i

Upland Oak Ecology Symposium:

History, Current Conditions, and Sustainability

Fayetteville, Arkansas

October 7–10, 2002

Editor

Martin A. Spetich

Sponsored by

Arkansas Wildlife Federation

Arkansas Forest Resource Center

Arkansas Game and Fish Commission

Arkansas Forestry Commission

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

University of Arkansas Cooperative Extension Service

Financial Contributors

Arkansas Chapter, National Wild Turkey Federation

Arkansas Chapter, The Wildlife Society

Arkansas Forest Resource Center

Arkansas Forestry Commission

Arkansas Game and Fish Commission

Arkansas Natural Heritage Commission

Arkansas Wildlife Federation

National Wild Turkey Federation

U.S. Department of Agriculture, Forest Service, Ozark National Forest

Ross Foundation

The Nature Conservancy

U.S. Department of Agriculture, Forest Service, State and Private Forestry
ii

The “Upland Oak Ecology Symposium: History, Current Conditions, and Sustainability” was held October 7–10, 2002, in

Fayetteville, AR. Recent events such as drought and oak decline are hastening the loss of oaks in upland oak forests of the

Interior Highlands. This and the lack of oak regeneration in many areas of the Highlands raise questions of future viability and

sustainability. In response, a group of natural resource organizations cosponsored a symposium on upland oak ecology. Their

objective was to convene a diverse group of resource specialists and scientists to examine upland oak ecosystems in the light

of historical influences, problems and trends, how they function, and ideas about their long-term restoration.

Sponsors of the symposium included the Arkansas Wildlife Federation; Arkansas Forest Resource Center; Arkansas Game

and Fish Commission; Arkansas Forestry Commission; U.S. Department of Agriculture (USDA), Forest Service, Southern

Research Station; and the University of Arkansas Cooperative Extension Service. Each sponsor provided at least one

representative to the steering committee. The committee worked long hours to prepare and implement the symposium. Its

members included:

Rebecca McPeake, Cooperative Extension, University of

Arkansas

Larry Nance, Arkansas Forestry Commission

Tom Nupp, Arkansas Tech University

Tracy Powers, USDA Forest Service, Public Affairs

George Rheinhardt, Arkansas Forestry Commission

Scott Simon, The Nature Conservancy

Martin A. Spetich, USDA Forest Service, Southern

Research Station

Tamara Walkingstick, Cooperative Extension, University of

Arkansas

Rick Williams, Arkansas Forest Resource Center

Nancy Young, USDA Natural Resources Conservation

Service

PREFACE

David Blackburn, Arkansas State Plant Board

Martin L. Blaney, Arkansas Game and Fish Commission

Cheryl Chatham, USDA Forest Service, Public Affairs

Steve Duzan, Arkansas Wildlife Federation

Tom Foti, Arkansas Natural Heritage Commission

Dr. John Gray, Arkansas Wildlife Federation

Caroll Guffey, University of Arkansas at Monticello, School

of Forest Resources

James Guldin, USDA Forest Service, Southern Research

Station

Doug James, University of Arkansas

Chris Kellner, Arkansas Tech University

Gene Leeds, USDA Forest Service, Ozark National Forest

Jack Martin, Society for the Preservation of Ozark Culture

Robert McAnally, Arkansas Game and Fish Commission

Partial funding was provided by the Arkansas chapters of the National Wild Turkey Federation and The Wildlife Society; the

Arkansas Forest Resource Center, Arkansas Forestry Commission, Arkansas Game and Fish Commission, Arkansas Natural

Heritage Commission, Arkansas Wildlife Federation; the National Wild Turkey Federation; USDA Forest Service, Ozark

National Forest; Ross Foundation; The Nature Conservancy; and USDA Forest Service, State and Private Forestry.

Special thanks to Dr. John L. Gray, Little Rock, AR, for his enthusiastic help with this symposium and to Arkansas Tech

University students for their assistance at the symposium.
iii

CONTENTS

Page

Introduction and Synthesis

Upland Oak Ecology Symposium: A Synthesis

Martin A. Spetich . . . . . . . . . . . . . . . . . . . . . . . . . 3

The Oak Forest Ecosystem

Thinking About Oak Forests as Responsive

Ecosystems

Paul S. Johnson . . . . . . . . . . . . . . . . . . . . . . . . . 13

Historical Perspectives Influencing the

Establishment and Sustainability of

Upland Oak Forests

Upland Hardwood Forests and Related

Communities of the Arkansas Ozarks in the

Early 19th Century

Thomas L. Foti . . . . . . . . . . . . . . . . . . . . . . . . . . 21

The Forest as a Resource: From Prehistory to

History in the Arkansas Ozarks

George Sabo III, Jami Joe Lockhart, and

Jerry E. Hilliard . . . . . . . . . . . . . . . . . . . . . . . . . . 30

History of Missouri Forests in the Era of

Exploitation and Conservation

David Benac and Susan Flader . . . . . . . . . . . . . 36

Old-Growth Wooded Pasture in the Ozarks

David H. Jurney and David W. Stahle . . . . . . . . 42

Age Distribution of Oak Forests in North-Central

Arkansas

Rick Soucy, Eric Heitzman, and

Martin A. Spetich . . . . . . . . . . . . . . . . . . . . . . . . . 53

Patterns of Oak Dominance in the Eastern

Ouachita Mountains Suggested by

Early Records

Don C. Bragg . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Upland Oak Forest Ecology and Wildlife Ecology

Upland Oak Ecology and Management

D.H. Van Lear . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Oak Dispersal Syndromes: Do Red and White

Oaks Exhibit Different Dispersal Strategies?

Michael A. Steele, Peter Smallwood,

William B. Terzaghi, John E. Carlson,

Thomas Contreras, and Amy McEuen . . . . . . . . 72

The Keystone Role of Oak and Hickory in the

Central Hardwood Forest

James S. Fralish . . . . . . . . . . . . . . . . . . . . . . . . . 78

A Pilot Test of Indicator Species to Assess

Uniqueness of Oak-Dominated Ecoregions in

Central Tennessee

W. Henry McNab, David L. Loftis, Callie J.

Schweitzer, and Raymond M. Sheffield . . . . . . . 88

Page

Oak Forest Composition, Site Quality, and

Dynamics in Relation to Site Factors in the

Southeastern Missouri Ozarks

John M. Kabrick, Stephen R. Shifley,

Randy G. Jensen, David R. Larsen,

and Jennifer K. Grabner . . . . . . . . . . . . . . . . . . . 94

A Dendrochronological Analysis of Red Oak Borer

Abundance

Rose-Marie Muzika and Richard P. Guyette . . . 102

Wildlife and Upland Oak Forests

James G. Dickson . . . . . . . . . . . . . . . . . . . . . . . . 106

Oak-Black Bear Relationships in Southeastern

Uplands

Joseph D. Clark . . . . . . . . . . . . . . . . . . . . . . . . . 116

Use of Tree Species by Summer Birds in

Ozark Upland Oak-Hickory Forest

C. Joan Patterson and Douglas A. James . . . . . 120

Survival of Hardwood Regeneration During

Prescribed Fires: The Importance of Root

Development and Root Collar Location

Patrick Brose and David Van Lear . . . . . . . . . . . 123

The Effects of Humans and Topography on

Wildland Fire, Forests, and Species Abundance

Richard P. Guyette and Daniel C. Dey . . . . . . . . 128

Fire History of a Forest, Savanna, and

Fen Mosaic at White Ranch State Forest

Daniel C. Dey, Richard P. Guyette, and

Michael C. Stambaugh . . . . . . . . . . . . . . . . . . . . 132

A Perspective on Quercus Life History

Characteristics and Forest Disturbance

Richard P. Guyette, Rose-Marie Muzika,

John Kabrick, and Michael C. Stambaugh . . . . . 138

Survivorship and Growth of Oak Regeneration in

Wind-Created Gaps

Erik C. Berg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

Comparison of Saproxylic Beetle (Coleoptera)

Assemblages in Upland Hardwood and

Bottomland Hardwood Forests

Michael D. Warriner, T. Evan Nebeker,

Steven A. Tucker, and Terence L. Schiefer . . . . 150

Litter Decomposition in Low and High Mortality

Northern Red Oak Stands on Extremely Acidic

Southwestern Pennsylvania Soils

Michael C. Demchik and William E. Sharpe . . . . 154

Characterization of an Old-Growth Forest in the

Cross Timbers of Oklahoma

S.L. Clark and S.W. Hallgren . . . . . . . . . . . . . . . 160
iv

Page

Upland Oak Ecosystem Restoration

and Management

Upland Oak Regeneration and Management

David L. Loftis . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

Effects of Different Large-Scale Prescribed

Burning Regimes on Advance Reproduction in

the Missouri Ozarks

Daniel C. Dey and George Hartman . . . . . . . . . 168

Oak Ecosystem Restoration and Maintenance

in Southern Illinois

Charles M. Ruffner and John W. Groninger . . . . 177

Effect of Pre-Harvest Shade Control and

Fencing on Northern Red Oak Seedling

Development in the Central Appalachians

Gary W. Miller, James N. Kochenderfer,

and Kurt W. Gottschalk . . . . . . . . . . . . . . . . . . . . 182

Fire and Thinning in an Ohio Oak Forest: GridBased Analyses of Fire Behavior, Environmental

Conditions, and Tree Regeneration Across a

Topographic Moisture Gradient

Louis R. Iverson, Anantha M. Prasad,

Todd F. Hutchinson, Joanne Rebbeck, and

Daniel A. Yaussy . . . . . . . . . . . . . . . . . . . . . . . . . 190

Oak Growth and Response to Thinning

Stephen R. Shifley . . . . . . . . . . . . . . . . . . . . . . . 198

Success of Underplanting Northern Red Oaks

Martin A. Spetich, Daniel C. Dey,

Paul S. Johnson, and David L. Graney . . . . . . . 206

Wood Products by Species and Quality in

Upland Forests

David W. Patterson . . . . . . . . . . . . . . . . . . . . . . . 212

Oak Decline

Oak Decline and Red Oak Borer in the Interior

Highlands of Arkansas and Missouri: Natural

Phenomena, Severe Occurrences

Dale A. Starkey, Forrest Oliveria,

Alexander Mangini, and Manford Mielke . . . . . . 217

Biology and Sampling of Red Oak Borer

Populations in the Ozark Mountains of Arkansas

Damon Crook, Fred Stephen, Melissa Fierke,

Dana Kinney, and Vaughn Salisbury . . . . . . . . . 223

Oak Mortality Trends on the Interior Highlands

of Arkansas

James F. Rosson, Jr. . . . . . . . . . . . . . . . . . . . . . . 229

Assessing Oak Decline Incidence and Distribution

in the Southern U.S. Using Forest Inventory and

Analysis Data

Steven W. Oak, James R. Steinman,

Dale A. Starkey, and Edwin K. Yockey . . . . . . . . 236

Birds of Upland Oak Forests in the Arkansas

Ozarks: Present Community Structure and

Potential Impacts of Burning, Borers, and

Forestry Practices

Kimberly G. Smith, Michael Mlodinow,

Janet S. Self, Thomas M. Haggerty, and

Tamara R. Hocut . . . . . . . . . . . . . . . . . . . . . . . . . 243

Page

Impacts of Potential Oak Forest Change on

Breeding Birds in Northwestern Arkansas

Douglas A. James . . . . . . . . . . . . . . . . . . . . . . . . 253

Oak Decline in Missouri: History Revisited

Jay R. Law, Ross Melick, Charly Studyvin,

and James R. Steinman . . . . . . . . . . . . . . . . . . . 257

Modeling Gypsy Moth-Related Tree Mortality

Under Different Outbreak Scenarios in Interior

Highlands Forests

Kurt W. Gottschalk, James M. Guldin,

and Jimmie J. Colbert . . . . . . . . . . . . . . . . . . . . . 259

Management

Fitting Fire into Oak Management

Patrick Brose . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263

Conversion of Successionally Stable Even-Aged

Oak Stands to an Uneven-Aged Structure

Edward F. Loewenstein and James M. Guldin . . 264

Regeneration Potential of Selected Forested

Stands on the Cumberland Plateau of

North Alabama

Callie Jo Schweitzer, David L. Loftis,

Yong Wang, and Greg C. Janzen . . . . . . . . . . . . 269

Survival of Hardwood Seedlings and Saplings

Following Overstory Thinning and Prescribed

Fires in Mixed-Oak Forests of Southern Ohio

Joanne Rebbeck, Robert Long, and

Daniel Yaussy . . . . . . . . . . . . . . . . . . . . . . . . . . . 275

Understory Response to Disturbance:

An Investigation of Prescribed Burning and

Understory Removal Treatments

Benjamin J. Dolan and George R. Parker . . . . . 285

The Influence of Soil Scarification on Oak

Reproduction: Review and Management

Considerations

John M. Lhotka, James J. Zaczek, and

Russell T. Graham . . . . . . . . . . . . . . . . . . . . . . . 292

The Effects of Lime, Fertilizer, and Herbicide

on Forest Soil Solution Chemistry and Northern

Red Oak Radial Growth Following Shelterwood

Harvest

Angela M. Happel and William E. Sharpe . . . . . 295

Oak Bole-Wood Chemistry Response to

Fertilization at Two Ozark Sites

David R. DeWalle, William E. Sharpe, and

Bryan R. Swistock . . . . . . . . . . . . . . . . . . . . . . . . 297

Spatial and Temporal Distribution of Weeviled

Acorns Within a Northern Red Oak Seedling

Orchard

D.R. Miller and S.E. Schlarbaum . . . . . . . . . . . . 299

Closing Remarks

Where Do We Go From Here?

Martin L. Blaney, Scott Simon,

James M. Guldin, Tom Riley, Donny Harris,

and Rebecca McPeake . . . . . . . . . . . . . . . . . . . . 303

Index of Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
1

Introduction and Synthesis
2
3

INTRODUCTION

This manuscript is a synthesis of major ideas presented at

the Upland Oak Ecology Symposium held October 7–10,

2002, in Fayetteville, AR. More than 350 managers, scientists, landowners, and others gathered to discuss problems

and opportunities common to upland oak (Quercus spp.)

forests, focusing mainly on forests of the Interior Highlands.

However, much of the information contained is applicable to

upland oak forests in general. This paper highlights common

threads among symposium papers and incorporates additional supporting information to help link the full range of

ideas presented.

As the proceedings papers illustrate, upland oak forests are

complex systems that have evolved over millennia. Both

human and natural disturbances have played an important

role in their development. In his keynote paper, Paul Johnson

explains that the response of upland oak forests to disturbance can be anticipated by understanding the stages of

stand development, and by recognizing that such forests

are in a constant state of change. Dr. Johnson’s presentation set the stage for a valuable, informative conference.

HISTORICAL PERSPECTIVES INFLUENCING THE

ESTABLISHMENT AND SUSTAINABILITY OF

UPLAND OAK FORESTS

Oak- and hickory- (Carya spp.) dominated forest communities of what is now known as the Central Hardwood Region

(Merritt 1980) became established at least 5,000 years ago

(Fralish, in press). The use of fire by Native Americans

influenced development of this forest complex. Without

modern fire breaks such as roads or fire lines, once set, fire

would likely transform large landscapes on a regular basis.

Native Americans also intimately interacted with these

forests in many other ways. For instance, hardwoods were

the most important wood for native dwellings in northern

Arkansas, and oak was the most important species for fuelwood. Thus, between 500 and 5,000 years ago, communities of at least 250 people were an important component of

the forest ecosystem in the Boston Mountains of Arkansas,

especially where wood, water, and productive soils existed

(George Sabo III, in press).

The overall impact of Native Americans on the landscape

varied with their historic population levels. DeVivo (1990)

presents a convincing argument that presettlement Native

American populations were much greater than previous

estimates. He suggests that by the time Europeans began

settling the interior, noncoastal areas of North America

(nearly 200 years after Columbus landed on the continent),

the diseases transmitted over the previous 200 years had

depopulated the areas significantly. He and others have

based their estimates on historical information about diseasecaused depopulation of Latin American regions. He further

quotes Williams (1989): “There is the strong possibility that

in the late 15th century the Western Hemisphere may have

had a greater total population than Western Europe.”

By the early 1800s, European settlement of northern

Arkansas had begun. Tree measurements taken then have

allowed scientists to estimate relative forest species composition and structure of the period. During that time, General

Land Office surveys were conducted in the Arkansas Ozarks.

Based on those records, the Boston Mountains and the

Springfield Plateau Subsection had more trees per acre than

areas to the north. Today, the Boston Mountains have even

more trees per acre than they did then, probably a result of

fire suppression (Foti, in press). In fact, a fire-history study

in the Lower Boston Mountains by Guyette and Spetich

(2003) found major changes in the mean fire interval (MFI)

since 1680. They divided the time since 1680 into four

periods: the Native American period (1680 to 1820), EuroAmerican settlement period (1821 to 1880), regional development period (1881 to 1910), and fire suppression period

(1911 to 2000), in which they found the MFI to be 11.2

years, 2.7 years, 2.9 years, and > 80 years, respectively.

This provides quantitative evidence of how effective the

past 80+ years of fire suppression has been in this region.

Over the past 80+ years, fire suppression likely has altered

species dynamics of these upland hardwood forests. On

medium- to high-quality sites, one impact has been a lack

of successful regeneration and recruitment of oak into

forest overstories while shade-tolerant species such as red

maple (Acer rubrum L.) have become more dominant. For

instance, in a study of four mature oak stands in northcentral Arkansas, Soucy and others (in press) found that

oak establishment has declined while establishment of

UPLAND OAK ECOLOGY SYMPOSIUM: A SYNTHESIS

Martin A. Spetich1

1 Research Forester, USDA Forest Service, Southern Research Station, Hot Springs, AR 71902.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Recent changes in upland forests of the Interior Highlands have raised the interest of and questions from

professional resource specialists and the public. This renewed interest in Interior Highland forests provided researchers

an opportunity to update resource specialists on new knowledge regarding upland oak ecology. Symposium presentations

and the papers presented in this volume offer up-to-date knowledge that can be applied to the management of upland oak

forests and can help resource specialists keep the public better informed.
4

shade-tolerant species has continued successfully over the

past 50 to 60 years. This likely is due to lack of disturbance.

Based on the ecology and physiology of oaks, and the fire

history of these forests, reduced fire disturbance and the

resultant increase in competing species over the last 100

years appears to be a major factor in the loss of successful

oak regeneration on these medium- and high-quality sites.

However, on low-quality sites, oaks can regenerate and

successfully compete, even in the absence of fire. For

instance, a study in the Ouachita Mountains comparing

early records and recent data for a xeric site where fire had

long been absent indicated a trend toward successful oak

regeneration (Bragg, in press; Murphy and Nowacki 1997).

The 5,000-year history of these oak-hickory forests provides

many lessons for the modern forest manager. New information is being used to better understand upland oak forest

ecology and dynamics and, where appropriate, to mimic

past disturbances.

UPLAND OAK FOREST ECOLOGY AND

WILDLIFE ECOLOGY

The Central Hardwood Forest region (Merritt 1980) has been

dominated by oak and hickory trees for thousands of years,

with oaks being a keystone species (Fralish, in press; Spetich

and others 2002). Disturbance and oak forest dynamics

relative to disturbance are overriding themes in this section

of the proceedings, and many papers focus primarily on

disturbance by fire. Historically, these forests were regularly

subjected to fire. Fire frequency and intensity were greatly

influenced by humans (Dey and others, in press) and by

topography (Guyette and Dey, in press).

Of all the disturbance factors that have shaped upland oak

forests, fire probably is among the most important. Van Lear

(in press) proposes that, because oaks adapt to low-intensity surface fires, it is possible to use prescribed fire to reach

a variety of management goals in oak-dominated forests.

Brose and Van Lear (in press) point out several reasons

why oak is better at surviving surface fires than other

species. For example, due to the hypogeal germination

strategy of oaks and hickories, their root collars are closer

to ground level than many other hardwood species. This

helps protect their dormant buds from fire.

Acorns must survive predation if they are to become seedlings. Differences between red oak (Q. rubra L.) and white

oak (Q. alba L.) acorns—such as the energy contained

within them, palatability to wildlife, and masting time—help

these species survive predation (Steel and others, in press).

Acorns that survive and germinate have additional challenges. In forests of many Northern and Eastern States

where white-tailed deer (Odocoileus virginianus) populations are high, browsing of oak seedlings has a significant

impact on oak regeneration. However, in the large contiguous forest matrix of Arkansas’s Boston Mountains, we have

rarely observed oak-specific browsing damage to seedlings

from deer. This likely is due in part to the preponderance of

other species preferred by deer, such as poison ivy (Toxicodendron radicans L.), greenbrier (Smilax Bona-nox L., S.

glauca Walt., S. rotundifolia L.), huckleberry (Vaccinium

vacillans var. crinitum Fern.), red maple (A. rubrum L.), and

Virginia creeper (Parthenocissus quinquefolia L. Planch.).

When making management decisions, it is important to

determine the existing mix of impacts on acorn and oak

seedling survival.

Survival and successful competition of oak seedlings can

lead to changes in forest composition and structure, which

are important to bird communities. For instance, Patterson

and James (in press) found that birds in this region used

oaks more often than other tree species. Further, bird habitat can be improved through management activities such as

prescribed fire, various harvesting techniques, and natural

disturbances (Dickson, in press).

Management activities also can be used to provide a wide

range of habitats. For instance, maintaining a wider range

of successional stages in oak forests of the Interior Highlands likely would have reduced the impact of oak decline

and enhanced habitat for a wide range of wildlife species,

some of which need both mature forest and early successional habitat. For example, both oak mast found in mature

forests and soft mast found in early successional habitats

are needed by black bears (Ursus americanus) (Clark, in

press). Natural disturbances such as wind, fire, and oak

decline also can create early successional habitats, but

unlike well-planned management activities, not necessarily

at the time, place, or scale that would most benefit wildlife

populations and the public.

Forest managers know the importance of predicting how

mature oak trees respond to natural disturbances such as

oak decline and associated factors like increased red oak

borer (Enaphalodes rufulus Haldeman) populations. For

instance, Muzika and Guyette (in press) present an innovative study that invites exploration of past oak borer events

relative to tree age, ring width, and temperature. Such

studies will help identify conditions that influence oak borer

populations and lead to models that help managers predict

future population levels and activity.

To accurately model upland oak forest systems, scientists

need data that have been collected over a long time. In

addition, standard, comparable, precise, quantitative data

among species are necessary when modeling oak lifehistory characteristics (Guyette and others, in press). It is

often difficult to discern significant changes over the short

term in these forests; e.g., Demchik and Sharp (in press).

Even in small, gap-size disturbances, seedling dynamics

are highly variable during the first several years after a

disturbance event; e.g., Berg (in press). At the stand scale,

the stand-initiation stage is chaotic, making predictions of

species and stand structure problematic (Johnson, in press).

Even more broadly, when modeling large landscapes,

ecologically discrete areas need to be well defined and

evaluated (Kabrick and others, in press; McNab and others,

in press).

To increase the predictive power of forest models, it will

be necessary to make greater commitments to long-term

studies. Mechanisms should be developed to continue

orphaned studies; i.e., studies where the responsible

researcher has retired or otherwise moved on. Such

mechanisms will allow future generations of scientists
5

and managers to examine stand dynamics throughout the

life of a forest, rather than the life of an individual researcher.

Such commitment will make future restoration and management of these forests possible and help maximize benefits

to the public.

UPLAND OAK ECOSYSTEM RESTORATION AND

MANAGEMENT

There was general agreement at the symposium that oak

regeneration and appropriate disturbance factors, which

allow successful survival and growth of oak regeneration,

are critical to restoration of the upland oak forest. In fact,

successful oak regeneration has been acknowledged as

problematic in eastern forests for at least 25 years (Lorimer

1989). The potential for even larger losses of keystone oak

species helped focus authors in this section on the success

of oak regeneration and disturbance factors that could facilitate successful oak restoration. Without oaks, there would

be no oak ecosystem. Effective management methods will

be necessary to help guide oaks into a successful position

relative to their interspecific competitors, so they may

survive to become part of the future forest (Spetich and

others, in press).

The outcome of interspecific competition between oak

regeneration and other natural vegetation is a function of

site factors, associated differences in growth rates of cooccurring species, the genetics of plant populations, and

the state of the vegetation complex when silviculturally

prescribed or naturally imposed disturbances occur. The

competitive capacity of a species, therefore, may vary as

those factors vary in time and space (Spetich and others

2002). This in turn influences the composition and structure

of the next stand.

Understory and midstory structure and composition are

important factors in species composition and dynamics of

the next stand (Miller and others, in press; Ruffner and

Groniger, in press). Managing these components properly

is necessary for successful restoration of oak-hickory forests.

This leads us to the two key requirements for successful

oak regeneration: “(1) to ensure that competitive regeneration sources are present, and (2) to provide timely, sufficient

release of these regeneration sources” (Loftis, in press).

In order to restore and maintain oak forests, we need a

well-developed understanding of how they function and

respond under various environmental conditions and disturbances. For example, we know there are major differences

in relative competitive capacity of oaks across the spectrum

from low-quality xeric sites to high-quality mesic sites (Loftis,

in press; Spetich and others 2002). As site index increases,

the competitive capacity of oak decreases because more

and more species can survive and compete. Without disturbance, oaks are competitively excluded from the higher

quality, more mesic sites.

Fire is probably the most widely recognized disturbance

element missing from these upland forests today. This has

led to increased research activity in prescribed fire with the

intent of finding the best method(s) of restoring this disturbance agent. For instance, a study by Dey and Hartman (in

press) examined the effects of repeated burning of oak

forest vegetation, providing valuable insight into relative fire

response among species in the Missouri Ozarks. They

found that although repeated burns reduced survival of all

species one growing season following the last fire, the

overall effect resulted in favoring oak and hickory reproduction. Iverson and others (in press) demonstrated how a

combination of sensors, data recorders, and landscapelevel analysis helped them gain significant insight into fire

behavior in an oak forest.

Once a stand has been successfully regenerated through

natural or anthropogenic disturbance, an appropriate

management regime will be necessary to keep the stand

growing vigorously. Increased stand vigor can help reduce

losses to oak decline, insects, and disease, as well as

maximize yield. Shifley (in press) explains that an understanding of forest development stages will help practitioners administer appropriate thinning regimes to achieve

vigorously growing forest stands. Practitioners can achieve

the most successful thinning regime by starting early in the

stem-exclusion stage and working with the stand’s natural

dynamic as presented by Shifley (in press). Stages of stand

development can be illustrated pictorially, which gives

resource specialists an important visual reference of forest

development. Such visual references can also provide

deeper insight into structural changes caused by disturbance events, such as the current oak decline event.

OAK DECLINE

From 1856 to 1986 there have been 57 oak-mortality events

recorded in the Eastern United States (Millers and others

1989). This included one in 1959 in the Ozark Mountains of

Arkansas (Tool 1960), one in 1980-81 in Northwestern

Arkansas (Bassett and others 1982, Mistretta and others

1984), and another in Missouri from 1980 to 1986 (Law and

Gott 1987). The current oak-decline event in Arkansas and

Missouri has been recognized as unique among other known

oak-decline events due to the proliferation of oak borers,

one of the contributing factors. Because of this extraordinary proliferation, the development has received widespread

attention from experts around the country (Starkey and

others, in press). However, many factors, such as drought,

also influence oak decline.

Starkey and others (in press) have defined drought as an

“inciting factor” of oak decline. Crook and others (in press)

examine three drought events over the past 50 years. Even

though the last drought (1998 to 2000) was not as severe

as the previous two major droughts (one in the early 1950s

and one in the mid-1960s), the authors suggest that it likely

led to the current unprecedented outbreak of red oak borer.

One of the major changes that occurred in upland forests

over the last few decades is an increase in tree density and

tree age, both conditions that make forests more vulnerable

to oak decline (Oak and others, in press). Crook and others

(in press) also did an extensive survey of 21 trees on a plot

in the Ozarks and concluded that oak borers were responsible for tree death. Their conclusion that red oak borers

are a main cause of tree death differs from the conclusion

of others who view oak borers as one of several contributing factors (Law personal communication; Oak and

others, in press; Starkey and others, in press). With or

without oak borers, oak species across large landscapes
6

die during an oak-decline event. There is little doubt that

the additional stress of this large population of borers is

helping to contribute to the demise of many trees, as are

advanced stand age, high stand density, and drought. However, the latter three stresses predispose a stand to oak

decline whereas oak borers are opportunistic organisms

that take advantage of already stressed trees. For trees on

the verge of death, additional stress from any one of these

stress mechanisms could result in earlier mortality.

A regional oak-decline study covering 12 Southeastern

States examined data from 26,907 forest inventory plots

(Oak and others, in press). The authors found a total area

of 104.7 million acres dominated by oaks. Of that total, 43.5

million acres constituted sites with trees large enough and

with enough oak basal area to be considered susceptible to

oak decline. Those results are based on the most recent

Forest Inventory and Analysis inventory cycle (from 1991 to

1997). In Arkansas, they found that the area affected by

oak decline more than doubled from 1988 to 1995 and that

this was concurrent with increases in stand age and stand

density.

An oak-decline event such as the current one has the

potential to significantly alter forest structure and species

composition, which in turn will affect wildlife. Both Smith

and others (in press) and James (in press) addressed

potential effects of oak decline on bird populations. Smith

predicted that 10 to 20 species would decline, while 11 or

more species would increase. However, James predicted

that 21 bird species would decrease while 38 would

increase. The difference between the two studies may be

due in part to their interpretation of how extensively oak

decline will impact tree species composition. For instance,

Smith and others suggest elimination of red oaks while

James appears to view this as a thinning of the forest with

some areas of high oak mortality.

Based on previous oak-decline events (Oak and others

1988, Starkey and others 1989, Tainter and others 1984),

it is likely that oaks will remain an important component of

these forests at the regional scale, but that the species no

longer will be the dominant tree in many stands without

active management to encourage competitive oak regeneration. On sites where oak reproduction is present but

competing species have the advantage, active management will be necessary to successfully guide a new cohort

of oak into the tree canopy.

MANAGEMENT

We now recognize that there are often multiple management options in a given stand (Loftis, in press). Generally,

more management options are available on low-productivity, xeric to xero-mesic sites where oak regeneration tends

to be more successful than on more productive sites.

Loewenstein and Guldin (in press) define such low-productivity sites as successionally stable oak stands. On more

productive, mesic sites where fire or other disturbance

mechanisms have been absent, long-term oak regeneration

is seldom very successful. On those sites, competitive woody

species (including shade-tolerant species that easily out

compete oaks in the absence of disturbance) often are

more abundant. If the management objective is to maintain

oak as a major component of the stand, then management

options typically are more limited and problematic on the

more productive sites.

We often separate high-quality (mesic) and low-quality (xeric)

sites when referring to a specific management technique.

For instance, Loewenstein and Guldin (in press) describe a

technique to convert even-aged oak stands to uneven-aged

stands on sites where oaks are successionally stable (lowto medium-quality sites). Schweitzer and others (in press)

modeled forest stands that fall into the low- and high-quality

categories. They concluded that significantly different management regimes would be necessary on each site due to

differences in the relative competitiveness of oaks. Prescribed fire is often suggested as a possible management

option on high-quality sites. However, fire alone may not be

sufficient because these forests have been without fire for

so long that competing species can be large in diameter

and therefore resistant to fire. In such cases additional

work, perhaps through mechanical or chemical control, will

be needed initially to control competing species, helping to

restore the desired understory and midstory forest structure

and species composition.

Brose (in press) describes optimal times and methods to

apply prescribed fire. One method combines a shelterwood

system with prescribed fire. This is supported by a recent

study by Rebbeck and others (in press), who found that the

number of fire top-killed seedlings was highest when overstory removal and fire were combined. Fire top-killed oak

seedlings resprout under those conditions while accumulating energy in their root system, but shade-tolerant competitors do not. Additionally, results from a study by Dolan

and Parker (in press) show that fire and silvicultural treatments can be combined to improve growing conditions for

oak seedlings.

However, Brose (in press) also suggests that mechanical

site scarification may be a better management strategy

than fire for initial establishment of new seedlings. Lhotka

and others (in press) review four studies on how scarification affects oak seedling establishment. For seedlings to

survive, scarification would need to be combined with other

management practices. On areas where scarification is

operationally feasible, it likely would be most useful in

small, defined areas. Studies suggest that future research

also should consider time of scarification relative to time and

amount of seed fall. For instance, Miller and Schlarbaum (in

press) found that weevil predation on early-fall acorns

differed from predation on acorns that fell later.

Fertilization is another seldom-used tool in management of

upland oak forests, and it can be a useful option where the

desire for increased growth rate outweighs costs. Happel

and Sharp (in press) examined the use of fertilizer, lime,

and herbicide, and found an increase in radial growth of

oak on extremely acidic soils. DeWalle and others (in press)

found that nitrogen fertilization can cause short-term soil

acidification. A study by Graney (1986), in which a one-time

fertilizer application of a nitrogen and phosphorus combination was applied to oaks, found significant increases in

diameter growth over a 10-year period.
7

CONCLUSIONS

Upland oak-dominated forests are complex ecosystems that

became established at least 5,000 years ago. Both human

and natural disturbances have played a role in their development. Native American activities probably had a major

impact on upland oak forest development, especially through

the use of fire as a management tool. By the mid-1800s,

European settlers began to substantially alter the landscape

through forest clearing and increased fire frequency. Over

much of the 20th century, massive and effective fire suppression efforts resulted in changes in forest structure and

composition. Oak regeneration has changed the most on

medium- to high-productivity sites.

Today’s land managers face many challenges and difficult

decisions in caring for upland oak forests. Competitive oak

regeneration often is absent on productive sites; oak decline

is changing forest structure and composition throughout the

Interior Highlands; disturbance mechanisms are not yet

thoroughly understood; and new problems such as gypsy

moth and sudden oak death pose additional threats.

Nonetheless, a renewed commitment to research, as well

as active management on a large scale over the next 15

years, could make the restoration of upland oak forests

possible across the region. Development of models for predicting the competitive capacity of oak, relative to disturbance

in specific plant communities and site-quality combinations,

will greatly improve the chances for success in restoring

and managing oak-dominated plant communities.

But a commitment to long-term and orphaned studies also

will be necessary. For example, in the Boston Mountains of

Arkansas the author has found (Spetich, unpublished

observations) that tagged oak rootstocks that have been

top-killed sometimes will lie dormant for 1 year or more

before resprouting, a fact that short-term studies would not

have captured. Monitoring rootstocks over time will allow

better determination of their true survival and competitive

success. In addition, long-term studies will improve the land

manager’s working knowledge of forest dynamics and

benefit other components of the upland oak ecosystem.

As forests evolve, so does our knowledge of them. The

papers in this volume represent views of various authors’

knowledge at one point in time. But a caring, responsible

stewardship will require a continuous monitoring of change—

both in forest dynamics and in our knowledge of them. In

carrying out such stewardship, the scientist and land manager both must be willing to use new information in ways that

ensure the evolution of responsible decision-making.

ACKNOWLEDGMENTS

Thanks to Michael G. Shelton and Stephen R. Shifley for

reviewing this manuscript and to Betsy L. Spetich for

editorial guidance and insight.

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10
11

The Oak Forest Ecosystem
12
13

INTRODUCTION

Because forests are “open systems,” they are continually

responding to forces originating from both within and

outside the forest itself. Unlike a tree seedling in a growth

chamber with precisely fixed growth conditions, trees and

other organisms in a forest must continually adjust to

changing conditions, many of which are unknown or only

occur probabilistically. The list of factors that can change

are indeterminate, i.e., they are so numerous and often

unknown that we are unable to list all of them even for a

single acre of forest. They include both physical and

biological factors. Some factors produce effects that are

sudden and result in major changes, while others operate

more slowly and subtly. The only constant is the forest’s

continual response to relentless change.

TYPES OF RESPONSES

All forests respond to external (exogenous) and internal

(endogenous) forces. Exogenous forces include, but are

not limited to, wind, fire, insects, tree diseases, and human

activity. Endogenous forces include crown closure, tree

growth, tree mortality and associated self-thinning, and

changes in species composition. In all cases, the forest

“responds” to internally or externally induced changes.

Because these changes are endless, an oak forest or

savanna is therefore never “finished”–whether it is the

product of human endeavor or of exclusively “natural”

processes. Human activity, from an ecological and historical

perspective, represents only one of the many forces that

influence forests. Moreover, silvicultural and ecological

restoration projects may not always produce their intended

results. Forests are in effect “equal opportunity” responders

to whatever forces and events come their way. We nevertheless need not be working blindly in achieving management goals. On the contrary, the manager can capitalize on

a wealth of information on how oak forests respond to

endogenously and exogenously caused changes.

Endogenous Change in Even-aged Oak Stands

Even-aged stands usually originate from sudden largescale disturbances, natural or human-caused, that destroy

all or most of the overstory of the previous stand. An evenaged stand thus consists of a group of trees comprising a

single age class. This usually means that tree ages differ by

no more than about 20 years.

Even-aged stands progress through a relatively predictable

series of developmental stages until the next stand-initiating

disturbance or some other severe disturbance occurs. These

stages result from the internal dynamic of the stand itself.

Defining these stages is useful in understanding the development of oak forests even though the duration of each

stage and the accompanying changes in stand structure,

density, and species composition may differ from stand to

stand.

Although various terms have been used to define the stages

of stand development, it is convenient here to follow the

terminology of Oliver and Larson (1996) as modified by

Oliver (1997). They defined four stages: (1) the stand initiation stage, (2) the stem exclusion stage, (3) the understory

reinitiation stage, and (4) the complex stage (fig. 1). The

complex stage of development also has been called the

old-growth stage (Oliver 1981). These stages and their

definitions provide a convenient conceptual framework for

anticipating the inevitable changes in the ecological states

that occur in oak forests.

The stand initiation stage—The development of an evenaged stand begins with the stand initiation stage (fig. 1).

This stage typically lasts about 20 years in eastern oak

forests. A brushy mass of woody vegetation comprised of

thousands of trees and shrubs per acre, usually mixed with

a luxuriant growth of vines and herbaceous plants characterizes this stage. It is a period of rapid change with intense

competition among trees and other plants for growing

space. Standing biomass is small relative to later stages of

development, but the rate of biomass increase is high.

During this stage, the quantity of dead biomass is often

larger than during other stages of stand development. This

results from the stand-initiating disturbance itself, which

except when preceded by fire, usually leaves a large

residue of tree boles and branches on the forest floor.

During the stand initiation stage, gaps in the new vegetative

cover may persist for a decade or longer while new trees and

other vegetation become established. New tree seedlings

and herbaceous vegetation initially require little growing

space. During this stage there are numerous microenvironments where seeds find the necessary conditions for

germination and growth free from predators, competitors,

and pathogens. Changes in the number, species, and size

THINKING ABOUT OAK FORESTS AS RESPONSIVE ECOSYSTEMS

Paul S. Johnson1

1 Principal Silviculturist (Retired), USDA Forest Service, North Central Research Station, University of Missouri, Columbia, MO 65211.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Like all forests, oak forests are continually responding to disturbances originating from both within and outside

the forest. Oaks (Quercus spp.) owe their very existence to disturbance. In this context, silvicultural and other management practices can be thought of as planned disturbances designed to direct forest change in specific ways. The internally

(endogenously) controlled stages of stand development provide a useful framework for anticipating such changes

together with an understanding of how external (exogenous) forces can further modify such changes.
14

of trees during the stand initiation stage are difficult to

accurately predict. This is due to numerous essentially

random events that influence the timing and spatial distribution of seed dispersal, germination, and seedling survival.

Stand development during this period is subject to great

natural variation, and predictions of stand development

during this stage are usually only specifiable probabilistically (Dey and others 1996a, Johnson and others 2002).

Future stand composition is heavily dependent on the

amount and size of tree reproduction that is pre-established

(i.e., occurring in “advance” of) the time of disturbance.

Whether oaks are successful in attaining dominance during

this stage largely depends on the number and size of oak

seedlings and seedling sprouts present at the time of

disturbance. In turn, this largely depends on site quality, the

occurrence of prior disturbances such as fire or windthrow,

or the natural development of overstory canopy gaps. Site

quality combined with natural or silviculturally reduced

stand densities during the stand initiation stage are closely

connected to conditions that favor the development and

accumulation of oak reproduction under the parent stand.

This accumulation is more persistent on the poorer sites

and where canopy closure is incomplete (Johnson and

others 2002). Under those conditions, some of the oak

reproduction can grow to a large size (fig. 2). When large

advance oak reproduction is released from the inhibiting

effect of the parent stand overstory it responds by producing

one or more long flushes of terminal shoot growth in a

single growing season (Johnson 1979, Johnson and others

2002). In turn, this imparts an initial growth advantage to

the relatively shade-intolerant oaks.

The species composition of trees during the initiation stage

is continually responding to the growth and maturation of

the stand. Early theories of forest succession proposed that

each species modifies the site to make it more favorable for

the establishment and growth of succeeding species.

However, the actual processes can vary widely among the

different types of oak forests. For example, in the Ozark

Highlands of Missouri, the major tree species present at the

time of disturbance become quickly stratified into crown

classes through a process that could be described as

competitive sorting. By the end of this stage, the initially

abundant and ubiquitous sassafras (Sassafras albidum

Figure 1—Stages of stand development occurring after a major disturbance that destroys all or most of

the parent stand (from Johnson and others 2002).

Figure 2—Diameters of roots of oak reproduction measured just

below the root collar in relation to overstory crown cover and site

index in West Virginia forests. The estimates represent the

average of the scarlet, black, white, northern red and chestnut

(Quercus prinus L.) oaks sampled. Estimates are based on a linear

regression model that includes slope percent as a predictor; for

this graph slope percent is held constant at 25. Each data point

represents 7 to 10 trees (adapted from Matney 1974).

Stand

initiation

stage

Stem

exclusion

stage

Understory

reinitiation

stage

Complex

stage

0.8

0.6

0.4

0.2

60 70 80 90

Site

index

35

50

65

80

Crown cover (percent)

Root diameter (inches)
15

(Nutt.) Nees), flowering dogwood (Cornus florida L.), blackgum (Nyssa sylvatica Marsh.), and hickories (Carya spp.)

are largely relegated to the inferior crown classes. Black

oak (Quercus velutina Lam.), white oak (Q. alba L.), scarlet

oak (Q. coccinea Muenchh.) and other oaks by then usually

predominate in the dominant and codominant crown classes.

This competitive sorting process is reflected in each species’

probability of attaining dominance. For a given species, this

probability depends on a tree’s size at the time of the stand

initiating disturbance and site factors (fig. 3).

During the next two stages of stand development, few if any

new trees are added to the overstory. Consequently, the

composition of an even-aged stand at the end of the stand

initiation stage is a good indicator of the species’ richness

of the future overstory. However, a species’ relative abundance at this stage is often a poor indicator of its future

importance. During the ensuing stem exclusion stage,

species composition usually shifts toward the species that

are best adapted to the site and able to attain and hold

dominant or codominant crown positions. Dominance by

oaks at the end of the stand initiation stage therefore does

not always assure their continued dominance. The longerterm outcome varies among the many different types or

classes of oak forests, and is often implicit in ecological

classification systems (Johnson and others 2002).

The stem exclusion stage—In oak forests of the Eastern

United States, crown closure is usually complete by the

beginning of the second decade after a stand-initiating disturbance. By that time, trees have stratified into well-defined

crown classes and natural mortality has changed the initially

clumped spatial distribution of trees to a more random distribution (Rogers 1983). This stage of stand development is

termed the stem exclusion stage because few, if any, new

stems are added to the population of overstory trees (Oliver

and Larson 1996). Mortality rates are high, especially among

trees in intermediate and suppressed crown classes. The

combined growth, competition, and mortality of trees during

this stage produce spatial adjustments in the main canopy

that maintain full utilization of growing space. It is usually

not until after the stem exclusion stage begins that predictive growth and yield models are applicable. During this and

subsequent stages, patterns of stand development and

changes in species composition are more predictable than

during the stand initiation stage.

If oaks are to maintain a position of dominance at this stage

of development, they must outgrow their competitors. Oaks

do this in three ways: (1) through inherently faster growth,

(2) through an initially superior crown position, or (3) through

greater persistence than their competitors. On some sites

in the Ohio Valley, persistence may allow oaks to survive

when other faster-growing species such as yellow-poplar

(Liriodendron tulipifera L.) or red maple (Acer rubrum L.)

succumb to drought (Hilt 1985). Persistence also may allow

more oaks than other species to survive fires, or permit

oaks to eventually grow taller than species of inherently

small stature such as flowering dogwood, which may

temporarily overtop the oaks.

As an even-aged stand matures, its diameter frequency

distribution continually changes. For example, in 10-year-old

upland oak stands of the eastern United States, diameter

distributions form reverse J-shaped curves comprised of

thousands of trees per acre. However, in the absence of

exogenous disturbance, this diameter distribution may

progressively transform itself into a bell-shaped diameter

distribution comprised of few hundred trees per acre by the

time the stand reaches a mean diameter of 8 inches in

diameter at breast height (d.b.h.) (Schnur 1937). On sites

of average quality, this occurs at approximately stand age

85, which is well into the understory reinitiation stage of

development. In the absence of exogenous disturbance,

numbers of trees decline with time through the process of

self-thinning (Johnson and others 2002). During the stem

exclusion stage, about 80 percent of trees die from crowding during self-thinning on average sites (Schnur 1937).

Where markets for small trees exist, thinning stands during

the stem exclusion stage thus can utilize many trees that

would otherwise die from self-thinning. Moreover, the

retained trees accelerate their growth in response to crown

expansion, which in turn is facilitated by the increase in

growing space available to them. Thinning during this stage

also can be used to control species composition and the

quality of future final crop trees.

When oak forests are subject to recurrent low-intensity

disturbances (as in oak savannas maintained by periodic

burning) they may not pass through the stem exclusion

stage. In oak savannas, periodic burning maintains a

relatively open overstory, which in turn maintains relatively

high light intensities in the understory. Although the reproduction of oaks and other species is usually abundant under

these conditions, its recruitment into the overstory is inhibited by recurrent topkill of reproduction unless there is a

Figure 3—Dominance probabilities for advance reproduction

(seedlings and seedling sprouts) of different species in the Ozark

Highlands of Missouri. Dominance probability is defined here as

the probability that advance reproduction of a given initial size will

attain an intermediate-or-larger crown class 21 years after

clearcutting. For each species, probabilities are for 6-foot-tall

advance reproduction with 1-inch basal diameters growing on

southeast- or northwest-facing mid-slopes. Probabilities differ by

aspect and slope position. The five species groups shown are the

predominant hardwoods occurring within this ecoregion.

Probabilities were generated by the regeneration model ACORn

(Dey and others 1996b).

0.6

0.5

0.4

0.3

0.2

0.1

0.0

Hickory Sassafras Blackgum Dogwood Oaks

Dominance probability
16

fire-free period of sufficient duration. Under these conditions,

growth of oak reproduction into the overstory is limited

more by the disturbance regime than by insufficient light.

The fire-tolerant oak reproduction nevertheless responds to

this disturbance regime by slowly accumulating beneath the

savanna understory.

The understory reinitiation stage—During the understory

reinitiation stage, tree reproduction becomes reestablished

beneath the parent stand (fig. 1). In oak forests, this reproduction often becomes a major component of the new stand

that develops after the next stand-initiating disturbance.

Many factors influence which species become established

in the understory and consequently which species are likely

to dominate after a stand-initiating disturbance. In oak

forests, light and soil moisture rank among the most

important of these factors. This is also the stage of stand

development when oak forests usually attain economic

maturity. Consequently, it is a critical period in the development of an oak stand silviculturally. The reproduction that

becomes established (naturally or by human design) largely

determines future stand composition.

Compared to the stem exclusion stage, trees in the main

canopy are larger and fewer in number during the understory reinitiation stage. At this stage of stand development,

some main canopy trees periodically produce large quantities of seed. Large crowns are important determinants of

acorn production and thus the establishment of oak seedlings and the availability of acorns to wildlife. Moreover,

when large trees die they create larger canopy openings

than those created during earlier stages of stand development. The crowns of large main canopy trees also expand

more slowly than they did during earlier stages of stand

development. Consequently, canopy gaps remain open for

longer periods, and this often results in light intensities near

the forest floor sufficient for seedling establishment and

growth. The resultant spatial heterogeneity of the main

canopy creates spatial variation in the amount of light that

reaches the forest floor. This produces microenvironments

favorable for the establishment of oak reproduction that can

develop large root systems, which in turn are correlated with

rapid height growth. Established trees in subordinate crown

positions also benefit from the increased growing space

when an overstory tree dies and creates a canopy opening.

The successional replacement of oaks by more-shade

tolerant species is one of the most pervasive problems

associated with oak silviculture on highly productive sites.

The understory reinitiation stage is therefore a critical time

for intervening silviculturally if the objective is to maintain or

increase the proportion of oak in the future stand. However,

not all oak forests are successional to non-oaks. In the

Ozark Highlands of Missouri and similar dry oak forests in

the Eastern United States, the successional displacement

of oaks is limited by the inability of other hardwoods to

persist in the superior crown classes. Although non-oaks

may aggressively fill canopy gaps immediately after disturbance, their occurrence as canopy dominants is usually

ephemeral. This limitation to persist as a canopy dominant

is determined by each species’ life-history, stature, and

physiological responses to site conditions. Regardless of

the spatial scale of disturbance, the non-oak hardwoods

rapidly drop out of the stand or assume a subordinate

canopy position as competition intensifies with crown

closure (Dey and others 1996a).

Differential dropout rates among species are reflected in

their probabilities of attaining an intermediate-or-better

crown class after clearcutting. For a given initial (preharvest) basal diameter, these probabilities are higher for

oaks than for other hardwoods 15 years after cutting. By

that time, oaks dominate stands and species are stratified

into well-defined crown classes. This outcome is the result

of the collective influence of initial floristics, overstory

inhibition, and competitive sorting processes that control

secondary succession in oak-dominated ecosystems such

as the Ozark Highlands and elsewhere where oak reproduction naturally (intrinsically) accumulates.

Reverse J-shaped diameter distributions are most often

associated with uneven-aged forests, but they also occur in

certain even-aged forests—including those beyond the

stem exclusion stage of development. These stands often

originate following the disturbance of stands comprised of

both shade-tolerant and shade-intolerant species. In subsequent stages of stand development, reverse J-shaped

diameter distributions may evolve through the recruitment

of shade tolerant reproduction into the overstory. Meanwhile, the less tolerant oaks may develop a bell-shaped

diameter distribution (Johnson and others 2002).

The complex stage—In the absence of timber harvesting

or other exogenous disturbances that eliminate the overstory, even-aged stands progress toward the complex stage

(Oliver 1997). During this stage, the natural mortality of

large overstory trees creates canopy gaps, which occur

irregularly in time and space. Gap size is typically equal to

the crown area of one tree or a small cluster of trees.

Because these gaps are relatively large, crown expansion

of trees adjacent to a gap is insufficient to fill the gap. This

lag in crown closure allows subcanopy trees and established reproduction to increase height growth and crown

expansion to fill the canopy gap. As new canopy gaps

occur, they are filled by new age classes of trees. If this

gap-filling process continues in the absence of a standinitiating event, an uneven-aged stand eventually evolves.

The complex stage of stand development includes oldgrowth forests, and Oliver and Larson (1996) originally

termed this stage the old-growth stage. However, there is a

basis for distinguishing between the two. All old-growth

forests are complex, but not all complex forests are oldgrowth. Definitions of old-growth oak forests are usually

based on overstory age, stand disturbance history, and

structural characteristics such as the presence of old trees,

snags, and down wood. The various definitions of old-growth

all assume that human impact on forest development has

been minimal. However, older second-growth forests

(managed and unmanaged) may have complex structures

that do not meet the strict definition of old-growth.

The Development of Uneven-aged Oak Stands

As even-aged stands advance toward the complex stage of

development, trees initially comprising a single age class

gradually evolve into a multi-aged population as a result of
17

the successional processes accompanying stand maturation and gap formation and filling. As stands mature, canopy

gaps become more numerous until the forest forms a

mosaic of old trees and gaps filled with younger trees of

various ages. As reproduction within gaps captures growing

space, stand-wide diameter distributions gradually change.

In the absence of a stand-initiating disturbance, the diameter

distribution may change from bell-shaped to reverse Jshaped. Regardless of the shape of the diameter distribution, the normal evolution of stand structure from even- to

uneven-aged eventually produces an uneven-aged collection of highly dispersed, even-aged groups of trees, each

occupying a relatively small area. Eventually, the various

tree age classes become visually indiscernible.

Although the overall diameter frequency distributions of oldgrowth forests containing oaks often form a reverse-J shape,

the diameters of the oaks themselves may not conform to

that distribution. The way a stand evolves structurally and

compositionally largely depends on differences in the rates

at which co-occurring species of tree reproduction are

recruited into the overstory. Where non-oaks fill most of the

canopy gaps created during the complex stage, those

species will predominate among the smaller trees (e.g., the

left tail of a reverse-J diameter distribution). Depending on

the interaction of site factors with the biological characteristics of the non-oaks, the oaks may or may not ascend to

dominance. The competitive capacity of the oaks largely

depends on site quality and correlatively the tree species

they are competing with. In the more productive oak forests,

a bell-shaped diameter distribution of oaks embedded

within an overall reverse J-shaped distribution reveals an

oak population doomed to displacement by other species.

A bell-shaped distribution for any given species reflects its

failure to grow into the overstory. Oaks often lose this

successional race to other long-lived species that are better

adapted to establishment and survival under shade (e.g.,

sugar maple (Acer saccharum Marsh.)). Bell-shaped oak

diameter distributions thus are harbingers of the oak’s

replacement unless there are disturbances that specifically

favor oak regeneration.

In the Ozark Highlands of Missouri, crown stratification

among the oaks persists into the complex stage (Shifley and

others 1995). There, oaks are usually not successionally

displaced by other tree species and the relative permanence

of oaks is reflected by their relatively high abundance in the

smaller diameter classes, even in old-growth stands. In

mature, relatively undisturbed second-growth forests, the

diameter frequency distributions of the oaks tend to peak in

the smaller diameter classes. In these stands the diameter

distributions of oaks approach the reverse-J shape characteristic of all-aged stands. Diameter distributions of all

species combined (including non-oaks) clearly have a

reverse J-shaped form because the smaller diameter

classes are comprised of relatively large numbers of shadetolerant species such as flowering dogwood and blackgum.

However in that region, the predominant subcanopy species

are largely relegated to the subcanopy (Dey and others

1996a). The relative permanence of the oaks is indicated

by the persistence of diameter distributions that, under

natural conditions, often approach a reverse-J shape. However, specific characteristics of diameter distributions in this

ecosystem, and their natural occurrence and silvicultural

maintenance, depend on species composition and stand

density (Larsen and others 1999, Loewenstein and others

2000).

Exogenous Forces and Disturbance-Recovery

Cycles

When forest disturbance is limited to gap-scale events,

stand development follows the normal sequence (fig. 1).

However, stand-initiating events that eliminate all or most of

the overstory can occur during any stage of stand development. These events return stands to the stand initiation stage

of development. In contrast, smaller-scale (incomplete

stand-scale disturbances) may eliminate only a portion of

the overstory and leave significant numbers of trees standing. Although incomplete stand-scale disturbances change

the stage of stand development, they do not return the

stand to the stand initiation stage. Rather, they create a

mixed stage of stand development. Mixed-stage stands

resulting from natural events often form mosaics of younger

trees developing in large canopy openings interspersed

with patches of older trees. They often form irregularly

spaced tree populations of variable size and age structure.

Mixed-stage stands also can result from various types of

timber harvesting.

Stands in the mixed stage of development are distinguishable from stands in other stages by: (1) the spatial scale of

disturbance, which is greater than gap-scale, and (2) stand

density, which is often below average maximum density.

Relatively young trees also may dominate mixed stage

stands. Low density, highly disturbed stands of all descriptions therefore fall into the mixed stage of development.

Examples of stands in the mixed stage include oak

savannas, stands resulting from indiscriminate timber

harvests, and some silvicultural practices. The latter include

heavily thinned stands, shelterwoods, and some stands

managed by group selection or single-tree selection cut to

low or moderate densities. Oak forests in the mixed stage

of development are ubiquitous because the exogenous

forces that create them are so common.

The complete spectrum of forest developmental stages thus

includes the mixed stage plus the four stages previously

defined. Collectively they represent points in a potentially

endless series of disturbance-recovery cycles initiated by

stand-scale and gap-scale disturbances. These cycles

follow specific sequences determined by the developmental

stage of the stand at the time of disturbance and the type

and spatial scale of disturbance. Disturbance and recovery

cycles provide a conceptual framework for ecological

process and silvicultural practice. However, control of stand

composition and structure is often complicated by unpredictable natural disturbance events that often lie beyond the

direct control of the forest manager. Even when forests are

intensively managed, unplanned and unwelcome disturbances are a part of management reality.

Frequent stand-initiating disturbances can maintain a forest

in the stand initiation stage indefinitely. Such disturbance

regimes were common and extensive in many regions of

North America before European settlement. For example, in

the prairie-forest border region of southwestern Wisconsin,
18

plant communities described as “oak scrub” failed to develop

beyond the sapling stage because of frequent wildfires that

persisted for centuries (Grimm 1984). As long as frequent

fires occurred, the stands of oak scrub persisted. The fires

arrested succession, and thus maintained stands in the

stand initiation stage of development. But by the early

twentieth century, wildfires were largely controlled and

region-wide the oak scrubs quickly responded by developing into closed canopy forests so common in that region

today (Curtis 1959).

SUMMARY AND CONCLUSIONS

A panoply of events and processes, predictable and unpredictable, represent the reality of managing oak forests. Our

current management models are based largely on the

sequence of changes occurring during the initiation stage

through the reinitiation stage of stand development—with

and without timber harvesting or other management practices. Superimposed on those changes are a myriad of

possible unplanned exogenous disturbances that can

abruptly redirect forest development at any time. Moreover,

rapidly emerging interests include managing for old growth,

wildlife and acorn production, biodiversity, various aesthetic

values, and restoring savannas and the other historical plant

communities associated with the oaks. A common denominator to all of these issues is the regeneration of oak forests,

which ultimately determines the sustainability of the oaks

for whatever end. However, the controlling ecological

processes for all of these problems differ greatly among the

various kinds of plant communities dominated by oaks.

Understanding the likely responses of such communities to

both endogenous and exogenous forces is central to

formulating effective management practices and thus to

minimizing unintended consequences.

LITERATURE CITED

Curtis, J.T. 1959. The vegetation of Wisconsin. Madison: University

of Wisconsin Press. 657 p.

Dey, D.C.; Johnson, P.S.; Garrett, H.E. 1996a. Modeling the

regeneration of oak stands in the Missouri Ozark Highlands.

Canadian Journal of Forest Research. 26(4): 573-583.

Dey, D.C.; Ter-Mikaelian, M.; Johnson, P.S.; Shifley, S.R. 1996b.

Users guide to ACORn: a comprehensive Ozark regeneration

simulator. Gen. Tech. Rep. NC-180. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central Forest

Experiment Station. 35 p.

Grimm, E.C. 1984. Fire and other factors controlling the Big

Woods vegetation of Minnesota in the mid-nineteenth century.

Ecological Monographs. 54(3): 291-311.

Hilt, D.E. 1985. Where has all my yellow-poplar gone? Northern

Journal of Applied Forestry. 2(3): 67-69.

Johnson, P.S. 1979. Shoot elongation of black oak and white oak

sprouts. Canadian Journal of Forest Research 9(4): 489-494.

Johnson, P.S.; Shifley, S.R.; Rogers, R. 2002. The ecology and

silviculture of oaks. Wallingford, UK: CABI Publishing. 503 p.

Larsen, D.R.; Loewenstein, E.F.; Johnson, P.S. 1999. Sustaining

recruitment of oak reproduction in uneven-aged stands in the

Ozark Highlands. Gen. Tech. Rep. NC-203. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central

Research Station. 11 p.

Loewenstein, E.F.; Johnson, P.S.; Garrett, H.E. 2000. Age and

diameter structure of a managed uneven-aged oak forest.

Canadian Journal of Forest Research. 30(7): 1060-1070.

Matney, T.G. 1974. Oak regeneration in natural upland oak stands

of West Virginia. Morgantown, WV: West Virginia University.

131 p. Thesis.

Oliver, C.D. 1981. Forest development in North America following

major disturbances. Forest Ecology and Management. 3(3):

153-168.

Oliver, C.D. 1997. Hardwood forest management in the United

States: alternatives for the future. In: Meyer, Dan A., ed.

Proceedings of the twenty-fifth annual hardwood symposium;

1997 May 7-10; Cash, NC: National Hardwood Lumber

Association, Memphis, TN: 45-58.

Oliver, C.D.; Larson, B.C. 1996. Forest stand dynamics. New York:

Wiley. 520 p.

Rogers, R. 1983. Spatial pattern and growth in a Missouri oakhickory stand. Columbia, MO: University of Missouri. 211 p.

Dissertation.

Schnur, G.L. 1937. Yield, stand, and volume tables for even-aged

upland oak forests. Tech. Bull. 560. Washington, DC: U.S.

Department of Agriculture. 87 p.

Shifley, S.R.; Roovers, L.M.; Brookshire, B.L. 1995. Structural and

compositional differences between old-growth and mature

second-growth forests in the Missouri Ozarks. In: Gottschalk,

K. W.; Fosbroke, S. L. C., eds. Proceedings of the tenth central

hardwood forest conference; 1995 March 5-8; Morgantown,

WV. Gen. Tech. Rep. NE-197. Radnor, PA: U.S. Department of

Agriculture, Forest Service, Northeastern Forest Experiment

Station: 23-36.
19

Historical Perspectives Influencing the

Establishment and Sustainability

of Upland Oak Forests
20
21

INTRODUCTION

Understanding the composition, structure and processes

of natural communities of the past may provide valuable

perspectives for developing appropriate forest management

approaches and understanding of current issues such as

oak decline and red oak borer. This does not mean that the

goal of management today must be the restoration of past

conditions; accomplishing that goal may be impossible given

current social, economic or ecological constraints. Knowledge of past conditions may simply inform managers and

decision makers about how much change has occurred in

the landscape and what some of the implications of that

change may be.

The presettlement character of the Ozark Mountain region

has been the subject of considerable and sometimes acrimonious debate. A central issue has been the structure of

the wooded areas, specifically whether they were open

woodlands with herbaceous ground cover or whether they

were closed-canopy forest. A further question involves the

processes that may have led to a previously more open

condition, especially fire frequency. These issues have

substantial implications today for deciding on “appropriate”

management for public lands, for achieving silvicultural

objectives such as oak regeneration, and for understanding

current forest health problems.

The typical view of the vegetation of the Ozark region that

dominated the scientific literature of the first half of the 20th

Century was that most of the non-prairie areas were dense

forest (e.g., Braun 1950). This view was challenged by

Beilmann and Brenner (1951), who presented historic

descriptions and notes of the first land surveyors from the

early 19th Century that provided evidence that much of the

non-prairie area of the Missouri Ozarks was not closed

forest but rather was open woodland often termed “barrens.”

Such areas had trees spread widely enough to allow sunlight

to reach the ground, dramatically increasing the density

and diversity of vegetation in that stratum. In many cases,

particularly in the most open woodlands, the ground-layer

flora was comprised of species typically found in prairies.

Steyermark (1959) issued a spirited and devastating

rebuttal, also quoting from historic sources and surveyor’s

notes to argue his position that the patterns of vegetation

structure in Missouri had changed little from the early

historic time to the present. Many later researchers (Ladd

1991, Nigh and Pallardy 1983, Schroeder 1981) have

provided more support for the Beilmann and Brenner view

than that of Steyermark, and have provided considerable

insight into the role of fire in maintaining the open condition.

Most of the debate over historic condition of oak woodlands

of the Ozarks has been limited to the Missouri portion of the

region. The conclusions reached there may apply to the

Arkansas Ozarks as well, but there may be differences.

While the physiography of part of the Arkansas Ozarks is

the same as that of adjacent areas of Missouri, the Boston

Mountains Subdivision (Foti 1974) does not extend into

Missouri. The Boston Mountains and the Ozark Highlands

have been recognized as separate sections (Foti and

Bukenhofer 1998, Foti and Bukenhofer 1999, Keys and

others 1995) as a result of the significant differences

between them. In turn each of these sections has been

subdivided into subsections, each of which varies somewhat

from the others, in terms of both physical and biological

features (fig. 1). Therefore the descriptions and analyses

presented here will be stated in terms of these finer geographic regions. Subsections are still large enough to contain

many of the GLO survey section corners, but are small

enough to reduce the landscape and plant community

variation within each.

HISTORIC DESCRIPTIONS OF THE ARKANSAS

OZARKS

The most comprehensive map of the vegetation of Arkansas

including the Ozarks in the 19th Century was provided by

Sargent (1884) who mapped pine forest, hardwood forest

and prairie. However, he did not map structural differences

of the forest types.

UPLAND HARDWOOD FORESTS AND RELATED COMMUNITIES OF

THE ARKANSAS OZARKS IN THE EARLY 19TH CENTURY

Thomas L. Foti1

1 Chief of Research, Arkansas Natural Heritage Commission, Little Rock, AR 72201.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Historic accounts of the 19th Century Arkansas Ozarks mention such communities as oak forests, pine forests,

barrens and prairies. I document the region-wide distribution of these types based on data from the first land survey

conducted by the General Land Office (GLO). Structural classes used here include closed forest, open forest, woodland,

savanna, open savanna and prairie or herbaceous-dominated. The analysis is based on subsections of the Ozark

Mountains within Arkansas. These provide areas small enough to represent the landscape level diversity of the Ozark

ecoregion, but large enough to encompass a relatively large number of GLO corners, the basic unit of analysis. As of the

1820s and 1830s, there were differences in the proportion of structural classes within these subsections: the Boston

Mountains had more closed forest than the Ozark Highlands to the north, but communities were more open than today,

probably as a result of recent fire suppression.
22

In the White River Hills Subsection of the Ozark Highlands

Section Schoolcraft in 1818 found cane thickets and forests

of oak, ash, maple, walnut, mulberry, sycamore, hickory,

and elm on alluvial soils. He found prairies of coarse grass

and “scanty” timber on the limestone hills and “bald

mountains” (Rafferty 1996).

Owen (1858) described traveling north from Huntsville,

Madison County, through the Boston Mountains and

Springfield Plateau, saying one travels first through barrens

and then prairie (p. 103). He described the land between

the White River and Bentonville (Benton County) in the

Springfield Plateau as being mainly barrens interspersed

with prairies. He expressed the opinion that the prairies

there had been of much greater extent and had been

reduced by human activity.

Near the White River in the Upper Boston Mountains

Subsection, Gerstacker (1881) described forest rather than

barrens: “There was no trace of fir [cedar]; the mountains

were covered with oak, beech, and hickory . . . It struck me

as extraordinary that the best and most fertile land was on

the hill tops, where in other places, it is generally the worst;

here grew black walnut, wild cherry, with stems sometimes

twenty inches in diameter, black locust, and sugar maple,

trees which generally grow only on the richest soils” (p. 282).

PREVIOUS STUDIES BASED ON GLO SURVEY

NOTES

General Land Office (GLO) notes of the original land survey

of the Ozarks from 1818 to the 1850’s provide quantitative

data on forest composition at that time. Surveyors traversed

the east and south sides of each 6 mile by 6 mile township

and then the east and south sides of each mile-square

section within each township. Direction and distance from

each section corner and quarter-section corner (that is,

halfway along each section side traversed) to two or four

bearing trees were measured and species were identified

(Bourdo 1956). Diameter of each tree was also recorded.

Location of additional line trees and qualitative descriptions

of the topography, soil, forest, and undergrowth along each

mile line surveyed were also recorded. Although there were

no doubt biases in the selection of bearing trees and sometimes errors in measurements, these surveys are the most

complete quantitative data set on vegetation in the early

19th Century.

These surveys offer several ways to characterize vegetation:

(1) Compilation of numbers of trees by species can provide

information on composition, (2) Diameters of bearing trees

can provide estimates of size, (3) Distances to bearing trees

can provide estimates of total density and density by species,

(4) Diameter and distance combined can provide estimates

of basal area or dominance, (5) Mile notes can provide qualitative assessment of land, timber and undergrowth, and

(6) Plat sheets of each township provide maps of notable

features such as streams, prairies, fields and ridgelines.

Figure 1—Subsections of the Arkansas Ozarks referred to in this study, along with the locations of GLO corners

analyzed.
23

Prairies are often well delineated both in the notes and on

plat sheets because these were considered valuable in

land selection decisions. Other measures must be determined from the written data and notes.

Of particular interest in the present study is the density of

trees in the non-prairie areas. Most previous studies have

used methods developed in Illinois to characterize the openness of the areas with trees based on average distance of

bearing trees from the corner (Anderson and Anderson 1975,

Rodgers and Anderson 1979). According to these studies,

savanna is defined as having less than 50 percent canopy

cover of trees, a density of 1 tree per 5 acres to 19 trees

per acre, and average distance from the corner greater than

32 feet (48 links). Open forest varies from 19 to 40 trees

per acre, average distance from 22 feet (33 links) to 32 feet,

and closed forest has a greater density. This definition of

savanna as having an arboreal crown cover of less than

50 percent follows Curtis (1959). Curtis defined the lower

limit of tree density for savanna at 1 tree per acre rather

than 1 tree per 5 acres as Anderson and Anderson did.

As in Missouri, the notes have been used to characterize

the vegetation of the Arkansas Ozarks. In most instances,

these studies were conducted by anthropologists and

archeologists to examine settlement patterns, and therefore

forest composition and structure were secondary to the

main interest.

The dominant trees in the Lee Creek watershed of Crawford

County in the Lower Boston Mountains Subsection in 1837-

1843 were white oak, black oak and post oak, with appreciable numbers of hickory. White oaks most commonly

occurred on steep slopes and higher elevations. Post oaks

were most common on high elevations, upper stream valley

floodplains and intermediate flat uplands. Black oak and

hickories were distributed across all landform types

(Harmon and others 1996, Lockhart and others 1995).

Tree species distribution and density were characterized

within three townships along War Eagle Creek in Madison

County (Upper and Lower Boston Mountain subsections

and Springfield Plateau Subsection) by Joyce (1981). The

study area was mapped into SCS (now NRCS) land

capability classes and average density, dominance and

frequency of all trees within each class were calculated.

Trees of all capability classes except one were classed as

closed forest using criteria of Rodgers and Anderson (1979).

Trees of Class III, having severe limitations that reduce the

choice of crops or require conservation practices or both,

had an average density (18.4 trees per acre) that classed

them as savanna. Approximately 18 percent of the study

points fell within this class. Using a different approach, the

instances in which the surveyor used such terms as “very

little timber” or “no timber of any value or size” in the mile

notes were mapped. This occurred in 20 of the 216 total

miles surveyed, but all of these occurred on the 52 lines

(38 percent) within the Springfield Plateau; none occurred

in the Boston Mountains. She concluded that these were

the actual “barrens” referred to in narratives. The lines of

the Class III areas were often described as “open woods”.

The average distance to trees on the lines with “barrens”

are not provided, nor are the locations of the Class III areas.

Red oaks and white oaks were the most frequently recorded

tree species groups within the study area at 374 and 365

trees respectively, and post oak was third with 145 trees.

The Class III savanna areas that contained 18 percent of

the total trees contained 29 percent of the total post oaks,

0.6 percent of the white oaks and 24 percent of the red

oaks. Thus post oak and the red oaks were more important

than average in these areas and white oak much less

important.

The vegetation of Benton and Washington counties, in the

Springfield Plateau and both Upper and Lower Boston

Mountains subsections, was mapped from the GLO notes

interpreted with the assistance of topographic maps by Miller

(1972). Five generalized communities were interpreted and

mapped: (1) oak barrens (also called open woodlands and

prairie woodlands), (2) lowland forest, associated with

streams, (3) lowland or bottomland prairie, in the floodplain

of major streams, (4) upland forest, and (5) upland prairie.

The oak barrens were “basically grass covered with interspersed trees and brush”. They “were most often located

on relatively flat lands at moderate elevations (1100-1400

feet), or steep rough slopes.” Predominant trees were post

oak and blackjack, with a few occurrences of black oak and

black hickory. Lowland forest was diverse, with red oak, bur

oak, black walnut, ash, slippery elm, shagbark hickory and

others. Species of the prairies were not listed. Upland forest

generally occurred at elevations from 1400-1700 feet. It

was dominated by white oak, black oak, red oak, post oak,

walnut, chinkapin oak, and others. At some places it was

more open, with more xerophytic species, and difficult to

distinguish from barrens without clues from topography.

He concluded, “...it seems that this area was largely Oak

Barrens and Prairie with the forest restricted to the highlands and stream bottoms.” This agreed with the historic

description of Owen (1858).

NEW ANALYSIS OF GLO SURVEY NOTES

The purpose of the current study is to characterize the

original plant community mosaic of the Arkansas Ozarks.

Using field notes of General Land Office surveyors, I analyze

the distributions of dominant species, along with density of

trees along survey lines. Because of the limitations of available data, the study concentrates on structure of vegetation

rather than processes that maintained it, such as fire.

METHODS

In order to provide broad characterization of the vegetation

of the Arkansas Ozarks, I analyzed GLO data along north-tosouth transects. These transects crossed each of the ecological sections and subsections of the Ozark Ecoregion (fig. 1).

This provided a sample of the entire region. I recorded the

following data at each section and quarter section point:

(1) species of bearing trees and (2) average distance in

links to the bearing trees. I summarized mile notes if they

provided insight into community structure (e.g., “barrens”,

“thinly timbered”, “oak-hickory” etc.). I grouped species

recorded in the notes based on reliability of identification

and ecological insight provided. The groups pine, white

oaks and red oaks characterize the overall vegetation of

broad areas. I recorded post oak and blackjack oak separately since they might indicate more xeric areas and/or

more frequently burned areas, beech as an indicator of
24

more mesic areas, and cedar since it is easily killed by fire

and its presence in large numbers could indicate lack of

fire. All other species were recorded as “other”.

The density of trees in the non-prairie areas can be estimated from the surveyor’s data on distance to the bearing

trees. The square of the average distance to bearing trees

in links (1 link=2/3 foot) provides an estimate of the average

area in square feet occupied by each tree (Anderson and

Anderson 1975). From this figure the density of trees per

acre can be calculated. This approach is equivalent to the

correction factor provided by Cottam and Curtis (1956) for

utilizing the point-centered quarter method with two, rather

than four sampled trees. In a few instances the GLO surveyors recorded the distances to 4 bearing trees, generally at

the corners of each township. In calculating density at these

corners, the point centered-quarter method should use the

square of the average distance in feet to determine area

occupied by each tree (Cottam and Curtis 1956). In this

study, basal area was calculated as the average basal area

of the bearing trees multiplied by the calculated density.

Tree density categories used in Illinois (Anderson and

Anderson 1975, Rodgers and Anderson 1979) were used in

this study as well, and have already been stated. The terms

savanna and barrens are used in this analysis to maintain

consistency with the earlier studies cited here. However, an

additional distance criterion was chosen to approximate a

cover of 25 percent using a density half that of the maximum

“savanna” criterion of Anderson and Anderson (1975). This

distance of 67 links or 45 feet gives a density of 9.5 trees

per acre and a canopy cover of 25 percent. A corner with

lower density of trees than this is termed here “open

savanna”. The term “savanna” is favored here over

“barrens” since the former term may be given a simple and

objective definition, whereas no such definition for “barrens”

exists; it may have meant different things to different

observers.

In addition to defining classes using density only, a second

method of calculation is used that includes both density and

diameter. Since the class definitions are actually based on

tree canopy coverage, a given density of small trees will

have less canopy coverage than the same density of large

trees. The older techniques were empirically derived, based

on typical densities and sizes of trees in woodlands of

Illinois. The newer method allows measured diameters and

basal area to be used along with density to provide an

estimate of canopy coverage, which is the actual criterion

on which definitions of savanna or forest are based. It is

derived from formulas and tables widely accepted by

foresters to distinguish “fully stocked” timber stands, that is,

those whose crowns are just touching and therefore are

fully utilizing the available sunlight, from those that are too

open or too dense (Gingrich 1967). Law and others (1994)

used the same equations to provide a graphical technique

for estimating the percentage of total area covered by oak

crowns based on knowledge of basal area, tree diameter

and density. Strictly speaking, these equations and the

resulting charts only apply to oak forests, but both the

authors and most users apply them to mixed forests where

oaks make up the largest component. This applies to the

forests encountered in the GLO surveys of the Arkansas

Ozarks. This method estimates percent canopy coverage

for any combination of tree density, diameter and basal

area, which can then be grouped into classes based on any

desired definition.

Definitions of open wooded communities other than those

cited already have been used. Current efforts to create a

U.S. National Vegetation Classification System by The

Nature Conservancy, NatureServe, The Ecological Society

of America, the Federal Geographic Data Standards

Committee and others do not use the terms savanna or

barrens. The nearest equivalent term is woodland, and is

defined to be a community with a canopy cover of trees of

from 25 to 60 percent (Grossman and others 1998). Nuzzio

(1986) provided an alternative definition of “oak savanna”

as having a tree canopy cover of 10 to 80 percent. Since

the method proposed by Law (1994) produces an estimate

of actual canopy cover, corner points can be grouped and

analyzed using any definition. Therefore, this method was

used in conjunction with these two definitions as well as

with the Anderson definitions.

These techniques for recording and analyzing data minimize

surveyor bias in at least two ways: (1) species identification

is simplified since the species groups could be easily identified by the surveyor, (2) exact locations of corner points are

not a concern since they are grouped by broad but ecologically meaningful ecological regions. Bias in selection of

species would under-represent the species selected against

and over-represent the species selected for. Bias in selection would also overestimate the distance to bearing trees,

since other trees had been ignored. The use of broad

density classes minimizes this effect. The use of several

openness categories simply shifts the corner to the next

lower openness class, rather than a much lower openness

class.

Results are reported by subsection and include frequency

of each species group, average density, and openness

class of woody cover (prairie, open savanna, savanna,

woodland, open forest and closed forest). Nomenclature

throughout follows Smith (1988).

RESULTS

The surveyors of the lines used in this study identified 27

taxa among the 792 trees at 379 corners (table 1). White

oak and black oak were the most common trees named,

making up 29 and 24 percent of the total sample, respectively. Post oak, pine and hickory followed in abundance,

each with over 6 percent of the total trees. The white oak

species group, consisting of white oak and post oak, was

the most abundant, with 41 percent of the total number. The

red oak group, consisting of black oak, blackjack oak,

Spanish oak (southern red oak), red oak, pin oak and

chinquapin oak, followed with 31 percent of the total.

The red oak group (without blackjack oak) was consistently

abundant across all subsections, varying from 38 percent of

the total bearing trees in the Upper Boston Mountains and

35 percent in the Springfield Plateau to 24 to 26 percent in

the other subsections (table 2). Blackjack oak occurred only

in the subsections of the Ozark Highlands, comprising a

maximum of 16 percent of the bearing trees of the Central
25

Plateau Subsection. The greatest abundance of white oak

was in the Central Plateau where it made up 57 percent of

the total trees. Its abundance was intermediate in the Boston

Mountains (32 to 38 percent) and lowest in the Springfield

Plateau and White River Hills (13 to 15 percent). The abundance of post oak was almost the inverse of white oak in

that it was the most named-bearing tree in the White River

Hills (28 percent). It was of intermediate abundance in the

Upper Boston Mountains and Springfield Plateau (11 and

16 percent) and it comprised only 2 percent of the trees in

the Lower Boston Mountains and 1 percent of the trees in

the Central Plateau (table 2).

Pine was most commonly selected in the Springfield Plateau

(14 percent) and was of intermediate abundance in the

Lower Boston Mountains and White River Hills (8 percent

of each). It made up only 1 percent of the Central Plateau

total and was not recorded in the Upper Boston Mountains.

Hickory was recorded in all subsections except the Central

Plateau and reached its highest levels in the Boston

Mountains at 9 percent. Eight cedars were used as bearing

trees only in the White River Hills, making up 4 percent of

the total. Seven beech trees occurred only in the Lower

Boston Mountains, comprising 3 percent of the total.

“Other” trees consistently made up 11 to 15 percent of the

total in each subsection, but comprised only 1 percent of

the total in the Central Plateau (table 2).

The Boston Mountains subsection corners were dominantly

white oak and red oak, but with pine, hickory and other at

the next level in the Lower Boston Mountains and post oak,

hickory and other in the Upper Boston Mountains. The

Central Plateau Subsection was dominated by white oak

with red oak as a distant second and blackjack oak as a

distant third. The White River Hills Subsection was dominated by post oak and red oak, with white oak and other at

the next level, and the Springfield Plateau was dominated

by red oak, with post oak, white oak, pine and other sharing

the next level (table 2).

Average density over the entire study area was 52 trees per

acre (table 3). Density varied from 38 trees per acre in the

Central Plateau to 76 trees per acre in the Upper Boston

Mountains. Density in the Boston Mountains and Ozark

Highlands sections were comparable at 52-54.

As expected, the Anderson method, which used density

alone, generally placed corners into more closed classes

than the Law method, which used both density and diameter

of bearing trees (tables 3 and 4). While Anderson’s method

classed 38 percent of all corners as closed forest, the Law

method classed only 21 percent as closed forest. The open

forest and savanna classes were not greatly different

between the two methods, but the Anderson method

classed only 13 percent of the corners as open savanna,

Table 1—Tree names recorded by the surveyors, with presumed species, analysis group,

and number of individuals recorded

Surveyor name Presumed species Group Total Percent

Ash Fraxinus sp. Other 10 1.3

Beech Fagus grandifolia Ehrh. Other 7 0.9

Black jack (oak) Quercus marilandica Muench. Red oak 26 3.3

Blackgum Nyssa sylvatica Marsh. Other 32 4.0

Black oak Quercus velutina Lam. Red oak 191 24.1

Cedar Juniperus virginiana L. Cedar 8 1.0

Cherry Prunus serotina Ehrh. Other 1 0.1

Chinquapin Castanea pumila (L.) Mill. Other 7 0.9

Chinquapin oak Quercus muehlenbergii Engelm. Red oak 1 0.1

Dogwood Cornus florida L. Other 8 1.0

Elm Ulmus sp. Other 14 1.8

Gum elastic Bumelia lanuginosa (Michx.) Pers. Other 1 0.1

Gum uncertain species Other 3 0.4

Hickory Carya sp. Hickory 48 6.1

Maple Acer sp. Other 7 0.9

Mulberry Morus rubra L. Other 1 0.1

Pin oak Quercus palustris Muench.? Red oak 1 0.1

Pine Pinus echinata Mill. Pine 55 6.9

Post oak Quercus stellata Wang. Post oak 95 12.0

Red, slippery elm Ulmus rubra Muhl. Other 2 0.3

Red oak uncertain species Red oak 21 2.7

Sassafras Sassafras albidum (Nutt.) Nees Other 4 0.5

Spanish oak Quercus falcata Michx. Red oak 10 1.3

Sugar tree Acer saccharum Marsh. Other 3 0.4

Sweetgum Liquidambar styraciflua L. Other 3 0.4

Walnut Juglans nigra L. Other 2 0.3

White oak Quercus alba L. White oak 231 29.2

Total 792 100.0
26Table 2—Number and percentages of tree species groups in each subsection

White Red Post BlackSection/subsection oak oak oak Pine Hickory jack Cedar Beech Other Total

no. % no. % no. % no. % no. % no. % no. % no. % no. % no. %

Lower Boston Mountains 101 38 68 26 6 2 20 8 23 9 7 3 40 15 265 100Upper Boston Mountains 33 32 39 38 11 11 9 9 12 12 104 100

Boston Mountains total 134 36 107 29 17 5 20 5 32 9 7 2 52 14 369 100

Springfield Plateau 21 15 47 35 22 16 19 14 6 4 3 2 18 13 136 100White River Hills 25 13 48 24 55 28 15 8 10 5 9 5 8 4 27 14 197 100Central Plateau 51 57 22 24 1 1 1 1 14 16 1 1 90 100

Ozark Highlands total 97 23 117 28 78 18 35 8 16 4 26 6 8 2 46 11 423 100

Total 231 29 224 28 95 12 55 7 48 6 26 3 8 1 7 1 98 12 792 100

Table 3—Average density, and number and percentages of corners in structural classes using method of Anderson and classes selected to maintainconsistency with previous studiesSection/subsection Density Closed For. Open For. Savanna Open Sav. Prairie Forest Open Total

no./ac no. % no. % no. % no. % no. % no. % no. % no.

Lower Boston Mountains 44.8 49 40 42 34 25 20 6 5 0 0 91 75 31 25 122Upper Boston Mountains 75.7 26 53 17 35 4 8 2 4 0 0 43 88 6 12 49Boston Mountains total 53.7 75 44 59 35 29 17 8 5 0 0 134 78 37 22 171Springfield Plateau 61.8 27 41 11 17 17 26 10 15 1 2 38 58 28 42 66White River Hills 47.4 30 32 20 21 22 23 17 18 5 5 50 53 44 47 94Central Plateau 38.5 12 25 3 6 15 31 13 27 5 10 15 31 33 69 48

Ozark Highlands total 49.9 69 33 34 16 54 26 40 19 11 5 103 50 105 50 208

Arkansas Ozarks total 51.6 144 38 93 25 83 22 48 13 11 3 237 63 142 37 379
27

while the Law method placed 34 percent in this class. There

is no criterion in the Law method for defining prairie, but the

Anderson method placed over 3 percent of the corners in

this structure class. Overall, the Anderson method classed

63 percent of the corners as closed or open forest (table 3),

while the Law method placed about 60 percent of the

corners into the open classes (table 4).

Although the Law method predicted much less closed forest

in each subsection than Anderson, the relative amounts are

similar (tables 3 and 4). Based on the Anderson method,

the Upper Boston Mountains had the greatest percentage

of corners classed as closed forest at 53 percent, with the

Springfield Plateau and Lower Boston Mountains ranked

next. Using the Law method, the Springfield Plateau has

the highest percentage of corners classified as closed

forest at 26 percent, with the Lower Boston Mountains and

Upper Boston Mountains ranked next. Interestingly, the

Upper Boston Mountains, with the highest density, dropped

from first to third in the two rankings. Since the Anderson

method only considers density and Law adds diameter, this

is an indication that the diameters of trees in the Upper

Boston Mountains were smaller than those of the other two

subsections.

The Law method predicted a similar or lower percentage of

open forest in each subsection than the Anderson method,

with Upper and Lower Boston Mountains showing the

greatest declines, and with savanna becoming predominant

in those subsections. Open savanna increased greatly

using the Law method, and is the predominant class in the

subsections of the Ozark Highlands with the highest proportion in the Central Plateau Subsection at 71 percent. The

Anderson method defined prairie only in the Ozark

Highlands subsections.

Combining closed forest and open forest into “forest”, and

savanna, open savanna and prairie into “open”, using the

Anderson method, the Boston Mountains subsections are

dominantly Forest, the Central Plateau is dominantly Open,

and the Springfield Plateau and White River Hills are approximately evenly divided (table 3). Using the Law method, the

Boston Mountains subsections are approximately evenly

divided between forest and open, the Central Plateau is

dominantly open, and the Springfield Plateau and White

River Hills subsections are somewhat more open than

forest (table 4).

Using the cover estimates from Law and the class definitions

of Grossman, the percentage of forest (>60 percent cover)

varied from 40 percent in the Lower Boston Mountains to

15 percent in the Central Plateau, with the other subsections

clustering around 34 percent (table 5). The herbaceous

class of Grossman is equivalent to the open savanna class

Table 4—Number and percentages of corners in structural classes using method of Law and classes selected to

maintain consistency with previous studies

Section/subsection Closed For. Open For. Savanna Open Sav. Forest Open Total

no. % no. % no. % no. % no. % no. % no.

Lower Boston Mountains 28 23 34 28 42 34 18 15 62 51 60 49 122

Upper Boston Mountains 11 22 11 22 16 33 11 22 22 45 27 55 49

Boston Mountains total 39 23 45 26 58 34 29 17 84 49 87 51 171

Springfield Plateau 17 26 9 14 14 21 26 39 26 39 40 61 66

White River Hills 17 18 18 19 20 21 39 41 35 37 59 63 94

Central Plateau 5 10 2 4 7 15 34 71 7 15 41 85 48

Ozark Highlands total 39 19 29 14 41 20 99 48 68 33 140 67 208

Arkansas Ozarks total 78 21 74 20 99 26 128 34 152 40 227 60 379

Table 5—Number and percentages of corners in structural classes using method of Law and classes

of Grossman

Section/subsection Forest Woodland Herbaceous Total

no. percent no. percent no. percent no.

Lower Boston Mountains 49 40 56 46 17 14 122

Upper Boston Mountains 16 33 25 51 8 16 49

Boston Mountains total 65 38 81 47 25 15 171

Springfield Plateau 23 35 18 27 25 38 66

White River Hills 32 34 27 29 35 37 94

Central Plateau 7 15 8 17 33 69 48

Ozark Highlands total 62 30 53 25 93 45 208

Arkansas Ozarks total 127 34 134 35 118 31 379
28

used before, except that a canopy cover of exactly 25 percent is classed as woodland under the Grossman definition

and herbaceous under the open savanna definition used

here.

Using cover estimates from Law and class definitions of

Nuzzio, the highest percentage of forest (>80 percent cover)

was 29 percent in the Upper Boston Mountains, with Lower

Boston Mountains and Springfield Plateau closely following

(table 6). The Nuzzio herbaceous class (<10 percent cover)

varied from 44 percent in the Central Plateau to 5 and 8

percent in the Lower and Upper Boston Mountains,

respectively.

The average cover of corners described as “barrens” or

“thinly timbered” by the surveyors was 28 percent and the

average density was 39 trees per acre. These indicate

open conditions but not greatly so.

DISCUSSION

The criteria proposed by Law and others are based on

those widely accepted in forest management and therefore

should be preferred, particularly for distinguishing closed

forest from open forest. These criteria become more difficult

to implement as the structure becomes more open, however, partly because the structure of the charts allows less

precise definition of lower canopy coverage. Also, there is

no criterion under this method for distinguishing prairie.

This method generally defines more open communities for

a specified density than the criteria proposed by Anderson

and Anderson, but where tree diameters are large it can

predict more closed communities.

Guldin and others (1999) analyzed Ozark and Ouachita

timber by ecological Section based on USDA Forest

Inventory and Analysis data. They showed a density of

trees greater than 6 inches d.b.h. of 153 per acre in the

Boston Mountains Section and 116 per acre for the Ozark

Highlands Section. Density of trees in the early 19th Century

in these Sections was 54 and 50 per acre, respectively.

Although the modern and GLO numbers are not strictly

comparable, this indicates a substantial increase in density

of trees in the Ozarks over this period. This agrees with

others such as Ladd (1991), who attributed this increase to

fire suppression.

The various methods and class definitions generally agree

that the Upper and Lower Boston Mountains subsections

and the Springfield Plateau Subsection had more closed

forest than the other subsections but that the amount,

particularly based on the Law method, was much less than

today. The subsections of the Ozark Highlands all had high

coverage of the most open communities (open savanna

and herbaceous).

Based on findings of earlier studies (Joyce 1981, Miller

1972), it is likely that the location of transects used in this

study causes an overestimate of the amount of forest in

relation to open structure in the Springfield Plateau, in that

both of those studies demonstrated more open conditions

than data from transects in this study. Both of their study

areas were located west of the westernmost transect in this

study, where the Springfield Plateau is broader and more

level than the places where these transects crossed. The

broader and flatter sites, combined with the level-bedded

strata of the Ozark Mountains, would have been more

exposed to wind, more droughty and more susceptible to

frequent fire. The high amounts of pine along the transects

studied here are indicative of steep, cherty slopes in

contrast to the often level plains underlain by limestone

further west.

Although geologic substrate and topography exert control

directly over plant communities of the Ozarks, they probably

also exert indirect control through precipitation since the

Upper Boston Mountains are higher and moister than the

other subsections and have up to 10” per year greater precipitation than subsections to the north within the Arkansas

study area.

LITERATURE CITED

Anderson, Roger C.; Anderson, M.R. 1975. The presettlement

vegetation of Williamson County, Illinois. Castanea 40: 345-

363.

Beilman, A.P.; Brenner, L.G. 1951. The recent intrusion of forests

in the Ozarks. Annals of the Missouri Botanical Garden 38. St.

Louis, MO. pp 261-282.

Bourdo, E.A., Jr. 1956. A review of the General Land Office survey

and of its use in quantitative studies of former forests. Ecol. 37:

754-768.

Table 6—Number and percentages of corners in structural classes using method of Law and classes

of Nuzzio

Section/subsection Forest Savanna Herbaceous Total

no. percent no. percent no. percent no.

Lower Boston Mountains 33 27 83 68 6 5 122

Upper Boston Mountains 14 29 31 63 4 8 49

Boston Mountains total 47 27 114 67 10 6 171

Springfield Plateau 18 27 36 55 12 18 66

White River Hills 22 23 46 49 26 28 94

Central Plateau 5 10 22 46 21 44 48

Ozark Highlands total 45 22 104 50 59 28 208

Arkansas Ozarks total 92 24 218 58 69 18 379
29

Braun, E. Lucy. 1950. Deciduous forests of Eastern North America.

Cottam, Clarence; Curtis, John T. 1956. The use of distance

measures in phytosociological sampling. Ecol. 37: 451-460.

Foti, Thomas L. 1974. Natural divisions of Arkansas. In: Ark. Natural

Area Plan, Ark. Dept. of Planning, Little Rock, AR. 248 pp.

Foti, Thomas L.; Bukenhofer, George A. 1998. A description of the

sections and subsections of the Interior Highlands of Arkansas

and Oklahoma. Journal of the Ark. Acad. Of Sci., Vol. 52, pp.

53-62.

Foti, Tom; Bukenhofer, George. 1999. Ecological units of the

Highlands. In Ozark-Ouachita Highlands Assessment: terrestrial

vegetation and wildlife. Report 5 of 5. Gen. Tech. Rep. SRS-35.

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

Southern Research Station, pp1-6. Chapter 1.

Gerstacker, Frederich. 1881. Wild sports in the Far West. J. W.

Lovell, New York.

Gingrich, Samuel F. 1967. Measuring and evaluating stocking and

stand density in upland hardwood forests in the Central States.

Forest Science. 13(1): 30-38.

Guldin, James M.; Thompson, Frank R.; Richards, Lynda L.;

Harper, Kyra C. 1999. Status and trends of vegetation. In

Ozark-Ouachita Highlands Assessment, Terrestrial Vegetation

and Wildlife. USDA Forest Service, Southern Research Station,

GTR SRS-35, Asheville, NC. pp. 21-72. Chapter 3.

Harmon, Debbie; Lockhart, Jami J.; Sabo, George, III. 1996. From

surveyor’s chains to satellites: a study of historic environmental

change and land use on the Lee Creek unit of the Ozark

National Forest, Crawford and Washington Counties, Arkansas.

Arkansas Archeological Survey Project 955, Fayetteville. 56 pp.

plus appendices.

Joyce, Jane S. 1981. A settlement pattern study of the War Eagle

Creek region, Madison County, Arkansas, during the pioneer

period. Fayetteville, AR: University of Arkansas. 101 pp.

Unpublished M.A. thesis.

Keys, James E., Jr.; Carpenter, Constance A.; Hooks, Susan L.

[and others]. 1995. Ecological units of the Eastern U.S., first

approximation. (map and booklet of map unit tables) Atlanta,

GA. USDA Forest Service. 82 pp.

Ladd, Douglas. 1991. Reexamination of the role of fire in Missouri

oak woodlands. In: Proceedings, Oak Woods Management

Workshop; Charleston, IL: Eastern Illinois University. pp. 76-80.

Law, Jay R.; Johnson, Paul S.; Houf, Garry. 1994. A crown cover

chart for oak savannas. Technical brief, USDA Forest Service,

North Central Forest Experiment Station, U MO, Columbia MO.

6 pages. (note: available at http://www.ncrs.fs.fed.us/pubs/tb/

tb2/techbrf2.html).

Lockhart, Jami J.; Hilliard, Jerry E.; Sabo, George, III; Weddle,

Deborah A. 1995. The evolution of human ecosystems in the

Ozark National Forest, a pilot study of the Lee Creek unit.

Arkansas Archeological Survey Project 876, Fayetteville.

125 pp.

Miller, Henry M. 1972. A vegetal reconstruction of early historic

northwest Arkansas. Fayetteville, AR: University of Arkansas.

123 pp. Unpbl. Ph.D. dissertation.

NOAA. 1980. Local climatological data. Nat. Ocean. Atmos.

Admin. Asheville, NC.

Nuzzio, Victoria A. 1986. Extent and status of Midwest oak

savanna: presettlement and 1985. Natural Areas Journal. 6(2):

6-36.

Owen, David D. 1858. First report of a geological reconnoissance

(sic) of the northern counties of Arkansas made during the

years 1857 and 1858. Johnson and Yerkes, State Printers,

Little Rock. 256 pp.

Rafferty, M.D. 1996. Rude pursuits and rugged peaks, Schoolcraft’s

Ozark Journal 1818-1819. The University of Arkansas Press

Fayetteville, AR. 170 pp.

Rodgers, Cassandra S.; Anderson, Roger C. 1979. Presettlement

vegetation of two prairie peninsula counties. Botanical Gazette

140(2): 232-240.

Sargent, Charles S. 1884. Map of Arkansas showing the distribution of forests. In A report on the forests of North America.

Tenth Census of the United States. Vol. 9. Washington.

Schroeder, Walter A. 1982. Presettlement prairie of Missouri.

Natural History Series, No. 2, Missouri Department of

Conservation, Jefferson City. 37 pp.

Smith, Edwin B. 1988. An atlas and annotated list of the vascular

plants of Arkansas. Second ed., privately published. 489 pp.

Steyermark, Julian A. 1959. Vegetational history of the Ozark

forest. The University of Missouri Studies. Columbia, MO.

138 pp.
30

INTRODUCTION

Prehistoric Native Americans entered North America more

than 12,000 years ago. Archeologists and paleoecologists

have documented the important role Native Americans

played in shaping forest ecosystems through use of fire,

harvest of timber, tree stand management, plant domestication, and agricultural land clearing (Delcourt 1987, Denevan

1992, Hammett 1992). As a result, we now believe that

European explorers entered environments already modified

by native land use practices (Cronon 1983, Silver 1990).

Cooperative efforts by the Arkansas Archeological Survey

and the Ozark-St. Francis National Forests begun in 1993

provide an opportunity to examine these issues in detail

(Harmon and others 1997, Lockhart and others 1995). We

discuss here research that addresses one issue in particular: How did prehistoric Native American land use practices

impact Ozark forest ecosystems?

LEE CREEK STUDY AREA

Our study area in the Lee Creek Unit of the Ozark National

Forest covers an area of approximately 404 square kilometers located in the Boston Mountains province of the

Ozark Plateau (fig. 1). Narrow, V-shaped valleys bordered

by steep slopes and vertical bluffs rise from clear, gravelbedded streams. Flat ridge tops separate adjacent valleys.

The vegetation today is upland hardwood dominated by oak

and hickory with scattered pine and brushy undergrowth.

Lee Creek and its tributaries flow in a southwesterly direction from higher elevations in the northeastern corner of the

study area. Valley bottoms are less than a kilometer wide.

Sediments are thin and rocky, with narrow bands of moderately fertile soils extending along the streams. Bottomland

floods create conditions suitable for limited agriculture.

ENVIRONMENTAL AND CULTURAL HISTORY

Three major climate events affected the region during the

period of human occupation: (1) the Pleistocene/Holocene

transition, which began about 12,000 years ago and

brought an end to Ice Age conditions; (2) the mid-Holocene

Climatic Optimum or Hypsithermal episode from 9,000 to

about 5,000 years ago, during which warmer and drier

conditions prevailed; and (3) the Late Holocene Neo-Boreal

episode, which began about 500 years ago and brought

cooler and less stable conditions. Tree rings studies indicate that our region experienced frequent and protracted

drought conditions during the Neo-Boreal era (Cleveland

and Stahle 1996).

Known archeological sites occur in our study area in sufficient number and distribution to permit study of prehistoric

land use strategies, especially for the period covering the

past 5,000 years (Harmon and others 1997, Lockhart and

others 1995). Evidence from these sites and others located

in the Pine Mountain area farther downstream (Raab 1976,

Trubowitz 1980) makes it possible to identify general trends

of prehistoric cultural development.

THE FOREST AS A RESOURCE:

FROM PREHISTORY TO HISTORY IN THE ARKANSAS OZARKS

George Sabo III, Jami Joe Lockhart, and Jerry E. Hilliard1

1 Archeologist, Computer Services Program Coordinator, and Research Associate, Arkansas Archeological Survey, Fayetteville, AR 72704,

respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Study of past human land use in the Lee Creek Unit of the Ozark National Forest challenges the existence of

“pristine” forests predating the arrival of historic Americans. The distribution of early nineteenth century American

settlements corresponds closely to the distribution of late prehistoric Native American archeological sites. One explanation

for this finding is that pioneer American settlers occupied lands already altered by earlier Native Americans. To test this

hypothesis, we used historical accounts and Geographic Information Systems approaches to develop a model of late

prehistoric land use, emphasizing agricultural field clearing practices and wood consumption for building and fuel use. The

extrapolated impacts of these Native American activities may well account for the forest environment encountered by

historic American settlers. The major implication of this study is that long-term dynamics of forest ecosystems are best

understood when human populations are included as components of those systems.

Figure 1—Location of the Lee Creek Unit.
31

The first human occupants of the Lee Creek valley arrived

about 12,000 years ago, when a late Pleistocene spruce-jack

pine boreal forest was giving way to an early Holocene oakhickory forest (Delcourt and Delcourt 1981). The solitary

archeological site dating to this era represents the presence

of small groups of mobile hunters and gatherers who probably did not have much impact on local environments.

The region remained sparsely populated during the next

few thousand years; only two sites have been discovered

that date to the mid-Holocene era. The region had been

encroached by open oak savannah when those sites were

occupied (Delcourt and Delcourt 1981). Deer and other

forest animals, fish and shellfish, birds, and wild plant foods

including nuts, seeds, and fruits were the primary food

resources supporting those groups. A slight increase in

local environmental impacts probably resulted from the

increased use of plant foods.

Native populations expanded after 5,000 years ago, as

indicated by the presence of 48 sites in the study area that

were occupied between 5,000 and 500 years ago. We

recognize three types of sites: rock shelters (n=18) used for

temporary camping, burial of the dead, and storage of

perishable foodstuffs; small, special-purpose sites (n=15)

located in a wide variety of settings; and residential sites

(n=15) covering areas larger than 1,000 square meters that

were occupied year-round by several extended families for

long periods of time. The people who lived at these sites

were engaged in the production of locally domesticated

plants including lambs-quarters, little barley, knotweed,

sumpweed, and several varieties of squashes. Corn, a

tropical cultigen domesticated in Mexico, was also grown in

small amounts. The advent of plant domestication, coupled

with significant population growth, increased the level of

human impact on the forest ecosystem.

Northwest Arkansas was part of the Osage Indian hunting

territory during the late seventeenth and early eighteenth

centuries. French hunters and traders entered the region

toward the end of that period, and Euro-American settlement began after Fort Smith was built along the Arkansas

River in 1817. A series of treaties signed during the following decade forced the removal of Native Americans from

the region.

METHODS

Our investigation of the environmental impacts of past land

use strategies in the Lee Creek valley involves three tasks:

(1) creation of environmental models using Geographical

Information System (GIS) techniques; (2) reconstruction of

past land use strategies from archeological and historical

evidence; and (3) analysis of the geospatial impacts of reconstructed land use practices on Ozark forest ecosystems.

Several environmental models were developed as GIS data

layers for this project: elevation, slope, aspect, hydrography,

soils, and line and witness tree locations recorded by nineteenth century General Land Office (GLO) surveyors. These

initial models were used to create a series of derived

products. Elevation and slope gradients and hydrography

were used to create a terrain model based on a drainage

class technique that specifies ten landforms. The addition

of a fourth variable — aspect (defined in terms of four 90o

quadrants plus a fifth category for flat surfaces) — yields an

expanded model comprised of 50 landform classes. The

accuracy of both models was confirmed through extensive

testing in which the expected and actual distributions of

several cultural and environmental features were compared

(Lockhart and others 1995: 8-20). For the sake of simplicity,

we use the ten-class model here (fig. 2).

Analysis of archeological data within an “adaptation type”

model provides a way to reconstruct ancient land use patterns with respect to past environmental features (Sabo and

others 1989:1-2). These models define relationships that

connect social, technological, and economic practices with

the abundance, distribution, and predictability of environmental resources such as food and raw materials. Two

prehistoric adaptation types are represented in the archeological data from the Lee Creek Unit: semisedentary hunting/

gathering/gardening and semisedentary agriculture. In both

of these models, local groups occupy year-round base

camps, but part of the resident group spends part of each

year engaged in seasonal subsistence pursuits elsewhere.

Geographical Information System applications are used to

reconstruct the spatial impacts of past land use strategies

on Ozark forest ecosystems. Here we illustrate the use of

historical analogs and catchment analysis to estimate

environmental impacts in the Lee Creek study area.

THE FOREST AS A RESOURCE

Let us turn now to an examination of three prehistoric land

use practices to estimate their impact on Ozark forest

environments.

Figure 2—Terrain model for the Lee Creek Unit showing ten

landform classes top to bottom: lower, middle, and upper stream

floodplains; lower, middle, and upper stream slopes and bluffs;

intermediate and high slopes and bluffs; intermediate and high flat

uplands.
32

The first practice is timber harvest for construction purposes.

In excavated dwelling structures in northwest Arkansas,

hardwoods such as red oak, white oak, and hickory were

preferred for wall posts, which typically measured 10-30 cm

in diameter. These structures average four to eight meters

on a side and required about 50 stems for the walls, and

half again as many stems for the roof timbers, interior roof

supports, and interior bench supports.

Wood charcoal from archeological hearth features provides

evidence of a second practice for firewood collecting. A

breakdown by species of samples recovered from excavations at the Dirst site along the Buffalo National River

reveals that oak species were by far the most preferred fuel

woods, followed by sycamore, pine, hickory, and maple

(Guendling and others 1992, Sabo and others 1990).

The advent of gardening and, later, more intensive field

agriculture created a need for cleared areas, possibly in

excess of land cleared through timber harvest and firewood

collecting. We’ll consider this hypothesis shortly.

How can we estimate the cumulative environmental impacts

resulting from these three activities over several centuries

of human occupation in the region? That is the question to

which we turn next.

PREHISTORIC LAND USE IN GEOSPATIAL

PERSPECTIVE

Since early historic Osage lifeways correspond to both of

our target adaptation types, we can search historical

records for useful analogs to the more ancient ecosystems.

Several visitors to Osage settlements during the early

nineteenth century left observations indicating that wood,

water, and fertile soils were important limiting factors in

settlement location choices. For example, in 1819 Thomas

Nuttall observed: “The river lands are no less extensive and

luxuriant between the Verdigris and the Arkansa, and would

apparently support a condensed settlement; but the prairies

will only admit of settlements along their borders, in consequence of a scarcity of wood and water” (Nuttall 1999:211-

12). Victor Tixier described an Osage village he visited in

1839: “Hunting lodges had been erected in a bend of the

stream. Water and wood were near at hand” (McDermott

1940:159).

To quantify wood consumption and land clearing requirements, it is necessary to consider settlement population

size. Here again, historical sources provide guidance. On

December 30, 1819, Henry Rowe Schoolcraft happened

upon three recently abandoned Osage hunting camps

along Swan Creek in southwest Missouri, in an environmental setting similar to the Lee Creek Valley. Schoolcraft

described these camps as “all very large, arranged with

much order and neatness, capable of quartering probably

100 men each” (Rafferty 1996:78). Using a conservative 1:4

ratio of hunters to overall population, we estimate a group

size of 400 individuals. A similar contingent of Little Osages

encamped near Fort Osage along the Missouri River were

living in 60 lodges “circular in form, not more than ten or

fifteen feet in diameter” when they were visited in 1811 by

Henry Marie Brackenridge (Brackenridge 1814:217). These

numbers suggest that each family of 4-8 members occupied

its own lodge. The total floor area of those lodges, estimated

at 480 to 985 square meters, could be accommodated at

our large open archeological sites in the Lee Creek study

area.

Since Lee Creek is narrower than the Verdigris and Missouri

Rivers along which Nuttall’s and Brackenridge’s observations were made, we need to evaluate the 400-person

village size in relation to estimates of regional population

densities. For the early historic era, these range from 0.05

and 0.64 persons per square kilometer (Guyette and others

2002). These densities translate to a range of 20 to 259

people for our study area. The late prehistoric population in

the Lee Creek valley undoubtedly was distributed among

several settlements, so the existence of 15 large, permanent

settlements is consistent with the higher population density

figure, considering the likelihood that only a few of those

sites were occupied simultaneously. Furthermore, the Native

American occupants of that area made seasonal visits to

other areas, such as the prairie-plains region to the west,

for economic activities that included hunting buffalo. These

considerations suggest that our study area probably was

“home” at any particular time to several extended families

representing a total population of no more than 250 people.

The use of conservative wood consumption and land clearance estimates is appropriate in view of seasonal fluctuations affecting the resident population size.

What was the annual timber consumption of this community?

Unfortunately, our otherwise keen observers of nineteenth

century Osage village life fail us on this question, necessitating an appeal to other sources of information. Robert

Heizer’s (1963) calculation of 83 pounds of wood per family

per day for Native Americans living in northern California

(where comparable annual temperature ranges prevail and

where hardwoods were likewise the major fuel source)

provides a yearly per capita figure of 2.3 tons that seems

reasonable for our study area. From this, the annual firewood requirement for 250 people is calculated at 575 tons.

Using U.S.D.A. figures of ten cords of mixed hardwood per

acre and with each cord weighing about 1.5 tons (Graves

1919), our 575 tons represents the timber resources of

roughly 38 acres.

How much wood was required for construction and for

manufacture of other items? If each dwelling required about

75 stems (adding roof and bench supports to the 50 wall

stems mentioned previously), then the 40 structures

required to shelter 250 people would consume about 3,000

stems. Using modern figures from the Lake Winona

Research Natural Area in Arkansas, timber of 10-30 cm

diameter in this quantity would clear an additional 12 – 15

acres at 250 stems per acre, more or less (Fountain 1991).

These structures, however, would not need to be replaced

every year. French colonists at Arkansas Post complained

in the early eighteenth century that wall posts set into the

damp, frequently flooded sediments of eastern Arkansas

had to be replaced every eight to ten years, so we can

estimate that the wall posts of structures built along Lee

Creek would last at least that long. Even with additional

timber requirements for ancillary structures, dugouts, and
33

other items, the total quantity of timber required for

construction and manufacturing represents but a small

fraction of the annual firewood requirement. We therefore

decided to use the 575-ton figure as a conservative

estimate of total annual wood needs for all purposes.

The area of Ozark forests impacted by this magnitude of

wood harvest can be calculated through site catchment

analysis. That is, an occupied settlement has a surrounding

“catchment area” from which residents harvest resources

like firewood. The overall dimensions of site catchments are

usually set in relation to the maximum distance people are

willing to travel to acquire those resources. How far were

Osages willing to walk to collect firewood? Again, our keen

observers don’t provide exact figures, but in 1819 Thomas

Nuttall accompanied an Osage hunter “about 9 or 10 miles

over the alluvial lands of the Grand river” (Nuttall 1999:211).

They were not burdened by heavy loads of firewood, but it

would be unwise to underestimate the capacity of Osage

women who, according to Nuttall, were “accustomed to

perpetual drudgery,” and were “stouter and lower in stature

than the men” (Nuttall 1999:216). Still, it seems unlikely that

the range for firewood collecting would have extended

beyond one-third of the range of fast moving hunters. A

5-kilometer catchment area surrounding each Lee Creek

settlement seems reasonable in view of these considerations, and is consistent with worldwide ethnographic data

on human foraging ranges.

A second issue concerns the overall shape of the catchment

area. Most applications use a “concentric circle” approach,

which assumes that a person can move with equal ease in

every direction. That is not the case in the highly dissected

Ozark terrain of the Lee Creek valley. Our solution involves

defining catchments in relation to estimated travel costs,

where costs accumulate in relation to incremental increases

in the slope angle of the ground. Put simply, it is more

difficult or “costly” to travel up (or down) a steep slope than

it is to travel across flat land.

Catchment areas were calculated for three of the large,

open sites in the Lee Creek Unit. All of the Late Holocene

semisedentary sites (representing both hunting-gatheringgardening and agricultural adaptation types) occur on the

lower and middle stream valley classes of our terrain model.

Therefore, we selected one site from the lower stream

valley class, a second site from the middle stream valley

class, and a third site from the boundary where these two

units join.

The areas encompassed within 1-, 3- and 5-kilometer

catchments surrounding these sites are shown in figure 3

(see also table 1). These catchments yield fairly consistent

estimates on the availability of local wood supplies: the

1-kilometer catchments contain less than four years’ supply,

the 3-kilometer catchments expand the supply to one or two

decades, and the 5-kilometer catchments contain timber

sufficient to meet demands for roughly four decades, or

about two generations.

We are not suggesting, of course, that Native American

groups in the Lee Creek valley were clear-cutting 38 acres

of timberland per year. More likely, they were cutting some

trees to acquire building timbers and wood for other manufacturing purposes (i.e., dugouts), collecting deadwood to

use as fuel, and culling both young and old trees from nut

tree groves to increase the room for crown breadth development of productive middle-aged trees – thereby producing

additional firewood supplies. The immediate result of these

activities was thinning of local tree stands, but over several

years cleared areas were likely produced, especially in the

bottomlands surrounding larger settlements. The number

and distribution of large open sites in our study area therefore probably represents a series of generational relocations

Figure 3—Catchment areas for three archeological sites in the Lee

Creek Unit calculated in relation to travel cost surfaces. The light

gray (smaller) areas represent 1-km catchments, the intermediate

gray areas represent 3-km catchments, and the dark gray (larger)

areas represent 5-km catchments.

Table 1—Catchments and estimated wood

supplies for archeological sites in the Lee

Creek Unit

Catchment Wood

Site range Area supply

km acres years

3CW42 1 133.3 3.5

3 832.2 21.7

5 1,675.9 43.7

3CW119 1 15.8 < 1.0

3 512.7 13.4

5 1,521.3 39.7

3CW132 1 216.3 5.6

3 785.9 20.5

5 1,499.0 39.1
34

prompted by exhaustion of local wood supplies within

adjacent catchment areas. The distribution of these sites

in addition to the time span they represent (roughly 4,000

years) further suggests a cyclical pattern of movement in

which abandoned sites were reoccupied following reestablishment of forest vegetation.

Under a hunting, gathering, and gardening economy,

requirements for cleared land would be modest; a figure of

0.25 acres per person per year is a reasonable approximation. At this amount our 250-person community might

require as much as 62.5 acres of garden space. With the

emergence of more intensive field agriculture, cleared land

requirements in the Lee Creek valley, as elsewhere in

eastern North America, increased to something on the

order of 0.5 acres per person per year. This produced an

overall requirement for as much as 125 acres of croplands,

coupled with an increased rate of soil exhaustion.

To determine annual requirements for cleared land, we also

need to consider the effects of field rotation. We can never

be certain about prehistoric rotation cycles; however, many

Southeastern and Southern Plains groups shifted to new

fields after old ones had been used for about five years

(Moore 1987:143-44, Silver 1990:50-51). If one of every

five fields were rotated in this manner in any given year,

then old fields would have at least a 25-year recovery

period – a time interval during which trees would grow to

about the right size for use in dwelling construction but

would not have grown so large that they would be difficult

to remove (Silver 1990:50). At this rate, annual field

expansion requirements would range from roughly 12.5

acres (gardening) to 25 acres (agriculture) per year. If these

estimates correspond to prehistoric circumstances in the

Lee Creek valley even approximately, then the annual

requirement for newly cleared lands for either gardening or

field agriculture would fall well within the annual amounts of

land from which firewood was collected.

In sum, these estimations suggest that firewood collecting

by the late prehistoric occupants of the Lee Creek valley

produced the single most extensive impact on local forest

resources. Garden and agricultural field production were

probably embedded within the areas cleared as a result of

timber harvest and firewood collecting. The calculated

catchment areas suggest that wood supplies were obtained

from the bottomlands, terraces, and adjacent hill slopes

along Lee Creek. Over several generations, a community of

250 persons would have cleared extensive tracts of bottomlands in an area the size of the Lee Creek Unit, even with

cyclical return to favored sites.

FROM PREHISTORY TO HISTORY

The extent of prehistoric land clearance reconstructed here

suggests that Euro-American settlers entered Ozark forests

that were already modified by previous groups of Native

Americans, who had been living in the region for many

thousands of years. Plotting the locations of the first white

settlements on a map along with the late prehistoric sites

provides additional support for this suggestion (fig. 4). The

major implication of this study is that long-term dynamics of

forest ecosystems are best understood when human

populations are included as components of those systems.

Figure 4—Late prehistoric Native American sites (gray squares)

and early historic Euro-American sites (black circles) in the Lee

Creek Unit.

ACKNOWLEDGMENTS

Partial funding for this research was provided by the OzarkSt. Francis National Forests through a cost-share arrangement with the Arkansas Archeological Survey. The authors

bear responsibility for any shortcomings in the content of

this article.

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chains to satellites: a study of historical environmental change

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Forest, Crawford and Washington Counties, Arkansas.

Arkansas Archeological Survey Project 955 Final Report. 59 p.

Heizer, R.F. 1963. Domestic fuel in primitive society. Journal of the

Royal Anthropological Institute of Great Britain and Ireland 93:

186-94.

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evolution of human ecosystems in the Ozark National Forest: a

pilot study of the Lee Creek Unit. Arkansas Archeological

Survey Project 876 Final Report. 125 p.

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Moore, J.H. 1987. The Cheyenne nation: a social and demographic

history. Lincoln: University of Nebraska Press. 390 p.

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during the year 1819. Fayetteville: University of Arkansas

Press. 361 p.

Raab, L.M. 1976. Pine Mountain: a study of prehistoric human

ecology in the Arkansas Ozarks. Arkansas Archeological Survey

Research Report No. 7.

Rafferty, M.D., ed. 1996. Rude pursuits and rugged peaks:

Schoolcraft’s Ozark journal 1818-1819. Fayetteville: University

of Arkansas Press. 170 p.

Sabo, G., III; Early, A.M.; Rose, J.C. [and others]. 1989. Human

adaptation in the Ozark-Ouachita Mountains. Arkansas

Archeological Survey Research Series No. 31. 296 p.

Sabo, G., III; Guendling, R.L.; Limp, W.F. [and others]. 1990.

Archeological investigations at 3MR80-Area D in the Rush

Development Area, Buffalo National River, Arkansas. Vol. I.

Southwest Cultural Resources Center, Professional Papers No.

38, Sante Fe. 353 p.

Silver, T. 1990. A new face on the countryside: Indians, colonists,

and slaves in south Atlantic forests, 1500-1800. Cambridge:

Cambridge University Press. 204 p.

Trubowitz, N.L. 1980. Pine Mountain revisited: an archeological

study in the Ozarks. Arkansas Archeological Survey Research

Report No. 23.
36

INTRODUCTION

The forests and the people of the Missouri Ozarks experienced waves of change from the 1880s to the 1940s. During

this era large-scale timber operations moved into the region

and began to harvest timber. After the collapse of the timber

industry local Ozarkers worked to re-establish an independent society free of outside interference. After a decade of

failed efforts the federal and state governments finally

succeeded in establishing a presence in the Missouri

Ozarks during the 1930s. This entire succession of events

occurred in an atmosphere of tension between Ozarkers

and outsiders over the control of natural resources and the

character of Ozark society.

PRE-TIMBER ERA

Ozarkers’ heritage shaped the society that existed before

the arrival of the timber industry. Many residents of the region

traced their lineage through the upland South to Scotland.

Scots-Irish who migrated to the United States in the 18th

century brought a pragmatic approach to life and a distrust

of authority. As residents of the frontiers of Virginia, North

Carolina, Kentucky, Tennessee, and, later, the Missouri

Ozarks, they honed their love of independence and their

ties to the wooded hills on which they depended. (Stevens

1991).

Geographically and culturally isolated, Ozarkers depended

on their ability to extract a living from the natural world,

roaming the woods in search of game, fruits, nuts, berries,

and herbs to supplement their small farms. They used the

forest as a commons where livestock roamed free and firewood and timber belonged to whoever cut or collected it.

They burned the forest each spring to improve forage for

their livestock and reduce ticks and snakes. The issue of

woodsburning would be at the center of conflicts between

Ozarkers and outsiders from the 1880s to the 1940s and

beyond.

THE TIMBER BOOM

The Missouri Ozarks experienced a timber boom from

approximately 1880 to the 1910s, as railroads penetrated

the region. During these years large firms such as the

Missouri Lumber and Mining Company, the Ozark Land and

Lumber Company, and the Cordz-Fisher Lumber Company

bought land and built mills throughout the region. They

sought mostly the shortleaf pine on some 6.6 million acres

of the eastern Ozarks but also tapped the white and red

oak with which it was mixed.

The control of resources emerged as a primary issue as the

timber industry began to dominate the region. The Missouri

Lumber and Mining Company (MLM) obtained 30,000 acres

of pineland in Carter County years before it moved a single

employee or piece of machinery there. As timber companies

bought and cut land throughout the Ozarks, traditional

residents of the region lost some of their access to the

resources they had depended on for survival.

The firms sought not only to prevent trespass but to establish

a productive, and dependable, labor force. The MLM met

this need by creating a company town in Carter County

named Grandin (fig. 1), after one of the firm’s initial investors;

its sawmill at its peak was reputed to be the largest in the

nation. Interactions between the MLM and the residents of

Grandin and the surrounding hills demonstrate the conflicting visions of society during the years of the timber boom in

the Missouri Ozarks. The MLM worked to control the lives

of its employees to ensure consistent production while

Ozarkers tried to maintain elements of their traditional lifestyle and relationship with the woods. Tensions developed

over schedules of work, religion, education, and leisure

activities.

The MLM attempted to get as much work out of its

employees as possible despite workers’ desire to set their

own schedules. Ozarkers resisted the MLM’s inclusion of

HISTORY OF MISSOURI FORESTS IN THE ERA OF

EXPLOITATION AND CONSERVATION

David Benac and Susan Flader1

1 Visiting Assistant Professor, Southeastern Louisiana University, Department of History and Political Science, Hammond, LA 70402; and

Professor of History, Department of History, University of Missouri, Columbia, MO 65211, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—The era of timber exploitation and early conservation in the Missouri Ozarks occurred roughly from 1880 to

1950, beginning when large timber companies moved into the region to harvest the pine and oak of the valleys and

ridgelines. Pine was largely depleted by 1910, but oak harvest continued. Resident Ozarkers, who came largely from a

tradition of subsistence hunting, gathering, and basic farming, frequently resisted the efforts of both timber companies,

such as the Missouri Lumber and Mining Company, and governmental agencies to bring modernization and industrial

productivity to the region. As a result, governmental conservation developed later in Missouri than in neighboring states.

The federal government created its first national forests in Missouri in 1933, and the state did not establish a permanent

agency devoted to forestry until 1937. The struggle to control access to the region’s forest resources and culture remained

a prominent issue throughout the era. The legacy remains today in forests with an abnormally high percentage of cull and

continued resistance of Ozarkers to governmental regulation.
37

Sunday in the regular workweek as it expanded its operations beyond Carter County. When the firm faced local

opposition over Sunday work as it began logging in

Reynolds County in 1905, it offered the county’s prosecuting

attorney $300 per year if he would discourage people from

using legal means to resist. But when MLM expanded into

Shannon County in 1907, the prosecuting attorney there

sided with the locals. MLM’s Ozark manager C.C. Sheppard

reported to company president J.B. White that “there is

nothing we can do at present, except discontinue this

[Sunday] work.” [On Reynolds County see J.B. White to

W.B. Pettibone (Jan. 12, 1906), folder 57. On Shannon

County see C.C. Sheppard to J.B. White (Feb. 12, 1907),

folder 364. All letters are in the Missouri Lumber and Mining

Papers (hereafter cited MLM Papers) at Western Historical

Manuscripts Collection, Ellis Library, Columbia, MO (hereafter cited WHMC)]. Ozarkers and the MLM had different

ideas about work. Ozarkers entered the timber boom from a

subsistence lifestyle grounded in the cycle of the seasons,

while MLM attempted to institute an industrial view of labor

based on production quotas and a time clock. Conflicts over

this basic element of society reflected the larger tensions of

the era.

