price was a significant predictor

of harvest behavior, and this suggests that the

substitution effect of a price increase is stronger

than the income effect (Dennis 1989). Boyd (1984)

investigated the effect of reforestation cost sharing

on the harvest decision, and found that the costshare payment is not a significant harvesting

predictor. Variables significant to harvesting

included stumpage price, technical assistance, size

of landholding, farm occupation, and education.

Hyberg and Holthausen (1989) presented both

harvest and reforestation models based on survey
243

data collected in Georgia. Several variables were

found to be significant in predicting harvesting,

including income and land values, which were

inversely related to the probability of harvesting.

This suggests that wealthier landowners forego

harvest for the amenity values their forest

land provides. Stumpage price was negatively

correlated with harvesting, while tract size,

knowledge of cost-sharing programs, technical

assistance, and farming as an occupation were

positive predictors. Dennis (1989, 1990) found that

harvesting decisions were influenced by income,

education, and relative values landowners place

on amenities and consumption, as represented

by standing stock. The negative coefficient he

obtained for the income variable also suggests,

like others, that affluent landowners might be

less interested in timber production. In a similar

study of Finnish landowners, Kuuluvainen and

others (1996) concluded that high stumpage prices,

standing stock, and forest growth are all important

indicators of timber harvesting by NIPF owners.

Conway and others (2003) investigated the

behavior of NIPF landowners in Virginia,

observing that risk perception associated

with growing trees and tract size are important

predictors of timber harvesting, and that absentee

ownership (defined by location of residence

> 50 miles from the land parcel) negatively

influenced harvesting.

It is suggestive that the estimated coefficient

of the tract size variable has been positive for all

of the harvest probability models discussed here.

In fact, Dennis (1989) predicted that changes

in timber supply would be attributed to changes

in total land area in production, rather than to

increases in per-acre volume. A higher probability

of harvesting on larger tracts also is consistent

with observed higher net prices; i.e., the market

price net of logging costs (Conway and others

2003, Dennis 1989, Hyberg and Holthausen 1989).

The current trend towards parcelization of NIPF

land into smaller land units, as urbanization and

economic growth spreads from city centers,

may, therefore, have important implications

for policy. The bulk of research suggests that

parcelization may reduce timber availability

over a range of prices.

The treatment of timber prices differs among

these studies. Dennis (1989, 1990) and Hyberg

and Holthausen (1989) used aggregate prices

in their models, while Conway and others (2003)

used actual returns for those who harvested

and predicted prices for those who did not.

Kuuluvainen and others (1996) used annual

prices from written contracts with the individual

landowners for the years in which the landowner

made a sale, and regional prices for the years in

which the landowner did not sell. Not surprisingly,

there has been considerable debate about the role

that prices play in harvesting decisions. Dennis

(1989) argues that stumpage price increases

induce both income and substitution effects, and

this implies that the effect of price on probability

of timber harvesting depends on the relative

strength of each effect. He further suggests that

the influence of price on harvesting is necessarily

ambiguous. Other work has supported this,

finding a lack of responsiveness of landowners

to stumpage prices in various management

decisions (Alig 1986, Brooks 1985, Conway and

others 2003, Dennis 1989, deStiegeur 1984,

Klosowski and others 2001, Newman and Wear

1993). While these studies are numerous, others

have identified a significant influence of price on

management decisions, particularly for sawtimber

harvests (Binkley 1981, Cohen 1983, Hyberg and

Holthausen 1989, Kuuluvainen and others 1996,

Royer 1985). The price influence is positive in

all but Hyberg and Holthausen (1989).

Landowner Reforestation Decisions

The decision to reforest land following

harvesting may be important for meeting longterm softwood timber production goals. In the

South, most tree planting takes place on cutover

timberland (Royer 1985, 1987). Royer (1985)

modeled the reforestation behavior of southern

NIPF owners. His results suggested that

pulpwood prices, knowledge of cost sharing,

income, and contact with professional foresters

were important predictors of pine (Pinus spp.)

tree planting on cutover timberlands. Higher

reforestation costs and farming as an occupation

reduced the likelihood of reforestation. Brooks

(1985) found that cost-sharing payments

significantly increase the likelihood of tree

planting. Similarly, higher reforestation costs

negatively influenced tree planting in the

Southcentral United States. Stumpage prices

had no effect on reforestation in his study. Romm

and others (1987) relate forestry land investment

in northern California to a variety of owner and

ownership characteristics. High income and fulltime residence emerged as significant predictors

of investment behavior, (e.g., reforestation) in their

model. Midrange income, absentee ownership,

and greater landowner age preclude forestry

investment. Hyberg and Holthausen (1989) found

that knowledge of cost sharing not only increases

likelihood of harvesting, as mentioned above,

Chapter 22.

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Southern Forest Science:

Past, Present, and Future

Socioeconomic

244

but also affects the probability of reforestation.

Stumpage prices, household income, and technical

assistance also positively affected tree planting,

while higher reforestation costs led to decreased

tree planting. Finally, Conway and others (2003)

and Amacher and others (1998) found that access

to the resource, timber bequest intentions, and

the ratio of landowner debt to income were

important predictors of reforestation for

Virginia landowners.

Models of timber management and

reforestation behavior based on information have

also been used to study landowner decisions. For

example, Straka and Doolittle (1988) developed a

“diffusion of innovations” model, of a kind widely

used in agricultural technology adoption studies,

to assess how information about a new product

or practice is communicated to individuals, and

how individuals decide to accept or reject it.

Their model is used to determine the rate of

reforestation among NIPF owners. The specific

research question they were concerned with

was whether owners who spend resources to

regenerate are more likely to be innovative than

those who do not. They found that landowners who

reforest were more venturesome and innovative,

with higher incomes, and were more likely to

belong to organizations, had higher levels of

education, and owned more land.

Landowner Decisions to Participate

in Programs

Many studies of participation in forestry

assistance programs were undertaken in the

1990s (Bell and others 1994, Crabtree and others

1998, Esseks and others 1992, Nagubadi and

others 1996). Bell and others (1994) analyzed

landowner participation in Tennessee’s Forest

Stewardship Program. Individuals most likely

to participate had a household income of $50,000

or greater, had previous experience with forestry,

actively sought information regarding land use

programs or practices, supported conservation,

and had unmanaged forest, pasture, or cropland as

primary land uses. Bell and others concluded that

a Government should concentrate resources on

promoting education, rather than increasing the

amount of cost sharing, if the goal is to promote

forest management. Esseks and others (1992)

found that Conservation Reserve Program

(CRP) participation was positively correlated

with involvement of landowners in technical

assistance and forestry experience, and was

negatively correlated with income. Nagubadi

and others (1996) studied cost-sharing program

participation in Indiana. Tract size, membership

in forestry organizations, age, and residence on

the land emerged as important determinants of

program participation.

Romm and others (1987) investigated NIPF

landowner propensity to invest in forestry or

respond to public policies and programs. They

suggest that public programs for nonindustrial

private forestry cannot be targeted effectively

unless the program’s purpose is defined narrowly.

Hyberg and Holthausen (1989) believe that

incentive programs can actually reduce timber

supply. They argue that as landowner wealth

increases, landowners may substitute amenities

for timber production, reducing their future

harvesting. Kluender and others (1999) feel that

incentive payments often do not lead to additional

production from NIPF land, and that cost-share

programs have not kept real prices from rising.

Brockett and Gephard (1999) studied the

Tennessee Greenbelt Program. This program

provides preferential property tax treatment for

landowners who do not develop their land. Their

land is then valued in its current use, rather

than in its “highest and best” use. Brockett and

Gephard conclude that tax incentives are too small

to affect long-term behavior of NIPF landowners

faced with pressures to develop their land. They

argue that such tax programs simply reward

landowners for making forestry investments

they would already make without the tax relief.

Landowner Bequest Decisions

Harvesting, reforestation, and forestry

assistance program participation are not the only

important management decisions made by NIPF

landowners. Royer (1985) argued, for example,

that “additional modeling efforts should address

other forestry decisions to provide a more

comprehensive look at the landowner behavior.”

Bequest motives are also critical to meeting timber

demand, since timber and land bequests affect

the future contiguity and size of forest cover.

There has been some, but not extensive, progress

in this area (Amacher and others 2002, Conway

and others 2003, Hultkrantz 1992). Since many

NIPF landowners in the South are approaching

retirement age (Alig and others 1990), their

bequest decisions will become very important to

the continued use of forest land. In fact, timber

bequests from one generation to another may

actually be more important in promoting longterm timber investment than Government

incentives, according to Hultkrantz (1992). Royer

(1985) found that plans to sell forest land within
245

the next 20 years resulted in a 22-percent decline

in probability that a landowner would reforest

following a timber harvest. Conway and others

(2003) and Amacher and others (2002) related

timber bequest intentions (plans to leave a timber

bequest to heirs in the future) to a variety of land,

owner, and market parameters. They determined

that stumpage price, time spent in nonconsumptive

recreational activities, absentee ownership, and

tract size are significant predictors, among others.

Except for tract size, each of these variables

positively affected the probability of bequests.

Increasing tract size negatively influenced the

likelihood of leaving timber to heirs.

Landowner Participation in

Nontimber Activities

Recent NIPF research has examined in more

detail the nontimber amenity tradeoffs that forest

landowners face. In particular, researchers have

become interested in the substitution between

harvesting and nontimber preferences (Conway

and others 2003, Pattanayak and others 2002)

and willingness to accept payments to postpone

harvesting and capture wildlife benefits (Kline

and others 2000). Conway and others assumed

that harvesting and reforestation decisions are

not determined independently of nontimber

activity and bequest decisions; i.e., that they

are not separable (e.g., see Koskela 1989). The

nontimber activity decision is modeled explicitly

as an endogenous variable by considering the

choice of activity and the time spent in an activity.

In other studies, forest inventory or land area

in forests has been used as a proxy for amenity

preferences (Binkley 1981, Pattanayak and others

2002). Conway and others (2003) examined actual

use, finding that nonconsumptive activities such

as hiking, camping, and observing wildlife were

positive indicators of timber bequest intentions,

but recreational activities were not correlated

with harvesting or reforestation behavior. Kline

and others (2000) conducted a telephone survey

of NIPF owners in western Oregon and western

Washington to determine willingness of

landowners to accept incentive payments and

forego harvesting (for the sake of protecting

wildlife habitat). Willingness to accept was

related to ownership objectives, socioeconomic

characteristics, and incentive offered. Landowner

age, education, income, multiobjective ownership,

and incentive payment were positive predictors

of willingness to accept, while size of landholding,

sales income, and plans to cut trees were

negative predictors.

Predicting the Intensity of Forest Practices

Most of the above studies were efforts aimed

at estimating the probability that a landowner

undertakes an action. There are some studies that

have examined the intensity of either harvesting

or reforestation. For example, deSteigeur (1982,

1984), Cohen (1983), and Hardie and Parks (1996)

examined the levels of reforestation landowners

undertake on their land. Cohen (1983) found

that reforestation implemented by Southern

U.S. landowners was positively correlated with

stumpage prices, cost sharing, and household

income, but reforestation costs and interest rates

did not emerge as significant factors. De Steiguer

(1984) considered whether Government payments

(specifically the Forestry Incentive and

Agricultural Conservation Payment) programs

substituted for private investment through

changes in tree planting. He showed that planting

investment level was influenced positively by

income and negatively by interest rates.

Government cost-share payments were not

significant, supporting his hypothesis that costshare payments have not significantly altered

reforestation investment by NIPF landowners.

Goodwin and others (2002) also finds this to

be the case using aggregate time series crosssection data for several Southern U.S. States.

Finally, Hardie and Parks (1996) examined the

intensity of reforestation in response to CRP

payments in the South. Their results indicated

that sawtimber price, cost-share payments,

household income, size of landholding, technical

assistance, and inheritance of the property

have highly significant positive coefficients.

Sociological Studies

Although this section has focused on

econometric studies, one cannot ignore the large

body of literature that seeks to identify sociological

factors associated with NIPF ownership. This line

of research developed in the 1970s (Egan 1997)

and stemmed from the heightened awareness that

forest landowners often hold land for nontimber

benefits and embrace multiple ownership

objectives. Some recent studies have appeared in

the forestry literature. These include a paper by

Bliss and others (1997), who found that the views

of nonindustrial owners regarding forestry and

environmental issues are similar to those of the

general public, contrary to previous conjectures.

Bourke and Luloff (1993) also provided evidence

that NIPF landowners and the public have

common concerns with respect to forests and

management policies. Johnson and others (1997),

Chapter 22.

 Nonindustrial Forest Landowner
Southern Forest Science:

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246

who considered how NIPF owners view forest

regulations, found that possible future regulations

were not important in landowners’ most recent

harvest decisions. Bliss (1994) argued that

researchers tend to focus too exclusively on the

timber supply question and should instead focus

on landowners as individuals. Egan (1997) agrees,

arguing that the success of forestry assistance

programs is dependent on understanding the

many objectives of NIPF landowners.

NEW RESEARCH DIRECTIONS

T

he preceding review of recent work hints at

many new and fruitful areas for landowner

research. In this section we comment on

several topics that have not been studied but

have important policy implications.

Investigate the Price Acceptance Behavior

of Landowners

Although there are some exceptions, previous

empirical landowner behavior models have largely

focused on estimating probabilities and levels of

harvesting or reforestation. A separate set of

theoretical literature describes how landowners

approach the decision to participate in harvesting

activities [see Fina and others (2001) for a recent

review of this literature]. In this work, the

existence of a “reservation price” is established for

each landowner. A reservation price for harvesting

represents an offer or payment a landowner must

receive before harvesting and selling his or her

timber. Although reservation prices have intuitive

appeal for the timber harvesting decisions, the

reservation price approach should in principle

apply to other landowner market activities, such

as selling land, or converting land use from

agricultural uses to forest production through

reforestation and afforestation efforts.

To date, there has been little empirical testing

and estimation of reservation prices among

nonindustrial landowners. Yet, such research

might be important to predicting future timber

supply obtained from any given landowner or

collection of landowners. This is especially true

for landowners and markets affected by

urbanization or forest parcelization. Many of

these landowners are usually absentee, or are

not actively engaged in harvesting or reforesting

at any one time. The preferences of these

landowners are important determinants of their

reservation prices and hence their propensity

to enter timber markets in the future.

Estimating reservation prices represents a

challenge, as they are unobserved and obviously

functions of both landowner preferences and

market parameters. Only when the landowner

is offered a bid (or observes a market price) that

exceeds his or her reservation price, will the

landowner choose to harvest. Similarly, if the

landowner is offered some payment or incentive to

plant trees on currently open or agricultural land,

the landowner will undertake such an activity only

if the payment is greater than the minimum he

or she is willing to accept for the change in land

uses. This willingness to accept is equivalent

to a reservation price for land use activities,

and like the timber sale reservation price, it will

depend on preferences of the landowner, market

characteristics, and income derived from forest

and agricultural activities.

In some cases, landowners who do not harvest

will never do so, either because their reservation

price path over time is consistently higher than

prevailing market prices and offers, or because

their preferences are such that their reservation

prices are above the practical range of market

prices. Reservation prices capitalize landowner

preferences for timber and nontimber products

and income or wage possibilities. Thus, differences

in attitudes about harvesting and other forest

management activities will be realized through

differences in reservation prices across

landowners. For example, landowners with very

high reservation prices might be those who have

higher incomes, attach higher values to nontimber

benefits, or those who associate higher risk with

establishing forests. In addition, expectations

about the path of future prices (price risk) may

influence reservation prices for harvesting timber.

Ownership type (absentee or onsite owners) and

ownership objectives (land speculation or forest

management preferences) may also have

substantial influences on reservation prices.

The decision to accept any price for harvesting

timber and the decision to switch land use should

depend on variables such as these.

To understand how likely it is that different

types of landowners will eventually harvest, or

understand how various policies will affect the

decisions of landowners to enter the market,

we need to identify the most important factors

affecting reservation prices for different types

of landowners. A similar problem arises when one

considers the participation of landowners in land

use decisions. It is well known that frequent land

sales in already fragmented areas may be
247

contributing to increased parcelization and

decreased prospects for sustainable forest

management, or production of amenities that

require contiguous forest blocks. As with timber,

a landowner’s reservation price for land will give

some indication of whether the landowner will

participate in the land sale market. Reservation

prices for land sales are also important indicators

of landowner behavior and market outcomes with

respect to timber harvesting.

A comparison of reservation prices and market

prices for landowner activities is also needed.

Landowners are price takers. If an individual

landowner’s reservation price for harvesting

is higher than the prevailing market price, then

the landowner will not enter the market.

Understanding the difference between the two,

one of which is observed and the other of which

has to be estimated, will, therefore, give some

indication of how much markets need to change

before landowner harvesting changes by certain

amounts. The difference between reservation

prices and market prices should reflect costs

incurred searching for buyers, differences in

information possessed by landowners and timber

buyers, and specific characteristics of forest tracts

that are valued in the market. Identifying the gap

between reservation prices and market prices will

improve the prediction of future land and timber

sale activity, in that it will provide a means to

determine what type of landowners exist at

the economic “margin,” that is, are closest to

participating in sale activities. It will also indicate

how far certain landowners are from participating

in the market. These landowners would not

typically be included in a sample of landowners

who harvest in any given period.

It is this predictive capacity of empirical

reservation price work that might be the next

contribution to timber supply modeling, or to

forecasting changes in timber availability. Most

landowners in a given sample may not harvest. In

some cases, this may be because their reservation

prices do not coincide with market prices, or in

other cases their timber may not be mature

enough to harvest. In the former case, without

knowing how far landowners are from the margin

of activity, there is no way of knowing how far

landowners are from participating in forest

harvesting. The harvesting and reforestation

choice models reviewed earlier require substantial

data about landowners who have recently

harvested. Landowners who do not intend to

harvest at the time of data collection, i.e., at

prevailing market conditions, and those who

have not harvested in the past, are often treated

in different ways with respect to the prices they

are assumed to face.

How does one estimate reservation prices for

harvesting or for converting land to forest use?

One way is to use a revealed or stated preference

approach in which landowners are given various

offers for undertaking a harvest or land use

activity, and then asked to indicate whether they

would accept or reject the offer. Two versions

of this method have been applied recently. One

version employs referendum voting—a single

price is offered and landowners can either accept

or reject this price. Kline and others (2000)

make use of this approach to determine when

landowners will choose to preserve forests over

a certain time period. The other version is

to use a payment table to offer a range of prices,

and then allow landowners to indicate how likely

they are to accept these prices if offered them.

This approach is taken by Amacher and others

(2001). The advantage of these methods is that

they can be used to identify thresholds for prices

that landowners would accept to undertake some

activity. They can also be used to determine

market prices a given landowner would be

willing to accept for harvesting under varying

probabilities. Thus, both methods can be used

to identify the most important predictors of

reservation prices.

Empirical analysis of reservation prices could

be used to improve targeting of Government

policies in new ways. For example, suppose that

a policymaker wished to achieve a certain acreage

target for land in forests, perhaps in response to a

carbon sequestration goal. Estimated reservation

prices for land use decisions would indicate the

minimum payment landowners would need to

receive in order to achieve the land use target.

Typically, economists assert that the compensation

for converting a unit of land to forests should

equal returns from the current use foregone by

switching. The importance of reservation prices

in this decision is often overlooked, but it is

important when the landowner attaches a value

to the nontimber benefits produced by forests.

For example, a landowner’s preference for

nontimber goods could lower the reservation

price for shifting land to the extent that it is

smaller than the foregone returns from the

current use. A landowner for whom this is true

would be willing to accept a payment that

is smaller than the foregone financial returns

in order to switch land from a nonforest use

to forests. Any Government program seeking

Chapter 22.

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Southern Forest Science:

Past, Present, and Future

Socioeconomic

248

to influence land use behavior at minimum cost

should, therefore, focus on reservation prices,

and not just on lost returns, as reservation prices

better reflect the opportunity cost of switching

land use.

Investigate Importance of

Adjacent Landowners

Forest ecosystems cut across the many stands

that constitute any forest unit. Biologists have

long known this and have argued that trees of

many age classes and species mixes are necessary

for conservation of biodiversity or contiguous

habitat for certain animal species (Franklin and

Foreman 1987, Giles 1978). Forest stands are also

linked by human needs and actions. For instance,

the recreational opportunities presented by larger

forest areas may be dependent on the interaction

or coordinated management of several stands.

Economic models have rarely acknowledged

the interdependence among stands, but it is

a fact of nonindustrial forest management that

management decisions made by the owners of one

stand can affect the welfare of other landowners

holding adjacent stands. One can easily imagine

that the quality of nontimber benefits obtained

from forests, such as wildlife amenities, should

depend importantly on decisions made by adjacent

landowners. It is, therefore, reasonable to expect

that landowners may make decisions concerning

their forests with the effect of their decisions on

adjacent landowners in mind, or in anticipation

of management decisions of adjacent landowners.

There are very few analytical treatments of

the economics of stand interdependence. Stand

interdependence was originally discussed by

Bowes and Krutilla (1985, 1989), who proposed

a linear programming approach for maximizing

the rents associated with multiple stands under

a single (Government) owner. Swallow and Wear

(1993) and Swallow and others (1997) were the

first to formulate explicit spatial interactions for

nontimber amenity benefits between two adjacent

stands. Koskela and Ollikainen (2001) evaluated

the rotation age decision for a landowner who

makes decisions for a single stand under the

assumption of a purely exogenous adjacent

stand. There is also very recent literature on

stand interdependence in other contexts, such

as species conservation.

The extent to which a landowner takes into

account the effects of his or her management

on other landowners is unknown, but it is an

important question. The behavior of landowners

who do not coordinate, or who anticipate actions

of other landowners, could be socially costly.

In fact, the impact of one landowner’s decision on

the forest ecosystem used by another landowner

can represent a type of economic “externality”

associated with private forest management. Only a

social planner who managed the forest ecosystem

as a whole would have incentives to solve for the

economically efficient rotation age of each stand,

conditional on its impacts on all other stands. The

challenge for policy, therefore, becomes finding an

instrument that encourages each landowner to act

as if he or she were a sole owner, managing all of

his or her stands in concert. Such an instrument

would obviously need to target the individual

landowner and, thus, it may not be feasible to

implement in practice. The most efficient

instrument would also depend on the types

of property rights arrangements governing

ownership and management of forest land.

It certainly seems difficult to identify such an

instrument at this stage given our current

understanding of landowner behavior.

In light of this difficulty, empirical work should

be directed at determining how serious lack of

coordination among landowners can be, and also

how various property rights arrangements (full

or partial) affect incentives for landowners to

coordinate actions. The most promising line of

research would seem to involve linking adjacent

stand effects to observed and planned landowner

decisions. This might be achieved through a survey

targeted at groups of landowners, determining to

what extent they view their decisions as important

to adjacent landowners, and how much they

anticipate the behavior of others when making

harvesting, reforestation, and land use decisions.

Most of the social costs associated with lack of

coordination may come from a landowner’s ability

to effectively commit to an action with regard to

his or her neighbors. For example, a landowner

may agree not to harvest a specific area of wildlife

habitat because an adjacent landowner has also

committed to doing so, and because both

landowners are hunters of late-successional

wildlife species. However, in periods of high prices,

one landowner may be inclined to harvest after

such an understanding is reached. This is because

each landowner’s reservation price is specific to

each person’s preferences. Understanding how

landowners react to one another, if they do at all,

will help us understand how landowners respond

to policies targeting use of their forest land.
249

Investigate Substitution Between

Landowner Decisions

Existing literature suggests that we have

considerable understanding about the harvesting

and reforestation decisions of nonindustrial forest

landowners, and some emerging understanding

of other decisions and substitution between

various decisions. What this newer work teaches

us is how other decisions impact harvesting and

reforestation, and why it is important not to

examine one decision, such as harvesting, in

isolation from other decisions. Timber supply

depends on the interaction of all relevant decisions

landowners make. Take, for example, the case of

nontimber activities. Interest in those that are

complementary with harvesting influence behavior

very differently than would interests in nontimber

activities viewed as substitutes by the landowner.

If we do not know how landowners choose

between nontimber activities, then we will have

an incomplete picture of harvesting behavior.

The problem becomes even more complicated

when one considers the interaction of land use,

nontimber activities, and timing of harvesting. For

example, landowners may consider it equivalent to

either forego harvesting for amenities, or simply

bring more land into forest production. Stand

interdependency is also potentially important.

If a landowner can substitute nontimber goods

on adjacent land for production of these goods

on their own land, such as hunting or maintenance

of wildlife habitat quality, then this will also affect

harvesting decisions. Obviously, an important

factor here is the timing of decisions. Provencher

(1997) provides some support for the existence

of this substitution. He argues that linearity

in econometric specifications of nonindustrial

timber harvesting decisions is a troublesome

assumption, as it imposes certain restrictions

on substitutability across decisions and activities

for a landowner and, thus, may not give a complete

picture of the relationships between landowner

decisions and important variables.

Integrate Landowner Models into

Large-Scale Policy Models

Many studies have sought to estimate the

probability that landowners undertake some

activity, such as harvesting or reforestation.

There is now a growing literature about landscape

models (e.g., Wear and Bolstad 1998). Many of

these models are not based on actual landowner

data defining responses of land use to external

market changes. The challenge now is to integrate

landowner response models into larger scale

landscape models that can be used for

policy analysis.

Landscape models may be used to understand

forest fragmentation. Fragmentation of parcels

into smaller units has been associated with

changing landowner characteristics and the

current structure of estate taxation. Arguments

are often made that parcelization of land into

smaller pieces will eventually decrease timber

supplies through reduced land access and higher

wood costs. Fragmentation may also reduce

nontimber benefits by disrupting wildlife

corridors. These changes would also lead to a

different type of forest industry organization,

and could also lead to changes in landowner

composition on large land area scales. Recall

that recent work also establishes that landowner

characteristics are changing. Increasingly,

nonindustrial private landowners are absentees,

and absentee landowners are known to have

different preferences for land and timber

sales than the historically abundant resident

landowners. As we noted earlier, landowner

differences are often realized through

differences in reservation prices for harvesting

or the willingness to leave timber as a bequest.

Clearly, fragmentation and parcelization can

be understood by first integrating models for

predicting landowner behavior into spatial land

use models. Landowner decisionmaking would

then be an endogenous factor driving the spatial

realization of land use change. The benefits from

greater integration of landowner responses into

landscape predictions will be better prediction of

landscape change in response to market changes

or demographic changes in landownership, and

better prediction of the pattern and size of

environmental benefits and costs associated

with landowner and market-driven change.

Expand Our Understanding of Information

Asymmetries Involving Landowners

One assumption made in nearly all empirical

work is that markets are “perfect” in terms of the

information available to landowners. For example,

it is implicitly assumed that landowners have the

same information as timber buyers regarding

prices for harvesting, and they know with

certainty the market desirability of their land.

However, new evidence suggests that landowners

may not have perfect information. Hardie and

Larson (1994) discuss a model in which buyers

Chapter 22.

 Nonindustrial Forest Landowner
Southern Forest Science:

Past, Present, and Future

Socioeconomic

250

and sellers of timber have asymmetric information

with regard to the market. Munn and Rucker

(1994) showed that landowners with access to

consultants tend to obtain higher prices for timber

harvesting than those who do not have such

representation. Most recently, Sullivan and others

(2002), who studied a sample of actual timber bids,

concluded that the competitiveness of a timber

sale, i.e., whether it was negotiated or based on

elicited bids, affects the marginal valuation of

forest land characteristics in the timber price by a

timber buyer.

These studies collectively suggest that

information externalities may be present in timber

markets. Empirical work should continue to

identify the costs to landowners of not having

perfect information. The implications for how

timber markets respond to changes in economic

variables, such as prices, will depend on how

competitive timber markets are. Thus, the existing

literature on landowner responses to external

variables, which assumes that landowners make

decisions on the basis of perfect information, may

be flawed. There is much scope for future

empirical work examining the implications of

information differences to landowner behavior and

timber supply. Such work will give us a better

understanding of the social costs associated with

information asymmetries, and a better

understanding of the scope for Government

intervention in these cases.

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Chapter 22.

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Southern Forest Science:

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Socioeconomic

252

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253

Chapter 23.

Recreation

and Nontimber Forest Products

H. Ken Cordell and

James L. Chamberlain1

Abstract—Research on forest recreation over

the last 60 years has been voluminous. Research

on nontimber forest products (NTFP) has been

much less voluminous. In this chapter the history

of these two tracks of research has been

reviewed. Not all studies are mentioned; rather,

a representative selection of the subject matter

is discussed. Forest recreation research had

its beginnings in the late 1950s within a few

southern universities and with two Federal

Agencies—the U.S. Department of Agriculture

Forest Service and the Economic Research

Service. In these beginnings the challenge was

to shed more light on who recreates, where

recreation occurs, what impacts it has on the

resource, and whether recreation and tourism

is one way to address persistent poverty in

some areas of the South. Through the 1960s

and 1970s, research expanded tremendously,

with greater participation among universities

and public agencies. Not only were practical

problems being addressed, but also advances

in theory and methods were being forged

as the science of forest recreation matured.

Through the 1980s and 1990s, many topics

of management concern and of scientific

concern were addressed as outlets for

recreation and leisure sciences grew and the

needs for scientific information for recreation

management expanded. This recreation

research is reviewed in brief in the chapter

that follows, as is research on NTFPs.

INTRODUCTION

U

nlike recreation research, the study of

nontimber forest products (NTFP) is a

relatively new topic in forestry in the South.

The products of concern are forest plant materials

that may include fungi, mosses, lichens, herbs,

vines, shrubs, trees, or parts thereof. Only a

modest amount of research dealing with NTFPs

has been undertaken over the last 50 years. Most

of this research has focused on describing the

varied uses of the plants, their site requirements,

and other botanical factors. Until very recently,

within the last decade, NTFPs were not well

recognized as a management concern or as

a recreational or commercial pursuit. Much

of the early research focused on defining

and understanding how people used these

products. Currently, more university and

agency scientists are looking at NTFPs from

management, recreational, commercial, and

ecological impact perspectives.

This chapter covers research over the last

five decades in the South regarding two related

but mostly distinct forest uses. The first is forest

recreation. The focus is to overview the research

applied to understanding recreation in forest

settings. The author listed first for this chapter

is principally responsible for the text covering

forest recreation, which, because of the vast

volume of this research, is limited to brief

overviews of what has been accomplished. The

second topic is gathering and using NTFPs.

These products are mostly plant based and do

not include lumber or pulpwood. While gathering

forest products is often recreational, it is different

than almost all other recreational activities

in that it involves removal of natural materials.

The second author is principally responsible

for covering research on this topic.

1

 Senior Scientist and Scientist, U.S. Department of

Agriculture Forest Service, Southern Research Station,

Athens, GA 30602, and Blacksburg, VA 24060, respectively.
Southern Forest Science:

Past, Present, and Future

Socioeconomic

254

Historical Overview of Outdoor

Recreation Research

Prior to the Outdoor Recreation Resources

Review Commission (ORRRC), which started

its work in 1958 and published its results in 1962,

very little forest recreation research had been

done anywhere in the country, especially in the

South. In fact, prior to World War II, there was

little policy or management emphasis, let alone

research, applied to recreational uses of forest

lands, public or private. As demand for outdoor

recreation grew after the war years, however, and

as the U.S. economy rebounded from the war’s

impacts, participating in outdoor activities and

taking outdoor-oriented family vacations grew

rapidly. That growth sparked creation of the

ORRRC and drew national attention to the need

for research to better understand the implications

of this fast-growing phenomenon.

As of the end of 1962, there were six known

outdoor recreation research studies in progress

by university faculty and graduate students

in the South. At that time, a number of university

park and recreation administration academic

departments were creating outdoor recreation

curricula throughout the region. Examples

included Clemson University, North Carolina

State University, the University of Arkansas,

and Texas Agricultural and Mechanical University.

The national visibility of the ORRRC reports

gave energy and justification to these emerging

programs and to building research capacity

within some of them. In these early years,

outdoor recreation research was underway

at the University of Florida, University of

Arkansas, University of Georgia, and at Virginia

Polytechnic Institute and State University. The

topics ranged from income earning potentials of

outdoor recreation in rural areas to management

evaluations of national forests and to recreation

use estimation procedures (Graves 1963).

As with the universities in the South,

Government agencies were just beginning to

institute recreation research programs. The U.S.

Department of Agriculture Forest Service (Forest

Service) and Economic Research Service were

early to establish recreation research programs

in the South (van der Smissen 1963) and elsewhere

in the country. The few scattered publications

beginning to emerge from the Forest Service,

primarily the Southeastern Forest Experiment

Station (SEFES) with headquarters in Asheville,

NC, covered use impacts on developed recreation

sites, hunting and fishing use, private land access

issues, and how to include recreation in forest

management planning. There were two Forest

Service research locations in the South. The

principal one was located in Asheville, NC, and

had as its primary objectives the development of

methods for measuring and predicting recreation

use, mitigating use impacts, and assessing

aesthetic values in forest environs. A second

was located in Raleigh, NC, and affiliated with

the School of Forestry at North Carolina State

University. Its mission was to study outdoor

recreation issues on industrial and nonindustrial

private land. Research of this period by the

Economic Research Service in the South was

primarily focused on examining the potential for

earning income from rural outdoor recreation

development, including forest recreation. The

issue driving this work was the prevalence of

low-income communities and poverty in some

areas in the region.

Historical Overview of NTFP Research

Research on NTFPs is a new topic in forestry

in the South. The products of concern are typically

defined as plant materials harvested from forests

and may include fungi, mosses, lichens, herbs,

vines, shrubs, trees, or parts thereof. Many

plant parts are harvested, including the roots,

tubers, leaves, bark, twigs, branches, fruit, sap,

and resin, in addition to the wood. Until very

recently, within the last decade, NTFPs were not

recognized as natural resources being harvested

from the forests. Historically, the primary focus

of research on these products has been on human

use, botanical identification, taxonomy, and

ecological distribution. Much of the early research

focused on defining and understanding how people

used these products.

The long history of using nontimber products

gathered from the forests of southern Appalachia

is not reflected in the scientific knowledge base.

Native Americans used forest plants as tools, food,

medicine, and religious ceremonial implements.

They used bark for housing, branches and stems

for utensils and tools, and wood for containers

and other household products. Plants and plant

products were fully integrated into and essential

to their personal lives. Much of the knowledge

gained from Native Americans is the foundation

of the herbal medicinal industry today in the

United States (Ody 1993). Over the course of three

centuries, more than 400 medicinal forest products

used by the Cherokee have been documented

(Hamel and Chiltoskey 1975). This traditional

knowledge was shared with early European

settlers, who used the products for personal

use, as well as in commercial trading.
255Chapter 23. Recreation

During the 1800s, the United States and the

NTFP industry changed dramatically. The political

turmoil in the United States during the mid-1800s

increased the need to explore the forests for new

and substitute products. By 1863, due to port

blockades, the South was in dire need of most

medicinal products that previously had been

purchased from abroad. A field surgeon, pulled

from his duties to explore the forest resources

of the Confederate States, reported finding more

than 400 substitutes for medicinal plants that

had been imported from Europe (Porcher 1970).

Porcher (1970) reported that species “to be

collected by soldiers while in service in any part

of the Confederate States” included dogwood

(Cornus spp.) as a quinine substitute, tulip poplar

(Liriodendron tulipifera L.) for fevers, sweetgum

(Liquidambar styraciflua L.) for diarrhea, and

mayapple (Podophyllum peltatum L.) as a

laxative. Beyond this cursory examination to

identify potential medicinal uses, more advanced

research on these products was lacking throughout

most of the next century.

FOREST RECREATION RESEARCH IN THE

SOUTH THROUGH THE 1980S

The following sections cover the history and

accomplishments of recreation research in the

South from the late 1950s through the 1980s.

Five major recreation topic areas are overviewed,

starting with onsite use estimation. The other

four topics include visitor profiles and preferences,

use impacts and carrying capacity, large-scale

assessments, and a variety of other topics such

as economic impacts and private land recreational

access. A primary source for these descriptions is

the proceedings of the Southeastern Recreation

Research Conference (SERR), an annual regional

conference first convened on February 6–7, 1979.

The senior author of this chapter was one of

the original organizers and sponsors of this

conference. Although the SERR does not capture

the full complement of recreation and related

publications done in the South or by southern

researchers, it is a good sampling and is used

here as the major source. SERR was the first of

a number of annual outdoor recreation research

conferences now held in several regions of the

country. The 24th annual SERR was held in Athens,

GA, on February 20–22, 2002. Scientists known to

have been engaged in recreation research in these

earlier years were sent a request to forward their

career publication list for use in developing the

history in this chapter.

Onsite Use Estimation

This area of recreation research was one of

the earliest topics of emphasis in the South, and

elsewhere in the country. In the 1950s, very little

was known about the amount, type, and location

of forest recreation use. The most notable of the

early work to help fill this knowledge gap was done

by the Forest Service recreation research work

unit in what was then known as the SEFES (now

known as the Southern Research Station). The

project was located in Asheville, NC, and George

A. (Jim) James was the first of this unit’s project

leaders. His work in recreation use estimation

methods became very well known and used

nationally. His research focusing on use estimation

was done cooperatively with national forests, State

agencies, and the Washington Office of the Forest

Service. The work progressed along two main

lines—estimating use on developed recreation

sites and estimating use in dispersed forest areas.

The term “dispersed forest areas” refers to the

general forest area accessible by trail, road, or

overland, but having no other development.

Estimating use on developed sites—Research

to develop reliable and cost-effective methods

for estimating recreation use at developed sites

received much attention in these early years of

Forest Service recreation research (James 1971).

Researchers designed and tested methods for

estimating the amount of use, by activity, on

developed sites such as campgrounds and on dayuse sites such as swimming beaches. Correlated

measures such as traffic flow counts or water

metering were monitored to allow updates of initial

onsite count estimates. Some of the earliest work

drew attention to the use of pneumatic traffic

counters to derive estimates of recreation visits

and use (James and Ripley 1963). Monitoring

traffic flows or other use indicators along with

sampling actual use and users is a technique

that became known as double sampling. It is

an approach still much used in use estimation

or other onsite studies, and it is currently being

applied by the Forest Service nationally.

Advancements in these early years included

correlating traffic flows using one or more traffic

counters with simultaneous samples of different

recreation activities and affiliated sites for

ultimately deriving estimates of total use by type

and site. Traffic counts were obtained using singlelocation counters devoted to monitoring traffic

flows at the entrance to a single site. As well,

monitoring proceeded using two or more traffic

counters in tandem on trunk routes to a number
Southern Forest Science:

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Socioeconomic

256

of developed recreation sites (James and Rich

1966). Tests showed that estimates of visits

by activity could be derived for up to eight

developed sites based on traffic counts along

only one trunk road. An extension of double

sampling on developed sites was its application

to estimation of use at visitor information centers

(Cordell and others 1970). In this application,

regression was used to estimate relationships

among use of a visitor center, use of its peripheral

sites, traffic counts, volume of shuttle bus ticket

sales, center entrance counts, and other variables

known to be a function of the number of recreation

visitors flowing through a site or area.

Since the early work by James, Cordell, and

a few others in the 1960s and 1970s (James 1971),

and some work in the early 1980s, little additional

research to develop more efficient techniques for

estimating use of developed sites has occurred

(Siderelis and Tyre 1975). During the 1970s and

into the early 1980s, limited testing of techniques

was done by the U.S. Corps of Engineers,

the National Park Service, and the Forest

Service (Coughlin and others 1978). A level of

accomplishment had been reached which called

for synthesis of earlier work to create handbooks

and guides for application of sampling techniques

(e.g., Mischon and Wyatt 1979).

A modest amount of new work was underway

to take advantage of emerging computer

technology to assist in more efficient sampling,

data collection and management, analysis, and

estimation (Erickson and others 1980). A few

studies sought to evaluate field applications of

various sampling techniques. For example, one

study looked at double sampling as it was being

applied across 34 sites in Region 5 of the National

Forest System (California) and found a number of

misapplications and resulting errors (Tarbet and

others 1982). Additional work in the 1970s and

1980s focused on establishing systems for

maintaining and reporting recreation use statistics

at subregional, regional, or national levels (U.S.

Department of the Interior 1986). Some work

focused on extending application of tested forest

recreation use sampling systems to municipal

settings. For example, Tyre and Siderelis (1979)

reported on instant-count sampling as a technique

for estimating recreation use in municipal

settings. For the most part, however, the methods

engineered for estimating developed-site use and

the double sampling techniques developed by

James and others have persisted as the accepted

state-of-the-art in developed site recreation use

monitoring (Tarbet and others 1982). In the 1970s

and 1980s, attention and interest was beginning

to shift to the more difficult job of estimating

dispersed recreation use.

Recent work pertaining to use of developed

sites has focused on applying existing techniques

of use estimation for national applications to

produce mandated national and regional reports

by the Forest Service and other Agencies. In the

South and nationwide, the National Park Service,

U.S. Corps of Engineers, and Forest Service

have in place advanced systems for estimating

management area, regional, and national scale

use by type of activity and season of the year.

The Forest Service assembled a guidebook on

“Techniques and Equipment for Gathering Visitor

Use Data on Recreation Sites” (Yuan and others

1995). This publication was based largely on early

research done in the South by James and his

associates at the SEFES. Most recently, a national

system has been developed for application on

national forests and is comanaged by the Forest

Service’s Southern Research Station. That

national system is designed to estimate recreation

use across the National Forest System (English

and others 2002). It includes both developed sites

and dispersed areas, and like the guidebook, much

of it builds upon the research done in earlier years

within the SEFES.

Estimating use in dispersed areas and

wilderness—In the late 1950s, the Forest

Service organized and staffed a number of forest

recreation research work units around the country.

Fourteen problem areas were identified as high

priority for these research work units (Van der

Smissen 1963). Of these 14 problem areas, one

was “Determination of Techniques and Procedures

for Measuring Forest Recreation Use.” The

newly formed unit at the SEFES was ultimately

assigned the lead in developing and testing

methods for estimating forest recreation use.

The most challenging problem facing this unit

was that of conceptualizing approaches for

sampling and estimating use in dispersed forest

areas. Dispersed areas then and now constituted

most of the acreage of the national forests, and of

other public lands. It was widely thought that 70

percent of the use of public lands at that time was

dispersed use, as opposed to use in developed sites

such as campgrounds, visitor centers, picnic areas,

and interpretive trails.

Dispersed areas (including designated

wilderness) include large bodies of water,

recreation roads and trails, natural lakes, rivers,

open range, and general forest areas. Use of such
257

areas is typically of low intensity and highly

dispersed and, thus, is difficult and costly to

sample. Examples of dispersed activities include

hiking, backpacking, birding, driving forest roads,

and fishing. One of the first published studies of

dispersed use was done by Cushwa and McGinnes

(1964). This study revealed that a stratified

random sampling approach produced good

estimates of dispersed uses within an area of over

100 square miles in a portion of an eastern national

forest. A second study (James and Harper 1965)

extended these methods to an entire eastern

national forest. Further extensions of such work

included multiple dispersed areas, large bodies

of water, trout streams, trails and designated

wilderness areas (James 1971, James and

Schreuder 1972). Because wilderness is often quite

remote and unmonitored otherwise, affordable

methods successfully tested included use of selfregistration systems and a variety of devices for

counting trail use. There was relatively little work

in development of estimation techniques after the

retirement of James in 1974. H. Ken Cordell, who

took over as project leader in 1976, carried on the

work begun by James. One advancement was

testing and refining the use of directional traffic

circuits using dual-input, time-interval recorders

in forested areas with multiple entry and exit

roads (Erickson and Liu 1982). Research

sponsored by the SEFES provided an evaluation

of use sampling on the Arapaho and Roosevelt

National Forests and the Pawnee National

Grassland (Saunders 1982). Current applications

were evaluated, and updated estimates were

provided to these administrative units of the

National Forest System. Technology for

estimating recreational use in dispersed forest

settings is currently being applied nationally,

employing independent regional samples by the

Forest Service through the Agency’s National

Visitor Use Monitoring System (English and

others 2002). National forests sampled in Region 8

up to the time of this writing include the National

Forests of Florida, the Caribbean National Forest

in Puerto Rico, the Ouachita National Forest in

Arkansas, and the George Washington and

Jefferson National Forests in Virginia.

Visitor Profiles, Preferences, and

Behavior Studies

When the Forest Service established a

national branch of Forest Recreation Research in

1957, its staff was limited and budgets were small.

But the new branch was viewed as important, and

with considerable field support it began to grow.

Cooperative research work units were established

at three universities across the country. One of

the emphasis areas of this growing branch was the

characterization of forest recreation visitors and

their preferences for recreation sites, facilities,

and services.

The need to know more about the visitor

underlay many of the studies in outdoor recreation

in the late 1950s and 1960s. National studies, such

as those done by the ORRRC, pointed out just how

little was known about the recreation participant

of that time (Outdoor Recreation Resources

Review Commission 1962). Use estimation studies

usually devoted some peripheral attention to

describing the visitors being sampled and to

describing generally their preferences for

amenities, facilities, and services. But the results

were far from adequate, especially in probing

visitor preferences for site attributes, facilities,

and other characteristics important in planning

and managing a recreation setting.

The SEFES established a number of studies

to learn more about visitors, their characteristics,

and their preferences. Included were onsite

surveys of campers and users of other types of

developed forest sites. Campers in that period

were predominantly family or extended family

groups on weekend camping trips. Some were

vacationing for 2 to 3 weeks and camping at sites

being studied as part of their multisite travel

agenda. Camping was a fast-growing activity in

the 1960s, growing nationally by 35 percent

between 1960 and 1965 (Cole and Wilkins 1971).

Most southern campers were middle to uppermiddle income, white, and suburban, and they

worked mainly in white-collar jobs.

Campers’ preferences for the makeup and

location of a campsite included features such as

adequate space between campsites for privacy,

and shaded sites close to restrooms, trails, and

swimming opportunities (Cordell and James 1971,

Cordell and Sykes 1969, James and Cordell 1970).

Other visitor profile studies done by the Forest

Service covered day users, water users, and

general forest area users. Then, as today, males

were much more prevalent in these types of

outdoor recreation pursuits, and most recreation

visitors tended to be people living within 50 miles

of the areas they were using.

Other agencies doing work in the South at that

time in the area of forest visitor characteristics

and preferences included the National Park

Service, the Tennessee Valley Authority, the U.S.

Fish and Wildlife Service, the U.S. Corps of

Engineers, and numerous State agencies. While

Chapter 23.

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Southern Forest Science:

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258

these efforts did not always focus on forest

recreation, they nonetheless had direct

implications for forest recreation planning and

management. Studies of hikers indicated that

about 7 percent of the population hiked in the

1960s. Most of those who hiked covered a distance

between 1 mile to just a few miles (Lucas 1971).

Hikers tended to be about evenly divided between

males and females, and they tended to be young,

middle income, and white, with a high school or

college education. Hikers then as now preferred

well-groomed trails, natural settings devoid of

development, destinations for the hike that focused

on some prominent natural or historical feature,

and absence of crowding. Wellman and Buhyoff

(1980b) reported on a study of off-road vehicle

use and social conflict at Cape Hatteras National

Seashore, a problem persisting today and perhaps

growing. Roggenbuck (1979) conducted a field

experiment that provided a usable method for

evaluation of interpretive programs. Buhyoff

and Wellman (1979a) studied environmental

preferences, and Buhyoff and others (1979) took

the study of preferences and perceptions further

to report on the aesthetic effects of southern pine

beetle (Dendroctonus frontalis Zimmermann)

in southern forest landscapes. Wellman and

Buhyoff (1980a) also examined and reported

on the effects of regional familiarity on forest

landscape preferences.

For Federal and State resource management

agencies in the 1960s and 1970s, studies of hunters

and anglers were very prominent and much in

demand (Bond and Whittaker 1971). In these

decades and in earlier decades, hunting and fishing

were viewed as two of just a handful of primary

forest recreation activities and were given

prominence in forest management. James and

others (1969) reported that in the 1960s smallgame hunters’ age averaged in their late 30s,

while the anglers averaged in their early 40s.

Most hunters and anglers had participated in

these activities as youths and most had lived in

rural communities in their youth. Seventy percent

of the population was urban in the late 1960s, and

most hunters and fishermen of that time, as now,

were urban. This is a highly significant change;

the majority of hunters and anglers were known to

be rural in previous decades, when the South was

largely an agrarian region. Both groups of forest

recreationists preferred good road, trail, and

water access; well-managed wildlife and fish

populations; and absence of crowding.

Water recreation, especially river floating and

running, was a fast-growing interest in the 1970s

and into the 1980s. A number of studies examined

river floaters including kayakers, canoers, rafters,

inner-tube floaters, and swimmers. One such

study looked at the characteristics and wild river

management preferences of Chattooga River users

(Howard and others 1977). Wellman and Killeen

(1979) studied the status of existing research and

analyzed social conflicts associated with river

recreation in the Southern Appalachians for the

Forest Service. Another study found that twothirds of Chattooga River users were males and

that they averaged around 30 years old, had some

college education, were mostly in white-collar

occupations, and had a number of previous river

recreation experiences (Townsend and Tarbet

1982). River users, like other forest recreation

users, preferred clean and safe recreation

settings with minimal crowding, good access

to areas and facilities, and lack of interuser

conflicts. Roggenbuck and others2 reported

on the relationships between specialization,

displacement, and depreciative behavior

among canoeists on Virginia rivers. Hammitt

and McDonald (1982b) studied the influences

of experience level as a determinant of choices

in managing recreation resources, such as rivers.

Finally, a number of studies of forest recreation

visitors in the 1970s and 1980s focused on visual

aspects of forest recreation experiences. For

example, Hammitt and others (1984) reported

research on visitors’ visual perceptions and

preferences along forest trails, at scenic

overlooks, and along edge environments in

Tennessee. In these studies, it was found that

trail users preferred seeing small streams and

ravines and that other users preferred varying

viewpoints of interiors, edges, and exteriors

of forest settings. Hull (1988) reported on the

scope and accomplishment of forest visual

quality management and research. Ruddell and

Hammitt (1987) studied visitors to a State park

to identify factors associated with preference for

edge settings.

In other studies dealing with visual preferences,

surveys identified the importance of seeing wildlife

in the overall recreation experience. For example,

2

 Roggenbuck, J.W.; Wellman, J.D.; Smith, A.C. 1980.

Specialization, displacement and definition of depreciative

behavior among Virginia canoeists. 109 p. Unpublished report.

Report to U.S. Department of Agriculture Forest Service,

North Central Forest Experiment Station. On file with: North

Central Forest Experiment Station, 1992 Folwell Avenue, St.

Paul, MN 55108.
259

Hastings and Hammitt (1985) reported that

viewing wildlife was secondary in importance only

to viewing scenery. In addition to seeing wildlife,

visitors also wanted information on the wildlife

they saw. An example of the range of other visual

quality research is work that examined the

aesthetic qualities of forest trees (Cook 1972).

Another example was a study of the influence that

remnants of tree cutting had on overall visual

quality of a forest setting (Cook and others 1985).

It was found that controlling the visibility of limbs,

tops, and other evidence of timber thinning by

mechanically lowering their profiles improved

visual quality as perceived by forest visitors.

Bryan explored more broadly what Americans

wanted in the way of aesthetic qualities from

their forests (Bryan 1976). Buhyoff and others

(1978) worked to clarify land-space architectural

interpretations of people’s landscape preferences,

experimented with manipulating dimensionality

in landscape preference judgments (Buhyoff and

Riesenmann 1979), and noted seasonality bias in

landscape preference research (Buhyoff and

Wellman 1979b).

Use Impacts and Carrying Capacity Studies

(Sites, Trails, and Rivers)

Use impacts on recreation sites—As Federal and

State agencies became more and more engaged in

forest recreation management through the 1950s

and 1960s, and as use levels rose, greater attention

was being paid to the impacts of increasing and

repeated use on the vegetation, soils, and other

conditions of forest recreation sites. In a number

of studies, mostly by Forest Service scientists,

both the deteriorating condition of developed

campsites and results of tests of rehabilitation

options were examined. In one study (Cordell and

Talhelm 1969), trial plantings of various species

of turf grass indicated that such practice would

be ineffective in widespread application aimed at

improving deteriorated recreation sites. Soon after

the test sites were reopened to use, all varieties

of planted grasses were suffering badly from

trampling associated with site use. In another

study, small trees and shrubs were planted on

recreation sites to see if they would grow and

provide visual barriers and vegetative cover

(Cordell and James 1971). Results were mixed,

but mostly the study showed that the benefits of

planting heavily used sites are marginal because

ongoing site use continues to have damaging

effects. Because tests showed that plantings had

little effect, researchers generally agreed that

“hardening” sites with pavement, stone, or other

materials is a better approach for developed sites

such as campgrounds (Cordell and others 1974).

Other work focused more on the effects of

use on trails and forest conditions in general.

Saunders3 studied the effects of recreational

disturbance on the Southern Appalachian sprucefir (Picea spp.-Abies spp.) forests, which were then

and continue to be under pressure from a variety

of insect, disease, air pollutant, and recreation use

factors. Saunders (1979) further studied vegetation

cover differences among randomly selected forest

plots with and without recreation use. Plots

with use showed impacts on vegetation and soil

condition. Lockaby and Dunn (1977) also examined

the impacts of sustained recreation use, but mostly

they focused on forest soil properties in the

eastern Piedmont. Whittaker (1978) compared the

surface impacts of hiking and horseback riding in

the Great Smoky Mountains National Park and

found that they differed significantly in magnitude

on a per-unit-of-use basis. Another study in the

Great Smoky Mountains National Park (Bratton

and others 1979) looked at trail erosion patterns

and overall level of severity of foot traffic impact.

Kuss (1982) studied the effects of footgear and

boot-tread design on trail wear and this led

to reconsideration of tread design by boot

manufacturers. Subsequent work focused on

monitoring processes (Klein and Burde 1991),

including monitoring of impacts at backcountry

campsites and shelters in the Great Smoky

Mountains National Park.

Use capacity and management—Beyond site

use impact research, little work was done on site

and area capacity in the South in the decade of the

1960s. For practical management at that time, the

essential ingredients of capacity decisions were

knowledge of the interrelationships between

management objectives, user attitudes, user

preferences, and site use impacts (Lime 1976).

Although not based on research done in the South,

some of the most definitive work on carrying

capacity, as applicable in the South as anywhere,

was that synthesized by LaPage (1963) and Wagar

(1964). Not until the late 1960s and 1970s did work

on recreation carrying capacity again assume a

high profile.

3

 Saunders, P.R. 1977. The effect of recreational disturbance

on the Southern Appalachian spruce-fir forests. 25 p.

Unpublished report. Paper presented at the third annual

conference on science and research in national parks,

southeastern region, Gatlinburg, TN. On file with: H. Ken

Cordell, Southern Research Station, 320 Green Street,

Athens, GA 30602–2044.

Chapter 23.

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Southern Forest Science:

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260

In 1974, Hammon and others (1974a) began

publishing their work on capacity of water-based

recreation systems. Initially this work focused

on reviewing and digesting existing published

works for application to reservoir management

in the Southeast. Later in 1974, they published

a synthesis and systems-approach interpretation

of the capacity literature as it applied to

management of water-recreation systems

(Hammon and others 1974b). Cordell and others

(1975) published the final part of their research

on water-based recreation systems the following

year. They examined the interrelationships

between spatial distribution of use, user

satisfactions under different use levels, and

apparent displacement of users. From this work

it became clear that beyond some threshold of

use, satisfaction and spatial distribution of use

is significantly altered by increasing system use

loadings. Followup application of this work was

published in 1977 (Cordell 1977) in proceedings of

the River Recreation Management and Research

Symposium in Minneapolis. Overall findings from

this research provided reservoir management

guidelines and pointed out the complexity of

applying standards and quantitative analysis to

capacity questions. However, approaches were

developed that have subsequently been adopted.

Other, more basic research was being conducted

on better defining the concept of carrying capacity

and its theoretical foundations. For example,

Schreyer and Roggenbuck (1978) examined

the influence of experience expectations on

perceptions of crowding as related to the notion

of social psychological carrying capacity of forest

recreation areas. Noe and others (1982) examined

normative responses and norm activation among

off-road vehicle users within a managed seashore

recreation environment. Bryan (1979) studied and

published on potentials of use conflicts in outdoor

recreation as a consideration in capacity planning.

Smith and others (1983) studied and reported on

priorities for river recreation management in the

Southern Appalachians that centered on carrying

capacity and other use issues. Hammitt and others

(1982a) examined perceptions among users of

needs for use management controls and strategies.

As a result of these studies and others around the

country, the concept of capacity evolved to an

understanding that capacity was not some magical

upper limit on recreation visits per unit of time

and space, but that in addition to some range

of persons per unit, it must include visitors’

preferred conditions, which can vary widely

across sites, conditions, and cultures (Chilman

and others 1981).

Further capacity research in the South was

spotty through the 1980s. Chilman was a leader

in advancing the principles of and development

of tools for analyzing capacity questions (Chilman

and others 1989). His work advanced the concept

that capacity is a desired set of conditions that

emphasize quality factors. He developed and

published a revised carrying capacity analysis

system. This work was linked to the evolving

concept of limits of acceptable change (LAC)

(Stankey and others 1985). Absher studied

and found valid application of LAC in planning

wilderness management and capacity

considerations on the Cumberland Island National

Seashore (Absher 1989). Wellman and Belcher

(1989) reported on the nature and importance

of managerial perspectives in determining

appropriate river recreation use policies for the

mid-Atlantic region for the National Park Service.

Large-Scale Recreation Assessments

U.S. Public Law 85–470 established the

ORRRC in 1958 (Outdoor Recreation Resources

Review Commission 1962). The work of this

commission was the first comprehensive, national

scale assessment of outdoor recreation demand

and supply in the United States. Several

were to follow, many of which were done by

recreation research scientists in the South in

the years after 1980. On the basis of ORRRC’s

recommendations, a Bureau of Outdoor Recreation

and the Land and Water Conservation Fund

(LWCF) were created in the 1960s. To be eligible

for matching grants from the LWCF, a State had

to conduct and submit to the Bureau a Statewide

Comprehensive Outdoor Recreation Plan

(SCORP). The bureau and its successor agencies

were also required to conduct and submit to the

Congress a nationwide outdoor recreation plan.

Both the State and national plans required

comprehensive assessments, which were the

source and inspiration for numerous State,

regional, and national participation surveys,

supply studies, demand and needs analyses, and

efforts to build forecasting models. Examples of

the assessment work undertaken in the South are

described in the paragraphs that follow. Examples

are used because this work is too voluminous to

fully discuss in this chapter. Interestingly, that

portion of the 1960 ORRRC national participation

survey analysis that dealt with relationships

between demographics and participation was done

in the South by Charles Proctor at North Carolina

State University (Proctor 1962).
261

Examples of research done at the State level in

the South include work reported by Howard (1968)

of Clemson University. Howard did a statewide

survey of outdoor recreation facilities for the State

of South Carolina. Siderelis, at North Carolina

State University, conducted a modeling study to

develop computerized (mainframe) techniques for

forecasting recreation participation (Siderelis and

Hassel 1975). Jarvis and others (1978) developed

models and forecasts of recreation demand for

the Upper Savannah River Basin as a part of their

work to better assess future outdoor recreation

demand in South Carolina. Roggenbuck (1978)

conducted the outdoor recreation demand survey

for the State of Virginia as a part of that State’s

SCORP assessment. Roggenbuck and Kushman

(1980) studied riparian landowners’ attitudes

toward a State wild river program. Senter and

McLellan (1982) examined the compatibility of

data used in SCORP to describe private recreation

providers for use in statewide planning. There

were numerous SCORP or other statewide

assessment projects in the South in the 1960s,

1970s, and 1980s. Unfortunately, most of these

followed ad hoc formats so there was little Stateto-State compatibility of data.

Regarding national recreation assessment

research originating in the South, in 1977, the

SEFES was assigned by the Washington Office

to conduct nationwide and region-by-region

assessments of recreation demand and supply

under the authority of the 1974 Forest and

Rangeland Renewable Resources Planning

Act (RPA). The first report resulting from this

assigned research was published in the 1980

RPA Assessment report (U.S. Department of

Agriculture, Forest Service 1980). Stemming from

that work was publication of a follow-on national

assessment report published by the American

Forestry Association (Cordell and Hendee 1982).

The Forest Service’s southern research work

unit reported its regional and national outdoor

recreation and wilderness assessment work in

the “Third Nationwide Outdoor Recreation Plan”

published by the Department of the Interior in

1979, the Rockefeller Outdoor Recreation Policy

Review group report “Outdoor Recreation for

America” in 1983, reports by the President’s

Commission on Americans Outdoors in 1986,

and proceedings of the 1988 National Outdoor

Recreation Benchmark Symposium (Siehl 1989).

In continuing to build data and research

capacity for future rounds of recreation

assessments, and to improve coverage of

private recreation supply trends, an examination

of potential conflicts between private recreational

property developments and forest land ownership

and management in the South was conducted

(Cordell and others 1982). Wellman and others

(1980) studied response rates and patterns to

mailed questionnaire surveys and identified the

reluctant respondent as an important survey

target by examining the differences between

early and late respondents. Wellman and Marans

(1981) looked at the use of time budgets as an

aid to research, assessments, and planning for

recreation. Wellman (1987) wrote a book on

wildland recreation policy, and this book included

a discussion of the need for assessments in making

policy and planning decisions.

For the 1985 RPA Assessment update, Cordell

and Hartmann (1984) studied trends in outdoor

recreation in the two decades since the original

nationwide assessment done by the ORRRC

between 1958 and 1960. In examining ways to

assess the overall effectiveness and adequacy of

supply of recreation opportunities, Cordell and

English (1985) studied recreational trip distances

as a criterion for defining relevant supply

inventory radii. Roggenbuck and Ham (1986)

examined the methods and kinds of information

used in recreation management and planning as a

contribution to the nationwide assessment for the

President’s Commission on Americans Outdoors.

Much of the above assessment work was

summarized and used as background material

for the 1989 RPA Assessment (Cordell and

others 1990b). Papers covering work in the areas

of supply conditions and trends, participation

trends, demand forecasting, international demand,

wilderness, and social factors in recreation trends

were published in the 1988 National Outdoor

Recreation Forum (Watson 1989).

In the 1990s, statewide, subregional, southern

region, and national assessment work in the South

continued and even accelerated. The sophistication

of this research has also improved. In 1996, results

of an assessment for the Southern Appalachians

were published (Cordell and others 1996). In 1999,

the Third Nationwide RPA Assessment of Outdoor

Recreation and Wilderness was published (Cordell

1999). In 2002, the “Southern Forest Resource

Assessment” was published, and included a

Southwide assessment of recreation demand and

supply (Cordell and Tarrant 2002). These and

other research efforts over the last 2 1/2 decades

have led to development of a system of data,

Chapter 23.

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Southern Forest Science:

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262

models, and reporting technologies that

is used throughout the country and in many

other countries.

Additional Recreation Research Topics

of the 1980s

Assessing economic impacts—In 1984, a national

meeting was convened by southern researchers

to evaluate abilities to assess the economic impacts

of recreation and tourism (Propst and others

1985). From that meeting came a coalition between

the Forest Service, U.S. Corps of Engineers,

Tennessee Valley Authority, National Park Service,

National Association of State Park Directors,

and other organizations to develop data collection

technology and to improve input-output modeling

capacity for recreation and tourism. The results

of that meeting fed development and improvement

of numerous onsite surveying approaches,

including the Public Area Recreation Visitor

Survey (PARVS) and improvement of the inputoutput economic accounting model. Following

that very positive result, Propst and others

(1986) began applying updated technology by

studying trends in outdoor recreation consumer

expenditures to see if visitor expenditure profiles

are stable over time. Aiken (1988) looked at the

regional economic impacts of visitor spending near

and at the Chincoteague National Wildlife Refuge.

Jackson (1988) evaluated different measurements

of economic impacts associated with recreation use

at U.S. Corps of Engineers projects in the South.

Paterson (1988) examined the usefulness of

economic impact assessment as a tool for regional

tourism development. Watson and Cordell (1988)

discussed use of economic impact assessments

as a means for demonstrating the importance of

outdoor recreation relative to other, sometimes

competing, uses of natural resources. Fritschen

(1989) reported on advances in measuring the

economic impacts of recreation at U.S. Corps of

Engineers water-resource projects, and methods

of accounting for spending associated with users

accessing a reservoir from places outside formally

designated reservoir recreation sites. From data

generated from the PARVS, Bergstrom and others

(1989) examined and estimated rural economic

development impacts of outdoor recreation

in Georgia.

Wilderness research—From its genesis in 1964

and an initial total size of around 9 million acres,

the National Wilderness Preservation System

(NWPS) has grown to more than 106 million acres

of public land managed by four Federal Agencies.

Fifty-six percent of National Park Service lands,

20 percent of U.S. Fish and Wildlife Service

lands, and 18 percent of Forest Service lands

are in designated wilderness status. The Bureau

of Land Management has only 5 million acres

of wilderness, but has 17 million acres set aside

as wilderness study areas. A modest amount

of research regarding wilderness management

and the status of the NWPS has been conducted

in the South. Some of that work is summarized

in this chapter.

Roggenbuck and Berrier (1981) studied

communication techniques for dispersing

wilderness campers, and in related work

Roggenbuck and others (1982a) looked at the

role of interpretation in managing recreational

carrying capacity. Roggenbuck and others

(1982b) studied wilderness management as

it was practiced in the Southern Appalachians

in the early 1980s.

Cordell and others (1986) summarized previous

studies of visitor needs and user impacts in

wilderness in the East. Watson and others (1987)

examined techniques for producing accurate

wilderness use estimates, using some of the

dispersed-use methods described earlier in this

chapter. Hartmann and others (1987) conducted

regional comparisons of Forest Service wilderness

users with an emphasis on eastern wilderness

users and the implications for further policy and

research refinement. Region-to-region differences

were small. Roggenbuck and Watson (1989)

summarized the wilderness recreation use

situation in the region and nationally for the

Outdoor Recreation Benchmark meeting held

in Tampa, FL. Watson and others (1989) studied

visitor characteristics and preferences on three

national forest wilderness areas in the South. Most

such studies were of particular wilderness areas in

the South and focused on wilderness visitors. From

these and other studies, much has been learned

about wilderness use, wilderness visitors, and

wilderness management options. Management

and policy for wilderness in the region and to some

extent nationally has been much influenced by

the information flowing from this research.

Based in part on this earlier work, Cordell and

Watson (1987) conceptualized a framework for

wilderness assessments and related future

research. Reed and others (1989) wrote regarding

optimizing nonrecreational wilderness uses and

values as a contribution to ongoing wilderness

system assessment. Watson and others (1989)

summarized the knowledge of the characteristics
263

of wilderness users. Cordell and others (1989)

summarized research on marketing based on

research pertaining to wilderness experiences.

Private land recreational access—As in the

North, industrial and nonindustrial private land

dominates in the South, relative to public land in

Federal or State ownership. Most of the forest

science dealing with private owners and lands

has focused on timber supply potentials and the

effectiveness of a variety of incentive programs

for nonindustrial owners. In more recent studies,

reference is given to the increasing recognition

given by landowners to the amenities of their land,

relative to the income-earning potentials of these

lands. The rising relative importance of amenities

has been acknowledged by its assuming a much

higher profile in private land research (Amacher

and others 2004). Research from the mid-1980s

on has typically given full recognition to the rising

importance of amenity values (Boyd and Hyde

1989, Hyde and Newman 1991).

Little of the early research on private lands and

owners focused specifically on the issue of public

recreational access or use. Of the limited research

that was undertaken, prominent was research

on landowner liability (Kaiser and Wright 1985,

Kozlowski and Wright 1988) and access rights

(Gramann and Bonnicksen 1985). Other studies

examined the relationship between timber or other

income-earning motives and recreation, (e.g.,

Jones and Self 1991).

As part of the RPA national assessment of

outdoor recreation, work was begun in the South

cooperatively with Clemson University to develop

a national database on recreational use and access

to private lands. The first resulting national

survey to determine public outdoor recreation

opportunities on nonindustrial private forest

and rangelands was conducted in 1975–76,

cooperatively with Clemson University and the

Soil Conservation Service (Cordell and Stevens

1984). Based in part on this work, a study of trends

in recreational access to private rural lands

was reported in 1985 (Cordell and others 1985),

and a study to validate procedures for the next

nationwide survey of private landowners, to occur

in 1985–86, was conducted in 1984 (Sale and others

1987). Results of that next national survey, done by

the SEFES, were reported in several sources and

used in the 1990 RPA Assessment (Cordell and

Wright 1989, Wright and others 1989). In all these

studies, access for persons not associated with the

owner by way of family or other close personal

relationship was quite limited and found to be

diminishing over time in all regions of the country.

In the South, this diminishing access was found

in part to be offset by increased leasing by persons

unrelated to the owner.

Behavior, perceptions, and motivations—

A significant number of scientists studying forest

recreation in the South have been trained in social

psychology theory and methods. A more limited

number are grounded in either sociology or

economics. The makeup of studies of behaviors,

perceptions, and motivations among outdoor

participants reflects the disciplinary backgrounds

of the scientists who conducted those studies.

Some examples of the numerous examinations

and rich literature on behaviors, perceptions,

and motivations follow. One notable early

publication was written by Bryan (1977); it

concerned specialization among trout fishermen

and the implications of the findings for resource

management. Groves and others (1975) presented

a multiframe reference approach to studying

and better understanding leisure motivations.

McLellan and Gahan (1976) studied recreation

user characteristics and behaviors on Hartwell

Reservoir in South Carolina. Hull and Buhyoff

(1982) reported on the effects of distance on the

perception and rating of scenic beauty. Wellman

and others (1981) studied the accuracy of

predictions by park managers of the motivations

of visitors to two National Park Service areas.

Burrus-Bammel and others (1982) reported on

a study of the perceptions of hunting and hunters

by various groups. Burrus-Bammel and Samuel

(1984) also studied the sources of introduction to

and motivations for wild animal trapping.

There were a wide array of places and

recreation settings where behavior, perceptions,

and motives were studied. In 1982, Mulligan and

others reported on the interactive effects of

outdoor noise and visible aspects of vegetation on

behavior in urban settings. Noe and others (1982)

examined perception of conflict between off-road

vehicle and non-off-road vehicle users in a leisure

setting. Ruddell and Hammitt (1985) studied

motives for visiting a South Carolina State

park and provided interpretations for visual

management of park edge environments. English

and Cordell (1985) conducted a cohort-centric

analysis of outdoor recreation participation

trends and found significant cohort effects on

participation behavior changes. A comprehensive

coverage of studies done on behaviors in the

South in the 1980s is too voluminous to cover in

this chapter, but suffice it to say that this work

has had profound impacts on forest recreation

management in the region.

Chapter 23.

 Recreation
Southern Forest Science:

Past, Present, and Future

Socioeconomic

264

RESEARCH IN THE 1990s

F

ollowing is an overview of some of the outdoor

recreation and related research published

between 1990 and 2002. Much of it was

sponsored by Federal Agencies, some by State

agencies, and other by private interests.

Broad-Scale Assessments

In 1990, broad-scale assessment work was

continuing, mostly stemming from the Forest

Service’s RPA assessment work. Cordell and

others (1990b) produced their third nationwide

assessment of outdoor recreation and wilderness

demand and supply trends. Findings indicated

rapid and continuing recreation demand growth

in the United States. An important finding was

that participation is growing at significantly

different rates among different ethnic groups, in

different regions, and between different activities.

In 1991, as national and regional demand and

supply assessment work progressed, focus moved

to technical aspects such as methods and data

for assessing demand and supply (Cordell and

Bergstrom 1991), estimating demand functions

(Peterson and Cordell 1991), and inventory

approaches for broad-scale database development

(Burkiewicz 1991). In the 1990s as never

before, there was growing awareness of the

unprecedented social change taking place,

and studies were being initiated to look at the

consequences of these changes. For example,

Murdock and others (1992) studied the

implications of demographic change for

fisheries management and fishing.

A number of assessment studies dealt with

marketing and markets for outdoor recreation.

Examples include English and others (1993)

reporting on regional market projections,

Miles and others (1993b) studying a proposed

segmentation framework for outdoor recreation

markets, Bayless and others (1994) assessing

the market demand for wildlife viewing sites,

and Miles and others (1993a) reviewing

environmental attitude scales and their utility

in consumer marketing. As updates to the 1990

RPA Assessment, Cordell and others (1993)

studied the effects of rural land subdivision on

public recreation access, and English and Cordell

(1993) examined the utility of the Marion Clawson

concept of effective recreation opportunity

indexing, an important step in assessing the

adequacy of supply. In the early 1990s, use of

Geographic Information Systems (GIS) in outdoor

recreation planning and assessment was taking

hold. One of the early works was by Chubb and

Hammitt (1993), who developed a GIS procedural

manual for the Blue Ridge Parkway. In 1994,

additional broad-scale assessment work by

Bergstrom and others (1994) examined the use and

potential future of the RPA assessments of outdoor

recreation among managers and policy personnel

in the Forest Service. During 1995 and 1996, a

number of studies were reported that dealt with

identifying who the recreation participants and

potential participants are as information essential

to effective marketing. Bixler and others (1995a)

wrote concerning getting the novice into natural

environments as a way of introducing a broad

base of the population to those environments.

In 1995 and 1996, broad-scale assessment

work continued, with Cordell and others (1995)

reporting on long-term outdoor recreation

participation trends, Flather and Cordell

(1995) publishing an analysis of historical and

anticipated trends in wildlife-related recreation

activities, Cordell and others (1996) assessing

the demographic and economic changes underway

in the Southern Appalachians, and Hayden and

others (1996) assessing outdoor recreation demand

and supply in the Southern Appalachian region.

This last work was part of the comprehensive

Southern Appalachian Assessment of forest

resources. Other studies in 1995 and 1996 included

Lewis and others (1995), which segmented outdoor

recreation markets using behavioral data, and Hull

and others (1996), which dealt with the ebb and

flow of brief leisure experiences. In 1997, Cordell

and others (1997b) profiled participants in fishand wildlife-related outdoor recreational activities

in the United States, Teasley and others (1997)

studied the use of private lands in the United

States for outdoor recreation, and Cordell and

others (1998a) described trends in outdoor

recreation and their implications for private

land management in the East. The third national

survey of private landowners was done in 1996

and used in the 2000 RPA Assessment, as well

as being published in other places (Teasley and

others 1999). Hull (2000) looked at romantic biases

in natural areas recreation management and

has written extensively about the concept

and application of forest aesthetics (Hull and

others 2000).

As a result of the nationwide surveying of public

participation for the RPA assessment, several

spinoff studies were published. They included

Cordell and others (1999) describing the rapid and

substantial growth in popularity of birding in the

United States, based on the National Survey on

Recreation and the Environment (NSRE) data;
265

Cordell and Super (2000) describing trends

in Americans’ outdoor recreation participation

across a wide range of activities; and Fly and

others (2000) looking at knowledge of and

attitudes, which were mostly favorable, toward

wilderness in the Southern Appalachian ecoregion.

Followup studies of recreation participation, and

especially participation in birding, included

estimating recent trends in participation by

Cordell (2001) and by Cordell and Herbert

(2002). Fedler and Ditton (2001) looked at factors

associated with taking up or dropping out of

recreational fishing participation. Other broadscale research included Robertson and Hull (2001),

which reported a case study of the nature of

landscape perceptions at Whitetop Mountain.

It also included publication of work to assess

public understanding of nature, especially local

knowledge of what constitutes natural forest

conditions (Hull and others 2001).

Social Group Differences

The growing diversity of the population

in the region prompted a number of studies of

social group differences. Recreation participation

differences by race were studied by Brown (1994)

and Miles and others (1994) who studied AfricanAmerican participation patterns in forest and

other wildland outdoor recreation activities. Bixler

and others (1995b) looked at negative perceptions

of natural environments among various social

groupings, especially by race, and how these

perceptions related to preferences for outdoor

activities. Floyd and others (1995) studied the

effect of race on environmental and recreation

preferences, and Ditton (1996) reported on

work aimed at understanding diversity among

largemouth bass anglers. Betz and others (1998)

compared amenity uses and recreational access

among social strata making up U.S. private

landowners, Bowker and Leeworthy (1998)

studied the effects of ethnicity in recreation

demand estimation, and Johnson and others

(1998) examined marginality and ethnicity in

outdoor recreation in the rural South, and

compared inner city and rural residents. Tarrant

and Shafer (1998) compared preferred experiences

and setting conditions of eastern and western

wilderness areas.

In the later 1990s, Tarrant and Cordell (1999)

helped bring more visibility to the issue of

environmental justice in recreation management

by looking at the spatial distribution of outdoor

recreation sites relative to residence locations

of different social groups. Johnson and Bowker

(1999) compared onsite wildland activity choices

among African-Americans and white Americans

in the rural South and described the management

implications of their findings. Bowker and others

(1999) conducted a national assessment of the use

and predicted effects of user fees for recreation

services on public lands, including equity

considerations. English and others (2000)

continued to study economic effects of dependence

on tourism on communities in the rural South and

elsewhere. Bixler and Morris (2000) identified

factors differentiating participants in water-based

wildland recreation from nonparticipants and

interpreted the implications of this work for

recreation activity instruction provided to different

social groups. Porter and Tarrant (2001) conducted

a case study of environmental justice related to

Federal tourism sites in southern Appalachia;

Cordell and others (2002) examined cultural

emphasis on recreation and the environment;

Hunt and Ditton (2002) described freshwater

fishing participation patterns among racial and

ethnic groups in Texas; Krause (2001) described

the roles played by dogs in solo recreation by

women; and Johnson and others (2001) examined

constraints on outdoor recreation by race, gender,

and rural dwelling across regions of the country.

Economic Studies

As a follow-on to the important work of the

1980s to improve data and models for economic

impact research, a number of secondary economic

effects studies were reported. These included

Bergstrom and others (1990b) who looked at

economic impacts of State parks on State

economies in the South; Clonts and others

(1991) who studied economic impacts of hunting

land access; and Cordell and others (1990a)

who estimated the economic effects of river

recreation use on local economies in the Southern

Appalachians. Bergstrom and others (1990a)

looked at the economic impacts of recreational

spending on rural areas of the South. All of these

studies found modest income and employment

multipliers and modest overall income and

employment impacts.

Economic impact research continued in

the early 1990s, and began to focus more on

applications of technological improvements

brought about by the work done in the 1980s.

Examples include Cordell and others (1991), who

looked at the effects of outdoor recreation on State

and local economies in the South; Lee and Propst

(1994), who studied the benefits of segmentation to

reduce variance in estimates of spending profiles;

Chapter 23.

 Recreation
Southern Forest Science:

Past, Present, and Future

Socioeconomic

266

Watson and others (1991), who studied the impacts

of resource-based tourism on local economies; and

Cordell and others (1992), who estimated economic

growth stimulus from State park management.

Other economic impact studies in the early 1990s

included Betz and Perdue (1993), on the role of

amenity resources in rural development. English

and Bergstrom (1994) studied the links between

recreation site development and regional economic

impacts. Hawks and Bowker (1994) estimated the

local economic impacts of lake recreation in

northern California using approaches developed

in assessing lake recreation impacts in western

North Carolina.

Later in the 1990s, Bergstrom and others

(1996) studied the effects of reservoir aquatic

plant management on recreational expenditures

and regional economic activity, again using some of

the same approaches used in the earlier research

in western North Carolina. In 1995, English

questioned the widespread belief that resourcebased recreation was a major solution for rural

economic growth because of limited impacts often

associated with rural recreation. English and Thill

(1996) assessed methods for estimating regional

economic impacts of recreation travel where

survey data are limited. Cordell and others

(1997a) estimated the economic effects on the

regional economies of the Rocky Mountains and

Appalachians of outdoor recreational visits and

spending associated with use of Forest Service

sites. English (2000) calculated confidence

intervals for regional economic impacts of

recreation by bootstrapping visitor expenditures,

a much needed addition since most impact

estimates do not consider confidence intervals

on the estimates. English and others (2000) also

examined tourism dependence among counties

in rural America. In all of the above cited studies,

as with numerous other studies not covered here,

economic impact and interdependency effects were

found to be important to local economies; but

unless the recreation visitation is substantial and

sustained throughout the heavy-use season and

the rest of the year, and unless the local economy

is reasonably diverse and well developed, those

effects are almost always modest.

Other economic studies focused on demand for

and valuation of outdoor recreation experiences

and sites. Prominent examples included work

based on results from the 1990 RPA Assessment,

such as Bergstrom and Cordell (1991), which

reported an analysis of the demand for and value

of outdoor recreation in the United States, and

Cordell (1992), which reported on amenity,

conservation, and environmental values in the

United States. Other “demand” studies looked

at revenue capture potentials from charging fees

(Teasley and others 1993), measurement of

recreation benefits using contingent valuation and

the question whether the payment vehicle matters

(Bowker and others 1993), and recreation use

values for alternative reservoir water-level

management scenarios (Cordell and Bergstrom

1993). Bowker and others (1994) looked at

sensitivity of contingent valuation estimates of

recreation trips to the elicitation approach used,

and English and Bowker (1994) examined an

alternative technique for estimating the demand

for river outfitter services. Choi and others

(1994) studied the influence of various intervening

variables in recreation substitution decisions, an

area important in valuation and other behavioral

studies. Siderelis and Moore (1995) estimated the

net benefits of recreation use of rail trails.

In the second half of the decade of the 1990s,

Bowker and others (1996) estimated values for

guided rafting trips on southern rivers, and

Siderelis and others (1995) developed a boating

choice model for the valuation of lake access.

Economics research during 1997 and 1998

indicated progress in methods and attention to

important resource issues. Examples included

Bowker and others (1997), who conducted a

demand analysis of off-road motorized recreation;

Leeworthy and Bowker (1997), who estimated

nonmarket economic user values in the

environmentally sensitive Florida Keys; Bhat

and others (1998), who tested an ecoregional

approach to the economic valuation of landand water-based recreation in the United States;

and Siderelis and Moore (1998), who estimated

the influence of site preference variables on

recreation demand. Bowker and others (1998)

studied benefits transfer and count data travel

cost models. Zawacki and others (2000) used a

travel cost analysis to examine nonconsumptive

wildlife-associated recreation participation, and

Siderelis and Moore (2000) developed approaches

for incorporating perceptions by users of site

quality into recreation travel cost models. In all

of the above demand and valuation research, net

benefits were found to be substantial, valuation

methods reliable, and recreation demand overall

somewhat price sensitive.

Motivations, Perceptions, and Behaviors

Studying recreation use, users, motivations,

perceptions, and other aspects of participation

in the outdoors continued as an important topic
267

in the 1990s. Roggenbuck and others (1990a)

studied the learning benefits from leisure. Hull

(1990) studied mood as a product of leisure, its

causes and its consequences. Chilman and others

(1991) reported on design of recreation monitoring

systems using participant observers. Cornell and

Leary (1991) examined family participation in

developed camping. Patterson and Hammitt (1990)

studied back-country encounter norms, actual

encounters, and their relationship to wilderness

solitude. Van Cleave and others (1991) looked at

attitudes of summer visitors to the Great Smoky

Mountains region. Roggenbuck and others (1991)

applied encounter norms in a study of river float

trips and as a result questioned the use of the

social norms concept. Hull (1991) contributed

research on mood as a product of leisure and as

a predictor of visitor satisfaction. Caldwell and

others (1994) studied zoo visitors’ satisfactions.

Bixler and others (1992) examined restrictive

and nonrestrictive approaches in recreation

management. Hammitt and Shafer (1992)

analyzed visual dimensions for parkway planning.

Stewart and Hull (1992) compared the post hoc

and real-time construct validity of the concept

of satisfaction. Adams and Hammitt (1993)

reported on behavior in relationship to

interpretive encounters with wildlife. Hammitt

and Patterson (1993) looked at use patterns and

solitude preferences of shelter users in back

country. Shafer and Hammitt (1993) examined

effects of management conditions on wilderness

recreation experiences. In 1994, Fedler and Ditton

reported on angler motivations in fisheries

management. Hammitt and others (1994) studied

approaches to identifying and predicting visual

preferences for Southern Appalachian forest

recreation vistas. Hull and Michael (1994) looked

at the relationship between nature-based

recreation, mood change, and stress restoration.

Rutlin and Hammitt (1994a) examined functions of

privacy in the Ellicott Rock Wilderness. Rutlin and

Hammitt (1994b) also surveyed users and use

patterns of Ellicott Rock Wilderness visitors.

Schneider and Hammitt (1995) studied visitor

response to outdoor recreation conflicts. Shafer

and Hammitt (1995) examined congruency among

wilderness experience dimensions, condition

indicators, and user coping behaviors. Examples of

later visitor studies included Frauman and others

(1997) on the application of means-end theory to

understanding interpretive service users, and

Noe and others (1997) on park user perceptions

of resource and use impacts. Research covering

river recreation included Tarrant and others

(1997), who examined the effects of situational and

personal factors in measuring perceived crowding

for high-density river recreation; Tarrant and

English (1996), who developed a crowding-based

model of social carrying capacity for application to

recreational boating; and Hammitt and Lin (1997),

who examined the literature on establishing uselevel standards for river recreation. Onsite use

studies included Symmonds and others (1999)

on recreational carrying capacity for managing

mountain bike use in the Southern Appalachians,

and Thigpen and Siderelis (2001) on the use of

paddle trails in coastal North Carolina. Walker and

others (1998) studied onsite optimal experiences

and their relationship to offsite benefits. Tarrant

and others (1999) provided a summary of onsite

research on motivations, attitudes, preferences,

and satisfactions among outdoor recreationists.

Onsite studies included Schuster and Hammitt

(2000) on stress experienced by visitors and

reported hassles in the Shining Rock Wilderness

Area and Schuster and others (2001) on rock

climbers’ attitudes toward the management and

use of bolts. Siderelis and Moore (2000) studied

and modeled the effects of perceptions of site

quality as a determinant of recreation trip choices.

Wilderness Research

Wilderness continued as a topic of focus in the

1990s. Roggenbuck and others (1990b) examined

the wilderness classification process and its

application to land management. Hammit and

Patterson (1991) considered coping behaviors

in relation to wilderness users’ desire for greater

privacy. Hammitt and Dulin (1991) reported on

the significance of encounters with wildlife during

wilderness visits. Roggenbuck and others (1993)

reviewed relevant research on defining acceptable

use, resource, and other conditions for wilderness.

Hammitt and Rutlin (1995) developed use

encounter standards and estimated relational

curves for evaluating achieved privacy in

wilderness. Tarrant and others (1995) identified

factors affecting visitor evaluations of the noise

and visual intrusiveness of aircraft overflights

of wilderness.

In 1997 and 1998, a moderate amount of

wilderness research was done in the South.

Tarrant and Shafer (1997) looked for uniformity

of condition indicators used in wilderness

management; Walker and others (1998) studied

the relationship between onsite experiences and

offsite benefits; Hammitt and Rutlin (1997) wrote

concerning how well visitors achieved privacy

in wilderness; and Johnson and Bowker (1997)

Chapter 23.

 Recreation
Southern Forest Science:

Past, Present, and Future

Socioeconomic

268

presented data on wilderness awareness and

potential participation in wilderness recreation

across diverse social groups. In other research,

Cordell and others (1998b) examined survey

results indicating how the public values wilderness. Cordell and Teasley (1998) reported on

estimated recreational trips to wilderness, using

the NSRE. Cordell and Stokes (2000) wrote about

the importance of wilderness as a social value held

broadly across the U.S. population, while Hammitt

and Schuster (2000) speculated on potential for

growth of wilderness use in the next 100 years.

Roggenbuck and Driver (2000) provided an article

on the benefits of nonfacilitated, i.e., individual,

uses of wilderness. Fly and others (2000) examined

knowledge of and attitudes toward wilderness

among persons living in the Southern Appalachian

region. A national assessment of the values of

wilderness began in 2003 and is being led by the

Forest Service research group in Athens, GA.

Methods

Studies were also progressing to develop

research tools. For example, Chubb and others

(1991) reported on work using GIS technology

for integrating multiple management datasets;

Henderson (1994) reported on the growing use

of qualitative data methods; Chilman and others

(1994) developed approaches for monitoring

off-road vehicle riding areas; Janiskee and others

(1994) reported on inventories of rails-to-trails

resources; and Siderelis and Roise (1991)

developed optimal strategies for managing

park operations.

Also being reported were advances in methods

and theory. For example, tests for homogeneity

across waves of mail surveying were reported

by Choi and others (1992); tests for the validity

of photo-based scenic beauty judgments were

reported by Hull and Stewart (1992); Hull

and Stewart (1992) also reported on their

examination of the construct validity of the

concept of satisfaction; and work was completed

that examined recreation specialization as a

social conceptualization (Ditton and others

1992). Further work on specialization included

investigation of the relationship between

constraints and specialization (Norman

1992). Wood and others (1996) identified the

determinants of satisfaction for participants

where quality deer management is practiced.

Research evaluating recreation opportunities

and visual aspects included Buhyoff and others

(1995), which examines the validity and reliability

of expert visual assessment approaches.

Later in the 1990s, several additional studies

were carried out. Tarrant and English (1996)

estimated a crowding-based model of social

carrying capacity to be applied to river

recreational boating management. Siderelis

and Perrygo (1996) applied the concept of

recreation benefits to neighboring sites for

assessing riparian rights. Overdevest and others

(1997) operationalized place attachment through

mapping and planning for place values on national

forests. Buhyoff and Miller (1998) evaluated an

expert system for assessing visually perceived

values of landscapes. Borrie and others (1998)

studied the use of verbal reports by study subjects

in recreation research. During 1999 and 2000,

methods studies included Tarrant (1999), on

variability of a perceived crowding scale, and

Tarrant and Green (1999), on the validity of

outdoor recreation as a predictor of environmental

attitudes. Tarrant and Cordell (1999) employed

GIS technology to analyze the environmental

justice implications of the spatial distribution

of outdoor recreation sites in the Southern

Appalachians. Porter and Tarrant (2001) extended

our understanding of the usefulness of GIS in

studying environmental justice related to

Federal tourism sites in southern Appalachia.

NTFP RESEARCH IN THE SOUTH

S

outhern forests provide many products that

are plant based, but that are not timber. Long

before advanced technology existed to harvest

timber, people collected natural forest materials

for various uses. While research on timber

harvesting and managing forests for wood

products expanded greatly during the 20th century,

studies of nontimber products and uses were

few. Today, many local collectors can track their

heritage and relationship with NTFPs back

several generations. The collection and trade

of these products are important to the economies

of Appalachian and other southern households and

communities. But, in addition, the plants are also

critical components of healthy forest ecosystems.

Over the last decade, demand for and collection

of nontimber products has increased significantly.

Because of this increased demand, there has

been growing concern about the sustainability

of NTFPs and the effects of increasing harvesting

on ecosystem sustainability.

Defining NTFPs

NTFPs are plants, parts of plants, fungi, and

other biological materials that are harvested

within and on the edges of natural, manipulated,
269

or disturbed forests. They may include fungi,

moss, lichen, herbs, vines, shrubs, or trees. Many

different plant parts are harvested, including

roots, tubers, leaves, bark, twigs and branches,

fruit, sap and resin, and wood (Chamberlain and

others 1998). One useful method of classifying

these products organizes them into four major

product categories:

1. Culinary products include mushrooms, ferns,

and the fruits, leaves, and roots of many plant

species. Perhaps the most important of the

Southeast’s culinary forest products are ramps

(Allium tricoccum Ait.). Another important

culinary species, black walnut (Juglans nigra

L.), which is native to the Eastern United

States, also is used in the medicinal and

dietary supplement industry.

2. Wood-based NTFPs are produced from

trees or parts of trees, but not commercially

sawn wood. Some of the more important woodbased NTFPs include the stems of sassafras

(Sassafras albidum Nutt.) for walking sticks,

willow (Salix L.) stems for furniture, and the

knees of cypress (Cupressus L.) for carvings.

3. Floral and decorative products include

crooked-wood [Lyonia ferruginea (Walt.)

Nutt.] from the forests of Florida to

compliment dry flower arrangements,

grapevine for wreaths and baskets, and galax

(Galax urceolata L.) for a variety of uses.

Moss harvested from hardwood forests of

Appalachia is used domestically and exported

to the European floral industry.

4. Medicinal forest products include roots and

herbaceous materials from more than 50 plant

species, and are used for a variety of medicinal

or dietary applications.

Research

A modest amount of research dealing with

NTFPs has been undertaken over the last 50

years. Most of this research has focused on

describing the varied uses of the plants, their site

requirements, and other botanical factors. Some

of the more popular products have had extensive

research, although most of the research focuses

on areas tangential to forestry and forest

management. For example, there is a large

body of knowledge about the medicinal uses

of plant species, but forest managers lack basic

knowledge about the population biology and

ecology of many of the plants that are harvested

as nontimber products.

A modest amount of research has focused

on personal use and recreational collection of

nontimber products. Prominent among recent

work is the 2000–01 NSRE conducted by the

Forest Service. Specific questions were asked

of respondents to the NSRE concerning their

gathering of products from forests (Cordell and

Tarrant 2002). The specific trigger question asked

was, “During the past 12 months, did you gather

mushrooms, berries, firewood, or other natural

products?” In the South, 31 percent of the

respondents reported that they gather natural

products. Of these, almost 54 percent did their

gathering activity in a forest setting. Over 96

percent did their gathering for personal use and

only 2 percent did it for income. Nine percent of

gatherers collected mushrooms, 47 percent picked

berries, 73 percent collected firewood, 35 percent

collected rocks and minerals, 43 percent tree

materials, and 43 percent herbs and flowers.

Among the many miscellaneous things gathered

were insects, feathers, walnuts, arrowheads, gold,

moss, pine needles, Spanish moss, water, wild

honey, and sea shells. Over the last 12 months,

29 percent had gathered on 3 or fewer days; 34

percent had gathered on 4 to 10 days; and about

11 percent had gathered on 30 or more days.

The demographics of people collecting for

personal use are enlightening. Forty-two percent

of the people gathering were male and 58 percent

were female. Thirty percent were under age 35

and 20 percent were 55 years or older. Eighty-six

percent were white, 9 percent black, 3 percent

Hispanic, 2 percent American Indian, and the

remaining < 1 percent Asian Americans. By

income, the largest group (36 percent of gatherers)

earned between $25,000 and $50,000 per year.

The next largest group earned between $50,000

and $75,000 (about 17 percent). Those earning

< $15,000 per year made up just over 1 percent

of all gatherers in the South. Forty-one percent

of gatherers live in rural areas and 59 percent in

urban areas. Almost 12 percent of gatherers had

less than a high school education; and 59 percent

had some college, up to a doctorate.

Other research has looked at the major

products resulting from gathering. The large

number and diversity of plant species that yield

NTFPs make this research challenging. Krochmal

and others (1969) identified more than 125

medicinal plant species specific to Appalachia.

Botanists of the Forest Service estimate that

approximately 35 species of medicinal plants are

collected for commercial purposes in the National

Forests in North Carolina (National Forests

Chapter 23.

 Recreation
Southern Forest Science:

Past, Present, and Future

Socioeconomic

270

in North Carolina 2000). Discussions with

medicinal plant dealers in the region reveal that

approximately 50 species native to the area are

commonly collected. Culinary forest products

include mushrooms; ferns; tubers, e.g., ramps; and

the fruits and leaves of more than a dozen species.

The number of forest species harvested to produce

wood-based nontimber products is equal to the

number of species of trees, shrubs, and vines that

grow in the region. Floral products include more

than 50 species of moss and lichen, several species

of berries, ground covers, vines, and twigs and

stems of numerous species.

Overall, research on NTFPs is modest. Beyond

basic taxonomic identification, little information

has become available to aid forest management

decisionmaking. Some of the more popular

products, such as ginseng (Panax quinquefolium

L.), have been the focus of some literature. But

this work has centered mostly on cultivation and

folk history (Davis 1997, Hankins 2000, Hufford

1997). Robbins (1998) provides an overview

of ginseng, but emphasizes markets, trade,

regulations, and the need for conservation. In

reports to the U.S. Fish and Wildlife Service,

Gagnon4 5 examines the sustainability of ginseng

and goldenseal (Hydrastis canadensis L.) and

provides recommendations for monitoring of

wild populations. Other species, such as galax,

bloodroot (Sanguinaria canadensis L.), and pine

straw (Pinus elliottii Englem. and P. palustris

Mill.), all of which are important nontimber

products, have received much less research.

Galax, also known as wandflower and beetleweed, is native to the southeastern portion of the

United States. The single round or heart-shaped

leaves are preferred in floral arrangements as

background foliage (Noland 1997). Most literature

concerning the ecology of galax focuses on its

distribution, range, and habitat (Evans 2000, Fern

1997–2000, Hathaway 2002, Horticopia 2001, Reed

2001). Several studies have examined the genetic

makeup of the plant (Burton and Husband 1999,

Nesom 1983). One of the distinguishing

characteristics of galax is its distinct odor;

yet according to Amoroso (2002), the source

of the odor is still unknown.

Bloodroot, an ephemeral spring-blooming

herbaceous perennial, is found throughout

Southern Appalachian forests. Like the literature

on galax, most of the literature concerning this

important medicinal plant has focused on botanical

aspects. The flowers of bloodroot have 8 to 10

petals, significantly more than those of other

species in the Papaveraceae family (Lehmann

and Sattler 1993). According to Lehmann and

Sattler (1993), these extra petals replace some

of the stamens in a process known as homeosis.

The dispersal of bloodroot seeds is based on

a symbiotic relationship with ants (Marshall

and others 1979) that feed on a lipid-rich

appendage called an elaiosome. After consuming

the elaiosome, ants discard the intact and

viable remaining portion of the seed in their

underground nests, which increases germination

and reproduction of the plant (Beattie and Culver

1982, Handel 1976, Hendershot 2002). Seeds that

are “planted” in the nests are safe from predation,

can avoid competition with parent plants, and have

access to essential nutrients (Czerwinski and

others 1971, Heithaus 1981, Pudlo and others

1980). While the bright red sap exuded from the

roots of bloodroot is the desired product, the

alkaloids found in the sap can be poisonous,

causing nausea, vomiting, and dizziness or fainting

(Russell 1997). Bennett and others (1990) found

that plants located in the Southern Appalachian

forests have higher concentrations of active

ingredients than those found along the West

Virginia-Pennsylvania border.

As is common with most NTFPs, the greatest

amount of literature about bloodroot concerns

its medicinal values (Fern 1997–2000, Haughton

2003, Plyler 2001–2002). Cough lozenges can be

made by mixing root sap and maple syrup (Miller

1988, Sanders 1995). According to Grieve (1931),

Haughton (2003), and Plyler (2001–2002), small

doses have been used to stimulate heart rate and

may help in combating heart disease. A profusion

of clinical studies have debated the effectiveness

of bloodroot products to inhibit plaque and

gingivitis (e.g., Drisko 1998, Hannah and others

1989, Harper and others 1990, Kopczyk and others

1991). In the early 1990s, bloodroot was used as

an active ingredient in a commercial toothpaste

(Damm and others 1999).

4

 Gagnon, D. 1999. An analysis of the sustainability of American

ginseng harvesting from the wild: the problem and possible

solutions. 53 p. Unpublished report. Final report to the Office of

Scientific Authority of the U.S. Fish and Wildlife Service.