One of the most effective methods of social control throughout history has been religion. The MLM made every effort to

serve as the patron of Grandin’s religious institutions throughout the company’s tenure in the town. The MLM claimed to

remain open to all doctrines and there is no evidence that

the company attempted to influence the sermons of its

preachers. While in Grandin the MLM paid the salaries of

the preachers at no fewer than three churches—Methodist,

Baptist, and Congregationalist. The Congregational Church

established a particularly close relationship with the MLM.

C.E. Slagle, who ran the company store, occasionally

served as a deacon, and the church created an association,

the Knights of King Arthur, devoted to teaching young men

vocational skills useful in a timber economy as well as the

dangers of alcohol and tobacco, which gained the Congregationalists an extra stipend from the MLM. Ozarkers,

however, favored the Baptist church, derisively described

by White as having “tobacco stained floors and walls” [J.B.

White to G. Andrews (Feb. 26, 1906), folder 111; W. Bosard

to J.B. White (Feb. 11, 1907), folder 362; J.B. White to C.C.

Sheppard (Aug. 1, 1907), folder 530; J.B. White to E.B.

Grandin (Sept. 6, 1907), folder 584; all in MLM Papers].

Ozarkers demonstrated their rejection of the urban and

industrial values of the MLM by patronizing the church they

felt most comfortable in.

Although the MLM never explicitly stated a desire to shape

the minds of children in the region, its combination of

programs such as the Knights of King Arthur and the

maintenance of company schools served to draw the youth

of the Ozarks into the control of the company. The MLM

built Grandin’s school, paid the teachers, and provided

Figure 1—Carter County and surrounding area.
38

each graduate with a gift. There is some evidence that

these practices paid off. When Leonard Hawn’s father left

the MLM’s employ in 1907, Leonard, a graduate of the

Grandin school, chose to seek his future with the MLM

rather than with his family [C.C. Sheppard to J.B. White

(May 30, 1907), folder 438, MLM Papers].

Leisure activities, especially the use of alcohol, represented

yet another arena of tension. Ozarkers drank on the job,

bootlegged, and opened illicit drinking establishments,

while the MLM consistently fired employees drunk at work

whether they were laborers, foremen or doctors. One of the

best examples of this is the case of Dr. Rhea, a resident of

nearby Oregon County, who was employed to assist while

the regular MLM physicians took their vacations. After Rhea

spent two weeks at a logging camp, the company discovered

he had spent a large portion of the time drinking with the

locals and fired him immediately [C.C. Sheppard to J.B.

White (June 19, 1906), folder 189, MLM Papers]. Ozarkers,

regardless of their position in society, returned to their

tradition of relaxing in one another’s company with their

whiskey when they had the opportunity. As a proponent of

modernization and efficiency the MLM could not tolerate

drunkenness among its employees.

The timber boom came to a close in the Missouri Ozarks

around 1910 (fig. 2), when it was beginning to peak in

Arkansas, Louisiana and other states in the South and

taking off in the Pacific Northwest. By then Missouri’s pine

was virtually gone, and it has never recovered; even today it

amounts to only about 600,000 acres, less than one-tenth

its former acreage. The MLM and other large companies

moved their operations to other regions with uncut forests,

selling off their cutover land to unsuspecting buyers or

simply stopping payment of taxes.

The MLM understood the psyche of its workers. When the

company decided to close its operations in Grandin, several

Ozarkers confronted J.B. White at the company store with

concerns about their future. White pacified the locals when

he told them he “considered it much better for them to have

a small farm and a garden even if they lived in small log

houses and raised their living and have their hogs fattening

on the mast, that they would be better off than working

around a saw mill and paying rent” [J.B. White to A. Johnston

(Feb. 5, 1910), folder 755, MLM Papers]. Whether or not

the exchange happened exactly the way White claimed,

many locals did turn to farming after the big mills left the

Ozarks.

Figure 2—Missouri sawlog production (in million board feet) in selected years, 1860-2000.

Figures from 1869 to 1946 are from U.S. Census of Manufactures categories “sawed timber”

or “lumber sawed,” as reported in Steer (1948). For certain years Steer also includes

“estimates” that are somewhat higher, i.e., 1929—260 and 1939—296. Sawlog figures from

1958 to 1997 are from USDA resource bulletins.
39

THE TRANSITIONAL ERA

The years from about 1910 to the mid-30s were a transitional era in the Missouri Ozarks. While Ozarkers attempted

to return to a life of subsistence agriculture, the timber

interests still in the area sought to extend the life of the

remaining oak and other hardwoods by initiating an industrial style of conservation. Neither group truly succeeded.

With the departure of much of the timber industry, locals

tried to meet their needs with family farms. Between 1900

and 1920 the number of farms increased in both Carter and

Shannon counties. Despite this growth, both counties stayed

near the bottom of the state in terms of percentage of land

in farms, meaning that most farms were small (Stevens

1991). Locals purchased what land they could and tried to

cultivate the rugged terrain, supplementing their meager

produce by hacking oak ties and cutting wood from highgraded stands for stave bolts, charcoal, and firewood. Much

of this cutting was from land they did not own but claimed

permission to cut, a practice described as “grandmawing.”

As Ozarkers tried to regain their traditional self-sufficiency

they also sought to assert their independence from outside

forces. They did this in part through opposition to government

agencies, which found the Ozarks a less than welcoming

region. Although the federal government was active in

states bordering Missouri, including Arkansas where the

Arkansas (later, Ouachita) and Ozark National Forests were

established in 1907 and 1908, it was unable to establish a

forestry presence in the Missouri Ozarks during the period.

Unlike Arkansas, Missouri had no public domain remaining

at the time; but even after passage of the Weeks Act in 1911,

which authorized purchase of land for national forests in the

eastern states, the Missouri General Assembly, disproportionately representative of rural areas, failed to pass

enabling legislation for two forests proposed in 1914.

Nor was the rural-dominated Missouri legislature willing to

approve a state forestry agency advocated by several governors, even though more than half the states established such

an agency during the Progressive Era. The state passed a

game and fish law, including a license and warden system,

in 1905, but the Game and Fish Department struggled to

establish a presence in the Ozarks, where locals made

sport of dodging the regulations and the wardens. In 1917

the legislature authorized five percent of all game and fish

license fees to be set aside in a state park fund, a measure

in considerable disfavor among both urban sportsmen and

Ozarkers, especially after the diversion was increased to 25

percent in 1923 and the state began buying parklands in

the Ozarks. The parks would be off limits to hunting, timbering, and livestock.

The state’s efforts in forest conservation during the transitional period devolved to the hands of a group of influential

timbermen who continued to tie their fortunes to Missouri,

where St. Louis was the main crosstie market in the nation

and Kansas City still a major distribution point for southern

lumber. At a dinner in 1921 sponsored by the Lumbermen’s

Exchange of St. Louis and the Tie and Timber Division of

the St. Louis Chamber of Commerce, they organized a

Missouri Forestry Association (MFA) in order to “advance

the public understanding of the importance of timber crops”

and insure “a proper area of forests so maintained and cared

for as to furnish a supply of timber for future needs” [The

organization meeting of the Missouri Forestry Association

(Dec. 21, 1921-Jan. 22, 1922), and Missouri Forestry

Association: Constitution (Dec. 7, 1921), both in folder 275,

Frederick Dunlap Papers, 1891-1937, WHMC.]

The MFA dominated Missouri’s efforts to establish control

over its forests during the 1920s, advocating fire prevention, tax reform, and reforestation and opposing national

forests or regulation at any level, federal or state. Though

some urban conservation and recreational interests

promoted national forests and other public land at the time,

the MFA sought to prevent the U.S. Forest Service from

entering the state. They did not favor state forests either,

except perhaps as small demonstration areas, though they

advocated a state forestry program that could encourage

protection of private forests. Missouri was one of only a

handful of forested states with no forestry legislation or

administration whatever by the 1920s. When the ClarkeMcNary Act of 1924 made federal matching funds available

to qualified state forestry agencies for fire protection and

reforestation, the MFA lobbied for the best they could get in

1925 from a legislature ever attentive to rural voices, a

small forestry program under the State Board of Agriculture,

provided that they—the timber industrialists in MFA—would

pay the salary of the state forester and related expenses

[for one demonstration of the MFA’s relationship with the

Clarke-McNary Act see Minutes of council meeting (Aug. 4,

1925), folder 276, Dunlap Papers].

Despite having achieved some success, the MFA could not

change the attitudes of most Ozarkers towards forestry. Both

MFA and the new state forester devoted their greatest efforts

to the fire problem, but Ozarkers refused to give up the practice of woodsburning, an important part of their traditional

culture. The new state forester, Frederick Dunlap, and his

only assistant, Paul Dunn, who was stationed in the Ozarks

to organize local communities to control their own fire, tried

valiantly to make inroads. But when funding for their small

program dried up entirely in 1931, they gave up in despair

and left the state; Dunlap filed a final report concluding that

fire control was “impossible” in the Ozarks (Callison 1953, 96)

(we have been unable to find the report). The MFA also may

have given up on its attempts to control the state’s forests

by this time, as it seems to have essentially disappeared.

ERA OF GOVERNMENTAL INVOLVEMENT

As the great depression, which had already begun in the

Ozarks in the 1920s in the aftermath of the timber boom,

deepened over the entire nation during the 1930s, economic,

social, and environmental conditions combined to facilitate

the entrance of government into the Missouri Ozarks.

At the urging of the governor, the state legislature in 1929

finally passed an act authorizing national forests in

Missouri, but an amendment rendered it moot by limiting

acquisition to 2000 acres per county. Then a new National

Forest Reserve Association, formed by local businessmen

and public officials in the eastern Ozarks, won authorization

in 1933 for up to 25,000 acres per county—a limitation

subsequently removed—and the U.S. Forest Service

quickly established eight purchase units in the Ozarks and
40

began land acquisition. The National Plan for American

Forestry, issued in 1933, concluded that private owners

were responsible for “practically all the major forest

problems” and recommended public ownership of half the

nation’s forest land; state planners in turn recommended

that 8 million acres in Missouri be in public ownership and

devoted to intensive forestry (Missouri land use problems

and policy. Transmitted to National Resources Board May

18, 1935 by E.A. Mayes, research assistant, 141p. tps., in

Missouri State Planning Board, 1933-1943, Missouri State

Archives, Jefferson City, MO). In fact only about 1.3 million

acres would be purchased in Missouri during President

Roosevelt’s New Deal.

Even before the acquisition of substantial national forest

lands, however, Missouri took advantage of the New Deal’s

Civilian Conservation Corps and other work relief programs

to develop its state parks, by 1933 totaling more than

40,000 acres. The state’s emphasis on park development,

funded in part by diversions from fishing and hunting

license fees, coupled with decimated wildlife populations

and the ever-political nature of the game and fish warden

system, led Missouri sportsmen to launch an initiative petition campaign in 1935 for a constitutional amendment to

create a bipartisan conservation commission with full

authority for fish, wildlife, and forestry, but not parks (Flader,

in press). Though the measure passed overwhelmingly in

1936, most of the 29 counties in which it failed were

forested counties in the Ozarks, where residents were still

deeply resistant to outside interference (Callison 1953).

With parks now relegated to a separate agency, the new

commission in 1938 hired George White from the U.S.

Forest Service to develop a state forestry program. White

hired five more professionally trained foresters and assigned

them to protection districts in the Ozarks. With lookout

towermen and high school boys hired locally to help spot

and fight fires and with a mobile motion picture unit, they

began the long, slow process of educating Ozarkers about

the perils of woodsburning. Until they could control fire,

reforestation and forest management would hardly pay—

though, White believed, if landowners could be induced to

plant trees, they would become advocates for fire control

(Keefe 1987). By late 1938 White had cooperative firefighting agreements with 144 private landowners—likely

corporations, as they owned between 500 and 37,000 acres

apiece. The size of the holdings suggests that, while the

forestry program may have had support, it was not from the

common Ozarker. As late as 1946, the forestry division

admitted that fire protection remained its primary focus

[Missouri Conservation Commission, Press Releases,

1937-1939 and 1946-1947 (bound and held by the State

Historical Society of Missouri, Columbia), 1-2].

The Missouri General Assembly in 1946 finally passed its

first significant forestry legislation, the State Forestry Act,

which established a “forest cropland” program and provided

penalties for woods arson; and it finally began appropriating

funds ($150,000) from general revenue for forestry purposes,

mostly fire control, which enabled the state to receive more

matching funds from the federal government. By 1950

Missouri’s 15.5 million acres of forest included 150,000 acres

of state forests and 1.3 million acres of national forests, Figure 3—Missouri timber ownership by class.

although the land had only about one-fifth the stocking of

sawtimber that could be expected under good management

and open range for livestock still prevailed in much of the

Ozarks. About 6 million acres, public and private, were

organized in forest protection districts, only about two percent of which burned annually, compared with an estimated

one in three acres before fire control (OM 1951-52: 341-43).

The state was on its way to a more effective forestry program.

CONCLUSION—THE LEGACY

The growing success of the U.S. Forest Service and the

Forestry Division of the Missouri Conservation Commission

marked the beginning of permanent governmental involvement in the Ozarks. Later generations would establish the

Ozark National Scenic Riverways (1964), end the practice

of open range grazing (1967), begin to recognize the

region’s ecological significance, and even appreciate and

begin to mimic the ecological role of natural fire.

By the close of the 20th century, Missouri’s 14 million acres

of forest land, four-fifths of which is in the Ozarks, would

remain overwhelmingly (83 percent) in private hands (fig. 3),

controlled by more than 300,000 landowners, the vast

majority of whom owned fewer than 50 acres. Forest industries would own less than 2 percent (compared with 25 percent in Arkansas and 14 percent in the country as a whole)

and public agencies 15 percent, including 1.5 million acres

in the Mark Twain National Forest, some 444,000 acres of

state forests, and 138,000 acres of state parks. The incidence

of wildfire—as opposed to prescribed fire—is down to about

1/10 of 1 percent of Missouri’s forests burned annually, but

almost all the fires are human caused, the majority of them

still classified as arson—a lingering remnant of the Ozark

tradition of woodsburning and resistance to outside authority.

More than a century of land abuse by industry and Ozarkers

alike, coupled with continued poverty, rugged individualism,

and distrust of governmental authority, has left Missouri

forests with the highest percentage of cull material (tables 1

and 2)—trees unusable for industrial wood products because

of rot, dead material, form, or other defect—of any state in

the nation (Shifley 1999). Virtually all of this cull is in hardwoods, much of it in the red oak group that came to dominate the more than 6.6 million acres formerly in shortleaf

pine in the wake of heavy exploitation and continued burning,

grazing and erosion. This legacy of mistreatment, coupled

Private farmer

37%

Private corporation

7%

National forest

10%

Other public

5%

Private forest industry 2%

Private individual 39%
41

with drought and the advancing age of many trees, has left

the state’s forests especially vulnerable to wood-boring

insects, fungi, and other manifestations of oak decline.

Yet Missouri still has no forest practices act to guide the

treatment of private lands. A broadly representative

Table 1—Total cull material

Growing Cull

Rank State Cull stock of total

 billion cubic feet percent

1 Missouri 4.8 9 35

2 Mississippi 2.9 19.8 13

3 Maine 2.8 24.3 10

4 Virginia 2.4 25.9 8

5 Wisconsin 2.2 16.6 12

6 Texas 1.9 12.9 13

7 N. Carolina 1.9 32.7 5

8 Minnesota 1.9 15.1 11

9 Louisiana 1.9 18.9 9

10 Georgia 1.9 30.7 6

Source: Shifley (1999).

Table 2—Percentage of hardwood cull material

Hardwood

Hardwod growing Cull of

Rank State cull stock total

- - - billion cubic feet - - - percent

1 Missouri 4.8 8.1 37

2 Kansas 0.7 1.2 36

3 Oklahoma 0.9 1.6 35

4 Iowa 0.9 1.7 34

5 Nebraska 0.1 0.3 22

6 Arkansas 1.9 12.3 13

7 Tennessee 1.5 13.8 10

8 Illinois 0.5 4.7 10

9 Kentucky 0.6 14.8 4

Source: Shifley (1999).

Governor’s Advisory Committee on Chip Mills that heard

testimony for more than a year on the sorry state of

Missouri’s forests proved unwilling to embrace any sort of

regulatory mechanisms for better forest management,

largely out of respect for—or fear of—Ozarkers’ insistence

on private property rights and their resistance to governmental regulation, and the state legislature failed to enact

any of the committee’s recommended economic incentives

(Lewis, in press). The challenge for Missourians to secure

better management of their forests remains immense.

LITERATURE CITED

Callison, C.H. 1953. Man and wildlife in Missouri: the history of

one state’s treatment of its natural resources. Harrisburg, PA:

Stackpole, 1953), 134 p.

Flader, S.L. [In press]. History of Missouri forests and forest

conservation. In: Flader, S.L., ed. Toward Sustainability for

Missouri Forests. Proceedings of a conference held in

Columbia, MO, March 4-5, 1999. St. Paul: USDA Forest

Service, North Central Research Station.

Keefe, J.F. 1987. The first 50 years. Jefferson City, MO: Missouri

Department of Conservation. 446 p.

Lewis, B.J. [In press]. Chip mills and Missouri forests: a case study

in policy development. In: Flader, S.L., ed. Toward Sustainability

for Missouri Forests. Proceedings of a conference held in

Columbia, MO, March 4-5, 1999. St. Paul: USDA Forest

Service, North Central Research Station.

[OM]. 1951-52. Official manual, State of Missouri. Jefferson City,

MO: Secretary of State.

Shifley, S.R. 1999. Forest inventory, growth, and removals in

Missouri. Report to the Governor’s Advisory Committee on Chip

Mills. Columbia, MO: USDA Forest Service, North Central

Research Station. 48 p.

Steer, H.B. 1948. Lumber production in the United States 1799-

1946. USDA Misc. Pub. No. 669.

Stevens, Donald L., Jr. 1991. A homeland and a hinterland: the

Current and Jacks Fork riverways. Historic resource study,

Ozark National Scenic Riverways. Omaha, NE: USDI National

Park Service, Midwest Region. 248 p.

U.S. Congress, Senate. 1933. A national plan for American forestry.

Report of the Forest Service of the Agricultural Department on

the forest problem of the United States, in response to S. Res.

175. 2 vols. 73rd Cong., 1st sess., S. Doc. 12. Washington, DC:

GPO. 1,653 p.
42

INTRODUCTION

Landscapes and vegetation communities are in constant

change. The disciplines of geography and archeology, which

deal with human-land relationships, can provide us with

ecological models of plant change related to human use of

the available natural resources. This paper identifies archeological and historical data that can be used to confirm or

disprove changes in ecosystem models of the Arkansas

Ozarks. Such changes are relevant to our understanding of

the cycling of species with different life spans in response

to climatic drought episodes, insect infestations, and fire

regimes. A case study is provided on the Wedington Unit,

Boston Mountain Ranger District, Ozark-St. Francis

National Forests.

STUDY AREA

The Wedington Unit (fig. 1) lies west of Fayetteville in the

extreme northwestern corner of Arkansas, where Ozark

Plateau remnants of the Boston Mountains form outlying

ridges over the Springfield Plateau. The Unit falls on the

divide between Benton and Washington Counties, and is

bounded on the north and east by the Illinois River.

Wedington Mountain, an erosional remnant of the Ozark

Plateau, runs generally north-south through the study area.

GEOLOGY AND SOILS

The rocks of the Ozarks are primarily sedimentary in origin,

formed by deep sea and near-shore sediments laid down

during the Paleozoic era (Sabo and others 1982). The

Wedington Unit consists of the northward extension of the

sandstone formations of the Boston Mountains onto the

limestone-dominated Springfield Plateau. The Boston

Mountains are capped by the Mississippian era Wedington

sandstone unit of the Fayetteville shale formation (Haley

1976). These generally level-bedded strata are warped by

domal uplift and deeply incised by streams, giving the

region a mountainous relief.

The Springfield Plateau consists of gently sloping Mississippian limestones and contains the Boone limestone/chert

formation. This formation is important for the readily available chert that was heavily exploited by Native Americans

for the manufacture of stone tools. Dickson (1991) divides

chert from the Boone formation into St. Joe, Reeds Spring,

Keokuk, and Moorehead varieties.

The dominant soils of the Wedington study area were

developed under hardwood vegetation (Harper and others

1969, Phillips and Harper 1977). In the uplands, the soils

are Allegheny, Apison, Enders, Hector, Mountainburg,

Steprock, and Nella—all primarily stony and gravelly sandy

loams. Soils on the mountaintops are generally < 3 feet

deep, while soils on slopes and benches may range to 7

feet deep. Soils on the lower uplands of the Springfield

Plateau in the study area are primarily Captina, Nixa,

Pickwick, and Tonti. These are silt loams and cherty silt

loams that range from 3.5 to 5.5 feet deep. Soils in the

flood plains of the study area include Britwater, Captina,

Razort, and Secesh. These are silt loams and gravelly silt

loams that range from 4 to > 7 feet deep.

No typical mollic (black surface horizon, thickened) prairie

soils (Carytown, Jay, Mayes, Newtonia, Sogn, Taloka) have

been mapped within the Wedington study area (Phillips and

Harper 1977). In fact, the nearest known soils in Benton

County that developed under prairie vegetation (Jay) are at

least 2 to 3 miles north of the area. In Washington County,

Taloka soils have thickened surface epipedons typical of

prairie soils and are found south of the study area (Harper

and others 1969). These soils are frequently found in

association with the Captina soils that do surround the

Wedington study area; however, Captina soils have shallower surface horizons and are thought to have developed

under hardwoods (Phillips and Harper 1977).

GENERAL LAND OFFICE RECORDS

Today, there are only a few areas of the Ozarks that still

contain the full range and proportion of plant and animal

species that flourished prior to European settlement. Land

managers need statistically sound models of presettlement

plant distributions over entire landscapes to understand

vegetation potential and historical changes in vegetation

(Foti and Glenn 1991, Warren 1984, Warren and O’Brien

1984). The original land surveys made when the public

OLD-GROWTH WOODED PASTURE IN THE OZARKS

David H. Jurney and David W. Stahle1

1 Heritage Program Manager, Ozark-St. Francis National Forests, Russellville, AR 72801; and Professor, Department of Geosciences,

University of Arkansas, Fayetteville, AR 72701, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Forests in the Ozarks are ancient: the dominance and density of their various arboreal and herbaceous

species have fluctuated over time in relation to climatic change and cultural influences. This study examines the nature of

the pre-European forest composition in the Ozarks through studies of geology and soils, General Land Office surveys,

archeology, and dendrochronology. Examples and a case study on the Wedington Unit are drawn from the Ozark-St.

Francis National Forest, where, in some areas, old-growth oak forests remain adjacent to former agricultural fields that

are regenerating naturally. This paper also identifies forest management practices that aid in the maintenance of diverse

old-growth ecosystems.
43

domain was sold or given to private individuals or entities

are excellent sources of these data. In these surveys, the

observations of prairie-forest boundaries and witness trees

recorded at each land tract corner provide quantitative

information that can be used to reconstruct arboreal

communities and their interfaces with prairies (Bourdo

1956; Curtis 1959; Delcourt 1976; Delcourt and Delcourt

1974, 1977; Jurney 1982, 1987; Sears 1925).

Surveyor bias has been analyzed by several researchers

(Bourdo 1956; King 1978, 1984; Sears 1925; Warren 1984)

and appropriate methods developed to address these biases

(Jurney 1982, 1987; Siccama 1971). Since land surveys

are legal documents, General Land Office (GLO) surveyors

were instructed to record the nearest tree to each corner of

a tract as a witness tree, so that the corner itself could be

relocated over time (Dodds and others 1943, McKitrick

1918, McMahon 1941, Shine 1969). As early as 1806, witness trees were required to be as close as possible to the

land tract corner (White 1982), and in 1831 this was specifically mandated in Tiffin’s instructions to all Federal land

surveyors (Dodds and others 1943). In the 20th century, this

stipulation was changed toward selection of more permanent corners (Bragg 2002, Stewart 1935). Tharp (1941,

1948) presents discussions on the tree-ring dating of witness trees in order to provide legal witness for land tract

corners and “follow the footsteps of the surveyor.” Generally

speaking, the closer the tree to the corner, the easier it is to

locate again by subsequent surveyors laying out land grants

from the public domain. It was also easier and more cost

effective for the field crews of the original surveyor to mark

nearby trees rather than selecting certain species at greater

distances.

Figure 1—Wedington Unit prairie and forest reconstructed from Government Land Office surveys,

1832 to 1833.

32W 31W

17N

16N

Boston Mtns

Project

Area

BE705

BE703

BE704

WA252

1 mi

1 km

Mountains

Prairie

River/lake

Federal bdy

County line

Floodplain

Barrens

Benton

County

Washington

County
44

GLO surveyors noted and marked from one to four trees at

each corner of a tract, describing each tree, its diameter,

and the direction and distance to it from the corner. When

land lines were being run, trees falling on a line were also

noted and marked, and the boundaries between forest and

prairie recorded; all of which provide evidence for the extent

of fire-dependent ecosystems. Occasionally, observations

such as “burned over,” “barrens,” or “burned tree” provide

direct evidence of fire in the forests (Weniger 1984, 1996).

In Texas, these direct observations were recorded in Hill

and Falls Counties (Weniger 1984), and tree sizes and

densities have been used to determine fire return effects on

community development along the interface of Blackland

Prairies and the Post Oak Savannah (Jurney 1987, 1988a,

1988b, 1988c). In Arkansas, the term “barrens” appears to

reflect a fire-dependent ecosystem; the term has also been

found in notes from Johnson, Benton, and Washington

Counties (Lockhart and others 1995, Miller 1972, Sabo and

others 1982). This term is definitely correlated with “burned

over” areas in Jackson County, MO, where prairie fires had

burned into forested areas and killed former witness trees

(Jurney 1982).

The usefulness of correlating GLO witness tree distributions

to soil and topographic settings is demonstrated by two

studies in the Ozarks: Chaney (1990) on the Middle Fork of

the White River in Washington County, and the Arkansas

Archeological Survey on the Lee Creek Unit of the Boston

Mountain Ranger District in Crawford County (Lockhart and

others 1995). Both studies observed that although post

oaks (Quercus stellata) favored moderately to well-drained

soil, they were absent from poorly drained soils. White oaks

(Q. alba) were distributed across the foothills and upper

slopes and nearly absent from the flood plains of the interior

Ozarks. Red oaks (Q. falcata, Q. pagoda) were more frequent

on well-drained slope soils and the flood plains. Black oaks

(Q. velutina, Q. schumardii) and hickories (Carya spp.) were

evenly distributed across all soils. Historic settlement has

disrupted the vegetation patterns, introducing red cedars

(Juniperus virginiana) and pines (Pinus spp.) into many

areas and allowing the spread of other species such as

maple (Acer spp.), sycamore (Plantanus occidentalis),

walnut (Juglans nigra), cottonwood (Populus deltoides),

and hackberry (Celtis laevigata) in all areas.

The GLO studies have direct relevance to historic vegetation regimes, and the U.S. Department of Agriculture (USDA)

Forest Service is currently developing a witness tree geographic information system (GIS) layer for all the Ozark-St.

Francis National Forests. Until this is completed, individual

study areas have been selected to demonstrate the potential for land management. One of these is the Wedington

Unit.

We reconstructed the presettlement vegetation for the entire

Wedington Unit of the Ozark-St. Francis National Forest

and peripheral areas surrounding the unit, comprising

24,320 acres (9 846.2 ha). Figure 1 illustrates the interface

of prairies and forests in the Wedington study area. Some

areas, such as barrens, identify fire-prone areas, in addition

to the prairie areas. Since many of the areas shown as prairies are located on soil types developed under forests, it is

assumed that most of these prairies were produced by wildfires. A long linear prairie is located along the road from

Fayetteville to Rogers, while others appear to be associated with agricultural fields. Prairies are found in upland,

slope, and flood plain settings.

Table 1 lists 25 canopy species and 5 understory species

observed by 3 individual surveyors in the Wedington Unit

and adjacent forests and prairies during 1833 and 1834.

The witness tree matrix consists of 334 trees (table 1). The

original surveys were plotted on U.S. Geological Survey

7.5-minute quadrangles and were sorted according to six

physiographic/topographic zones (flood plain, flood plain

prairie, slope, slope barrens, upland, upland brushy prairie).

Common names for trees were used by the land surveyors.

Exact scientific nomenclature cannot be determined with

confidence for all species, but the best-guess scientific

names are presented in table 1.

The flood plain contained 52 witness trees. The dominant

species included post oak (15.4 percent), black walnut

(13.5 percent), hickory and sycamore (9.6 percent each),

and white oak and blackjack oak (Q. marilandica) (5.8 percent each). The next most common species were black oak,

elm (Ulmus spp.), hazel (Corylus americana or Hamamelis

virginiana), sumac (Rhus spp.), and locust (Gleditsia spp.

or Robinia pseudoacacia) with 3.8 percent each. Incidental

species (1.9 percent each) included overcup oak (Q. lyrata),

black gum (Nyssa sylvatica), cherry (Prunus serotina),

hackberry, honey locust (Gleditsa spp.), box elder (Acer

negundo), ash (Fraxinus spp.), red bud (Cercis Canadensis),

and spicewood (Lindera benzoin).

The flood plain prairie contained nine trees, dominated by

hickory (44.4 percent) and blackjack oak (22.2 percent).

Incidental species included plum (Prunus spp.) and cane

(Arundinaria gigantea).

The slope contained 122 trees, dominated by black oak

(31.9 percent), blackjack oak (27 percent), post oak (23.7

percent), and white oak (7.3 percent). Incidental species

included hickory, black gum, cherry, hazel, sumac, vines,

and briers. The only red oak tree in the Wedington Unit was

recorded in the slope zone. The slope barrens contained

single observations of white oak, black oak, blackjack oak,

chinquapin (Castanea pumilia), and hazel.

The upland contained 144 trees, dominated by black oak

(33.3 percent), post oak (27.7 percent), blackjack oak (25

percent), and white oak (5.5 percent). Incidental species

included hickory, elm, maple, hazel, sumac, whortleberry

(Vaccinium spp.), huckleberry, vines, and briers. The brushy

upland prairies included single observations of elm and

plum.

No pines or cedars were recorded in the original notes.

Both species have regenerated naturally in an early 20th

century field on the top of Wedington Mountain. The cedars

were introduced by settlement, the pines by the USDA

Forest Service.

The distance from the land tract corner to the witness tree

provides a point-specific distance index that is highly variable. We used these data to calculate an average density
45

index in each physiographic/topographic zone. The densest

area is the flood plain (17.7 feet), followed by the slope and

upland (25.3 feet each). The brushy upland prairies yielded

a point density index of 104 feet, followed by the flood plain

prairie (105.6 feet) and the slope barrens (119.1 feet). The

slope barrens correspond to the old-growth post oak stands

along the benches and intact uplands of Wedington Mountain. This yields an estimate of 72 trees per acre during the

1832–33 period. Due to fire suppression, the stands are

denser today, averaging up to 148 trees per acre (see Tom

Foti, in press).

PREHISTORIC ARCHEOLOGY

Archeological surveys of approximately 25 percent of the

Ozark-St. Francis National Forests have yielded the 1,472

prehistoric sites shown in table 2 (Jurney 2001). The largest

single category is undifferentiated prehistoric lithic scatters

(73.6 percent), followed by undifferentiated Archaic (9 percent), Woodland (4.8 percent), Mississippian (3.7 percent),

and Late Archaic (3.5 percent). All other categories are

represented by few sites.

The majority (14.5 percent) of the identified cultural components date to the Archaic (1,500+ YBP). This indicates a

relatively low intensity of human occupation and use of the

Ozarks throughout most of prehistory. Sedentary populations are represented by the Mississippian, Woodland, and

phase categories (11.1 percent). Sedentary groups are

marked by semipermanent villages, mound building, and

incipient agricultural practices (Davis and Limp 1994).

Native Americans lived light-on-the-land in the Ozarks for

nearly 9,000 years. During this time, the primary hunting

strategy was the group surround; fire may have been used

to drive game or alter local habitats. Some wild plants were

domesticated near the end of this era, probably due to

Table 1—Listing of General Land Office witness treesa from the Wedington Unit, Boston Mountain Ranger District,

Ozark-St. Francis National Forest (T16-17 N, R 31-33 W), surveyed in 1832-1833

Zone

Species Flood Floodplain Slope Brushy

common name Scientific name plain prairie Slope barrens Upland prairie Total

Ash Fraxinus 1 0 00 00 1

Black gum Nyssa 1 0 10 00 2

Black oak Quercus veluntina 2 0 39 1 48 0 90

Black walnut Juglans nigra 7 1 00 00 8

Blackjack oak Q. marilandica 3 2 33 1 36 0 75

Box elder Acer 1 0 00 00 1

Cherry Prunus 1 0 00 00 1

Chinquapin Castanea 0 0 01 11 3

Elm Ulmus 2 0 00 10 3

Hackberry Celtis 1 0 00 00 1

Hazel Corlyus 2 0 11 11 6

Hickory Carya 5 4 3 0 4 0 16

Honey locust Gleditsia 1 0 00 00 1

Locust Robinia 2 0 10 00 3

Maple Acer 0 0 10 00 1

Overcup oak Q. macrocarpa 1 0 00 00 1

Pawpaw Asiminia 1 0 00 00 1

Plum Prunus 0 1 00 00 1

Post oak Q. stellata 8 0 29 0 40 0 77

Red bud Cercis 1 0 00 00 1

Red oak Quercus spp. 0 0 1 0 0 0 1

Spicewood Linderia 1 0 00 00 1

Sumac Aralia 2 0 10 10 4

Sycamore Plantanus 5 0 00 00 5

White oak Q. alba 3 0 9 1 8 0 21

Understory

Briers 0 0 1 0 1 0 2

Cane Arundinaria 1 1 00 00 2

Huckleberry Vaccinium spp. 0 0 0 0 1 0 1

Vines 0 0 1 0 1 0 2

Whortleberry Vaccinium spp. 0 0 1 0 1 0 2

Total 52 9 122 5 144 2 334

a Witness trees were noted and marked to facilitate subsequent location for dispersal of public domain, and denotes their legal status as a

court witness.
46

increasing land disturbances around bluff shelters and

riverine base camps (Fritz 1985, 1990). Around 1,500 years

ago, garden agriculture, probably using slash-and-burn

strategies, intensified the human alteration of the landscape. Many flood plain forests were also cleared for

villages, mound centers, and agricultural fields. Hunting

strategies shifted to more solitary strategies, but there

appear to have been attempts to gather food and natural

resources in the interior Ozarks and transport them to

regional population centers in the Arkansas River valley

and the lower valleys of major streams incised into the

Ozark dome (Schambach 2001).

Few major excavations and sporadic archeological surveys

have been conducted in the Wedington Mountain area

shown in figure 1. The most extensive excavations have

been conducted at the Moss Shelter (3WA252) located on

private land approximately 1 mile south of Wedington Gap

(Stahle 1986), and at the Albertson site (3BE174) located

on Spavinaw Creek approximately 15 miles north of the

project area (Dickson 1991). Moss Shelter was formed by

dissolution of shales and sandstones by water and wind

action. Albertson was formed by riverine undercutting of

limestone beds. Cultural manifestations at Moss and

Albertson range from transitional Paleo-Indian to Mississippian (ca. 10,000 to 500 years ago). The majority of the

diagnostic materials date to the Middle and Late Archaic,

ca. 8,000 to 1,500 years ago (Dickson 1991, Stahle 1986).

Moss Shelter represents the typical formation of upland

bluff shelters (fig. 2). The basic process begins with the

dissolution of the shale beds that lie under more resistant

sandstone layers. Block faulting from freeze-thaw cycles

and root penetration also contribute to the formation of

sediment traps along the benches of the mountains. Cultural deposits were recovered > 2 m deep at this site, and

similar deposits have been found along the upper benches

of Wedington Mountain. Other shelters on the northern end

of Wedington Mountain were formed by block fracturing of

the sandstone as well as water and wind action. Cultural

deposits extend along benches and down slopes from all

known rock shelters in the vicinity.

A number of archeological surveys recording prehistoric

open sites and rock shelters have been conducted in the

vicinity by USDA Forest Service archeologists. Two prehistoric lithic scatters were discovered and recorded during

our investigation of the Wedington Unit. One (3BE703) is

located on the southern point of the ridge overlooking

Wedington Gap. The site consists of several bifacial thinning flakes observed on a deflated area of the sandstone

outcrop. The area appears to have been used as a tool

refurbishing station and provided a superb vantage point

with a view to the west, southwest, and southeast on both

sides of the gap. The second prehistoric site (3BE704) is

located in the bottom of Wedington Gap. This area is marked

by erosion of the overlying sandstone to the underlying

shale; the vegetation consists of a suite of xeric plants,

including blackjack oak. The site consists of a highly disturbed scatter of Boone chert debris. Artifacts collected

included five chert cores, four large decortication flakes,

two bifacial tool fragments, and one heat-treated lamelar

flake. The site has been severely damaged by illegal offthe-road vehicle traffic.

The two prehistoric sites in the Wedington study area represent two different types of activity. One (3BE704) was a

staging area for transforming chert cores imported from the

adjacent Springfield Plateau into tools. Apparently heattreatment of these cores was practiced here. The second

site (3BE703) appears to be a hunting or territorial lookout,

based on the vantage point that provides visual coverage of

several miles. The only activity represented in the material

culture here is the resharpening of tools that were manufactured in another locality. Neither site represents a habitation locus.

Plant remains, mostly acorns, from 10 sites in the dry bluff

shelters of the Ozarks provide information on the cultural

selection of oak species (Cande 1997, Hilliard 1986). Acorns

were quantified in these studies, but carbonized hickory nut

shells and other plant remains were not quantified. Of the

10 sites listed in table 3, only 3 had more acorns from white

oaks than from red oaks. Comparing the archeological data

with the GLO data, this relative frequency of red oaks

species to white oak species (87 to 21 percent, column 3 in

table 3) is to be expected.

Table 2—Prehistoric sites on the Ozark-St. Francis

National Forest compiled from the Automated

Management of Archeological Site Data in Arkansas

(AMASDA) database kept by the Arkansas

Archeological Survey

Years ago Culture/period Count

 no. percent

12,000+ PaleoIndian 10 0.7

9,500 Dalton 6 0.4

9,499 Early Archaic 12 0.8

Middle Archaic 8 0.5

5,000 Mid-Late Archaic 1 0.1

Late Archaic 52 3.5

Undifferentiated Archaic 133 9

1,800 Early Woodland 9 0.6

Late Woodland 4 0.3

Woodland 71 5

1,100 Middle Mississippian 1 0.1

Late Mississippian 2 0.1

Mississippian 54 3.7

Kent Phase 3 0.2

Caddo I. 1 0.1

Caddo 1 0.1

Neosho 1 0.1

410 Contact 3 0.2

Contact pre-1800 1 0.1

150 Protohistoric 5 0.3

Undifferentiated 1,077 73.6

Total 1,455 100.0
47

In some of these sites, large conical pits were excavated

and filled with over a gallon of acorns, in order to parch the

contents. Parched acorns have also been found across the

Ozarks in woven bags that served to reduce insect infestation, preserve the nut meat, and make the shells more

removable (Fritz 1985, 1990, 1997). Red oaks may have

been considered a more dependable food source since

they do not germinate until spring and are less susceptible

to insects, and the acorns have a slightly higher caloric

value than white oaks (Hilliard 1986).

HISTORIC ARCHEOLOGY

Archeological surveys (Jurney 2001) of approximately 25 percent of the Ozark-St. Francis National Forest have recorded

2,535 historic sites (table 4). The largest single category is

developed settlement-rural agriculture (73.9 percent),

followed by pioneer settlement-agriculture (9.1 percent),

developed settlement (7.6 percent), developed settlementrural nonagriculture (3.5 percent), Anglo-American (1.8 perTable 3—Listing of red oak and white oak acorns from

Ozark archaeological sites in Arkansas

Red Red White White

Site oak oak oak oak Total

no. percent no. percent no.

3BE1 749 65.1 402 34.9 1,151

3WA4 173 39 266 61 439

3BE10 211 85.5 36 14.5 247

3CR8 35 21 131 79 166

3BE6 41 63 24 37 65

3BE11 22 60 15 40 37

3MA5 13 54.2 11 45.8 24

3NW624 51 66 26 34 77

3NW625 5 31 11 69 16

Total 1,300 922 2,222

BE = Benton; WA = Washington; CR = Carroll; MA = Madison; NW

= Newton.

Analyzed by Hilliard (1986) and Cande (1997).

1 2 3

4 5

Initial

human

occupation

6

7

Terminal

human

occupation

8

9

Figure 2—Schematic of Ozark bluff shelter formation processes (Cande 1997,

Laville and others 1980).
48

cent), and developed settlement-city/town (1.7 percent). All

other categories are represented by only a few sites (table 4).

The significance of these data is that the majority (89.2 percent) of the identified cultural components date to the developed settlement era of the late 19th and 20th centuries (ca.

1890 to 1940). This indicates a tremendous increase in

human impacts to the landscape that tied to population

growth and improved transportation (see Guyette and

others, in press).

The historic archeological data (Jurney 2001) provide a

minimum estimate of 9,452 farmsteads on the Ozark-St.

Francis National Forests (total area 1,158,289 acres) that

were occupied between 1890 and 1940. Using 110 acres as

a mean farm size with 43 acres under cultivation (Schalm

1973), 1,039,720 acres (89.7 percent) of the forest could

have been occupied between the late 19th and early 20th

centuries, 406,436 acres were cleared and cultivated, and

the remaining 633,284 acres were used as wooded pasture. Based on these interpolations, the unoccupied portion

of the Ozark-St. Francis National Forests (188,569 acres)

may have been used by free-range herders.

One historic site (3BE705) investigated as part of the present study consists of a 20-acre cleared field on the top of

Wedington Mountain. The access road to the field passes

through the rock escarpment in a narrow cleft. Rock fences

had been constructed in all low areas along the escarpment

to prevent free-ranging livestock from entering the field on

the top, the fence and escarpment providing an approximate 4,592-foot perimeter. The rock wall, which comprises

about 15 percent of the total perimeter, is 4 feet tall and

measures 3 feet thick in places. It is estimated that 8,265.6

cubic feet of stone (approximately 1,836.8 tons) were

removed from the field and rock outcrop to build this rock

fence, a significant investment in labor to achieve a protected cultivated area. If the escarpment wall were not in

place, the investment would have been much greater to

protect the field crops from free-ranging livestock.

Old-growth trees were removed from the cultivated field but

were left in place along the bench below the escarpment

wall, where livestock were allowed to free-range. Since it

was abandoned, the old field has been reclaimed by red

cedars, pines, and mixed hardwoods. We cored these trees

using a Swedish increment corer. The red cedars are at

least 68 years old, indicating that the field was abandoned

or converted to fallow ground around 1933. The bench and

side slopes of this area retain old-growth characteristics.

Tree-ring collections on the south end of the mountain by

Wedington Gap have yielded one of the best records of

frost rings (false spring events) in all of Arkansas and

Oklahoma (Stahle 1990).

Based on our examination of the Benton County Deed

Records in the Bentonville Courthouse and the Forest

Service tract acquisition files, the land containing the field

and old-growth wooded pasture on Wedington Mountain is

part of a homestead land grant to Harry and Lizzie Beck

dated November 3, 1899. The land falls on the dividing line

between Washington and Benton Counties. The 80-acre

parcel in Benton County was sold to Thomas Dunn in

October 1905. The land was acquired by S.C. Peacock in a

tax sale and was resold to Clarence S. and Cora Rankin

July 12, 1913. They sold the land, including the portion in

Washington County, to A.L. and Doris McCulley (134 acres

total) on October 14, 1922. Doris and her son J.H. (wife

Carrie E.) and daughter May sold the land to the U.S.

Resettlement Administration on November 13, 1938. At that

time, two dwellings, a poultry house, a barn, a well, and a

spring were located at the core of the farm. The upland

pasture was cultivated on the south end and wooded on the

north end. Based on our courthouse and tract acquisition

file research for this paper, little improvement and expansion was done to the farm from 1899 to 1907. During the

Peacock ownership in 1908, a central barn was built. The

McCulley ownership in 1922 marked the expansion of the

farm with the construction of two houses, followed by a

poultry house in 1933. The upland pasture was most likely

cleared and cultivated around 1922. At least five serial

occupations worked the land in this area. The McCulley

occupation from 1922 to 1933 was the most intense.

DENDROCHRONOLOGY

Since the late 1950s, tree-ring samples have been collected

from stands of living trees across Arkansas and adjacent

States. A series of chronologies has been developed for the

region from these collections (Stahle 1990; Stahle and

Hehr 1984; Stahle and others 1984, 1985b). The five longest Arkansas chronologies established are for baldcypress

(Taxodium distictum) and span the period 1322 to 1990.

Table 4—Listing of historic sites on the Ozark-St.

Francis National Forest compiled from the Automated

Management of Archeological Site Data in Arkansas

(AMASDA) database kept by the Arkansas

Archeological Survey

Years

ago Site category Count Percent

450 Late Holocene semisedentary 24 0.9

150 Pioneer settlement 20 0.8

Pioneer settlementagriculture 231 9.1

110 Developed settlement 193 7.6

Developed settlement-rural

agriculture 1,877 74.0

Developed settlement-ruralnonagriculture 90 3.6

Developed settlement rural

plantation 7 0.3

Developed settlement-city/

town 44 1.7

Developed settlement-rural

forager 1 0.1

Anglo-American 45 1.8

Developed settlementAfrican American 3 0.1

Total 2,535 100.0
49

The mean germination date is 1498, and the stands range

in age from 214 to 668 years. The nine second-longest

chronologies are for white oak. White oak spans the period

1598 to 1993, with a mean germination date of 1697 and

an age range of 89 to 395 years. Thirty-four post oak chronologies span the period 1626 to 1993, with a mean germination date of 1671 and an age range of 257 to 372 years.

Five shortleaf pine (Pinus echinata) chronologies span the

period 1649 to 1982, with a mean germination date of 1760

and an age range of 71 to 333 years. Two black oak chronologies span the period 1870 to 1959 and are similar to red

oak in growth patterns and ages (< 100 years longevity).

The significance of these data revolves around the maximum ages of various species. Baldcypress, the longest

lived at 650 years, is restricted to aquatic habitats of large

rivers and swamps. Several stands are present on the St.

Francis Division of the Ozark-St. Francis National Forests.

Post oak and white oak have approximately the same life

spans (350 years), while the life span of shortleaf pine is

slightly less. These three species generally reach old age

between 300 and 350 years. Black oak and red oak have

much shorter life spans, rarely reaching 100 years. Because

of this range in life spans, it is to be expected that species

dominance should vary across the landscape. It is our

opinion that the apparent decline of red oak in the area may

be a result of an overly mature species dying out, while

longer-lived species such as shortleaf pine, white oak, and

post oak remain viable.

We have collected fire-scarred trees and stumps in the southern Ozarks as part of ongoing fire and ecosystem studies

conducted by the USDA Forest Service. In the southern

Ozarks, continuous fire scar records have been compiled on

the Bayou and Pleasant Hill Ranger Districts for three time

periods: 1747 to 1764, 1804 to 1906, and 1916 to 1954.

From 1747 to 1764, the fire return interval ranged from 1 to

3 years with a mean return interval of 2.43 years. From 1804

to 1906, the fire return interval ranged from 1 to 9 years with

a mean return interval of 4.4 years. From 1916 to 1954, the

fire return interval ranged from 1 to 12 years with a mean

return interval of 5.3 years (D.H. Jurney. 2002. Historic fire

regime. 19 p. On file with: Ozark-St. Francis National Forests,

605 W. Main, Russellville, AR 72801). This suggests a

general trend toward decreasing fire returns with increasing

historical settlement and fragmentation of the landscape

(R. Guyette. 2000. Notes on fire history at three sites in the

Lower Atoka Hills adjacent to the Arkansas River. On file with:

School of Natural Resources, I-30 Agriculture Building,

University of Missouri, Columbia, MO 65211).

CONCLUSIONS

Natural pollen traps—sediment deposits containing fossilized pollen—have not been found in the Wedington study

area, or, more generally, in the Ozark-St. Francis National

Forests. This discussion presents a broad-brush comparison using data from adjacent regions. Pollen and geological studies suggest that over the last 40,000 years, climate

has been the major driving force behind changes in plant

communities across the landscape (Bousman 1991). Around

16,000 years ago, dominant tree species included pine

(29.3 percent), oak (16.9 percent), willow (16.5 percent),

and hickory (10.1 percent), with about 50 percent canopy

cover. Current landforms developed around 7,500 years

ago; since then, there have been at least five periods alternating between aggradation and erosion (Jacobson and

Primm 1997). Around 9,000 years ago, vegetation was

dominated by oak (63.8 percent) and pine (9 percent), with

40 percent canopy cover. Early Indians were highly mobile

and apparently followed large herds of now-extinct animals.

They may have used large fires to drive animals into traps

or to attract grazing herds to certain locations. Human

population was low, and the extent of human-caused and

natural disturbances remains unknown.

Around 5,000 to 6,000 years ago, the current climate and

suite of natural ecosystems developed and included the most

extensive grasslands and lowest percentage of canopy cover

(10 percent, minimum). Oaks continued to grow in dominance (72 percent) and remain at this level today (Bousman

1991). Pines decreased to 5 percent; hickories comprise 6

percent. Indian populations increased during the same

period; they appear to have settled into specific ecological

niches where their activities were concentrated. The Ozark

bluff shelters received extensive settlement at this time and

appear to have been bases for seasonal rounds of plant

and animal exploitation. Human-caused environmental disturbances increased around base camps and gardens and

led to the domestication of wild plants in the Ozarks (Fritz

1985, 1990, 1997). Around 1,500 years ago, tropical cultigens imported from Mexico provided the basis for the development of sedentary life ways. Indians developed large

population centers with settlement concentrated in the flood

plains. Bluff shelters appear to have been used for mortuary

practices and food storage. Fire scar records from trees

indicate a mean fire return interval of 2.43 years during the

late 1700s (R. Guyette. 2000. Notes on fire history at three

sites in the Lower Atoka Hills adjacent to the Arkansas River.

On file with: School of Natural Resources, I-30 Agriculture

Building, University of Missouri, Columbia, MO 65211)

(D.H. Jurney. 2002. Historic fire regime. 19 p. On file with:

Ozark-St. Francis National Forests, 605 W. Main, Russellville,

AR 72801). Based on Texas pollen studies (Bousman

1991), around 1,000 years ago the canopy cover was 20

percent. Today, the percentage of canopy cover has

returned to the level of 8,000 years ago (40 percent).

With the advent of European settlement in the 19th century,

the trend toward nucleated settlement in the flood plains

increased. The rectangular land survey system forced land

grants into shapes oriented north-south, and the average

grant ranged from 40 to 160 acres, arbitrarily chosen from

the available public domain. This pattern of public land distribution forced dispersed settlement into 40- to 160-acre

parcels. Land was first chosen along larger streams where

cultivation was possible, then less suitable land was chosen

by later settlers. By the late 1800s, most of the Ozarks had

been claimed by settlers, and farmsteads dotted the landscape (1 per 110 acres). During this period, a mean fire

return interval of 4.4 years was recorded in fire-scarred

trees (R. Guyette. 2000. Notes on fire history at three sites

in the Lower Atoka Hills adjacent to the Arkansas River.

On file with: School of Natural Resources, I-30 Agriculture

Building, University of Missouri, Columbia, MO 65211)

(D.H. Jurney. 2002. Historic fire regime. 19 p. On file with:

Ozark-St. Francis National Forests, 605 W. Main, Russellville,
50

AR 72801). The increased population density contributed to

a reduction in forest fire spread but increased the impacts

to specific land parcels through logging, plowing, construction of rock fences, and soil depletion from increased erosion. Certain trees such as red cedar, bois d’arc (Maclura

pomifera), and walnut were transplanted for food and

economic purposes to locations where they had formerly

been rare (Jurney 1994).

Acquisition of worn-out farmlands by the USDA Forest

Service in the early 20th century led to the rehabilitation of

many eroded fields and the planting of trees that could

provide a sustained yield of wood products. Fire suppression became a primary concern, and fire was taken out of

the ecosystem. Fire-scarred trees indicate mean return

intervals ranging from 5.3 to 22 years during this period

(R. Guyette. 2000. Notes on fire history at three sites in the

Lower Atoka Hills adjacent to the Arkansas River. On file

with: School of Natural Resources, I-30 Agriculture Building,

University of Missouri, Columbia, MO 65211) (D.H. Jurney.

2002. Historic fire regime. 19 p. On file with: Ozark-St.

Francis National Forests, 605 W. Main, Russellville, AR

72801). The fire atlases for the Bayou and Piney Ranger

Districts from 1935 to 1972 yield data on fire occurrence at

the time. Because fires were immediately suppressed, the

atlases cannot provide extent information, only the area of

the District and number of fires for each period of record.

Dividing the District area by the number of fires and the

number of years in the record, lightning fires ranged from

zero on the St. Francis in the Mississippi Delta, 150 miles

from Wedington, to 111 on the Bayou at the eastern edge of

the Ozark Dome, 50 to 80 miles southeast of the Wedington

study area. This yields a minimum estimate of 6 to 18 lightning fires per million acres per year. Human-caused fires

ranged from 91 on the St. Francis to 672 on the White Rock

(50 miles southeast of Wedington) (D.H. Jurney. 2002.

Historic fire regime. 19 p. On file with: Ozark-St. Francis

National Forests, 605 W. Main, Russellville, AR 72801).

This yields a minimum estimate of 87 to 114 human-caused

fires per million acres per year.

Today, forests resembling presettlement conditions are rare.

The wooded pastures of Wedington Mountain are examples

of old-growth post oak forests, barrens, and savannahs that

have received fewer disturbances by historic settlement

than adjacent areas. It is important that such areas are

managed for their old-growth characteristics to retain the

diverse ecosystems in which they are located. In our

opinion, old-growth wooded pastures exhibit long-term

resiliency, and perhaps maintenance of this ecosystem will

reduce forest susceptibility to infestations such as the red

oak borer and oak decline.

Specific recommendations to preserve and maintain diverse

old-growth ecosystems are presented here for consideration by forest managers. First, we recommend using the

GLO records to develop a GIS layer showing potential

historic vegetation prior to extensive European disturbances. The correlation of GLO vegetation types to soils,

slope/aspect, and land type associations will enhance the

silvicultural prescriptions that are used to plan future

forests. Dendrochronological analysis is recommended to

develop spatial models of natural old-growth distributions of

multiple tree species. Point-specific fire scars should also

be collected from old trees and snags to improve our understanding of the frequency, intensity, and extent of wildfires

in the presettlement ecosystem. Finally, there is a need to

correlate lightning strikes and lightning-caused wildfires

with weather parameters to improve modeling of fire spread

across the Ozark landscape.

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INTRODUCTION

The Ozark Mountains are the dominant physiographic

feature in northern Arkansas. They include over 15 million

ac of oak-dominated forests. Oaks have been important

species in the region over the past 6,000 yrs (Delcourt and

Delcourt 1991), and there are compelling financial and

ecological reasons for maintaining a significant oak component in the landscape. Species such as northern red oak

(Quercus rubra L.), white oak (Quercus alba L.), and black

oak (Quercus velutina Lam.) have historically been, and

continue to be, sources of valuable timber. The harvesting

of these prized species provides economic benefits to the

rural people and communities involved with the logging

industry. From a wildlife perspective, acorns are an essential seasonal food supply for a variety of game species such

as deer, bear, and turkey.

Despite the current abundance of mature oak forests, the

long-term sustainability of oak is uncertain in northern

Arkansas and much of the eastern United States. Difficulties

in naturally regenerating oaks have been documented in

the Lake States (Crow 1988, Lorimer 1993), the northeast

(Abrams 1997), the Appalachians (Carvell and Tryon 1961,

Loftis 1990), and the central hardwood region (including

northern Arkansas) (Graney 1989, Sander 1972, Sander

and Graney 1993). In the Arkansas Ozarks, oak generally is

succeeded by species like blackgum (Nyssa sylvatica

Marsh.), flowering dogwood (Cornus florida L.), red maple

(Acer rubrum L.), and black cherry (Prunus serotina Ehrh.).

There are several possible contributing factors to the oak

regeneration problem. These include acorn predation

(Bowersox 1993), damage to oak seedlings by insects and

diseases (Oak 1993), and excessive tree competition

resulting from decreased fire frequency (Abrams 1992,

Brose and others 1999, Van Lear and Waldrop 1989). The

latter hypothesis, that shade tolerant non-oak species accumulate beneath mature oaks in the absence of fire and

inhibit the recruitment of oak seedlings, has been cited as a

dominant factor by the research community. Yet any of

these factors would hinder or eliminate the development of

advance oak seedlings and saplings. Regardless of the

cause(s), traditional silvicultural practices that simply

involve cutting the overstory without regard to these factors

can lead to upland forests that are compositionally and

structurally different from the previous forest.

The abundance of mature oak forests in northern Arkansas

demonstrates that oak regeneration has not always been a

problem. Indeed, previous disturbance conditions appear to

have facilitated successful oak establishment and development. To better understand current oak regeneration difficulties, it is important to gain information on when and how

today’s mature oak forests regenerated. We selected four

oak stands in north-central Arkansas for detailed study. The

objective was to use tree ring analysis to reconstruct the

patterns of tree establishment in each stand.

METHODS

Study Areas

Four mature white oak-northern red oak-hickory (Carya spp.)

stands in north-central Arkansas were selected for study.

The stands, located in the White River Hills and Springfield

Plateau subsections of the Ozark Mountains (USDA Forest

Service 1999), were on the Sylamore Ranger District of the

Ozark-St. Francis National Forest in Stone County and

Baxter County, AR. Sites were no closer than 0.5 miles from

each other; the distance between the two most widely spaced

stands was 12 miles. Elevations ranged from 700 to 1400 ft.

Soils were Clarksville and Noark very cherty silt loams (Ward

1983, Ward and McCright 1983), and slopes were 8 to 40

percent. Site index for upland oak was 70 ft at base age 50

(Ozark-St. Francis National Forest, unpublished data).

All four stands had been commercially harvested from 1998

to 2000 using the group selection system. With this method,

approximately one-sixth of the area in each stand was regenerated in 0.25–1.0 ac scattered openings. All merchantable

trees in the openings were harvested and removed, while

non-merchantable trees greater than 1-in in d.b.h. (diameter

at breast height) were killed by stem injection with herbicide

(glyphosate). In addition, a commercial thinning from below

was conducted in some parts of the forest matrix between

the openings.

AGE DISTRIBUTION OF OAK FORESTS IN NORTH-CENTRAL ARKANSAS

Rick Soucy, Eric Heitzman, and Martin A. Spetich1

1 Graduate Research Assistant and Assistant Professor, School of Forest Resources, Arkansas Forest Resources Center, University of

Arkansas, Monticello, AR 71656; and Research Forester, USDA Forest Service, Southern Research Station, Hot Springs, AR 71902,

respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—We used tree ring analysis to reconstruct the tree establishment patterns in four mature white oak (Quercus

alba L.)-northern red oak (Quercus rubra L.)-hickory (Carya spp.) forests in the Ozark Mountains of north-central Arkansas. Cross sections were removed from the stumps of 321 recently harvested trees and total age determined for each. All

four stands originated between 1900 and the 1920s following a stand-level disturbance(s) such as timber harvesting and/

or wildfire. Oak establishment was abundant for 10-30 yrs following the disturbance(s) but steadily declined thereafter.

There was no oak establishment at the study sites over the past 50-60 yrs. Establishment since the 1940s and 1950s was

dominated by shade tolerant species such as flowering dogwood (Cornus florida L.) and red maple (Acer rubrum L.)
54

Data Collection

In 2000 and 2001, we established one transect in each

stand and systematically selected three openings for further

study. Depending on stand size, the distance between the

openings chosen was 500 to 2000 ft. In each opening we

established one 0.25-ac circular plot. Using chainsaws, a

cross section was cut from all non-rotten stumps within the

plots that possessed a ground line diameter larger than 2 in.

The cross sections were tallied by species or species group

(e.g., red oak). In most of the openings, at least several

unmerchantable trees were not felled during harvesting. We

felled and removed cross sections from the stumps of these

trees if their ground-line diameters exceeded 2 in. In all, we

collected 321 sound cross sections.

To calculate the pre-harvest tree density and basal area in

each stand, we sampled the forest matrix between the openings. Two 0.05-ac overstory/midstory plots were established

100 ft north and south of the northern and southern boundaries of each opening sampled; 6 plots were established

in each stand. Plots were offset if they included skid trails

or areas that had been commercially thinned. Within each

plot, species and d.b.h. were tallied for all living trees

greater than 4.5 in d.b.h.

Laboratory Procedures

Tree cross sections were transported to the University of

Arkansas – Monticello for preparation and analysis. Each

cross section was sanded with progressively finer sandpaper so that individual tree rings were clearly visible. Tree

age for each cross section was determined by counting the

tree rings under a dissecting microscope. About ten percent

of the samples were independently recounted to check the

precision of our work. The mean difference between the

original counts and recounts was 2.1 yrs. Tree ages were

grouped by decade to reconstruct tree establishment and

stand development patterns at each site.

RESULTS AND DISCUSSION

Stand Structure

The four stands were similar in terms of total overstory/

midstory tree density and basal area (table 1). Densities

ranged from 193 to 204 trees per ac, and basal areas varied

from 114 to 122 ft2 per ac. White oak, red oak (including

northern red oak and black oak), and hickories were the

dominant species. In each stand, they combined for at least

92 percent of the tree density and at least 96 percent of the

basal area. There were more white oak stems than red oak

or hickory in all four stands. Associated species included

flowering dogwood, red maple, eastern redcedar (Juniperus

virginiana L.), and shortleaf pine (Pinus echinata Mill.).

Age Distribution

The age distributions of the study areas exhibited a number

of similarities (figs. 1A through 1D). First, there was an

abrupt pulse of tree establishment beginning in the 1900s

(fig. 1C) or 1910s (figs. 1A, 1B, and 1D). It is likely that a

disturbance such as timber harvesting and/or wildfire triggered this regeneration response by removing all or portions

of the forest canopy. Separate age distributions of each

0.25-ac plot (not depicted) indicate that disturbances were

likely stand-level in scale. That is, an establishment pulse

during a particular decade in one plot was also evident in

the other two plots in that stand.

Second, few of the trees we sampled originated prior to

1900. Although red oaks are not particularly long-lived – for

example, physiological maturity of black oak occurs near

age 100 (Sander 1990) – white oak is a long-lived species

with rotation ages of 120+ yrs (Rogers 1990). Therefore,

some older trees probably were killed by the same disturbance(s) responsible for the regeneration pulse. The nearabsence of older trees also suggests that post-disturbance

establishment was dominated by either germinating seedlings or the release of advance regeneration.

Third, tree establishment was particularly abundant for 10

to 30 yrs following disturbance, but steadily decreased with

increasing stand age. Perhaps the initial disturbance in each

stand was the sole disturbance, or subsequent disturbances

were relatively small and had little effect on establishment.

Lorimer (1985) observed that examining age distributions

alone may be insufficient to reconstruct stand disturbances.

We are currently analyzing tree radial growth patterns to

more accurately describe disturbance history of the study

areas.

Table 1—Stand characteristics of trees greater than 4.5 in dbh at the four study sites

Stand 1 Stand 2 Stand 3 Stand 4

Species Density Basal area Density Basal area Density Basal area Density Basal area

trees/ac ft2/ac trees/ac ft2 /ac trees/ac ft2 /ac trees/ac ft2/ac

White oak 93 46 80 46 87 48 110 73

Red oaka 73 60 47 44 53 63 43 32

Hickories 20 7 60 21 43 10 37 11

Flowering

dogwood — — 10 2 7 1 3 1

Otherb 10 5 7 1 3 < 1 7 1

Totals 196 118 204 114 193 122 200 118

a Includes northern red oak and black oak.

b Includes red maple, eastern redcedar (Juniperus virginiana L.), and shortleaf pine (Pinus echinata Mill.).
55

Finally, different species established at certain times. White

oak and red oak aggressively colonized the disturbed study

areas from the 1900s through the 1920s (fig. 1A-1D). In the

1930s, white oak continued to establish, albeit at reduced

levels, but red oak establishment ceased and never resumed.

Although white oak is considered intermediate in shade tolerance, it is more tolerant than northern red oak and black oak,

and is most tolerant as a seedling or sapling (Rogers 1990).

White oak was clearly able to establish in the shaded conditions of the developing stands better than red oaks. Yet

after the 1930s, white oak establishment also decreased

and ceased by 1950 to 1970. Coincident with the cessation

in oak establishment was an increase in establishment of

shade tolerant species such as flowering dogwood and red

maple (fig. 1A-1D). These species consistently established

from the 1930s through the 1970s and 1980s; field observations at the study sites indicated they were abundant in

seedling and sapling size classes not sampled in this study.

CONCLUSIONS

The four mature oak stands we studied in north-central

Arkansas originated following stand-level disturbances that

occurred between 1900 and 1930. Following the disturbances, oak establishment continued for decades, with the

more tolerant white oak establishing for a longer period

than red oaks. Few white oaks, and no red oaks, established

at the study sites over the past 50 to 60 yrs. Instead, establishment became dominated by shade tolerant species.

These results demonstrate that disturbance is a prerequisite

for successful oak regeneration. Current investigations into

tree radial growth patterns should provide additional information on the type and frequency of disturbances at the

study sites.

ACKNOWLEDGMENTS

Financial support was provided by the Southern Research

Station of the USDA Forest Service. We are grateful to Bob

Rhodey of the Ozark-St. Francis National Forest for his

technical assistance.

LITERATURE CITED

Abrams, M.D. 1992. Fire and the development of oak forests.

Bioscience. 42: 346-353.

Abrams, M.D. 1997. Does the absence of sediment charcoal provide substantialevidence against the fire and oak hypothesis?

Journal of Ecology. 85: 373-380.

Figure 1—Age distributions for trees greater than 2 in at ground-line diameter at (A) Stand 1, (B) Stand 2, (C) Stand 3, and (D) Stand 4. Note

that the “Other” category includes blackgum, red maple, and sassafras (Sassafras albidum (Nutt.) Nees).
56

Bowersox, T.W. 1993. Artificial regeneration of oaks in the uplands.

In: Oak regeneration: serious problems, practical recommendations (D. Loftis and C.E. McGee, eds.). USDA Forest Service

General Technical Report SE-84, pp. 250-263.

Brose, P.H.; Van Lear, D.H.; Keyser, P.D. 1999. A shelterwood-burn

technique for regenerating productive upland oak sites in the

Piedmont region. Southern Journal of Applied Forestry. 16:

158-163.

Carvell, K.L.; Tryon, E.H. 1961. The effect of environmental factors

on the abundance of oak regeneration beneath mature stands.

Forest Science. 7: 98-105.

Crow, T.R. 1988. Reproductive mode and mechanisms for selfreplacement of northern red oak (Quercus rubra) – a review.

Forest Science. 34: 19-40.

Delcourt, H.R.; Delcourt, P.A. 1991. Late-quaternary vegetation

history of the Interior Highlands of Missouri, Arkansas, and

Oklahoma. In: Proceedings of the conference on the restoration

of old growth forests in the Interior Highlands of Arkansas and

Oklahoma (D. Henderson and L.D. Hedrick, eds). USDA Forest

Service, Ouachita National Forest; Winrock Institute for

Agricultural Development, pp. 15-30.

Graney, D.L. 1989. Growth of oak, ash, and cherry reproduction

following overstory thinning and understory control in upland

hardwood stands of northern Arkansas. In: Proceedings of the

fifth biennial southern silvicultural research conference; 1988

November 1-3; Memphis, TN. USDA Forest Service General

Technical Report SO-74, pp. 245-252.

Loftis, D.L. 1990. A shelterwood method for regenerating red oak

in the Southern Appalachians. Forest Science 36. 4: 917-929.

Lorimer, C.G. 1985. Methodological considerations in the analysis

of forest disturbance history. Canadian Journal of Forest

Research. 15: 200-213.

Lorimer, C.G. 1993. Causes of the oak regeneration problem. In:

Oak regeneration: serious problems, practical recommendations (D. Loftis and C.E. McGee, eds.). USDA Forest Service

General Technical Report SE-84, pp. 14-39.

Oak, S.W. 1993. Insects and diseases affecting oak regeneration

success. In: Oak regeneration: serious problems, practical

recommendations (D. Loftis and C.E. McGee, eds.). USDA

Forest Service General Technical Report SE-84, pp. 105-111.

Rogers, R. 1990. Quercus alba L. White oak. In: R.M. Burns and

B.H. Honkala (eds.), Silvics of North America, volume 2, hardwoods. USDA Forest Service Agriculture Handbook 654, pp.

605-613.

Sander, I.L. 1972. Size of oak advance reproduction: key to growth

following harvest cutting. USDA Forest Service Research Paper

NC-79.

Sander, I.L. 1990. Quercus velutina Lam. Black oak. In: R.M. Burns

and B.H. Honkala (eds.), Silvics of North America, volume 2,

hardwoods. USDA Forest Service Agriculture Handbook 654,

pp. 744-750.

Sander, I.L.; Graney, D.L. 1993. Regenerating oaks in the Central

States. In: Oak regeneration: serious problems, practical

recommendations (D. Loftis and C.E. McGee, eds.). USDA

Forest Service General Technical Report SE-84, pp. 174-183.

USDA Forest Service. 1999. Ozark-Ouachita Highlands Assessment: terrestrial vegetation and wildlife. Report 5 of 5. USDA

Forest Service General Technical Report SRS-35.

Van Lear, D.H.; Waldrop, T.A. 1989. History, uses, and effects of

fire in the Appalachians. USDA Forest Service General

Technical Report SE-54.

Ward, L.B. 1983. Soil survey of Stone County, Arkansas. USDA

Soil Conservation Service, Washington DC, 152 pp.

Ward, L.B.; McCright, R.T. 1983. Soil survey of Baxter and Marion

Counties, Arkansas. USDA Soil Conservation Service,

Washington DC, 136 pp.
57

INTRODUCTION

Humans have dramatically changed forest composition,

disturbance regimes, and understory dynamics across most

of North America. Very few stands remain that retain sufficient ecological integrity to use as standards for restoration,

and new perturbations continually alter these remnants.

This challenges stewards and researchers who desire to

maintain certain features of the natural environment, especially when the management objects are isolated parcels in

a matrix of unprotected forests.

To describe how the forests of Arkansas have changed,

researchers have examined narratives of early explorers

(Strausberg and Hough 1997), historical documents and

photographs (Smith 1986), and General Land Office (GLO)

survey notes (Bragg 2003, Foti and Glenn 1991). All of

these sources can contribute to our understanding of forest

composition and structure. However, the quality of any

historical information must be thoroughly evaluated before

inferring definitive ecological conclusions (Forman and

Russell 1983, Noss 1985). Reliable information is critical

when assessing long-term change in remnant stands of oldgrowth forest.

The 113-ha Lake Winona Research Natural Area (LWRNA)

has been preserved as a relic old forest in the Ouachita

Mountains of central Arkansas (Fountain and Sweeney

1987). Little is known about the developmental history of

the LWRNA, limiting its utility as a case study of forest

change. This study is intended to supplement existing

ecological research on the eastern Ouachita Mountains

including the LWRNA, with special emphasis on long-term

patterns of overstory oak dynamics.

METHODS AND MATERIALS

Study Area

Located in the Ouachita Mountains of western Saline County,

the study area lies approximately 50 km west of Little Rock

and encompasses the whole GLO-surveyed area of

Township 2 North, Range 18 West (T2N R18W). The LWRNA

(fig. 1) falls entirely within T2N R18W. Since the whole township is relatively uniform in landform and vegetation, and

rather than abbreviating the already limited GLO data to the

small area encompassed by the LWRNA, the data for the

LWRNA will be considered detailed enough for comparison

with the larger GLO results. In terms of relative species

composition and stand development patterns, this assumption should not be too problematic.

Fountain and Sweeney (1987) described the environment

of the LWRNA, which is typical of the region as a whole.

The landscapes are predominately steep hills and low mountains, with slopes ranging from gentle (5 to 10 percent) to

very steep (> 50 percent). Sandstones and shales dominate

the bedrock of the region, and the colluvial-origin soils are

primarily Typic Hapludults. Alum Fork, a major tributary of

the upper Saline River, and many small creeks drain the

township.

Data Sources

This comparison was taken from three main sources: the

original land survey (GLO) notes (Daniels 2000), an ecological assessment of the LWRNA (Fountain and Sweeney

1987), and a trade journal report on the lumbering potential

of the region (Anonymous 1904). These reports, coupled

with other historical and modern references, describe the

forest conditions of the LWRNA region from the early 1800s

to the present.

For many years researchers have used GLO survey notes

to describe presettlement vegetation patterns, e.g., Bourdo

1956, Delcourt 1976, and Lutz 1930, although there are

some challenges with their interpretation related to surveyor

bias, scale incompatibility, and species clarity (Bragg 2003,

Schulte and Mladenoff 2001, Whitney and DeCant 2001).

For example, Bragg (2003) reported on the uncertainties

related to surveyor species delineations, including the

timing of most survey work (November to March, during the

dormant season), the surveyors’ lack of formal taxonomic

PATTERNS OF OAK DOMINANCE IN THE EASTERN OUACHITA MOUNTAINS

SUGGESTED BY EARLY RECORDS

Don C. Bragg1

1 Research Forester, USDA Forest Service, Southern Research Station, Monticello, AR 71656.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Many years of human influence across the Interior Highlands have caused profound changes in forest

composition, disturbance regimes, and understory dynamics. However, information on the historical condition of these

forests is limited. General Land Office (GLO) records, old documents, and contemporary studies provided data on the

township encompassing the Lake Winona Research Natural Area (LWRNA). The study area was first surveyed between

1821 and 1838, and few settlers had settled this mountainous region by the 1930s. A 1987 ecological assessment of the

LWRNA, coupled with other reports, supplemented the GLO descriptions. The original surveys tallied at least 15 species

of witness trees, primarily white oak (Quercus alba L.), black oak (Q. velutina Lam.), shortleaf pine (Pinus echinata Mill.),

blackgum (Nyssa sylvatica Marsh.), and post oak (Q. stellata Wang.). A 1931 resurvey identified at least 14 taxa, but by

then the witness trees had become overwhelmingly shortleaf pine, with much less oak. Forest composition in the LWRNA

is shifting once again toward oak dominance, with a prominent pine supercanopy.
58

training, and their use of nonspecific or obscure common

names. Though these concerns may limit interpretation of

GLO records, the survey notes still represent the best

available quasi-quantitative information on presettlement

vegetation conditions.

The township and range lines of T2N R18W were surveyed

as early as 1821, with most of the interior section lines

completed in early 1838. For simplicity, I refer to these data

as the “Original 1838 data” since the GLO completed the

vast majority of the interior lines during that year. As an

aside, John R. Conway surveyed much of the study area.

A member of an early regional political dynasty, Conway’s

father, John S., was the first governor of Arkansas, his older

brother Henry was an Arkansas congressman, brother

Frederick was the surveyor-general of Missouri, brother

Figure 1—The 1840 plat map of T2N R18W, showing the approximate location of major drainages and the LWRNA.

Alum Fork, Saline River

Lake Winona

T2N R18W

RNA
59

William was an Arkansas supreme court justice, and

brother Elias became governor of Arkansas in 1852

(Herndon 1922).

By 1931, a resurvey of T2N R18W was commissioned. The

notes do not give any justification for this effort, although it

could be related to an ownership dispute. Arthur W. Brown,

a federal surveyor, undertook the resurvey of T2N R18W

between August and December of 1931 and relocated

approximately half of the original corners. Many of the

witness trees had died or been cut since the original GLO

survey, so most corners required remonumentation. Another

resurvey of a portion of the township was completed in the

mid-1970s when the U.S. Department of Agriculture Forest

Service requested a survey of the Lake Winona spillway

elevation. However, I did not include this traverse because

of the very limited area surveyed within T2N R18W.

The Ouachita National Forest established the LWRNA in

1977 to preserve a remnant of the pine-hardwood forest

that once dominated much of the Ouachita Mountains. In a

baseline ecological assessment, Fountain and Sweeney

(1987) reported an overstory of > 100-year-old shortleaf

pine (Pinus echinata Mill.) and a mid- and understory overwhelmingly dominated by oaks (Quercus spp.), hickories

(Carya spp.), gums (Liquidambar sp. and Nyssa sp.), and

shrubs. They predicted that the lack of fire, coupled with

individualistic pine mortality from disease, insects, wind,

and lightning, would eventually lead to a hardwood-dominated overstory.

I searched the GLO records for any witness or line trees

with the surveyors’ assignment of species and an estimated

diameter. The common names given by the surveyors

(table 1) are probably reliable to species for the most obvious taxa, e.g., white oak (Q. alba L.), but are only accurate

to genera for others, e.g., hickory. The 1987 assessment

of the LWRNA was conducted by trained ecologists and

foresters using modern equipment and measurement protocols, and hence better reflects the true distribution of vegetation. The taxonomic assignments by Fountain and Sweeney

(1987) were assumed to be accurate to species. For broad

discussion, species groups have been used to simplify the

naming conventions. Hence, the white oak group includes

white oak and post oak (Q. stellata Wang.); the red oak

group consists of southern red oak (Q. falcata Michx.),

black oak (Q. velutina Lam.), blackjack oak (Q. marilandica

Muenchh.), and spotted oak (Q. shumardii Buckl.); the

hickory group probably contains several Carya; the gums

consist of blackgum (N. sylvatica Marsh.) and sweetgum (L.

styraciflua L.); the conifer group includes eastern redcedar

(Juniperus virginiana L.) and shortleaf pine; and other hardwoods contain all other minor hardwood taxa.

RESULTS

The original GLO survey of the LWRNA region in the early

1800s described a largely untouched wilderness, with oaks

and pine dominating the overstory (table 2). The 1838

survey reported at least 15 taxa. Witness trees were mostly

white oak, black oak, shortleaf pine, blackgum, and post

oak. Blackjack oak, commonly found in open, fire-dominated sites, was used several times as a witness tree. Other

minor shade-tolerant species such as flowering dogwood

Table 1—Common names of trees used by the 1821–

1838 and 1931 surveyors in T2N R18W, and their

probable taxonomic equivalents

Surveyor name Probable scientific namea

Pignut hickory Carya cordiformis (Wang.) K. Koch

Hickory C. spp.

Chinkapin Castanea pumila (L.) Mill. var. ozarkensis

(Ashe) Tucker

Dogwood Cornus florida

Ash Fraxinus spp.

Holly Ilex opaca

Cedar Juniperus virginiana

Sweetgum Liquidambar styraciflua

Gum L. styraciflua, Nyssa sylvatica

Mulberry Morus rubra L.

Blackgum N. sylvatica

Pine Pinus echinata

Cherry Prunus serotina Ehrh.

White oak Quercus alba

Red oak Q. falcata, Q. rubra, Q. velutina

Blackjack oak Q. marilandica

Spotted oak Q. shumardii

Post oak Q. stellata

Black oak Q. velutina, Q. rubra L., Q. falcata

Elm Ulmus spp.

a Multiple species are listed if several options are possible.

(Cornus florida L.) and American holly (Ilex opaca Ait.) were

mentioned, but their infrequent usage suggests that their

presence in the early 1800s was limited.

The intervening century found the region gradually settled,

logged, and farmed. Most witness trees in the 1931 resurvey

were small-diameter shortleaf pine (fig. 2), followed by

white oak, blackgum, and post oak. Surveyor A.W. Brown

noted much of mature pine and oak had been removed,

although some areas still contained virgin timber. Brown

placed the hickory, gum, elm (Ulmus spp.), ironwood [Ostrya

virginiana (Mill.) Koch.], and holly along the creek bottoms

implying that their presence in upland areas was limited.

Brown’s report also stated that “[p]ractically the entire township produces a very good growth of native grasses, but the

efforts of the Forest Service to get settlers to launch more

extensively into the cattle business have so far proved

rather fruitless,” and later “timber on the hillsides is quite

free of undergrowth” (Brown 1931).

During the next half-century, much of the township experienced timber harvest and fire suppression. The 1987 LWRNA

inventory indicated a decline in pine dominance and a resurgence of oak importance. Conifers (mostly shortleaf pine)

had decreased from almost 74 percent of surveyed stems

to < 35 percent of trees in the LWRNA inventory (fig. 2).

White and red oaks, gums, and other hardwoods increased

noticeably and dominated the understory (Fountain and

Sweeney 1987), which had virtually no shortleaf pine or

eastern redcedar. The white oak group comprised nearly

one-third of the stems in the LWRNA, and the red oak group

increased to almost 11 percent, or over five times their
60

presence just 50 years earlier. Hickories, gums, and other

minor hardwood species also increased their stocking,

although they still represent a minor component (about

20 percent) of the stand.

DISCUSSION

Comparison of GLO data with Fountain and Sweeney’s

work suggests that pine gained more prominence between

the early 1830s and 1930, with a concurrent decrease in

Table 2—Common names of species (and counts) noted in the GLO surveys

of T2N R18W and the LWRNA

1838 GLOa 1931 Resurveya 1987 LWRNA inventoryb

White oak (135) Pine (299) Shortleaf pine (456)

Black oak (91) White oak (58) White oak (408)

Pine (78) Blackgum (19) Blackgum (108)

Blackgum (13) Post oak (14) Red maple (75)

Post oak (11) Black oak (5) Black oak (71)

Hickory (8) Sweetgum (3) Post oak (58)

Sweetgum (5) Ash (2) Hickory (48)

Blackjack oak (4) Cedar (2) Blackjack oak (37)

Dogwood (3) Blackjack oak (1) Dogwood (40)

Elm (3) Gum (1) Southern red oak (34)

Gum (3) Hickory (1) (many other hardwoods present)

Holly (2) Holly (1)

Red oak (2) Pignut hickory (1)

Cherry (1) Red oak (1)

Chinkapin (1) Spotted oak (1)

Mulberry (1)

a Common names as provided by the surveyors; count totals are for the entire T2N R18W.

b Trees per hectare for the “dominant” species on the LWRNA.

oak. Regional forest dynamics changed markedly during

this period, especially after commercial logging began early

in the 20th century (Shelton and Murphy 1990, Smith 1986).

The frequency of hardwoods in the 1838 GLO notes suggests

that these hills had undergone a remarkable transformation

by the 1930s. Harvesting and fire, coupled with land clearing, probably improved shortleaf pine establishment, resulting in large numbers of small pine being utilized as witness

trees by the 1931 resurvey.

Figure 2—Frequency distribution of major species groups in the original Government Land Office

surveys and the 1987 LWRNA inventory (see text for group delineations).

Species group

Total (percent)

0

10

20

30

40

50

60

70

80

90

100

White

oaks

Red

oaks

Hickories Gums Other

hardwoods

Conifers

1931 Township resurvey

1987 LWRNA inventory

1838 Original GLO survey
61

However, because of uncertainty in how surveyors actually

selected their witness trees, I did not further quantify oak

and pine composition. Even though the oldest GLO notes

suggested the prominence of oaks and other hardwoods,

the surveyors’ preferences may have biased tree selection.

For example, it is possible that hardwoods were chosen

more frequently than shortleaf pine because they contrasted

with a pine overstory (Bourdo 1956, Bragg 2003). If so, the

abundance of some hardwood species from the initial GLO

surveys may exceed their true historical representation.

Other reports, e.g., Smith 1986, disagree with the relative

dominance of hardwoods suggested by the GLO notes.

Early (pre-1900) observations on the study region indicated

shortleaf pine was the dominant overstory species. For

instance, Anonymous (1904) reported pine sawtimber volume five times that of hardwoods in the eastern Ouachita

Mountains. However, Anonymous (1904) alone is not definitive proof of an informational discontinuity, because this

nonrefereed (and even promotional) source may reflect

biases that emphasize the commercial potential of the region.

Additionally, merchantable sawtimber does not directly translate into stocking proportions, especially if the hardwoods

were predominantly small-diameter, poorly formed stems.

Oaks and other hardwoods have probably long held subordinate positions in the Ouachita Mountains of central

Arkansas, especially on exposed sites in fire-prone areas.

However, given the absence of large-scale catastrophic

disturbances like fire or timber harvesting, it is likely that the

mixed pine-hardwood overstory of the LWRNA will gradually revert to a hardwood-dominated stand. In a secondgrowth pine-oak stand near the LWRNA, Shelton and

Murphy (1990) reported a noticeable decline in smaller pine

size classes and increased representation by white oak,

southern red oak, and other hardwoods. However, if borers,

sudden oak decline, drought, or similar destructive agents

arise, then the LWRNA may develop a greater prominence

of hickory, gum, red maple (Acer rubrum L.), and other

hardwoods.

CONCLUSIONS

Barring a major disturbance, the dominance of closedcanopy hardwood under- and midstories means the existing

supercanopy of shortleaf pine will not replace itself. Unless

constrained by decline, oaks (especially white and black

oak) are poised to replace shortleaf as the pines succumb

to age, insects, lightning, and other causes. The long-term

preservation of current conditions, i.e., shortleaf pine dominance, at the LWRNA is highly unlikely, but whether or not

oaks will reach and maintain their expected importance is

less certain.

ACKNOWLEDGMENTS

I thank the following for their contributions to this research:

Hope Bragg, Adrian Grell, Eric Heitzman, Mike Shelton, and

Bruce Walsh.

LITERATURE CITED

Anonymous. 1904. The heart of Arkansas’ shortleaf pine belt and

phases of its growth. American Lumberman. December: 35-40.

Bourdo, E.A. 1956. A review of the General Land Office survey and

of its use in quantitative studies of former forests. Ecology. 37:

754-768.

Bragg, D.C. 2003. Natural presettlement features of the Ashley

County, Arkansas area. American Midland Naturalist. 149: 1-20.

Brown, A.W. 1931. Dependent resurvey of T. 2 N., R. 18 W., 5th

principal meridian, Arkansas. In: Daniels, C., comm. Original

General Land Office survey notes and plats for the State of

Arkansas, 1815-present. Little Rock, AR: State Lands

Commission. 16 CDs.

Daniels, C., comm. 2000. Original General Land Office survey

notes and plats for the State of Arkansas, 1815-present. Little

Rock, AR: State Lands Commission. 16 CDs.

Delcourt, H.R. 1976. Presettlement vegetation of the north of Red

River land district, Louisiana. Castanea. 41: 122-139.

Forman, R.T.T.; Russell, E.W.B. 1983. Evaluation of historical data

in ecology. Bulletin of the Ecological Society of America. 64: 5-7.

Foti, T.L.; Glenn, S.M. 1991. The Ouachita Mountain landscape at

the time of settlement. In: Henderson, D.; Hedrick, L.D., eds.

Proceedings of the conference on the restoration of old growth

forests in the Interior Highlands of Arkansas and Oklahoma.

Morrilton, AR: Winrock International Institute: 49-65.

Fountain, M.S.; Sweeney, J.M. 1987. Ecological assessment of the

Lake Winona Research Natural Area. Res. Pap. SO-235. New

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

Southern Forest Experiment Station. 14 p.

Herndon, D.T. 1922. Centennial history of Arkansas. Chicago: S.J.

Clarke Publishing Co. 1,035 p. Vol. 1.

Lutz, H.J. 1930. Original forest composition in northwestern

Pennsylvania as indicated by early land survey notes. Journal

of Forestry. 28: 1098-1103.

Noss, R.F. 1985. On characterizing presettlement vegetation: how

and why. Natural Areas Journal. 5: 5-19.

Schulte, L.A.; Mladenoff, D.J. 2001. The original US public land

survey records—their use and limitations in reconstructing

presettlement vegetation. Journal of Forestry. 99: 5-10.

Shelton, M.G.; Murphy, P.A. 1990. Age and size structure of a

shortleaf pine-oak stand in the Ouachita Mountains—implications for uneven aged management. In: Coleman, S.S.; Neary,

D.G., eds. Proceedings of the sixth biennial southern silvicultural research conference. Gen. Tech. Rep. 70. Asheville, NC:

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

Forest Experiment Station: 616-629. Vol. 2.

Smith, K.L. 1986. Historical perspective. In: Murphy, P.A., ed.

Proceedings of the symposium on the shortleaf pine ecosystem.

Little Rock, AR: University of Arkansas Cooperative Extension

Service: 1-8.

Strausberg, S.; Hough, W.A. 1997. The Ouachita and Ozark-St.

Francis National Forests: a history of the lands and USDA

Forest Service tenure. Gen. Tech. Rep. SO-121. Asheville, NC:

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

Research Station. 45 p.

Whitney, G.G.; DeCant, J. 2001. Government Land Office survey

and other land surveys. In: Egan, D.; Howell, E.A., eds. The

historical ecology handbook. Washington, DC: Island Press:

147-172.
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63

Upland Oak Forest Ecology

and Wildlife Ecology
64
65

INTRODUCTION

As the Wisconsin ice sheets retreated to the North toward

the end of the Pleistocene Epoch, tundra and boreal vegetation that had dominated the Central Hardwood Region

began to be replaced by hardwood species. Spurred on by

the warming climate and the widespread use of fire by

Native Americans, oaks (Quercus spp.) gradually dominated

the region (Abrams 2002, Carroll and others 2002).

Fire, early man’s only tool to manipulate the landscape, has

been a major ecological process shaping the pattern, composition, and structure of vegetation in the eastern United

States. Frequent fires set by man and lightning kept the

forests open and park-like. Fire regimes characterized by

frequent, low-intensity burns favored plants adapted to

survive these types of fires. Oaks and other fire-adapted

species benefitted from this fire regime and were able to

out-compete less fire-adapted species and dominate much

of the Central Hardwood Region.

Regenerating oaks on productive upland sites has been a

major silvicultural challenge for decades in eastern hardwood forests (Carvell and Tryon 1961, Clark and Watts 1971,

Loftis and McGee 1993). Could land-use history tell us why

oaks cannot be regenerated on good quality sites? We know

that fire was a much more dominant factor historically than

it is today. In fact, foresters had long considered taboo the

use of fire in hardwood management. However, in the last

two decades, the use of fire by Native Americans to manage

the landscape has become more appreciated (Pyne 1982,

Buckner 1983, Pyne and others 1996, Bonnicksen 2000,

Carroll and others 2002).

Recent books about oak ecology and management provide

excellent treatments of these broad topics (Hicks 1998,

Johnson and others 2002, McShea and Healy 2002). Therefore, I will confine my remarks to the fire ecology of upland

oaks and how fire can be used silviculturally to sustain oak

forests in various ecological conditions.

LAND-USE HISTORY AND ITS ROLE IN

SUSTAINING OAK FORESTS

Man is intimately linked to the distribution and dominance

of oak in the Central Hardwood Region. About 12,000 years

ago, Native Americans made their way into North America

(Williams 1989, Bonnicksen 2000, Carroll and others 2002).

They used fire in many ways because it helped them survive

and improved their quality of life. Over thousands of years,

the American Indian became expert in using fire for various

purposes, e.g., for hunting, to concentrate game in convenient areas, to encourage fruit and berry production, to keep

the woods open along major corridors of travel, to fire-proof

their villages, and for many other uses (Williams 1989,

Pyne and others 1996, Bonnicksen 2000). Anthropogenic

burning was certainly more important than lightning-ignited

fires in shaping the vegetative character of the Central

Hardwood Region.

The Native American population of North America has been

estimated as high at 18 million at the time of Columbus

(Dobyns 1983). Their influence on the eastern forest was

far out of proportion to their population density, primarily

because of their use of fire (Hudson 1976). Because of their

high populations and burning activities, Native Americans

ensured that much of the Central Hardwood Region was

relatively open woodlands, savannahs, and prairies. The

eastern United States in 1500 was a managed landscape

and had been for thousands of years (Buckner 1983,

Williams 1989, MacCleery 1992, Pyne and others 1996,

Carroll and others 2002)

Indians burned frequently, complementing lightning as an

ignition source. Their burning extended the fire season

beyond the “natural” lightning-fire season of summer. After

UPLAND OAK ECOLOGY AND MANAGEMENT

D.H. Van Lear1

1 Bowen Professor of Forestry, Department of Forest Resources, Clemson University, Clemson, SC 29634-1003.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Of the many disturbance factors that shaped hardwood forests in the eastern United States, fire was perhaps

the most important. Fires ignited by Native Americans and lightning played a dominant role in sustaining oak (Quercus

spp.) forests throughout the Central Hardwood Region. Prior to logging at the turn of the last century, fires in the region

were mostly light to moderate intensity surface fires. Exclusion of frequent surface fires for over 70 years has changed the

character of these previously open forests and contributed to the gradual invasion of oak stands by shade-tolerant, fireintolerant species. Although upland oaks are more easily maintained on poor quality sites, sustaining oak species on good

quality sites is difficult. When canopy-gap type disturbances occur on good sites, oak regeneration is not competitive

enough to grow into the mid- and upper canopy. If there is a major disturbance in the overstory of these mixed stands,

pioneer shade-intolerant species such as yellow-poplar (Liriodendron tulipifera)out-compete oak regeneration and

dominate the next stand. Periodic underburning in mixed hardwood stands creates conditions similar to those prior to fire

exclusion and are conducive to oak regeneration and establishment. A shelterwood-burn technique has recently been

developed that can be used on productive upland sites to enhance the competitive position of oaks in the advance

regeneration pool. Oaks are well adapted to tolerate fire and benefit from fire at the expense of their competitors.

Foresters can use prescribed fire where feasible to sustain oaks in a variety of ecosystem conditions ranging from fully

stocked timber stands to open oak woodlands.
66

Indian populations plummeted in the 16th and 17th centuries

from exposure to European diseases, their level of burning

declined and the forest became uncommonly dense (Carroll

and others 2002).

Early European settlers displaced the Indians, but continued

using fire for many of the same reasons, i.e., to clear the

woods of underbrush, to expose nuts, to clear agricultural

fields, and to enhance grazing. Not until the early decades

of the 20th century were there serious efforts to exclude fire

as an ecological process in eastern North America. However, burning was still a common practice into the 1940s

and 50s in the Southern Appalachian Mountains and the

Ozark Highlands (Pyne and others 1996, Carroll and others

2002).

Widespread attempts to exclude fire, combined with exploitive logging of early successional species, e.g., shortleaf

pine (Pinus echinata) from the Ozark highlands, enabled

the modern oak forest to develop rapidly across much of

eastern North America (Dey 2002). An era of fire exclusion

had begun that would produce different environments from

those that had existed in previous millennia and which

would have numerous unexpected consequences (Brose

and others 2002).

Now oaks are not being sustained on good quality sites

(Healy and others 1997, McWilliams and others 2002).

Land-use history — a history based not only on written

history (Hudson 1976, Dobyns 1983, MacCleery 1992) but

also on nature’s history as recorded in sediment cores

showing pollen and charcoal distribution for thousands of

years (Watts 1983, Delcourt and Delcourt 1987, Carroll and

others 2002), clearly demonstrates the important role fire

once played in the eastern United States. It is reasonable

to conclude that a policy of fire exclusion over much of the

past century is a major cause of our inability to regenerate

oaks on better sites today. Of course, there are other

factors that are important in certain areas, especially overbrowsing by deer (Lorimer 1993). But exclusion of fire, in

my opinion, is the primary reason for the disturbing trend of

oaks failing to regenerate on good quality sites throughout

much of the Central Hardwood Region.

ADAPTATIONS OF OAKS TO FIRE

Fire has been so ubiquitous and exerts such profound influences on the environment that it is reasonable to assume

that natural selection favored individuals in populations that

could best survive fire (Pyne and others 1996). Plant species

that evolved with fire adapted by developing attributes that

increased their chances of survival in those environments.

Among the fire-adaptations of oaks is their tenacious ability

to resprout repeatedly, after other species have died, from

root collar buds following topkill by fire (Waldrop and others

1987). The ability to resprout time after time after their tops

are killed would improve oak survival rates because they

would continually occupy the same growing space over long

periods of time, beyond the elimination of other species.

Oaks have thick bark which insulates their living cambium

from the heat of surface fires (Hare 1965). Competing

species such as maples (Acer spp.) and American beech

(Fagus grandifolia) have thinner bark, especially when

young, and are quite susceptible to fire damage or mortality.

Because acorns are often buried by squirrels and/or jays

(Sciuridae and Corvidae) and germination is hypogeal,

root-collar buds of oaks are well protected from the heat of

surface fires (soil is a poor conductor of heat). Many of

oaks’ competitors, such as yellow-poplar, have seeds that

germinate on the soil surface and thus have exposed buds

which are more susceptible to mortality from fire (Brose and

Van Lear 1998, Brose and others 1999a, Brose and others

1999b). A major reason why oaks tolerate fire better than

most competitors is because oak sprouts often originate

beneath the soil surface (Burns and Honkala 1990).

Some adaptations not only allow plants to survive fire but

also play a major role in predisposing plant communities to

recurrent fire (Mutch 1970). Fallen oak leaves are resistant

to decay and curl as they dry, providing a highly aerated fuel

bed which encourages frequent surface fires. In contrast,

leaves of fire-sensitive hardwoods like American beech,

yellow-poplar, and maples lie flat on the ground and decay

rapidly, preventing a flammable fuel bed from developing.

Unless fire-adapted plant communities tend to promote recurrent fire, they are likely to be replaced by non-flammable

communities (Bond and van Wilgen 1996).

MAJOR ECOLOGICAL DISTURBANCES AFTER

EUROPEAN SETTLEMENT

Europeans began settling the Central Hardwood Region

over 300 years ago. Since then, there have been many

types of anthropogenic disturbances, including logging,

fuelwood cutting, charcoal production, grazing, agriculture,

and development in the region (Buckner 1992, Hicks 1998,

Dey 2002). Timber exploitation began in the mid 1800s when

the steam engine allowed the entire region to be heavily

logged. Often harvests were followed by intense and severe

fires in the heavy logging debris, which created coppice

forests dominated by oaks (Clatterbuck 1991, Dey 2002).

These intense and often severe fires differed from fires of

previous millennia which, because of their frequency, were

generally low intensity burns in light fuels (Carroll and

others 2002).

In the early 1900s the chestnut blight (Cryphonectria parasitica) was introduced into New York’s Botanical Garden. By

the late 1930s, the blight had eliminated chestnut (Castanea

dentata) as an important component in eastern forests,

although its snags and downed logs continue to provide

habitat for wildlife to this day. American chestnut was

dominant in mixed stands throughout much of the Central

Hardwood Region occupying a broad swath from the

Appalachian Mountains to Arkansas and south into Georgia,

Alabama, and Mississippi. Chestnut was one of the most

economically, as well as ecologically, important species in

the region and was generally replaced by oak forest associations (Hicks 1998, Johnson and others 2002, McShea

and Healy 2002). However, on good quality sites in the

southern Appalachians, heavily logged chestnut-dominated

stands often succeeded to associations dominated by

mesophytic species (Vandermast and Van Lear 2002).
67

Catastrophic wildfires around the turn of the last century in

the Lake States and Rocky Mountains aroused the country’s

attention and concern. Cutover forests in the southeastern

Coastal Plain burned so frequently that forest regeneration

was often impossible. Slash fires following logging in the

Appalachian Mountains burned severely with devastating

offsite effects, such as erosion, sedimentation, and smoke

pollution. The public began to see fire as an enemy to be

suppressed at all costs (Pyne and others 1996, Johnson

and Hale 2002). In the early decades of the 20th century, a

policy of fire exclusion began that created ecosystems

different from those fire-dependent ecosystems that had

existed in previous millennia.

Over-zealous fire exclusion in ecosystems that had previously been fire dependent is a form of disturbance, i.e., a

state of disorder which changes the very nature of those

ecosystems. Exclusion of fire had many unexpected and

undesirable consequences, including endangerment of firedependent ecosystems and many species that live in them

(Landers and others 1995, Brennan and others 1998, Brose

and others 2002). On good quality sites in the southern

Appalachians, rhododendron (Rhododendron maximum)

has encroached on upland sites and now threatens the

diversity and productivity of cove forests (Vandermast and

Van Lear 2002). The spread of rhododendron is, in part,

related to the exclusion of fire in the mountains.

SUSTAINING OAK FORESTS WITH FIRE

Oak forests are in trouble. They are being replaced by other

species, especially on good quality sites because of natural

succession trends and because we have been unable to

consistently regenerate oak species on these sites following harvest. Fire has been excluded in many areas of the

Central Hardwood Region. In some areas, unnaturally high

deer herds prevent oak regeneration because oaks are

preferentially browsed by white-tailed deer (Healy 1997).

Insect pests, e.g., the red oak borer, and diseases, e.g., a

root rot caused by the fungus Armillaria, contribute to the

problem of oak decline in the Ozarks (Lawrence and others

2002). Other papers in the proceedings of this conference

cover these latter topics, so I will address the use of fire to

regenerate oak-dominated stands.

In the dense shade of mature mixed-hardwood stands, oak

seedlings and seedling sprouts do not develop into competitive stems either because of poor initial establishment of

oak seedlings or the slow juvenile growth of oak advance

regeneration if present (Loftis 1983, Abrams 1992, Lorimer

1993, Loftis and McGee 1993). Overstory removal by either

partial or complete cuttings often releases well-established

shade tolerant regeneration, such as red maple, or facilitates establishment of fast-growing shade intolerant seedlings like yellow-poplar. Oak species generally become a

minor component or altogether absent on good quality sites

as the new stand develops (McGee 1979, Abrams 1992,

Lorimer 1993). Numerous researchers think this pattern of

stand succession is a relatively recent phenomena, developing in the past 75 years or so, and is tied to the exclusion

of fire from eastern hardwood forests (Little 1974, Van Lear

and Johnson 1983, Crow 1988, Van Lear and Waldrop

1989, Abrams 1992, Lorimer 1993).

Repeated surface fires, especially in the growing season,

remove much of the mid- and understory strata in mature

mixed hardwood stands, reducing shading and providing

growing space for oak advance regeneration. Spring fires

are especially effective in killing these lower strata trees

(Barnes and Van Lear 1998), some of which die gradually

over several years. If oak advance regeneration is >1⁄2 inch

at ground line, it is likely to survive burning by sending up

new sprouts. Fire prepares a favorable seedbed for caching

of acorns by squirrels and jays (Darley-Hill and Johnson

1981, Galford and others 1989) and may reduce surface

soil moisture, which discourages establishment of mesophytic species (Barnes and Van Lear 1998). Frequent

burning may also control insect predators of acorns and

new seedlings (Galford and others 1989). All these fire

effects create environments that favor oak regeneration on

better quality sites.

Because forest ecosystems are complex and fire regimes

vary (season, intensity, severity, fire-return interval, etc.),

effects of fire in hardwood stands also vary. Single fires in

mixed hardwood stands have occasionally created oakdominated stands (Roth and Hepting 1943, Carvell and

Maxey 1969) but sometimes species composition in young

stands has been little altered by single fires (Johnson 1974,

McGee 1979, Augspurger and others 1987). Many earlier

studies, mine included, failed to adequately document fire

behavior characteristics and other features of the treatment

fires.

Season of burning and fire intensity are important considerations if oak regeneration is to be favored by fire. Season of

burning affects sprouting vigor. In the winter when root

reserves are highest, hardwoods have the greatest ability

to sprout following topkill. In the growing season, root

reserves are lower and sprouting vigor is less. Fire intensity

is critical because certain species, such as the oaks, can

survive higher intensity fires than their competitors

(Waldrop and others 1987, Brose and Van Lear 1998).

Fire is, of course, but one disturbance factor that affects

vegetation. Fire often works in combination with other

environmental forces, especially with wind or ice storms

that break up the overstory canopy. When the upper canopy

is reduced or removed by wind or ice, ecosystems are

predisposed to fire (Myers and Van Lear 1998). Openings

in the overstory increase insolation and drying of fuels, as

well as favor growth of fine fuels which help carry surface

fires.

UNDERSTORY BURNING TO ENCOURAGE OAK

REGENERATION

Van Lear and Watt (1993) described a theoretical silvicultural prescription to encourage oak regeneration in the

Piedmont of South Carolina by repeated understory burning

in mature mixed hardwood stands near the end of the rotation. Barnes and Van Lear (1998) continued this study and

found that oak rootstocks in the regeneration layer were

increased, root/shoot ratios of oaks were enhanced, and

competitive woody species decreased by repeated burning.

Understory and midstory density was reduced by about 50

percent. Although boles of small diameter (5 to 10 inches)

trees were often damaged by repeated burning, there was
68

little visible damage to boles of large overstory oaks from

these low intensity fires.

Understory burning must be continued at 2-3 year intervals

for perhaps 10 years or so before sufficient oaks of competitive size will be present in the advance regeneration. In addition, seed-producing individuals that are vigorous competitors

of oak, such as yellow-poplar, should be harvested at the

beginning of the burning program. The initial fire will stimulate germination of yellow-poplar seed stored in the duff but

subsequent fires will kill these small seedlings. Repeated

underburning is handicapped by the expense and risks of

multiple prescribed fires (Van Lear and Brose 2002). Nevertheless, if no oak advance regeneration exists in a stand

and prescribed fires are feasible, periodic understory burning provides a means to encourage establishment of oak

seedlings and seedling sprouts, while reducing competitors.

THE SHELTERWOOD-BURN METHOD TO

REGENERATE OAKS

A shelterwood-burn method was recently developed in the

Piedmont of Virginia to enhance the competitive position of

oak regeneration in such stands (Keyser and others 1996,

Brose and Van Lear 1998, Brose and others 1999a).

Although developed outside the Central Hardwood Region,

this method may be effective there and should be tested.

The initial shelterwood harvest removes roughly half of the

overstory basal area, leaving the best dominant and co-dominant oaks. In this first cut, all yellow-poplars are removed.

Following this partial harvest is a 3- to 5-year waiting period,

during which time the advance regeneration develops.

Generally the advance regeneration on good sites will be

dominated by species other than oaks. The third step occurs

after the waiting period when a relatively hot growing season

burn is run through the advance regeneration.

A growing season fire in early spring kills most of the yellowpoplar regeneration and sets back other competitors. Red

maple, for example, requires hotter fires to achieve desired

mortality rates (Brose and Van Lear 1998). Oak regeneration is favored because oak seedlings/sprouts, many of

which have grown to a ground-line diameter >0.5 inch following the initial shelterwood cut, survive the fire by vigorous

resprouting from their relatively large root systems.

Oak seedling/sprouts with large root/shoot ratios are capable

of vigorous sprouting and growth after the spring burn if

adequate light is available, which the fire provides (Brose

and Van Lear 1998). In our study of the shelterwood-burn

technique in Virginia’s Piedmont, density of free-to-grow

oaks exceeded 300 stems per acre with high intensity spring

fires, while yellow-poplar density was reduced up to 90 percent. Low-intensity winter burns provided little control of

yellow-poplar. Summer fires provided substantial numbers

of free-to-grow oaks in the medium-high intensity levels,

although many of the smaller oak seedlings were killed

because they were not of sufficient size to tolerate the heat.

Additional burns may be prescribed if oak regeneration is

not adequate after one burn. In many situations within the

Central Hardwood Region and beyond, decades of fire

exclusion have allowed oak competitors to become so

firmly established that oak regeneration may not be as plentiful as desired. Oak dominance of the advance regeneration

should increase with repetitive spring burning if such burns

are deemed necessary.

A shelterwood cut is the essential first step in this technique

because the shelterwood produces oak litter which creates

a flammable fine fuel bed capable of carrying the subsequent

fire. Clearcutting would produce a forest floor dominated by

less flammable foliage. Shading from the shelterwood also

prevents yellow-poplar regeneration from growing so large

during the interval before burning that it could not be killed

by fire (Hane 1999).

Although research on the shelterwood-burn technique was

done in the Piedmont where yellow-poplar is the major competitor, other species are serious competitors in the Central

Hardwood Region. Competitive species may exhibit either

exploitive or conservative ecological strategies, depending

upon the type of disturbance, to enhance their chances of

survival (Bormann and Likens 1979, Johnson and others

2002). Most oak species are relatively conservative and do

not allocate large portions of photosynthate to top-growth

following large-scale overstory disturbances, as do many of

their competitors.

Differences in developmental patterns probably explain why

oaks benefit from the shelterwood-burn method. Yellowpoplar, for example, usually regenerates prolifically following the initial shelterwood cut. Because its seed remains

viable for years in the duff and it is a pioneer species, it

grows densely and vigorously during the first few years

after disturbance and dominates the advance regeneration

pool. During this time yellow-poplar regeneration allocates

most of its energy to top-growth. Conversely, oak regeneration allocates much of its energy to root growth during the

interval between shelterwood cutting and burning (Hane

1999). Oaks are therefore able to sprout vigorously after

burning while yellow-poplar can not. Without burning, oak

regeneration could not compete with the fast growing

yellow-poplar seedlings.

During the 3 to 5 year waiting period, logging slash decomposes and become less hazardous to burn. Heavy logging

slash from the initial shelterwood cut resting against boles

of residual trees should be lopped or pulled away to prevent

bole damage during burning. Distances between residual

trees are generally great enough that directional felling can

prevent most tops from being in close proximity to boles of

residual trees (Brose and Van Lear 1998, Brose and others

1999a). Residual overstory trees can recover from the

shock of the initial cut during the waiting period before they

are stressed again by burning.

Management Options with the Shelterwood-Burn

Method

There are several management options available to landowners following completion of the shelterwood-burn technique. The first option would be to harvest the shelterwood

and release the oak-dominated regeneration. This method

of timber management is economically attractive because

the initial cut of the shelterwood method produces immediate income. A small portion of the profit is then used to

pay for the prescribed burn a few years later. Removal of
69

the shelterwood after burning is more profitable than the

initial cut because the best oaks were retained and probably

increased in value during the intervening years before final

harvest. However, the shelterwood-burn method can be

used to accomplish objectives other than timber management (Brose and others 1999).

The shelterwood-burn method can be used by wildlife

managers to sustain hard mast production and provide

palatable browse during the regeneration period. The

classic structure of the shelterwood can be maintained

while stockpiling oak regeneration with periodic burns

(Brose and others 1999b). Many upland game and nongame species utilize the mast, browse, and cover in a

regenerating shelterwood (Brose and others 1999b,

Lanham and others 2000).

The shelterwood-burn method could be used to restore rare

fire-maintained ecosystems (Brose and others 1999b).

Frequent (1-2 year intervals) growing season burns after

the initial shelterwood cut would favor herbaceous vegetation (Bond and van Wilgen 1996) and would gradually

reduce the density and size of woody regeneration and

create a hardwood woodland or savannah, two increasingly

rare habitats in the eastern United States after decades of

fire exclusion (Buckner 1983, Pyne 1982, Van Lear and

Waldrop 1989, Abrams 1992).

Would a regeneration technique developed in the Piedmont

of Virginia be successful in the Central Hardwood Region?

Some fire research suggests that it would. Repeated burning in oak-pine communities on xeric sites in the Cumberland

Plateau reduced regeneration of red maple and other nonoak species and promoted chestnut oak regeneration

(Arthur and others 1998). Hot fires in mountain laurel

thickets in the Northeastern United States opened overstory

canopies, i.e., a disturbance similar to a shelterwood

harvest, and allowed oak reproduction to grow past the

dense shrub layer (Moser and others 1996).

FELL AND BURN SITE PREPARATION

FOLLOWING COMMERCIAL CLEARCUTTING

Phillips and Abercrombie (1987) described a site preparation technique used in the Southern Appalachians following

commercial clearcutting (removal of merchantable stems

only) to develop pine-hardwood mixtures. The technique

consisted of spring felling of residual (unmerchantable)

stems after leaf-out, followed by an intense, but not severe,

summer broadcast burn. Pine species were then planted at

relatively wide spacings to maintain a pine component

among the sprouting hardwoods.

Spring felling of residuals followed by burning reduced

sprout growth of competing hardwood species more than

that of oak sprouts. The intense broadcast burns used in

this technique often cause new oak sprouts to originate from

below the mineral soil surface and result in well-anchored

stems. These results indicate that intense broadcast burns

following harvest should increase (or at least maintain) the

oak component in the new stand.

Care must be used in prescribing broadcast burns on poor

quality sites. If the burns consume the entire forest floor,

severe erosion and nutrient loss may result. These negative

consequences can generally be prevented if burning is

done when the lower layers of the forest floor and root mat

are damp. Such conditions often occur in the Southern

Appalachians a few days after a soaking rain (Phillips and

Abercrombie 1987).

CONCLUSIONS

Until the early decades of the past century, fire played a

major role in maintaining oak-dominated forests in the

eastern United States. As a result of fire exclusion and, in

some cases, other factors, such as deer browsing, oak

forests on good quality sites are being replaced by other

species. On poor quality sites oaks are maintaining

themselves.

Upland oaks are well adapted to regimes of frequent lowintensity surface fires. Because of these adaptations,

prescribed fire can be used to accomplish different management objectives, ranging from establishment of oak regeneration to restoration of open oak woodlands. However,

foresters have been reluctant to use prescribed fire in hardwood stands because of fear of damaging boles of highvalue trees.

Practical silvicultural prescriptions using fire for oak regeneration have been lacking. It is now understood that periodic

understory burning in mature mixed hardwood stands

creates environmental conditions, such as reduced low

shading and less competition, which favor oak regeneration. In addition, a shelterwood-burn method has recently

been developed for good quality sites which have proven

successful in improving oaks’ competitive position in the

advance regeneration pool in mixed hardwood stands. This

technique reduces the density and vigor of oaks’ competitors, especially when growing season burns of relatively

high intensity are used, and develops adequate numbers of

vigorous free-to-grow oak stems in the advance regeneration pool.

Forest managers will need to use prescribed fire or a fire

surrogate (herbicide) to sustain oaks on good quality sites.

The land-use history of the Central Hardwood Region and

the fire ecology of oaks tell us that fire and oak forests go

hand in hand. If we study our history (as recorded both by

man and by nature) carefully, we will understand that the

region has been a managed landscape for millennia and

fire was the primary management tool. It played a major

role in sustaining oak forests and will need to be used now

and in the future to favor oaks.

ACKNOWLEDGMENTS

The author thanks Dr. Peter Kapeluck, Dr. Geoff Wang,

and Ms. Elizabeth Blizzard for helpful suggestions during

preparation of this paper.

LITERATURE CITED

Abrams, M.D. 1992. Fire and the development of oak forests.

BioScience 42: 346-353.

Arthur, M.A.; Parately, R.D; Blankenship, B.A. 1998. Single and

repeated fires affect survival and regeneration of woody and

herbaceous species in an oak-pine forest. Journal of the Torrey

Botanical Club 125: 225-236.
70

Augspurger, M.K.; Van Lear, D.H.; Cox, S.K.; Phillips, D.R. 1987.

Regeneration of hardwood coppice following clearcutting with

and without prescribed fire. pp. 89-92. In: Proceedings of the

Fourth Biennial Southern Silvicultural Research Conference.

U.S. Department of Agriculture Forest Service General

Technical Report WO-3. Washington, DC.

Barnes, T.A.; Van Lear, D.H. 1998. Prescribed fire effects on

hardwood advance regeneration in mixed hardwood stands.

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72

INTRODUCTION

Although oaks dominate many forest ecosystems worldwide

(Barnes and others 1998), several aspects of oak ecology

remain poorly understood including oak regeneration and

masting (McShea and Healy 2001). Animals that eat and

disperse acorns, such as squirrels, mice, and jays may play

a pivotal role in oak forest dynamics (Jones and others 1998,

Ostfeld and others 1996), influencing regeneration both positively and negatively through their roles as seed dispersers

and predators. The ecology and evolution of oaks is likely

to be strongly dictated by the behavioral decisions of these

animals. Understanding oak forest ecosystems may therefore require multidisciplinary approaches that determine

how the behavioral ecology of animals affects oak forest

characteristics including levels and patterning of seedling

recruitment and plant physiological traits. Our research

attempts to examine such linkages by focusing on behavioral

responses to various acorn characteristics as a starting

point.

MECHANISMS OF OAK DISPERSAL

Acorn Characteristics and Oak Dispersal

The behavior of most acorn consumers and dispersers

follows directly from several key characteristics of the two

major subgenera of oaks in North America (Kaul 1985): the

white oak group (hereafter WO, subgenus Quercus, formerly

Leucobalanus) and the red oak group (RO, subgenus

Erythrobalanus). Acorns of WO species contain low levels

of both tannins (2 percent by mass) and lipids (5-10 percent)

and usually germinate in the autumn, during or shortly after

seed fall. Acorns of RO, in contrast, possess more tannins

(6-10 percent) and lipids (18-25 percent) and usually require

cold stratification to break dormancy, at least in temperate

regions. In the following sections we review several lines of

investigation that collectively demonstrate the influence of

these acorn characteristics on the feeding and caching

behavior of acorn consumers, and ultimately, the reciprocal

effect of such behavioral decisions on oak dispersal and

establishment.

Acorn Food Preferences

The differences in lipid and tannin levels between WO and

RO acorns have long been considered primary determinants of feeding preferences of many avian and mammalian

acorn consumers. Lipid levels represent the primary source

of digestible energy in acorn cotyledon and are thus the

reason that acorns are so highly sought for food by >150

species of wildlife (Van Dersel 1940). However tannins, a

group of water soluble phenolic compounds common in

acorns, readily bind to salivary and digestive enzymes

reducing both their palatability and their digestibility (Robbins

and others 1987, Chung-MacCoubrey and others 1997).

Thus when selecting between acorn types for food, most

species are faced with a trade-off between RO acorns that

are high in energy but unpalatable and others (WO) that

contain significantly less energy but are far more palatable

and digestible (Smith and Follmer 1972).

Attempts to determine whether mammals prefer RO or WO

acorns have produced varying results depending on study

conditions (Lewis 1980, Smith and Follmer 1972). This

controversy was largely resolved in 1986 by Smallwood

and Peters who examined the feeding response of eastern

gray squirrels to artificial acorns made from ground cotyledon

of Q. alba acorns to which varying amounts of tannin and

lipid were added. By presenting free-ranging gray squirrels

with these artificial acorns, they found that gray squirrels

selected acorns low in tannin levels in autumn when energy

OAK DISPERSAL SYNDROMES: DO RED AND WHITE OAKS

EXHIBIT DIFFERENT DISPERSAL STRATEGIES?

Michael A. Steele, Peter Smallwood, William B. Terzaghi,

John E. Carlson, Thomas Contreras, and Amy McEuen1

1 Associate Professor of Biology, Department of Biology, Wilkes University, Wilkes-Barre, PA; Associate Professor of Biology, Department of

Biology, University of Richmond, Richmond, VA; Associate Professor of Biology, Department of Biology, Wilkes University, Wilkes-Barre, PA;

Associate Professor of Molecular Genetics (Director, Schatz Center for Tree Molecular Genetics), School of Forest Resources and the Huck

Institute for Life Sciences, Pennsylvania State University, University Park, PA; Postdoctoral Fellow, Department of Wildlife Ecology and

Conservation, University of Florida, Gainesville, FL; and Postdoctoral Research Associate, Department of Biology, Wilkes University, WilkesBarre, PA, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—We provide an overview of the ecological and evolutionary interactions between oaks and several of their

dispersal agents, and review a series of studies that demonstrate how various acorn characteristics affect feeding and

caching decisions of these animals, which in turn may influence oak dispersal and establishment. We demonstrate that

acorns of red oak species show a marked dispersal advantage over those of various white oak species. From this, we

predict that red oaks are likely to establish in a wider range of micro-environments and at greater distances from maternal

sources, whereas white oaks should be limited to establishment closer to maternal sources. This in turn should influence

the spatial pattern of oak recruitment and seedling physiological traits. We discuss current efforts to test this Differential

Dispersal Hypothesis (DDH) and its implications for various aspects of oak ecology including masting, seedling physiology, and regeneration.
73

requirements were low and food was relatively abundant. In

contrast, in the winter when energy requirements were high,

squirrels selected artificial acorns with higher lipid levels

even when they contained higher amounts of tannin

(Smallwood and Peters 1986).

Early Germination in WOs and Embryo Excision

The behavior of early germination in WO acorns presents

a second problem for acorn consumers. Rapid autumn

germination in many WOs, occurring in some species while

acorns are still attached to the tree (Steele pers. obs.),

involves the rapid transfer of energy into a taproot that is

high in cellulose and indigestible for most granivores (Fox

1974). Early germination in WO species likely represents

an adaptation to prevent seed predation by granivorous

mammals and birds (Barnett 1977, Steele and Smallwood

2001), and perhaps larval insect predators (e.g., Curculio)

that begin feeding on acorns before they mature. For

mammals, birds, and even some insects early germination

greatly limits the availability of WO acorns as food in the

autumn. Early germination means that if not eaten soon

after seed fall, much of the energy of the WO crop will no

longer be available to seed consumers. Moreover, if whole

intact WO acorns are stored, it is likely that such energy

stores would be lost as these acorns continue to produce

taproots during periods of warmer weather.

At least one group of mammals—the tree squirrels (Sciurus)

—appear to have overcome this problem with the behavior

of embryo excision (Fox 1974, 1982; Pigott and others

1991). Eastern gray squirrels, for example, are known to

carefully remove the radicle and excise the embryo from

the apical end of WO acorns with their incisors prior to

caching these acorns (Fox 1982, Pigott and others 1991).

Recently we reported that this behavior is quite common,

and that WO acorns with excised embryos remain in tact in

the scatter hoards of squirrels for up to six months (Steele

and others 2001b). Several observations also suggest that

this behavior may be an adaptation unique to the genus

Sciurus. We have observed the behavior in at least two

other species of tree squirrels (S. niger in the midwestern

U.S. and S. aueregaster in central Mexico), but have failed

to observe any such behavior in at least four other species

of small mammals, all of whom otherwise show similar feeding and caching responses to acorns (see below). Recently

we presented acorns to naïve captive raised eastern gray

squirrels that possessed no previous experience with acorns.

The animals cached dormant RO acorns over those of WO,

removed the radicles of germinating WO acorns, and on

occasion excised or attempted to excise the embryos of

WO acorns (Steele and others, unpublished data). We

argue that this behavior is likely unique to the tree squirrels

and that there is a strong innate basis for the behavior.

Caching Responses and Acorn Perishability

Both the behavior of embryo excision and the selective

consumption of WO acorns in autumn suggest that some

acorn consumers may be sensitive to acorn perishability

due to germination. In fact, Smallwood and Peters (1986),

in their analysis of acorn preferences of gray squirrels,

predicted that squirrels might selectively cache RO acorns

over those of WO, and that they may use tannin as a cue to

identify less perishable RO acorns. Over the last decade,

we have fully verified this first prediction with two series of

experiments in which we have presented small mammals

with RO and WO acorns. In the first, we directly observed

free-ranging gray squirrels and recorded their feeding and

caching decisions. The second experiment, repeated many

times under a variety of conditions, involved selective

provisioning of granivorous mammals with metal-tagged

acorns (e.g., Steele and others 2001b). Following their

dispersal, metal detectors were used to relocate the tags

and determine those acorns cached and those eaten, as

evidenced by discarded tags. In all such experiments we

found that small mammals selectively dispersed and cached

RO acorns and consistently ate those of WO species. These

experiments, coupled with several others conducted on

captive mammals (e.g., southern flying squirrels, whitefooted mice) lead us to conclude that selective dispersal

and caching of RO is a behavior common to most scatterhoarding mammals in Eastern deciduous forests. (Although

bluejays (Cyanocitta cristata) are also important dispersal

agents of oak, especially over long distances (>1 km), most

studies conclude that they selectively disperse primarily RO

species with smaller acorns (Darley-Hill and Johnson 1981,

Johnson and Webb 1989, but see Bossema 1979, Monsandl

and Kleinert 1988 for dispersal by European jays)).