Groupe de recherché en écologie forestière. Université du

Québec à Montréal. On file with: Southern Research Station,

1650 Ramble Road, Blacksburg, VA 24060-6349.

5

 Gagnon, D. 1999. A review of the ecology and population

biology of goldenseal, and protocols for monitoring its

population. 27 p. Unpublished report. Final report to the Office

of Scientific Authority of the U.S. Fish and Wildlife Service.

Groupe de recherché en écologie forestière. Université du

Québec à Montréal. On file with: Southern Research Station,

1650 Ramble Road, Blacksburg, VA 24060-6349.
271

Ramps are perhaps the most common spring

edible among NTFPs. Several studies have

examined soil factors, mycorrhizal status, root

anatomy, and the phenology of ramps and related

species (Andersson 1993, Brundrett and Kendrick

1988, DeMars 1996, Whanger and others 2000).

Other research has looked at the chemistry of the

edible portion to identify the active ingredients

(Calvey and others 1997, Carotenuto 1996).

Botanical observations, demographic studies,

and examination of ecological patterns of wild

populations have been undertaken (Hanes 1953,

Hanes and Ownbey 1946, Jones and Shildneck

1980, Nault and Gagnon 1993). Some aspects

of the plant’s pollination ecology and biomass

production have been examined (Nault and

Gagnon 1987, 1988). Rock6 and Nantel and others

(1996) have studied population viability and the

impact of harvesting.

Research on pine straw is better developed

than that on many other nontimber products.

Silvicultural guidelines for pine straw management

in the Southeastern United States are readily

available (Duryea and Edwards 1992, Morris

and others 1992, Woodland Owner Notes 1995).

A significant amount of research has looked

at the impact of pine straw raking on associated

vegetation (Kelly 1996, Litton 1994, Wild 1993,

Wolters 1972). While Litton (1994) and Kelly (1996)

focused their research on the impact of removing

longleaf pine straw on plant populations, Wild

(1993) examined the effects of removal on slash

pine (P. elliottii Englem.) growth and soil

productivity. Wolters (1972) found no significant

effect of pine straw mulch on southern bluestem

(Andropogen spp.) production. Other research

has examined the potential of pine straw in

agroforestry systems (Blanche and Carino 1997,

Blanche and others 1997, Brauer and others 2002).

Collection as a commercial activity has been

studied only lightly and, thus, little exists in the

way of formal estimates of the value of the various

NTFP markets in this region. There are some data

that illustrate the economic importance of these

products. In 1996, collectors of black walnut were

paid more than $2.5 million.7 One company located

in rural southwest Virginia and specializing in pine

roping had sales in excess of $1.5 million in 1997

(Hauslohner 1997). A volunteer fire department in

western North Carolina generates approximately

35 percent of its budget from its annual ramp

festival. Based on 2001 prices, the average

wholesale value of ginseng harvested from the

southern forests exceeds $18.5 million. Certainly,

the aggregate value of NTFPs to the Appalachian

economy far exceeds these examples.

Although ginseng can be found growing

naturally from north Georgia to Southern Canada,

this popular medicinal plant is collected primarily

from the Appalachian region. Based on data

from the U.S. Fish and Wildlife Service, wild

ginseng harvested in seven States accounted

for approximately 82 percent of the harvest

from 1978 through 1998. Of those States, West

Virginia, Kentucky, Tennessee, and North Carolina

account for approximately 47 percent of all forestharvested ginseng. The others, i.e., Indiana,

Ohio, and Virginia, account for approximately

35 percent.

These States also have higher than average

unemployment rates and proportions of people

below the poverty level. For example, the

proportion of people in Kentucky below the

poverty level exceeds the national average by

3 percentage points (U.S. Census Bureau 2002).

The unemployment rate in that State is almost

three times the average for the entire country.

In North Carolina, Kentucky, Tennessee, and

Virginia, the average unemployment rate is more

than 3 percentage points above the national

average. Clearly with such high unemployment,

the possibility of supplementing family income

by collecting and selling NTFPs must be attractive

to local inhabitants.

Research regarding forest management for

NTFPs is in its infancy. Chamberlain (2000) and

Chamberlain and others (2002) have examined

management of national forests in the Eastern

United States for these products. The goal of this

research was to broaden understanding of issues

affecting management. Only 7 of 32 forest

management plans for eastern national forests

addressed NTFPs. Of the eastern national forests

with management plans for NTFPs, only the

National Forests in Florida are located in the

South. The management plan for Florida’s national

forests acknowledged the need for research to

develop a system to deal with the increasing

demand for gathering products .8

6

 Rock, J. 1996. The impact of harvesting ramps (Allium

tricoccum Ait.) in Great Smoky Mountains National Park.

[Not paged]. Unpublished manuscript. On file with: Great

Smoky Mountains National Park, 107 Park Headquarters

Rd., Gatlinburg, TN 37738.

7

 Personal communication. 1998. J. Jones, Manager, Hammons

Products Company, 105 Hammons Drive, Stockton, MO 65785.

8

 U.S. Department of Agriculture. 1985. Land and resource

management plan. [Not paged]. On file with: National Forests

in Florida, 325 John Knox Road, Suite F-100, Tallahassee, FL

32303.

Chapter 23.

 Recreation
Southern Forest Science:

Past, Present, and Future

Socioeconomic

272

Chamberlain and others (2002) also examined

the attitudes and perspectives of forest managers

at several administrative levels to estimate the

constraints on improving management of these

forest products. Fundamentally, four critical

problems impede efforts to improve management.

These are (1) lack of knowledge about the biology

and ecology of the flora from which these products

originate, (2) the diverse nature of the products

and their collectors, (3) a severe lack of market

knowledge, and (4) insufficient personnel and fiscal

resources to assign to management. Until these

obstacles are overcome, NTFPs management

will remain ad hoc, at best.

Although Chamberlain found a lack of

management effort toward NTFPs, there are

initiatives underway to better understand these

products. Federal Agencies that manage forest

lands in North Carolina have initiated projects to

examine harvesting impact on galax populations.

The office of the National Forests in North

Carolina has proposed a study to determine

growth and yield of several NTFPs, including

galax (Kauffman and others 2001). At this time,

no results are available, but informal monitoring

has been undertaken. The foundation for the study

is recognition that there had been a major increase

in the issuance of galax permits over the last 5

years. Because of this, there are concerns that

patches of galax are being stripped of large leaves

faster than the rate of regeneration. Kauffman

and Danley9 argue that the restricted harvesting

season should decrease the trampling of young

leaves and provide time for larger leaves to harden

off. They recommend annual checks be made

in the spring to determine if the season needs

to be modified.

The National Park Service has the only study

actually underway to examine the impact of

harvesting galax leaves. Ulrey10 established

permanent sample plots along the Blue Ridge

Parkway. In all, thirty-two 1-m square plots were

established in 2001. Locations for these plots were

selected based on three criteria: (1) no evidence

of collection, (2) some evidence of collection, and

(3) well-developed patch. Treatments included

removing as many large leaves (> 3 inches)

as possible. Harvested leaves were weighed

and counted, and remaining leaves were counted.

Removal rates were calculated by comparing

harvested leaves to the number of leaves retained

in each plot. Although insufficient time has passed

to provide definitive results, discussions with

the principal investigator of this project indicate

that the impact of harvesting on populations

is insignificant.

PARTING OBSERVATIONS AND POINTS

TO PONDER

Recreation Research

R

ecreation research done in the South by

scientists employed in the South has been

highly productive. Since 1960 and inspired in

part by the ORRRC of that time, a number of

highly important and intriguing areas of inquiry

have been undertaken. In the beginning, problems

of economic development in impoverished areas,

use impacts on forest recreation sites, and

estimating recreation use were focal areas. Indeed

over the years since 1960, research and application

have shown that for all three of these problem

areas, we pretty much understand the problems

and have research-provided tools or knowledge to

address them. Forest-based outdoor recreation as

an economic development tool to address poverty

is not very effective—too seasonal and too leaky

for most rural economies. Managing use impacts

in forest recreation sites requires site hardening

and visitor flow management because planting

grasses, shrubs, and other vegetation does not

hold up. And, we have tools for estimating

recreation use at developed and dispersed areas,

if only we had the will and dollars to implement

those tools more broadly.

Research has provided a pretty clear picture

of who forest recreation visitors are, what they

want to have and see, and how satisfied they are

under different circumstances. We understand

their opinions about fees and how they might

react to a variety of use-regulatory measures

and information systems. We did enough studies

of crowded or environmentally sensitive sites

to develop reasonably good principles to guide

management within social, physical, and ecological

capacities. Indeed, research applied across a

broad spectrum of use and activity situations has

provided good understanding of the phenomenon

of crowding and acceptable or unacceptable

encounters with other users.

9

 Kauffman, G.; Danley, D. 2001. Restriction on galax gathering

season. [Not paged]. Unpublished internal report. On file with:

National Forests in North Carolina, P.O. Box 2750, Asheville,

NC 28802.

10 Ulrey, C. 2001. Summary of first year (2001) results from

galax removal study. 4 p. Unpublished report. On file with:

Southern Research Station, 1650 Ramble Road, Blacksburg,

VA 24060–6349.
273

To assist planners, policy analysts, policy

setters, and legislators at all levels, including

private investors and business managers, research

has provided a succession of broad-scale recreation

demand and supply and social assessments to help

make visible recent and likely future trends. Tools,

data, and findings measuring the effectiveness of

the spatial distribution of supply, forecasting likely

future demand, and examining the social equity

aspects of different potential management

scenarios have been provided. Long- and shortterm trends have been described in laborious

detail, as have participation patterns across

different parts of the region, and different regions

of the country. Access to private lands, as well as

to public lands, has been examined and described,

as have trends in access.

Methods for and studies estimating the

value of sites and site attributes contributing

to outdoor recreation also are among the benefits

of recreation research in the South. Tradeoff

analysis and cost-benefit analysis are the

processes in which these values estimates are

most appropriately applied. A spinoff benefit of

valuation research is the ability to predict effects

on visitation of different pricing policies (a hot

topic now) and predict who might be impacted

most or least by pricing. Another spinoff benefit is

being able to predict revenue likely to occur with

different pricing policies. Underlying all the above

research, which is worthy of far more description

and praise than is offered here, is a continuous

flow of new and improved methods for doing

research. Better and more realistic assumptions,

better measurement scales, more sensitive

input-output models, and a plethora of other

advancements have made recreation research

more effective and more credible. But what of the

future? Where does recreation research need to go

from here? The following are points to ponder as

we set sail into the 21st century.

There is a wealth of research-based knowledge

on hand concerning a variety of forest recreation

topics and problem areas. Not everything that is

needed and certainly not all that will be needed to

fully address the mass of emerging new problems

and complexities will be found in the literature of

the past. But, contained between the title on page

1 and the last publication listed in the literature

cited section on the last page of a large and rich

volume of literature, estimated at roughly 6 to 8

times the number of recreation publications cited

in this chapter; i.e., 1,200 to 1,500 journal articles,

proceedings articles, book chapters, books, etc., is

a huge amount of knowledge. Have we adequately

applied this knowledge? Likely, the answer is

no. At least we feel we have not. There is a crying

need to synthesize, interpret, and make more

accessible our research findings. It is a fact that

managers, planners, business managers, and

others in provider roles will not conduct literature

reviews, nor are they likely to read research

papers. Let us not kid ourselves. The most likely

scenario with most research publications is that

three peers read it in the beginning, and since

then six graduate students read them for use in

dissertations. Overall, maybe a total of 10 ever

read the typical research article, including the

one that the author sent to mom. A priority for

the near future in recreation research, then, is

to assemble, organize, study, interpret, and design

a delivery system to put our research to work.

Dr. Michael Rauscher has developed and is

implementing the idea of a research encyclopedia.

Look up a concept, such as fees, and via

hyperlinks, access relevant research written

at a level applicable broadly. As well, research

literature should be interpreted collectively

to ascertain broadly applicable principles

and guidelines.

The existing body of research literature, then,

is highly valuable and contemporarily applicable.

But forest recreation is not static. New problems

arise, the face of the user changes, and the social

and economic environment within which

everything operates evolves. We see a number

of research problem areas needing attention

(and funding). These are:

• Democracy and a free country is better

than any of the alternatives. However, with

this freedom and with free enterprise and

resulting differentials of wealth and income

can develop inequities in access to forest

recreation opportunities, public and private.

Associated with access are any number of

cultural, legal, or physical barriers that differ

in type and degree across southern society.

Some of these barriers involve fear, such as

women may feel in solo recreation.

• New forms of recreation participation and

burgeoning development of new equipment for

forest recreation participation feeds conflicts

already extant between uses and users. A vivid

example is motorized uses of forest roads and

trails. Walking, biking, and horseback riding

users are not compatible and cannot compete

with motorized users. Walkers cannot compete

with bikers. Bikers cannot compete with

horseback riders. And so on. More use, more

Chapter 23.

 Recreation
Southern Forest Science:

Past, Present, and Future

Socioeconomic

274

varied forms of use, and greater diversity of

users will ensure that this problem of conflict

will only heighten in the future.

• Growing use, use in areas where it never

used to occur, concentrated use in certain

areas, and shrinking places to recreate are

among the factors that will contribute to

increasing impacts on forest recreation sites.

Especially sensitive are wildlife populations

at certain times of the year, riparian areas,

habitats for threatened and endangered plant

and animal species, and fragile or pristine

features, such as rock cliffs. Managing use

and understanding capacities will continue

as a problem begging for research attention.

• A virtual explosion of new outdoor clothing,

sports equipment, transport and sport

vehicles, means of traversing the landscape,

and other technological developments has

been occurring in this region and in the

Nation. Site designs, management guidelines,

information flows, and accommodations

often are not well matched to modern needs

and expectations.

• One of the needs most often mentioned by

recreation users is that of access to better

information. Information on hazards, locations

of places of interest, interpretation of natural

and historical aspects of forest sites, and any

number of other aspects of forest areas is high

in demand by the recreating public. Especially

growing in priority is providing conservation

education opportunities offsite, onsite, and in

association with recreation visits. Information

programs, interpretation, and conservation

education need to be integrated, and research

is needed to guide that integration.

The population of the South is changing

with the times and changing as a result of a tide

of immigrants from other cultures. Research

regarding public attitudes and values associated

with forests, forest management, and forest

recreation has not kept pace with these changes.

Often managers are left to guess what the public

voice would say if it were invited to sit at the

management decision table this year, next year,

or 10 years down the road.

Recreation seekers come to forested areas and

rural places in part, maybe in very large part, to

see and experience rural and natural landscapes.

Ceaseless development and sometimes insensitive

management choices affect the character,

sometimes the ecosystem functioning, and

sometimes, in the eye of the visitor, the quality

of these landscapes. Research can shed light on

these impacts and perceptions of them.

The processes of forest recreation planning

and decisionmaking can be laborious and highly

challenging. This is especially so when it is

necessary to step back to conduct comprehensive

planning across a broad spectrum of management

and policy options. Simplified frameworks and

procedures for planning, including accessing

and using large demand and supply databases,

are needed. A critical aspect of such planning

is assurance that the public is heard from

and understood at local, subregional, and

regional levels.

Exposure to media, entertainment fantasies,

international travel, different cultures, and a host

of other personality shaping factors ensure that

there is an ongoing evolution in the makeup and

priorities of forest visitors. Understanding trends

in motivations and expectations and linking

recreation to improving other aspects of life, e.g.,

fitness and health, are increasingly important.

As society changes and our knowledge of

and association with the land seem to diminish,

there are increasing questions about the place

of a NWPS for this region, and Nation. Wilderness

is much more than a recreation resource. It

represents much more than an ecosystem as

in the eyes of an ecologist. Needed is better

understanding of the value and the social,

economic, and welfare aspects of wilderness

and trends in these aspects.

In forest recreation, science-based planning

and management is much needed—in our view,

needed much more than at any previous time.

Many charged with recreation planning do not

have the background, resources, data, and

information to come anywhere near fully

accomplishing their charge. Highly focused

research with minimal duplication and maximum

partnering is needed. And, more and more this

research needs to provide turn-key data and

information systems for direct application in

management, investment, and planning.

NTFPs Research

Research for NTFPs is needed in three main

areas. The first relates to the sustainability of

forest resources and the communities that depend

on those resources. Sustainability cannot be

achieved without a concerted effort to improve our

scientific knowledge of the ecological dynamics

of the plant species being harvested. Second, the
275

long-term maintenance of household and local

economies that depend on nontimber products will

be in jeopardy unless the true value and impact

of harvesting is understood. Third, the social and

cultural threads of community fabric that have

evolved through generations will be lost if research

is not undertaken to find ways to sustain this way

of life while improving forest management.

Ecological issues, if not addressed, could result

in long-term or permanent decline in biological

diversity. The science-based knowledge does not

exist to ensure that current harvest levels are

ecologically sustainable. Research is needed to

examine and determine the effects of harvesting

on local plant populations, as well as the impact

on associated forest ecosystems. Basic knowledge

of the population dynamics of most NTFPs is

required. Further, baseline inventory data and

regular monitoring of populations are essential

in developing sustainable forest management

strategies. Standardized protocols for inventory

and monitoring for nontimber products is severely

lacking. Current supplies, as well as regeneration

rates, are key elements in determining sustainable

harvest levels, and yet remain unknown.

Management decisions will continue to be based

on incomplete and perhaps inaccurate information

until the science has been done to answer some

very fundamental questions.

In general, NTFP economies remain a mystery.

Unlike timber, the economic value of NTFPs is

not defined nor fully understood. The volumes and

values of NTFPs are not reported, documented,

or monitored, although the overall value of some

sectors, e.g., herbal medicines, is partially

documented. Economic and market data are

essential for setting fair and equitable rates for

collection permits. Knowledge of the value to rural

communities and households also is lacking, and

yet this information is needed to influence policies

for sustainable forest management. Policymakers

and decisionmakers need to be knowledgeable

about the economic importance of NTFPs to rural

communities. Accurate and reliable data on the

supply and demand for NTFPs is essential to

determine sustainable economic harvest levels.

Traditional ecological knowledge is critical

in understanding the fundamentals of NTFP

management. Many collectors have a long

history and strong cultural ties to these products.

Research is needed to document collection

methods, techniques, local knowledge on resource

accessibility, and other knowledge that could

be used to develop socially and ecologically

acceptable management approaches.

To improve the science-based knowledge

concerning NTFPs to a level where sufficiently

reliable information is available to forest managers

will require a shift in institutional commitments.

This institutional transformation will involve

nurturing collaboration between varied disciplines,

such as getting botanists, ecologists, foresters, and

forest products marketing professionals to work

together to determine standardized protocols and

management approaches. To ensure that research

is grounded in the social fabric and that

subsequent protocols and policies are socially

acceptable, sound social science and improved

institutional arrangements also are needed.

LITERATURE CITED

T

he recreation and wilderness research

literature cited in this paper is listed.

Following separately later is the nontimber

products literature.

Forest Recreation Research Literature

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Chapter 23.

 Recreation

289

Chapter 24.

Timber Market Research,

Private Forests, and Policy Rhetoric

David N. Wear and

Jeffrey P. Prestemon1

Abstract—The development of the profession

and practice of forestry in the United States can

be linked to urgent concerns regarding timber

shortages in the late 19th century (Williams 1989).

These were based largely on perceived failures of

forest landowners to protect or invest enough in

the productive capacity of their forests (Manthy

1977). The South, as the only major timberproducing region of the United States in which

private interests have almost exclusively controlled

forests and where unfettered interaction between

private buyers and sellers has determined timber

prices and harvests, provides the clearest example

of the way the private sector manages forests. It

provides a setting for evaluating core assumptions

regarding markets, market failure, and conservation

rhetoric, and for examining the potential role

of various policy approaches for attaining

conservation goals. We examine the history of

research into private timber management and the

function of private timber markets in the South.

In particular, we examine research that provides

insights into the behavior of private forest owners

and the structure of private timber supply. We

also examine how this body of research has been

influenced by and in turn may have influenced

policy perspectives regarding forests in the United

States. Research on the function and structure of

timber markets, especially in the South, has clearly

illustrated that the private sector can generate an

orderly market for a commodity (timber) with

a long production period. Investment responses

to scarcity signals in the South demonstrate that

timber capital is viewed as a reasonably liquid

asset and that market failure with respect to

intertemporal allocation does not hold. In an

interesting reversal of rhetoric, it appears clear

now that timber production from public forests—

more strongly influenced by policy shifts and

administrative process—is much less reliable or

stable than private timber supply. Policy concerns

regarding southern timber markets have evolved

partially in response to an improved understanding

derived from timber market research. Current

concerns focus on the ability of forests to provide

a broad range of resource values, and improved

understanding of how timber markets operate is

required for a full understanding of the ultimate

sustainability of forests, their functions, and their

derivative benefits.

INTRODUCTION

T

he workings or failings of timber markets

are core issues at the foundation of the

conservation movement in the United States.

The rhetoric of timber famine, which dates back at

least to the 1500s in North America (Hyde 1980),

obtained strong public currency in the late 1800s

and eventually led to the establishment of Federal

forestry programs and creation of the national

forests. Regulation of forestry activities by some

States also resulted. The profession and practice

of forestry in the United States likewise can be

linked to these urgent concerns regarding timber

shortages in the late 19th century (Williams 1989).

Timber shortages can be viewed as resulting

from market failures with several potential causes.

Overharvesting—that is, harvesting without

adequate provision for future needs—implies

either (1) an insecure timber resource or

(2) a lack of information regarding overall timber

inventories. Without secure property rights,

timber owners cannot be certain about future

access to their timber, and have a strong incentive

to harvest soon. The same outcome would result

from timber being harvested from a common

property resource. Without information on overall

inventories, timber owners cannot anticipate

oncoming shortages, and so fail to recognize the

potential for additional returns from delaying their

harvests. Both cases would lead to departures

from the economically optimal allocation of

harvesting over time, pushing harvest rates

beyond socially optimal levels.

1

 Research Forester and Project Leader, and Research

Forester, U.S. Department of Agriculture Forest Service,

Southern Research Station, Research Triangle Park, NC

27709, respectively.
Southern Forest Science:

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290

Another related concern regarding timber

markets has been a perceived failure of forest

landowners to protect or invest enough in the

productive capacity of their forests (Manthy

1977). Investment below socially optimal levels

could result from several potential causes. One

is simply that returns from forest investments

are not competitive with those from alternative

investments; that is, expected returns from

timber fail to justify the investment on financial

grounds. In cases where investment is competitive

but is not undertaken, the reasons could be

(1) a lack of access to investment capital,

(2) a lack of information regarding production

potential, (3) a lack of market information

regarding current or anticipated future prices,

(4) a long production period that effectively locks

up capital for unreasonable periods of time—

sometimes called capital illiquidity, or (5) excessive

investment risk. All five of these concerns have

been raised as explanations for a perceived

underinvestment in forests.

The South is the only major timber-producing

region of the United States in which private

interests have almost exclusively controlled

forests and where unfettered interaction between

private buyers and sellers has determined timber

prices and harvests throughout the 20th century.

Private landowners currently control 89 percent

of timberland (productive or potentially productive

forest land) in the region (Conner and Hartsell

2002). Twenty percent is held by the forest

industry. The South provides the clearest

example of the way the private sector manages

forests. It provides a setting for evaluating core

assumptions regarding markets, market failure,

and conservation rhetoric, and for examining the

potential role of various policy approaches for

attaining conservation goals. In this chapter,

we examine the history of research into private

timber management and the function of private

timber markets in the South. In particular, we

examine research that provides insights into

the behavior of private forest owners and the

structure of private timber supply. We also

examine how this body of research has been

influenced by and in turn may have influenced

policy perspectives regarding forests in the

United States.

HISTORICAL PERSPECTIVES ON

PRIVATE FORESTS

P

atterns of resource utilization across time

and space are defined by the intersection

of social organization with initial resource

reserves, underlying biological productivity, and

technological change and adoption. The history

of forest use in the United States is an outcome

of, among other factors, divestiture of a public

domain, establishment of forest reserves, longsustained economic expansion, and the structure

of private property rights. The role of private

enterprise, both in supplying and consuming

timber, has long been contentious and is often

seen as the root of natural resource problems

in the United States.

At the turn of the century, perceived abuse

and waste of private forests was the primary

motivation for the American Conservation

Movement in the United States.2 The rhetoric

of timber famine then, and for many decades

to follow, was strongly rooted in the belief that

private timber owners would fail to sustain the

productivity of their forests. The national illusion

of timber inexhaustibility began to wane by the

late 1800s, and the resulting conservation and

wilderness movements of the late 19th and early

20th centuries were based almost exclusively on

the argument that private-sector management of

forests would lead to destruction of forest lands

and emergence of a “timber famine” in the young

United States (Pinchot 1947, Williams 1989).

A treatise on emerging timber scarcity in 1874

(Hough, as cited by Steen 1976) initially formalized

the issue for the Federal Government, attracted

the attention of President Grant, and led in 1876

to the establishment of the Division of Forestry

within the U.S. Department of Agriculture (Steen

1976). Public ownership of forests in the form

of the forest reserves (eventually the national

forests) and the formation of the U.S. Department

of Agriculture Forest Service (Forest Service)

implicitly recognized concerns regarding timber

scarcity and the assumption that private

ownership was the root cause of resource

destruction and eventual shortage.

2

 The related wilderness movement of the day was clearly

motivated by other concerns, but both can be viewed as

motivated by concerns regarding the loss and destruction of

forest lands. Even at this early date, however, the wilderness

movement, led by John Muir, was separate from and often at

odds with the conservation movement led by forestry advocates

(see Nash 1967).
291

Until the 1960s, forest policy in the United

States was driven almost exclusively by this

timber scarcity rhetoric,3 and resulted in efforts

to expand the Federal forest estate and Federal

programs to support State and private forest

management. The latter initiative dates from the

Clarke-McNary Act of 1924, which authorized

funding for, among other things, forest nurseries

and technical advice to woodlot owners to support

reforestation, and extended authority to acquire

private land for national forests for the purpose

of providing timber.

The antipathy toward private ownership

had other results. Into the 1940s and especially

in the 1930s, conservation leaders, including

some Chiefs of the Forest Service, argued for

national regulation of timber harvesting and

management on private lands (e.g., U.S.

Department of Agriculture Forest Service 1941).

National private harvest regulation was never

approved—the responsibility for forest regulations

remaining with the States—and disappeared

from the Agency’s rhetoric by the late 1940s. Still,

private land continued to be viewed as a primary

source of resource problems and increasing

resource scarcity in the United States.

ECONOMIC PERSPECTIVES ON

RESOURCE SCARCITY

T

he belief that private ownership resulted in

timber scarcity was essentially taken as selfevident and remained untested until the 1970s,

when research into the limits of growth began to

focus broadly on material scarcity. Motivated in

large part by concerns regarding oil supplies, a

major thrust of resource economics in the 1970s

and the 1980s was the study of resource scarcity.

This body of work focused especially on how to

measure changes and trends in resource scarcity

in a way that provided information about the

potential for and limits of economic growth.

Economic scarcity is not strictly a physical

quantity concept but is influenced by information,

technology, and quality. To illustrate, consider

that a mineral ore is scarce only if it is needed

(demanded) in some form for the production of

goods and services. It seems logical that as the ore

is extracted and used it would become “more

scarce.” However, the availability of this ore

for human uses is determined not by its total

quantity (which is generally not known), but by

the known quantity (the information part) that

can be extracted by affordable means (the

technology-driven cost part).

The available quantity of this ore can actually

be increased in two ways. One is through

discovery of additional deposits, i.e., by improved

information. The other is through technological

advances that either allow more efficient use of

the ore extracted from existing deposits, i.e.,

through utilization of lower quality grades, or

enable substitution of other materials for the ore

in the production of the relevant goods. With a

renewable resource such as timber, stocks may

also be directly enhanced through investment.

Information and technology, therefore, play

important roles in defining resource scarcity.

Resource economists use trends in resource

prices (rents) or in the marginal costs of extraction

to gauge changes in economic scarcity. With good

market information, producers will internalize

their expectations regarding future returns (based

on inventories and technology) and current and

anticipated demands into decisions regarding what

to produce now vs. what to produce in the future.

Therefore, sustained increases in price provide a

strong signal that the resource is becoming scarcer

as producers withhold material from the market in

anticipation of higher future returns. Conversely,

a sustained decline in prices signals decreasing

scarcity. Erratic price movements or discrete

jumps in price paths might indicate that producers

were surprised by a change in market conditions

impossible to foresee or an information failure.

Analyses of price trends were the first studies

to directly challenge the premises of historical

scarcity rhetoric. Studies by Libecap and Johnson

(1978) and Berck (1979) failed to reject the

hypothesis that wood product prices in the late

19th and early 20th centuries increased at rates

consistent with the prevailing, risk-free interest

rates. This pattern of price growth is predicted

by economic theory for the optimal use of an

exhaustible resource. That is, these findings

offered evidence that refuted the notion that

historical timber harvesting had been completely

indifferent to future implications.

Evaluation of 20th-century price paths also did

not suggest market failure. In the 1960s and 1970s,

researchers beginning with Barnett and Morse

(1963) evaluated trends in resource rents (in situ

prices) for various natural resources to look for

Chapter 24.

 Timber Market Research

3

A clear exception to this claim is concern and debate

regarding the impacts of forest removals on the condition of

navigable streams and on potential for flooding that dominated

the debate regarding the Weeks Act of 1911. As specified by the

Weeks Law and until revised by the Clarke-McNary Act of

1924, property for eastern national forests could only be

acquired to protect navigable streams (Steen 1976).
Southern Forest Science:

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Socioeconomic

292

evidence of increasing scarcity. Contrary to

popular sentiment, evidence suggested no

emerging scarcity for nearly all resources

evaluated, even mineral resources. Technological

changes coupled with new discoveries were

credited with effectively augmenting resource

stocks in the 20th century. Throughout these

studies, however, the major exception to the trend

away from scarcity was timber, which showed

an unambiguous increase in scarcity. Rates of

increase for timber rents (stumpage prices)

were, however, not inconsistent with an optimal

depletion pattern.

These results suggest that there has not

been an information failure in timber markets;

i.e., they do not support the notion that producers

failed to account for the future when making

harvest decisions even as harvesting shifted from

one region of the country to another. However,

they do not completely allay concerns regarding

conservation of forest resources, even from

a strictly timber harvest perspective. Most

important, they suggest that timber was not

managed as a renewable resource through the

early portions of the 20th century. On the contrary,

timber price trends appeared consistent with those

expected for mining of a nonrenewable resource.

One explanation of why a potentially renewable

resource would be utilized as a nonrenewable

resource is that old-growth timber and second

growth or managed timber are two very different

resources. It can be argued that old growth

is essentially nonrenewable, since economic

conditions do not promote the production of oldgrowth timber. Second growth is also expensive

to produce and is not financially attractive as long

as relatively inexpensive old growth is available.

The interactions between old-growth harvesting

and second-growth management have been

explored in a study by Lyon (1981). Using optimal

control theory, he found that an orderly timber

market would start with a mining phase that

would eventually trigger an investment phase

in a transition to a sustained, agricultural style

of timber production. The trigger mechanism

is timber price. Investment in forests commences

when the price is high enough to warrant

competitive rates of return to second-growth

timber production. After transition, landowners

anticipate and adjust timber stocks to ameliorate

resource scarcity. Timber production and forest

management in the United States since the

1970s seem to be consistent with these

general prognoses.

Taken together, these studies might suggest

that concerns regarding timber famine perhaps

were overstated. However, these findings are

viewed through a lens of economic theory and data

analysis that was unavailable during the early 20th

century. In addition, the activities spawned by the

American Conservation Movement in the late 19th

century may have provided information—scarcity

signals—that modified the behavior of timber

producers. That is, the rhetoric of the American

Conservation Movement may have led to change

before policy actions did. Whatever the causal

path, it became clear by the 1980s, at least to

economists, that timber famine was not a relevant

contemporary policy concern. By the 1990s timber

scarcity had disappeared from forest policy

rhetoric completely. Scarcities of contemporary

concern relate to the habitat or ecosystem

conditions provided by forests.

The net effect of this research into resource

scarcity had important influence on the thinking

of resource economists and policy analysts. It (1)

rejected the notion that private timber production

necessarily proceeded without anticipating future

scarcity, (2) left open the question of whether

anticipated shifts to renewable agriculture-style

production would occur, and (3) illustrated that

scarcity can emerge—timber prices can rise—even

where no market failure occurs. Overall, this body

of work clarified a set of hypotheses for studying

the structure and function of timber markets.

SOUTHERN TIMBER MARKET RESEARCH

R

esearch into material scarcity shifted the

foundation of forest economics research.

Until this time, much research was targeted

at understanding the magnitude of assumed

market failures. From the 1980s forward, however,

the focus shifted to understanding how market

behavior could influence forest conditions. For

some research, the focus shifted from addressing

problems with the intertemporal allocation of

timber to understanding how timber management

might shape allocative problems with other

nonpriced benefits from forests. In other cases,

the research focused fully on modeling and

forecasting the future evolution of forest

production, prices, and forest incentives with

increasingly greater precision.

The resource economics research into material

scarcity changed the frame of reference for

forest economics research but provided only an

incomplete understanding of timber markets and

private production. These initial analyses were

based on highly aggregate data for a very
293

heterogeneous resource, and the findings left

several questions regarding market mechanisms

unaddressed. For example, Can local “scarcities”

appear and drive spatial redistribution of demand?

Do prices for some species increase at the risk-free

rate of interest until it becomes profitable to shift

to a substitute species? How are timber markets

related spatially? Why should (or do) timber prices

increase in the long run if the timber resource

is in its “sustained production” phase? If they do

increase over time, is this the result of information

failure or market failure? Forest economics

research in the South and elsewhere applied

multiple approaches to develop a better

understanding of the specific working of timber

markets in the region, but these questions

to some extent remain unanswered.

Economic research generally targets either the

behavior of individual agents, e.g., producers or

consumers, or the operation of highly aggregate

markets, e.g., the interaction between price and

quantity on a large scale. Forest economics

research has focused both on the behavior of

individual forest landowners and on aggregate

timber markets, mainly for softwood products.

Both approaches have been exploited in the South

to develop insights into the ultimate outcomes

of forest management on private lands.

ANALYSIS OF HARVEST CHOICES

T

he central conceptual construct of forest

economics is the optimal harvest model.

The first correct formulation is credited to

Faustmann in 1849 and still serves as a point

of departure for research into landowner behavior

(Faustmann 1849). Indeed, Newman (1988)

identifies more than 85 derivative publications in

the modern literature. Extensions of the optimal

rotation literature address the influence of

nonmarket values (Hartman 1976), spatial

configuration (Swallow and Wear 1993), and price

dynamics (Brazee and Mendelsohn 1988, Clarke

and Reed 1989, Forboseh and others 1996, Gong

1999, Haight and Holmes 1991, Lohmander

1988, Thomson 1992). These studies explore

management choices (mainly harvest) that would

result from a given set of production functions,

objectives, and constraints.

The intertemporal structure of forest

production is what defines forest economics as

a unique endeavor, and the many variants of

optimal harvest models provide the theoretical

foundation for nearly all of the work that is forest

economics, especially work on individual harvest

and management choices. These models have

been used to construct normative, simulation

approaches for investigating individual

behavior and have been the theoretical basis

for constructing models for positive statistical

analysis of harvest choices. We explore these

two approaches in turn below.

NORMATIVE TIMBER MANAGEMENT MODELS

M

uch early research into forest economics

involved comparing actual timber

management with the behavioral norms

defined by optimal rotation models. “Normative”

research approaches prevailed from the 1950s

through the 1970s. In the South, this research

focused on investment behavior across landowner

types to investigate the potential for increasing

timber supply from private land.

Research on individual investment behavior

has directly addressed whether landowners

were pursuing optimal management regimes—

as defined by the economist—within their

forests. Differences between optimal and actual

investment levels were viewed as an untapped

potential to produce timber from private lands.

These foregone investments were labeled timber

investment opportunities (TIO). Suboptimal

management was attributed to various market

failures, including information failures with

respect to technical knowledge of forest

management, but more importantly with respect

to timber prices and timber price trends, and due

to prohibitive upfront costs, failure of markets to

reflect the future value of standing timber, and

limited access to capital (Adams and others 1982).

The results of TIO analysis were used to argue

for various forest policies to address these failures.

In particular, TIO results were central arguments

for programs that subsidize forest planting,

including cost-share programs such as the

Forestry Incentives Program and the Agricultural

Conservation Program. In effect, these programs

were designed to overcome the “front-end loading”

of costs that discourages investment in long-run

timber production. Assessments of timber markets

through the 1980s identified TIOs on private lands

as clear evidence that information and capital

failures impeded timber supply and as a strong

indication that public assistance could leverage

additional timber supply from the private lands.

In addition, the gap between actual investment

and modeled optimal investment was used as an

indication that the lack of a widely available price

reporting system was retarding the efficient

expansion of timber investment in the South—

Chapter 24.

 Timber Market Research
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294

an information failure. The demand for price

information led eventually to the formation of a

price reporting service covering the entire South.

Another element of the nonindustrial private

forest (NIPF) market failure discourse addresses

risk. Some perceive forest management as a risky

investment heavily influenced by physical risk of

catastrophic loss caused by insects, disease, fire,

ice, or wind. It has been argued that risk reduction

through fire prevention and suppression efforts

set the stage for forest investment activities in

the region. Government-sponsored insurance for

timber production was also proposed to address

the TIO untapped potential. Insurance policies

of this sort have not developed, although some

private timber insurance is available today.

Subsequent research suggests that risk levels

are perhaps not as high as once thought and are

effectively mitigated by mixed (geographically

and biologically diversified) holdings of forest

land. Still, for the risk-averse small landholder

with a single holding, the probability of a

catastrophic loss, although small, could strongly

influence his or her decisions.

The premise of much early forest economics

research on individual behavior was that these

market failures did occur; analysis was used

to measure the implications of market failure.

Beginning in the 1970s, however, research began

to challenge these premises. The development

of individual choice econometric models, coupled

with the development of computational speed and

capacity, allowed researchers to compare observed

landowner choices with economically rational

choices. As a result, various hypotheses regarding

choices could be tested directly.

POSITIVE HARVEST CHOICE MODELS

E

conometric models of individual choices

examine the probability of a choice as a

function of relevant explanatory variables.

The selection of variables, as well as the functional

form of the model, can be developed by the theory

of producer behavior, modeling landowners as

producers seeking to maximize the provision of

timber and perhaps other products, or consumer

behavior, modeling landowners as individuals

maximizing the utility that they derive from

forests in the context of a household budget

constraint. In both cases, the model structures are

based on market behavior. Tests of significance of

the relevant variables are construed as tests for

consistency with market behavior.

Harvest choice models provide direct insights

into the responsiveness of timber owners to

signals from timber markets. If landowners

were indifferent to scarcity signals in the form

of timber prices, then the market would fail to

allocate timber efficiently across time. This is one

expression of the timber famine hypothesis. This

hypothesis has been universally rejected by a

collection of harvest choice studies (Binkley 1981,

Dennis 1990). All of these studies find a positive

correlation between timber prices and the

propensity to harvest timber and, therefore, reject

the null hypothesis that harvests are not price

sensitive. However, these studies did not address

the relative efficiency of harvest behavior and,

thus, leave unanswered questions regarding the

optimality of harvest responses to relative prices.

The econometric harvest choice literature also

began to crystallize the idea that rational behavior

need not only embrace the provision of timber

products. A study by Hyberg and Holthausen

(1989) challenged the application of the production

theory model to forest landowners. Newman and

Wear (1993) found management by nonindustrial

private landowners not to be inconsistent with

profit-maximizing behavior but rather to reflect

the relatively high value such landowners place on

holding standing inventory. Also, findings from

harvest choice studies consistently showed that

certain demographic variables, including age,

education, and ownership type, were significant

in explaining harvest choices (Binkley 1981,

Dennis 1990). This implies that harvest

preferences are heterogeneous and may be

linked to nontimber goods and services derived

from forest holdings. In other words, departures

from the expected behavior under a single

ownership objective of timber production may

not be proof of market failure. Instead, such

departures may be the result of rational behavior

in a well-functioning market, if other private

values are also produced from the forest.

ANALYSIS OF TIMBER MARKETS

E

conomists also study the behavior of

production at aggregate levels. In the case of

timber markets, much research has addressed

the structure of timber supply at various levels

of aggregation, but has focused mainly on the

supply response of relatively homogeneous

regions. Aggregate analysis provides a framework

for evaluating the feedbacks between timber

demand and supply in defining the response of

the private sector to scarcity signals. Various

techniques have been applied to this area of
295

investigation. As with harvest choice modeling,

the discussion may be split into two parts dealing

with normative and positive approaches.

NORMATIVE TIMBER SUPPLY MODELS

T

he original applications of normative models

to timber supply were simply aggregations

of normative harvest choice models. They

defined the optimal rotation for each quality class

of forests for a given price and then summed the

average annual harvest implied for each forest

class to define total harvest. By solving the

problem for a large number of prices, the

aggregate supply relationship could be defined.

Such analyses were constructed for the State of

Georgia by Montgomery and others (1975), for

east Texas by Hickman and Jackson (1981), and

for Louisiana by Hotvedt and Thomas (1986). This

approach implicitly models the supply that would

flow when each forest class has achieved a uniform

age distribution between zero and its optimal

harvest age (the forester’s “normal” forest),

an outcome that could result in a long-run static

equilibrium for the given price. Accordingly, this

approach defines only a long-run supply, because

it does not explicitly address the existing age

structure of forests. This approach can provide

insights into the maximum potential timber

output by modeling the output consequences

of strict adherence by landowners to maximum

profit objectives.

Normative models can, however, provide an

extremely rich supply specification and, as shown

by Hyde (1980) and Jackson (1980), can provide

a tractable approach to examining the market

consequences of various forest sector policies;

for example, public land management strategies

and timber taxes. The detailed supply specification

also allows for analysis of market effects of

technological or environmental changes.

Normative models can also be implemented to

address conversion of land from forest use to

nonforest uses and vice versa. These strengths

derive from the explicit linkage between individual

behavior and aggregate outcomes, which

can account for heterogeneous forests and

forest owners.

Normative supply models provided an

important and explicit bridge from stand-level

analysis to market-level assessment. They

provided the first economically grounded

estimates of timber supply and credible measures

of maximum supply potential for a region; Vaux

(1954) is credited with the first application. In

spite of the limitations implicit in any attempt to

fully simulate market interactions and short-run

behavior, they provided an early mechanism for

exploration of the potential welfare implications of

various management and policy strategies. These

studies, therefore, framed a set of questions that

would eventually be addressed by the use of

increasingly sophisticated analysis.

Extensions of this mechanistic or engineering

approach, especially using linear programming,

expanded their usefulness. Dynamic adjustment

processes can be modeled to address short-run

responses. Quadratic programming can be used

to simulate the interaction of supply and demand

(Greber and Wisdom 1985, Samuelson 1952).

Entropy constraints can be used to simulate the

variability of observed market responses (Sallnas

and Eriksson 1989). The strength of this modeling

approach is its rich supply specification, which

allows for analysis of the economic and welfare

implications of new technologies and new or

hypothetical policy instruments (Wear 2003).

POSITIVE TIMBER MARKET ANALYSIS

P

ositive analysis of timber markets departs

from normative models’ focus on supply

potential to address expected supply

responses. Positive models of timber supply

implicitly link the biological model of timber

production to a behavioral model of harvest choice

and are developed by applying statistical methods

to observed behavior. Their strength is the

calibration to observed behavior, while the

challenges of this modeling approach have been

statistical methodologies and access to adequate

data. Methodological concerns have largely been

resolved; i.e., through the development of

simultaneous equation and other estimation

techniques and improvements in computational

power that allows their application. Data

availability and quality can still stand between

theoretical development and application.

There are two core motivations for estimating

positive timber market models. One is to test

hypotheses regarding the structure and function

of timber markets and the effects of forest policies.

For example, such models provided the first

empirical tests for simple price responsiveness of

timber supply, i.e., that forest owners harvest

more timber when prices rise. More sophisticated

approaches have permitted more refined testing

which addresses increasingly refined hypotheses

regarding investment response, policy effects,

market structure, and market extent.

Chapter 24.

 Timber Market Research
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296

The second, and perhaps the more compelling,

motivation for this area of research has been to

develop forecasts of market activity. Public and

private planners need forecasts of both harvest

quantities and timber prices. Initial developments

of positive market models in the 1970s took place

at a time when there was much concern about

underinvestment by NIPF landowners, especially

in the South. Price information, including forecasts

of future prices, was seen as a necessary condition

for the encouragement of optimal investment in

forest management. In addition, national forest

planning regulations developed in the late 1970s

required timber price forecasts, and the Forest

and Rangeland Renewable Resources Planning

Act (RPA) of 1974 explicitly required the

Forest Service to assess future timber supply

and demand.

Several studies focused on southern timber

markets or contained a southern market

component. McKillop (1967) provided the initial

positive analysis of aggregate timber markets.

Robinson (1974) examined regional stumpage

and lumber markets for the South and the Pacific

Northwest for the period 1947 to 1967. His study

raised a set of questions regarding the magnitude

of the supply response (quantified by the price

elasticity of timber supply) that were addressed

by subsequent research. As part of their national

timber market analysis for RPA, Adams and

Haynes (1980) specified southern sawtimber

supply functions for two subregions of the South.

Daniels and Hyde (1986) applied a regional supply

and demand model to the total (hardwood and

softwood) wood products sector in North Carolina.

Newman (1987) was the first to model markets

for different products in the South concurrently.

He used a profit-maximization approach to derive

timber demand and supply equations to model

the southern pulpwood and solid wood markets

in the South. This allowed for the delineation of

substitution possibilities by stumpage producers

in the region. Newman found solid wood timber

to be a weak complement to pulpwood supply

as owners jointly produce both goods and, more

significantly, this study clarified the important

part that the joint production of different timber

products may play in determining the structure of

timber supply. Prestemon and Wear (2000) further

characterized the implications of joint production

on timber supply.

These positive timber market models provide

the central behavioral construct for developing

timber market forecasting models. Timber

forecasting models are generally hybrids of both

empirical and simulation approaches, constructed

by linking empirical estimates of supply response

and timber demand to mechanistic models of

timber growth, as well as models of land use

change and timber investment behavior.

Timber market forecasting models have played

critical roles in anticipating change and discussing

policy approaches to or implications of forest

production. The model developed by Adams and

Haynes (1980) is still the centerpiece of national

timber market assessments conducted for the

RPA (e.g., Adams and Haynes 1996) and has

been used to simulate the impacts of various

forest sector policies including cost-share

programs and international trade scenarios.

Regional analysis, which demands a higher degree

of spatial specificity than is generally provided

by international or national models, is likewise

anchored by timber market forecasts. In the

South, models developed by Abt and others (2000)

have been used for this work (e.g., Prestemon

and Abt 2002).

An important area of research that developed

through the 1990s involved testing the extent

of markets and the linkages between spatially

separated markets; in effect, this tests the law

of one price. Understanding how shocks and the

effects of policies are transmitted across space is

essential for characterizing how timber markets

respond at the relatively fine spatial scales of

regional models. Research on spatial price

linkages can also be used to evaluate market

efficiency. For example, efficient price

transmission between markets allows production

in one region to respond immediately to shocks in

another region, implying that the effects of policies

and market shocks, e.g., hurricane damage, large

mill closures, etc., are rapidly shared across

regions. Incomplete price transmission, on the

other hand, would imply that the consequences

of local policy shifts and shocks would be borne

locally. Tests of “market integration” have been

conducted for various levels of production and

at various spatial grains. Analysis of markets

for materials at higher stages of production (e.g.,

finished materials such as lumber) generally

supports market integration, even between broad

regions (Jung and Doroodian 1994, Murray

and Wear 1998, Uri and Boyd 1990). Studies of

stumpage markets have not generally supported

market integration hypotheses (Bingham and

others 2003, Nagubadi and others 2001, Prestemon

and Holmes 2000) defining a set of questions
297

regarding not only the structure of stumpage

markets, but also the linkages between markets

at various stages in the production chain.

ONGOING INITIATIVES

T

imber market research continues to address

questions regarding the current and future

use and conditions of southern forests.

However, these questions have shifted away from

core behavioral questions and aggregate outcomes

and toward understanding the spatial structure

and ecological implications of timber market

activities. The integration and cointegration

line of research continues to investigate the

communication of prices between subregions of

the South, exploring the spatial extent of markets

for various products. In addition, research is

beginning to model the supply response of

private landowners in spatially explicit fashion.

Increased spatial definition is required to

address questions regarding the effects of forest

uses on ecological and environmental conditions.

Increasingly, concerns are being raised regarding

the effects of timber market activity on the

structure of forested ecosystems and on the ability

of these systems to sustain ecological integrity and

a variety of benefits beyond timber products (Wear

and Greis 2002). A key concern with respect to

the ecological structure of southern forests is the

extent, location, and management intensity of pine

plantations. These are determined as the outcomes

of investment decisions by private landowners.

Clearly, the answers to these types of questions

require insights into where, within the South,

production and investment will respond to

expanding demands for southern timber.

Spatially refined forecasting requires aggregate

models with the spatial and production detail

used to construct normative supply models and

individual choice models in the past. Research

into supply responses at finer scales has begun

to explicitly bridge from the findings of individual

choice models to the implications at regional

levels. The key to this research is linking harvest

behavior to supply responses through a forest

inventory. Prestemon and Wear (2000) accomplish

this by modeling harvest choices for individual

inventory plots, based on a general optimal

harvest choice framework, and then estimating

supply impacts by applying a harvest probability

to the area expansion factor of each plot; this link

between a behavioral model and the area frame

structure of an inventory was first developed by

Hardie and Parks (1991). Pattanayak and others

(2002) also use the forest inventory and analysis

inventory to model supply responses from

partitions of the inventory defined by ownership,

location, and quality. Both approaches provide

promise for building spatial, ownership, and

productivity detail into market forecasting models.

Another aspect of understanding the

spatial structure of timber markets is a more

comprehensive understanding of individual choices

regarding uses of forest land. This requires

addressing the linkages among all interrelated

decisions regarding land and resources, including

land use, investment, and harvest choices. A

better understanding of the influence of landowner

characteristics on management choices is also

needed. This would be required, for example,

to forecast how changing demographics could

influence the area of forest as well as the supply

of timber from forests. For example, the Southern

Forest Resource Assessment describes a future

in which the area of pine plantations will rapidly

expand southwide (Prestemon and Abt 2002).

But as the South becomes more populated, the socalled accessibility question regarding timber

inventories, i.e., defining how much inventory

would be accessible to timber harvesting in

the future, becomes more important. Newman

and Wear (1993) modeled timber supply and

investment in a common analytical framework.

However, while several investigators have studied

land use, investment, and harvesting separately,

none have yet linked all three into a common

analysis to address the accessibility question.

CONCLUSIONS

F

orest economics research often addresses

issues at the core of forest policy debates,

and it has had a strong influence on policy

rhetoric, perspectives, and, at least indirectly,

policy outcomes. Research on the function and

structure of timber markets, especially in the

South, has clearly illustrated that the private

sector can generate an orderly market for a

commodity (timber) with a long production period.

Investment responses to scarcity signals in the

South demonstrate that timber capital is viewed

as a reasonably liquid asset and that market

failure with respect to intertemporal allocation

does not hold. In an interesting reversal of

rhetoric, it appears clear now that timber

production from public forests—more strongly

influenced by policy shifts and administrative

process—is much less reliable or stable than

private timber supply.

Chapter 24.

 Timber Market Research
Southern Forest Science:

Past, Present, and Future

Socioeconomic

298

The public and policy concerns regarding

whether or not private timber markets will work

to provide a sustainable level of timber harvests

have been answered. The emphasis has now

shifted to understanding how these markets work

in attempts to predict how market activity will

reshape the extent and structure of forests within

the South. This is the crux of understanding how

human occupation and utilization of land and

resources will influence ecosystem structure and

function in the future. Understanding how the

private sector will organize timber production is

one of the keys to understanding overall forest

sustainability that addresses the provision of all

desired goods and services derived from forests.

Researchers should not, however, mistake the

presence of an orderly private timber market as

an indication of a fully efficient market. Indeed,

research into industrial organization shows that

markets that are not completely competitive can

exhibit aggregate behavior that is qualitatively

similar to the perfectly competitive case.

However, inefficiencies can impose substantive

welfare costs on consumers. In the case of timber

markets, findings of inefficiency derived from

integration studies raise some concerns in this

regard. Research into individual landowner

choices has not yet fully addressed whether

observed investment is suboptimal due to capital

constraints, tax structure, risk perspectives, or

combinations of these factors. Research into the

presence and effects of market power is generally

underdeveloped—Murray’s (1995) analysis of

southern timber market structure is an exception.

Policy concerns regarding southern timber

markets have evolved partially in response

to an improved understanding derived from

timber market research. Current concerns are

urgent, and improved understanding of how

timber markets operate is required for a full

understanding of the ultimate sustainability

of forests, their functions, and their derivative

benefits in the future.

ACKNOWLEDGMENTS

Wear’s approach to the topic of this chapter

reflects explorations of similar topics with

David Newman (Newman and Wear 1990)

and with Peter Parks (Wear and Parks 1994).

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Biodiversity
Southern Forest Science:

Past, Present, and Future

Biodiversity

302

Chapter 25.

Biodiversity and Southern Forests. ........................................ 303

Chapter 26.

Population Viability

as a Measure of Forest Sustainability. ........................................... 307

Chapter 27. Responses of Southeastern

Amphibians and Reptiles

to Forest Management: A Review.................................................. 319

Chapter 28.

Monitoring Tree Species Diversity

over Large Spatial and Temporal Scales....................................... 335

Chapter 29.

Population Growth and the Decline of

Natural Southern Yellow Pine Forests. .............. 347
303

Chapter 25.

Biodiversity

and Southern Forests

B

iological diversity encompasses all levels

of natural variation and includes molecular,

genetic, and species levels. All of these

factors contribute to diversity accumulated at

the landscape scale. However, biodiversity is not

equally dispersed across the landscape, but rather

clustered in pockets. The Southeastern United

States supports several biodiversity hotspots

including the Southern Appalachians, the

Panhandle of Florida and Alabama, and the

Everglades. As landscapes continue to be modified

by habitat fragmentation, loss, degradation, and

conversion, many species cannot adapt and will

eventually be extirpated. While the Southeast

remains relatively forested, much of the region’s

current forest exists as tree plantations. Some

plantations have replaced agricultural land and

constitute additional habitat for many forest

species. Other plantations have been created

from natural forested systems, and this kind

of conversion has likely resulted in a less

diverse and structurally simplified landscape—

one that is less beneficial to most native species.

Additionally, changes in the frequency and

source of disturbance have severe implications

for many southeastern ecosystems. For example,

pine forests, pine savannas, and prairies all

depend on fire for their persistence, albeit at

varying frequencies.

South and Buckner (2004) argue that most

of the major landscape changes were a direct

result of human population growth over the past

200 years. During that period, the population

of the area that is now the United States grew

from 6 million to the present estimate of 275

million. Fire and field abandonment have helped

maintain stands of yellow pine. However, current

silvicultural practices and social attitudes toward

fire have resulted in a 65-percent reduction in

natural yellow pine stands in the Southeast.

Unfortunately, present trends suggest that

conservation of such stands, and species associated with them, will be difficult if silvicultural

practices and public attitudes do not change.

Gordon (2001) provides an excellent

overview of some of the key issues related

to forest management and its effects on

biodiversity. Gordon highlights four important

issues: (1) some details about species dependency

in relation to southern forests, (2) the history

of forestry in the South and its implications for

diversity, (3) what changes have recently occurred

in forestry, and (4) what lies ahead in the next

century. Furthermore, scientists continue to

discuss the relative merits of an intensive

production-based or conservation-based approach

for future forestry. Agricultural forestry seeks

to simplify the landscape in terms of structure,

pattern, and product. The benefit of this approach

is the intense use of smaller plots of land. The

drawback is the reduction of biodiversity in and

around those managed stands. Contrast this with

the conservation-based approach, which focuses

on maintaining a complex landscape and supports

a greater diversity of species. Gordon provides

examples of each approach and concludes that we

need to utilize both approaches in the next century

while further investigating how to balance them.

Rather than focus on current research issues,

Wigley and others (2001) provide a historical

perspective on how research on biodiversity, and

particularly wildlife diversity, has evolved in the

Southeast. Early research focused on game

species, but currently includes threatened and

endangered species, nongame species, biodiversity,

landscape ecology, and sustainable forestry.

Participants in this research include universities,

Government agencies, nonprofit organizations,

consultants, and industry. Several principles

have emerged from this research: stand structure

is important; larger spatial scales need to be

considered; habitat associations may be complex

but must be understood; landscape diversity

can increase biodiversity; abiotic factors, e.g.,

disturbance and site quality, can have profound

influences on biodiversity; and silvicultural

treatments can be used to enhance habitat quality

for a variety of species. Wigley and others suggest

that future research needs to continue to

Eric T. Linder1

1

 Assistant Professor, Mississippi State University, Department

of Biological Sciences, Mississippi State, MS 39762.
Southern Forest Science:

Past, Present, and Future

Biodiversity

304

investigate wildlife-forestry issues, especially

on managed forests, but that researchers

also need to propose affordable and practical

techniques for meeting biological objectives.

Bats (Myotis spp.) occupy a unique niche

and due to several life-history characteristics,

are relatively vulnerable to anthropogenic

stressors. Unfortunately, very little is known

about the ecology of most bat species and how

they respond to forest management (Loeb and

Krusac 2001). Research priorities for this group

should include: (1) determining distribution

and status, (2) determining habitat requirement

and associations, (3) determining effects of

management practices, (4) determining resource

partitioning, and (5) developing effective sampling

protocols and techniques. Baseline information

for bats is largely lacking, and this makes

management for this group potentially haphazard.

However, some habitat information does exist,

and management should focus on bats’ use

of snags, large-diameter hollow trees, riparian

zones, caves, mines, and bridges.

Carter and others (2001) describe the use

of multivariate techniques to identify landtypes

in the southern loam hills of south Alabama. Using

a combination of vegetation, landform, and soil

variables, they identify seven landtypes in this

system, each with a unique assemblage of plant

species. This approach can be used at the

landscape scale to identify specific land units,

which can be linked to specific management

decisions and used to detect assemblages that

may contain rare or endangered species.

Linder and others (2004) propose the use

of habitat-based population viability analysis

(PVA) to assess management alternatives over

relatively large spatial scales, e.g., national forests.

These models are constructed in a Geographic

Information System, which makes it possible to

conduct spatially explicit analyses. Models were

constructed using widely available data that cover

the extent of the study area. The response variable

was presence or absence of the target species,

while the explanatory variables included stand

age, forest type, and a suite of measurements of

the physical characteristics of the area in question,

such as elevation. By including forest age and

type, Linder and others were able to generate

and project virtual forests in the future. In this

study, they generated five different virtual forests,

based on different levels of timber harvesting and

natural disturbances, at 10-year increments over a

60-year period. This approach could be applied to

additional species or use diversity measures

such as species richness to assess potential

impacts of various management strategies.

Rather than using future scenarios to aid in

management decisions, Bragg (2001) proposes

using a historical reconstruction of forest

conditions to aid in the reconstruction of forests

and the conservation of biodiversity. He

demonstrates this approach by showing how

it would be applied to shortleaf (Pinus echinata

Mill.) and loblolly pine (P. taeda L.) stands in

southern Arkansas. Using a variety of information

sources including lumber operation records,

travelers, scientific reports, land surveys, and

historical photographs, he delineates reference

stand conditions. Early evidence suggests

that historical basal area was much lower than

previously thought, but with more large trees

than now occur in old-growth forests. The spatial

heterogeneity was also much more complex in

historical forests than contemporary forests, but

the understory and litter levels of historical forests

resemble those of contemporary forests. The goal

of this approach is to determine structural and

compositional features of ecosystems to which

species were historically adapted, which should

aid in the preservation of those species.

Harrington and Edwards (2001) explain in

detail how they experimentally restored the

abundance and diversity of the herbaceous

understory in longleaf pine (P. palustris Mill.)

plantations. They quantified the consequences

of competition for light, water, and nutrients, and

then compared these consequences to the potential

smothering, mulching, or nutrient cycling effects

of pine needle fall. Their results show the value

of maintaining low-stocking levels of pines and

limiting the encroachment of hardwoods or shrubs.

Prescribed fire is also beneficial in reducing

the needle-fall accumulation on the forest floor.

Experiments like this one can be used to show

managers how to restore communities and

historical ecosystem conditions.

Sites formerly occupied by longleaf pine

stands may also be used by restoration ecologists

as seed banks for other rare or threatened species.

Walker (2001) examined such sites, since converted

to loblolly pine plantations, and existing longleaf

stands on the Coastal Plain of North Carolina.

She conducted vegetation surveys and used

the seedling emergence technique to examine the

seed bank. Over 35 species and 1,000 individuals

germinated, and the seed banks from both sites

contained species not recorded during surveys.
305

Of the 35 species, many were weedy, but many

were also indicative of stable longleaf communities.

This study suggests that seed banks remain viable

in highly disturbed longleaf pine communities,

offering one more tool for the restoration ecologist.

Experiments may provide additional

insight into how forest management can affect

biodiversity. For example, Rosson and Amundsen

(2004) examined the impact of harvest disturbance

on tree species diversity at the landscape scale.

Timber harvesting has been a major disturbance

in the South over the past century, and with recent

reductions in harvesting in other regions of the

country, more pressure has been put on southern

forests. Rosson and Amundsen examined data

collected in Mississippi by the Forest Inventory

and Analysis Research Work Unit of the U.S.

Department of Agriculture Forest Service. Tree

species richness in plots where no harvesting

occurred was compared with tree species richness

for harvested and unharvested plots combined.

Tree species richness decreased by 11 percent

from 1977 to 1994 for all plots combined, but

it increased by 44 percent from 1967 to 1994

on the plots that were not harvested. Other

factors have certainly contributed to the decline

in species richness across forests in the South,

but harvesting is suggested to be a significant

factor in this study.

Southeastern forests house a rich herpetofauna,

but declines in populations of many species have

prompted ecologists to examine how management

activities may be affecting this group (Russell and

others 2004). Lanham and others (2001) studied

the herpetofauna in recently harvested gaps in

bottomland hardwood forests in South Carolina.

Specifically, they compared herpetofaunal use

of ephemeral, skidder-created ponds with use

of natural depressional wetlands. Salamanders

appeared to be affected negatively by skidder

trails and gap creation. Response of frogs was

mixed, with hylid abundance greater in gaps

but Rana spp., Nerodia spp., Chelydra sp., and

Eurycea sp. more abundant in skidder-created

ponds. Species diversity also appeared to increase

along skidder trails. Results suggest that overall

abundance did not differ between treatments,

but community composition may be changed if

habitat suitability for some species is changed.

Baughman and Guynn (2001) studied

herpetofauna assemblages in intensively managed

loblolly pine plantations in South Carolina. The

goal of this study was to assess the baseline

herpetofauna assemblages before installation

of a complex corridor system. These assemblages

were consistent with those on other sites in the

Southeast in terms of diversity and relative

abundances of the groups under consideration

(anurans > salamanders > reptiles > turtles).

Despite the apparent consistency between sites,

small differences in abundance were found, which

could lead to misleading conclusions without

pretreatment sampling.

Haskell and others (2001) examined how

the avian community varied across habitats on

the Cumberland Plateau in southern Tennessee.

Species richness was consistently lower in loblolly

pine plantations than in oak-hickory (Quercus

spp.-Carya spp.) forests, and abundance was lower

in most plantations. Plantations had fewer cavityand tree-nesting species, and fewer Neotropical

migrants, than did oak-hickory forests. Thinned

forests seemed to have higher avian species

richness, evenness, and abundance than oakhickory forests had. Haskell and others also

studied how avian communities change with

respect to human development. They found

that residential and rural areas exhibited higher

species richness, evenness, beta diversity, and

abundance than did oak-hickory forests. Using

Partners in Flight priority scores, which were

assigned to each species, they quantified and

ranked the conservation value of each habitat

type considered. This approach appears to

support results from direct comparisons, yielding

a conservation ranking (from greatest to least)

of residential-rural areas, thinned forests, oakhickory forests, and pine plantations.

Many habitats in the Southeast—and in

other parts of the world—are threatened by

degradation, fragmentation, conversion, invasion

by nonnatives, loss, and other problems. If recent

demographic trends continue, more stress

will be placed on the habitats and biodiversity

of the Southeast. Although there is interest in

afforestation (conversion of nonforest land to

forest), application of afforestation in the areas

where this is most economically suitable may

actually reduce regional biodiversity (Matthews

and others 2002). Consequently, it is likely that

pressure on our forest resources will continue

to mount. The scientific community has a

responsibility to provide landowners and the public

with information that help us to meet demands on

our natural resources while maintaining native

biodiversity. The creation and refinement of tools

used by ecologists, e.g., PVA gap analysis, and

is one such contribution. Furthermore, because

many of the threats to biodiversity involve

Chapter 25.

 Biodiversity
Southern Forest Science:

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Biodiversity

306

ecosystem processes or large spatial scales, it

will be necessary to have cooperation between

universities, nongovernmental organizations,

private landowners, and public land managers.

LITERATURE CITED

Baughman, W.M.; Guynn, D.C., Jr. 2001. Herpetofauna

assemblages in intensively managed pine plantations. In:

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eds. Proceedings of the southern forest science conference.

http://www.southernforestscience.net/. [Date accessed: July

20, 2004].

Bragg, D. 2001. Conserving biological diversity through

reconstruction of historical forest conditions. In: Johnsen,

K.H.; Rauscher, M.; Hubbard, W.G.; Jordin, J.B., eds.

Proceedings of the southern forest science conference.

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July 20, 2004].

Carter, R.E.; MacKenzie, M.D.; Gjerstad, D.H. 2001.

Landscape scale classification of longleaf pine ecosystems in

south Alabama. In: Johnsen, K.H.; Rauscher, M.; Hubbard,

W.G.; Jordin, J.B., eds. Proceedings of the southern forest

science conference. http://www.southernforestscience.net/.

[Date accessed: July 20, 2004].

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J.B., eds. Proceedings of the southern forest science

conference. http://www.southernforestscience.net/. [Date

accessed: July 20, 2004].

Harrington, T.B.; Edwards, M.B. 2001. Overstory and

understory interactions in longleaf pine plantations:

implications for community restoration. In: Johnsen,

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2001. Vertebrate communities in a changing landscape:

a case study of birds and salamanders on the southern

Cumberland Plateau. In: Johnsen, K.H.; Rauscher,

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of the southern forest science conference. http://

www.southernforestscience.net/. [Date accessed:

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Lanham, J.D.; Cromer, R.B.; Hanlin, H.H. 2001. Functional

response of herpetofauna to harvested gaps and skidderrut wetlands in a southern bottomland hardwood forest.

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conference. http://www.southernforestscience.net/.

[Date accessed: July 20, 2004].

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viability as a measure of forest sustainability. In: Rauscher,

H. Michael; Johnsen, Kurt, eds. Southern forest science:

past, present, and future. Gen. Tech. Rep. SRS–75. Asheville,

NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station: 307–317.

Loeb, S.C.; Krusac, D.L. 2001. Bats in southern forests:

critical research and management needs. In: Johnsen,

K.H.; Rauscher, M.; Hubbard, W.G.; Jordin, J.B., eds.

Proceedings of the southern forest science conference.

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July 20, 2004].

Matthews, S.; O’Connor, R.; Plantinga, A.J. 2002. Quantifying

the impacts on biodiversity of polices for carbon

sequestration in forests. Ecological Economics. 40: 71–87.

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species diversity over large spatial and temporal scales. In:

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science: past, present, and future. Gen. Tech. Rep. SRS–75.

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Russell, K.R.; Wigley, T.B.; Baughman, W.M. [and others]. 2004.

Responses of southeastern amphibians and reptiles to forest

management: a review. In: Rauscher, H. Michael; Johnsen,

Kurt, eds. Southern forest science: past, present, and future.

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319–334.

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the decline of natural southern yellow pine forests. In:

Rauscher, H. Michael; Johnsen, Kurt, eds. Southern forest

science: past, present, and future. Gen. Tech. Rep. SRS–75.

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Walker, J. 2001. Advances in rare plant biology: implications

for management. In: Johnsen, K.H.; Rauscher, M.; Hubbard,

W.G.; Jordin, J.B., eds. Proceedings of the southern forest

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[Date accessed: July 20, 2004].

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Wildlife in managed forests: the evolution of research in

the South. In: Johnsen, K.H.; Rauscher, M.; Hubbard, W.G.;

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accessed: July 20, 2004].
307

Chapter 26.

Population Viability

as a Measure of Forest Sustainability

Eric T. Linder, Nathan A.

Klaus, and David A. Buehler1

Abstract—Many forest managers work to balance

timber production with protection of ecological

processes and other nontimber values. The

preservation of biodiversity is an important

nontimber value. When a suite of management

options is being developed, it is difficult to estimate

quantitatively the impact of the various scenarios

on biodiversity. We suggest population viability

analysis (PVA) as a tool for estimating the

quantitative impact of landscape modifications

on species. Using a habitat-based approach to

PVA, we examine the potential effects of five

management alternatives on the chestnut-sided

warbler (Dendroica pensylvanica), a managementindicator species, on the Cherokee National Forest

in Tennessee. This analysis shows that population

size is positively correlated with disturbance.

It also appears that without active management,

this species, which is dependent upon early

successional forests, may not find enough suitable

habitats to maintain viable populations over the

next 50 years. Although habitat-based PVA

is demonstrated here for a single species, it

has been modified to assess large biota. Habitatbased PVA is a useful tool for those who must

assess the potential impact of landscape

modification on biodiversity.

INTRODUCTION

D

uring the late 1800s and early 1900s,

the forests of the Southern United States

were overexploited and mismanaged in ways

that resulted in depletion of timber resources,

extensive erosion, degradation of water quality,

and negative impacts on wildlife habitat and

wildlife populations. The latter half of the 20th

century saw the emergence of new attitudes

regarding land use by private and public

landowners. Legislation such as the MultipleUse Sustained-Yield Act of 1960 and the National

Forest Management Act of 1976 requires that

national forests be managed for both timber

and nontimber values. Today, forest managers

are beginning to work to achieve ecological

sustainability on both public and private lands

(Kohm and Franklin 1997). Pursuit of ecological

sustainability includes efforts to maintain

ecosystem functions and processes, timber

production, and nontimber values. Biological

diversity, or biodiversity, is an important

nontimber value. Biodiversity is diversity at the

genetic, species, landscape, and ecosystem level

(Noss and Cooperrider 1994). However, it can be

difficult to assess the success of management for

biodiversity (Botkin and Talbot 1992). Managing

for biodiversity requires the development of

strategies for monitoring the flora and fauna

of the area in question (Lindenmayer and others

1999). Only a few researchers have described

organized approaches to planning for biodiversity

as an objective of multiple-use management

(Kuusipalo and Kangas 1994, Millar and others

1990, Probst and Crow 1991).

Management to conserve biodiversity or to

avoid species extinction is generally addressed

at the scale of a species geographic range, which

may extend across many political boundaries,

ecoregions, or even continents. Species that are

widespread and abundant are generally of little

management concern, although nonnatives and

1

 Assistant Professor, Mississippi State University,

Department of Biological Sciences, Mississippi State, MS

39762; Wildlife Biologist, Georgia Department of Natural

Resources, Forsyth, GA 31029; and Professor, University of

Tennessee, Department of Forestry, Wildlife, and Fisheries,

Knoxville, TN 37901, respectively.
Southern Forest Science:

Past, Present, and Future

Biodiversity

308

pests are notable exceptions to this rule. Most rare

species are of management concern, however, and

since most managers work on a spatial scale that

is small relative to a species global distribution,

preserving biodiversity is really a matter of

preserving populations. Small populations are

subject to environmental stochasticity and many

other uncertainties and are consequently more

at risk of extinction. Thus, if populations are to

persist, they must be adequately large (Menges

1990, Pimm and others 1988).

It is generally acknowledged that a greater

diversity of habitat types is positively correlated

with greater biodiversity. Forest management

generally affects the composition and spatial

arrangement of forest stands at the landscape

scale. Different management practices can

produce profoundly different habitat conditions.

Industrial forest lands, for example, may support

large (> 50 ha) even-aged stands of trees of

a single species; e.g., loblolly pine (Pinus taeda

L.). Biodiversity in these managed forests

can be enhanced by maintaining a diversity of

stand-age classes and stand-size classes across

the landscape. Other silvicultural practices that

modify forest habitat conditions include thinning

and prescribed burning. It can be difficult to

predict the consequences when habitat conditions

are modified over large areas. For this reason,

tools that assess landscape change can be

particularly valuable. The use of spatially explicit

habitat models is one such tool (Dunning and

others 1995).

Population viability analysis (PVA) has been

used to predict the likelihood that a population

of a single species will persist over a given time

period (Boyce 1992, Nunney and Campbell 1993,

Soulé 1987). The relative merits of the criteria

used in such analyses have been discussed

elsewhere (Mace and Lande 1991). Early PVA

employed deterministic models that examined the

management of endangered species and relied

solely on demographic analyses (Miller and Botkin

1974). Later, population models that incorporated

demographic and environmental stochasticity

were developed (Menges 1990; Shaffer 1981,

1983). Since these models account for a portion

of the stochastic events characteristic of small

populations, this marked a dramatic improvement

in PVA. In 1986, the conceptual framework of

PVA was broadened to include a comprehensive

examination of factors that can affect the

persistence of populations (Gilpin and Soulé

1986). Population persistence is subject to

variation arising from several sources, including

stochastic, demographic, temporal, spatial,

individual, and other processes (White 2000).

One challenge associated with the use of PVA is

an accurate estimate of the variation induced by

such processes. A number of researchers have

studied parameter estimation and its influence on

model performance (Akcakaya and others 1997,

Burgman and others 1993, Conroy and others

1995, Dennis and others 1991, Groom and Pascual

1998, Ludwig 1999, Taylor 1995, White 2000).

One outcome of quantifying population

persistence is the concept of the minimum viable

population size (MVP) (Harris and others 1987).

An MVP is an estimate of the minimum number of

individuals required to constitute a population that

can persist for a given time period. There has been

considerable debate about the characteristics of

MVPs (Harris and others 1987, Henriksen 1997,

Thomas 1990). Many aspects of species biology

must be considered when workers attempt to

determine what the MVP is, and these aspects

will vary across taxa and with circumstances, e.g.,

genetic variability, mating system, reproductive

power. PVA has continued to evolve as a

conservation tool and now includes demographic,

genetic, and spatially explicit models (Beissinger

and McCullough 2002, Young and Clarke 2000).

The various roles played by PVA have been

summarized by Burgman and Possingham (2000).

The most common approach to PVA is to

model species demography. This usually occurs

when species abundance is relatively low, and

there are relatively few populations. Demographic

PVA has been conducted for dozens of species, and

these analyses have ranged from simple population

projections to spatially explicit, individual-based

models that include heterogeneous landscapes

and age-specific demographics (Beissinger and

Westphal 1998). One especially interesting aspect

of demography is sensitivity analysis (Crouse and

others 1987, Mills and others 1999), which can be

used to determine which demographic parameter,

e.g., juvenile survival, birth rate, has the greatest

impact on the population growth rate. Managers

can plan their actions in accordance with such

analysis, but the use of this method does not

guarantee success.

When a single population is under

consideration, demographic model development

is relatively straightforward but is affected by

the type and quantity of data under consideration

(Morris and others 1999). When the spatial scale
309

is sufficiently large or when multiple populations

are under consideration, a new approach may

be useful. For example, one can include a spatial

component in the model. This component can be

explicit (Lindenmayer and Possingham 1996) or

nonexplicit (Hanski and others 1996). Both of these

approaches have merits, and both are consistent

with the use of PVA to make specific spatial

decisions. This makes PVA an extremely valuable

conservation and management tool. However, a

major drawback of spatially explicit models is that

it takes additional data to construct and run them.

Also, the use of additional model parameters may

negatively impact predictability (Ruckelshaus

and others 1997). It is up to the modeler to decide

whether a more complex model, which typically

represents a more biologically realistic depiction,

is preferable to a simpler model that requires less

time and effort to construct.

Because count data are easily collected and

relatively inexpensive, they are commonly

available to land managers. Count data can be

used to construct simple time-series models for

the projection of population estimates (e.g., Boyce

and Miller 1985, Dennis and others 1991). It is

important to know whether a population trajectory

is based on data for a single population or for

several populations. Because a species may be

declining in some populations while increasing

in others, it can be very helpful to incorporate

spatial structure into population models (Stacey

and Taper 1992, White 2000). Another factor to

be considered is the adequacy of the time span

employed. Morris and others (1999) suggest

that a minimum of 10 years be used. However,

even when a long-term dataset, e.g., 26 years,

is employed, conclusions about population

persistence can become outdated quickly when

populations change abruptly (Boyce 2001, Dennis

and others 1991). Finally, although time-series

models are useful in determining population

trajectories, they offer no insight into the

processes driving the population decline.

Another approach to PVA is to examine the

ecological factors associated with population

decline or population stochasticity. Loss or

degradation of habitat is the most significant

threat facing species (Pimm and Gilpin 1989,

Wilcox and Murphy 1985). Habitat loss is

listed as a significant threat for 82 percent of

endangered bird species (Temple 1986). Other

factors that can reduce the viability of a population

include predators, nonnative species, parasites,

and disease. However, ecological variables are

rarely addressed in PVA because of the difficulty

of collecting the necessary data and incorporating

them into analyses (Boyce 1992).

In response to criticism surrounding the

use of only demographic-based PVA for land

management decisions (Harrison 1994, Taylor

1995), researchers attempted to develop a habitatbased approach (Roloff and Haufler 1997, White

and others 1997). Two approaches have been

developed, and both are based upon concepts

rooted in community and population ecology.

Community ecologists have developed the concept

of minimum area requirements, while population

biologists have emphasized minimum population

size (Soulé 1987). Both approaches quantify the

habitat available in a given landscape and then

estimate the sustainable population size. Both

assess a landscape’s potential (the amount of

suitable habitat available for the target species)

but differ in their assessment of the detail of

data required to conduct risk analysis. White and

others (1997) use general habitat relationships

to determine habitat suitability, while Roloff and

Haufler (1997) use an empirically derived, spatially

explicit habitat model. Both approaches utilize

presence and absence data, which can be collected

with considerably less time and effort than

demographic data.

The use of PVA is important in mitigating

the negative effects of landscape change on

biodiversity (Burgman and others 1993). Habitat

loss and fragmentation continue to challenge

conservationists. PVA models have evaluated

the impacts of habitat fragmentation or loss

(Lindenmayer and Possingham 1994, McCarthy

and Lindenmayer 1999, Noon and McKelvey

1996), established area requirements (Goldingay

and Possingham 1995), and aided in optimizing the

design of nature reserves (Burgman and others

1993, Lindenmayer and Possingham 1994).

However, PVA has limitations that should be

recognized (McCarthy and others 1996, Taylor

1995). The most useful products of a PVA may not

be the absolute numbers or statistics generated,

but rather the relative values generated under

various management scenarios (Boyce 1992).

Relative impacts of various management

scenarios have been assessed for a handful of

species (Drechsler 1998, Haig and others 1993,

Lindenmayer and Possingham 1996, Pfab and

Witkowski 2000). In the present case study,

we use habitat-based PVA to examine the impact

of various management scenarios on the viability

of forest songbirds.

Chapter 26.

 Population Viability
Southern Forest Science:

Past, Present, and Future

Biodiversity

310

CASE STUDY

T

he management of public lands is a central

element of national environmental policy in

the United States. The management practices

employed on public lands today are an outgrowth

of past practices, growing awareness of ecosystem

importance, and conflicts over various issues,

e.g., wilderness vs. timber production. Attempts

to resolve these issues can be expensive for

all parties concerned. For example, the USDA

Forest Service spends over $5 million annually

on lawsuits regarding proposed sales of timber on

land it manages (U.S. Department of Agriculture,

Forest Service 1997). One contentious issue is the

role of timber management in the management of

our national forests. Impacts on native flora and

fauna have been cited as reasons for limiting

timber harvests (Harwood 1997). Many studies

have examined the impact of forest management

on a variety of plant and animal groups. In this

study, we focus on impacts on forest songbirds.

Most studies associated with bird communities

and timber management examined the impact

of a particular treatment on community structure.

This is done by examining the bird community

before and after harvests. Most such studies have

concluded some species are negatively impacted

by timber harvesting and that other species

benefit from it (Thompson and others 1992).

From a management perspective, this suggests

that timber harvesting may be a viable option for

the management of habitat for some songbirds.

Natural disturbance has always shaped forest

communities; anthropogenic disturbance, e.g.,

silviculture, has had an important role in shaping

North American forest communities for the past

200 years (Smith and others 1996). The frequency,

intensity, and type of disturbance affect forest

structure and composition. Bird communities

change dramatically in response to these changes

in habitat conditions (Newbold 1996).

We considered two silvicultural methods in

this case study: even-aged and uneven-aged timber

harvesting. On the Cherokee National Forest

(CNF), recent even-aged management consists

of relatively small clearcuts averaging 10 ha

in area. Clearcutting has been the preferred

regeneration system on the CNF for the past

30 years. However, because of public opposition

to clearcutting, uneven-aged management

may predominate in the future. The CNF uses

group-selection cuts that result in a forest that is

structurally diverse at the understory, midstory,

and canopy levels. This approach results in forests

that have structural attributes similar to those

of old-growth forests (Annand and Thompson

1997, Thompson 1993). However, uneven-aged

harvesting is a relatively recent silvicultural

approach and, consequently, few studies have

evaluated its potential as a management tool

(Annand and Thompson 1997, King and others

2001, Twedt and others 2001). The goals of this

case study are to assess the effects of various

management alternatives on the viability of the

chestnut-sided warbler (Dendroica pensylvanica)

(CSWA), a forest songbird. To achieve this, we

ask three basic questions:

1. Are current harvest levels adequate to

support viable populations of CSWAs?

2. What is the impact of natural disturbance

in providing habitat for the CSWA?

3. What timber harvesting strategy best

promotes the viability of the CSWA

on the CNF?

We show how a habitat-based PVA can be

used to assess the impact of various management

scenarios on CSWA, a species that is typically

associated with early succession forests.

METHODS

P

oint-count data collected in the CNF during

the 1992–96 breeding seasons were used to

construct a habitat model. Standardized avian

census methods were employed (Hamel and others

1996). Habitat variables were derived from the

Forest Service’s Continuous Inventory of Stand

Conditions (CISC) database and the Southern

Appalachian Assessment database. Variables

included forest type, condition class, stand age,

site index, and elevation (table 26.1). Both

databases exist in a Geographic Information

System, and our analysis was conducted at a pixel

resolution of 30 m2

, which is a scale appropriate

for our target species. We used stepwise logistic

regression (PROC LOGISTIC) (SAS/STAT 1990)

with a P < 0.10 level to build a habitat model

to predict the occurrence of CSWAs. The habitat

model was then applied back onto the CNF,

creating a probability surface that reflected the

likelihood of occurrence of breeding territories

ranging from zero to one. To estimate the amount

of suitable habitat on the CNF, we multiplied the

likelihood of occurrence for each stand by that

stand’s acreage. The products are similar to the

habitat units (HU) in a Habitat Suitability Index

model (Schroeder 1983), which for this case study,

is equal to 1 ha of suitable habitat. To convert the

products into an estimate of the potential to
311

support a given breeding population, we summed

the products across the study area and multiplied

the total by the average breeding density of CSWA

from Hamel (1992). We used a minimum viable

population size of 250 breeding pairs, a very

optimistic estimate, as the critical threshold

below which the species would not persist. To

avoid overestimation of available habitat on the

strength of marginal probabilities of occurrence,

we stipulated that habitat would not be considered

suitable where the probability of occurrence was

< 75 percent. Habitat patches that were less than

one territory in size were not considered suitable.

In this exercise, we projected figures from

CISC databases 60 years into the future. This was

accomplished by using a SAS-based forest model

to simulate even-aged and uneven-aged timber

harvests. The management alternatives developed

varied with forest type, total area harvested per

10-year interval, relative proportion of even-aged

to uneven-aged harvesting (area basis), group size,

and intensity of harvest. Specific variation of

intensities and harvesting methods were based

on past harvesting practices and expert opinion

of the district silviculturists. Since our target

species is associated with early succession habitat,

we also considered the rate at which forests were

restoring themselves naturally. Consequently, we

modeled five natural disturbances on the basis

of existing literature and historical averages for

this region. Natural disturbances included fire,

ice, wind, southern pine beetle (Dendroctonus

frontalis Zimmermann), and hemlock woolly

adelgid (Adelges tsugae Annand). Each was

assigned randomly to forest stands that could be

affected by the type of disturbance; e.g., southern

pine beetle did not impact northern hardwood

stands. For each simulation, virtual forests were

updated every 10 years.

Five scenarios were simulated, each with a

different intensity of disturbance: no timber

harvesting or natural disturbance, no harvesting

but natural disturbance, harvesting at expected

level (based on recent average harvests on the

Table 26.1—Habitat variables and descriptions used to construct

chestnut-sided warbler model

Habitat variable Description Range

Age (years) Current age of stand 0 – 172

Forest type

Yellow pine Yellow pine forest 0 – 1

White pine-hemlock White pine or hemlock forest 0 – 1

Cove hardwood Cove hardwood forest 0 – 1

Northern hardwood Northern hardwood forest 0 – 1

Mixed hardwood-pine Mixed hardwood and pine forests 0 – 1

Oak-hickory Oak-hickory forest 0 – 1

Stand-condition class

Seed Seedling-sapling 0 – 1

Pole Poletimber 0 – 1

Saw Sawtimber 0 – 1

Site index (feet)

Site index 1 Site potential, dominant 4 – 130

 tree height in 50 years

Site index 2 Site index < 70 0 – 1

Site index 3 70 < site index < 80 0 – 1

Site index 4 80 < site index < 110 0 – 1

Elevation (m)

Elevation 1 Elevation 231 – 1530

Elevation 2 Elevation < 475 0 – 1

Elevation 3 475 < elevation < 872 0 – 1

Elevation 4 Elevation > 872 0 – 1

Chapter 26.

 Population Viability
Southern Forest Science:

Past, Present, and Future

Biodiversity

312

1,200

1,000

800

600

400

200

300 percent cut

200 percent cut

Expected cut

1993 2003 2013 2023 2033 2043 2053

Breeding pairs (number)

Year

No cut

No disturbance

CNF), 200 percent of expected harvest, and

harvesting at 300-percent expected levels. These

scenarios offered a range of disturbance intensities

and allowed us to assess the impact of various

management practices compared to natural

disturbance rates. Using the ArcView Spatial

Analyst extension (Environmental Systems

Research Institute 1996), we calculated the area

of each habitat patch for each simulation. Number

of habitat units was calculated for each 10-year

interval and so that the habitat potentials for the

disturbance scenarios could be compared easily.

We also conducted sensitivity analysis on the

habitat variables to test their relative importance.

Each forest simulation was run repeatedly, with

systematic manipulation of input variables at each

harvest level and at levels 30 percent above and

below each harvest level. The OPTEX procedure

(SAS 1990) was used to identify a subset of

variable settings, and this reduced the number

of iterations necessary. The response of total

HUs to each habitat variable was then tested

using the general linear model procedure (PROC

GLM) (SAS 1990). Sensitivity analysis quantified

the importance of each variable independent of

the relative abundance of each forest type. This

approach was also used to compare the influence

of management alternatives across forest types.

RESULTS

T

he CSWA is relatively uncommon in our

study area, occurring on 14 percent of census

points. The CSWA model included positive

associations with elevation, seedling and/or sapling

condition class, site index, and several forest types

(table 26.1). Variation explained (indicated by

max-rescaled R-square) was 0.6484. The correct

classification percentage (concordance) was 95.6,

which is relatively high. The Hosmer-Lemeshow

goodness-of-fit test (Hosmer and Lemeshow 1989)

indicated that the fit of the data was acceptable

at P > 0.05. The CSWA model indicated that

preferred habitat consisted of young productive

forests at elevations > 1000 m.

Characteristics of high-quality habitat varied

across the landscape, with northern hardwoods

providing the greatest breeding opportunities

(662 HUs), followed by oak-hickory (520 HUs),

mixed pine-hardwood (113 HUs), yellow pine (48

HUs), and hemlock-white pine (34 HUs). CSWA

habitat was positively associated with most types

of disturbance, including (in order of descending

importance) area of even-aged harvesting in oakhickory, area of disturbance by ice and or wind,

area of even-aged harvesting in cove hardwoods,

area of uneven-aged harvesting in oak-hickory,

and area of even-aged harvesting in mixed pinehardwoods. Disturbance by fire, southern pine

beetle, and hemlock woolly adelgid were not

related to habitat availability for CSWA. Not

surprisingly, the strongest negative association

with habitat availability was the association with

forest age. Sensitivity analysis indicated that most

forms of disturbance were extremely important

in generating suitable habitat. Ice and/or wind

disturbance was the only natural disturbances

that were of much importance, however.

At expected levels of harvesting, the amount

of suitable CSWA habitat increased slightly (8

percent) from 1993 to 2053. Based on an average

breeding density of 11.9 breeding pairs per 40

ha (Hamel 1992), the initial landscape in 1993

could support approximately 416 breeding pairs.

Based on the various disturbance scenarios, the

landscapes could support from 250 to 790 breeding

pairs in 2053, with suitable habitat being positively

correlated with disturbance (fig. 26.1). Thus all

disturbance scenarios considered provided

adequate habitat to ensure viability (MVP =

250). In the 300-percent harvesting scenario, the

number of HUs available increased dramatically

the first three decades and declined over the

last two decades. The decline in suitable habitat

resulted from maturation of trees in the previously

harvested areas and a lack of stands suitable for

harvesting in the latter years of this simulation.

Figure 26.1—Habitat potential for the chestnut-sided warbler

on the Cherokee National Forest under five management

alternatives over a 60-year time horizon.
313

DISCUSSION

D

isturbance is vital to the maintenance of

habitat for CSWA. However, sensitivity

analysis suggests that natural disturbance

contributes relatively little to the creation of

habitat suitable for CSWA on the CNF. If viable

populations of CSWA are to be maintained, it may

be necessary to create additional suitable habitat

by means of active management.

Only habitat variables found in the CISC

database were employed in this study. The virtual

forests regenerated by timber harvesting were

very similar, in terms of CISC variables, to forests

regenerated by natural disturbance. For example,

simulated clearcuts and wildfires reset condition

class and age to identical values. In actual systems,

disturbances of these types are likely to produce

dissimilar biological results. Schulte and Niemi

(1998) found that key habitat characteristics of

logged and burned sites differed significantly, and

that this resulted in avian richness and abundance.

Similarly, there were structural differences

between forests that had been disturbed by

tornadoes and those that had been clearcut

(Newbold 1996). Again there were differences

in avian community composition, but diversity

did not vary with source of disturbance in this

instance. Natural disturbance should be

incorporated into habitat models systems

in which it can play a significant role.

Habitat for CSWA can easily be created

through forest management. It is possible

to manage for species associated with latesuccessional forest by allowing forest stands

to age, but it may take decades for high-quality,

late-successional habitat to develop. It may be

necessary to use silvicultural treatments to

promote development of structural characteristics,

e.g., snags, cavities, or den trees, important to

species dependent on this habitat. The challenge

for managers is to provide the balance of habitat

types, seral stages, and landscape configurations

that is most suitable for the desired diversity

of species.

The results of this particular study are

relatively clear with respect to CSWAs, as the

management alternatives evaluated were distinct

and only the intensity of harvesting varied among

simulations. Because the approach we employed

is spatially explicit, we could have compared

the relative effects of several scenarios while

maintaining consistent harvest volume. A spatially

explicit approach can also be used to assess the

effects of several different landscape

configurations. Researchers have developed

decisionmaking tools for assessing scenario

outcomes in studies that yield results that are

less clear (Burgman 2000, Drechsler 2000).

Several potentially conflicting ecological,

social, and economic factors must be accounted

for when planners attempt to formulate the best

land use plan for a tract of land. Various pressures

are causing researchers, managers, and the

general public to devote more attention to the

problem of preserving biodiversity (Kuusipalo

and Kangas 1994, Lindenmayer and others 1999).

The preservation of biodiversity implies the

maintenance of viable populations of all species

deemed desirable. While PVA is a useful

management tool, it is not possible to conduct

intensive analyses for each species within the

area of interest. It may be necessary to conduct

analyses only for indicator species. The use

of indicator species is meant to make it possible

to estimate the responses of multiple species

to a variety of alternatives without addressing

the requirements of each species individually. The

appropriateness, advantages, and disadvantages of

using indicator species in planning for sustainable

forestry has been addressed elsewhere

(Lindenmayer and others 1999).

There are several criticisms of demographicbased PVAs (Harrison 1994, Taylor 1995).

However, a recent retrospective analysis of the

predictive accuracy of PVAs clearly demonstrated

their value as a management tool (Brook and

others 2000). One study that made use of spatially

explicit models and specific management plans was

conducted by Liu and others (1995) who examined

the potential effects of several management

practices on Bachman’s sparrow (Aimophila

aestivalis). This species breeds in open, mature

pine stands, which are also being managed

for the endangered red-cockaded woodpecker

[Picoides borealis (Vieillot)]. In their analysis,

Liu and others (1995) considered several aspects

of management, including thinning, burning,

and harvesting. Results indicated that certain

harvesting practices, such as clustered harvesting,

produced a landscape more favorable to juvenile

dispersal and subsequent survival. Age-specific

thinning and burning of some stands made them

suitable as habitat at an earlier age. One of the

important findings of this study is that Bachman’s

sparrow and red-cockaded woodpecker apparently

require very different management, although both

species are associated with mature pine stands.

Chapter 26.

 Population Viability
Southern Forest Science:

Past, Present, and Future

Biodiversity

314

In this system, the threat of habitat resulting

from stochastic events is relatively high (Dunning

and Watts 1991), which increases the likelihood

of extinction because population size is small

(Shaffer and Samson 1985).

Another excellent analysis of forest

management and population viability was

Lindenmayer and Possingham’s (1996)

study of the endangered Leadbeater’s possum

(Gymnobelideus leadbeateri). This species

is associated with ash forests (Eucalyptus) in

Australia and prefers to nest in large trees that

are several hundred years old (Lindenmayer and

others 1991). The majority of suitable habitat for

this species is designated for timber harvesting,

which makes future viability of the species quite

uncertain. Using ALEX, a computer program for

PVA (Possingham and Davies 1995), Lindenmayer

and Possingham (1996) attempted to address some

of the issues related to the conservation needs

of Leadbeater’s possum. They increased the

usefulness of their PVA model by incorporating a

submodel to account for the spatial and temporal

variation in habitat quality. Results indicated that

spatial arrangement and size of habitat were

important factors in extinction risk. Landscapes

that contain fewer but larger patches of habitat

are often more suitable for species that depend

on old-growth forest, but Lindenmayer and

Possingham found that landscapes that contain

more and smaller habitat patches are more

satisfactory for Leadbeater’s possum.

A possible objection to the use of habitat models

is they are usually developed for a single species.

Using some sort of indicator species may alleviate

some, but not all, of the concerns associated with

the use of a single nonindicator species. One option

is to develop these models for a suite of species,

thus capturing the diverse ecological requirements

of most of the biota in question. White and others

(1997) developed a habitat-based approach to risk

assessment; they attempted to quantify the risk

of landscape change for all terrestrial vertebrates

in a particular county. Landscape changes were

largely socioeconomic in origin and thus partly

subject to control by county-level zoning

restrictions. The first steps in determining the

potential impact on biodiversity were to estimate

area requirements of each individual species and

then to determine the quantity of each habitat

type. Six possible future landscapes were

generated, with varying amounts of each habitat

type in each scenario. Because this was done

in a spatially explicit framework, patch size

could be determined, and this made it possible

to estimate carrying capacity of each patch for

each species. Species richness was calculated for

each landscape plan. Results indicated that some

land use plans were considerably more detrimental

to biodiversity than others. While this approach

lacks the precision of a single-species habitat

model, it undoubtedly requires less data than

many others, and this can make it a viable option

when workers are attempting to assess the effects

on the entire biota.

SUMMARY

O

ur study illustrates the use of PVA to assess

the relative merits of various management

alternatives, especially when lack of time or

money makes it impractical to collect demographic

data. If natural disturbance continues at historic

rates for the next 50 years, early successional

habitat may not be created rapidly enough to

sustain a viable population of CSWA. Managers

may have to actively disturb the landscape to

provide suitable habitat for species that utilize

early successional habitat and are less abundant

than CSWA. Species associated with latesuccession habitat are likely to see available

habitat continue to increase unless the frequency

and intensity of disturbance increase beyond

normal historical levels. Managers must balance

the need for additional habitat for early

successional species with the need to maintain

suitable habitat for late-successional species.

The approach we have outlined is firmly

based on established ecological principles and

is well suited for meeting management objectives.

Two factors that strongly influence population

viability are area of suitable habitat (Laurance

1991) and population size (Pimm and others

1988). Demographic models may be too resource

intensive for use in assessing the impact of future

landscape changes on an entire biota. Habitatbased PVA does require sound habitat models,

and thus an appropriate set of habitat variables

as well as reliable distribution data on the target

species (Roloff and Haufler 1996). Other concerns

related to the use of habitat models have been

addressed elsewhere (Beutel and others 1999,

Karl and others 2000). We advocate the use

of habitat-based PVA in management planning

where it is applicable.
315

ACKNOWLEDGMENTS

We thank Randy Dettmers and Arnold Saxton

for help with the forest simulation models

employed and the field assistants who have

helped gather data over the years. We also thank

the Forest Service, Laura Mitchell of the Forest

Service, and the silviculturists assigned to the

CNF for assistance with this project.

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Chapter 26.

 Population Viability

319

Chapter 27.

Responses of Southeastern

Amphibians and Reptiles

to Forest Management: A Review

Kevin R. Russell,

T. Bently Wigley, William

M. Baughman, Hugh G.

Hanlin, and W. Mark Ford1

Abstract—Forest managers in the Southeast

increasingly need information about amphibian

and reptile responses to silvicultural practices

in order to guide sustainable forestry programs.

A review of existing literature indicates that effects

of silvicultural practices on herpetofauna often

are region- and species-specific, with individual

taxa responding positively, negatively, or not at

all in the short term. Responses of herpetofauna

to forestry likely are influenced by adaptations

of taxa to historical disturbance regimes. Few

studies have evaluated long-term population

or landscape-level implications of silvicultural

practices for herpetofauna. Furthermore, many

existing studies lack pretreatment data, replication,

or appropriate reference conditions. We suggest

that future research focus on manipulative and

retrospective studies designed to identify forestry

practices that successfully blend economic

objectives with herpetofaunal conservation.

INTRODUCTION

F

orests of the Southeastern United States

support a rich diversity of amphibians and

reptiles (herpetofauna). Of the more than

450 species of herpetofauna native to North

America, approximately half occur in the

Southeast and roughly 20 percent, are endemic.

Over 100 species (45 amphibians, 59 reptiles,

excluding sea turtles) have been reported

from the Coastal Plain of South Carolina alone

(Zingmark 1978). Herpetofauna often are the

most abundant vertebrates in forest ecosystems

(Burton and Likens 1975, Congdon and others

1986); in the Southeast, they comprise up to 45

percent of vertebrate species, excluding fish

(Vickers and others 1985).