In another series of experiments we sought to determine

specific cues that small mammals use to determine which

acorns to eat and which to disperse and cache. Hadj-Chikh

and others (1996) addressed this question by presenting

free ranging gray squirrels with pairs of acorns that varied

with respect to several characteristics (i.e., size, perishability

due to germination schedules, fat and tannin levels). They

produced overwhelming support that the animals were

responding to acorn perishability over any other factor,

including tannins. Likewise, in a related experiment, Steele

and others (1996) found that tree squirrels selectively cache

sound acorns over those infested with insect larvae, which

the animals instead consume along with the larvae. Together

these results indicate that tree squirrels, and perhaps other

acorn consumers, rely on acorn perishability to make caching

decisions.

More recently we also have found that tree squirrels can

distinguish between dormant and non-dormant RO acorns

even when the non-dormant acorns exhibit no physical signs

of germination (Smallwood and others 2001, Steele and

others 2001a). Moreover, by manipulating acorn chemistry

and creating artificial acorns with one type of pericarp (WO

or RO) that contain ground RO or WO cotyledon (with varying

concentrations of fat and tannin), Steele and others (2001a)

showed that squirrels only cache those artificial acorns

constructed of RO pericarps, regardless of their contents.

However, when these RO pericarps are first soaked in

acetone (to potentially control for chemical cues in the pericarp), gray squirrels consistently consume these acorns.

These results point to a chemical cue (or the absence of

one) in the pericarp that may be used by the animals to

identify dormant, non-perishable seeds (Steele and others

2001a). Future efforts are directed at comparing the chemical profiles of dormant and non-dormant acorns and determining whether squirrels detect a dormancy cue or simply

respond to damaged packaging (i.e., the pericarp).
74

Partial Consumption of Acorns

In addition to selectively caching RO acorns, small mammals

and several other acorn consumers, selectively consume

portions of individual acorns in a manner that may also

influence dispersal and establishment of the oaks. Steele

and others (1993) found that several vertebrates as well as

weevil larvae (genus Curculio) selectively feed on the basal

portion (proximal end) of several species of RO acorns,

especially when acorns and other food are abundant (Steele

and others 1993). Each vertebrate species uses a markedly

different technique for opening acorns, but each frequently

consumes only 10-40 percent of the basal portion of the

cotyledon.

Because the acorn embryo (< 1 percent of the biomass of

the acorn) is located in the extreme apical end of the fruit,

many of these partially eaten acorns can still germinate. In

greenhouse experiments, for example, germination rates

are as high or higher for partially eaten acorns as they are

for intact seeds (Steele and others 1993). In behavioral

experiments, Steele and others (1998) also found that gray

squirrels often dispersed and cached the potentially viable

apical fragments. And, although germination and establishment rates of partially eaten acorns in the field are substantially lower than those of whole acorns, these observations

suggest that the ability to survive partial predation may

represent a means by which several RO species sometimes

escape seed predation. We suggest that in the life of an

oak (150 or more years) infrequent establishment as a

result of partial acorn consumption need only occur rarely

for this to represent a successful reproductive strategy.

Tests of alternative hypotheses to explain the underlying

causes of the behavior point to a suite of chemical and

physical traits that may collectively promote partial consumption and subsequent survival of RO seeds. Steele and

others (1993) found that tannin levels (as measured by

protein binding capacity) are significantly higher in the

apical half of the acorns of two RO species, where the

embryo is located. More recently, several of us also found

that both lipid levels and Na levels are significantly higher

in the basal half than the apical half of three additional

species of acorns (Steele and others, unpublished data).

Consequently, the top of the acorn may not only be more

palatable and digestible because of lower tannin levels but

may also contain more energy (lipid), and an important

nutrient (Na), often limiting for herbivorous mammals such

as tree squirrels (Steele and Koprowski, 2001 and references therein). In other experiments, Steele and others

(1998) have shown that although partial acorn consumption

is not influenced by the thickness or presence of the pericarp, the shape of the acorn can affect the behavior. When

acorns are shelled and the cotyledon is carved so the basal

and apical ends of the acorn are reversed, tree squirrels

begin eating from the true apical end of the seed (which

looks like the basal end). Thus it appears several physical

and chemical characteristics may act synergistically to

promote partial consumption of the basal half of acorns and

subsequent survival of these damaged fruits.

Table 1—Overview of characteristics of RO and WO acorns, behavioral responses to these characteristics by acorn

consumers, and the influence of these responses on the oaks

Acorn characteristics Acorn type Response and influence on oaks References

Low tannin, low fat WO Selective consumption of WO in autumn Smallwood and Peters 1986

High tannin, high fat RO Selective consumption of RO in winter Smallwood and Peters 1986

Selective caching of RO for winter Smallwood and Peters 1986

Early germination WO Consumption of acorns Hadj-Chikh and others 1996

Steele and others 2001a

Embryo excision by tree squirrels Fox 1982, Pigott and others 1996

Steele and others 2001a

Delayed germination RO Selective scatter hoarding of RO Hadj-Chikh and others 1996

Potential for far greater dispersal in RO Smallwood and others 1998

Insect Infestation RO and WO Selective consumption of infested acorns Steele and others 1996

Selective scatter hoarding of RO only

Chemical gradients RO and WO Partial consumption of RO only and Steele and others 1993

in acorns subsequent survival of damaged seeds Steele and others 1998

Acorn shape RO Partial consumption of RO Steele and others 1998

Acorn size RO Selective long distance dispersal of

Smaller-seeded RO by jays Darley-Hill and Johnson 1981

Selective scatter hoarding of Steele and others unpub. data

Larger-seeded RO by tree squirrels
75

SYNTHESIS, IMPLICATIONS, AND FUTURE

DIRECTIONS

Acorn Fates and The Differential Dispersal

Hypothesis (DDH)

The studies reviewed above collectively point to a marked

contrast in dispersal strategies of the two primary groups of

oaks in North America. Table 1 summarizes the major

behavioral responses of avian and mammalian agents of

oak dispersal to the different characteristics of RO and WO

acorns. Figure 1 is a seed fate diagram that integrates

these various responses.

The obvious conclusion to follow from these summaries is

that acorns of RO have a significant dispersal advantage.

RO acorns are dispersed greater distances from their

sources, cached more often in a wide variety of environments, and even show the ability, under some circumstances,

to escape partial predation. Acorns of WO, in contrast,

should show short dispersal distances and may be in fact

adapted for rapid germination near or under parent trees.

Although most of our studies have been conducted in

eastern deciduous forests, we predict that because of the

consistent differences between RO and WO acorns across

North America, this phenomenon of differential dispersal is

likely to occur throughout temperate forests of North

America. If in fact RO and WO species exhibit contrasting

dispersal syndromes, several important implications may

follow.

Differential Dispersal and the Spatial Arrangement

of Oaks

One likely outcome of these contrasting dispersal strategies

is a significant difference in the spacing of RO and WO seedlings (Smallwood and others 1998, Steele and Smallwood

2001). RO seedlings are likely to establish at greater

distances from parents and thus become more widely

spaced; WO seedlings should be clumped near or under

parent trees. In an initial test of this hypothesis, Smallwood

and others (1998) measured the distribution of seedlings

and adult trees of several oak species in the same forest

plot to construct best-fit, putative seedling shadows using

the computer models of Ribbens and others (1994). The

two WO species studied (Q. alba and Q. prinus) had short

truncated seedling distributions and extensive clumping of

seedlings within a few meters of the parent. In contrast, the

two RO species (Q. rubra and Q. velutina) showed no

clumping and seedling shadows of RO extended much

farther than those of WO.

Although results of Smallwood and others (1998) support

the DDH, they demonstrate the expected pattern of seedling distribution for only one site. We are currently examining

seedling distributions for six additional oak forests throughout eastern North America to determine the consistency of

these findings. In addition Smallwood’s results are derived

from computer models that generate expected distributions

in relation to putative, not definitive, parents. To more definitively determine seedling-parent distances, we are currently

conducting parentage analysis of seedlings (via microsatelFigure 1—Acorn fate diagram for species of red oak (open rectangles) and white oak (shaded rectangles). The width of arrows is proportional

to the probability of the corresponding event.

 Seed fall

Dispersal

Larder 

hoarded

Scatter

hoarded

Partial 

consumption

Recovered 

and scatter

hoarded

Failure to

recover Pilfered

 RO WO

Recovered 

and eaten

Eaten

 Seed fall

Germination and 

establishment

Eaten

 (heavy 

consumption)

Germination and 

establishment

Scatter

hoarded

Larder

hoarded

Dispersal

Pilfered Failure to

recover

Recovered

and scatter

hoarded

Germination and 

establishment

Recovered 

and eaten

Recovered

and eaten
76

lite DNA fingerprinting) in several managed and old-growth

stands of oak in the central and eastern U.S. Although the

final outcome of these genetic analyses is not yet available

one of two general conclusions is likely.

If the molecular analyses ultimately show greater dispersal

of RO seedlings than WO as predicted, these contrasting

dispersion patterns are likely to result in two sets of alternative cascading effects for the two subgenera of oaks.

Assuming the microenvironment beneath parent trees is

both more shaded and exhibits less variability in microsite

conditions, white oak seedlings would then be expected to

be more shade tolerant, less capable of colonizing new

micro-environments, and more competitive than RO seedlings (reviewed by Steele and Smallwood 2001). Currently

we are testing several of these predictions.

If, on the other hand, the molecular results fail to support

the hypothesis by showing white oak seedlings to be widely

dispersed, as preliminary results suggest, the most obvious

question to follow will be how are white oaks dispersed?

Perhaps seedlings exhibit different distributions than seeds

because of strong differential survival of rarely dispersed

seeds. White oaks may therefore be more dependent than

ROs on such rare events, the occasional acorn that is

carried and dropped, or the exceedingly rare occasions

when whole WO acorns are scatter-hoarded and subsequently forgotten. Perhaps in the life of an oak such rare

events are, simply, the rule.

Differential Dispersal and Masting in Oaks

A second implication to follow from our behavioral studies,

regardless of the molecular findings, concerns the masting

patterns in RO and WO species. Masting is the synchronized, episodic production of seeds by one or more tree

species in one year, followed by widespread crop failure in

others. Masting is common in oaks and considered by many

as a genetically influenced factor affecting their dispersal

and establishment (Crawley and Long 1995, Koenig and

Knops 2001, Sork and others 1993). In a recent review

Koenig and Knops (2001) concluded that masting in oaks is

an adaptive response that is best explained by the predator

satiation hypothesis. This hypothesis argues that mast failures serve to decrease seed predators, while good crop

years result in satiation of seed predators and seedling

establishment.

Koenig and Knops (2001) also note, however, that the most

significant evidence against the predator satiation hypothesis for oaks “...is the lack of synchronization in masting

behavior among species within a community, in particular

between species requiring different numbers of years to

mature acorns” [e.g., RO and WO species]. We argue that

such asynchrony between RO and WO species (especially

within a community) is expected because of differential treatment of WO and RO acorns by acorn consumers. Although

ROs clearly would benefit from synchronized masting with

WOs, since WO acorns could then satiate predators while

RO acorns were dispersed, WOs may have no advantage in

masting with ROs and may potentially be at a disadvantage

of synchronizing its mast with species that are preferred for

caching. This could potentially explain some asynchrony in

acorn masting as WOs evolve to “escape” masting with RO.

We have tested this prediction by simulating RO and WO

acorn abundance and found that significant scatter hoarding

of WO acorns only occurs when these acorns are abundant

and ROs are not (Steele and others, unpublished data).

Because of the extreme susceptibility of WO acorns to predation, we also expect seed fall patterns within a season to

differ between the two oak groups, with WO species showing rapid seed fall and RO species extending their release

of acorns over longer periods. We are currently testing

these hypotheses by conducting a meta-analysis of acorn

production studies.

In conclusion, seed consumers have the potential to affect

such wide-reaching factors as plant spatial patterns, physiological traits, and degree and timing of acorn masting. Understanding the degree to which these behaviors influence oak

dynamics may prove critical for effectively managing oak

ecosystems in the face of such threats as forest fragmentation and climate change.

ACKNOWLEDGMENTS

We thank Wilkes University, The University of Richmond, and

The School of Forest Resources, PSU for support during

preparation of this manuscript. Financial support of our

research is provided by the National Science Foundation

(DBI-9978807).

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78

INTRODUCTION

Various oak (Quercus) and hickory (Carya) species have

been the dominant components of the central hardwood

forest for the past several millennia. Although the last glacial

advance (Wisconsin Stage) did not extend much beyond

Wisconsin and Michigan, it had a major influence on forest

vegetation. Delcourt and Delcourt (1991) and Franklin (1994)

have summarized the research on vegetation change since

glacier degradation. Analysis of pollen profiles from bogs

and information from geology, archeology, and anthropology

indicate that the central states forest went through a progression of vegetation types. When the glacier was still advancing

about 16,500 years BP, spruce (Picea) and pine (Pinus)

dominated much of Wisconsin, Illinois, Indiana, and Ohio.

From about 13,500 to 11,500 years BP, the forest was a

mixture of hemlock (Tsuga), pine, spruce, fir (Abies), oak,

birch (Betula), elm (Ulmus), ash (Fraxinus), maple (Acer),

and beech (Fagus). By 10,000 years BP, mixed hardwoods

were dominant within the forest because of the effects of the

northward movement of the warm humid tropical airmass.

As the glacier melted between 10-11,000 and 9,000 years

BP, a variety of oak species became the dominant forest

species. The climate continued to warm and become drier

between about 8,700 and 5,000 years BP. This period is

known as the Hypsithermal. Concurrent with the warming of

the climate was an increase in the occurrence of fire that

probably was accentuated by the increased movement and

activity of the Early American peoples. During this period,

prairie expanded eastward well into Ohio and possibly farther

east, and oak and hickory probably were the dominant

woodland species. Transeau (1935) noted the existence of

the prairie peninsula during the late 1700s and early 1800s.

The present plant communities of the Tennessee Barrens

are considered by Anderson and Bowles (2000) to be an

extension of tall grass prairie. During the Hypsithermal,

mixed oak and mesophytic hardwoods were restricted to

coves and ravines.

After 5,000 years BP, precipitation levels increased so that

oak expanded on uplands while mesophytic hardwoods,

such as sugar maple (Acer saccharum Marsh.), red maple

(Acer rubrum L.), American Beech (Fagus grandifolia

Ehrh.), basswood (Tilia americana L.), and ash (Fraxinus),

replaced oak in ravines and stream terraces. At that time,

mesophytic species may also have been important on

upland sites.

Later, succession to mesophytic species on upland slopes

and hills was slowed due to the use of fire and clearing of

land by the Woodland (2,500-1,000 years BP), Mississippian

(1,000-500 years BP), and Native American Indians (<500

years BP). The Woodland culture depended largely on

gathering of nuts, berries, and other wild plant foods such

as roots. Southern pines (shortleaf, Pinus echinata Miller;

Virginia, Pinus virginiana Miller) appeared in the forest

during this period probably due to increased levels of fire.

The Mississippian culture introduced agriculture into the

central states; growing of foods such as corn, beans, squash,

and pumpkin supplemented fishing and gathering of nuts

and berries. Permanent villages often were constructed

along major rivers and tributaries. Slash and burn agriculture

and sedentary farming were common practices (Franklin

1994). The Native American Indians continued these practices and used fire to clear forest around their camps. Their

reasons for use of fire included clearing of brush for

improved hunting with bow and arrow, and better visibility

for protection against enemy sneak attacks.

At the time of the original land survey in 1806-10, oak and

hickory dominated the upland communities of most of

southern Illinois including many north slopes and stream

terraces (Fralish and others 1991, Fralish and others 2002,

Sauer 2002). Forest ecologists universally agree that an

active presettlement fire cycle (before ca. 1810) maintained

the oak-hickory ecosystem. Abrams (1992) makes a strong

case for the relationship between fire and development of

oak dominated forests. The writings of early travelers

reported relatively open woods and the frequency of fire.

THE KEYSTONE ROLE OF OAK AND HICKORY IN

THE CENTRAL HARDWOOD FOREST

James S. Fralish1

1 Emeritus, Department of Forestry, Southern Illinois University, Carbondale, IL 62901-4411.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Communities of the central hardwood forest have been dominated primarily by oak and hickory for the past

5000 years. Over this time period, they have become keystone species within the ecosystem and are of major importance

in maintaining biodiversity. Not only do the large number of oak and hickory species by themselves contribute to community richness but they are known to provide food and support for a substantial number of wildlife species. Moreover, the

structure created by dominance of oak and hickory in the forest community provides an environment for a highly diverse

herbaceous understory. Data from oak-hickory stands with a maple-beech understory of saplings and small trees show a

90 percent drop in photosynthetically active radiation (PAR) at ground level accompanied by a 35 percent increase in litter

weight compared to stands without an understory. The result is over a 90 percent drop in species richness and cover. This

drastic loss of biodiversity, foliage, and fruit has serious implications for insect and bird populations and also suggests a

potential for increased soil erosion and loss of nutrients. Extensive research into the loss of biodiversity is advised.
79

RECENT DISTURBANCE REGIMES AND OAK

HICKORY

A new disturbance regime in the Central Hardwood Forest

Region began at the time of settlement around 1810 to

1820. Fralish (1997) reported that the level of forest disturbance was reduced with settlement, and in some of the more

eastern populated areas, this reduction probably was necessary to protect farms, towns, and other property including

woodlots. However, during the period of European settlement and development in southern Illinois (1810-1930) and

probably surrounding areas and states, the general level of

disturbance was high as large land areas were cleared for

agricultural crops. Fire used to clear land escaped in the

woods so that the level of disturbance remained about that

of presettlement time or was greater in some areas (e.g.,

Illinois Ozark Hills) as landowners and farmers continued

to disturb the forest by various activities associated with

settlement including heavy timber harvesting for buildings,

railroad ties, and other construction, and grazing by free

roaming cattle and pigs. In 1920, Miller reported that from

the top of Bald Knob (a high point in the Illinois Ozark Hills),

he could not see the Mississippi River because of smoke

from six different wild fires. This level of disturbance maintained the oak-hickory component of the present forest at

about that of the presettlement forest. Based on an analysis

of presettlement witness tree records of the Land Office

survey, McArdle (1991), and more recently, Fralish and

others (2002) found that the amount of oak, hickory, and

yellow-poplar in the present (Illinois Ozark Hills) forest was

somewhat greater than in presettlement time suggesting a

slightly greater level of disturbance during the period the

present mature forest community was established as

seedlings.

This disturbance regime abruptly ended and a new one

began when fire protection laws were instituted in the late

1920s, and further, after large land areas were purchased

for state and federal forests and parks developed in the

1930s and later. Grazing on private property and timber

harvesting on national and state forest land continued but

the beneficial effect of fire was absent. Since the passage

of fire control laws and the cessation of wild fire, and the

general protection of the ecosystem beginning in the late

1920s and early 1930s, oak and hickory trees have continued to grow while few seedlings reached sapling size

before dying. Because large forested areas have remained

undisturbed for the past 70+ years, scattered stems of fireintolerant but shade tolerant species such as sugar maple,

red maple, and American beech have grown to tree size

and a become major seed source. Now forest communities

are rapidly converting from mid-successional oak and

hickory species to shade tolerant climax mesophytes with a

concurrent loss of biodiversity.

There is little doubt that near total absence of fire has

permitted the development of this classical secondary

successional process, particularly on mesic sites in large

areas of the central hardwood forest (Interior Low Plateaus,

Central Lowlands, and Ozark Plateaus). Replacement of

high quality stands of oak and hickory by mesophytes has

been reported for stands in Pennsylvania (Downs and

Abrams 1991), Ohio (McCarthy and Wistendahl 1988,

McCarthy and others 1987, Cho and Boerner 1991,1995),

Indiana (Myers and others 1983, Parker and others 1985,

Parker and Sherwood 1986, Ward and Parker 1989),

Kentucky and Tennessee (Fralish and Crooks 1988, 1989,

Kettler 1990, Fralish and others 1993, Franklin and others

1993), Michigan (Host and others 1987, Hammett and

Barnes 1989), Wisconsin (Menges and Loucks 1984),

Missouri (Kucera and McDermott 1955, Anonymous 1983,

Nigh and others 1985a, 1985b, Pallardy and others 1991),

Iowa (Countryman and Miller 1989) and as far west as

Kansas (Abrams 1986). In the center of the central hardwood region, a similar pattern has been reported for forest

communities in northern Illinois (Wilhelm 1991), central

Illinois (Boggess 1964, Boggess and Bailey 1964, McClain

and Ebinger 1968, Anderson and Adams 1978, Adams and

Anderson 1980, Ebinger and Newman 1984, Lehnen and

Ebinger 1984, Ebinger 1986, Landes and Ebinger 1991,

Edgington 1991), and in southern Illinois (Harty 1978,

Schlesinger 1976, 1989, Fralish 1988, 1997, Fralish and

others 1991, McArdle 1991, Shotola and others 1992,

Schildt 1995, Helmig 1996). For the whole of Illinois,

Iverson (1989) reported a 4,119 percent increase in the

maple-beech forest type from 24,800 acres to 1,046,400

acres between 1962 and 1985.

Given time, the dense shade created by a closed canopy of

shade tolerant mesophytic species will eliminate the oak

and hickory by preventing seeding establishment and

survival. Because oak and hickory have dominated the

forest for thousands of years, the life cycle and ecological

requirements of numerous other plant and animal species

have become entwined with the existence of oak and

hickory. Thus, oak, and to a lesser extent hickory, have

become keystone species.

THE KEYSTONE SPECIES CONCEPT

A keystone species has been defined as a species (or group

of species) that should be conserved because it makes an

unusually strong contribution to community structure, maintains critical or key ecosystem processes, or has a disproportionately large effect on other species (Meffe and Carroll

1991) or on the persistence of other species in the community. A “key process” is a critical ecosystem function that

controls ecosystem characteristics (Meffe and Carroll 1991).

A keystone species may be of several types, such as a

major producer, predator, prey, or mobile link species (e.g.,

pollinators). Either a single species or a group of species

may function as a keystone species. It follows, therefore,

that keystone species management is management directed

toward ecologically important species as a surrogate for

managing for all species in a [forest community or] ecosystem (Meffe and Carroll 1991). One function of a keystone

species may be to support other forest species and maintain high biodiversity (species richness). High species diversity may promote stability at the ecosystem level because

species usually vary in their tolerance to natural perturbation (e.g., fire) and anthropogenic stressors. Stressors may

be single or multiple. As the number of independent stressors

with different modes of action increases, there will be fewer

resistant species with the potential to survive or increase

under the influence of an altered environment (Breitburg

and others 1998, Bond 1994). An altered environment

includes the absence of fire in the fire-dependent oakhickory forest.
80

However, depending on the type of ecosystem, it may be

difficult to identify a keystone species in some ecosystems.

In the central hardwood forest, there is sufficient evidence

to classify oak and hickory species as keystones. A substantial number of wildlife species are not the only biota

dependent on these species, but as will be shown later.

Although large in number, oak and hickory species are

relatively similar in their tolerance to natural and anthropogenic stressors, and thus, as keystone species, the

absence of fire combined with invasion by mesophytic

species become major stressors for oak-hickory forest both

as a community and ecosystem. These two stressors (no

fire, succession to mesophytes) are combining to eliminate

the once strongly dominant keystone oak and hickory.

KEYSTONE CHARACTERISTICS OF OAK AND

HICKORY

In the central hardwood forest, it is apparent that oak and

hickory, when viewed in the light of changes that are occurring with invasion of maple, beech and other mesophytes,

create a community structure and environment that maintains critical ecosystem processes, and has a disproportionately large effect on other species, particular on the

persistence of other species in the community. It is well

known that the production of mast (nuts from trees) is

important to a substantial number of wildlife species, but for

other living organisms, such as the highly diverse herb

layer and oak and hickory seedlings and saplings, crown

density and canopy structure are important.

Keystone species functions may deal with factors limiting

production such as water, light, and nutrients (Vogt and

others 1997). In the absence of a canopy created by an

invasion by sugar maple, American beech, and other mesophytes, the structure of a mature or nearly mature (age

>115 years) oak-hickory forest is typically even-aged with

a single high, relatively thin overstory canopy easily penetrated by photosynthetically active radiation (PAR). However, level of PAR (photosynthetic photon flux density)

varies with overstory structural characteristics that in turn

vary with soil and topographic conditions. Photosynthetic

photon flux density decreases rapidly with increasing depth

of tree crowns (Kozlowski and Pallardy 1997).

On xeric sites (south, southwest, and west rocky slopes),

post oak (Quercus stellata Wang.), blackjack oak (Quercus

marilandica Muench.), southern red (Quercus falcata

Michx.), scarlet oak (Quercus coccinea Muench.), white oak

(Quercus alba L.), and black oak (Quercus velutina Lam.)

trees are generally deformed as well as short (maximum

height about 45 feet), have large openings in the individual

crowns, and are widely spaced so that canopy closure may

be only 35-50 percent in these woodlands or barrens

(Fralish and others 1999); basal area (25-40 sq.ft. per A.;

Fralish 1994), site index (35-50), and total biomass are

extremely low. The overall result is that in a xeric post oakblackjack oak forest, PAR at ground level is, on average, 15

to 20 percent (about 200-250 umol/m2/sec.) of full sunlight

(about 1200 umol/m2/sec.) with many near full-sun flecks

scattered across the forest floor. These sunflecks are

essential for survival of many understory plants (Chazdon

and Pearcy 1991). In the midcanopy, scattered

arborescents such as sparkleberry (Vaccinium arboreum

Marsh.) and Juneberry [Amelanchier arborea (Michx. f.)

Fern.] usually are present but typically there is no oak and

hickory sapling stratum; but seedlings may be numerous

and a herbaceous layer usually is present (Jones 1974,

O’Dell 1978).

On xeric-mesic sites (south, southwest, and west slopes

with relatively deep soil), the trees are tall (70-80 feet), relatively straight with more well developed crowns (higher leaf

density), and have a higher site index (50-65) and basal

area (75-120 sq.ft. per A.; Fralish 1994) compared to oak on

xeric sites. The stands on these sites may be dominated by

either pure white oak, white oak with several species of the

“black oak” group (black, scarlet, southern red), or by species

of only the black oak group. There generally is more light

penetration in stands dominated by black oak. Because

species of the black oak group are more shade intolerant

than white oak, they tend to have thinner crown density and

a greater distance between crowns to let more light through

to the lower leaves. “Black oak” species not only have fewer

leaves but leaves in the upper portion of the crowns have

large sinuses to permit passage of light. The lower leaves

tend to have more green leaf area to capture light with the

extreme condition found in the large misshapen black oak

seeding leaves that essentially have no sinuses. The sunflecks in these stands are smaller but may comprise up to

80 percent of total light reaching the forest floor (Chazdon

and Pearcy 1991). The PAR in black oak stands is about

10-15 percent of full sunlight (Fralish 1997). Scattered arborescents such as Juneberry [Amelanchier arborea (Michx. f.)

Fern.] and flowering dogwood (Cornus florida L.) may be

present but typically there is no oak and hickory sapling

stratum; seedlings may be numerous and a herbaceous

layer usually is present (Jones 1976, O’Dell 1978).

Form and crown density are further developed in trees on

mesic sites (north, northeast and east slopes and stream

terraces). These stands generally are dominated by nearly

pure white oak or northern red oak (Quercus rubra L.);

black oak seldom is more than a scattered tree. At maturity,

the trees are tall (100-120 feet) and stands have a high site

index 96-75) and basal area (130-160 sq. ft. per A.; Fralish

1994). White and northern red oak are shade intermediate

and slightly more shade tolerant that other upland oak

species. White oak crowns usually are more dense than

those of black oak although the crowns seldom touch or

overlap in the forest overstory canopy. However, even in a

forest of white or northern red oak, crown depth seldom

exceeds 1/2 of total tree height. Here PAR probably is 5 to

10 percent of full sun; sunflecks are smaller and more

scattered. Flowering dogwood is the most common midcanopy arborescent and usually is scattered but pawpaw

(Asimina triloba (L.) Dunal) may form dense thickets.

In contrast to oak and hickory species, the crowns of the

shade tolerant species have leaves with small sinuses

(sugar and red maple), leaves without sinuses (American

beech), densely packed crowns, and a deep crown as

shade tolerance permits survival of leaves and branches on

the lower half of the trunk (sugar maple and beech). The

green cells in the leaves of these shade tolerant species

have a special light capturing mechanism that allows them
81

to photosynthesize under extremely low light conditions

where PAR may be only one percent of full sunlight. The

mechanism may be visualized as a large molecule in which

antennae or spokes composed of chlorophyll A, carotinoids,

and xanthophyll funnel light energy to chlorophyll B to the

hub at the center of the spokes. Oak and hickory do not

have this mechanism and are inefficient at photosynthesizing at low light levels.

Light levels are lowest in upland oak-hickory dominated

stands where there also is a dense midcanopy of maple

and beech. These multi-layered canopies reduce PAR to its

lowest levels of less than 0.01 percent. Not only is there a

total absence of sunflecks and indirect radiation but the

light transmitted through the leaves is highly filtered. These

stands also have a high leaf area index (area of leaves/

area of ground), thus the litter layer may be several inches

thick and create a smothering effect well into the summer

and fall. Oak seedling and herbaceous layers and even

sugar maple and beech seedlings usually are absent in this

environment (Fralish and others 1991).

FOREST SUCCESSION AND LOSS OF BIOTA

The elimination of natural disturbance such as fire initiated

the process of succession which has had and is having

several distinctly negative impacts on the forest ecosystem.

Succession usually has been viewed as a single lengthy

event but in the central hardwood forest some events are

distinct, relatively short, and independent and disjunct from

other events or processes.

Loss of the Black Oak Species

In the central hardwood forest, the first stage of succession

is the loss of “black oak” species (black, blackjack, southern

red, scarlet) from post oak dominated stands on xeric sites,

or from stands of mixed white oak, “black oak,” and northern

red oak on xeric-mesic and mesic sites. On xeric sites where

mesophytes seldom invade, the loss of black oak may be

considered as part of a compositional change as opposed

to the process of succession. The death of “black oak” trees

in post and white oak stands has been documented at LBL

(Kentucky and Tennessee) and in Illinois. At LBL, data from

the 1976 and 1986 remeasurement of permanent plots

indicated that high mortality occurred in the black oak group

while species of the “white oak” group (white oak, post oak

and chestnut oak (Quercus prinus L.) and hickory had relatively low mortality (Groton and others 1988). Approximately

70 percent of the stems alive in 1988 were oak with only 20

percent of these in the black oak group, but approximately

45 percent of total mortality was black oak (Wellbaum 1989).

On permanent plots at Kaskaskia Experimental Forest in

southern Illinois, mortality of scarlet, black and northern red

oak was higher than that of white oak with the mortality

level of scarlet twice that of black oak (Schlesinger 1989).

However, loss of trees of black oak species on xeric and

xeric-mesic sites may only be temporary because mesophytic species usually are not a problem and opening of the

canopy may permit the establishment of black oak seedlings. A comparison of 10-12 year old clearcut oak stands at

Land Between The Lakes indicates that species of the

black oak group have a collective average relative density

of 20 to 30 percent (Snyder 1995); however, in many

stands, the density was double or triple that of the white

oak group or hickory suggesting that there could be a

substantial recovery over time.

On mesic sites in the central hardwood forest region, death

of black oak species is the only beginning of a more

extensive loss of biodiversity as species richness (number)

decreases concurrently with purification (reduced equability)

as white oak temporarily assumes greater dominance.

Small trees {< 8 inches in diameter at breast height (d.b.h.)]

with poorly developed crowns and the largest trees (70-100

cm in d.b.h.) of the shorter lived (150-175 years) “black

oak” species have been or are being phased out while

trees of the longer lived (300-350 years) white oak and

hickory remain. Individuals of “black oak” reach physiological maturity and the end of their life span at about 150-

170 years. At 125-150 years or earlier for some species

such as scarlet oak, trees begin to show the typical signs of

old age: heart rot, presence of large dead branches, patches

of dead bark, large broken branches and/or tops, reduced

number of leaves (thin crown) and a weak root system

(frequent wind thrown trees). The relatively high density

and increased competition in forest stands in addition to the

drought and insect attacks of the 1980s may have reduced

tree vigor which subsequently resulted in increased mortality

due to secondary causal agents such as Hypoxylon canker.

Loss of White Oak and Hickory

The loss of white oak and hickory is probably the last event

to occur as mesophytes totally occupy the site. On mesic

sites, white oak (specifically Quercus alba) and hickory

(extreme life expectancy = 300-400 years) will be replaced

by the more long lived (450-500 years) sugar maple and

American beech. Because of the extensiveness of mesic

sites, the effect of succession will be to create “islands” of

remaining white oak and post oak stands on xeric and

xeric-mesic sites in some regions (e.g., Shawnee Hills;

LBL) or to completely blanket the landscape with a near

monoculture of sugar maple or American beech in others

(e.g., Illinois Ozark Hills, Illinois Coastal Plain, Tipton Till

Plain).

Reduced Productivity/Mast

Forest productivity will decrease as oak and hickory trees

are systematically eliminated from the forest. In a high light

environment (direct sunlight on the upper crowns), they

grow faster than maple and beech. In a shaded environment,

maple and beech seedlings, saplings, and midcanopy trees

survive better and grow faster. The physiological basis for

the growth differential between these two groups is reviewed

by Hale and Orcutt (1987), Kozlowski and others (1991),

and Kozlowski and Pallardy (1997).

There is an interesting paradox regarding the rate of oak

growth and rate of succession. It would be reasonable to

expect that slow-growing oak and hickory stands on xeric

and xeric-mesic sites should be easily replaced by invading

species, while their high growth rate on mesic sites would

permit them to dominate indefinitely. The reverse situation

actually occurs. The lack of soil moisture which results in

slow oak growth on xeric sites also prevents succession to
82

mesophytic (moisture requiring) species. High soil moisture

on mesic sites permits a rapid oak growth rate but creates

an environment suitable for invasion and development of a

community dominated by shade tolerant mesophytes. In

terms of resource management, the most productive oak

and hickory stands are being replaced by slower growing

mesophytic species while the least productive stands remain

intact. The amount of mast produced for wildlife parallels

that of tree growth.

Loss of Animals

The importance of oak and hickory nuts to wildlife is well

known and documented. Nationwide, oak is used by 96

animals (Martin and others 1951); however, for eastern

United States (land west of the prairie zone), the number is

considerably lower (table 1). Of the 44 animals listed, the

majority are birds (28) and of these only seven are considered game animals; the remainder (21) are small birds.

Succession impacts stand productivity by reducing the

amount of mast (nuts, buds, twigs) produced for wildlife as

oak and hickory are replaced by mesophytes. Thus, loss of

animals will start to occur as the black oak are lost but the

major impact will come decades or more latter when white

oak trees die. While beech is a mast producer, the soft

tissues of maple seed quickly decompose if the seed does

not germinate.

However, the impact of succession on wildlife populations is

going to be greater than that suggested by the number of

species listed in table 1. The somewhat more indirect influence will be on herbaceous plants which support various

neotropical migrant birds and insect populations.

Loss of Herbaceous Plants

The present high density of seedlings, saplings and small

trees of mesophytic species within the central states oakhickory forest is having a major deleterious effect on the

herbaceous layer. This loss is the most important unreported

impact resulting from forest succession. The loss in herb

richness can be considerable as Jones (1974) and Harty

(1978) reported between 50 and 75 herbaceous plants for

both spring and summer/fall guilds.

Data collected from Trail of Tears State Forest in the Illinois

Ozark Hills region indicates that as photosynthetically active

radiation decreases and the amount of ground litter

increases, there is a major decrease in the number of

herbaceous species (table 2). Species richness increased

200 percent from an average of 10 species/10 m2 sample in

a forest composed of black and white oak and hickory with

a closed canopy of smaller sugar maple trees (d.b.h. of 10-

20 cm) to an average of 31.5 species/10 m2

 in open stands

dominated by black oak, white oak, and hickory without

maple. There is little difference in species richness between

the open black/white and post oak stands although post

oak occurs on drier sites and has considerably higher PAR

levels. In dense sugar maple dominated forest of the Ozark

Hills region, few seedlings or herbs can be observed.

Wilhelm (1991) also reported a decrease in the number of

summer and fall flowering species between 1980 and 1988

and related this decrease to the increase in sugar maple

importance in the tree canopy. At Land Between The Lakes

(LBL) in Kentucky and Tennessee, Close (1996) recorded

cover for herbaceous in uncut post oak, black oak, and

white oak dominated stands. By comparison, Glickauf (1998)

found about twice the number and double the cover of

species in shelterwood cut stands at LBL, suggesting that

even in oak dominated stands, the light resource prevents

full development of understory herbs. Therefore, it should

be of no surprise that the added layers of branches and

leaves, due to a midcanopy of mesophytic species, impoverishes the herbaceous stratum.

In a related experiment on a common oak-hickory forest

herb, pots containing dittany [Cunila origanoides (L.) Britt.]

plants were placed in the open and in the same four

community/structural types as listed in table 2: post oak,

black oak/white oak without a sugar maple understory,

black oak/white oak with a thin maple understory, and black

oak/white oak with a dense maple understory. The amount

of light decreased with increasing overstory and understory

density. The plants in the two open areas (no shade) were

healthy and robust (high dry weight) and produced copious

flowers in the fall. The plants in the post oak and black oak/

white oak stands (minimum shade) without maple grew

well, were slightly taller than the open grown plants, and

flowered in the fall, but were less robust (smaller dry

weight). One-half of the dittany plants in the black oak/white

oak forests with a thin maple midcanopy (moderate shade)

and all but one plant under the dense maple midcanopy

(heavy shade) were dead by July or August. The one plant

that survived under heavy shade did not flower. Across the

light levels (table 2), plants grown in shade were taller and

thinner than those grown in the open, and the heavier the

shade, the taller and thinner the stem such that under the

two lowest light levels, the plants were unable to maintain

an upright orientation, fell over and died.

As described earlier, the amount of PAR on the forest floor

is a function of crown and stand density (structure). The

adaptive geometry of oak trees (Horn 1971) permits light

penetration through the canopy and increases photosynthesis not only in lower leaves but permits survival of herbaceous plants on the forest floor. Because of oak species

have thin crowns and there is space around each crown,

the relatively low amount of leaf biomass produces only a

thin leaf litter layer in the fall, and this layer is decomposed

by early summer.

Conversely, extremely shade tolerant species such as

sugar maple and American beech have a high stem density,

overlapping crowns and thick crowns of multiple leaf layers

as lower branches remain alive. These characteristics

produce a high leaf biomass. In autumn, the leaves create

a thick (3-5 cm deep) litter layer that often remains throughout the growing season and smothers the new growth of

herbaceous plants. The litter appears to be of sufficient

thickness that new seedlings will not survive because the

extending radical cannot reach mineral soil and water

before desiccation occurs. Bazzaz (1979, 1996) describes

these and additional relationships.

Although the invasion of mesophytes reduces the number

of oak forest herbs, the herbaceous layer of maple/beech
83

Table 1—Amount of oak (Quercus) species used as food by bird and animal species in eastern United States

Type of animal Percent of diet Region

Upland game birds (acorns, buds)

Grouse, ruffed ** E

Pheasant, ringed-necked * NE

Prairie chicken, greater * Wisc

Prairie chicken, lesser * Okla

Quail, bobwhite ** NE

Songbirds (acorns)

Blackbird, rusty + NE

Crow, common * E

Flicker, yellow-shafted + E

Grackle, purple *** E

Grosbeak, rose-breasted + E

Jay, blue   E

Meadowlark + SE

Nuthatch, white-breasted ** * E

Sapsucker, yellow-bellied + E

Starling + NE

Thrasher, brown ** E

Titmouse, tufted ** E

Towhee, red-eyed ** NE

Woodpecker, downy + E

Woodpecker, red-bellied *** E

Woodpecker, red-cockaded + SE

Woodpecker, red-headed *** E

Wren, Carolina + E

Waterfowl (acorns)

Mallard duck * E

Pintail duck + SE

Wood duck ***** NE

Wood duck *** SE

Marsh birds (acorns)

Rail, clapper + SE

Fur and game animals (acorns, buds, bark)

Bear, black **** NE

Beaver + NE

Fox, gray + S

Fox, red + NE

Muskrat + NE

Opossum * E

Rabbit, cottontail * NE

Rabbit, mearns + NE

Raccoon ++++ E

Squirrel, flying ** NE

Squirrel, fox   E

Squirrel, gray ** ** E

Squirrel, red ** E

Small mammals (acorns)

Chipmunk, eastern ** NE

Mouse, meadow + E

Rat, wood ++ S

Hoofed browser (twigs, foliage, acorns)

Deer, white-tailed **** E

Data summarized from Martin and others (1951). The star ranking system for percent of diet is: + = 0.5–5 percent; * = 2-5 percent; ** = 5–10 percent;

*** = 10–25 percent;   = 25–50 percent; ** *** = > 50 percent. Location is designated by region: E = eastern United States; NE = central hardwood

forest region including most of the Appalachian Mountains and the northern hardwood-conifer forest of the Lake States and New England; SE =

southern pine-hardwood forest.
84

dominated communities has high species richness in some

regions (Curtis 1959) and some mesic sites in the central

hardwood forest (Jones 1974, Harty 1979, Close 1996).

Small stems of sugar maple, American beech and other

mesophytes indicate the advance of this forest, but the gap

between time of elimination of oak-hickory forest herbs and

time of invasion of mesophytic forest herbs may be 50 to

100 years or longer and may not occur on more xeric sites.

During this gap, insect populations are likely to be reduced

and soil surface erosion increased depending on seedling

density. These aspects of herb importance should be the

thrust of future research.

A dense herbaceous layer is important for production of

flowers and seeds and of leaf material for insects, all of

which are used by various neotropical bird species. The

above ground herbaceous layer also protects the soil from

erosion by heavy rains as roots assist in holding soil is

place. Herbaceous plants also store nutrients and reduce

the loss of nutrients from the site and ecosystem.

OAK MANAGEMENT

It would appear that near complete loss of the oak-hickory

forest component is eminent. Given another 75-100 years,

there will be few stands dominated by oak and hickory species although a few scattered trees may remain. Moderate

disturbances that would regenerate oak and hickory remain

absent or restricted, and at this time, there appears to be

limited opportunity to reintroduce fire into the ecosystem.

Non-scientists have suggested that oak regeneration will

appear when large individual trees die as is occurring with

the black oak component. These large individuals may be

standing dead or on the ground as windfalls. Standing dead

typically lose progressively larger branches over a period of

five to ten years and then fall as a single pole-like structure.

A windfall, where the entire tree tips and falls, will typically

leave intact the midcanopy of mesophytic species where it

was standing but may disrupt the midcanopy under adjacent large trees. In either case of individual tree death, or

under a silvicultural program of individual tree selection

where sugar maple and American beech have formed a

sufficiently mid-canopy, no canopy gap for light penetration

is formed, or if formed, it is rapidly closed by the crowns of

mesophytes. The death of or removal of individual trees

works strongly to the advantage of sugar maple and beech

and to the detriment of oak and hickory seedlings and

saplings which need direct solar radiation throughout their

entire life.

Conversely, data from 80 permanent plots in the Illinois

Ozark Hills have shown that clearcutting is not the answer

to regenerating oak on moist sites. This case study by

Presmyk (1987) examined four contiguous areas: 1981

clearcut, 1975 clearcut burned (wildfire) in 1981, mature

forest burned (wildfire) in 1981, unburned forest. The original

overstory on these areas was black, white, and northern red

oak with yellow-poplar and beech as secondary species.

The plots were resampled in mid 1990. In the 1981 clearcut

(no fire), the north slopes converted immediately to beech,

red maple, yellow-poplar, black gum and sassafras; a small

amount of oak was present. In the 1975 clearcut that burned

in 1981, the beech, maple, and other tree species on north

slopes were killed and the area reverted into a tangle of

brush [devil’s walking stick, Aralia spinosa L.; sassafras,

Sassafras albidum (Nutt.) Nees; mulberry, Morus rubra L.;

grape, Vitis spp.]. Few stems of oak were present. However,

on the drier south slopes, white and black oak were major

regenerating species along with red maple, yellow-poplar

(Liriodendron tulipifera L.), black gum (Nyssa sylvatica

Marsh.), and sassafras. The burned mature forest had a

similar understory as did the unburned forest but the burned

forest had larger amounts of sassafras, white oak, yellowpoplar, and black gum. The conclusion is that clearcutting

alone does not regenerate oak, post harvest fire may reduce

a forest to non-productive status for a lengthy period, and

that fire in mature forest increases the amount of oak regeneration. It would appear that on moist sites in particular, fire

prior to harvesting is necessary to establish oak regeneration. In the absence of fire after cutting, the forest will immediately convert to mesophytic hardwoods if they are the

major understory component. In the clearcuts of these

watersheds, erosion of tributaries to the main intermittent

stream was evident and substantial.

Based on research, it would appear that in stands where

stems of the invading mesophytes are still relatively small

(saplings), several prescribed fires followed by partial

harvesting using an even-aged approach such as shelterwood would permit the establishment of oak and hickory

seedlings, maintain mast production at a reasonable level,

and develop the herbaceous layer while protecting the site.

Table 2—The relationship between number of species, photosynthetically

active radiation, and litter weight under four forest canopy/community types

on southeast, south, and southwest slopes in the Illinois Ozark Hills region

Canopy/community type

Open Closed

Post oak Black oak Black oak Oak/maple

PAR (umol m-1 s-1) 233.8 138.4 51.7 8.85

Litter weight (kg/m2) 0.75 0.66 0.97 1.10

Species/10 m2 31.5 31.5 25.0 10.0

PAR = photosynthetically active radiation.

Unpublished data collected in 1996. All the oak communities include some white oak,

southern red oak, and scarlet oak.
85

CONCLUDING REMARKS

For many years, mast production for wildlife has been

considered one of the most important attributes of oak and

hickory dominated communities. However, due to the length

of time (centuries) oak and hickory have dominated the

central hardwood forest region, and because of the low

density of their crowns and overstory canopy, they have

become of major importance to the herbaceous stratum

and the wildlife that depend on herb foliage and seed for

survival. In terms of supporting mammals, birds, herbs, and

insects, oak and hickory have become keystone species. In

the central hardwood forest, loss of these dominant keystone species through succession will result is loss of biota

ecologically and evolutionarily associated with oak-hickory

forest.

In recent years, new attitudes developed jointly with new

available scientific information have directed forest management away from timber production and toward other

forest ecosystem values such as preservation of rare or

endangered species, development of old growth characteristics, and maintenance of species diversity to the level

thought to be present in presettlement communities (before

ca. 1810). Unfortunately, it is too often believed that total

protection will permit the forest to maintain or restore these

values. This belief is in error because oak and hickory are

shade intolerant keystone species subject to successional

replacement, and thus, their response is similar to other

communities composed of disturbance dependent, pioneer

species of the southwest (e.g., longleaf pine, Pinus

palustris), the north (quaking aspen, Populus tremuloides),

and west (lodgepole pine, Pinus contorta).

Disturbance plays an important role in ecosystem development. Fire in particular reduces invasion of mesophytes in

oak stands, and with a less dense overstory, white and

black oak stands can be maintained to old growth with a full

complement of understory herbs. Conversely, the extremely

dense, multi-layered mesophytic forest is viewed by many

as the epitome of old growth (primeval forest), yet according to early land survey records, it was rare to nonexistent

in most areas of the central hardwood forest (Crooks 1988;

Fralish and others 1991, 2002).

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88

INTRODUCTION

Ecoregions are large areas of the Earth’s surface that

enclose smaller ecosystems having common characteristics

(Bailey 1998). Ecoregions may be delineated using differing

mapping criteria, but are largely integrations of physical,

biological, and cultural components, including climate,

geologic formations, soils, terrestrial and aquatic fauna and

flora, and land use (Bailey 1983, Omernik and others 2000).

Assessment, evaluation, analysis, and planning across subregional areas are increasingly being based on ecoregions

(Bryce and others 1999) and particularly land management

decisions dealing with water-quality issues (Griffith and

others 1999). Ecoregion maps are typically delineated in a

subjective, qualitative manner, but generally are not tested

because independent datasets are not available. Untested

ecoregion maps have been used for purposes such as

resource assessments (Rudis 1998).

Tree species in the Southern Appalachian Mountains are

distributed individualistically along temperature and moisture gradients (Whittaker 1956) that are likely associated

with physiological requirements of vegetation for establishment, growth, and reproduction (Kramer and Kozlowski

1960). McNab and others (2002) found that Southern

Appalachian tree species can be used as indicators of

forest site productivity. Kuchler (1964) and others used

overstory cover types, consisting largely of tree species, as

a means of stratifying large, subregional geographic areas

into smaller, more homogeneous ecological units. We

reasoned that if adjacent mapped polygons are dissimilar

environmentally, then the frequency of occurrence of one or

more tree species should differ also and provide a means

of testing ecoregion uniqueness. Also, tree species could

provide a biological basis for subdivision of large ecoregions

into more homogeneous smaller units.

We are not aware of tests of ecoregion mapping in the

South. We have successfully used data from an extensive

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

Forest Inventory and Analysis (FIA) plots to identify tree

species that indicate site quality (McNab and others 2002).

Our success suggests that FIA data could be used to test

similarity of ecoregions, also using an indicator-species

approach. The primary objective of our current study was to

determine if species composition differed among ecoregions.

We based our study on the premise that assemblages of

tree species will vary among areas of differing environmental conditions. Our study should be considered a pilot

test because it was made in a small geographical area that

did not include the full extent of the mapped ecoregions.

METHODS

Our study was limited to FIA unit 4 of Tennessee (fig. 1),

which consists mainly of the Cumberland Plateau physiographic province and smaller areas of three other provinces.

Schweitzer (2000) describes forest statistics of this region,

which extends over 4 million acres, includes 16 counties,

A PILOT TEST OF INDICATOR SPECIES TO ASSESS UNIQUENESS OF

OAK-DOMINATED ECOREGIONS IN CENTRAL TENNESSEE

W. Henry McNab, David L. Loftis, Callie J. Schweitzer, and Raymond M. Sheffield1

1 Research Foresters, USDA Forest Service, Southern Research Station, Asheville, NC 28806; Research Forester, USDA Forest Service,

Southern Research Station, Normal, AL 35762; and Research Forester, USDA Forest Service, Southern Research Station, Asheville, NC

28802, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—We used tree indicator species occurring on 438 plots in the Plateau counties of Tennessee to test the

uniqueness of four conterminous ecoregions. Multinomial logistic regression indicated that the presence of 14 tree

species allowed classification of sample plots according to ecoregion with an average overall accuracy of 75 percent

(range 45 to 94 percent). Additional analysis revealed that the largest ecoregion could be subdivided into northern and

southern zones based on frequency of occurrence of five other indicator species. Under the premise that tree assemblages of varying composition indicate areas of differing environmental conditions, results of our test suggest the

delineated ecoregions are unique.

Figure 1—The study occurred in the plateau FIA survey unit of

Tennessee.
89

and is about 71 percent forested. Smalley (1982, 1983,

1984) developed a conventional forest site classification

system for this region. In Hinkle’s (1989) extensive vegetation study, oak and hickory assemblages dominate forest

cover types.

We evaluated ecoregions mapped by Griffith and others

(1998). Griffith and others (1997) described the mostly

qualitative methods of their ecoregionalization process in

Tennessee as “compiling and reviewing relevant materials,

maps and data; outlining the regional characteristics; drafting the ecoregion boundaries; creating digital coverages

and cartographic products; and revising as needed after

review by national, state, and local experts.” Essentially, the

U.S. Environmental Protection Agency (EPA) ecoregions

are areas of relatively uniform climate, geology, landform,

natural disturbance, land use, terrestrial vegetation, and

aquatic fauna. Other intermediate-scale ecoregion maps

were available in digital format. However, we selected this

one primarily because it delineated the escarpment as a

sinuous but relatively large, distinctive, and detailed

ecoregion that could be displayed relatively accurately on

the base map. Also, the escarpment unit generally agreed

with our field observations and knowledge of the area. Our

study tested this ecoregion as a unique ecosystem, which

apparently was an issue among reviewers of the final map

product (Griffith and others 1997). Ecoregions were retained

for analysis that included a minimum of 30 plots.

Using the FIA Eastwide database (Hansen and others 1992),

tree- and plot-level data were available for 513 sample plots

in the 1999 inventory that had been installed at intersection

locations on a 3- by 3-mile grid. Arborescent vegetation ≥ 1

inch in diameter at breast height at each grid location was

inventoried by species at four points with 1/24-acre and

1/300-acre nested plots. However, genera were used as

inventory groups where species could not be determined

accurately, such as for hawthorns (Crataegus spp.), serviceberries (Amelanchier spp.), and occasionally for hickories

(Carya spp.). Schweitzer (2000) provides additional information on the vegetation sampling methods. In addition to

a species list, available data for each plot included elevation

(nearest 10 feet), aspect (nearest degree), slope gradient

(nearest percent), and latitude and longitude. For tree

species we recorded the inventory data on each sample

plot as a binary variable: present or absent. To reduce the

confounding influence of disturbance associated with regeneration of certain species, e.g., yellow-poplar, red maple,

and sweet birch (Beck and Della-Bianca 1981, Golden

1974), we did not use a measure of abundance as independent variables, such as number of individuals of each

species present or crown area by species. We excluded

plots that were not forest land, or had been planted, or

were not stocked with trees.

In the analysis, we included only those species present on

10 percent or more of the total plots to reduce the chance

that uncommon species unique to this dataset could unduly

influence the results. We excluded the hickory genus from

the analysis because some species are highly site specific;

e.g., bitternut, but were not identified. We used several types

of analyses to investigate the distribution of tree species

among and within ecoregions. We used chi-square to test

hypotheses that the frequency of occurrence of each species

among ecoregions did not differ from its frequency of occurrence over the entire unsubdivided study area. We used

calculated species richness, i.e., the number of species

present on each plot, and available plot basal areas to

characterize the tree stands among ecoregions.

We used logistic regression instead of discriminant analysis

to develop classification functions because most of our

independent variables were qualitative (Press and Wilson

1978). We used multinomial logistic regression to examine

the relationship of the presence of multiple species with the

four ecoregions. Our statistical software package, STATA v.

7 (StataCorp 2001), did not provide a fast and efficient stepwise procedure to determine a suitable model with this type

of analysis. Therefore, we began initial trial formulations

with influential species from the chi-square goodness-of-fit

tests and our own field experience. We followed the rationale

of Hosmer and Lemeshow (2000) to develop and interpret a

significant and parsimonious multinomial model.

We used ordinary logistic regression to study the effect of

latitude on tree distribution within the largest ecoregion, the

Cumberland Plateau. We arbitrarily subdivided the Plateau

into north and south zones at 36° latitude, near Crossville,

TN, to provide about equal plot numbers for analysis.

Species included in this analysis were limited to those

occurring on ≥ 10 percent of the plots. This model used

backward elimination of species insignificant at the P = 0.05

level of probability.

RESULTS AND DISCUSSION

Ecoregion Study Areas

For analysis we retained ecoregions that included a minimum

of 30 plots, which included, from west to east: (1) eastern

highland rim, 40 plots; (2) plateau escarpment, 115 plots;

(3) Cumberland Plateau, 216 plots; and (4) Cumberland

Mountains (67 plots) (table 1). For brevity, these ecoregions

are hereafter called rim, escarpment, plateau, and mountains, respectively. We excluded smaller portions of two

ecoregions (Sequatchie Valley and Nashville Basin) because

of their small size and lack of sufficient plots for analysis.

Over the study area, plot elevation averaged 1,568 feet

(range 670 to 3,200 feet), slope gradient averaged 24

percent (range 0 to 84 percent), and all aspects were

represented.

Mean Basal Area and Species Richness

Stand basal area averaged almost 105 square feet per acre

throughout the study area (table 2). Average basal area

was lowest in the rim and highest in the Cumberland

Mountains. Except for one plot in the plateau, stand basal

areas among ecoregions ranged from about 10 square feet

per acre to > 150 square feet per acre. The plot of highest

basal area was located in the northern portion of the plateau

and consisted of an unusual species combination of red

maple, three oak species (chestnut, scarlet, and chinkapin),

black gum, sourwood, bigleaf magnolia, white pine, and

hemlock. The latter three species suggested that the site

was situated near a mesic environment, such as a stream

ravine. High stocking levels were not unusual in the plateau,

where nine stands had basal areas exceeding 170 square

feet per acre.
90

Species richness averaged 12.5 throughout the study area

and ranged from about 3 in the mountains to almost 24 in

the rim (table 2). The lowest species richness (3) occurred

on a single plot on a mesic site in the mountains where a

stand with basal area of 48 square feet per acre consisted

only of red maple, yellow-poplar, and black locust. Generally, a minimum of 6 to 7 species and maximum of 19 to 20

species were present on plots of all ecoregions. In the plateau ecoregion, species richness was negatively correlated

with elevation (r = -0.24, P < 0.0004) and positively correlated with slope percent (r = 0.28, P < 0.0001). In the rim,

richness was correlated with slope gradient (r = 0.38, P =

0.009) and transformed aspect (r = -0.37, P = 0.019).

Species Composition of Ecoregions

A total of 87 species or species groups, e.g., Amelanchier

spp., were identified in the study area, of which 35 species

were present on ≥ 10 percent (43) of the total 438 plots

(table 3). The nine most common species occurred on more

than one-third of the sample plots in each of the four ecoregions. Red maple was the species of widest distribution,

occurring on 83 percent of the total study area, followed by

white oak and black gum. Some species were uniformly

common in three of the four ecoregions, such as sugar

maple, chestnut oak, and American beech. Species such as

shortleaf pine, hophornbeam, and southern red oak occurred

with higher frequencies in two of four ecoregions. None

of the common species occurred with obviously higher

frequency in a single ecosystem, which alone could be

used as an indicator species. Several of the less common

species, including tree-of-heaven, bigleaf magnolia, and

willow oak, occurred almost exclusively in a single ecoregion, but their scarcity makes then unsuitable as an

indicator species. Chi-square tests of hypothesized proportional frequency ratios indicated that the frequency of

occurrence (expressed as a percentage) of many species

varied among ecoregions (table 3). Although the individual

variation in occurrence of species suggests differences

exist among ecoregions, a multispecies model should

provide increased classification accuracy.

Classification Among Ecoregions

A multiple logistic model utilizing the 36 common species

occurring on the field plots indicated that 14 were significantly associated with the four ecoregions (table 3). Overall

classification accuracy was 75 percent. The model classified

inventory plots in the plateau with greatest accuracy, 94 percent, and those in the rim with lowest accuracy, 42 percent.

Table 1—Characteristics of principal ecoregions in the study area of Tennessee

Ecoregions

Characteristic Rim Escarpment Plateau Mountains

Physiography Weakly Mountainsides Rolling Low

dissected tableland mountains

plateau

Elevation (ft.) 800 – 1,300 800 – 2,400 1200 – 2,000 1,200 – 3,500

Geologic age Mississipp. Pennsylvan. Pennsylvan. Pennsylvan.

Primary bedrock or Limestone, Sandstone- Sandstone, Sandstone,

mixture chert limestone mix siltstone siltstone

Soil order Ultisols Ultisols Ultisols Inceptisols

Precipitation (in.) 52 – 56 52 – 60 48 – 60 50 – 55

Frost free (days) 190 – 210 180 – 200 180 – 200 180

Jan. Min/Max (F) 25 – 46 24 – 44 24 – 44 21 – 43

Jul. Min/Max (F) 65 – 88 63 – 85 63 – 85 61 – 85

Potential natural Mixed oak Mixed mesophytic, Mixed oak Mixed

vegetation mixed oak mesophytic

Primary landuse Agriculture Forests Forests Forests

Table 2—Mean (SE) and range of stand basal area and species richness by

ecoregion in the study area of Tennessee

Ecoregion Plots Stand basal area (ft2 per ac) Species richness

N Mean (SE) Range Mean (SE) Range

Rim 40 99.9 (5.4) 10 – 158 13.5 (0.6) 7 – 24

Escarpment 115 104.3 (3.0) 34 – 206 13.2 (0.2) 6 – 20

Plateau 216 105.3 (2.3) 4 – 224 11.9 (0.2) 6 – 18

Mountains 67 106.8 (4.2) 16 – 186 12.3 (0.4) 3 – 19

All 438 104.8 (1.6) 4 – 224 12.5 (0.1) 3 – 24
91

Table 3—Arborescent taxa occurring on  10 percent of the total 438 sample plots occupying four

ecoregions in the study area of Tennessee and their significance as potential indicator species

Ecoregiona Indicator

Arborescent taxa Rim Esc. Plt. Mtn. All Ind.b Mul.c

 - - - - - - - - - -percent of plots- - - - - - - - - -

Red maple (Acer rubrum) 73 64 94 87 83 0.032 .

White oak (Quercus alba) 63 51 94 67 76 0.001 *

Black gum (Nyssa sylvatica) 78 57 82 69 73 0.085 *

Sourwood (Oxydendrum arboreum) 40 40 85 45 63 0.001 *

Yellow-poplar (Liriodendron tulipifera) 73 65 47 76 58 0.012 .

Black oak (Quercus velutina) 40 43 67 42 54 0.005 .

Sassafras (Sassafras albidum) 40 42 57 48 50 0.171 .

Pignut hickory (Carya glabra) 45 59 44 45 48 0.253 .

Dogwood (Cornus florida) 68 49 46 34 47 0.104 .

Chestnut oak (Quercus prinus) 13 46 47 63 46 0.003 .

Scarlet oak (Quercus coccinea) 30 24 61 31 44 0.001 .

Northern red oak (V:Quercus rubra) 43 57 27 54 40 0.001 .

Mockernut hickory (Carya tomentosa) 55 27 46 39 41 0.030 .

Virginia pine (Pinus virginiana) 18 21 53 30 38 0.001 .

Sugar maple (Acer saccharum) 55 71 6 55 35 0.001 *

Black cherry (Prunus serotina) 45 32 25 36 30 0.142 .

Shortleaf pine (Pinus echinata) 0 12 39 22 26 0.001 .

Shagbark hickory (Carya ovata) 35 49 9 13 23 0.001 *

American beech (Fagus grandifolia) 43 30 8 36 21 0.001 *

Post oak (Quercus stellata) 20 5 35 6 21 0.001 .

Green ash (Fraxinus pennsylvanica) 43 32 5 15 17 0.001 .

White ash (Fraxinus americana) 28 42 2 13 16 0.001 .

Eastern redbud (Cercis canadensis) 33 43 0 10 16 0.001 *

Eastern white pine (Pinus strobus) 0 3 28 9 16 0.001 *

Southern red oak (Quercus falcata) 33 2 24 6 16 0.001 *

Black locust (Robinia pseudoacacia) 3 26 5 33 14 0.001 *

Eastern hemlock (Tsuga canadensis) 0 9 20 15 14 0.005 .

American holly (Ilex opaca) 0 3 23 9 13 0.001 .

Cucumbertree (Magnolia acuminata) 5 18 3 34 12 0.001 *

Eastern hophornbeam (Ostrya virginiana) 28 28 2 6 12 0.001 .

Serviceberry (Amelanchier sp.) 3 3 19 9 12 0.001 .

Eastern redcedar (Juniperus virginiana) 43 25 4 0 12 0.001 *

Bitternut hickory (Carya cordiformis) 18 10 9 19 11 0.077 .

Sweetgum (Liquidambar styraciflua) 28 11 7 12 11 0.006 *

Winged elm (Ulmus alata) 33 25 1 3 11 0.001 *

Black walnut (Juglans nigra) 20 23 1 7 10 0.001 .

a Abbreviations of ecoregions and number of plots: Rim = Eastern Highland Rim (40 plots); Esc. = Cumberland Plateau

escarpment (115); Plt. = Cumberland Plateau (216); Mtn. = Cumberland Mountains (67).

b Chi-square probability that the actual frequencies of occurrence of individual species among ecoregions are equal to the

expected frequency determined for the area as a whole.

c Multinomial logistic regression probability (* denotes P ≤ 0.05) that the presence of certain combined species discriminate

among ecoregions.

Source: Griffith and others (1998).

Inclusion of black gum as a significant indicator species

was surprising and probably was simply an artifact of the

dataset because it occurred in all ecoregions at a relatively

high level.

Several contributing factors are possible explanations for

the reduced classification accuracy of several ecoregions,

particularly the mountains and escarpment. The most

important factor is lack of precise map delineation of some

ecoregion boundaries, particularly the upper elevation location of the highly crenulated escarpment. Unlike boundaries

of other ecoregions that have broad transition zones, the

escarpment is generally sharply defined. Also, the small

sample sizes for several ecoregions likely influenced model

accuracy. In our test, the best results were obtained for the

largest ecoregion, for which 233 plots were available for

analysis. Finally, our biological indicator, tree species, may

be an inexact integrator of environmental conditions.

Inclusion of shrub and herbaceous species would likely

increase classification accuracy.
92

Classification Within Ecoregions

Twenty-two species were present on >10 percent of the

216 plots in the plateau and were used to develop a logistic

model for subdividing this ecoregion into northern and

southern zones (table 4). Three of the 22 species, yellowpoplar, white pine, and shortleaf pine, occurred with unequal

frequencies between the two zones, and two species, chestnut oak and American holly, were significant at a lower level

(P ≤ 0.1). An overall classification accuracy of 70 percent

was achieved with a logistic model that included the three

significant (P ≤ 0.05) species. Two species, chestnut oak

and American holly, which were not significantly associated

with the two ecoregion zones, increased in importance (P <

0.02) in the presence of the other species. The presence of

both these species increased the probability that a subject

plot was situated in the southern zone of the plateau. The

presence of two pine species, shortleaf and white, were

strong indicators of plot classification membership in the

northern zone. Individual classification accuracies were

similar for the two zones: 70 percent for the south and 72

percent for the north.

These results suggest the plateau could be subdivided into

northern and southern zones. If a latitude effect within the

plateau ecoregion is real, perhaps resulting from climatic or

physiographic differences, the boundary likely would not be

at the location of our subdivision, 36° latitude, which we

selected arbitrarily. Inclusion of shrubs and herbs has often

increased classification accuracies of site-specific applications of indicator species, such as productivity evaluation

(Hodgkins 1961); however, it is unclear if nontree species

would be beneficial to classification over large geographic

areas.

CONCLUSIONS

In this pilot study in the Cumberland Plateau region of

Tennessee, we investigated the use of tree indicator species

as a means of testing the delineation of ecoregions, which

are ecologically dissimilar areas that likely respond differently to management. Using inventory data from > 400

permanent FIA plots established throughout the study area

of > 4 million acres, we found that the relative frequency of

occurrence of 14 tree species varied significantly in each of

Table 4—Arborescent taxa occurring on  10 percent of the total 216 sample plots

occurring in two zones of the Cumberland Plateau ecoregion in Tennessee and

their significance as potential indicator species

Zonea Indicator

Arborescent taxa South North All Ind.b Mul.c

- -percent of plots- -

Red maple (Acer rubrum) 94 94 94 0.994 .

White oak (Quercus alba) 93 96 94 0.773 .

Sourwood (Oxydendrum arboreum) 86 84 85 0.900 .

Black gum (Nyssa sylvatica) 83 81 82 0.843 .

Black oak (Quercus velutina) 65 69 67 0.761 .

Scarlet oak (Quercus coccinea) 63 60 61 0.779 .

Sassafras (Sassafras albidum) 63 52 57 0.317 .

Virginia pine (Pinus virginiana) 51 55 53 0.714 .

Yellow-poplar (Liriodendron tulipifera) 36 57 47 0.028 N

Chestnut oak (Quercus prinus) 55 39 47 0.074 S

Dogwood (Cornus florida) 39 52 46 0.157 .

Mockernut hickory (Carya tomentosa) 46 47 46 0.914 .

Pignut hickory (Carya glabra) 50 37 44 0.125 .

Shortleaf pine (Pinus echinata) 28 50 39 0.011 N

Post oak (Quercus stellata) 41 29 35 0.145 .

Eastern white pine (Pinus strobus) 16 40 28 0.001 N

Northern red oak (Quercus rubra) 28 26 27 0.739 .

Black cherry (Prunus serotina) 24 26 25 0.838 .

Southern red oak (Quercus falcata) 24 23 24 0.837 .

American holly (Ilex opaca) 28 17 23 0.102 S

Eastern hemlock (Tsuga canadensis) 16 24 20 0.190 .

Serviceberry (Amelanchier sp.) 15 22 19 0.228 .

a Latitude 36o

 arbitrarily divides the Cumberland Plateau ecoregion into southern (107 plots) and

northern zones (109 plots), approximately at Crossville, Tennessee.

b Chi-square probability that the frequencies of occurrence of individual species between the two

zones are not different from the expected frequency determined for the area as a whole.

c Multiple logistic regression probability (letter denotes P ≤ 0.05) that the presence of certain

combined significant species discriminates between the southern (S) and northern (N) zones of the

ecoregion.

Source: Griffith and others (1998).
93

4 adjacent ecoregions. In addition, five other indicator

species provided evidence of latitudinal differences in the

largest ecoregion. In conclusion, our study provides evidence

suggesting that the delineated ecoregions are discrete

ecological units that should not be combined. Also, we

demonstrated the potential value of indicator species for

purposes other than their conventional use for evaluation of

forest site quality.

LITERATURE CITED

Bailey, R.G. 1983. Delineation of ecosystem regions. Environmental

Management. 7: 365-373.

Bailey, R.G. 1998. Ecoregions. New York: Springer-Verlag. 176 p.

Beck, D.E.; Della-Bianca, L. 1981. Yellow-poplar: characteristics

and management. Agric. Handb. 583. Washington, DC: U.S.

Department of Agriculture, Forest Service. 91 p.

Bryce, S.A.; Omernik, J.M.; Larsen, D.P. 1999. Ecoregions: a geographic framework to guide risk characterization and ecosystem

management. Environmental Practice. 1: 141-155.

Golden, M.S. 1974. Forest vegetation and site relationships in the

central portion of the Great Smoky Mountains National Park.

Knoxville, TN: University of Tennessee. 275 p. Ph.D. dissertation.

Griffith, G.E.; Omernik, J.M.; Azevedo, S. 1998. Ecoregions of

Tennessee. Reston, VA: U.S. Geological Survey. 1: 940,000;

color poster with map, descriptive text, summary tables, and

photographs.

Griffith, G.E.; Omernik, J.M.; Azevedo, S.H. 1997. Ecoregions of

Tennessee. EPA/600R-97/022. Corvallis, OR: U.S. Environmental

Protection Agency (pp. 3, 18). 51 p.

Griffith, G.E.; Omernik, J.M.; Woods, A.J. 1999. Ecoregions, watersheds, basins, and HUCs: how State and Federal Agencies

frame water quality. Journal of Soil and Water Conservation.

54(4): 666-676.

Hansen, M.H.; Frieswyk, T.; Glover, J.F.; Kelly, J.F. 1992. The

Eastwide forest inventory data base: users manual. Gen. Tech.

Rep. NC-151. St. Paul, MN: U.S. Department of Agriculture,

Forest Service, North Central Forest Experiment Station. 56 p.

Hinkle, C.R. 1989. Forest communities of the Cumberland Plateau

of Tennessee. Journal of the Tennessee Academy of Science.

64(3): 123-129.

Hodgkins, E.J. 1961. Estimating site index for longleaf pine through

quantitative evaluation of associated vegetation. In: Proceedings

of Society of American Foresters Annual Meeting: 28-32.

Hosmer, D.W.; Lemeshow, S. 2000. Applied logistic regression. 2d

ed. New York: John Wiley. 373 p.

Kramer, P.J.; Kozlowski, T.T. 1960. Physiology of trees. New York:

McGraw-Hill. 642 p.

Kuchler, A.W. 1964. Potential natural vegetation of the conterminous

United States. Spec. Publ. 36. New York: American Geographical

Society. 116 p. + map, 1: 3,168,000.

McNab, W.H.; Lloyd, F.T.; Loftis, D.L. 2002. Preliminary evaluation

of methods for classifying forest site productivity based on

species composition in western North Carolina. In: Doruska,

P.F.; Bragg, D.C., eds. Proceedings of the southern mensurationists’ conference. Monticello, AR: Arkansas Forest Resources

Center: 10-18.

Omernik, J.M.; Chapman, S.S.; Lillie, R.A.; Dumke, R.T. 2000.

Ecoregions of Wisconsin. Transactions of the Wisconsin

Academy of Sciences, Arts and Letters. 88: 77-103.

Press, S.J.; Wilson, S. 1978. Choosing between logistic regression

and discriminant analysis. Journal of the American Statistical

Association. 73: 699-705.

Rudis, V.A. 1998. Regional forest resource assessment in an

ecological framework: the Southern United States. Natural

Areas Journal. 18: 319-332.

Schweitzer, C.J. 2000. Forest statistics for Tennessee’s plateau

counties, 1999. Resour. Bull. SRS-49. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southern Research

Station. 60 p.

Smalley, G.W. 1982. Classification and evaluation of forest sites in

the Mid-Cumberland Plateau. Gen. Tech. Rep. SO-38. New

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

Southern Forest Experiment Station. 58 p.

Smalley, G.W. 1983. Classification and evaluation of forest sites

on the Eastern Highland Rim and Pennyroyal. Gen. Tech. Rep.

SO-43. New Orleans: U.S. Department of Agriculture, Forest

Service, Southern Forest Experiment Station. 123 p.

Smalley, G.W. 1984. Classification and evaluation of forest sites in

the Cumberland Mountains. Gen. Tech. Rep. SO-50. New

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

Southern Forest Experiment Station. 84 p.

StataCorp. 2001. Stata statistical software. Release 7.0. College

Station, TX: Stata Corporation.

Whittaker, R.H. 1956. Vegetation of the Great Smoky Mountains.

Ecological Monographs. 26: 1-80.
94

INTRODUCTION

In most parts of the Central Hardwood Region, physical site

factors are important determinants of species composition,

site quality, and successional trends (e.g., Johnson and

others 2002, Nigh and others 2000, VanKley and others

1994). Although general trends in species composition

related to aspect, landforms, and soil conditions are readily

recognized by experienced resource managers, the magnitude of those differences and the variation in responses

across similar sites has not been well quantified.

The Missouri Ozark Forest Ecosystem Project (MOFEP) is

an on-going, centuries-long experiment that is evaluating

the effects of even-aged, uneven-aged, and no-harvest

management on a wide array of forest attributes, including

overstory and understory vegetation, wildlife populations,

mast production, insects, and fungi (Brookshire and Shifley

1997, Shifley and Brookshire 2000, Shifley and Kabrick

2002). An initial part of that experiment was the detailed

mapping of soils and landforms and the detailed inventory

of forest overstory and understory vegetation (Grabner

2000, Jensen 2000, Kabrick and others 2000, Shifley and

others 2000). This has afforded a unique opportunity to

examine the relationship of site factors to species composition across nearly 9,400 acres of mature, relatively

undisturbed, second-growth Ozark forest.

Grabner (2002) found that depth to dolomite, geology and

soil order (which together reflect major physical and chemical differences of soil parent materials in the study region),

slope aspect, and landform position were important site

factors for identifying and distinguishing different ecological

landtypes and landtype phases in the MOFEP study region.

These site factors affect the availability of light energy,

nutrients, and water. In this paper, we evaluate the relative

importance of each of these site factors for explaining

differences in oak species composition and growth relative

to other tree species and to forest site quality in Missouri

Ozark forests. Specific objectives were to (1) quantify the

composition and growth of oaks and other overstory species

in relation to the site factors of landform, aspect, depth to

dolomite bedrock, and parent materials, and (2) relate those

site factors to site index which has traditionally been used

to evaluate site quality in the region.

METHODS

MOFEP Site Description

The MOFEP study and experimental design is described

elsewhere in detail (Brookshire and Hauser 1993, Brookshire

and Shifley 1997, Kurzejeski and others 1993, Sheriff 2002,

Shifley and Brookshire 2000). The study consists of nine

sites ranging in size from 772 ac to 1,271 ac, primarily within

the Current River Oak Forest Breaks and the Current River

Oak-Pine Woodland Hills landtype associations of the Ozark

Highlands. The Current River Oak Forest Breaks has narrow

ridges and steep sideslopes with relief of 300-450 ft, which

exposes the Roubidoux, Gasconade, and Eminence formations. The Current River Oak-Pine Hills has broad ridges

with relief <300 ft and exposes only the Roubidoux and

Gasconade bedrock formations. Upland soils of these landtype associations are primarily Ultisols and Alfisols formed

in highly weathered hillslope sediments or residuum; soils

in upland waterways and bottomlands are primarily Ultisols

and Alfisols formed in gravelly alluvium (Kabrick and others

2000; Meinert and others 1997).

Vegetation Sampling and Site Index

Determinations

There are 648 permanent vegetation plots distributed

roughly equally among the nine MOFEP sites. Since 1991,

these permanent plots have been re-inventoried approximately every three years to document the condition of

woody vegetation. Within permanent plots, live and dead

trees ≥ 4.5 in. diameter at breast height (d.b.h.) are sampled

in 0.5-ac circular plots; trees between 1.5 and 4.5 in. d.b.h.

OAK FOREST COMPOSITION, SITE QUALITY, AND DYNAMICS IN RELATION

TO SITE FACTORS IN THE SOUTHEASTERN MISSOURI OZARKS

John M. Kabrick, Stephen R. Shifley, Randy G. Jensen,

David R. Larsen, and Jennifer K. Grabner1

1 Research Foresters, USDA Forest Service, North Central Research Station, Columbia, MO 65201; Resource Forester, Missouri Department

of Conservation, Ellington, MO, 63638; Associate Professor of Forestry, University of Missouri, Columbia, MO 65211; and Research Forester,

Missouri Department of Conservation, Columbia, MO 65201, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Physical site factors are known to affect forest species composition but the pattern and variation across forest

landscapes has not been well quantified. We discuss relationships between site factors including soil parent materials,

depth to dolomite bedrock, aspect, and landform position and the distribution of vegetation, site index, and short-term

succession in oak forests in the southeastern Missouri Ozarks. Overall, we found few strong relationships between these

site factors and tree species composition except black oak (Quercus velutina Lam.) was more abundant on summit and

shoulder landform positions. On average, site index was three to five ft. greater on backslopes than on summits and four

ft. greater on north-facing slopes than on south-facing slopes. In the absence of disturbance, white oak (Q. alba L.) was

generally succeeding species in the red oak group, especially on upper landforms.
95

are sampled in four 0.05-ac circular subplots; trees at least

3.3 ft tall and less than 1.5 in. d.b.h. are sampled in four

0.01-ac circular subplots nested within the 0.05-ac subplots.

Characteristics recorded for each tree include species, d.b.h.

or size class for trees < 1.5 in. d.b.h., and status (e.g., live,

dead, den, cut, blow-down). Plot and subplot data were

combined to obtain plot averages by d.b.h. or size class

and all values are converted to an acre basis for analysis.

From 1993 to 1996, site index was determined on suitable

trees at MOFEP. Trees considered suitable were canopy

codominants having good form with no indication that they

had been suppressed and showing the best growth potential. One to five candidate trees selected for site index

determination were sampled outside of the 0.5 ac permanent

vegetation plots but within 330 ft of vegetation plots. Tree

distance and azimuth from the geo-referenced vegetation

plot center were recorded for each site index tree and later

used to determine the latitude and longitude of each site

Figure 1—Illustration of hill cross section showing typical locations of bedrock geology, landforms, soil parent material, and soil depth

to bedrock. Definitions for landforms are included. See Methods for definitions of soil parent material, soil depth to bedrock, and

aspect classes.
96

index tree. Trees were assigned a ranking of their perceived

quality for indicating site index. Tree heights were measured

with clinometer to the nearest ft. A single increment core

was extracted at breast height and taken to the lab for age

determination. Site index was determined using species,

height, age at d.b.h., and published site index equations for

species in the Missouri Ozarks (McQuilkin 1974, 1978;

Nash 1963).

Soil and Site Characterization

A detailed landscape-scale soil mapping project was conducted on MOFEP in 1994-1995 (Kabrick and others 2000;

Meinert and others 1997). This included characterizing

geomorphology, geology, and soil characteristics of each

permanent MOFEP vegetation plot. Laboratory data

generated from 120 soil excavations was correlated to the

soil-landscape map units. Detailed information about the

soil-landscape mapping and soil characterization data can

be found in Kabrick and others (2000), Meinert and others

(1997), and data available through the Missouri Department

of Conservation.

Site Factors and Variables Used in this Study

We considered four site factors: landform position, parent

material, aspect, and depth to bedrock. Definitions of landforms follow those used for routine soil surveys and are

defined in figure 1. Soil parent materials were alluvium,

hillslope sediments (Daniels and Hammer 1992), and

hillslope sediments overlying residuum. At MOFEP, alluvium

contained 35 to 60 percent cherty gravel and/or cobbles,

clays having mixed mineralogy, cation exchange capacities

(CEC) of 2-22 cmol(+)kg-1, and base saturations (BS) of

2-60 percent. Hillslope sediments generally had 15-60

percent cherty gravel, kaolinitic mineralogy, CEC <20

cmol(+)kg-1, and BS of 5-55 percent. Residuum, primarily

from dolomite, had < 15 percent gravel, mixed or smectitic

mineralogy, CEC 5-40 cmol(+)kg-1, and BS of 30-100 percent. Aspect classes were protected (316-135 degrees),

and exposed (136-315 degrees). Site depths to bedrock

were classified as deep (>48 in. throughout), variable depth

(10-50 percent dolomite out crop; soil depth 0 to >48 in.), or

shallow (glades with >50 percent dolomite outcrop and soil

depth <48 in.).

To evaluate relationships between species composition and

site factors, we selected a subset of 310 MOFEP vegetation

plots that were each uniform with respect to site factors.

Because harvest treatments on MOFEP that began in 1996

reduced the number of undisturbed plots available, we

used data inventoried in 1994-1995, prior to implementing

harvest treatments, for our analysis. Response variables

included mean number of trees per acre and mean basal

area per acre for white oak, post oak, scarlet oak, black

oak, and for other oaks and tree species combined.

To evaluate site quality relationships, we used site index

estimates made from 289 white oaks and 706 black oaks.

These two species were selected because they were most

abundant site index tree species at MOFEP. Because site

index trees were located outside of the permanent vegetation plot boundaries, we identified site factors of each site

index tree by projecting the geo-referenced tree locations

onto the soil-landscape map with GIS software. We then

estimated individual site factors associated with each site

index tree using the soil-landscape information database.

To evaluate dynamics, we selected a subset of 210 MOFEP

vegetation plots that were each uniform in site factors and

had not been harvested or thinned during the period from

the first MOFEP inventory in 1991-1992 and the most recent

inventory completed in 2001-2002. We then calculated the

mean change in basal area of trees ≥ 4.5 in. d.b.h. from the

first to the most recent inventory. This was done for white

oak, post oak, scarlet oak, black oak, other oaks (combined),

and all other tree species (combined).

RESULTS

Oaks are the dominant trees at MOFEP (table 1). The four

most abundant oaks, black oak, scarlet oak, white oak, and

post oak, together comprise nearly 71 percent of the total

basal area. Chinkapin oak, blackjack oak, Shumard oak,

and northern red oak also occur, but together they comprise

1 percent of the basal area. Shortleaf pine, pignut hickory,

black hickory, mockernut hickory, blackgum, and flowering

dogwood are also abundant and important species of

Missouri Ozarks forests and woodlands.

We found few strong relationships between selected site

factors and tree species composition. Black oak basal area

was relatively greater on upper landforms than on lower

landforms, and both black oak and scarlet oak basal area

were greater on soils formed in hillslope sediments than on

soils formed in other parent materials (fig. 2). White oak

and post oak basal areas were slightly greater on benches

than on other landforms. Post oak basal area was slightly

greater on soils formed in alluvium than on soils in other

parent materials and on soils variable in depth to dolomite

than on deep soils or shallow soils. The basal area of “other

oaks,” of which chinkapin oak was most abundant, was

greatest on shallow soils.

White oak site index was approximately three ft. less than

black oak site index regardless of site factor (fig. 3), illustrating the well-documented height growth rate difference

between these two species (Carmean and others 1989).

White oak and black oak site index each were greater on

backslopes and less on summits. We also found the site

index for each species to be four ft. greater on protected

(316-135 degrees) aspects than on exposed (136-315

degrees) aspects. Site index was considerably lower on

shallow soils than on soils that were deep or variable in

depth to dolomite.

During the past decade, white oak basal area increased

considerably regardless of the site factors and increased

the most on benches (fig. 4). Post oak basal area also

increased, and relatively large net growth increases occurred

on both upper and lower landforms, in alluvium, and in soils

that were either variable in depth or shallow to dolomite

bedrock. Most notably, both scarlet oak and black oak basal

area decreased on summits and shoulders and black oak

basal area also decreased on benches. The category “other

oaks,” which is mostly composed of chinkapin oak, increased

primarily on sites having soils that were variable in depth or

shallow to dolomite bedrock. The basal areas of “other
97

Table 1—The 48 tree species observed on 648 MOFEP vegetation plots

Scientific name Common name Basal area Trees per acre

ft2/ac no.

Quercus velutina Lam. Black oak 23.2 58

Q. coccinea Muenchh. Scarlet oak 20.3 49

Quercus alba L. White oak 19.6 130

Pinus echinata Mill. Shortleaf pine 8.0 21

Quercus stellata Wangenh. Post oak 5.8 22

Carya glabra (Mill.) Sweet Pignut hickory 3.8 49

C. texana Buckl. Black hickory 3.6 44

C. tomentosa Poir. Nutt. Mockernut hickory 3.4 56

Cornus florida L. Flowering dogwood 3.2 349

Nyssa sylvatica Marsh. Blackgum 2.3 86

Quercus muehlenbergii Engelm. Chinkapin oak 0.6 5

Q. marilandica Muenchh. Blackjack oak 0.5 3

Acer rubrum L. Red maple 0.4 54

Sassafras albidum (Nutt.) Nees Sassafras 0.4 104

Juglans nigra L. Black walnut 0.3 1

Ulmus rubra Muhl. Slippery elm 0.3 20

U. alata Michx. Winged elm 0.3 19

Fraxinus americana L. White ash 0.2 18

Juniperus virginiana L. Red cedar 0.1 3

Acer saccharum Marsh. Sugar maple 0.1 3

Quercus shumardii Buckl. Shumard oak 0.1 1

Q. rubra L. Northern red oak 0.1 < 1

Carya cordiformis (Wangenh.) K. Koch Bitternut hickory 0.1 1

Ulmus americana L. American elm 0.1 4

Rhamnus caroliniana Walt. Carolina buckthorn 0.1 36

Cercis canadensis L. Redbud 0.1 16

Morus rubra L. Red mulberry < 0.01 4

Diospyros virginiana L. Persimmon < 0.01 6

Amelanchier arborea (Michx. f.) Fern. Serviceberry < 0.01 7

Crataegus spp. Hawthorn < 0.01 4

Prunus serotina Ehrh. Black cherry < 0.01 5

Bumelia lanuginosa (Michx.) Pers. Gum bumelia < 0.01 3

Carya ovata (Mill.) K. Koch Shagbark hickory < 0.01 < 1

Celtis occidentalis L. Hackberry < 0.01 9

Viburnum rufidulum Raf. Rusty black haw < 0.01 7

Fraxinus pennsylvanica Marsh. Green ash < 0.01 2

Carpinus caroliniana Walt. Hornbeam < 0.01 3

Gleditsia triacanthos L. Honey locust < 0.01 < 1

Prunus americana Ehrh. Wild plum < 0.01 1

Ostrya virginiana (Mill.) K. Koch Ironwood < 0.01 < 1

Asimina triloba (L.) Dunal Pawpaw < 0.01 8

Rhus copallina L. Winged sumac < 0.01 1

Celtis laevigata Willd. Sugarberry < 0.01 1

C. tenuifolia Nutt. Dwark hackberry < 0.01 2

Rhus glabra L. Smooth sumac < 0.01 1

Elaeagnus umbellata Thunb. Autumn olive < 0.01 < 1

Robinia pseudoacacia L. Black locust < 0.01 < 1

Staphylea trifolia L. Bladdernut < 0.01 < 1

species,” mostly comprised of shortleaf pine, and the three

most common hickories, increased regardless of site

factors.

DISCUSSION

Oaks are the most dominant genera of trees in our study

area and comprise most of the basal area regardless of

landform, soil parent materials, aspect classes, and depths

to and extent of dolomite bedrock. This differs from mesophytic forests of the Central Hardwood Region found north

and east of the Missouri Ozarks where oaks are components

of more diverse forests and where oaks are often restricted

to drier sites such as on ridge tops and south-facing slopes

(Johnson and others 2002). This suggests that the condi-
98

Figure 2—Proportion of mean basal area by species group and (A) landform, (B) soil parent material,

(C) soil depth to bedrock, and (D) aspect.

Figure 3—Mean site index (age 50) for white oak and black oak by (A) landform, (B) soil parent material,

(C) soil depth to bedrock, and (D) aspect. There were no black oak site index trees on shallow soils,

panel (C).
99

Figure 4—Mean net basal area growth (ft2 ac-1 decade-1) by species group and (A) landform, (B) soil parent material, (C) soil

depth to bedrock, and (D) aspect for trees ≥ 4.5 in. diameter at breast height.
100

tions of our study area are generally drier, and therefore

they restrict development of many of the mesic species that

are abundant elsewhere in the Central Hardwoods Region.

Moreover, oaks are adapted to fire (Guyette and Dey, 1997;

Johnson and others 2001), an important disturbance throughout the Ozarks for hundreds of years prior to extensive fire

suppression efforts beginning around 1940 (Batek and others

1999, Guyette and Dey 1997). Most evidence suggests that

fire in the pre-European landscape also maintained a more

open woodland structure in our study region rather than the

closed-canopy forests present today (Batek and others

1999).

In our analysis, the species composition differences related

to site factors were subtle. The most prominent relationships

were that black oaks were more abundant on drier landforms

such as summits and shoulders than on other landforms

and both black oaks and scarlet oaks were more abundant

in soil parent materials having a low water holding capacity

and low nutrient supply than in other soil parent materials.

Evidence from remnant stumps indicates that in the preEuropean landscape, shortleaf pines were once much more

prominent on these drier and nutrient-poor sites than they

are today (Guyette and Dey 1997). Guyette and Dey (1997)

attribute relatively low abundance of shortleaf pine in these

sites today to the extensive pine harvesting during the late

1800’s and early 1900’s followed by frequent burning. It

appears that black oaks, and to some degree scarlet oaks

are now most abundant in sites that historically supported

more shortleaf pines.

Both black oaks and scarlet oaks are susceptible to decline

as they mature, particularly on droughty, nutrient-poor sites

(Johnson and others 2002). At MOFEP, most of the black

oak and scarlet oak basal area is from older, large-diameter

trees. Our data show that black oaks on all sites had a net

growth loss due to high mortality and both black oak and

scarlet oak net growth losses were particularly great on

summits and shoulders. On undisturbed sites, white oaks

appear to be replacing black oaks and scarlet oaks and are

increasing in basal area regardless of the site factors.

Compared to black oaks and scarlet oaks, white oaks are

more shade tolerant, live longer, and are less susceptible to

oak decline. Consequently, white oaks had a greater ingrowth rate and lower mortality rate than either black oaks

or scarlet oaks. Post oaks are also increasing in dominance,

but at a much slower rate because of their slow growth rate

and because their shade intolerance limits their regeneration

in the absence of disturbances. Much like white oaks, post

oaks are long lived and not considered very susceptible to

decline. Relatively large net growth increases by post oaks

occurred where post oaks were particularly abundant such

as on both upper and lower landform positions, in alluvium,

and in variable depth and shallow soils. Of the common,

“other species,” shortleaf pine, pignut hickory, black hickory,

and mockernut hickory had the greatest net basal area

increases, largely due to moderate growth rates of residual

trees and low mortality rates during the sampling period

(data not shown).

Site quality, as determined by site index, was more closely

related to site factors than was species composition. Landform position and aspect were the two most important factors

followed by depth to or extent of dolomite bedrock and soil

parent materials. Specifically, our data suggest that the highest site indices for both white oaks and black oaks occurred

on protected backslopes where soils were deep and were

formed in hillslope sediments overlying residuum. These

particular site factors thus indicate where water and nutrients

are more available and where rooting volume is greater.

It is important to recognize that the four site factors evaluated in our study are not completely independent of one

another. For example, soils that are shallow to bedrock

occur more frequently on exposed aspects, and alluvium is

found nearly exclusively in floodplains. Clearly, these site

factors must be used in combination as is the practice in

ecological classification schemes such as the one that

Grabner (2002) developed for the MOFEP study area. Our

analysis quantified relationships among the composition,

site quality, and growth of oaks and other trees species,

and site factors most important for identifying and distinguishing ecological land types and phases in the southeastern Missouri Ozarks.

ACKNOWLEDGMENTS

We thank the dozens of technicians who sampled woody

vegetation on MOFEP during the past decade as well as all

of the scientists and Missouri Department of Conservation

staff who have made conducting MOFEP possible. We also

thank Doyle Henken of the Mark Twain National Forest and

Dr. Eric Zenner of the University of Minnesota for reviewing

an earlier draft of this manuscript.

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Batek, M.J.; Robertus, A.J.; Schroeder, W.A. [and others], 1999.

Reconstruction of early nineteenth-century vegetation and

fire regimes in the Missouri Ozarks. Journal of Biography,

26: 397-412.

Brookshire, B.L.; Hauser, C.H. 1993. The Missouri Ozark Forest

Ecosystem Project: the effects of forest management on the

forest ecosystem. In: Gillespie, A.R.; Parker, G.R.; Pope, P.E.;

Rink, G. R., editors. Proceedings of the 9th central hardwood

forest conference. Gen. Tech. Rep. NC-161. St. Paul, MN: U.S.

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land classification in the southeast Missouri Ozarks. University

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102

INTRODUCTION

Enaphalodes rufulus (Haldeman) Coleoptera: Cerambycidae,

(red oak borer) is a wood boring insect that occurs throughout a wide range of deciduous forests in North America

(Donley and Acciavatti 1980). In the past, damage associated

with this insect has resulted in log degrade and overall

decrease in wood quality. Recently very high population

levels of the red oak borer have coincided with oak decline

sites, and although not a primary mortality agent, it is clear

that an abundance of red oak borer damage occurs in oak

dominated forests with high tree mortality. Many explanations

have been invoked to explain recent and unprecedented

outbreaks of E. rufulus in the Ozark Highlands of Missouri

and Arkansas. Among these, the abundance and age of

host tree species, principally Quercus species (oaks), may

provide an explanation. It is more likely, however, that the

outbreaks are a result of host abundance coupled with the

potential effect of climate on the development of E. rufulus.

Historically, borer populations may have been limited by the

sporadic occurrence and mixed age distribution of host tree

species in the Missouri Ozarks. Forest harvesting regimes

(ca. 1900), however, have resulted in extensive tracts of

even-aged forests consisting predominantly of host species,

namely Quercus sect. Lobatae (red or black oaks). On many

sites these tree species have replaced shortleaf pine (Pinus

echinata). A complete understanding of oak decline and

specifically red oak borer abundance is lacking; in particular

the relationship of red oak borer and site, climate, stand

history has yet to be clarified. There is a need to understand

tree, forest, and environmental conditions that influence

such outbreaks.

Dendrochronology has been used often in entomology

research to evaluate the frequency and timing of defoliator

outbreaks (e.g., Fritts and Swetnam 1989, Swetnam and

Lynch 1993), or the influence of defoliators on growth loss

(Muzika and Liebhold 1999). The use of dendrochronology

to examine wood boring insects, however, is relatively

uncommon. Notable exceptions include a study by McManus

and Giese (1968) that revealed that precipitation, temperature and flooding, were positively related to population

fluctuations of the Columbian timber beetle (Corthylus

columbianus Hopkins). Cambium mining insects (Diptera:

Agromyzidae) create scars, sometimes referred to as pitch

flecks, and have been used to evaluate population dynamics

over a period of several decades (Schimitschek 1935, Ylioja

and others 1999).

For this study, our primary goal was to document historic red

oak borer occurrences as a way to examine the presence

and abundance of red oak borer relative to a variety of

abiotic factors. The intent is to begin to decipher the components of oak decline. Specifically, we examined the

response of oak borers to climate, tree growth, tree age and

stand age. We used dendrochronologically-dated xylem

wounds made by oak borer larvae to construct borer activity

chronologies at an oak decline site in the Missouri Ozarks.

METHODS

The study area was located in the Mark Twain National

Forest, approximately 5 km east of Bixby, Missouri. The

stand was a designated salvage site where most of the trees

were to be removed soon after our study was complete.

The 70-year old stand was dominated by scarlet oak and

black oak. We established two 20 m belt transects and

sampled each scarlet and black oak that fell within the

transects. Thirty-one trees were sampled. Each sampled

tree was felled and cut into one meter intervals, beginning

at 1 m.

In the lab cross sections were prepared by sanding. Annual

tree growth increments were cross-dated (Stokes and Smiley

1986) and tree stem initiation dates determined. Injuries

were identified as borer damage by the wound configuration and characteristics (size, xylem wound shape, holes in

bark, excelsior fibers), the presence of borer tunnels and

tunnel stain traces, and infrequently, the occurrence of live

larvae in tunnels. Although all borer wounds can be dated,

not all borer tunnels on a cross-section are datable. The

dimensions of each dated wound were measured and used

as confirmation and stratification of wounds. These include:

tangential extent of callus tissue and cambial death, the

radial extent of callus tissue, presence/absence of tunnels,

tunnel width and length. Borer wounds from all thirty-one

A DENDROCHRONOLOGICAL ANALYISIS OF RED OAK BORER ABUNDANCE

Rose-Marie Muzika and Richard P. Guyette1

1 Associate Professor and Research Associate Professor, Department of Forestry, University of Missouri, Columbia, MO, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Unprecedented outbreaks of red oak borer (Enaphalodes rufulus Haldemann) have occurred in the lower

Midwestern United States. Although generally not a mortality agent, red oak borer appears to contribute to general oak

decline and mortality. The objective of this project was to explore dendrochronology as a means of determining the role of

tree age, tree growth and climate in long-term red oak borer activity and to quantify the historic importance of red oak

borer. In a Quercus (oak) dominated forest in Missouri, 31 oak trees were sampled and dendrochronological methods

used to develop a red oak borer chronology. Borer activity in the stand has increased over the past 70 years with large

increases occurring over the last 25 years. The abundance of wounds was related to tree age, ring width, annual mean

temperature, and annual mean minimum temperature. Red oak borer wound abundance was not related to tree basal

area increment, mean maximum temperature nor precipitation.
103

trees were then compiled into a frequency distribution with

annual resolution. Specifically, this oak borer chronology

represents a time series of oak borer activity as preserved

in the tree-ring record by the larval scarring of the cambium.

Radial growth chronologies of sampled trees were constructed in order to examine the relationships between

borer activity and tree growth. Growth chronologies were

calculated as raw ring-width (mm) and annual basal area

increment (cm2) was constructed. Basal area chronologies

were used to assess tree growth and vigor while ring-width

chronologies were used as an indirect estimate of change

in wood density. Correlation analysis was used to determine the strength of relationship between red oak borer

abundance and several stand and climate variables.

RESULTS

We tree-ring dated a total of 743 oak borer wounds on the

31 trees that grew in a declining oak forest in southeastern

Missouri. From these data we developed a red oak borer

chronology that described the levels of larval activity for a

period extending more than 60 years (fig. 1). The red oak

borer has a synchronized two-year life cycle (Solomon

1995). The predominance of wounds (89 percent) occurred

biennially, supporting our supposition that red oak borer

caused most cambial injuries.

Borer wounds increased abruptly during the late 1970’s and

remained at high levels to such an extent that red oak borer

abundance was consistently greater than at any time since

stand initiation in 1935 (fig. 1). The dramatic increase in red

oak borer wounds occurred at a stand age of approximately

50 years.

Figure 1—An annual frequency distribution of larval borer wounds dated on 137

cross sections from 31 oak trees near Bixby, MO.

Table 1—Correlation coefficients for the relationship between growth

variables and tree-ring dated borer wounds

Growth variables All dated wounds Dated wounds/tunnels

Mean ring-width -0.47** -0.43**

[ln] ring-width -0.51** -0.47**

Basal area increment 0.17* 0.15*

Forest stand age 0.50** 0.46**

* = p < 0.05; ** = p < 0.01.

Dated wounds/tunnels are wounds that were associated with characteristic red oak

borer tunnels. Mean ring-width is the raw nonstandardized width of the rings. Analysis

includes all years of record (1920–2000).

Calendar year

1940 1950 1960 1970 1980 1990 2000

Borer wounds / cross-section

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

15 25 35 45 55 65 75

Stand age
104

We examined the correlations between growth variables and

red oak borer activity. Correlations were performed on all

dated wounds, as well as only those wounds that co-occurred

with tunnels. The latter category of wounds represents a

more conservative estimate of red oak borer activity. Basal

area increment was not significantly related to the frequency

of borer wounds (table 1), but mean ring-width and logarithmic transformed ring-width were both inversely related to

red oak borer abundance, and forest stand age was positively related to red oak borer abundance.

Annual mean temperature and annual mean minimum

temperature were positively related to red oak borer activity

(table 2). Neither annual mean maximum temperature nor

annual total precipitation was significantly related to red

oak borer activity. Results were similar whether all dated

wounds were used or dated wound with tunnels only.

DISCUSSION

These data indicate that the large increases in the frequency

of borer wounds occurred in the mid to late 1970s (fig.1)

despite the fact that this wood boring beetle has gained

attention only during the late 1990’s. Furthermore, red oak

borer wounds did not correlate with basal area increment,

an index that quantifies the amount of basal area that

accrues on a tree or in a forest, i.e. the cross sectional area

of wood produced by the tree annually. The lack of a relationship indicates that red oak borer outbreaks are not

simply related to decreases in tree vigor. There was an

inverse association between mean ring-width and increases

in wound frequency (table 1). This association may be

related to several direct and indirect factors such as reductions in wood density. Although outbreaks of red oak borer

are associated with stressed trees that eventually succumb,

these data suggest that individual trees and entire stands

can support substantial populations of red oak borer for

decades before the stand exhibits signs of decline.

Correlation analyses indicate that temperature, ring width,

and stand age were most strongly related to the frequency

of borer attacks. Minimum temperature was most strongly

related to the frequency of red oak borer wounds (table 2).

The effect of temperature on red oak borers is corroborated

by previous laboratory experiments that found increases in

Table 2—Correlation coefficients for the relationship between climate variables

and tree-ring dated borer wounds

Climate variables All dated wounds Dated wounds/tunnels

Annual mean temperature -0.49* -0.56**

Annual mean max temperature -0.22* -0.12**

Annual mean min temperature - 0.54* -0.59**

Annual total precipitation -0.18* -0.06

** = p < 0.05; ** = p < 0.01.

Dated wounds/tunnels are wounds that were associated with characteristic red oak borer

tunnels. Analysis is for even calendar years only during the period of recent red oak borer

abundance (1956–2000). Even years are the years of synchronous red oak borer larval injury to

the cambium.

temperature (21.1 to 32.2 oC) were positively related to the

survival and fecundity of laboratory reared red oak borer

(Galford 1974). We found no significant relationships

between precipitation (table 2) and borer activity, despite

the purported influence of drought on reduction in tree

resistance.

Climatic factors can strongly influence insect populations,

and substantial evidence exists to demonstrate how fecundity, survival, and dispersal are affected by temperature,

precipitation, wind or humidity. Over long time periods, rainfall has been the most consistent predictor of insect populations, at least defoliators (Swetnam and Lynch 1993). Our

data suggests that although drought may play a role in

general oak decline, there seems to be no relation between

precipitation at our study sites and red oak borer abundance.

Considering the potential implication of climate change and

red oak borer, among other insects (Williams and Liebhold

2002), it is critical to examine trends in temperature in order

to develop predictions. Although the magnitude of increase

in mean temperatures has been modest, change in mean

minimum temperature has been much larger. In the region

of the case study, minimum temperatures have increased

about 2.8 o

F since the 1960s. Minimum temperatures could

be most limiting to borer development, growth, reproduction, and fecundity (Galford 1974).

Whole wood density and ring-width have been shown to be

strongly related in ring-porous angiosperms (Panshin and

Zeeuw 1970). Large-diameter vessel elements that occur

only in earlywood have large empty lumens that make the

earlywood less dense. Since earlywood width tends to be

consistent among rings, irrespective of total width; proportionally, more earlywood (low-density) occurs in narrow

rings. Since ring width size is negatively related to red oak

borer wounds, wood density could be a direct and important variable concerning the temporal, spatial, and stem

distribution of larval wounds. Wood density might reflect

host quality from both a physical and chemical perspective.

As density decreases the proportion of early wood within

rings increases as does the proportion of readily hydrolyzed

hemicellulose (Wu and McGinnes 1974). Further research

may explain the significance of this factor.
105

CONCLUSIONS

Our research has provided insight into the evaluation of

historical abundance of red oak borer and of factors controlling its activity. Oak borer wound chronologies offer us a

new tool. The sectioning of trees and dating of wounds

provides data on insect larval populations in an exact location for from 50 to 150 years. The data compiled is high

resolution (tree wounds dated to the year), relatively longterm (many generations of insects), and abundant (many

single trees have over one hundred borer wounds). This

type of research will greatly improve our ability to sample

and interpret both short and long-term changes in the

abundance of wood boring insects and decipher basic

biological limitations on insects.

This research represents a case study providing some indication about the factors that influence red oak borer activity

and consequently oak decline. Further research will provide

greater information about these and other factors that may

ultimately assist in developing predictive models and influence management activity.

LITERATURE CITED

Donley, D.E.; Acciavatti, R.E. 1980. Red oak borer. Forest Insect

and Disease Leaflet 163. USDA Forest Service.

Fritts, H.C.; Swetnam, T.W. 1989. Dendroecology: a tool for evaluating variations in past and present forest environments.

Advances in Ecological Research 19: 111-188.

Galford, J.R. 1974. Some physiological effects of temperature

on artificially reared red oak borers. Journal of Economic

Entomology 67: 709-710.

McManus, M.L.; Giese, R.L. 1968. The Columbian timber beetle,

Corthylus columbianus. VII. The effects of climatic integrants

on historic density fluctuations. Forest Science. 14(3) 242-253.

Muzika, R.M.; Liebhold, A.M. 1999. Changes in radial increment in

host and non-host tree species with gypsy moth defoliation.

Canadian Journal of Forest Research 29: 1365-1373.

Panshin, A.J.; Zeeuw, C. 1970. Textbook of wood technology. New

York: McGraw-Hill Book Company. 705 p.

Schimitschek, E. 1935. Dendromyza-Larven als Korbweidenschadlinge. Lehrkanzel fur Forstentomologie und Forstschutz,

Hochschule fur Bodenkultur, Wien 15: 123-126.

Solomon, J.D. 1995. Guide to insect borers of North American

broadleaf trees and shrubs. Washington DC: U.S. Department

of Agriculture, Forest Service, Agriculture Handbook 706.

Stokes, M.A.; Smiley, T.L. 1986. Introduction to tree-ring dating.

Chicago: University of Chicago Press. 78 p.

Swetnam, T.W.; Lynch, A.M. 1993. Multicentury, regional –scale

patterns of western spruce budworms outbreaks. Ecological

Monographs 63: 399-424.

Williams, D.W.; Liebhold, A.M. 2002. Climate change and the outbreak ranges of two North American bark beetles. Agricultural

and Forest Entomology 4: 87-99.

Wu, K.Y.; McGinnes, E.A. 1974. Intra-incremental studies of methylation in scarlet oak. Wood Science 7: 92-98.

Ylioja, T.; Roininen, H.; Ayres, M.P. [and others]. 1999. Host-driven

population dynamics in an herbivorous insect. Proceedings of

the National Academy of Sciences 96: 10735-10740.
106

HISTORY

Around 10,000 BC or even earlier, the first humans arrived

in North America. Here they found several species of megafauna and beech-maple forests. By about 5,000 BC the

megafauna had disappeared and the climate had become

warmer and drier. Oak-Hickory forests dominated the lower

eastern United States on upland sites, with Pine-Hardwood

forests prominent in the deep South. The influence of the

natives in North America grew, and accounts of early French

explorers in the 1500s chronicled substantial populations

and influence on the land by natives. But later accounts by

Spanish explorers in the 1700s painted quite a different

picture. Apparently there had been widespread demise of

the natives, attributed to diseases contracted from the

earlier explorers. A substantially reduced human population

had lessened effect on the forest and there was widespread

development of old-growth forests.

Accounts of the earliest naturalists in the 1700s such as

William Bartram (Van Doren 1928) tell of vast old-growth

forests with large trees, snags, and down material. But he

also describes prairies and grass-forb habitat with associated species, such as indigo buntings and yellow-breasted

chats, and game species such as the wild turkey, white-tailed

deer, and elk; each of which depend on early successional

habitat during some stage of their life cycle. A forest savannah

condition with sparse overstory and grassy ground cover

probably was widespread in the lower South, but also apparently prevalent in some mountain systems, such as the

Ouachitas as recounted by Bukenhofer and Hedrick (1997).

But the old growth forests of the 1700s and its associated

wildlife would soon face the onslaught of European colonizers who rapidly changed the landscape. As natives were

overcome or evicted, new settlers colonized the eastern

North American hardwood forests. They cleared new ground

to make way for their crops, and felled trees for wood to

heat their homes and build their houses and barns. The

vast forests of the East fell to the axe and saw.

In the late 1800s and early 1900s the wholesale clearing of

the forest and the direct harvest of many species of animals

were profound. There was little thought of or provision for

the future, nor concept of conservation. Game animals were

taken at will to feed the settlers’ burgeoning families, and

predators were regarded as competitors or threats and

shot. A few species, such as the Carolina parakeet and

passenger pigeon, were lost forever and other species

suffered. The relatively remote eastern mountains functioned

somewhat as refuges for a few impacted species, such as

black bears and wild turkeys.

Recovery of the forests in some fashion began in early

1900s. Southeastern mountains were less fertile than

prairies or bottomland, and were less populated by humans.

Consequently, a higher portion of these mountainous regions

was included in the National Forests. Later, cutover forest

land and crop land were abandoned and regenerated to

forest. And even later, wildlife management had its beginnings. The first efforts were directed toward game species

whose populations were precariously low.

In recent years, oak forests of the U.S. have aged and

increased in extent. The broad category of upland hardwood forests of the South increased from 65 to 75 million

acres from 1952 to 1996 (Sheffield and Dickson 1998). And

many stands are even-aged, having regenerated at about

the same time.

DYNAMIC NATURE

The oak forests of the eastern U.S. have always been

diverse as well as dynamic; having been continually molded

and influenced by a variety of natural and anthropogenic

forces. Fire, windstorms, diseases, and insects have played

a major role in what the forests were and how they functioned. The natives, and even more so the early settlers,

added to these forces, compounding the effects. One

wholesale change illustrates. The American chestnut was

once a dominant tree of eastern Appalachian hardwood

WILDLIFE AND UPLAND OAK FORESTS

James G. Dickson1

1

 Merritt Professor of Forestry, Louisiana Tech University, Ruston, LA 71272.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—The oak forests of the eastern U.S. have always been diverse as well as dynamic; continually molded and

influenced by a variety of natural and anthropogenic forces. These forests support thousands of species of plants, untold

numbers of insects and other invertebrates, and hundreds of species of vertebrate wildlife. Because of the large number

of species, I focus on species and communities of special interest or concern. Acorns are a primary fall and winter diet

item of many vertebrate species. Acorns build energy reserves, which are very important for winter survival and successful reproduction for a number of species. The wild turkey, white-tailed deer, and American black bear, which suffered and

were very limited a century ago, have been restored and now flourish. There are a wide variety of bird species associated

with upland oak forests; most associated with specific habitat attributes. Generally, there is concern for two categories of

birds: neartic-neotropical migratory birds, and early successional, grass-forb associated birds. Bats are important

ecological components of oak forests; several species of cave bats are endangered and there is concern for others. Even

though upland oak ecosystems are mostly xeric, the forests support a high diversity of reptile and amphibian species, and

provide important habitat for many species.
107

forests. But the chestnut blight in the early 1900s eliminated mature forms of American chestnut from the landscape. So what once was an oak-chestnut forest became

an oak-hickory forest.

Today, the dynamic nature and changes continue. For

example, demise of older oak stands is being wrought by

the gypsy moth in the Appalachians and the red oak borer

in the Ozarks. Influences on the forests are exacerbated by

the increased number of humans and their associated technology. Large scale damming of rivers, wholesale land use

changes, and pesticides serve as examples.

WILDLIFE

Upland oak forests of the U.S. support thousands of species

of plants, untold numbers of insects and other invertebrates,

and hundreds of species of vertebrate wildlife. Wildlife communities have evolved over thousands of years with the

forests and have been molded by the dynamic nature of the

forests. A few species, such as the Carolina parakeet, have

been lost. Premier game species, such as the white-tailed

deer and wild turkey, have been restored. While the status

of others, such as the myriad reptiles and amphibians,

remain generally unknown.

Acorns

Obviously, one of the most prominent characteristics of oak

forests in relation to wildlife is the acorns they produce.

Acorns are a primary fall and winter diet item of many vertebrate species, as well as insects. Some examples of the

variety of species which consume acorns include: passerine

birds- such as blue jays, woodpeckers- red-headed and

red-bellied, waterfowl-wood ducks (even on upland sites),

squirrels- gray, fox, and southern flying, small terrestrial

rodents- such as wood rats and Peromyscus, raccoons,

wild hogs, and high profile species: black bear, white-tailed

deer, wild turkey, and northern bobwhite.

Oak acorns have relatively low levels of protein and phosphorus (Short and Epps 1976), but with a high lipid content

they provide an important energy source to animals. Acorns

build energy reserves, which are very important for winter

survival and successful reproduction for a number of species.

An important feature of oak mast production in regard to

the ecology of the forest and its wildlife communities is the

extreme variability in annual production. For example, in a

19-year study in the Ozark Mountains of Arkansas, annual

acorn production fluctuated drastically in all four vegetation

types (Dickson 1990). In each forest type there was very

little or no production in 5 of the 19 years. There was no

production in the cedar glades or streambottom oak type,

less than 10 kg/ha in the pine-oak type, and less than 22

kg/ha in the upland oak type. Conversely, mast production

was profuse (>120 kg/ha) in 7 of the 19 years in the upland

oak type and 9 of 19 years in the pine-oak type.

In that myriad species consume acorns, this phenomenon

of erratic acorn production helps insure regeneration of oak

forests during years when the ample acorn supply surpasses

the collective demands of species that consume acorns.

But this extreme variability in annual production is tough on

the wildlife that depends on mast.

The importance of acorns to species and its’ effects on their

population viability is demonstrated by data from studies of

several different species. During boom years life is good;

but in bust years there is extreme competition for acorns

and wildlife suffers. For example in an oak dominated Ozark

forest, annual acorn production was critical to deer herd

health and productivity (Rogers and others 1990). During

years of low acorn production, winter survival of deer was

lower and fawn survival the subsequent spring also was

lower than that of years of moderate to high production.

Mast from oaks also is very important to black bears. In the

southern Appalachians, oak mast, primarily white oak, has

a significant impact on bears in terms of natality, mortality,

and movements (Pelton 1991). The birth and survival of

young bears were directly associated with oak mast crops.

Acorns are also very important to some species of rodents.

For example, populations of white-footed mice declined

with acorn failures and increased with acorn supplementation (Jones and others 1998).

Oak forests are important habitat for wild hogs (Dickson and

others 2001). For example, in the Appalachians Eurasian

wild hogs used mixed oak stands more than expected during

years of high mast production, but not when little mast was

available (Singer and others 1981); and a similar habitat

use pattern was observed in bottomland hardwoods in

South Carolina (Kurz and Marchinton 1972). Acorns are a

preferred food item and hogs are efficient foragers. During

years of minimal acorn production, wild hog consumption of

acorns probablynegatively affects native mast-consuming

species.

Turkeys, deer, and bear

The wild turkey, white-tailed deer, and American black bear

suffered, and experienced population lows during the era of

exploitation in the 1800s and early 1900s. But they have

been restored, and populations have increased dramatically in recent decades (fig. 1).

Traditional and optimum habitat for the wild turkey is oak

forests in conjunction with other associated land uses (see

Dickson 1992). These forests and the mast they produce

provide optimum fall and winter habitat, and are used

extensively. Associated forest ground and shrub vegetation,

openings, and agriculture pastures and crop land provide

strutting grounds, nesting sites, and appropriate brood

habitat.

Wild turkeys have persisted in oak forests historically.

Recently, due to maturing of the forests, better protection,

and trapping and transplanting, populations have prospered,

and now thrive throughout southern oak forests (fig. 1) and

elsewhere. Population estimates nationwide now surpass

5 million.

White-tailed deer are distributed throughout and thrive today

in upland oak forests where their dietary needs of browse,

forbs, fungi, and soft and hard mast are met. Populations

today are found in every county in the Southeast (fig. 1).

Although soils are not as productive in mountainous oak

forests as in some other types and they are not optimum
108
109
110

Figure 1—Relative densities of wild turkeys, white-tailed deer, and American black bear for 1970 and 1996 by county in the

Southeast. Density categories are: turkey-low <6, med 6-15, high >15 per sq mi; deer- low <15, med 15-30, high >30 per sq

mi; bear-low <1 per 1,500 ac, med- 1 per 1,500-1 per 1,000 ac, high >1 per 1,000 ac (from Dickson 2001).
111

deer habitat, they still remain heavily forested and whitetailed deer fare well there. Also, the white-tailed deer has

proven highly adaptable, and thrives where oak forests are

interspersed with agriculture crops or even suburbs.

Black bears require large areas of suitable habitat with little

human interaction, secure corridors for movements, some

very thick understory habitat, and rocky outcrops or large

hollow trees for denning (Pelton 2001). As with the wild

turkey and white-tailed deer, the American black bear

suffered substantially earlier from habitat loss and direct

harvest. The last refuges were remote areas, such as

swamps and mountains. Populations persisted and recently,

numbers have increased and populations are viable in

mountainous eastern oak forests- the Appalachians and

Ozark/Ouachitas (fig. 1).

Birds

Some upland oak forests, such as the southern Ridge and

Valley and Interior Low Plateau are heavily fragmented.

Conversely the oak forests of the Ozarks and southern

Appalachians are substantial in distribution and remain

Table 1—Abundance of nearctic-neotropical migratory birds in central

hardwood forests

Stand age

Species R S P M G T

Whip-poor-will U U U U U U

Ruby-throated hummingbird C N N N ? N

Acadian flycatcher N N C A N A

Eastern wood-pewee N N U A N A

Eastern phoebe N N U U N U

Great-crested flycatcher C C C C C C

Blue jay C C C C C C

American crow U U U U U U

Carolina wren C C U N ? ?

Blue-gray gnatcatcher A C C C C C

Eastern bluebird C N N N N N

Wood thrush U C C C U C

Gray catbird C C N N ? N

White-eyed vireo C C N N ? N

Yellow-throated vireo N N N U N U

Red-eyed vireo U U A A U A

Blue-winged warbler A C N N ? N

Golden-winged warbler C U N N ? N

Northern parula N N U C N C

Chestnut-sided warbler C C N N ? N

Yellow-throated warbler N N U U N U

Pine warbler N N C C N C

Prairie warbler A C N N ? N

Black-and-white-warbler C C C C C C

Worm-eating warbler U C C C C C

Ovenbird U C C C U U

Louisiana waterthrush N U C C C C

Common yellowthroat A U N N ? N

Kentucky warbler A C U U A C

Hooded warbler C C U U C C

Yellow-breasted chat A C N N ? N

Orchard oriole U N N N N N

Summer tanager C C C A C C

Scarlet tanager U U C A U A

Indigo bunting A C U U A C

Eastern towhee A U N N C N

Field sparrow A N N N ? N

Brown-headed cowbird A C C C C C

American goldfinch U N N N N N

R = regeneration; S = sapling; P = poletimber; M = mature; G = group selection;

T = single tree selection; A = abundant; C = common or regular; U = uncommon;

N = not present.

Source: Dickson and others (1993).
112

mostly intact. These widespread hardwood forests may

serve as source populations for some species, contributing

to landscape-scale population viability.

There is a wide variety of bird species associated with

upland oak forests. Some are habitat generalists, but most

are associated with specific habitat attributes. Forest structure, among other factors, determines bird species distribution (table 1). Some species, such as the field sparrow and

northern bobwhite, are associated with grass-forb habitat.

Others, such as the prairie warbler and white-eyed vireo,

inhabit shrub level vegetation. Some, such as the Kentucky

and hooded warblers inhabit shaded forest understories.

And some, such as the red-eyed vireo and summer and

scarlet tanagers, are found in tree canopies.

Based on Partners in Flight assessments, generally there is

concern for two categories of birds: neartic-neotropical

migratory birds, and early successional, grass-forb associated birds (Hunter and others 2001). Migratory species

considered of high priority and associated with mature oak

forests are presented in table 2. Causes for the decline are

Table 2—Primary habitat associations and seasonal status among high priority

landbird species within upland hardwood-dominated forested landscapes of the

Southeastern U.S.

Hardwood-dominated forests

Hardwood Central Appalachian

Regional high priority species pine mix hardwoods forests

American Woodcock B,W B

Yellow-billed Cuckoo B B B

Northern Saw-whet Owl

S. Appalachian pop. b

Chuck-will’s-widow B

Red-headed Woodpecker B,W

Yellow-bellied Sapsucker

S. Appalachian pop. B

Eastern Wood-Pewee B B B

Acadian Flycatcher B B B

Black-capped Chickadee

S. Appalachian pop. b

Red-breasted Nuthatch

S. Appalachian pop. b

Brown Creeper

S. Appalachian pop. b

Winter Wren

S. Appalachian pop. b

Golden-crowned Kinglet

S. Appalachian pop. b

Wood Thrush B B B

Yellow-throated Vireo B B

Northern Parula B B B

Black-throated Blue Warbler B

Black-throated Green Warbler

Atlantic Coastal pop. B

Blackburnian Warbler B

Cerulean Warbler B B B

Worm-eating Warbler B B B

Swainson’s Warbler B B

Louisiana Waterthrush B B

Kentucky Warbler B B B

Hooded Warbler B B B

Canada Warbler B

Appalachian forests = Appalachian forests include here mature to old-growth northern

hardwoods, hemlock-white pine-hardwoods, mixed mesophytic (cove) hardwoods, with various

gradations into Appalachian oak (central hardwoods) types on drier more exposed sites and into

spruce-fir at the highest elevations; B = breeding; W = wintering; B,W = refers to species using

similar habitat but in different areas between seasons (i.e., highly migratory); lower case (b) =

refers to habitats where species occurs in very low densities but may still prove to be important

to that species.

Source: Hamel (1992); Hunter and others (2001).
113

unclear. Perhaps wintering habitat is important; populations

of some mature forest associated species have declined

while upland hardwood forests in the U.S. have aged. Some

of these are isolated populations of otherwise widespread

species, such as the southern Appalachian population of

the Bewick’s wren (Hunter and others 2001).

Another group that has experienced declines in recent

decades is the early successional associated species.

Populations of resident game species, such as northern

bobwhites, ruffed grouse, and American woodcock, have

suffered substantial declines in recent decades as upland

forests have aged (Dickson 2001). Because of habitat

changes and/or population declines, several species in

both groups, neartic-neotropical migrants associated with

early successional habitat, such as prairie, chestnut-sided,

and golden-winged warblers are often listed as species of

concern (Hunter and others 2001).

So forest structure, and natural and anthropogenic forces

that affect that structure, to a large extent determine bird

communities. One example is the effects of the ecosystem

management practices on the Ouachita National Forest

(Bukenhofer and Hedrick 1997). In response to thinning

and prescribed burning, Wilson and others (1995) found

10 ground/shrub foraging and shrub nesting species of

breeding birds were favored, and 2 ground nesters, the

ovenbird and black-and-white warbler were disfavored.