Several interrelated factors account for

this regional herpetofaunal diversity, including

tremendous variability in habitats related to a

complex matrix of physiography and disturbance

regimes (Sharitz and others 1992). Moreover

many species of southeastern herpetofauna

exhibit biphasic life histories, occupying both

terrestrial and aquatic habitats during annual

cycles (Gibbons and Semlitsch 1991).

Increasingly, forest managers are challenged

to balance production of forest products

with maintenance of environmental quality,

management of wildlife habitat, and conservation

of biodiversity (Moore and Allen 1999, Sharitz

and others 1992). Concerns about even-aged

management, and particularly clearcutting,

have prompted considerable research on effects

of timber harvesting on wildlife. Most research

has focused on mammals and birds, and other

vertebrates such as amphibians and reptiles have

received less attention (deMaynadier and Hunter

1995, Gibbons 1988, Moore and Allen 1999).

1

 Assistant Professor of Wildlife Ecology and

Management, University of Wisconsin – Stevens

Point, College of Natural Resources, Stevens Point,

WI 54481; Forest Wildlife Manager, National Council

for Air and Stream Improvement, Inc., Clemson, SC

29634; Southern Region Wildlife Biologist, Westvaco

Corporation, Summerville, SC 29484; Professor

of Biology, University of South Carolina Aiken,

Department of Biology and Geology, Aiken, SC 29801;

Research Wildlife Biologist, U.S. Department of

Agriculture Forest Service, Northeastern Research

Station, Parsons, WV 26287, respectively.
Southern Forest Science:

Past, Present, and Future

Biodiversity

320

Despite their presumed role in forest food webs

(Burton and Likens 1975, Congdon and others

1986), potential value as indicators of habitat

quality (Dunson and others 1992), and controversy

about global amphibian declines (e.g., Pechmann

and others 1991), herpetofauna often are not fully

considered in forest management decisions

(deMaynadier and Hunter 1995).

Questions about the compatibility of forestry

and conservation of herpetofaunal biodiversity are

driven largely by concerns that both terrestrial

and aquatic habitats for many species may be

degraded or eliminated in intensively managed

forests. In particular, the permeable eggs, gills,

and skin of amphibians make them potentially

sensitive to changes in both aquatic and terrestrial

habitats (Dunson and others 1992). To evaluate

these concerns, deMaynadier and Hunter (1995)

presented a comprehensive review of available

literature about effects of forestry on North

American amphibians. Several studies suggested

that clearcutting and other forest management

prescriptions had short-term impacts on some

amphibians, especially salamanders. However,

other work indicated that many species (1) were

relatively insensitive to forest management,

(2) recovered more rapidly after harvesting than

previously thought, or (3) responded positively

to forestry practices (deMaynadier and Hunter

1995). This literature review revealed that

amphibian responses to forest management

were complex and often specific to taxa or

regions (deMaynadier and Hunter 1995).

Since deMaynadier and Hunter’s (1995) review,

additional studies have provided new insights

about southeastern forestry and herpetofauna.

Also deMaynadier and Hunter’s (1995) review

did not address questions about reptiles, perhaps

because of the focus on global amphibian declines

(Gibbons and others 2000), or the historical

perception that forestry impacts on reptiles

generally were neutral or positive (Campbell

and Christman 1982, Welsh and Lind 1991).

Although evolutionary, morphological, behavioral,

and ecological differences between amphibians

and reptiles are substantial (Gibbons and others

2000), it is likely that these ectothermic tetrapods

will continue to be considered collectively from

both conservation and management perspectives

(Gibbons and Stangel 1999, Gibbons and others

2000). The purpose of this chapter is to provide

an up-to-date overview of information available

about responses of amphibian and reptile

populations to forestry practices in the

Southeastern United States.

OVERVIEW OF LITERATURE ON FORESTRY

AND SOUTHEASTERN HERPETOFAUNA

Harvesting and Silviculture

P

resumably the microclimatic, vegetational,

and structural changes that occur after timber

harvesting, and clearcutting in particular,

create unsuitable conditions for moisture- and

temperature-sensitive amphibians. DeMaynadier

and Hunter (1995) reviewed potential negative

effects of harvesting on microhabitats correlated

with amphibian species richness and abundance.

Timber harvesting removes forest canopy, and so

causes increased light penetration that results in

higher soil temperatures and more evaporative

loss of water from the soil and understory.

Cover, in the form of leaf litter, coarse woody

debris (CWD), and understory vegetation may

be reduced following clearcutting and associated

site preparation activities (Hunter 1990). Clearcut

areas also are subject to greater daily fluctuations

in temperature and humidity, and to increased

soil surface disturbance during intensive harvest

activities (deMaynadier and Hunter 1995).

However, it has been suggested by several authors

(e.g., Campbell and Christman 1982, Greenberg

and others 1994, Welsh and Lind 1991) that

clearcutting and other harvesting regimes often

create favorable habitats for heliothermic reptiles

adapted to early successional habitats.

Amphibians—Several studies in hardwood forests

of the Southern Appalachians appear to support

the contention that changes in microhabitats

and climate after clearcutting reduce amphibian

diversity and abundance, with negative effects

most pronounced on salamanders (Ash 1988, 1997;

Buhlmann and others 1988; Ford and others 2002;

Harpole and Haas 1999; Knapp and others 2003;

Petranka and others 1993, 1994). In northern

Georgia, stand age was an important factor

explaining the abundance and community

composition of plethodontid salamanders, e.g.,

Plethodon and Desmognathus spp., in cove

hardwood communities (Ford and others 2002).

In North Carolina, populations of plethodontid

salamanders in recent clearcuts were 40 percent

of those in undisturbed forested plots, and by the

fourth year after harvesting, no salamanders could

be found on clearcut sites (Ash 1988). Similarly

Petranka and others (1993, 1994) found that

plethodontid salamanders disappeared from

Appalachian forests after clearcutting and that

recovery to preharvest population levels took up to

60 years at high-elevation sites. Hyde and Simons

(2001) also reported that effects of disturbance on

the diversity and abundance of plethodontid
321

salamanders in the Great Smoky Mountains

National Park were still evident after 60 years.

Petranka and others (1993) hypothesized that

during the last century, clearcutting reduced

plethodontid salamander abundance by 70 percent

in western North Carolina alone, with current

harvest-related losses approaching 14 million

salamanders per year.

Three recent studies have evaluated effects

of uneven-aged harvesting techniques on

Appalachian salamanders. Harpole and Haas

(1999) compared abundance of plethodontid

salamanders before and after application of

seven treatments (understory removal, group

selection, two variants of shelterwood, leave

tree, clearcutting, reference) in low-elevation

hardwood forests in southwest Virginia. They

found that salamander numbers were lower after

harvesting on the group selection, leave tree, and

clearcut sites, but no postharvest differences were

detected during the same period on reference

or understory removal sites. However, Ford

and others (2000) detected no differences in

abundance of plethodontid salamanders among

group selection treatments, two-aged timber

harvests, and uncut control stands in highelevation, Southern Appalachian hardwood forests

of North Carolina. Bartman (1998) did not find

that shelterwood harvesting affected salamander

populations in the North Carolina Appalachians.

Although it appears likely that diversity and

abundance of plethodontid salamanders would

decrease after clearcutting, Ash and Bruce (1994)

and other authors (Ash 1997, Johnson and others

1993) argue that available data do not indicate that

the long-term losses predicted by Petranka and

others (1993, 1994) have occurred. For example,

Ash (1997) determined that plethodontid

salamander populations on previously clearcut

sites in the mountains of western North Carolina

returned to 100 percent of those in nearby

unharvested forests within 24 years of cutting,

rather than the 60 years reported by Petranka and

others (1993). Harper and Guynn (1999) also

reported that plethodontid salamanders appeared

to recover relatively quickly from clearcutting,

with salamander densities in stands 13 to 39 years

old (χ = 21 years) equal to those in older (≥ 40

years) stands.

Responses of amphibians to forest management

in other physiographic regions of the Southeast

are more complex, with studies reporting

individual species increasing, decreasing, or not

changing in abundance after clearcutting (Clawson

and others 1997, O’Neill 1995, Pais and others

1988, Perison and others 1997, Russell and others

2002b). Perison and others (1997) reported that

the overall abundance of amphibians was lower

in clearcuts than in forested stands in the upper

Coastal Plain of South Carolina, but they found

that certain species, such as green treefrogs (Hyla

cinerea Schneider) and eastern narrowmouth

toads (Gastrophryne carolinensis Holbrook),

were more abundant on clearcut sites. In Alabama,

Clawson and others (1997) found that clearcutting

of forested floodplains along blackwater streams

had little impact on the total abundance of

amphibians, but species evenness changed almost

immediately after harvesting. Significant declines

of two-lined salamanders (Eurycea cirrigera

Green) and gray treefrogs (H. chrysocelis Cope)

on clearcut sites were offset by increases of several

species, including southern cricket frogs (Acris

gryllus LeConte), southern toads (Bufo terrestris

Bonnaterre), and eastern narrowmouth toads.

Abundance and richness of several frogs and

toads (anurans) increased at temporary wetlands

in Florida (O’Neill 1995) and South Carolina

(Russell and others 2002b) after clearcutting of

surrounding upland pine plantations. Foley (1994)

reported that clearcuts in eastern Texas supported

fewer marbled salamanders (Ambystoma opacum

Gravenhorst) than did unharvested controls,

but timber harvesting had no effect on numbers

of smallmouth salamanders (A. texanum Matthes).

In a manipulative experiment, Chazal and

Niewiarowski (1998) found no significant

differences in the number of captures, body mass

and length, or clutch size of pond-breeding mole

salamanders (A. talpoideum Holbrook) after 6

months exposure to a 4-month-old clearcut and a

40-year-old pine stand (animals were captured at

an isolated wetland breeding site and placed in

100-m2

 pens installed after timber harvesting).

Limited evidence suggests that species

composition and structure of stands influence

diversity and abundance of amphibians in southern

forests. Means and others (1996) speculated

that conversion of natural longleaf pine (Pinus

palustris Mill.) stands to slash pine (P. elliottii

Engelm.) plantations in Florida eliminated

populations of flatwoods salamanders (A.

cingulatum Cope). In the Coastal Plain of South

Carolina, Bennett and others (1980) and Hanlin

and others (2000) found that the density of

amphibians was significantly higher in natural oakhickory habitats than in previously clearcut evenaged slash pine plantations. Some researchers

have speculated that because habitat features

which affect the abundance of amphibians, such

as soil acidity, leaf litter depth and type, hardwood

Chapter 27.

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Southern Forest Science:

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Biodiversity

322

shrub abundance, and CWD, may be reduced

in conifer plantations, these stand types may be

inhospitable for many species of amphibians

(Bennett and others 1980, deMaynadier and

Hunter 1995, Pough and others 1987). However,

Hanlin and others (2000) found that pine

plantations actually supported higher amphibian

diversity than did hardwood stands. Grant and

others (1994) also reported relatively high

amphibian diversity in Coastal Plain pine

plantations, with intermediate-aged (8 years old)

intensively managed loblolly pine (P. taeda L.)

stands having higher amphibian diversity than

recently clearcut (1 to 3 years old) and older

stands (26 years old). Grant and others (1994)

hypothesized that the greater structural and

vegetational complexity of intermediate-aged

stands, particularly near ground level, could

explain differences in species diversity. They

suggested that maintenance of stand structural

diversity is critical for sustaining herpetofaunal

communities in managed forests of the Southeast,

but this hypothesis remains to be tested.

We believe that taxonomic differences among

amphibians and habitat differences among

physiographic regions largely explain the

divergence between results of studies conducted

in the Southern Appalachians and those conducted

elsewhere in the Southeast. Populations of

plethodontid salamanders often decline after

timber harvesting, but anurans often respond

favorably to harvesting in Coastal Plain forests.

Plethodontid salamanders are lungless and

entirely terrestrial (Duellman and Trueb 1986) and

these traits may make them sensitive to changes in

microclimate and microhabitats after harvesting

(deMaynadier and Hunter 1995). Results of

studies from other regions of North America

support the supposition that plethodontids may

experience greater population declines after

timber harvesting than other groups

(deMaynadier and Hunter 1995).

Anurans have higher operating and tolerance

temperatures than do salamanders, and they have

the ability to store and reabsorb large quantities

of water in the bladder, e.g., 20 to 30 percent of

body mass (Duellman and Trueb 1986). These

characteristics may explain their tolerance to

warmer conditions found in harvested stands

(deMaynadier and Hunter 1995). Unlike

plethodontid salamanders inhabiting Appalachian

forests shaped by relatively small-scale and lowintensity natural disturbances (Brose and others

2001, Sharitz and others 1992), amphibians in the

southeastern Coastal Plain presumably are

adapted to the high-intensity natural disturbances,

e.g., stand-replacing fires, hurricanes, that

characterize this region. In much of the Coastal

Plain, elevated water tables, increased soil

saturation, and ruts created by tree removal,

skidding, and bedding often create standing

water in clearcuts (Cromer and others 2002,

O’Neill 1995, Perison and others 1997). These

fish-free pools, which are often numerous after

heavy rains, apparently attract more anurans to

clearcuts than are attracted to unharvested stands

(Clawson and others 1997, Cromer and others

2002, O’Neill 1995, Perison and others 1997,

Russell and others 2002b).

Reptiles—Terrestrial reptiles generally are

thought to benefit from the early successional

habitats created by forest management (Campbell

and Christman 1982, Welsh and Lind 1991), but

in reality they do not respond to harvesting as

a cohesive assemblage. Studies in Florida sand

pine [P. clausa (Chapm. ex Engelm.) Vasey ex

Sarg.] -scrub habitats have shown that many

reptile species respond favorably to even-aged

forest management (Campbell and Christman

1982, Greenberg and others 1994), leading these

authors to suggest that properly managed

clearcutting is sufficiently similar to the effects

of historic high-intensity wildfires so that its

use can be recommended for maintaining early

successional habitats for reptiles. The integrity

of these open-scrub reptile communities is

diminished by forest maturation, and clearcutting

appears to create important microhabitat features

such as patches of bare sand (Greenberg and

others 1994).

Although numbers of several lizard species

increased following clearcutting in eastern

Texas, no changes were detected for several

other reptiles (Foley 1994). Clearcutting adjacent

to bottomland hardwood stands in the upper

Coastal Plain of South Carolina generally

increased richness and abundance of reptiles

relative to richness and abundance in forested

stands (Perison and others 1997). However, at least

two reptile species, ringneck snakes (Diadophis

punctatus Linnaeus) and eastern musk turtles

(Sternotherus odoratus Latreille), were more

abundant on unharvested plots (Perison and others

1997). Seldom encountered in habitats lacking

cover, ringneck snakes are among those

southeastern reptiles associated with deep litter

or other surface objects in mesic hardwood or

hardwood-pine forests (Gibbons and Semlitsch

1991). Russell and others (2002b) also found that

clearcutting adjacent to Coastal Plain isolated
323

wetlands temporarily reduced numbers of several

turtle and snake species, including black racers

(Coluber constrictor Linnaeus), but no effects

were evident by 2 years after harvesting. Although

black racers are common in early successional

habitats, clearcutting temporarily eliminated or

disturbed understory vegetation and woody cover

that served as refugia and nest sites.

Although effects of forest management on

southeastern reptiles have not received the same

attention as those on amphibians, available data

suggest that reptile responses also are speciesand region-specific. The response of an individual

reptile species to harvesting is influenced by a

variety of factors including the degree of habitat

specificity, the spatial scale at which the organism

selects its habitat, the morphology and physiology

of the organism, and numerous other biotic and

abiotic factors. Thus clearcutting may be sufficient

to create the open habitats favored by many

southeastern reptiles, but insufficient to create

habitat suitable for others unless forested patches

or CWD are retained.

Roads and Skidder Ruts

Many forestry operations incidentally create

aquatic habitats that are used by herpetofauna

for reproduction, foraging, and cover. Examples

of such habitats include pools along logging roads

and machinery ruts within stands. However, these

activities can alter hydrological processes and

damage natural aquatic habitats (deMaynadier

and Hunter 1995). Because the reproductive

strategies, e.g., timing, of many amphibian species

are adapted to fluctuating hydrology, an increasing

concern is that these artificial aquatic habitats may

act as population sinks for amphibians if seasonal

drying occurs too rapidly (reproductive failure)

or not at all (permanent habitat for predators).

To date, only two studies have evaluated effects

of roads and harvest skidder ruts on southeastern

herpetofauna. Adam and Lacki (1993) documented

widespread use of forest road-rut ponds for

breeding by eight species of salamanders and

anurans in Kentucky. Road-rut use was positively

associated with surface area, depth, and water

clarity, but negatively associated with detrital

coverage. More recently, Cromer and others (2002)

compared herpetofaunal communities in recently

harvested gaps, skidder trails, and undisturbed

depressional wetlands to assess effects of group

selection harvesting and skidder traffic on

herpetofauna in a South Carolina bottomland

hardwood forest. Total species richness and

abundance were similar among gaps, skidder

trails, and undisturbed bottomland depressions.

However, salamander abundance, especially

for pond breeding Ambystoma spp., was

negatively correlated with pronounced rutting

from skidder trails. The characteristic ephemeral

hydrology of bottomland depressions was altered

in the harvested gaps and along skidder trails to

produce perennially flooded ponds. This created

permanent habitat for several aquatic and

semiaquatic species of amphibians and reptiles

that dispersed from bottomland depressions

during periods of drought. However, the skiddertrail ruts also supported fish and invertebrate

predators whose populations in the natural

depressions typically are controlled by

annual droughts.

Although selective harvesting techniques

have been recommended as an alternative to

clearcutting as a means of protecting forest

herpetofauna (deMaynadier and Hunter 1995),

these approaches may require repeated stand

entries with additional ground disturbance and

may create more roads and ruts than do evenaged regeneration methods. The artificial aquatic

habitats created by these activities may have

significant implications for habitat selection, and

effects on reproductive success and survival of

herpetofauna should be evaluated.

Site Preparation

Mechanical treatments—As deMaynadier

and Hunter (1995) noted, generalizations about

the effects of clearcutting on herpetofauna

can be misleading because a wide range of site

preparation techniques are associated with

even-aged management. For example, intensive

mechanical site preparation is used extensively

in the Coastal Plain to expose seedbeds and

remove competing vegetation prior to replanting,

but is rarely employed in Appalachian forest

management. Unfortunately, few studies have

specifically examined effects of postharvest

mechanical site preparation on southeastern

amphibians and reptiles. The available literature

suggests that these activities can, at least

temporarily, reduce habitat complexity and affect

some herpetofauna negatively. Although direct

mortality is likely for selected species (Dodd 1991,

Russell and others 2002b), mechanical treatments

typically are applied only once during stand

initiation, and intensive mechanical treatments,

such as raking, harrowing, disking, chopping,

bedding, probably do greater harm by removing

leaf litter, CWD, herbaceous vegetation, root

channels, and other important microhabitats

for herpetofauna (Enge and Marion 1986, Whiles

and Grubaugh 1993).

Chapter 27.

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Southern Forest Science:

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Biodiversity

324

Enge and Marion (1986) compared

herpetofaunal populations of three pine flatwoods

stands in Florida: a 40-year-old pine stand and two

clearcuts receiving minimum (roller-drum chop,

bed, plant) and maximum (stump removal, burn,

windrow, harrow, bed, plant) site preparation

treatments. After treatment, the maximum

site preparation stand had less leaf litter, CWD,

and herbaceous vegetation, and had a greater

percentage of exposed soil, than did the minimumtreatment or reference stands. Amphibian

richness did not vary significantly among the

three stands, but amphibian abundance was lower

in both site preparation treatment stands than in

the reference stand. Intensive site preparation

reduced abundance and richness of most reptile

species, with the largest impact on fossorial

snakes. The authors attributed lower reptile

abundance in the maximum site preparation

clearcut to elimination of CWD and other cover

objects that served as refugia and nesting sites.

However, intensive site preparation appeared

to benefit at least one species, the six-lined

racerunner (Cnemidophorus sexlineatus

Linnaeus), a lizard that prefers open sandy areas.

A limitation of Enge and Marion’s (1986) study

is that effects of site preparation were not isolated

from those of harvesting. Russell and others

(2002b) found that when compared to clearcut-only

and reference stands, mechanical site preparation

of sites adjacent to isolated wetlands in the South

Carolina Coastal Plain did not appear to negatively

influence amphibians breeding at the ponds. In

fact, bronze frogs (Rana clamitans Latreille)

migrated into wetlands from site-prepared

stands in higher numbers in the second year

after treatment. Snakes, including black racers,

were less abundant within the first 6 months

after treatment, possibly in response to physical

disturbance of nest sites and reductions in ground

cover. These effects were short lived, however, and

no effects of site preparation on reptiles were

detected in the second year after application.

In addition to removing surface cover,

mechanical site preparation may destroy burrows

and other subsurface refugia of fossorial

herpetofauna. Several studies have documented

destruction of gopher tortoise (Gopherus

polyphemus Daudin) burrows by chopping and

other mechanical treatments (Diemer and Moler

1982, Landers and Buckner 1981, Marshall and

others 1992, Tanner and Terry 1981), although

Landers and Buckner (1981) and Diemer and

Moler (1982) observed tortoises emerging from

destroyed burrows and either reopening them

or excavating new sites. Loss of gopher tortoise

burrows to site preparation can indirectly affect

other species; at least 332 wildlife species are

known to use burrows of gopher tortoises,

including several rare amphibians and reptiles

(Lips 1991). Soil disturbance from site preparation

also has been linked to destruction of Red Hills

salamander (Phaeognathus hubrichti Highton)

burrows in Alabama (Dodd 1991).

Prescribed fire—Prescribed burning is used

to achieve a variety of silvicultural objectives

including controlling heavy fuel accumulation,

exposing mineral soil, releasing available nutrients

for seedbed preparation, and controlling insects,

diseases, and competing vegetation. A detailed

literature review of fire effects (and fire exclusion)

on southeastern herpetofauna was conducted

by Russell and others (1999) and only a brief

summary is provided here. Generally, replacing

fire-adapted vegetation with fire-intolerant

associations, e.g., hardwoods, in the southeastern

Coastal Plain leads to concomitant declines in

overall herpetofaunal abundance and diversity.

However, it may be appropriate to use prescribed

fire in combination with other forestry practices

to benefit Coastal Plain herpetofauna by restoring

an historic mosaic of successional stages, habitat

structures, and plant species compositions in

both terrestrial and aquatic habitats (citations

in Russell and others 1999). For example, in

southern Florida, richness and abundance of

herpetofauna consistently were higher in slash

pine plots subjected to three different burn

intervals (1, 2, 7 years) than in a reference plot

protected from burning for 20 years (Mushinsky

1985). Based on these results, Mushinsky (1985)

recommended a 5- to 7-year prescribed burn cycle

to maintain diverse herpetofaunal communities in

southern Florida sandhills.

Available evidence suggests that direct

mortality of herpetofauna following fire typically

is low and presumably outweighed by maintaining

desired habitat features (Means and Campbell

1981, Russell and others 1999). Although fireinduced disturbance may temporarily decrease

herpetofaunal diversity within a particular stand,

a heterogeneous matrix of stand ages and

structural conditions should increase diversity

on a broader scale (Greenberg 2002, Greenberg

and others 1994, Jones and others 2000, Litt and

others 2001). Unfortunately, concerns over crop

tree productivity, smoke management, air quality

standards, and liability have led to fire exclusion
325

policies that may have significant long-term

consequences for herpetofauna in Coastal Plain

forests and elsewhere (Russell and others 1999).

Even within fire-adapted southern forests some

species of herpetofauna may depend on climax

vegetation (Greenberg 2002). Means and Campbell

(1981) examined herpetofaunal communities in

longleaf pine and shortleaf pine (P. echinata Mill.)

stands in peninsular Florida that had been

burned annually for 60 to 70 years and in an

unburned forest that had succeeded to a closedcanopy hardwood association. Three species of

amphibians [tiger salamander (A. tigrinum

nebulosum Holowell), oak toad (Bufo quercicus

Holbrook), ornate chorus frog (Pseudacris ornata

Holbrook)] and six-lined racerunners were

captured predominantly from the burned

pine stands, whereas three amphibian species

[marbled salamander, mole salamander, and slimy

salamander (Plethodon glutinosus Green)] were

captured almost exclusively in the hardwood

forest. The authors suggested that these

differences in distribution reflected adaptations

(or lack thereof) of individual species to fire

(Means and Campbell 1981).

Almost all studies of fire effects on southeastern

herpetofauna have been conducted in Coastal Plain

forests (Russell and others 1999), and caution must

be exercised when extending conclusions to other

areas. Until recently, fire was not considered an

important or desirable disturbance regime in

mixed-hardwood forests of the Appalachian

and Piedmont regions (Brose and others 2001).

However, it has been hypothesized that periodic,

low-intensity surface fires were crucial for

perpetuating these oak-dominated forests for

millennia and are necessary to restore such forests

(Brose and others 2001). To date, only two studies

have investigated prescribed fire-herpetofauna

relationships in these areas. Ford and others

(1999) found that prescribed fires in the Southern

Appalachians had little effect on herpetofauna and

concluded that concerns about negative effects of

prescribed burning on plethodontid salamanders

probably were unwarranted. An ongoing study

evaluating the use of prescribed fire to restore oak

forests in the South Carolina Piedmont also has

not found dramatic negative impacts (Floyd and

others 2002).

Other topics needing attention include (1)

the combined effects of fire frequency, intensity,

and seasonality on herpetofauna; (2) the use of

herbicides as a substitute for prescribed fire

(Litt and others 2001); and (3) the use of

prescribed fire to restore and maintain aquatic

habitats of herpetofauna threatened by hardwood

succession (Russell and others 1999).

Herbicides—In forestry, herbicides are used for

site preparation, for release of crop trees from

herbaceous and woody plants, for managing

species composition and structure, and for timber

stand improvement (Miller and Mitchell 1994).

Herbicides may be broadcast across a stand,

sprayed in bands centered on rows of trees,

or applied to individual woody stems. Individual

stems usually are treated by directly spraying

foliage, applying the herbicide to the tree bole (or

to wounds on the bole), or applying a soil-active

herbicide to the ground near the tree.

Documented adverse effects of herbicides

on some herpetofaunal life stages include

mortality, reduced body mass, failure to

metamorphose, decreased stimulatory response

of neuroepithelial synapses, chromosomal

fragmentation, deformities, and DNA profile

abnormalities (citations in Pauli and others 2000).

It has been suggested that herbicides are among

the causative factors explaining global declines

of amphibian populations (citations in Fellers

and others 2001). However, these effects generally

have occurred at exposure levels above those

likely to occur in normal forestry operations.

Furthermore, several literature reviews have

concluded that commonly used forestry herbicides

are not acutely toxic to wildlife because they have

relatively low mutagenicity, have no or very weak

oncogenetic effects, are rapidly eliminated by

animals, do not bioaccumulate, and have a short

environmental half life (McComb and Hurst

1987, Miller and Witt 1991). Forestry herbicides

also are used infrequently, i.e., many even-aged

stands receive only one or two applications during

a typical rotation, and most herpetofauna likely

are shielded from direct exposure, i.e., by being

underground or under vegetation, leaf litter,

or CWD.

Because herbicides are designed to kill

vegetation, they can affect herpetofauna indirectly

by altering habitat. Herbicide effects on habitat

vary with soils, structure of the pretreatment

plant community, herbicide product used,

application rates, timing of application, weather

conditions, and other factors. However, herbicide

application to individual trees in midrotation or

maturing stands often promotes canopy gaps and

understory biomass production (McComb and

Hurst 1987). When broadcast in regenerating

stands, herbicides often temporarily reduce

biomass production for one to several growing

Chapter 27.

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Southern Forest Science:

Past, Present, and Future

Biodiversity

326

seasons, and shift the dominant understory

vegetation from woody to herbaceous plants

(Miller and Witt 1991).

Few studies have documented herpetofaunal

response to herbicide-induced habitat changes.

Results of those studies, and studies for other

wildlife taxa, suggest that herpetofaunal responses

are species-specific (Howell and others 1996,

Lautenschlager 1993, McComb and Hurst 1987),

with individual species increasing, decreasing,

or not changing in abundance at the stand level

(Cole and others 1997, Harpole and Haas 1999,

Lautenschlager and others 1998, Yahner and

others 2001). Landscape-level responses of

herpetofaunal species to herbicide applications

probably depend on the productivity and natural

disturbance regime of the landscape (Huston

1999), the extent of the area simultaneously

treated with herbicides, the vegetation structure

of treated stands and the broader landscape,

and other factors previously described.

Whether used alone or with other management

practices, e.g., prescribed fire, herbicides may be

applied to meet selected management objectives

for herpetofauna and other wildlife species. For

example, Brooks and others (1993) concluded

that any of the three herbicide treatments they

evaluated (hexazinone, imazapyr, and picloram

+ triclopyr) were compatible with the goal of

maintaining quality habitat for gopher tortoises.

Managers can use herbicides to control nonnative

plant species; create snags; manipulate the species

composition and structure of understory, midstory,

and overstory vegetation; manage the spatial and

temporal availability of habitat; and for other

purposes (Wigley and others 2002).

Riparian Buffers, Isolated Wetlands,

and Terrestrial Corridors

Riparian buffers—Retention of streamside

management zones (SMZs or buffers) as a means

of conserving biodiversity continues to be a widely

debated strategy (Harrison and Voller 1998). Some

studies conducted in the Pacific Northwest suggest

that unharvested riparian buffers are important

for protecting stream- and riparian-associated

amphibians from effects of timber harvesting

(Corn and Bury 1989, Welsh and Lind 1991).

Riparian buffers presumably lessen accumulation

of fine sediments in stream substrates, limit

increases in water temperatures, and mitigate

other negative impacts of soil transport and solar

radiation on stream habitats (deMaynadier and

Hunter 1995). Little information is available,

however, about effects of riparian logging on

southeastern stream amphibian communities

(Pauley and others 2000). In the Southern

Appalachians, salamanders were 50 percent

more abundant in SMZs than in adjacent

harvested areas (Petranka and others 1993).

In the western Piedmont of North Carolina,

Willson and Dorcas (2003) found that the relative

abundance of stream-dwelling salamanders was

inversely proportional to the percentage of

disturbed habitat at the watershed scale, but

they found no relationship between the relative

abundance of salamanders and the percentage

of disturbed habitat within riparian buffer zones.

Stiven and Bruce (1988) speculated that streamdwelling blackbelly salamanders (Desmognathus

quadramaculatus Holbrook) were less abundant

in recently logged Appalachian watersheds, and

that harvesting also might alter genetic diversity

of the affected populations.

In eastern Texas, Foley (1994) found that SMZs

retained in clearcuts actually supported higher

diversity of herpetofauna than did unharvested

reference stands. He and others (deMaynadier

and Hunter 1995) have suggested that in addition

to protecting aquatic amphibians, riparian buffer

strips could also provide an intact strip of forested

habitat capable of harboring populations for future

recolonization of adjacent disturbed areas. Bowers

and others (2000) examined herpetofaunal

response to different planting regimes in the Pen

Branch corridor, which is associated with a thirdorder stream on the Savannah River Site in South

Carolina. This stream received thermal effluents

from a nuclear reactor for over 30 years, and

this resulted in the destruction of most riparian

vegetation in a portion of the stream’s floodplain.

Subsequent erosion created a braided stream

system with a greatly expanded delta, and

restoration of the area began with planting of

bottomland hardwood species in 1993. Species

diversity of herpetofauna in the unaffected

riparian zone was significantly higher than

on vegetated islands located between stream

braids within the impacted floodplain corridor,

and there were also significantly more species

and individuals within the riparian zone than

in the corridor. According to Bowers and others

(2000), these results highlight the importance of

the unaffected riparian zone in the faunal recovery

of the floodplain.

Recommended streamside buffer widths

for herpetofauna in other regions of North

America range from 30 to over 100 m (McComb

and others 1993, Rudolph and Dickson 1990).
327

It has been recommended that riparian buffer

widths be adjusted proportionally with stream

width, intensity of adjacent harvest, and slope

(deMaynadier and Hunter 1995). However,

we agree with Wigley and Melchiors (1993)

that we know too little about empirical

relationships between forest management

effects and riparian habitat functions to justify

our recommending specific stream buffer widths

for southeastern herpetofauna.

Isolated wetlands—Although little effort has

been devoted to research and management of

stream-associated herpetofauna in southern

forests, protection of isolated wetland habitats

in the southeastern Coastal Plain has received

increasing attention. Carolina bays, cypress ponds,

and other isolated wetlands, i.e., those with no

permanent connections to aboveground stream

or river systems, are critical habitats for

herpetofauna adapted to seasonal hydroperiods

and the absence of predatory fish. Of 29 anuran

species native to the southeastern Coastal Plain,

20 breed primarily or exclusively in isolated

wetlands (Moler and Franz 1987). Several species

of salamanders, e.g., Ambystoma spp., also

migrate to isolated wetlands for mating and egg

deposition but return to upland habitats for the

remainder of the year (Gibbons and Semlitsch

1991). In contrast, many Coastal Plain turtles and

snakes seek food and cover in isolated wetlands or

their peripheries but migrate to adjacent uplands

for egg laying and hibernation (Gibbons and

Semlitsch 1991, Russell and Hanlin 1999).

Most species of herpetofauna associated with

isolated wetlands in the Coastal Plain also use

adjacent upland forests, and several authors

have recommended, on the basis of anecdotal or

retrospective data, that closed-canopy forested

buffers or complete exclusion of upland forest

management activity is necessary to protect

these aquatic habitats and maintain landscape

connectivity among wetlands (see citations

in Russell and others 2002b). For example,

Pechmann and others (1991) speculated that the

initial absence and then presence of marbled

salamanders at an isolated wetland in South

Carolina resulted from regeneration of

surrounding upland forests that previously were

clearcut and burned. Raymond and Hardy (1991)

reported that a clearcut 156 m away from a

breeding pond in Louisiana appeared to influence

the migratory movements and survivorship of the

pond’s breeding population of mole salamanders.

On the strength of data on movements of several

salamander species from isolated wetlands

to adjacent upland forests, Semlitsch (1998)

hypothesized that a buffer zone encompassing

95 percent of the populations using those upland

stands would extend approximately 164 m from

the wetland’s edge. Burke and Gibbons (1995)

estimated that an upland buffer 275 m in width

would be necessary to protect 100 percent of the

nest and hibernation sites of two aquatic turtle

species associated with isolated wetlands.

In contrast, Wigley (1999) reported that

retention of an adjacent forested buffer was

correlated with the presence of only 1 of 40

amphibian species and 37 reptile species sampled

from 444 temporary isolated wetlands across

the southeastern Coastal Plain—the pine woods

treefrog (Hyla femoralis Bosc). Russell and others

(2002a) also found that 5 small isolated wetlands

(0.38 to 1.06 ha) surrounded by 18- to 25-year-old

loblolly pine plantations in the Coastal Plain of

South Carolina were used by at least 56 species

of herpetofauna, suggesting that these aquatic

habitats within managed forests are capable of

supporting high herpetofaunal diversity. Although

retaining forested buffers around isolated

wetlands is widely recommended, to date only

Russell and others (2002b) have experimentally

evaluated management of upland forest buffers

on southeastern wetland herpetofauna. They

examined immigration and emigration of

herpetofauna from isolated wetlands in the

South Carolina Coastal Plain before and after

clearcutting and mechanical site preparation

of adjacent upland forests. Although harvest

treatments significantly altered overstory and

ground cover characteristics of upland stands, no

treatment-related changes in the overall richness,

abundance, or community similarity of amphibian

and reptile communities at the wetlands were

observed. Only short-term negative effects were

observed for turtles and snakes. These taxa were

less abundant only within the first 6 months after

clearcutting and site preparation, possibly in

response to physical disturbance of nest sites and

temporary changes in ground cover. No amphibian

species showed negative responses to treatments,

and the number of bronze frogs at the wetlands

increased after treatments. The authors noted that

although it is premature to suggest that upland

forested buffers surrounding southern isolated

wetlands are unnecessary, assumptions about

effects of forestry operations on isolated wetland

herpetofauna, and management based on such

assumptions (Semlitsch 1998, 2000), must

be tested in the field.

Chapter 27.

 Amphibians and Reptiles
Southern Forest Science:

Past, Present, and Future

Biodiversity

328

Corridors—Preston (1962) was among the first

to suggest possible conservation benefits of upland

habitat corridors. Preston speculated that habitat

preserves would become isolated, and that the only

remedy was to maintain continuous corridors that

would link reserves. Most studies of corridors have

examined movement patterns of mammals and

birds (Bennett 1990, Wegner and Merriam 1979).

The function and conservation value of upland

corridors is still debated widely (citations in

Harrison and Voller 1998, Ford and others 2000).

Although use of corridors to manage amphibians

has been advocated (Semlitsch 2000), we are aware

of only one study of the effects of retaining upland

forest corridors for herpetofauna in the Southeast

or elsewhere (Baughman 2000). In this study from

South Carolina, three sites were randomly

selected for retention of a 100-m wide unharvested

forest corridor traversing the length of a clearcut,

and one site was assigned as an unharvested

reference. Baughman (2000) found that mean

numbers of herpetofauna captured entering or

within corridors did not differ from mean numbers

of herpetofauna captured in harvested areas, and

that herpetofauna assemblages and movement

rates for corridors were similar to those for the

stands from which the corridors were created.

Although corridors provided a continuous web of

closed-canopy forest across the study landscape,

Baughman (2000) emphasized that long-term

monitoring is needed before potential benefits of

terrestrial corridors for herpetofauna in managed

forests of the Southeast can be determined.

Demographic Responses to Management

Although short-term measures of richness

and abundance may not be affected by forest

management, such measures often are not good

predictors of habitat quality (Van Horne 1983),

and changes in habitats could have longer term

consequences for reproductive success, survival,

and dispersal of herpetofauna. Few studies have

collected demographic data to determine whether

responses to forestry practices are age- or sexspecific. Enge and Marion (1986) reported that

although there was no difference between overall

frog biomass in forested plots, in clearcut plots,

fewer juvenile frogs were captured on harvested

sites. Raymond and Hardy (1991) suggested that

survival of female mole salamanders was lower

than survival of males following clearcutting,

whereas Ash (1988) reported that sex and age

classes of plethodontid salamanders declined at

the same rate after clearcutting. Also, without

appropriate marking and recapturing techniques,

it is difficult to collect data indicative of true

population sizes or to monitor movements of

herpetofauna in response to forestry practices

(Ash and Bruce 1994). For example, estimates

by Petranka and others (1993) of plethodontid

salamander mortality resulting from clearcutting

are based on the assumption that these

salamanders exhibit poor dispersal capabilities

 and strong site fidelity. Bartman (1998) did not

observe dispersal of plethodontid salamanders

immediately after logging in North Carolina

Appalachian forests, but fates (death vs. dispersal)

of herpetofauna after clearcutting and other

forestry activities remain poorly known (Ash and

Bruce 1994, deMaynadier and Hunter 1995).

Landscape-Level Responses

Although characterizing stand-level

responses of herpetofauna to forest management

is important, perhaps the most pressing questions

are at larger scales (Guerry and Hunter 2002).

Some recent studies have characterized

herpetofaunal communities at the landscape

level. Leiden and others (1999) conducted

a broad survey of herpetofauna across an

industry-managed landscape in South Carolina.

The landscape contained stands in various stand

structural classes, including pine plantations.

Leiden and others (1999) confirmed the presence

of 73 of 102 species of amphibians and reptiles

potentially occurring in the landscape (based

on range maps). This represented the highest

recorded richness of amphibians and reptiles

in South Carolina, with the exception of

the Savannah River Site, where continuous

sampling has occurred since the 1950s (Gibbons

and others 1997).

Responses of herpetofauna to forest

fragmentation have not been studied as often

as have responses of other vertebrates, such as

birds. However, a limited number of field studies

suggest that isolation of forest patches may

influence occupancy of terrestrial habitat in such

patches by adult amphibians (citations in Guerry

and Hunter 2002). Fox and others (2004) and

Shipman and others (2004) censused amphibians

and reptiles in four forested watersheds (1500 to

4000 ha each) in the Ouachita Mountains that were

managed at different intensities, and thus levels of

“fragmentation,” ranging from largely unmanaged

to intensive even-aged management. Watershedto-watershed differences in amphibian richness

were negligible, and community similarities were

high (Fox and others 2004). The watersheds

had similar reptile communities, but the least

intensively managed watershed had lower
329

per-plot abundance, species richness, and

diversity of reptiles than the others (Shipman and

others 2004). This was attributed to dominance by

two reptile species in the least intensively

managed watershed.

Because many aquatic and semiaquatic

herpetofauna use adjacent terrestrial habitats for

dispersal, foraging, and refuge, both the proximity

of wetlands to terrestrial habitat and the area of

terrestrial habitat may influence habitat

occupancy. If populations of wetland-associated

herpetofauna exhibit metapopulation structure,

reduced immigration and emigration rates

resulting from disconnection of habitat patches

may negatively influence viability (Guerry and

Hunter 2002, Joyal and others 2001). In Maine,

Guerry and Hunter (2002) found species-specific

responses of pond-breeding amphibians to area

and proximity of adjacent terrestrial forests.

Although the presence and abundance of some

species were positively related to forest area and

pond-forest adjacency, other species exhibited

negative or no associations with one or both of

these factors. However, we are unaware of any

studies that explicitly evaluate effects of forest

fragmentation on either terrestrial or aquatic

amphibians in the Southeast.

MANAGEMENT IMPLICATIONS OF

NATURAL DISTURBANCE REGIMES

C

urrently available evidence suggests that

southeastern herpetofauna respond in a

complex manner to changes in climatic,

vegetational, and structural features of stands and

landscapes after the implementation or exclusion

of specific management practices (such as fire

suppression). DeMaynadier and Hunter (1995)

argue that herpetofauna generally benefit when

forest management prescriptions retain sufficient

microhabitat and microclimate elements within

stands, and ensure a diversity of habitat types

across larger areas. They also suggest that

identifying and then minimizing differences

between forest management practices and

historic patterns of natural disturbance, e.g.,

retention or creation of microhabitats, will

improve conservation of herpetofauna in our

managed forests.

We suggest this historic context has often been

overlooked by those considering the effects of

forest management on southeastern herpetofauna.

Current forest management regimes are only the

latest in a continuum of forest clearing, intensive

agriculture, prescribed burning, forest regrowth,

and timber harvesting across the Southeast

(Sharitz and others 1992). Prior to human

influence, natural disturbances, e.g., fire,

hurricanes, windthrow, ice storms, occurring at

different frequencies, intensities, and extents

depending on physiographic region, controlled the

character of southern forests and maintained the

stand and landscape diversity essential to support

the flora and fauna of the region (Brose and others

2001, Myers and Van Lear 1998, Sharitz and others

1992). Unmanaged southern forests were not a

homogeneous blanket of “intact” or “continuous”

closed-canopy forest, but rather a heterogeneous

mixture of stands of different ages and structural

types. Many vertebrates in the South, including

herpetofauna, have tolerated and adapted to

disturbance events throughout much of their

evolutionary histories (Campbell and Christman

1982, Greenberg and others 1994, Russell and

others 1999). Thus the complexity and regional

nature of herpetofaunal responses to forest

management should not be surprising. As Means

and Campbell (1981) point out, it is illogical

to conclude that herpetofauna associated with

southeastern forests are not themselves adapted

to local patterns of disturbance. We have found,

however, that few studies or management

recommendations (Semlitsch 2000) involving

responses of herpetofauna to forest management

have fully considered the spatial and temporal

complexity of forest habitats, including

disturbance scales and intensities that species

and communities are adapted to. It is absolutely

necessary that we understand this context if

we are to predict how southeastern herpetofauna

will respond to forest management, and if

we are to develop efficacious and cost-effective

conservation strategies. For example, are

recommendations for closed-canopy buffers

around isolated wetlands consistent with the

existence of the exposed and sparsely vegetated

nest sites selected by many turtle species (Kolbe

and Janzen 2002)? Management and recovery

strategies for herpetofauna that do not recognize

the dynamic rather than static nature of southern

forests, or those that provide one-size-fits-all

solutions, are likely to fail.

CONSIDERATIONS FOR FUTURE RESEARCH

I

ncreasingly, researchers and resource

managers are recognizing the importance

of herpetofauna within the context of forest

management (deMaynadier and Hunter 1995,

Dunson and others 1992). However, much remains

to be learned concerning effects of forestry

practices on southeastern herpetofauna. Currently

available data suggest that herpetofauna are

Chapter 27.

 Amphibians and Reptiles
Southern Forest Science:

Past, Present, and Future

Biodiversity

330

influenced both positively and negatively (and

occasionally not at all) by management of southern

forests, and responses are specific to individual

regions, taxa, and management prescriptions.

The population and community effects of forest

management activities on southeastern

herpetofauna are still difficult to assess, though,

because of methodological limitations and because

a variety of study designs have been employed

(deMaynadier and Hunter 1995).

The absence of pretreatment data, replication,

and true reference conditions in many studies

has limited conclusions about impacts of forestry

on herpetofauna (Ash and Pollock 1999,

deMaynadier and Hunter 1995, Petranka 1999,

Russell and others 1999). Most studies have

inferred management effects on the strength

of retrospective comparisons of herpetofaunal

attributes of harvested and unharvested sites.

This approach assumes that the herpetofaunal

populations of harvested sites once exhibited

characteristics, e.g., abundance, identical with

those of populations present on forested reference

sites. Baseline data on habitat parameters are

necessary if we are to assess the comparability

of sites and the extent of postharvest changes.

Only six studies investigating effects of forest

management on southeastern herpetofauna have

employed manipulative designs with pretreatment

and posttreatment data, treatment replication,

or true spatial and temporal references (Ash

1997, Chazal and Niewiarowski 1998, Clawson

and others 1997, Harpole and Haas 1999, Knapp

and others 2003, Russell and others 2002b). Also

needed are longer-term studies that separate

immediate population responses to harvesting

from long-term effects on fitness.

The challenge for future studies of

herpetofauna-forestry relationships has moved

beyond simply documenting the range of harvest

effects to successfully blending economic and

cultural objectives with those for conservation

of herpetofauna by identifying silvicultural

prescriptions that retain significant natural

components of regenerating stands (deMaynadier

and Hunter 1995, Grant and others 1994).

Although documentation of the magnitude of

silvicultural effects on herpetofauna is increasing,

the causal factors that shape the distribution and

abundance of herpetofauna in southern forests

remain poorly understood. Pioneering work by

MacArthur and MacArthur (1961) demonstrated

the importance of vegetational structural diversity

to avian communities. However, quantitative

studies that explicitly examine relationships

among structural attributes of forests and

herpetofaunal populations in the Southeastern

United States are lacking (Grant and others

1994). Studies from the Pacific Northwest and

Northeast suggest that structural characteristics

and components of forests, particularly those at

ground level, e.g., CWD, leaf litter depth and

moisture, understory vegetation, are important

correlates of herpetofaunal abundance and

diversity (Aubry 2000, deMaynadier and Hunter

1995, McComb and others 1993, Pough and

others 1987).

Although microhabitat variables such as

CWD and leaf-litter depth often increase with

stand age, there is a great deal of stand-specific

variability related to natural and silvicultural

disturbance history, climate, soils, elevation,

proximity to aquatic habitats, and other influences

(Oliver and Larson 1996). For example, intensive

site preparation treatments, e.g., bedding or

windrowing, may retard development of stand

structure by eliminating cull trees, snags, CWD,

and understory species, whereas less-intensive

applications that only slightly disturb the soil, e.g.,

roller chopping, or occasional prescribed burning,

may increase diversity and biomass of understory

species (Hunter 1990). Thus stand age may not

be an accurate delimiter of transitions in stand

structural development (deMaynadier and

Hunter 1995, Hunter 1990, Oliver and Larson

1996), particularly across regions and ownerships

with different methods of harvesting or

site preparation.

Approximately 90 percent of southeastern

forests are privately owned (U.S. Department

of Agriculture, Forest Service 1988), and most

of these forests will continue to be managed

for economic benefit. We think that information

obtained by means of retrospective and

manipulative studies that elucidate relationships

among stand structural diversity, forest

management practices, and herpetofaunal

communities can be used to integrate management

of these forests with the protection and promotion

of herpetofaunal biodiversity. This will be

accomplished by approximating the range

of natural disturbance events that historically

shaped the region’s forests. One research

approach is to inventory the distribution and

abundance of herpetofauna in forest stands

with variable structural characteristics and

management histories within larger landscapes

(Gibbons and others 1997, Wigley and

others 2000). Then quantitative models can be

developed that relate distribution, abundance,
331

and demographic characteristics of species to

specific habitat elements found in managed

forests, and eventually integrated into sustainable

landscape models that would predict herpetofauna

responses to different management scenarios

(Wigley and others 2001).

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335

Chapter 28.

Monitoring Tree Species Diversity

over Large Spatial and Temporal Scales

James F. Rosson, Jr. and

Clifford C. Amundsen1

Abstract—The prospect of decline in biological

diversity has become a central concern in the

life sciences, both around the world and across

the United States. Anthropogenic disturbance has

been identified as a major factor affecting species

diversity trends. An increase in the harvesting

of naturally diverse timber stands in the South

has become an important issue. The ultimate

impact of this high, and increasing, level of

disturbance on tree species diversity in forests

of the Southern United States is uncertain. We

offer a brief review of literature related to major

points in the development of species diversity

concepts over the last 100 years. This is followed

by a case study that makes use of periodic U.S.

Department of Agriculture Forest Service, Forest

Inventory and Analysis (FIA) data from Mississippi.

Our interest, for southern forests, is whether tree

species richness has declined, increased, or

remained essentially stable over the last 35 years.

We find that tree species richness has declined by

11 percent across Mississippi since 1977. However,

in FIA plots that had no evidence of harvesting,

tree species richness increased by 44 percent since

1967. It is difficult to determine what constitutes a

healthy level of tree species richness for particular

sample designs and large-scale State surveys.