The effects of tree harvesting on habitat structure and bird

communities have been amply demonstrated (Dickson and

others 1993). Two studies serve as examples and illustrate

the relationships. In an oak-hickory forest in northwestern

Arkansas, heavy cutting of understory and selective cutting

of overstory disfavored the understory nesting bird guild,

but favored some early successional species such as the

indigo bunting, edge species such as the eastern wood

pewee, and canopy nesters in the short term (Rodewald

and Smith 1998). In a central hardwood forest in Missouri

(Annand and Thompson 1997), five migrant songbirds, the

blue-winged warbler, prairie warbler, northern towhee, whiteeyed vireo, and yellow-breasted chat were more abundant

in clearcut treatments. Indigo buntings and field sparrows

were more abundant in clearcut and shelterwood treatments.

Hooded warblers and northern parulas were more abundant

in selection treatments. Ovenbirds and wood thrushes were

more abundant in mature sites. And Acadian flycatchers

and red-eyed vireos were more abundant in group and

single-tree selection treatments and mature stands. A nest

parasite, the brown-headed cowbird, was more abundant in

clearcuts, and abundance of the two avian nest predators,

the blue jay and American crow, did not differ among the

five treatments.

Bats

Bats are important ecological components of oak forests.

Several species are endangered, and there is concern for

other species. Bats are long-lived and have a low reproductive rate; usually one offspring each year. Bat species can

be grouped into two categories: cave bats, which inhabit

caves at some time, and non-cave bats, which seldom

enter caves. Three species of cave bats in the southern oak

forests are endangered: the gray bat, the Indiana bat, and

the eastern populations of Townsend’s big-eared bat (Ozark

and Virginia big-eared bats) (Harvey and Saugey 2001).

And three other species of forest cave bats, the southeastern

bat, the eastern small-footed bat, and the Rafinesque’s bigeared bat are of special concern.

Disturbance of cave bats by humans can be a problem. Cave

bats in hibernating or maternity colonies expend precious

energy when disturbed, and are vulnerable to disturbance.

Protection of cave sites is important to the conservation of

these species.

Habitat features and management activities near bat caves

and even forest wide may affect bats (Harvey and Saugey

2001). For example, a group of Rafinesque’s big-eared bats

always foraged less than 2.5 km from their hibernaculum

and maternity cave along ridgelines in an upland oak-hickory

forest (Hurst and Lacki 1999). Forest structure obviously is

important to bats during some time in their life cycle. Bats

use tree leaves, loose bark, cavities, snags, and other

structure, such as spanish moss for roosting and sometimes

maternity sites. Trees with these features are used by and

benefit bats. Streamside zones contain many tree and stand

features positive for bats; so retention of mature trees in

streamside zones when harvesting adjacent stands is beneficial. Bats are insectivorous, and silvicultural practices

which promote flying insects can be positive. Tree harvesting or prescribed burning may open foraging areas and

enhance insect prey. Bats often forage over water, such as

ponds and lakes, so appropriate habitat near water probably benefits bats.

Reptiles and amphibians

Even though upland oak ecosystems are mostly xeric, the

forests support a high diversity of reptile and amphibian

species, and provide important habitat for many species.

Some species are not associated with water, and spend

their entire life in forested habitat, often in small areas. The

greatest diversity of salamanders in the United States occurs

in the oak- dominated southern Appalachian region (Gibbons

and Buhlmann 2001). Species of the genus Plethodon are

common and several are endemic, with relict populations

inhabiting isolated mountains (Pough and others 1998).

Examples include the Peaks of Otter salamander on a 5-mile

stretch of ridge in Virginia, the Cow Knob salamander at

high elevations on the George Washington National Forest

along the Virginia-West Virginia boundary, and the Weller’s

salamander in the high elevation remnant spruce forests on

mountain tops in North Carolina and Virginia.

Other species are dependant on non-forest habitat for critical

stages of their life cycle. Salamanders, such as Ambystoma,

and frogs, such as narrow mouthed toads, inhabit forests

as adults but lay their eggs in water and their larvae are

aquatic. For these species, stream structure and water

quality in conjunction with moist forest habitat are important

habitat features. Streamside zones or strips of mature trees

along permanent or intermittent streams can provide

important habitat for a number of species (e.g., Rudolph

and Dickson 1990).

Other species are dependant on different and often limited

habitat. Examples include the Tennessee cave salamander,
114

which inhabits caves, and the green salamander that

inhabits shaded, moist, sandstone cliffs. For species or

populations that inhabit limited and often isolated habitat,

moist upland forests may function very importantly as

connective or linkage habitat. Also, other forest structures,

such as snags and down material, afford protection and

provide habitat for a variety of reptiles and amphibians.

CONCLUSIONS

Upland oak forests have always been dynamic, subjected

to and developed by a variety of natural and anthropogenic

forces. Wildlife communities of these forests have evolved

with and are adapted to these forests and their dynamic

nature. To accommodate the full complement of native wildlife a wide variety of different habitats, such as grass-forb,

shrub, woodland savannah, and mature stands should be

maintained in sufficient quantity and size.

ACKNOWLEDGMENTS

I thank Larry Hedrick and John Dickson for reviewing this

manuscript.

LITERATURE CITED

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renewal in the Ouachita Mountains. Transactions North American

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Dickson, J.G. 1990. Oak and flowering dogwood fruit production

for eastern wild turkeys. Proceedings National Wild Turkey

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Dickson, J.G., comp., ed. 1992. The wild turkey: biology and

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editor., Wildlife of Southern Forests: Habitat and Management.

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115

APPENDIX A

Common and Scientific Names of Animals in Text

Common name Scientific name Common name Scientific name

Mammals

Small-footed bat Myotis leibii

Indiana bat M. sodalis

Southeastern bat M. austroriparius

Gray bat M. grisescens

Rafinesque’s big-eared bat Plecotus rafinesquii

Townsend’s big-eared bat P. townsendii

Gray squirrel Sciurus carolinensis

Fox squirrel S. niger

Southern flying squirrel Glaucomys volans

White-footed mouse Peromyscus leucopus

Eastern woodrat Neotoma floridana

Black bear Ursus americanus

Raccoon Procyon lotor

Wild hog Sus scrofa

Elk Cervus elaphus

White-tailed deer Odocoileus virginianus

Birds

Wood duck Aix sponsa

Ruffed grouse Bonasa umbellus

Wild turkey Meleagris gallopavo

Northern bobwhite Colinus virginianus

American woodcock Scolopax minor

Carolina parakeet Conuropsis carolinensis

Red-headed woodpecker Melanerpes erythrocephalus

Red-bellied woodpecker M. carolinus

Eastern wood-pewee Contopus virens

Acadian flycatcher Empidonax virescens

White-eyed vireo Vireo griseus

Red-eyed vireo V. olivaceus

Blue jay Cyanocitta cristata

American crow Corvus brachyrhynchos

Birds (cont.)

Bewick’s wren Thryomanes bewickii

Blue-winged warbler Vermivora pinus

Golden-winged warbler V. chrysoptera

Northern parula Parula americana

Chestnut-sided warbler Dendroica pennsylvanica

Prairie warbler D. discolor

Black-and-white warbler Mniotilta varia

Ovenbird Seiurus aurocapillus

Kentucky warbler Oporornis formosus

Hooded warbler Wilsonia citrina

Yellow-breasted chat Icteria virens

Summer tanager Piranga rubra

Scarlet tanager P. olivacea

Eastern towhee Pipilo erythrophthalmus

Field sparrow Spizella pusilla

Indigo bunting Passerina cyanea

Brown-headed cowbird Molothrus ater

Reptiles and Amphibians

Eastern narrow-mouthed toad Gastrophryne carolinensis

Green salamander Aneides aeneus

Tennessee cave salamander Gyrinophilus palleucus

Peaks of Otter salamander Plethodon hubrichti

Cow knob salamander P. punctatus

Weller’s salamander P. welleri

Invertebrates

Gypsy moth Lymantria dispar

Red oak borer Enaphalodes rufulus

Plants

American chestnut Castanea dentata

White oak Quercus alba

Spanish moss Tillandsia usneoides
116

UPLANDS BY DEFAULT

Although we tend to equate bear habitat in the Southeast

with mountainous upland hardwood forests, bear occurrence in the mountains is probably by default rather than

preference. Historically, bears were common in the bottomland hardwoods of the Southeast (Gerstacker 1854, Bartram

1955). Remnant bottomland forests in Louisiana and

Arkansas continue to support some of the highest bear

densities in North America (Beausoleil 1999, R. Eastridge,

Arkansas Game and Fish Commission, unpublished data).

Those fertile bottomlands, however, were among the first to

be developed for agriculture and other uses and now

comprise only about 15 percent of their historic acreage

(Gosselink and others 1989). Bears rapidly disappeared

from those developed areas and, today, black bear populations in fragmented bottomlands are at greatest risk of

extinction (Neal 1992, Bentzien 1998).

As the conversion of bottomland forests to farmland

occurred, the less fertile, rugged land in the mountains

remained relatively undeveloped. During the early to mid1900s, many such upland areas came into public ownership, primarily as national forests and parks. Bears managed

to persist in inaccessible reaches of many of these areas

and later served to repopulate adjacent uplands where bear

densities had been severely reduced (Clark and Pelton

1998). Today, many consider bears to be overabundant in

portions of the region’s uplands. Although bears were

extirpated in the Cumberland Plateau of Tennessee and

Kentucky, and in the Interior Highlands of Arkansas and

Missouri, bear reintroduction programs in these areas have

been successful (Smith and Clark 1994, Eastridge and

Clark 2001).

OAKS, THE DRIVING FORCE

Simply put, bears could not survive in southeastern uplands

today without oak mast. Acorns have been found to be the

major fall food item of bears in virtually every study conducted

in southeastern uplands (Vaughan 2002). Pelton (1989)

describes acorns as the “driving force for bear population

dynamics” in the southern Appalachians; the same is

probably true in the Interior Highlands of Arkansas (Clapp

1990, Clark 1991).

Acorns are an important energy source for bears because

they are relatively high in fat and carbohydrates (Inman

1997). High-energy fall diets enable bears to withstand the

rigors of winter denning, production of young, lactation, and

food scarcity in early spring (Poelker and Hartwell 1973,

Eagle and Pelton 1983). During good acorn years, bears

are capable of fulfilling their energy requirements for 4 to 6

months of hibernation during a 2- or 3-month period of

intense foraging in the fall. Bears have been known to

consume >20,000 calories in a 24-hr period while feeding

on acorns (Nelson and others 1983). Additionally, acorns

are sometimes eaten in spring following years of mast

abundance. In the Interior Highlands, hard mast comprised

up to 45 percent volume and 75 percent frequency of spring

diets of bears during some years (Clapp 1990).

Bear movements increase dramatically in response to

acorn abundance, known as the “fall shuffle.” Their activity

patterns change from being primarily crepuscular, to nearly

continuous activity to forage on acorns (Garshelis and

Pelton 1980). Bears seasonally shift their home ranges and

movement patterns to take advantage of localized mast

(Garshelis and Pelton 1981) resulting in long-range movements during mast shortages. Acorn failures can have a

marked effect on bear mortality rates, with increased highway deaths being associated with the extensive movements.

Also, hunting mortality can be dramatically affected during

poor acorn years (Kane 1989, McDonald and others 1994,

Noyce and Garshelis 1997), with greater movements leading to higher success among hound hunters and localized

mast resulting in increased effectiveness of archery hunters.

With sequential years of mast failure, outright starvation

can occur.

OAK-BLACK BEAR RELATIONSHIPS IN SOUTHEASTERN UPLANDS

Joseph D. Clark1

1 Research Ecologist, U.S. Geological Survey, Southern Appalachian Field Laboratory, University of Tennessee, Knoxville, TN 37996.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Bears (Ursus americanus) primarily occur in upland habitats in the Southeast because uplands were the last to

be developed for agriculture and were more likely to become publicly owned. National parks and forests created in the

early to mid-1900s served as sources to supply surrounding uplands with bears. Bears could not survive in southeastern

uplands without oak mast. Bear reproductive and mortality rates in the region have been shown to be directly linked with

acorn production. Masting is thought to be an adaptation by oaks to satiate predators during good acorn years, thus

ensuring that the remainder will germinate. Acorn predator populations, however, cannot respond numerically to increased

acorn production because the masting is episodic and synchronous. Consequently, bears have developed physiological,

behavioral, and ecological adaptations to cope with such food shortages. Despite such adaptations, upland hardwood

forests in the Southeast are of lower quality than they once were. The loss of the American chestnut (Castanea dentata),

higrading, and soil degradation have markedly decreased the carrying capacity for bears and other wildlife. Other changes

such as recent forest management practices, forest fragmentation, invasion by the gypsy moth (Lymantria dispar), and

oak decline threaten to further degrade the capability of southeastern uplands to support bears.
117

The lack of acorns also can result in reproductive failure

(Eiler and others 1989, Pelton 1989). Bears have delayed

implantation, with breeding and fertilization occurring in

summer, and implantation of the blastocyst into the uterine

wall in fall. Failure to implant may occur in females in poor

physical condition. If implantation does take place in such

cases, the newborn cubs may not survive because of the

inability of the female to lactate (Vaughan 2002). Following

den emergence, cub mortality during mast failures has

been shown to be >80 percent (Vaughan 2002). Reproductive rates may be particularly impacted when mast failures

occur in 2 sequential years, as has occurred in the southern

Appalachians (Pelton 1989). Such mast failures also delay

age of first reproduction in females and can cause reproductive synchrony in this biennial breeder. In good mast

years following poor ones, parturition occurs among nearly

all adult females. This will result in a large cohort of

dispersing 2-year-old subadults, an age class vulnerable to

hunting and more prone to nuisance activity. Those 2-yearolds will likely breed the following year and subsequently

contribute to another large cohort. Thus, acorn failures and,

to a lesser extent, good acorn crops, have long-lasting

ecological effects on bear population dynamics.

BEARS, OAKS, AND COEVOLUTION

Acorns are an important source of fats and carbohydrates

in the diets of not only bears, but >180 other wildlife species

as well. Reproduction and survivorship for many species

are closely coupled with acorn production. Population fluctuations of white-footed mice (Peromyscus leucopus), gray

squirrels (Sciurus carolinensis), white-tailed deer (Odocoileus

virginianus), blue jays (Cyanocitta cristata), and red-headed

woodpeckers (Melanerpes erythrocephalus) have all been

linked with fluctuations in acorn mast crops (Pearson 1953,

Smith 1986, Elkington and others 1996, McCracken and

others 1999). Because of these many acorn predators, oaks

have developed mechanisms which reduce such predation.

Masting is the intermittent production of large seed crops

by a population of plants (Kelly 1994). One hypothesis to

explain this phenomenon is predator satiation (Salisbury

1942; Janzen 1971, 1975; Silvertown 1980, 1982; Koenig

and Knops 2002). Under that hypothesis, seed predator

populations are kept low in non-masting years because of

the scarcity of seeds whereas, during heavy mast years,

overabundant fruit places foraging limitations on mast

predators. Masting must be episodic so that populations of

mast predators do not have enough time to respond reproductively. Masting must also be synchronous over broad

areas so that acorn predation is not affected by immigration

from poor to good mast areas. Although weather patterns

(e.g., spring frosts, drought) can affect acorn production,

recent evidence suggests a natural periodicity to acorn production consistent with the predator satiation hypothesis

(Sork and others 1993).

Additionally, acorns have an anti-predator defense, tannin,

which makes them less palatable and digestible. Red oaks

have higher tannin content than do white oaks, but white

oaks sprout soon after they fall to the ground and, thus, do

not need as much protection from predation (Fox 1982).

Red oak acorns, on the other hand, have about three times

the fat content as white oaks. Both the fat and the tannin

are localized to certain portions of the acorns. White-footed

mice, squirrels, and other animals prefer red oak acorns,

perhaps because they can select the portion of the acorn

with the highest fat and lowest tannin content for consumption (Fox 1982, Line 1999). Black bears consume acorns

whole; consequently, they prefer white oak acorns. Thus,

masting and tannin content in oaks appear to be adaptations to acorn predation by bears and other species.

Conversely, bears are well adapted to endure such acorn

shortages and to take advantage of years of acorn abundance. Pelton (1989), in his review of the importance of oak

mast to black bears, states that bears adjust physiologically,

behaviorally, and ecologically in response to oak mast.

Physiologically, bears are adapted systemically and hormonally to digest the fats and carbohydrates found in acorns

(Brody and Pelton 1988). Once digested, bears have the

ability to store large quantities of fat and to use that stored

energy when needed. During hibernation, another adaptation to periods of food scarcity, that fat is converted to

energy and urea and other byproducts are recycled (Nelson

and others 1983). Weight loss during hibernation is from

adipose tissue only; lean body mass is conserved.

Behaviorally, bears are able to scale trees to eat acorns

from the canopy before the fruits fall. In acorn-rich areas,

bears tend to partition themselves spatially and temporally,

with minimal intraspecific conflicts, thus maximizing caloric

intake while minimizing caloric expenditure. Rogers (1987)

suggested that bears may first visit such food-rich areas as

cubs and later return as adults. The high level of intelligence of these mammals undoubtedly helps them relocate

areas where foods have been plentiful in the past.

Ecologically, bears are typical of a species adapted to fluctuating environmental conditions (Stearns 1977). The basic

strategy for bears, in a teleological sense, is to produce

young only when environmental (and, thus, physiological)

conditions are favorable and, once born, invest a maximum

amount of energy to ensure their survival. For example,

bears have a long gestation period, delayed age of first

reproduction, and a lengthy rearing period to maximize the

chances that their progeny will survive. Litter sizes are

small, enabling mothers to invest more energy to care for

cubs. Also, bears may defer reproduction during periods of

environmental stress (e.g., by implantation failure, fetal

absorption). In years when food is scarce, bears enter dens

earlier and avoid further energy expenditures. Thus, oaks

and acorn predators such as bears are engaged in what

has been called a “coevolutionary arms race.”

A CHANGING LANDSCAPE

Although oaks are “the driving force” today, that may not

have always been the case. The oak forests that we associate with southeastern uplands are essentially second- and

third-growth replacements. Additionally, many important

food-producing plants (e.g., American chestnut) have been

lost within the past century. Consequently, upland habitat

where most southeastern bears reside has been significantly degraded.

It is difficult to imagine how the southern Appalachians must

have looked when the American chestnut was a dominant
118

tree; >40 percent of the overstory in the southern Blue

Ridge Mountains once was chestnut (Keever 1953). The

chestnut blight fungus (Cryphonectria parasitica), introduced around 1900, resulted in the nearly complete loss of

American chestnut in the eastern U.S. (Keever 1953).

Those oak-chestnut forests have since been replaced

largely by oak-hickory forests (McCormick and Platt 1980).

Besides being common, annual crops of chestnuts were

more reliable, without the extreme fluctuations common to

oaks. In North Carolina, mast production was estimated for

2 10-year periods; one before and one 35 years after the

chestnut blight fungus had killed all mature chestnut trees

(Diamond and others 2000). Total hard mast output was 34

percent less after the chestnut blight and annual pre-blight

mast production was relatively stable, whereas annual postblight production fluctuated substantially. These findings

suggest that the loss of mature chestnuts markedly reduced

the carrying capacity of southern Appalachian forests for

certain wildlife species, which certainly included the black

bear.

Bears have remarkable adaptability, and have flourished

even with the loss of the American chestnut in the East.

Nevertheless, changes are taking place in southeastern

upland hardwood habitats that could negatively affect bears

in the future. Past logging practices have resulted, not only

in young forests in southeastern uplands, but in forest

higrading and soil degradation as well. Another important

consideration for bears is soft mast production, the importance of which may have been underestimated in the past

(Inman 1997). Clapp (1990) found that soft mast [dominated by Carolina buckthorn (Rhamnus caroliniana), Virginia

creeper (Parthenocissus quinquefolia), black cherries,

(Prunus serotina), devil’s walkingstick (Aralia spinosa),

pokeweed berries (Phytolacca americana), blackgum (Nyssa

sylvatica), and persimmon (Diospyros virginiana)] comprised

a greater proportion of black bear diets in the Interior

Highlands in 2 of 3 years than did hard mast. Blueberries

(Vaccineum spp.), blackberries (Rubus spp.), cherries, and

grapes (Vitis spp.) all respond favorably to light gaps and

disturbance. Pokeweed, for example, requires soil disturbance to generate. Given the trend away from the creation

of early successional stage habitats on national forests,

such buffer foods may not be as abundant as in the past.

That is not to say that bears cannot thrive in mature hardwood forests. In Great Smoky Mountains National Park, for

example, bear densities are high (Eason 2002). Forests in

the Smokies, however, have a substantial old-growth component (>20 percent), and the large trees that fall create

light gaps. It may be many years before such a dynamic is

achieved in the second- and third-growth upland forests

found on our national forests. Soft mast production may be

low in the interim.

A change that has yet to fully strike the southeastern uplands

is the invasion of the gypsy moth. These insects have defoliated oaks in much of Virginia, but bears there were able to

make use of buffer foods (primarily soft mast including

grapes and pokeweed) and shift their movement patterns

to patches of oaks that were not affected by the moths

(Kasbohm and others 1998). Again, changes in forest

composition and a reduction in soft mast could greatly

affect the ability of bears to withstand chronic reductions in

acorns.

Bears are a mobile, wide ranging species, and have developed the physical and intellectual ability to take advantage

of patchy, sporadic food resources. Fragmentation through

clearing of woodlands for other uses and the construction

of roads through prime bear habitat will greatly diminish the

ability of bears to exploit such food resources. Although

bears have demonstrated the plasticity to adapt to historic

and recent habitat changes (i.e., chestnut blight, gypsy

moths, and forest fragmentation), the cumulative effects of

these perturbations, along with future problems (i.e., climate

change and oak decline), may have a more widespread

and lasting effect on bears.

Bears are inextricably linked with oaks in southeastern

uplands. Managers should strive for a landscape mosaic

comprised of red and white oak species interspersed with a

wide array of soft mast to serve as buffer foods during

acorn shortages. It is important to monitor changes in foodproducing plants within bear range and to evaluate the

effects those changes may have on bear population

dynamics. Only then will we be able to explore ways to

mitigate their effects.

LITERATURE CITED

Bartram, W. 1955. The travels of William Bartram. M. van Doren,

editor. Dover Books, New York, New York, USA. 414 p.

Baughman, M.J.; Jacobs, R.D. 1992. Woodland owners’ guide to

oak management. Minnesota Extension Service, University of

Minnesota, www.extension.umn.edu/distribution/

naturalresources/DD5938.html.

Beausoleil, R.A. 1999. Population and spatial ecology of the

Louisiana black bear in a fragmented bottomland hardwood

forest. Knoxville, TN: University of Tennessee, [Not paged].

M.S. thesis.

Bentzien, M.M. 1998. Endangered and threatened wildlife and

plants: New 12-month finding for a petition to list the Florida

black bear. Federal Register 63(235): 67613-67618.

Brody, A.J.; Pelton, M.R. 1988. Seasonal changes in digestion in

black bears. Canadian Journal of Zoology 66: 1482-1484.

Clapp, D.L. 1986. Availability and consumption of foods and

importance of habitats used by black bears in Arkansas.

Fayetteville, AR: University of Arkansas. 119 p. M.S. thesis.

Clark, J.D.; Guthrie, W.R.; Owen, W.B. 1987. Fall foods of black

bears in Arkansas. Proceedings of the Annual Conference of

the Southeastern Association of Fish and Wildlife Agencies 41:

432-437.

Clark, J.D.; Pelton, M.R. 1999. Management of a large carnivore:

black bear. Pages – 209-223 in J. Peine, ed., Ecosystem

Management for Sustainability: Principles and Practices

Illustrated by the Southern Appalachian Biosphere Reserve

Cooperative. Lewis Publishers, Boca Raton, Florida, USA.

Diamond, S.J.; Giles, R.H.; Kirkpatrick, R.L.; Griffin, G.J. 2000.

Hard mast production before and after the chestnut blight.

Southern Journal of Applied Forestry 24: 196-201.

Eagle, T.C.; Pelton, M.R. 1983. Seasonal nutrition of black bears in

the Great Smoky Mountains National Park. Proceedings of the

International Association for Bear Research and Management

5: 94-101.
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Eason, T.H. 2002. Population ecology of black bears in Great

Smoky Mountains National Park. Knoxville, TN: University of

Tennessee, . [Not paged]. Ph.D. dissertation.

Eastridge, R.; Clark, J D. 2001. Experimental reintroduction of

black bears to the Big South Fork area of Kentucky and

Tennessee. Wildlife Society Bulletin 29: 1163-1174.

Eiler, J.H.; Wathen, W.G.; Pelton, M.R. 1989. Reproduction in

black bears in the Southern Appalachian Mountains. Journal of

Wildlife Management 53: 353-360.

Elkington, J.S.; Healy, W.M.; Buonaccorsi, J.P. [and others]. 1996.

Interactions among gypsy moths, white-footed mice, and

acorns. Ecology 77: 2332-2342.

Fox, J.F. 1982. Adaptation of gray squirrel behavior to autumn

germination by white oak acorns. Evolution 36: 800-809.

Gerstacker, F. 1854. Wild sports in the Far West: the narrative

of a German wanderer beyond the Mississippi, 1837-1843.

Reprinted from the English translation of 1854, with introd. and

notes by Edna L. Steeves and Harrison R. Steeves. Duke

University Press, Durham, N.C., USA.

Gosselink, J.G.; Shaffer, G.P.; Lee, L.C. [and others]. 1989.

Cumulative impact assessment and management in a forested

wetland watershed in the Mississippi River floodplain. Marine

Sciences Department, Louisiana State University, Baton

Rouge, Louisiana, USA.

Inman, R.M. 1997. Caloric production of black bear foods in Great

Smoky Mountains National Park. Knoxville, TN: University of

Tennessee, [Not paged]. M.S. thesis.

Kane, D.M. 1989. Factors influencing the vulnerability of black

bears to hunters in northern New Hampshire.Durham, NH:

University of New Hampshire. [Not paged]. M.S. thesis.

Kasbohm, J.W.; Vaughan, M.R.; Kraus, J.G. 1998. Black bear

home range dynamics and movement patterns during a gypsy

moth infestation. Ursus 10: 259-267.

Keever, C. 1953. Present composition of some stands of the former

oak-chestnut forest in the southern Blue Ridge Mountains.

Ecology 34: 44-54.

Kelly, M.J. 1994. The evolutionary ecology of mast seeding.

Trends in Ecological Evolution 9: 465-470.

Koenig, W.D.; Knops, J.M.H. 2002. The behavioral ecology of

masting in oaks. Pages 129-148 in Oak Forest Ecosystems.

W. J. McShea and W. M. Healy, editors. The Johns Hopkins

University Press, Baltimore, Maryland, USA.

Line, L. 1999. When nature goes nuts. National Wildlife 37(6):

48-57.

McCormick, J. F.; Platt, R.B. 1980. Recovery of an Appalachian

forest following the chestnut blight or Catherine Keever-you

were right! American Midland Naturalist 104: 264-273.

McCracken, K.M.; Witham, J.W.; Hunter, M.L., Jr. 1999. Relationships between seed fall of three tree species and Peromyscus

leucopus and Clethrionomys gapperi during 10 years in an oakpine forest. Journal of Mammalogy 80: 1288-1296.

McDonald, J.E., Jr.; Fuller, D.P.; Fuller, T.K.; Cardoza, J.E. 1994.

The influence of food abundance on success of Massachusetts

black bear hunters. Northeast Wildlife 51: 55-60.

Neal, W.A. 1992. Threatened status for the Louisiana black bear

and related rules. Federal Register 57(4): 588–595.

Nelson, R.A.; Folk, G.E., Jr.; Pfeiffer, E.W.; [and others]. 1983.

Behavior, biochemistry, and hibernation in black, grizzly, and

polar bears. International Conference on Bear Research and

Management 5: 284-290.

Noyce, K.V.; Garshelis, D.L. 1997. Influence of natural food

abundance on black bear harvests in Minnesota. Journal of

Wildlife Management 61: 1067-1074.

Pearson, P.G. 1953. A field study of Peromyscus populations in

Gulf Hammock, Florida. Ecology 34: 188-207.

Pelton, M.R. 1989. The impacts of oak mast on black bears in the

Southern Appalachians. Pages 7 - 11 in C. E. McGee, ed.,

Proceedings of the Workshop: Southern Appalachian Mast

Management, August 14-16, University of Tennessee,

Knoxville, Tennessee.

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Southeastern United States. Pages 31-44 in A. L. Gaski and D.

F. Williamson, editors. Proceedings of the Second International

Symposium on the Trade of Bear Parts. Traffic USA/World

Wildlife Fund, Washington D.C., USA.

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Washington State Game Department, Biological Bulletin 14.

Olympia, Washington, USA. 180 p.

Rogers, L.L. 1987. Effects of food supply and kinship on social

behavior, movements, and population growth of black bears in

northeastern Minnesota. Wildlife Monograph 97: 1-72.

Smith, K.G.; Clark, J.D. 1994. Black bears in Arkansas: characteristics of a successful translocation. Journal of Mammalogy. 75:

309-320.

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in three species of North American deciduous oaks. Ecology

74: 528-541.

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240 in Oak Forest Ecosystems. W. J. McShea and W. M. Healy,

editors. The Johns Hopkins University Press, Baltimore,

Maryland, USA.
120

INTRODUCTION

When European settlers arrived, much of northwestern

Arkansas was in oak-hickory forest, and many regions are

still heavily wooded in this manner (James and Neal 1985).

These extensive forests of the Ozarks in northwestern

Arkansas are believed to be population sources for several

species of birds (Robinson and others 1995). There is

much concern in recent decades about population declines

in forest breeding intercontinental migratory birds in many

regions of eastern North America (Martin and Finch 1995,

Sauer and Droege 1992, Sauer and others 1999). Due to

these declines population sources are important in helping

to maintain population numbers elsewhere (Pulliam 1988).

In recent years the red oak borer, Enaphalodes rufulus

(Haldane), has had considerable impact on oak trees, devastating large areas (Spencer 2001). The loss of these trees

may have a negative impact on populations of bird species,

some of which are already stressed by other factors.

The present study was designed to investigate the importance of oaks in summer foraging by species of both yearround resident and summer resident migratory bird species

in closed canopy oak-hickory forests that were not infested

with the oak borer. Relative abundance of different tree

species was used to determine whether oaks are used in

greater or lesser proportion than their abundance by various

bird species and in what proportion are other tree species

used compared to their abundance and compared to oaks.

SITES

Six sites, all in northwestern Arkansas, were used in this

study. All were closed canopy oak-hickory forests in different

stages of development with varying amounts of undergrowth.

Tree composition differed between sites. The following sites

were located in Washington County: (1) Mount Sequoyah

in Fayetteville, Section 15, Township 16N, Range 29W;

(2) Lake Fayetteville area, Section 19, Township 17N, Range

29W; (3) Wilson Lake area, southeast of Fayetteville,

Section 2, Township 15N, Range 30W; and (4) Devil’s Den,

near West Fork, Section 26, Township 13N, Range 31W.

The remaining sites are Hobbs State Management Area at

Beaver Lake near War Eagle in Benton County, Section 36,

Township 19N, Range 29W; and Withrow Springs near

Forum in Madison County, Section 10, Township 17N,

Range 26W.

METHODS

During the months of May, June, and July 2002 foraging

behavior was studied in birds occupying oak-hickory forests

in areas appearing unaffected by the oak borer. Two investigators walking together found foraging birds as they were

encountered. One identified the birds and the tree species

they occupied, the other recorded the information. A bird

was considered to use a tree if it was either seen or heard

in the tree. Data was recorded sequentially (Robinson and

Holmes 1982). No more than three sequential observations

of the same bird in the same tree were made. Both yearround resident and intercontinental migratory species were

investigated. The number of bird observations per study

area were approximately the same, but did differ somewhat.

Relative abundance of different species of trees in the study

areas was determined by establishing two perpendicular

transects transversing each of the study areas. There were

two investigators. One identified the species of each tree

having a diameter at breast height (d.b.h.) greater than 7.5

cm that occurred within a meter each side of the transect

line, the other recorded this information.

RESULTS AND DISCUSSION

Tree Species Composition

To summarize forest composition, oak species (Quercus)

made up about 25 percent or more of the trees at Wilson

Lake, the Hobbs State Management Area, and Withrow

Springs, nearly 20 percent at Mount Sequoyah and Lake

Fayetteville, and slightly more than 10 percent at Devil’s

Den. Hickory species (Carya) made up approximately 20

percent of the trees at Wilson Lake and the Hobbs State

Management Area, somewhat less at Mount Sequoyah,

between 5 and 10 percent at Lake Fayetteville and less

than 5 percent at Devil’s Den and Withrow Springs. Elm

species (Ulmus) made up over 30 percent of the trees at

USE OF TREE SPECIES BY SUMMER BIRDS IN

OZARK UPLAND OAK-HICKORY FOREST

C. Joan Patterson and Douglas A. James1

1 Graduate Student and Teaching Assistant, and Professor, Department of Biological Sciences, University of Arkansas, Fayetteville, AR

72701, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Impacts of oak-boring beetles in the Ozark region could produce major changes in forest communities of

northwestern Arkansas resulting in loss of oaks replaced by other tree species. Because the extensive Ozark forests are a

major source of surplus birds, alterations of forest structure producing changes in foraging opportunities for birds could

have serious consequences. This study compared tree species usage while foraging in summer by year-round resident

and summer resident migratory forest bird species. Extent of usage was compared to relative abundance of different tree

species at each of six study sites. The results show that oak species were used by forest birds in greater proportion than

their abundance at the sites.
121

Mount Sequoyah, over 20 percent at Wilson Lake, between

5 and 10 percent at Lake Fayetteville, Devil’s Den and the

Hobbs State Management Area, and < 2 percent at Withrow

Springs. The proportion of black gum, Nyssa sylvatica Marsh,

was around 20 percent at Withrow Springs, somewhat less

at Devil’s Den, around 5 percent at the Hobbs State

Management Area, and low or not found at the three other

sites. The proportion of flowering dogwood, Cornus floridana

Linnaeus, was > 25 percent of the trees at Devil’s Den,

nearly 20 percent at Lake Fayetteville and Withrow Springs,

over 10 percent at the Hobbs State Management Area, and

< 5 percent at Mount Sequoyah and Wilson Lake. Snags

made up >10 percent but <20 percent of trees at all sites.

Other tree species were present in smaller numbers.

Birds Found

To provide a summary of bird species involved, Tufted

Titmice, Baeolophus bicolor (Linnaeus), were observed

relatively frequently at all sites, with the most observations

at Mount Sequoyah and Withrow Springs. Carolina

Chickadees, Poecile carolinensis (Audubon), were observed

frequently at Mount Sequoyah and Lake Fayetteville, less

at Wilson Lake and Withrow Springs, and least often at

Devil’s Den and Hobbs State Management Area. Whitebreasted Nuthatches, Sitta carolinensis Latham, were

observed with moderately high frequency at Withrow

Springs and moderately low frequency at the other sites.

Downy Woodpeckers, Picoides pubescens (Linnaeus),

were observed with moderately high frequency at Mount

Sequoyah and moderately low frequency at the other sites.

The Red-bellied Woodpecker, Melanerpes carolinus

(Linnaeus), was observed at moderate frequency at Hobbs

State Management Area and at low frequency elsewhere.

Blue Jays, Cyanocitta cristata (Linnaeus), were observed at

moderate frequency at Devil’s Den and at low frequency

elsewhere. Of the summer resident migratory birds, Redeyed Vireos, Vireo olivaceus (Linnaeus), were observed

often at Wilson Lake and Hobbs State Management Area,

somewhat less at Withrow Springs, less at Devil’s Den, and

at moderately low frequency at Mount Sequoyah and Lake

Fayetteville. Blue-gray Gnatcatchers, Polioptila caerulea

(Linnaeus), were observed very often at Wilson Lake,

moderately often at Hobbs State Management Area and

Devil’s Den, less often at Lake Fayetteville and infrequently

at Mount Sequoyah. Black-and-white Warblers, Mniotilta

varia (Linnaeus), were observed rather often at Devil’s Den,

less at Lake Fayetteville, and rather infrequently at other

sites. Twelve other species of birds were not abundant at

the study sites but were included as part of the foraging

data.

Trees used by birds

The focus of this study was use of tree species by foraging

birds, not foraging differences between bird species, so all

birds were combined in evaluation of bird use of various

tree species, especially oak species compared to non-oaks.

Bird observations were to some extent dependent. This

problem was overcome by combining all bird species into a

single data set totaling more than one thousand observations. At every site oaks were used in greater proportion

than their abundance at the site and other tree species

were used less than their abundance.

The findings can be analyzed in three different ways (table

1). Firstly, data from all six study areas can be combined

omitting the very low tree and usage frequencies. This

produces the results in the top part of table 1. To elaborate,

there were six species of oaks of which five were used by

birds more frequently than their forest abundances, only

one oak used less. There were 24 species of non-oaks and

19 were used less than their abundance in the forest, 5

were used more than their frequency. Chi-square analysis

of this pattern (two-by-two contingency table) showed that

the oaks were frequented by birds significantly more often

than non-oaks relative to their respective frequencies in the

forest (Chi-square = 8.44, 1 d.f., p<0.01, 2-tailed test).

Rather than combining across all study sites, the separate

information of each site can be used and accumulated

across all sites. Thus the information on relative tree

species usage by birds can be inspected at one site, and

the same usage of the same tree species at other sites can

be added to that data, repeating and accumulating with the

same tree species at each site. If the low frequencies of

tree abundance and avian foraging usage are omitted, this

produces the data in the middle of table 1. Thus, repeat

species of oaks across all study sites totaled 20 species

events, of which 18 were used more than expected, only 2

less than their frequency in the forest. The same information for non-oaks shows 59 species events of which 36

were used less than their proportion in the forest, 23 used

by birds more than expected. Chi-square analysis of this

pattern (two-by-two contingency table) showed that birds

used oaks significantly more than their abundance in the

forest, non-oaks significantly less (Chi-square = 17.15,

1 d.f., p<0.001, two-tailed test).

The same approach using information from each site accumulated across each site separately can include the low

frequencies of tree presence and bird usage. These results

are in the bottom part of table 1. Chi-square analysis of

Table 1—Usage of oaks by birds compared to other

tree species, whether used more or less frequently

than tree species abundances in the forest

Species Number Number

Taxa events used more used less

Combined data less low frequencies

Oaks 6 5 1

Non-oaks 24 5 19

Accumulated data less low frequencies

Oaks 20 18 2

Non-oaks 59 23 36

Accumulated data including low frequencies

Oaks 28 23 5

Non-oaks 110 35 75
122

these columns support the previous results (Chi-square =

20.41, 1 d.f. p<0.001, 2-tailed test).

The study will be continued in upcoming years to confirm

these preliminary findings and to obtain enough data to

determine which birds rely most on oaks and to see which

other tree species might also be preferred. This study

raises serious cause for concern that indeed at least some

of these forest birds will be negatively affected if oak

species are devastated as predicted. It would also be

valuable to study foraging behavior in forests already

impacted by the oak borer to see which bird species are

present and whether or not their foraging behavior has

been modified in the presence of oak loss.

ACKNOWLEDGMENTS

Thanks go to Melissa Fierke who took time and effort to

explain how to accomplish some of the data analysis.

Special thanks go to Donald W. Ouellette for his

considerable assistance in obtaining the data.

LITERATURE CITED

James, D.A.; Neal, J.C. 1986. Arkansas birds: their distribution and

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123

INTRODUCTION

In the past 20 years, the perceived role of fire in mixed-oak

forests has changed from a solely destructive force to be

prevented, to acceptance of its historical role in perpetuating

mixed-oak forests, to active research on the effects and

potential uses of prescribed fire as a regeneration tool. This

research has produced a wide variety of results: sometimes

fire is beneficial (Brown 1960, Carvell and Maxey 1969,

Ward and Stephens 1989); sometimes it is detrimental

(Johnson 1974, Loftis 1990, Wendel and Smith 1986); and

sometimes it has no noticeable effect on oak regeneration

(Merritt and Pope 1991, Teuke and Van Lear 1982). The

studies differed from each other in many important aspects.

For example, they were conducted in different regions and

at different times of the year. Some were post-wildfire assessments, while others dealt with prescribed fires. Some were

burned – unburned comparisons, while others were preburn

versus postburn evaluations. Some occurred in the dense

shade of stands that had been undisturbed for decades,

while others took place in the high-light conditions of new

or recently disturbed stands. They did share some similarities: nearly all of the studies used plots to inventory vegetation, focused on sprouts, assumed fire intensity was equal

throughout the burn, and ignored root development differences among hardwood species. Consequently, they produced widely disparate findings and resulted in no definitive

silvicultural technique involving fire as a predictable regeneration tool.

In 1993, the Virginia Department of Game and Inland

Fisheries conducted a 1-year pilot study of prescribed fire

effects on hardwood regeneration in oak-dominated shelterwood stands (Keyser and others 1996). The study revealed

that oak reproduction was more resistant to summer fire

than were competing hardwood species. This study led to a

4-year comprehensive fire project, which was intended to

address some of the shortcomings of previous studies. The

goal was twofold: (1) confirm the pilot study’s findings, and

(2)elucidate why earlier fire/oak research had produced

such different results. The fire project addressed some of the

shortcomings of previous studies. For instance, responses

of regeneration of major hardwood species were compared

among varying fire severities within differing seasons-ofburn (Brose and others 1999a, Brose and Van Lear 1998).

The spatial relationship between fuel loading and its proximity to a residual tree and subsequent fire damage were

studied (Brose and Van Lear 1999). Also, a fire – silvicultural technique was developed (Brose and others 1999b).

Like previous fire studies, this one relied heavily on plots to

inventory hardwood regeneration and focused on what

sprouted after the fires.

However, the study did not use plot-based inventory methods

exclusively. Data also were collected on the fate of individual stems of the major hardwood species groups. The

purpose of this paper is to present the findings gleaned

from using the individual-stem approach to study fire effects

in mixed-oak forests.

METHODS

Site Description

The study took place from 1994 to 1998 in three central

Virginia mixed-oak stands. The stands were similar to each

other. All were situated on the top and upper side slopes of

gently rolling hills at elevations of 500-600 feet above sea

level. Soil series for all three stands was a Cecil sandy loam

with a white oak site index of 75 feet (base age 50). The

stands originated in the late 1890s, were even-aged, and

had been partially harvested about 1990, reducing basal

area from 120 to 60 ft2

 per ac. The resultant shelterwood

had about 50 percent canopy closure. The most abundant

canopy species were the upland oaks [black oak (Quercus

velutina), chestnut oak (Q. prinus), northern red oak (Q.

rubra), scarlet oak (Q. coccinea), and white oak (Q. alba)].

American beech (Fagus grandifolia), blackgum (Nyssa

sylvatica), flowering dogwood (Cornus florida), mockernut

hickory (Carya tomentosa), pignut hickory (C. glabra), red

maple (Acer rubrum), and yellow-poplar (Liriodendron

tulipifera) also were present, especially in the midstory. The

heavy partial cut resulted in abundant advance regeneration (> 20,000 stems per ac) with all canopy species

represented though yellow-poplar was the most abundant

SURVIVAL OF HARDWOOD REGENERATION DURING PRESCRIBED FIRES:

THE IMPORTANCE OF ROOT DEVELOPMENT AND ROOT COLLAR LOCATION

Patrick Brose and David Van Lear1

1 Research Silviculturist, USDA Forest Service, Northeastern Research Station, Irvine, PA 16329; and Professor, Department of Forest

Resources, Clemson University, Clemson, SC 29634, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Fire ecology studies in eastern hardwood forests usually use plot-based inventory methods and focus on

sprouting stems to detect changes in vegetative composition and structure. Rarely are individual stems studied and stems

that fail to sprout are usually ignored. In this study, an individual stem mortality approach was employed. Four hundred

fifty stems of eight different species were tagged before prescribed burns. Top-killed stems later were analyzed to

determine why some died and others did not. Root collar diameter and root collar location proved to be critical in rootstock

survival. These findings indicate why oak and hickory, with their seed burial, hypogeal germination, and root-development

strategies, are more likely to survive surface fires than many of their competitors.
124

species. Hickory and oak regeneration height averaged

less than 2 feet while red maple and yellow-poplar reproduction averaged more than 4 feet.

Study Design and Implementation

The basic design and implementation of the study are thoroughly described elsewhere (Brose and Van Lear 1998,

Brose and Van Lear 1999, Brose and others 1999a), but

are reviewed briefly here. The stands ranged from 15 to

50 acres; each was divided into four treatments (spring,

summer, and winter burns, and an unburned control). In

1994, prior to the prescribed fires, fifteen 8-foot radius

regeneration inventory plots were established systematically in each treatment to ensure uniform coverage. A linear

transect to inventory fuels (Brown 1974) originated from

each plot center and extended out 50 feet. Each plot/transect was photographed before the fires. Along each fuels

transect, three to five advance regeneration stems, visually

judged to represent the range in height of surrounding

reproduction, were tagged for long-term study. Species,

root collar diameter (RCD), and root collar location (RCL)

were recorded for each tagged stem. Root collar is defined

as the transition point between stem and root and is identifiable by a ring of callous tissue and dormant buds. A total

of 150 stems per treatment were measured, for a total of

600 stems (450 in burn treatments, 150 in controls).

Virginia Department of Game and Inland Fisheries personnel

conducted the prescribed burns in February (winter), April

(spring), and August (summer) 1995. Fire behavior was

typical for the seasons: spring fires burned more intensely

than summer and winter fires. Plots, transects, and tagged

stems were reinventoried for 3 years following the fires.

Statistical Analysis

In previous research (Brose and others 1999a, Brose and

Van Lear 1998), fire severity (a continuous variable) was

divided into discrete classes. This was accomplished by

comparing the preburn photos to the appropriate plot immediately after the fire to visually assess fire effects. This evaluation subsequently was coupled with the initial postburn

fuels inventory, leading to four severity classes (low, mediumlow, medium-high, and high) within each season-of-burn

(Brose and Van Lear 1998). The severity classes were

defined as follows:

1. low - consumed only the most recently fallen leaf litter

and 1-hour fuels, top-killed less than 75 percent of small

reproduction (stems less than 4.5 feet tall) and small

saplings [more than 4.5 feet tall but less than 2 in. in

diameter at breast height (d.b.h.)]

2. medium-low - removed all leaf litter, 1-hour, and 10-hour

fuels, top-killed more than 75 percent of small reproduction and small saplings but killed few, if any, stems

greater than 2 in. in d.b.h.

3. medium-high – same as medium-low except stems 2-5

in. in d.b.h. were frequently top-killed

4. high – same as medium-high plus burned down into the

duff layer, noticeably reduced 100-hour fuels, and topkilled stems greater than 5 in. in d.b.h.

The 12 combinations of fire severity and season-of-burn

could be reduced to three groups of distinct impact (table 1).

Minor impact indicated that only one species group was

significantly reduced in density (number of stems per acre)

and this response was found in the low-, medium-low and

medium-high severity winter burns and the low-severity

spring burn. Moderate impact indicated that densities of two

species groups were reduced and this effect was noted in

the high severity winter burn, medium-low severity spring

burn, and the low and medium-low severity summer burn.

Major impact indicated that densities of more than two

species groups decreased in response to the prescribed

fires and this result occurred in the medium-high and high

severity spring and summer fires.

The tagged stems were sorted into four categories based

on RCL: in litter, at litter/duff interface, in duff, and at or

below the duff/soil interface. Four RCD classes (<0.25 in.

diameter, 0.25-0.50 in. diameter, 0.51-0.75 in. diameter,

and >0.75 in. diameter) were defined based on an approximate minimum number of 20-tagged stems per RCD class.

This created a 4x4 RCD/RCL grouping table for each

impact level.

The null hypothesis was that the stem mortality rate (the

proportion of stems failing to sprout after fire) would not

differ by RCD/RCL grouping. To test this hypothesis, Chisquare analysis (Ott 1993) was used on each impact level.

The mortality rate in each impact level was calculated by

dividing the number of dead stems by the total number of

stems. The number of stems in each cell of the RCD/RCL

grouping table was then multiplied by the mortality rate to

obtain the expected number of dead stems per cell. The

number of tagged stems failing to sprout in each RCD/RCL

grouping was the observed value.

Also tested by chi-square analysis was species distribution

of all tagged stems by RCD/RCL grouping. For this test, the

null hypothesis was that there were no differences among

species by RCD/RCL grouping. The expected value for

each species was its proportional contribution to the entire

sample size. For both tests, alpha was set at 0.05 to detect

significant differences between expected and observed

values.

Table 1—Impact of fire severity and season-of-burn

interaction on mortality of hardwood regenerationa

Season of burn

Fire severity

classification Spring Summer Winter

Low Minor Moderate Minor

Medium-low Moderate Moderate Minor

Medium-high Major Major Minor

High Major Major Moderate

a Minor, moderate, and major signify that one, two, and more

than two species groups were reduced in density, respectfully.
125

RESULTS

The 450 tagged stems in the burn treatments were distributed by species as follows: 228 oak, 55 hickory (combined

with oak for analysis purposes), 80 red maple, and 87 yellowpoplar. All species were found in all RCD/RCL groupings,

but definite species-specific trends were detected (table 2).

Yellow-poplar dominated the smallest/shallowest RCD/RCL

classes, while oak and hickory comprised the vast majority

of the stems in the largest/deepest RCD/RCL classes, and

red maple was predominated in the middle groupings.

Of the 450 tagged stems in the burn treatments, 37 were not

top-killed by the fires and were dropped from the analysis.

The remaining 413 were distributed among the three impact

levels as follows: minor–121, moderate–135, and major–

157. Within each impact level, the tagged stems were fairly

evenly distributed among the 16 RCD/RCL groupings with

about 5 to 15 stems per each combination. Of these, 183

failed to sprout by the end of the study and were distributed

among the three impact levels as follows: minor–34, moderate–62, and major–87 (table 3).

Chi-square analysis rejected the null hypothesis, dead stems

were not evenly distributed in any the three impact categories (table 3). The distribution of the 183 dead stems by

RCD/RCL class was skewed toward the smallest/shallowest

classes, regardless of impact level. At minor impact, 34 of the

121 (28.1 percent) tagged stems never sprouted and twothirds of these dead stems were found in the two smallest

RCD/RCL classes (<0.25/litter and <0.25/litter-duff). However, neither of these had 100 percent mortality of all stems.

Table 2—Distribution of 450 hardwood stems in the

burn treatments by RCD/RCL groupinga

Root collar Root collar diameter

location <0.25 0.25–0.50 0.51–0.75 >0.75

 - - - - - - - - - - - - - - inches - - - - - - - - - - - - - -

Litter 11, 8, 28 9, 8, 21 10, 3, 13 7, 6, 8

Litter/duff 35, 7, 6 16, 10, 6 12, 5, 0 12, 4, 1

Duff 32, 5, 2 22, 8, 0 17, 7, 1 14, 2, 0

Duff/soil 23, 3, 0 26, 1, 1 24, 2, 0 13, 1, 0

Chi-square: 181.65, Critical Value: 34.76 (alpha = 0.05, df = 47).

a Each three-number sequence in each column represents, from

left, numbers of hickory/mixed oak, red maple, and yellow-poplar,

respectively.

Table 3—Distribution of total and dead stems by RCD/RCL grouping

within each impact levela

Root collar Root collar diameter

location <0.25 in. 0.25–0.50 in. 0.51–0.75 in. >0.75 in.

 Minor impact (121 total stems, 34 dead, 28.1%)

Litter 14, 12, 86% 9, 4, 44% 8, 1, 13% 4, 0, 0%

Litter/duff 15, 11, 73% 7, 3, 43% 5, 0, 0% 3, 0, 0%

Duff 9, 3, 33% 8, 0, 0% 7, 0, 0% 5, 0, 0%

Duff/soil 8, 0, 0% 10, 0, 0% 5, 0, 0% 4, 0, 0%

Chi-square: 46.23, critical value: 7.26 (alpha = 0.05, df = 15).

 Moderate impact (135 total stems, 62 dead, 45.9%)

Litter 17, 15, 88% 11, 7, 64% 6, 4, 67% 6, 2, 33%

Litter/duff 15, 13, 87% 8, 5, 63% 3, 1, 33% 4, 0, 0%

Duff 13, 9, 69% 10, 3, 30% 7, 0, 0% 4, 0, 0%

Duff/soil 8, 2, 25% 8, 1, 13% 9, 0, 0% 6, 0, 0%

Chi-square: 32.74, critical value: 7.26 (alpha = 0.05, df = 15).

 Major impact (157 total stems, 87 dead, 55.4%)

Litter 16, 13, 81% 14, 13, 93% 12, 5, 42% 5, 2, 40%

Litter/duff 18, 16, 89% 11, 8, 73% 9, 5, 56% 7, 1, 14%

Duff 14, 11, 79% 7, 5, 71% 5, 2, 40% 5, 0, 0%

Duff/soil 8, 4, 50% 10, 2, 20% 12, 0, 0% 4, 0, 0%

Chi-square: 26.72, critical value: 7.26 (alpha = 0.05, df = 15).

a The first number in each column is the total number of stems before the

prescribed fires, the second number is the number of dead stems after the

prescribed fires, and the third is the proportion of stems killed.
126

Four other classes, occupying the upper-middle range of

RCD/RCL classes, also contained some dead stems, but

not to the same extent of the two smallest classes. The

lower-middle and largest/deepest RCD/RCL classes contained no dead stems. Also, the dead stems were primarily

yellow-poplar. Only a few red maple, hickory, and oak

seedlings failed to sprout.

In the moderate-impact level, 62 of the 135 (45.9 percent)

tagged stems never sprouted (table 3). Again, these were

concentrated in the two smallest/shallowest RCD/RCL cells

(<0.25/litter and <0.25/litter-duff) which had nearly 100 percent mortality, and the three adjacent intermediate RCD/

RCL classes, which had mortality greater than 50 percent.

As RCD and RCL increased, mortality decreased and no

mortality occurred to stems in the largest/deepest RCD/

RCL classes. Yellow-poplar and red maple constituted the

majority of dead stems, but oak and hickory also were

killed, especially in the smallest/shallowest RCD/RCL

classes.

In the major impact group, 87 of the 157 (55.4 percent)

tagged stems never sprouted (table 3). Only the largest/

deepest RCD/RCL groups (0.51-0.75/duff-soil, >0.75/duff,

and >0.75/duff-soil) had no mortality, while the smallest/

shallowest groupings (<0.25/litter, <0.25/litter-duff, <0.25/

duff, 0.25-0.50/litter, and 0.25-0.50/litter-duff) had almost

100 percent mortality. The remaining eight groups were

split between four having greater than 50 percent mortality

and four with less than 50 percent mortality. Nearly all

yellow-poplar died in this impact grouping as did approximately 50 percent of hickory, oak, and red maple.

DISCUSSION

Previous research has shown the importance of season-ofburn and fire severity as factors influencing the response of

hardwood regeneration to fire (Brose and others 1999a,

Brose and Van Lear 1998). This study adds root collar

diameter and root collar location as significant explanatory

factors. The stems with the shallowest and smallest roots

sprouted in far fewer numbers after the fires than stems

with deeper and larger roots (table 3). Species seemed

inconsequential as hickory and oak seedlings with shallow

and small roots were as susceptible to fires as comparable

red maple and yellow-poplar. The reverse also was true as

large, deep-rooted maples and poplars sprouted after the

fires, as well as similar oaks and hickories.

Species differed in distribution among the RCD/RCL classes

(table 2). While generally all species were found in all cells,

yellow-poplar dominated the smallest/shallowest ones,

while oak and hickory dominated the largest/deepest

classes. Red maples occurred most often in the intermediate RCD/RCL cells. Consequently, there were differing

species responses to the fires and this was a function of at

least four factors: season-of-burn, fire severity, root collar

diameter, and root collar location.

This study also provides insight into the disparate results

among many of the early fire/hardwood studies. Root collar

location and diameter of the regeneration usually were not

determined and fire severity often was ignored or considered equal throughout the burn area. Without knowing

these factors, predicting or understanding the outcome of a

fire is virtually impossible. One can imagine a high-severity,

growing-season fire annihilating a newly established cohort

of oak seedlings arising from unburied acorns (shallow/

small roots) while older, well-established red maple regeneration (somewhat deep/large roots) is able to sprout. A

comparable fire in well-established oak reproduction (deep/

large roots) and new red maple seedlings (shallow/small

roots) would probably produce opposite results. Thus, fire

studies that do not account for these important root characteristics could reach opposite conclusions about fire

effects on oak and red maple regeneration.

The root collar diameter and location differences between

oak/hickory and red maple/yellow-poplar (table 2) are a

result of their silvics. Hickory nuts and acorns have hypogeal

germination, i.e., cotyledons remain in the shell and serve

as a belowground energy source for seedling development.

Red maple and yellow-poplar seeds have epigeal germination, i.e., cotyledons emerge and rise above the shell to

form the first photosynthetic leaves. This difference in germination strategy places hickory and oak seedlings’ root

collar, and the accompanying dormant buds, lower than that

of red maple and yellow-poplar.

This basic difference in germination strategy is accentuated

by wildlife. Hickory nuts and acorns are routinely buried an

inch or more into the forest floor by birds and small mammals

while seeds from red maple and yellow-poplar typically are

not cached. Thus, a hickory or oak seedling generally will

have a deeper root collar than a red maple or yellow-poplar

seedling because of seed burial and hypogeal germination.

Another important silvical difference between hickory/oak

and red maple/yellow-poplar reproduction is the developmental rate of the root system. Upon germinating, oaks and

hickories send a strong radicle deep into the soil to establish a taproot and emphasize root development over stem

growth (Kelty 1988, Kolb and others 1990). Red maple and

yellow-poplar take the opposite approach; root development is sacrificed to promote rapid stem growth. Thus,

hickory and oak regeneration usually are shorter than their

competitors, but have larger root systems. It is these two

silvical characteristics, hypogeal germination and emphasis

on root development, and seed burial by wildlife that allows

hickory and oak regeneration to be favored over reproduction of their competitors in a periodic fire regime.

An important management consideration evident from this

study is the need to withhold fire, and possibly harvesting,

too, when advanced reproduction is relatively small. Seedlings with root collars less than 0.25 in. diameter exhibit

significantly greater mortality after a prescribed fire than

reproduction with larger root collars. Treatment should be

delayed a couple of years to allow newly established oak

seedlings to grow large enough roots to survive a fire or

other forest-floor disturbance.

ACKNOWLEDGMENTS

The authors acknowledge all the support provided by the

Virginia Department of Game and Inland Fisheries, especially Patrick Keyser, without which this project would not

have been possible. The authors also thank Gary Miller,
127

Steve Horsley, Thomas Schuler, and Susan Stout for their

efforts in reviewing earlier drafts of this manuscript.

LITERATURE CITED

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advance regeneration to seasonal prescribed fires in oakdominated shelterwood stands. Canadian Journal of Forest

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Brose, P.H.; Van Lear, D.H. 1999. Effects of seasonal prescribed

fires on residual overstory trees in oak-dominated shelterwood

stands. Southern Journal of Applied Forestry. 23(2): 88-93.

Brose, P.H.; Van Lear, D.H.; Cooper, R. 1999a. Using shelterwood

harvests and prescribed fire to regenerate oak stands on

productive upland sites. Forest Ecology and Management. 113:

125-141.

Brose, P.H.; Van Lear, D.H.; Keyser, P.D. 1999b. A shelterwoodburn technique for regenerating productive upland oak sites in

the piedmont region. Southern Journal of Applied Forestry.

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Brown, J.H. 1960. The role of fire in altering species composition

of forests in Rhode Island. Ecology. 41: 310-316.

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material. Gen. Tech. Rep. INT-16. Ogden, UT: U.S. Department

of Agriculture, Forest Service, Intermountain Forest and Range

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Carvell, K.L.; Maxey, W.R. 1969. Wildfire destroys! West Virginia

Agric. and Forest Exp. Stat. Bull. 2: 4-5, 12.

Johnson, P.S. 1974. Survival and growth of northern red oak

seedlings following a prescribed burn. Resource Note NC-177.

St. Paul, MN: U.S. Department of Agriculture, Forest Service,

North Central Forest Experiment Station. 6 p.

Kelty, M.J. 1988. Sources of hardwood regeneration and factors

that influence these sources. In Smith, H.C.; Perkey, A.W.;

Williams, E. editors. Guidelines for regenerating Appalachian

hardwood stands; 1988 May 24-26; Morgantown, WV: West

Virginia University Office of Publications: 17-30.

Keyser, P.D.; Brose, P.H.; Van Lear, D.H.; Burtner, K.M. 1996.

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preliminary trials. In: Wadsworth, K.; McCabe, R., editors.

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Resources Conference. March 10-12; Tulsa, OK: Wildlife

Management Institute 61: 215-219.

Kolb, T.E.; Steiner, K.C.; McCormick, L.H.; Bowersox, T.W. 1990.

Growth response of northern red oak and yellow-poplar seedlings to light, soil moisture, and nutrients in relation to ecological

strategy. Forest Ecology and Management. 38: 65-78.

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red oak reproduction in the Southern Appalachians. Forest

Science 36(4): 908-916.

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including wildfire and prescribed burning, on the regeneration

of oaks in Indiana. Stat. Bull. 612. West Lafayette, IN: Purdue

University Department of Forestry and Natural Resources. 45 p.

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methods and data analysis. Belmont, CA: Wadsworth

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regeneration in the Southern Appalachians. Resour. Pap. 30.

Atlanta, GA: Georgia Forestry Commission. 12 p.

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128

INTRODUCTION

Temporal and spatial differences in the frequency of fire

effect ecosystem structure and function. In many fire regimes

non-human ignitions are overwhelmed by anthropogenic

ignitions. Consequently, human population density, culture,

and topography control ignition in these fire regimes affect

the long-term disturbance frequency and species composition. These factors can be quantitatively used to predict the

frequency of fire in ecosystems. The interactions of fuels,

ignitions, and topography as they affect the fire regime over

a period of 300 years can be derived from analyses of fire

history data.

The scale, frequency, and legacy of disturbance regimes

and their effects on the distribution of forest species also

have important management, policy, and political implications. Debates about even-aged versus uneven-aged management, or no timber harvesting often hinge on what is

natural, or what was the pre-European disturbance regime.

Managers and policy makers are often interested in mimicking natural disturbance regimes with silvicultural prescriptions to foster native plant and animal species diversity

(Loucks 1970). The species composition of Ozark forest

ecosystems is a legacy of their long-term disturbance

regimes. Thus, fire regimes and fire frequencies are associated with the abundance of many species of reptiles, birds,

fungi, and plants in the Ozarks. Knowledge of these regimes

and their effects is valuable for understanding present-day

forest species composition and structure. We show the

long-term affects of anthropogenic disturbance and topographic roughness on forests, flora, and fauna using data

from the Missouri Ozark Forest Ecosystem Project (MOFEP),

a long-term study initiated to quantify forest management

effects on flora and fauna (Brookshire and others 1997;

Brookshire and Hauser, 1993). The goal of this paper is to

illustrate how anthropogenic disturbance and topography

have been major factors affecting disturbance frequency at

the MOFEP sites and that historic disturbance regimes

have a legacy that continues to affect contemporary plant

and animal distributions today.

FIRE HISTORY SUMMARY

The three important factors that determine fire regimes in

oak-dominated ecosystems are topographic roughness,

human population density, and culture. Specifically, the

roughness of the topography around a site mitigates the

propagation of disturbance related factors, such as fire,

logging, and human travel into a site. Topographic roughness is positively correlated with the length of mean fire

intervals. Consequently, fires are less frequent in rough

than in flat terrain, especially during periods of limited

anthropogenic ignitions (fig. 1). The strength and direction

of the topographic effect diminishes as the spatial and

temporal frequency of anthropogenic ignitions increases to

a point of pyro-saturation (ignitions occur throughout the

landscape and fuels are burned as soon as they are able to

support the spread of a fire). Since topography generally

changes through time very slowly, its influence on fire

regimes is not only long-term but dates to long before the

first effects of human ignitions.

Fire has been an integral tool in the lives of humans for

many thousands of years. Thus, humans are a potential

and dynamic source of ignition, when and wherever they

are present and irrespective of whether landscape burning

is promoted (Pyne 1982, 1995) or suppressed (Westin 1992).

The early records of fire history support the idea that fire

frequency is a function of potential human ignitions. Fire

frequency has been correlated with human population in a

number of studies (Dey and Guyette 2000, Guyette and

Dey 1997, Guyette and others 2002). The positive relationship between population density and fire frequency diminishes as ignitions become more frequent and fuels fail to

accumulate. As population density increases further, fire

frequency lessens due to change in land use and fire

suppression.

Cultural values have influenced wildland fire use and

suppression in different ways through time. Historically fire

was used to improve travel, for hunting wild game, to

THE EFFECTS OF HUMANS AND TOPOGRAPHY ON WILDLAND FIRE,

FORESTS, AND SPECIES ABUNDANCE

Richard P. Guyette and Daniel C. Dey1

1 Research Associate Professor and Research Forester, The School of Natural Resources, University of Missouri, Columbia, MO 65211,

respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Ignitions, fuels, topography, and climate interact through time to create temporal and spatial differences in the

frequency of fire, which, in turn, affects ecosystem structure and function. In many ecosystems non-human ignitions are

overwhelmed by anthropogenic ignitions. Human population density, culture, and topographic factors are quantitatively

related to fire regimes and the long-term pattern in fire frequency and species composition. These factors can be

quantitatively related and used to reconstruct and predict the frequency of fire in ecosystems and to identify changing

factors involved in anthropogenic fire regimes. Quantitative fire histories from oak-pine sites in Arkansas, Indiana,

Missouri, and Ontario are used to examine patterns of interaction in fuels, ignitions, and topography over a period of 300

years. Fire regimes and fire frequencies are associated with the abundance of many species of reptiles, birds, fungi, and

plants. Human population density and topographic roughness are master variables in understanding temporal and spatial

differences in fire regimes and their effects on ecosystems.
129

promote nut and berry production, to prepare sites for agriculture, to improve browsing and grazing conditions, etc.

But as a timber economy developed, and people built homes

in the hinterlands, suppressing fire became a necessity. In

the modern era, cultural values have become the most

important factors controlling fire frequency as increasing

population density increases the risk of wild fire to human

safety and economics. Good pasture may require burning

while defect free timber may require fire suppression. Unlike

incidental anthropogenic ignitions (proxy: human population

density), which stem directly from basic human requirements

for cooking, transport, warmth and safety, value oriented

cultural constraints on wildland fire originate from our societies economic system. This includes fire suppression for

perceived and real safety as well as prescribed fire for

ecosystem diversity, safety, and silvicultural purposes. The

artifact of fire suppression (the human separation of ignition

and fuels) creates its own dangers especially since fuel and

economic conditions can be highly variable through time.

LONG-TERM LEGACY OF FIRE, DISTURBANCE,

AND SPECIES GROUPS

Landscape level fire histories and species population data

allow for the study of species abundance, distribution, and

beta diversity within a region. Species groups are sensitive

to the long-term effects of fire and forest disturbance as

shown by the data collected on a wide array of species as

part of the Missouri Ozarks Forest Ecosystem Project

(Brookshire and Shifley 1997). Data on plant and animal

abundances (Kabrick and others 1997, Bruhn and others

1997, Clawson and others 1997, Grabner and others 1997,

Renkin 1997, Fantz and Renken 1997) at nine sites in the

Ozarks are associated with regional differences in the historic fire and disturbance regimes as quantified by an index

of disturbance (Guyette and Kabrick, 2002). Disturbance

interval indices are correlated with the abundance of tree

species, small mammals, reptiles, amphibians, birds, herbaceous plants, fungi, oak species in the overstory, and ground

flora (fig. 2). Trees, reptiles, birds, herbaceous plants, and

Armillaria species, as groups, all show sensitivity to longterm disturbance regimes. This may be a positive or negative association with fire and disturbance. Amphibians show

a lower sensitivity to disturbance. The low sensitivity of

amphibians to disturbance may be explained by their subterranean habitat (e.g., salamanders), which may buffer

them from aboveground disturbances and by the limiting

effects on populations of scarce breeding habitat (water

bodies) in the MOFEP study area.

Fire and disturbance result in changes in the distribution of

light and spatial structure of forests that, in turn, regulates

microclimate (i.e., light, temperature, humidity and moisture). Species have adapted to niches created by varying

frequencies of disturbance. In the southeastern Ozarks,

Figure 1—Landscape roughness and human population are major factors in disturbance

regimes. Here, mean fire intervals are mapped for the period 1700-1780 in the MOFEP study

region. Fire intervals are based on the model: MFI = -442.1 + (449.9 x topo) -(0.001 x pop),

where MFI is the mean fire interval, topo is an Index of topographic roughness, pop is the

natural log of human population density times the square of river mile (Guyette and Dey 2000).

Numbers are site designations and locations for the nine MOFEP sites.
130

several closely related species (fig. 2) are associated with

very different frequencies of disturbance in the same region.

The abundances of some closely related (in the same genus)

trees, birds, and fungi (Armillaria spp.) have contrasting

correlations with the frequency of disturbance (table 1).

Figure 2—The association between fire and disturbance and the abundance of 75 species by group. Species near a correlation

of 1 on the y-axis are strongly and negatively associated with frequent disturbances. Species near a correlation of -1 on the yaxis are strongly and positively associated with the frequent disturbances. Species near a correlation of 0 on the y-axis are not

strongly associated with the frequency of disturbance. Significant (p < 0.05) correlations for a single species-disturbance test are

greater than 0.60 or less than -0.60. While the power of an individual species test is low (only 9 sites), differences in the

sensitivity of species groups to disturbance are evident.

Post oak (Quercus stellata), summer tanagers (Piranga

rubra), and Armillaria mellea are found at sites with frequent

disturbance while white oak (Quercus alba), scarlet tanagers

(Piranga olivacea), and Armillaria gallica are found in

forests with less frequent canopy disturbance.

MOFEP data: Kabrick and others 1997, Fantz and

Renken 1997, Renken 1997, Clawson and others

1997, Grabner and others 1997, and Bruhn and others,

Guyette and Kabrick 2002.

Table 1—Correlation coefficients among genus pairs and

disturbance illustrate how closely related species at the Missouri

Ozark Forest Ecosystem Project sites are often very different in

their association with long-term disturbance frequencya

Genus LS species, r ES species, r Differenceb, r

Quercus alba, +0.92 stellata, -0.96 alba-stellata, +0.97

Armillaria gallica, +0.88 mellea, -0.49 gallica-mellea, +0.84

Piranga olivacea, +0.68 rubra, -0.55 olivacea-rubra, +0.79

a Correlation coefficients are for the disturbance interval index (Guyette and

Kabrick 2002) and species abundances at the nine sites. Note the opposite

signs of correlation coefficients by different species within the same genus.

b Difference is the abundances of early successional (ES) species subtracted

from late successional (LS) species. Significant (P < 0.05) correlations are

shown in bold.

Source: Bruhn and others (1997); Clawson and others (1997); Guyette and

others, in press; Kabrick and others (1997).
131

ACKNOWLEDGMENTS

The authors thank the Missouri Department of Conservation,

the Missouri Ozark Forest Ecosystem Project, the National

Park Service, and the USDA Forest Service for their

support of this research. In addition, the authors thank

J. Bruhn, R. Clawson, J. Grabner, J. Kabrick, R. Renkin,

J. Faaborg, D. Fantz, and D. Hamilton for the collection of

MOFEP data. Also, we want to thank Mike Stambaugh for

producing the map of fire intervals.

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G.R. eds. Proceedings of the 9th central hardwood forest conference. Gen. Tech. Rep. NC-161. St. Paul, MN: U.S. Department

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132

INTRODUCTION

Wildfires have influenced Ozark forests, prairies, and wildlife for centuries (Chandler and others 1983). Speculation

on the fire history of many areas in the southwestern Ozarks

has been difficult because of the anthropogenic influence

(Westin 1992) on these fire regimes and the highly variable

nature of fuels and vegetation. Knowledge of fire history

provides an ecological basis for restoring fire disturbance

and developing silvicultural prescriptions that use fire to

favor native communities. The objective of this study is to

document a fire regime in a landscape with the potential for

diverse vegetative assemblages, both in time and space,

which includes closed canopy oak forests, savannas,

prairies, and fens. We present a 292-year fire history based

on dendrochronological analyses of fire scars for a site

near the West Fork of the Spring River on the White Ranch

State Forest, Howell County, Missouri.

METHODS

The study area is located (36° 32′ N, 91° 52′ W) along the

northeastern slopes of the West Fork of the Spring River in

the White Ranch State Forest, which is managed by the

Missouri Department of Conservation. The landscape in the

area is gently rolling with about 37 m of elevation change

per km. The study site is about 1 km2 in area and is presently

covered by a complex mosaic of oak forests in the uplands

and slopes, savannas and glades along slopes, and grassy

fens in low lands.

Cross-sections were cut within 20 cm of ground level from

44 post oaks in the study area. Trees with solid boles were

selected for cutting by sounding with a long handled ball

pin hammer. The majority of the post oaks at the study site

were hollow. Of the 44 trees cut only 35 cross-sections

were used in identifying fire scar years. Nine trees sampled

were deleted from analysis because heart rot, indistinct

rings, or injury made precise dating of fire scars impossible.

Trees ranged in age from 12 to 300 years or more.

Fire scars in this study are defined as basal injuries, which

have killed cambial cells, exhibit a localized cambial growth

response, and contain callus tissue. Fire scars also are

associated with abnormal tyloses formation, general growth

responses (from release or crown damage), and false rings.

Often there was no external evidence that a post oak tree

had a fire scar, although there were many hollow trees with

external fire scars in the surrounding area.

Many other types of scars were present on the crosssections. Damage caused by pin worms and bark scarrers

was not common but it was distinctive and not easily

confused with fire scars. Lightning scars were identified by

their presence in sections well above the ground.

Fire wounds from ground level sections of post oak were

used to reconstruct fire frequency. All fire dates were designated as the year of growth response to the injury. Thus, a

scar that we dated to 1770 may have been caused by a fire

that occurred anytime in the previous dormant season,

approximately September 1769 to April 1770. This is of

particular importance when considering if fires occur more

frequently during drought years as indicated by ring width.

Dendrochronology uses the pattern in tree-rings caused by

climate to date annual growth increments (Stokes and Smiley

1968). This enables accuracy in dating to the year, serves

as a check on ring counts from live trees, and allows for the

dating of wood of unknown age. Post oaks in this study were

dated using a post oak chronology from Clayton Ridge

(Stahle and others 1985) on the Rolla-Houston Ranger

District of the Mark Twain National Forest. Annual rings

were dated using skeleton plots of ring-widths, measured

ring-width series, signature years, and ring counts.

Post oak is probably the most fire resistant species in the

Ozarks, with the possible exception of shortleaf pine. The

determination of fire frequency is difficult using post oak

FIRE HISTORY OF A FOREST, SAVANNA, AND

FEN MOSAIC AT WHITE RANCH STATE FOREST

Daniel C. Dey, Richard P. Guyette, and Michael C. Stambaugh1

1 Research Forester, USDA Forest Service, North Central Research Station, Columbia, MO 65211; Research Associate Professor and

Research Associate, The School of Natural Resources, University of Missouri, Columbia, MO 65211, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—We present the fire history of a 1-km2 area that is a mosaic of oak forest, savanna, and fen on the White

Ranch State Forest, Howell County, Missouri. We dated 135 fire scars on 35 cross-sections of post oak (Quercus stellata)

trees and constructed a fire chronology dating from 1705 to 1997. Mean fire return intervals by periods were 3.7 years

(1705 to 1830), 7.6 years (1831 to 1960), and 3.6 years (1961 to 1997). Fire frequency was positively correlated (r = 0.53,

p <0.01) with the expansion and migration of the Osage Tribe from 1710 to 1830. Later, between 1831 and 1900,

exponential increases in Euro-American population density were negatively correlated (r = -0.64, p <0.05) with fire

frequency. Fires were more likely to have occurred in drought years before 1830 than after 1830. Droughts after 1830

were related to the percent of trees scarred during years with evidence of fire.
133

because this species is very resistant to scarring by low

intensity fires. Paulsell (1957) noted that only 10 percent of

the post oaks were scarred in annually burned plots, whereas 23 percent of the post oaks were scarred in the periodic

burn plots. On the periodically burned plots, litter build up

may have resulted in greater fire intensities that were capable of scarring more trees. This relationship between fuel

buildup, fire intensity, and ability to scar trees may result in

an under estimate of the number of fires in post oaks growing under low intensity surface fire regimes. More important,

however, is the under estimation of fire frequency due to

scarring resistance in post oak. For example, only one scar

may be produced for every four to ten exposures to low

intensity fires. Thus, mean fire intervals determined from

fire scars on oak trees should be viewed as minimum fire

return intervals.

We also attempted to sample trees in various size classes

to minimize the effect that tree size has on scarring and to

increase the accuracy of the composite fire chronology.

Further, we constructed a composite fire scar chronology

(Stokes and Dieterich 1980) from all of the 135 fire scars

identified on the 35 dated cross-sections. Percent of trees

scarred in any given fire year was determined by dividing

the number of sample trees with ring records in a fire year

by the number of trees with scars and multiplying by 100.

RESULTS AND DISCUSSION

Fire Frequency

A fire scar chronology composed of all the fire scars from

the sample of 35 post oaks dated is given in figure 1. The

frequency of fire, as mean fire return intervals (MFI), is

summarized for various historic or cultural periods over the

last 292 years in the 1-km2 study area in table 1. The mean

fire return interval was similar for the Native American Period

(1711 to 1830) and the Modern Period (1961 to 1997), but

the fire scar record indicates that fires burned less frequently

during Euro-American settlement and development (1831

to 1960). The percent of trees scarred was significantly

different (t=5.1, p <0.0001) for the two periods, 1711 to

1830 and 1831 to 1960. The mean percent of trees scarred

during the Native American and Modern Periods was four to

six times that of the period of Euro-American settlement

and development (table 1). Fire frequency and percent of

trees scarred were not significantly different (t=1.78,p=0.08)

between the two periods, 1711 to 1830 and 1961 to 1997

because of the high variance and short duration of the

Modern period. However, there certainly could be

significant ecological differences resulting from fires during

these two periods. Mean fire return intervals (MFI) at White

Ranch State Forest are similar to those at three other study

sites (table 2) that also have oak forest and savanna

vegetation (Guyette and Cutter 1991; Cutter and Guyette

1994; Guyette and McGinnes 1982) in the Missouri Ozarks.

Figure 1—Composite fire scar chronology and percent of trees scarred by fire year for the study site at

White Ranch State Forest, Howell County, MO.

Table 1—Mean fire return intervals by historic periods

 Trees scarred

 (percent)

Scar

Historic period MFI Range All years years

 - - years - -

Native American

(1711–1830) 3.7 1 – 13 4.3a 17.5a

Euro-American

settlement

(1831–1960) 7.6 2 – 17 0.7b 5.6b

Modern agriculture

(1961–97) 3.6 1 – 7 3.4ab 12.8ab

All periods (1711–1997) 4.9 1 – 17 2.6 13.2

Mean fire return intervals (MFI) are for the presence of fire (a fire

scar on at least 1 of 35 samples) in all or part of the 1-km2 study

area.

Statistics with the same superscript letters on different lines are

not significantly different (α = 0.05).

60

50

40

30

20

10

 0

1700 1750 1800 1850 1900 1950 2000

Calendar year

Trees scarred (percent)
134

Climate, Fire Occurrence, and Fire Severity

The mean reconstructed Palmer Hydrologic Drought Index

(Cleaveland and Stahle 1996) for all fire years before 1830

was -0.66 compared to a mean of +0.32 for all fire years

after 1830 (table 3). Before 1830, drought was an important

factor in the occurrence of fire years, but after 1830 fires

burned in years of above average precipitation. This may

be because drought increased the probability of fires spreading to the study site or because Native Americans chose the

most severe fire weather to ignite fires. Both factors probably contributed to the occurrence of fires in years of growing

season drought before 1830. Others (e.g., Sutherland 1997)

have noted the general lack of correspondence between

fire years with drought years after 1830.

When the percent of trees scarred is calculated based on

those years with evidence of fire, there is no significant correlation between growing season drought and the percent

of trees scarred before 1830, but there is a significant correlation (r = -0.47, p = 0.01) between growing season drought

and the percent of trees scarred after 1830. This indicates

that before 1830 growing season droughts had more of an

effect on the year of occurrence of a fire and little effect on

the severity of fire at the study site. The opposite relationship occurs after 1830 when growing season drought does

not affect the year of occurrence of fire but is related to the

severity (percent of trees scarred) of fire.

Cultural Interpretations

In 1818, Schoolcraft (1821) observed several abandoned

“Indian camps” just below the confluence of Bryant Creek

and the North Fork of the White River. These camps were

west of the study site separated by 40 km of gently rolling

terrain. The study site also lies near the confluence of two

streams, the West and South Forks of the Spring River.

Schoolcraft also commented on the abundance of bear, elk,

deer, and beaver in the area. Thus, geographic location at

the confluence of rivers, the distance from sites of known

Native American occupation, and the abundance of game

suggests that there was reason for a human population

within the vicinity of the study site before Euro-American

settlement of the area.

Population, Land Use, and Fire

Population and agriculture are two factors that greatly affect

anthropogenic fire regimes. Fire history at the White Ranch

State Forest shows a changing relationship to these important factors. Fire frequency at the study site was positively

correlated (r=0.53, p <0.01) with the expansion (Wiegers

1985) and migration (Wolferman 1997) of the Osage Tribe

(Marriott 1974) between 1710 to 1830 (table 4). During the

latter part of this period, Shawnee, Delaware, and Cherokee

were migrating through the area (Weslager 1978) and they

may have contributed to the frequency of fire at the study

site. A positive relationship between fire frequency and

human population makes sense (Guyette and Cutter 1997)

because more people usually cause more ignitions, especially at low levels of human population density. In contrast,

exponential increases in Euro-American population density

between 1830 and 1900 were negatively correlated (r = -0.63,

p <0.05) with the scarring of trees. How human population

density during this period (1830 to 1900) affected the frequency of fire is not well understood and is addressed in

the next section.

Population density is not significantly correlated with the

percent of trees scarred during the 1900s. This relationship

is expected as population density increases because a

complex of cultural factors controls the frequency of fire.

Anthropogenic fire is affected by changes in land use, in

the type of ownership, in the price of timber and the price of

beef, the value of real estate, and by the adoption of fire

suppression policies. Since 1960, there has been a

Table 2—A comparison of mean fire return intervals

at White Ranch State Forest, Caney Mountain

Wildlife Refuge, Laclede County, and Cedar Glades

Period WRSF CMWR LACCO CEDAR

 - - - - - - - - - - - - years - - - - - - - - - - - -

1710–1830 3.7 4.8 3.0 3.3

1831–1980 7.6 6.9 12.5 9.4

WRSF = White Ranch State Forest; CMWR = Caney Mountain

Wildlife Refuge; LACCO = Laclede County; CEDAR = Cedar

Glades.

All sites are more than 50 km from the White Ranch State

Forest.

Table 3—Drought and the percent of trees scarred by historic period

Period PHDI %TREE X PHDI PHDI

(%TREE > 6)

Native American

(1711–1830) -0.66 (n = 31) r = -0.47 (p = 0.01) -0.97 (n = 24)

Euro-American

(1831–1997) +0.32 (n = 24) r = +0.04 (p = 0.80) -1.22 (n = 7)

%TREE = percent of trees scarred; PHDI = Palmer Hydrologic Drought Index.

Negative values of the reconstructed Palmer Hydrologic Drought Index represent

relatively dry periods (Cleavland and Stahle 1996). Correlations are given for the

percent of trees scarred and the PHDI (%TREE X PHDI). The PHDI is also given

for only those years with multiple scarring of trees (percent trees scarred > 6).
135

decrease in the percent of trees scarred and an increase

human population density. The number of cattle on farms

follows the same general trends as human population and

its correlation with the percent of trees scarred (table 4).

Trends in the Fire Frequency of Forests and

Savannas

The trends in fire scarring of trees at the White Ranch State

Forest are similar to patterns observed at other fire history

sites in oak forest-savanna mosaics in southwestern

Missouri (fig. 2). These sites include a site in the redcedar

glades in Douglas County (Guyette and McGinnes 1982), a

site on an oak-hickory ridge near the Gasconade River in

Laclede County, (Cutter and Guyette 1994), and a site in a

post oak forest-savanna at the Caney Mountain Wildlife

Refuge (Guyette and Cutter 1991). The trend at these sites

has been an increase in fire frequency before 1780, an

increase in fire frequency and the percent of trees scarred

Table 4—Correlations among population density, cattle density, and

the percent of trees scarred (an 11-year moving average) by periods

1711–1830 1830–1900 1900–97 1960–90

Human population

density 0.53 -0.63 0.08 -0.73

Cattle on farms — -0.52 0.07 -0.74

Cattle data and the correlation for the 1830 to 1900 period are based on the State

cattle population from 1867 to 1900. Positive and negative correlations indicate

that trends in the percent of trees scarred are coincident with changes in human

and cattle production.

Figure 2—Patterns in fire scarring of post oaks at White Ranch State Forest compared with other fire history sites from

oak forests and savannas throughout the Ozark Highlands in Missouri.

between 1780 and 1820, and then a steady decline in fire

frequency ending circa 1900. A notable exception in fire

trends at White Ranch State Forest is that the frequency of

fire increases between 1960 and 1997, and it is greater

than at the other sites, although differences are not

statistically significant.

Differences in the fire regime before and after 1830 may be

due to both a change in the frequency of fire and a change

in the intensity of fire. The difference in the percent of trees

scarred between the Native American period and the period

of Euro-American settlement and development could be the

result of a number of factors (table 5) that reduced the

scarring of trees. These might include changes in fuel

continuity, in vegetation type, in fuel characteristics, in

farming practices, in the density of large herbivores, in fire

frequency, and in the frequency and seasonality of human

ignitions.

Caney Mt.

White Ranch S. F.

Ava Glades

2.0 Laclede Co.

1.5

1.0

0.5

0.0

1750 1800 1850 1900 1950 2000

Calendar year

Scars per tree per decade
136

Post Oak Regeneration

The year of growth initiation for each post oak stem was

determined. No periods of regeneration stood out as

exceptional or different from the rest. This is in contrast to

an earlier study (Cutter and Guyette 1994) in which the

trees sampled indicated that the dominant overstory trees

had regenerated in a stand replacement event that resulted

in an even-aged overstory. Of the post oaks sampled, none

had pith dates (no stems regenerated) between 1815 and

1880, which can be characterized as a period of decline in

fire frequency, in percent of trees scarred in a fire year, and

in increased settlement and agricultural development.

However, because the sample trees were not randomly

selected, any inferences regarding stem initiation may give

a biased view of oak regeneration in relation to fire

disturbance.

CONCLUSIONS

1. Mean fire return intervals by periods were 3.7 years

(1705 to 1830), 7.6 years (1831 to 1960), and 3.6 years

(1961 to 1997). The percent of trees scarred is

significantly different (t=5.1, p <0.0001) for the two

periods 1705 to 1830 and 1831 to 1960. Since some

fires may not have scarred any of the sample trees,

these interval estimates are minimum fire return intervals

for the study area.

2. Population density is an important factor related to fire

frequency. Before 1830 fire frequency is positively

related to human population density, a source of

anthropogenic ignitions.

3. Later (1830 to 1900) population density is inversely

correlated with fire frequency as land use effects reduce

the frequency and severity of fires.

4. Fires were more likely to have occurred in drought years

before 1830 than after 1830.

5. Droughts are related to the percent of trees scarred after

1830 in years with evidence of fire.

6. Historical documentation of Native American populations

40 km west of the study site in the early 1800s indicates

anthropogenic ignitions maintained the level of fire

frequency documented before 1830.

7. The trends in fire frequency at White Ranch State Forest

are similar to those found at three other sites in the

Missouri Ozarks with areas of oak forest and savanna

vegetation.

8. A declining trend in the percent of trees scarred at White

Ranch State Forest between 1830 and 1900 is the

opposite of trends of increasing fire frequency found in

highly dissected and forested regions of the Ozarks such

as the Current River watershed.

9. Although a complete age structure was not determined

for the study forest, dates of stem initiation of the

dominant post oaks sampled do not indicate that this

was an even-aged forest originating from a stand

replacement type disturbance. Dominant post oaks

regenerated throughout the past 292 years resulting in

an irregular age structure of overstory oaks.

Regeneration of dominant post oaks was minimal during

a period in the fire chronology when fires burned less

frequently and with less intensity.

LITERATURE CITED

Chandler, C.; Cheney, P.; Thomas, P. [and others]. 1983. Fire in

forestry. Vol. I: Forest fire behavior and effects. New York:

Wiley-Interscience. 450 p.

Cleaveland, M.K.; Stahle, D.W. 1996. Variability of hydrologic

drought in the Ozark Highlands, 1680-1980. In: Tree rings,

environment, and humanity. Dean, J.S.; Meko, D.; Swetnam, T.,

eds. Radiocarbon. 43-50.

Cutter, B.E.; Guyette, R.P. 1994. Fire frequency on an oak-hickory

ridge top in Missouri. American Midland Naturalist 132: 393-398.

Guyette, R.P.; Cutter, B.E. 1991. Tree-ring analysis of fire history

of a post oak savanna in the Missouri Ozarks. Natural Areas

Journal 11: 93-99.

Guyette, R.P.; Cutter, B.E. 1997. Fire history, population, and

calcium cycling in the Current River watershed. In: Pallarydy,

S.G.; Cecich, R.A.; Garrett, H.E.; Johnson, P.S., eds.

Proceedings 11th Central Hardwood Forest Conference. 1997

March 23-26; Columbia, MO. USDA Forest Service, North

Central Forest Experiment Station GTR NC-188. 354-372.

Guyette, R.P.; McGinnes, E.A., Jr, 1982. Fire history of an Ozark

glade in Missouri. Transactions of the Missouri Academy of

Science 16: 85-93.

Marriott, A. 1974. Osage Indians II. New York: Garland Pub. Inc.

270 p.

Paulsell, L.K. 1957. Effects of burning on Ozark hardwood

timberlands. Columbia, MO: University of Missouri Agricultural

Experiment Station Bull. 640. 24 p.

Table 5—Possible factors influencing fire frequency and

the scarring of trees before and after 1830 in forestsavanna vegetation of the southwestern Ozarks

Before 1830

1 Fuel buildup during fire free intervals

facilitates fire spread and intensity

2 Fires in late summer and fall of year burn

hotter than spring fires

3 Warm season grasses create more volatile

fuels

4 Effects on fuels by herbivores limited

5 Few firebreaks facilitate continuous spread

of fire

6 Native Americans choose the most severe

fire weather for burning

After 1830

1 Fire intensity low from annual fuel reduction

by fire

2 Fires in spring cooler than fall fires

3 More cool-season grasses are less volatile

4 Fuel reduction and trampling by more large

herbivores

5 Increasing numbers of firebreaks, roads,

and fields

6 Fine prairie fuels replaced by slower

burning forest litter
137

Schoolcraft, H.R. 1821. Journal of a tour into the interior of

Missouri and Arkansaw, from Potosi, or Mine à Burton, in

Missouri Territory, in a south-west direction, toward the Rocky

Mountains: performed in the years 1818 and 1819. London:

Richard Phillips and Co. 102 p.

Stahle, D.W.; Hehr, J.G.; Hawks, G.G., Jr. [and others]. 1985.

Tree-ring chronologies for the Southcentral United States. TreeRing Laboratory and the Office of the State Climatologist,

Fayetteville, AR: Dept. of Geography, University of Arkansas.

135 p.

Stokes, M.A.; Dieterich, J.H. 1980. Proceedings of the fire history

workshop. General Technical Report RM-81, Ft. Collins, CO:

USDA Forest Service Rocky Mountain Forest and Range

Experiment Station. 142 p.

Stokes, M.A.; Smiley, T.L. 1968. Introduction to tree-ring dating.

Chicago, IL: University of Chicago Press. 73 p.

Sutherland, E.K. 1997. History of fire in a southern Ohio secondgrowth mixed-oak forest. In: Pallarydy, S.G.; Cecich, R.A.;

Garrett, H.E.; Johnson, P.S., eds. Proceedings 11th Central

Hardwood Forest Conference. USDA Forest Service, North

Central Forest Experiment Station GTR NC-188. 172-183.

Weslager, C.A. 1978. The Delaware Indian westward migration.

Wallingford, PA: Middle Atlantic Press. 266 p.

Westin, S. 1992. Wildfire in Missouri. Jefferson City, MO: Missouri

Department of Conservation. 161 p.

Wiegers, R.P. 1985. Osage culture change inferred from contact

and trade with the Caddo and the Pawnee. Columbia, MO:

University of Missouri. 229 p. Ph.D. dissertation.

Wolferman, K.C. 1997. The Osage in Missouri. Columbia, MO:

University of Missouri Press. 119 p.
138

INTRODUCTION

Plant strategy theory suggests that life history characteristics reflect growth and reproductive adaptations to population density, environmental disturbance, and stress (Grime

1979, Odum 1997). Species attributes and abundance

should correspond to predictions based on competitive

ability and maximizing fitness in a given disturbance environment. Thus, selection theory predicts that there should be

correlations between growth and reproductive variables

among species that are consistent with the species ability

to remain competitive and maximize fitness in a given

environment. The opposing strategies of r and K selective

forces (MacArthur and Wilson 1967) have been used to

explain persistence of species in given environments.

Generally, r-strategists are those that have a high rate of

reproduction and growth providing an advantage in acquiring resources made available through disturbance. A Kstrategist has characteristics that allow it to more effectively

compete for resources in communities that are near carrying capacity and where resources are predictable and

relatively favorable.

Many consider r- and K-selection theory to be valid but an

oversimplification (Crawley 1997) because it does not consider fitness attributes that are not influenced by population

density. We use this theory because it lends itself to linear

quantification among the species of a single genus whose

member’s life history strategies are similar in many respects.

Grime (1979) classifies life history traits into three dimensions based on the overriding factors of stress and disturbance. Using this classification a competitor (C) plant species

as one that persists in a low stress, low disturbance environment. A stress tolerator (S) exploits conditions of high stress

and low disturbance; and a ruderal (R) represents a reproductively driven strategy and persists in low stress and high

disturbance.

Oaks, members of the genus Quercus, represent the most

important hardwood species group both ecologically and

economically in North America. In addition to the 90 recognized species in North American (Flora Committee 1997)

there are at least 70 hybrids in Northeastern Forest

(Gleason and Cronquist 1991) and about 23 species in the

Central Hardwood Region (Nixon 1997). As a group, oaks

have wide ecological amplitude and can dominate highly

varied environments. Oaks may all be classified as competitors or stress tolerators, sensu Grime (1979), but are not

ruderal when compared to many tree species, e.g. Populus,

Salix, Robinia. Differences in life history strategies should

be especially clear within a genus such as Quercus, showing evolutionary divergence and speciation in response to

environmental factors including disturbance and stress.

The objective of this study is to provide an understanding of

how plant strategy theory can be quantified and evaluated

based on numerous variables. The specific hypotheses are:

(1) oak reproductive and growth characteristics are significantly correlated; (2) the distribution of these characteristics

among species is consistent with r and K life history strategies. Furthermore, we intend to create a preliminary oak r

and K Index for quantitative use and to use this index to

examine and possibly predict relationships among life

histories (the abundance of r and K attributes), disturbance

frequency, oak species abundance, and basal area at nine

sites in the Ozark Highlands of Missouri.

METHODS

We used data describing 13 oak species from the Central

Hardwoods Region: white oak (Quercus alba), post oak

(Quercus stellata), bur oak (Quercus macrocarpa), chinquapin oak (Quercus muehlenbergii), northern red oak (Quercus

rubra), black oak (Quercus velutina), scarlet oak (Quercus

coccinea), southern red oak (Quercus falcate), pin oak

(Quercus palustris), blackjack oak (Quercus marilandica),

swamp white oak (Quercus bicolor), overcup oak (Quercus

lyrata), and nuttal oak (Quercus texana). Variables and

sources are listed in table 1. Only species with available

data for all six characteristics can be used in the statistical

analysis, therefore this study explores only 13 species.

A PERSPECTIVE ON QUERCUS LIFE HISTORY CHARACTERISTICS

AND FOREST DISTURBANCE

Richard P. Guyette, Rose-Marie Muzika, John Kabrick, and Michael C. Stambaugh1

1 Research Associate Professor and Associate Professor, School of Natural Resources, University of Missouri, Columbia, MO; Research

Forester, USDA Forest Service, North Central Research Station, Columbia, MO; and Research Specialist, University of Missouri, Columbia

MO, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Plant strategy theory suggests that life history characteristics reflect growth and reproductive adaptations to

environmental disturbance. Species characteristics and abundance should correspond to predictions based on competitive ability and maximizing fitness in a given disturbance environment. A significant canonical correlation between oak

growth attributes (height growth, xylem permeability, shade tolerance) and reproductive attributes (longevity, acorn weight,

and the age to reproduction) based on published values indicates that the distribution of oak attributes among species is

consistent with r and K selection theory. Growth and reproductive attributes were used to calculate an index reflecting the

relative values of the r and K strategies of oak species. This index was used to examine changes in the dominance of oak

species at nine sites in the Ozarks. Changes in oak species dominance and differences in their landscape distributions

were consistent with predictions based on their r and K index values and estimates of forest disturbance.
139

Growth and Reproductive Characteristics

Data on oak growth and reproductive characteristics come

from a number of sources. Reproductive data on acorn

weight, age of reproduction and tree longevity were found

in Schopmeyer (1974), Foster and Ashe (1908), Miller and

Lamb (1985), Nixon (1997). Burns and Honkala (1990),

Brown and Panshin 1940, Panshin and ed Zeeuw (1970)

were sources of data for the growth-related physiological

attributes of shade tolerance and potential conductivity as

well as longevity, age of first reproduction. Height growth (in

feet) derived from median site index curves for oak species

were used to estimate the rate of height growth (Carmean

and others 1989).

Acorn weight is an important reproductive characteristic

because large acorn size confers a reproductive and competitive advantage to oaks in highly competitive environments

such as forests and prairies. Long and Jones (1996) found

that among 14 oak species larger acorns consistently produced larger seedlings. Large acorns probably represent a

K-strategy attribute as light, wind dispersed seeds - common

with trees of prodigious seed output- suggests an r-strategy.

We used the weight of an acorn in fractions of a pound in

all analyses.

Organisms that reproduce early in their life have an advantage in capturing resources in environments with high rates

of disturbance that may provide many opportunities for

reproduction. Early reproductive age is a r-strategy attribute

(Pianka 1999).

Longevity of individual trees confers a variety of selective

advantages, including reproduction, in that the trees will

have opportunities to reproduce over a longer period.

Competitive advantages of longevity are numerous also,

e.g. long term site occupation and exploitation of resources.

Long-lived species are generally considered K-strategists.

Rapid growth confers an advantage to species in capturing

resources in non-competitive environments with high rates

of disturbance, thus representing a r-selective attribute. We

used both height growth and potential stem nutrient transport as measures of growth potential. We used the reciprocal of height growth at 50 years in calculating the index to

match positive trends in shade tolerance and longitudinal

permeability among oak species.

The longitudinal permeability of tree stems effects stem

water transport and can limit the supply of water and nutrients to the crown (Kozlowski and others 1991) and thus

growth. Xylem permeability is conceptualized as a trade off

between safety and conductance (Lambers and others

1998). Increased conductance may maximize growth but

increases the risk of cavitations and negative physiological

effects. The cost of risky anatomical structure of the red oak

group corresponds to the r-strategy of many species that

maximize growth in response to competitive selection pressures. The red and white oaks have many xylem characteristics that differentiate the potential conductance (and thus

maximum growth) of these species groups such as vessel

element size, as tyloses formation in vessels, and distinct

heartwood-sapwood boundaries. For example, red oak

heartwood is about 100,000 times more permeable than

white oak heartwood (Siau 1971). Red oak vessel elements

are larger than those of white oak (Brown and Panshin

1940). We used a value of 1 for the white group and a

value of 2 for the red oak group to reflect differences in

potential growth due to xylem conductance.

Shade tolerance can confer a competitive advantage to

young oak trees under varying degrees of competition for

light. Shade tolerance classes (Burns and Honkala 1990)

were quantified as 1 for very intolerant, 2 for intolerant, 3

for intermediate, 4 for tolerant, and 5 for very tolerant.

Tolerance for growth under shady conditions is a K strategy

attribute.

Table 1—Oak species and their growth and reproductive characteristicsa

Species Acorns Age Longevity Height Shade Xylem Repro. Growth r&K

Quercus alba 3.11 40 300 54 3 2 1.46 0.65 1.06

Q. stellata 0.98 25 320 45 1 2 -0.30 -0.60 -0.45

Q. macrocarpa 4.98 35 340 35 4 2 2.77 2.89 2.83

Q. muehlenbergii 0.94 40 250 50 2 2 -0.20 0.07 -0.06

Q. rubra 2.98 25 130 55 3 1 -0.19 -0.41 -0.30

Q. velutina 1.52 20 175 62 3 1 -0.45 -0.53 -0.49

Q. coccinea 1.58 20 120 62 1 1 -0.54 -1.15 -0.84

Q. falcate 0.67 25 150 57 2 1 -0.62 -0.78 -0.70

Q. palustris 0.91 26 130 70 2 1 -0.59 -0.91 -0.75

Q. marilandica 0.94 20 200 30 2 1 -0.55 -0.18 -0.37

Q. bicolor 3.11 20 325 60 3 2 0.44 0.45 0.44

Q. lyrata 2.67 27 350 40 3 2 0.73 1.40 1.07

Q. texana 3.93 5 120 90 2 1 -0.63 -1.03 -0.83

a The column headings are species = oak genus, acorn = acorns weight (g), age = age of first reproduction,

longevity = estimated maximum tree age in years, height (growth rate) = median site index (feet) at 50 years (the

reciprocal was used in index calculations), shade = shade tolerance rating, xylem = wood conductance type, repro. =

normalized reproductive variable index, growth = normalized growth variable index, and r&K = r and K index value.

Acorn weight (1 pound per number of acorns) and the reciprocal of height were used in calculating indices.
140

R and K Index

We created an r and K index for oak species to examine

differences among oak species and to test this concept with

the spatial distribution of oak species and temporal change

in oak species abundance. The r and K indices were constructed for reproductive and growth related factors presented above and based on plant selection theory (Grime

1979). Three reproductive characteristics were multiplied:

(1) age of first acorn production (in years), (2) species

longevity (in years), (3) and acorn weight (acorns per lb.).

These values were then normalized (mean of 0 and a

standard deviation of 1) to create a reproductive index.

Three growth characteristics were multiplied: (1) height

growth at 50 years, (2) shade tolerance class, (3) and

heartwood permeability class. These values were then

normalized (mean of 0 and a standard deviation of 1) to

create a growth index. The mean of the reproductive and

growth indices is the r and K index.

Data for the abundance, distribution, and dominance of oak

species is derived from studies resulting from the Missouri

Ozark Forest Ecosystem Project (MOFEP) (Brookshire and

Shifley 1997, Kabrick and others 1997). This project is an

experiment to assess the landscape level impacts of management practices on forest ecosystems including wildlife,

plants, and forest productivity.

Data describing disturbance frequency, fire frequency, and

the development and values of disturbance indices are

taken from Guyette and Kabrick (2002). Fire frequency was

estimated with regressions developed from fire scar chronologies at 26 sites in the Current River watershed (Guyette

and others 2002, Guyette and Dey 2000). Mean fire interval

estimates in this study are for the period of maximum variation in fire frequency among sites, the years 1700 to 1850.

Only five of the 13 oak species (white, post, black, scarlet

and red oak) grow at the MOFEP study sites, thus only five

oak species could be used in testing predictions made by

the r and K index approach about how species oak may be

related to disturbance at these sites.

RESULTS

Oak reproductive and growth characteristics were significantly correlated using two methods. Pearson correlation

analysis of reproductive and growth indices showed significance (r = 0.94, p <0.001) among oak species attributes

(fig. 1). Multivariate analysis using among growth and reproductive resulted in a canonical correlation coefficient of 0.98

(p <0.01). All individual growth and reproductive variables

were positively correlated but only acorn weight versus

shade tolerance (r = 0.54, p = 0.03) and longevity versus

permeability (r = 0.94, p <0.01) were strongly correlated.

Correlation analyses indicate that the distribution of all

measured characteristics among species is consistent with

the theoretical predictions of r and K life history strategies.

Figure 1—Scatter plot of the relationship between indices of the reproductive and growth

strategies of 13 oak species (see table 1 for details).
141

The distribution of oak species at the nine large (> 314 ha)

sites (Missouri Ozark Forest Ecosystem Project) was

related to their r and K index values and the long-term

disturbance histories of the sites (fig. 2). The abundance of

five oak species that grow at these sites was weighted by

Figure 2—Scatter plot illustrating the relationship between the

abundance of oak strategies (number oak by species x r and K

index, summed by site) and disturbance history at the nine

MOFEP sites.

Figure 3—Growth, in-growth, and mortality for oaks at the nine MOFEP sites in undisturbed plots during 1992-

2002. Growth is average basal area increases for trees >4.5 in. in diameter at breast height (d.b.h.); in-growth is

average basal area increases by trees originally <4.5 in. in d.b.h. that grew into the larger size class during the

sampling period; mortality is basal area of trees that died during the sampling period.

their r and K index value and was correlated (r = 0.71, p =

0.03) with index values of long-term disturbance frequency

(Guyette and Kabrick 2002).

Recent changes in the abundances of oak species at the

nine MOFEP sites are consistent with their life history strategies and their r and K index values. Ten years of inventory data (1992-2002) measured in undisturbed, permanent

vegetation plots show that the net basal area of oaks with

high r and K indices such as white oak are increasing while

those species with low r and K indices such as black jack

are decreasing (fig. 3). These abundance changes at these

undisturbed sites are roughly correlated with their r and K

index values.

DISCUSSION

Non-random associations among growth and reproductive

characteristics of oak indicate a distribution of attributes

that is consistent with r and K selection processes that has

occurred over an evolutionary time scale in response to

disturbance and competition. The development of an r and

K index among the species of a genus may have utility in

management as well as scientific research. Quantification

of species strategies could aid in predicting forest composition in response to silvicultural prescriptions. Residual

basal area left after logging may be used in the prediction

of species regeneration. Scientist might use the r and K

index values to explain species distributions. For example,
142

bur oak, an extreme K strategist (table 1), only occurs in

many areas in extremely competitive environments such as

flood plain forests and in tall grass prairies where large

seeds and a high degree of shade tolerance allow for initial

regeneration.

CONCLUSIONS

Quantitative comparisons among the life history strategies

of oak and other large genera via index values are possible,

may prove of value, but have limitations. We used values

found in the oak literature. There is considerable difficulty in

finding precise quantitative data that are comparable among

a number of species. For instance, although we found

excellent data on acorn weight, other variables such as the

age of first reproduction or shade tolerance were more

qualitative – more expert opinion than actual measured

quantities. Thus, we believe that it should be understood,

that when using the numeric values of r and K indices,

these values only qualitatively estimate differences among

species life history traits.

ACKNOWLEDGMENTS

The authors want to thank the Missouri Ozark Forest

Ecosystem Project and the Missouri Department of

Conservation for their support is this project.

LITERATURE CITED

Brookshire, B.L.; Shifley, S.R. 1997. Proceedings of the Missouri

Ozark Forest Ecosystem Project symposium: An experimental

approach to landscape research, 1997 June 3-5, St. Louis, MO.

Gen. Tech. Rep. NC-193. St. Paul, MN: U.S. Department of

Agriculture, Forest Service, North Central Forest Experiment

Station. 378 p.

Brown, H.P.; Panshin, A.J. 1940. Commercial timbers of the United

States. McGraw-Hill Book Comp. New York. 554 p.

Burns, R.M.; Honkala, B.H. 1990. Silvics of North America. Vol. 2,

Hardwoods. Agriculture Handbook 654. USDA Forest Service.

Washington DC. 877 p.

Carmean, W.H.; Hahn, J.T.; Jacobs, R.D. 1989. Site index curves

for forest tree species in the Eastern United States. North

Central Forest Exp. Station. GTR NC-128. 142 p.

Crawley, M.J. 1997. Plant ecology. Blackwell Science. London.

715 p.

Flora of North America Editorial Committee. 1997. Flora of North

America. Vol. 3. Oxford Univ. Press. New York. 590 p.

Foster, H.D.; Ashe, W.W. 1908. Chestnut oak in the Southern

Appalachians. USDA Forest Service. Circular 135. Government

Printing Office. Washington DC. p 21.

Gleason, H.A.; Cronquist, A. 1991 Manual of vascular plants of

Northeastern United States and adjacent Canada. The New

York Botanical Garden, Brox New York. 910 p.

Grime, J.P. 1979. Plant strategies and vegetation processes. John

Wiley & Sons. New York. 222 p.

Guyette, R.P.; Dey, D.C. 2000. Humans, topography, and wildland

fire: the ingredients for long-term patterns in ecosystems. In:

Proceeding: Workshop on fire, people, and the Central

Hardwood Landscape, D.A. Yaussey, compiler. GTR NE-274,

129 p.

Guyette, R.P.; Kabrick, J.M. 2002. The legacy and continuity of

forest disturbance, succession, and species at the MOFEP

sites. In: Proceedings of the second Missouri Ozark Forest

Ecosystem Project symposium (Shifley and Kabrick eds.).

USDA Forest Service. GTR NC-227. 227 p.

Guyette, R.P.; Muzika, R.M.; Dey, D.C. 2002. Dynamics of an

anthropogenic fire regime. Ecosystems 5: 472-486.

Kabrick, J.M.; Larsen, D.R.; Shifley, S.R.1997. Analysis of pretreatment woody vegetation and environmental data for the

Missouri Ozark Forest Ecosystem Project. In: Brookshire, B.L.;

Shifley, S.R. eds. Proceedings of the Missouri Ozark Forest

Ecosystem Project symposium: An experimental approach to

landscape research. Gen. Tech. Rep. NC-193. St. Paul, MN:

U.S. 378 p.

Kozlowski, T.T.; Kramer, J.P.; Pallardy, S.G. 1991. The physiological ecology of woody plants. Academic Press, Inc. NY. 657 p.

Lambers, H.; Chapin, F.S., III; Pons, T.L. 1998. Plant physiological

ecology. Springer, New York. 540 p.

Long, T.J.; Jones, R.H. 1996. Seedling growth strategies and seed

size effects in fourteen oak species native to different soil

moisture habitats. Trees 11: 1-8.

MacArthur, R.H.; Wilson, E.O. 1967. The theory of island

biogeography. Princeton Univ. Press. Princeton, New Jersey.

Miller, H.A.; Lamb, S.H. 1985. Oaks of North America.

Naturegraph Publishers, Inc. Happy Camp. California. 327 p.

Nixon, K.C. 1997. Qurecus. In: Morin, N.R. eds. Flora of North

America Vol 3. Oxford Univ. Press. New York. 590 p.

Odum, E.P. 1997. Ecology a bridge between science and society.

Sinauer Associates, Inc. Sunderland, Massachusetts. 330 p.

Panshin, A.J.; de Zeeuw, C. 1970. Textbook of wood technology.

McGraw-Hill Book Comp. New York. 705 p.

Pianka, E.R. 1999. Evolutionary ecology. Sixth Edition. BenjaminCummings.

Schopmeyer, C.S. 1974. Seeds of woody plants in the United

States. USDA Forest Sevice, Dep. Agric. Handbook No. 450.

Washington, D.C.

Siau, J.F. 1971. Flow in wood. Syracuse Univ. Press. Syracuse.

New York. 131 p.
143

INTRODUCTION

Hurricane-force winds frequently initiate forest structural

and compositional changes in the Southern Appalachians.

The effects of wind on upland hardwood forest structure

and composition have been studied mostly in the context of

either small gap-phase openings, or in retrospective studies

of ancient disturbances. Larger (> 0.1 ha) wind-created

openings, which are common across Southern Appalachian

landscapes (Greenberg and McNab 1998), can be an

important factor in shaping understory colonization, growth,

and survival (Runkle 1985).

Increases in light created by wind-generated gaps change

the dynamics of understory plants. Generally, seedling

survivorship and growth improve as gap size increases, as

canopy cover decreases, and in the photosynthetically

active radiation (PAR)-rich north end of gaps (Ashton 1996,

Chen and others 1995, Dale and others 1995). PAR and

attendant plant growth and survivorship gradually decline

from gap center to exterior forest (Chen and others 1995).

Many investigators have linked tree seedling survivorship

and growth with gap size and categorical position (gap

center, gap edge, outside gap) within and around gaps

(Sipe and Bazzaz 1995). Analyzing understory vegetation

as a function of categorical covariates is attractive to many

investigators, because these discrete approaches yield

easily understood mean responses. However, continuous

variables lend themselves to predictive equations that

enable managers to understand where responses take

place along a gradient of change. If managers could predict

survivorship and growth along linear distance gradients,

they could then also predict the extent of gap partitioning

for arborescent species of interest.

Windstorms create massive amounts of woody debris in hardwood forests (Greenberg and McNab 1998). This debris may

either enhance or hinder seedling survivorship and growth.

Hurricane Opal, which struck the Bent Creek Experimental

Forest on October 5, 1995, provided a firsthand opportunity

to evaluate the effects of wind damage, particularly large

area gaps, on forest understory vegetation. I investigated

the relationships of oak (Quercus) seedling survivorship

and growth to spatial and structural gradients in and around

large Hurricane Opal-created gaps.

OBJECTIVES

My objective was to test the hypotheses that 2-year oak

seedling survivorship and growth increase as gap size

increases, on a linear distance gradient toward gap center,

in the north end of gaps, and as hurricane-created woody

debris decreases.

METHODS

Hurricane Opal struck Bent Creek on the morning of

October 5, 1995. Opal created sustained winds of 8.9 miles

per second and maximum peak gusts of 25.9 miles per

second at the nearby Asheville, NC, airport. Within a 259-ha

surveyed parcel at Bent Creek, an average of 0.89 canopy

gaps/ha were created by Opal-generated windfalls. Singletree gaps were the most common opening, averaging 57 ±

34 m2. Multiple-tree gaps averaged 171 ± 117 m2 (Greenberg

and McNab 1998).

Gap Selection

Selected gaps are located within the 2 400-ha Bent Creek

Experimental Forest, about 16 km south of Asheville, NC

(35.5o N, 82.6o W) in the Southern Appalachian Mountains.

Gaps were restricted to openings at least 0.1 ha in size.

Also, at least six canopy trees per gap must have fallen as

a result of Hurricane Opal. Beck (1988) commented on the

0.1-ha size as being a reasonable minimum for the successful colonization and development of the most shade-intolerant eastern hardwoods. By restricting gap areas to > 0.1

SURVIVORSHIP AND GROWTH OF OAK REGENERATION

IN WIND-CREATED GAPS

Erik C. Berg1

1 Forester, USDA Forest Service, Southern Research Station, Asheville, NC 28806.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—The effects of wind on upland hardwood forest structure and composition have been studied mostly in the

context of either one to two tree mortality gap-phase openings or in retrospective studies of ancient disturbances. Larger

(> 0.1 ha) wind-created openings are common across Southern Appalachian landscapes and can be an important factor in

shaping understory colonization, growth, and survival. I investigated the relationships of oak seedling survivorship and

growth to spatial and structural gradients in and around large hurricane-created gaps on the Bent Creek Experimental

Forest. I related 2-year tagged-seedling survivorship to distance from gap edge and physical site through logistic

regression. Seedling survivorship declined progressively on a linear distance gradient from gap exterior to gap center.

Survivorship also declined as microsite soil moisture increased. I used multiple nonlinear regressions to relate 2-year

tagged-seedling basal diameter growth and height growth to distance from gap edge, initial seedling height, canopy cover,

and physical site. Basal diameter growth increased as midstory canopy cover declined, at gap positions close to gap

center, as initial seedling height increased, and as microsite soil moisture increased. Seedling height growth increased

with decreasing overstory canopy cover, at locations near gap center, as initial seedling height increased, and as

microsite soil moisture increased.
144

ha, I ensured that all native hardwoods had enough light to

colonize and grow successfully.

Using Runkle’s (1992) definition of the extended gap to

determine perimeters, I located 12 gaps meeting the above

criteria ranging from 0.13 to 1.26 ha from October 1995 to

June 1996.

Project Site

Of the 12 gaps, 6 are located in dry oak-hickory vegetation

communities, 4 in acidic coves, and 2 in rich coves (Schafale

and Weakley 1990). The frost-free growing season extends

from approximately May 1 to mid-October. Annual precipitation ranges from 120 cm at 670 m elevation to 150 cm at 850

m elevation. Soils are derived from gneisses and schists, with

occasional intrusions of mafic minerals found in amphibolite

deposits. All soils are > 80 cm deep and acidic (pH < 5.2).

Hurricane-created windfall trees mostly were uprooted and

did not snap off from the bole. All selected gaps supported

some residual hardwood overstory and midcanopy trees;

residual tree distribution was highly variable.

Gap Sampling Design

Sampling points were installed during May to July 1996.

Two horizontal perpendicular axes were located within each

gap: north-south and east-west. Axes intersected at gap

center. Axis orientation was changed when realignment

allowed a gradient along the entire length of a gap. Transect lines extended from center along established axes in

the cardinal directions. Sampling points were located at:

1. gap center

2. out from center along transects 7.3 to 10.67 m apart until

gap edge was reached

3. at the north, south, east, and west gap edges

4. progressively outward beyond gap edges 7.3 m apart.

The most extreme points were installed outside gaps where

ground-level solar radiation approximated that of forests

unaffected by windthrow.

This design resulted in 15 to 32 sampling points per gap

and 269 points among all 12 gaps. Established sampling

points formed the centers of 13 m2

 circular quadrats.

Tree Seedling Measurements

One or two oak seedlings ≤ 3.81 cm in diameter at breast

height were selected at random within each of the 13 m2

circular quadrats and tagged for long-term identification and

measurement. Tagged oaks included 54 northern red (Q.

rubra L.), 38 chestnut (Q. prinus L.), 69 black (Q. velutina

L.), 2 southern red (Q. falcata Michx.), and 73 scarlet (Q.

coccinea Muenchh.).

Tagged oaks were pooled into one analysis group, because

survivorship rates, growth, and response to disturbance are

similar for these species (Personal communication. 2000.

David Loftis, Project Leader, USDA Forest Service, Southern

Research Station, Bent Creek Experimental Forest, Asheville,

NC 28806). Seedlings were measured twice: June to

October 1996 and October to November 1998.

Variables

A wide array of variables were measured and tested as

covariates (see table 1 for detailed descriptions of covariates used in final models):

Variables that directly relate to hypotheses:

• distance/gap attributes: gap area, gap perimeter, ratios

of gap length to width, distance from gap center to edge,

distances from north and south gap edges to center,

cardinal direction from center, and gap aperture (angle

from gap center to canopy treetops at gap edge (Runkle

1992)

• cover: canopy cover of overstory, midstory, and total

canopy

• debris resulting from Hurricane Opal: crown debris,

coarse woody debris, tree-fall pits or mounds.

Covariates that help explain background variability:

• site: slope, aspect, categorical indices of soil moisture

potential (xeric, subxeric, submesic, mesic), elevation,

landform index (McNab 1993), and terrain shape index

(McNab 1989)

• vegetative competition: overtopped vs. not-overtopped

(dichotomous estimate of subject seedling position

relative to surrounding vegetation), shrub coverage, tree

seedling densities

• tagged seedling condition: sprout vs. seed origin, broken

vs. whole seedling top, microtopography where the seedling is located, initial height, and initial basal diameter.

Data Analysis

I used regression analysis to test all hypotheses.

Seedling survivorship—I employed logistic regression to

test the seedling survivorship hypothesis.

The logistic model (Hosmer and Lemeshow 2000) is

1 exp( )

exp( )

i i

i i

b X

b X P

+ =

where

P = predicted probability of seedling survivorship

i b = vector of regression coefficients

Xi = vector of independent variables

exp = base of the natural logarithm.

Data were pooled across all 12 gaps and 269 quadrats and

analyzed with SAS PROC LOGISTIC (SAS Institute 2000).

Basal diameter and height growth—I tested seedling basal

diameter and height growth hypotheses with nonlinear

regression, using SAS PROC NLIN (SAS Institute 2000).

I regressed basal diameter growth against covariates using

the exponential function, β0

(eβ1x1+β2x2...βnxn ). I modeled

height growth with another exponential function,

β 0 + eβ1x1+β2x2...βnxn .
145

These functions are modifications of the Mitcherlich equation, commonly used to model vegetation growth (Myers

1990). Other investigators have used similar functions to

model tree diameter and height growth (Vanclay 1994).

RESULTS

Survivorship

Based on the results of my logistic model (table 2), I rejected

the hypothesis that survivorship should increase as gap

size increases, toward gap center, in the north end of gaps,

and as hurricane-created debris declines.

Oak seedling survivorship declined toward gap center and

on high-moisture microsites as indexed by terrain shape

index (TSI) (fig. 1). The negative slope of the TSI parameter

in the survivorship model makes sense; oak survivorship is

superior on drier sites, probably because arborescent seedling competition is less than that of mesic sites (Johnson

and others 2002).

My predictive model is weak; standard error of the gap

position (GAPPOS) parameter is roughly half the parameter

estimate (table 2). The low rescaled pseudo-R2

 of 0.11 bears

evidence that my survivorship model has poor goodness-offit. Classification accuracy is poor, as evidenced by the area

under the ROC curve (Hosmer and Lemeshow 2000) of

0.774 (1.0 = perfect classification; 0.5 = no classification

benefit; < 0.7 generally indicates poor classification) (fig. 2).

Also, my model exhibited declining percent correct classifications with increasing cut point values (94 percent at cut

point of 0.50 to 83.3 percent at cut point of 0.90), suggesting poor classification ability.

Topography (seedling location: pit, mound, or near large

woody debris) was not correlated with seedling survivorship

(table 1). Because only a small fraction of gap areas were

covered with pits and mounds, few tagged seedlings were

located on these microsites, making any statistical relationships improbable. I found no relationship of oak seedling

survivorship to hurricane-created debris, including crown

debris and log debris > 8 cm in diameter.

Oak seedling survivorship was not related to cardinal

direction within gaps or gap size. I found no relationship of

Table 1—Variables used in oak seedling survivorship and growth regression models: data from 12 Hurricane Opalcreated gaps within the Bent Creek Experimental Forest

Variable Mean Range Explanation

units

GAPPOS 5.64 (m) -29.27 – 95.30 Gap position: Linear horizontal distance from gap-edge to quadrat center.

(fig. 1) Distances from edge towards gap interior are positive, from edge to gap

exterior are negative.

MIDCOVER 0.6 (decimal) 0.0 – 1.0 Midcanopy cover: Canopy cover of midcanopy trees. Canopy cover was

measured with a go/no-go densitometer (Geographic Resource Solutions

1997) at 17 points within 3.6 m of each quadrat center. The GRS device is

essentially a small periscope with level vials and center point for dichotomous calls as to whether or not there is arborescent vegetation overhead.

Positive “hits” were then summed and divided by 17 to yield the fraction of

the area with overhead canopy.

OVERCOV 0.5 (decimal) 0.0 – 1.0 Overstory cover: Canopy coverage of true canopy species, such as the

oaks. Measured as above.

LFI .19 (decimal) .08 – .34 Landform Index (McNab 1993): The degree of protection offered by the

surrounding topography, expressed as the percent slope from gap center

to the surrounding landscape horizon. The mean of 8 readings taken at

45-degree intervals. LFI is a surrogate for soil moisture. Higher values

suggest higher soil moisture content.

TSI 3.0 (decimal) -8.6 – 36.6 Terrain Shape Index (McNab 1989): Microsite topography, expressed as

the percent slope parallel to ground surface within 15.24 meters from gap

center. The mean of 8 readings taken at 45-degree intervals. TSI is a

surrogate for microsite soil moisture. Higher values suggest higher soil

moisture content.

SURV 0.9 (decimal) 0.0 – 1.0 Survivorship between 1996 and 1998: Dichotomous response variable.

BDGROW98 0.3 (cm) -4.3 – 2.5 Basal diameter growth between 1996 and 1998; response variable.

HT96 0.6 (m) 0.1 – 3.7 Initial seedling height: measured in 1996.

HTGROW98 0.2 (m) -1.5 – 2.5 Height growth between 1996 and 1998; response variable.

GAPPOS = gap position; MIDCOVER = midstory canopy cover; OVERCOC= overstory cover; LFI = landform index; TSI = terrain shape

index; SURV = 2-year survivorship probability; BDGROW98 = 2-year basal diameter growth; HT96 = initial height; HTGROW98 = 2-year

height growth.
146

survivorship to surrounding arborescent seedling competition, gap aperture, canopy cover, or tagged seedling

condition, including initial seedling height, seedling origin

(sprouts vs. propagules from seed), or amount of seedling

top damage.

Growth

I encountered significant problems with outliers in all growth

analyses. In particular, negative growth observations

created enormous modeling problems. Negative basal

diameter and height growth are not unusual; oak seedlings

frequently lose their tops to herbivory or weather damage

(Johnson and others 2002). New tops usually develop after

resprouting, but the new growth may not make up for increment lost over the 2-year measurement period. Some of

these negative growth observations in larger diameter stems

created high influence points that actually reversed the sign

of initial height (HT96) parameter slopes. I solved this

problem by deleting all negative growth observations.

My analyses supported my hypotheses of increased oak

basal diameter and height growth toward gap center (table

3, figs. 3 and 4). However, data analyses did not support

my hypotheses that growth would increase in larger gaps,

in the north end of gaps, and as hurricane-created debris

decreased.

Table 2—Logistic modela: 2-year oak seedling survivorship

Response Likelihood Prob. > Maximum rescaled Correct classifications

variable n ratio chi-square Pseudo-R2 pseudo-R2 (cut point)

percent

SURV 234 9.532 .0085 .04 .11 94.0 (.50)

83.3 (.90)

Covariate Parameter Standard Prob >

estimate error Chi-square chi-square

INTERCEPT 3.392 .410 68.53 <.0001

GAPPOS -.029 .016 3.16 .08

TSI -.101 .042 5.95 .01

a SURV = 2-year survivorship probability; BDGROW98 = 2-year basal diameter growth; HTGROW98 = 2-year

height growth; MIDCOVER = midstory canopy cover; OVERCOC: overstory cover; GAPPOS = gap position; HT96

= initial height; LFI = landform index; TSI = terrain shape index (table 1).

Figure 1—Two-year oak survivorship vs. GAPPOS and TSI.

GAPPOS = gap position; TSI = terrain shape index (table 1).

Figure 2—Two-year oak survivorship vs. GAPPOS and TSI: ROC

curve (45°

 diagonal plot suggests poor model accuracy; straight

line = perfect accuracy). Area under curve = 0.774 (0.5 = no

classification benefit; 1.0 = perfect classification).

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

60

40

20

0

-20

-5 0 5 10 15 20 GAPPOS- m

TSI

Predicted oak survivorship

Predicted oak survivorship

1.1

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

1-Specificity

Sensitivity

Receiver operating characteristic (ROC) curve

oak survivorship vs. GAPPOS, TSI
147

the height growth model R2 is 0.23. Also, the distance gradient covariate GAPPOS explained little of the variability in

growth, as evidenced by high GAPPOS standard errors

relative to parameter estimates in both the basal diameter

and height growth models (table 3).

HT96 contributed substantially to explaining variability in

basal diameter and height growth (table 3). Basal diameter

and height growth correlated with seedling origin (sprouts

vs. propagules arising from seed). However, initial height

was so highly collinear with origin that origin had to be

eliminated from all models.

Site variables, TSI, and landform index (LFI) explained

much of the variation in growth (table 3). I have no rational

explanation why LFI proved valuable in the basal diameter

growth model as opposed to TSI in the height growth model.

The positive slopes of TSI and LFI (HT96-LFI in the basal

diameter growth model, and HT96-TSI in the height growth

model) make sense; growth of surviving seedlings should

be superior on mesic sites.

Both overstory canopy cover (OVERCOV) and midstory

canopy cover (MIDCOVER) (table 1) were negatively correlated with oak seedling height growth. However, OVERCOV

was much more strongly related to height growth than was

MIDCOVER. In fact, MIDCOVER was not significant in the

presence of OVERCOV when both variables were included

in the height growth model.

The interaction terms HT96-LFI in the basal diameter growth

model and HT96-TSI in the height growth model include

covariates not included as main effects in the nonlinear

functions (table 3). This contradicts recommendations of

some statisticians to always include main effects in “hierarchically well formulated models” (Glantz and Slinker

1990). However, including both interaction and all main

effect terms created substantial collinearity, so I deleted

problematic main effects from both the basal diameter

growth and height growth models.

Table 3—Nonlinear growth models: 2-year oak seedling basal diameter and height growtha

Response Mean square Computed F Prob. Nonlinear Parameter Standard

variable n error statistic > F R2 Covariate estimate error

BDGROW98 169 .09 77.52 <.0001 .31 INTERCEPT 0.463 .065

MIDCOVER -1.01 .256

GAPPOS 0.01 .004

HT96-LFI 2.24 .260

HTGROW98 169 .0518 12.0 <.0001 .23 INTERCEPT -.8143 .041

HT96 .1192 .041

GAPPOS .00256 .001

OVERCOV -.1702 .001

HT96-TSI .0110 .005

a BDGROW98 = 2-year basal diameter growth; HTGROW98 = 2-year height growth; HT96 = initial height; GAPPOS = gap

position; MIDCOVER = midstory canopy cover; OVERCOC: overstory cover; LFI = landform index; TSI = terrain shape index

(table 1).

Figure 4—Two-year oak height growth vs. GAPPOS, HT96, TSI,

and OVERCOV.

Two-year height growth by gap position

HT96 (initial height) = .4 m 

TSI (terrain shape index) = 3.0

Overcov (overstory cover) = .5

0.0

0.1

0.2

0.3

32 (center) 0 (edge) Neg. 20 

(exterior)

Neg. 30 

(exterior)

GAPPOS (gap position) - m

Height 

growth - m

Two-year height growth by gap position

HT96 (initial height) = .4 m

TSI (terrain shape index) = 3.0

Overcover (overstory cover) = .5

Figure 3—Two-year oak basal diameter growth vs. GAPPOS,

HT96, TSI, and MIDCOVER.

Two-year basal diameter growth by gap position

HT96 (initial height) = .4 m

LFI (landform index) = .19

midcover (midstory canopy cover) = .6

0.0

0.2

0.4

0.6

32 (center) 0 (edge) Neg. 20 

(exterior)

Neg. 30 

(exterior)

GAPPOS (gap position) - m

Basal diameter

growth - cm

Two-year basal diameter growth by gap position

HT96 (initial height) = .4 m

LFI (landform index) = .19

Midcover (midstory canopy cover) = .6

Seedling basal diameter and height growth were highly variable. Basal diameter growth mean square error was 0.09

with mean of 0.3 cm; height growth mean square error was

0.0518 with mean of 0.2 m. Accordingly growth relationships

are weak; the basal diameter growth model R2 is 0.31, and
148

DISCUSSION

Survivorship declined toward gap center and increased at

gap edge and in microsites up to 20 m beyond gap edge in

the unaffected forest (fig. 1). My results of higher seedling

survivorship in microsites closer to gap edge than gap

center mirror those of McNab (McNab, W.H. 2002. Poor

American chestnut seedling survivorship in gap-centers.

Unpublished data analysis. U.S. Department of Agriculture,

Forest Service, Southern Research Station) and Sipe and

Bazzaz (1995). Meiners and others (2000) found that oak,

ash (Fraxinus americana L.), and red maple (Acer rubrum

L.) survivorship suffered in the subdued light environment

at gap perimeters; seedling survivorship was enhanced

near gap centers. Why are my findings of low survivorship

toward gap center diametrically opposed to the results of

other investigators such as Meiners and others (2000)?

Perhaps seedling competition increases toward gap center,

which may be contributing to early oak seedling death. This

trend may reverse through time for seedlings near gap

center that are able to attain dominance. Eventually, oak

seedlings outside gaps probably will die at an increasing

rate, because they will not be able to acquire sufficient

sunlight to achieve their compensation points (Kramer and

Kozlowski 1979).

My findings of increasing basal diameter and height growth

along a linear distance gradient toward gap center are

consistent with those of Brown (1996). He found that height

growth of tropical hardwoods increased linearly on a

distance gradient from gap exterior to gap center. Brown’s

study is one of few relating seedling performance to linear

distance gradients.

Tree seedling survivorship and growth generally improve as

gap size increases because of solar radiation gains at

ground level (Sipe and Bazzaz 1995). However, improvements in growth often attenuate beyond thresholds in gap

size. For example, Coates (2000) found substantial seedling growth enhancement as gap size increased up to 0.1

ha but discovered no growth improvements in sizes beyond

0.1 ha to 0.5 ha. However, I found no correlations of oak

seedling survivorship or growth with gap size. I suspect that

having my gaps > 0.1 ha in size diluted the effect of gap

size on oak survivorship and growth.

The lack of relationship of oak survivorship and growth to

hurricane-created crown debris is surprising. Crown debris

intercepts substantial solar radiation and should be negatively correlated with survivorship and growth. Crown debris

was heavily distributed throughout gaps as a result of windthrown trees. I suspect that one reason for this lack of

correlation is deterioration of crown debris over the 2-year

measurement period. Crown debris coverage declined from

a mean of 10.6 percent in 1996 to 0.7 percent in 1998.

Generally, tree seedling survivorship and growth increase

as midstory and overstory canopy densities decrease

(Buckley and others 1998, Dey and Parker 1997). As

expected, I found that seedling growth was negatively correlated with cover. Why did I not find a significant negative

relationship of seedling survivorship to canopy cover? I

suggest that the tagged seedlings had sufficient carbohydrate reserves to sustain life over the 2-year response

period, even under residual tree canopies. However, the

answer eludes me, because my logistic model only

measured the dichotomous response of live vs. dead, not

physiological condition.

Most surprising is the lack of relationship between oak survivorship and initial size (Johnson and others 2002). Oaks

are advance-regeneration-dependent (Johnson and others

2002, Loftis 1989). Probability of their survival and subsequent competitive status is based on size, as represented

by basal diameter or height (Battaglia and others 2000,

Loftis 1990). Having large initial size confers competitive

advantages in high-density cohorts of regeneration. My

findings of no survivorship relationship with initial size may

be because my analysis includes only 2 years of response

time. Many authors suggest that oak survivorship is quite

high for the first few years after disturbance before severe

competition takes place (Johnson and others 2002).

Topographic factors can serve as surrogates of available

soil moisture (Vanclay 1994). TSI and LFI apparently captured important differences in soil moisture across all 12

gaps to explain much of the variability in survivorship and

growth (tables 2 and 3).

This study validates the use of LFI and TSI to explain site

difference impacts on seedling survivorship and growth.

Previously, these indices had been used solely in site classification studies (Hutto and others 1999) (W.H. McNab.

1995. Field guide to site classification in the Bent Creek

Experimental Forest. Unpublished manuscript. On file with:

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

Research Station). Because many forestry investigations

are better analyzed with regression than through agricultural-style field-blocked studies, physical site variables such

as LFI and TSI are invaluable in explaining vegetation

response by differing site qualities.

CONCLUSIONS

1. Oak seedling survivorship declined on a continuous

horizontal distance gradient from gap exterior to gap

center.

2. Seedling basal diameter and height growth increased on

a continuous horizontal distance gradient from gap

exterior to gap center.

3. Arborescent overstory cover proved useful in explaining

reductions in seedling height growth; midcanopy cover

substantially reduced basal diameter growth. Seedling

survivorship was not related to cover.

4. Hurricane-created debris had no discernible effect on

seedling growth or survivorship.

5. Gap size did not affect 2-year oak seedling survivorship

or growth in the range of gap sizes investigated (0.1 to

1.3 ha).

6. Gap-edge effects on oak seedling survivorship and

growth persisted at least 20 m into the unaffected forest.

7. Physical site variables enable oak seedling growth and

survivorship comparisons among a wide variety of sites.
149

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Pickett, S.A.; White, P.S., eds. The ecology of natural disturbance and patch dynamics. New York: Academic Press: 17-33.

Runkle, J.R. 1992. Guidelines and sample protocol for sampling

forest gaps. Gen. Tech. Rep. PNW GTR-283. Portland, OR:

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

Northwest Research Station. [Number of pages unknown].

SAS Institute. 2000. SAS. Version 8.1. Cary, NC: SAS Institute,

Inc. [Number of pages unknown].

Schafale, M.P.; Weakley, A.S. 1990. Classification of the natural

communities of North Carolina: third approximation. Raleigh,

NC: North Carolina Natural Heritage Program, Division of Parks

and Recreation. 325 p.

Sipe, T.W.; Bazzaz, F.A. 1995. Gap partitioning among maples

(Acer) in central New England: survival and growth. Ecology.

76: 1587-1602.

Vanclay, J.K. 1994. Modelling forest growth and yield: applications

to mixed tropical forests. New York: CABI. 312 p.
150

INTRODUCTION

Dead, decaying wood is known to play a number of important

roles in terrestrial ecosystems from nutrient cycling, moisture retention, to habitat complexity (Harmon and others

1986). Due to involvement in such diverse ecological functions and processes, dead wood has been recognized as

an important forest resource (Stevens 1997). With this recognition, has come a growing awareness of the contribution

dead wood makes to forest biodiversity (Lofroth 1998).

Of the various organisms that make use of dead wood,

insects represent one of the most species-rich and abundant components (Hanula 1996). Some insects spend the

majority of their life cycle living within, and feeding on, dead

wood. Once dead wood is fragmented by wood-boring

species, other insects enter, feeding on the decaying wood

or the hyphae of wood-decaying fungi. These species, in

turn, represent prey for a variety of predaceous insect

species.

Speight (1989) termed insect species dependent upon

dead wood, wood-decaying fungi, or other organisms within

dead wood for some portion of their life cycle as saproxylic.

Saproxylic insects represent a fundamental component of

most forest ecosystems, playing vital roles in the initial

fragmentation and breakdown of dead woody debris

(Ausmus 1977, Edmonds and Eglitis 1989) as well as

comprising a food base for other organisms (Beckwith and

Bull 1985).

Saproxylic insects, beetles in particular, have received much

attention in Europe as regards their diversity, conservation,

and potential to serve as indicators of forest condition

(Hågvar and Økland 1997, Nilsson and others 1995,

Väisänen and others 1993). A number of European studies

have noted variations in saproxylic beetle faunas in relation

to forest structure (Barbalat 1998), successional stage

(Gutowski 1995), and management practices (Barbalat

1996).

Outside of insects considered to be pests of wood products,

little base-line information exists regarding species composition and status of saproxylic insects in forests of the

southeastern U.S. Though little studied, there has been a

call for additional research concerning the role dead wood

plays in the maintenance of southern forest biodiversity

(McMinn and Crossley 1996). Basic assemblage-level data

concerning the community composition and structure of

saproxylic species within different forest types, and across

successional stages, could provide a standard by which

disturbances, human-induced or natural, could be evaluated (Kaila and others 1997). In that light, our objective in

this study was to compare and characterize the saproxylic

beetle assemblages of upland and bottomland hardwood

forests. Both upland and bottomland hardwood forests are

characterized by significant ecological differences in moisture, tree species composition, and site conditions. Such

factors may play important roles in shaping the saproxylic

beetle fauna of both forest types.

STUDY SITES

This study was conducted at the Noxubee National Wildlife

Refuge in east-central Mississippi (Noxubee County). Study

sites were established in two upland hardwood and two

bottomland hardwood stands on the refuge. Dominant tree

species in both upland hardwood stands included white oak

(Quercus alba L.), mockernut hickory (Carya tomentosa

(Poir.)), and black oak (Q. velutina (Ell.)). A number of large

shortleaf pine (Pinus echinata (Mill.)) occurred in one of the

upland hardwood stands. Dominant tree species in the

bottomland hardwood stands included willow oak (Q. phellos

L.), cherrybark oak (Q. falcata var. pagodifolia Ell.), red maple

(Acer rubrum L.), and American sweetgum (Liquidambar

styraciflua L.). The bottomland hardwood stands occurred

along the floodplain of the Noxubee River and flooded for

four to six days in early April 2000 when the Noxubee River

overflowed its banks. All four stands used as study sites

ranged in age from 45 to 60 years of age.

COMPARISON OF SAPROXYLIC BEETLE (COLEOPTERA) ASSEMBLAGES IN

UPLAND HARDWOOD AND BOTTOMLAND HARDWOOD FORESTS

Michael D. Warriner, T. Evan Nebeker, Steven A. Tucker, and Terence L. Schiefer1

1 Invertebrate Zoologist, Arkansas Natural Heritage Commission, Little Rock, AR 72201; Professor, Department of Entomology and Plant

Pathology; Animal Care Coordinator, Department of Wildlife and Fisheries; Curator, Mississippi Entomological Museum, Department of

Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS 39762, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Insects dependent upon dead wood, wood-decaying fungi, or other organisms within dead wood for some

portion of their life cycle have been termed saproxylic. Beetles comprise a large component of the saproxylic fauna within

forests and play vital roles in the initial fragmentation and breakdown of dead woody debris. To evaluate the influence of

forest type on saproxylic beetle assemblages, we surveyed upland and bottomland hardwood stands in east-central

Mississippi. Overall, the two forest types shared a number of similarities in terms of their saproxylic beetle faunas.

However, ecological differences between these two forest types were evident, most notably in diversity and abundance of

beetle species dependent upon wood-decaying fungi.
151

MATERIALS AND METHODS

Insect Sampling Protocol

Saproxylic beetles were sampled using Malaise traps and

window traps (flight-intercept traps). Malaise traps are large

tent-like structures that passively trap low-flying insects and

collect them in a container filled with a preservative/killing

agent. Collecting containers were filled with 70 percent

ethanol. One Malaise trap was placed in each upland hardwood and bottomland hardwood stand.

Window traps were also deployed at each study site. Window

traps, modified from Økland (1996), consisted of two perpendicular clear plastic sheets (35 cm x 40 cm) attached to a

collecting container (33 cm diameter). Collecting containers

were filled with propylene glycol. A roof was placed on top

of the intersecting clear plastic sheets to prevent rainfall

from flooding the collecting container. Window traps were

hung between two trees at a height of 2 m. A total of six

traps, spaced 20 m apart, were operated at each study site.

All traps were operated continuously from May to October

2000. Malaise and window traps were serviced, and

collected insects removed, on a biweekly basis. Beetles

collected from both trap types were sorted to morphospecies and stored in 70 percent ethanol.

Selection of Target Saproxylic Groups

One obstacle confronting insect-related projects is the overwhelming diversity of species that can be collected (Disney

1986). As an alternative to identifying all insects, assemblages of select species representing different functional

groups have been suggested for use as monitoring tools or

indicators of environmental change (Kremen and others

1993). Based upon that rationale, we identified target groups

for use in our analyses. The groups selected comprised

saproxylic beetles representing major functional groups

within dead wood. The represented functional groups, and

associated beetle taxa, used in our analyses were as follows:

Xylophagous beetles

Coleoptera: Cerambycidae (longhorned beetles)

Predaceous beetles:

Coleoptera: Cleridae (checkered beetles)

Fungivorous beetles:

Coleoptera: Erotylidae (pleasing fungus beetles)

Longhorned beetles include a number of species that feed

as larvae within trees and shrubs. A small number of species

feed on healthy hosts, however, most species feed on dead,

decaying wood (Yanega 1996). Most checkered beetles

feed on the larvae of wood-boring beetles (Cerambycidae,

Scolytidae) as both larvae and adults. Pleasing fungus

beetles are a group of mostly fungivorous species, many of

which feed on wood-decaying fungi.

Data Analysis

Species diversity between sites was evaluated using rarefaction (Simberloff 1972). Rarefaction estimates the number

of species in a random subsample to the entire sample.

The resulting value can then be interpreted as a measure

of diversity because the technique takes into account both

species richness and abundance. The main advantage of

using rarefaction is that it is independent of sample size.

Abundances of target taxa were compared between upland

and bottomland hardwood stands using t-tests. Similarities

in faunal composition among study sites were assessed

using the Morisita-Horn index. The Morisita-Horn index was

chosen because sample size and diversity of the sample

have little influence on its calculation (Morisita 1959, Wolda

1981). Distribution of numbers of species and individuals

representing each functional group (xylophagous, predaceous, fungivorous) were compared among upland hardwood and bottomland hardwood stands using a Chi-square

test.

RESULTS AND DISCUSSION

Saproxylic Beetle Diversity and Abundance

Overall, a total of 56 saproxylic beetle species were collected

from the bottomland hardwood study sites and a total of 48

species from the upland hardwood sites. Species diversity,

as measured by rarefaction, varied between the forest types

for two of our three target saproxylic groups (fig. 1). For

longhorned beetles, predicted diversity was slightly higher

in the bottomland hardwood stands than in the upland hardwood sites. Species diversity of pleasing fungus beetles

Figure 1—Species richness of target saproxylic beetle groups, as

estimated by rarefaction, in upland and bottomland hardwood

study sites.

Figure 2—Abundances of target saproxylic beetle groups in upland

and bottomland hardwood study sites.

45

40

35

30

25

20

15

10

5

0

BLH I BLH II UH I UH II

Cerambycidae

Erotylidae

Cleridae

Expected number of species

1000

900

800

700

600

500

400

300

200

100

0

BLH I BLH II UH I UH II

Cerambycidae

Erotylidae

Cleridae

Number of individuals
152

was considerably higher in bottomland hardwood stands,

reflecting the presence of a number of species not present

in the upland hardwood sites. Checkered beetle species

diversity was relatively equitable across all four study sites.

Abundances of longhorned beetles were found to be relatively similar (t=-0.36, df=145, P=0.3597) in bottomland

hardwood and upland hardwood forests (fig. 2). Conversely,

pleasing fungus beetle (t=1.71, df=29, P=0.0489) and

checkered beetle (t=1.75, df=21, P=0.04735) abundances

varied significantly in relation to forest type, with larger

numbers of both groups present in bottomland hardwood

forests.

Comparisons of saproxylic beetle assemblages between

stands of the same forest type displayed relatively high

degrees of complementarity. The Morisita-Horn value calculated for saproxylic beetle assemblages from the two bottomland hardwood sites indicated a high level of similarity at

0.92. A similar level of congruence was found to exist

between the two upland hardwood sites as well (0.91).

Comparisons between upland hardwood and bottomland

hardwood forest types yielded lower values (BLHI/UHI=0.77,

BLHI/UHII=0.75; BLHII/UHI=0.72, BLHII/UHII=0.68), indicating a lesser degree of similarity in saproxylic beetle

species composition. Analysis of numbers of species representing each functional group revealed no major differences

among the four study sites (χ2=2.29, df=6, P=0.8912).

Differences were noted when abundances of each functional group were compared across study sites. Upland

hardwood stands were characterized by significantly lower

numbers of individuals from predaceous and fungivorous

functional groups (χ2=672.80, df=6, P=<0.001). Numbers of

xylophagous individuals did not differ across the four study

sites.

Of the three target groups, longhorned beetles exhibited the

smallest amount of variation between the two forest types.

The most commonly collected longhorned beetle species

from both forest types included Strangalia luteicornis

(Fabricius), Neoclytus acuminatus (Fabricius), S. bicolor

(Swederus), and Elaphidion mucronatum (Say). Strangalia

luteicornis, and S. bicolor are known to feed on decaying

hardwoods. Neoclytus acuminatus is known to prefer

recently dead, as well as weakened and dying hardwoods.

Elaphidion mucronatum feed primarily on the branches of

dead hardwoods.

Although both upland hardwood and bottomland hardwood

forests contained different tree species, larval host preference did not seem so specific as to limit large numbers of

longhorned beetle species to one forest type. Many of the

longhorned beetles collected possess relatively broad larval

host preferences in terms of hardwood trees, with individual

species known to feed on a range of hickory (Carya), oak

(Quercus), elm (Ulmus), and/or ash (Fraxinus) species.

Notwithstanding that, both forest types did contain species

either trapped only within a specific forest type or characterized by higher abundances in one forest type. For

instance, Orthosoma brunneum (Forster) occurred in larger

numbers in bottomland hardwood stands than in upland

hardwood stands. This species is known to prefer welldecayed wood in moist conditions. Higher numbers within a

moist, flood-prone forest type is understandable. Likewise,

Parandra polita Say were only collected from upland hardwood stands. The larvae of P. polita feed on the heartwood

of hickory and beech, tree species common in our upland

hardwood study sites. The pine component of one upland

hardwood stand was also evident in the presence of Prionus

pocularis Dalmeister, a species known to feed on dead pine

logs, and Typocerus zebra (Olivier), a species that mines

dead pine roots.

Checkered beetles exhibited some variation between

upland and bottomland hardwood forests. Although number

of species did not differ significantly between the two forest

types, numbers of individuals did. This difference was

largely attributable to much larger numbers of Enoclerus

ichneumoneus (Faricius) in the bottomland hardwood

stands than in the upland hardwood stands. Enoclerus

inchneumoneus is a checkered beetle known to feed on a

variety of wood-boring beetle larvae, particularly those

under the bark of hardwood trees.

Although upland and bottomland hardwood stands could

not be strictly differentiated based upon longhorned beetle

and checkered beetle species composition, they could based

upon trap collections of pleasing fungus beetles. Both

species composition and abundance of pleasing fungus

beetles differed between the two forest types. Upland hardwood stands contained only four of the 10 species collected

in the bottomland hardwood stands. The most commonly

collected species from both forest types were Tritoma

biguttata (Say) and T. thoracica (Fabricius). Both species

were collected in numbers four to seven times higher in

bottomland hardwood stands than in upland hardwood

stands. Species only collected from bottomland hardwood

stands included Ischyrus quadripunctatus (Olivier),

Megalodacne heros (Say), T. pulchra (Say), and T. punticeps

(Fabricius). These beetles are all known to feed on the

fruiting bodies of fungi. Megalodacne heros, for instance,

feeds on bracket fungi (Ganoderma spp.), while the various

Tritoma and Triplax species feed on gilled fungi (Amanita

spp., Polyporus spp.). Upland hardwood stands were

largely characterized by a lack of these beetle species.

Upland stands were also characterized by lower numbers

of pleasing fungus beetles (406), when compared to

bottomland stands (2024).

The pleasing fungus beetle fauna of bottomland hardwood

stands is likely a reflection of the mesic conditions of these

forests. Although we did not quantify number of fruiting

bodies, the supposition can be made that the warm, humid

conditions of bottomland hardwood forests may be more

conducive to fungal growth and development than the drier

conditions found in upland sites. Availability of wood-decaying fungi has been demonstrated to be an important factor

affecting the diversity of saproxylic beetles in Europe

(Økland and others 1996). Quantification of wood-decaying

fungi fruiting bodies, in relation to pleasing fungus beetle

diversity and abundance, could aid in elucidating any

similar relationships in forests of the southeastern U.S.

CONCLUSIONS

Pleasing fungus beetles represent a saproxylic group that

could be potentially sensitive to changes in forest condition,

particularly as it pertains to suitable levels of moisture for
153

fungal growth and availability of dead wood for wood-decaying fungi. These beetles are easily sampled with Malaise

traps (Goodrich 1997) and relatively easy to identify. Their

use as potential indicators seems especially appropriate for

mesic forest types, such as bottomland hardwood stands,

where they may be more diverse and abundant. Overall,

longhorned beetles and checkered beetles did not appear

to be a defining group in terms of either forest type. However, longhorned beetles have been shown to respond to

changes in forest condition brought about by certain silvicultural practices (Warriner and others 2002). In that sense,

they represent a potentially useful group when evaluating

the impact forest management practices have upon dead

wood resources within a stand.

ACKNOWLEDGMENTS

We would like to thank Richard Smith of the Noxubee

National Wildlife Refuge for providing advice regarding

selection of study sites and information regarding stand

characteristics. We also thank Mike Caprio (Mississippi

State University) for his assistance in the preparation of

figures.

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arthropod and annelid populations. Ecol. Bull. (Stockholm)

25: 180-192.

Barbalat, S. 1996. Influence of forest management on three woodeating beetle families in the Areuse Gorges (Canton of

Neuchatel, Switzerland). Rev. Suisses de Zool. 103: 553-564.

Barbalat, S. 1998. Importance of forest structures on four beetle

families (Coleoptera: Buprestidae, Cerambycidae, Lucanidae,

and phytophagous Scarabaeidae) in the Areuse Gorges

(Neuchatel, Switzerland). Rev. Suisse de Zool. 105: 569-580.

Beckwith, R.C.; Bull, E.L. 1985. Scat analysis of the arthropod

component of pileated woodpecker diet. Murrelet 66: 90-92

Disney, R.H.L. 1986. Inventory surveys of insect faunas:

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Edmonds, R.L.; Eglitis, A. 1989. The role of the Douglas-fir beetle

and wood borers in the decomposition of and nutrient release

from Douglas-fir logs. Can. J. For. Res. 19: 853-859.

Goodrich, M.A. 1997. The pleasing fungus beetles (Coleoptera:

Erotylidae) of Beall Woods State Park, Wabash Co., Illinois.

Trans. Ill. St. Acad. Sci. 90: 139-145.

Gutowski, P.F. 1995. Changes in communities of longhorned and

buprestid beetles (Coleoptera: Cerambycidae, Buprestidae)

accompanying the secondary succession of the pine forests of

Puszcza Bialowieska. Fragm. Faun. 38: 389-409.

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with living sporocarps of Fomitopsis pinicola (Fr.) Karst. in four

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Kaila, L.; Martikainen, P.; Punttila, P. 1997. Dead trees left in clearcuts benefit saproxylic Coleoptera adapted to natural disturbances in boreal forest. Biodiv. Conserv. 6: 1-18.

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Harrison, eds. Conservation biology principles for forested

landscapes. UBC Press, Vancouver, B.C. pp. 185-214.

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154

INTRODUCTION

In southwestern Pennsylvania, mortality of northern red oak

has occurred that is related to low levels of available Ca

and high levels of available Al (Demchik 1998). In a review

of the literature, Cronan and Grigal (1995) suggested that

at molar ratios of Ca/Al of 1 or less a 50 percent chance of

growth reduction of forest trees exists. Ca/Al ratios of less

than 1 were found for all B-horizons in high mortality stands.

Soil conditions such as these reportedly reduce litter decomposition rates (Tamm 1976, Wolters 1991). Reduced decomposition rates slow nutrient cycling.

On sites that have experienced a large thinning (as experienced with increased rates of mortality), decomposition

rates may increase. Increased exposure of forest soil to

sunlight can increase rates of nutrient cycling from litter

(Zhang 1995). For this reason, if all other factors were

equal, the rates of decomposition on a site that has undergone substantial mortality would be expected to increase.

However, low Ca/Al ratios (soil acidity) may serve to reduce

decomposition rates, thus potentially canceling out such

increases.

Litter quality is also important to the rate of decomposition.

Lamb (1976) found Monterey pine (Pinus radiata) decomposition rates to be most influenced by soil nutrients at the

site of litter origin. The difference in soil nutrients at the site

of origin was potentially an index of litter quality. Foliar

samples taken from the canopy of high mortality stands on

the Laurel Hill were found to be lower in Ca and K than

foliar samples from low mortality stands (Demchik 1998).

Soils in these high mortality stands had lower Ca/Al ratios

(Demchik 1998).

In additional to physical breakdown, minerals released from

the litter are an important component of decomposition. In

general, leaf matter contains the highest ash content of

litter fall and is approximately 70 percent of total litter fall

(Bray and Gorham 1964). Laskowski and others (1995)

reported that litter turnover of Ca, magnesium (Mg) and

manganese (Mn) was governed by biological processes,

litter turnover of K and Na was controlled by physical processes (leaching) and litter turnover of Zn was controlled by

both fixing to humic materials and leaching. In general, base

nutrients in organic matter decrease with time (O’Connell

1988) while iron (Fe), Zn, copper (Cu) (Laskowski and

others 1995) and Al (McBrayer and Cromack 1980) may

increase with time. Bases decrease with decomposition and

leaching but proposed causes for increases in the absolute

quantity of metals have not been firmly defined. Laskowski

and others (1995) suggested a natural process but they

proposed no mechanisms to explain how it occurred.

Because base nutrient availability on acidic soils is governed

in large part by organic matter decomposition, changes in

rates of decomposition could drastically alter nutrient cycling.

Assessing the effect of both litter origin and site of decomposition on changes in nutrient release from litter is useful

in assessing the impact of soil acidification on forests.

The objectives of this study were to determine if differences

occurred between high and low mortality oak stands for

decomposition rates, element concentrations and absolute

level of elements in northern red oak leaves between high

and low mortality oak stands on the Laurel Hill.

METHODS

The Site

Three blocks of land on the Forbes State Forest (Hickory

Flats, Linn Run and Jones Mill) were selected that contained stands with high mortality (40 to 60 percent standing

dead oak timber) and low mortality (0 to 10 percent standing dead oak timber) of northern red oak in the Laurel Hill

region of southwestern Pennsylvania. The overstory trees

were 85-90 years old. The geology of the area is dominated

by parent material from the Pottsville, Mauch Chunk and

LITTER DECOMPOSITION IN LOW AND HIGH MORTALITY NORTHERN RED OAK

STANDS ON EXTREMELY ACIDIC SOUTHWESTERN PENNSYLVANIA SOILS

Michael C. Demchik and William E. Sharpe1

1 Agroforestry Management Extension Educator, University of Minnesota, Central Lakes Agricultural Center, Staples, MN 56479; and

Professor of Forest Hydrology, Environmental Resources Research Institute and School of Forest Resources, The Pennsylvania State

University, University Park, PA, 16802, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Previous research has shown that decomposition of organic matter is slower in soils with high levels of soil

acidity and available aluminum (Al). The objective of this experiment was to determine if differences in decomposition

rates of northern red oak leaves occurred between extremely acidic and less acidic sites that also differed in oak mortality.

Leaf litter from red oaks on high and low acidity soils was reciprocally transplanted into both high and low acidity sites.

After one growing season, neither site of decomposition or leaf origin had a significant effect on the rate of decomposition.

Litter that decomposed in low acidity stands tended to lose more calcium (Ca) and sodium (Na) and gain more phosphorus (P) than litter that decomposed in high acidity stands. Litter with origins in the low mortality stands tended to lose

more potassium (K) and gain more P and zinc (Zn) than litter with origins in the high mortality stands. The stand with the

highest oak mortality did not have the highest rate of decomposition indicating that soil acidity (low Ca/Al ratio) may have

operated to reduce decomposition at that site.
155

Burgoon formations. The soils were Typic Dystrochrepts of

the Hazelton very stony sandy loam, Calvin very stony silt

loam, and Dekalb very stony loam series, Aquic Fragiudults

of the Ernest very stony silt loam series and Typic Hapludults

of the Gilpin very stony silt loam series. All soils were

extremely acidic (table 1). Soils on the high mortality stands

had Ca/Al ratios in the A and B horizon that would indicate

high probability of expression of aluminum toxicity in plants.

Ca/Al ratios in the A and B horizon of low mortality stands

were higher and would have a low probability of expression

of aluminum toxicity (table 1; Data summarized from Demchik

1998). High mortality stands for Hickory Flats and Linn Run

had lower overall leaf mass production compared to the low

mortality stands. No difference in leaf mass production was

found between high and low mortality stands in the Jones

Mill block (Demchik 1998). For a more complete description

see Demchik (1998).

Litter Collection

Approximately 500 grams of northern red oak leaf litter was

collected in April 1996 from all six stands. The leaf litter was

oven-dried at 90 °C until a consistent mass was reached

and then two weeks more in order to limit resident microflora. Thus a total of 6 bulk samples, one from each stand

was available for use.

In order to assess decomposition, litter bags were used.

Bags made of 0.2 mm nylon mesh with dimensions of

20X10 cm were filled with 3 grams of the dried northern red

oak leaves. The mesh bags were closed with standard size

carbon steel staples. Twenty litter bags were filled with litter

from each stand. A total of 120 bags were prepared (20

samples for each of six litter sources).

A reciprocal transplant within blocks was the design used

for placing the litter bags in the field (fig. 1). Within each

stand, 10 litter bags with litter of “origin” in that stand and

10 litter bags with litter of “origin” in the other stand in that

block were buried. The litter bags were buried between the

organic layer and the A-horizon under 5 cm of leaf litter in

early May 1996. The litter bags were collected in midOctober after 167 days in the field. The leaves were removed

from the bags and washed with deionized water over a 0.01

mm sieve to remove clinging soil mineral fraction and root

material that had grown into the bag. All visible leaf material

was salvaged. The washed leaves were oven dried at 90 °C

until a consistent mass was reached. Results were analyzed

using nested ANOVA with blocks.

Table 1—SrCl2

 extractable Ca/Al ratios and soil pH from low mortality and high mortality plots

of northern red oak on Hickory Flats, Linn Run, and Jones Milla

 Hickory Flats Linn Run Jones Mills

Parameter Low High Low High Low High

0.01M SrCl2 extractable Ca/Al ratios and soil pHb

O-horizon 37.9 ± 7.6 9.1 ± 1.2 12.6 ± 4.1 7.9 ± 1.2 6.4 ± 0.8 27.8 ± 7.9

3.74 ± 0.04 3.77 ± 0.04 3.99 ± 0.02 3.95 ± 0.04 4.4 ± 0.03 4.0 ± 0.04

A-horizon 2.3 ± 0.4c 1.2 ± 0.6c 2.2 ± 1.0c 1.1 ± 0.4c 1.6 ± 0.5 1.2 ± 0.3

3.65 ± 0.04 3.60 ± 0.02 4.01 ± 0.04 3.65 ± 0.03 4.26 ± 0.03 4.09 ± 0.04

B-horizon 1.3 ± 0.5d 0.7 ± 0.4d 1.2 ± 0.4c 0.40 ± 0.3c 1.1 ± 0.2c 0.66 ± 0.3c

3.78 ± 0.04c 3.68 ± 0.03c 4.12 ± 0.03c 3.82 ± 0.02c 4.26 ± 0.02d 4.2 ± 0.03d

a n = 8-20 for each cell.

b Data presented as means±SE.

c Denotes significant difference between low and high mortality stands of decomposition within each block at 5

percent.

d Denotes significant difference between low and high mortality stands of origin within each block at 10 percent.

Figure 1—The reciprocal transplant design for decomposition of

northern red oak leaf litter from low and high mortality stands (leaf

origin) that was allowed to decompose on low and high mortality

stands.
156

Mineral content analysis was conducted on randomly

selected samples using Inductively Coupled Plasma

Emission Spectroscopy at the Pennsylvania State

University Agricultural Analytical Services Laboratory

following procedures of Dahlquist and Knoll (1978). Three

randomly chosen replicates of each of the 12 possible combinations of litter by origin and site of decomposition were

selected for a total of 36 samples. Three replicates of fresh

1995 oak litter from each of the 6 stands were also analyzed

to determine mineral content prior to decomposition. Data

were analyzed using ANOVA. In addition to physical decomposition and concentration of minerals in the sample before

and after decomposition, changes in total quantity of a

mineral in the sample were determined. Due to high variance in sample nutrient levels both prior to decomposition

and after decomposition, mean total quantity of a nutrient

prior to decomposition was determined by summing the

estimates for each litter origin. This gave a single estimate

of total quantity of the nutrient in a sample bag for each

litter origin (i.e. low and high mortality stands for each

block). Variance was determined for each pooled estimate

from differences between samples. Total nutrient level was

determined after decomposition by essentially the same

procedure. This resulted in 12 estimates of total nutrient

level (i.e. leaf litter from low and high mortality origin that

decomposed in low and high mortality sites of decomposition in each block). Percent of absolute gain or loss was

determined by the formula:

percent change = 

( )( )

( )

aa bb 100

b b

CM CM

C M

−

 (1)

where

Ca= concentration of nutrient after decomposition

Ma= mass of sample after decomposition

Cb= concentration of nutrient before decomposition

Mb= mass of sample before decomposition

Results were compared using computed standard errors.

RESULTS

Decomposition Rate

Significant decomposition occurred on all blocks. However,

the only block where a difference in rate of decomposition

was found between high and low mortality stands (site of

decomposition) was the Hickory Flats block (table 2). The

low mortality stand lost less mass (30 percent ± 3 percent)

than the high mortality stand (47 percent ± 3 percent; P

<0.01).

The only block where litter origin had an effect on rate of

decomposition was also the Hickory Flats block (table 3).

The litter that came from the low mortality stand lost less

mass (35 percent ± 3 percent) than the litter that came from

the high mortality stand (42 percent ± 3 percent; P <0.05).

A significant litter origin by site of decomposition interaction

was found (P <0.009). Litter from the low mortality stands of

all blocks decomposed more slowly when in the low mortality

stands than when in the high mortality stands (table 4) and

rates of physical decomposition were not related to soil Ca/

Al ratio.

Chemical Changes

Effect of site of decomposition—After decomposition, litter

originating from the low mortality stands tended to have

greater concentrations of P, Mn and lower concentrations of

Mg and Ca than litter originating from the high mortality

stands (table 2).

Table 2—Percent of physical decompositiona (n = 20 per cell) and concentration of mineralsa (n = 6 for each

cell) in remaining sample of northern red oak leaf litter that decomposed in low mortality and high mortality

stands (site of decomposition) of northern red oak in block established on Hickory Flats, Linn Run, and Jones

Mill

 Hickory Flats Linn Run Jones Mills

Parameter Low High Low High Low High

Decomp.(%) 30 ± 3b 47 ± 3b 43 ± 1 43 ± 2 23 ± 3 26 ± 5

Mass lost(g) 0.9 ± 0.09b 1.41 ± 0.09b 1.29 ± 0.03 1.29 ± 0.06 0.69 ± 0.09 0.78 ± 0.15

Ca(%) 0.56 ± 0.05b 0.75 ± 0.05b 0.58 ± 0.06b 0.93 ± 0.05b 0.67 ± 0.04b 0.74 ± 0.04b

Mg(%) 0.021 ± 0.001b 0.024 ± 0.001b 0.037 ± 0.001 0.038 ± 0.001 0.031 ± 0.001b 0.035 ± 0.001b

K(%) 0.071 ± 0.012 0.085 ± 0.008 0.094 ± 0.006 0.10 ± 0.011 0.129 ± 0.016 0.095 ± 0.011

P(%) 0.058 ± 0.01b 0.054 ± 0.003b 0.065 ± 0.006b 0.061 ± 0.001b 0.073 ± 0.005b 0.059 ± 0.005b

Mn(ug/g) 882 ± 46b 820 ± 50b 922 ± 34b 624 ± 65b 583 ± 30 647 ± 78

Fe(ug/g) 419 ± 87 312 ± 62 313 ± 58 349 ± 48 228 ± 67 248 ± 87

Cu(ug/g) 10.0 ± 2.6 9.8 ± 0.4 8.5 ± 0.75 8.4 ± 0.63 8.6 ± 0.75 8.2 ± 0.75

B(ug/g) 14.9 ± 2.1 16.8 ± 1.0 18.4 ± 2.7 17.7 ± 3.3 16.8 ± 2.3 17.8 ± 1.9

Al(ug/g) 998 ± 293 1014 ± 200 437 ± 31 356 ± 20 322 ± 36 321 ± 88

Na(ug/g) 82 ± 7.4 92 ± 6.5 38 ± 24 33 ± 11 54 ± 11 55 ± 10

Zn(ug/g) 115 ± 40 127 ± 20 155 ± 21 154 ± 18 157 ± 12 224 ± 10

a Data presented as means ± SE.

b Denotes significant difference between low and high mortality stands of decomposition within each block at 5 percent.
157

Litter that decomposed in the low mortality stands tended to

lose more Ca and Na and gain less Zn than litter that

decomposed in the high mortality stands (fig. 2). Litter that

decomposed in the low mortality stands tended to gain P

while litter that decomposed in the high mortality stands lost

P (fig. 2).

Prior to decomposition, litter from the low mortality stands

had significantly greater concentrations of Ca than litter

from the high mortality stands. This difference was significant for the Hickory Flats and Linn Run blocks (P <0.01).

Boron was greater for the low mortality stand on Jones Mill

than the high mortality stand (P <0.01).

After decomposition, no effect of litter origin was found in

concentration of Ca (except in Hickory Flats block); howTable 3—Percent of physical decompositiona (n = 20 per cell) and concentration of mineralsa (n = 6 for each

cell) in remaining sample of northern red oak leaf litter that originated in low mortality and high mortality stands

(litter origin) of northern red oak in blocks established on Hickory Flats, Linn Run, and Jones Mill

 Hickory Flats Linn Run Jones Mills

Parameter Low High Low High Low High

Decomp.(%) 35 ± 3b 42 ± 3b 41 ± 2 43 ± 4 23 ± 3 24 ± 3

Mass lost(g) 1.05 ± 0.09b 1.26 ± 0.09b 1.23 ± 0.06 1.29 ± 0.12 0.75 ± 0.09 0.72 ± 0.09

Ca(%) 0.67 ± 0.06 0.65 ± 0.06 0.66 ± 0.08b 0.84 ± 0.06b 0.75 ± 0.07b 0.66 ± 0.08b

Mg(%) 0.021 ± 0.001b 0.024 ± 0.001b 0.034 ± 0.002b 0.040 ± 0.003b 0.032 ± 0.004 0.034 ± 0.004

K(%) 0.084 ± 0.01b 0.072 ± 0.006b 0.112 ± 0.008b 0.083 ± 0.006b 0.138 ± 0.005b 0.086 ± 0.004b

P(%) 0.056 ± 0.01 0.056 ± 0.008 0.074 ± 0.006b 0.052 ± 0.01b 0.071 ± 0.005b 0.061 ± 0.005b

Mn(ug/g) 918 ± 116b 784 ± 84b 915 ± 185b 631 ± 128b 625 ± 105 605 ± 87

Fe(ug/g) 239 ± 61b 491 ± 57b 379 ± 41b 282 ± 27b 280 ± 111b 196 ± 45b

Cu(ug/g) 10.0 ± 1.2 8.8 ± 1.0 8.8 ± 0.5b 8.2 ± 0.4b 8.8 ± 0.2b 8.0 ± 0.3b

B(ug/g) 15.0 ± 1.0c 13.8 ± 0.8c 16.3 ± 0.8b 19.7 ± 0.8b 15.3 ± 0.9b 19.3 ± 1.0b

Al(ug/g) 510 ± 293b 1,501 ± 636b 422 ± 31b 371 ± 20b 377 ± 36b 265 ± 88b

Na(ug/g) 97 ± 7 62 ± 65 37 ± 25 34 ± 11 57 ± 17 52 ± 6

Zn(ug/g) 123 ± 46 119 ± 7 205 ± 65b 104 ± 30b 195 ± 25 186 ± 77

a Data presented as means ± SE.

b Denotes significant difference between low and high mortality stands of decomposition within each block at 5 percent.

c Denotes significant difference between low and high mortality stands of origin within each block at 10 percent.

Table 4—Percent decomposition and mass loss of leaf litter from low mortality and high mortality

stands (origin) that decomposed in low and high mortality stands (site of decomposition) of northern

red oak in blocks established on Hickory Flats, Linn Run, and Jones Mill

Leaf origina b Hickory Flats Linn Run Jones Mills

Site of

decomposition Low High Low High Low High

Low mortality 21 ± 3% 38 ± 3% 33 ± 2% 53 ± 2% 18 ± 3% 24 ± 3%

0.63 ± 0.09g 1.14 ± 0.09g 0.99 ± 0.06g 1.59 ± 0.06g 0.54 ± 0.09g 0.72 ± 0.09g

High mortality 43 ± 4% 62 ± 4% 45 ± 1% 43 ± 4% 23 ± 4% 20 ± 5%

1.29 ± 0.12g 1.86 ± 0.12g 1.35 ± 0.03g 1.29 ± 0.12g 0.69 ± 0.12g 0.60 ± 0.15g

a n = 10 for each cell.

b Data presented as means ± SE.

ever, since the litter from the low mortality stands started

the experiment with greater concentrations of Ca, the portion

that was lost was calculated. A tendency to lose more Ca

from the litter from the healthy sites was found (P <0.07).

After decomposition, the litter from the low mortality stands

had greater concentrations of K, P, Mn, Zn and Cu than the

litter from the high mortality stands (table 3). In absolute

terms, litter with origin in the low mortality stands lost more

K than litter with origin in the high mortality stands (fig. 3).

Litter with origin in the low mortality stands gained more Zn

and less Al than litter from the high mortality stands (fig. 3).

Litter from the low mortality stands tended to gain Na and P

while litter from the high mortality stands tended to lose both

elements (fig. 3). Across all samples, total amounts of B,

Mn, K, Mg and Ca after decomposition were lower and Al

and Zn were higher (figs. 2 and 3).
158

DISCUSSION

The high mortality stands selected for this study had a considerable amount of standing dead timber and lower Ca/Al

ratios in the A and B-horizons (Demchik 1998). These two

factors could have quite opposite effects on decomposition.

Increases in canopy gap size can increase decomposition

(Zhang 1995), but sites with low Ca/Al ratios may have

reduced rates of decomposition (Tamm 1976, Wolters 1991).

Of the blocks, only Hickory Flats showed significantly higher

decomposition rates in the high mortality stand. The more

open canopy may have resulted in greater decomposition

rates. This indicates that the difference in soil chemistry

between the sites, specifically the low Ca/Al ratios in the

soils of the high mortality site, did not reduce the decomposition rates.

The overall lack of significant difference in rates of decomposition between high and low mortality sites may be related

to the position of the litter bags in the soil column. The litter

bags were buried at the interface of the O-layer and A-horizon. The O-layer was not different in Ca/Al ratio between

stands (Demchik 1998). Even with differences in Ca/Al ratio

observed in the A-horizon, the actual effect of the Ca/Al

ratio may have been limited by bag placement.

While only limited differences occurred in rates of decomposition, the litter that decomposed in the low mortality stands

lost more Ca and Na and gained more P than litter that

decomposed in the high mortality stands. Transport of Ca is

controlled primarily by biological action (Laskowski and

others 1995). More favorable soil conditions on the low

mortality sites and greater site occupation by trees and

other vegetation may have resulted in greater Ca uptake

and processing by soil organisms. Ca that was not taken up

by vegetation may be more susceptible to leaching. The

gain of P is documented to occur in the early stages of

decomposition for Scots pine (Pinus silvestris) (Berg and

Staaf 1980). Leaf litter from the low mortality stands lost

more K and gained more P and Zn than leaf litter from the

high mortality stands. Potassium loss is primarily controlled

by leaching (Laskowski and others 1995). More K was

leached from the litter from the low mortality stands probably

because the amount tended to be a function of the amount

present. The greater accumulation of Zn and P in the litter

originating in the low mortality stands is probably caused by

either strictly chemical transport or by fixation with humic

compounds (Laskowski and others 1995) that are produced

in the earlier stages of decomposition (Edwards and others

1970). More research is required to elucidate the reason for

these differences.

While much variation was evident, some general observations can be made about the nutrient transport observed.

Of the soil bases, total level of Ca seemed to be the most

stable. Magnesium, K and Na had much higher rates of

loss. Laskowski and others (1995) found K and Mg to be

more mobile than Ca; however, Na was found to be less

mobile than all other soil bases (although this varied with

litter origin). Locally, the mobility of Na was of less importance than the other soil bases. For most forests of the

east, Na is only a major soil cation near the coast or adjacent to roadways, where NaCl is used to de-ice surfaces.

While Mn and B leached from the sample at rates roughly

similar to rates of decomposition, Zn and Al increased in

absolute mass. Laskowski and others (1995) found increases

in total level of Zn in litter and McBrayer and Cromack

(1980) found increases in Al. While Laskowski and others

(1995) suggested this as a natural process, they offered no

explanatory mechanism. Possible explanations may include

fecal deposition of soil mineral fraction by soil invertebrates,

adhesion of soil particles by leaching foliar polysaccharides

and root exudates. Additionally, since plant available Al was

problematic on these soils (Demchik 1998), possible formation of complexes of Al with P could explain these increases.

Figure 2—The change in total mineral content of northern red

oak leaf litter after decomposition for 167 days during the growing season of 1996 for the leaf litter allowed to decompose in

low and high mortality stands (n=6 bags per bar).

Figure 3—The change in total mineral content of northern

red oak leaf litter after decomposition for 167 days during

the growing season of 1996 for the leaf litter from low and

high mortality stands (n=6 bags per bar).
159

SUMMARY AND CONCLUSIONS

Collectively, more Ca and Na were lost from samples decomposing on sites with low mortality of northern red oak, even

though the overall rates of physical decomposition were

similar. Potentially, Ca was being actively transported from

this litter by plants and processed by soil biota. Ca remaining in litter may be more likely to leach with subsequent

inputs of hydrogen ions.

Origin of litter affected the loss and gain of nutrients. Litter

originating in the low mortality stands tended to lose more

K and gain more P and Zn than litter originating in the high

mortality stands. This litter had higher concentrations of

these minerals to begin with; consequently, more could be

expected to be lost as a consequence of mobile anion

driven leaching. The greater accumulation of Zn and P in

the litter originating in the low mortality stands was probably

caused by either chemical transport or by fixation with

humic compounds and Al. More research is required to

elucidate the reasons for these differences.

In general, of the soil bases, total level of calcium seemed

to be the most stable. Magnesium, K and Na had much

higher rates of loss. Manganese and B leached from the

samples at rates roughly similar to rates of decomposition.

Zinc and Al increased in absolute mass.

Overall, while several potentially important differences were

seen in the quantity of nutrients remaining after decomposition, no important differences in decomposition were found.

The more acidic soils of the high mortality stands may have

balanced the increased decomposition rates expected in

these more open stands.

LITERATURE CITED

Berg, B.; Staaf, H. 1980. Decomposition rate and chemical

changes of scots pine needle litter. II. Influence of Chemical

Composition. In: pp. 375-390. T. Persson (ed.), Structure and

Function of Northern Coniferous Forests: An Ecosystem Study,

Ecolological Bulletin, Stockholm, Sweden. Chapter 32:

Bray, J.R.; Gorham, E. 1964. Litter production in forests of the

World. In: pp. 101-157. J.B. Cragg (ed.), Advance Ecological

Resources, Academic Press, New York, NY, USA.

Cronan, C.S.; Grigal, D.F.; 1995. Use of calcium/aluminum ratios

as indicators of stress in forest ecosystems. Journal of Environmental Quality. 24: 209-226.

Dahlquist, R.L.; Knoll, J.W. 1978. Inductively coupled plasma

atomic emission spectrometer: analysis of biological materials

and major trace and ultra-trace elements. Applied Spectroscopy.

32(1): 1-29.

Demchik, M.C. 1998. The influence of soil nutrient conditions in

northern red oak stands on litter decomposition, tree growth

and tree mortality and the effect of soil nutrient amendments on

tree growth and stump sprouting on Pennsylvania’s Laurel Hill,

The Pennsylvania State University, School of Forest Resources,

Ph.D. Thesis.

Edwards, C.A.; Reichle, D.E.; Crossley, D.A. 1970. The role of soil

invertebrates in the turnover of organic matter and nutrients. In:

pp. 147-172. D.E. Reichle (ed.). Analysis of Temperate Forest

Ecosystems, Springer-Verlag, New York, NY, USA.

Lamb, D. 1976. Decomposition of organic matter on the forest floor

of Pinus radiata plantations. Journal of Soil Science. 27: 206-

217.

Laskowski, R.; Niklinska, M.; Maryanski, M. 1995. The dynamics of

chemical elements in forest litter. Ecology. 76(5): 1393-1406.

McBrayer, J.F.; Cromack, K., Jr. 1980. Effect of snow-pack on oaklitter release in a Minnesota forest. Pedobiologia. 20: 47-54.

North Dakota State University. 1988. Recommended chemical soil

test procedures for the north-central region. North Dakota

Agricultural Experiment Station, NDSU, Bulletin No. 499.

revised.

O’Connell, A.M. 1988. Nutrient dynamics in decomposing litter in

karri (Eucalyptus diversicolor F.Muell.) forests of Southwestern

Australia. Journal of Ecology. 76: 1186-1203.

Tamm, C.O. 1976. Acid precipitation: biological effects in soil and

on forest vegetation. Ambio. 5: 235-238.

Wolters, V. 1991. Effects of acid rain on leaf litter decomposition in

a beech forest on calcareous soil. Biological Fertility of Soils.

11: 151-156.

Zhang, Q. 1995. Effect of gap size on nutrient release from litter

decomposition in a natural forest ecosystem. Canadian Journal

of Forest Resources. 25(10): 1627-1632.
160

INTRODUCTION

Many cross timbers forests in central Oklahoma were neither

extensively logged nor farmed and may contain some of the

largest tracts of old-growth forests, particularly those dominated by oak, in eastern North America (Therrell and Stahle

1998). We studied a 90 ha old-growth forest in Osage

County, Oklahoma which is one of the few designated forest

preserves in the cross timbers. Our objectives were (1) to

examine changes in species composition and structure

across a topo-edaphic gradient and (2) to determine how

well these stands conform to traditional models of old-growth

stand structure.

MATERIALS AND METHODS

We delineated three stands based primarily on aspect and

elevation, sampled overstory and understory tree species,

and evaluated site characteristics in randomly placed 0.3 ha

plots in each stand. We used detrended correspondence

analysis (DCA) to identify important gradients in species

composition and canonical correspondence analysis (CCA)

to determine if measured site characteristics could help

explain such gradients. We fit the negative exponential and

rotated sigmoid curves to the diameter distributions for

Quercus stellata in each stand using least-squares regression. Distributions of estimated total and exposed crown

area by diameter class were predicted from regression

equations using measurements from a subset of Q. stellata

trees.

RESULTS AND DISCUSSION

Q. stellata dominated in all stands and Q. marilandica was

the second most common overstory tree. Juniperus virginia

was relatively rare as an overstory tree, but appeared to be

increasing in abundance, particularly in the most open stand.

The DCA and CCA revealed a moisture gradient along the

first axis. More mesic tree species, such as Q. velutina and

Q. shumardii, had the lowest scores along the first axis, while

more xeric species, such as Q. stellata and J. virginiana,

had the highest scores. Sandy soil texture and northeasterly slope positions were associated with more mesic forest

species. Neither the negative exponential nor the rotated

sigmoid curve accurately described the diameter distributions in any stand (R2

<0.95). The primary deviations from

the models were the constant or increasing abundance

from small to large saplings. The stands did not show equal

allocation of growing area among size classes, but tended

to have bimodal distributions with reduced crown area in

the mid-diameter classes. These stands may exhibit natural

population structures different than those of shade tolerant

species growing in mesic forests, for which previously developed models of old-growth structure have been developed.

However, deviations from models of balanced stand structure may be the result of recent fire disturbances.

ACKNOWLEDGMENTS

This research was partially supported by the U.S. Army

Corps of Engineers (contract DACW42-02-P-0043). We are

grateful to The Wilderness Society for their support through

the Gloria Barren Scholarship. The Nature Conservancy

provided technical assistance and allowed access to the

study site.

LITERATURE CITED

Therrell, M.D.; Stahle, D.W. 1998. A predictive model to locate

ancient forests in the Cross Timbers of Osage County,

Oklahoma. Journal of Biogeography. 25: 847-854.

CHARACTERIZATION OF AN OLD-GROWTH FOREST

IN THE CROSS TIMBERS OF OKLAHOMA

S.L. Clark and S.W. Hallgren1

1 Graduate Research Fellow and Associate Professor, Department of Forestry, Oklahoma State University, Stillwater, OK 74078, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.
161

Upland Oak Ecosystem

Restoration and Management
162
163

INTRODUCTION

The remarkable book by Johnson, Shifley, and Rogers

(Johnson and others 2002) covers much of what I am going

to say either directly or indirectly, and in greater depth.

However, I will provide a few additional insights based on

my work in oak silviculture over the last 30 years.

Upland oaks have two fundamental requirements for

successful regeneration and subsequent management,

both in oak-dominated systems and in systems where oaks

are important components of mixed hardwood forests.

These two requirements are:

1. the presence of competitive sources of oak regeneration

2. timely, sufficient release of these oak regeneration

sources.

The first requirement—competitive oak regeneration sources

—is a restatement of the First Law of Oak Silviculture; i.e.,

successful oak regeneration after harvest will come from

advance reproduction that exists in the current stand and

stump sprouts from trees that are harvested from the current

stand. I will discuss progress that has been made in assessing (1) the competitiveness of oak regeneration sources

and (2) silvicultural practices to develop competitive oak

regeneration sources.

The second requirement—timely, sufficient release—

concerns the timing and pattern of tree removal from the

existing stand to ensure the regeneration sources develop,

ultimately, into overstory trees. I will discuss a broader range

of silvicultural systems that can provide timely, sufficient

release than we envisioned 30 years ago.

COMPETITIVE REGENERATION SOURCES

Assessing Regeneration Potential

When I began research in oak regeneration, the notion was

well accepted that advance reproduction and stump sprouts

were the sources of successful regeneration after harvest

cutting. This First Law of Oak Silviculture was based on

early work done by Leffleman and Hawley (1925), Korstian

(1927), Liming and Johnson (1944), and on work in the

1950s, 1960s, and 1970s (Clark and Watt 1971, Sander

1971, Sander and Clark 1971).

The next logical step was important—the development of

methods and models to predict the oak component of the

next stand, based on the population of regeneration sources

in the current stand. The foundation of the models was the

relationship between the size of advance reproduction and

postharvest development (Sander 1971), and the relationship between tree size and age, and stump-sprout development (Johnson 1977). Researchers developed models for

the Ozarks (Dey 1991, Sander and others 1984) and for the

Southern Appalachian (Loftis 1990a). The models were

applied to sample data collected from stands considered for

harvest. For example, I developed a simple model that

predicted the probability of success of advanced red oak

reproduction 20 years after harvest (dominance probability)

based on the size of advance reproduction and oak site

index (Loftis 1990a). I also adapted dominance probabilities

for stump sprouts from Paul Johnson’s work (Johnson 1977).

Therefore, knowing the site index and the size distribution

of red oak regeneration sources, a silviculturist could predict what the oak component would be in the next stand.

This development of prediction models was an important

step forward. Previously, when we cut stands, we were

either satisfied with the outcome, or we lamented that the

oak component in the new stand was much less than we

desired or much less than was in the previous stand. With

the development of these models we had tools to give us

information on regeneration outcomes before we made the

cut, and an opportunity to apply different management

techniques to achieve a different outcome.

Even before I completed development of this model, I was

uneasy. It considered competition only implicitly as a function of site index. That is, my interpretation of the inverse

relationship between site index and dominance probability

was that competition increases as site quality increases.

For a stem of a given size, it is reasonable to expect that it

would have a better chance to become dominant or codominant on site index 70 than on site index 90. What bothered

me was the assumption of an “average competitive environment” when the competitive environment within even a

single stand can vary widely. In reality, it makes a huge

difference whether a 1-inch basal diameter advance red

oak stem is going to be competing against a yellow-poplar

stump-sprout or against other small advance reproduction.

UPLAND OAK REGENERATION AND MANAGEMENT

David L. Loftis1

1 Project Leader, USDA Forest Service, Southern Research Station, Asheville, NC 28806.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—In oak-dominated plant communities and in other communities where oaks are important, the keys to natural

regeneration of upland oak components are (1) to ensure presence of competitive regeneration sources, and (2) to

provide timely, sufficient release of these sources. Regeneration sources vary significantly among different types of plant

communities and disturbance regimes. Options for timely, sufficient release of oak regeneration sources include stand

structures associated with even-aged, two-aged, and uneven-aged silvicultural systems. I discuss the nature and

management implications of these variations, the regeneration options, and stress the importance of evaluating oak

regeneration potential.
164

Another thing bothered me. On higher quality sites where I

observed oaks competing successfully after crown closure

(stem exclusion stage), there was an absence of yellowpoplar. Apparently, at least on a patch-wise basis, abundant, well-developed advance reproduction of oaks (and

other species) competitively excluded yellow-poplar of

seedling origin. Height-age (site index) curves for yellowpoplar and oak (Beck 1962, Doolittle 1958, Olson 1959)

indicate that even when oak is free to grow at crown closure,

if surrounded by free-to-grow yellow-poplar, oak is going to

lose the battle. Only where yellow-poplar is excluded prior

to crown closure will oaks be successful. The patchy nature

of early regeneration development might not be apparent in

older stands, since a patch might ultimately contribute only

one or two dominant or codominant oak trees, and, by age

60, these big oaks would appear intimately mixed with other

species.

Since the 1980s I have been trying to flesh out an intuitive,

conceptual model that addresses these phenomena, a

model in which competition among regeneration sources is

the main driver (Loftis 1989). The prediction system builds

on the concepts of Egler (1954) and Noble and Slatyer

(1980), as well as the applied work of Johnson (1980) and

Marquis (1984). The predictions of postharvest species

composition at the time of crown closure are driven by data

collected from small plots, say 0.01 acre, in the mature stand

in which all existing regeneration sources are enumerated

by size class. The model will stochastically add new seedlings of some species, e.g. yellow-poplar to plots when

appropriate, and it will stochastically add stump sprouts

from trees present on the plot. The model chooses several

“winners” on each plot from the existing reproduction

sources and from added seedlings on that plot, based on a

ranking of expected postharvest performance. The model

then combines the winners from each plot into a summary

of stand-level species composition; including, but not

restricted to oaks. This modeling approach provides the

capability to deal with altered competition situations resulting from silvicultural practices. These practices might include

the elimination of stump sprouts with herbicides or an altered

size class distribution of regeneration sources resulting from

silvicultural treatments designed to enhance advance reproduction development. I have developed a computer prototype of this model and an enhanced version should be

available in 2004.

In the last two decades researchers have developed useful

evaluation tools and prediction models. I hope managers

will use these models in the silvicultural prescription process

in the future. Assessing regeneration potential is the critical

first step in regenerating oaks.

Enhancing Regeneration Potential for Oaks

If these models predict an unsatisfactory oak component in

the next stand, we must do one of the following:

1. make the oaks more competitive

2. reduce competition from other species

3. do a combination of the two.

Either directly or indirectly, successful silvicultural treatments are going to cause one of these outcomes. This

simple construct provides a useful context for discussing

silvicultural treatments designed to favor oaks.

In a given stand, there is not a lot we can do to alter the

population of oaks that will produce stump sprouts. To make

oaks more competitive, we must increase the number and

size of advance reproduction, enhancing their ability to

sustain more rapid height growth after release. For oakdominated ecosystems on more xeric sites, oak advance

reproduction that can compete successfully after disturbance accumulates over time in mature stands. However,

on more mesic sites oak advance reproduction that can

compete after disturbance does not accumulate in mature

stands (Johnson and others 2002, Loftis 1983a). Rather, it

cycles in and out of the system with new seedling establishment after good acorn crops followed by mortality. But the

survivors at any point do not develop into advance reproduction of a size that would be competitive if released by

overstory removal (Loftis 1983a, McGee 1967). Interrupting

this cycle of establishment and mortality to enhance survival and growth of advance oak reproduction requires a

silvicultural treatment that alters stand structure and the

light environment. By removing midcanopy and some lower

canopy trees with herbicides, leaving a main canopy with

no large gaps, we have increased survival and growth of

small oak advance reproduction in the Southern Appalachians (Loftis 1990b). This treatment allows the population of

small oak advance reproduction to develop after a few

years into a population of larger advance reproduction,

making oaks more competitive after release. This process

also reduces competition from other species. Potential

sprouts from midcanopy and lower canopy trees are treated

with herbicides, thereby directly reducing competition from

these trees both before and after overwood removal. The

reduction in competition from yellow-poplar is more subtle.

First, while the residual canopy with no canopy gaps is

sufficient to allow oak seedlings to develop, it is not sufficient to allow the establishment and development of yellowpoplar. Secondly, new yellow-poplar seedlings that become

established after overwood removal will be in an inferior

competitive position, at least on a patch-wise basis, because

of the development of large advance reproduction of oaks

and other species.

Prescribed burning is another silvicultural treatment that

has received a great deal of attention over the past 20

years. A number of hypothetical mechanisms might favor

oak reproduction:

1. burning could alter stand structure and the light environment, providing for the development of larger advance

reproduction—making oaks more competitive

2. burning could top-kill poorly formed oak advance reproduction, transforming them from stems that would respond

slowly to release into thrifty sprouts that respond quickly

to release—making oaks more competitive

3. burning, particularly recurrent burning, could kill or inhibit the development of competing vegetation—reducing

competition from other species
165

4. burning could alter the seedbed, resulting in increased

establishment of more oak seedlings—making oaks

more competitive

5. burning could adversely affect insect predators of acorns,

resulting in more oak seedlings—making oaks more

competitive.

Understanding the role of fire in oak ecosystems and devising useful prescriptions to effect desired oak regeneration

outcomes requires that these and other hypotheses be

tested. Several ongoing studies are testing these hypotheses in various places and in different kinds of oak ecosystems. For example, after a single fire on relatively mesic

sites in the Southern Appalachians, I found that survival of

northern red oak seedlings was reduced on burned plots,

and that, over time, surviving oak seedlings grew no better

or worse than seedlings on nonburned plots (Loftis 1990b).

Burning had no apparent effect on stand structure and the

light environment. On somewhat less mesic sites, prescribed

burning reduced the number and vigor of yellow-poplar

competitors after burning in stands where a shelterwood cut

had been conducted several years before (Brose and Van

Lear 1998). Several other studies are ongoing (Dey and

Hartman, in press; Iverson and others, in press) and viable

prescriptions for prescribed burning may emerge from some

of these studies. Workable prescriptions may differ from one

upland oak ecosystem to another, and there may be some

ecosystems where prescribed fire may play no role at all.

Another area of silvicultural practice is planting. Researchers

have expended a good deal of effort developing technology

to produce oak seedlings that can perform satisfactorily

after outplanting (Johnson 1988, 1989; Kormanik and

others 1998) making oaks more competitive. Some have

suggested that the best opportunities for planting oaks

successfully are on sites of intermediate quality, in a site

index range from 60 to 75 feet (Johnson and others 2002)

where competition is less severe. Attempts to plant oaks on

higher quality sites have certainly met with limited success

(Loftis 1979, McGee and Loftis 1986). Planting in clearcuts

on mesic sites in the Southern Appalachians where site

index exceeds 80 feet requires herbicides to reduce competition of other species, yellow-poplar in particular (Personal

communication. 2000. Paul Kormanik, Silviculturist, USDA

Forest Service, Southern Research Station, Forestry

Sciences Laboratory, Athens, GA 30602-2044).

Another approach to planting oaks is planting under a shelterwood (Johnson and others 1986; Weigel and Johnson

1998a, 1998b). This approach is somewhat analogous to

the shelterwood method described above for natural regeneration. However, in this case, the advance reproduction is

planted in conjunction with a shelterwood and given a few

years to become well established and to expand root systems before a partial or final removal cut opens the stand

and the associated competition develops, making the oaks

more competitive. Treating understory and midcanopy trees

during the period under the shelterwood both increases

light for the planted oaks and reduces competition from

other species after overwood removal (Johnson and others

2002).

In my opinion, devising and implementing silvicultural strategies to favor oaks should usually involve treatments that

both make oaks more competitive and that reduce competition from other species. The modeling approach I outlined

is designed, at least conceptually, to provide insights into

how well treatments accomplish these objectives on a

stand-specific basis.

Intermediate stand treatments can also be used to directly

favor oak and typically do so by reducing competition from

other species in such operations as cleanings and thinning

(Shifley, in press).

TIMELY, SUFFICIENT RELEASE OF OAK

REGENERATION SOURCES

A generation ago the prevailing opinion was that even-aged

silviculture was the preferred approach to managing oak:

“Oak grows best in full sunlight, and oak silviculture should

be even-aged.” (Clark and Watt 1971: p. 38).

In the ensuing 30 years, we have found a number of ways

to provide timely, sufficient release of oak regeneration

sources that result in silviculture classified as other than

even-aged.

Where competitive oak regeneration sources are present,

either as a result of intrinsic processes or as a result of

prior disturbances, clearcutting or overstory removal will

result in successful oak regeneration (Beck 1988, Johnson

and others 2002, Roach and Gingrich 1968). Successful

oak regeneration has also been achieved by applying a

two-cut shelterwood when competitive advance reproduction was present at the initial cut (Loftis 1983b). In this case,

residual basal areas after the initial cut included plots with

33 and 66 square feet, and the level of overwood retention

did not result in any differential species response. Yellowpoplar and other less shade-tolerant species developed

about as they would have in a clearcut, although with some

reduction in height growth. Normally, a final removal cut

would be made no more than 10 to 20 years after the initial

cut to ensure continued development of the oak regeneration.

The shelterwood method I designed to take advantage of

differential species response between northern red oak and

yellow-poplar may not work everywhere (Shuler and Miller

1995) or may need to be modified for different ecosystems.

And in some ecosystems, an aggressive, shade-tolerant

species, e.g. sugar maple, might be better able to take

advantage of the modest increase in the light resource than

oak.

Even-aged silviculture has been successful for oak regeneration. As noted earlier, when competitive regeneration

sources are present as a result of intrinsic processes,

disturbance, or treatment, a shelterwood will result in

successful oak regeneration. Therefore, it is reasonable to

believe that a lower residual basal area shelterwood—a

shelterwood with reserves—designed to create a two-aged

stand would also successfully regenerate oak. Oak did

regenerate well on one lower quality site where we reduced

basal area to about 20 square feet per acre, where stumpsprout potential was high, and large advance reproduction

was present at the time of the cut. In another stand on a
166

high-quality site where we had reduced midcanopy and

lower canopy trees to favor the development of large oak

advance reproduction, successful oak regeneration is

occurring at crown closure 5 years after creating a shelterwood with reserves. The patches at this site are large

enough to ensure that oak will be a component of the next

new stand. These methods create stands that “may be twoaged or tend towards an uneven-aged condition as a consequence of both an extended period of regeneration and the

retention of reserve trees that may represent one or more

ages classes” (Helms 1998: p. 151). Two-aged methods

provide more complex stand structures to satisfy nontimber

objectives.

Uneven-aged silviculture applied to oak stands offers

intriguing possibilities and uncertainties. Managers may

have some concerns over whether to apply group selection

as an extension of the structural control methodology

developed for single-tree selection, or as small-scale area

control. However, in terms of biological response, oaks can

be successfully regenerated if competitive regeneration

sources are present when the openings are created. In the

Southern Appalachians, in group-selection openings of

one-fifth acre or larger, the same species composition

develops as in much larger clearcut openings (Beck 1988).

Yellow-poplar, one of our more shade-intolerant species,

regenerated quite well in these small openings 25 years

after they were created. An intriguing possibility is related to

a common response observed along edges of group-selection openings and extending into the surrounding stand.

The increase in light penetrating into the surrounding stand

usually results in development of oak advance reproduction

if small oak seedlings are present when openings are

created, providing an opportunity to favor oaks in regeneration with a subsequent enlargement of the opening. In

addition, group selection should provide, at least theoretically, the flexibility necessary to take advantage of the

sometimes patchy distribution of competitive, large advance

reproduction in forest stands.

Regenerating oaks using single-tree selection has generally been viewed negatively. In a Southern Appalachian

study of single-tree selection on relatively mesic sites

(Della-Bianca and Beck 1985), oak regeneration and

regeneration of other overstory species generally has been

far from sufficient. Since 1946, managers have applied

structural control using a reverse-J distribution with residual

basal area target of 65 square feet, a maximum diameter of

34 inches and a q of 1.4 (2-inch classes). After more than

50 years and four cutting cycles, we have a stand that

roughly approximates a reverse-j (negative exponential)

distribution, but most of the smaller diameter trees are

noncanopy, shade-tolerant species. In the study, the recent

addition of the application of herbicides has produced some

encouraging trends with respect to development of large

oak advance reproduction. However, how or if we can

provide timely, sufficient release of this advance reproduction using single-tree selection remains to be seen.

On the other hand, there is at least one documented success

using single-tree selection in the relatively more xeric western range of oaks (Lowenstein 1996). It seems reasonable

to wonder whether or not some form of single-tree selection

might also work on xeric sites in other parts of the oak

range where advance reproduction capable of competing

after release tends to be abundant.

CONCLUSIONS

There are a number of conclusions about regeneration and

management for which we can find general consensus:

• The First Law of Oak Silviculture has not been repealed.

We have to have competitive oak regeneration sources

present when we begin removing the stand

• These competitive oak regeneration sources can result

from natural stand processes including natural disturbances, or

• We can implement silvicultural treatments to develop

competitive regeneration sources.

• These silvicultural treatments can (1) make oaks more

competitive, (2) reduce competition from other species,

or (3) both of the above

• Management of oak stands can potentially be evenaged, two-aged, or uneven-aged

• We still have a lot to learn

LITERATURE CITED

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Brose, P.H.; Van Lear, D.H. 1998. Responses of hardwood

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Research. 28: 331-339.

Clark, F.B.; Watt, R.F. 1971. Silvicultural methods for regenerating

oaks. In: Proceedings of the oak symposium. Upper Darby, PA:

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symposium: history, current conditions, and sustainability. Gen.

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sustainability. Gen. Tech. Rep. Asheville, NC: U.S. Department

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development in the Missouri Ozarks. Res. Pap. NC-149. St.

Paul, MN: U.S. Department of Agriculture, Forest Service,

North Central Forest Experiment Station. [Number of pages

unknown].

Johnson, P.S. 1988. Undercutting alters root morphology and

improves field performance of northern red oak. In: Proceedings of the 10th North American For. Biol. Workshop: 316-323.

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on forest sites with special reference to northern red oak. In:

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[Place of publication unknown]: [Publisher unknown]: 46-62.

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Planting northern red oak in the Missouri Ozarks: a prescription. Northern Journal of Applied Forestry. 3: 66-68.

Johnson, P.S.; Shifley, S.R.; Rogers, R. 2002. The ecology and

silviculture of oaks. CABI Publishing. 503 p.

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Forest Park, GA: Southeastern Lumber Manufacturing

Association: 17-19.

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Effect of seedling size and first-order lateral roots on early

development of northern red oak on mesic sites. Gen. Tech.

Rep. SRS-20. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southern Research Station: 247-252.

Korstian, C.F. 1927. Factors controlling germination and early

survival in oaks. Yale University Sch. For. Bull. 19. [Place of

publication unknown]: [Publisher unknown]. [Number of pages

unknown].

Leffelman, L.J.; Hawley, R.C. 1925. The treatment of advance

growth arising as a result of thinnings and shelterwood cuttings.

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unknown]: [Publisher unknown]. [Number of pages unknown].

Liming, F.G.; Johnson, J.P. 1944. Reproduction in oak-hickory

forest stands of the Missouri Ozarks. Journal of Forestry. 42:

175-180.

Loftis, D.L. 1979. Northern red oak performs poorly in North

Carolina planting. Res. Note SE-277. Asheville, NC: U.S.

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Southern Appalachians: a research approach. Gen. Tech. Rep.

SE-24. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station: 144-150.

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hardwood stands with the shelterwood method. Southern

Journal of Applied Forestry. 7: 212-217.

Loftis, D.L. 1989. Species composition of regeneration after clearcutting Southern Appalachian hardwoods. In: Miller, James H.,

comp. Proceedings of the fifth biennial southern silvicultural

research conference. Gen. Tech. Rep. SO-74. New Orleans:

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advance red oak reproduction in the Southern Appalachians.

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in the Southern Appalachians. Forest Science. 36: 917-929.

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of a managed uneven-aged oak forest. Columbia, MO:

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treatments in hardwood stands of the Alleghenies. Gen. Tech.

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stands. Res. Note SE-72. Asheville, NC: U.S. Department of

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Station. 6 p.

McGee, C.E.; Loftis, D.L. 1986. Planted oaks perform poorly in

North Carolina and Tennessee. Northern Journal of Applied

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predict successional changes in plant communities subject to

recurrent disturbances. Vegetatio. 43: 5-21.

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Southeast. Res. Note 125. Asheville, NC: U.S. Department of

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Station. [Number of pages unknown].

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central hardwoods. Agric. Handb. 355. [Place of publication

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size of advance reproduction. Journal of Forestry. 69: 809-811.

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forests in the Central States. Agric. Handb. 405. [Place of

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Service. [Number of pages unknown].

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advance reproduction in the Missouri Ozarks. Res. Pap. NC251. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station. [Number of

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establish oak reproduction on mesic forest sites in West

Virginia—10-year results. Gen. Tech. Rep. NE-197. Radnor,

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

Northeastern Forest Experiment Station: 375-387.

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the Ozark Highlands: a shelterwood prescription. Tech. Brief

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Ozark Highlands: a shelterwood prescription. Tech. Brief TBNC-5. St. Paul, MN: U.S. Department of Agriculture, Forest

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168

INTRODUCTION

Over the past 400 years or more, fires burned throughout

the Ozarks, shaping the nature of the vegetation (Ladd

1991, Guyette and Cutter 1991, Cutter and Guyette 1994,

Guyette and others 2002). The frequency of fire varied

across the Ozarks with changes in topography and was

modified throughout time by humans. The net result was a

mosaic of pine and oak savannas and woodlands and mesic

hardwood forests (Batek and others 1999). Today, however,

fire occurrence in the Ozarks has been drastically reduced.

In Missouri, fires usually burn less than 50,000 acres per

year throughout a 16 million acre area that encompasses

the Ozark Highlands (Westin 1992). Individual fires average

less than 20 acres, and humans cause nearly all (> 99 percent) of these fires.

Since the advent of fire suppression in the 20th century,

savanna and woodland communities have developed into

mature, closed-canopied forests as tree density and stocking and vertical structure of woody species have increased.

Managers of federal and state natural resource agencies

are reintroducing fire using prescribed burning to restore

oak/pine savannas and woodlands, to restore glade and

fen communities, to promote native biodiversity, and to

restore historic disturbance regimes. Large area burns

(500 acres to 7,000 acres) are being done throughout the

Ozarks.

The Nature Conservancy (TNC) is restoring fire through

prescribed burning on approximately 2,500 acres of their

Chilton Creek Preserve in the Missouri Ozark Highlands.

Their fire plans are guided by information provided by

Guyette and others (2002) who have documented mean fire

intervals of 3.6 and 4.1 years just west of Chilton Creek

during the historic period 1700 to 1820, which predates

most European settlement in the area. TNC’s management

objective is to use fire to restore the quality and ecological

integrity of terrestrial natural communities and improve

habitat for species of conservation concern in the Ozarks

where fire has long had a strong influence on ecosystem

structure and function. They are intensively monitoring the

response of vegetation and other selected biota to a set

of fire treatments that differ primarily in the frequency of

burning. In this paper, we present the response of tree

advance reproduction after four years of implementing the

fire treatments.

METHODS

The Chilton Creek Preserve is a 5,657 acre site located

along the Current River in Shannon and Carter Counties,

Missouri (T 28 N, R 1 W) (fig. 1). The site lies within the

Current River Hills subsection of the Ozark Highlands (Keys

and others 1995), an area characterized by rugged, steeply

dissected valley and hollows and narrow ridges (approximately 500 foot relief). The area is covered in relatively

continuous oak-hickory and oak-pine woodlands and

mature forests growing on excessively drained cherty clay

residuum. Based on an inventory of overstory trees [with

diameter at breast height (d.b.h.) ≥ 4.5 inches], we found

that basal area averaged 79 ft2 per acre (range 38 to 160),

and stocking was 69 percent (range 36 to 120) [according

to Gingrich (1967)] on the subset (n = 26) of circular halfacre plots used in our study.

The Chilton Creek watershed was divided into five management units (fig. 1) of approximately 500 acres each (table 1).

All units were burned in the spring of 1998 to initiate the

process of restoring fire. Thereafter, units were burned

during the dormant season (usually in March or April) on a

randomly selected 1 to 4 year return interval basis, with the

exception of the Kelly North management unit, which was

burned annually (table 1).

We sampled individual stems of advance reproduction on

26 of the 250 (0.5-acre) permanent vegetation plots (fig. 1).

Initial stem measurements were done in the fall of 1997,

before the first burn. We recorded species, stem basal

diameter one-inch above the ground, d.b.h., and height on

2,741 stems that were distributed among the five management units (table 1). Overall, the basal diameter of all stems

EFFECTS OF DIFFERENT LARGE-SCALE PRESCRIBED BURNING REGIMES

ON ADVANCE REPRODUCTION IN THE MISSOURI OZARKS

Daniel C. Dey and George Hartman1

1 Research Forester, USDA Forest Service, North Central Research Station, Columbia, MO 65211; and Fire Ecologist, Missouri Department

of Conservation, Columbia, MO 65201, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—In 1997, The Nature Conservancy initiated a large-scale prescribed fire management study on approximately

2,500 acres of their Chilton Creek property located in Shannon and Carter counties, Missouri. Since the spring of 1998,

five management units, of roughly 500 acres each, have been burned in the dormant season to simulate a range of fire

regimes that vary from annual fires to fire free intervals that average from 1 to 4 years. The intent is to simulate high

frequency, low intensity fires that occurred historically in the watershed and study fire effects on the biota. The overstory

was inventoried on half-acre permanent plots located in the different burn treatments. Survival and height growth of the

advance reproduction was recorded on smaller plots nested within the half-acre plots. In this paper, we present the effects

of the different burning regimes on the advance reproduction.
169

Figure 1—Location of the Chilton Creek Preserve and study area with locations of vegetation

sampling plots (circles) and the subset of plots (triangles) we used to evaluate the effects of

fire on advance reproduction.

Table 1—Schedule of prescribed burns conducted at Chilton

Creek during the dormant season in each of the management

units; size of each unit with the distribution of study trees is also

presented

 Dormant season fire Advance

Burn unit 1998 1999 2000 2001 Acres reproduction (N)

Kelly South X X X 403 363

Kelly North X X X X 603 542

Chilton South X X X 725 1,123

Chilton North X 464 358

Chilton East X 254 355
170

ranged between 0.1 and 6.0 inches, and heights varied

from 0.1 to 50 feet (table 2). In the fall of 1998 and 2001,

we inventoried all stems and counted the number of sprouts

and measured the height of the tallest sprout for surviving

trees that had been topkilled by previous fires.

Fuel loading was estimated before each burn using two

permanent 50-foot transects on each plot following the

methods of Brown (1974) and Brown and others (1982).

Total fuel loads averaged 4.3 to 5.9 tons per acre for any

given burn year, and herbaceous/litter fuels accounted for

much of the total tonnage (table 3). Weather conditions

before each burn were recorded onsite using a belt weather

kit or Kestrel 3000 weather meters. Weather during the

burn was recorded at the National Park Service station

located 4 miles from the study area. Temperatures during

most burns were between 60 to 75 oF, winds were generally

less than 4 miles per hour, and relative humidity ranged

from 33 to 44 percent (table 3).

During each burn, we estimated flame length, rate-of-spread

and flaming front temperature (table 3). Flame length was

measured with passive flame height sensor arrays, which

consisted of 20 lengths of cotton string soaked in flame

retardant that were suspended from wires positioned 10 feet

above the fuel bed. Visual measurements of flame angles

were used to convert flame height to flame length according to Ryan (1981) and Finney and Martin (1992). Visual

estimates of flame lengths were also made during the burns

by observers. Flame lengths were highly variable but often

were in the range of 1 to 3 feet. Rate-of-spread was determined by direct observation using a stopwatch to time the

movement of the flaming front over a known distance or by

using arrays of modified clock assemblies that were buried

in the soil along a transect (Grabner 1996). Rates-of-spread

were also variable, but the fire front usually moved at a rate

of 3 to 16 chains per hour. Fire temperature along the flame

front was measured using temperature sensitive paints

applied to aluminum tags that were suspended from 9 gauge

Table 2—Pre-burn seedling and sapling basal diameter, diameter

breast height, and total heighta

Species N BD D.b.h. HT

 - - - - - inches - - - - - feet

White oak 346/185 1.4 ± 1.5 1.9 ± 1.2 10.8 ± 11.7

Scarlet oak 156/56 1.0 ± 1.4 1.9 ± 1.3 7.3 ± 11.4

Blackjack oak 56/25 1.7 ± 1.8 2.9 ± 1.1 9.6 ± 10.5

Chinkapin oak 106/31 0.6 ± 0.9 1.2 ± 1.0 4.6 ± 6.3

Post oak 180/79 1.2 ± 1.4 2.0 ± 1.1 7.8 ± 9.4

Black oak 224/92 0.9 ± 1.3 1.6 ± 1.3 7.5 ± 10.6

Pignut hickory 299/179 1.4 ± 1.4 1.8 ± 1.0 10.7 ± 10.8

Black hickory 128/53 1.1 ± 1.2 1.6 ± 1.1 6.9 ± 7.5

Mockernut hickory 296/153 1.0 ± 1.1 1.3 ± 0.9 7.5 ± 7.4

Flowering dogwood 316/192 1.4 ± 1.3 1.7 ± 1.0 10.1 ± 12.2

Blackgum 240/156 1.3 ± 1.2 1.5 ± 0.9 9.7 ± 7.8

Persimmon 32/10 0.5 ± 0.5 1.0 ± 0.5 4.3 ± 4.9

White ash 65/29 0.9 ± 0.9 1.2 ± 1.0 6.7 ± 6.0

Sassafras 286/115 0.8 ± 1.0 1.4 ± 0.9 7.3 ± 8.0

Shortleaf pine 74/53 1.9 ± 1.5 2.0 ± 1.2 11.5 ± 7.9

BD = basal diameter; d.b.h. = diameter at breast height; HT = total height; N =

the first sample size.

a The first sample size is given for BD and HT, and the second is for d.b.h.

(means and one standard deviation are presented).

Table 3—Fuel conditions, fire weather, and behavior for each of the prescribed burns

 Fuel characteristics Fire behavior

 Moisture Load Weather Temp.

Burn 1- 10- 100- 1- 10- Sur- 1- 2-

year Slope hr. hr. hr. hr. hr. Herb. Total Wind Temp. RH FL ROS face ft. ft.

 - - - - - - - percent - - - - - - - - - - - - tons per acre - - - - - mph oF % ft. ch/hr - - - - - oF - - - - -

1998 4 – 36 8 8 13 0.24 0.94 3.5 5.9 2 – 4 65 – 75 39 3.2 15.8 589 309 246

1999 11 – 25 8 8 16 0.27 1.4 1.8 4.3 0 – 2 59 – 69 44 1.0 5.9 361 179 154

2000 4 – 33 7 7 14 0.3 1.6 2.2 5.2 0 – 2 68 – 76 36 1.5 6.5 470 232 184

2001 4 – 33 7 7 12 0.24 1.3 1.9 4.6 0 – 2 50 – 64 33 1.1 2.7 250 153 150
171

steel rods (Cole and others 1992). Tags were hung at the

fuel surface, and at 1- and 2-foot heights above the fuel

surface on each rod. Temperatures were highest at the fuel

surface (ground level) and reached 250 and 600 o

F.

For each species, we used logistic regression (Allison 1999)

to model the probability of survival in 1998 (after one burn)

based on initial basal diameter, initial height, and the interaction between basal diameter and height. Similarly, we

modeled the probability that a stem of advance reproduction

would be alive in 2001 (4 years after burn treatments were

begun) based on initial stem size and number of times the

reproduction was burned. We used an information-theoretic

approach to modeling the probability of survival for advance

reproduction that had experienced prescribed burning

(Burnham and Anderson 2002). The set of apriori models

for each species was ranked using Akaike’s Information

Criterion, AIC, which were adjusted for small sample sizes

(AICc) when necessary. AIC values were used to compute

the AIC and Akaike weight (wi) for each model. These

statistics (i.e., AIC and wi) were used to identify models

that performed well and for estimating the support a model

had for being the best. Models with a lower AIC and a

greater wi

 have more support for being the better models of

those being compared. In all comparisons for a species, we

included the null (intercept only) model.

RESULTS AND DISCUSSION

1998 Fire Damage – After One Burn

Mortality of advance reproduction after one spring burn

was generally below 10 percent for most species (table 4).

Mortality was low (i.e., < 5 percent) in hickory (Carya), blackgum (Nyssa sylvatica Marsh.), sassafras (Sassafras albidum

(Nutt.) Nees), chinkapin oak (Quercus muehlenbergii

Engelm.), and blackjack oak (Quercus marilandica

Muenchh.). Sassafras had the lowest mortality (0.3 percent)

and shortleaf pine (Pinus echinata Mill.) had the highest

(38 percent). White oak (Quercus alba L.), post oak (Quercus

stellata Wangenh.), black oak (Quercus velutina Lam.),

scarlet oak (Quercus coccinea Muenchh.), and flowering

dogwood (Cornus florida L.) experienced relatively moderate levels of mortality (i.e., 5 to 10 percent). For all species,

stems of advance reproduction averaged about 1 inch in

basal diameter (table 2), and diameters ranged from 0.1 to

6.0 inches.

We found that initial basal diameter and height of advance

reproduction were significantly (α = .05) related to the probability of survival one year after a dormant season fire,

regardless of species, based on logistic regression analyses. The full model used to predict survival after one burn,

which included initial basal diameter and height, and their

interaction, had strong support for being one of the best

models considered for flowering dogwood (wi = 0.94) and

for black oak (wi = 0.88). The full model had moderate

support (wi

 = 0.62) in explaining blackgum’s response to a

prescribed burn. For the other species, subset models that

contained intial basal diameter, intial height, or a combination of the two variables had moderate support for being in

the set of best survival models (wi

 varying from 0.25 to

0.63). For all species, there was no support (wi

 = 0) for the

null hypothesis model (intercept only model). The Hosmer

Lemeshow goodness-of-fit test on the full model showed a

good fit of the model for all species except black oak. In

Table 4—Fire damage to advance reproduction one growing season after one or more (i.e., 3 to 4)

springtime prescribed burns

Minimum basal

 Sample Topkill diameter for < 10

size Mortality with sprouts Total damage percent mortality

(1/3+) 1 3+ 1 3+ 1 3+ 1 3+

Species burns burn burns burn burns burn burns burn burns

 - - - - - - - - - - - - - - percent - - - - - - - - - - - - - - - - - - - - inches - - - - - -

White oak 346/255 5 22 52 63 57 85 0.2 4.5

Post oak 180/145 9 21 64 74 73 95 0.3 2.0 (3 burns)

2.6 (4 burns)

Chinkapin oak 106/54 5 17 76 74 81 91 0.2 0.1 (3 burns)

2.2 (4 burns)

Scarlet oak 156/121 10 44 65 53 75 97 0.3 5.1

Black oak 224/170 10 28 70 69 80 97 0.7 1.6 (1 foot)

1.8 (5 foot)

2.2 (10 foot)

Blackjack oak 56/37 4 41 80 59 84 100 0.2 > 6

Hickory 723/520 3 17 94 70 97 87 0.1 6 (< 10 foot)

1.5 (10 foot)

Flowering dogwood 316/245 5 52 82 38 87 90 1.75 > 6

Blackgum 239/185 2 50 49 38 51 88 0.1 > 6 (1-10 foot)

Sassafras 286/216 0 9 79 84 79 93 0.1 0.1

White ash 65/44 14 25 61 70 75 95 0.5 0.6 (1-5 foot)

Shortleaf pine 74/18 38 39 18 39 56 78 3.75 > 6
172

other studies, tree stem diameter has been correlated to

survival after burning because it is directly related to bark

thickness and tree height, and hence to a tree’s ability to

resist heat injury to the cambium or to the crown (Hare 1965,

Loomis 1973, Hengst and Dawson 1994, Regelbrugge and

Smith 1994).

The probability of survival increased rapidly with increasing

basal diameter for most species, but less so with flowering

dogwood and shortleaf pine (fig. 2). In general, the minimum basal diameter needed for survival to be at least 90

percent was less than 0.5 inch for most species (table 4).

However, flowering dogwood and shortleaf pine advance

reproduction had to be larger than 1.8 and 3.8 inches,

respectively, before their chances of survival exceeded

90 percent.

Total fire damage (sum of mortality and topkill) was high

after one dormant season fire (table 4). Most of the fire

damage to advance reproduction was topkilled seedlings

that sprouted during the following growing season. Waldrop

and Lloyd (1991) observed that low to moderate intensity

surface fires can topkill most hardwood stems that are less

than 4 inches in diameter, and that mortality declines as

Figure 2—The probability that advance reproduction will be alive one growing season after a dormant

season prescribed fire based on the initial basal diameter and species. All logistic models shown

were significant (α = 0.05) and had at least moderate support according to the Akaike weight (wi

).
173

tree diameter increases above 4 inches. Dormant season

fires also promote hardwood sprouting after topkill because

carbohydrate reserves in the root system are still at relatively high levels. White oak, blackgum, and shortleaf pine

had the lowest overall amount of fire damage.

2001 Fire Damage – After One, Three, or Four

Burns

After three or four burns, total fire damage (mortality and

topkill) was high for all species and was often greater than

it was after one burn (table 4). For advance reproduction

that was burned three or four times, a higher proportion of

the damage was due to mortality and less of the damage

was topkill compared to trees that had been burned only

once. Mortality after three or more burns increased notably

in scarlet oak, blackjack oak, flowering dogwood, and

blackgum. Moderate increases in mortality were seen in the

other species. Sassafras showed the greatest tolerance to

being burned repeatedly. For most species, basal diameters

associated with 90 percent or greater survival were substantially higher after three or more burns than they were

after one burn (table 4). For some species, the threshold

diameter varied with tree height or with the number of burns

experienced by the advance reproduction. Sassafras

showed a tremendous ability to tolerate being burned

repeatedly with more than 90 percent of the stems surviving

even for small diameter trees (e.g., 0.1 inches).

For most species, initial basal diameter, initial height, and

number of burns were significantly (p <0.05) related to the

probability of survival one growing season after either one,

three or four dormant season burns. The full logistic model,

which included initial basal diameter and height, their interaction and the number of burns, had strong support for

being the best model (wi

 = 0.99) for blackgum and hickory,

and moderate support (wi ranging from 0.32 to 0.65) for

black oak, flowering dogwood, and white oak. The initial

basal diameter and number of burns model had moderate

support (wi varying from 0.22 to 0.47) for white ash (Fraxinus

americana L.), post oak, chinkapin oak, scarlet oak, and

white oak. For blackjack oak, the initial basal diameter model

(wi = 0.54) and the number of burns model (wi = 0.36) had

the most support in predicting survival of advance reproduction. The survival of blackjack oak advance reproduction

was as low as 62 percent after four consecutive burns and

as high as 87 percent after one burn. The number of burns

model also had moderate support (wi

 = 0.42) for predicting

survival in chinkapin oak, where survival ranged from 98

percent for trees subjected to only one burn to 84 percent

for trees burned as many as four consecutive years. Survival

of sassafras advance reproduction was high enough, even

after four consecutive burns (i.e., 91 percent), that all

models tested were statistically insignificant (p >0.05). For

all species, there was no support (wi

 = 0) for the null hypothesis model (intercept only model). The Hosmer Lemeshow

goodness-of-fit test on the full model showed a good fit of

the model for all species except scarlet oak and hickory.

The probability of survival increased with increasing initial

basal diameter for all oak species (fig. 3) and white ash. In

contrast, survival probabilities declined with increasing

stem diameter in hickory, blackgum and flowering dogwood

species regardless of tree height or number of burns. In

these species, tall trees had higher chances of surviving

than did short trees of the same basal diameter, regardless

of the number of fires. In flowering dogwood, the effect of

height on survival was most pronounced in smaller diameter

trees, whereas the opposite was observed in blackgum and

black oak advance reproduction.

Survival for all species was greatly reduced after three or

four fires (fig. 3). In many cases, survival of advance reproduction was 20 to 30 percent less after four fires than after

one. Differences in survival between trees subjected to one

or four burns were greatest for small diameter trees, but

survival probabilities converged at larger basal diameters

(e.g., 3-inch and larger trees). In general, multiple burns

lowered survival in flowering dogwood and blackgum more

than in most of the oaks, with the exception of scarlet oak

and blackjack oak. Survival in scarlet oak was reduced by

nearly 40 percent for small diameter advance reproduction,

but it improved with increasing basal diameter, though not

to the extent that was seen in other oak species.

Recovery of Height and Understory Woody

Structure

The effect of fire and time since the last fire on the height of

sprouts from advance reproduction that were topkilled was

similar among the species. We compared pre- and postburn height distributions in the single burn and four burn

treatments for oak species combined and for flowering

dogwood, a major competitor of oak reproduction (Dey and

others 1996). Post-burn height distribution of oaks was

substantially different than the initial distribution four growing seasons after a burn (fig. 4). One burn caused densities

of sprouts in the smallest height classes (< 4 feet tall) to

increase above initial levels, and eliminated many of the

taller advance reproduction. The tallest oak sprouts had

only made it into the 10-foot height class in four years since

the burn, approximately 14 feet or more shorter than the

tallest pre-burn stems. This slow recovery in height after

each fire may be due to sprouts growing under a forest

canopy that averaged 79 ft2 per acre (range 38 to 160) and

69 percent stocking (range 36 to 120). Dey and Jensen

(2002) found that overstory densities that averaged 62 ft2

per acre inhibited the height growth of oak stump sprouts.

Further, we found that the tallest oak sprouts were less

than 4 feet one season after four consecutive burns, and

most of the advance reproduction were less than 2 feet tall.

Similar results were seen in flowering dogwood. Waldrop

and Lloyd (1991) also found that fire increased the density

of trees in the smaller size classes by causing shoot dieback and formation of sprout clumps, and by promoting the

establishment of new seedlings in South Carolinian Coastal

Plain forests, where relatively young stands had been subjected to a range of periodic fire treatments over 40 years.

SUMMARY

One dormant season prescribed burn reduced the size distribution of advance reproduction for common hardwood

species found in the Missouri Ozark Highlands. Most stems

of advance reproduction less than six inches in basal

diameter were damaged by fire, usually by shoot dieback

followed by formation of sprout clumps. Mortality of advance

reproduction was generally low in all species after one burn.

We found that the probability of survival was significantly
174

related to size of advance reproduction and that there were

real differences among the species studied. Recovery of

height by the hardwood sprouts is slow under a mature

forest canopy. Thus, one fire can significantly modify the

structure of the woody understory in upland oak forests for

Figure 3—The probability that advance reproduction will be alive one growing season after four

consecutive dormant season burns, two years after three burns, or four years after a dormant season

prescribed fire based on the initial basal diameter, initial height and species. All logistic models shown

were significant (α = 0.05) and had at least moderate support according to the Akaike weight (wi

).

up to four years, but it does little to alter the composition of

the advance reproduction. By virtue of reducing the diameter

and height of advance reproduction, a single prescribed

burn predisposes sprouts to experience more severe

damage and higher rates of mortality from subsequent fires.
175

Three or four consecutive dormant season burns caused

substantially higher mortality to advance reproduction and

consequently greater levels of total fire damage. Mortality

of flowering dogwood and blackgum advance reproduction

increased substantially under a regime of frequent to annual

fire. Mortality of oak and hickory advance reproduction was

also increased to a lesser degree by frequent burning.

Among the oaks, scarlet and blackjack advance reproduction were most vulnerable to repeated burning, whereas

black, post, and white oak were intermediate. Overall,

repeated burning in the dormant season favors oak and

hickory reproduction.

ACKNOWLEDGMENTS

We thank The Nature Conservancy for their cooperation in

this study, for their help in data collection, and for access to

their property. They also funded and implemented the

prescribed burning treatments. The Missouri Department of

Conservation provided funding for field crews to collect data.

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177

INTRODUCTION

Late Holocene forests of southern Illinois were comprised

of oak-hickory and mixed mesophytic forests with inclusions

of glades, prairies, and savannas. Braun (1950) classified

regional forests as Oak-Hickory in the Ozark Hills of southwestern Illinois and Mixed Mesophytic across the Shawnee

Hills of southeastern Illinois and western Kentucky. Küchler

(1964) mapped the potential vegetation of this region as

Oak-Hickory. Much has been published concerning the

ecology of these forests, particularly species-site, productivity, and diversity relationships (Fralish 1988, 1997; Fralish

and others 1991). While edaphic factors affecting vegetation

structure have been explored, few studies have investigated

the role that disturbances, particularly human disturbances,

have had on these forest ecosystems.

Several key natural disturbance regimes have been characterized across the southern Illinois landscape. Primarily,

these include tornado and wind damage, ice storms, periodic

drought, and floods (Parker and Ruffner, in press). These

occur rather sporadically, and the effects of single events

are relatively localized on the landscape. While it is accepted

that these natural disturbances have some impact on forest

composition and structure, it is widely held that long-term

human disturbances, including burning, grazing, and cutting, have been the primary forces shaping the oak-hickory

forests of southern Illinois (Olson 1996, Fralish 1997,

Ruffner and others 2003, Parker and Ruffner, in press).

Oaks have several biological adaptations to fire. Oak stems

have thick, corky bark, a tenacious ability to repeatedly

resprout following top-kill due to a high root:shoot ratio and

dormant buds near the root collar, and the ability to compartmentalize wounds (Abrams 1992, Johnson 1993, Van

Lear and Watt 1993, Smith and Sutherland 1999). In addition, oaks benefit from post-fire site conditions, such as the

open understory and reduced impact of fire-intolerant competitors, and xerification of the site through consumption of

duff and exposure of soil to greater solar radiation, allowing

oak to dominate the advance regeneration pool (Van Lear

and Watt 1993).

Despite the conceptual acceptance of the importance of

anthropogenic disturbances, little fire scar evidence from

the pre-settlement period exists because of the widespread

logging of the primary forests and deterioration of cut

stumps (Robertson and Heikens 1994, Olson 1996, Batek

and others 1999). While pre-settlement fire scar data are

likely lost forever, researchers have compiled substantial

evidence of fire’s role in post-settlement forests of southern

Illinois by using an historical ecology approach including

analysis of vegetation structure (Anderson and others 2000),

witness tree distributions (McArdle 1991), fire scar analysis

(Robertson and Heikens 1994), documentary evidence

(Hall and Ingall 1910, Miller 1920), and land-use history

studies (Ruffner and others 2002, van de Gevel 2002).

Historical accounts depict the region as heavily influenced

by natives (Allen 1945, Temple 1966, Brown 1985). The

landscape encountered by early European settlers reflected

nearly 10,000 years of Native American manipulation and

transformation. Native American use of fire and agricultural

clearing was probably much greater prior to the 1500-1600s

when large epidemics decimated regional native populations. Reduced disturbance regimes allowed an overall

expansion of forest canopy cover. Thus, when European

settlement began in the late 1700s-early 1800s, the anthropogenic landscape resembled a mosaic of oak-hickory

woodlands and forests interspersed with small patches of

barrens, savannas, and glades (Olson 1996, Dey and

Guyette 2000, Parker and Ruffner, in press).

Regional studies reporting historic period fire histories

indicate that fire ignitions were high following European

settlement due to farmers clearing underbrush from the

forest to enhance regeneration of browse and increase

ease of travel and hunting (Hall and Ingall 1910, Miller

1920). The amount of land cleared for agriculture peaked in

OAK ECOSYSTEM RESTORATION AND MAINTENANCE

IN SOUTHERN ILLINOIS

Charles M. Ruffner and John W. Groninger1

1 Assistant Professors, Department of Forestry, Southern Illinois University, Carbondale, IL.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Oak dominance in southern Illinois appears to be a consequence of long-term anthropogenic disturbances,

including burning, grazing, and cutting. The increased prevalence of thin-barked, shade tolerant species, such as sugar

maple and beech on presently oak-dominated upland sites appears to be a result of the extremely low-intensity disturbance regimes of the late 20th century. Our preliminary work indicates that moderate intensity fall burns top-kill 40 percent

of pre-burn sugar maple and beech seedlings [< 2 inches in diameter at breast height (d.b.h.)] and increase herbaceous

cover between 15-25 percent. However, sapling sized stems are largely undamaged suggesting that burning alone will not

effectively restore oak dominance. Thus, a replicated study has been implemented to test the effectiveness of periodic

burning and partial cutting, alone and in combination, to control mesophytic tree species and regenerate upland oak

stands. Vegetation dynamics will be assessed on a long-term basis to document the effects of fire and cutting towards

maintaining oak dominated ecosystems.
178

the early 1900s after which badly eroded lands were abandoned and either planted or naturally regenerated to forest.

Many abandoned farms and cut-over lands were purchased

during the 1920s-30s for public parks and forests and managed as timberlands throughout the 20th century (Parker

and Ruffner, in press). With the development of an effective

fire-suppression campaign in the 1930s-40s, human caused

ignitions dropped, and fire was greatly limited as a force

shaping vegetation.

The virtual elimination of fire from the landscape during the

early 20th century fostered the expansion of mixed mesophytic species across the region (Fralish and others 1991).

Numerous authors have studied central hardwood “oldgrowth” stands typified by the absence of cutting, burning,

and most forms of management over the past several

decades (Weaver and Ashby 1971, Nelson and others 1973,

Schlesinger 1976, Barton and Smeltz 1987, Fralish and

others 1991, Martin 1992, Robertson and Heikens 1994,

Spetich 1995, Fralish 1997, Zaczek and others 2002, Ruffner

and others 2003, and Groninger and others 2003). These

studies report similar and significant shifts in species compositions and forest structure across a spectrum of forested

sites. Overwhelmingly, sugar maple (Acer saccharum) and

American beech (Fagus grandifolia) were found to be

increasing in stand density and basal area at the expense

of the oak and hickory species that dominated the overstory. In particular, still important, but declining overstory

species such as black oak (Quercus velutina) and southern

red oak (Q. falcata) are not represented in younger age

classes. Age-diameter figures suggest that a large cohort of

mixed maple, beech, ash, and black gum (Nyssa sylvatica)

recruited only a few years after the control of understory fire

and the reduction of harvesting in some forests of the Ozark

and Shawnee Hills (van de Gevel and Ruffner 2002, Zaczek

and others 2002).

The presence of an understory dominated by mesophytic tree

species has been associated with poor oak seedling and

sapling development (Loftis 1990, Lorimer and others 1994).

However, removal of the mesophytic midstory has aided in

the development of the advance regeneration needed for

the perpetuation of upland oak ecosystems (Crow 1988,

Johnson 1993). Despite this, operational methodologies to

remove dense midstories are costly and of uncertain reliability (Miller 1984, Horsley 1990, Groninger and others 1998).

The composition of the understory and midstory may play

an especially important role in the development of the next

overstory in many southern Illinois stands where overstory

dominants such as black oak and southern red oak are

approaching their maximum ages en masse.

Recent studies have conducted prescribed burns in several

transitional forests across southern Illinois with mixed

success (Ruffner 2001, Ruffner and others 2003, Ruffner

and Davis 2002). Understory prescribed burns have been

effective in top-killing seedlings of these mixed mesophytic

species with little or no effect on sapling-sized stems, unless

subjected to multiple burns. Further, these burns have been

ineffective for promoting oak regeneration in these stands.

From these initial results we posit that understory burning is

not effective in top-killing the larger unwanted stems that

are shading the understory and precluding the development

of oak and hickory advanced regeneration. Thus, we have

developed an experiment to test the effects of three silvicultural treatments on controlling unwanted species and inducing oak-hickory recruitment. Recent burning activities will

be discussed in this paper and the current experimental

design and possible implications for oak ecosystem maintenance will be explained.

PHYSICAL AND HISTORICAL CONTEXT OF STUDY

AREA

The current project focuses on upland forests of the Ozark

Hills of southwestern Illinois and the Shawnee Hills of

southern Illinois.

Ozark Hills

The Ozark Hills region (113,340 acres) in southwestern

Illinois is characterized by mature dissected topography

capped with loess deposits and underlain with cherty limestone (Fralish 1997). Ridgetop sites are relatively narrow

spur ridges capped with loess above steep sideslopes of

colluvial materials, which descend to narrow riparian zones

comprised of alluvial soils. Pre-European settlement forests

were dominated by oak-hickory species with increased numbers of American beech, sugar maple, and tulip-poplar (Liriodendron tulipifera) across more mesic sites (McArdle 1991).

McArdle argued that these forests developed under a moderate to infrequent disturbance regime based on the fact

that oak-hickory importance increased after European settlement in response to the more intense disturbance regime of

logging, clearing for agriculture lands, and increased grazing

and burning. Indeed, much of the region’s forests were extensively logged between 1880-1920 and frequent fire was

identified as a major problem for forest development in the

1920s (Miller 1920, Miller and Fuller 1922, Fralish 1997).

Fires continued through the 1940s until much of the Ozark

Hills were purchased by the USDA Forest Service in the late

1930s and effective fire control measures were implemented.

Shawnee Hills

The Shawnee Hills comprise a 950,495 acre, unglaciated

east-west escarpment bisecting southern Illinois (Fralish

1997). Topography of this section is characterized by broad

ridgetops bearing deep loess deposits dissected by moderately steep sideslopes opening onto broad flat valleys

(Fenneman 1938). Pre-European settlement forests of this

region were dominated by xerophytic species such as post

oak (Quercus stellata), black oak, and white oak (Q. alba),

with mesophytic species tulip-poplar (Liriodendron tulipifera), American beech and sugar maple having lower

importance across most sites (Fralish 1997).

Stands disturbed during the early 20th century from harvesting, fire or grazing are 58-84 percent similar to pre-settlement oak hickory forests suggesting compositionally stable

forests (Harty 1978, Fralish 1997). However, the reduction

of harvesting on public land and the eventual near removal of

fire from the landscape during the last century has caused

a shift in importance values particularly across northern

aspects and low slope positions (Fralish 1997). Reduced

disturbance patterns have resulted in a distinct increase in

sugar maple and American beech recruitment into the midstory and understory positions (Schlesinger 1976, Fralish
179

1997, Ruffner and others 2003). Still other midstory species

such as winged elm (Ulmus alata), hophornbeam (Ustrya

virginiana), and dogwood (Cornus spp.) appear capable of

limiting oak recruitment on many sites.

Current management objectives of Illinois Department of

Natural Resource agencies across this region focus on

increasing oak-hickory advance regeneration while reducing mesophyte stem density with experimental prescribed

burns coupled with timber stand improvement cuttings

(Allen 2001, Ruffner and Davis 2002). Justification for this

rests on the assertion that anthropogenic disturbances

(either Native American or Euro-American) have been the

driving force influencing forest structure and function across

this region for at least the last four hundred years (Fralish

1997, Parker and Ruffner, in press).

PRESCRIBED FIRE TREATMENTS

Prescribed fire has been widely used to reduce competing

vegetation, slow successional transition, reduce pest and

pathogen populations, enhance wildlife habitat, facilitate

site preparation, and encourage recruitment of resprouting

species (Mutch 1994). Many authors have called for the reintroduction of prescribed burning in oak forests of the east,

but few have documented the efficacy of this practice (Van

Lear and Watt 1993, Brose and others 2001).

Perhaps the most successful experiments to date include

those in oak forests of the Piedmont region of Virginia

(Keyser and others 1996, Brose and Van Lear 1998, Brose

and others 1999). Following shelterwood harvests with a 50

percent basal area reduction, these authors conducted

repeated prescribed burns to significantly reduce tulip-poplar regeneration and increase advance oak regeneration.

They suggest that this harvest/fire disturbance regime

closely mimics the conditions that fostered the development

of these oak dominated systems (Brose and others 1999).

In addition, they report that allowing several years to lapse

between the initial cut and burning is critical. This waiting

period allows for several key components including the

establishment and growth of vigorous oak seedlings and

regeneration of the buried tulip-poplar seed pool. Although

burns were also conducted in the winter and summer, spring

appeared to be the best time period for burning because it

presented the most favorable weather conditions such as

warm temperatures, lower humidities, and sunny days

(Brose and others 1999).

Within forests of southern Illinois, land managers have been

utilizing prescribed fire since the mid 1980s. While the US

Forest Service fire management program has largely been

forced into a “suppression” mode due to extensive litigation,

several Illinois Department of Natural Resources Divisions

actively manage vegetation with prescribed fire (Ruffner

2001). The Divisions of Forest Resources and Natural

Heritage both use fire to maintain unique vegetation and

habitat types in glade and oak savannas, improve wildlife

habitat, and foster oak regeneration while reducing competing mesophytic species in forestlands (Ruffner 2001).

The effect of a fall prescribed burn in an oak-hickory forest

stand was investigated using two 0.10 ha permanent plots

at Ozark Hills Nature Preserve, Trail of Tears State Forest.

Despite the low-to-moderate intensity of the burn caused by

fall weather conditions, the burn effectively met the primary

objectives of reducing understory competition from mesophytic tree species and increasing diversity of herbaceous

species. Analysis of pre- and post-burn data indicates that

nearly 40 percent of understory sugar maple and American

beech seedlings were top-killed and herbaceous cover

increased 15-25 percent within the plots. While these

numbers indicate reduction of unwanted seedlings, sapling

sized stems were left untouched by this level of burning.

Thus, a replicated study similar to those conducted by Brose

and his associates was designed to test the effectiveness

of periodic burning and partial cutting of midstory, mesophytic trees on the development of oak-hickory regeneration.

This newest project evaluates and demonstrates the use of

prescribed fire and partial cutting, alone and in combination

with one another, on restoring oak forest health and sustainability. All study sites are in upland forest stands in

southern Illinois with an oak-hickory dominated overstory

and a midstory consisting of shade tolerant tree species.

Site index ranges between 50-80 for upland oaks. Stand

basal area averaged 110.1 ft2 per acre (+ 4.5 SE) with an

average stem density of 226.2 (+ 26.7 SE) trees per acre.

A total of five, four acre blocks (each comprising a burned

only plot, a cut only plot, a burned and cut plot, and an

unmanaged control) have been installed across southern

Illinois. Block compartments have 30-50 percent of standing

basal area reduced by cutting stems <12 inches in d.b.h.,

favoring healthy oak-hickory stems for the residual stand.

Burn compartments will be treated three times in five years

beginning spring (2003) with a typical fuel model 9 prescription aimed at top-killing mesophytic resprouts and generating

an advanced regeneration pool of oak-hickory stems. At

each site, permanent plots have been installed to permit

repeated measurement of the following variables:

• growth and fire damage for trees larger than 4 inches in

d.b.h.

• tree species regeneration, shrub species, and tree

saplings up to 4 inches in d.b.h.

• herbaceous species composition, cover, and quality for

wildlife.

CONCLUSION

Perpetuation of oak dominated uplands is a priority among

a wide range of constituencies in southern Illinois. Managers addressing this problem are faced with an incomplete

understanding of past processes that produced the presently

dominant oak overstory. Specific questions concern the timing, frequency, and intensity of anthropogenic and natural

fires and the potential impacts of native and agricultural

animals in stand establishment and maintenance. Equally

puzzling is the extent to which overstory and midstory

mesophytes must be controlled in order to carry a cohort of

oak and hickory from seedling to overstory status. Also,

with the prolonged absence of fire, some mesophytes have

developed to the extent that they are now overstory trees.

Removal of these now fire resistant individuals through

cutting may be necessary to meet ecosystem restoration

goals, but is inconsistent with esthetic expectations for

public lands. Retention of these trees might necessitate
180

implementation of prescribed fires of greater than historic

intensity and or frequency. These hotter fires may negatively impact the quality and value of maturing timber and

thereby alienate some landowners with economic incentives for forest management. Alternatively, retaining large

mesophytes may preclude adequate fuel development and

result in the failure to secure oak and hickory recruitment.

In the face of these uncertainties, the establishment of

demonstration plots such as those described here could

serve as a focal point to help interested parties in southern

Illinois determine where oak ecosystem restoration is desirable and how it may be effectively implemented. This empirical approach may also help address historical questions

which often serve as a justification for ecosystem maintenance and restoration. A network of similar installations

across fire-influenced oak dominated portions of North

America may serve to increase public understanding of the

fundamental roles played by humans and fire in the widespread occurrence of these ecosystems.

ACKNOWLEDGMENTS

The authors wish to thank James Zaczek and David Allen

for their constructive reviews of the manuscript and to the

members of the Saluki Fire Dawgs fire management crew

for data sampling and burn implementation. This research

is supported through grants from the McIntire-Stennis

Cooperative Forestry Program and the Wild Turkey

Federation.

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182

INTRODUCTION

Regenerating northern red oak (Quercus rubra L.) on highquality growing sites is a continuing problem in the central

Appalachian region. New stands that develop after harvests

often contain fewer oak stems than the preceding stand,

and the proportion of oak in the new stand usually does not

meet management objectives. The basic problem is that

harvests are often applied when there is a lack of competitive advanced oak seedlings present, thus the probability of

successful oak regeneration is relatively low.

Competition among various species on a given site determines future species composition. After a significant disturbance to the forest canopy, numerous woody and herbaceous

species compete for the light, water, and nutrients freed by

the removal of overstory trees. The sources of new woody

regeneration include: (1) new seedlings from seed stored in

the forest floor, (2) sprouts from cut stumps, wounded roots,

and broken shoots, and (3) advanced seedlings that developed before the disturbance. Species that compete with

oaks on mesic sites often exhibit faster initial height growth

than new oak seedlings and small advanced oak seedlings.

If the oaks are not able to keep pace with competing species

in the early stages of development, they usually die as the

new overstory canopy closes above them (Trimble 1973).

Oak stump sprouts are usually competitive with other

species, but they contribute relatively few new stems on

mesic sites (Loftis 1983a, Sander 1988). As a result, the

primary source of successful oak reproduction on mesic

sites comes from relatively large advanced oak seedlings.

If large advanced oak seedlings are lacking before the

harvest, then competing species usually dominate the

composition of new stands (Beck and Hooper 1986).

Successful oak regeneration is related to the size and

number of advanced seedlings present when harvests occur

(Sander and others 1984, Loftis 1990a). For example, on

northern red oak site index 80 (base age 50 years), the

probability that an advanced oak seedling with a 0.1-inch

basal diameter will become dominant or codominant 20

years after a harvest is essentially zero (Loftis 1990a).

Even if thousands of such small seedlings are present

before a harvest, very few will compete successfully after

the harvest due to their small initial size. This probability

increases to 1 percent for a 0.2-inch basal diameter, and

8 percent for a 0.75-inch basal diameter. As the seedling

size and probability of success increase, fewer seedlings

are needed to obtain adequate regeneration after a harvest.

A pre-harvest inventory of advanced oak seedlings is

recommended to determine if there will be a sufficient oak

component in the new stand (Loftis 1990a). If projected oak

regeneration is insufficient, silvicultural treatments may be

needed to increase the growth and survival of advanced

seedlings before the overstory is removed (Loftis 1990b).

In undisturbed mature oak stands, advanced oak seedlings

usually exhibit both poor survival and slow growth. In one

study, the survival of a cohort of northern red oak seedlings

that germinated after a good acorn crop steadily declined

from 60 percent after 1 year to only 10 percent after 10 years

(Beck 1970). Similarly, the average total height of survivors

was less than 1 foot after 1 year and generally did not

increase over the next 10 years. In the southern Appalachians, shelterwood treatments that removed more than 50

percent of the stand basal area stimulated the growth of

advanced oak seedlings, but also stimulated the development of competing species such as sweet birch (Betula

lenta L.) and yellow-poplar (Liriodendron tulipifera L.),

particularly where canopy gaps were created (Loftis

EFFECT OF PRE-HARVEST SHADE CONTROL AND FENCING ON

NORTHERN RED OAK SEEDLING DEVELOPMENT IN

THE CENTRAL APPALACHIANS

Gary W. Miller, James N. Kochenderfer, and Kurt W. Gottschalk1

1 Research Forester, USDA Forest Service, Northeastern Station, Morgantown, WV 26505; Research Forester, USDA Forest Service,

Northeastern Station, Parsons, WV 26287; and Research Forester and Project Leader, USDA Forest Service, Northeastern Station,

Morgantown, WV 26505, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Successful oak regeneration is related to the size and number of advanced seedlings present when harvests

occur. This study was installed to quantify the effect of microsite light availability and deer on the development of advanced

northern red oak (Quercus rubra L.) reproduction in mesic Appalachian hardwood stands. Microsite light was manipulated

with pre-harvest herbicide treatments. Twelve 0.4-acre plots were randomly assigned to each of three microsite light

levels and an untreated control for a total of 48 plots. A woven wire fence was erected around 8 plots in each treatment.