Additional analytical complexity comes from the

lack of documentation and knowledge concerning

various levels of richness dynamics for large spatial

and temporal scale studies.

INTRODUCTION

Q

uestions about, concerns about, and interests

in biological diversity have reached high

levels of priority with academics, research

scientists, resource conservationists, political

decisionmakers, civic leaders, and interested

members of the general public (particularly

those in the environmental community). Though

biological diversity has been of interest to

ecologists for many decades, broader popular

interest in the subject developed in the 1980s in

response to the highly publicized exploitation and

deforestation of tropical rain forests (Wilson and

Peter 1988). This disturbance takes the form of

intensive and extensive timber harvesting and land

clearing. Heightened public interest in biological

diversity and the decline of tropical forests was

reflected in the 1986 National Forum on

Biodiversity (Wilson and Peter 1988).

Anthropogenic disturbance on forest land in the

United States, and its long-term effects on forest

biology, has also received considerable attention

(Hunter 1999, Kimmins 1997, Kohm and Franklin

1997, Maser 1994, Noss and Cooperrider 1994,

Perry 1994, Szaro and Johnston 1996). The types

of disturbance range from permanent clearing,

as in the conversion of forest land to urban

or agricultural use (in this context permanent

may mean only a few years to many decades),

to intense and repeated harvesting activity.

Increases in timber harvesting in the Southern

United States has raised concerns about the longterm sustainable (both productive and ecologically

sound) use of the forest resource. The concept of

sustainable use is different from its predecessor,

sustainable yield, in that equal weight is given to

biological, social, economic, and political

components, whereas sustainable yield matches

levels and rates of harvesting with maximum

rates of species production. See Campbell (2002)

for more background on sustainability.

1

 Research Forester, U.S. Department of Agriculture Forest

Service, Southern Research Station, Knoxville, TN 37919; and

Professor, University of Tennessee, Ecology and Evolutionary

Biology, Knoxville, TN 37996, respectively.
Southern Forest Science:

Past, Present, and Future

Biodiversity

336

Increases in timber harvesting on private

land in the Southern United States have resulted

primarily from a combination of consumer

demands and reductions in the amount of publiclands timber being offered for contract sales.

The latter follows from reductions in the allowable

sale quantity [the amount of timber offered for

sale on national forests by the USDA Forest

Service (Forest Service)]. These reductions in

timber being offered for sale can be attributed to

issues related to habitat protection (as for the

spotted owl in the Northwestern United States),

reductions in budget and staff, and increases in the

amount of time and money expended in litigation

(Kohm and Franklin 1997). The result is that less

timber is being removed from national forest

lands, particularly in the West. The Southern

United States is making up much of the shortfall in

western timber production by increasing harvests

on forest industry and nonindustrial private forest

lands. Currently, the Southern United States

accounts for 65 percent of all tree volume

harvested in the United States (Smith and others

2001). This is a substantial increase since 1992,

when the South contributed 55 percent of all

harvested volume (Powell and others 1993).

The issues of sustainable forests and

sustainable forestry involve both short- and

long-term impacts. An example of short-term

impacts would be timber supply shortages while

long-term impacts reflect the integrity of forest

biology. The latter include, but are not limited

to, soil deterioration, habitat destruction and

alteration, changes in stand structure, successional

interruptions, stand fragmentation, declines in

old-growth area, age-class imbalance, changes

in species composition, and impacts on overall

biological diversity. Noss (1996) has identified

seven types of biotic impoverishment in forests.

These can be thought of as trajectories of change

as the dynamics of natural forest processes are

shifted by more intense management. The changes

are: older stands to younger stands, structurally

and compositionally complex stands to simple

stands, large continuous forests to smaller

fragmented patches, forest stands that are in close

proximity to each other (or are continuous with)

to increasingly isolated patches, frequent cool fires

to fewer hot fires, few roads to many roads, and

stable species populations to more endangered

species. Any of these factors may occur

independently or in combination.

As forest harvesting activity in the

Southern United States continues to increase,

decisionmakers will need reliable information

that tracks the impact of harvesting on forest

resource integrity. In order to evaluate the

long-term impact of intense timber harvesting,

decisionmakers need to know how tree species

diversity and overall forest composition may

be affected. The effect an increasing area of

artificially regenerated forest stands will have on

species diversity over a large area, such as a State,

is a related concern. For conservation strategies

to be effective, reliable information about species

diversity trends must be available. Traditional

ecological studies have in most cases dealt with

smaller areas. However, extrapolations from smallscale, independent, and scattered studies do not

provide adequate and reliable information about

conditions and processes over large spatial scales.

The study of biological diversity is not new.

This chapter presents a brief chronological review

of the diversity concept as it has developed in

the United States over the last century. We then

discuss preliminary findings of a large-scale

diversity assessment for an extensive forest

area in the Southern United States, along with

considerations that are important when applying

such assessments over large geographic regions.

A case study based on data from recent forest

surveys of Mississippi is used to illustrate a

method of tracking tree species richness over time.

HISTORICAL OVERVIEW OF THE DIVERSITY

CONCEPT IN THE UNITED STATES

M

uch of the species diversity work after

the 1950s was aimed at devising new

mathematical methods for quantifying

diversity assessments. This review does not cover

the broad range of studies devoted exclusively

to that subject. Additionally, a general lack of

standardization in the terminology may cause

some confusion. In this chapter, we use the terms

richness and species diversity interchangeably,

but we recognize that richness is one type of

measurement attribute describing species

diversity (Magurran 1988, Pielou 1974). Richness

has traditionally been defined as the number of

species occurring in a specific area. This area may

be small or large. It is important to understand

how the richness measure (or any other species

diversity measure) is obtained because results

obtained from applying different sample designs

to the same sample population have differed

considerably (Diserud and Aagaard 2002).

Earlier, the concept of species diversity

was regarded as a historical phenomenon related

to the accumulation of species over time (Fischer
337Chapter 28. Monitoring Tree Species Diversity

1960, Wallace 1876, Willis 1922). What is now

called the study of species diversity was

considered as part of the study of species

abundance and species populations. Much of the

interest and early work in species abundance was

by animal ecologists (Kingsland 1985). The early

part of the 20th century also saw the beginning of

development of techniques for describing plant

communities in quantitative terms. Examples

include the works of Clements (1905), Gleason

(1920), Cain (1932), and Braun (1935). Oosting

(1956) described the difference between two

approaches to analysis—descriptive (analytical)

statistics and qualitative (synthetic) statistics.

Descriptive statistics involved measures of

individual stands (the actual concrete community

that could be visualized on the ground); qualitative

statistics were estimates of measures of several

stands in aggregate (the abstract community

type composed of disjunct stands).

Jaccard (1912) was the first to demonstrate

that there was an increase in the number of

species with an increase in area (Goodall 1952).

This was later expressed mathematically by

Arrhenius (1921). Application of the terms “rich”

and “poor” is usually credited to Baker (1918),

who recorded the number of species on lake

bottoms. Thienemann, a limnologist in Europe,

identified three important species-abundant

principles: (1) the greater the variety of habitats,

the larger the number of species; (2) the more

that conditions deviate from the normal optima

for most species, the smaller is the number

of species that occur and the greater the number

of individuals that do occur; and (3) the longer a

habitat has been in the same condition, the richer

and more stable is the community (Goodman 1975,

Hynes 1972). The third of these principles is now

known as the stability-diversity hypothesis, and

is still studied and strongly debated today.

Elton (1927) and others realized that species

numbers and diversity were most likely a part of

important principles in plant and animal ecology,

but Elton observed that it was not clear what

these important principles entailed (McIntosh

1985). Publication of Thienemann’s first two

principles led other workers to conduct a long

series of studies involving species-area relations.

Cain (1938) and Preston (1948) were early

investigators of species-area curves. The early

work dealing with mathematical properties of

species-area relations has been reviewed by

Connor and McCoy (1979). By carefully

counting species, several investigators were able

to demonstrate that species were organized into

predictable compositions (at least at the guild

level) and structures (Gleason 1922; Preston 1948;

Williams 1944, 1953). Many early works showed

that a majority of species were rare and less

abundant, and that only a few species were

dominant or very abundant. Ecologists soon found

it was not possible to conduct a census of an entire

biotic community and that patterns of dominance

and species abundance would have to be detected

by sampling (Golley 1993). Graphing the number

of species observed against the number of

individuals on a logarithmic scale often produced

a straight line. Supposedly, the slope of this line

was a measure of the species diversity of the

community (Fisher and others 1943). Pielou

(1977) states that this approach to species

diversity analysis was first introduced by Fisher

in 1943. Margalef’s later work (1958) was

instrumental in the popularization of the phrase

“species diversity” among ecologists (Green

1979). Although much work had been done

on species diversity up through the 1950s,

no ecology textbooks of the 1940s and 1950s,

with the exception of Odum’s textbook (1959),

even mentioned the term “diversity” (Schluter

and Ricklefs 1993).

In 1969, the famous Brookhaven Symposia

in Biology maintained that the continuity and

sustainability of life systems appeared to be

associated with the number of species per unit

of area (Wolda and others 1969). This meeting

also ensured the popularization of the term

“diversity.” By the late 1960s the study of diversity

was expanding, involving not only the number

of species but also the proportionate distribution

of individuals (evenness) and the consequent

development of a myriad of diversity indices. This

period also marks the beginning of a significant

number of diversity study contributions to the

literature. Lloyd and Ghelardi (1964) are credited

with introducing use of the term “evenness”

in the context of diversity (Krebs 1989).

The beginning of the modern era of

quantitative ecology has been attributed to

MacArthur (McIntosh 1985). Building on Preston’s

work (Preston 1948) concerning the canonical

distribution of species, MacArthur and Wilson

expanded upon Preston’s idea as the basis for their

seminal book “Theory of Island Biogeography”

(1967). Ideas developed in this book essentially set

the stage for much of the ecological work over the

next two to three decades. Many workers in either

plant or animal ecology borrowed and built upon

MacArthur’s ideas and work related to speciesarea and species-distribution phenomena.
Southern Forest Science:

Past, Present, and Future

Biodiversity

338

The literature related to species diversity

studies and technique development over the last

several decades is voluminous. Many papers in

the literature have dealt with the development of

new and improved measures of diversity. Several

papers and books are considered seminal and

helped clarify and resolve certain issues pertaining

to the problems of measuring and analyzing

species diversity data. Examples are Pielou (1969,

1975), Peet (1974, 1975), and Hurlbert (1961).

A comprehensive summary of the diversity

literature, prior to 1979, has been prepared

by Dennis and others (1979).

Diversity analysis was incorporated into many

ecological studies after the 1960s, and increases

in tropical forest land clearing and growth of the

environmental movement stimulated interest

in species diversity along with genetic diversity,

habitat diversity, landscape diversity, and

ecosystem diversity. In the United States,

questions were raised about the management

of national forests. One particular concern was

the conversion of hardwood stands to pine stands.

To address this concern, language identifying

the need to preserve natural diversity was written

into the National Forest Management Act of 1976.

An important workshop addressing this issue was

held in 1982 (Cooley and Cooley 1984).

Prominent biologists were quick to address

global threats to diversity. This resulted in the

National Forum on Biodiversity, which took place

in Washington, DC, in September 1986 (Wilson

and Peter 1988). The published proceedings of

this meeting were distributed widely and quickly

brought national and international attention

to the potential problem of declining species

diversity and the ultimate loss of species

through extinction. Since then a followup volume

“Biodiversity II” has been published, covering

such topics as how scientists study diversity, the

status of existing knowledge about life on Earth,

and a series of key questions that remain

unanswered (Reaka-Kudla and others 1997).

Since the National Forum on Biodiversity,

other important conferences have been held.

These include the International Symposium of

Ecological Perspective of Biodiversity which took

place in Kyoto, Japan, in December 1993 (Abe and

others 1997); the Symposium on Biodiversity in

Managed Landscapes: Theory and Practice, held

in Sacramento, CA, in July 1992 (Szaro and

Johnston 1996); the Sixth Cary Conference, held

in May 1995 at the Institute of Ecosystem Studies,

Millbrook, NY (Pickett and other 1997); and

the plenary sessions of the 45th annual meeting

of the American Institute of Biological Sciences

at Knoxville, TN, in August 1994. The last resulted

in the publication of a supplementary issue of the

journal “Bioscience” (Bioscience 1995). These

meetings and published proceedings focused

on educating the public about the importance

of biodiversity, described the current state of

knowledge in particular disciplines, and provided

examples of failures and successes in managing

ecosystems to preserve biological diversity while

maintaining economic viability (Powledge 1998).

Several books about diversity have been

published over the last few years. Examples

include “Species Diversity in Space and Time”

(Rosenzweig 1995), “Species Diversity in

Ecological Communities” (Ricklefs and Schluter

1993), “Biological Diversity” (Huston 1994),

“Precious Heritage: The Status of Biodiversity

in the United States” (Stein and others 2000),

“Saving Nature’s Legacy: Protecting and

Restoring Biodiversity” (Noss and Cooperrider

1994), “Maintaining Biodiversity in Forest

Ecosystems” (Hunter 1999), “Ecological Diversity

and its Measurement” (Magurran 1988), “The

Unified Theory of Biodiversity and Biogeography”

(Hubbell 2001), “Global Biodiversity Assessment”

(Heywood 1995), “Global Biodiversity: Status

of the Earth’s Living Resources” (Groombridge

1992), and “Biodiversity: A Biology of Numbers

and Difference” (Gaston 1996). All are

comprehensive in scope and include sizeable

reference sections. Huston’s reference section

covers 98 pages. The list above is not complete

but provides an entrance into the literature.

Although much work has been completed on

the theory and concepts of biological diversity,

little has been done on the application of this

theory to real world problems. The literature is

based largely on incidental observations or reports

rather than detailed systematic and analytical

evaluations. Studies dealing with comparative

analysis are valuable and rare (Machlis and

Forester 1996).

Most of the studies that have been undertaken

were done in small areas that had attracted

investigators’ attention, mostly because these

sites had unusual biotic or abiotic characteristics.

The cost in time and money of sampling across

areas larger than a few hundred hectares is often

prohibitive. Examples of plant patterns and

responses to anthropogenic disturbance in

forests at a small scale can be found in Grime
339

(1979), Oliver (1981), and Hunter (1990). Certain

workers, such as Sites and Crandall (1997) and

Skov (1997), have implemented novel approaches

to biodiversity studies. Quantitative studies using

systematic and analytical techniques on a large

regional scale (an area the size of a State or larger)

are lacking (Langer and Flather 1994, LaRoe and

others 1995). There have also been requests for

the establishment and application of rigorous

standardized sampling and analytical techniques

for biodiversity assessments (Debinski and

Humphrey 1997, Solomon 1979).

Because of the cost and complexity of sampling

large continuous geographic areas, very little, and

very limited, data (usually addressing only specific

resource and conservation issues) are available

for large regional studies. Some investigators

have taken several local studies and extrapolated

the results to a larger area or continental region.

One example is a study by Glenn-Lewin (1977)

in which richness information data from six

temperate forest communities across North

America were analyzed for correlations across

large spatial scales in species diversity within

ecosystem and community structure. Other studies

have also followed a similar approach, either

by aggregating several local studies scattered

across a region or by using abstract information

from flora listings by county (Currie 1991, Currie

and Paquin 1987, Monk 1967). Although such

efforts provide much-needed information, these

studies lack rigor because they are based on

nonprobability samples and because they have

too few plots (from a regional perspective).

Additionally, the data come from studies that

poorly represent the whole of vegetation

conditions and complexes across large areas.

There have been few definitive descriptions

of diversity of temperate tree species in relation

to disturbance over areas as large as a State.

Only one study has attempted to evaluate these

relationships over large geographic areas;

Stapanian and others (1997) used data from Forest

Service Forest Health Monitoring plots, but these

data were incomplete because only 14 States were

included in the program at the time of the study

and because there were fewer than 150 forested

plots (on average) for each State. It is questionable

whether this small number of initial sample plots is

sufficient to represent an area as large and diverse

as a State. Additionally, such a small number of

plots severely limits any attempt to poststratify

the data. Since implementation of the Forest

Health Monitoring Program has only recently

begun, no adequate historical data are available.

Therefore, trend analysis of species diversity is

very limited at this time with these datasets.

Beyond the timber supply issue, concerns

have been raised about the sustainability of the

entire biotic and abiotic forest base. Several recent

books have documented the urgent need to alter

forest management practices to achieve certain

conservation goals (Hunter 1980, Huston 1994,

Kohm and Franklin 1997, Noss and Cooperrider

1994, Szaro and Johnson 1996). The Forest Service

has adopted and implemented the concept of

ecosystem management in order to protect and

provide sustainability for all attributes of forests.

Foremost in these new approaches to forest

management is the concept of managing forests in

a way that protects and fosters the establishment

of natural biodiversity. With the establishment

of the biosphere initiative, the Ecological Society

of America has brought the biodiversity problem

to the public forum and to the attention of

policymakers (Lubchenco and others 1991).

Additionally, the dialog has gone beyond the

biological aspect of the diversity issue to include

and quantify the economic benefits of a diverse

natural world (Freeman 1998).

There has been much speculation about the

impact of timber harvesting on forest biology,

most of it based on studies of small stands.

Application of a probability-based sample would

provide meaningful insight into the status of any

State’s forests. Some investigators have concluded

that the status of species diversity in U.S. forests

has improved dramatically during the last century

(Salwasser and others 1992). Others are convinced

that the degradation of entire ecosystems is

continuing (Noss and others 1994). No studies

or rigorous statistics that accurately document

the status of biodiversity over large areas

in the United States are available (LaRoe

and others 1995, Noss and Cooperrider 1994,

U.S. Environmental Protection Agency

1990). Therefore, neither claim can be

supported rigorously.

Resources for tightly focused large-scale

research efforts to evaluate trends in diversity are

lacking. Therefore, it seems appropriate to adapt

and employ existing large-scale data, particularly

if it is rigorously assembled, for the analysis of

diversity dynamics. Such data, although originally

assembled for use in timber inventory studies and

quantitative interpretation, exist in the continuous

forest inventory records of the Forest Service,

Forest Inventory and Analysis (FIA). These data,

Chapter 28.

 Monitoring Tree Species Diversity
Southern Forest Science:

Past, Present, and Future

Biodiversity

340

which have been collected under conditions that

allow their validity to be tested, can be used to

demonstrate diversity trends and dynamics over

a large spatial scale over a considerable period

of time. Below, we analyze such data for the State

of Mississippi.

A CASE STUDY OF DIVERSITY TRENDS

IN A SOUTHERN FOREST

D

ata for Mississippi were used as a source of

information about changes in tree species

diversity over time. The data were from the

FIA Program and consisted of field plot data

collected over the last 35 years during four survey

measurements (1967, 1977, 1987, and 1994). Field

plots in which tree harvesting occurred were

considered as having undergone experimental

manipulation; plots in which there was no

harvesting during the four survey measurements

were considered the control. This methodology—

that of treating natural or anthropogenic

disturbance as the manipulation stage of an

experiment—is useful in situations in which

it is impractical to conduct a true experiment

(Hairston 1989, Scheiner 1993).

The study consisted of two phases. In the

first phase, all of the plots in the statewide

sample were considered without any regard to

poststratification criteria. Levels of tree species

diversity for the four survey measurements were

compared. In the second phase, only sample plots

that had not been harvested during the period

covered by the four survey measurements were

considered. The null hypothesis, that there was no

difference in tree species diversity over the four

survey measurements made in 1967, 1977, 1987,

and 1994, was tested for both the total plot dataset

and the undisturbed plot dataset with parametric

statistics. The repeated measures analysis-ofvariance procedure was used for the tests, with

significance established at the 0.05-percent level.

Only trees larger than or equal to 12.7 cm in

diameter at breast height were included in the

analysis. An overview of the forest survey sample

design used in Mississippi has been described by

Rosson (2001). The diversity measure used was

species richness, defined as the total number of

different species occurring on each survey sample

unit (field plot). This was a departure from

traditional practice, in which the species richness

count is typically the sum of different species

occurring on all of the sample units. An advantage

of analyzing the richness count by sample unit was

that this procedure made it possible to utilize

parametric statistical tests. Additionally, this

methodology reduced the effect of overweighting

the loss of one or two species. This was especially

important in this study because the low sampling

intensity over a large scale means that the forest

survey sample design does not adequately sample

rare or infrequently occurring species. Preston

(1948) has shown how sampling fails to capture the

entire spectrum of species. There will always be a

percentage of species that occur so infrequently

that they will not be detected by sampling. In

large-scale assessments it is important that

richness measures reflect overall shifts across

a State. The occurrence or nonoccurrence

of one species on only one sample plot may

reflect only a uniqueness of the sample design,

and not a biological event.

RESULTS AND DISCUSSION

Disturbance Background

B

etween 1977 and 1994, 4.1 million ha of

Mississippi timberland underwent some

form of harvesting.2 A harvest was defined

as any harvesting activity in which all, or a high

proportion, of the manageable stand was removed,

thereby marking the beginning of a new stand

rotation. Examples of types of harvests are partial

harvests (which would include various selection

methods), seed tree, shelterwood, high-grade,

and clearcut harvests, as defined by Smith (1962).

In addition to these harvested areas, another 0.9

million ha of timberland underwent cutting in an

intermediate stand treatment such as thinning or

stand improvement.

Of the 4.1 million ha harvested in Mississippi,

1.6 million ha were clearcut (see footnote 2).

Clearcutting often has the greatest potential effect

on altering tree species diversity. This is because

natural stands that are harvested are frequently

replaced with monospecific softwood plantations.

Management programs typically favor only one

species in plantations. In addition, harvest cycles

may become shorter and shorter.

The clearcut acreage was spread fairly evenly

across Mississippi, with the exception that clearcut

acreage was lower in the northwest portion of the

State (fig. 28.1) (see footnote 2). Between 1977 and

2

 Rosson, James F., Jr. Current stand characteristics of

Mississippi timberland harvested between 1977 and 1994. 21 p.

Manuscript in preparation. On file with: Southern Research

Station, Forest Inventory and Analysis, 4700 Old Kingston

Pike, Knoxville, TN 37919.
341

Field measurement (year)

1967 1977 1987 1994

Mean number of species per sample unit

4.2

4.4

4.6

4.8

5.0

5.2

n = 2,990 

n = 2,806

n = 2,958 

n = 3,180

Field measurement (year)

1967 1977 1987 1994

Mean number of species per sample unit

4

5

6

7

8

n = 553 

n = 553 

n = 553 

n = 553 

1987, 0.6 million ha of new softwood plantations

were established; another 0.4 million ha were

established between 1987 and 1994. Currently,

there is a total of 1.7 million ha in softwood

plantations throughout Mississippi.3 The direct

effect of these monocultural plantations was to

reduce average tree species diversity in the State.

Tree Species Diversity Dynamics

Mean tree species richness estimates, across

Mississippi, for all sample units combined were

4.53, 5.02, 4.82, and 4.49 species per sample unit

for survey years 1967, 1977, 1987, and 1994,

respectively (fig. 28.2). There was not a significant

difference between richness in 1967 and richness

in 1994 (df = 2,805, p < 0.0617). The change in

richness from 1977 to 1994 was highly significant

(df = 2,805, p < 0.0001); note that significant is

(0.05 ≥ p > 0.01); very significant is (0.01 ≥ p >

0.001), and highly significant is (p ≤ 0.001) (Sokal

and Rohlf 1995).

In contrast, tree species richness means for

sample units without any harvesting disturbance

were 4.73, 5.86, 6.49, and 6.80 species per sample

unit for 1967, 1977, 1987, and 1994, respectively

(fig. 28.3). The increase in richness between

1967 and 1994 was highly significant (df = 552,

p < 0.0001).

Tree species richness for all sample units

combined increased between 1967 and 1977.

Thereafter, richness declined in every survey

Chapter 28.

 Monitoring Tree Species Diversity

3

 Rosson, James F., Jr. The status of forest plantations in

Mississippi, 1994. 30 p. Manuscript in preparation. On file with:

Southern Research Station, Forest Inventory and Analysis,

4700 Old Kingston Pike, Knoxville, TN 37919.

Figure 28.1—Spatial distribution of clearcut

timberland in Mississippi. Each dot represents

500 ha of clearcut timberland, harvested

between 1977 and 1994. During this period,

1.6 million ha were clearcut.

Figure 28.2—Mean species richness per sample unit

for Mississippi, by survey year, for all sample units. The

error bars represent 2 standard errors of the mean.

Figure 28.3—Mean species richness per sample unit

for Mississippi, by survey year, for sample units that

had no evidence of harvesting disturbance during the

four survey measurements. The error bars represent 2

standard errors of the mean.
Southern Forest Science:

Past, Present, and Future

Biodiversity

342

measurement. One possible explanation for this

was that the forests of Mississippi, within that

period, were recovering from the heavy cutting

that ended in the 1930s. Species richness had, most

likely, been increasing through the decades that

followed that cutting. It was during the late 1960s

and 1970s that a new wave of timber harvesting

began. The peak of more than five species per plot

in 1977 (fig. 28.2) may indicate the end of the

recovery period and the beginning of a new period

of decline in species richness. The analysis is

complex because there is no adequate source of

baseline data with which to compare results. We do

not know what constitutes a normal, healthy level

of tree species richness for this particular sample

design. The undisturbed sample units were the

only applicable benchmark for potential tree

species richness in Mississippi, and one should

recognize that factors other than harvesting could

have affected richness. Examples of such factors

might include ownership (and owner objectives),

site, and stand history. Moreover, the stage of

succession will also affect the number of species

per plot. Some forest stands that are in

midsuccessional stages may have the highest

richness because they contain early, mid, and latesuccessional species.

Demonstrating a significant difference between

means without considering the ecological relevance

of the difference may be trivial. Recent literature

has emphasized the importance of the distinction

between biological and statistical significance

(Hilborn and Mangel 1996, Krebs 1989, Scheiner

1993). In our study, we consider the change in tree

species richness to be both biologically and

statistically significant, based on the following.

First, the same sample units were remeasured

during each survey year. Second, and most

importantly, the sample design remained the same

throughout all four measurements. The same

sample unit points were remeasured and the same

basal-area prism factor was used throughout. It is

also very important that the species lists for all the

survey periods were the same. This meant

grouping some species from the recent, more

detailed, surveys to match those of older surveys

(when there was less emphasis on tallying species

of lesser economic importance). See Rosson (1999)

for further details.

Use of remeasured plots helps eliminate much

of the variation that is inherent in natural

populations. High levels of variation can mask

some true biological differences, so reducing this

variation as much as possible improves the rigor of

the study (Hayek and Buzas 1997, Husch and

others 1982). In monitoring studies, the best

estimates of variables used to detect change, such

as density and basal area, are provided by the use

of permanent, remeasured sample units (Bonham

1989). Second, the magnitudes of richness change

(usually more than 3 percent), together with the

size of the sample and a very low standard error,

further support the evidence of real biological

shifts in trees species richness. Finally, the

comparison of the undisturbed sample units with

all the sample units combined empirically supports

the overall decline in tree species richness since

the 1977 survey measurement.

The fact that tree species richness has

increased significantly on sample units without

harvesting supports the premise that harvesting

disturbance is the major contributing factor in the

decline of tree species richness. However, it is

important to note that the study did not, nor was it

designed to, find a causal agent of decline in

richness. The study only points out that tree

species richness has declined significantly over

time and that concurrent harvesting disturbance is

probably a major contributing factor.

There are no established criteria or guidelines

for determining what level of tree species richness

is too low for an area as large as a State. Also, we

do not know the degree to which tree species

richness varies naturally. Finally, little is known

about the resiliency of mixed forest stands to the

disturbances to which they are being exposed.

Further work needs to be done in these areas

before the results of tree species richness

monitoring can be utilized in a rigorous and

meaningful manner.

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Chapter 28.

 Monitoring Tree Species Diversity

347

Developed Other PasturelandRangelandCropland

0

2

4

6

8

10

12

14

New land use

Deforestation (million acres)

Chapter 29.

Population Growth and the Decline of

Natural Southern Yellow Pine Forests

David B. South and

Edward R. Buckner1

Abstract—Population growth has created

social and economic pressures that affect the

sustainability of naturally regenerated southern

yellow pine forests. Major causes of this decline

include (1) a shift in public attitudes regarding

woods burning (from one favoring it to one

that favors fire suppression) and (2) an increase

in land values (especially near urban centers).

The increase in land values reduces the chance

of farmland abandonment, which was common

in the first half of the 20th century. Abandoned

farmlands provided many of the sites for the

naturally regenerated pine stands that are being

harvested today. Also, higher land values and

higher taxes put pressure on landowners to

subdivide their land for development or to

establish more profitable tree plantations.

These population-related factors and outbreaks

of the southern pine bark beetle have resulted

in a decline in naturally regenerated southern

pines of more than 38 million acres since

1953. As population pressures reduce the

incidence of wildfire, prescribed burning,

and the abandonment of old fields, the decline

in naturally regenerated southern yellow pine

will continue. By 2030, only 23 million acres

of natural southern yellow pine may remain.

INTRODUCTION

P

opulation growth is the principal factor

placing pressure on forest lands (Barlow

and others 1998; Wear and others 1998,

1999). In some cases, the effect is immediate

as when naturally regenerated forests are

converted to developments, pastureland,

rangeland, cropland, plantations, or other

uses. In the United States, 11.7 million acres

of forests were converted to developed land

during the period from 1982 to 1997 (fig. 29.1).

Population growth also influences forests in

subtle ways that take place over decades. The

public generally overlooks gradual changes in

species composition, even when millions of acres

are affected. Naturally established southern

yellow pines2 are disappearing over Eastern

North America. This trend is exacerbated by

southern pine bark beetle (Dendroctonus

frontalis Zimmermann) epidemics.

With the exception of spruce pine (Pinus

glabra Walt.), southern yellow pines are intolerant

of shade, and exposed mineral soil is generally

required for their successful establishment. Pines

were often the primary tree cover over much of

the Southeast when the first historians recorded

plant names. However, during the second half

of the 20th century, the combined effects of fire

1 Professor, Auburn University, School of Forestry

and Wildlife Sciences, Auburn, AL 36849; and Professor

Emeritus, The University of Tennessee, Department

of Forestry, Wildlife and Fisheries, Knoxville, TN

37996, respectively.

2 For the purpose of this chapter, the southern yellow

pines are defined as eight members of the genus Pinus

(subsection Australes Loud.) plus sand pine and Virginia

pine. “Natural” stands of pine are those that are regenerated

by seedfall and not by direct seeding or planting.

Figure 29.1—The conversion of forested land to other

land uses in the United States from 1982 to 1997 (U.S.

Department of Agriculture, Forest Service 2001).
Southern Forest Science:

Past, Present, and Future

Biodiversity

348

1960 1980 2000 2020 2040

20

30

40

50

60

70

80

Year

Timberland (million acres)

1950 1960 1970 1980 1990 2000

0

20

40

60

80

Year

Stands (million acres)

Oak-hickory Oak-pine Pine plantations

suppression, increases in naturally regenerated

hardwoods, and conversion of old-field pine stands

to plantations of loblolly pine (P. taeda L.) and

slash pine (P. elliottii Engelm. var. elliottii) have

resulted in a decline in natural southern yellow

pine timberland3 from 72 million acres in 1953 to

34 million acres in 1997 (fig. 29.2). In contrast, oak

(Quercus spp.), hickory (Carya spp.), red maple

(Acer rubrum L.), sweetgum (Liquidambar

styraciflua L.), and other hardwoods have

increased. Oak-pine and oak-hickory stands

have increased by more than 25 million acres

(fig. 29.3). Pine plantations (many established

on former agricultural lands) have also increased

by an estimated 30 million acres (table 29.1).

If foresters had not planted pine seedlings

and not used herbicides and prescribed burning,

we estimate that there would be < 30 million acres

of southern yellow pine forests today (instead of 63

million acres). This is because pine plantations are

more productive than natural stands. Although

plantations represent about 14 percent of the

southern forests, they provide more than half

of the wood harvested each year.

FIRE AND POPULATION GROWTH

When populations of counties increase, the

value of land and timber in those counties

increases. Also, the number of houses “in

the woods” in the South has increased dramatically

since 1950. As property values increase, the need

to protect these assets from wildfire increases. The

management of fire is related to human population

density. South (the author) hypothesizes that the

number of wildfire burns of more than 1,000 acres

is related to population density. Counties with

population densities of < 6 persons per square

mile will likely have a higher probability of a

regeneration fire than counties with more than

1,000 persons per square mile. In addition,

foresters find it harder to conduct prescribed

burns as population density increases. The

absence of fires discourages natural pine

regeneration and allows hardwoods to

replace pines.

Before Humans

Before humans settled North America, forest

fires were started by lightning and occasionally by

volcanoes. In the Southeast, southern yellow pines

adapted to a variety of fire regimes. Some pines

such as pond pine (P. serotina Michx.), Ocala sand

pine [P. clausa var. clausa (Chapm. ex Engelm.)

Vasey ex Sarg.], Table Mountain pine (P. pungens

Lamb.), and some pitch pine (P. rigida Mill.)

genotypes evolved serotinous cones. The chances

of successful natural regeneration of these species

were strongly tied to fire frequency and intensity.

Although the cones of loblolly pine, slash pine,

shortleaf pine (P. echinata Mill.), longleaf pine

(P. palustris Mill.), and Virginia pine (P. virginiana

Mill.) are not serotinous, fires helped to maintain

viable populations of these species. Value

judgments about species types, stand origin,

and timber volumes were not made during this

period, as humans were not part of this ecosystem.

3 Natural pine timberland: stands in which 50 percent or

more of the volume is composed of naturally regenerated

pine and which are capable of producing crops of industrial

wood. This does not include pine forests in national parks or

other areas that are withdrawn from timber utilization by

statute or administrative regulation.

Figure 29.3—Increases in oak-hickory, oak-pine,

and pine plantation stands from 1953 to 1997 (U.S.

Department of Agriculture, Forest Service 2001).

Figure 29.2—Actual and predicted decline of natural

southern yellow pine timberland in the South (U.S.

Department of Agriculture, Forest Service 1988;

Wear and Greis 2002).
349Chapter 29. Natural Southern Yellow Pine Forests

Prehistoric Cultural Impacts

As humans moved into North America

from Asia 12,000 years ago, they brought fire

with them as a cultural tool. They often burned

both grasslands and woods. These activities

“superimposed a new and extensive fire regime

over the existing natural one” (Pyne 1982). Fire

was employed to replace forests with grasslands

and thereby support grassland browsers as a food

source. Fire was also used as an aid to hunting,

as a tactical weapon, as a method of weed control,

and sometimes in hope of altering weather (Pyne

1982). Blankets were used to extinguish accidental

fires in lodges and villages. Backfires were set

to keep wildfires from reaching villages. There

are no references supporting the idea that early

inhabitants of North America suppressed wildfires

in forests.

Early European Settlement Fires in the South

European explorers who traveled along the

eastern coast of North America frequently saw

fires and thick smoke. When Europeans settled

along the east coast, most adopted the practice

of burning the woods. “Perhaps nowhere else in

the country were Indian burning practices more

thoroughly adopted and maintained than in the

piney woods, in the remote hills, and on the sandy

soils . . .” of the South (Pyne 1982). Pyne (1982)

further claims that

Early settlers on the coastal plains

learned broadcast burning from local

tribes. As they moved inland, crossing

some of the premier fire regimes of North

America, pioneers carried their fire habits

with them. The northern woods might be

cleared and settled without fire, but not

the southern rough. Skill in broadcast

Table 29.1—Changes in timberland area over a 44-year period for selected

species in the United States

Region Stand type 1953 1997 Change Change

- - - - million acres - - - - %

South Longleaf and slash 26.9 13.1 -13.8 -51

South Loblolly, shortleaf, and others 51.8 49.7 -2.1 -4

North Loblolly, pitch, shortleaf, Virginia 3.6 2.3 -1.3 -36

South Longleaf 12.2 2.8 -9.4 -77

South Loblollya 35.6 39.1 +3.5 +10

South Shortleafa 7.8 4.7 -3.1 -40

South Slash 14.7 10.3 -4.4 -30

South Virginia, pond, pitch, sanda 8.4 5.9 -2.5 -30

South Southern yellow pine

timberland total 78.7 62.8 -15.9 -20

South Oak-pine 24.0 29.8 +5.8 +24

South Oak-hickory 54.9 74.3 +19.4 +35

South Oak-gum-cypress 34.5 28.5 -6.0 -17

South Oak total 113.4 132.6 +19.2 +10

South All timberland 204.5 201.0 -3.5 -2

a

 Acreages are estimates made by the authors. Note: Timberland does not include land in national

parks or wilderness areas where timber harvesting to produce crops of industrial wood is not

allowed due to statute or administrative regulation. The total of forest land and plantations in

the South was 226 million acres in 1953 and 214 million acres in 1997 (U.S. Department of

Agriculture, Forest Service 2001).

Source: Outcalt and Sheffield (1996); Smith and others (2001); U.S. Department of Agriculture,

Forest Service (1988).
Southern Forest Science:

Past, Present, and Future

Biodiversity

350

fire was essential to southern frontier

survival: nearly all dimensions of southern

agrarian economy relied on it - for

landclearing, for hunting and habitat

maintenance, and for range improvement.

It was employed for fuel reduction in

naval stores operations, the antecedent

to industrial logging, and it was used by

homesteaders to protect themselves from

the fires that others were sure to light.

Fire protection was even built into the

architecture of frontier cabins: the cleared

yards around wooden structures acted as

firebreaks and as points for igniting

protective backfires - doing double duty,

as fish ponds did for rural houses in New

England. What made the South special,

however, was the confluence of economic,

social, and historical events that worked

to sustain this pattern of frontier economy

long after it disappeared elsewhere in the

United States, a pattern that created a

socioeconomic environment for the

continuance of woodsburning.

20th Century Fires in Southern Forests

Even though laws were passed that penalized

woods arson, it continued to be a common practice

throughout most of the 20th century. With an

increase in population, there was an increase in

the number of incendiary fires (U.S. Department

of Agriculture, Forest Service 1968). The 50-year

average (1917–66) for incendiary fires in the

South equates to 39 percent of all wildfires.

In comparison, the 5-year average (1973–78)

for incendiary fires rose to 55 percent (U.S.

Department of Agriculture, Forest Service 1980).

In 1978, there were 35,850 incendiary fires in the

South (U.S. Department of Agriculture, Forest

Service 1980). This was far more than occurred in

other regions such as the Eastern States (2,589)

and the Pacific States (3,135).

As populations grew, the number of people

employed to suppress fire also grew. The result

was a decline in the total area of woods burned

annually. In 1917, 14 million acres were burned

on protected areas of the South. By 1999, only

about 1 million acres burned annually. Each year,

< 0.4 percent of the South’s forest land is now

burned. The average fire size was about 13 acres

in 1978 (U.S. Department of Agriculture, Forest

Service 1980).

Over recent decades, public attitudes

toward woods burning have changed. As

population increased, the acceptability of fire

in the environment has decreased. For example,

a 1996 survey showed that a majority of

respondents disagreed with the statement,

“Using fire as a management tool in the national

forest is a good idea” (Southern Appalachian

Man and the Biosphere 1996). Today, natural

and arson fires are rapidly extinguished to protect

human investments. Suppression of wildfires

has increased to the point that when 7 million

acres burn, it is considered a “bad fire year.”

We certainly do not wish to see our homes and

cabins go up in smoke. As a result, few biologists

would suggest that forest fires should be allowed

to reach a “natural equilibrium.”

POPULATION GROWTH AND HARVESTS

T

he amount of forest land available for timber

harvesting in a region is negatively related

to the region’s population density (Wear

and others 1998, 1999). In North Carolina, the

percentage of a county in timberland might decline

from 70 to 30 percent as the population level

increases from 40 to 990 people per square

mile (Wear and others 1998). A decline in forest

land will reduce both the acreage harvested

and the acreage in early stages of natural pine

regeneration. In the absence of wildfire and

management to obtain natural pine regeneration,

a reduction in harvesting will favor succession

from pine to hardwoods.

INCREASE IN HARDWOODS

A

 reduction in the acreage burned results

 in a decrease in natural regeneration of

 pines while that of hardwoods increases.

Even though relatively few oaks, red maples,

or hickories are planted in the South (Boyer

and South 1984), there have been large increases

in the acreage of upland hardwood stands since

1953 (table 29.1). Since 1953, the increase in oakhickory and oak-pine stand types totals more

than 25 million acres. Ingrowth of hardwoods

likely converted 5 million acres of pine stands

into oak-pine stands (in which hardwoods make up

50 percent or more of the basal area). Continued

aversion to the use of fire and herbicides in pine

stands will result in additional conversion of pine

stand types to oak-pine or oak-hickory stand

types. Currently, the acreage of natural oakhickory forest type (fig. 29.4) is twice that of all

southern yellow pine types combined.
351

Longleaf-slash

pine

Loblolly-shortleaf

pine

Oak-hickory

0

50

100

150

Forest-type group 

Timberland (million acres)

Forest Service

Public

Industry

Private

Pastureland Cropland Rangeland Rural land

0

2

4

6

8

10

12

14

Former land use

Afforestation (million acres)

Chapter 29.

 Natural Southern Yellow Pine Forests

High-grading is a common harvesting method

on private lands. For example, a landowner might

remove all of a stand’s merchantable pines, leaving

25 percent of the stand’s original basal area

in low-quality hardwoods. The resulting stand

would be reclassified as an oak-hickory forest type.

This trend is much greater on lands owned by

individuals than on land owned by industry (Alig

and others 1986). Since most of the land in the

East is owned and managed by private individuals

(fig. 29.4), there has been an overall decline

in southern yellow pine since 1953 (table 29.1).

About 60 percent of the forest acreage harvested

annually in the South is harvested by methods

other than clearcutting (U.S. Department of

Agriculture, Forest Service 2001), but this

percentage is higher on privately owned lands.

Only about 1 percent of the forest area in

the South is clearcut annually (Rudis 1998).

Even-aged regeneration harvesting on national

forests in the Southern Appalachian region is

declining (Southern Appalachian Man and the

Biosphere 1996).

Southern pine beetles generally kill pines

that are under stress caused by drought or from

high-stocking levels or both. Droughts increase

the incidence of outbreaks, but overstocking is

often the prime factor that weakens the pines

(Ku and others 1980). The absence of management

practices to control stocking will increase the risk

of mortality from southern pine beetles. Recently,

thousands of acres of natural pines have been

killed throughout the South.

INCREASE IN PLANTATIONS

I

n 1926, there were only about 3,000 acres

of pine plantations in the South. By 1953,

pine plantations occupied 2 million acres, and

plantation acreage increased to more than 32

million acres by 1999 (Wear and Greis 2002).

Today, approximately 17 percent of forest land

in the South is in pine plantations. Even though

pine plantation acreage has increased by 33 million

acres since 1953, pine types have declined by about

16 million acres (table 29.1). This decrease is due

largely to the inaction of nonindustrial private

landowners (Alig and others 1986) who do not

use artificial or managed natural regeneration to

maintain their land in pine-dominated ecosystems.

Natural regeneration of pines after harvesting can

be difficult without fire, herbicides, or mechanical

site preparation.

Pine plantations have been established widely

on former farmland. The Soil Bank Program was

responsible for the stabilization of 1.9 million acres

of mostly “worn out” farmland between 1956 and

1961. During the 1980s, the Conservation Reserve

Program stimulated widespread establishment

of pine plantations. This effort was responsible

for the planting of more than 2.6 million acres on

farmland. In addition, subsidy programs helped

to establish more than 180,000 acres of longleaf

pine plantations on farmland. Between 1982 and

1997 more than 22 million acres of afforestation

occurred on former pastureland, cropland, and

rangeland (fig. 29.5). A large portion of this was

from artificial regeneration. Of the 30.3 million

acres of pine plantations that existed in 1997, at

least 2.7 million acres were afforested through

Government incentive programs. We estimate

that by 1997, more than 5 million acres of southern

Figure 29.4—Acreage of naturally regenerated

longleaf-slash pine, loblolly-shortleaf pine, and oakhickory forests in the Eastern United States in 1997

by ownership class (U.S. Department of Agriculture,

Forest Service 2001).

Figure 29.5—The afforestation of nonforested land to

timberland in the United States from 1982 to 1997 (U.S.

Department of Agriculture, Forest Service 2001).
Southern Forest Science:

Past, Present, and Future

Biodiversity

352

10 20 30 40

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Stands (million acres) 

Natural regeneration (million acres)

Loblolly pine

Slash pine

Virginia pine

Longleaf pine

Shortleaf pine

yellow pine plantations had been established by

afforestation under Government-assisted and

nonsubsidized programs. Some predict that

an additional 23 million acres of agricultural land

will be afforested by the year 2040 (Wear and

Greis 2002).

Acreages in plantations and natural stands

are listed by species in table 29.2. Loblolly pine

accounts for most plantations, and it is also the

predominant species in natural stands. In contrast,

there are few or no plantations of spruce pine and

Table Mountain pine, and their natural stand area

is small.

There appears to be a relationship between

amount of land supporting a pine species and the

amount of young natural regeneration recorded

for that species (fig. 29.6). It is often overlooked

that pine plantations provide seed trees for

regeneration of adjacent areas. For example,

although the area supporting natural slash pine

stands is about the same as for Virginia pine

(table 29.2), there is much more natural

regeneration of slash pine. This may simply

be due to the existence of about 7 million more

acres of slash pine plantations than Virginia

pine plantations (table 29.2). Establishing pine

plantations on what was previously farmland and

on upland hardwood sites increases the chance

of subsequent natural regeneration of pines.

The use of prescribed fire is more likely

in plantations than in natural stands. During

the 1980s, about 54 percent of the yellow pine

plantations showed evidence that they had been

burned during the past 10 years, while fire effects

were evident in only 35 percent of the natural

pine stands (Rudis and Skinner 1991). Both

Table 29.2—Acres of southern yellow pines in the Eastern United States during the 1990s,

number of Forest Inventory and Analysis survey plots (data generated from Forest Inventory

Mapmaker Version 1.0: run October 15, 2001), and the authors’ predicted decline in natural

stands for the mid-21st centurya

Planted or Predicted

direct- decline of

Natural seeded Natural Survey natural

Species Total stands stands stands plots stands

- - - - - - - - - - - - acres - - - - - - - - - - - - - percent number percent

Spruce 39,416 39,416 — 99 7 10

Table Mountain 92,830 92,830 — 100 28 50

Sand 676,321 238,067 438,254 35 276 30

Pitchb 854,826 826,462 28,364 97 165 50

Pond 916,474 910,732 5,742 99 361 20

Longleaf 2,819,804 2,346,513 473,290 83 864 45

Virginia 3,424,405 3,163,475 260,931 92 920 50

Shortleaf 5,322,636 4,837,941 484,695 91 1,142 50

Slash 10,722,061 3,335,145 7,386,917 31 3,495 25

Loblolly 39,385,704 17,860,361 21,334,218 45 9,680 35

Total 64,254,477 33,650,942 30,412,411 52 16,938 38

a

 The total decline of natural pine stands is based on predictions by Wear and Greis (2002) and Alig and

others (2002).

b Assumes no artificially regenerated stands of pitch pine in New Jersey.

Figure 29.6—The amount of land in pine stands and

amount of natural regeneration (age class 1 to 5 years)

for five southern yellow pines.
353Chapter 29. Natural Southern Yellow Pine Forests

percentages will likely decline as the population

of rural counties increases. Public opinion, risk

of liability, smoke regulation, and residential

developments are important barriers to burning

on private lands in the South (Haines and

others 2001).

REDUCED PINE REGENERATION

When yellow pine stands remain unburned

for about 10 years, hardwoods such as oaks,

hickories, and red maple become abundant

in the understory (Wahlenberg 1960). Where fire

continues to be excluded and no action is taken to

reduce the ingrowth of hardwoods, the basal area

represented by pines declines as that of hardwoods

increases. The area classified as oak-pine (where

pine makes up 25 to 50 percent of the stocking)

increased by 24 percent between 1953 and 1997

(table 29.1). This accounts for an estimated

5.8 million acres of the decline in natural pine.

Approximately 4.5 million acres of pine plantations

now have more than 50 percent of their basal area

in hardwoods (Rosson 1995).

Since 1953, acreage in oak-hickory stands has

increased by almost 20 million acres (table 29.1).

Practices that have caused this include (1) fire

exclusion, (2) high-grading of pine-hardwood

stands, and (3) harvesting of pine stands without

replanting pines or implementing successful

measures to naturally regenerate pine. In spite

of tree planting efforts over the past 44 years,

the acreage in loblolly-shortleaf-longleaf-slash

pine cover types has declined by more than 15

million acres (table 29.1). Although forest

industries plant seedlings to keep their land in

pines, practices used by private nonindustrial

landowners have favored the conversion of pine

stands to hardwoods.

Forest Inventory and Analysis data were used

to determine the distribution of stand-age classes

for natural stands of several southern yellow pines

(fig. 29.7). These data indicate a peak in natural

pine regeneration between 1930 and 1950

(equivalent to age classes 40 to 60). A more recent

peak during the 1980s can be observed for loblolly

pine and slash pine. To some extent it is also

evident for longleaf pine. This recent peak may

be due to the abandonment of pastureland, and to

some extent to the Conservation Reserve Program

(which takes cropland out of production). Some

of the “natural” regeneration may have occurred

on abandoned agricultural fields that were

adjacent to loblolly or slash pine plantations.

During the 1990s, the area in natural yellow

pine was as follows: 2.3 million acres of longleaf

pine, 3.3 million acres of slash pine, 4.6 million

acres of shortleaf pine, and 17.8 million acres of

loblolly pine (table 29.2). Alig and others (2002)

predicted a 38-percent decline for all the southern

pines by the mid-21st century. We took their

prediction and subdivided it by species (table 29.2).