Approximately 1,500 individual seedlings were tagged for long-term study. An additional 200 seedlings were tagged for

annual destructive tests to measure shoot and root development. Three years after treatment, survival averaged 74 percent

in fenced/high-light plots compared to 22 percent in unfenced/untreated plots. Fencing had a much stronger influence on

survival than microsite light. Treatments also increased shoot length by 30 percent, root length by 39 percent, shoot

weight by 145 percent, root weight by 337 percent, and basal diameter by 26 percent compared to controls. Practical

considerations and long-term implications are discussed.
183

1983a). Alternative shelterwood treatments that removed

only 30 percent of stand basal area from below, with no

canopy gaps, increased survival and growth of advanced

oak seedlings without stimulating the development of

competing species (Loftis 1988). Similar treatments have

not been tested in the central Appalachians.

In most central Appalachian hardwood stands, adequate

advanced oak reproduction does not develop due to several

factors: (1) predation of acorns by deer, insects, rodents,

and birds, (2) browsing of seedlings and sprouts by deer,

and (3) excessive competition from dense interfering vegetation in the midstory and understory strata. These conditions call for pre-harvest silvicultural treatments that reduce

acorn predation, reduce deer browsing of established seedlings, and reduce interfering plants so that advanced oak

seedlings can grow to sufficient sizes before overstory

removal (Lorimer 1993, Marquis 1981, Marquis and others

1976, Tilghman 1989).

Preparing for successful regeneration requires proper management of stand structure in the overstory, midstory, and

understory for many years before a harvest (Carvell and

Tryon 1961, Sander and Clark 1971, Gottschalk 1983, Beck

1988, Leak and others 1987, Loftis 1990b, Hannah 1987,

Marquis and others 1992). Forest managers in the central

Appalachian region need a reliable and efficient treatment

for developing adequate advanced oak reproduction before

harvest operations. Preliminary results in the region indicate that advanced oak reproduction is more abundant in

stands where the canopy is closed and the subcanopy

density is reduced (Schuler and Miller 1995, Miller 1997).

A key to preparing for successful reproduction is a clearer

understanding of the relationship between subcanopy stand

density and the survival, growth, and development of oak

seedlings and their competitors. This study was installed to

quantify the effect of microsite light availability and deer on

the development of advanced oak reproduction in mesic

Appalachian hardwood stands.

STUDY SITES

The study was installed in 80-year-old second-growth

central Appalachian hardwood stands on the Monongahela

National Forest in northern Randolph County, West Virginia.

Overstory trees in the study area regenerated after landscape-scale logging operations that were conducted between

1915 and 1920. In 1998, northern red oak accounted for 59

percent of the basal area, while yellow-poplar, black cherry

(Prunus serotina Ehrh.), American beech (Fagus grandifolia

Ehrh.), red maple (Acer rubrum L.), sugar maple (Acer

saccharum Marsh.), and cucumbertree (Magnolia acuminata

L.) also occupied significant proportions of the overstory.

Annual precipitation in the study area averages 59 inches

and is evenly distributed throughout the year. Soils are

described as Dekalb channery loam (loamy-skeletal, mixed,

mesic Typic Dystrochrept) (USDA Soil Conservation Service

1967). The study area is located on site index 80 for northern

red oak (base age 50). Several layers of dense subcanopy

vegetation were present before treatments were applied.

This vegetation included striped maple (Acer pensylvanicum

L.), American beech, red maple, and sugar maple. There

were approximately 20 to 25 white-tailed deer (Odocoileus

virginianus) per square mile in the study area. The stands

contained an average of 5,000 2-year-old advanced northern red oak seedlings per acre when the study was installed.

METHODS

Microsite light on the forest floor was manipulated by treating selected subcanopy stems with an approved herbicide.

A 50 percent solution of glyphosate as Accord 41.5 percent

SL in a water carrier was used in all herbicide applications.

The treatments included three microsite light levels plus a

control defined as follows:

Control—no stems were treated

Low—all stems greater than 2.0 feet tall and less than or

equal to 2.0 inches in diameter at breast height (d.b.h.)

were cut near the ground, and the surfaces of cut stumps

immediately were wetted with herbicide solution

Medium—in addition to stems included in the Low treatment, all stems greater than 2.0 inches and less than or

equal to 7.0 inches in d.b.h. were injected

High—in addition to stems included in the Low and

Medium treatments, all remaining stems that were in the

intermediate or suppressed crown classes were injected.

The hack-and-squirt method was used to inject herbicide

into target stems in the Medium and High treatments. A

hatchet with a 1.75-inch wide blade was used to make the

incisions, and incisions were spaced 1.5 inches apart on

each target tree. A squirt bottle was used to dispense about

1.5 ml of herbicide into each incision.

In all three herbicide treatments, oak stems were neither

cut nor injected in order to retain them as possible sources

of advanced reproduction or sprouts.

Each treatment was applied to 12 square plots, resulting in

a total of 48 plots, and each plot was 0.4-acre in size. A 6.5-

feet tall woven wire deer fence was erected around 8 plots

in each of the treatments, for a total of 32 fenced plots. A

square 0.1-acre measurement plot was centered within

each treatment plot, thus providing a buffer around each

measurement plot, and all data were collected within the

measurement plots. The fences were erected in July 1998,

and the herbicide treatments were applied in late July 1999.

Species, d.b.h., and crown class were recorded for all stems

greater than or equal to 1.0-inch d.b.h. before treatment

within the 0.1-acre measurement plots. A post-treatment

inventory was completed a year later to determine the

percent reduction in basal area achieved in each plot.

Photosynthetically active radiation (PAR) was measured

within each plot in late July before treatment and each year

after treatment to quantify changes in microsite light. PAR

was measured with synchronized Accupar Ceptometers

placed 1 meter above the ground at a fixed location in a

nearby open field and at 9 designated points within each

plot. Measurements in the open were compared to mean

measurements within the plots at synchronized times to

determine percent PAR associated with each plot (Parent

and Messier 1996, Gendron and others 1998).

Approximately 1,500 individual oak seedlings were tagged

for long-term study. Survival and total height of live seed-
184

lings were recorded in late summer before treatment and

each year after treatment.

An additional 50 seedlings in each treatment were tagged

within fenced plots to perform annual destructive tests to

measure root and shoot response to each microsite light

level. All seedlings tagged for the destructive tests germinated in the spring of 2000. Approximately 10 seedlings

were extracted from each treatment in September of 2000,

2001, and 2002, thus providing growth response data for

each of the first three growing seasons. Measurements

taken on extracted seedlings included shoot length, root

length, dry shoot weight, dry root weight, and basal

diameter.

DATA ANALYSIS

Statistical analyses were completed to provide insight into

four important relationships: (1) the effect of herbicide treatments on microsite light, (2) the effect of herbicide treatments

and fencing on survival and height of tagged red oak seedlings, (3) the effect of herbicide treatments on third-year

shoot and root characteristics of extracted seedlings, and

(4) the effect of herbicide treatments on basal diameter of

extracted seedlings over 3 growing seasons.

A one-factor repeated measures ANOVA was used to examine the effect of herbicide treatments on microsite light.The

fixed effect model has the form:

ij i j ij ( )ij

Y =+ + + + μ α β αβ ε

where

Y = percent PAR

μ = the overall mean

α = the effect of herbicide treatment

β = the effect of time

ε = the random error.

A two-factor repeated measures ANOVA was used to

analyze the effect of the herbicide treatments (Factor 1)

and fencing (Factor 2) on seedling survival and height. The

fixed effect model has the form:

ij i j k ijk ijk ( )()() ( ) ij ik jk Y =+ + + + + + + + μ α β θ αβ αθ βθ αβθ ε

where

Y = survival proportion or height

μ = the overall mean

α = the effect of herbicide treatment

β = the effect of fencing

θ = the effect of time

ε = the random error.

The remaining terms represent the interaction of factors in

the full model.

For third-year shoot and root response, data were analyzed

using a one-factor ANOVA. The fixed effect model has the

form:

Yi ii =+ + μα ε

where

Y = shoot length, root length, shoot dry weight, or root dry

weight

μ = the overall mean

α = the effect of herbicide treatment

ε =the random error.

For seedling basal diameter, means were compared for each

of the first three growing seasons after treatment. Basal

diameter data were collected from the same seedlings used

to compare shoot and root development. It was not possible

to conduct a repeated measures analysis of basal diameter

since the subjects were destroyed each year. Instead, the

data were analyzed as a two-factor ANOVA and the fixed

effect model used has the form:

ij i j ij ( )ij

Y =+ + + + μ α β αβ ε

where

Y = basal diameter

μ = the overall mean

α = the effect of herbicide treatment

β = the effect of time

ε = the random error.

The general linear models procedure in SAS was used for

all statistical analyses (SAS Institute Inc. 1998). The TukeyKramer HSD mean separation test was used for all multiple

comparisons. Treatment effects were considered to be

statistically significant when P <0.05. For each analysis, the

residuals were tested for normality using the Shapiro-Wilk

test and for homogeneity of variance using the Levene test.

RESULTS AND DISCUSSION

The average basal area on all study plots was 180 ft2 per

acre before treatment. The herbicide treatments reduced

basal area by an average of 22, 10, and 2 percent for the

High, Medium, and Low treatments, respectively (table 1).

Loftis (1990a) recommended reducing basal area by 30 to

35 percent when applying similar pre-harvest shelterwood

treatments in stands on site index 80 in the southern Appalachians. The basal area reduction in this study ranged

from 1 to 35 percent, thus all treatment levels were equal to

or less than those recommended for stands in the southern

Appalachians (table 1).

Microsite Light

Before treatment, the low levels of microsite light beneath

the dense subcanopy vegetation were not conducive to oak

seedling survival and growth. The average PAR was 1.9 percent before treatment, and none of the plots was receiving

the minimum amount of light needed for oak seedling survival. When seedlings do not receive enough light, as is
185

common in stands with a dense subcanopy layer, photosynthesis produces less carbohydrates than are used in

respiration, thus the seedlings eventually die (Hodges and

Gardiner 1993). Hansen and others (1987) found that small

northern red oak seedlings need PAR ≥ 30 μmol m-2s-1 to

achieve the necessary positive carbon balance. All measures of PAR in untreated plots were below this threshold

level. It was clear that low microsite light levels on the

forest floor had prevented the development of any large

advanced oak seedlings for many years.

One year later, the herbicide treatments resulted in a significant increase in microsite light reaching the forest floor (fig.

1). The High, Medium, and Low treatments increased microsite light to 12, 8, and 4 percent PAR, respectively. The

repeated measures ANOVA indicated a significant effect of

treatment (P <0.01), time (P <0.01), and the interaction of

treatment and time (P <0.01). The differences among the

treatments were still intact after the third growing season,

although the subtle changes in microsite light that occurred

each year appear to differ by treatment. By the end of the

third year, slight reductions in microsite light were evident in

the High and Medium treatments, probably due to crown

expansion among overstory trees into small canopy gaps.

Microsite light in the Low and Control treatments remained

relatively stable for the first three growing seasons. As this

study continues, more information about the longevity of

treatment effects on microsite light will become available.

Seedling Survival and Height

This comparison of survival and height included all 1,076

tagged seedlings that were still alive after 3 years. The

repeated measures ANOVA with two factors indicated that

time (P <0.01), microsite light (P = 0.02), and fencing (P

<0.01) had a significant effect on the 3-year survival of oak

seedlings. There was no evidence of interaction between

microsite light and fencing (P = 0.78). At each level of

microsite light, fencing increased survival by more than 20

percent (fig. 2). Note that survival was 22 percent in

untreated plots, and the addition of a fence increased

survival to 44 percent. Also, in fenced plots, each increase

in microsite light further increased survival by 10 percent.

For example, the Low treatment increased survival to 54 percent, the Medium treatment increased survival to 64 percent,

and the High treatment resulted in maximum survival of 74

percent (fig, 2). Repeated measures ANOVA are robust to

violations of multivariate normality and homogeneity of

covariance matrices, thus applying the arcsine square root

transformation to the observed survival proportions yielded

similar results. A similar repeated measures ANOVA for

seedling height indicated that time (P <0.01) and fencing (P

<0.01) significantly affected seedling height, but height did

not differ significantly by microsite light treatment (P = 0.46).

Seedling height in fenced plots averaged 4.7 inches, while

those in unfenced plots averaged 3.5 inches after 3 years.

Shoot and Root Response After 3 Years

This comparison is based on a relatively small sample,

approximately 10 seedlings per treatment, extracted from

fenced plots for laboratory analysis of shoot and root development. Shoot length, root length, shoot weight, and root

Table 1—Summary of shade control treatments and effects on basal area

and microsite light availability

Reduction in Residual

Treatment Plots Stems treated basal area stand PAR

 no. no./ac - - - - - - - - - - percent - - - - - - - - - -

Mean Range Mean Range Mean Range

Control 12 — — — — 2 1 – 3

Low 12 209 70 – 450 2 1 – 13 4 3 – 8

Medium 12 360 180 – 600 10 3 – 25 8 4 – 16

High 12 410 270 – 640 22 16 – 35 12 8 – 25

PAR = photosynthetically active radiation.

Figure 1—Mean percent of photosynthetically active radiation

before and 3 years after shade control treatments, with one

standard error bar shown above each mean.

14

12

10

8

6

4

2

0

High Medium Low Control

Treatment

Pretreatment

1st year

2nd year

3rd year

Percent

Photosynthetically active radiation
186

weight were significantly related to microsite light resulting

from the herbicide treatments. In addition, the analysis of

residuals exhibited no evidence to reject assumptions of

normality or homogeneity of variance in any of the comparisons. Multiple comparisons of treatment means following

each ANOVA showed that significant root responses

occurred at lower microsite levels than that observed for

shoot responses. Shoot length in the High treatment was

significantly greater than in other treatments, while shoot

length among the Medium, Low, and Control treatments

was not significantly different. Shoot length averaged over

10 inches in the High treatment compared to less than 8

inches in the other treatments (fig. 3). By contrast, root

length in both the High and Medium treatments was significantly greater than that observed in the Control treatment.

Root length averaged over 10 inches in the High and

Medium treatments compared to less than 8 inches in the

Low and Control treatments (fig. 3). The High treatment

increased shoot length and root length by 30 and 39 percent, respectively, compared to controls. Shoot weight in

the High treatment was significantly greater than in other

treatments, and shoot weight among the Medium, Low, and

Control treatments was not significantly different. Average

shoot weight in the High treatment was 145 percent greater

than that observed in control plots (fig. 4). Root weight in

the High and Medium treatments was significantly greater

than in the Control treatment. Average root weight in the

High treatment was 337 percent greater than that observed

in the control plots (fig. 4).

Seedling Basal Diameter

Both time (P <0.01) and microsite light treatment (P <0.01)

were significantly related to seedling basal diameter,

although there was no evidence of interaction between time

and treatment (P = 0.67). The residuals were consistent

with normality and homogeneity of variance assumptions.

The High treatment led to an increase in basal diameter

each of the first three growing seasons, with the greatest

increase occurring in the third growing season (fig. 5). After

three growing seasons, the Medium and Low treatments

Figure 2—Mean survival of advanced northern red oak seedlings 3

years after shade control treatments and fencing, with one

standard error bar shown above each mean.

Figure 3—Mean shoot and root length of seedlings extracted 3

years after treatments, with one standard error bar shown above

each mean. For each variable, means with the same letter are not

significantly different based on Tukey-Kramer HSD multiple

comparison test at the 0.05 level.

Figure 4—Mean shoot and root dry weight of seedlings extracted 3

years after treatments, with one standard error bar shown above

each mean. For each variable, means with the same letter are not

significantly different based on Tukey-Kramer HSD multiple

comparison test at the 0.05 level.

100

80

60

40

20

0

High Medium Low Control

Fenced

Unfenced

Percent

Treatment

Third-year survival

14

12

10

8

6

4

2

0

High Medium Low Control

Treatment

Inches

Shoot

Root

Third-year shoot and root length

a a a

a

b b

b

b b

3.0

2.5

2.0

1.5

1.0

0.5

0.0

High Medium Low Control

Treatment

Grams

Third-year shoot and root weight

Shoot

Root

a

a

a

a

b b

b

b

b
187

did not produce significant increases in basal diameter

compared to controls. Basal diameter in the High treatment

averaged 0.146 inches, approximately 26 percent greater

than that observed in the controls.

In general, the data indicated that enhanced root development occurred in the High and Medium treatments, with

some evidence of faster stem development in the High

treatment (figs. 3 and 4). Oak seedlings typically exhibit a

conservative growth strategy in which surplus photosynthate resources are allocated to root development before

notable shoot development occurs (Hodges and Gardiner

1993). Apparently the Medium treatment resulted in enough

photosynthate to enhance root development within 3 years

after treatment, but increases in shoot development may

not be evident for a few more years.

Practical Implications

An example is presented in table 2 to illustrate the practical

implications of the results presented here. The example is

based on 20-year dominance probabilities for red oak seedlings presented by Loftis (1990b). This approach predicts

the number of dominant/codominant (D/C) stems 20 years

after overstory removal based on the number and size of

seedlings present when the overstory is removed. The

number of D/C stems projected to develop in the new stand

Figure 5—Mean basal diameter of seedlings extracted 1, 2, and 3

years after treatments, with one standard error bar shown above

each mean.

Table 2—Predicted number of dominant/codominant oak stems in the new stand based on

the size and number of advanced oak seedlings present when harvest occurs

Time between

treatment and Pre-harvest Dominancea Survival Pre-harvest D/C stems

harvest basal diameter probability rate oak seedlings 20-yr after harvest

year inches - - - - - percent - - - - - - - - - - - number per acre - - - - - -

 Predicted outcome with high shade control and fencing

0 0.089 0.0 100.0 5000 0

1 0.113 0.0 88.2 4410 0

2 0.128 0.6 83.5 4175 25

3 0.146 0.7 73.5 3675 26

4 0.167 0.8 68.0 3400 27

5 0.191 0.9 63.0 3150 28

6 0.218 1.2 58.0 2900 32

7 0.248 1.4 53.0 2650 37

8 0.281 1.7 48.0 2400 41

9 0.317 2.1 44.0 2200 46

10 0.356 2.5 40.0 2000 50

11 0.398 3.1 36.0 1800 56

12 0.443 3.7 32.0 1600 59

 Predicted outcome with no shade control and no fencing

0 0.089 0.0 100.0 5000 0

1 0.089 0.0 69.6 3480 0

2 0.089 0.0 41.2 2060 0

3 0.116 0.0 21.8 1090 0

4 0.120 0.5 11.0 550 3

5 0.124 0.5 6.0 300 1

6 — — 0.0 0 0

D/C = dominant/codominant.

a Loftis 1990a.

0.20

0.15

0.10

0.05

0.00

High Medium Low Control

Treatment

Inches

Basal diameter

1st year

2nd year

3rd year
188

is found by multiplying the dominance probability for a given

seedling size by the number of such seedlings present.

Note that the dominance probability increases as seedling

size increases because larger advanced seedlings can

compete more successfully against other species as the

new stand develops.

The example compares two silvicultural alternatives. One

alternative includes fencing and shade control as applied in

the High treatment. The other alternative includes no

fencing and no shade control. Computations for the first

three years are based on actual survival rates and average

basal diameters observed in the High and Control treatments. Computations beyond the third year were estimated

as a linear projection of basal diameter growth and a

negative exponential projection of survival based on the

observed 3-year trends in each of the two silvicultural

alternatives.

With shade control and fencing—The treatments increased

the projected number of successful D/C oaks within 3 years,

and continued increases are expected for several years into

the future. After 3 years, the survival rate was 73.5 percent

and the average basal diameter was 0.146 inches (table 2).

Applying the corresponding dominance probability indicates

that 0.7 percent of the surviving 3675 seedlings, or 26 stems

per acre, would become D/C in the new stand if the overstory were removed after the third year. Postponing overstory removal for several additional years would allow

advanced seedlings to grow larger, thus introducing a greater

dominance probability and a greater projected number of

successful D/C oaks in the next stand. However, natural

mortality will also reduce the number of seedlings each

year. Projections of both decreasing survival and increasing

growth indicate that the projected number of successful D/C

oaks generally increases for at least 10 years after preharvest treatments were applied. If treatments are applied

8 to 10 years before removing the overstory, projections

indicate that the new stand will contain 40 to 50 D/C oaks

per acre when the new stand is 20 years old.

With no shade control and no fencing—In the absence of

pre-harvest treatments, the projected number of successful

D/C oaks remained near zero, and no improvement is

expected in the future. After 3 years, the survival rate was

only 21.8 percent, and the average basal diameter was

0.116 inches (table 2). These trends suggest that few seedlings will remain after 5 years, and those that survive have

little chance of becoming dominant or codominant after the

overstory is removed. Even if the overstory had been

removed immediately, when there were 5,000 seedlings per

acre, the dominance probabilities indicate that none would

compete successfully after the harvest because of their

small initial size.

For simplicity, this example was based on applying the

appropriate dominance probability to a single size class,

the mean basal diameter observed in each alternative. In

real-world applications, a population of advanced oak

seedlings often exhibits a distribution of size classes and

each size class has a corresponding dominance probability.

It is more accurate to estimate the projected number of

successful D/C oaks by applying dominance probabilities to

the number of advanced seedlings in each size class and

summing the results (Loftis 1993).

SUMMARY

The example illustrates three important results of this study.

First, pre-harvest shade control and fencing increased

survival and stimulated faster shoot and root growth.

Successful oak regeneration is related to the size and

number of advance seedlings present before a harvest,

thus the treatments tested in this study increased the probability of successful oak regeneration. In the absence of preharvest treatments, especially fencing, the probability of

successful oak regeneration remained near zero. Second,

significant shoot and root development occurred in the first

3 years, but more time is needed to allow seedlings to fully

respond to the treatment. As the seedlings develop larger

basal diameters, their corresponding dominance probability

will also increase. Data from this study indicated that treatments should be applied at least 8 to 10 years before a

planned harvest to assure that seedlings attain at least a 2

to 3 percent probability of becoming dominant or codominant once the overstory is removed. Third, annual measurements of PAR showed only slight decreases in microsite

light each year, indicating that observed survival and

growth rates will continue for several years. In the High

treatment, it is expected that enhanced microsite light will

be available for 10 to 12 years after treatment. This

extended response period provides a practical window of

opportunity for scheduling future activities such as commercial shelterwoods and/or removal of the overstory once

competitive advanced oak seedlings develop.

Periodic control of undesirable vegetation can be a valuable long-term practice in forest management. Zedaker

(1986) reasoned that applying herbicide treatments at

opportune times in the life cycle of hardwood stands is an

effective means of allocating site resources to desirable

species. In this case, pre-harvest shade control treatments

allow advanced northern oak seedlings to acquire the site

resources necessary to become competitive with other

species and enhance the probability of successful oak

regeneration. Oaks are notorious for slow height growth in

the early stages of development (Hodges and Gardiner

1993). Small seedlings need at least 8 to 10 years of

desirable growing conditions before overstory removal to

develop into competitive advanced seedlings. Pre-harvest

herbicide treatments provide such conditions, in that interfering plants are eliminated quickly and they do not become

reestablished for many years. Forest managers should

consider maintaining relatively low levels of undesirable

subcanopy vegetation in hardwood stands, even many

years before a planned harvest, to keep interfering species

in check and continually allocate resources to preferred

species.

ACKNOWLEDGMENTS

The authors thank David L. Loftis, Thomas M. Schuler, John

P. Brown, Fekedulegn Desta, and Stephen P. Satterfield for

providing helpful review comments; and James H. Knibbs

for assisting with the NEPA process on the Monongahela

National Forest.
189

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190

INTRODUCTION

Ohio is undergoing a conversion from its oak-hickory

(Quercus and Carya) forests to primarily maple (Acer L.)

and tulip poplar (Liriodendron tulipifera L.) forests. This

change is typical among many midwest and eastern states.

Data from the USDA Forest Service forest inventories

between 1968 and 1991 (Kingsley and Mayer 1970, Dennis

and Birch 1981, Griffith and others 1993) indicate that the

proportion of total volume in oak and hickory declined substantially relative to maple, tulip poplar, and black cherry

(Prunus serotina Ehrh.). The relative importance of several

oak and hickory species in Ohio declined by at least 22 percent during this same period while maples and tulip poplars

increased by at least 38 percent in total volume. This trend

corroborates regional patterns in Illinois (Iverson and others

1989, Iverson 1994), Pennsylvania (Nowacki and Abrams

1992), and several other eastern states (Powell and others

1993). This trend has prompted a large scientific effort to

assess the problem and search for management solutions

(e.g., Loftis and McGee 1993, Abrams 1996, Brose and

others 1999, Elliot and others 1999, Huddle and Pallardy

1999, Tybirk and Strandberg 1999, Johnson and others

2002).

Several factors contribute to the decline of oaks in eastern

forests. Oaks do not regenerate well under closed canopies

and thus are declining while more shade-tolerant species

are thriving (Hilt 1985, Loftis and McGee 1993). In addition,

when light and moisture are not limiting (e.g., after a clearcut), tulip poplar and some other species can out-compete

the oak (Beck 1990, Marquis 1990). The success of oak

regeneration after a canopy-changing disturbance seems to

follow a moisture gradient, that is, regeneration of oak is

adequate only under xeric conditions in situations where it

can successfully compete with more mesic species (Iverson

and others 1997).

Historically, fire has been a component of oak forests in

southern Ohio. Dendroecological studies have shown that

fires were frequent from the time of Euro-American settlement ca. 1800 to ca. 1930 (Sutherland 1997; Hutchinson

and others 2002). However, after ca. 1930, fires usually

were suppressed, resulting in a dramatic increase in

recruitment of maples and other non-oak species.

Preliminary findings of an earlier study in southern Ohio

indicated that several burns did not sufficiently increase

light to the forest floor for satisfactory oak regeneration to

occur. Therefore, a new study was initiated in 2000 to

assess the effectiveness of thinning, in addition to prescribed

fire, for its potential to improve oak regeneration. As part of

the national Fire and Fire Surrogates Study (FFS), our

group is studying these treatments as possible means of

reducing maple abundance and fostering oak recruitment in

the Oak Hills study region.

Microclimatic effects have been found to be critical in forest

ecosystems. Topographic characteristics and surface cover

can greatly influence several microclimatic factors, including air temperature, soil temperature, and moisture (Kang

and others 2000). Human-controlled factors such as silvicultural cutting and fragmentation, also can have profound

influences on microclimatic factors (Chen and others 1999,

Zheng and others 2000). Thus, our study stratified sites by

moisture class to allow this feature to be evaluated with the

applied treatments.

FIRE AND THINNING IN AN OHIO OAK FOREST: GRID-BASED ANALYSES OF

FIRE BEHAVIOR, ENVIRONMENTAL CONDITIONS, AND TREE REGENERATION

ACROSS A TOPOGRAPHIC MOISTURE GRADIENT

Louis R. Iverson, Anantha M. Prasad, Todd F. Hutchinson,

Joanne Rebbeck, and Daniel A. Yaussy1

1 Landscape Ecologist, Ecologist, Forest Ecologist, Forest Physiologist, and Forester, USDA Forest Service, Northeastern Research Station,

Delaware, OH 43015, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Prescribed fire alone and in combination with thinning were accomplished in late 2000 to spring 2001 at

Zaleski State Forest in southern Ohio. Sites were monitored before and after the treatments were applied. Light was

assessed via hemispherical photographs taken in July 2000 and 2001. Oak and hickory seedlings and saplings were

sampled during those same time periods. Soil moisture was monitored eight times in 2001 via time-domain-reflectometry

(TDR). Air temperature was recorded every 2 seconds during the fires, and soil temperature was recorded hourly in the

months following the fires. These data allow us to evaluate, in concert with the landscape moisture patterns: (1) aspects

of fire behavior, and (2) effects of the thinning and burning on soil moisture and temperature, light, and vegetation. The

thin-and-burn treatment, relative to the control, generally resulted in more light, higher soil moisture, higher seasonal soil

temperatures, but no short-term effects on oak-hickory regeneration. The integrated moisture index (IMI), a GIS-derived

index categorizing landscape into three moisture regimes, was related to many of the measured variables: sites modeled

as topographically wetter had more soil moisture, lower fire and seasonal soil temperatures, less light penetration, and

less oak and hickory regeneration.
191

The objectives of the FFS project are to measure the effects

of both fire and thinning on oak regeneration and on

components of biodiversity within the ecosystem. In this

paper, we present a preliminary analysis, of one site, of

how the following characteristics vary among moisture

classes and treatments: (1) fire behavior; (2) seasonal soil

temperature and moisture following treatment; (3) canopy

light penetration before and after treatment; and (4) oak

and hickory seedlings and saplings before and the first

season after treatment.

METHODS

Site Description and Study Design

The results reported here are from the Zaleski State Forest,

located in Vinton County about 80 km southeast of

Columbus, OH (82o

 25' W, 39o 18' N). This is one of three

southeast Ohio sites that are part of the FFS study. The

area is part of the unglaciated Allegheny Plateau and is

characterized by dissected topography and less than 100 m

of total relief. The overstory is dominated by oak, especially

in the more xeric positions on the landscape. Oak establishment occurred from ca. 1840-1925, under conditions of frequent fire (Hutchinson and others 2002). Common species

include chestnut oak (Quercus prinus L.), white oak (Q. alba

L.), red oak (Q. rubra L.), scarlet oak (Q. coccinea Muenchh.),

black oak (Q. velutina Lam.), pignut hickory (Carya glabra

(Miller) Sweet), mockernut hickory (C. tomentosa (Poiret)

Nuttall), and bitternut hickory (C. cordiformis (Wangenheim)

K. Koch). Other common overstory species include red

maple, tulip poplar, and American beech (Fagus grandifolia

Ehrhart), which are more abundant on mesic positions of

the landscape.

Oaks are much less abundant in the midstory and understory layers, and species composition in these layers is

more strongly related to topographic influences. Oak and

hickory regeneration is present only on a few highly xeric

and open ridge-top positions. Red maple and a few other

species tend to dominate the lower strata and will likely

dominate the next forest.

The Integrated Moisture Index (IMI) was used to capture

the influence of varying topography and soils across the

landscape (Iverson and others 1997). The IMI is a GIS model

(0-100 scale) of long-term moisture availability based on

solar radiation, position on the slope, curvature of the

landscape, and water-holding capacity of the soils. IMI has

been used to predict forest site productivity and composition, understory composition and richness, soil nitrogen,

aluminum, pH, and bird distributions (Iverson and others

1996, Hutchinson and others 1999, Dettmers and Bart

1999, Boerner and others 2000, Dyer 2001). In this study,

plots were categorized into three IMI classes: xeric (score

11-34.5), intermediate (34.5-46), and mesic (46-78.5).

A sampling grid (311 points) was overlaid on the Zaleksi

site by establishing a point every 50 m, using a global positioning device (fig. 1). The site was divided into four (26 to

31 ha) treatment units: control (C), burn only (B), thin only

(T) and thin+burn (TB). Only C, B, and TB were evaluated

for this paper.

Figure 1—Map of treatment units, grid points, and IMI classes in the Zaleski State Forest.
192

Thinning occurred during the fall of 2000. For the TB site,

basal area was reduced 27 percent, from 25.5 m2/ha to

18.5 m2

/ha. The density of canopy trees (dominant/codominant) was reduced 26 percent, from 192 to 142 stems/ha,

and midstory density was reduced 41 percent, from 255 to

150 stems/ha.

The fire was conducted on 4 April 2001 between 1300 and

1553 EST. Three firing teams ignited across the north line,

across the south line, and down the middle. Each firing

team used two or three drip torches, allowing them to set

several lines of fire parallel to the control lines. During the

fires, air temperature ranged from 15 to 18 oC, relative

humidity from 23 to 35 percent, and windspeed from 5 to 6

km/hr. The area received a dusting of snow on April 1 and

about 0.3 cm of rain on the morning of April 3, so the coarser

fuels were not dry at the time of the burn. However, warm

and dry air on April 3 dried fine fuels rapidly.

Fire Temperatures and Analysis

Prior to the burn, stainless steel temperature probes (Type

K thermocouple) were installed at 60 grid points in the B

unit and 63 points in the TB unit (fig. 1). The thermocouples

were placed 25 cm above the soil surface. Hobo® data

loggers (Onset Computer Corporation) were buried 2 m

away in closed PVC containers and connected to the probes

via a buried cable. Extreme care was used to limit disturbance of the litter layer during the burial of the cable; a

hatchet was used to cut a small slit in the ground to lay the

cable and the litter layer was reconstructed over the closed

slit.

The data loggers were programmed to capture air temperature every 2 seconds on the day of the burn. From these

data, we calculated the following: (1) maximum temperature; (2) duration of temperature above 30 o

C; (3) a heat

index, defined as the summed temperatures above 30 oC

(an integral under the temperature curve); and (4) time of

maximum temperature. An example output from the Hobo

data logger software is shown in figure 2.

An animation of the burning fire was created using the data

from maximum temperature, duration of elevated temperatures, and time of the maximum temperature. For each of

123 grid points from which the data were successfully

collected, spreadsheet functions were built, for each of 248

30-second time periods, to linearly raise the temperatures

for each grid point to the maximum and down from the

maximum. The duration was used to calculate the beginning and ending times of the elevated temperatures. The

248 time-slice temperatures for each grid point were then

linked to 248 maps via ArcView 3.2a (Environmental

Systems Research Institute 1996) and interpolated via an

inverse-weighted distance function, then merged into a

movie.

Environmental Monitoring

Light, soil moisture, and soil temperature were monitored

following the burns to assess differences among treatments.

Light also was measured before the treatments. Monitoring

for all three variables was conducted at each grid point that

was not within a 50 m buffer of a treatment boundary, on

just the C (45 points) and TB (60 points) units. The two

extremes were selected for evaluation because evaluating

all four treatments was cost-prohibitive. (Ten 0.1 ha-plots in

each treatment unit are used to assess the environmental

variables at a less extensive scale. The data are not

reported here.)

To estimate understory light levels, hemispherical photographs were taken at each grid point with a digital camera

in July 2000 and July 2001. The images were analyzed for

percentage open sky and percentage transmittance with

the Gap Light Analyzer (GLA) program (Frazer and others

1999).

Soil moisture was recorded eight times during the 2001

growing season: 3 May, 17 May, 7 June, 14 June, 6 August,

20 August, 4 September, and 12 September. The large time

gap between June and August was due to equipment

failure. Moisture was sampled with a TRIME (Time Domain

Reflectometry with Intelligent MicroElements) – TDR (TimeDomain-Reflectometry) sensor. PVC tubes, sealed at the

bottom and with a removable cap at the top, were buried in

the weeks following the burn to a depth of 50 cm or bedrock.

A power auger was used to drill a hole sized equally to the

outside diameter (~5 cm) of the tube and the tube was

inserted carefully to ensure close contact between the soil

and the tube throughout its depth. The sensor measures

the volumetric soil water via electromagnetic field measurement of the dielectric constant of the soil.

The temperature probes used to monitor fire behavior also

were used to monitor soil temperature following the fires.

On the TB grid points, the probes were turned from a vertical

to horizontal position into the soil at a depth of 2 cm. On

the C grid points, the probes were positioned in a similar

fashion. The Hobo data loggers were programmed to

acquire soil temperature hourly from setup in April to

October 31, 2001.

Oak and Hickory Regeneration

At each grid point, the number of oak and hickory seedlings

(<50 cm height) was recorded in a 12.6 m2 circular plot

(2 m radius) centered on the grid point. Oak and hickory

saplings [>50 cm height to 10 cm diameter at breast height

(d.b.h.)] were recorded in a 78.5 m2

 circular plot (5 m radius)

Figure 2—Example output of the air temperature data recorder on

the day of the fire.

220

200

180

160

140

120

100

80

60

40

20

0

12:40:00 13:20:00 14:00:00 14:40:00

Temperature (±C)

04/05/01 12:34:23 04/05/01 14:42:03
193

also centered on the grid point. Vegetation data, also

recorded at the grid points but not reported here, include

the abundance of seedlings and saplings of all tree species,

species and basal area of overstory trees (recorded with a

10 basal area factor prism), and the cover of forbs, graminoids, shrubs, woody vines, and tree seedlings on the

forest floor.

Statistical Analysis

Analyses and graphic outputs were produced in Splus

(Mathsoft 1996). Analysis of variance was used to detect

trends due to treatment (B vs. TB for the response variables

for fire behavior; C vs. TB for response variables light,

moisture, soil temperature, and oak and hickory seedlings

and saplings) or moisture class (xeric, intermediate, or

mesic). For oak and hickory regeneration, the year (2000

vs. 2001) was also compared with an analysis of variance.

Interactions among treatments were also evaluated in each

analysis. Where appropriate on the three IMI classes,

multiple means were tested with Tukey’s multi-comparison

test. To test significant differences in oak and hickory seedling or sapling densities between 2000 and 2001, a pairwise t-test was used with 100 paired samples.

RESULTS AND DISCUSSION

Fire behavior

The B unit had an average maximum temperature of 174 oC,

while the TB unit averaged 138 oC (fig. 3). The B unit burned

later in the day when there was higher air temperature and

lower humidity. However, on the TB unit, temperatures

exceeding 30 oC lasted an average of about 11 minutes,

compared to 9.5 minutes on the B unit; likely the result of

fuel moisture differences. The average heat index, which

takes into account both temperature and duration, was

10,556 for the B unit and 9,177, or about 13 percent less,

on the TB unit (fig. 4).

There was a significant trend with moisture class for average heat index (ANOVA, P = 0.02): 12,734 for xeric, 9,729

for intermediate, and 7,639 for mesic sites (fig. 4). This

trend is reflective of conditions where the fuels remained

moister in the mesic areas from the rain and snow dusting

the previous few days. Maximum temperature was not

statistically different among moisture classes, although

xeric sites had higher temperatures (175 o

C) than the

intermediate (150 o

C) or mesic sites (147 oC) (fig. 3).

Animation of fire

The recorded information from the sensors located each

50m throughout the study area allowed us to evaluate and

visualize some aspects of the fire behavior. Although the

animation cannot be shown in this paper, the reader is

encouraged to view it at the web site at: http://www.fs.fed.us/

ne/delaware/4153/ffs/zaleski_burn.html.

This animation shows the fire being set from the east, along

both north and south fire lines, as well as some internal

firing. The simulation also shows a slower rate of spread in

the valleys, with hotter, faster fires on the more xeric

locations.

Light

A total of 112 hemispherical photographs were analyzed

with the GLA software: 43 in 2000 (pre-thinning and burning) and 69 in 2001 (post treatments). There was a large

increase in percentage open sky after thinning and burning,

from 7.1 percent to 11.9 percent, on average (fig. 5). The

percentage open sky varied by moisture regime, with the

more mesic locations having a slightly more closed canopy

Figure 3—Maximum air temperatures (+ standard error of mean)

recorded during the day of the fire, by treatment and moisture

class. Legend: (1) site - Z=Zaleksi; (2) treatment – B=Burn,

TB=Thin and Burn; (3) moisture class - X=xeric, I=intermediate,

and M=mesic.

Figure 4—Cumulative heat index, calculated from maximum

temperatures and duration, by treatment and moisture class.

Legend: (1) site - Z=Zaleksi; (2) treatment – B=Burn, TB=Thin and

Burn; (3) moisture class - X=xeric, I=intermediate, and M=mesic.
194

than xeric or intermediate. Even after thinning, the mesic

locations had only 9.5 percent open sky as compared to

over 12.1 percent for the other two treatments (fig. 5). The

mesic sites, in addition to receiving less solar radiation, were

more difficult to harvest because of longer skid distances

and often steep topography.

Moisture

In general, the moisture levels decreased as the season

progressed (fig. 6). The September 2001 data showed much

drier conditions than the average values. Soil moisture variability was fairly high as expected from the field data. Many

factors contribute to the detected moisture levels at a given

location, including the amount of litter, green material,

proximity to large tree roots, macro- and micro-topographic

influences, drainage, microfissures in the soil, nearby

animal activity, and errors associated with the technology.

Though not statistically significant, mean moisture levels

were usually higher on the TB unit compared to C (fig. 6).

We suggest that the removal of trees during thinning may

have reduced substantially the amount of soil moisture

transpired. The smaller plants, more abundant on the TB

sites, transpire only a fraction of what larger trees do, so

removal of overstory trees will substantially remove total

leaf area and reduce transpiration. Transpiration per unit of

land area has been shown to generally increase with greater

leaf area index unless the canopy boundary layer resistance

is so high that energy input controls evaporation (Landsberg

1986). In addition, the TB unit tended to have more green

coverage at the herbaceous level, possibly providing a

‘living mulch’, which reduces solar radiation at the surface,

perhaps to a level even lower than that on the C unit.

Moisture levels tended to increase from xeric to mesic IMI

classes, though differences were not statistically significant.

The higher moisture readings observed on the xeric TB unit

can be traced to several outlier points which exist in complicated topographic settings not captured adequately in GIS

using 30 m digital elevation model pixels. One would expect

that it is more likely to find pockets of mesic conditions

within an area classified as xeric (e.g., small drainages not

detectable in 30 m grid cells), than vice versa.

Soil Temperature

Soil temperatures were recorded hourly from 13 April to

31 October, 2001, for each of the 105 points. There was a

substantial treatment effect, with the TB unit having significantly higher (P <0.001) soil temperatures than the C unit

throughout most of the season (fig. 7). The greatest differential was in April, when the soil surface was blackened

following the spring fires. At this time, the daily maximum

temperature differentials were as much as 4 o

C. In an earlier

study, we found similar trends, with soil temperatures as

much as 6.2 o

C higher on burned vs. control sites in May

(Iverson and Hutchinson 2002).

There were also significant (P <0.03) temperature differences among moisture classes in all months except August

(P = 0.06) and October (P = 0.37). In general, daily maximum temperatures were greatest on xeric and least on

mesic areas (fig. 7). This pattern can be explained by

increasing soil moisture content and associated thermodynamics (fig. 6), as well as decreasing solar radiation

exposure (fig. 5) from the xeric to mesic moisture regimes.

Figure 5—Percent open sky, 2000-2001 for Zaleski, as analyzed

from hemispherical photographs and the GLA software. Legend:

(1) site - Z=Zaleksi; (2) treatment - C=control, TB=Thin and Burn;

(3) moisture class - X=xeric, I=intermediate, and M=mesic. Figure 6—Percent soil moisture, by volume, for the Zaleski site

during the 2001 growing season. Shown are the overall average

values (eight sampling dates and three depths) and the last

sampling date, from September 12-17, 2001. Legend: (1) site -

Z=Zaleksi; (2) treatment - C=control, TB=Thin and Burn; (3)

moisture class - X=xeric, I=intermediate, and M=mesic.
195

Oak and Hickory Regeneration

There was an average of 8,060 oak or hickory seedlings/ha

in 2000 and 6,390 seedlings/ha in 2001. There were very

few oak or hickory saplings (>50 cm to 10 cm d.b.h.): 40 per

ha in 2000 and 48 per ha in 2001. There were no significant

differences in oak and hickory seedling or sapling densities

between years using a pairwise t-test (N = 100 paired

samples).

Oak and hickory seedling densities were significantly different among moisture classes (ANOVA, P=0.02), while treatment effect was nearly significant at the 5 percent level (P =

0.06), and year was not significant (fig. 8). No interaction

effect was present. Fire and thinning treatments did not

alter the number of oak or hickory seedlings in the first

growing season following the spring fires: similar patterns

existed before (2000) and after (2001) treatment. In both

years, the TB unit had slightly more oak and hickory seedlings on the xeric and intermediate moisture classes, and

slightly less on the mesic sites. Over both years and both

treatments, the mesic sites had significantly fewer oak and

hickory seedlings as compared to the other moisture

classes. There were no significant differences in sapling

densities among moisture classes, treatments, or years.

Figure 7—Daily maximum soil temperatures, averaged by month, for the Zaleski site during the 2001 growing

season. Data were extracted from hourly data collect from 105 sensors. Legend: (1) site - Z=Zaleksi; (2)

treatment - C=control, TB=Thin and Burn; (3) moisture class - X=xeric, I=intermediate, and M=mesic.

Figure 8—Oak and hickory seedling numbers per quadrat (2 m

radius circle=12.87 m2) for Zaleski, 2000-2001. Legend: (1) site -

Z=Zaleksi; (2) treatment - C=control, TB=Thin and Burn; (3)

moisture class - X=xeric, I=intermediate, and M=mesic.
196

CONCLUSIONS

We have demonstrated a method to capture some aspects

of fire behavior during prescribed surface fires in eastern

forests. Thermocouples and data recorders buried prior to

the fires successfully logged temperatures every 2 seconds,

which allowed analysis of maximum fire temperatures,

duration, and heat index. With a spatial analysis of the

data, a movie animation of the fire was created.

This study also provides a preliminary analysis of two

primary factors related to landscape-level microclimate and

vegetation: a human-controlled silvicultural regime of thinning and burning, and a topographically controlled moisture

index. The thin-and-burn treatment, as compared to the

control, resulted in higher seasonal soil temperatures. The

blackened surface and the open canopy facilitated more

absorption of solar radiation. The TB unit also increased

soil moisture levels near the soil surface apparently because

of reduced evapotranspiration. An evaluation of the thin-only

and burn-only treatments (pending analysis of plot-level data)

is needed to better assess these cumulative effects. In this

first season after treatment, we did not detect a difference

in oak and hickory regeneration between TB and C units.

The integrated moisture index also was related to the measured variables. The wetter sites had higher soil moisture,

though there was a lot of variability associated with finescale features on the landscape. The IMI was based on a

30 m digital elevation model (DEM). If a finer-resolution

DEM were available, perhaps the small ravines (less than

30 m wide) would be captured more accurately by the moisture index. Wetter sites also had lower fire temperatures

and seasonal soil temperatures due to less incoming solar

radiation. We also found lower light availability on the wetter

zones. These sites tend to be the most difficult to harvest

with poor accessibility. Finally, the wetter zones had significantly fewer oak and hickory seedlings and saplings. In

fact, it was difficult to find a sapling on any site, but especially in the wetter zones. These data provide further

evidence that these species regenerate poorly under

closed-canopy, mesic conditions.

Though oak and hickory regeneration densities were unaffected by treatments, personal observation indicates that at

least some of the resprouted oaks and hickories exhibit

increased growth given adequate light and reduced competition from fire-sensitive species such as red maple. We are

hopeful that over time, adequate oak and hickory advance

reproduction will develop on the treated sites, thus improving

the sustainability of forests that have been long dominated

by oaks and hickories.

ACKNOWLEDGMENTS

We thank many field and laboratory personnel that acquired

much of the data presented here: David Hosack, Robert

Ford, Becki Wells, Justin Prindle, Kristy Tucker, Brad Tucker,

Lisa Pesich, Justin Wells, Jeff Mathews, Matt Weant, Karyn

Tremper, Aaron Iverson, and Margaret Iverson. Thanks also

to Robert Long, Sara Duke, and Susan Wright for reviewing

the manuscript. This is contribution number 16 of the

National Fire and Fire Surrogate Research Project. Although

the authors received no direct funding from the U.S. Joint

Fire Science Program (JFSP), this research could not have

been accomplished without JFSP support of existing Fire

and Fire Surrogate project sites. This research was also

supported in part by the National Fire Plan through the

Ohio Hills Fire Behavior and Effects project administered by

USFS Project-4153.

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198

INTRODUCTION

Traditionally, interest in forest growth and yield has been

associated with timber production. However, growth and

yield is simply one aspect of the broader subject of stand

dynamics that deals with changes in stand size structure

and species composition over time. These changes can be

related to timber yield, but they can also be related to yield

in wildlife habitat, quantity of mast production, aesthetic

qualities, or even ecological services such as storing carbon

or maintaining species diversity. Like timber yield, yield of

these other products and amenities changes over time and

in response to management activities. Yield tables or

growth models can aid in estimating future quantities of all

these outputs.

Growth and yield can be evaluated and analyzed at different spatial resolutions. Stand growth and yield (per acre) is

often of primary interest, but stand growth is the composite

outcome of growth and survival of thousands of individual

trees. Hence, growth of individual trees as affected by

species, size, and competition is also often of interest,

particularly for stands with mixed species and multiple age

classes. Likewise, the composite growth and yield of multiple

stands in a geographic region, their spatial arrangement,

and their anticipated change over time can be important in

forest planning, locating a new wood using facility, or dealing with insect or disease problems.

Major factors that affect growth and yield of oak trees and

oak stands are presented in this paper. Particular emphasis

is given to response to thinning, changes in stand structure,

and changes in species composition over time.

OAK TREE GROWTH

There are clear differences among species in diameter

growth rates (fig. 1). For example, mean growth rates for

scarlet oak in Missouri are approximately twice those for

post oaks of comparable diameter. Over several decades

these differences can result in substantial differences in

tree diameter (and often a tree’s height and crown position). However, tree longevity also plays a role, and over

many decades the faster growing black and scarlet oaks

are less likely to survive than white or post oaks, other

factors being equal (Shifley and Smith 1982, Smith and

Shifley 1984). Hence, in the long run, persistent oaks such

as white oaks can often capture dominance from fastergrowing, shorter-lived trees in the red oak group. We probably underestimate the influence of periodic droughts and

other infrequent but severe external stressors in affecting

longevity and species composition over the life of a stand.

Such events may only occur once or twice during a rotation,

but they can radically change stand species composition

(e.g., the disproportionate loss of red and black oaks during

drought-induced oak decline).

OAK GROWTH AND RESPONSE TO THINNING

Stephen R. Shifley1

1 Research Forester, USDA Forest Service, North Central Research Station, University of Missouri, Columbia, MO 65211.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Oak growth and yield is simultaneously influenced by tree-, stand-, and landscape-scale factors. At the tree

scale oak diameter growth varies by tree species (typically n. red oak >= scarlet oak > black oak > white oak > chestnut

oak > chinkapin oak > post oak), but oak diameter growth is even more strongly influenced by crown class. Oak stands go

through up to 5 stages of development that differ in tree size structure and stand dynamics. Knowing a stand’s developmental stage helps guide the application of thinning practices and other silvicultural techniques. Periodic thinning

beginning at age 30 in oak stands can double board foot yield over a rotation relative to unmanaged oak stands. This

results from capturing volume that would otherwise be lost through mortality and from reallocating growing space to

desirable trees. The greatest increases in yield occur when a series of periodic thinnings is started when the stand enters

the stem exclusion stage of development. Stump sprouts require even earlier treatment to maximize growth. Estimating

future growth and yield in even-aged stands is often facilitated by application of mathematical models; models are a

necessity for growth estimation in uneven-aged stands and stands with a large non-oak component.

Figure 1—Mean periodic tree diameter-at-breast-height growth for

black (Quercus velutina Lam.), scarlet (Q. coccinea Muenchh.),

white (Q. alba L.), and post oaks (Q. stellata Wangenh.) in

Missouri (based on Shifley and Smith 1982).
199

Crown position is even more influential than species in

controlling diameter growth. A tree’s crown class (dominant,

codominant, intermediate or overtopped) can completely

overshadow differences among species (fig. 2). Trimble

(1969) stated that crown class is the single most important

factor in tree diameter growth, and it is clear that a dominant

or codominant oak of nearly any species will, on average,

grow faster in diameter than an overtopped or intermediate

oak of any other species.

Tree crown class is the result of the competitive sorting that

takes place as trees increase in size and vie for a finite

amount of growing space. The average annual diameter at

breast height (d.b.h.) growth for a stand decreases as stand

age and basal area increase, but those dominant and

codominant trees that are well positioned in the canopy

continue to grow rapidly at the expense of trees that have

smaller or crowded crowns. Trees rarely improve their crown

class over time unless a timber harvest or other significant

stand disturbance occurs to release growing space. Thus, if

a tree achieves a dominant or codominant crown class, it

must maintain that canopy position or it will eventually lose

out to competitors. Thinning manipulates crown classes

and growing space to favor trees that satisfy management

objectives.

Compared to diameter growth, the height growth of dominant and codominant trees is less affected by stand density.

Hence, height growth of trees that have continuously

remained in these two crown classes is used to measure

site quality via site index. Previous studies have shown that

on the same site the site index (i.e., height in feet at age

50) for scarlet oak is 3 feet greater than for black oak which

is in turn 4 feet greater than for white oak (McQuilken 1974).

However, oaks have different height growth patterns. Scarlet

and black oak get off to a rapid start but slow after 50 or 60

years. When the trees reach 100 years, white oaks in the

upper canopy will often be 10 to 15 feet taller than black

oaks (Carmean 1971). Tree height growth and site index

are, of course, closely linked to volume growth of trees and

stands.

In contrast to trees in the upper canopy, height growth of

trees in subordinate crown classes is greatly affected by

competitors, and oaks that fail to maintain a favorable

crown position usually face an early demise, barring some

disturbance to the overstory that increases available growing space. One of the few oak height models based on tree

diameter and age (regardless of crown class) was published

by Hilt and Dale (1982) as part of the OAKSIM model.

Over long periods of time, oaks that are persistent (e.g.,

through sprouting or through greater shade tolerance than

competitors) are sometimes able to survive, despite the

presence of faster growing competitors. For example, white

oak (which is slower growing but longer lived and slightly

more shade and drought tolerant than black, red, and scarlet

oak) may eventually achieve dominance opportunistically.

This may be the result of a designed timber harvest, or it

may occur by chance when shorter lived species reach the

end of their life span or when the droughts or other disturbances (that inevitably occur over the course of a long rotation) take their toll on other species. As the number of sites

monitored continuously over many decades gradually

increases, the importance of extreme events (e.g., drought,

ice, fire, partial harvest) in triggering changes in species

composition is increasingly apparent.

Figure 2—Effect of tree crown class on diameter growth for oaks and hickories in Missouri. The hickory group is a

composite of all Carya spp. (based on Shifley and Smith 1982).
200

TREE RESPONSE TO THINNING

Controlling tree crown class through thinning is the single

most important thing a manager can do to increase tree

growth and stand yield over time. Studies in oak stands

have demonstrated that dominant and codominant oaks will

respond to increased thinning intensity with increased diameter growth across a wide range of diameters and ages,

even if stand stocking is reduced to 30 percent or less

(Dale 1972). Note, however, that oak management guides

for timber production generally recommend keeping minimum stocking above 50 percent to avoid development of

epicormic branching and to fully utilize the growing space

per acre. At lower stocking levels, diameter growth of individual trees is increased, but stand growth is typically not

maximized. Significant thinning effects have been reported

for red, black and scarlet oaks up to 90 years old in

Connecticut (Ward, 2002).

It often takes two years for tree diameter growth to achieve

maximum response to thinning, and the effects of thinning

on individual overstory trees may persist for as long as two

decades. When trees are given a competitive advantage

through thinning, they are often able to maintain that

advantage by increasing their crown area and capturing

growing space which allows them to maintain the faster

growth rate for years. There are two general exceptions to

this response to thinning. First, trees with small, poorly

formed crowns (e.g., intermediate and overtopped crown

classes) may not respond at all to thinning, or the response

may be delayed by three to five years as tree crowns

gradually enlarge to capture the growing space release by

thinning. Second, oaks in stands less than 10-years old

may not increase their diameter growth in response to thinning. In young stands crown classes are not firmly established, and the growing space released by the removal of a

young tree is small relative to the ability of surrounding trees

to expand and capture growing space. The rapid growth of

vegetation relative to tree size in young stands means the

effect of thinning is generally short-lived. Thus, the potential

benefits of thinning in seedling/sapling stands can be quickly

erased by crown expansion in residual trees and a flush of

herbaceous growth. Consequently, diameter growth of

dominant and codominant trees less than 10 years old has

shown a variable response to thinning. When stands are

very young, the intermediate and overtopped trees are

actually more likely to respond to thinning with increased

diameter growth than are larger trees. Herbicides applied to

cut trees may increase the duration of the thinning effect in

young stands (Johnson and others 2002).

Oaks often originate as stump sprouts, and sprouts present

a different situation with respect to thinning young trees.

Thinning has been demonstrated to be effective in increasing diameter growth on sprouts that were as old as 25 years,

but the sooner sprout clumps are thinned to a single stem

(down to 5 years of age), the greater the gain in diameter

growth relative to unthinned clumps (Johnson and others

2002). Early thinning of stump sprouts to a single stem can

double diameter growth relative to sprouts in unthinned

clumps; diameter increases of 30 to 60 percent are common,

depending on site index and initial tree size (Johnson and

Rogers 1980). Although retaining the single largest sprout

typically results in the largest future tree, smaller sprouts

released at an early age can perform nearly as well. Consequently, retaining sprouts based on form rather than tree

size will result in relatively little loss in future size (Johnson

and others 2002).

STAND GROWTH AND RESPONSE TO THINNING

As even-aged oak stands develop over time they go through

five stages of stand development: (1) stand initiation, (2) stem

exclusion, (3) understory reinitiation, (4) complex, and

(5) mixed stage (fig. 3) (Johnson and others 2002, Oliver and

Larson 1996). These stages are defined by the population

dynamics governing the tree community at each stage of

development. For upland oaks in the Central Hardwood

Region, the stages of development are associated with a

characteristic range of stand ages. The stand dynamics at

each stage govern the efficacy of thinning and the stand

response to thinning. Thus, knowledge of a stand’s stage of

development is useful in understanding when, why, and

how to thin.

Following a stand initiating disturbance (e.g., clearcut or

stand-replacing fire) even-aged oak stands enter the stand

initiation stage of development (fig. 3). New trees are

added to the stand, tree crowns expand rapidly relative to

their initial size, and trees compete intensely for growing

space. Woody vegetation is often dense and “brushy”. At

this stage the growing space that is released by the death

or removal of individual trees is rapidly occupied by the

expanding crowns of surrounding trees. Consequently, thinning effects are short lived and highly variable. However,

thinning stump sprouts is an exception. Because clumps of

stump sprouts share the same growing space and the same

root system, competition among them is much more intense

than for seedlings or seedling sprouts with a single stem.

Young sprout clumps respond with rapid growth when they

are thinned to a single stem. In essence, clumps of stump

sprouts begin life in the stem exclusion stage of development and stump sprout response to thinning is similar to

that described below for stands in the stem exclusion stage

of development.

As oak stands mature and move into the stem exclusion

stage of development, the site is fully occupied and the

number of trees in the stand naturally decreases as trees

increase in size (fig. 4). Trees that are at a competitive

disadvantage are eliminated from the stand. In the absence

of a major disturbance, the number of trees per acre will

decrease exponentially over time. This change can be

expressed graphically as a function of age or in the format

of a Gingrich-style stocking chart.

It is during the stem exclusion stage of development that

managers can have the greatest impact on stand growth and

yield. Thinning conducted during this stage of development

can recover trees that will otherwise die and simultaneously

reallocate growing space to the most desirable residual

trees based on species, size, or form. Increased volume

yield from thinning is the combined result of (1) utilizing trees

that would otherwise die and (2) increasing the growth of

selected residual trees (fig. 5). In his yield tables for thinned

oak stands, Gingrich (1971a, 1971b) indicated that by thinning a stand early and often it is possible to double board

foot volume yield relative to unthinned stands. The key is to
201

Figure 3—Stages of oak stand development with notes on thinning for increased timber production and on other management practices (based on Johnson and others 2002, illustrations

by David Hamilton).
202

Figure 4—(A) The shift from the stand initiation stage to the stem

exclusion stage of development is signaled by the change from

increasing to decreasing trees per acre over time. This occurred at

about age 17 in this example. (B) Basal area continues to increase.

The solid line shows data for a bottomland sweetgum-red oak

stand (Johnson and Krinard 1988) and the dashed line shows data

for an upland oak-mixed hardwood stand in Connecticut (Ward and

others 1999).

Figure 5—Yield of thinned and unthinned stands over time. With

regular thinning, the combined yield of cut and residual trees can

double the yield of an unmanaged stand (based on Gingrich

1971a).

start thinning early in the stem-exclusion stage of development—approximately age 30 for eastern oak stands. The

biggest net increases in total volume occur by thinning oak

stands on excellent sites, but even on moderate and poor

sites total yield can be doubled relative to unthinned stands.

During the understory reinitiation stage the stand is nearing

economic maturity and silvicultural practices in oak stands

generally concentrate on establishing desirable advance

reproduction and maintaining tree quality. Thinning during

this stage of development will result in faster growth of vigorous residual trees on good sites. Due to the relatively large

tree crowns, removal of trees by thinning will also provide

more light to the forest floor and canopy gaps will persist

longer than at earlier stages of development. Economically

the major concerns associated with thinning at this stage

revolve around (1) minimizing epicormic branching, (2) minimizing mechanical damage of residual trees, (3) controlling

future species composition, and (4) ensuring that thinning

prior to overstory removal provides sufficient time (about a

decade) to capture the response of residual trees. For oak

stands that are to be managed on long rotations or to be

converted to uneven-aged silviculture, commercial thinning

through the stem exclusion stage of development will

typically result in faster growth and greater total yield.

When a stand reaches the complex stage of development

(fig. 3), it has become an uneven-aged stand because

canopy gaps are sufficiently large to recruit new age cohorts.

Thinning to promote overstory crop trees or thinning to promote the development of a balanced uneven-aged stand

structure is warranted if the goal is uneven-aged

management.

It is difficult to generalize about growth and yield for oak

stands with mixed species and multiple age classes.

Although the same basic principles apply with regard to

how trees respond to stand density and crown class, the

differential growth and survival rates among tree species

and size classes can greatly affect the oak component of

the stand. Estimating growth and yield for such stands

requires the use of mathematical models. Mathematical

models also facilitate exploring the outcome of alternative

thinning practices on stand development. For example,
203

Table 1—Oak growth and yield models (excludes regeneration models)

Model type and name Applicability Notes

Yield Tables

Upland oaks (Schnur 1937) Well-stocked, even-aged, Comprehensive yield, composition, and size structure information by site

unmanaged upland oak stands; index and age; the primary reference for upland oak yield in fully stocked,

geographic range is bounded by unmanaged, minimally disturbed stands; good baseline source of

New York, southern Michigan, comparison for managed stands

Missouri, Tennessee, and

western North Carolina

Oak woodlots (Gevorkiantz Even-aged, mixed oak stands in Comprehensive volume yield by age and site quality; good baseline for

and Scholz 1948) western and south-central comparison of managed stands

Wisconsin

Managed upland central Central hardwood region, even- Good guidance on the broad-scale effects of thinning on stand yield

hardwoods (Gingrich aged upland stands that are by age, and site index; thinning prescriptions are linked to Gingrich (1967)

1971a, 1971b) managed or where stocking guide and management guides by Roach and Gingrich (1962,

management is contemplated 1968)

Stand-Level Models

GROAK (Dale 1972, 1973) Based on data from Ohio, Predicts oak growth and yield as function of stand age, stand basal area,

Kentucky, Missouri, and Iowa; and site index; evaluates the effects of thinning on oak growth and yield;

applicable to even-aged, upland more versatile than yield tables for thinned oaks; models can be applied

mixed oaks stands using spreadsheet software; also incorporated into the Northeast Decision

Model (NED) (http://www.fs.fed.us/ne/burlington/ned/)

Upland oaks (Graney and Boston Mountains region in A recalibration and detailed evaluation of methodology used on GROAK

Murphy 1994) northwest Arkansas as applied to the Boston Mountain region

Minnesota yield models Oak-hickory forests in Minnesota Predicts growth and yield as a function of stand age and stand basal area;

(Walters and Ek 1993) based on statewide Forest Inventory and Analysis inventory data including

stands with a wide variety of past disturbances; good indicator of regional

“woods run” yields; part of a system of models for 14 Minnesota forest

types

Appalachian hardwood Appalachian hardwoods in the Predicts density, height, and volume for red oak, white oak, and other

mutltispecies model Blue Ridge ecoregion of North species groups, including d.b.h. frequency distribution by species

(Bowling and others 1989) Carolina and Georgia

Individual-Tree Models

OAKSIM Even-aged upland oak stands Estimates growth and survival of individual trees with overall stand growth

(Hilt 1985a, 1985b) aged 3 to 120 years in southern constrained to be consistent with Dale’s (1972) GROAK model; one of the

Ohio and eastern Kentucky few sources of oak height growth and taper equations (Hilt and Dale

1982); can be implemented using the NED http://www.fs.fed.us/ne/

burlington/ned/

TWIGS Even- and uneven-aged stands Software allows simulated thinning, volume estimation, and economic

Miner and others (1988), with pure or mixed species; four analysis; tree growth and survival models have been incorporated into

Bolton and Meldahl regional variants cover from FVS (see below) http://www.ncrs.fs.fed.us/pubs/Software

(1990a, 1990b), and Hilt Minnesota to Missouri to West

and Teck (1989) Virginia to Maine, and Alabama,

Georgia, and South Carolina

FVS (Forest Vegetation Regional variants (21) are Good software support and excellent integration with data management,

Simulator) applicable to major forested scenario evaluation, output, and display tools; nationally implemented and

http://www.fs.fed.us/fmsc/ regions of the United States; supported; can be user-calibrated with local inventory data; applicable to

fvs/. variants applicable with oaks all major species groups within a region; includes models for some

include Lake States, Central western oak species groups; models governing species dynamics are

States, Northeast, Southeast, from a variety of sources including PROGNOSIS (Stage 1973), TWIGS

South, Central Rockies, (see above), and those developed specifically for FVS

Klamath Mountains, Pacific

Northwest Coast, Westside

Cascades, and Westside Sierra

Nevada

GHAT Even-aged Appalachian mixed Height growth, diameter growth, volume growth, and survival following

Harrison and others hardwoods in Blue Ridge thinning; designed specifically to address response to thinning in mixed

(1986, updated 2000) physiographic province of species stands; includes equations for white, black, northern red, scarlet,

Virginia, North Carolina, and chestnut oaks http://www.cnr.vt.edu/g&y_coop/ghat.pdf

 Tennessee, and Georgia
204

thinning or other cultural treatments that target particular

tree species such as the oaks (favorably or adversely) can

greatly alter future growth, yield, species composition and

value. It often takes decades for the oak cohorts in a mixed

species stand to succeed or fail, and models are the only

practical tools available to address growth and yield for the

infinite range of mixed stands that occur. Growth and yield

models applicable to oaks and oak mixtures are summarized

in table 1. Models accommodate a wide range of initial

stand conditions, can evaluate alternative management

regimes, produce repeatable results, and are increasingly

used as a component of larger simulation and management

systems. Examples include the Northeast Decision Model

(NED) (http://www.fs.fed.us/ne/burlington/ned/), and national

forest planning efforts based on the Forest Vegetation

Simulator (FVS) (http://www.fs.fed.us/fmsc/fvs/).

ECONOMIC CONSIDERATIONS

Simulation models also facilitate economic analysis of thinning alternatives. Some models have integrated economic

analysis capabilities. Predicted outcomes can also be

analyzed in stand-alone economic analysis software which

is widely available. Professional judgment and field experience are still required to evaluate potential effects of thinning on tree quality. In economic terms potential changes in

tree grade can supercede the effects of total volume growth,

and the available models have little or no capacity to predict

changes in tree grade. Reported economic returns from

thinning vary greatly depending upon the condition of the

stand prior to thinning, growth response, and alternative

rates of return (Johnson and others 2002). However, given

the uniformly low alternative rates of return currently available, investment in hardwood thinning is as attractive an

investment as at any time in the past several decades.

SUMMARY

Thinning has the potential to as much as double total yield

over a rotation by capturing volume that would otherwise be

lost to mortality. However, to maximize the effect, thinning

should begin early in the stem exclusion stage of stand

development and be repeated until one or two decades

prior to a regeneration harvest. In addition to increasing

total merchantable yield, thinning can increase tree quality

and value. Tree conditions (species, crown class), stand

conditions (stage of development, density, species mixture),

and even landscape conditions (e.g., potential risk of disturbance by pathogens or fire) are all important considerations

in thinning decisions. Perhaps most important is an understanding of the stand’s stage of development. The stage of

development (stand initiation, stem exclusion, understory

reinitiation, complex, or mixed) provides important information on the stand’s natural dynamic. Thinning is usually most

effective when the silviculturist or resource manager works

with, rather than against, the stand’s natural dynamic (e.g.,

thinning to increase volume growth when the stand is in the

stem exclusion stage, thinning to facilitate advance regeneration when the stand is in the understory reinitiation stage,

etc.) Most effective thinning practices are designed to work

in concert with the stands natural dynamic and to accelerate change to meet ecological or economic objectives. A

wide range of simulation models are available to explore

alternatives for specific stand conditions.

ACKNOWLEDGMENTS

Thanks to Dan Yaussy, USDA Forest Service, Northeastern

Research Station, Delaware, OH, and to Ross Melick and

Charly Studyvin, Mark Twain National Forest, USDA Forest

Service, Rolla, MO, for helpful suggestions on an earlier

version of this manuscript.

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growth and yield simulator for managed, even-aged, upland

oak stands. Gen. Tech. Rep. NE-104. Broomall, PA: U.S.

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Experiment Station. 22 p.
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206

INTRODUCTION

Oaks are important to wildlife and, in turn, in forest energetics. Wildlife species that utilize oak mast include whitetailed deer (Odocoileus virginianus), black bear (Ursus americanus), turkey (Meleagris gallopavo), blue jays (Cyanocitta

cristata), squirrels (Tamiasciurus spp., Sciurus spp., and

others), and mice (Peromyscus spp.). For instance, a study

by Harlow (1975) found that acorns made up an average of

76 percent of the diet of white-tailed deer during November

and early December. Fluctuations in wildlife populations

often follow fluctuations in oak mast production (McShea

and Schwede 1993, Nixon and others 1975, Wentworth and

others 1990). Major declines in the population of oaks could

lead to similar declines in the populations of associated wildlife species where alternative resources are not available.

Over the last several years, oak decline has had a major

impact throughout the Ozark Highlands. Mortality over large

forest areas has led to the creation of shelterwood-like

conditions. However, previously dense overstories have left

many of these sites without oak regeneration or regeneration of sufficient size to survive competition from more shadetolerant competitors. To address restoration of these sites,

management methods are needed that can place oaks in a

desirable position in relation to their interspecific competitors so that they may survive to become part of the future

forest.

One option for restoring oak to these sites may be to plant

oak seedlings under a shelterwood. For instance, Dey and

Parker (1997) found that 99 percent of northern red oak

seedlings were alive 2 years after underplanting in a shelterwood (50 percent crown cover) while only 90 percent

survived in a closed-canopied undisturbed stand. Additionally, root volume, area, and dry mass were significantly

greater for the shelterwood-planted seedlings. In a study

comparing overstory density and understory competition,

Teclaw and Isebrands (1993) found that underplanted

northern red oak performed better in shelterwoods with

25 percent crown cover than those with 50 percent crown

cover. In this study we summarize the success of shelterwood-underplanted northern red oak (Quercus rubra L.)

seedlings relative to interspecific competitors and provide

management recommendations to optimize underplanting

success.

The objectives of this paper are (1) to summarize the 11-

year success of planting northern red oak seedlings under

shelterwoods from which they were released 3 years after

planting and (2) to recommend management methods to

optimize successful underplanting of northern red oak

based on these results.

SITES

The study sites were located in the Boston Mountains of

Arkansas in the southern lobe of the Central Hardwood

Region (Merritt 1980). The Boston Mountains are the highest and most southern member of the Ozark Plateau physiographic province. They form a band 30 to 40 miles wide and

200 miles long from north-central Arkansas westward into

eastern Oklahoma. Elevations range from about 900 feet in

the valley bottoms to 2,500 feet at the highest point. The

plateau is sharply dissected; most ridges are flat to gently

rolling and are generally < 0.5 mile wide. Mountainsides

consist of alternating steep simple slopes and gently sloping

benches.

Soils on mountaintops and slopes usually have shallow to

medium depth and are represented by medium-textured

members of the Hartsells, Linker, and Enders series (Typic

Hapludults). They are derived from sandstone or shale residuum, and their productivity is medium to low. In contrast,

soils on mountain benches are deep, well-drained members

of the Nella and Leesburg series (Typic Paleudults). They

developed from sandstone and shale colluvium, and their

productivity is medium to high. Rocks in the area are

SUCCESS OF UNDERPLANTING NORTHERN RED OAKS

Martin A. Spetich, Daniel C. Dey, Paul S. Johnson, and David L. Graney1

1 Research Forester, USDA Forest Service, Southern Research Station, Hot Springs, AR 71902; Research Forester, USDA Forest Service,

North Central Forest Experiment Station, Columbia, MO 65211-7260; Research Forester, Retired, USDA Forest Service, North Central

Research Station; and Research Forester, Retired, USDA Forest Service, Southern Research Station, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—We summarize results of the growth and survival of northern red oak (Quercus rubra L.) seedlings 11 years

after planting in shelterwoods in the Boston Mountains of Arkansas. Shelterwood overstories were harvested 3 years after

underplanting > 4,000 northern red oak seedlings. Woody vegetation that was competing with planted seedlings received

two, one, or no competition control treatment(s). Results are expressed as the probability that a planted tree will live to

attain a favorable competitive position at a specified year. These probabilities depend on initial seedling stem caliper

before planting, site quality, weed control intensity, and shelterwood percent stocking. These probabilities of success

increase with decreasing shelterwood stocking, decreasing site quality, increasing initial stem caliper, and increasing

intensity of weed control. The reciprocals of the dominance probabilities provide silviculturally useful estimates of the

numbers of trees that would need to be planted to obtain, on the average, one competitively successful tree in the future.

Based on these results, we provide practical management methods to optimize success of underplanted northern red oak

seedlings and to reach future stocking goals.
207

alternating horizontal beds of Pennsylvanian shales and

sandstones. Annual precipitation averages 46 to 48 inches;

March, April, and May are the wettest months. Extended

summer dry periods are common, and autumn is usually

dry. The frost-free period is normally 180 to 200 days long.

METHODS

A total of 4,320 2-0 seedlings, undercut the first year in the

nursery, were planted in early April 1987 at a 7.9- by 7.9-foot

spacing in a split-split plot experimental design with five replicates (locations). The later loss of two main plots resulted

in 4,128 seedlings being available for this study. Site index

for red oaks (northern red and black oaks) ranged from 60

to 79 feet based on indirect estimation from soil and topographic factors (Graney 1977). Planted trees and competition

were measured after the 1st, 3rd, 4th, 6th, 8th, and 11th growing

seasons. This manuscript summarizes the 11th-year performance (8 years free of the shelterwood) of planted trees.

Designed study variables fall into two major categories:

(1) those related to planting environment and (2) those

related to nursery production. The former include shelterwood residual overstory density (40, 60, and 80 percent

stocking) and three different competition control treatments

(no competition control, one competition control treatment,

and two competition control treatments). Designed to control woody stems > 1 foot tall and ≤ 1.5 inches in diameter

at breast height (d.b.h.), competition control treatments

consisted of applying herbicide to cut stem surfaces. The

latter designed study variables include time of lifting, shoot

clipping, and four local seed sources (table 1).

In addition to the designed study variables, initial basal stem

diameter (caliper) of each seedling was measured 0.8 inch

above the root collar to 0.004 inch. Initial caliper averaged

0.43 inch and ranged from 0.16 to 0.89 inch. The height of

the dominant woody competitor was measured on a 33.8-

square-foot plot centered at every fourth planted tree location. The dominant competitor species, most abundant

competitor species, and the density of all tree reproduction

≥ 11.8 inches tall also were recorded for each competition

plot. More detailed methods can be found in Spetich and

others (2002).

Through logistic regression, we were able to ascertain important environmental and management variables necessary

to determine planted tree success. The logistic model allows

us to integrate the combined effects of these variables into

Table 1—Designed study variables defined (independent variables)a

Independent

Variable category variable name Variable description

Planting environment Preharvest overstory Three levels: shelterwoods were thinned to 40, 60, or 80 percent

stocking—stocking after stocking before planting. The overstory was removed 3 years after

thinning from below planting.b

(shelterwood creation)

Competition control Three levels: (1) control,d (2) one herbicide treatment (the winter before

treatmentsc spring planting) plus mechanical weeding the winter before overstory

removal, (3) two herbicide treatments. In both number 2 and 3 above,

the first herbicide application (Tordon 101R or Roundup) was applied to

cut stems the winter prior to planting. In number 3 above, the second

herbicide application (Garlon-4) was applied to cut stems the winter

before overstory removal.e

Nursery production Shoot clipping treatments Three levels: (1) shoots not clipped, (2) shoots clipped 8 inches above

the root collar in the fall (November to December) before planting, and

(3) shoots clipped 8 inches above the root collar in the spring (March)

before planting.

Time of lifting Two levels: (1) seedlings lifted in November, and (2) seedlings lifted in

March.

Seed source Four sources: collected from local stands distributed across the Buffalo

Ranger District of the Ozark National Forest

a The dependent variable is the success probability. The success probability is the likelihood that a planted tree will live to attain a favorable

competitive position, i.e., at least 80 percent of the mean height of dominant competitors, at a specified year.

b Overstory trees were defined as stems > 1.5 in. d.b.h. When harvests occurred, the cut surfaces of harvested trees were treated with an

herbicide.

c Competition control treatment refers to stems that were1 foot tall or taller and < 1.5 in. d.b.h. d Stems < 1.5 in. d.b.h. not treated e Overstory shelterwood removal occurred during the winter of 1989–90.
208

a single expression. This expression not only indicates the

likely success of a planted tree (where a successful tree is

one that survives, plus attains and maintains at least 80 percent of the height of dominant competitors) under specific

conditions, but its reciprocal is also a practical tool. Using

these reciprocals, resource managers can determine the

number of trees to plant to achieve a desired future stocking level of oak.

RESULTS AND DISCUSSION

Between year 6 and year 11, mortality of planted oaks

increased by 21 percent. Overall, mortality was highest for

oak seedlings with stems of 0.16 to 0.47 inch caliper. By

year 11, the highest survival rate, 79 percent, was observed

for seedlings with the largest initial caliper (0.67 to 0.87

inch). The survival rate was second highest (74 percent) for

seedlings with calipers between 0.47 to 0.67 inch, and the

lowest survival (67 percent) was recorded for seedlings in

the 0.16- to 0.47-inch class.

We examined the field performance of individual planted

trees and their competitors because competitive position in

relation to surrounding vegetation is an important determinant of seedling survival. Rating of the most significant

competitor results in a competition-centered approach to

tree planting. More than 50 percent of the competition plots

had dominant competitors represented by four species;

sassafras (Sassafras albidum Nutt.), blackgum (Nyssa

sylvatica Marsh.), red maple (Acer rubrum L.), and black

cherry (Prunus serotina Ehrh.) were found in 16.6, 15.3,

12.5, and 10.8 percent of the plots, respectively. The four

most abundant competitors were flowering dogwood

(Cornus florida L.), blackgum, sassafras, and red maple,

representing 23.2, 19.7, 12.7, and 10.7 percent of competitors, respectively (table 2). We further evaluated competitive success and variables important to that success using

logistic regression.

Spetich and others (2002) found that planted tree success

at year 11 increased with initial seedling stem caliper,

decreasing site index, lower shelterwood stocking levels,

increased woody vegetation competition control, and shoot

clipping. Variables that increased success probabilities the

most were percent shelterwood stocking, woody vegetation

competition control, and initial caliper of seedlings. In figure

1A we show the relationship of initial caliper, site index, and

success probability for two woody competition control treatments (based on models by Spetich and others 2002).

Figure 1B illustrates decreased probability of seedling

success when no woody competition control is applied.

Figure 2 illustrates the relationship of percent shelterwood

stocking and initial caliper, where larger caliper and lower

stocking results in a higher probability of seedling success.

The reciprocals of success probabilities provide silviculturally useful estimates of the number of trees that would need

to be planted to yield, on the average, one competitively

successful tree in year 11. In table 3 we present these reciprocals as a practical tool to help managers make underplanting decisions.

Table 2—Percent of competition plotsa in which a given species occurred as the dominant

competitor or most abundant competitor in 1997 (8 years after shelterwood overstory removal)

Dominant competitor Abundant competitor

Densityb (%) Total Densityb (%) Total

Species 40 60 80 40 60 80

 - - - - - - - - - - - - - - - percent - - - - - - - - - - - - - - - -

Sassafras (Sassafras albidum Nutt.) 6.0 3.8 6.7 16.6 8.6 5.9 8.7 12.7

Blackgum (Nyssa sylvatica Marsh.) 3.8 5.6 5.8 15.3 3.9 7.5 8.3 19.7

Red maple (Acer rubrum L.) 3.9 4.9 3.7 12.5 4.8 3.0 4.9 10.7

Black cherry (Prunus serotina Ehrh.) 3.5 3.7 3.6 10.8 4.3 3.6 2.8 4.4

Flowering dogwood (Cornus florida L.) 2.4 2.1 3.2 7.8 1.9 2.2 1.2 23.2

Carolina buckthorn (Rhamnus caroliniana Walt.) 2.9 1.0 2.6 6.5 1.7 1.5 1.3 3.1

Oaksc (Quercus spp.) 2.6 2.3 1.2 6.1 1.9 0.7 0.9 5.4

Hickories (Carya spp.) 2.5 1.0 1.2 4.7 1.7 0.8 1.0 3.4

Eastern hophornbeam (Ostrya virginiana Mill.) 0.7 2.8 0.2 3.7 1.6 0.6 1.0 2.8

Sumac (Rhus spp.) 1.9 0.4 0.6 2.8 0.8 1.9 0.1 3.4

Sugar maple (Acer saccharum Marsh.) 0.4 0.6 1.3 2.2 0.3 0.6 1.3 2.1

Paw paw (Asimina triloba (L.) Dun.) 1.3 0.8 0.0 2.0 1.1 1.1 0.0 2.1

White ash (Fraxinus Americana L.) 0.3 1.0 0.7 1.9 0.4 1.3 0.4 2.0

Witch hazel (Hamamelis virginiana L.) 0.3 0.6 0.4 1.3 0.3 0.9 0.4 1.6

Otherd 2.0 2.1 1.6 5.7 1.6 1.2 0.7 3.4

a Based on 1,027 plots, 33.8-ft2

 in size where woody competitors occurred. b Represents percent stocking in the shelterwood phase.

c Includes white oak, northern red oak, and black oaks.

d Species that represent < 1.0 percent of the total and include American elm, American beech, black locust,

serviceberry, wild plum, redbud, hackberry, mulberry, cucumber tree, Ozark chinkapin, black walnut, umbrella

magnolia, eastern redcedar, and devils walkingstick.
209

Figure 1—Success probability by initial seedling caliper and site index (SI) for top-clipped trees planted under shelterwoods with 40 to 60

percent stocking. (A) Two competition control treatments. (B) No competition control (based on Spetich and others 2002).

Figure 2—Success probability by initial seedling caliper and

percent shelterwood stocking (based on Spetich and others 2002).

(A) (B)

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Initial seedling caliper (inches)

Success probability

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Initial seedling caliper (inches)

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

Success probability

SI 60

SI 69

SI 79

SI 60

SI 69

SI 79

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

Success probability

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Initial seedling caliper (inches)

40 – 60 stocking 

80 stocking

Percent

This study was not installed under oak decline conditions,

so the recommendations below are best applied to healthy

stands. However, reductions in stocking levels in stands

affected by oak decline can approximate reductions in

stocking imposed by a harvest. Following the recommendations below could result in similar oak underplanting

success in these stands also.

RECOMMENDATIONS

To take maximum advantage of investments in site preparation, oaks could be planted at densities within treated areas

that assure those areas are fully occupied at maturity, where

“fully occupied” is the desired oak stocking at maturity necessary to meet management goals. Estimated dominance

probabilities can facilitate decisions on an appropriate

planting density. A reasonable goal might be at least 100

competitively successful trees per acre at stand age 11.

This density would allow for some losses to mortality and

suppression beyond 11 years, yet provide reasonable

assurance that the oaks, by themselves, would ultimately

occupy most of the growing space within treated areas.

Using this method, the high per acre planting and site

preparation costs associated with the planted area could be

spread across the entire stand. For example, limiting planting to 20 percent of stand area would effectively reduce

costs of $400 per acre actually planted (nursery stock plus

planting plus site preparation costs) to $80 per acre prorated

across the entire stand. Where possible, the unplanted

portion of the stand (80 percent) could be regenerated

naturally. Regeneration would be deemed successful if the
210

Table 3—Number of trees to plant in order to obtain one successful tree

in year 11a

Woody competition controlb

None Oncec Twice

Densityd (percent)

Calipere 40 – 60 80 40 – 60 80 40 – 60 80

inches - - - - - - - - - - - - - - - - - - - - percent - - - - - - - - - - - - - - - - - - - -

Site index 60 feet

0.16 126.0 259.8 67.7 139.1 33.9 69.1

0.24 21.9 44.3 12.2 24.1 6.5 12.4

0.32 9.6 18.7 5.6 10.4 3.3 5.7

0.39 6.0 11.4 3.7 6.5 2.3 3.7

0.47 4.5 8.2 2.9 4.9 1.9 2.9

0.55 3.7 6.6 2.4 4.0 1.7 2.5

0.63 3.2 5.6 2.2 3.5 1.6 2.2

0.71 2.9 5.0 2.0 3.1 1.5 2.1

0.79 2.7 4.5 1.9 2.9 1.5 1.9

0.87 2.6 4.2 1.8 2.7 1.4 1.8

Site index 69 feet

0.16 306.5 633.7 164.0 338.6 81.4 167.5

0.24 38.9 79.6 21.2 42.9 11.0 21.7

0.32 14.4 28.7 8.1 15.8 4.5 8.3

0.39 8.2 15.8 4.8 8.9 2.9 4.9

0.47 5.7 10.8 3.5 6.2 2.2 3.6

0.55 4.5 8.2 2.9 4.9 1.9 2.9

0.63 3.8 6.8 2.5 4.1 1.7 2.5

0.71 3.4 5.9 2.3 3.6 1.6 2.3

0.79 3.0 5.2 2.1 3.3 1.5 2.1

0.87 2.8 4.8 2.0 3.0 1.5 2.0

Site index 79 feet

0.16 748.0 1,547.9 399.6 826.5 197.6 408.1

0.24 69.9 143.6 37.7 77.1 19.1 38.5

0.32 21.9 44.3 12.2 24.1 6.5 12.4

0.39 11.2 22.2 6.5 12.3 3.7 6.6

0.47 7.3 14.1 4.4 8.0 2.7 4.5

0.55 5.5 10.4 3.4 6.0 2.2 3.5

0.63 4.5 8.2 2.9 4.9 1.9 2.9

0.71 3.9 6.9 2.5 4.2 1.8 2.6

0.79 3.4 6.1 2.3 3.7 1.6 2.3

0.87 3.1 5.4 2.1 3.4 1.6 2.2

a (Eight years after shelterwood overstoryremoval): calculated by dividing 1 by the

success probability. To determine the number of trees per acre to plant, multiply the

number of trees per acre that you would like to have at year 11 (11 years after

planting) by a number below. To locate this number use the one where your specific

site index, competition control plans, and overstory density intersect with the caliper of

trees you wish to plant.

b In all three cases of none, competition control once and competition control twice:

stems > 1.5 inches d.b.h. were cut with the overstory and treated with herbicide.

c Includes a mechanical weeding before shelterwood removal.

d Represents percent stocking in the shelterwood phase.

e This is the initial basal stem diameter of seedlings measured 0.8 inches above the

root collar.

Source: Spetich and others 2002.
211

combined planted and natural reproduction produces an

adequate standwide representation of oak and other acceptable growing stock. Adequacy and acceptable growing

stock would be defined by the management goals; e.g.,

wildlife hard mast needs, species diversity, forest restoration, maintenance of this keystone species, or any reasonable management objective. Specific steps to follow to

optimize planted seedling success include:

1. Select upland sites within the site index range of 60 to

79 feet for red oaks.

2. Create a shelterwood by reducing overstory density to

40 to 60 percent stocking by thinning from below; i.e.,

concentrating removals on subcanopy trees down to 1.5

inches d.b.h. Treat the cut surface of cut stems of

competitors with an effective herbicide.

3. Before planting, cut all competing woody plants 1 foot or

taller and 1.5 inches or less d.b.h., then apply an effective herbicide to the cut surface.

4. Plant 2-year-old undercut seedlings with clipped tops

that average at least 0.5 inch in caliper measured 0.8

inch above the root collar (seedlings should be grown

from a local seed source).

5. Apply a second competition control treatment (herbicide)

before shelterwood removal.

6. Remove the shelterwood three growing seasons after

planting. Treat the cut surface of cut stems of competitors with an effective herbicide.

ACKNOWLEDGMENTS

We extend our appreciation to the field technicians who

installed and measured this study: Richard Chaney, Jim

Whiteside, Clare Bond Whiteside, Greg Polus, Arvie

Heydenriech, and Jesse Swaford. We thank Ozark National

Forest personnel for assistance with stand selection and

study installation. Thanks to Dr. James M. Guldin and Dr.

Eric Heitzman for reviewing this manuscript and to Betsy L.

Spetich for editorial guidance.

This publication reports research involving herbicides. It

does not contain recommendations for their use, nor does it

imply that the uses discussed here have been registered.

All uses of herbicides must be registered by appropriate

State and/or Federal Agencies before they can be

recommended.

LITERATURE CITED

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performance of underplanted red oak (Quercus rubra L.) in

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Graney, D.L. 1977. Site index predictions for red oaks and white

oaks in the Boston Mountains of Arkansas. Res. Pap. SO-139.

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

Southern Forest Experiment Station. 9 p.

Harlow, R.F. 1975. Deer foods during years of oak mast abundance

and scarcity. Journal of Wildlife Management. 3: 330-336.

McShea, W.J.; Schwede, G. 1993. Variable acorn crops: responses

of white-tailed deer and other mast consumers. Journal of

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Merritt, C. 1980. The central region. In: Barrett, J.W., ed. Regional

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Nixon, C.M.; McClain, M.W.; Donohoe, R.W. 1975. Effects of

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the Lake States, USA. Annaels des Sciences Foresties. 50:

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Southern Appalachians. Proceedings of the annual conference

of the Southeastern Association of Fish and Wildlife Agencies.

44: 142-154.
212

INTRODUCTION

The wood products that can be produced from trees of the

upland forest of Arkansas are discussed in this paper. These

products depend on several factors such as species and

quality. Therefore, the different types of wood that are present will be discussed as well as how growth rate affects

the quality of each type. Also discussed will be how tree

form affects wood quality. Finally, the different types of

products will be presented.

WOOD TYPES

The upland forest is mainly a hardwood forest. Hardwoods

can be classified into two types: ring-porous and diffuseporous. Ring-porous woods include species such as the

oaks, hickories, and ashes. These species are the most

desirable in the forest. The diffuse-porous woods include

red maple and blackgum. Diffuse-porous woods are usually

less desirable and used in products of lesser value. Some

of these woods are referred to as soft hardwoods and are

used in place of southern pine in some products. There are

some softwoods such as shortleaf pine on some south

facing slopes and eastern red cedar present in the upland

forests.

EFFECTS OF GROWTH RATE

The effect of growth rate on the quality of wood depends on

the type of wood under consideration. With ring-porous

woods, the quality improves as the growth rate increases.

This is because of the structure of the growth rings. In ringporous hardwoods, three to five rows (depending on species)

of large pores or vessels are laid down at the beginning of

the growing season and the remainder of the ring is made

up of fibers and small vessels. No matter what the size of

the growth ring is, the tree will always lay down the same

number of rows of large vessels. Any extra growth or lack of

growth will appear in the amount of fibers produced. Therefore, the faster the growth is, the stronger and the more

appealing to the eye the wood is.

Back when the chip mills were operating in the Northwest

part of the state, I was contacted by one mill manager to

check the quality of their chips because the Japanese

customers were refusing to pay the agreed upon price. The

wood samples I examined had very small growth rings made

up of mainly earlywood vessels and very few fibers. I told

the manager that I could see why the Japanese were

saying that they were realizing twenty-five percent less pulp

per ton of chips as compared to chips procured from east of

the Mississippi. It is interesting to note that there were

several groups that insisted that those trees should not be

cut but allowed to grow larger. Once larger, they would

provide high quality hardwood lumber. Sorry, but with the

growing conditions that those trees were experiencing, they

would never produce anything but very low quality wood.

With diffuse-porous hardwoods, the vessels are much

smaller and located throughout the growth ring. Because of

this, there is no correlation between growth rate and wood

properties or quality for diffuse-porous woods. The wood is

basically the same whether fast grown or slow grown.

Softwoods such as eastern red cedar, hemlock, spruce, fir,

etc., show the same relationship as diffuse-porous hardwoods. Softwoods with abrupt latewood such as southern

pine and Douglas-fir appear to have lower quality wood

with an increase in growth rate. Some researchers believe

that this is the effect of age, not growth rate.

EFFECTS OF TREE FORM

Besides the growth rate, a tree’s form greatly affects the

quantity and quality of the products that can be produced.

It is desirable that each tree be straight. When the bole

deviates from straight, solid wood products will have cross

grain, which will result in warping and splitting when dried.

The more severe the sweep (curve in the bole), the shorter

the logs have to be cut to minimize the effects of cross

grain. Trees with crook will have portions bucked out and

left in the forest.

Leaning trees are most undesirable. All trees want to be

upright. If hardwood trees are leaning, they will produce

tension wood on the upper side of the bole, which will force

the bole into an upright position. Tension wood is bad from

the start. It causes problems with machining, drying, finishing, and pulping. The chemical composition and cell structure of tension wood is different from normal wood.

The best trees have circular cross sections with the pith in

the center. When a tree has a tear drop or oval cross

section, the pith is located toward the smaller side and the

quality of the solid wood products it produces is lower.

There are two main reasons for non-circular cross sections.

First, tension wood will cause the tree to produce a wide

WOOD PRODUCTS BY SPECIES AND QUALITY IN UPLAND FORESTS

David W. Patterson1

1 Research Professor, Arkansas Forest Resources Center, Monticello, AR 71656.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Products that can be produced from an upland forest depend on the species and quality of the trees present.

Quality depends on growth rate and tree form. These variables are discussed as well as the products that can be

produced such as veneer and plywood, grade lumber, handle stock, pallet stock, cross ties, and industrial lumber.
213

growth ring on the upper side and a very narrow ring on the

lower side. The undesirability of tension wood has already

been mentioned. Second, when there is competition on two

or three sides of the tree, the crown will grow toward the

sunlight and the bole will grow more on that side.

Limbs result in knots in solid wood products manufactured

from the tree. Knots are the single most important qualitylimiting defect and they grow from the pith outward. The

best quality trees self-prune early and quickly produce a

clear surface for most of the bole’s length. A downside with

hardwoods is that in many species, if the sunlight reaches

the bole, new limbs (epicormic branching) will form at the

cambium. It is sad to see a prime grade tree suddenly

sprouting new branches on its lower bole and thereby,

substantially lowering the grade. Therefore, one must be

careful not to cause epicormic branching when thinning a

hardwood stand to increase growth rate.

The hardwood tree grades for factory grade lumber are an

example of how tree form affects the quality. The first limiting factor is size: grade 1 trees must be at least 16 inches

in diameter at breast height (d.b.h.), grade 2 trees must be

13 inches in d.b.h., and grade 3 trees must be 10 inches in

d.b.h. The second limiting factor is the amount of clear

material in the third best face. Defects such as limbs, bird

pecks, whorls, bulges, cracks, etc. limit the clear spaces.

The next limiting factor is the amount of sweep: nine percent for grade 1, 15 percent for grade 2, and 50 percent for

grade 3 trees.

WOOD PRODUCTS

The most valuable product from the hardwood forest is

veneer. Most hardwood veneers are sliced and not peeled.

Grain orientation is critical to achieve the desired visual

effect. The logs are sawn to produce flitches that have the

desired grain orientation on their face. The flitch is attached

to a veneer slicer that slices veneers with the same grain

pattern. One can see that in order to obtain the desired

veneer, the process must start with logs that are large,

straight, circular in cross section, and clear of knots and

other defects. Veneers from highly valued species are used

in the production of decorative hardwood plywood, furniture, cabinets, paneling, etc. Veneers from lower valued

species such as red maple, blackgum, sweetgum, and

yellow-poplar are used for inner plies and back plies for

products where only the face shows.

Some of the soft hardwoods are peeled and used with

softwoods to make structural plywood. I have visited some

plywood plants in North Carolina where red maple, sweetgum and yellow-poplar are used with southern pine to make

plywood. Since defects and/or patches are permitted, the

best quality logs are not required.

The most common use for quality logs is factory grade

lumber. Since you do not need perfect logs to make solid

wood parts, the price of factory grade logs is lower than for

veneer grade logs. Many of the big sawmills do pay according to the log grade and not just by volume or weight. The

price of the resulting lumber varies greatly by grade as well.

The difference between the price of FAS (top grade) and

No. 3 common (lowest grade) lumber could be a factor of

seven or eight for red oak and other valued species. Grade

lumber can be used to make furniture, cabinets, paneling,

flooring, mouldings, and architectural woodwork. It is easy

to sell the high grade lumber but somewhat difficult to sell

the low-grade lumber. All logs, regardless of grade, have

some low-grade lumber in them.

Quality hickory and ash logs can be used to produce handle

stock. Hickory is used for handles of striking tools such as

hammers, picks, and axes while ash is used for long handles

such as hoes, shovels, and rakes. Again, the faster the

growth rate, the better the handles are from these species.

The number one user of hardwood lumber in the United

States is the pallet industry. Approximately five billion board

feet of hardwood lumber or almost 40 percent of the total

hardwood production are used annually in the production of

pallets. Here strength and stiffness are the deciding factors

and not appearance. Sagging deck boards cause problems

when inserting the forks of a forklift through the pallet.

Cross ties are another market for lower grade logs. These

logs must be big enough so that there is no wane or other

defects in the bearing plate area. The logs need to be

straight so that the resulting ties will remain straight after

drying.

Industrial lumber includes board road, sewer boards and

dunnage. Board road is a 3-layer, reversing herringbone

roadway for heavy equipment going in and out at an oildrilling site. It minimizes the land disturbance. The law

requires that any ditch over four feet deep must be bulkheaded before anyone can work in the ditch. Sewer boards

are used for that purpose. Dunnage is used to insure that a

cargo item does not shift or move while being transported

by rail or ship.

In other parts of the country, soft hardwoods are used to

make oriented strand board (OSB). The original OSB mills

were in the Lake States using aspen. If the red oak borer

does kill most of the oaks in the forest, red maple and other

soft hardwoods may become the dominate species. But,

OSB plants cost a lot of money.

The hardwood forest can also be used as a source of raw

material for the pulp and paper industry. But even the pulp

and paper industry requires a certain level of quality in its

wood resource. Hardwood pulp is generally used to make

high end paper such as coated and glossy paper used in

magazines while softwood pulp is generally used for newsprint and paper bags.

Fuel is the number one use of wood in the world. Home

fireplaces and stoves along with industrial energy uses can

remove a lot of low-grade trees from the forest. Transportation costs may be the limiting factor in Arkansas.

The sale of products (wood, water, wildlife, etc.) offset the

costs of forestry operations in the upland forest. This paper

has discussed how the growth of the trees affects the quality

and types of wood products that can be produced from the

upland forests. This information should aid the forester in

making management decisions on upland forests.
214
215

Oak Decline
216
217

INTRODUCTION

Oak decline is a complex disease with no single cause

(Manion 1981, Wargo and others 1983). It is characterized

primarily by progressive branch dieback and mortality of

oaks growing in the overstory. Dieback and mortality are

generally slow and can occur over several years. However,

sudden mortality and rapid dieback can occur as well. A

number of interacting factors contribute to decline—stand,

site, abiotic and biotic factors (fig. 1). Oak decline is best

conceptualized, according to Manion (1991), by categorizing factors into predisposing, inciting and contributing

groups (fig. 2). Stands are predisposed to decline by such

factors as relatively advanced physiologic age (Hyink and

Zedaker 1987, Oak and others 1996), shallow, rocky soils,

ridgetop and upper slope locations, dense oak stocking,

and previous climate (e.g., severe regional droughts during

the 1950’s, 1980’s (Tainter and others 1990)). Decline is

incited by factors such as short-term, acute drought or insect

defoliation. Secondary insects and pathogens are contributing factors that further stress trees and ultimately lead to

mortality. Some contributing factors are: armillaria root rot

(Armillaria [Fr.:Fr.] spp.), two-lined chestnut borer (Agrilus

OAK DECLINE AND RED OAK BORER IN

THE INTERIOR HIGHLANDS OF ARKANSAS AND MISSOURI:

NATURAL PHENOMENA, SEVERE OCCURRENCES

Dale A. Starkey, Forrest Oliveria, Alexander Mangini, and Manfred Mielke1

1 Plant Pathologist, Field Office Representative, and Entomologist, USDA Forest Service, Southern Region, State & Private Forestry, Forest

Health Protection, Pineville, LA 71360; and Plant Pathologist, USDA Forest Service, Northeast Area, State & Private Forestry, Forest Health

Protection, St. Paul, MN 55108, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Oak decline is a complex disease resulting in dieback and mortality of oaks. A number of factors are involved

and can be classified as predisposing, inciting, or contributing, according to their roles. Decline events have been noted

repeatedly during the past century in the eastern U.S. A severe episode of oak decline is occurring in the Interior

Highlands region of Arkansas and Missouri. It includes an unprecedented epidemic of red oak borer (Enaphalodes rufulus

Haldeman). Mortality and dieback of northern red, (Quercus rubra L.), black, (Q. velutina Lam.), scarlet (Q. coccinea

Muenchh.) and southern red (Q. falcate Michx.) oaks on thousands of acres of Interior Highland forest became evident in

1999 following 2 years of severe regional drought. A third year of drought in 2000 greatly exacerbated the problem and

mortality and dieback have continued through 2002. Aerial sketch-map surveys of portions of the Ozark National Forest in

Arkansas estimated that up to 300,000 acres are severely affected. Data from ground evaluations during 1999-2000 on

the Ozark and Mark Twain National Forests (Missouri) showed an average of 15-28 percent of red oak basal area per

acre is dead in affected stands. An additional 2-14 percent had severe dieback. Data from 2000 and 2002 plot remeasurements on the Ozark National Forest showed that mortality and dieback continued, especially in red oaks where

an additional 16-20 percent of basal area per acre died over three years. However, many stands with high basal areas of

red oaks have experienced nearly 100 percent mortality. Red oak borer attacks were noted only on red oak species.

Greater than 10 old and new red oak borer attacks on the lower bole were noted on over 18 and 23 percent, respectively,

of red oak basal area per acre in damaged stands on the Ozark National Forest in 1999. On the Mark Twain National

Forest in 2000, 54 percent of the red oak basal area per acre had greater than 10 attacks.

Figure 1—Causal factors of oak decline organized by type. Figure 2—Causal factors of oak decline organized by their function

in the decline syndrome.

Abiotic Factors 

 Climatic trends or past events 

 Drought 

Biotic Factors 

 Boring insects 

 Canker fungi 

 Defoliating insects 

 Root disease 

OAK 

DECLINE

Site/stand Factors 

 Density/competition 

 Physiological age 

 Soil depth/texture/fertility 

 Species/genotypes 

 Topography 

Anthropogenic Factors 

 Stand disturbance

 Frost

Predisposing Factors 

 Climatic trends or past events 

 Density/competition 

 Physiological age 

 Soil depth/texture/fertility 

 Species/genotypes 

 Topography 

 

Inciting Factors 

 Drought 

 Defoliating insects 

 Frost 

 Stand disturbance 

OAK 

DECLINE

Contributing Factors 

 Boring insects 

 Canker fungi 

 Root disease 
218

bilineatus Weber), red oak borer (ROB, Enaphalodes rufulus

Haldeman) and hypoxylon canker (Hypoxylon atropunctatum

[Schwein.:Fr.] Cooke). Species in the red oak group (northern red oak, Quercus rubra L.; black oak, Q. velutina Lam.;

scarlet oak, Q. coccinea Muenchh.; and southern red oak,

Q. falcate Michx.) are affected more quickly and severely

than those in the white oak group (white oak, Q. alba L.;

post oak, Q. stellata Wangenh.; chestnut oak, Q. prinus L.;

Starkey and others 1989). Other species are affected as

well, to varying degrees, but generally much less severely

than oaks.

Oak decline or similar events have been described in most

eastern states since the mid-1800’s (Ammon and others

1989, Hopkins 1902, Millers and others 1988). Events have

been documented in the Ozark Highlands of Arkansas and

Missouri in the early and mid-1980’s (Bassett and others

1982, Lewis 1981, Mistretta and others 1981, Rhodes and

Tainter 1980, Starkey and others 1989, Yeiser and Burnett

1982). The Highlands area has an abundance of older oakhickory forest types on sites of low to moderate productivity

that are susceptible to decline. Stands with these characteristics seem particularly prevalent on national forests. In

1999, mortality and dieback of red oaks became abundant

on the Ozark and Ouachita National Forests in Arkansas,

and the Mark Twain National Forest in Missouri. Decline

and mortality were accompanied by unusually heavy attacks

by the ROB.

ROB’s have generally been considered to cause degrade in

red oaks due to the galleries they excavate in the wood

(Donley and Acciavatti 1980, Solomon 1995) rather than

causing tree mortality. They have a two-year life cycle with

adult emergence mostly synchronous in odd-numbered

years. Emergence peaks in mid-summer and adults lay

eggs on red oak bark, particularly under lichens. After the

eggs hatch, young larvae bore through the bark and begin

to feed in the inner bark and eventually excavate a small

area, killing the cambium layer in an area usually not exceeding about 4 square inches. During the second season, larvae

begin to bore into the wood of the tree and turn upward until

the larvae reach mature size (about 0.5 inches in diameter).

Frass and sawdust are ejected from the galleries as they are

excavated and continually enlarged to accommodate the

growing larvae. Borers pupate within the gallery and adults

exit the same entrance hole they created, leaving an oval

emergence hole. Casual tree examinations and dissections

on the Ozark National Forest have documented high borer

populations and adult emergence in 1999 and 2001. Most

foresters, entomologists and pest management specialists

who have viewed the problem indicate they have never

before seen an outbreak of such magnitude. Preliminary,

detailed tree dissections have documented hundreds of old

and new attacks on individual red oaks (Personal communication. Dr. Fred Stephen. 2001. Professor, University of

Arkansas, 317 Agriculture Bldg., Fayetteville, AR 72701),

whereas the highest previously published rates are about

71 attacks per tree (Hay 1974).

Aerial sketch-map surveys were conducted to estimate the

extent and severity of the problem, and to guide field survey

work. Ground evaluations were conducted in Arkansas

(Starkey and others 2000) and Missouri (Mielke and others

2000) to determine the extent, severity and cause of the

recent dieback/mortality and to document its association

with ROB attacks. Revisits to surveyed stands on the Ozark

National Forest were made in 2000 and 2002 in order to

monitor progress of the decline event.

METHODS/ACTIVITIES

An evaluation was conducted in late summer, 1999 on the

Pleasant Hill Ranger District of the Ozark National Forest

north of Clarksville, Arkansas (Starkey and others 2000).

Ranger District personnel conducted an aerial sketch-map

survey and delineated large areas of forest that fell into 3

strata of damage: severe (hardwood stands within the gross

Table 1—Data collected on trees in sample stands, Ozark and Mark Twain National Forests, 1999–2002

Variable Description

Species Appropriate species code

D.b.h. Diameter at breast height to the nearest 0.1 inches

Crown class 4 = dominant, 3 = codominant, 2 = intermediate, 1 = suppressed

Crown condition 0 = healthy, normal crown

1 = slight dieback: <1/3 of crown

2 = moderate dieback: 1/3-2/3 of crown

3 = severe dieback: >2/3 of crown

4 = dead, died this year: fine twigs present, brown leaves may be present, little or no bark sloughing

5 = dead, died 2–4 years ago: no fine twigs present, bark sloughing, sapwood rot obvious

6 = dead, died 4 or more year ago: stubby branches, extensive bark sloughing, extensive sapwood rot

ROB-OLD Red oak borer attacks from previous years; number of old attacks on the lower 8 feet of bole: 0 = none,

1 = 1–10, 2 = 11–20, 3 = 21–30, etc.

ROB-NEW Red oak borer attacks from current year; number of new attacks on the lower 8 feet of bole: 0 = none,

1 = 1–10, 2 = 11–20, 3 = 21–30, etc.

ROB = red oak borer.
219

forest area with a visual estimate of 75+ percent of crown

cover affected [mortality, dieback or dead foliage]), moderate (50-75 percent of crown cover affected) and slight (<50

percent crown cover affected). Six sawtimber-sized oakhickory stands with reasonably good road access were

selected at random in each of the damage strata for ground

survey. Sample stands were surveyed using 5 basal-areafactor 10 prism plots arrayed on a transect through the main

part of the stand at a minimum spacing of 150-200 feet. For

sample trees >4 inches in diameter at breast height (d.b.h.),

data included species, d.b.h., crown class, crown condition,

number of old ROB attacks and number of new ROB attacks

(table 1). In each stand, plot 1 was marked and a GPS

(global positioning system) reading taken. These plots were

relocated and re-measured in 2000 and 2002 to monitor the

long-term progress of decline/mortality.

A similar ground survey was done on the Potosi and Salem

Ranger Districts of the Mark Twain National Forest in

Missouri in 2000 (Mielke 2000). Five affected stands were

sampled on the Potosi Ranger District and 6 on the Salem.

Stands were sampled in the manner described above except

that old and new ROB attacks were not differentiated.

A more extensive aerial sketchmapping survey was performed

in 2001 over the entire main division of the Ozark National

Forest (Boston Mountain, Pleasant Hill, Bayou, and Buffalo

Ranger Districts) by Forest personnel. Areas with light,

moderate, and severe activity were delineated as in 1999.

RESULTS

Aerial sketchmapping of the Pleasant Hill Ranger District in

1999 delineated approximately 19,000 acres (16 percent)

as severely affected, 24,000 (20 percent) as moderately

Figure 3—Percentage of basal area per acre by stratum and crown

condition, Ozark National Forest, 1999.

Figure 4—Percentage of basal area per acre by species group and

crown condition, Ozark National Forest, 1999.

affected and 75,000 acres (64 percent) as slightly affected.

Ground sampling of the 54 plots yielded a sample tree

population of 864 trees. Red oaks comprised 46 percent of

the basal area, white oaks 28 percent, and other species

26 percent. Ground sampling confirmed the relative damage

classification during aerial sketchmapping. Mortality and

dieback of all species were most prevalent in the severe

stratum where 24 percent of the basal area per acre had

moderate to severe dieback or was dead fig. 3). Damage

was less in the moderate (12 percent) and light (8 percent)

strata. Comparing species groups, red oaks were more

severely affected across all strata than white oaks or other

species—22 percent of basal area per acre with moderate

to severe dieback or dead compared to 8 and 7 percent,

respectively (fig. 4). Red oaks in the severe stratum had the

most damage—35 percent of basal area per acre with

moderate to severe dieback or dead and less in the moderate (19 percent) and light (9 percent) strata (fig. 5).

Enumeration and characterization of ROB attack sites on

the lower 8 feet of bole represent just a rough (and probably very conservative) estimate of infestation levels since

they are difficult to tally accurately and quickly. Nonetheless, they provide a useful picture of the relative extent and

nature of borer attacks. ROB attacks (both old and new)

were noted only on red oak species—54 percent of basal

area per acre had 1 or more old attacks and 45 percent had

1 or more new attacks (fig. 6). Both old and new ROB attacks

on red oaks were most prevalent in the severe stratum,

followed by the moderate and slight strata (figs. 7 and 8).

Old ROB attacks on red oaks were most prevalent on dead

trees (fig. 9). New ROB attacks, however, were most prevalent on moderate/severe red oaks followed by dead, then

healthy/slight red oaks (fig. 10).

Figure 5—Percentage of basal area per acre of red oaks by

stratum and crown condition, Ozark National Forest, 1999.

Figure 6—Percentage of red oak basal area per acre with old and

new red oak borer attacks, Ozark National Forest, 1999.

0%

20%

40%

60%

80%

100%

Light Moderate Severe

Damage Stratum

Dead

Moderate/severe

Healthy/slight

0%

20%

40%

60%

80%

100%

Red oaks White oaks Other species

Species Group

Dead

Moderate/severe

Healthy/slight

0%

20%

40%

60%

80%

100%

Light Moderate Severe

Damage Stratum

Dead

Moderate/severe

Healthy/slight

0%

20%

40%

60%

80%

100%

Old New

Red Oak Borer Attacks

21 or more

11-20

1-10

0 attacks
220

Sampling on the Mark Twain National Forest in 2000 produced similar results with about 20 percent of scarlet and

black oak basal area per acre dead, and 11 percent with

moderate to severe decline (fig. 11). As on the Ozark

National Forest, white oaks were much less affected. In

addition, ROB attacks were present on most red oaks—

almost 45 percent of basal area per acre had over 10

attacks (fig. 12).

Data from the re-measured plots on the Ozark National

Forest showed that dieback and mortality continued in 2000

and 2002. In 2000, newly killed basal area accrued mostly

in red oaks across all strata—an increase of 5-6 percent

(table 2). Moderate/severe dieback increased most in white

oaks in the light stratum (3.6 percent), but also increased in

both white and red oaks in the light and moderate strata. In

2002 red oak mortality increased 11-14 percent in the

moderate and severe strata (table 3). Thus, over the 3-year

period, red oak mortality increased 7-20 percent while white

oak and other species increases were only 2-7 percent and

2-8 percent (table 4).

Figure 7—Percentage of red oak basal area per acre with old red

oak borer attacks by stratum, Ozark National Forest, 1999.

Figure 8—Percentage of red oak basal area per acre with new red

oak borer attacks by stratum, Ozark National Forest, 1999.

Figure 9—Percentage of red oak basal area per acre with old red

oak borer attacks by crown condition, Ozark National Forest, 1999.

Figure 10—Percentage of red oak basal area per acre with new red

oak borer attacks by crown condition, Ozark National Forest, 1999.

Figure 11—Percentage of basal area per acre by species group

and crown condition for the Mark Twain National Forest.

Figure 12—Percentage of red oak basal area per acre with red oak

borer attacks on the Mark Twain National Forest.

Table 2—Estimated change (1999–2000) in percent of

basal area per acre (trees >4 inches d.b.h.) by crown

condition, species group, and damage strata on the

Ozark National Forest

 Stratum

Crown condition Light Moderate Severe

Red oaks

Healthy and slight -7.3 -7.9 -5.4

Moderate and severe +1.8 +1.5 0

Dead +5.5 +6.3 +5.4

White oaks

Healthy and slight -5.4 -1.6 0

Moderate and severe +3.6 +1.6 0

Dead +1.8 0 0

Other species

Healthy and slight -1.8 0 0

Moderate and severe +1.8 0 0

Dead 0 0 +1.8

0%

20%

40%

60%

80%

100%

Light Moderate Severe

Damage Stratum

21 or more

11-20

1-10

0 attacks

0%

20%

40%

60%

80%

100%

Light Moderate Severe

Damage Stratum

21 or more

11-20

1-10

0 attacks

0%

20%

40%

60%

80%

100%

Healthy/Slight Moderate/Severe Dead

Cown Condition

21 or more

11-20

1-10

0 attacks

0%

20%

40%

60%

80%

100%

Healthy/Slight Moderate/Severe Dead

Cown Condition

21 or more

11-20

1-10

0 attacks

0%

20%

40%

60%

80%

100%

Red oaks White oaks

Species Group

Dead

Moderate/severe

Healthy/slight

27%

39% 17%

17%

21 or more

11-20

1-10

0 attacks
221

The most recent (2001) aerial sketchmapping over the entire

main division of the Ozark National Forest estimated that

over 600,000 gross acres had moderate to severe damage

from oak decline, with 300,000 of that in the severe category.

DISCUSSION

Clearly, the current oak decline episode in Arkansas and

Missouri is severe and unique in relation to its association

with such extremely high populations of ROB. The decline

episode will run its course, probably abating with the return

of more normal rainfall patterns. However, forest composition and structure will be severely impacted for years to

come. Oaks generally, and the red oak group particularly,

will be a smaller component of the new forest taking shape,

and given the prevailing low-disturbance/fire suppression

regime, will most likely be replaced by shade-tolerant hardwood trees. The course of the ROB epidemic is uncertain.

The reduction in host material will probably result in a

return to a more historically normal population. The effects

of these phenomena are currently being felt by the woodusing industry in the Ozark Highlands. Effects on wildlife,

recreation, or other resources are no doubt occurring as

well. These remain to be well documented.

ACKNOWLEDGMENTS

Special thanks are offered to Ozark and Mark Twain National

Forest personnel for conducting aerial sketchmapping

surveys and providing invaluable assistance for ground

survey activities.

LITERATURE CITED

Ammon, V.; Nebeker, T.E.; Filer, T.H. [and others]. 1989. Oak

decline. Tech. Bull. 161. Mississippi State, MS: Mississippi

Agricultural & Forestry Experiment Station. 15 p.

Bassett, E.N.; Fenn, P.; Mead, M.A. 1982. Drought-related oak

mortality and incidence of Hypoxylon canker. Arkansas Farm

Research 31(1): 8.

Donley, D.E.; Acciavatti, R.E. 1980. Red oak borer. Forest Insect

and Disease Leaflet 163. Washington, D.C.: U. S. Department

of Agriculture, Forest Service. 7 p.

Hay, C.J. 1974. Survival and mortality of red oak borer larvae on

black, scarlet, and northern red oak in eastern Kentucky.

Annals of the Entomological Society of America 67: 981-986.

Hopkins, A.D. 1902. On the study of forest entomology in America.

U.S. Department of Agriculture, Division of Entomology bull.

37: 5-28.

Hyink, D.M.; Zedaker, S.M. 1987. Stand dynamics and the evaluation of forest decline. Tree Physiology 3: 17-26.

Lewis, R., Jr. 1981. Hypoxylon spp., Ganoderma lucidum and

Agrilus bilineatus in association with drought related oak

mortality in the South. (Abstr.) Phytopathology 71(8): 890.

Manion, P.D. 1981. Tree disease concepts. Prentice Hall, Inc.

Englewood Cliffs, NJ. 399 p.

Mielke, M. 2000. Forest health evaluation of oak mortality and

decline on the Mark Twain National Forest, 2000. St. Paul, MN:

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

Area, State & Private Forestry, Forest Health Protection, St.

Paul Field Office. 10 p.

Millers, I.; Shriner, D.S.; Rizzo, D. 1988. History of hardwood

decline in the Eastern United States. Gen. Tech. Rep. NE-126.

Broomall, PA: U.S. Department of Agriculture, Forest Service,

Northeastern Forest Experiment Station. 75 p.

Mistretta, P.A.; Affeltranger, C.E.; Starkey, D.A. [and others]. 1981.

Evaluation of oak mortality on the Ozark National Forest,

Arkansas, 1981. Rep. No. 81-2-26. Alexandria, LA: U.S.

Department of Agriculture, Forest Service, Southeastern Area.

15 p.

Oak, S.; Tainter, F.; Williams, J.; Starkey, D. 1996. Oak decline risk

rating for the Southeastern United States. Ann. Sci. For.

53: 721-730.

Rhodes, J.D.; Tainter, F.H. 1980. Precipitation extremes and tree

growth. Arkansas Farm Research. 29(6): 12.

Solomon, J.D. 1995. Guide to insect borers in North American

broadleaf trees and shrubs. Ag. Hdbk. AH-06. Washington,

D.C.: U.S. Department of Agriculture, Forest Service. 735 p.

Table 3—Estimated change (2000–2002) in percent of

basal area per acre (trees >4 inches d.b.h.) by crown

condition, species group, and damage strata on the

Ozark National Forest

 Stratum

Crown condition Light Moderate Severe

Red oaks

Healthy and slight -1.8 -10.9 -8.9

Moderate and severe 0 -3.1 +0.5

Dead +1.8 +14.0 +11.5

White oaks

Healthy and slight -1.8 -3.0 -0.5

Moderate and severe -3.6 +1.5 0

Dead +5.5 +1.5 +0.2

Other species

Healthy and slight 0 0 -9.2

Moderate and severe -1.8 0 0

Dead -1.8 0 +6.4

Table 4—Estimated change (1999–2002) in percent of

basal area per acre (trees >4 inches d.b.h.) by crown

condition, species group, and damage strata on the

Ozark National Forest

 Stratum

Crown condition Light Moderate Severe

Red oaks

Healthy and slight -9.1 -18.8 -14.3

Moderate and severe +1.8 -1.6 +0.5

Dead +7.3 +20.3 +16.9

White oaks

Healthy and slight -7.2 -4.6 -0.5

Moderate and severe 0 +3.1 0

Dead +7.3 +1.5 +0.2

Other species

Healthy and slight -1.8 0 -11.0

Moderate and severe 0 0 0

Dead +1.8 0 +8.2
222

Starkey, D.A.; Oak, S.W.; Ryan, G.W. [and others]. 1989. Evaluation of oak decline areas in the South. Prot. Rep. R8-PR17.

Atlanta, GA: U.S. Department of Agriculture, Forest Service,

Southern Region. 36 p.

Starkey, D.A., Mangini, A.; Oliveria, F.L. [and others]. 2000. Forest

health evaluation of oak mortality and decline on the Ozark

National Forest, 1999. Rep. No. 2000-02-02. Alexandria, LA:

USDA Forest Service, Southern Region, State & Private

Forestry, Forest Health Protection. 31 p.

Tainter, F.H.; Retzlaff, W.A.; Starkey, D.A.; Oak, S.W. 1990.

Decline of radial growth in red oaks is associated with shortterm changes in climate. European Journal of Forest Pathology

20: 95-102.

Wargo, P.M.; Houston, D.R.; LaMadeleine, L.A. 1983. Oak decline.

Forest Insect and Disease Leaflet 165. Washington, D.C.; U.S.

Department of Agriculture, Forest Service. 8 p.

Yeiser, J.L.; Burnett, F. 1982. Fate of forest trees stressed by heat

and drought in southeastern Arkansas. Southern Journal of

Applied Forestry. 6(4): 194-195.
223

INTRODUCTION

The red oak borer Enaphalodes rufulus (Haldeman)

(Coleoptera: Cerambycidae), a normally endemic insect

species of only minor importance, is currently undergoing a

remarkable outbreak of unprecedented magnitude within

the forests of the Ozark Mountains in Arkansas and

Missouri (USA) (Stephen and others, in press).

Forests of the Ozark Mountains have been recently subject

to stress from a widespread disease complex known as

“oak decline” (Oak and others 1996). This complex is

believed to result from a series of predisposing, inciting and

contributing factors (Manion 1991). In the Ozark Mountains

predisposing factors are tree age, prolonged drought, poor

soils and low site quality. Inciting factors are thought to be

short periods of severe drought stress (Starkey and others

2000). Data from the National Oceanic and Atmospheric

Administration suggest there has been a drought of

moderate consequence from 1998 until 2000, and two more

serious droughts in the past 50 years (fig. 1). Whether

these periods of drought have been sufficient to serve as

an inciting factor for an oak decline event is speculation.

Contributing factors have been postulated as being

defoliating insects (walking sticks, Diapheromera femorata

Say), root diseases (e.g., Armillaria mellea (Vahl: Fr.)

Kumm., stem cankers (Hypoxylon species) along with

secondary borers such as the two-lined chestnut borer,

Agrilis bilineatus (Weber) and the red oak borer.

The red oak borer has an interesting two-year life cycle in

the central US, with adults emerging synchronously, only in

odd numbered years, around mid June (Hay 1972, Donley

and Acciavatti 1983). Females oviposit eggs within bark

crevices or under lichens (Donley 1978) which hatch within

14 days (Solomon 1995). Resulting larvae then chew into

the bark and excavate a gallery in phloem tissue. After a

winter-long quiescent period, larvae move from the phloem

into the sapwood where in their second year they again

overwinter before pupating around May. During the later

feeding stages frass is ejected from entrance holes and can

be seen at the base of infested trees. Preliminary estimates

of red oak borer densities, made by our lab during 2001,

were striking. The number of early larval attack holes

averaged 244/m2. Density of mature (2nd year) larvae

averaged 21.4/m2 while emerging adult density averaged

18.5/m2. The magnitude of the outbreak becomes clear

when compared to Hay’s (1974) study that examined 480

trees but reported only 2.5 to 3.7 average attacks per tree

(the highest being 71). Hay (1974) also trapped emerging

adults and reported that the highest number of emerging

adults on a tree was 15.

We present here a summary of our sampling methods. We

also present an update on red oak borer biology and

mortality, along with preliminary data on population levels at

the within-tree level. The importance of red oak borer as

the main contributing factor to current oak mortality will also

be discussed.

METHODS

A plot was selected within the “Fly Gap/Morgan Mountain”

area of the Ozark-St. Francis National Forest so that it

incorporated an appropriate representation of variation in

site and stand conditions as well as red oak borer

infestation density. All trees sampled within the plot were

geo-spatially referenced using a GPS navigator unit

(Garmin III+). Stand conditions were assessed in a 100 m x

30 m (3000 m2 area) plot. Species and diameter at breast

height (d.b.h., 1.3 m) was determined for all trees >10 cm.

Crown condition and emergence hole density (from 0-2 m

ht) were recorded as in table 1. Crown class, epicormic

branching (shoots arising from latent buds of the tree bole),

current year red oak borer attack and Hypoxylon presence

were also recorded, as summarized in table 2.

Three trees were selected for felling using the rating

system summarized in table 1. The three trees sampled

were rated as emergence hole density classes of 1 low tree

and 2 medium trees on the dates shown in table 3. Trees

with a crown condition of 4 or 5 were not sampled as they

were dead. Felled trees were cut into 0.5m sections; each

log having the north-facing side marked with a line cut into

the bark. Samples were then labeled, before being taken

back to the laboratory for intensive sampling. Samples were

BIOLOGY AND SAMPLING OF RED OAK BORER POPULATIONS

IN THE OZARK MOUNTAINS OF ARKANSAS

Damon Crook, Fred Stephen, Melissa Fierke, Dana Kinney, and Vaughn Salisbury1

1 Research Associate; Professor, Team Leader; Research Student; and Research Specialists, Department of Entomology, University of

Arkansas, Fayetteville, AR 72701, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

ABSTRACT—A complex interaction of multiple factors has resulted in >75 percent mortality/decline of more than 1 million

acres of red oak (Quercus, subgenus Erythrobalanus) on the Ozark-St. Francis National Forests. The most striking feature

of this oak decline event is an unprecedented outbreak of red oak borer. A visual stand assessment method was devised

for categorizing red oak borer infestation based on crown condition and number of adult emergence holes in the tree bark.

An intensive sampling method was also developed to study borer populations at the within-tree level. Complete tree

dissections revealed that red oak borer colonizes the entire tree bole. Emergence holes are the highest ever reported in

the literature averaging 19.97/m2 of bark despite high mortality during early larval stages.
224

Figure 1—Evidence for droughts in the Ozark Mountain region, from 1950 through 2000.

Table 1—Tree sampling categorization A

Emergence hole

Crown condition density classess

0 = No dieback

1 = 1 – 33% dieback 0 = None

2 = 33 – 66% dieback 1 – 5 = Light

4 = Died this year

 (brown leaves in August) 5 – 20 = Medium

5 = Dead 2 – 4 years (no fine twigs) >20 = Heavy

6 = Dead >4years

emergence holes were mapped (ht versus circumference

from north-facing line). The logs then had the surface layer

of bark scraped off with a ten-inch ‘Ox-Head’ draw knife so

that early larval galleries and larvae (dead and alive) could

be counted and mapped. Older, deeper galleries were then

traced down into the sapwood, using chisels, before being

mapped.

RESULTS

Stand Description

Total live tree (>10 cm d.b.h.) density was 450 trees/ha and

total basal area occupied by large trees was 24.3 m2/ha.

Tree species richness (gamma diversity, Whittaker 1975)

was 12 with red oaks being dominant (123 trees/ha and

11.3 m2/ha basal area). White oaks were the next dominant

tree species (113 trees/ha and 7.0 m2/ha basal area). Other

tree species totaled 214 trees/ha with a basal area of 6.32

m2/ha. Standing dead tree density was 107 trees/ha, 38

percent of which comprised of red oaks (50 percent of

these red oaks died this year).

kept in a refrigerated room at 2 °C to prevent larval

development or migration within the tree. Chilling appeared

to have no effect on larval mortality. Lichens and moss

were cleaned off the bark surface with a 14 cm diameter

wire wheel brush (drill-powered) after which attack and

Drought 

Number 

Drought Period Duration 

(months) 

Peak monthly 

PDSI 

Mean monthly 

PDSI 

s.e. for mean 

 PDSI 

1 May 1952 – Dec 1956 56 -5.19 -2.93 (a) 0.16 

2 Mar 1962 – May 1967 63 -4.81 -1.55 (b/c) 0.19 

3 Oct 1978 – Apr 1981 19 -3.79 -2.21 (a/b) 0.29 

4 Apr 1998 – Oct 2001 41 -2.69 -1.22 (c) 0.16 

The Palmer Drought Severity Index (PDSI): An Index based on the principles of balance between moisture 

supply and demand, uses temperature and rainfall information to indicate the severity of a wet or dry spell. 

The above monthly values are averages of time-bias-corrected divisional temperature-precipitation-drought 

index data from Arkansas division 1, 2, 4 and 5 for the past 50 years obtained from National Oceanic and 

Atmospheric Administration 

(http://wf.ncdc.noaa.gov/oa/climate/onlineprod/drought/xmgr.html) 

The four droughts indicated above displayed extended periods of moderate to 

extreme drought.

-6.00

-4.00

-2.00

0.00

2.00

4.00

Jan-50Jan-52Jan-54Jan-56Jan-58Jan-60Jan-62Jan-64Jan-66Jan-68Jan-70Jan-72Jan-74Jan-76Jan-78Jan-80Jan-82Jan-84Jan-86Jan-88Jan-90Jan-92Jan-94Jan-96Jan-98Jan-00

Palmer Drought Severity Index

Non Drought May 1952 - December 1956 March 1962 - May 1967 October 1978 - April 1981 April 1998 - October 2001
225

Crown condition of the red oaks was generally poor with

severe epicormic branching being apparent on trees with

greater dieback. Twenty-two percent of live red oaks

appeared to suffer no apparent dieback, 35 percent

experienced 1-33 percent dieback, 27 percent had 34-66

percent dieback, and 16 percent had >67 percent crown

dieback.

Emergence hole categories appear to be related to crown

condition (fig 2). Of 21 trees sampled with 0-33 percent

dieback, 20 had less than 5 emergence holes. All but one

standing dead red oak tree with intact bark (n=9) had >5

emergence holes, indicating that they had undergone a

longer ‘history’ of attack by previous generations of red oak

borer.

Crown class of live red oaks showed that in this particular

plot, trees were mainly dominant and co-dominant with

respect to other tree species. Of the 37 live red oaks

examined all showed signs that they had been attacked by

the latest generation of larvae (July/August 2001). Dead

trees and trees with very severe crown dieback tended not

to show signs of recent attack. Hypoxylon was only

observed on dead and dying trees.

Table 2—Tree sampling categorization B

Epicormic Current

Crown class branching Hypoxylon year attack

1 = suppressed Yes Present Brown ooze on bole

2 = intermediate No Absent Frass at tree base

3 = codominant Is it associated

4 = dominant with ROB (Y/N) Attack holes

ROB = red oak borer.

Table 3—Dates of tree felling 2002

Tree Rating Date

Tree 1 High 1-16-02

Tree 2 Low 3-12-02

Tree 3 Medium 4-4-02

Tree 4 Medium 4-5-02

Tree 5 Medium 6-28-02

Figure 2—Red oak borer emergence hole category in relation to tree crown condition for the Fly

Gap/Morgan mountain area of the Ozark National Forest.

















	

 































 !"#

 $ 


 
 

%

&"'(
226

TREE DISSECTIONS

Examination of infested log sections revealed some

interesting facts from which several assumptions could be

made about borer/tree interactions. First, after newly

hatched larvae burrow into phloem tissue they form small,

irregular, circle-shaped galleries of approximately 4 cm2.

When, around November, temperatures drop it appears

larvae enter a quiescent period until the following May.

Dissections revealed that cell tissue around these galleries

became necrotic and blackened. It is uncertain when this

necrotic tissue formed around the larvae but it appeared to

occur once larval feeding stopped during winter.

During June 2002, dissections revealed that the surviving

larvae had not yet moved out of the necrotic galleries. For

all three trees sampled the mean number of attack holes/m2

of bark was 179 (±16.4SE). The mean number of

emergence holes/m2 of bark for all three trees was 19.97

(±2.51SE).

Dissections revealed that borers attacked every section of

the tree’s main bole. Bark attack site density increased in

number from the base of the tree to the middle, after which

density decreased (fig. 3). Numbers appeared to dip slightly

just before halfway up the infested bole. Late larval

galleries and emergence site density also followed this

general trend (figs. 4 and 5). Early larval galleries, however,

appeared to gradually decrease in density from base to top

of the tree (fig. 6).

Mortality was calculated for three time periods from July

2001 – Aug 2001

1. mortality from attacks of newly hatched larvae: from July

2001 until formation of early first year gallery by larvae

(Aug-Nov 2001 approx) (n=82)

( ) #1 1 0.337 0.07

#

st total year galleries SE

total bark attack sites

  − =±    

Figure 3—Distribution of bark attack densities (per 1 m2) of red oak borer larvae from the

base (1) to the tip of the tree (10). n=3.

Figure 4—Distribution of late larval galleries (per 1 m2

) from the base (1) to the tip of the

tree (10). n=3.





















      	  

)
'(

*

















      	  

)
'(


#((+('((

227

2. mortality from live early larvae: larvae in galleries formed

from Aug-Nov 2001 until live larvae were sampled in

trees during Jan-May (n=82)

( ) # 1 0.442 0.03

#1st

total live earlylarvae SE

total year galleries

 

− =±    

3. total mortality from attack of new larvae: from July 2001

until live larvae in necrotic gallery (sampled Jan-May

2002) (n=82)

( ) # 1 0.657 0.04

#

total liveearly larvae SE

total bark attack sites

  − =±    

It is important to note that these mortality estimates are not

calculated from number of eggs oviposited on the bark

surface, but from newly hatched larvae that are able to first

bore into the bark surface. Mortality is expected to be low

when later stage larvae have burrowed into the sapwood of

the tree (mainly due to protection offered by living in gallery

so deep inside the bole).

DISCUSSION

It is clear from our preliminary results that red oak borer

population densities are remarkably high and that trees

within the Ozark National forest are undergoing severe

levels of attack. Despite heavy larval mortality during the

past year surviving larvae boring into the sapwood were still

at incredibly high densities, especially when compared to

Hay’s results from 1974. The only other reported survey of

red oak borer attack was done by Donley and Rast (1984)

who reported that red oak borer adult emergence (from 421

red oaks) averaged 2.0 per tree in Pennsylvania and 3.6 in

Indiana.

At present we cannot explain the apparent trend for

population densities to dip near the center of the infested

Figure 5—Distribution of bark emergence sites (per 1 m2) from the base (1) to the tip of

the tree (10). n=3.

Figure 6—Distribution of live early larvae (per 1 m2

) from the base (1) to the tip of the

tree (10). n=3.























      	  

)
'(

*"'











	







      	  

)
'(


#((+('((

228

boles. This may simply be an artifact. Further tree

dissections will clarify whether the borer population has a

uni- or bi-modal distribution within trees.

Although predisposing factors such as old tree age, shallow

soils, periods of drought, low species diversity and fungal

pathogens may be indicted as possible contributors to the

current ‘oak decline’ event, it is clear that red oak borer

populations are much higher than ever seen in recorded

history and that they are the main factor responsible for

tree death. If oak decline has reduced tree vigor in such a

manner as to permit higher survival of red oak borers over

several generations, it is perplexing to note that such high

levels of red oak borer populations have never been

reported with other oak decline events, despite the fact that

this endemic insect species has been present in those

forests. The consequences of the current outbreak in terms

of changes to forest composition and structure are as yet

unclear. It is predicted that changes to some groups, such

as the complex of neotropical migrant birds, may be

significant (Smith and Stephen, in press).

Mortality studies are continuing and it is hoped that by July/

August 2003 partial life tables will be completed for an

entire generation. Current sampling methods at the withintree level are being refined to optimize number of tree

sections needed to accurately estimate within tree

population densities. This will enable more trees to be

sampled from different areas and allow populations to be

compared between stands of different conditions.

Our initial stand assessments show that crown condition

and emergence hole density (from 0-2 m) give a quick and

simple method of assessing red oak borer infestation. This

method is presently being used by USDA Forest Service

survey teams to assess red oak borer populations in stands

over the entire Ozark-St. Francis National Forests. These

surveys should be able to more precisely estimate the

severity of the current epidemic.

ACKNOWLEDGMENTS

This research was funded in part by the University of

Arkansas, Arkansas Forest Resources Center and the UA

Division of Agriculture. Laboratory assistance with

dissection studies from Stephen Wingard and Leah Lucio is

gratefully acknowledged.

LITERATURE CITED

Donley, D.E. 1978. Oviposition by the red oak borer, Enaphalodes

rufulus Coleoptera: Cerambycidae. Annals of the Entomological

Society of America 71: 496-498.

Donley, D.E.; Acciavetti, R.E. 1980. Red oak borer. USDA Forest

Service For. Ins. & Dis. Leaflet 163. 7 p.

Donley, D E.; Rast, E. 1984. Vertical distribution of the red oak

borer Enaphalodes rufulus (Coleoptera: Cerambycidae), in red

oak. Environmental Entomology 13: 41-44.

Hay, C.J. 1972. Woodpecker predation on red oak borer in black,

scarlet, and northern red oak. Annals of the Entomological

Society of America 65: 1421-1423.

Manion, P.D. 1991. Tree disease concepts. 2nd ed. Prentice Hall,

Englewood Cliffs, New Jersey.

Oak, S.; Tainter, F.; Williams, J.; Starkey, D. 1996. Oak decline risk

rating for the Southeastern United States. Annales des

Sciences Forestierres 53: 721-730.

Smith, K.G.; Stephen, F.M. [In press]. Potential effects of largescale elimination of oaks by red oak borers on breeding

neotropical migrants in the Ozarks. In: Ralph, C.J.; Rich, T.D.,

eds. Proceedings: Bird conservation, implementation and

integration in the Americas. U.S. Department of Agriculture,

Forest Service.

Solomon, J.D. 1995. Guide to insect borers in North American

broadleaf trees and shrubs. USDA Forest Service, Washington

D.C. 706 p.

Starkey, D.A.; Mangini, A.; Oliveria, F.L. [and others]. 2000. Forest

health evaluation of oak mortality and decline on the Ozark

National Forest, 1999. Forest Health Protection Report 2000-

02-02, 31 p.

Stephen, F.M.; Salisbury, V.B.; Oliveria, F.L. [In press]. Red oak

borer, Enaphalodes rufulus (Coleoptera: Cerambycidae), in the

Ozark Mountains of Arkansas, U.S.A: an unexpected and

remarkable forest disturbance. Integrated Pest Management

Reviews (in press).

Whittaker, R.H. 1975. Communities and ecosystems. 2nd edition.

Macmillan, New York.
229

INTRODUCTION

A recent outbreak of the red oak borer (Enaphalodes rufulus

Haldeman) in Arkansas has raised interest and concern

about oak mortality. Data currently available are not suitable

to quantify the extent of infestation or the number of trees

killed. However, U.S. Department of Agriculture (USDA)

Forest Service, Forest Inventory and Analysis (FIA) data,

which span three survey measurement periods, are available to quantify mortality trends prior to the borer outbreak.

Although the most recent survey (dated 1995) predates the

red oak borer outbreak, valuable information can be derived

from older surveys to describe oak mortality patterns on the

Interior Highlands of northwest and west Arkansas. By providing baseline data of mortality dynamics, it may be easier

to put into perspective the extent of infestation now occurring

in the oak component. With a better understanding of mortality dynamics, resource managers may better use silvicultural techniques to prevent, retard, or cope with mortality

incidents (Nyland 1996). Little information has been reported

about oak mortality patterns by physiographic regions,

ownership, size class, and species.

I considered an area that includes the Interior Highlands of

Arkansas (Fenneman 1938), where the oak-hickory forest

type predominates. Oaks (Quercus) were the species of

interest. A drought event in Arkansas in the early 1980s provided the opportunity to correlate oak mortality with drought

during three survey periods (1978, 1988, 1995). I compared,

over time, total oak mortality among Physiographic Sections

(Fenneman 1938), ownership classes, and stand-size

classes. I also examined mortality trends for select oak

species.

METHODS

The inclusive area of the study is the Interior Highlands

Physiographic Division (Fenneman 1938). In Arkansas,

this Division includes four physiographic sections in two

provinces: The Springfield-Salem Plateaus and Boston

Mountains sections in the Ozark Plateaus Province and the

Arkansas Valley and Ouachita Mountains sections in the

Ouachita Province (fig 1).

The data of surveys conducted in 1978, 1988, and 1995

came from the USDA Forest Service, Forest Inventory and

Analysis (FIA). Using geographic information system (GIS)

software, I digitally traced the physiographic boundary lines

of the four physiographic sections over a layer of FIA plot

locations, thereby establishing the baseline data file to

define FIA plots by physiographic strata. The scale of the

map used to outline the physiographic boundaries was

1:7,000,000 (adequate for regional analysis).

The sample design for the three surveys consisted of sample plots located on a 3-mile by 3-mile grid. Only trees ≥ 5.0

inches in diameter at breast height (d.b.h.) were used in

this study. These trees were tallied using a 37.5 basal area

factor (B.A.F.) prism on 10 points dispersed over an area of

1 acre (see Rosson 2002 for more details on sampling

methods in Arkansas).

Several plot- and tree-level attributes were sampled on

each sample unit. Tree attributes important to this study

were species, d.b.h., and tree history. Of particular interest

in this study was tree history, which was used to identify

mortality.

Because sample plots were remeasured, trees could be

tracked over time and their history noted whether they were

new trees, survivor trees, cut (removed) trees, or mortality

trees (dead and standing, dead and broken off, or dead and

completely down). Use of remeasured plots is one of the

best techniques available to track tree mortality over time

(Bonham 1989).

Mortality estimates were generated from weighted density

data. Trees per acre (t.p.a.) was the metric used. The

weighting was derived from the area factor—the amount of

land area each plot represented. When weighting was

applied, the resulting metric was the total oak population

expanded by plot by strata.

Although it would seem that a dead tree could be easily identified, errors can be made. Because FIA data are collected

OAK MORTALITY TRENDS ON THE INTERIOR HIGHLANDS OF ARKANSAS

James F. Rosson, Jr.1

1

 Research Forester, USDA Forest Service, 4700 Old Kingston Pike, Knoxville, TN 37919.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Using data from the U.S. Department of Agriculture (USDA) Forest Service, Forest Inventory and Analysis

program, I studied mortality trends of oak (Quercus spp.) across four physiographic sections of the Interior Highlands in

Arkansas. Surveys for 1978, 1988, and 1995 showed oak mortality levels of 3.9, 8.9, and 5.5 percent, respectively.

Increases in mortality were strongly correlated with a major drought event in 1980 (reflected in the 1988 survey). The

highest recorded mortality (1988 survey) was in the Arkansas Valley section. Other strata examined included ownership

and stand-size classes. The highest mortality by ownership was on forest industry lands; by stand-size class, it was

highest where diameters averaged ≥ 12.0 inches. Six oak species accounted for 95 percent of mortality. A high population

resilience rate was evidenced by the rapid increase and decrease in oak mortality before and after the 1980 drought

event.
230

T = the elapsed time (in years) per plot between plot

 measurements

n = the number of sample plots per strata.

The AAPM is an estimator of the number of trees that died

per strata or species for each survey period.

The annual periodic mortality rate is,

APMR = (Nld × Wa /Nd × Wa )/ T ×100.0 (2)

where

APMR = the annual periodic mortality rate (in percent)

Nld = the number of live and dead trees per acre per plot (by

 strata or species)

Nd = the number of dead trees per acre per plot (by strata

 or species)

Wa

 = the area factor

T = the elapsed time (in years) per plot between plot

 measurements.

The APMR is an estimator of the proportion of trees that

died per strata or species.

Differences in oak mortality by physiographic type,

ownership, and stand-size class were tested with a t-test

procedure for the unplanned comparison of two means

(Greig-Smith 1983, Kent and Coker 1992). This was

derived by,

2

2

2 ts = (y1 − y 2 )/ SEM1 + SEM (3)

in all seasons, recently dead deciduous trees may escape

detection from late fall through the end of winter. The assessment also may have missed trees that had died and were

harvested between surveys; i.e., it was not possible to determine if a cut tree was dead or alive at the time of harvest.

For these reasons, I chose not to include harvested trees in

this study.

Tree measurement is another possible source of error. The

d.b.h. of recently dead trees may be accurate, but those trees

dead for a period of years may have fallen over, broken off,

or the bole may be decayed to an extent that accurate measurement is not possible. In such cases, d.b.h. was derived

from a model that estimates d.b.h. at the time of death. Time

of death since the most recent survey was estimated in the

field by the data collector. The d.b.h. model was only used

to project from time of death the supposed growth of a living

tree of the same size. This is important when sampling with

variable radius plots because d.b.h. is used to determine

tree density.

To evaluate changes in mortality, the average annual

periodic mortality and annual periodic mortality rate were

derived.

The average annual periodic mortality is,

AAPM = (∑( ) Nd × Wa / T )/n (1)

where

AAPM = the average annual periodic mortality

Nd = the number of dead trees per acre per plot (by strata

 or species)

Wa = the area factor per plot

Springfield-Salem

Plateaus

Boston Mountains

Arkansas Valley

Ouachita Mountains

Figure 1—The four physiographic sections on the Interior Highlands of Arkansas (After Fenneman, 1938).
231

where

t

s

 = the t-statistic value

1 y = the mean of mortality at time 1

2 y = the mean mortality at time 2

SEM1

 = the standard error of the mean at time 1

SEM2 = the standard error of the mean at time 2.

The tests were done at the 0.05 probability level.

RESULTS AND DISCUSSION

The Interior Highlands comprise 16.5 million acres in west

and northwest Arkansas (fig. 1). Forty-two counties are

included; 29 of them totally within the Physiographic

Province and the remaining 13 partially inside the southern

and eastern boundary line. A total of 10.2 million acres of

timberland occur within the Interior Highlands (table 1).

The largest physiographic section is the Ouachita, which

has 5.1 million acres of land area and 3.8 million acres of

timberland. The largest ownership class is in nonindustrial

Table 1—Timberland area by Fenneman’s Physiographic Sections

and by ownership classes on the Interior Highlands of Arkansasa

Fenneman’s

Physiographic

Section and Total land Timberland

Ownership Class area area n

 - - - thousand acres - - -

Ouachita

National forest 1,308.1 230

Public 136.1 25

Forest industry 1,201.3 212

NIPF 1,115.1 192

Total 5,073.6 3,760.6 659

Arkansas Valley

National forest 161.1 30

Public 129.7 20

Forest industry 90.0 15

NIPF 1,344.1 214

Total 3,532.3 1,724.9 279

Boston Mountains

National forest 738.8 131

Public 23.1 4

Forest industry 113.2 19

NIPF 1,510.6 258

Total 3,130.5 2,385.7 412

Springfield-Salem Plateaus

National forest 125.6 26

Public 94.7 15

Forest industry — —

NIPF 2,091.5 333

Total 4,746.0 2,311.8 374

Interior Highlands

National forest 2,333.5 417

Public 383.6 64

Forest industry 1,404.4 246

NIPF 6,061.3 997

Total 16,482.3 10,182.9 1,724

n = the number of timberland sample plots in each physiographic and

ownership strata; NIPF = nonindustrial private forest; — = no sample plot.

a Area data is based upon plots measured in the 1995 survey.
232

private forest (NIPF), 6.1 million acres, followed by national

forest, which is 2.3 million acres (table 1).

The average annual periodic mortality (AAPM) for all oaks

sampled on the Interior Highlands increased from 1978 to

1988 and then fell to near the 1978 levels at the time of the

1995 survey (table 2). The largest increase in oak mortality

was on the Arkansas Valley physiographic section, where

the AAPM went from 954.1 to 5,306.7 trees per weighted

plot, a highly significant change (t0.05 = 6.60). The other physiographic sections also had significant increases in AAPM

between 1978 and 1988, 1,081.0 (t0.05 = 3.68), 2,499.5 (t0.05

= 5.20), and 1,425.4 trees per weighted plot (t0.05 = 2.73) for

the Ouachita, Boston Mountains, and Springfield-Salem

Plateaus sections, respectively.

The highest annual periodic mortality rate (APMR) was in

the Arkansas Valley section in 1988, where 14.04 percent

of all oaks died. The other sections also showed increases

between 1978 and 1988, then returned to near their 1978

levels when the 1995 survey was conducted. There was no

discernible pattern in the ranking of physiographic sections

by APMR. The highest rankings by survey year were: the

Springfield-Salem Plateau section, the Arkansas Valley, and

the Boston Mountains for 1978, 1988, and 1995,

respectively.

The patterns of AAPM by ownership and survey year were

similar to those of the four physiographic sections. There

was an increase between 1978 and 1988 followed by a

decrease between 1988 and 1995 (table 3). There were no

significant differences among ownerships in 1978. Specifically, there was no difference between national forest

timberland and public timberland (t0.05 = 0.52) nor was there

a significant difference between forest industry and NIPF

(t0.05 = 1.17).

Statistically significant differences were evident between

ownerships in 1988. The AAPM on national forest land

increased to 3,883.5 trees per weighted plot, the highest of

any ownership in the 3 survey years. National forest lands

were significantly different from other public lands; 3,883.5

and 1,984.7 trees per weighted plot, respectively (t0.05 = 2.81).

There was a statistically significant difference between

forest industry and NIPF lands, 2,071.4 and 3,766.4 trees

per weighted plot (t0.05 = 3.61). The 1995 survey showed

that the AAPM had declined somewhat. Changes in AAPM

by ownership between 1988 and 1995 were only significant

for national forest (t0.05 = 2.18) and NIPF timberland (t0.05 =

4.30); other public and forest industry lands were not significantly different, t0.05 = 1.11 and t0.05 = 1.81, respectively.

When comparing AAPM among ownerships within the 1995

survey, I found no difference between national forest and

other public lands (t0.05 = 0.36) but the difference between

forest industry and NIPF was statistically significant (t0.05 =

3.74). Additionally, there was no difference between national

forest and NIPF lands in AAPM (t0.05 = 0.94) or between

other public lands and NIPF (t0.05 = 0.76).

Stand-size classes were examined to discern differences

among the size classes between years and within years

(table 4). In 1978, there were no differences in the AAPM

between the 5.0-7.9-inch and 8.0-11.9-inch classes (t0.05 =

0.42); nor was there a difference between the 8.0-11.9- and

the 12.0-15.9-inch classes (t0.05 = 0.50) or the 12.0-15.9-

and the ≥ 16.0-inch classes (t0.05 = 0.33). As in the previous

Table 2—Average annual periodic mortality per plot and annual periodic mortality rate by

year and Fenneman’s Physiographic Sectionsa

Variance

Average of average

Fenneman’s annual annual

Physiographic periodic Annual periodic periodic

Year Sections mortality mortality rate mortality n

percent

1978 Ouachita 1,122.9 3.64 23,755,817.8 613

Arkansas Valley 954.1 2.61 8,483,027.0 167

Boston Mountains 1,834.0 3.87 18,770,468.8 302

Springfield-Salem Plateaus 2,054.5 4.96 23,372,541.0 180

1988 Ouachita 2,203.9 8.16 31,112,018.5 657

Arkansas Valley 5,306.7 14.04 99,604,425.9 265

Boston Mountains 4,333.5 8.49 71,044,389.8 421

Springfield-Salem Plateaus 3,479.9 7.15 51,183,438.2 357

1995 Ouachita 1,724.1 4.88 27,125,931.2 659

Arkansas Valley 2,119.6 5.62 29,964,393.3 279

Boston Mountains 3,071.4 6.12 40,688,129.3 412

Springfield-Salem Plateaus 2,919.4 5.68 40,196,162.5 374

n = the number of timberland sample plots in each physiographic strata.

a The average annual periodic mortality is the number of trees per acre weighted by the area expansion

factor each plot represents.
233

Table 3—Average annual periodic mortality per plot and annual periodic mortality rate

by year and ownership class on the Interior Highlandsa

Variance

of average

annual

Ownership Average annual Annual periodic periodic

Year class periodic mortality mortality rate mortality n

percent

1978 National forest 1,505.5 3.45 17,264,299.1 387

Public 1,245.2 4.23 8,333,702.2 40

Forest industry 1,005.6 4.27 34,763,366.9 232

NIPF 1,501.9 3.89 18,152,184.7 603

1988 National forest 3,883.5 9.04 69,280,316.1 416

Public 1,984.7 5.67 17,147,416.7 59

Forest industry 2,071.4 11.05 40,547,095.8 251

NIPF 3,766.4 8.74 57,929,807.3 974

1995 National forest 2,775.2 5.81 37,901,590.2 417

Public 3,101.7 7.07 46,059,335.8 64

Forest industry 1,188.4 5.65 19,066,464.8 246

NIPF 2,444.0 5.32 34,850,646.2 997

n = the number of timberland sample plots in each ownership strata; NIPF = nonindustrial private forest.

a The average annual periodic mortality rate per plot is the number of trees per acre weighted by the area

expansion factor each plot represents.

Table 4—Average annual periodic mortality per plot and annual periodic mortality

rate by year and stand-size class on the Interior Highlandsa

Variance

Stand-size of average

class in annual

inches Average annual Annual periodic periodic

Year at d.b.h. periodic mortality mortality rate mortality n

percent

1978 <5.0 0.0 0.00 0.0 68

5.0 – 7.9 1,324.5 2.90 39,913,321.3 250

8.0 –11.9 1,501.9 3.90 16,594,270.2 862

12.0 –15.9 1,817.5 7.45 21,333,720.0 73

?16.0 1,438.4 10.97 9,514,229.2 9

1988 <5.0 55.7 0.27 367,409.0 248

5.0 – 7.9 3,457.9 8.94 52,296,977.3 306

8.0 –11.9 4,324.8 9.60 69,783,893.8 1,029

12.0 –15.9 3,364.1 11.22 48,486,792.1 100

?16.0 3,668.8 27.91 50,125,944.4 17

1995 <5.0 818.9 4.77 12,284,125.3 131

5.0 – 7.9 1,201.1 3.88 17,616,440.5 270

8.0 –11.9 2,687.9 5.43 37,734,153.9 1,187

12.0 –15.9 3,472.2 10.18 47,316,184.3 123

?16.0 2,744.6 18.95 57,227,065.9 13

D.b.h. = diameter at breast height; n = the number of timberland sample plots in each stand-size strata.

Note that some trees ?5.0 inches in d.b.h. may occur in the <5.0 inch stand-size class because the

class is the average of all trees on the sample plot.

a The average annual periodic mortality rate per plot is the number of trees per acre weighted by the

area expansion factor each plot represents.
234

physiographic and ownership tests, the 1988 survey showed

a large increase in AAPM for all the stand-size classes,

although no statistically different averages occurred among

any of the classes. By 1995, the AAPM was still significantly

different from what it had been in 1978 for the 8.0-11.9-inch

stand-size class (t0.05 = 4.02). The remaining size classes

were not significantly different.

The APMR was highest for the largest stand-size class

(≥ 16.0 inches d.b.h.). This class averaged 11, 28, and 19

percent mortality for 1978, 1988, and 1995, respectively;

but the inferences were not as strong because of the small

sample size (table 4). However, the magnitude of the APMR

for this size class does support the notion that mortality

rates will be higher in older stands when conditions of

stress exist (Oliver and Larson 1990).

Six oak species accounted for 96 percent of the total oak

density (trees ≥ 5.0 inches d.b.h.) on the Interior Highlands.

The relative ranking of these oaks was Quercus alba (35

percent), Q. stellata (24 percent), Q. velutina (14 percent),

Q. rubra (11 percent), Q. falcata (7 percent), and Q. marilandica (5 percent), and it remained the same throughout

the three survey periods despite increases and decreases

in mortality.

These six oaks also accounted for 95 percent of the total

oak mortality (AAPM) for the three survey periods, although

their ranking did shift somewhat between surveys. Quercus

alba had the most trees die in 1978, accounting for 28 percent of total oak mortality. Following were Q. velutina, Q.

stellata, Q. rubra, Q. marilandica, and Q. falcata, accounting for 20, 19, 12, 9, and 7 percent of total oak mortality. By

1988, the proportion of Q. alba mortality had decreased to

24 percent while Q. velutina increased to 24 percent.

Quercus velutina led in the proportion of oak mortality in

1995 (23 percent) while Q. alba had declined even more

(down to 18 percent), third in rank behind Q. velutina and

Q. stellata.

There were shifts among species rankings depending on

whether AAPM or APMR were used when estimating mortality. The AAPM provided information about the total number

of trees that died, while the APMR revealed the proportion

of a stratum or species that died. With regard to the latter,

most oak death recorded in the 1988 survey occurred in Q.

alba, although the proportion of that species’ population to

have died was only 6 percent (table 5).

The ranking of the six important oaks by APMR in 1978 was

Q. marilandica, Q. velutina, Q. rubra, Q. falcata, Q. alba, and

Q. stellata (table 5). Quercus marilandica led in all three

surveys with 8, 21, and 15 percent APMR for 1978, 1988,

and 1995, respectively.

Damage due to the 1980 drought was most apparent in

the 1988 survey, but only a slight shift in species ranking

occurred. Quercus falcata surpassed Q. rubra, 12 percent

versus 8 percent, respectively. By 1995, the ranking was

the same as in 1978 except that Q. stellata surpassed Q.

alba (5 percent versus 3 percent, respectively).

Empirical data have depicted Quercus species mortality

trends on the Interior Highlands of Arkansas since 1969.

The data were analyzed by physiographic section, ownership, stand-size class, and species. There were significant

Table 5—Annual periodic mortality rate (percent) of select Quercus

species on the Interior Highlands of Arkansas by survey yeara

Species 1978 n 1988 n 1995 n

%%%

Quercus alba L. 3.03 70 6.48 205 2.90 92

Q. falcata Michx. 4.02 20 11.68 63 5.18 34

Q. falcata var.

pagodifolia Ell. 3.59 3 18.64 9 13.61 5

Q. lyrata Walt. 12.51 3 4.88 3 3.24 4

Q. marilandica Muenchh. 7.67 29 20.86 91 14.72 66

Q. michauxii Nutt. 0.00 0 0.00 0 4.92 1

Q. muehlenbergii Engelm. 0.77 3 1.00 1 4.69 8

Q. nigra L. 2.52 1 5.19 11 7.36 6

Q. nuttallii Palmer 4.78 2 3.93 7 15.51 1

Q. palustris Muenchh. 0.00 0 6.90 3 0.00 0

Q. phellos L. 5.50 6 14.44 14 8.98 11

Q. rubra L. 4.07 50 8.28 112 7.18 105

Q. shumardii Buckl. 7.29 4 6.52 4 1.48 3

Q. stellata Wangenh. 2.99 56 6.40 133 4.62 106

Q. velutina Lam. 5.48 62 13.05 179 8.59 153

n = the number of sample plots where mortality was recorded for at least one Quercus

species ?5.0 inches in d.b.h.

a Only Quercus species that occurred (live or dead) on at least five sample plots in any

of the three survey years were included. Total n was 1,262 for 1978, 1,700 for 1988, and

1,724 for 1995.
235

differences among surveys for all categories. The most

logical cause for these differences was the 1980 drought,

which significantly increased tree mortality.

Despite increases in mortality in 1988, the Quercus population (trees ≥ 5.0 inches d.b.h.) increased across the Interior

Highlands by 1995. Only one species of the highest ranking

six oaks decreased—Q. marilandica. The highest AAPM by

physiographic section was on the Arkansas Valley; the highest AAPM by ownership was on forest industry land; and

the highest AAPM by stand size was in classes ≥ 12.0 inches,

all in 1988. Overall, across the Interior Highlands, the

Quercus APMR was 3.9 percent in 1978, 8.9 percent in

1988, and 5.5 percent in 1995.

Although FIA data cannot be used to test cause and effect

hypotheses, correlation inferences between natural or maninduced disturbance events, and supporting data, can be

quite strong. In this mortality study, strong, statistically significant increases in oak mortality were evident for the 1988

survey. Trees measured in 1988 reflected responses that

occurred between 1978 and 1988. A period of drought

occurred around 1980, early in the 1988 survey period. This

left enough time for stressed trees to respond (death or

survival). If the event had occurred closer to the end of the

survey period, the response may not have been evident by

the time of measurement and thus would not have been

detected until the following survey measurement. This is

one type of situation that makes strong cause-and-effect

inferences difficult to interpret when using survey data.

Because mortality increased between 1978 and 1988 but

had declined by 1995, it can be assumed that the drought,

directly or indirectly, caused the increase in oak mortality

reflected in the 1988 survey period. However, it is not known

what constitutes a normal AAPM or APMR for oak on the

Interior Highlands. If it can be assumed that the mortality

levels for the 1978 survey period (years 1969 to 1978) are

close to normal, then this study shows an increase in

mortality in the 1988 survey followed by a fairly quick return

to mortality levels reflected in the 1978 survey. This may

indicate a high rate of population resilience to short-term

stress when viewed at the macro scale of sampling (Begon

and others 1986, Kimmins 1997).

LITERATURE CITED

Begon, M.; Harper, J.L.; Townsend, C.R. 1986. Ecology:

individuals, populations, and communities. Sunderland,

Massachusetts: Sinauer Associates, Inc. 876 p.

Bonham, C.D. 1989. Measurements for terrestrial vegetation. New

York: John Wiley. 338 p.

Fenneman, N.M. 1938. Physiography of Eastern United States.

New York: McGraw-Hill. 691 p.

Greig-Smith, P. 1983. Quantitative plant ecology. 3rd ed. Berkeley,

CA: University of California Press. 359 p.

Kent, M.; Coker, P. 1992. Vegetation description and analysis: a

practical approach. New York: John Wiley. 363 p.

Kimmins, J.P. 1997. Forest ecology: a foundation for sustainable

management. Upper Saddle River, New Jersey: Prentice Hall.

596 p.

Nyland, R.D. 1996. Silviculture: concepts and applications. New

York: McGraw-Hill. 633 p.

Oliver, C.D.; Larson, B.C. 1990. Forest stand dynamics. New York:

McGraw-Hill. 467 p.

Rosson, J.F., Jr. 2002. Forest resources of Arkansas, 1995.

Resour. Bull. SRS-78. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southern Research Station. 82 p.
236

INTRODUCTION

Hardwoods dominate forest cover in the thirteen states of

the southern region, with about two-thirds of the area in

upland hardwood, bottomland hardwood, or oak-pine mixtures. Upland hardwood is by far the largest forest type

group, accounting for about 37 percent of the forested area

(Sheffield and Dickson 1998). Oaks dominate the growing

stock volume in upland hardwood stands, comprising 47

percent of the total region wide. The next most abundant

species is yellow poplar, which makes up only 12.6 percent

(Hansen and others 1992).

Oak species are economically and ecologically important in

the southern region as valuable timber species and indispensable habitat components for wildlife feeding on hard

mast. However, oak decline is a widely distributed change

agent that is altering species composition and forest structure in upland hardwood and mixed oak-pine forests. Oak

decline is a disease complex resulting from the interaction

of three groups of factors as described by Manion (1991).

Physiologic age, soil depth and texture, oak species composition, and oak density are the main long-term predisposing

factors. Common inciting factors include prolonged acute

drought, spring defoliating insects like fall cankerworm and

gypsy moth, and late spring frost. The biotic agents most

often identified as contributing factors include Armillaria

root disease, Hypoxylon canker and insect pests of opportunity like twolined chestnut borer and red oak borer. The

symptom separating oak decline from other diseases of oak

is slow, progressive dieback from the top downward and the

outside inward in upper canopy trees (i.e., dominants and

codominants). This symptom reflects aboveground the

condition of the root system underground. The time scale of

disease progression from inception to the death of susceptible trees is typically measured in years or decades, but

tree mortality after a relatively short period of dieback

sometimes occurs.

Oak decline is not a new phenomenon. Forest workers

reported occurrences as early as the mid 1800’s (Beal

1926, Balch 1927) and in every decade since the 1950’s

(Millers and others 1988). An apparent increase in incidence and severity in the early 1980’s and continuing

through the 1990’s led to an intensification of survey and

monitoring activities (Bassett and others 1982, Starkey and

others 1989, Stringer and others 1989, Oak and others

1990, Starkey and others 2000), but most were relatively

limited in geographic scale. Periodic multi-resource inventories conducted by the U.S.D.A Forest Service Southern

Research Station Forest Inventory and Analysis work unit

(FIA) afford the opportunity for regional assessments of oak

decline. The results for two inventory cycles- 1984 through

1989 and 1991 through 1997 are reported in this paper.

METHODS

Permanent inventory plots are distributed over the land area

of each state and visited at approximately six to eight year

intervals by FIA field crews. Detailed accounts of data collection procedures can be found in field instruction manuals

(U.S.D.A Forest Service 1984, 1985). Included among these

procedures is coding for tree damages. The standard code

that correlates most closely with oak decline is dieback,

when it occurs in dominant and codominant oak trees. The

geographic limit of this analysis was determined by the

twelve southern states using common damage coding.

These states are Virginia, North Carolina, South Carolina,

Tennessee, Georgia, Florida, Alabama, Mississippi,

Louisiana, Arkansas, Oklahoma, and Texas.

The host type population in these states included plots where

oaks dominate tree species composition (table 1). These

plots represent the area eligible for oak decline. Other

forest types may also contain relatively small numbers of

oaks subject to decline, but such plots were excluded

because resource damage from this disease is unlikely.

ASSESSING OAK DECLINE INCIDENCE AND DISTRIBUTION IN

THE SOUTHERN U.S. USING FOREST INVENTORY AND ANALYSIS DATA

Steven W. Oak, James R. Steinman, Dale A. Starkey, and Edwin K. Yockey1

1 Plant Pathologist, USDA Forest Service, Southern Region, Forest Health Protection, Asheville, NC 28804; Forest Health Monitoring

Coordinator, USDA Forest Service, Northeastern Area State and Private Forestry, Newtown Square, PA 19073; Plant Pathologist, USDA

Forest Service, Southern Region, Forest Health Protection, Pineville, LA 71360; and Analytical Biologist, USDA Forest Service, Southern

Region, Forest Health Protection, Asheville, NC 28804, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Forest Inventory and Analysis data for twelve southern states were used to evaluate regional oak decline

status. Total host type, vulnerable host type, and affected areas were determined. The attributes used for classification

were forest type, predominant stem size class, oak basal area percent, and dieback damage coding. Host type totaled

104.7 million acres in the most recent inventory cycle (1991-1997), of which 41.6 percent were classified as vulnerable.

Oak decline affected over 4.4 million acres, or 10.1 percent of the vulnerable host type. This was a slight incidence

increase over the previous inventory cycle (1984-1989). Two-thirds of the decline-affected area was contained in 4 statesVirginia, North Carolina, Arkansas, and Tennessee in decreasing rank order. Large increases in incidence occurred in

Arkansas and North Carolina, while incidence decreased markedly in Tennessee. Oak decline incidence in Virginia

remained unchanged between inventory cycles.
237

The vulnerable host type population was defined as the

subset of host type plots where the predominant size class

was pole- or sawtimber, and oaks comprised 30 percent or

more of total stand basal area. Plots with these combinations of forest type, size class, and oak density represent

the highest risk for oak decline occurrence and resource

damage. Affected plots were the subset of vulnerable host

type plots where one or more dominant or codominant oaks

had dieback recorded as a damage code.

Subjective evaluation of dieback was considered the greatest potential source of error in decline classification. Quality

assurance procedures for a similar FIA assessment of oak

decline in western Virginia revealed that field crews were

proficient at identifying decline symptoms. Field checks of

10 percent of plots classified as decline-affected showed

they were correctly diagnosed in 92 percent of the cases

(Oak and others 1991). However, all plots in the western

Virginia assessment were classified as decline-affected and

were inventoried during the growing season when decline

symptoms are easier to diagnose. We established the reliability of individual tree coding and decline classification in

this assessment by field checking 102 plots in North Carolina

and Tennessee. These plots represented both affected and

unaffected plots diagnosed in the dormant and growing

seasons (table 2). These states were selected because the

inventories were the most recently completed at the time of

validation and, therefore, least likely to have changed condition over time. Field checks were conducted during the

growing season after the statewide inventories were

completed (approximately 2-10 months).

RESULTS

Validation

Individual tree coding by FIA field crews for presence or

absence of dieback was correct for 89 percent of the cases

(table 3). Accuracy was highest for unaffected trees than for

affected overall, with no errors found for unaffected trees

diagnosed in the dormant season. Affected trees evaluated

in the dormant season were the most difficult for field crews

to diagnose, though some of these apparent errors of

omission could have been due to dieback that developed

between the initial inventory and the validation effort. It is

less likely for dieback symptoms to have been lost or

masked in the short time between the initial inventory and

validation.

Table 1—Forest Inventory and Analysis forest types and forest-type groups

included in host type for oak decline analysis

Physiographic Forest-type

type group Forest type

Upland Oak-hickory Post oak-black oak-bear oak

Chestnut oak

White oak-red oak-hickory

Northern red oak

Yellow-poplar–white oak–northern red oak

Southern scrub oak

Mixed hardwoods

Oak-pine White pine-northern red oak-white ash

Eastern redcedar-hardwood

Longleaf pine-scrub oak

Shortleaf pine-oak

Virginia pine-southern red oak

Loblolly pine-hardwood

Slash pine-hardwood

Other oak-pine

Oak-gum-cypress Swamp chestnut oak-cherrybark oak

Sweetgum-Nuttall oak-willow oak

Overcup oak-pine

Table 2—Number of plots in Tennessee and

North Carolina used for dieback and oak

decline validation, by initial inventory season

and decline status

Inventory season Decline Unaffected

 - - - number of plots - - -

Growing 37 29

Dormant 14 22

Combined 51 51
238

1984-1989 Survey Period

The total area of host type was 114.7 million acres in the

twelve surveyed states (table 4). Alabama led the region

with 13 million acres, but there were six others with more

than 11 million acres each (Georgia, Arkansas, North

Carolina, Virginia, Tennessee, and Mississippi in decreasing

rank order). While the total host type acreage in the remaining states was no higher than 7 million acres (Florida), the

differences in host type acreage among states was probably due more to differences in total state land area, than to

density of host type plots.

Vulnerable host type totaled about 40 million acres. The

geographic distribution of these plots show more dense

concentrations in the Southern Appalachian Mountains of

Virginia, North Carolina, Tennessee, South Carolina, and

Georgia; along the eastern and western highland rim of

middle Tennessee; and in the Ozark-Ouachita highlands of

Arkansas and eastern Oklahoma (fig. 1). The regional distribution map showing plot locations is not one snapshot in

time, but rather a mosaic of snapshots due to the varying

inventory dates for each state.

The total area affected by oak decline was 3.6 million acres

during this survey cycle (table 4). Virginia had the largest

area (1.1 million acres). About 60 percent of the total

affected area was located in Virginia, Tennessee, and North

Carolina. Sampling error for affected area varied from 0.89

to 16.82 percent for all States, but was < 2 percent for each

of the top three.

Regional incidence (percent of vulnerable host type area

affected by decline) averaged 9.13 percent, but this was

highly variable among states. Virginia and Florida had

incidence approaching 20 percent, though Virginia had

nearly 4 times the vulnerable host type acreage of Florida.

Tennessee and North Carolina had incidence of about 12

and 10 percent, respectively, while Mississippi, Alabama,

Oklahoma, and Louisiana had incidence of 3 percent or

less. Relatively high densities of affected plots are located

in northern Virginia, western North Carolina, the western

highland rim of middle Tennessee, and in the northern

Arkansas highlands (fig. 2.)

1990-1997 Survey Period

Host type area totaled 104.7 million acres during this period

(table 5), a decrease of over 10 million acres since the

earlier inventories. Florida experienced the greatest loss

(3 million acres), but Georgia, North Carolina, and South

Carolina each lost in excess of 1 million acres. Loss of host

type could be due to diversion of former timberland to nonforest uses, such as urbanization; or change from oak dominated forest to a different forest type through management

actions or natural forest dynamics (i.e., succession).

Table 3—Validation of dieback and decline status

of Forest Inventory and Analysis plots in

Tennessee and North Carolina

Season of Decline Unaffected

inventory plots plots Both

 - - - - - - - percent correct - - - - - - -

 Individual tree dieback coding

Growing 84 93 88

Dormant 79 100 92

Combined 83 96 89

 Stand decline classification

Growing 84 83 83

Dormant 86 77 81

Combined 84 80 82

Table 4—Area and incidence of oak forest type affected by oak decline, 1984–89

Vulnerable Inventory

State Host type host type Affected Incidence year

acres no. plots acres no. plots acres no. plots percent

Alabama 13,032.5 2,244 4,169.9 718 138.1 24 3.31 1984

Arkansas 12,219.6 2,162 4,758.9 836 289.5 51 6.08 1988

Florida 7,306.4 2,711 1,522.0 568 296.0 114 19.45 1987

Georgia 12,526.3 3,501 4,058.7 1,250 341.2 69 8.41 1989

Louisiana 6,363.2 1,088 1,140.0 195 16.3 3 1.43 1984

Mississippi 11,112.2 1,917 2,465.3 422 93.7 16 3.80 1987

North Carolina 11,913.9 3,510 4,259.7 1,135 422.6 100 9.92 1984

Oklahoma 3,581.0 600 2,005.2 331 29.6 5 1.48 1986

South Carolina 6,606.5 2,378 2,133.8 730 139.9 51 6.56 1986

Tennessee 11,328.4 1,944 5,596.8 963 651.0 114 11.63 1989

Texas 6,843.0 1,137 1,873.3 308 99.2 16 5.30 1986

Virginia 11,887.3 3,327 5,802.3 1,515 1,114.4 272 19.21 1986

Total 114,720.3 26,907 39,785.9 8,852 3,631.5 871

Overall

incidence 9.13
239

Figure 1—Geographic distribution of vulnerable host type plots for 12 Southern States, 1984-1989.

Figure 2—Geographic distribution of affected plots for 12 Southern States, 1984-1989.

Despite the loss of host type, vulnerable host type increased

by 3.7 million acres regionwide. Arkansas registered the

largest increase among the 12 states, almost 2 million

acres, and led the region in total vulnerable host type area

with 6.7 million acres. Virginia, Tennessee, and Alabama

each had more than 4 million acres of vulnerable host type,

but other large increases were noted in Mississippi,

Louisiana, and Texas (1.4, 1.0, and 0.9 million acres, respectively). Geographic patterns similar to those observed in the

earlier inventory were also seen during this period (fig. 3).
240

Figure 3—Geographic distribution of vulnerable host type plots for 12 Southern States, 1990-1997.

Area affected by oak decline totaled 4.4 million acres, up

0.8 million acres since the previous inventory. Virginia

affected area remained almost the same (1.1 million acres

in both inventories), but large changes occurred in North

Carolina, Arkansas, and Tennessee. Despite a decrease in

vulnerable host type in North Carolina, affected area nearly

doubled to 0.8 million acres. In Arkansas, the large increase

in vulnerable host type was mirrored by an increase in

affected area of more than double, while in Tennessee,

vulnerable host type remained the same and affected area

decreased to half the area reported for the earlier inventory

period. As for the earlier survey period, sampling error was

low for the top three States in affected area.

Regional incidence increased slightly to 10.13 percent.

Incidence in Virginia remained close to 20 percent, while

incidence in North Carolina almost doubled to a similar

figure. As in the earlier inventory, about 60 percent of the

total affected area was represented by three states, with

Arkansas replacing Tennessee and joining Virginia and

Table 5—Area and incidence of oak forest type affected by oak decline, 1990–97

Vulnerable Inventory

State Host type host type Affected Incidence year

acres no. plots acres no. plots acres no. plots percent

Alabama 13,402.9 2,835 4,272.1 756 260.5 47 6.10 1990

Arkansas 12,252.4 2,081 6,734.2 1,145 707.0 121 10.50 1995

Florida 4,271.8 1,621 1,601.8 595 211.7 80 13.22 1995

Georgia 9,797.3 3,501 3,747.1 1,250 250.7 69 6.69 1997

Louisiana 6,317.3 1,106 2,174.4 385 167.0 31 7.68 1991

Mississippi 11,381.5 1,930 3,900.6 659 203.4 37 5.21 1994

North Carolina 9,280.8 2,711 3,861.3 1,040 754.3 178 19.53 1990

Oklahoma 3,602.1 593 1,960.9 321 135.5 21 6.91 1992

South Carolina 5,106.6 1,798 1,809.8 611 164.0 55 9.06 1993

Tennessee 11,343.3 2,672 5,176.6 1,126 357.5 74 6.91 1997

Texas 6,962.7 1,197 2,763.4 476 105.8 19 3.83 1992

Virginia 10,945.6 2,960 5,510.1 1,413 1,090.5 268 19.79 1992

Total 104,664.3 24,555 43,512.3 9,777 4,407.9 1,000

Overall

 incidence 10.13
241

Figure 4—Geographic distribution of affected plots for 12 Southern States, 1990-1997.

North Carolina in the more recent inventory. Florida had

high incidence in both inventories, but relatively low host

type, vulnerable, and affected areas. The density of affected

plots remained high in northern Virginia, but appeared to

have intensified between inventory periods in western North

Carolina and the Ozark-Ouachita highlands of Arkansas

and Oklahoma. By contrast, affected plot density appeared

to decrease in eastern Tennessee and the western highland

rim (fig. 4).

DISCUSSION

Virginia, North Carolina, and Tennessee had consistently

large oak decline affected area in the inventories conducted

between 1984 and 1997, ranking in the top four among the

12 states in both inventories. Together they accounted for

about 60 percent of the total affected area in the region.

Florida had among the highest oak decline incidence during

the period, but this was applied against vulnerable host

type area that was the smallest among the states evaluated.

The aging and growth of upland hardwood forests in

Arkansas resulted in large increases in vulnerable host type,

and affected area over the inventory period. Vulnerable

host type increased about 1.5 times between 1988 and

1995, while affected area increased about 2.5 times from

290,000 acres to 707,000 acres. This change captured by

the 1995 inventory represents the beginning of the current

unprecedented oak decline episode in the Ozark-Ouachita

highlands. The earliest reports of the current episode were

not made until about four years later in 1999 (Starkey and

others 2000).

FIA inventories are useful for evaluating oak decline incidence and distribution. Other conditions can result in dieback

that does not constitute oak decline. However, the presence

of dieback symptoms in dominant and codominant oak trees

in combination with the forest types, predominant tree size

classes, and oak densities we recognized reliably represented oak decline. Future work will present finer spatial

resolution of these data by breaking out individual survey

units within states and by application of nearest neighbor

statistical tools to individual plots.

Changes in methods instituted since the 1997 inventory

cycle have made future analysis by these methods obsolete. New procedures will have to be developed for use with

the new sampling designs. As long as the dieback symptom

is recognized and recorded, oak decline analyses with FIA

data sets will be possible.

LITERATURE CITED

Balch, R.E. 1927. Frost kills oak. Journal of Forestry. 24: 949-950.

Bassett, E.N.; Fenn, P.; Mead, M.A. 1982. Drought-related oak

mortality and incidence of Hypoxylon canker. Arkansas Farm

Research 31(1): 8.

Beal, J.A. 1926. Frost killed oak. Journal of Forestry. 24: 949-950.

Hansen, M.H.; Frieswyk, T.; Glover, J.F.; Kelly, J.F. 1992. The

Eastwide forest inventory data base: users manual. Gen. Tech.

Rep. NC-151, St. Paul, MN: U.S. Department of Agriculture,

Forest Service, North Central Forest Experiment Station. 48 p.

Manion, P.D. 1991. Tree disease concepts. Second ed. PrenticeHall, Englewood Cliffs, NJ. 328-348.

Millers, I.; Shriner, D.S.; Rizzo, D. 1988. History of hardwood

decline in the Eastern United States. Gen. Tech. Rep. NE-126.

Broomall, PA: U.S. Department of Agriculture, Forest Service,

Northeastern Forest Experiment Station. 75 p.
242

Oak, S.W.; Huber, C.M.; Sheffield, R.M. 1991. Incidence and

impact of oak decline in western Virginia, 1986. Resour. Bull.

SE-123. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station. 16 p.

Oak, S.W.; Starkey, D.A.; Ishikawa, P. 1990. Application of color

infrared aerial photography for detecting oak decline damage

and change in southern forests. In: Greer, J.D., ed. Protecting

Natural Resources with Remote Sensing- Proceedings of the

Third Forest Service Remote Sensing Applications Conference.

Bethesda, MD: American Society for Photogrammetry and

Remote Sensing: 95-107

Sheffield, R.M.; Dickson, J.G. 1998. The South’s forestland—on

the hot seat to provide more. Proc. N. Amer. Wildl. and Natural

Res. Conf.: 63: 316-331.

Starkey, D.A.; Mangini, A.; Oliveria, F.L. [and others]. 2000. Forest

health evaluation of oak mortality and decline on the Ozark

National Forest, 1999. Rep. No. 2000-02-02. Alexandria, LA:

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

State & Private Forestry, Forest Health Protection. 31 p.

Starkey, D.A.; Oak, S.W.; Ryan, G.W. [and others]. 1989.

Evaluation of oak decline areas in the South. U.S. Department

of Agriculture, Forest Service, Southern Region. Atlanta, GA.

Prot. Rep. R8 PR-17. 39 p.

Stringer, J.W.; Kimmerer, T.W.; Overstreet, J.C.; Dunn, J.P. 1989.

Oak mortality in eastern Kentucky. Southern Journal of Applied

Forestry. 13: 86-91.

Tainter, F.H.; Retzlaff, W.A.; Starkey, D.A., Oak, S.W. 1990.

Decline of radial growth in red oaks is associated with shortterm changes in climate. Eur. J. For. Path. 20: 95-105.

U.S. Department of Agriculture, Forest Service. 1984. Field survey

inventory work plan, Texas/Oklahoma 1985. Starkville, MS:

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

Forest Experiment Station, Forest Inventory and Analysis Work

Unit. 95 p.

U.S. Department of Agriculture, Forest Service. 1985. Field

instructions for the Southeast. [Unnumbered]. Asheville, NC:

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

Forest Experiment Station, Forest Inventory and Analysis Work

Unit. 165 p.
243

INTRODUCTION

The forested Ozarks are generally believed to represent as

a source region for Neotropical migrants compared to

fragmented areas to the east and north that have become

population sinks (Donovan and others 1995, Robinson and

others 1995, Howell and others 2000), with higher

reproductive success among the more common Neotropical

migratory species (> 50 percent, Li 1994). Relatively few

studies have been conducted on breeding birds in

undisturbed, upland hardwood forests of Arkansas (e.g.,

James 1971, Shugart and James 1973, Smith 1977) and

almost no studies have examined birds in migration or

during winter (James and others 1981, Rodewald 1995).

More commonly, studies have been conducted on avian

responses to forestry practices (e.g., Thompson and others

1992, Annand and Thompson 1997, Rodewald and Smith

1998), fragmentation (e.g., Donovan and others 1995), or

insect outbreaks (Williams and others 1993, Nagy and

Smith 1997, Smith and Stephen, in press).

The Ozark Mountains and Oak/Hickory Forest

Ecosystem

Braun (1950) first coined the term “Interior Highlands” in

referring to the forested Ozark and Ouachita mountains.

Whereas the Ouachita Mountains are primarily forested

with pines mixed with hardwoods, the Ozark Mountains are

the western edge of the eastern deciduous forest (Braun

1950), having compositional affinities with forests stretching

east through Ohio, Pennsylvania, and into southern New

England (Whitney 1994: fig. 4.3).

The pre-settlement forest in some parts of the Ozarks was

nearly a monoculture of majestic white oaks (Quercus

alba), with canopies barely touching, first branches 3-5 m

from the ground, and a grass understory (see Braun 1950,

Beilman and Brenner 1951). Other forested habitats

included bottomland hardwoods in river drainages and

cedar glades in drier areas, with significant amounts of pine

in southeastern Missouri (Widmann 1907). Both red

(subgenus Erythrobalanus) and white (Leucobalanus) oaks

were common in the Arkansas Ozarks at the time of

settlement (Foti and Heitzman, in press). However, the

Ozarks were clear-cut in the period 1880-1900, primarily for

railroad ties for the western United States (reviewed in

Smith and Petit 1988). The resulting forest today is a nearly

even-aged mixture of oaks, hickories, maples, and other

deciduous species with some pine in the southern portions.

Given the even-aged closed canopy, there generally is little

or no shrub layer development and the ground cover is

predominately poison ivy (Rhus radicans). Shelford

(1963:59) referred to the Missouri and Arkansas Ozarks as

the largest forest of oak and hickory without pine in North

America and the Ozarks currently have the highest density

of oaks in the United States (McWilliams and others 2002).

The Arkansas Ozarks are over 90 percent forested today,

and about 75 percent of the forest is composed of a variety

of oak-dominated habitats (Smith and others 1998). Based

on slope and aspect, it is sometimes useful to separate

north-facing slopes into mesic upland and south-facing

slopes into xeric upland forests (e.g., James 1971, Smith

1977). According to a U.S. Department of Agriculture,

Forest Service 1995 Forest Survey, red oaks (subgenus

Erythrobalanus) comprise 46 percent of the live-tree

volume, 42 percent of growing stock volume, and 35

percent of sawtimber volume of Arkansas timberland (J.M.

Guldin, F. Oliveria, and M. Spetich. 2001. Research

considerations in the red oak borer epidemic of 2001—

suggested research strategy. Unpublished report. On file

BIRDS OF UPLAND OAK FORESTS IN THE ARKANSAS OZARKS:

PRESENT COMMUNITY STRUCTURE AND POTENTIAL IMPACTS OF

BURNING, BORERS, AND FORESTRY PRACTICES

Kimberly G. Smith, Michael Mlodinow, Janet S. Self,

Thomas M. Haggerty, and Tamara R. Hocut1

1 Professor of Biology and Research Associate, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701; District

Wildlife Biologist, USDA Forest Service, Ozark National Forest, Buffalo Range District, Jasper, AR 72641; Professor of Biology, Department

of Biology, University of North Alabama, Florence, AL 35632-0001; and GIS Coordinator, USDA Forest Service, Ozark National Forest,

Buffalo Range District, Jasper, AR 72641, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Based on published works, our own research, and the U.S. Forest Service’s R8 Bird database, we characterize breeding bird communities in mesic and xeric upland hardwood forests of the Arkansas Ozarks. Although 59 species

have been recorded as breeding, typical breeding assemblages in mesic forests are 20-25 species, with only 5 species

commonly found in xeric forests. Due to changes in forest composition, the breeding assemblages of today were probably

rare or absent from the Ozarks 150 years ago. Any forestry practice that opens the closed canopy increases the number of

species in upland hardwood forests. Development of a shrub-layer allows a difference suite of birds to occupy the forest,

which typically would be unsuitable habitat for them. Relatively few birds occur in upland forest in fall migration and

especially winter, but many migrants use this habitat in spring. The recent decline in oaks due to the borer infestation may

dramatically change the avifauna of this upland habitat. Prescribed burning in deciduous forests may also have positive

and negative effects, which need further investigation. Cowbirds do not occur in upland forests, and their spread should

be limited by the lack of feeding sites.
244

with: U.S. Department Of Agriculture, Forest Service, Hot

Springs, AR 71901). Thus, much of the Arkansas Ozarks

are covered with oaks, and red oaks, the more numerous

subgenus, are of great commercial value to the economy

of the state. Currently, however, the forests of the Ozark

Mountains in Arkansas and Missouri are experiencing a

remarkable outbreak of a native, normally endemic insect

species, the red oak borer, Enaphalodes rufulus (Haldeman)

(Coleoptera: Cerambycidae). By the end of 2001, the U.S.

Forest Service estimated > 400,000 ha of forest in the Ozark

Mountains were being impacted by this outbreak.

In this paper, we first characterize the breeding bird communities of the xeric and mesic upland hardwood forests of the

Arkansas Ozarks, and present some data on birds present

in spring and fall migration and during winter. We then present results of our research on effects of various forestry

practices on breeding bird communities. Based on those

results, we speculate on the effects of the current red oak

borer outbreak on bird community structure. Potential

impacts on bird communities from other sources, such as

prescribed burning and cowbirds, are also discussed.

METHODS

Data reported here were compiled from four primary sources:

two studies conducted by the authors that examined effects

of various forest practices on bird community structure, data

collected by the U.S. Forest Service on the Ozark National

Forest in conjunction with their R8Bbird monitoring program,

and theses, dissertations, and published works by graduate

students at the University of Arkansas over the last 30 years.

Fleming Creek

In 1982 and 1983, the U.S. Forest Service’s Silviculture and

Hydrology Laboratories, at the time located in Fayetteville,

AR, began a study of the impacts of 3 forest management

practices on hydrology of 4 watersheds (one was a control)

that drain into Fleming Creek, in north central Franklin

County, AR, just south of the Madison County line.

One watershed (FC1, 11.3 ha) was a “conversion to pine”

treatment. Both loblolly (Pinus palustris Mill.) and shortleaf

(P. echinata Mill.) pine seedlings were planted in February

and March of 1982 prior to herbicide application. Loblolly

pines were planted on sites with more northerly aspects

while shortleaf pines were planted on southerly aspects. No

harvesting was done in this watershed, but existing hardwoods were killed via Velpar application (liquid squirted on

1.2 x 1.2 m spacing) in 1982 and Tordon 101 injection in

1983 and left standing.

Another watershed (FC3, 5.9 ha) was a shelterwood harvest, in which the existing stand was thinned to 56-60 percent of original basal area in 1982. Merchantable hardwood

trees were cut during thinning and remaining, undesirable

hardwoods (e.g., dogwoods, redbuds) were injected with

Tordon 101. All work was completed in 1982.

The third watershed (FC4, 6.9 ha) was clearcut and all merchantable timber was removed, smaller trees of desirable

species (e.g., oaks, hickories) were severed close the ground

to promote sprout regeneration, and undesirable trees were

injected with Tordon 101. All work was completed in 1982.

A fourth watershed (FC2, 13.3 ha) was designated as a control. No disturbance of any kind occurred in this watershed.

Monthly bird censusing began in all 4 watersheds in October

1983 and continued through September of 1984, with additional censuses in November 1984 and February, March,

April, May, July and September of 1985, for a total of 18

censuses. Due to the small size of watersheds, a circular

trail was established in each watershed and each census

lasted approximately 1 hr, during which the observer would

record all birds seen or heard on the plot while walking the

trail, care being taken not to count individuals more than

once. On each census day, two observers randomly chose

2 plots each and the direction to walk on the trail (i.e., clockwise or counter-clockwise). Censuses were begun at 10:00

and the 2 censuses by each observer were usually completed

by 12:30. Data were grouped by season: spring (April – May,

n = 4), summer (June – August, n = 3), fall (September –

November, n = 5), and winter (December – March, n = 6).

Ozark National Forest Study

In 1993, a long-term project was initiated to study the

effects of various management practices in oak-hickory

forests within the Ozark National Forest. During 1993, two

study areas were established (Williams Hollow and Gulf

Branch) in anticipation of future harvesting, and an additional 3 study areas (Swain, Barberry, and Junction) were

established in 1994.

Since 1993, 10-minute fixed-radius point-counts (Hutto and

others 1986) have been conducted 4 times each summer at

each study area during early June through early July. All

species seen or heard within a 50-m radius of the center of

the plot were recorded. Points were at least 150 m apart. All

censuses were conducted by M. Mlodinow, who attempted to

census plots on nearly the same days each year. However,

censuses have not been performed on rainy or windy days.

Williams Hollow—Censusing began in summer of 1993 on

sixteen 50-m radius circles. During fall of 1993, harvesting,

which consisted of group selection cutting, was completed

at the site by November of that year. Fourteen of the 16 circles were within the harvested area; two circles were approximately 75 m from the edge of the cut area, but were included

in the analysis because they probably were influenced by

the harvesting operation. Most of the uncut area was

thinned between the 1998 and 1999 field seasons.

Gulf Branch—Censusing began during summer of 1993 on

twelve 50-m radius circles. Between 17 and 24 June 1994,

a logging road was established in the study area, possibly

directly affecting one circle. Prior to censusing in 1995,

logging, which consisted of shelterwood harvesting, was

begun and was completed during fall of 1995. No logging

activities were observed during censusing in summer of

1995. Prior to the 1997 field season, site preparation activities were completed, during which most of the understory

was cut, creating scattered brushpiles. Six circles were

within the area receiving all treatments and 6 circles were

at least 100 m outside the treatment area.

Junction—Censusing began in 1994 on eight 50-m circles.

During summer of 1996, group selection harvesting was
245

begun in mid-June prior to the last census and was

completed in fall of 1996. Site preparation was 50 percent

completed by March 1997.

Swain and Barberry—Censusing began in 1994 at Swain

on six 50-m circles. This area was harvested in a group

selection cut between the 1999 and 2000 field seasons, so

we considered data collected between 1994 through 1999 as

undisturbed forest. Censusing began in 1994 at Barberry

on six 50-m circles. This area has not been sold for harvest

and serves as a control for the other plots.

University of Arkansas Studies

The first seminal work done on habitat selection of birds in

the Arkansas Ozarks was by Francis James (1971). Not

only did this reveal important habitat relationships of birds

in the Arkansas Ozarks, it introduced the use of multivariate

statistics to the ornithological world. Hank Shugart (Shugart

and James 1973) conducted thesis research examining

changes in bird community structure along a successional

gradient at the Pea Ridge National Monument, Benton

County, AR. Unfortunately, his mesic upland forest plot was

only 2.8 ha in size, limiting the usefulness of those data.

Kimberly Smith (1977) conducted his thesis research in

Leatherwood Cove, Newton County, AR, comparing the distribution of species along a moisture gradient on north- and

south-facing slopes in what was then a part of the Buffalo

National River. Douglas James lead an NSF-funded undergraduate research project on the fauna of the Buffalo National

River during summer of 1977 and winter of 1978 (James

and others 1981). Pingjun Li (1994) examined reproductive

ecology of 11 species of forest birds in the Ozark National

Forest in Franklin County as part of his doctoral research.

Paul Rodewald (Rodewald 1995, Rodewald and Smith

1998) examined effects of understory removal and selective

cutting of the canopy on 26 species of birds in the eastern

part of the Ozark National Forest (northern Pope and southern Newton cos.). Smith and long-time collaborator Frederick

Stephen (Smith and Stephen In press) speculate on the

impact of the current red oak borer on bird community

structure in the Arkansas Ozarks.

U.S. Forest Service R8 Bird Data

Beginning in 1996, the Ozark-St. Francis National Forest

implemented a landbird monitoring program within the Ozark

National Forest. A total of 61 mesic upland hardwood plots,

corresponding to habitats 53,54,55,69 and 81 in Hamel

(1991) and 20 xeric upland hardwood plots, corresponding

to habitats 51, 57, and 99 in Hamel (1991), were established

throughout the national forest. Between 1997 and 2001,

point counts (Hamel and others 1996) were conducted

primarily by John Andre, Steve Duzan, Wayne King, Steve

Osborne, Frank Palmer, and Glen Thomas. The resulting

11,630 records of individual birds during those 5 years are

available in the R8Bird database (Trani and Belcher 2002).

Species Occurrence and Analysis

Birds were characterized as common, rare, or present by

the following criteria. All species studied by James (1971)

were by definition “common.” Shugart and James (1973)

presented densities of males per 40-ha and noted the

presence of other species. Birds with densities of 5 or fewer

males per 40-ha were considered rare and those over 5

males per 40-ha were considered common. Smith (1977)

presented a discriminant function analysis that ordinated

samples along a moisture gradient. Birds at Fleming Creek

were considered common if more than 5 sightings occurred

on the 3 censuses. Species were present if seen once and

rare if seen 2 to 5 times. Birds at Swain and Barberry were

common if seen each year, rare if not seen every year, and

present if only seen one or two years. Species in the R8Bird

database were considered common if more than 20 individuals were recorded, rare if more than 5 but fewer than

20 individuals were recorded, and present if 4 or fewer

individuals were recorded.

For the Fleming Creek watersheds, we compared richness,

species diversity (H), and equitability (J) for all time periods

and for the breeding season, using PROC GLM and

Duncan’s multiple range test in SAS (SAS Institute, Inc.,

Cary, NC). Overall similarity of the watersheds was

calculated using the method described by Wolda (1981).

RESULTS

Breeding Bird Community Structure

A total of 59 species have been reported as breeding in

upland hardwood forests in the Arkansas Ozarks (table 1),

including Sharp-shinned Hawk (Accipiter striatus), Eastern

Screech-Owl (Otus asio) and Whip-poor-will (Caprimulgus

vociferous) reported by Rodewald (1995). A total of 25

species are permanent residents and 34 are migrants, but

most species are either rare or present. Common resident

species in mesic upland forests include Downy Woodpecker,

Pileated Woodpecker, Tufted Titmouse, and White-breasted

Nuthatch and possibly Red-bellied Woodpecker, Blue Jay,

and American Crow. Common breeding migrants include

Yellow-billed Cuckoo, Eastern Wood-Pewee, Acadian

Flycatcher, Red-eyed Vireo, Blue-gray Gnatcatcher, Wood

Thrush, Black-and-white Warbler, Worm-eating Warbler,

Ovenbird, Hooded Warbler, and Scarlet Tanager. Thus, the

typical avian breeding assemblage in a mesic upland forest

in the Arkansas Ozarks is around 20-25 species (Shugart

and James 1973, James and others 1981, Rodewald and

Smith 1998). Only 5 species, Red-eyed Vireo, Tufted

Titmouse, Blue-gray Gnatcatcher, Ovenbird, and Indigo

Bunting, commonly occur in xeric upland hardwood forests

in the Arkansas Ozarks during summer.

Winter Bird Community Structure

Upland hardwood forests are nearly birdless during winter.

Of the 10 species seen during winter at Fleming Creek, 8

were seen only once or twice – Cooper’s Hawk (Accipiter

cooperii), Red-tailed Hawk, American Crow, Carolina

Chickadee, Downy Woodpecker, Red-bellied Woodpecker,

White-breasted Nuthatch, and Yellow-rumped Warbler.

Pileated Woodpeckers were seen 4 times and 15 American

Goldfinches were counted.

Migration in Upland Hardwood Forests

Rodewald (1995) reported 32 species of non-breeding

migrants during spring (late April-May) of 1993 and 1994 on

his study sites in eastern Ozark National Forest (table 2).

Only 8 non-breeding migrants were seen on the control

watershed at Fleming Creek during spring migration (table 2).
246Table 1—Birds reported in relatively undisturbed upland hardwood forests during the breeding season in the Arkansas Ozarks

James Shugart and Smith Fleming Swain/ Forest Service

(1971) James (1973) (1977) Creek Barberry R8.bird

Species Scientific name Mesic Xeric Mesic Xeric Mesic Mesic Mesic Xeric MesicTurkey vulture* Cathartes aura P P

Red-shouldered hawk* Buteo lineatus P

Broad-winged hawk B. platypterus P P

Red-tailed hawk* B. jamaicensis P P

Wildturkey* Megeagris gallopavo P P

Mourning dove* Zenaidura macroura R PP

Yellow-billed cuckoo Coccyzus americanus C P C RC

Great horned owl* Bubo virginianus PP P

Barred owl* Strix varia P

Common nighthawk Chordeiles minor P P

Chuck-will’s-widow Caprimulgus carolinensis P PChimney swift Chaetura pelagica P P

Ruby-throated hummingbird Archilochus colubris R P PPRed-bellied woodpecker* Melanerpes carolinus CR R R R

Downy woodpecker* Picoides pubescens C R CP R CHairy woodpecker* P. villosus R R PR

Northern flicker* Colaptes auratus R PPPileated woodpecker* Dryocopus pileatus P R C CC

Eastern wood-pewee Contopus virens C C C C CC

Acadian flycatcher Empidonax virescens C C CC C P CEastern phoebe Sayornis phoebe P P

Great crested flycatcher Myiarchus crinitus CR C P P

White-eyed vireo Vireo griseus C P

Yellow-throated vireo V. flavifrons C RR

Red-eyed vireo V. olivaceus CR C C C C C C CBlue jay* Cyanocitta cristata C P C RR

American crow* Corvus brachyrhynchos R CC

Fish crow* C. ossifragus P

Carolina chickadee* Poecile carolinensis C RR

Tufted titmouse* Baeolophus bicolor CC C C C C R C

White-breasted nuthatch* Sitta carolinensis CR R R C R C R CCarolina wren* Thryothorus ludovicianus C C R PRBlue-gray gnatcatcher Polioptila caerulea C C R CR R C C

Wood thrush Hylocichla mustelina C C R R PC

Gray catbird Dumetella carolinensis C

Northern parula Parula americana CC R

Black-throated green warbler Dendroica virens R

Yellow-throated warbler D. dominica P

 continued
247

Table 1—Birds reported in relatively undisturbed upland hardwood forests during the breeding season in the Arkansas Ozarks (continued)

James Shugart and Smith Fleming Swain/ Forest Service

(1971) James (1973) (1977) Creek Barberry R8.bird

Species Scientific name Mesic Xeric Mesic Xeric Mesic Mesic Mesic Xeric MesicPine warbler* D. pinus P PP

Cerulean warbler D. cerulea C R

Black-and-white warbler Mniotilta varia CC C R C R C

American redstart Setophaga ruticilla C

Worm-eating warbler Helmitheros vermivorus C P P RCOvenbird Seiurus aurocapillus C C CC C C C

Louisiana waterthrush S. motacilla P P

Kentucky warbler Oporornis formosus C RR R

Commonyellowthroat Geothlypis trichas P

Hooded warbler Wilsonia citrina C C C RC

Yellow-breasted chat Icteria virens P

Summer tanager Piranga rubra R PP

Scarlet tanager P. olivacea C C C C RC

Eastern towhee* Pipilo erythrophthalmus C PNorthern cardinal* Cardinalis cardinalis CC P R P P

Indigo bunting Passerina cyanea C R R CCBrown-headed cowbird* Molothrus ater P

American goldfinch* Carduelis tristis PP P

C = more common species; R = rarer species; P = species present on study site at least once (see text for full explanation).Names followed by * are permanent resident species.Where possible, the distinction is made between xeric and mesic upland forests. Data from Fleming Creek are from the control watershed during June and July. Data fromSwain are from 1994 through 1999; data from Barberry are from 1994 through 2002; data from R8.bird are from 1997 through 2001.
248

Very little is known about use of upland hardwood forests

during fall migration. Only 10 species were seen at Fleming

Creek during fall and 8 of them were permanent resident

species. One Ovenbird was observed along with 2 Brown

Creepers (Certhia americana).

Combining all seasons, there were no differences in richness or species diversity among the 4 watersheds at Fleming

Creek, but there was a significant difference in equitability

(or evenness), species being less evenly distributed in the

clear-cut (J = 0.80) than in the other 3 watersheds (J > 0.90

for all three) (F = 4.61, df = 3, 59, P = 0.006). During summer,

species diversity and average species richness were significantly higher in the selective-cut (H = 2.90, average number

of species per census = 22.0) compared to the other 3 watersheds (F = 8.65, df = 3, 8, P = 0.007 and F = 11.25, df = 3, 8,

P = 0.003). Overall similarity (Wolda 1981) of the 4 watersheds at Fleming Creek for all censuses was 26 percent,

suggesting that the plots are not very similar in species

composition.

Effects of Various Forest Practices on Breeding

Birds

Almost any forestry practice that disturbs the closed canopy

of an upland hardwood forest in the Arkansas Ozarks

increases the number of species present during the breeding season. At Fleming Creek, 21 species were found in the

control, but 24 were found in the clearcut, 29 in the selective cut, and 30 in the pine conversion. At Gulf Branch, there

were 32 species during the 3 years pre-cut and a total of 36

species present in the 7 years post-cut. At Williams Hollow,

there were 28 species the first year (pre-cut) and a total of

39 species during the 9 years post-cut. At Junction, there

were 29 species in the 3 years pre-cut and a total of 38

species in the 6 years of post-cut.

While several permanent resident species and some

migrants remained common (table 3), a new suite of birds

became common in the forests that had been subject to

harvest. These included Indigo Bunting, Carolina Wren,

Hooded Warbler, Kentucky Warbler, Northern Cardinal,

Table 2—Migrant species observed during spring on the control at Fleming Creek and

in the eastern part of the Ozark National Forest

Species Scientific name Fleming Creek Eastern ONF

Black-billed cuckoo Coccyzus erythropthalmus X

Red-headed woodpecker Melanerpes erythrocephalus X

Least flycatcher Empidonax ninimus X

“Trails” flycatcher E. trailii/alnorum X

Yellow-bellied flycatcher E. flaviventrus X

Ruby-crowned kinglet Regulus calendula X

Veery Catharus fuscescens X

Swainson’s thrush C. ustalatus X X

Gray-cheeked thrush C. minimus X X

Solitary vireo Vireo solitarius X

Warbling vireo V. gilvus X

Philadelphia vireo V. philadelphicus X

Blue-winged warbler Vermivora pinus X X

Golden-winged warbler V. chrysoptera X

Tennessee warbler V. peregrina X X

Orange-crowned warbler V. celata X

Nashville warbler V. ruficapilla X

Blackburnian warbler Dendroica fusca X X

Cape May warbler D. tigrina X

Magnolia warbler D. magnolia X

Yellow-rumped warbler D. coronata X X

Bay-breasted warbler D. castanea X

Blackpoll warbler D. striata X

Yellow warbler D. petechia X

Mourning warbler Oporornis philadelphia X

Canada warbler Wilsonia canadensis X

Wilson’s warbler W. pusilla X

American redstart Setophaga ruticilla X X

Rose-breasted grosbeak Pheucticus ludovicianus X

Dickcissel Spiza americana X

Bobolink Dolichonyx oryzivorus X

Orchard oriole Icterus spurious X

Baltimore oriole I. galbula X X

ONF = Ozark National Forest.

Source: Rodewald (1995).
249

Table 3—Birds reported in disturbed upland forests that have been subjected to herbicides and the planting of pines

(pine conversion), clearcutting, and shelterwood and group-selection harvesting regimesa

Pine

conversion Clearcut Shelterwood Group selection

Species Fleming Fleming Fleming Gulf Branch William’s Hollow Junction Swain

Turkey vulture* P

Wild turkey* P

Northern bobwhite* P

Yellow-billed cuckoo P P C C C R

Chuck-will’s-widow R

Chimney swift P

Ruby-throated hummingbird C C C R R R R

Red-bellied woodpecker* R R R R R

Downy woodpecker* R R C C C C C

Hairy woodpecker* R R R C R R

Pileated woodpecker* P R C C R P

Eastern wood-pewee C C R C C C C

Acadian flycatcher R R C R C

Eastern phoebe C R P P

Great crested flycatcher P P

White-eyed vireo P P C C

Yellow-throated vireo P C R R R R

Red-eyed vireo C C C C C C

Blue jay* R R R C C R

American crow* C C R R

Carolina chickadee* P R R C C C C

Tufted titmouse* R R C C C C

White-breasted nuthatch* R C C C C

Carolina wren* P R C C C C

House wren P

Blue-gray gnatcatcher R P C C C C

Eastern bluebird* R P R P P

Wood thrush P R R R

American robin* P P

Cedar waxwing* P P

Blue-winged warbler R

Northern parula P R

Chestnut-sided warbler R

Pine warbler* R R

Cerulean warbler P

Black-and-white warbler P C C C C R

Worm-eating warbler P R C R R

Ovenbird P R C C C C

Louisiana waterthrush P P P

Kentucky warbler C R R R C C R

Common yellowthroat P

Hooded warbler C R C C C C C

Yellow-breasted chat R C R R

Summer tanager P R R

Scarlet tanager R R C C C C C

Eastern towhee* C C R C C C P

Field sparrow P

Northern cardinal* P R C C C R

Blue grosbeak R R P P

Indigo bunting C C C C C C C

Brown-headed cowbird* P P R P R C P

American goldfinch* C C C R R R R

C = more common species; R = rarer species; P = species present on study site at least once (see text for full explanation).

Names followed by * are permanent resident species.

a All these studies have occurred in rather mesic situations. The Fleming Creek data are based on three censuses conducted in June and

July of 1984 and 1985; the Gulf Branch data are based on point-counts done each summer from 1996 through 2002; the William’s Hollow

data are based on point-counts from 194 through 2002; the Junction data are from point-counts conducted from 1997 through 2002; and the

Swain data are from point-counts conducted from 2000 through 2002.
250

Eastern Towhee, Eastern Wood-Pewee, and White-eyed

Vireo. Other species not normally associated with mature

forests also appeared in small numbers: Blue Grosbeak

(Vermivora pinus), Chestnut-sided warbler (Dendroica

pensylvanica), Blue-winged Warbler, Yellow-breasted Chat,

and Eastern Bluebird (Sialia sialis). Brown-headed

Cowbirds have a greater presence in disturbed forest (table

3) compared to undisturbed forests (table 1).

DISCUSSION

The breeding birds found in upland deciduous forest of the

Arkansas Ozarks form a distinct group (James 1971),

composed of obligate mesic forest species, such as

Acadian Flycatcher, Wood Thrush, Worm-eating Warbler,

Cerulean Warbler, Ovenbird, Black-and-white Warbler, and

Scarlet Tanager, and other more wide-ranging species,

mostly permanent residents that tend to have higher

population densities (Shugart and James 1973, Smith

1977, Rodewald and Smith 1998). Members of that later

group would include Carolina Chickadee, Tufted Titmouse,

Pileated and Downy woodpeckers, and White-breasted

Nuthatch. No introduced or exotic species have invaded

this particular habitat.

In a typical upland hardwood forest in the Arkansas Ozarks,

most migratory breeders and permanent resident species

nest in the canopy or in tree trunks, a few migratory species

nest on the ground (e.g., Ovenbird and Black-and-white,

Kentucky, and Worm-eating warblers) and only one species

nests in shrubs (Hooded Warbler). Given the relatively

even-age structure of those upland forests, the canopy is

closed and there is very little development of a shrub layer.

For example, Acadian Flycatchers commonly sally for

insects between the bottom of the canopy and above the

forest floor within the forests of the Ozarks (Smith 1977).

However, opening the canopy and allowing light to

penetrate to the forest floor quickly (i.e., with 1 or 2 years)

allows for development of a shrub layer (Rodewald and

Smith 1998), which becomes an almost impenetrable

thicket within 5 to 10 years. Even relatively small openings

may have an impact on forest birds (Annand and

Thompson 1997) and development of the shrub layer may

attract new species (e. g., White-eyed Vireo, Blue

Grosbeak, Indigo Bunting) not normally associated with

mature forested habitats (Thompson and others 1992,

Annand and Thompson 1997, Rodewald and Smith 1998).

Opening of the forest canopy either immediately (Kendeigh

1982) or eventually (Rabenold and others 1998) allowed

early successional bird species to colonize new areas that

previously were unsuitable habitats (see also Thompson

and others 1992). Rodewald and Smith (1998) concluded

that removal of understory vegetation could negatively

affect some ground-nesting and shrub-nesting forest

interior species, whereas edge species might react

positively. Similarly, Gram and others (2001) recently

documented short-term changes in bird community

structure in the Missouri Ozarks with an estimated change

of only < 10 percent of the canopy structure. Fragmented

forests in Missouri actually have more species than

contiguous forests, but the abundance of Neotropical

migrants that breed in mature forests is greatly reduced in

the fragmented forests (Howell and others 2000).

Xeric upland hardwood forests had fewer breeding species

than did mesic upland forests (table 1). At Pea Ridge

National Monument, densities in xeric forest were about

100 males per 40-ha compared to nearly 400 males per-40

ha (Shugart and James 1973). Upland hardwood forests

contain very few species in winter and our data suggest

that fall migration may be meager in that habitat. It would

appear that upland hardwood forests in the Arkansas

Ozarks have a substantial migration in spring, which

warrants further study. Rodewald (personal communication)

also felt that numbers of birds in spring migration were

higher on his study plots in the eastern Ozarks than in the

western edge around Fayetteville.

Given the descriptions of the pre-settlement forests of the

Ozarks (Braun 1950, Beilman and Brenner 1951, contra

Steyermark 1959), these upland assemblages must be of

recent origin, commonly occurring together in these forests

for maybe only the last 150 years. The recent expansion of

these upland forest types in the Ozarks may explain why

fewer species breed here than in areas further to the east.

Indeed it would appear that xeric upland hardwood forests

in the Ozarks have the least number of breeding species

than any other forest type in the eastern deciduous forest.

Smith (1977) suggested that the recent appearance of the

xeric upland forest may explain the low number of breeding

species. The recent expansion of the Black-throated Green

Warbler (Rodewald 1997), and possibly of Cooper’s and

Sharp-shinned (Accipiter striatus) hawks, would suggest

that new species are still being added to the avifauna of the

Arkansas Ozarks.

Impact of Elimination of Red Oaks by Red Oak

Borers

Many forest insect species that have become unique and

distinctly significant disturbance factors in relatively

unmanaged native forests are exotics. The red oak borer,

however, is a native insect species in eastern North

America (Donley and Acciavatti 1980) that attacks living

oak trees. Population levels of the epidemic magnitude

currently being reported in the Ozark Mountains have never

been witnessed within the range of this species. Typically

red oak borer infestations have been local and they

previously have been considered as an unimportant insect

pest in oak forests (Oak 2002).

As reviewed in Smith and Stephen (In press), factors

involved with the current outbreak include advanced age of

stands (70-100 years); xeric conditions associated with

shallow rocky soils, exacerbated by three years of drought;

and appearance of two fungi, one attacking roots and one

attacking above ground, all of which weaken the trees’

resistance to attack by red oak borers. Coincident with that

opinion is the idea that the logging history of the region,

which consisted of continuous high grading of the forests

during the early 1900s, resulted in stands that are

frequently dominated by red oaks of similar age structure

(Ozark-St. Francis National Forests 1978).

Based on research presented here and other published

works, Smith and Stephen (in press) predicted that populations of 10 of 20 migratory species (Yellow-billed Cuckoo,

Acadian Flycatcher, Red-eyed Vireo, Wood Thrush, Black-
251

throated Green Warbler, Cerulean Warbler, Worm-eating

Warbler, Ovenbird, Louisiana Waterthrush, Scarlet Tanager)

will decline, and only 6 forest species were predicted to

increase (Eastern Wood-Pewee, Blue-gray Gnatcatcher,

Chestnut-sided Warbler, Hooded Warbler, Kentucky

Warbler, Summer Tanager). At least 5 early successional

species currently found in the Arkansas Ozarks (e.g.,

White-eyed Vireo, Blue Grosbeak, Blue-winged Warbler,

Indigo Bunting, Yellow-breasted Chat), which are rare or

absent from upland hardwood forests, should increase with

the development of a scrub layer as the canopy opens.

Possibly new species currently absent from the Arkansas

Ozarks, such as Prairie Warbler (Dendroica discolor), will

appear as a breeding species (see Annand and Thompson

1997). Cerulean Warbler, a species of conservation

concern, is currently a relatively common wide-spread

breeder in the Arkansas Ozarks (James and others 2001),

but it will probably be extirpated with the demise of large

oak trees (see Rodewald and Smith 1998). Populations of

Black-throated Green Warblers, which recently colonized

the Arkansas Ozarks (Rodewald 1997), will likely also be

greatly reduced, as will most wood-warblers that breed in

mature forests. In the short-term, populations of Chestnutsided Warblers, another new breeder in the Ozarks

(Rodewald 1997), will probably increase (Rabenold and

others 1998). In other studies where tree species

disappeared, canopy foraging species were negatively

impacted by the elimination of live trees in the canopy, and

ground and low-foraging species were not (Kendeigh 1982,

Rabenold and other 1998). Thus, the red oak borer

infestation has the potential to greatly alter the composition

of the avifauna of the Ozarks, which may have far-reaching

implications for many species of Neotropical migratory bird

species. Elimination of oaks from the Ozarks could

potentially reverse the source-sink relationship rather

quickly, such that the Ozarks also may become unsuitable

for sustained reproductive success for many species.

Prescribed Burning

Although historically prescribed burning as been rare in deciduous forests (Rotenberry and others 1995), there currently

is interest in having more prescribed burns in upland hardwood forests. Dechant (1996) had the opportunity to census

a plot of deciduous forest that had been burned the previous

winter in the Erbie Historic Area in north Newton County, AR,

and compare it with an adjacent plot of forest that did not

burn. Although her sample sizes are small, she found an

increase in Acadian Flycatcher and Blue-gray Gnatcatcher

on the burned plot, and Eastern Wood-Pewee, Yellowthroated Vireo, and Summer and Scarlet tanagers on the

burned plot, but not on the control. Black-and-white Warbler,

Carolina Wren, and White-eyed Vireo occurred on the

control but not the burned plot. As others have found, this

suggests that flycatchers and birds that sally for food respond

positively to burns, whereas the ground- and shrub-nesting

layer may be adversely affected, at least in the short term.

More research is needed in upland deciduous forest on the

effects of fire on bird populations. For example, Burke and

Nol (1998) recently demonstrated that female Ovenbirds

are more sensitive to changes in soil invertebrate densities,

which could be affected by fire, than are male Ovenbirds.

Brown-headed Cowbirds in the Arkansas Ozarks

With forest fragmentation due to red oak borers, one might

expect that parasitism by Brown-headed Cowbirds would

increase (e.g., Donovan and others 1995, Howell and

others 2000). Donovan and others (1995) and Howell and

others (2000) found that cowbirds were more common in

fragmented forests in the Missouri Ozarks than in

contiguous forests. Although cowbird nest parasitism is

almost zero in upland forests of the Arkansas Ozarks today

(table 1, Li 1994), cowbirds are more numerous in forests

that have had some alterations (table 2). However, ever

though individuals may travel long distances to breed

(Thompson 1994), presence of cowbirds in the forests of

the Arkansas Ozarks will be severely limited by the

availability of suitable feeding sites (Thompson 1994).

ACKNOWLEDGMENTS

This work benefited from conversations with John Andre,

Fred Stephen, Jim Guldin, and William Thompson. Frank R.

Thompson III and Paul Rodewald kindly reviewed the

manuscript. Ed Larson and Dave Graney suggested and

facilitated the research at Fleming Creek, and Dan Marion,

U.S.D.A. Forest Service Research Hydrologist, who is

responsible for the Fleming Creek data today, answered

many questions concerning the Fleming Creek site. Joe

Neal and Bob Sanger conducted some censuses at

Fleming Creek. Research on forest practices in the Ozarks

has been funded for the last 10 years by the U.S. Forest

Service, in cooperation with the University of Arkansas. Part

of this manuscript was written while Smith was a Charles

Bullard Fellow at the Harvard Forest, Harvard University.

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253

INTRODUCTION

Widespread death of oaks (Quercus) due to attacks by red

oak borer beetles, Enaphalodes rufulus (Haldeman), is well

documented (Spencer 2001). Resulting thinning and opening of the upland oak-hickory forests has been described

for the Ozark Plateaus region of Arkansas (Spencer 2001).

The change in forest structure before recovery would produce intervening rather open canopy stands with dense

understory compared to pre-infestation conditions. Particularly in areas of dense oak stands, such as at high elevations in the Ozark National Forest, areas of forest are being

completely removed.

This phenomenon will affect avifaunal composition in

impacted areas. As a resource for predicting the nature of

these changes there are 44 years (1967 to 2000) of data

available from two roadside bird censuses in the region of

concern. These censuses, two routes from the Breeding

Bird Survey (Robbins 1986), are situated at high elevations

where northern red oak (Quercus rubra L.), of northern

affinity, thrives the best. This oak is the primary host of the

red oak borer. These two Breeding Bird Surveys are also the

only ones in Arkansas that have high numbers of two bird

species of northern affinity, Scarlet Tanager and Ovenbird.

(Scientific names of birds are in the tables, and authorities

for these names are found in the A.O.U. Check-list of North

American birds, 7th ed.)

Both the census routes pass through mature forest with a

few pasture openings at high elevation around 2000 ft, and

dip down to extensive areas of pasture lands and farm residences around 1000 ft elevation. Therefore, both forest

birds and open country birds have been found over the

years on the routes. The objective of this study is to identify

the avian species already present that will increase or

decrease with the opening of the forest due to oak borer

infestation.

STUDY AREAS

The Compton and Lurton routes were the Arkansas routes

of the Breeding Bird Survey (Robbins 1986) used to analyze

the effects of forest change on the avifauna in the Ozarks.

Both routes are in Newton County. The Compton route

begins near the town of Compton on the ridge top, follows

highway 43 into the Buffalo River Valley joining highway 21

for a ways and then up to the ridge top again on a rural road.

The Lurton route follows rural roads starting near Lurton on

road 123 continuing north to Mt. Judea, then swinging south

again on a road toward Cowell. Both routes are 24.5 miles

long and at around 2000 ft elevation at each end dominated

by forest, with river valleys in the middle at around 1000 ft

or below dominated by pastures and farm yards.

METHODS

The Breeding Bird Survey (Robbins 1986) is a roadside

bird census comprising 50 stops along 24.5 miles of road,

the starting point randomly selected. Precisely the same

stops on the same routes are visited annually every June.

The census starts one-half hour before local sunrise at the

route starting point. The observer records at each stop all

the birds seen and heard there in a three-minute period.

Then the observer drives one-half mile to the next threeminute stop, repeating until all 50 stops are covered. This

has been repeated annually since 1967 at the Compton

and Lurton routes. The data presented here are for 44 years

from 1967 to year 2000. Results are expressed in number

of individuals per bird species for each route averaged over

the 44 years.

RESULTS

In order to evaluate which species will increase and which

will decrease with the opening of the forest, studies of birds

and their habitats must be consulted. Useful compilations of

this information exist. One publication covers Arkansas

(James and Neal 1986) another includes Arkansas and the

rest of the southeastern United States (Hamel and others

1992), three cover nearby Missouri Ozarks (Clawson 1982,

Evans and Kirkman 1981, Jacobs 1997), and one pertains

to the forest lands of the southeastern Atlantic coast states

(Hamel and others 1982). These sources were used collectively in making avian habitat determinations, supplemented

by the author’s own familiarity with Arkansas birds from

field studies over the past 50 years.

Among all the birds found on the routes only species associated with upland forest and open uplands were evaluated.

This eliminated water birds, one introduced species (pigeon),

nocturnal birds (routes are covered in daytime when owls

IMPACTS OF POTENTIAL OAK FOREST CHANGE ON

BREEDING BIRDS IN NORTHWESTERN ARKANSAS

Douglas A. James1

1 Professor of Biological Sciences, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Birds found on existing census routes in the Ozark region of northwestern Arkansas were used to predict

avifaunal changes that could occur in the area due to oak-hickory forest degradation caused by red oak borer beetle

infestations. The two census routes used passed through high elevation forests where red oaks thrive the best. Analysis

showed that 21 bird species would decrease, 38 would increase, and 6 would remain unchanged in abundance in the

event of forest thinning.
254

and goatsuckers are roosting), rare birds, species at the edge

of their range, and species such as vultures that fly over

several habitats. The birds that are expected to decrease

with the opening of the forest due to oak borer damage are

included in table 1, the ones that would increase are in

table 2, and shown in table 3 those that should remain

unchanged in abundance.

Three hawks occur along the routes: Red-shouldered Hawk,

Broad-winged Hawk, and Red-tailed Hawk. The open county

Red-tailed Hawk will increase in areas where extensive

tracts of forest are destroyed, the other two are forest birds

and will decrease except where forest damage is slight.

The two upland game birds are Wild Turkey and Northern

Bobwhite. The Turkey thrives where there are small forest

openings but does not tolerate extensive forest loss. Also,

acorns are a major winter food. Therefore, turkeys would

decrease following extensive oak forest thinning from red

oak borer damage. The bobwhite is an open country and

shrubby thicket bird. It will increase with the loss of forest

canopy.

Table 1—Summer birds found on the Compton and

Lurton Breeding Bird Surveys in the Arkansas Ozarks:

species that would decrease if forest stands become

more open

Birds per route

Species Compton Lurton

Red-shouldered Hawk (Buteo lineatus) 0.56 0.44

Broad-winged Hawk (B. platypterus) 0.11 0.44

Wild Turkey (Meleagris gallopavo) 0.22 0.22

Red-bellied Woodpecker

(Melanerpes carolinus) 6.56 2.89

Downy Woodpecker (Picoides

pubescens) 3.56 3.56

Hairy Woodpecker (P. villosus) 1.44 0.67

Pileated Woodpecker (Dryocopus

pileatus) 6.78 7.11

Eastern Wood-Pewee (Contopus

virens) 11.00 12.33

Acadian Flycatcher (Empidonax

virescens) 2.22 4.56

Yellow-throated Vireo (Vireo flavifrons) 2.44 0.67

Red-eyed Vireo (V. olivaceous) 37.89 54.89

White-breasted Nuthatch (Sitta

carolinensis) 3.78 9.44

Wood Thrush (Hylocichla mustelina) 5.78 6.00

Cerulean Warbler (Dendroica cerulea) 0.67 0.56

Black and White Warbler (Mniotilta

varia) 5.89 7.44

Worm-eating Warbler (Helmitheros

vermivorus) 1.44 2.89

Ovenbird (Seiurus aurocapillus) 9.89 33.67

Louisiana Waterthrush (S. motacilla) 1.33 0.56

Kentucky Warbler (Oporornis formosus) 9.00 5.78

Hooded Warbler (Wilsonia citrina) 2.89 5.22

Scarlet Tanager (Piranga olivacea) 6.89 9.00

Table 2—Summer birds found on the Compton and

Lurton Breeding Bird Surveys in the Arkansas Ozarks:

species that would increase if forest stands become

more open

Birds per route

Species Compton Lurton

Red-tailed Hawk (Buteo jamaicensis) 0.22 0.33

Northern Bobwhite (Colinus

virginianus) 6.00 1.22

Yellow-billed Cuckoo (Coccyzus

americanus) 8.56 12.67

Ruby-throated Hummingbird (Archilocus

colubris) 2.00 2.22

Red-headed Woodpecker (Melanerpes

erythrocephalus) 0.00 0.00

Northern Flicker (Colaptes auratus) 0.22 0.00

Eastern Phoebe (Sayornis phoebe) 4.22 3.00

Great-crested Flycatcher (Myiarchus

crinitis) 3.44 2.67

Eastern Kingbird (Tyrannus tyrannus) 1.89 1.33

Scissor-tailed Flycatcher (T. forficatus) 0.44 0.11

White-eyed Vireo (Vireo griseus) 6.56 4.22

American Crow (Corvus

brachyrhynchos) 32.11 30.00

Purple Martin (Progne subis) 6.89 6.22

Barn Swallow (Hirundo rustica) 6.78 1.56

Carolina Wren (Thryothorus

ludovicianus) 15.56 7.78

Blue-gray Gnatcatcher (Polioptila

caerulea) 13.44 13.11

Eastern Bluebird (Sialia sialis) 12.44 4.78

American Robin (Turdus migratorius) 7.78 3.33

Gray Catbird (Dumetella carolinensis) 0.22 1.22

Northern Mockingbird (Mimus

polyglottos) 0.44 0.56

Brown Thrasher (Toxostoma rufum) 2.67 0.33

European Starling (Sturnus vulgaris) 1.00 2.78

Blue-winged Warbler (Vermivora pinus) 0.56 0.33

Yellow Warbler (Dendroica petechia) 1.00 0.00

Prairie Warbler (Dendroica discolor) 0.00 0.11

Common Yellowthroat (Geothylpis

trichas) 2.56 0.78

Yellow-breasted Chat (Icteria virens) 6.22 7.56

Summer Tanager (Piranga rubra) 7.33 6.33

Eastern Towhee (Pipilo

erythrophthalmus) 12.11 7.89

Chipping Sparrow (Spizella passerina) 13.56 12.56

Field Sparrow (S. pusilla) 15.33 6.89

Northern Cardinal (Cardinalis

cardinalis) 17.67 15.00

Blue Grosbeak (Guiraca caerulea) 15.11 3.33

Indigo Bunting (Passerina cyanea) 39.89 51.22

Common Grackle (Quiscalus quiscula) 1.56 3.33

Brown-headed Cowbird (Molothrus

ater) 11.89 6.33

Orchard Oriole (Icterus spurius) 6.00 2.56

American Goldfinch (Carduelis tristis) 5.56 1.89
255

Yellow-billed Cuckoo, which is very abundant on both routes

(table 2), seeks more open than dense forest and will only

increase with forest thinning. Ruby-throated Hummingbird

is an open country bird. It too will increase when forest

openings are created.

Obviously most of the woodpeckers will decrease when the

forest is degraded. For a brief period dead trees and wood

boring insects will be an attraction followed by overall woodpecker decrease. The decreasing ones are Red-bellied

Woodpecker, Downy Woodpecker, Hairy Woodpecker, and

Pileated Woodpecker. The Red-headed Woodpecker is

very responsive to standing dead trees and is expected to

show a spectacular influx, even though none have been

present on either route. It is a nomadic species that quickly

finds new suitable areas. However, it also stores acorns for

winter food. The loss of oaks will have a negative effect.

Northern Flicker inhabits open lands where it feeds on the

ground on ants. It will increase.

There were six species in the flycatcher family on the two

census routes. Four will increase with forest degradation:

Eastern Phoebe, Great-crested Flycatcher, Eastern Kingbird,

Scissor-tailed Flycatcher. The Great-crested Flycatcher will

increase if forest thinning is not too severe. The change in

Phoebe abundance depends too on availability of its unique

nesting site. The kingbird and Scissor-tailed Flycatcher,

uncommon on the routes (table 2), occur in extensive open

country. Two other flycatchers are both forest dependent

and will decrease with disappearance of forest. Acadian

Flycather seeks thickets in dense mature woods. Eastern

Wood-Pewee, very abundant on the routes (table 1), will

increase some with initial forest canopy opening but will

decrease with further degradation.

Of the vireos on the routes, White-eyed Vireo is a denizen

of dense thickets in forest edge habitat and will increase

with forest opening. The other two, Yellow-throated Vireo

and Red-eyed Vireo, are forest birds and will decrease.

Notice that the Red-eyed Vireo along with the Indigo Bunting

(tables 1 and 2) are the most common birds on both routes.

These two top abundances are typical of bird populations in

Arkansas (James and Neal 1986, p. 48) and the eastern

United States.

American Crows, Purple Martins and Barn Swallows all will

increase with forest degradation. The Blue Jay is an interesting case. The large wintering migratory population (James

and Neal 1986) will dwindle because jays feed on acorns in

winter. The birds counted on the survey routes are nesting

birds not dependent on acorns in summer. However, they

are also year around residents, so their winter survival will

suffer from acorn deficits causing population decline. The

thinning of the forest would have the opposite effect producing more jay habitat because jays occupy broken forest,

not dense closed canopy stands. Counterbalancing these

two opposite effects, numbers of jays will probably be

unchanged.

Carolina Chickadee and Tufted Titmouse occur equally in

forest and forest edge. No change is expected in their

numbers. Forest disappearance will cause declined in

White-breasted Nuthatches. Carolina Wren, a forest edge

bird, already rather common, will increase. Blue-gray

Gnatcatcher is a forest bird but seeks more open forest and

forest edge. It will increase with forest canopy breakup.

The survey routes have seven species in the thrush and

mimic thrush families, plus the closely related starling. Only

one in this group, the Wood Thrush, now fairly abundant

(table 1) will decrease with forest change. The others thrive

in open country and forest edge and will increase: Eastern

Bluebird, American Robin, Gray Catbird, Northern Mockingbird, Brown Thrasher and European Starling.

Seventeen species of nesting warblers were found on the

two survey routes of which twelve are associated with upland

oak-hickory forest or upland open habitats. Opening the

forest will produce increases in five of these: Blue-winged

Warbler, Yellow Warbler, Prairie Warbler, Common Yellowthroat and Yellow-breasted Chat. Seven will decrease:

Cerulean Warbler, Black and White Warbler, Worm-eating

Warbler, Ovenbird, Louisiana Waterthrush, Kentucky and

Hooded Warblers. The Cerulean Warbler seeks forest

canopies with small breaks (James and others 2001), so at

first there will be an increase, later rapid decline as the

forest becomes more open.

With regard to the two tanagers, the Summer Tanager has

a southern affinity and the Scarlet Tanager is part of a

northern avifauna. They seek different habitats. Summer

Tanager will increase with forest thinning because it occupies broken forest and tall forest edge. Scarlet Tanager will

decrease since it occurs in closed canopy forests.

There were nine species in the sparrow, bunting, finch group

on the two Breeding Bird Survey routes. Two of these will

show no change, the House Sparrow because it occupies

barnyard and pasture sites, and the Dickcissel that depends

on extensive hay fields. The rest are all open country thicket,

forest edge, and old field birds. They will increase with

opening of the upland forest: Eastern Towhee, Chipping

Sparrow, Field Sparrow, Northern Cardinal, Blue Grosbeak,

Indigo Bunting (already extremely common, table 2), and

American Goldfinch.

Eastern Meadowlark will be unaffected by forest change

since it occupies pastures and hayfields. All the rest of the

Table 3—Summer birds found on the Compton and

Lurton Breeding Bird Surveys in the Arkansas Ozarks:

species that would not change in abundance if forest

stands become more open

_

Birds per route

Species Compton Lurton

Blue Jay (Cyanocitta christata) 8.89 8.67

Carolina Chickadee (Poecile

carolinensis) 9.89 13.67

Tufted Titmouse (Baeolophus bicolor) 16.78 9.67

Dickcissel (Spiza americana) 2.00 1.11

Eastern Meadowlark (Sturnella magna) 10.89 2.89

House Sparrow (Passer domesticus) 1.44 2.44
256

blackbird family will increase with forest degradation

because they thrive in a landscape mosaic of forest and

open country patches: Common Grackle, Brown-headed

Cowbird, Orchard Oriole.

DISCUSSION

Two Breeding Bird Survey routes in northwestern Arkansas

contain 44 years of information for predicting changes in

bird populations if upland forests are thinned and opened

by red-oak borer infestations. These two routes traverse

high elevation forests where northern red oak is most abundant, and where forest birds predominate. Both routes also

dip into a valley where open farmland exists inhabited by

open country and forest edge birds. These latter birds will

increase when the forest is opened; the forest birds will

decrease. Among the species found on the two census

routes there are 21 that will decrease in abundance, 38 that

will increase, and 6 that will exhibit no change.

This investigation refers only to what will happen to breeding birds in the event of forest change in the study area.

Decrease in forest cover will also affect winter resident bird

populations and migrant species in passage. Predictions

regarding these species will require further study. Some of

the breeding birds mentioned herein are permanent residents and thus are present in winter too.

ACKNOWLEDGMENTS

The author of this paper for many years covered both the

Compton and Lurton routes of the Breeding Bird Survey.

Others who have been in charge of either or both routes

over the years include Frances James, Helen Parker, Max

Parker Lance Peacock, Charles Preston, Joseph Neal and

Kimberly Smith. Their efforts are greatly appreciated.

LITERATURE CITED

American Ornithologists’ Union. 1998. Check-list of North American

birds. 7th ed. American Ornithologists’ Union, Washington, D.C.

829 p.

Clawson, R.L. 1982. The status, distribution, and habitat preferences of birds of Missouri. Missouri Department of Conservation,

Terrestrial Series no. 11. 80 p.

Evans, K.E.; Kirkman, R.L. 1981. Guide to bird habitats of the

Ozark Plateau. U.S. Dept. Agriculture, Forest Service, North

Central Experiment Station, General Technical Report NC-68.

78 p.

Hamel, P.B. 1992. The land manager’s guide to the birds of the

South. Nature Conservancy, Chapel Hill, North Carolina.

367+ p.

Hamel, P.B.; LeGrand, H.E., Jr.; Lennartz, M.R.; Gauthreaux, S.A.,

Jr. 1982. Bird-habitat relationships on southeastern forest

lands. U.S. Dept Agriculture, Forest Service, Southeastern

Forest Experiment Station, General Technical Report SE-22.

417 p.

Jacobs, B.; Wilson, J.D. 1997. Missouri breeding bird atlas.

Missouri Department of Conservation, Jefferson City. 430 p.

James, D.A.; Kellner, C.J.; Self, J.; Davis, J. 2001. Breeding

season distribution of cerulean warblers in Arkansas in the

1990s. Journal of the Arkansas Academy of Science 55: 66-74.

James, D.A.; Neal, J.C. 1986. Arkansas birds, their distribution and

abundance. University of Arkansas Press, Fayetteville. 402 p.

Robbins, C.S.; Bystrak, D.; Geissler, P.H. 1986. The breeding bird

survey: its first 15 years 1965-1979. U.S. Fish and Wildlife

Service, Resource Publ. No. 157.

Spencer, J. 2001. Dead and dying, what’s happening to Arkansas

oaks. Arkansas Wildlife 32(6): 3-7.
257

INTRODUCTION

In the 1980s, following extreme winters in the late 1970s

and severe droughts in 1976, 1980, and 1983, dead and

dying scarlet and black oaks were found on 185,000 acres

of the Mark Twain National Forest. That decline event was

linked to environmental stresses (Law and Gott 1987).

Severe oak decline is now affecting an estimated 500,000

acres on the Mark Twain. High-risk stands are predisposed

to severe damage because mature scarlet (Quercus

coccinea Muenchh.) and black oak (Q. velutina Lam.) dominate in fully stocked stands on droughty sites. The current

decline was triggered by serious moisture deficits from

1999 until mid-May, 2001. Insects and diseases contributing to tree death and decline include Armillaria root rot,

twolined chestnut borer (Agrilus bilineatus Weber), red oak

borer (ROB) (Enaphalodes rufulus Haldeman), and insect

defoliators.

The extensive areas now occupied by dense scarlet and

black oak stands are artifacts of European settlement that

replaced shortleaf pine (Pinus echinata Mill.) and oak-pine

forests and woodlands of long-standing (Nelson 2002). Prior

to European settlement, much of the Missouri Ozarks had

more-open forests and woodlands dominated by shortleaf

pine and maintained by large herbivores and by frequent,

low-intensity fires set by Native Americans (Nigh 1992,

Guyette and Cutter 1991, Yatskievych 1999, Stambaugh

2001). After extensive logging between 1870 and 1930,

these lands were subjected to annual burning and overgrazing by free roaming livestock, resulting in erosion and

loss of soil moisture holding capacity. Forest fire control

began in the mid-1930s, which allowed sprouts and seedlings of the red oak group to survive and develop. Missouri

botanist Julian Steyermark, in his 1937 study of newly

acquired national forest lands, reported a hodgepodge of

vegetation with some species out of place and others

occurring in disproportional numbers.

METHODOLOGY

In winter 2001/2002 permanent oak mortality monitoring

plots were established in 57 stands throughout portions of

the Mark Twain National Forest located in the Ozarks.

• 43 high risk stands (upland scarlet/black oak > 70 years

old)

• 10 DFC (desired future condition) stands (majority of

stocking in shortleaf pine/white oak, with black/scarlet

oak stocking < 40 percent)

• 4 Riparian stands to monitor oaks on drainageways/

lower slopes

Tree species and condition were tallied using 10-BAF

variable radius plots on 5 points/stand; three 1/100th acre

regeneration plots were established at each sampling point

(Mielke 2001).

RESULTS

Severe decline symptoms, mortality and ROB attacks were

limited almost exclusively to the red oak group. Forest

health was rated good only in the DFC stands; riparian and

high risk stands were fair. Red oak borers (ROB) infested

85-90 percent of the red oak group to some degree in all

stands except riparian stands, which had only 69 percent of

red oaks attacked. All stand categories had comparable

ratings for > 33 percent crown dieback (~ 40 percent), and

~ 8 percent red oak BA mortality in 2001. All districts had

high percentages of red oak BA affected by ROB (70-98

percent). However, the average number of ROB attacks/

tree was greatest on the Potosi/Fredericktown, Houston/

Rolla and Cassville Districts. Ratings for red oak crown

dieback > 33 percent varied from 28-48 percent between

districts. White oak reproduction generally exceeded red

oak group reproduction on all districts, in agreement with

earlier surveys (Law and Johnson 1989) (Davidson 1990).

Shortleaf pine reproduction was less abundant than that of

oak species and pine regeneration was absent on some

districts.

DISCUSSION

Based on monitoring of the 1980s decline on the Doniphan/

Eleven Point District (Law and Johnson 1989), further decline

and mortality of red oaks in declining stands is anticipated.

Scarlet and black oak components in heavily stocked

mature stands should be harvested and regenerated with

mixtures including more drought-tolerant, longer-lived white

oaks and shortleaf pine. Otherwise, red oak decline and

mortality are likely to recur frequently in the Missouri

Ozarks - history will continue to be revisited.

LITERATURE CITED

Davidson, Michael.1990. The effects of oak decline on the species

composition of the upland hardwood cover-type of southern

Missouri. Submitted to J. Law, Timber Staff Officer, USDA

Forest Service, Mark Twain National Forest, Rolla, MO, May

15,1990. 25 p.

OAK DECLINE IN MISSOURI: HISTORY REVISITED

Jay R. Law, Ross Melick, Charly Studyvin, and James R. Steinman1

1 Retired Timber Staff Officer and Consulting Forester, USDA Forest Service, Mark Twain National Forest, North Central Research Station,

Sinkin Experimental Forest, Salem, MO 65560; Silviculturist, Oak Decline Project, and Forest Silviculturist, USDA Forest Service, Mark Twain

National Forest, Rolla, MO 65401; and Forest Health Monitoring Coordinator, USDA Forest Service, NE/NA, Newtown Square, PA 19073,

respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.
258

Guyette, Richard P.; Cutter, Bruce E. 1991. The use of shortleaf

pine remnants to determine fire frequency in the Missouri

Ozarks. Report of research supported by the Mark Twain

National Forest, USDA Forest Service, Rolla, Missouri, as

Challenge Cost-Share Agreement No. 09-05-121. 18 p.

Law, Jay R.; Gott, Jerry D. 1987. Oak mortality in the Missouri

Ozarks. In: Sixth Central Hardwood Forest Conference.

p. 427-436.

Law, Jay R.; Johnson, Leo J. 1989. A five year record of change

for a declining scarlet oak stand in the Missouri Ozarks. In:

Seventh Central Hardwood Conference. p. 103-107.

Mielke, Manfred E. 2001. Forest health evaluation of oak mortality

and decline on the Mark Twain National Forest, 2000. 10 p.

Forwarded by: letter dated 03/27/2001, file designation 3400,

by M. Prouty, USDA Forest Service, Northeastern Area, State

and Private Forestry, St. Paul, MN.

Nelson, Paul W. 2002 . Background, ecological patterns and

processes; pineknot environmental impact statement, affected

environment and environmental consequences, vegetation

section. 25 p. Draft. USDA Forest Service, Mark Twain National

Forest, Rolla, MO.

Nigh, Tim. 1992. The forests prior to European settlement. Pp. 6-

13 in A.R.P. Journet and H.G. Spratt, Jr., eds. Towards a Vision

for Missouri’s Public Forests, March 27-28, 1992. Southeast

Missouri State University, Cape Girardeau, MO.

Stambaugh, Michael. 2001. Forest canopy gap dynamics in shortleaf pine forests of the Ozark Highlands. Columbia, Mo: Univ. of

Missouri. 186 p. M.S. thesis.

Steyermark, Julian A. 1937. Grazing report for the Clark National

Forest: section C & D. USDA Forest Service, Rolla, MO. 39 p.

Yatskievych, George. 1999. Steyermark’s flora of Missouri. Vol. 1.

Revised ed. The Missouri Department of Conservation,

Jefferson City, Missouri, in cooperation with The Missouri

Botanical Garden Press, St. Louis, Missouri. p. 88-91.
259

RESEARCH SUMMARY

The purpose of this study is to quantify the gypsy mothrelated mortality and subsequent mortality-induced growth

losses that might be expected in these highly susceptible

forests in the event of gypsy moth outbreaks in the forests

of the Interior Highlands. The Gypsy Moth Stand Damage

Model (Colbert and Racin 2001) was used to simulate these

losses using the “canned” scenarios that have been built

into the model. Three outbreak scenarios were considered—

moderate, heavy, and none. The length of the simulation

was set at 20 years since that period of time is long enough

to simulate changes but not so long that simulations would

be unreliable. Output from the model was averaged for each

simulation, weighted by forested acres expansion factors,

by each subsection and susceptibility class. These averages were then used to calculate percentage losses for

each scenario by dividing the moderate or heavy outbreak

result by the baseline result.

Inventory plot data were obtained from the Eastwide forest

survey database and FIA plots were stratified within the

Interior Highlands by ecological section and subsection.

The sheer number of forest survey plots and the plot-by-plot

processing required to translate plot data into the model

dictated that a subset of forest survey plots be sampled for

inclusion in the model. Within each ecological subsection,

plots were placed in a gypsy moth susceptibility class based

on percent of basal area in gypsy moth preferred species.

The initial random sample of forest survey plots was conducted to include a minimum of three plots per subsection

(without replacement) in each of the four susceptibility

classes. If this was less than a 1 percent sample of the

forested area of a subsection/susceptibility class combination, additional plots were sampled to bring the sample

percentage up to 1 percent.

No significant differences were observed by section for

basal area loss under either the moderate or heavy defoliation scenarios. Basal area declined over time; percent

basal area decline varied from 34.9 to 40.1 percent under

the moderate defoliation scenario, and from 74.6 to 81.3

percent under the heavy defoliation scenario. Conversely,

changes in stem density were significant by section. When

plots were stratified by susceptibility, the opposite effect

was seen. Under both moderate and heavy outbreak scenarios, significant differences in percent basal area loss

were observed by susceptibility class. Immune plots had a

smaller percent loss than highly susceptible plots. Under

the moderate outbreak scenario, percent basal area loss

varied from 25.6 in immune plots to 48.2 percent in highly

susceptible plots. Under the heavy outbreak scenario, the

trend was the same but more pronounced; basal area

decline varied from 64.0 percent in immune plots to 88.1

percent in highly susceptible plots. There were no significant differences in percent change in stem density by

susceptibility class under either the moderate or heavy

outbreak scenarios. The heavy outbreak scenario often

caused a reduction in the susceptibility class due to the

large amount of mortality in susceptible species. In these

results, the immune species group has significantly lower

percent declines than the other groups, which suggests

they will become more dominant at the end of the scenario.

LITERATURE CITED

Colbert, J.J.; Racin, George. 2001. How to use the stand-damage

model. Version 2.0. Gen. Tech. Rep. NE-281. Newtown Square,

PA: U.S. Department of Agriculture, Forest Service, Northeastern

Research Station. 79 p. [Computer program].

MODELING GYPSY MOTH-RELATED TREE MORTALITY UNDER

DIFFERENT OUTBREAK SCENARIOS IN INTERIOR HIGHLANDS FORESTS

Kurt W. Gottschalk, James M. Guldin, and Jimmie J. Colbert1

1 Research Forester, USDA Forest Service, Northeastern Research Station, Morgantown, WV 26505-3180; Research Forest Ecologist, USDA

Forest Service, Southern Research Station, Hot Springs AR 71902; and Research Mathematician (retired), USDA Forest Service,

Northeastern Research Station, Morgantown, WV 26505-3180, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—A simulation was conducted to determine how growth of forests in the Interior Highlands would change under

attack by the gypsy moth (Lymantria dispar L.). Simulations were conducted for three different outbreak intensities using

the Gypsy Moth Stand-Damage Model. Forest Inventory and Analysis (FIA) inventory data were used as input for the

simulation. An ecological approach was taken for the simulation runs by stratifying the FIA data by ecological subsection,

to better understand how outbreak effects might differ by subsection. Results show significantly greater percentage losses

in stem density in the southern part of the Interior Highlands under both the moderate and heavy outbreak scenarios. The

percent decline in basal area is nearly doubled in all susceptibility classes between the moderate and heavy defoliation

scenarios. This is the first detailed examination of the damage that will inevitably occur when, at some unforeseen point

within the next 100 years, gypsy moth becomes established in the Interior Highlands.
260
261

Management
262
263

SUMMARY

In the past decade, the use of prescribed fire in the mixedoak forests of the eastern United States has markedly

increased to help overcome the chronic lack of abundant,

vigorous oak regeneration (Yaussy 2000). However, prescribed burns implemented under inappropriate circumstances can result in failure to establish oak regeneration

and/or loss of existing oak reproduction. To correctly use

fire to promote regeneration of mixed-oak forests, stand

developmental dynamics (Oliver and Larson 1990) and the

oak regeneration process (Sander and others 1984) must

be considered simultaneously.