Spruce Pine

Spruce pine is the rarest southern pine

species in terms of total number of trees, total

volume, and number of acres. Since supporting

data are not readily available, we do not know

if the population of spruce pine is increasing or

declining. However, the standing volume of spruce

pine increased from about 464 million cubic feet

in 1963 (Sternitzke and Nelson 1970) to about 587

million cubic feet in 1993. So far, few are concerned

about the reproductive success of this species since

it is classified as very shade tolerant. In addition,

it is highly susceptible to fire and is naturally

adapted to areas where fire is infrequent. A small

decline in natural spruce pine acreage over the

next 50 years could result from development and

from utilization of this species as a less expensive

source of wood for finishing material.

Table Mountain Pine

Many Table Mountain pines on western and

northern exposures have serotinous cones that

open only when exposed to high temperatures.

Fire exclusion will cause continued decline of

this species (Southern Appalachian Man and

the Biosphere 1996). Prescribed burning can

be conducted to encourage natural regeneration,

but only certain types of burns will be effective

(Welch and Waldrop 2001). Although prescribed

burns may be attempted on public lands where

population levels are low, it is doubtful that

prescribed burns will be conducted on private

lands that are close to residential areas. For these

reasons, we believe that this species is the most

threatened of the southern yellow pines. Although

inventory data suggest that there has been an

increase in the numbers of Table Mountain pine

(table 29.3), this difference might be related to

having a small number of sample plots (28) and the

use of sampling methods that do not distinguish

between ingrowth and ongrowth. In the absence

of major wildfires, a 50-percent decline in Table

Mountain pine might occur by 2050.
Southern Forest Science:

Past, Present, and Future

Biodiversity

354

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Loblolly 1.54 Slash 0.90

Longleaf 0.54 Virginia 0.37

Shortleaf 0.30 Pond 0.46

Age class

Pine stands (thousand acres) Pine stands (thousand acres)

Figure 29.7—Acreage of natural even-aged pine stands by species and 5-year age classes.

The number on each graph represents the ratio obtained by dividing the number of acres

in the 0- to 10-year age class by the number of acres in age class 41 to 50 years.
355Chapter 29. Natural Southern Yellow Pine Forests

Sand Pine

In central Florida, there are many even-aged

stands of Ocala sand pine that regenerated

naturally after wildfire. Sand pine was not utilized

or planted much before World War II, but planting

began around 1956 when 8,000 seedlings were

grown at a nursery in Florida (Sampson 1973).

Today, more than 60 percent of the stands of

sand pine are plantations established mainly by

planting. The Choctawhatchee variety occurs in

the panhandle of northwest Florida and is rarely

planted. Recently, some natural pine stands have

been replaced by longleaf pine plantations. Rapid

urbanization of the Florida landscape could result

in a 30-percent decline in natural sand pine

acreage by 2050 (table 29.2).

Pitch Pine

Cones of pitch pine at the north end of its range

tend to be serotinous, while this trait disappears

in the southern end of the range. In 1978, the

National Parks and Recreation Act established

1.1 million acres in New Jersey as the Pinelands

National Preserve. Organizations like The Nature

Conservancy and the New Jersey Conservation

Foundation continue to purchase property within

the borders of the preserve while the Pinelands

Preservation Alliance alerts the public to

developments within the preserve. The New

Jersey Forest Fire Service has the task of

prescribed burning the Pine Barrens. It will be

interesting to learn how effective legislation will

be in slowing development and keeping prescribed

burning as a tool for managing the Pine Barrens.

By 2050, we expect a 50-percent decline in natural

pitch pine as a consequence of development.

Pond Pine

Confined to the lower Coastal Plain from

Virginia to Florida, pond pine is an ecological

enigma. Its serotinous cones and sprouting ability

attests to its dependence on fire for regeneration,

yet it exists in pocosins and swamps. These

traits identify intense fires at long intervals

as the primary regeneration vector. The Pond

Pine Wilderness Area was established in North

Carolina in 1984 and contains 1,685 acres. Because

this area is in an isolated location, development

will have little effect on new regeneration.

However, if intense wildfire is excluded from

this region, a gradual decline could occur over

the next half century.

Longleaf Pine

Natural longleaf pine has excellent wood

properties, and as a result is a preferred species

at many sawmills. Good seed crops are infrequent

and several years may be required before forest

managers achieve successful natural regeneration

of longleaf stands. Even when afforestation is

attempted on former cropland that has no

hardwood competition, success rates are

sometimes less than desired. These factors have

encouraged landowners who harvest longleaf pine

to plant other pine species. As a result, longleaf

pine timberland has declined by 77 percent in just

44 years (table 29.1). A Longleaf Pine Alliance has

been established to slow the rate of decline. Even

though this organization encourages landowners

to manage for longleaf pine, we predict that

natural longleaf pine will continue to decline as

a consequence of fire exclusion and a lack of effort

to obtain adequate natural regeneration. We

predict a 45-percent decline in acreage of natural

stands over the next 50 years (table 29.2).

Virginia Pine

This species was important to the stabilization

of badly eroded fields following agricultural

abandonment after the Great Depression. Today,

many of these naturally regenerated stands are

being replaced by hardwoods. Virginia pine will

continue to decline over the next several decades,

although small groups and individual trees will

become established in disturbed areas. Except

for use as Christmas trees, planting of this species

by landowners is rare. Although there may be over

Table 29.3—Inventory of Table Mountain

pine growing stock by diameter class for

two periods

D.b.h. class About 1977 1989–99

 - - - - - million trees - - - - - -

6 5.6 8.6

8 4.3 5.8

10 2.2 3.7

12 1.4 2.2

14 0.9 1.6

16 0.3 0.4

18 0.08 0.05

20 0.02 0.03

Source: Della-Blanca (1990); 1989–99 data (28

plots) generated from Forest Inventory Mapmaker

Version 1.0: run October 15, 2001.
Southern Forest Science:

Past, Present, and Future

Biodiversity

356

3 million acres of natural stands today, we predict

that fewer than 1.6 million acres will exist by 2050

(table 29.2).

Shortleaf Pine

Shortleaf pine is the most widely naturally

distributed southern yellow pine species. Although

it is valued as a sawtimber tree, it is rarely planted

by forest industry. Also, the planting rate by the

U.S. Department of Agriculture Forest Service in

Arkansas has been reduced since 1985. Shortleaf

pine was often grown at high seedbed densities,

and survival of the smaller seedlings after planting

tended to be lower than that for larger loblolly

pine seedlings. Many areas that supported

shortleaf pine have been replanted with loblolly

pine after timber harvesting. Although there

will continue to be natural regeneration, use

of “soft touch” regeneration techniques, such

as shelterwood and individual tree selection,

will likely result in less natural regeneration

of shortleaf than clearcutting and burning.

The most recent inventories suggest natural

regeneration is about 70 percent less than

previously (fig. 29.7). Although individual trees

will continue to be found throughout its range,

the acreage on which shortleaf pine constitutes

more than half of the basal area will continue to

decline due to replacement of shortleaf by

hardwoods and by loblolly pine plantations.

Slash Pine

Because slash pine has rapid early growth

and good wood quality traits, this species has

been favored by forest industry in Florida and

Georgia, and many plantations can be found

outside of its natural range. Many natural stands

have been harvested for economic reasons and

have been replaced by plantations. Some future

stands will develop from seed on areas adjacent

to plantations. Although these stands will contain

some genes from the genetically improved

plantation, future surveys will likely classify

these as stands showing no signs of artificial

regeneration. While the acreage of natural stands

will continue to decline as a result of development,

hardwood competition, and conversion to

plantations, the rate of decline in acreage of the

more common variety of slash pine might be

among the lowest of the southern pines. This may

be because many new “natural” stands are being

established adjacent to existing plantations.

However, natural stands of slash pine (var. densa)

will likely decline due to housing development

and low levels of natural regeneration.

Loblolly Pine

It is likely that more seedlings of this species

are planted each year than any other tree species

in the World. Loblolly does well on a range of site

conditions, and trials have shown that at age 20

years, it typically produces more biomass on

upland sites in the South than other species

with which it has been compared. Into the

foreseeable future, it will continue to be the most

commonly planted tree in the region. Natural

regeneration of loblolly pine appears to be as

common now as it was during the 1950s (fig. 29.7),

perhaps because loblolly plantations are very

widespread (table 29.2).

HERBICIDES IN PLACE OF FIRE

P

rescribed burning can keep pine ecosystems

viable by suppressing competing hardwoods

and preparing seedbeds. The effects of

herbicides are not identical with the effects

of prescribed fire, but certain herbicides can

sometimes substitute for prescribed burning.

In some cases, both fire and herbicides are used

to manipulate species composition. However,

foresters are burning fewer acres each year

as population pressures (in the form of clean

air regulations, housing developments, and

liability suits) are gradually eliminating fire

as a management tool. About 4.1 million acres

(< 3 percent of our forest land) are prescribed

burned in the South each year (Haines and

others 2001). Although herbicides could be used

to promote natural regeneration of pines, an

increase in urban and rural populations will likely

limit the use of herbicides around homes, near

highways, and even in plantations.

PREDICTIONS

B

etween 1990 and 2000, the population of

Georgia increased by 25 percent. Some predict

the population of the 13 Southern States will

double between 1996 and 2046, with 70 percent of

this increase in urban areas. During this period,

the U.S. population is predicted to increase by 67

percent. As the population increases, land values

and property taxes will increase, placing additional

pressure on pine forests. In some areas annual tax

on forest land exceeds $25 per acre. When taxes

equal or exceed the revenue landowners get

from their natural pine stands, owners will be

encouraged to seek ways to make the land more

economically productive. Taxation can result in

forest fragmentation as forest products companies

sell large tracts for residential development
357Chapter 29. Natural Southern Yellow Pine Forests

(Flick and Newman 1999). After forest land is

transferred to individual private landowners,

many will choose not to establish new forests with

either natural or artificial regeneration methods.

Population pressures over the South will

continue to increase into the foreseeable

future. This will result in an increase in forest

fragmentation (Rudis 1998). The presence of more

houses in forested landscapes will be especially

threatening to pine management strategies.

Some people living in these new homes will

want clean air (no smoke from prescribed burns),

no wildfires, no use of herbicides, and no chipping

of hardwoods. Some will want to establish forest

“preserves,” and succession in these preserves

will favor hardwoods at the expense of natural

pine stands.

Alig and others (1986) reported that natural

pine stands in the South decreased at a rate of

about 1.2 million acres per year between 1977 and

1985. They predict there will be 20 million acres in

natural yellow pine timberland in the South in

2030. This represents a decline of 20 million acres

over a 45-year period (or 450,000 acres per year).

Others predict a decline of 23 million acres by 2030

(fig. 29.1). The rate of decline is not expected to be

as great in the future as it was between 1977 and

1985. Although one computer model suggests the

acreage of natural pines might increase by 45

percent by midcentury (Zhou and others 2003),

this scenario is based on mathematics and not on

the opinions of foresters.

A Longleaf Pine Alliance has been established

to help slow the decline in the acreage of longleaf

pine. However, we believe that Table Mountain

pine is the most threatened of the southern yellow

pines. Professor South predicts a “Table Mountain

Pine Alliance” will be formed in the future.

We do not expect that important causal factors

will change in ways that will favor an increase

in the rate of natural pine regeneration. Except

for loblolly pine and slash pine, the acreage in new

natural pine stands (age class 0 to 10 years) is

< 60 percent of that for age class 41 to 50 years

(fig. 29.7). This ratio is only 30 percent for

shortleaf pine. If these trends continue, there

will be significantly fewer natural stands of

shortleaf pine, longleaf pine, Virginia pine, and

pond pine in the year 2030.

Factors that might contribute to an increase

in natural regeneration of pines include large

wildfires after droughts, an increase in prescribed

burning, an increase in the average rotation age

of natural pine stands, a reduction of tree planting

after logging of natural pine forests, a reduction in

tree planting after wildfires, an increase in the use

of herbicides to favor natural pine regeneration,

and the abandonment of pastureland or cropland.

Pressures from increased urban and rural

populations will discourage the implementation

of most of these factors. As a result, the loss of

natural pine ecosystems will continue at an

alarming rate.

ACKNOWLEDGMENTS

T

he authors wish to thank the U.S. Department of Agriculture Forest Service, Forest

Inventory and Analysis, for use of the

online version of the Forest Inventory

Mapmaker Program.

LITERATURE CITED

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Res. Pap. SE–260. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern Forest

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Alig, R.J.; Mill, J.; Butler, B. 2002. Private timberlands growing

demands, shrinking land base. Journal of Forestry. 100(2):

32–37.

Barlow, S.A.; Munn, I.A.; Cleaves, D.A.; Evans, D.L. 1998.

The effect of urban sprawl on timber harvesting: a look at

two Southern States. Journal of Forestry. 96(12): 10–14.

Boyer, J.N.; South, D.B. 1984. Forest nursery practices in the

South. Southern Journal of Applied Forestry. 8: 67–75.

Della-Bianca, L. 1990. Table Mountain pine. In: Burns,

R.M.; Honkala, B.H., tech. coord. Silvics of North America.

Agric. Handb. 654. Washington, DC: U.S. Department of

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Flick, W.A.; Newman, D.H. 1999. Tax code just fuels sprawl.

Atlanta Journal–Constitution. Dec. 11. http://

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accessed: July 14, 2003].

Haines, T.K.; Busby, R.L.; Cleaves, D.A. 2001. Prescribed

burning in the South: trends, purpose, and barriers.

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Ku, T.T.; Sweeney, J.M.; Shelburne, V.B. 1980. Site and stand

conditions associated with southern pine beetle outbreaks in

Arkansas—a hazard-rating system. Southern Journal of

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Outcalt, K.W.; Sheffield, R.M. 1996. The longleaf pine forest:

trends and current conditions. Resour. Bull. SRS–9.

Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southern Research Station. 23 p.

Pyne, S.J. 1982. Fire in America: a cultural history of wildland

and rural fire. Seattle: University of Washington Press.

654 p.

Rosson, J.F. 1995. Forest plantations in the Midsouth. Res. Pap.

SO–290. New Orleans: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station. 30 p.
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Rudis, V.A. 1998. Regional forest resource assessment in an

ecological framework: the Southern United States. Natural

Areas Journal. 18: 319–332.

Rudis, V.A.; Skinner, T.V. 1991. Fire’s importance in South

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ecological and cultural perspectives: Proceedings of an

international symposium. Gen. Tech. Rep. SE–69. Asheville,

NC: U.S. Department of Agriculture, Forest Service,

Southeastern Forest Experiment Station: 240–251.

Sampson, O.R. 1973. Nursery practices used for sand pine. In:

Brendemuehl, R.H. Sand pine symposium. Gen. Tech. Rep.

SE–2. Asheville, NC: U.S. Department of Agriculture,

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The Southern Appalachian assessment: summary report.

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Agriculture, Forest Service, Southern Region. 118 p.

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wildfire statistics. Washington, DC. 32 p.

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wildfire statistics. Rep. FS–343. Washington, DC. 56 p.

U.S. Department of Agriculture, Forest Service. 1988. The

South’s fourth forest: alternatives for the future. Rep.

FR–24. Washington, DC. 512 p.

U.S. Department of Agriculture, Forest Service. 2001. 2000

RPA assessment of forest and range lands. Rep. FS–687.

Washington, DC. 56 p.

Wahlenberg, W.G. 1960. Loblolly pine. Durham, NC: Duke

University. 603 p.

Wear, D.N.; Abt, R.; Mangold, R. 1998. People, space and

time: factors that will govern forest sustainability. In:

Transactions of the 63rd North American wildlife and

natural resources conference. Washington, DC: Wildlife

Management Institute: 348–361.

Wear, D.N.; Greis, J.G. 2002. The southern forest resource

assessment: summary report. Gen. Tech. Rep. SRS–54.

Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southern Research Station. 103 p. www.srs.fs.fed.us/

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Welch, N.T.; Waldrop, T.A. 2001. Restoring Table Mountain pine

(Pinus pungens Lamb.) communities with prescribed fire: an

overview of current research. Castanea. 66: 42–49.

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190–197.
Climate Change
Southern Forest Science:

Past, Present, and Future

Climate Change

360

Chapter 30.

Overview of Global Climate Change

and Carbon Sequestration .................................................................. 361

Chapter 31. Implications of

Global Climate Change

for Southern Forests: Can We Separate Fact from Fiction?. .... 365

Chapter 32.

Carbon Sequestration

in Loblolly Pine Plantations: Methods, Limitations,

and Research Needs for Estimating Storage Pools. ..................... 373

Chapter 33.

Forest Carbon Trends

in the Southern United States. ............................................................ 383
361

Chapter 30.

Overview of

Global Climate Change

and Carbon Sequestration

T

he potential influence of global climate change

on southern forests is uncertain. Outputs of

climate change models differ considerably

in their projections for precipitation and other

variables that affect forests. Forest responses,

particularly effects on competition among species,

are difficult to assess. Even the responses of

relatively simple ecosystems, such as managed

pine plantations, will be affected by complex

interactions. Large-scale perturbations, such

as rising atmospheric carbon dioxide (CO2

) and

changes in precipitation regimes, will interact

with site-specific factors such as soil nutrition.

Because making global change predictions is

difficult, it may be tempting to ignore the issue

entirely and base management and societal

planning solely on historical climate and forest

responses. However, scientific uncertainty and

difficulties in making predictions of system

responses are not relegated to this issue alone.

Chapters in this book and in the Southern Forest

Resource Assessment (Wear and Greis 2002)

discuss uncertainties connected with biodiversity,

forest productivity, societal demands for forest

values, forecasts of future forest type and extent,

urbanization, and the relative profit margins of

forest vs. agricultural lands. Economic forecasts

are particularly uncertain, as responses depend

not only on regional supply and demand but also

on national and international economic forces

that are in great flux. In all these cases, research

provides tools to assess past, current, and future

system flux so that planning can be based on the

best information available. Such planning ranges

from the small scale, as when a private landowner

considers options for a particular parcel of land, to

larger scales, as when States consider regulation

of forest-dependent water resources. In almost all

cases, science does not provide a definitive answer

to a question; rather, it provides probabilities

for potential directions and magnitudes of change.

In other words, science permits us to assess the

spectrum of risks that may be faced.

Clearly, the smaller the scale of inference, the

greater will be certainty of predictions, and vice

versa. For example, we can have strong confidence

how a particular fertilization treatment may

impact a stand of trees of a given age, species,

and site index, but much less confidence on what

effect such a treatment would have on a larger,

less refined land base. It is likely the largest

uncertainties are associated with issues that

may well have the biggest impact on people

and ecosystems. Consider some of the major

perturbations that have drastically altered the

forest landscape of the South over the past

century. Chestnut blight {Cryphonectria

parasitica (Murrill) Barr [formerly Endothia

parasitica (Murrill) Anderson & Anderson]}

rapidly altered the Appalachian forest structure

and did so with little warning. Large-scale

deforestation [often of longleaf pine (Pinus

palustris Mill.) or hardwood stands] was followed

by intensive agriculture, and in many cases this

was followed by natural reforestation to stands

largely made up of loblolly pine (P. taeda L.).

This “introduction” of loblolly pine led to a

major forest industry that both owned and with

increasing intensity managed forest land and has

provided a market for timber and fiber for private

landowners. Thus, just over a century ago the

forest landscape was one largely dominated by

longleaf pine and hardwoods (including chestnut),

and loblolly pine was a minor component. Now

we have a landscape in which longleaf pine

ecosystems occupy 5 percent of their previous

acreage (Outcalt and Sheffield 1996) and are the

focus of an active restoration effort, a greatly

increased proportion of hardwood stands are early

to midsuccession, and there are large expanses

of pine-hardwood forests and managed pine

plantations where loblolly is the most prevalent

pine. These examples illustrate two important

points. First, southern forest ecosystems can be

incredibly resilient to great perturbation. Second,

the state of our forests has been and continues to

be in rapid flux.

Kurt Johnsen1

1

 Supervisory Plant Physiologist and Project Leader, U.S.

Department of Agriculture Forest Service, Southern Research

Station, Research Triangle Park, NC 27709.
Southern Forest Science:

Past, Present, and Future

Climate Change

362

Global change is predicated due to humaninduced increases in greenhouse gases (chiefly

CO2) in the atmosphere. Current increases in

atmospheric CO2 are well documented and are due

to the combustion of fossil fuel and other human

activities. Atmospheric CO2 concentrations are

currently over 365 parts per million, 35 percent

higher than preindustrial values. They are

increasing at a rate of about 0.5 percent per year

and are predicted to equal or exceed 550 parts per

million by the middle of this century (Wigley and

others 1996). Thus, the first basic cog in the global

change physical machinery is clearly engaged, but

the ramifications for potential consequences are

in the realm of scientifically derived probabilities.

Science, as shown in this book, endeavors to

provide systematic methods for evaluating

current and anticipated ecosystem function and

composition given projected conditions, and to

provide information that can guide ecological,

economic, and social decisions that are made

by landowners, corporations, and governments.

Predictions and discussions of potential global

change have existed in both the scientific and

political arenas. In the chapter, “Implications

of Global Climate Change for Southern Forests:

Can We Separate Fact from Fiction?” by Hermann

Gucinski, Ron Neilson, and Steve McNulty

provide a discussion on discriminating fact from

fiction in this polarized debate. They discuss the

evidence that global change is currently impacting

climate and consider predictions of future climate

scenarios. Their major conclusion is that the

climate is likely to change given historical climate

variation and the possibility that an accelerating

greenhouse effect is in progress.

Interestingly, the major greenhouse gas, CO2

,

is fundamental to photosynthesis and provides

the carbon (C) that constitutes 50 percent of

the dry matter of woody tissue. Increasing CO2

concentration increases photosynthesis, at least

in the short run. Most plants, including trees,

initially grow faster when CO2 concentration is

increased. Until recently, studies on the growth

response of trees were mostly performed using

seedlings and saplings, and with only a handful of

species, loblolly pine being the most extensively

researched (Groninger and others 1999). Recent

work indicates that longer-term growth responses

of loblolly pine to elevated CO2 are largely

dependent on soil nutrient availability (Oren

and others 2001), which also greatly influences

belowground C cycling (Butnor and others 2003).

Besides research on direct responses to elevated

CO2, forest tree biology knowledge gained

through research is being incorporated into

models to predict forest responses to changes

in environment and/or management.

Because they are major constituents of the

landscape, forests can also sequester large

quantities of atmospheric C, thus offsetting

emissions from fossil fuel burning and thus the

rate of increase of CO2

. Again, C sequestration

potential has been most evaluated in loblolly pine.

Forest C sequestration can be characterized as

in situ and ex situ (Johnsen and others 2001). The

former represents C on a forest site in its biomass

and soil. Deforestation, reforestation, growth

rate, and rotation length can impact in situ C

sequestration. Ex situ C sequestration represents

C that remains sequestered in forest products.

Various product types (paper, lumber, etc.) have

various lifespans before their C returns to the

atmosphere via combustion or decomposition.

Forest C sequestration can provide a shortto medium-term offset for atmospheric CO2

emissions, while potential additional C sinks

are filled. Additionally, utilization of woody

biomass for bioenergy production can provide

long-term offsets, as these partly supplant fossil

fuel combustion.

As result of concern about the potential

impacts of global change, international policies

have been established to reduce total C emissions

to a predetermined baseline (Kyoto Protocol)

(Oberthür and Ott 1999). Carbon emissions are

the algebraic sum of total emissions and C

sequestered, again relative to the baseline. Forests

are recognized as one of the important avenues

for biologically sequestering C. Thus, the concept

of C credits has been born. Although the United

States has not signed the Kyoto Treaty, industry

is still interested in working with C emissions

and sequestration as a commodity. In the early

to mid-1990s some companies, particularly energy

companies, established programs to promote

forest C sequestration on private land. They did

this so that they could apply these offsets against

their own plant emissions. Nongovernment

organizations such as The Nature Conservancy

have established large forest C sequestration

programs throughout the world with a major

emphasis on managing for and quantifying C

sequestration. Very recently, a large-scale C

commodity exchange has been established for

the first time in the United States.
363

Large-scale policy (regional, national, global)

requires large-scale analyses. In the chapter,

“Forest Carbon Trends in the Southern United

States,” by Robert A. Mickler, James E. Smith,

and Linda S. Heath provides an analysis of

aboveground C stocks by forest types in the

Southern United States, and the change in

composition and extent of these stocks since

1957. This work is based on Forest Inventory

and Analysis data and a process model. Mickler

and others estimated that approximately 29

percent of the aboveground forest C in the United

States occurs in the South. Their analyses indicate

that aboveground forest C has increased at the

rate of 42 megatons per year from 1957 through

1997. Their analyses also indicate that acreage

in private pineland decreased by 18 percent

from 1957 to 1997. However, C stocks on this

landownership type are estimated to have

decreased by only 2 percent. These estimates

only hint at the tremendous increase in

productivity that has accompanied the continued

development of pine plantation forestry over

recent decades. Pine forestry has continued to

develop and use management tools such as site

preparation, fertilization, weed control, and the

use of genetically improved material, and the

result has been a steady increase in productivity

on managed pinelands.

Thus, managed pinelands represent a major

opportunity for increasing C sequestration in the

South. However, it is clear that any system of C

credits will require simple but reliable methods

for quantifying C sequestration. As the major

industrial forest species in the world, loblolly pine

has been the subject of a large body of research,

research that has steadily advanced to make

possible increased productivity in forest stands.

The same body of research, and the fact that

pine plantations are relatively simple ecosystems,

make loblolly pine plantations a prime target

for the implementation of C credits. In the

chapter, “Carbon Sequestration in Loblolly Pine

Plantations: Methods, Limitations, and Research

Needs for Estimating Storage Pools” by Kurt

Johnsen, Bob Teskey, Lisa Samuelson, John

Butnor, David Sampson, Felipe Sanchez,

Chris Maier, and Steve McKeand detail the

methodologies and tools required to quantify C

on a stand basis, and they identify areas in which

important work is still required to improve and

reduce the cost of quantifying forest C.

LITERATURE CITED

Butnor, J.R.; Johnsen, K.H.; Oren, R.; Katul, G.G. 2003.

Reduction of forest floor respiration by fertilization on both

carbon dioxide-enriched and reference 17-year-old loblolly

pine stands. Global Change Biology. 9: 849–861.

Groninger, J.W.; Johnsen, K.H.; Seiler, J.R. [and others]. 1999.

Elevated carbon dioxide in the atmosphere: what might it

mean for loblolly pine plantation forestry? Journal of

Forestry. 97: 4-10.

Johnsen, K.H.; Wear, D.; Oren, Ram [and others]. 2001. Carbon

sequestration and southern pine forests. Journal of Forestry.

99: 14–21.

Oberthür, S.; Ott, H.E. 1999. The Kyoto Protocol: international

climate policy for the 21st century. Berlin: Springer-Verlag.

359 p.

Oren, R.; Ellsworth, D.S.; Johnsen, K.H. [and others].

2001. Soil fertility limits carbon sequestration by forest

ecosystems in a CO2-enriched atmosphere. Nature. 411:

469–472.

Outcalt, K.W.; Sheffield, R.M. 1996. The longleaf pine forest:

trends and current conditions. Resour. Bull. SRS–9.

Asheville, NC: U.S. Dept. of Agriculture, Forest Service,

Southern Research Station. 23 p.

Wear, David N.; Greis, John G. 2002. Southern forest resource

assessment. Gen. Tech. Rep. SRS–53. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southern

Research Station. 635 p.

Wigley, T.M.L.; Richels, R.; Edmonds, J.A. 1996. Economic and

environmental choices in the stabilization of atmospheric CO2

concentrations. Nature. 379: 240–243.

Chapter 30.

 Overview of Global Climate Change

365

Chapter 31.

Implications of

Global Climate Change

for Southern Forests: Can We Separate Fact from Fiction?

Hermann Gucinski, Ron

Neilson, and Steve McNulty1

Abstract—There is no scientific dispute regarding

the existence of a greenhouse effect. There is

no doubt that water vapor, carbon dioxide (CO2),

and methane concentrations are greenhouse

gases. The data showing increases in CO2 in the

atmosphere are incontrovertible. Uncertainties

arise when the Earth’s biological responses

to climate change are to be quantified. Such

uncertainties can be compounded when the

responses of ecosystems, especially forests,

are to be delineated. Complex interactions

among effects of climate change, disturbance,

competition, invasive species, management

intervention, land use change, and other actions

must be clarified by modeling. Model development

has improved greatly, but evaluation and validation

remain difficult. Model outputs for the South

show a fairly wide range of potential changes

under scenarios developed from different climate

models, suggesting that the assumption of steadystate conditions has little likelihood of occurrence.

This implies that we should rethink management

approaches, design research to include new

ecosystem variables, and seek integrated

ecosystem knowledge on scales heretofore

rarely treated.

INTRODUCTION

T

here is persistent skepticism about the

evidence that greenhouse warming may

be occurring, and this skepticism requires

consideration. This chapter is a semitechnical

discussion of the issues, and is designed to shed

light on the question of climate change without

attempting to present new research information or

make new interpretations of the research findings.

There is no scientific dispute regarding the

existence of a greenhouse effect in planetary

atmospheres such as ours (Raval and Ramanathan

1989). Nor is there any doubt that water vapor,

carbon dioxide (CO2), and methane are greenhouse

gases (Ledley and others 1999). Moreover, the data

showing increases in atmospheric concentration of

CO2 are incontrovertible (Keeling and Whorf 1999,

Keeling and others 1989). Lastly, it is clear that

the rise in atmospheric CO2 is largely attributable

to the burning of fossil fuels (Andres and others

2000, Carbon Dioxide Information Analysis Center

2000). Does this prove that there will be climate

change in the form of global warming? It strongly

suggests a change in the Earth’s energy balance,

but there is no simple yes or no answer to the

question about global warming, because the

variables that affect the outcome are many, and the

interactions between Earth system processes have

not been delineated as fully as one might wish.

It is possible to make probabilistic estimates

of likely outcomes, and these have been made

(Harvey and others 1990, 1997). The Intergovernmental Panel on Climate Change (IPCC)

is thought to be the most authoritative scientific

body that has assembled such estimates. The

acceptance of the IPCC estimates has not been

total. Uncertainties remain, and skepticism

persists. Because these estimates have vast

policy implications, the debate has spilled from

the purely scientific area into the arena of public

1

 Assistant Director (now retired), U.S. Department of

Agriculture Forest Service, Southern Research Station,

Asheville NC 28802; Research Team Leader, Mapped

Atmosphere Plant-Soil System Team, U.S. Department

of Agriculture Forest Service, Pacific Northwest Research

Station, Corvallis, OR 97331; and Research Ecologist

and Project Leader, U.S. Department of Agriculture

Forest Service, Southern Research Station, Raleigh,

NC 27606, respectively.
Southern Forest Science:

Past, Present, and Future

Climate Change

366

debate and governmental policy. The controversy

has led august scientific bodies to make strong

statements regarding the status of climate

change science. In this case a group of National

Science Academies, representing 16 countries,

say the following (excerpted from http://

www.royalsoc.ac.uk/files/statfiles/document138.pdf):

The . . . IPCC represents the consensus

of the international scientific community

on climate change science . . . and we

endorse its method of achieving this

consensus. Despite increasing consensus

on the science . . . doubts have been

expressed . . . . We do not consider such

doubts justified . . . . We support the

IPCC’s conclusion that it is at least 90

percent certain that temperatures will

continue to rise, with average global

surface temperature projected to increase

by between 1.4 and 5.8 o

C above 1990

levels by 2100 . . . . The balance of the

scientific evidence demands effective

steps now to avert damaging changes

to the earth’s climate.

This statement has since been endorsed by

the National Academy of Sciences. Figure 31.1

shows the reconstructed temperature record for

the past millennium and the recent temperature

rise coincident with the era of industrial

development.

CLIMATE CHANGE SKEPTICS

D

espite the growing scientific consensus,

skepticism continues, both in the strictly

technical areas, where it is part of the

scientific process, and also in the arena of policy

development. It is useful to examine the scientific

validity of the claims made by the skeptics. These

claims have appeared in Web sites 2 3 and in a

book by Lomborg (1999) and can be summarized

as follows:

• The present uncertainties in Earth processes

overwhelm any confidence in predictions of

future climate. The uncertainties might include

modeling deficiencies, skewing of temperature

records due to “heat island” effects, or the

swamping of the small increases in CO2

 derived

from fossil fuel compared to the large-scale

exchange of CO2

 between the atmosphere

and the oceans and land

• Factors other than increases in greenhouse

gases are responsible for warming trends;

e.g., Milankovich cycle, changes in the sun’s

energy output

• Radiometric data from satellites and highaltitude devices show no warming

Arguments made on scientific grounds are

testable hypotheses, subject to confirmation or

rejection. We also see arguments made on policy

grounds, or derived from various logical positions,

or, at times, logical fallacies. Examples of the latter

include the use of the fallacy of “condemning the

origin,” e.g., climate change arguments are made

only by “greens” or radical environmentalists;

ergo, the argument must be false, or by

discrediting the process (“the IPCC is a

United Nations body, hence subject to political

conspiracies”). Policy perspectives are not subject

to scientific review, but can be examined in the

light of precedents, and by examining the

assumptions upon which they rest. For example,

the argument has been made that expending

national resources on mitigating potential climate

change is unwise because of present uncertainties.

One can investigate the underlying assumptions

using Bayesian formal decision theory. Thus,

it may be even more likely that the “no regrets”

option, i.e., the avoidance of investments to

mitigate climate change that will prove costly

if no climate change occurs, is not the least

expensive, given the risks. Of course, positions

derived from self-interest, i.e., having a “personal”

stake in the outcome, are not subject to scientific

debate, because they bear no relation to the

scientific process.

Consider the issue of scientific uncertainties.

The IPCC contends that improvements in data

collection and processing, model developments,

process-level understanding, and improved largescale consistency of models with observations

give a confidence level of better than 90 percent

for the statement that 20th-century global

temperature increases are the highest of the

last 1,000 years. Moreover, the likelihood that

temperature increases of the 20th century are

not due to climate variability is now estimated at

the 99 percent level (Houghton and others 2001).

Such convergence of the analysis demands a better

scientific response than simple rejection of the

climate change hypothesis on the grounds of

uncertainty. Hence it is important to distinguish

2

 George C. Marshall Institute. 2002. Homepage.

http://www.marshall.org. [Date accessed unknown].

3

 Heartland Institute. 2002. http://www.heartland.org.

[Date accessed unknown].
367

between scientific debate about the implications

of the remaining uncertainty, and categorical

assertions that uncertainties are large. Moreover,

improvements in process-level understanding have

largely overcome the difficulty of calculating small

differences between large numbers, and signals

can be observed despite the large flux of CO2

between atmosphere, oceans, and the land

(Houghton and others 2001).

Factors other than increasing greenhouse gas

concentrations in the atmosphere are affecting

the total radiative energy reaching the Earth’s

envelope. Some factors work on cyclical scales

far longer than any relevant to the postindustrial

emissions era, while others, such as 11-year

sunspot cycles, are too short to influence climate

change but do confuse the signal (Houghton and

others 1994, Lean and Rind 1996). Hansen (1998)

asserts that the existing record of solar radiance

observation shows variation on the order of 0.1

percent, which translates into a forcing of a few

tenths of watts/m2, whereas the forcing from

CO2 increase over preindustrial levels alone is

about 1.4 watts/m2 (Hansen 1998). The relevant

observation is that secular changes are additive

to the human-caused fossil fuel-derived effects,

and that the total picture needs to be analyzed.

Local anomalies, such as the heat island effect,

have been taken into account in the analysis of

global surface temperature data. For example,

Chapter 31.

 Global Climate Change

Figure 31.1—The reconstructed Earth surface

air temperature record for the past millennium

(http://www.ipcc.ch/present/graphics/

2001syr/ppt/05.16.ppt).
Southern Forest Science:

Past, Present, and Future

Climate Change

368

Hansen and others (2002) point out that observed

warming is greatest at high latitudes, especially

in Northern Canada, Alaska, and parts of the

Antarctic Continent. By comparison, the heatisland effect occurs primarily at middle latitudes

where the greatest numbers of cities are located.

Space-based observations see no stratospheric

warming. This is consistent with thermodynamic

principles, stratospheric cooling due to ozone

depletion, and effects of sulfate aerosols (National

Academy of Sciences 2001) and does not contradict

ground-based observations (Houghton and

others 2001).

The magnitude of uncertainties concerning the

heat island effects and the scale of the corrections

applied do not invalidate the record of recent

rise in global surface temperature, but affect

the absolute magnitude and its standard error.

Similarly, upper air temperature measurements

from balloons and aircraft do not invalidate

present assessments. The argument is advanced

that the greenhouse forcing from CO2

 increases

is negligible compared to the exchange of this

gas in the seasonal uptake and release from plant

photosynthesis and respiration. This argument

ignores both the physics of greenhouse gases

and the principle of superposition. The latter

that says as a first-order approximation the effects

of multiple processes are additive; hence, the

additional atmospheric loading of increasing CO2

will be cumulative regardless of the magnitude of

the annual exchanges.

It is important, therefore, to distinguish

skepticism stemming from bad science

or preconceived conclusion from scientific

skepticism that seeks to ensure the knowledge

derived is complete, accurate, and inclusive

of all the important variables that are driving

the system trajectory. Not all uncertainties have

been eliminated, nor is the potential of unexpected

future results negligible. This is particularly

true when one attempts to map the responses of

terrestrial vegetation to probable external forcing,

and even more so when one wants to examine

effects at local to regional scales.

IMPLICATIONS FOR SOUTHERN FORESTS

What, then, are the implications of global

climate change for the Southern United

States in general, and for its forests

in particular?

The most important inference is that the

continuation of the present climate is no longer

the only tenable scenario. Instead we are faced

with a range of scenarios that may have differing

probabilities attached to them but cannot be

dismissed out of hand. These scenarios arise

principally from two processes. One derives from

the uncertainties regarding future CO2 and other

greenhouse gas emissions, and the other from

differences in the climate models themselves,

which have been evolving to incorporate a greater

number of variables and feedback loops over

time. Models have been built that map potential

vegetation based on climate drivers including

temperature, such as growing degree days

and winter temperature minimums, water

(precipitation and soil moisture holding capacity),

and photosynthetic radiation. These can use the

outputs of general circulation models (GCM)

to drive the vegetation both in equilibrium phase,

i.e., after atmospheric CO2 has doubled and

equilibrium is attained, and in dynamic phase,

mapping the vegetation response to gradually

changing climate (e.g., Bachelet and others

2001, VEMAP members 1995). Building in the

responses of the terrestrial ecosystems via their

biogeochemical cycles is still a developing area

(National Academy of Sciences 2001).

As a result, major GCMs exhibit a range of

possible climate change outcomes, especially at the

regional scale, where the remaining uncertainties

are perhaps greatest. It is instructive to consider

the worst-case scenarios along with the benign or

even desirable outcomes.

A scenario that might pose particular difficulty,

because it might convey a false sense of security,

is one in which climate change would initially

be favorable, i.e., one with initial warming and

steady or increasing precipitation, followed by

the development of unfavorable conditions, i.e.,

continued warming accompanied by increasing

aridity. A hypothesis that may apply for the

Southern United States is the expansion of the

subtropical high-pressure fields, including the

Bermuda High (Bachelet and others 2001, Doherty

and Mearns 1999). Such expansion would shift

portions of the jet stream northward, which might

unfavorably alter the precipitation and water

regime. Southeastern forests would presumably

decline, and catastrophic fire could well be the

change agent for this decline.

For the Southern United States, ramifications

of such scenarios go beyond forest responses, and

include changes in water availability among other

hydrologic effects. One may use the global climate

models to calculate ground-water balance and

river discharge, which together can describe water
369

0.00 – 0.1 

0.11 – 0.25

0.26 – 0.5 

0.51 – 1

1.01 – 1.5

1.51 – 3

3.01 – 5.5

Increasing

stress

availability. Figure 31.2 is a depiction of the water

availability under the scenario of a drier South

onto which population growth rates have been

superimposed. The figure shows water stress

as the ratio of changed availability divided by

changed growth rates. This is only one possible

outcome of several, selected to show a worst-case

situation. There are benign and even promising

scenarios in which forest expansion is a strong

possibility. Unfortunately, there are no reliable

data at this time on the probability of occurrence

for any of these scenarios (see discussion in Smith

and others 2002).

The foregoing implies that our management

strategies with respect to climate change must be

structured to function in the context of uncertainty

and incomplete information. This is not shocking

and not unprecedented; a similar situation exists

with respect to other phenomena, such as market

fluctuations or exposure to risk from hurricanes

and floods. It simply means that decision theory

approaches developed elsewhere may be applied

here and that risk assessment and risk

management approaches apply in this arena as

they do in others (Gucinski and McKelvey 1992).

Risk assessment must address two elements,

the probability of the occurrence of an event, such

as future drought, and significance (or “value” or

“utility” in economics parlance) of the event when

it does occur. For large-scale events with costly or

even catastrophic outcomes, it has been customary

to take a “risk-averse” stance over a “risk-neutral”

one, but even that can be problematic in terms of

required action. The “zero-infinity” paradox, in

which the probability of the occurrence of an event

is vanishingly small, but the consequences simply

catastrophic, such as unprecedented wildfire, or

a massive earthquake in an urban area, requires

preparatory action regardless of likelihood.

What are the implications of potential climate

change for risk management?

The study of disturbance processes, and their

lessening or accentuation by changing climate,

is still relatively young. Wildfire frequency and

intensity is being modeled as a response to the

effects of climate change on forest ecosystems

(Lenihan and others 1998). McNulty (2002)

has described effects of hurricane on southern

forests. Management strategies for resistance

to hurricanes include planting (or encouraged

regeneration) of deeper rooted and salt-tolerant

species, and denser forest stocking (or lower

thinning levels). On the other hand, management

strategies for southern forest response to fire

include removal of understory, planting (or

encouraged regeneration) of species that are

more fire resistant, and lower stocking—or higher

thinning levels. It appears that improved forest

management and better policy is also needed

to improve postfire and posthurricane salvage.

Figure 31.2—Predicted change in water

supply stress defined as the ratio of the

2025 demand and supply divided by the

1990 ratio of demand and supply. Higher

stress is the result of both increasing

demand (population pressure) and the

changed supply (climate driven) (McNulty

and others 2004).

Chapter 31.

 Global Climate Change
Southern Forest Science:

Past, Present, and Future

Climate Change

370

However, increased stocking needed for improved

hurricane resistance increases fuel loads and

is detrimental to fire suppression.

Potential effects of climate change on

opportunistic species, especially invasives,

are being studied, as are fragmentation-related

barriers to plant migration, limits on seed,

disruption of pollinators, and other potential

problems. The better we understand the many

facets of the possible responses to potential

climate change, the better our position to

weigh courses of action that remain open.

We believe that the following may serve as

useful starting points for further exploration of

possible options for mitigating negative climate

change impacts on Southern U.S. forests:

• Manage forests for low-probability climate

scenarios that have large-scale consequences.

In this case, diversity may bring resiliency, and

ultimately sustainability. This strategy may be

especially appropriate for the Southern United

States, where the rotation period for reaching

harvest potential is relatively short

• Weigh the risks of omission against those

of commission. Sometimes the risks

incurred through inaction are greater than

by implementing active approaches early,

especially when these approaches would

be beneficial regardless of the effects of

impending climate change

• Analyze the potential cost of delaying action

in the hope of obtaining better information

when the delay may eliminate viable options.

This is the argument advanced by the National

Academies in endorsing the IPCC findings.

Delaying action until there is greater certainty

about the potential effects of climate change

may have its own costs. Of course, this does

mean that additional information should not

be sought or consulted

• Be aware that risk assessment is influenced

by both objective and subjective elements, and

that consistency in assessment approaches will

improve our chances of meeting our objectives

CONCLUSIONS

A

pproaches in which potential global climate

change is treated as a set of future risks have

often been ignored, and certainly have not

been used adequately to assess possible impacts

in the Southern United States. The existence of

decision-theory frameworks, and their use in other

sectors, makes this a viable option for managers,

who can also benefit from additional research

in the science community. If by improving our

understanding of the risk spectrum now and

applying the insights gained in the planning

process, we may have many more options

in the near term. Future climate change

constraints may limit the choices for climate

change mitigation considerably.

ACKNOWLEDGMENTS

T

he authors are grateful for the assistance

provided by Ms. Jennifer Moore, Dr. Ge

Sun, and Dr. John Bartlett with the analysis

and creation of figure 31.2. We also appreciate the

comments and suggestion of the two anonymous

reviewers for this chapter.

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Smith, T.M.; Karl, T.R.; Reynolds, R.W. 2002. Climate modeling:

how accurate are climate simulations? Science. 296: 483.

VEMAP members. 1995. Vegetation/ecosystem modeling and

analysis project: comparing biogeography and

biogeochemistry models in a continental-scale study of

terrestrial ecosystem responses to climate change and CO2

doubling. Global Biogeochemical Cycles. 9: 407–437.

Chapter 31.

 Global Climate Change

373

Chapter 32.

Carbon Sequestration

in Loblolly Pine Plantations: Methods, Limitations,

and Research Needs for Estimating Storage Pools

Kurt Johnsen, Bob Teskey,

Lisa Samuelson, John Butnor,

David Sampson, Felipe

Sanchez, Chris Maier, and

Steve McKeand1

Abstract—Globally, the species most widely

used for plantation forestry is loblolly pine (Pinus

taeda L.). Because loblolly pine plantations are

so extensive and grow so rapidly, they provide

a great potential for sequestering atmospheric

carbon (C). Because loblolly pine plantations are

relatively simple ecosystems and because such a

great volume of knowledge has been gained about

the species, the quantification of C dynamics of

loblolly pine stands will be relatively easy. Here,

we evaluate the state of science that relates to

quantifying standing C pools in managed loblolly

pine stands. We consider the accuracy and

precision with which aboveground and

belowground pools can be estimated, the

portability of these tools across different stand

types, and the intensity and efficacy of the

measurement techniques. We emphasize

the need to develop standard and relatively

inexpensive measurement protocols.

INTRODUCTION

T

he Southern United States is now the

most intensive and extensively managed

forested area in the World. The tree species

most widely employed in plantation forestry is

loblolly pine (Pinus taeda L.). Because loblolly

pine has great commercial and economic

importance, its culture and management has

been studied in great detail (Schultz 1997).

Although much practical knowledge has

been gained about loblolly pine, the research

has typically been aimed at providing information

needed for commercial wood and fiber production.

Such research has produced growth-and-yield

models, artificial regeneration methodology, stand

amelioration methodology (and especially that

relating to fertilizer use), and information about

forest genetics and tree improvement.

There is growing interest in quantifying the

ability of forest trees to sequester atmospheric

carbon (C). This interest stems from observed

rapid increases in atmospheric carbon dioxide,

an important greenhouse gas, and their potential

for changing the Earth’s climate. Because loblolly

pine plantations are so extensive and grow so

rapidly, they have great potential for sequestering

atmospheric C (Johnsen and others 2001c). And

because loblolly pine plantations are relatively

simple ecosystems and because such a great

volume of knowledge has been gained about

the species, the quantification of C dynamics

of loblolly pine stands will be relatively easy.

The quantification of C pools in loblolly

pine stands is necessary for two main reasons.

One benefit will be in developing and validating

process models (Johnsen and others 2001a, 2001b).

Conventional growth-and-yield models have been

practical tools for managing loblolly pine stands,

both naturally regenerated and plantation, over

the past century. These models are based on

empirical data about past performance and

utilize site index to characterize stand quality

1

 Supervisory Plant Physiologist and Project Leader,

U.S. Department of Agriculture Forest Service, Southern

Research Station, Research Triangle Park, NC 27709;

Professor, University of Georgia, School of Forest Resources,

Athens, GA 30602; Professor, Auburn University, School

of Forestry and Wildlife Sciences, Auburn, AL 36849; Plant

Physiologist, U.S. Department of Agriculture Forest Service,

Southern Research Station, Research Triangle Park, NC 27709;

Mathematical Modeler, Virginia Polytechnic Institute and

State University, Blacksburg, VA 24060; Chemist and Research

Biological Scientist, U.S. Department of Agriculture Forest

Service, Southern Research Station, Research Triangle Park,

NC 27709; and Professor, North Carolina State University,

Department of Forestry, Raleigh, NC 27695; respectively.
Southern Forest Science:

Past, Present, and Future

Climate Change

374

Stems

50%

Coarse roots

5%

Taproots

18%

Fine roots

1%

Foliage

10%

Branches

16%

Stems

37% Taproots and

coarse roots

7%

Fine roots

13%

Foliage

30%

Branches

13%

(A)

(B)

and productive potential. Growth-and-yield models

have been effective because the growth of the

stands they are used for has typically been similar

to the stands growth-and-yield tables were based

on. However, with intensive forest management

increasing, this assumption is no longer valid.

Loblolly pine is being grown at unprecedented

rates (Albaugh and others 1998, Samuelson and

others 2001). Process models, which incorporate

mechanistic information of tree and stand function,

will hopefully provide tools for predicting stand

performance under novel conditions. C, as a basic

and major constituent of cellulose, lignin, starch,

and sugars provides a valuable “currency” for

models to be based on.

Process models are needed for more than

managing stands of pine. Policy and planning

with respect to the uncertainty of future climate

and large-scale land management issues requires

modeling tools that can provide useful forecasts.

These efforts form the basis of the U.S.

Department of Agriculture Forest Service,

Southern Global Change Program. Clearly,

information and tools developed to inventory

stand C and model C dynamics at the managed

pine stand level should be utilized to improve the

performance of larger scale regional, national,

and international modeling efforts.

Quantifying pine stand C pools will also provide

a basis for “carbon credits.” Although no system

of C credits exists yet in the Southern United

States, they are in serious consideration in

Europe. It is clear that if C credits are to become

a practical reality, standardized, dependable,

but relatively simple protocols for quantifying

C pools will be needed to accurately evaluate

C sequestration over time.

In what follows, we evaluate the state of science

that relates to quantifying standing C pools in

managed loblolly pine stands. We consider the

accuracy and precision with which aboveground

and belowground C pools can be estimated, the

degree to which estimation tools are applicable

across different stand types, and the intensity

of the measurement technique. We emphasize

the need to develop standard and relatively

inexpensive measurement protocols.

PARTITIONING CARBON AMONG

TREE ORGANS

A

tree’s total biomass resides within its stem,

branches, leaves, reproductive organs, and

root system. Biomass is allocated differentially

among the aboveground and belowground

components, and the proportions of biomass

in different tissue components change during the

course of stand development. For example, foliage

can constitute up to 50 percent of a seedling’s dry

mass, but this proportion decreases greatly in

older trees (fig. 32.1A). Figure 32.1A shows

standing biomass components of fertilized trees at

the Southeast Tree Research and Education Site

(SETRES) (Albaugh and others 1998). Schultz

(1997) stated that approximately 20 to 25 percent

of standing biomass is present in root systems

of mature trees, consistent with results from

SETRES. In 1995, these stands had been fertilized

for 3 years, and differential allocation among

organs in terms of standing biomass was not

strongly evident. However, figure 32.1B shows

yearly production that indicates a much greater

proportion of new growth allocated to both

foliage and roots; fertilization reduced allocation

to fine roots (data not shown). Both foliage and

fine roots represent ephemeral organs. Thus,

the proportions of standing biomass cannot be

simply considered analogous to partitioning of

total C gain.

Figure 32.1—(A) standing biomass and (B) annual biomass

production for fertilized trees from the Southeast Tree

Research and Education Site located in North Carolina.

The stand was established in 1985 and data are from

1995, 3 years after fertilization commenced.
375

95 percent CI

33.75 – 52.29 kg

95 percent CI

94.02 – 291.33 kg

Baldwin and others 1987

Naidu and others 1998

Van Lear and others 1984

400

350

300

250

200

150

100

50

0

Biomass (kg/tree)

Albaugh and others 1998

Ralston 1973

Samuelson and others, in press

D.b.h. 27.2 cm

Height 21.9 m

Age 32 years

D.b.h. 17.5 cm

Height 14.6 m

Age 18 years

Goebel and Warner 1996

Shelton and others 1984

100

80

60

40

20

0

Standing volume (m3/ha)

C I F IF

Treatment

BIOMASS ESTIMATION

I

n several investigations, aboveground and

belowground organs of trees have been

harvested and the biomass of loblolly pine

stands has been estimated, typically in a plantation

setting. Often, relationships have been developed

between simple metrics [diameter at breast height

(d.b.h.) and height] and biomass components, and

these relationships can be used to estimate site C.

Although these studies can provide simple tools for

estimating C pools, they are largely site, age, and/

or tree size specific. In the following sections, we

discuss the estimation of C for aboveground and

belowground components using formulas available

in the literature and other methods.

Aboveground Standing Carbon

Stems—Figure 32.2 compares stem biomass

estimates from six independently derived

biomass equations at two tree size/age classes

[only Baldwin (1987) uses age as a predictor].

Note that except for Van Lear and others (1984)

and Naidu and others (1998), the larger size class

examined in figure 32.2 represents a tree size

larger than the sample trees examined in the

studies. The larger size class was examined,

though, because it represents a tree size

frequently occurring during a full rotation.

Except for Baldwin (1987), there is reasonable

congruency among the estimates. However,

confidence intervals are still large, and selecting

the right equation to use for any particular site

remains problematic. More such investigations

are needed across a wider range of sites and tree

sizes so that a stronger rationale can be developed

for model selection. On a positive note, two sites

that received extremely intensive management

treatments (Albaugh and others 1998; Samuelson

and others, in press) do not appear as outliers

relative to the other sites that had less

intensive management.

As boards and fiber are mostly contained in the

boles of trees, many growth-and-yield tables for

bole volume are available. For any given site, there

are multiple growth-and-yield models to choose

from. Again, we use SETRES as an example.

Figure 32.3 shows the volume estimates provided

by two growth-and-yield models: one from Goebel

and Warner (1969) and one from Shelton and

others (1984). Under all treatments, the Shelton

and others model predicts approximately 50

percent higher volume than Goebel and Warner.

The Goebel and Warner equation gives wood

volume not total volume, i.e., no bark. The Shelton

and others equation estimates volume outside

bark. These are not trivial differences, especially

for young trees, and probably account for a large

part of the differences in volume estimates.

As with biomass equations, a systematic

and nonsubjective method is needed for choosing

the right growth-and-yield model for application

to a particular stand. This will require a detailed

evaluation and integration of the many models

in the literature, as well as further research,

particularly on intensive forestry systems.

Landowners will need to provide nonsubjective

simple biometrics such as height, d.b.h., and

Chapter 32.

 Carbon Sequestration

Figure 32.2—Stem biomass estimates obtained by

applying six independently derived biomass equations

for two tree size or tree age classes. Confidence

intervals (CI) of 95 percent are shown for each size class.

Figure 32.3—Standing volume estimates, using two

growth-and-yield equations, for 10-year-old loblolly

pine stand trees grown for the last 5 years under four

treatments: control (C), irrigation (I), fertilization (F),

and irrigation plus fertilization (IF). Treatments are

described in Albaugh and others (1988).
Southern Forest Science:

Past, Present, and Future

Climate Change

376

5

4

3

2

1

0

01 2345

Litterfall LAI (m2m-2;one-half total basis)

LI-COR LAI-2000 vegetation area index (m2m-2)

stocking to a decision-support system that will

use the appropriate growth-and-yield table (or

biomass equation) and produce volume estimates.

Volume of stemwood, expressed as m3/ha, is

converted to Mg C/ha in the following way. First,

multiply volume in m3/ha by a value for the specific

gravity of pinewood. Schultz (1997) suggests 0.5 is

a good average to use. Then, because pine biomass

is approximately one-half C, multiply the result by

0.5 to obtain an estimate of stemwood in Mg C/ha.

Zobel and others (1972) and Tauer and LooDinkins (1990) demonstrated increasing specific

gravity with tree age, and decreasing specific

gravity with tree height, respectively, for loblolly

pine. Concentrations of C vary among tree organs,

ranging from 50 percent for branches to 42

percent for fine roots (Sampson and others 2001).

In reality, specific gravity of wood as well as C

concentrations of tree organs may vary with tree

growth rate as influenced by management, and

so both areas require further research and/or

literature review to provide good estimates

for application to a particular stand.

Branches—Branch biomass typically accounts

for 10 to 20 percent of biomass (Shultz 1997).

However, relatively little effort has gone into

predicting stand branch biomass (Baldwin

and others 1997). Branch biomass is strongly

influenced by stand age and site quality (Hepp

and Brister 1982). Again, the equations used

to produce figure 32.2 also provide estimates for

branch biomass, but stocking and productivity

influences limit the portability of these

relationships across sites.

Foliage—After planting, the quantity of

foliage accretes over time until it reaches a

semiplateau. Both the initial growth rate and the

plateau reached are functions of site limitations.

Therefore, in early stages of stand development,

strong relationships are exhibited between metrics

such as d.b.h. and height on the one hand, and leaf

area or mass on the other hand. Once tree canopies

close and a plateau in leaf mass is reached, such

simple relationships may no longer exist. For

larger trees, relationships between sapwood area

and leaf area or mass will probably be more useful

(Mencuccini and Grace 1995).

For midrotation stands like those at SETRES,

the standing biomass of foliage of trees past the

sapling phase is approximately 10 percent of total

stand biomass. However, production of foliage

biomass is much greater and at SETRES is

approximately 30 percent of yearly biomass

production. However, leaves represent the

photosynthetic capital of a tree, and leaf biomass,

or leaf area, is a major determinant of stand

productivity. Leaf area dynamics are critically

important in loblolly pine because the species

maintains each cohort of leaves for two growing

seasons so peak leaf area in late summer is

approximately twice that in midwinter leaf area.

Thus leaves are an important component of stand

biomass, and yearly leaf area dynamics must be

understood and modeled properly if stand

productivity is to be modeled satisfactorily.

Leaf biomass can be determined from

estimates of leaf area index (LAI), and vice

versa, if estimates for specific leaf area (g/m2

)

are also available. There are three common

approaches to estimating leaf biomass and LAI.

These include destructive biomass harvesting,

litterfall techniques, and “instantaneous”

techniques that employ measures of relative

light flux density. Destructive harvesting is

expensive and time consuming, and produces

results that may be site-specific. Estimating LAI

from littertrap data requires a waiting period, the

length of which depends on both the number and

longevity of individual annual foliage cohorts.

Instantaneous methods, such as using the

LI-COR LAI-2000 Plant Canopy Analyzer

(PCA), are rapid and much less expensive, and

permit estimation of seasonal patterns in LAI

when LAI varies monthly. However, the PCA

underestimates LAI by 10 to 30 percent in pine

stands (Sampson and Allen 1994), and corrections

as shown in figure 32.4 are required. Estimation of

Figure 32.4—Relationship between litterfall, estimated leaf area

index (LAI), and nondestructive measures using a LI-COR LAI2000 from the Southeast Tree Research and Education Site.
377

seasonal foliage biomass or LAI using PCA

will still require sequential measurements over

time. In an attempt to minimize the sampling

frequency, Sampson and others (in press)

developed equations for estimating seasonal

LAI from a single measurement. While this work

utilized plots that varied greatly in productivity

and stand structure, the general applicability of

such an approach still needs to be tested.

Belowground Standing Carbon

Roots—Taproots represent an important sink

of C; intensive destructive sampling at SETRES

showed that they constituted 15 to 18 percent of

total tree biomass. Taproot excavation is extremely

labor intensive. Heavy machinery can be utilized,

but losses due to ripping and imprecision in the

volume of soil sampled increase sampling error

considerably. In the future, it will be necessary

to develop inventories of stand taproot C on the

basis of relationships between taproot C and

simple measures such as d.b.h. and height, which

will also be used to estimate aboveground biomass.

Taproot morphology can vary tremendously within

a stand. The four taproots shown in figure 32.5

came from trees on the same site in South Carolina

and range from a single carrot-shaped root to a

complex series of large sink roots stemming from

a buttressed stem. Thus estimating total coarse

root biomass removes the subjectivity involved in

deciding exactly what constitutes the taproot.

Figure 32.5—

Taproots excavated

from a 20-year-old

plantation in South

Carolina, showing

the variation in root

morphology. Photos

by Lance Kress.

Chapter 32.

 Carbon Sequestration
Southern Forest Science:

Past, Present, and Future

Climate Change

378

60

50

40

30

20

10

0

0 50 100 150 200 250

Total aboveground biomass (mg/ha)

Coarse root biomass (mg/ha)

SETRES, NC 8 years

SETRES, NC 10 years

Bainbridge, GA 6 years

r2 = 0.98

Williamsburg Co., SC 20 years

Duke Forest, NC 14 years

Clemson, SC 41 years

Figure 32.6 illustrates the relationship between

coarse root biomass and total aboveground

biomass for combinations of site and stand age.

The figure shows total coarse root biomass

because of the morphological differences discussed

above. Log-log regression analyses of the data

in figure 32.6 indicate that the allometric constant

is approximately 0.20, which means that the ratio

of coarse root biomass to aboveground biomass

declines with stand development. Therefore,

simple coarse root biomass:aboveground biomass

ratios will not suffice. Note that these sites

represent a large range in soil permeability (deep

sand, clay, and loam), and so the fact that one

relationship holds between coarse root biomass

and aboveground biomass for all these sites is

surprising. Relationships will likely have to be

constructed for different site types. For example,

a water table that is high or fluctuating or both

may well reduce vertical taproot development.

Depending on soil and moisture conditions,

taproots can penetrate below 3 m. Thus taproots

reside in an environment that is not as conducive

to rapid decomposition as finer root components

and may be important in sequestering C

belowground. Ludovici and others (2002) examined

in situ decomposition of loblolly pine taproots

grown on a Piedmont site across a 60-year

chronosequence. Ten years following cutting,

approximately 45 percent of taproot biomass

persisted, and a small fraction was still recoverable

after 60 years. These trees were of a size and

age well beyond typical loblolly management

standards for many areas of the South, and so

taproot decomposition of more typical stands still

needs to be assessed.

The characterization of nontaproots into size

classes is subjective. Often, fine roots are defined

as being < 2 mm in diameter. As with leaves, fine

roots represent an ephemeral tissue type. Thus

the contribution of fine roots to total standing

biomass can be low (fig. 32.1A). However, the

contribution of fine roots to yearly production can

be high (fig. 32.1B). Fine root production and

biomass are affected by environmental conditions.

For example, fertilization can greatly reduce fine

root biomass production. Fine root biomass is

often estimated by means of soil coring, which

often requires high sample sizes as within-plot

special variation can be extremely high. Highintensity root core sampling at a 20-year-old

loblolly pine experiment in South Carolina

demonstrated the great variation in root biomass

and showed that the variation increases with

profile depth as fine roots become scarcer

(table 32.1A).

However, fine roots are much more

homogeneously distributed than are coarser roots.

Coarse root estimates derived via soil coring may

in fact have little value in themselves. We have

recently begun using an “air knife” that displaces

soil by means of compressed air. Root systems can

be excavated in a chosen area to a chosen depth

around a sample tree; roots over 2 mm in diameter

are left intact. This method appears to be superior

to coring for estimating coarse root biomass.

As the sample size requirements in table 32.1A

indicate, making precise estimates of root biomass

is extremely difficult. Alternative methodologies

need to be devised. Recently Butnor and others

(2001, 2003) have explored the use of ground

penetrating radar (GPR) to estimate root biomass.

Because it provides an integrated measure,

variability is actually lower in GPR estimates than

in estimates obtained by coring. The use of GPR

still requires that some coring be done so that

GPR images can be calibrated. However, in 4

hours, the equivalent of over 2,000 cores’ worth

of data can be collected using GPR, so sampling

intensity can be increased greatly. Although

GPR has shown promise on coarse-textured soils,

much more work needs to be done so that it can

Figure 32.6—Relationship between aboveground biomass and

coarse root biomass across sites. Note: All estimates are via

biomass sampling except those for the Williamsburg site,

where stem volumes were estimated using a volume equation

and converted to carbon values as described in text and value

was adjusted to add branch and leaf carbon using Baldwin and

others (1997). Southeast Tree Research and Education Site

(SETRES) estimates are via Albaugh and others (1998);

Bainbridge, GA, from Samuelson and others (in press);

Williamsburg, Co., SC; Duke Forest, NC, from Ralston (1973);

and Clemson, SC, from Van Lear and others (1984, 1995).
379

5

4

3

2

1

0

0 1 5 10

Year

Soil C (percent)

 0 – 10

10 – 20

20 – 30

Centimeters

be applied across more soil types. However, both

antennae optimization and rapid improvements

in data processing make it likely that GPR will

provide a very powerful and useful tool for

estimating root biomass.

Soil Carbon—Soil C often is the largest

component of a stand’s total C stock. Soil C is

typically sampled by coring, often in combination

with root sampling. As with roots, soil C

decreases with depth (table 32.1). Soil C is more

homogeneous than root biomass, however, and this

is reflected in the lower coefficients of variation

and sample size requirements for soil C (table

32.1). However, sampling intensity needs to be

high, and sampling therefore can be very costly.

If one is to take cores for soil C analyses, one

must decide whether to core by horizon or by

standard depths. Coring by horizon is more

difficult as it requires locating the horizon depths

for each sample, but it can reduce variation among

samples and thus decrease sample sizes. Coring by

depth is more rapid, but as soil profiles will often

change within a depth increment, variation among

samples will be higher. The tradeoffs between the

two protocols need to be established before one

chooses a sampling scheme.

If large cores with a known soil volume are

used, then data can simply be scaled to the stand

level volumetrically. Where small soil augers are

used, soil bulk density must be assessed so that

soil C data can be scaled up. Although soil C

concentrations typically decrease with depth, soil

bulk density increases also, and so values of both

characteristics must be determined to properly

scale the data to the stand level.

In managed stands, soil C can display large

temporal variation. After clearcutting, root

biomass soon becomes necromass and decomposes

over time, resulting in a large temporary increase

in soil C. This phenomenon is clearly shown

in figure 32.7, which displays soil C results of a

long-term site productivity study in the Croatan

National Forest in North Carolina. During year

zero, the old stand was cut and replanted. After

only 1 year, soil C increased, probably as a result

of the decomposition of the least recalcitrant

fine roots from the harvested stand. By year five,

soil C peaked as larger root classes decomposed.

By year ten, the strong pulse of organic matter

was largely lost due to soil respiration. However,

soil C concentrations were still higher than at year

zero. If C sequestered in the soil is to be quantified

properly, these fluctuations over time must be

taken into account. Although the soil C pulse is

ephemeral, it still results in a net exclusion of

C from the atmosphere.

Again, the variability among soil C

measurements is large and indicates that new

methodologies must be devised. Currently

workers are exploring the possibility of using

advanced Raman/SERS fiberoptic-based devices

(Wullschleger and others 2001), Laser-Induced

Breakdown Spectroscopy (Ebinger and

Figure 32.7—Percent soil carbon (C), by soil profile depth,

over time, for stands from the long-term site productivity

experiment located in the Croatan National Forest in

coastal North Carolina. The previous stand was harvested

and the new stand planted in year zero.

Chapter 32.

 Carbon Sequestration

Table 32.1—Site mean, mean square error, and

estimated sample size needed, by soil profile

depth, to detect 10-percent differences between

treatment means for root biomass (A) and percent

soil carbon (B)a

Depth Mean root mass MSE Sample size

cm g/core 10% difference

A

0–20 16.88 15.91 679

20–40 0.62 1.85 7,296

40–60 0.57 1.18 3,336

Mean % carbon

B

0–20 2.09 0.96 176

20–40 0.28 0.28 167

40–60 0.24 0.24 276

MSE = mean square error.

a

 Data is from a sample of 240 10-cm diameter soil cores

collected from a 20-year-old North Carolina State Forest

Nutrition Cooperative Regionwide 7 trial in Williamsburg Co., SC.
Southern Forest Science:

Past, Present, and Future

Climate Change

380

others 2001), and inelastic neutron scattering

(Wielopolski and others 2000) to analyze

and characterize C concentration in soil.

CONCLUSIONS

C

learly land will rarely if ever be managed

solely for sequestering atmospheric C.

However, C sequestration can provide a

cobenefit, and the possibility of receiving income

provided for C credits would often affect land

management decisions about management

intensity and rotation length.

Obviously sampling, site, and temporal variation

is associated with measuring each of the stand

components discussed above. We have indicated

where we think further research is needed both

to improve the precision of estimates and to make

estimation easier. Increased collaboration among

researchers in the Southern United States will

produce great gains.

True quantification of C sequestered by

managed forests will require assessing the

temporal variation of the various C pools,

integrating each curve, summing the integrated

values, and then dividing the sum by rotation

length. Models can be developed so that integrated

values can be estimated from measurements made

at critical times in a plantation’s development.

Alternatively, landowners could be credited for

C on a site each year, relative to some standard

base level. However, in the latter method, C

deficits following stand harvesting and planting

would require that a landowner actually pay for

negative C credits until accreted C again reaches

the baseline C level. This manner of executing

C credits would obviously be extremely difficult

and expensive.

We envision at least two tiers of precision

in estimates of standing C for the purposes of

documentation for C credits. At the coarser level,

the landowner might provide only basic stand

information such as d.b.h., height, and stocking.

All conversion factors, as well as soil C values,

would then be obtained from the literature and

might be stratified to provide different estimates

for different regions, soil types, and management

intensity. This level of precision would likely be

suitable for most small private landowners.

At finer and more precise levels, the landowner

would provide more specific stand data. These

could include direct estimates of soil C, root

biomass, specific gravity, C concentration of tree

tissue, and leaf area. These levels of precision

would more likely be used by forest industries,

and especially those with strong internal research

programs or cooperative research programs

with agencies and universities.

The value of C credits would then likely

increase as the direct inputs into estimates

increase. The financial gain made by providing

more direct information for stands will determine

the willingness of landowners to collect and

provide more data. It is possible that consulting

companies will proliferate. These consultants

would be geared up to use state-of-the-art tools,

and would incorporate field data into state-of-theart models to provide C sequestration estimates.

In any case, all estimates provided for C credit

documentation will need to be certified

for authenticity.

ACKNOWLEDGMENTS

T

he research that yielded the data reported

in this chapter was funded by the U.S.

Department of Agriculture Forest Service,

Southern Research Station; International Paper;

MeadeWestvaco; the North Carolina State Forest

Nutrition Cooperative; the University of Georgia;

and the National Council for Air and Stream

Improvement, Inc. Our thanks to two anonymous

reviewers who pointed out deficiencies in the

original manuscript; their suggestions are

greatly appreciated.

LITERATURE CITED

Albaugh, T.J.; Allen, H.L.; Dougherty, P.M. [and others]. 1998.

Leaf area and above- and belowground responses of loblolly

pine to nutrient and water additions. Forest Science. 44:

1–12.

Baldwin, V.C. 1987. Green and dry-weight equations for aboveground components of planted loblolly pine trees in the west

gulf region. Southern Journal of Applied Forestry. 11:

212–218.

Baldwin, V.C.; Peterson, K.D., Jr.; Burkhart, H.E. [and others].

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Chapter 32.

 Carbon Sequestration

383

Chapter 33.

Forest Carbon Trends

in the Southern United States

Robert A. Mickler, James E.

Smith, and Linda S. Heath1

Abstract—Forest, agricultural, rangeland,

wetland, and urban landscapes have different

rates of carbon (C) sequestration and total

C sequestration potential under alternative

management options. Future changes in

the proportion and spatial distribution of

land use could increase or decrease the

capacity of areas to sequester C in terrestrial

ecosystems. As the ecosystems within a

landscape change as a result of natural or

anthropogenic processes, they may go from

being C sinks to being C sources or vice versa.

We used periodic forest inventory data from

the U.S. Department of Agriculture Forest

Service’s Forest Inventory and Analysis Program

and Landsat Thematic Mapper data to obtain

estimates of forest area and type. A simulation

model for estimating and predicting C budgets

(FORCARB) and a physiologically based

forest productivity model (PnET) were used

to generate estimates of historic, current,

and future C storage for southeastern forests.

INTRODUCTION

I

f the United States is to meet the challenge

of future carbon dioxide (CO2) emission and

sequestration goals, the Southeastern region

will play a critical role in increasing carbon (C)

sequestration potential through conversion of

nonforest land to forest land and through the

management of forest lands. Terrestrial C fluxes

caused by changes in land use and landcover must

be quantified so that C sources and sinks in the

United States can be identified. International

treaties on greenhouse gas reduction require that

current C emissions and sequestration potential of

forest lands be determined so that baselines can be

established for current and future forest C stocks.

Changes due to afforestation (establishment

of forest on land that is not now in forest use),

deforestation (conversion of forest land to

nonforest use), and reforestation (regeneration

of forest after clearcut or significant partial-cut

harvesting) are being used to derive estimates

of forest C stocks for an historical baseline

and future projections. Additional gains in C

sequestration may be realized by increasing

photosynthetic C fixation by plants, reducing

decomposition of soil organic matter, reversing

land use changes that contribute to global

emissions, and creating energy offsets through

the use of trees in urban environments.

The Southeastern United States can play an

important role in a national program for reducing

greenhouse gas emissions. The conversion of

nonforest land to forest land results in an increase

in aboveground and belowground sequestered

C. The present-day conversion of abandoned

farmlands to naturally regenerated forests and

commercial forest plantations is contributing

to an increase in the region’s terrestrial C sink.

In this chapter, we present historic, current,

and future projections of forest C as simulated

by an empirical simulation model used to

estimate and predict C budgets (FORCARB)

and a physiologically based forest productivity

model (PnET).

1

 Assistant Technical Director, Mantech Environmental

Technology, Inc., Research Triangle Park, NC 27709; and

Research Plant Physiologist and Research Forester, U.S.

Department of Agriculture Forest Service, Northern

Global Change Program, Durham, NH 03824, respectively.
Southern Forest Science:

Past, Present, and Future

Climate Change

384

MODELING HISTORIC AND CURRENT

ESTIMATES OF FOREST CARBON

E

cosystem C pools for the aboveground portion

of southern forest ecosystems were estimated

using an inventory and modeling approach.

Similar approaches have been employed by

Plantinga and Birdsey (1993), Heath and Birdsey

(1993), Birdsey and Heath (1995), Turner and

others (1995), Intergovernmental Panel on Climate

Change (1997), and Houghton and others (1999).

Forest inventory data were obtained from the

U.S. Department of Agriculture Forest Service

(Forest Service), Forest Inventory and Analysis

Program (FIA) (Miles and others 2001, Smith and

others 2001). One can estimate regional C stocks

by multiplying forest area by C per unit area.

If a second survey is conducted at a later time,

then the rate of change in the C stocks can be

calculated as the change in C mass divided by

the time between inventories in years. Traditional

forest inventories provide the data required for

calculating C mass. Approximately 50 percent

of live tree biomass, or dry weight, is C.

Since the early 1950s, forests in the United

States have been surveyed periodically on a

Statewide basis. The inventories have been

conducted more intensively on the more

productive forest land known as timberland.

Timberland is defined as land capable of

producing in excess of 20 cubic feet per acre

per year of industrial wood products and not

designated as reserved. Approximately 94

percent of southern forests are timberlands.

Significant areas of less productive or reserved

forest lands that have not been inventoried in

the past exist in Texas, Oklahoma, and Florida.

FIA surveys were designed for estimating forest

area and merchantable timber volume. Tree

volume can be converted to C mass by means

of basic models or conversion factors. C in

other forest components can be estimated

similarly on the basis of forest attributes.

Forest C is often assessed separately for a

number of pools. For the purposes of this

chapter, we partition the forest into five

components: (1) aboveground live trees,

(2) aboveground standing dead trees, (3) down

dead wood (including stumps), (4) understory

vegetation, and (5) the forest floor. We focus

on aboveground pools in this chapter because

of the uncertainty in belowground C estimates,

and because there are accounting difficulties

relating to the transfer of large blocks of soil C

as a consequence of land use change (Heath

and others 2003).

Another important aspect of forest C budgets

in the United States is the fate of C in harvested

wood. The categories used to describe harvested

wood products in C budgets are (1) C in wood

products in use, (2) C in landfills, (3) C emissions

from wood burned to produce energy, and (4) C

emissions from wood either decaying or burned

without producing energy. Release of C emissions

may result from burning of wood for energy at

the mill, from other burning of fuel wood, or from

burning of biofuels made from wood. The sum

of the four categories of wood products is equal

to the total amount of C harvested. Estimates

of C in harvested wood products are based on

national estimates from Skog and Nicholson

(1998), partitioned by State on the basis of the

ratio of statewide removals to national removals

(Smith and others 2001).

Forest Carbon Estimates from

Past Inventories

Forest inventory data are available for the last

half of the 20th century. The data were compiled

for years 1953, 1963, 1977, 1987, 1992, and 1997.

The Forest Service has a detailed plot-level

database for the forest inventory data compiled

for the years 1987, 1992, and 1997. For the other

years, only forest statistics aggregated across the

landscape are available (Smith and others 2001).

Our estimates of historical tree C mass are

based on (1) generalized tree biomass equations

(Jenkins and others 2003); (2) tables of volume

distributed among diameter classes and forest

areas (Smith and others 2001) aggregated across

the landscape; (3) effects of ownership and forest

type on C content from the databases associated

with the 1987 and 1997 U.S. forest statistics

(Smith and others 2001, Waddell and others

1989); and (4) the equations of Smith and others

(2003). C density of forest growing stock was

estimated from average tree volumes, diameter

distributions, and biomass equations. Estimates

of C in nongrowing stock and standing dead trees

were based on similar relationships and data in

the detailed 1987 and 1997 databases. The other

nonstanding-tree C pools were estimated based

on relationships for live-tree C pools from the

1987 and 1997 data, and on forest floor equations

in Smith and Heath (2002), and understory

vegetation information in Birdsey (1992, 1996).
385Chapter 33. Forest Carbon Trends

MODELING CURRENT AND FUTURE

ESTIMATES OF FOREST CARBON

T

he physical and chemical environments of

forest ecosystems are changing at rates

unprecedented in recent geologic time. The

Mauna Loa record shows a 16.9-percent increase

in the mean annual concentration of atmospheric

CO2 from 315.98 parts per million by volume

(ppmv) of dry air in 1959 to 369.40 ppmv in 2000.

The 2.87-ppmv increase in CO2 concentration in

1997–98 is the largest single yearly increase since

the Mauna Loa record began in 1958 (http://

cdiac.esd.ornl.gov/ndps/ndp001.html). If emissions

continue to increase at this rate and there are

no measures taken to slow the growth of CO2

concentrations, a doubling of atmospheric CO2

is possible by 2100 (Houghton and others 1996).

In addition to elevated atmospheric CO2, climate

change resulting from the production or use of

greenhouse gases and sulfate aerosols has

increased over the last century. Air temperatures

have increased on average by 1 °F across the

United States during this period. In the Hadley

model scenario, the Eastern United States

has temperature increases of 3 to 5 °F by

2100, with larger increases for other regions

(National Assessment Synthesis Team 2000).

The physiological responses of southern forest

ecosystems to elevated CO2 and climate change

have been the subject of hundreds of publications.

A detailed review of the literature on this topic

for southern forests is presented in Mickler

and Fox (1997).

In this section, we present the responses of

southeastern forest to elevated CO2 and climate

change. The objective of the research described

here is to utilize remotely sensed forest cover

data linked to a productivity model to determine,

evaluate, project, and map forest productivity in

the Southeastern United States from the present

to 2100. We hope eventually to integrate existing

climate, soil, and remotely sensed landcover

data, and the Hadley2Sul climate scenario for

the Southeastern United States as input to forest

process models to predict, validate, and project

forest growth and forest biomass. This section will

describe methods for linking Landsat Thematic

Mapper (TM) landcover information and a PnET

to estimate and display forest productivity.

Remotely Sensed Forest Classification

Forest cover mapping using spaceborne sensors

has been a goal of forest managers since the

launch of Landsat-1 in 1972. The enhanced spatial,

spectral, and radiometric resolution available with

the launch of Landsat-4 and subsequent Landsat

satellites has improved the application of the TM

sensor for discerning forest cover classification at

Anderson Level II and III classification precisions

at a pixel spatial resolution of 30 m. One of the

projects sponsored by the Multi-Resolution

Land Characteristics (MRLC) Consortium was

production of landcover data for the conterminous

United States. Landcover was mapped using

general landcover classes. For example, forest

is classified as deciduous, evergreen, mixed, and

woody wetlands. Landcover classification was

based on MRLC’s Landsat-5 TM satellite data

archive and a host of ancillary sources.

The Landsat TM data used for this project

were preprocessed following the procedures

described by MRLC for the National Land Cover

Data (NLCD) set. The NLCD-selected TM scenes

consist of data acquired between 1990 and 1994.

Image processing for the NLCD set is described

by Vogelmann and others (1998, 2001). Spectral

information from leaf-on and leaf-off datasets

was used to derive the landcover classification

products. First-order classification products

were developed using predominantly the leaf-off

mosaics as a baseline and refined with the spectral

data from the other season and ancillary spatial

information. Further refinements in the

classification were made using decision trees

and visual inspection. Landsat TM and ancillary

data in the NLCD set were acquired for the

13 Southeastern States from MRLC (http://

www.epa.gov/mrlc/nlcd.html). Individual State

flat landcover files were imported into ERDAS

IMAGINE®. Image data were projected to Albers

projection, NAD83 datum, GRS1980 spheroid, and

units of meters. Individual State images were used

to produce one regional mosaic image. Forest area

was displayed and summarized for three NLCD

landcover classes: (1) deciduous forest (class 41),

(2) evergreen forest (class 42), and (3) mixed

forest (class 43). The deciduous forest class was

supplemented with the woody wetland class (class

91) to create a reclassified deciduous forest class.

The accuracy of the landcover classification has

been described by Yang and others (2001).
Southern Forest Science:

Past, Present, and Future

Climate Change

386

Land Use Change

Forest land and agricultural land account for 90

percent of the South’s total land use. Historically

conversion of forest land to agricultural use, and

vice versa, has been driven primarily by changes

in economic conditions (Adams and others 1996).

Smith and others (2001), who analyzed Forest

Service FIA survey data, reported that total forest

in the South decreased from 91 471 000 ha in 1953

to 86 646 000 ha in 1997, a 5.3-percent decline.

Murray and others (2001), who examined Natural

Resources Inventory survey data, determined that

the forest area of the region declined by 687 981

ha, or 1.1 percent, between 1982 and 1997. They

then assessed the future effects of global climate

change on forest and agricultural rents. Climate

projections using the Hadley base scenario with

a 2 °F (1 °C) and 4 °F (2 °C) warming combined

with a 20-percent reduction in precipitation

were applied to a model of land allocation for

the Southeastern U.S. forest area decline

by ~4 000 000 ha [2 °F (1 °C) warming] and

~8 000 000 ha [4 °F (2 °C) warming] by 2040.

Given the uncertainty associated with any

projection of change in forest area under global

climate scenarios and the historical trend for the

last 50 years showing only a slight decrease in

forest area in the region, the present study is

based on the assumption that forest area will

remain constant to 2100. We report the effects of

climate change on the future productivity of the

region’s forests with the knowledge that changes

in forest and agricultural returns may change

forest area in the future.

Forest Productivity Modeling

We utilized the physiologically based, monthly

time-step process model PnET to predict forest

productivity and hydrology across a range of

climates and site conditions. PnET predictions

of forest productivity have been correlated with

average annual growth in site basal area measured

across the Eastern United States (Aber and

Federer 1992), and predictions of forest biomass

from PnET have been correlated with average

annual growth in basal area measured at sites

across the Southeastern United States (McNulty

and others 1998). Forest biomass predictions

for 2000, 2050, and 2100 were estimated using a

decadal mean of net primary production (NPP)

from the PnET model. Input data required by

PnET include monthly climate parameters, soil

water-holding capacity (WHC), and speciesor forest-type specific vegetation parameters.

PnET output is dependent on the spatial

resolution of input data and includes forest

growth, evapotranspiration, drainage, and soil

water stress over time.

Monthly climate variables required by PnET

include minimum and maximum air temperature,

total precipitation, and solar radiation. The

Vegetation/Ecosystem Modeling and Analysis

Project (VEMAP) provides these variables for

the period 1895–1993 across the continental United

States at a 0.5° by 0.5°resolution (Kittel and others

1997) (http://www.cgd.ucar.edu/vemap/

datasets.html). VEMAP also provides transient

climate scenarios that include the same monthly

climate variables for 1994–2100, based on general

circulation models developed at the Hadley Centre

and the Canadian Climate Centre (http://www.metoffice.gov.uk/research/hadleycentre/index.html).

These climate scenarios, Had2CMSul and CGC1,

include temperature and precipitation effects

related to increasing atmospheric CO2 and sulfate

aerosols. These datasets have been used to

compare time-dependent ecological responses

of biogeochemical and coupled biogeochemicalbiogeographical models to historical time series

and projected scenarios of climate, atmospheric

CO2, and nitrogen deposition. This dataset has the

finest spatial resolution available with this level of

temporal and spatial consistency, and hence, other

input data are modified to match the 0.5° by 0.5°

resolution for the model.

Soil WHC is derived from the CONUS-Soil

dataset, which was developed by the Pennsylvania

State University Earth System Science Center.

The State Soil Geographic Data Base (STATSGO)

Program was developed by the U.S. Department

of Agriculture, Natural Resources Conservation

Service to store and distribute soil survey

information for U.S. lands. STATSGO maps were

compiled from more detailed soil survey maps

and present soil associations at a scale (1:250,000)

more appropriate for regional analysis. Soil WHC

information derived from the CONUS-Soil dataset

(Miller and White 1998) was adapted to the 0.5° by

0.5°grid by area-weighted averaging of the

CONUS soil series WHC polygons.

PnET vegetation variables include foliar

nitrogen concentration, light extinction coefficient,

and other physiological coefficients or constants

derived from field measurements and published

literature (Aber and Federer 1992). Based on the

climate, soil, and vegetation input data, PnET
387

calculates the maximum amount of foliage or

leaf area that can be supported. NPP equals

total gross photosynthesis minus growth and

maintenance respiration for leaves, wood, and

roots. Respiration is calculated as a function

of the current and previous month’s minimum

and maximum air temperatures. Changes

in water availability and plant water demand

place limitations on leaf area produced; as vapor

pressure deficit and air temperature increase

above optimal photosynthetic levels, total leaf

area decreases. Reduced leaf area decreases

total C fixation and alters ecosystem hydrology.

Transpiration is calculated from a maximum

potential transpiration modified by plant water

demand that is a function of gross photosynthesis

and water use efficiency. Interception loss is a

function of total leaf area and total precipitation.

Evapotranspiration is equal to transpiration

and interception loss. Drainage is calculated

as precipitation in excess of evapotranspiration

and WHC. Maximum water storage capacity is

equated to WHC to a depth of 100 cm. Monthly

evapotranspiration is a function of leaf area, plant

water demand, and climate; i.e., air temperature,

vapor pressure deficit.

We report PnET predictions of NPP for

evergreen, deciduous, and mixed forests. The

PnET model runs were performed for evergreen

and deciduous forest types. NPP for mixed forest

types was assumed to be a 50:50 mix of deciduous

and evergreen NPP. Estimates of NPP were

output at the 0.5° by 0.5° resolution, and then

Anderson Level II forest-cover type pixels were

assigned NPP values within each 0.5° by 0.5°cell.

The resulting estimates of forest productivity

across the Southeastern United States are

stored at a 30-m spatial resolution and include

information about attributes for specific forest

types. Forest biomass predictions for 2000, 2050,

and 2100 were estimated using decadal means

of NPP from the PnET model.

RESULTS AND DISCUSSION

Estimates of Carbon Stocks in Southern Forests

S

outhern forests presently contain 5810 Mt of

aboveground C on 87 million ha. Forests of the

conterminous United States contain 20 340 Mt

of aboveground C on 250 million ha. Thus the

South accounts for approximately 29 percent of

aboveground forest C stock in the conterminous

United States. Allocation of this stock among

forest ecosystem pools is shown in table 33.1. The

sum of standing C in live and dead trees is

provided in table 33.2 by forest type and

ownership. The majority of C is in privately

owned forests and in hardwood forest types.

Countywide estimates of mean aboveground

forest C density are shown in figure 33.1.

Aboveground C includes that in live and dead

trees, understory vegetation, down dead wood,

 and the forest floor. Values for each county

represent the mean for forest land within the

county. Only counties with at least 5 percent of

area classified as forest are included. Mean net

annual growth for the period 1987–97 is shown

in figure 33.2. The C pool represented in this

figure includes the aboveground portion of all live

trees having diameter at breast height greater

than 2.5 cm. Net annual growth is essentially the

net annual change in live tree C stock, a definition

consistent with the use of the term in summary

forest statistics of the United States (Smith and

others 2001).

Estimates of Forest Carbon Stocks 1953–97

In the Southern States, aboveground forest

C stocks generally accumulated steadily between

1953 and 1997 (fig. 33.3). The mean annual change

in tree C stocks between 1953 and 1997 (table 33.2,

column 2) is calculated as the difference between

C stocks in the 2 years divided by the interval in

years (44 years). A positive value represents an

average increase in C stock, as in the case of oakhickory forests, while a negative value indicates an

average decrease, as in the case of privately owned

longleaf-slash pine forests. Because these are total

C estimates, the differences could result from

changes in the area of forest, or in C density, or

both. Between 1953 and 1997, total area of

Chapter 33.

 Forest Carbon Trends

Table 33.1—Mean aboveground carbon density of

productive southern forests (timberlands) by forest

type and carbon pool, 1997

Forest type

Carbon pool Softwood Mixed Hardwood

Mg carbon/ha

Live trees 37.7 55.4 56.0

Standing dead trees 1.7 3.0 3.1

Understory vegetation 2.9 2.2 2.9

Down dead wood 3.3 7.4 7.5

Forest floor 9.3 7.6 5.7
Southern Forest Science:

Past, Present, and Future

Climate Change

388

Table 33.2—Mean aboveground tree carbon mass of southern forests by forest type

and ownership classifications, 1997a

Mean annual

carbon change Total tree Carbon

Forest type 1953–97 carbon density Forest area

Mt carbon per year Mt carbon Mg carbon/ha 1 000 ha

Privately owned forests

Miscellaneous conifer 0.1 14 74.1 193

Longleaf-slash pine -1.8 148 33.2 4 468

Loblolly-shortleaf pine 0.8 721 39.4 18 286

Oak-pine 6.0 486 45.1 10 767

Oak-hickory 23.4 1 686 59.3 28 445

Oak-gum-cypress 6.4 734 70.8 10 356

Elm-ash-cottonwood 0.3 52 61.5 851

Maple-beech-birch 0.3 28 71.5 397

Other Eastern types

(including nonstocked) 0.4 23 8.9 2 541

Total 35.8 3 892 51.0 76 303

Publicly owned forests

Miscellaneous conifer 0.1 6 66.7 86

Longleaf-slash pine 0.2 34 38.8 883

Loblolly-shortleaf pine 0.3 97 48.8 1 988

Oak-pine 1.1 75 52.9 1 418

Oak-hickory 3.8 229 71.6 3 198

Oak-gum-cypress 1.0 113 71.9 1 572

Elm-ash-cottonwood 0.1 8 74.9 102

Maple-beech-birch 0.1 6 83.7 72

Other Eastern types

(including nonstocked) < 0.1 6 5.8 1 025

Total 6.6 574 55.5 10 343

Total South 42.4 4 466 51.5 86 646

a

 The carbon pool includes aboveground portions of live and standing dead trees. Mean annual carbon change

between 1953 and 1997 is calculated as the net change in carbon stock divided by the number of years.
389

7.59 147.77 Mg C/ha

-1.2 3.1 Mg C/ha/year

Figure 33.1—Aboveground carbon (C) density

(Mg C/ha) for forested lands in 1997 in the

Southern United States.

Figure 33.2—Mean net annual tree growth 1953–

97 in terms of carbon (C) density (Mg C/ha/year)

for forested lands in the Southern United States.

Chapter 33.

 Forest Carbon Trends
Southern Forest Science:

Past, Present, and Future

Climate Change

390

0

100

200

300

400

500

600

700

1950 1960 1970 1980 1990 2000

Year

Alabama

Arkansas

Kentucky

Louisiana

Mississippi

Oklahoma

Tennessee

Texas

0

100

200

300

400

500

600

700

1950 1960 1970 1980 1990 2000

Year

Total C mass (Mt) 

Florida

Georgia

North Carolina

South Carolina

Virginia

Total C mass (Mt)

(A)

(B)

privately owned pine forest in the South decreased

by 18 percent, but total C in trees decreased

by only about 2 percent (see table 33.2). During

this interval, the proportion of planted pine to

all pines increased from about 2 percent to about

50 percent.

An estimate of the annual forest contribution

of C for each Southern State is presented in figure

33.4. Estimates of C in harvested wood products

are given in figure 33.5. All States have increased

C in forests over the period. A number of States

have sequestered 5 to 6 Mt C per year in forest

ecosystems. Many States have also sequestered an

additional 2 to 3 Mt C per year in products in use

and landfills, with an additional amount of C in

wood burned for energy.

Estimates of Forest Carbon Stocks 2000–2100

One can only speculate about the effects

of global climate change and socioeconomic

responses to the change on the future composition

of forest ecosystems. The analysis reported here

provides an estimate of potential forest production

for 2000, 2050, and 2100 for the Southeastern

United States. This analysis is based on an

uncalibrated model of forest C balance, a

warmer and wetter climate projected under

the Hadley2Sul scenario, and forest cover from

Landsat TM data (table 33.3). The trend in total

forest C stocks between 2000 and 2050 was

generally steady C accumulation throughout

the period for States in the northern portion

of the region and decreased C accumulation in

Figure 33.3—Estimated total aboveground

forest carbon (C) stock for (A) Southcentral and

(B) Southeastern States 1953–97. Total C mass

(Mt) is for all productive forest land within each

State. Aboveground C includes that in live and

dead trees, understory vegetation, down dead

wood, and the forest floor.
391

0

2

4

6

Alabama

Arkansas

Florida

Georgia

Kentucky

Louisiana

Mississippi

North Carolina

Oklahoma

South Carolina

Tennessee

Texas

Virginia

Mt C/year

1

3

5

0

2

4

6

8

10

12

Alabama

Arkansas

Florida

Georgia

Kentucky

Louisiana

Mississippi

North Carolina

Oklahoma

South Carolina

Tennessee

Texas

Virginia

Mt C/year

In use Landfills Energy Emitted

Chapter 33.

Table 33.3—Hadley 2000, 2050, and 2100 minimum, maximum, and average net primary production for

 Forest Carbon Trends

all forest types

Hadley 2000 Hadley 2050 Hadley 2100

State Min. Max. Avg. Min. Max. Avg. Min. Max. Avg.

g carbon/m2/year

Alabama 1064.2 2320.7 1313.9 1080.6 2158.0 1338.3 674.5 1761.8 1197.4

Arkansas 885.6 1464.4 1151.0 822.9 1480.3 1117.4 744.5 1534.7 1158.1

Florida 1172.8 2320.7 1554.6 1020.9 2191.6 1430.5 391.2 1806.0 1088.4

Georgia 1049.9 2019.8 1298.1 1004.4 1954.7 1323.5 360.2 2026.3 1127.4

Kentucky 997.3 1544.2 1213.2 1017.9 1702.7 1344.8 1006.2 1633.1 1328.5

Louisiana 1037.5 2331.2 1506.9 893.3 2171.1 1363.1 805.8 1755.7 1225.4

Mississippi 1078.1 2086.4 1367.4 999.0 2013.9 1310.2 884.9 1629.6 1210.0

North Carolina 1078.5 2135.5 1424.4 1269.9 2280.3 1627.4 1152.8 2222.0 1488.3

Oklahoma 892.5 1357.3 1107.6 800.1 1224.7 1015.3 546.5 1390.4 1006.0

South Carolina 1060.3 1900.4 1339.2 1184.8 2174.0 1462.1 600.7 2222.0 1344.7

Tennessee 1034.3 1595.2 1286.7 1019.2 1899.3 1402.4 1013.0 1926.5 1371.9

Texas 871.6 2079.4 1202.0 721.9 1933.6 1055.1 597.9 1628.3 1015.1

Virginia 646.8 1936.4 1242.2 785.8 2173.1 1437.5 801.9 1910.3 1359.0

Regional 646.8 2331.2 1313.5 721.9 2280.3 1354.3 360.2 2222.0 1250.7

Figure 33.5—Estimated mean annual change

of carbon in the harvested products

categories 1953–97.

Figure 33.4—Estimated mean annual change in

aboveground forest carbon stock 1953–97.

Estimates are for productive forest land.
Southern Forest Science:

Past, Present, and Future

Climate Change

392

150 2250 g C/m2/year

(A)

150 2250 g C/m2/year

(B)

150 2250 g C/m2/year

(C)

the Southern States (figs. 33.6A and 33.6B). There

is a projected decreasing trend in total forest C

stocks between 2050 and 2100 for all States in the

region (figs. 33.6B and 33.6C). Future trends in

climate suggest increasing air temperature that

will affect woody tissue respiration,

evapotranspiration, and the development of

diurnal and seasonal water stress. Air temperature

will likely be a contributing factor in lowering

future forest productivity, especially along the Gulf

Coastal Plains.

Figure 33. 6—

Estimated annual net

primary production

[g carbon (C) m2/

year] for all forest

types using the

Hadley2Sul climate

scenario for (A)

2000, (B) 2050,

and (C) 2100.
393

ACKNOWLEDGMENTS

T

his research was funded by the U.S.

Department of Agriculture Forest

Service, Southern Global Change

Program, Research Work Unit RWU–4852,

and the Northern Global Change Program,

Research Work Unit RWU–4104.

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Rauscher, H. Michael; Johnsen, Kurt, eds. 2004. Southern forest

science: past, present, and future. Gen. Tech. Rep. SRS–75. Asheville,

NC: U.S. Department of Agriculture, Forest Service, Southern

Research Station. 394 p.

Southern forests provide innumerable benefits. Forest scientists,

managers, owners, and users have in common the desire to improve

the condition of these forests and the ecosystems they support. A first

step is to understand the contributions science has made and continues

to make to the care and management of forests. This book represents

a celebration of past accomplishments, summarizes the current state

of knowledge, and creates a vision for the future of southern forestry

research and management. Chapters are organized into seven sections:

“Looking Back,” “Productivity,” “Forest Health,” “Water and Soils,”

“Socioeconomic,” “Biodiversity,” and “Climate Change.” Each section

is preceded by a brief introductory chapter. Authors were encouraged

to focus on the most important aspects of their topics; citations are

included to guide readers to further information.

Keywords: Biodiversity, climate change, forest health, forest history,

productivity, socioeconomics, soil, water.

DISCLAIMER

The use of trade or firm names in this publication is for reader information

and does not imply endorsement by the U.S. Department of Agriculture of

any product or service.

PESTICIDE PRECAUTIONARY STATEMENT

This publication reports research involving pesticides. It does not contain

recommendations for their use, nor does it imply that the uses discussed here

have been registered. All uses of pesticides must be registered by appropriate

State and/or Federal agencies before they can be recommended.

CAUTION: Pesticides can be injurious to humans, domestic animals, desirable

plants, and fish or other wildlife if they are not handled or applied properly.

Use all pesticides selectively and carefully. Follow recommended practices f

or the disposal of surplus pesticides and their containers.
United States

Department of Agriculture

Forest Service

Southern

Research Station

General Technical

Report SRS-75

Southern Forest Science:

Past, Present, and Future

H. Michael Rauscher and Kurt Johnsen, Editors

ence: Past, Present, and Future

2004