When a mature mixed-oak forest is in the understory reinitiation stage, timber harvest or other major disturbance

will move it to the stand initiation stage. Before this can

take place, oak regeneration must become established in

the mature stand. Research has shown that prescribed fire

can help by preparing the seedbed for acorn caching by

wildlife, xerifying the soil surface to inhibit establishment of

mesophytic species, and decreasing populations of acorninfesting insects (Barnes and Van Lear 1998, Van Lear and

Watt 1993). To do this, burning must take place shortly before

an acorn crop occurs. This is a difficult treatment to time

because acorn crop occurrence fluctuates annually and is

an event impossible to accurately predict. Also, these benefits only last a year or two. Burning should not take place

immediately after an acorn crop (Auchmoody and Smith

1993) or when oak regeneration is still young and small

(Brose and Van Lear, this proceedings) because fire kills

acorns and new seedlings. Burning in mature oak stands

also can help reduce understory competition and shade.

To do this, burning must occur repeatedly as single fires

seldom produce sufficient intensity to remove midstory

trees. Because of these caveats and limitations, using

prescribed fire to establish oak regeneration in mature

stands generally requires multiple burns beginning several

years or more before an anticipated harvest. Mechanical

site scarification or waiting for a bumper acorn crop are

probably better management strategies for establishing

new oak seedlings than prescribed burning.

A mixed-oak stand that is entering the stand initiation stage

via the shelterwood system is an ideal site for the use of

prescribed burning if it has abundant oak regeneration that

is being out-competed by faster growing species (Brose

and others 1999). In this setting, fire, especially during the

growing season, top kills the regeneration, shifting oak

reproduction to a position of dominance because of its

superior fire survival and sprouting abilities. In this context,

the residual crop trees must be protected from the fire by

removal of logging slash near their bases before burning or

prevention of slash accumulation during the logging operation (Brose and Van Lear 1999). A new oak stand formed

by a complete overstory removal also may benefit from

prescribed burning. Like a shelterwood, it, too, must have

abundant oak regeneration that is being out-competed by

faster-growing species. However, this scenario has not yet

been adequately researched to provide sound guidance.

Once a new oak stand grows past crown closure into the

stem exclusion stage, there is no reason to use fire in its

management. To do so would damage the lower boles of

the trees, resulting in long-term value loss (Carvell and

Maxey 1969).

Fire in mixed-oak forests can inadvertently create a major

regeneration obstacle. Burned areas attract deer as sprouting hardwoods are highly preferred browse and this could

lead to a localized deer overabundance problem. If this

happens, fencing will probably be necessary to protect the

new regeneration until it grows out of the reach of deer.

LITERATURE CITED

Auchmoody, L.R.; Smith, H.C. 1993. Survival of northern red oak

acorns after fall burning. Res. Pap. NE-678. Radnor, PA: U.S.

Department of Agriculture, Forest Service, Northeastern

Research Station. 6 p.

Barnes, T.A.; Van Lear, D.H. 1998. Prescribed fire effects on

hardwood advance regeneration in mixed hardwood stands.

Southern Journal of Applied Forestry. 22(3): 138-142.

Brose, P.H.; Van Lear, D.H. 1999. Effects of seasonal prescribed

fires on residual overstory trees in oak-dominated shelterwood

stands. Southern Journal of Applied Forestry. 23(2): 88-93.

Brose, P.H.; Van Lear, D.H.; Keyser, P.D. 1999. A shelterwood-burn

technique for regenerating productive upland oak sites in the

Piedmont region. Southern Journal of Applied Forestry. 23(3):

158-163.

Carvell, K.L.; Maxey, W.R. 1969. Wildfire destroys! West Virginia

Agric. and Forest Exp. Stat. Bull. 2: 4-5, 12.

Oliver, C.D.; Larson, B.C. 1990. Forest stand dynamics. New York,

NY: McGraw-Hill. 475 p.

Sander, I.L.; Johnson, P.S.; Rogers, R. 1984. Evaluating oak

advance reproduction in the Missouri Ozarks. Res. Pap. NC251. St Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station. 11 p.

Van Lear, D.H.; Watt, J.M. 1993. The role of fire in oak

regeneration. In Loftis, D.L.; McGee, C.E., editors. Oak

regeneration: Serious problems, practical recommendations.

Gen. Tech. Rep. SE-84. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern Forest Experiment

Station: 66-78.

Yaussy, D., comp. 2000. Fire, people, and the central hardwood

landscape. Conference Proceedings; 2000. Gen. Tech. Rep.

NE-274. Newtown Square, PA: U.S. Department of Agriculture,

Forest Service, Northeastern Research Station. 264 p.

FITTING FIRE INTO OAK MANAGEMENT

Patrick Brose1

1 Research Silviculturist, USDA Forest Service, Northeastern Research Station, Forestry Sciences Laboratory, Irvine, PA 16329.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.
264

INTRODUCTION

Oak-dominated forests of the Central and Eastern United

States have generally not been regarded as suited to

uneven-aged silviculture (Roach and Gingrich 1968, Sander

and Clark 1971). In fact, several attempts to apply the

selection method of reproduction cutting in oak-dominated

stands have resulted in compositional shifts toward more

shade tolerant species (Trimble 1970). Given these results,

one might legitimately ask why conversion of these stands

to an uneven-aged structure would be attempted, if maintenance of a dominant oak component were an objective of

management.

However, empirical and experimental data suggest that

under certain specific conditions, oak stands can be

managed using uneven-aged methods. Many landowners

are interested in managing uneven-aged stands because of

the attributes that such stands provide. Among these are

the maintenance of continuous forest cover in the stand,

sustained yield of high-value products over time, and

conditions suitable for plant and animal species that can

advantageously utilize the stratified canopies and minimal

harvesting impacts that are found in such stands.

In the Interior Highlands, not all stands are suitable for

application of uneven-aged silviculture. Of stands that are

ecologically suitable for conversion from even-aged to

uneven-aged condition, efficiency of conversion depends

greatly on stand condition at the beginning of the conversion process. For example, some landowners in the region,

most prominently the Pioneer Forest in Salem, MO, have

had great experience in creating well-structured unevenaged upland oak stands, but these stands had their origin

largely as poorly stocked cutover stands that were rehabilitated through judicious tending of residual growing stock

(Loewenstein 1996, Loewenstein and others 2000). This

pattern, where uneven-aged stands were created through

rehabilitation of understocked conditions resulting from

overcutting, has been a common theme in southern pine

experience as well (Guldin and Baker 1998).

Conversely, there has been little practical or research experience in creating an uneven-aged structure from well-stocked

even-aged oak stands. In this paper, a review of existing

information on even-aged stand dynamics is presented

from the perspective of applying that information to convert

fully-stocked even-aged stands of varying ages—immature,

mature, and overmature—into stands with uneven-aged

structure. Emphasis is given to three elements thought to

be critical to the success of such conversion—site conditions, species composition, and existing age structure. The

goal of this review is to suggest working hypotheses on the

patterns by which uneven-aged stands can be developed,

the treatments that might be applied, and the length of time

required to consider the conversion a success.

ATTRIBUTES OF SUCCESSIONALLY STABLE

EVEN-AGED OAK STANDS

Barrett (1995) broadly categorizes oak-dominated stands in

the oak-hickory type as either sub-climax or successionally

stable. Sub-climax stands have the highest site indices

(75+ feet, base age 50 years) and are the most difficult to

regenerate to oak. Succession on these sites tends toward

more shade-tolerant and/or mesophytic species (Barrett

1995, Johnson 1993, Sander and Graney 1993). Successionally stable oak stands often occur on poor to medium

quality sites that tend to be droughty. Few non-oaks can

persist on these sites as canopy dominants (Weitzman and

Trimble 1957, Roach and Gingrich 1968, Sander and Clark

1971, Barrett 1995). The selection studies that showed a

compositional shift were conducted in stands that tended

toward the sub-climax end of the spectrum. Conversely,

single-tree selection has been shown to be a viable silvicultural alternative for maintaining an oak-dominated forest

in successionally-stable stands (Loewenstein and others

1995, Loewenstein 1996, Loewenstein and others 2000).

Thus, discussion focuses on the successionally stable end

of the gradient of oak-dominated stands. The methodologies presented may prove to be more or less successful

(from the perspective of developing and maintaining three

age classes of oak) depending on where a stand is

classified along that gradient.

CONVERSION OF SUCCESSIONALLY STABLE EVEN-AGED

OAK STANDS TO AN UNEVEN-AGED STRUCTURE

Edward F. Loewenstein and James M. Guldin1

1 Assistant Professor, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL; and Research Forest Ecologist and Project

Leader, USDA Forest Service, Southern Research Station, Monticello, AR, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Developing a silvicultural prescription to convert an even-aged or unmanaged oak stand to an uneven-aged

structure depends in large part on the length of time the existing overstory will live. Four conversion prescriptions,

representing three initial stand conditions, are presented. Each prescription partitions the cut of the original overstory

differently in time and space depending on the interval between stand entries and the desired allocation of growing space

among the newly developing age classes.
265

CONVERTING EVEN-AGED STANDS TO

UNEVEN-AGED STRUCTURE

The success of conversion prescriptions depends on stand

age and species composition, which determine whether the

dominant overstory is capable of surviving the conversion

period. Species longevity, in conjunction with stand age,

gives an estimate of the time available to complete the

conversion before the remaining residual overstory must be

removed or until the likelihood of age-dependent mortality

increases dramatically. The ability to maintain this residual

overstory is not, in and of itself, integral to the conversion

process; what is important is managing the growing space

allocated to this age class. Widespread natural mortality of

trees in the main canopy is an unpredictable event that

affects both the development of trees in subordinate canopy

classes and the regeneration/recruitment process. By losing

control of growing space allocation, the ability to manage

stand structure is compromised.

The conversion of an even-aged (single tiered canopy) stand

to a multi-tiered structure (uneven-aged), and following conversion the maintenance of this structure, is accomplished

by vertically partitioning growing space among age classes

or cohorts. For purposes of this discussion, growing space

is defined as percent stocking based on Gingrich’s (1967)

tree area equations and stocking chart.

Conversion prescriptions will only work if stocking of all age

classes is kept closer to 58-60 percent stocking (the Gingrich

‘B’ line of stocking) rather than to 100 percent stocking (the

Gingrich ‘A’ line). The ‘B’ line represents the low end of full

stocking in a stand, assuming a uniform distribution of trees

across the site; each tree is at maximum crown spread and

there are no gaps between adjacent crowns. A stand at ‘B’

level stocking is allocating growth to significantly fewer trees

than is a stand approaching 100 percent stocking, and this

will be important during the conversion process.

Three conversion prescriptions will be discussed, based on

stand age—conversion of immature stands, mature stands,

and overmature stands. Within the mature stand condition,

two patterns of conversion—uniform conversion and patch

conversion—will also be discussed.

Immature Stands

In this prescription, a fully stocked young stand must be

heavily cut during the initial entry; as a result, residual

stocking levels will be quite low in the early years of the

conversion (table 1a). This heavy cut is needed because

young stands grow rapidly, and will quickly reoccupy the

available growing space. Stands subject to this prescription

must be followed closely lest stocking accrue to the point

where the Gingrich ‘B’ line is approached.

The prescription applies to stands that are immature and

fully stocked. It can also be used in situations where the

landowner wishes to develop an uneven-aged state, but the

existing stand does not lend itself to conversion. In such a

situation, the stand is regenerated, and the succeeding

even-aged stand is allowed to develop for approximately

30 years before the conversion is attempted.

However, even if the prescription is properly implemented,

the methodology is highly inefficient in that it requires investments that are not immediately recovered. Depending on the

size of the dominant overstory and local markets for small

diameter stems, there may be little income generated from

the stand during the conversion process. Each entry may

amount to a pre-commercial thinning. Thus, this prescription

Table 1—Levels of stocking by cohort and year used to

implement three prescriptions to convert successionally stable even-aged oak stands to uneven-aged

structure

 Cohort

Year 1 2 3 4 5 6 7

- - - - - - - - - - - percent stocking - - - - - - - - - - -

a. Immature stands

C-30 100 0 0 0 0 0 0

C-15 100 0 0 0 0 0 0

C 30 30 0 0 0 0 0

C+15 30 30 0 0 0 0 0

C+30 30 20 10 0 0 0 0

C+45 30 20 10 0 0 0 0

C+60 0 30 20 10 0 0 0

C+75 0 30 20 10 0 0 0

C+90 0 0 30 20 10 0 0

C+105 0 0 30 20 10 0 0

C+120 0 0 0 30 20 10 0

C+135 0 0 0 30 20 10 0

C+150 0 0 0 0 30 20 10

b. Mature stands

C-30 100 0 0 0 0 0 0

C-15 66 0 0 0 0 0 0

C 50 10 0 0 0 0 0

C+15 40 20 0 0 0 0 0

C+30 30 20 10 0 0 0 0

C+45 30 20 10 0 0 0 0

C+60 0 30 20 10 0 0 0

C+75 0 30 20 10 0 0 0

C+90 0 0 30 20 10 0 0

C+105 0 0 30 20 10 0 0

C+120 0 0 0 30 20 10 0

C+135 0 0 0 30 20 10 0

C+150 0 0 0 0 30 20 10

c. Overmature stands

C-30 100 0 0 0 0 0 0

C-15 66 0 0 0 0 0 0

C 40 20 0 0 0 0 0

C+15 30 30 0 0 0 0 0

C+30 0 40 20 0 0 0 0

C+45 0 40 20 0 0 0 0

C+60 0 30 20 10 0 0 0

C+75 0 30 20 10 0 0 0

C+90 0 0 30 20 10 0 0

C+105 0 0 30 20 10 0 0

C+120 0 0 0 30 20 10 0

C+135 0 0 0 30 20 10 0

C+150 0 0 0 0 30 20 10
266

should be implemented only with the understanding that the

desire for an uneven-aged stand outweighs the costs of

conversion.

Regeneration in this prescription is obtained almost exclusively from stump sprouting during the first cutting cycle

entries. By age 30, most oak stands are not yet producing

large quantities of acorns and the stand is sufficiently dense

that accumulation of advance reproduction has not begun.

By thinning the stand to approximately 30 percent stocking,

only the largest, most vigorous trees with the best form are

retained. In particular, one would select against trees that

show a propensity for epicormic branching because these

residual trees will be open grown, similar to the leave trees

in an irregular shelterwood (see Miller 1996). The second

age class is recruited from stump sprouts and the stand is

allowed to develop for another 30 years at which time the

dominant canopy tier has grown to approximately 55-58

percent (approaching ‘B’ line) stocking.

A cutting cycle of thirty years is possible only because the

residual stocking was reduced to 30 percent. If stocking

had not been reduced so dramatically, or if growth rates

were such that the dominant canopy class were to reach

full stocking (B-line) before 30 years had passed, then the

stand would have to be reentered in order to keep the subordinate age class alive. It is important to note that the point

a stand must be reentered is before the dominant canopy

reaches 58-60 percent stocking (the B-line), not at 100

percent stocking (A-line). As the dominant canopy layer

approaches B level stocking, it is fully occupying the available growing space in the stand. This leaves all subordinate canopy layers with no free growing space. In reality, this

point is reached somewhere above the B-line because the

distribution of trees in a stand is not perfectly uniform; however, the concept still applies.

Following the first cutting cycle, overstory stocking is again

reduced to approximately 30 percent stocking and the midstory is thinned to 20 percent stocking. The third age class

is recruited primarily from stump sprouts, supplemented by

advance reproduction. This second entry completes the

conversion. Three age classes have been established and

future stand entries are directed toward the maintenance of

the existing stand structure (see Larsen and others 1999).

The conversion is accomplished in thirty years, sixty if it

were initiated by an even-aged regeneration of the stand

(table 1).

Mature Stand, Uniform Reduction

In this second prescription, one is dealing with a fully stocked

stand of mature trees, a portion of which must be capable

of surviving an additional 60 to 70 years. This conversion

prescription calls for a uniform treatment across the stand

and because of this, the product yield during the conversion

process may fluctuate greatly across cutting cycles. However, because the trees being managed are of larger size,

each entry should produce commercial harvests of timber

and should generate income for the landowner.

For the initial entry, stand stocking should be reduced by no

more than one-third (to not less than 60 percent stocking)

in an operation similar to the preparatory cut of a shelterwood (table 1b). This harvest is designed to increase the

vigor of the residual overstory trees so they are less likely

to degrade when the stand is opened further; an ancillary

outcome is to develop the advance reproduction in the

understory that will become the second age class. The

amount of time between this harvest and the second is not

critical because its primary goal was not to establish a new

cohort. The second entry is made when the residual trees

have increased crown spread and some advance reproduction has developed (approximately 5–15 years). However, if

significant crown dieback occurs, possible in the shorterlived or less vigorous residuals, then the timing of the second

entry should be moved up to salvage the potential loss.

The second cutting-cycle harvest reduces overstory stocking to approximately 50 percent and is designed to recruit

the first new age class of the conversion process. Any tree

deemed likely to die or significantly degrade prior to the

next harvest entry is removed. Beyond that, the best trees

are left as uniformly as possible across the stand to meet

the desired stocking level. Note that only 10 percent of

available growing space is allocated to the new age class;

50 percent stocking is retained in the overstory, which

leaves only 10 percent available for establishment of the

new cohort. By retaining much of the growing space in the

dominant canopy tier, the density of the newly established

cohort is kept fairly low. This later reduces the amount of

precommercial thinning needed when the next cohort is

recruited at the subsequent cutting cycle harvest. However,

the stocking of the dominant canopy tier(s) must be kept

sufficiently low to maintain the vigor of the most subordinate

age class throughout the cutting cycle. Thus, residual

stocking levels and growth rates determine the length of

the cutting cycle.

The vigor of the most subordinate age class is a function of

the relative density of all superior age classes. When the

dominant canopy tiers reach full stocking, density dependent

mortality of the understory begins. The level of residual

stocking can be modified in the event that a shorter or longer

cutting cycle is desired; in this case, a 15-year cutting cycle

is initially suggested.

At the end of the first cutting cycle, the dominant canopy

tier is reduced to 40 percent stocking leaving approximately

20 percent free growing space for the developing understory layer. During this entry, the objective is not to develop

a third age class. One only seeks to ensure that the second

age class maintains sufficient growing space for continued

development. Thus, even if the second age class occupies

more than 20 percent stocking (growing space), it is left

untreated. Following the second cutting cycle, the overstory

is reduced in stocking to 30 percent, and the midstory to 20

percent, leaving approximately 10 percent free growing

space for the establishment of a third age class. Following

conversion, as canopy tiers become less distinct, the distribution of stocking between age classes is most easily allocated among size classes: sawtimber (overstory), poles

(midstory), and seedlings/saplings (reproduction/understory).

There is no need to establish a new cohort with each entry.

For an uneven-aged stand, only three age classes are

required. Therefore, it is possible to regenerate a new
267

cohort every second, third, or fourth entry into the stand

depending on the age of the oldest cohort and the length of

the cutting cycle. If such is the case, total stand stocking

should not be reduced to 50 percent until a regeneration

event is desired. Reduce stocking in the two superior canopy

tiers enough to ensure the most subordinate canopy class

remains vigorous [e.g., thin all trees >5 inches in diameter

at breast height ((d.b.h.)] to 50 percent stocking, thus

leaving 10 percent growing space for the most subordinate

class).

The suggested ratio of stocking among size/age classes

(30:20:10) approximates a q-value of 1.3 (for 2-inch diameter

classes). It maintains 70 percent of the stand basal area in

the sawtimber size classes and ensures sufficient numbers

of trees in the smaller size classes to sustain ingrowth while

allowing for natural mortality, crop tree selection, and timber

harvest. This stand structure has been found sustainable in

the Ozark Highlands of Missouri (Loewenstein 1996, Larsen

and others 1999, Loewenstein and others 2000). Using this

ratio of growing space among age classes during stand

conversion facilitates structural maintenance thereafter.

Mature Stand, Patch Reduction

In this third prescription for conversion, one is also dealing

with a mature stand of trees, and one uses the same stocking levels as outlined for the uniform conversion (table 1b).

However, the pattern of implementation is different.

Under this methodology, new cohorts are developed with

each entry, but not across the entire stand. Unlike the uniform

conversion prescription, the start of the conversion is staggered in patches across the stand. The initial reduction in

stand stocking is the same between the two methods, a

uniform reduction across the entire stand of one-third to not

less than 60 percent stocking. Following the first entry,

patches within the stand (for illustration, say 20 percent of

stand area in patches of different size and pattern) are

reduced in stocking to 50 percent to establish the second

age class. Throughout the matrix of the stand between the

patches, trees that are unlikely to survive the cutting cycle

are marked for removal, otherwise stocking is maintained

between 60 and 75 percent. After one cutting cycle, another

20 percent of patch area across the stand is reduced to 50

percent stocking; the section initially treated is reduced to

40 percent stocking, and the remaining 60 percent of the

stand is examined for potential mortality and thinned to

retain vigor. The cycle is continued until the entire stand

has received the full series of conversion entries described

in the uniform method, at which time the dominant overstory

of the last portion of the stand is 175 years old (assuming

the series was initiated in a 60-year-old stand). Each 20

percent portion of the stand may be treated as a contiguous

block, or may be treated as several smaller patches that

together equal 20 percent.

This patch approach to conversion results in a more even

flow of timber throughout the conversion process and has

the potential to ensure a regular income and a merchantable harvest with each entry. However, the ability to use this

approach is dependent on the size of the ownership and

local market conditions, which determine whether harvests

of a given volume are operable. Mature patch conversion is

also constrained by the age and species composition of the

stand. Under this scenario, the length of time required to

complete the conversion may extend from 30 to 60 years

beyond that of the uniform reduction strategy.

Overmature Stands or Short-Lived Species

Finally, one should consider those situations where the

existing dominant canopy will not survive the conversion

period. The immature method is applicable when the overstory trees in a stand either should not be retained or where

they will only survive the establishment of a single new age

class. The two mature stand methods assume that the overstory is capable of surviving the entire conversion process

(three new age classes). If, however, the dominant overstory is expected to die after the establishment of the second

age class, one should modify the allocation of growing space

during initial stand entries so that control of density in the

most subordinate age class becomes paramount. These

stands need to be regenerated as soon as possible, and

this prescription ensures that outcome (table 1c).

Wherever possible, the dominant overstory should be

retained for as long as it can be maintained in a vigorous

condition. However, in the case of an overmature stand, a

substantially greater portion of the growing space must be

allocated to the first cohort established during the conversion process because it will be used to constrain density in

succeeding cohorts.

The preparatory thinning is similar to the uniform methods.

Stocking is reduced uniformly by no more than one third to

not less than 60 percent stocking. The first cutting cycle

reduces overstory stocking to 40 percent, allocating 20 percent to the first new cohort. The second cutting cycle reduces

overstory density to 30 percent stocking, leaving 30 percent

for the subordinate age class. The third cutting cycle removes

the original overstory rather than allowing it to die piecemeal over time. The first cohort is thinned to 40 percent

stocking, allocating 20 percent to the second cohort. The

first cohort is cut back to 40 percent during the fourth cutting

cycle; no treatment is required in the subordinate cohort.

Conversion is completed with the fifth cutting cycle; the first

cohort is thinned to 30 percent stocking and the second

cohort to 20 percent, leaving 10 percent stocking available

for the establishment of a third.

Stand Structure—Is q Relevant During

Conversion?

All of these prescriptions have one attribute in common—

aggressive efforts to develop new age classes when called

to do so. Eventually, a more formalized uneven-aged regulation method will be implemented to supplement and guide

the retention of given levels of stocking in the different age

classes. Thus, structural control will become essential for

creating and maintaining an uneven-aged stand. During

conversion, growing space has been allocated based solely

on canopy position. Yet, it was never suggested that during

the conversion period the stand should be marked to a

guiding curve. Although a q based (or similar) approach is

essential for maintaining an uneven-aged structure in an

oak-dominated system (Larsen and others 1999), q has no

place in stand conversion!
268

Conversion of a stand to an uneven-aged structure cannot

be accomplished in the same manner as the maintenance

of stand structure in an existing uneven-aged stand. During

the conversion process, one should be treating each age

class independently, thinning each from below—in effect,

cut the worst and leave the best (Baker and others 1996)

within an age class. Unfortunately, following conversion when

one has three age-classes intermingled intimately on the

same area, canopy tiers become less distinct; thus, it

becomes more difficult to thin each cohort from below. It

becomes increasingly difficult to recognize the difference

between age classes (trees from all three age classes may

be found in the same diameter class). The guiding curve is

simply a methodology for ensuring the maintenance of a

sustainable stand structure. It differs from the conversion

prescriptions in that one would cut the worst from each size

class (rather than age class) and growing space is allocated by diameter class (rather than by age class).

SUMMARY

The choice of a conversion strategy is most dependent on

the expected longevity of the dominant overstory. If it will

survive the establishment of one new age class, or if it is

an immature stand, use the immature method. If it will survive the establishment of two new age classes, use the

overmature method. If a substantial portion of the original

overstory will survive the establishment of three new age

classes, then either of the two mature stand methods is

appropriate.

The goal at the end of conversion is to have partitioned

growing space (stocking) among age classes/canopy tiers

in a ratio of 30:20:10. This stand structure maintains a large

proportion of the growing space in sawtimber and controls

the density of small diameter trees (reducing the need for

pre-commercial thinning). Even so, it allocates sufficient

growing space to the most subordinate age class ensuring

sustainable recruitment into the overstory.

The length of the cutting cycle is affected by residual stand

density and growth rates. If a longer cutting cycle is desired,

residual stand density must be reduced. Otherwise, one

increases the risk of losing the youngest age class in the

stand. Density dependent mortality begins in the most

subordinate age class when the stocking level of all trees in

a superior crown position reach full stocking.

There is no need to recruit a new cohort of trees into the

stand with each cutting cycle. To recruit a new cohort, total

stand stocking must be reduced to approximately 50 percent; this should be done only when needed to maintain

three age classes in the stand. Alternatively, stocking of the

midstory and overstory should be reduced to 50 percent,

leaving 10 percent stocking available for the existing understory, thus maintaining a fully stocked stand.

ACKNOWLEDGMENTS

The authors would like to gratefully acknowledge the USDA

Forest Service, North Central Research Station, for their

support of the research leading to the development of this

paper.

LITERATURE CITED

Baker, J.B.; Cain, M.D.; Guldin, J.M. [and others]. 1996. Unevenaged silviculture for the loblolly and shortleaf pine forest cover

types. Gen. Tech. Rep. SO-118. U.S. Department of Agriculture,

Forest Service, Southern Research Station, Asheville, NC. 65 p.

Barrett, J.W., ed. 1995. Regional silviculture of the United States.

3rd edition, John Wiley and Sons, New York. 551 p.

Gin[g]rich, S.F. 1967. Measuring and evaluating stocking and

stand density in upland hardwood forests in the Central States.

Forest Science 13: 38-53.

Guldin, James M.; Baker, James B. 1998. Uneven-aged silviculture, southern style. Journal of Forestry 96(7): 22-26.

Johnson, P.S. 1993. Perspectives on the ecology and silviculture

of oak-dominated forests in the Central and Eastern States.

Gen. Tech. Rep. NC-153. U.S. Department of Agriculture,

Forest Service, North Central Forest Experiment Station, St.

Paul, MN. 28 p.

Larsen, D.R.; Loewenstein, E.F.; Johnson, P.S. 1999. Sustaining

recruitment of oak reproduction in uneven-aged stands in the

Ozark Highlands. Gen. Tech. Rep. NC-203. U.S. Department of

Agriculture, Forest Service, North Central Research Station, St.

Paul, MN. 11 p.

Loewenstein, E.F. 1996. An analysis of the size- and age-structure

of an uneven-aged oak forest. Columbia, MO: University of

Missouri. 167 p. Ph.D. dissertation.

Loewenstein, E.F.; Garrett, H.E.; Johnson, P.S.; Dwyer, J.P. 1995.

Changes in a Missouri Ozark oak-hickory forest during 40 years

of uneven-aged management. p 159-64. In: Proceedings, 10th

Central Hardwood Forest Conference. Gottschalk, K.W.;

Fosbroke, S.L.C. (eds.). Gen. Tech. Rep. NE-197. U.S.

Department of Agriculture, Forest Service Northeastern Forest

Experiment Station, Radnor, PA. 577 p.

Loewenstein, E.F.; Johnson, P.S.; Garrett, H.E. 2000. Age and

diameter structure of a managed uneven-aged oak forest.

Canadian Journal of Forest Research 30(7): 1060-70.

Miller, G.W. 1996. Epicormic branching on central Appalachian

hardwoods 10 years after deferment cutting. Res. Pap. NE-702.

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

Forest Experiment Station, Radnor, PA. 9 p.

Roach, B.A.; Gingrich, S.F. 1968. Even-aged silviculture for upland

central hardwoods. Ag. Hdbk. 355. U.S. Department of

Agriculture, Forest Service, Washington D.C. 39 p.

Sander, I.L.; Clark, F.B. 1971. Reproduction of upland hardwood

forests in the Central States. Agriculture Handbook 405. U.S.

Department of Agriculture, Forest Service, Washington, D.C.

25 p.

Sander, I.L.; Graney, D.L. 1993. Regenerating oaks in the Central

States. p 174-83. In: Oak Regeneration: Serious Problems,

Practical Recommendations. Loftis, D.L.; McGee, C.E. (eds.).

Gen. Tech. Rep. SE-84. U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station, Asheville,

NC. 319 p.

Trimble, G.R., Jr. 1970. Twenty years of intensive uneven-aged

management: effect on growth, yield, and species composition

in two hardwood stands in West Virginia. Res. Pap. NE-154.

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

Forest Experiment Station, Upper Darby, PA. 12 p.

Weitzman, S.; Trimble, G.R., Jr. 1957. Some natural factors that

govern the management of oaks. Stn. Pap. No. 88. U.S.

Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station, Upper Darby, PA. 40 p.
269

INTRODUCTION

The history of disturbance in the lower Cumberland Plateau

region is similar to other forested sites that are dominated

by mixed upland hardwoods. Harvesting practices have

generally tended toward high grading, leading to stands of

lower quality than expected on many sites. One possible

reason for the lack of management in these upland forests

may be a high level of uncertainty about viable silvicultural

options and their results (Dubois and others 1997). Loftis

(1992) previously outlined two problems associated with

regenerating these stands. First, oaks (Quercus spp.) demonstrate better regeneration on lower quality, xeric sites, and

second, oaks are poor competitors with other species, particularly yellow-poplar (Liriodendron tulipifera L.) and shadetolerant canopy species.

Most desirable species in oak-dominated forests or in forests

where oaks are prominent components are intolerant of

shade. Therefore, all or most of a stand must be removed

in order to develop a new age class.

Natural regeneration comes from three sources: (1) stump

or root sprouts, (2) advance reproduction, and (3) new seedlings established after a disturbance (Beck 1980). The oak

component in a new stand comes predominantly from

advance reproduction and stump sprouts (Beck 1970, Loftis

1990, McQuilken 1975, Roach and Gingrich 1968, Sander

1972, Sander and Clark 1971). That is, these pre-existing

vegetative structures persist through the disturbance of a

regeneration cutting. Acorns that germinate after cutting

provide new seedlings, but growth of these seedlings is slow,

and they rarely reach a dominant or codominant position in

the new stands (Loftis 1983, Sander 1972). Yellow-poplar,

a major competitor with oaks on productive sites, demonstrates a different reproductive strategy. While new yellowpoplar in a stand may also come from stump sprouts from

trees removed during the harvest and advance reproduction that existed prior to cutting, it also regenerates

successfully from new seedlings established after harvest

(Beck 1970, Clark and Boyce 1964). Seedlings are often

very numerous and on better sites can dominate the

composition of the new stand (Beck and Hooper 1986,

Merz and Boyce 1958, Sander and Clark 1971). In some

other upland hardwood systems, desirable species such as

ash (Fraxinus spp.) and black cherry (Prunus serotina

Ehrh.) can also regenerate from new seedlings.

The oak strategy—pre-existing vegetative structures persisting through disturbance—is characteristic of the vast majority of upland hardwood species (Beck 1980, Johnson 1977,

Loftis 1990). Prior to stand disturbance, because most

species depend on advanced growth, an inventory of the

number and size-class distribution of each species along

with an estimate of new seedlings can predict the postharvest species composition. Researchers have developed

methods for evaluating the natural regeneration potential of

upland oak forests (Johnson 1977; Johnson and Sander

1988; Loftis 1988, 1990; Lowell and others 1987; Marquis

and Ernst 1988; Sander and others 1976, 1984; Waldrop

and others 1986). Following a model developed by Loftis

(1989), this study uses size of advance growth, estimates

of new seedling establishment, and competitiveness of

various regeneration sources present to predict species

composition after heavy regeneration cuts on two distinct

land types. This paper examines model predictions of regeneration on stands located in north Alabama and compares

these predictions between stands found on two distinct

ecoregions.

SITES

Six upland hardwood stands located in Jackson County, AL,

were surveyed in the summer of 2001. These stands can

be broadly divided into two groups associated with the

strongly dissected southern portion the mid-Cumberland

Plateau region (Smalley 1982).

The first group of stands was located on the strongly dissected margins and sides of the plateau (the escarpment).

The second group was located on the weakly dissected

plateau surface (the plateau). The uniqueness of testing

how stands located on these two landscape associations

lies in their physiography and management potential. On

REGENERATION POTENTIAL OF SELECTED FORESTED STANDS ON

THE CUMBERLAND PLATEAU OF NORTH ALABAMA

Callie Jo Schweitzer, David L. Loftis, Yong Wang, and Greg C. Janzen1

1 Research Forester, USDA Forest Service, Southern Research Station, Normal, AL 35762; Project Leader, USDA Forest Service, Southern

Research Station, Asheville, NC 28806; Associate Professor, Alabama A&M University, Normal, AL 35762; and Lands Manager,

MeadWestvaco Corporation, Stevenson, AL 35772, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Forested areas in the Cumberland Plateau region have experienced a myriad of disturbances over the last

century. As a result, hardwood forests, such as those found in north Alabama, contain a mixture of species with wide

ranges of shade tolerance and growth rates. Both site characteristics and past disturbance history have contributed to

stands that are considered low to medium quality. Research into the outcome of regenerating these stands is limited. In

this paper, we evaluated possible regeneration outcomes in several stands using a regeneration model that ranks

expected postharvest performance based on reproduction origin, size, and competitiveness.
270

the plateau, soils are moderately deep-to-deep, loamy, and

clayey; slope does not exceed 10 percent. Soil drainage is

considered well drained, and soil fertility is low. Site index is

60 (base age 50) for upland oaks and 85 (base age 50) for

yellow-poplar, which typically occurs on concave surfaces

on the plateau (Smalley Land type 1, broad, undulating

sandstone uplands) (Smalley 1982). Oak reproduction is

usually prolific on these sites, although tree size may be

small. Clearcutting is commonly employed for regeneration,

because competition is sparse and oak reproduction

numbers are high.

On the escarpment, soils are deep to very deep and loamy.

Soil drainage is considered well drained, soil fertility is moderate to moderately low, while slopes range from 5 to 70

percent. Stands on the escarpment surveyed for this study

have slopes from 15 to 30 percent. Upland oak site index is

75 to 80, and yellow-poplar site index is 100 (Smalley Land

type 16, plateau escarpment and upper sandstone slopes

and benches, north aspect) (Smalley 1982). These stands

are mixed mesophytic types; beneath mature stands oak

reproduction numbers are low, the size is typically small,

and competition, particularly by yellow-poplar, is great.

PROCEDURES

Researchers have studied species composition of regeneration and its predicted response following disturbance in

the Southern Appalachian forest and in other predominantly

deciduous forest regions. Prediction of oak response has

led to the development of a regeneration model (Loftis

1989). Composition of a new stand following a regeneration

cut is a function of the species composition and size structure of the advance reproduction and overstory of the existing stand; as well, new seedlings become established shortly

after harvest. In particular, the model uses height as a basis

for ranking expected postharvest performance of advance

reproduction. Stump sprouts of the various species (from

stems > 1.5 inches in diameter at breast height (d.b.h.) are

assigned a rank for expected postharvest performance and

a probability of sprouting. If data are available, a provision

is also made for estimating probability of sprouting as a

function of stem d.b.h. For the few species able to regenerate from new seedlings established after disturbance, a

ranking of expected postharvest performance is assigned to

new seedlings, and a probability of new seedling establishment is estimated.

The regeneration model accompanies an inventory of the

existing stand that uses small (0.01 acre) regeneration

plots to enumerate all existing regeneration sources. In

particular, the model uses advance reproduction by height

class and overstory trees (stems > 1.5 inches d.b.h.) that

can potentially produce stump sprouts. The best performing

regeneration sources present on each plot are chosen as

“winners” based on their competitive rankings (table 1).

Rules in the model chose fewer winners when spaceconsuming stump sprouts occur, and algorithms deal with

ties if numerous individuals have the same rank.

Choosing winners on each plot in this fashion treats competition explicitly; i.e., the best competitors on these small

plots are the winners. The use of small regeneration plots

provides a representation of the variation in competitive

situations in the stand. Combined data from the individual

plots provide a summary of stand-level results. Overall, the

results provide a projection of likely species composition

of dominant and codominant stems at the time of crown

closure. Since there are stochastic elements in the model,

multiple simulations provide not only a mean regeneration

outcome, but also a range of regeneration outcomes.

Six stands were inventoried in the summer of 2001. Twentyone regeneration plots were randomly located within each

stand. All trees on a 0.01-acre plot were tallied by species

and 1-foot height classes following the categories 0 to 0.9

feet, 1.0 to 1.9 feet, 2.0 to 2.9 feet, 3.0 to 3.9 feet, > 4.0

feet but < 1.4 inches d.b.h., and > 1.5 inches d.b.h. Sixtythree 0.01-acre plots were inventoried on forested tracts on

the escarpment (3 stands with 21 inventory plots each), and

63 were inventoried on the plateau. Overstory tree data

(species, height, and d.b.h.) were obtained on 0.025-acre

plots corresponding to the regeneration plots. Each stand

was run through the regeneration model 20 times, and

model output for the stand summary was assessed. The

site index used for the plots on the plateau was < 75; site

index for stands on the escarpment was set at > 75.

Table 1—Ranking of expected postharvest performance

Ranking Expected postharvest performance

1 Yellow-poplar-SP, black cherry-SP, black locustSP, basswood-SP

2 Red maple-SP, sugar maple-SP, silverbell-SP,

Fraser magnolia-SP, cucumber-SP, ash-SP, birchSP, white pine-L, yellow-poplar-L, black cherry-L,

birch-L

3 Basswood-L, yellow-poplar-M, black cherry-M,

birch-M, silverbell-L, Fraser magnolia-L

4 Oak-SP, oak-L, ash-L, red maple-L, cucumber-L,

hickory-SP, dogwood-SP, sourwood-SP,

blackgum-SP, beech-SP, buckeye-SP, yellowpoplar-S, birch-S, black cherry-S, sugar maple-L,

hemlock-L, white pine-M

5 Yellow-poplar-SE, black cherry-SE, birch-SE, oakM, basswood-M, ash-M, red maple-M, silverbellM, Fraser magnolia-M, cucumber-M, white oakSP, hickory-L, dogwood-L, sourwood-L,

blackgum-L, beech-L, buckeye-L, fire cherry-SE,

sugar maple-M

6 Hickory-M, white oak-M, sourwood-M, blackgumM, beech-M, buckeye-M, hemlock-M, white pine-S

7 Oak-S, ash-S, basswood-S, silverbell-S, Fraser

magnolia-S, red maple-S, dogwood-M

8 White oak-S, hickory-S, dogwood-S, sourwood-S,

blackgum-S, beech-S, buckeye-S

SP = stump sprout; L = large advance reproduction (> 4 feet; > 3

feet for yellow-poplar); M = medium advance reproduction (> 2 feet;

≥ 1 feet < 3 ft for yellow-poplar); S = small advance reproduction

(< 2 feet; < 1 ft for yellow-poplar); SE = new seedlings established

after harvest.
271

RESULTS

Tree stand composition differed at each site. Stands located

on the plateau averaged 130.3 square feet of basal area

per acre (BA/A) and had 554 stems per acre (SPA) (table 2).

In these stands the dominant species were oaks (Q. alba

L., Q. prinus L., Q. velutina Lamarck, Q. coccinea Muenchh.),

representing 79 percent of the total BA/A. Other common

mid- and overstory species on the plateau included sourwood (Oxydendrum arboreum DC.), red maple (Acer rubrum

L.), and hickory [Carya glabra Sweet, C. ovata K., C. glabra

var. odorata (Marsh.) Little,C. ovalis (Wangenh.) Sarg.],

representing 7, 6, and 4 percent of the total BA/A. On the

escarpment, basal area averaged 108.6 square feet per

acre, with 124 SPA. Oaks (Q. alba, Q. prinus, Q. velutina,

Q. rubra L.) accounted for 37 percent of the total BA/A of

stands on the escarpment, followed by hickories (17 percent), sugar maple (A. saccharum Marsh.)(13 percent), and

yellow-poplar (13 percent). Species richness was higher on

the escarpment compared with the plateau.

There were more mid- and overstory canopy (canopy) SPA

on the escarpment compared with the plateau. Escarpment

trees had a quadratic mean diameter (q.m.d.) of 11.4 inches,

with a range from 1.6 to 35.8 inches d.b.h. Quadratic mean

diameter of plateau trees was 5.4 inches (1.6 to 24.0 inches

d.b.h. range). Red oaks on the escarpment averaged 6 SPA,

were 11 percent of the total BA/A, and had a q.m.d. of 18.7

inches. White oaks, at 19 SPA and 26 percent of the total

BA/A, averaged 16.4 inches q.m.d. The q.m.d. for escarpment sourwood, red maple, black locust (Robinia pseudoacacia L.), sassafras [Sassafras albidum (Nutt) Nees], sugar

maple, and yellow-poplar was 10.1 inches. White oaks on

the plateau were 35 percent of the total BA/A, averaging

208 SPA, 6.3 inches q.m.d., with a range of 1.9 to 16.0

inches d.b.h. Plateau red oaks had 44 percent of the total

BA/A and 44 SPA, averaging 15.4 inches q.m.d. (range 1.6

to 27.4 inches d.b.h.). The q.m.d. of plateau blackgum

(Nyssa sylvatica Marsh.), sourwood, red maple, and sassafras was 3.5 inches.

The regeneration tally appears in table 3. There were 9,713

SPA tallied for plateau stands and 9,527 SPA for escarpment

stands. Of these totals, 67 percent of plateau reproduction

and 66 percent of escarpment reproduction were < 1 foot in

height. The majority of these small size-class stems was in

the “other” species category (Diospyros virginiana L.,

Magnolia acuminata L., Ulmus spp., Cercis canadensis L.,

Ostrya spp., Ilex spp., Vaccinium spp., and others). Small

stems of oak were 28 percent of the total on the plateau

and 13 percent on the escarpment. On the plateau, 468 SPA

were > 1.5 inches d.b.h., or 5 percent of the reproduction

total. Species distribution in this size class was 31 percent

white oaks, 21 percent sourwood, 14 percent blackgum,

and 13 percent red maple. On the escarpment, 229 SPA

were 1.5 inches d.b.h. or larger (4 percent of the total number of stems) and were distributed as 32 percent sugar

maple, 15 percent others, 11 percent hickory, and 9 percent

blackgum.

The model predictions of SPA at crown closure appear in

table 4. The model predicted an average of 462 SPA for

stands on the escarpment, consisting of 27 percent black

cherry, 21 percent black locust, 15 percent sugar maple,

and 12 percent yellow-poplar. For plateau stands, the model

Table 2—Preharvest stand composition for escarpment and plateau

stands in north Alabama

Escarpment Plateau

Species BA/A Total SPA Total BA/A Total SPA Total

% % %%

Red oaks 11.5 11 6 5 56.6 44 44 8

White oaks 27.9 26 19 15 45.9 35 208 38

Ash2.3 2 3 2 0 0 0 0

Black cherry 1 1 1 1 0 0 0 0

Black locust 1.5 1 3 2 0 0 0 0

Blackgum 6.6 6 8 6 1.7 1 52 9

Basswood 0.9 1 2 2 0 0 0 0

Beech 2.6 2 4 3 0 0 0 0

Dogwood 0.4 0 1 1 0.1 0 4 1

Hickories 18.2 17 22 18 5 4 22 4

Red maple 4.4 4 11 9 7.6 6 82 15

Sassafras 0.8 0.5 2 2 1.3 1 18 3

Sourwood 1.7 2 4 3 9.5 7 114 21

Yellowpoplar 14 13 13 10 2.6 2 8 1

Sugar maple 14.1 13 23 19 0 0 0 0

All others 0.7 0.5 2 2 0.04 0 2 0

Total 108.6 100 124 100 130.3 100 554 100

BA/A = basal area per acre in square feet; SPA = number of stems per acre.
272

Table 3—Preharvest regeneration average stems per acre and percent of totals by size classes for escarpment and plateau stands

in north Alabama

< 1 foot > 1 foot – < 1.5 feet d.b.h. > 1.5 feet d.b.h. All classes

Species Escarpment Plateau Escarpment Plateau Escarpment Plateau Escarpment Plateau

ASPA Total ASPA Total ASPA Total ASPA Total ASPA Total ASPA Total ASPA Total ASPA Total

no. % no. % no. % no. % no. % no. % no. % no. %

Red oaks 186 3 1,014 16 16 1 162 6 3 1 38 8 205 2 1,214 13

White oaks 649 10 790 12 29 1 168 6 14 6 143 31 692 7 1,102 11

Ash 281 4 14 0 141 5 3 0 13 6 0 0 435 5 17 0

Black cherry 235 4 79 1 65 2 40 1 0 0 0 0 300 3 119 1

Black locust 5 0 5 0 14 0 17 1 2 1 2 0 21 0 24 0

Blackgum 171 3 90 1 89 3 113 4 21 9 65 14 281 3 268 3

Basswood 2 0 0 0 11 0 0 0 0 0 0 0 13 0 0 0

Beech 27 0 2 0 113 4 5 0 13 6 0 0 152 2 6 0

Dogwood 3 0 0 0 17 1 0 0 2 1 0 0 22 0 0 0

Hickories 332 5 225 3 48 2 57 2 25 11 40 8 405 4 322 3

Red maple 562 9 571 9 67 2 179 6 11 5 60 13 640 7 810 8

Sassafras 275 4 1,090 17 130 4 279 10 3 1 13 3 408 4 1,383 14

Sourwood 11 0 2 0 11 0 75 3 8 3 97 21 30 0 173 2

Yellowpoplar 29 0 0 0 13 0 2 0 6 3 3 1 48 0 5 0

Sugar maple 1,211 19 0 0 360 12 0 0 73 32 0 0 1,644 17 0 0

All others 2,287 37 2,595 40 1,910 63 1,667 60 35 15 8 2 4,232 44 4,270 44

Totals 6,265 6,478 3,033 2,767 229 468 9,527 9,713

ASPA = average stems per acre; d.b.h. = diameter at breast height.

Table 4—Average stems per acre of predicted stand-level winners and

post-harvest proportion in stand by species for escarpment and

plateau stands in North Alabamaa

Escarpment Plateau

Preharvest Preharvest

Predicted regeneration Predicted regeneration

Species SPA Total total SPA Total total

 - - - - percent - - - - - - - - - percent - - - - -

Red oaks 3 1 2 16 5 13

White oaks 5 1 7 61 18 11

Ash 23 5 5 0 0 0

Black cherry 124 27 3 28 8 1

Black locust 97 21 0 15 4 0

Blackgum 12 3 3 44 13 3

Basswood 4 1 0 0 0 0

Beech 6 1 2 0 0 0

Dogwood 2 0.5 0 0 0 0

Hickories 10 2 4 20 6 3

Red maple 23 5 7 69 20 8

Sassafras 5 0.5 4 32 9 14

Sourwood 2 1 0 47 14 2

Yellowpoplar 56 12 0 2 1 0

Sugar maple 71 15 17 0 0 0

All others 19 4 44 7 2 44

Totals 462 341

SPA = stems per acre.

a Regeneration percentages for all size classes for preharvest stand data are also

listed.
273

predicted 341 SPA, with 23 percent of this total oak, 20 percent red maple, 14 percent sourwood, and 13 percent

blackgum. For those species categorized in “all others,”

note that these species are not necessarily eliminated from

the new stand, but their dominance is altered in the predicted output.

The total predicted SPA of all oak species was greater on

the plateau (77 SPA) compared with the escarpment (8 SPA).

This difference is a reflection of the advanced growth-dependent reproductive strategy of oak and of stand composition

prior to disturbance. On the plateau, 79 percent of the BA/

A, and 46 percent of canopy SPA were oak. Oaks were also

well represented in the reproduction tallies, averaging 24

percent of the total SPA, with 22 percent of the total oaks

tallied > 1 foot tall. Large advance reproduction appeared

as highly ranked winners in the model output (ranked fourth

as stump sprouts). Oaks’ competition were red maple stump

sprouts (ranked second), sourwood stump sprouts and

large seedlings (ranked fourth and second, respectively),

and blackgum stump sprouts (ranked fourth). On the escarpment, oaks were 37 percent of the total stand BA/A, and 20

percent of the total canopy SPA. Only 9 percent of the

advance reproduction total was oak, and only 7 percent of

all oak advance reproduction was > 1 foot tall.

The four primary species competing with oak on the escarpment were black cherry, black locust, yellow-poplar, and

sugar maple. Sugar maple was well represented on the

escarpment (13 percent of the BA/A, and 23 percent of the

canopy SPA). Reproduction of sugar maple averaged 1,644

SPA, with 74 percent of these stems < 1 foot tall. The shade

tolerance of sugar maple and its ability to reproduce under

an overstory of sugar maple and other less tolerant species,

as well as the escarpment’s higher site quality compared to

the plateau, supports these predictions. The presence of

yellow-poplar in the overstory should have increased the

likelihood of new yellow-poplar seedlings postdisturbance,

but did not (12 percent predicted postdisturbance compared

with 13 percent of total SPA canopy predisturbance). Black

cherry and black locust were predicted as higher proportions of the new escarpment stands than was yellow-poplar.

Both yellow-poplar and sugar maple were minor components

of plateau stands and retained this status in the new stands.

The proportion of the stands occupied by black cherry and

black locust was predicted to increase substantially following overstory removal. On the escarpment, black cherry

stems increased from 1 canopy SPA to 124. The presence

of black cherry in the overstory (3 percent of the BA/A) and

the presence of medium-sized reproduction (22 percent of

the total reproduction, 65 of 300 black cherry SPA) contributed to its response, ranked first as stump sprouts and

third as medium-sized reproduction. Although black cherry

was not present in the overstory on the plateau, 17 SPA

were tallied as advanced reproduction, and 43 percent of

the total was medium-sized. The model predicted 28 SPA

of black cherry, or 8 percent of the total stand composition.

The lack of other high-ranking competition allowed for black

cherry to assume this proportion in the new stand.

On the escarpment, black locust was predicted to have 97

SPA, or 21 percent of the total number of stems. Prior to

disturbance, black locust had three SPA canopy and 1 percent of the BA/A. The number of black locust stems tallied

was 21 SPA, with 67 percent of these stems in the mediumsized reproduction class. These black locust were winners

(ranked first) postdisturbance, primarily as sprouts. Although

black locust was not present in the overstory on the plateau,

71 percent of the 24 SPA tallied in the plateau reproduction

were medium sized. Postdisturbance, these contributed to

15 SPA of black locust, or 4 percent of the total SPA.

CONCLUSIONS

Topographic position often dictates management in the

Cumberland Plateau region. In general, clearcutting regenerates stands on the plateau, as lower site quality, less

competition from other species, and relatively high numbers

of advance reproduction of oaks contribute to a desirable

species composition in the next stand. After disturbance, 23

percent of the new stand was predicted to be oak, followed

by red maple and sourwood.

If the preservation of the oak component for escarpment

stands is desired, management techniques can encourage

more and larger advanced oak reproduction and can reduce

competition. Following Loftis (1983), altering the light level

by reducing overstory or midstory basal area is being tested

on escarpment stands to examine the impact on oak regeneration. The large increase in black cherry and black locust

and the relatively unchanged proportion of yellow-poplar

that the model predicted were surprising. Black cherry is a

small component of escarpment stands and most likely will

not be competitive after crown closure. The rapid growth,

shade intolerance, and short-lived nature of black locust

negates its importance as a long-term competitor (McGee

and Hooper 1975). However, yellow-poplar may play a more

dominant role than predicted by the model, as documented

by others on similar sites (Beck 1970, Kuers and Kuthe

1998, Loftis 1988, McGee 1967). Results from these predictions will be compared with measured response in the

field, and the model will be adjusted accordingly.

LITERATURE CITED

Beck, D.E. 1970. Effect of competition on survival and height

growth of red oak seedlings. Res. Pap. SE-56. Asheville, NC:

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

Forest Experiment Station. 7 p.

Beck, D.E. 1980. Natural regeneration of southern hardwoods. In:

McElwee, R.L.; Bell, N.H., eds. Regenerating the southern

forests: tenth forestry and wildlife forum. Blacksburg, VA:

Virginia Polytechnic Institute and State University: 132-141.

Beck, D.E.; Hooper, R.M. 1986. Development of a Southern

Appalachian hardwood stand after clearcutting. Southern

Journal of Applied Forestry. 10: 168-172.

Clark, B.F.; Boyce, S.G. 1964. Yellow-poplar seed remains viable

in the forest litter. Journal of Forestry. 62: 564-567.

Dubois, M.R.; Stockman, J.L.; Golden, M.S. 1997. Silvicultural

assessment of alternative harvesting treatments in north

Alabama upland hardwood forests. In: Meyer, D.A., ed.

Proceedings of the twenty-fifth annual hardwood symposium.

Cashiers, NC: 113-122.

Johnson, P.S. 1977. Predicting oak stump sprouting and sprout

development in the Missouri Ozarks. Res. Pap. NC-149. St.

Paul, MN: U.S. Department of Agriculture, Forest Service,

North Central Forest Experiment Station. 9 p.
274

Johnson, P.S.; Sander, I.L. 1988. Quantifying regeneration potential of Quercus forests in the Missouri Ozarks. In: Ek, A.R.;

Shifley, S.R.; Burk, T.E., eds. Forest growth modeling and

prediction, Proceedings, mensuration, growth and yield, subject

group S4.01, IUFRO. Gen. Tech. Rep. NC-120. St. Paul, MN:

U.S. Department of Agriculture, Forest Service, North Central

Forest Experiment Station: 377-385.

Kuers, K.; Kuthe, V. 1998. Stand development 18 years after harvest of a high-quality hardwood site on the Cumberland Plateau

in Tennessee. In: Waldrop, T.A., ed. Proceedings of the ninth

biennial silvicultural research conference. Gen. Tech. Rep.

SRS-20. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southern Research Station: 583-589.

Loftis, D.L. 1983. Regenerating Southern Appalachian mixed hardwood stands with the shelterwood method. Southern Journal of

Applied Forestry. 7(4): 212-217.

Loftis, D.L. 1988. Regeneration oaks on high-quality sites, an

update. In: Smith, C.H.; Perkey, A.W.; Kidd, W.E., eds.

Proceedings of the guidelines for regenerating Appalachian

hardwood stands. Publ. 88-93. Bethesda, MD: Society of

American Foresters: 199-209.

Loftis, D.L. 1989. Species composition of regeneration after clearcutting Southern Appalachian hardwoods. In: Miller, J.H., comp.

Proceedings of the fifth biennial southern silvicultural research

conference. Gen. Tech. Rep. SO-74. New Orleans: U.S.

Department of Agriculture, Forest Service, Southern Forest

Experiment Station: 253-257.

Loftis, D.L. 1990. Predicting postharvest performance of advance

red oak reproduction in the Southern Appalachians. Forest

Science. 36(4): 908-916.

Loftis, D.L. 1992. Regenerating northern red oak on high-quality

sites in the Southern Appalachians. In: Meyer, D.A., ed.

Proceedings of the twenty-fifth annual hardwood symposium.

Cashiers, NC: 203-210.

Lowell, K.E.; Mitchell, R.J.; Johnson, P.S. [and others]. 1987.

Predicting growth and “success” of coppice-regenerated oak

stems. Forest Science. 33(3): 740-749.

Marquis, D.A.; Ernst, R.L. 1988. User’s guide to SILVAH, a stand

analysis, prescription and management simulator program for

hardwood stands of the Alleghenies. Warren, PA: U.S.

Department of Agriculture, Forest Service, Northeastern Forest

Experiment Station. 162 p.

McGee, C.E. 1967. Regeneration in Southern Appalachian oak

stands. Res. Note SE-72. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern Forest Experiment

Forest. 6 p.

McGee, C.E.; Hooper, R.M. 1975. Regeneration after clearcutting

in the Southern Appalachians. Res. Pap. SE-277. Asheville,

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

Southeastern Forest Experiment Forest. 3 p.

McQuilken, R.A. 1975. Growth of four types of white oak reproduction after clearcutting in the Missouri Ozarks. Res. Pap. NC116. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station. 5 p.

Merz, R.W.; Boyce, S.G. 1958. Age of oak “seedlings.” Journal of

Forestry. 54: 774-775.

Roach, B.A.; Gingrich, S.F. 1968. Even-aged management for

upland central hardwoods. Agric. Handb. 355. Washington, DC:

U.S. Department of Agriculture, Forest Service. 39 p.

Sander, I.L. 1972. Size of oak advance reproduction: key to growth

following harvest cutting. Res. Pap. NC-79. St. Paul, MN: U.S.

Department of Agriculture, Forest Service, North Central Forest

Experiment Station. 6 p.

Sander, I.L.; Clark, B.F. 1971. Reproduction of upland hardwood

forests in the Central States. Agric. Handb. 405. Washington,

DC: U.S. Department of Agriculture, Forest Service. 25 p.

Sander, I.L.; Johnson, P.S.; Rogers, R. 1984. Evaluating oak

advance reproduction in the Missouri Ozarks. Res. Pap. NC251. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station. 11 p.

Sander, I.L.; Johnson, P.S.; Watt, R.F. 1976. A guide for evaluating

the adequacy of oak advance reproduction. Gen. Tech. Rep.

NC-23. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Forest Experiment Station. 7 p.

Smalley, G.W. 1982. Classification and evaluation of forest sites

on the Mid-Cumberland Plateau. Gen. Tech. Rep. SO-38. New

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

Southern Forest Experiment Station. 58 p.

Waldrop, T.A.; Buckner, E.R.; Shugart, H.H., Jr.; McGee, C.E.

1986. FORCAT: a single tree model of stand development

following clearcutting on the Cumberland Plateau. Forest

Science. 32(2): 297-317.
275

INTRODUCTION

In many Midwestern and Eastern States, oak-hickory forests,

e.g., black (Quercus velutina), chestnut (Q. prinus), scarlet

(Q. coccinea), northern red (Q. rubra), white oak (Q. alba),

and shagbark (Carya ovata) and mockernut hickory (C.

tomentosa) are converting to forests dominated by maples

(e.g., red (Acer rubrum) and sugar (A. saccharum)), beech

(Fagus grandifolia), and tulip-poplar (Liriodendron tulipifera).

In Ohio, USDA Forest Service inventory data indicate that

the annual removal of white and red oaks (8 billion board

feet of sawtimber) equals or exceeds annual growth, while

the growth of maples and tulip-poplar, far exceeds removal

(~56 to 74 percent) (Griffith and others 1993). Currently,

oak regeneration on xeric sites is successful, but failures

are common on high-quality mesic sites (Abrams and Downs

1990). Fire suppression, deer browsing, pathogens, insect

herbivory, acorn predation, and inadequate competition for

limited resources such as light, soil nutrients, and moisture

contribute to the poor regeneration of oak (Johnson and

others 2002, Loftis and McGee 1993).

Fire has been a component of oak-hickory forests in central

Appalachian mixed-oak forests since pre-European settlement (Brose and others 2001). Since the 1930’s, fire has

been actively suppressed concurrent with a shift in the

composition of the understory and subcanopy to more

shade-tolerant and fire-intolerant species, e.g., maples.

In 1994, a large study was initiated in southern Ohio to

assess the use of low-intensity prescribed fires as a management tool to regenerate oaks, and to examine the effects

of fire at an ecosystem level (Sutherland and Hutchinson

2003). Preliminary findings indicate that despite annual and

infrequent burns, the canopy did not open sufficiently to

promote adequate oak regeneration (Personal communication. Daniel Yaussy. 2002. Research Forester, USDA Forest

Service, Northeastern Research Station, 359 Main Road,

Delaware, OH 43015). Consequently, a new study was

initiated in 2000 to assess the effects of overstory thinning

and fire on regenerating mixed-oak forests in southern

Ohio. It is one of 13 sites participating in the national Fire

and Fire Surrogates (FFS) Project, which has incorporated

a common “core” design to quantify the ecological and

economic impacts of prescribed fire and thinning. A multidisciplinary cooperative research team is studying how fire

and/or thinning treatments promote the sustainability of

mixed-oak ecosystems in central hardwood forests. In this

paper, we present the first-season posttreatment effects of

prescribed fires and thinning on the survival and health of

hardwood seedlings and saplings.

STUDY AREA

The Ohio Hills site of the FFS Project is replicated on three

study areas in southeastern Ohio: Zaleski State Forest (ZAL),

Tar Hollow State Forest (TAR), and Raccoon Ecological

Management Area (REMA). These sites have a highly

dissected topography with elevations ranging from 200 to

300 m, and slopes of 10 to 40 percent. Located within the

unglaciated Allegheny Plateau, the study area compromises

a variety of sandstones, shales, and clays. Each study area

is about 80 ha and is divided into four 20-ha treatment units:

thin only (T), burn only (B), thin+burn (TB) and control (C).

Within each treatment area, ten 50- by 20-m plots were

established across a range of moisture conditions (three

SURVIVAL OF HARDWOOD SEEDLINGS AND SAPLINGS

FOLLOWING OVERSTORY THINNING AND PRESCRIBED FIRES

IN MIXED-OAK FORESTS OF SOUTHERN OHIO

Joanne Rebbeck, Robert Long, and Daniel Yaussy1

1 Plant Physiologist, Research Plant Pathologist, and Research Forester, USDA Forest Service, Northeastern Research Station, Delaware,

OH 43015, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Prescribed fires in combination with thinning are being investigated as silvicultural tools in the regeneration of

mixed-oak forests in central Appalachia. Burns were conducted in spring 2001 within three forests in southern Ohio. Each

site was divided into four treatments of roughly 20 ha each: control (C), burn only (B), thin only (T), or thin plus burn (TB).

The basal area of T and TB stands was thinned from about 28 to 20 m2 ha-1 in the 4 months prior to the burns. Ten

seedlings (<140 cm tall) and 10 saplings [stems >140 cm tall and <10 cm in diameter at breast height (d.b.h.)] within each

of nine 1,000-m2

 plots in a treatment area at each site were evaluated before (2000) and after (2001) treatment. Oak and

hickory species were targeted for seedling evaluations. Dominant sapling species evaluated were red and sugar maple,

blackgum, hickory, and beech (oak was sparse or absence). At 4 months postburn, 0, 13, 62, and 80 percent of the

pretreatment seedlings were dead with living sprouts on the C, T, TB, and B plots, respectively. Nearly half of the 10

original saplings per plot were dead with sprouts in the TB and B plots (4.9 and 4.2). Sapling mortality (dead with no live

sprouts) was highest in TB plots (1.6 of original 10 per plot) compared with T (0.6), B (0.2), and C (0.07) plots. Seedling

mortality was highest in TB plots (3.4 seedlings of original 10 per plot), followed by T (2.2), B (1.6), and C (0.7) plots. We

anticipate that resprouting seedlings in the TB plots will respond vigorously to increased light conditions if maintained by

subsequent fires.
276

xeric, four intermediate, three mesic) determined by the

Integrated Moisture Index (IMI) (Iverson and others 1997).

Within each 50- by 20-m plot, ten 10- by 10-m subplots

were identified.

Due to logistical and personnel limitations, only 9 of the 10

plots in each treatment area were used. A plot was eliminated if its IMI value was redundant or nearly redundant

with another plot in the same treatment area; 108 plots

were used for the pathology and health evaluations of

seedlings and saplings.

THINNING AND PRESCRIBED FIRES

The initial basal area (BA) averaged 28.8 m2 ha-1 across all

areas. T and TB treatment areas were commercially thinned

from below to a BA of 20 m2 ha-1 during the fall and winter

of 2000. Low-intensity surface burns were conducted on

28 March and 4-5 April 2001 at the TAR, ZAL, and REMA

study sites. Air temperature was measured at 25 cm from

the forest floor with stainless steel temperature probes and

logged every 2 seconds with buried data loggers. Fires at

TAR were the least intense with maximum air temperatures

ranging from 21 to 226 °C in TB units and 21 to 293 °C in B

units. At ZAL, maximum air temperatures during fires ranged

from 42.2 to 414.6 °C in the TB unit and 63.8 to 397 °C in

the B unit. At REMA, maximum air temperatures ranged

from 50 to 354 °C in the B unit and 36.2 to 496 °C in the TB

unit. Details of the prescribed fires are reported elsewhere

(Iverson and others 2004).

PROCEDURES

Health Evaluations

In May and June 2000, 10 seedlings and 10 saplings were

identified in each plot. Seedlings were defined as woody

stems <140 cm tall and were further divided into three

height-based size classes: small (<10 cm), medium (10 to

50 cm), and large (50.1 to 140 cm). Saplings were defined

as >140 cm tall and <10 cm in diameter at breast height

(d.b.h.) and were divided into three d.b.h. classes: small

(<3 cm), medium (3 to 6 cm), and large (6.1 to 10 cm).

Attempts were made to ensure that individuals were distributed across the range of size classes for both seedlings

and saplings, and that they were distributed evenly across

the 50- by 20-m plot. For evaluations of seedling health,

tree species were selected in the following order of preference: Quercus spp., Carya spp., and others. Oaks and

hickories were preferred for saplings, but generally were

infrequent. As a result, health evaluations for saplings

focused on stems likely to be killed by fire, e.g., such as red

and sugar maple, blackgum (Nyssa sylvatica), and beech.

For seedlings, initial measurements included height to

terminal bud, basal diameter, and stem origin. If seedlings

were of sprout origin, the diameter of the root collar was

measured also. Since stems would be reevaluated numerous times over several years, seedlings were flagged and

locations were recorded on a plot map. Saplings were similarly identified and mapped but only d.b.h. was measured.

In all, 1080 seedlings and 1080 saplings were identified

(360 each within a study area).

Pretreatment health evaluations were conducted in June

and July 2000. For seedlings, number of leaves, leaf color

and size, crown shape, percent herbivory/disease/injury,

and percent fine twig dieback were determined using a

rating system adapted after Carvell (1967) and Gottschalk

(Personal communication. Kurt W. Gottschalk. 2000.

Research Forester, USDA Forest Service, Northeastern

Research Station, 180 Canfield St., Morgantown, WV

26505) (see table 1). If problems related to pathogens or

insects were obvious during evaluations, seedlings with

similar symptoms from off-plot locations were sampled

destructively to determine probable causal agents. Small

saplings were evaluated with the health protocols for seedlings. For medium and large saplings, evaluations of overstory health included crown vigor, percent dieback of fine

twig, percent herbivory/disease/injury, and presence or

absence of any stem injury (wounds and defects) (table 1).

Sapling protocols (stem injury, crown vigor, and dieback)

were adapted from methods developed for the North

American Maple Project (Cooke and others 1997). All

stems were reevaluated in June and again in late August/

September 2001 to determine postthinning and postfire

impacts.

RESULTS AND DISCUSSION

Pretreatment Evaluations

Shagbark, mockernut, bitternut [Carya cordiformis], and

pignut [C. glabra] hickory, represented ~35 percent of the

seedlings evaluated at each of three study sites (fig. 1a).

Oak (black, chestnut, red, scarlet, and white) represented

~64 percent of the seedlings evaluated at each site. Tulippoplar, white ash [Fraxinus americana], and American

chestnut [Castanea dentata]) represented 0 to 4 percent.

Eighty-four percent of the seedling stems originated from

seedlings with the remainder 16 percent originating from

sprouts.

Saplings evaluated were represented primarily by shadetolerant and fire-intolerant species. Red and sugar maples

represented 26 to 60 percent of the stems evaluated at

each study site (fig. 1b). Sugar maple was the dominant

species evaluated at TAR (40 percent), blackgum at ZAL

(28 percent), and hickory spp. at REMA (31 percent). Nearly

75 percent of the evaluated seedlings were 10 to 50 cm tall

while saplings were distributed more equally across all size

classes.

Posttreatment Evaluations

Survival and mortality of seedlings—Four months after

the prescribed fires (late August-early September 2001),

survival of the original 10 seedlings per plot averaged 0.37

(+0.14) and 0.41 (+0.13) in the TB and B units, respectively,

compared to average survival of 9.33 (+0.15) and 6.52

(+0.35) of the original 10 seedlings in the C and in the T

plots, respectively (fig. 2a). Sprouting was greatest in the B

plots (~80 percent), followed by the TB (~62 percent) plots

(fig. 2b). This level of postfire sprouting was anticipated

since oaks and hickories are fire-tolerant and readily sprout

from the root collar (Brose and Van Lear 1998). Seedling

mortality (dead with no live sprouts) was greatest in the TB

plots (~34 percent), followed by T (~22 percent), B (~16

percent) and C (7 percent) plots (fig. 2c).
277

Table 1—Health evaluation criteria and classes used to assess the effects of prescribed fire, thinning, and fire plus thinning on hardwood seedlings andsaplingsSeedlings and small saplings Medium and large saplings All saplings and seedlingsParameter Class Parameter Class Parameter ClassSize 1 = Small, < 10 cm tall Size 1 = Small, < 3 cm d.b.h., > 140 cm tall Stem injury W = Wounds

2 = Medium, 10 – 50 cm tall 2 = Medium, 3 – 6 cm d.b.h. C = Cracks3 = Large, 50.1 – 140 cm tall 3 = Large, 6.1 – 10 cm d.b.h. O = Open

1 = Closed

Origin S = Seedling Vigora 1 = Healthy, <10% dieback, discolor Diebacka 0 = No trace or dieback

P = Sprout 2 = 10 – 25% dieback, discolor 1 = < 10% dieback

3 = 26 – 50% dieback, discolor 2 = 11 – 25% dieback4 = 51 – 75% dieback, discolor 3 = 26 – 50% dieback5 = 76 – 100% dieback, discolor 4 = 51 – 75% dieback

Crown shape 1 = Normal, leader present 6 = Dead 5 = 76 – 100% dieback

2 = Flat-topped, no leader 6 = Dead3 = Flat-topped, with major fork below crown Herbivory and disease 0 = None, trace4 = Dead 1 = < 10%

2 = 11 – 25%3 = 26 – 50%

Leaf size 1 = Large, > 15 cm long 4 = 51 – 75%

2 = Medium, 10 – 15 cm long 5 = 76 – 100%3 = Small, < 10 cm long 6 = Dead

Leaf color 1 = Normal, dark green

2 = Light green between veins, and dark green along veins3 = Chlorotic, yellowish green between veins and light green along veins4 = Brown edges and tips

Leaf number 1 = < 10

2 = 10 – 253 = 26 – 504 = 51 – 1005 = 100+

a For dieback and sapling vigor estimates, only fine twigs included in estimates if other twigs with foliage present in the same area of bole or crown. Isolated dead twigs with no foliage

nearby considered dead due to shading excluded from estimates.
278

Figure 1—(a) Number of seedlings evaluated per species at REMA, Tar Hollow, and Zaleski study sites; (b) Number of saplings evaluated per

species at each site.

Survival and mortality of saplings—As expected survival

of original sapling stems was far greater than that observed

for seedlings. C plots had the highest survival at 98.9 percent (±0.6), while TB plots had the lowest at 48.5 percent

(±3.8) (fig. 3a). Survival was 90.4 percent (±1.7) in T plots

and 56.7 percent (±4.8) in B-only plots. At Tar Hollow, B

plots had the highest number of surviving original saplings

of all B and TB units. This was not surprising since the lowest maximum air temperatures during the prescribed fires

were observed at Tar Hollow. Likewise, the lowest number

of dead saplings with sprouts (2.9 saplings per plot) was

also observed at the TAR B-only unit (fig. 3c). Almost half of

the 10 original sapling stems per plot were dead with sprouts

in the TB (4.9 ±0.4) and B (4.2 ±0.5) plots (fig. 3b). Four

















	








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Figure 2—Survival of oak and hickory seedlings 4 months after low-intensity prescribed fires and/or overstory thinning at three sites in

southern Ohio: (a) mean number of original live stems per plot; (b) mean number of dead stems with live sprouts per plot; (c) mean

number of dead seedlings with no live sprouts.

months post-fire, sapling mortality (dead saplings with no

live sprouts) was highest in the TB plots (~16 percent of the

original saplings), compared with T alone (6.3 percent), B

alone (2 percent), and C (0.7 percent). Logging injury (stem

snapping, breakage, and wounding) was patchy and most

prevalent closest to cutting and skidding operations. In

some plots, the slash may have enhanced fuel loading or

provided fire breaks, depending on slope aspect, twig/

branch size and slash moisture content.













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Figure 3—Survival of hardwood saplings (<3 to 10 cm in d.b.h.) 4 months after low-intensity prescribed fires and/or overstory thinning

at three sites in southern Ohio: (a) mean number of original live stems per plot; (b) mean number of dead stems with live sprouts per

plot; (c) mean number of dead seedlings with no live sprouts per plot.

Sapling vigor—Vigor was assessed only for medium and

large saplings. The proportion of control saplings in the

healthy and light decline (10 to 25 percent dieback) vigor

classes did not change between 2000 and 2001 (fig 4a). The

proportion of T saplings in the severe decline vigor class

(76 to 100 percent) increased from 0 to 20 percent from preto post-treatment measurements (fig. 4b). In the B and TB

plots, there were dramatic increases in the proportion of

saplings with severe decline (76 to 100 percent dieback)

fig. 4c and d), particularly at REMA and ZAL where fires

were intense.













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Figure 4—Percentage of hardwood saplings in vigor classes (healthy = <10 percent dieback and discolor, light decline = 10 to 25 percent,

moderate decline = 26 to 50 percent, declining = 51 to 75 percent, severe declining = 76 to 100 percent, and standing dead) pretreatment

(2000) and posttreatment (2001) for control, thin, thin+burn, and burn units.

Dieback—Seedling dieback in control and burn plots averaged <10 percent (fig. 5a). Dieback was higher (11 to 25

percent) in the T and TB units. Since most of the B and TB

seedlings had resprouted, these evaluations indicated new

current-year stems. Not surprisingly, dieback of small saplings in B and TB plots was similar to that of seedlings (fig.

5b). For larger saplings, dieback was highest in the T and

TB plots, averaging 51 to 75 percent (fig. 5c). It is likely that

the position of these taller stems within the midcanopy

made them more prone to logging damage, as evidenced

by stem bending, breakage, and wounding, and thus more

vulnerable to fire-related injuries.

Incidence of foliar herbivory and disease—At 4 months

following the prescribed fires, there were no changes in

damage by foliar insects or diseases associated with thinning or burning among seedlings or small saplings (fig. 6).







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Mean herbivory-disease index values were similar across

treatments. Damage associated with foliar insects and

pathogens generally was insufficient in the summer of 2001

to adversely affect seedling or sapling growth.

SUMMARY

These first-season postfire results suggest that initial seedling and sapling mortality is highest when prescribed fire is

combined with overstory removal. The incidence of foliar

herbivory and disease was not affected by fire or thinning

treatments. Sprouting of seedlings and saplings (all size

classes) was common in both the B and TB units at all 3

study sites. We anticipate that resprouting seedlings in the

TB plots will respond vigorously to increased light conditions if maintained by subsequent fires. Competition from

fire-intolerant species such as red maple should be minimized with a second prescribed fire (planned for spring
282

Figure 5—Late summer assessments of dieback of hardwood seedlings and saplings following prescribed fires and/or overstory thinning:

(a) mean seedling dieback per plot; (b) mean small sapling dieback per plot; and (c) mean sapling dieback per plot. Rating of 1 = <10

percent dieback, while a rating of 5 = 76 to 100 percent dieback.







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Figure 6—Incidence of foliar herbivory and disease (Herbivory-Disease Index (HDI) on hardwood seedlings and saplings following

prescribed fires and/or overstory thinning: (a) mean seedling HDI per plot; (b) mean small sapling HDI per plot; and (c) mean sapling

HDI per plot. Rating of 1 = <10 percent, while a rating of 5 = 76 to 100 percent.







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2005). Fire improved height growth in oak and hickory and

enhanced stem form in oaks (Brose and Van Lear 1998).

Annual growth measurements and health evaluations of

these stems will allow us to determine whether prescribed

fire alone or combined with thinning results in larger and

more competitive oak and hickory stems compared to

unmanipulated controls in southern Ohio’s mixed-hardwood

forests.
284

ACKNOWLEDGMENTS

We thank David Hosack, Zachary Traylor, Mary Ann Tate,

Kristy Tucker, Brad Tucker, Ben Crane, Robert Ford, Justin

Wells, Jeff Matthews, Bert Smith, Spencer Wight, Eric Baker,

and Lisa Pesich for assistance in data collection and processing. This is contribution number 15 of the National Fire

and Fire Surrogate Research (FFS) Project, supported by

funds from the U.S. Joint Fire Science Program (JFSP).

This study was funded through the National Fire Plan of the

USDA Forest Service. Although the authors received no

direct funding from JFSP, this research could not have been

accomplished without its support of the existing National

FFS Research Project.

LITERATURE CITED

Abrams, M.; Downs, J.A. 1990. Successional replacement of oldgrowth white oak by mixed mesophytic harwoods in southwestern Pennsylvania. Canadian Journal of Forest Research.

20: 1864-1870.

Brose, P.; Schuler, T.; Van Lear, D.; Berst, J. 2001. Bringing fire

back, the changing regimes of the Appalachian mixed-oak

forests. Journal of Forestry 99: 30-35.

Brose, P.; Van Lear, D. 1998. Responses of hardwood advance

regeneration to seasonal prescribed fires in oak-dominated

shelterwood stands. Canadian Journal of Forest Research. 28:

331-339.

Carvell, K.L. 1967. The response of understory oak seedlings to

release after partial cutting. West Virginia Agricultural

Experiment Station, Bulletin 553.

Cooke, R.; Pendrel, B.; Barnett, C.; Allen, D.C. 1997. North

American maple project cooperative field manual. (5th rev).

Durham NH: U.S. Department of Agriculture, Forest Service,

Northeastern Area, State and Private Forestry.

Griffith, D.M.; DiGiovanni, D.M.; Witzel, T.L.; Wharton, E.H. 1993.

Forest statistics for Ohio, 1991. Resource Bulletin NE-128,

Radnor, PA: U.S. Department of Agriculture Forest Service,

Northeastern Forest Experiment Station. 169 p.

Iverson, L.R.; Dale, M.E.; Scott, C.T.; Prasad, A. 1997. A GISderived integrated moisture index to predict forest composition

and productivity of Ohio forests (U.S.A.). Landscape Ecology

12: 331-348.

Iverson, L.R.; Yaussy, D.; Rebbeck, J. [and others]. 2004. Spatial

and temporal distribution of fire temperatures from prescribed

fires in the mixed oak forests of southern Ohio. in J. Van

Sambeck, editor. Proceedings, Central Hardwoods Forest

Conference. Gen. Tech. Rep. NC-234. North Central

Experiment Station, USDA Forest Service, St. Paul, MN.

293-294.

Johnson, P.S.; Shifley, S.R.; Rogers, R. 2002. The ecology and

silviculture of oaks. New York, CABI Publishing. 503 p.

Loftis, D.L.; McGee, C.E., eds. 1993. Oak regeneration: serious

problems, practical recommendations. Gen. Tech. Rep. SE-84.

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

Southeastern Forest Experiment Station. 319 p.

Sutherland, E.K.; Hutchinson, T.F. 2003. Characteristics of mixedoak forest ecosystems in southern Ohio prior to the

reintroduction of fire. Gen. Tech. Rep. NE-299. Newtown

Square, PA: U.S. Department of Agriculture, Forest Service,

Northeastern Forest Experiment Station. 159 p.
285

INTRODUCTION

Disturbances of both natural and anthropogenic origin have

shaped forests in the Central Hardwood Forest Region for

centuries. Human-induced disturbances, such as fire and

clearing, have affected the region for approximately 10,000

years as large populations of native peoples and Europeans

have passed through or settled. By choosing to burn, clear,

or suppress disturbances, their actions have affected

succession and forest composition.

Upland forests of this region are typified by oak-hickory

(Quercus L.-Carya Nutt. spp.) overstories, with more shadetolerant species, like maples (Acer L. spp.), dominating the

understory. Advanced oak regeneration struggles to compete

with the abundant shade-tolerant species in the understory

and rarely survives long enough to grow to the overstory.

Succession of plant species is similar throughout the Central

Hardwoods: forests are first dominated by shade-intolerant,

fast-growing species, characterized in the region by oaks

and hickories, and are followed by those more tolerant of the

dense shade beneath the forest canopy. The forests eventually reach a state where the overstory is composed of

maples, beech (Fagus grandifolia Ehrh.), and other shadetolerant species. In central and northern Indiana, where

small isolated fragments of forest are dwarfed by the agricultural landscape and disturbances have been lacking,

shade-tolerant species have gained in dominance over the

past century. Spetich and Parker (1998) showed that the

mid-story composition of an old-growth forest in east-central

Indiana had changed from 14 percent oak and 12 percent

sugar maple (Acer saccharum Marsh.) in 1926 to 1 percent

oak and 43 percent sugar maple by 1992. It has been

predicted that gradual replacement of the oak-hickory overstory in this forest will lead to a canopy dominated by sugar

maple by the end of the twenty-first century (Spetich 1995).

Disturbances can be used to slow the succession toward

shade-tolerant species dominance and encourage regeneration of early successional species. One of the greatest

impacts that disturbances have on a forest is the reduction

of trees in the mid- and understory layers which consequently increases the light that reaches the forest floor.

Merritt and Pope (1991) have shown that the result of prescribed burning is to increase the intensity of light penetrating the forest canopy. They also found an increased density

of early successional species following burning.

Burning alone, however, may not be sufficient for oak regeneration, especially if the understory is already dominated by

late successional species. Research suggests that burning

will have little affect on species composition and may even

increase the number of shade-tolerant species that are

already prolific beneath the canopy (Arthur and others 1998,

Dolan 1994, Huddle and Pallardy 1996, McGee and others

1995, Merritt and Pope 1991). Furthermore, harvesting

treatments can encourage the growth of shade-tolerant

species by allowing light to reach seedlings which are

already present in the understory prior to cutting (Abrams

and Scott 1989, Jenkins and Parker 1998, Weigel and

Parker 1997). Therefore, altering only the light regime may

not be sufficient for increasing oak dominance in the

understory.

Brose and others (1999) have shown that the combination

of burning and shelterwood cuts can have a positive effect

on the composition of shade-intolerant species. While harvesting provided light for growth of shade-intolerant species

like oak, fire acted to reduce competition from more abundant species like red maple and tulip-poplar. Because of

physiological differences in the species, oak, which develops a strong root system as a seedling, is able to sprout

quickly following a fire and take advantage of the increased

light created by the harvesting and subsequent maintenance by the fire (Barnes and Van Lear 1998, Huddle and

Pallardy 1999, Kelty 1999, Kolb and others 1990).

UNDERSTORY RESPONSE TO DISTURBANCE: AN INVESTIGATION OF

PRESCRIBED BURNING AND UNDERSTORY REMOVAL TREATMENTS

Benjamin J. Dolan and George R. Parker1

1 Graduate Assistant and Professor of Forest Ecology, Purdue University, Department of Forestry and Natural Resources, West Lafayette, IN

47907-2033, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Lack of disturbance in the Central Hardwood Region has caused a decrease in abundance of shade-intolerant

species, such as oaks (Quercus spp.) and hickories (Carya spp.), while shade-tolerant species have proliferated in the

understory. The goal of this research is to determine how two disturbances, prescribed fire and mechanical understory

removal, affect woody species regeneration, as well as herbaceous species diversity. Preliminary analysis indicates that

all treatments had little effect on herbaceous species diversity; however, prescribed burning changed the composition of

woody species seedlings. While fire top-killed most seedlings, regardless of shade tolerance, shade-intolerant species

responded by resprouting. As a result of the reduction in the number of shade-tolerant species, burning treatments

produced greater equitability among tolerant and intolerant species seedlings. Removal treatments increased the level of

photosynthetically active radiation (PAR) reaching the forest floor, while a combination of burning and removal provided

both greater equitability among species and higher levels of PAR.
286

The objective of this research is to investigate whether prescribed fire and sub-canopy removal within mid-successional forests can be used to shift the species composition

of understory communities. This study examines how disturbances can be used to increase the abundance of shadeintolerant species through the control of shade-tolerant

species dominance and the simultaneous modification of

light conditions at the forest floor.

METHODS

Research Sites

Research was conducted on three Purdue University properties in west-central Indiana. Two properties, Martell Forest

(mesic slope) and Cox-Haggerty Woodland (dry slope), are

located at the break of the Tipton Till Plain and consist of

several areas with 18 to 50 percent slopes. South facing

slopes with oak-hickory overstories were chosen as study

sites on these two properties. Soils are classified in the

Strawn-Rodman complex and are well drained with moderate to low available water capacity (Ziegler and Wolf 1998).

The third property, McCormick’s Woods (mesic upland), is

located on the till plain and has level topography. The soil is

classified as Starks-Fincastle complex and is somewhat

poorly drained with high available water capacity (Ziegler

and Wolf 1998). The forest overstory at McCormick’s Woods

is also dominated by oak-hickory.

The disturbance and management history of these sites is

not well documented, but recent disturbances within these

woodlands have been minimal. The site at Martell Forest

burned accidentally in 1981, and though the intensity was

low, it completely burned the hillside of study. The understory is composed mainly of American elm and flowering

dogwood, though neither is dominant. The Cox-Haggerty

Woodland site was grazed until 1990 and, as a result, has

an understory dominated by plant species associated with

grazing, especially Amur honeysuckle (Lonicera maackii

(Rupr.) Herder). McCormick’s Woods was harvested several

times in the 1960s and 1970s using group and single-tree

selection cuts. The understory is dominated by sugar maple

and white ash (Fraxinus americana L.), which often grow

thick enough to prevent easy movement through the forest.

Plot Design

Study sites were divided into several 20 x 20 meter plots for

study and treatment. Treatment plots were established on a

grid system, oriented by cardinal directions, with a 10 meter

wide buffer left between plots to reduce treatment overlap.

Sampling was restricted to a 10 x 10 meter plot centered

within the treatment plot, leaving a 5 meter buffer surrounding the sampling plot to reduce edge effect from adjacent,

untreated areas. Twelve plots each were established at the

mesic and dry slope sites, and 20 plots were established at

the mesic upland site.

Sampling Design

Cover of herbaceous species and density of woody species

within the understory were sampled prior to treatment during

May and June 1999 and after treatment in May and June

2000 and 2001. Cover of herbaceous species was determined on a four-point scale based on percent cover: 1 =

less than 1 percent cover, 2 = 1-5 percent cover, 3 = 5-15

percent cover, and 4 = greater than 15 percent cover. Woody

and shrub sprouts resulting from stem top-kill were counted

as seedlings; each sprouting plant was counted as one

seedling. Finally each tree greater than 2 cm in diameter at

breast height (d.b.h.) within the sampling plot was identified

and measured at breast height.

Transmitted photosynthetically active radiation (PAR) was

measured prior to treatment in July 1999, and following

treatment in July 2000, for each sample plot. Measurements

were not recorded in 2001. A Sunflec Ceptometer (Decagon

devices, Inc., Washington, USA) was used to measure PAR

at five points within each plot: one at each corner and one

in the center. Measurements in full sunlight were also taken

each day plot measurements were taken. All PAR measurements were made on cloudless days between 12:00 p.m.

and 2:00 p.m. eastern standard time.

Treatments

One of four treatments was randomly assigned to each plot.

Each treatment was replicated five times at the mesic upland

site and three times at both the dry and mesic slope sites.

The treatments assigned were mechanical removal of the

subcanopy, prescribed burn, a combination of burning and

removal, and control.

Mechanical removal of the subcanopy occurred in August

1999 on plots designated for removal and combination

treatments. Woody stems greater than 1 cm in d.b.h. but

less than 15 cm in d.b.h. were cut using a chain saw and

completely removed from the treatment plot. Trees greater

than 10 cm in d.b.h. that would have been difficult to

maneuver and could not be felled easily were double

girdled and allowed to remain standing in the plot.

Prescribed burns were conducted in October and November

1999 on plots designated for burn and combination treatments. One meter wide fire break lines were constructed

around each treatment plot prior to burning using fire rakes

and a leaf blower. Depending on the weather and dryness

of the fuel, either a strip head or ring fire technique was

used to burn each plot. After ignition, the fires were allowed

to burn through the plots and extinguish themselves. Any

large debris left burning was extinguished using water

sprayed from backpack pump sprayers.

Data Analysis

Woody seedling data were analyzed to find differences in

diversity, evenness, and density between treatments at each

site. The Shannon-Wiener index was used to computer

diversity and evenness. To simplify results and interpretation,

tree species were separated into two categories, shadetolerant and shade-intolerant seedlings. Shade tolerance

was classified by each species’ ability to grow from a seedling to a sapling beneath a dense overstory. Some species

typically defined as shade-intolerant, such as black cherry

or white ash, were classified as shade-tolerant for this

study, because their abundant seedlings often grow to

sapling size and present immense competition to oaks,

hickories, and other shade-intolerant species typically

unable to grow beyond seedling size before mortality. The

effect of treatment and time on diversity, evenness and

density was analyzed with a repeated measures analysis
287

in SAS using Wilk’s Lambda to determine significance.

Square-root transformations were performed on density

data in order to decrease the amount of variability between

plots.

Herbaceous species abundance data were analyzed with

partial detrended correspondence analysis (pDCA) in

CANOCO to determine the effect of treatment on herbaceous community composition. PDCA, a variation of DCA

allowing for covariables, provided a graphical analysis of

community composition, as well as a plot depicting the

relationship between sites based on species compositions.

Using plot and time as covariables, the effects of these

factors were taken into account while the effect of treatment

remained as a potential source of variation. Sites plotted on

the graph were most similar to those plotted near it, while

those farther away were dissimilar. From this method, treatment effect was evaluated by looking for clusters of sites

which had the same treatment applied.

Photosynthetically active radiation data from each plot,

along with measurements taken in full sunlight, were used

to calculate the percent of full sunlight beneath the canopy

for each plot. Comparisons and analysis of the percent full

sunlight between plots and treatments were done using an

ANOVA in SAS.

RESULTS

Analysis of the three forest sites with burning, mechanical

removal, and combination treatments resulted in no significant difference in diversity as measured by the ShannonWiener index. Compared to the change over time at plots

which received no treatment, the overall diversity of seedlings did not increase or decrease with treatment (fig. 1).

Further, the difference between treatments at each site was

not significant. In comparison to the control plots, the graphs

show a decrease in diversity for burn treatments at the mesic

slope site by the third year (fig. 1b). This can be attributed

to an overall loss in the total number of seedlings because

of burning. The loss of species was not seen however after

the first year at this site or after the first or second years at

the dry slope (fig. 1a) or mesic upland sites (fig. 1c).

Evenness of species distribution within each plot increased

after the first year with burn treatments at each site. Both

burn treatments at the dry slope site showed a dramatic

increase in evenness over the change at the control site

(fig. 2a). The effect was continued through the second year

of treatment at which time the increase became statistically

significant (p = 0.05). The increase in evenness at the mesic

upland site was significant for the combination treatment

(p = 0.02), but not for the burn treatment (fig. 2b). At this

site, the increase in evenness after burning was apparent

after only the first year of treatment. The following year saw

a sharp decrease in evenness on all treatment plots. The

change in evenness at the mesic slope site tended to follow

that of the mesic upland; however, the results were not statistically significant (fig. 2c). All treatments showed a slight

increase in evenness over the control plots, but evenness

decreased after the second burn treatments. The removal

treatment at all sites tended to increase evenness slightly

over the control, though these changes were not significantly large.

Analysis of shade-tolerant seedling density reveals that only

plots which received the combination treatment changed

significantly (p = .10) in response to treatment. The greatest

decrease was found at the dry slope site (fig. 3a) where the

number of shade-tolerant seedlings was originally very high.

Both burn treatments largely reduced the number of shadetolerant seedlings at this site. The mesic slope (fig. 3b) and

mesic upland sites (fig. 3c) showed similar responses to the

burn treatments with a decrease in the number of shadetolerant species, though to a lesser degree than at the dry

slope site. At the mesic upland site, there was a large spike

Figure 1—Plot of Shannon-Wiener index of diversity

for each treatment over time at the dry slope site (a),

the mesic slope site (b), and the mesic upland site (c).

2.4

2.2

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Control

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Removal

Combo

H′ H′ H′
288

in the number of seedlings after the second year of treatment. This increased response in seedlings follows a large

mortality of saplings 2 to 5 cm in d.b.h. after the second

burn (table 1). These new sprouts were counted as seedlings and increased the total number of seedlings within

each plot. The response of the shade-tolerant seedlings to

the removal treatment did not differ significantly from that of

the control plots at any site.

Shade-intolerant species, including oaks and hickories,

showed much the same response to treatment as the shadetolerant species (fig. 4). The removal treatment seemed to

have the greatest influence on shade-intolerant species,

with a slight increase at the dry slope site after the first year

(fig. 4a), a slight increase at the mesic slope site after the

second year (fig. 4b) and a rapid increase at the mesic

upland site after the first year (fig. 4c). Response at all sites

to the burn treatment was a decrease in the number of

shade-intolerant seedlings.

Figure 2—Plot of evenness index for each treatment over time at

the dry slope site (a), the mesic slope site (b), and the mesic

upland site (c).

Figure 3—Plot of the average number of shadetolerant seedlings per plot for each treatment over

time at the dry slope site (a), the mesic slope site

(b), and the mesic upland site (c).

0.85

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Year 1 Year 2 Year 3

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Year 1 Year 2 Year 3

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Burn

Removal

Combo

Year 1 Year 2 Year 3

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2

Year 1 Year 2 Year 3

(a)

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Average number of seedlings Average number of seedlings Average number of seedlings
289

Table 1—Average number of saplings per plot > 5 cm

d.b.h. and < 1 m tall for each site and year

Year

Site Treatment 1 2 3

Average number per plot

Dry slope Control 5.00 5.00 5.33

Burn 3.67 0.00 0.33

Removal 0.67 0.00 0.33

Combination 10.67 0.00 0.00

Mesic slope Control 15.33 15.33 10.00

Burn 5.33 1.33 0.33

Removal 4.67 1.00 0.00

Combination 12.00 0.00 0.00

Mesic upland Control 32.40 27.00 28.60

Burn 34.40 0.60 4.00

Removal 59.80 14.20 1.40

Combination 50.80 0.00 0.00

D.b.h. = diameter at breast height.

Figure 4—Plot of the average number of shadeintolerant seedlings per plot for each treatment over

time at the dry slope site (a), the mesic slope site

(b), and the mesic upland site (c).

Detrended correspondence analysis at each of the three

sites reveals that there are no consistent changes in herbaceous communities as a result of the treatments (figs. 5a,

5b, and 5c). Site scores of the treated plots are scattered

among the control plot scores and are not clustered together.

A treatment effect on the herbaceous communities would

result in site scores being similar; however this is not the

case. Patterns based on disturbance treatment are not

clearly identifiable.

The percent of full sunlight as measured by the amount of

photosynthetically active radiation (PAR) increased with

each treatment at all sites, except the burn treatment at the

dry slope site (table 2). At this site, the abundance of Amur

honeysuckle and its ability to profusely resprout, caused a

decrease in PAR because of burning. Plots that were treated

with understory removal increased between 3 to 25 percent

full sunlight at the forest floor, while those treated with the

combination treatment had an increase of 10 to 25 percent.

Burn treatment plots had an increase of only 4 to 8 percent.

Table 2—Percent of full sunlight as measured by

PAR at the forest floor taken in mid-July before and

after each treatment

Year

Site Treatment 1 2

 - - percent PAR - -

Dry slope Control 1.37 9.50

Burn 8.92 5.40

Removal 15.22 41.93*

Combination 3.45 29.72*

Mesic slope Control 3.83 2.93

Burn 3.62 8.03*

Removal 3.23 6.68*

Combination 2.57 12.30*

Mesic upland Control 4.41 2.80

Burn 1.38 9.41*

Removal 2.37 5.63*

Combination 1.42 13.68*

PAR = photosynthetically active radiation.

An asterisk indicates a statistically significant change from

year 1 to year 2.

5.0

4.5

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3.0

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2.0

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1.0

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(b)

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(c)

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Control

Burn

Removal

Combo

Average number of seedlings Average number of seedlings Average number of seedlings
290

DISCUSSION

Consistent results across all three sites reveal important

patterns related to the disturbance treatments. The results

indicate that burning alone may not be sufficient to increase

the pool of shade-intolerant species in the forest understory, especially if the forest has already transitioned into a

dense understory of shade-tolerant species. It is important

to provide not only an environment suitable for oak establishment, but also for sustained growth. In providing

increased light through removal treatments, it may be

possible for shade-intolerant seedlings to survive until an

opportunity for growth to the overstory occurs, such as a

tree fall or some other disturbance which affects the forest

canopy.

Although the Shannon-Wiener index indicates that there is

little change in diversity because of treatment, a closer look

at evenness shows that burning can reduce competition

between species by reducing the total number of seedlings.

Further study is necessary to determine how the new and

surviving seedlings will respond to the changes in environmental conditions created by the burning and removal

treatments.

The response to the removal treatments is not yet clear

because of the short duration of this study. Research has

shown that light levels at or near 50 percent full sunlight

provide the best conditions for oak establishment, while

greater amounts of light are necessary for increased growth

rates (Crow 1988, Gardiner and Hodges 1998, Guo and

others 2001). The amount of light provided by the sub-canopy

removal treatments in this study may not be sufficient for

sustained growth; however, it may provide adequate light

conditions for a greater amount of shade-intolerant species

to establish. It will be several years before the effect of the

current removal treatments on establishment and sustained

growth of species like oak can be determined on these

research sites.

The lack of effect of burning and removal treatments on the

herbaceous species communities merits more research;

however, results of this study are encouraging for the use of

small disturbances to alter the composition of seedling

communities without affecting the herbaceous communities.

Response of the herbaceous communities was random,

proving that the treatments did not greatly affect the overall

composition. The effect of treatment on individual species is

not clear through this research, because the sampling

design was not structured for such a study. Further analysis

of continued disturbance on individual species is necessary,

but single disturbances do not affect individuals in such a

way as to change the overall community structure.

Results of this study support existing research concerning

the regeneration of oak and associated species. Low-intensity disturbances, like the combination of burning and subcanopy removal, can be used to improve conditions for oak

seedling establishment while reducing competition from

shade-tolerant species. While successive burns do not

dramatically alter the composition beyond that of a single

burn, repeated burns every few years will be necessary to

lessen competition from shade-tolerant seedlings. Through

the use of burning and sub-canopy removal, oak seedlings

can be maintained in the understory until they are provided

with adequate light conditions for growth to the overstory

that would occur with higher severity disturbances such as

harvesting or wildfire.

Figure 5—pDCA of herbaceous species showing site

values before and after treatment at the dry slope site

(a), the mesic slope site (b), and the mesic upland site

(c). Axis 1 and 2 are shown in each graph with 13 and

8 percent of variation explained for graph (a), 13 and 9

percent for graph (b), and 12 and 8 percent for graph

(c).

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Axis 1

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291

LITERATURE CITED

Abrams, M.D.; Scott, M.L. 1989. Disturbance-mediated accelerated succession in two Michigan forest types. Forest Science.

35: 42-49.

Arthur, M.A.; Paratley, R.D.; Blankenship, B.A. 1998. Single and

repeated fires affect survival and regeneration of woody and

herbaceous species in an oak-pine forest. Journal of the Torrey

Botanical Society. 125: 225-236.

Barnes, T.A.; Van Lear, D.H. 1998. Prescribed fire effects on

advanced regeneration in mixed hardwood stands. Southern

Journal of Applied Forestry. 22: 138-142.

Brose, P.; Van Lear, D.H.; Cooper, R. 1999. Using shelterwood

harvests and prescribed fire to regenerate oak stands on

productive upland sites. Forest Ecology and Management. 113:

125-141.

Crow, T.R. 1988. Reproductive mode and mechanisms for selfreplacement of northern red oak (Quercus rubra)—a review.

Forest Science. 34: 19-40.

Dolan, R.W. 1994. Effects of a prescribed burn on tree- and herblayer vegetation in a post oak (Quercus stellata) dominated

flatwoods. Proceedings of the Indiana Academy of Science.

103: 25-32.

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108: 127-134.

Guo, Y.F.; Shelton, M.G.; Lockhart, B.R. 2001. Effects of light

regimes on the growth of cherrybark oak seedlings. Forest

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periodic burning on tree survival and growth in a Missouri

Ozark oak-hickory forest. Forest Ecology and Management. 82:

1-9.

Huddle, J.A.; Pallardy, S.G. 1999. Effect of fire on survival and

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woody vegetation in silvicultural openings of southern Indiana

forests. Forest Ecology and Management. 109: 57-74.

Kelty, M.J. 1988. Sources of hardwood regeneration and factors

that influence these sources. West Virginia University Office of

Publications, Morgantown, WV. p 17-30.

Kolb, T.E.; Steiner, K.C.; McCormick, L.H.; Boersox, T.W. 1990.

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McGee, G.G.; Leopold, D.J.; Nyland, R.D. 1995. Understory

response to springtime prescribed fire in two New York

transition oak forests. Forest Ecology and Management. 76:

149-168.

Merritt, C.; Pope, P.E. 1991. The effect of environmental factors,

including wildfire and prescribed burning, on the regeneration

of oaks in Indiana. West Lafayette, IN: Purdue University,

Agricultural Experiment Station. 52 p.

Spetich, M.A. 1995. Characteristics and spatial pattern of oldgrowth forests in the Midwest. West Lafayette, IN: Purdue

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Spetich, M.A.; Parker, G.R. 1998. Distribution of biomass in an

Indiana old-growth forest from 1926 to 1992. American Midland

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Weigel, D.R.; Parker, G.R. 1997. Tree regeneration response to

the group selection method in southern Indiana. Northern

Journal of Applied Forestry. 14: 90-94.

Ziegler, T.R.; Wolf, D.R. 1998. Soil survey of Tippecanoe County,

Indiana. USDA Natural Resources Conservation Service. 342 p.

Appendix—List of species included in shade-tolerant

and shade-intolerant species analyses

Common name Scientific name

Shade-tolerant species

American basswood Tilia americana L.

American beech Fagus grandifolia Ehrh.

American elm Ulmus americana L.

Black cherry Prunus serotina Ehrh.

Flowering dogwood Cornus florida L.

Hackberry Celtis occidentalis L.

Sugar maple Acer saccharum Marsh.

White ash Fraxinus americana L.

Shade-intolerant species

Black oak Quercus velutina Lam.

Black walnut Juglans nigra L.

Bur oak Q. macrocarpa Michx.

Chinquapin oak Q. muehlenbergii Engelm.

Hickory species Carya spp. Nutt.

Northern red oak Q. rubra L.

Sassafras Sassafras albidum (Nutt.) Nees

Tulip-poplar Liriodendron tulipifera L.

White oak Q. alba L.
292

INTRODUCTION

Alteration of disturbance regimes in the central and eastern

United States has developed understory conditions that

have led to the dominance of shade-tolerant species in the

understory of many oak (Quercus spp.) stands (Lorimer

1984, Abrams 1992, Abrams and Nowacki 1992). With the

change in the understory environment following this shift in

forest structure, the establishment and development of oak

reproduction has diminished (Abrams 1992, Lorimer and

others 1994, Brose and others 1999). Other factors such as

vertebrate predation, sporadic acorn production, weevil

(Curculio spp) infestations, and microsite variability may

also play a role in limiting the establishment of oak reproduction (Gribko and others 2002). The lack of periodic

disturbance compounded with inherent biotic and abiotic

factors influencing oak establishment has made the regeneration of many oak stands difficult.

Acorn survival and germination is a necessary precursor for

the establishment of oak reproduction. However, few acorns

ever germinate into seedlings due to factors such as losses

from predation and exposure of acorns to unfavorable

environmental conditions (Crow 1988, Ostfeld and others

1996). It has been suggested that soil scarification, in the

presence of abundant acorns, may be useful to disrupt competing vegetation and enhancing the initial development of

oak reproduction (Lhotka and Zaczek 2003a, 2003b; Zaczek

2002). Specifically, scarification promotes favorable germination conditions for acorns, provides protection from predation, and plays a role in controlling competing vegetation

(Crow 1988). The results of four soil scarification studies and

a discussion of the implications of these studies in using

scarification to enhance the density and development of

oak reproduction is outlined in this paper.

PAST AND ONGOING STUDIES

Two recent studies conducted in southern Illinois suggest

that, in the presence of abundant acorns, soil scarification

can help increase the initial density of oak seedlings (Lhotka

and Zaczek 2003a, 2003b). One study was conducted in an

upland forest dominated by white oak (Quercus alba L.) and

black oak (Quercus velutina Lam.). The stand contained a

dense midstory of well-established sugar maple (Acer saccharum Marsh.) saplings and suppressed trees and little

advance oak reproduction. In October 1999, a 78-hp crawler

tractor with a 2.44-m-wide six-tooth brush rake was used to

scarify the soil. One year after treatment, scarified areas

had greater oak seedling densities (5,164 ha-1, 20 percent

of total seedlings) when compared to undisturbed areas

(1,273 ha-1, 9 percent of total seedlings). Scarification also

reduced midstory density by removing 31 percent of the

sugar maple stems within the scarified areas (Lhotka and

Zaczek 2003a).

A second study conducted in southern Illinois during the

same period was established in a bottomland forest composed primarily of cherrybark oak (Quercus pagoda Raf.)

and post oak (Quercus stellata Wangenh.) (Lhotka and

Zaczek 2003b). The understory had sparse tree regeneration

and was dominated by poison ivy (Toxicodendron radicans

L.). A 42-hp wheeled tractor pulling a 2.44-m wide field disk

was used to conduct the soil scarification. One year after

scarification, scarified plots had greater oak seedling densities (7,243 ha-1, 42 percent of total seedlings) than did control plots (453 ha-1, 9 percent of total). At the same time,

poison ivy cover in the scarified plots (7 percent) was reduced

compared to controls (35 percent). First year results, from

the upland and bottomland studies conducted in Illinois,

suggest that soil scarification has the potential to increase

initial establishment of oak and may have the ability to

control competing vegetation.

An early soil scarification study conducted within a northern

red oak (Quercus rubra L.) stand using disk scarification

also showed increased establishment of oak following soil

scarification (Scholz 1959). However, seven years after

treatment the initial advantages of disk scarification were

THE INFLUENCE OF SOIL SCARIFICATION ON OAK REPRODUCTION:

REVIEW AND MANAGEMENT CONSIDERATIONS

John M. Lhotka, James J. Zaczek, and Russell T. Graham1

1 Forester, USDA Forest Service, Rocky Mountain Research Station, Moscow Forestry Sciences Laboratory, Moscow, ID 83843; Assistant

Professor, Department of Forestry, Southern Illinois University, Carbondale, IL 62901; and Research Forester, USDA Forest Service, Rocky

Mountain Research Station, Moscow Forestry Sciences Laboratory, Moscow, ID 83843, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—Changes in historic disturbance regimes and the resulting changes in forest composition and structure have

contributed to oak (Quercus spp.) regeneration difficulties across much of its geographic range. One important component

of oak regeneration is the establishment and development of advance oak reproduction. Another is reducing competing

vegetation to enhance the development of oak reproduction. Past and ongoing research in the use of soil scarification to

enhance establishment and competitive position of oak reproduction from seed is summarized in this paper. Within each

study presented, initial establishment of oak reproduction was significantly greater in scarified areas compared to the

controls. From these studies, a series of management recommendations have been developed and will be presented to

provide researchers and land managers with information on applicability of soil scarification treatments to enhance initial

establishment oak reproduction.
293

no longer present. From the study, it was apparent that the

stand conditions were not conducive to oak seedling development, for the average seedling height was only 19 cm

after seven years. This trend suggests that without the

appropriate growing conditions for oak in place at the time

of treatment such as adequate light levels, protection from

deer browse, or control of competing vegetation the early

advantages gained by scarification may diminish over time.

A fourth study reviewed in this paper was conducted within

a poorly regenerating upland mixed-oak fenced shelterwood

in central Pennsylvania. The stand’s understory was dominated by red maple seedlings and had relatively few small

oaks. A soil scarification treatment was applied in 1993

within the shelterwood using a small crawler tractor and

1.8-m-wide brush rake. Soil scarification conducted within

shelterwood and in the presence of abundant viable acorns

increases the initial density and competitive position of oak

and that the advantage is apparent through year five (Zaczek

and others 1997, Zaczek 2002, Zaczek and Lhotka, in press).

One year after scarification, 32,618 oak seedlings ha-1 (78

percent of total seedlings) were found in the scarified plots,

while only 9,435 oak seedlings ha-1 were located in the control. The overwood and fence were removed at year three.

Five years after treatment, a greater density of oaks (39,432

ha-1) still remained in scarified plots when compared to controls (12,971 ha-1). Additionally, within the disturbed areas,

greater oak densities were present in the larger size classes

compared to other species including red maple. The competing red maple reproduction was significantly reduced in

density and height in response to scarification. Unlike the

Scholz (1959) study, the Pennsylvania upland study was

conducted in a stand with an understory environment more

conducive to the development of oak seedlings. This contrast in understory environments between the two studies

may explain the differences in understory dynamics seen

over time.

MANAGEMENT IMPLICATIONS

While soil scarification can increase the initial establishment

of desired oak species, operational and biological influences

may control the success of an operation. First, abundant

viable acorns must be present at the time of treatment, for

without the necessary seed, a soil scarification operation

will only serve to disrupt the existing vegetation and fail to

develop new oak germinants. Timing of scarification operation is also crucial. It is recommended that areas be scarified in the autumn of an abundant mast year following acorn

drop, but before leaf fall. This is important because it is

suggested that the litter accumulation after leaf fall may

provide additional protection against acorn predation (Bundy

and others 1991).

Extremely wet or dry conditions at the time of treatment may

also influence the success of the operation. Extremely dry

conditions may cause acorns to desiccate and fail to germinate (Olson and Boyce 1971) and the depth of penetration

by a disk in dry soils is limited. On the other hand, scarification may compact or displace soils and may bury acorns too

deeply, resulting in decreased seedling emergence.

A wide array of power sources and implements have been

used for scarification in forest operations. Selection of an

appropriate system must balance traction, soil scarification,

and maneuverability. An important factor influencing a

scarification operation is the presence of a dense midstory

and understory. Density is important because it may hamper

machinery maneuverability. The small-wheeled tractor with

disk, small crawler tractor with brushrake or Salmon blade,

and a modified drag-chain scarifier pulled by a small crawler

tractor are three methods that may be used for scarification

in partial harvests (Karsky 1993, Zaczek and others 1997,

Lhotka and Zaczek 2003b). These systems have the size

and maneuverability to operate in a partially harvested stand

without damaging residual trees, but still have sufficient

power to complete the operation (Karsky 1993). The disking

and drag-chain method may be preferred in open stands,

but the mobility of the equipment may be severely limited in

dense stands or those containing large amounts of slash.

Therefore, it may be necessary to thin and/or remove slash

prior to implementing the disk or drag-chain method. In

contrast, the bulldozer/brushrake method has the ability to

operate in dense and recently harvested stands, while still

providing scarification benefits (Zacaek and others 1997,

Zaczek 2002). Damage to residual crop trees is possible so

careful operation of equipment is necessary. For these

reasons, it is important to consider stand conditions prior to

planning a scarification operation.

Precision application of disturbance is another benefit that

scarification can provide. In contrast, other oak regeneration enhancement treatments such as prescribed fire may

be difficult or impractical to apply in small or irregularshaped patches and exclusion from sensitive areas may be

problematic. With the ability to pinpoint treated areas, a

manager could scarify poorly regenerating areas, while

avoiding streamside buffer zones, temporal ponds, or other

unique habitats.

Soil scarification may increase initial establishment, but this

silvicultural treatment alone may not create appropriate

conditions for the development of large, vigorous seedlings.

Without the necessary environmental conditions in place,

continued growth and survival of scarification produced

seedlings may be limited. Many factors can influence further

development of understory reproduction. A well-developed

midstory and associated low light levels will greatly hinder

the development of oak seedlings (Lorimer and others 1994).

The intolerant to midtolerant oak species are especially

harmed and cannot survive over a long period in these low

light levels (Crow 1988, Nowacki and Abrams 1992). Competing vegetation, deer browse, insects, disease, and other

environmental variables may also add to seedling mortality

(Crow 1988, Lorimer 1993, Oak 1993). It has been suggested

that a manipulation of the midstory or overstory may help

alleviate some of the problems created by low light levels

(Loftis 1983, Janzen and Hodges 1985, Loftis 1990, Lockhart

and others 2000). Without release, seedling survival will be

limited. This resulting mortality may leave the stand in a

condition similar to that present prior to the scarification

treatment.

Given the presence of abundant viable acorns, scarification

has been shown to increase oak seedling density. It is also

suggested that scarification may control competing midstory and understory vegetation (Lhotka and Zaczek 2003a,
294

Zaczek and Lhotka, in press). However, scarification may

also promote sprout development and therefore the response

of competing vegetation should be evaluated prior to scarification. Finally, we stress that silvicultural procedures such

as an overstory thinning should be applied prior to or in

concurrence with scarification to help enhance the survival,

growth, and development of newly established oak

seedlings.

ACKNOWLEDGMENTS

The authors thank John Groninger and Andrew Hudak for

their manuscript review and editorial comments.

LITERATURE CITED

Abrams, M.D. 1992. Fire and the development of oak forests.

BioScience. 42(5): 346-353.

Abrams, M.D.; Nowacki, G.J. 1992. Historical variation in fire, oak

recruitment, and post-logging accelerated succession in central

Pennsylvania. Bulletin of the Torrey Botanical Club. 199(1):

19-28.

Brose, P.H.; Van Lear, D.H.; Keyser, P.D. 1999. A shelterwood-burn

technique for regenerating productive upland oak sites in the

Piedmont region. South. J. Appl. For. 23(3): 158-163.

Bundy, P.P.; Alm, A.A.; Baughman, M.J. 1991. Red oak regeneration following “scarification” and harvesting: a case study.

North. J. Appl. For. 8: 173-174.

Crow, T.R. 1988. Reproductive mode and mechanisms for selfreplacement of northern red oak (Quercus rubra)—a review.

For. Sci. 34(1): 19-40.

Gribko, L.S.; Schuler, T.M.; Ford, W.M. 2002. Biotic and abiotic

mechanisms in the establishment of northern red oak seedlings: a review. Gen. Tech. Rep. NE-295. Newtown Square, PA:

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

Research Station. 18 p.

Janzen, G.C.; Hodges, J.D. 1985. Influence of midstory and understory vegetation removal on the establishment and development

of oak regeneration. In: Sholders, E., ed. Proceedings third

biennial southern silvicultural research conference. Gen. Tech.

Rep. SO-54. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southern Research Station: 273-278.

Karsky, D. 1993. Scarifiers for shelterwoods. USDA For. Serv. Tree

Planters Notes. 44(1): 13-15.

Lhotka, J.M.; Zaczek, J.J. 2003a. Effects of scarification disturbance on the seedling and midstory layer in a successional

mixed-oak forest. Northern Journal of Applied Forestry. 20(2):

85-91.

Lhotka, J.M.; Zaczek, J.J. 2003b. Soil scarification effects on initial

establishment of oak reproduction within two mixed-oak

bottomland stands in southern Illinois. Southern Journal of

Applied Forestry. 27(3): 164-171.

Lockhart, B.R.; Hodges, J.D.; Gardiner, E.S. 2000. Response of

advanced cherrybark oak reproduction to midstory removal and

shoot clipping. South. J. Appl. For. 24(1): 45-50.

Loftis, D.L. 1983. Regenerating Southern Appalachian mixed hardwood stands with the shelterwood method. South. J. Appl. For.

7: 212-217.

Loftis, D.L. 1990. A shelterwood method for regenerating red oak

in the Southern Appalachians. For. Sci. 36(4): 917-929.

Lorimer, C.G. 1984. Development of red maple understory in

northeastern oak forests. For. Sci. 30: 3-22.

Lorimer, C.G. 1993. Causes of the oak regeneration problem. In:

Lofis, D.L; McGee, C.E., eds. Oak regeneration: serious

problems and practical recommendations. Gen. Tech. Rep. SE84. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southern Research Station: 14-39.

Lorimer, C.G.; Chapman, J.W.; Lambert, W.D. 1994. Tall understorey vegetation as a factor in the poor development of oak

seedlings beneath mature stands. J. Ecol. 84: 227-237.

Nowacki, G.J.; Abrams, M.D. 1992. Community, edaphic, and

historical analysis of mixed oak forests of the Ridge and Valley

Province in central Pennsylvania. Can. J. For. Res. 22: 790-

800.

Oak, S.W. 1993. Insects and disease affecting oak regeneration

success. In: Lofis, D.L; McGee, C.E., eds. Oak regeneration:

serious problems and practical recommendations. Gen. Tech.

Rep. SE-84. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southern Research Station: 105-111.

Olson, D.F., Jr.; Boyce, S.G. 1971. Factors affecting acorn production and germination and early growth of seedlings and seedling

sprouts. In: Oak Symposium Proceedings; August 16-20, 1971;

West Virginia University; Morgantown, WV. Radnor, PA: USDA

Forest Service, Northeastern Forest Experiment Station: 44-48.

Ostfeld, R.S.; Jones, C.G.; Wolff, J.O. 1996. Of mice and mast.

Ecological connections in the eastern deciduous forests.

BioScience 46(5): 323-330.

Scholz, H.F. 1959. Further observations on seedbed scarification

show benefits to northern red oak were temporary. USDA For.

Serv. Tech. Notes. Lake States For. Experiment Station No.

555. 2 p.

 Zaczek, J.J. 2002. Composition, diversity, and height of tree

regeneration three years after soil scarification in a mixed-oak

shelterwood. For. Ecol. Manage. 163: 205-215.

Zaczek, J.J.; Harding, J.; Welfley, J. 1997. Impact of soil scarification on the composition of regeneration and species diversity in

an oak shelterwood. In: Palardy, S.G.; Cecich, R.A.; Garrett,

H.E.; Johnson, P.S., eds. Proceedings, 11th central hardwood

forest conference; Gen. Tech. Rep. NC-188. USDA Forest

Service, North Central Forest Experiment Station: 341-348.

Zaczek, J.J.; Lhotka, J.M. [In press]. Seedling reproduction in a

scarified oak shelterwood after overstory removal. Northern

Journal of Applied Forestry.
295

Soil acidity, nutrient deficient soils, lack of light penetration,

herbivory, and understory competition are the major obstacles encountered in regenerating and sustaining northern

red oak. Changes in soils that may occur during soil acidification include: reduced soil pH, increased availability of

aluminum (Al) and manganese (Mn), loss of base cations

due to leaching; and competition between base cations and

Al for exchange sites in the fine roots (Robarge and Johnson

1992).

Cronan and Grigal (1995) proposed that a calcium/aluminum (Ca/Al) ratio of 1.0 or less in soil solution posed at

least a 50 percent risk of adverse impacts on tree growth

and a ratio of 0.2 (or less) a 100 percent risk. Soil acidity

increases Al concentrations in the soil and has been implicated in oak regeneration failure in Pennsylvania (Lyon and

Sharpe 1995). Northern red oak (Quercus rubra L.) is sensitive to Al toxicity (Cronan and Grigal 1995, Demchik and

Sharpe 1999). Standard red oak regeneration practice in

Pennsylvania requires a shelterwood cut to provide seeds

for the new forest and allow enough light penetration to

promote seedling growth. In addition, herbicides, such as

sulfometuron methyl (Oust®), are used to reduce competition. Applications of lime and fertilizer have the potential to

ameliorate soil acidity; therefore, their use could be very

beneficial in the establishment of new seedlings The objectives of this study were to determine the effects of shelterwood harvest with herbicide application on soil and soil

solution chemistry; to test the efficacy of liming and fertilization as an acidity remediation treatment; and to determine the effects of these treatments on red oak tree growth.

Three sites with extremely acidic soils, forest floors dominated by hay-scented fern (Dennstaedtia punctilobula), and

predominately northern red oak (Quercus rubra L.) overstories were selected for study in southwestern Pennsylvania.

Soil solution samples were taken bi-weekly using tension

lysimeters for three growing seasons, from plots receiving

herbicide (Oust®, sulfometuron-methyl, 2.0 ounces per

acre) (H); lime and fertilizer (LF) (Dolomitic lime - 1.5 tons

per acre and 10-20-20 Nitrogen-Phosphorus-Potassium

(NPK) fertilizer - 0.5 tons per acre); and a combination of

the herbicide, and lime, and fertilizer (HLF) treatments. Two

plots served as controls (C). All plots were previously shelterwood harvested (within the year) to leave a residual basal

area of 4.9 m2 – 11.1 m2. Northern red oak tree diameters

at breast height (d.b.h.) were measured and basal area

increment (BAI) was calculated.

Median soil solution data indicated calcium (Ca), magnesium (Mg), potassium (K), and pH increased with the addition of lime and fertilizer. Soil solution from plots receiving

lime and fertilizer had increased Ca/Al and base cation/

aluminum (BC/Al) ratios above critical levels. The addition

of herbicide alone caused increased soil solution Al and H+

concentrations and reduced Ca/Al ratios to critically low

levels. Within the HLF treatment plot, the addition of lime

and fertilizer counteracted the acidifying effects of herbicide

treatment, while still providing hay-scented fern control.

Northern red oak measurements indicated that under normal

moisture conditions trees in the HLF plot had significantly

increased radial growth over all other treatments. Both the

LF and H treatments had significantly increased radial

growth over the control treatment. The improved soil solution chemistry conditions on all plots receiving lime and

fertilizer seemed to increase red oak radial growth.

Soil solution results indicated that even with the relatively

modest lime and fertilizer application rates used, important

soil chemistry improvements were produced. Sulfometuronmethyl herbicide application by itself lowered Ca/Al and BC/

Al ratios well below critical levels implicated in Al toxicity to

red oak, decreased soil solution pH, and increased plant

available Al. Liming and fertilization with hay-scented fern

control ameliorated soil acidification effects associated with

sulfometuron-methyl application and resulted in Ca/Al and

BC/Al ratios above critical levels and significantly improved

plant available Ca and Mg concentrations. Based on the

unfavorable soil chemical changes observed and their

amelioration by lime and fertilizer application, sulfometuronmethyl herbicides should not be used to promote northern

red oak regeneration on extremely acidic soils without

accompanying lime and fertilizer treatment.

LITERATURE CITED

Cronan, C.S.; Grigal, D.F. 1995. Use of calcium/aluminum ratios

as indicators of stress in forest ecosystems. Journal of

Environmental Quality. 24: 209-226.

Demchik, M.C.; Sharpe, W.E. 1999. The effect of calcium/aluminum ratio on root elongation of twenty-six Pennsylvania plants.

p. 211 – 217. In The Effects of Acidic Deposition on

Pennsylvania’s Forests. Sharpe, W.E. and Drohan, J.R. (eds.).

Proceedings of the 1998 PA Acidic Deposition Conference, Vol.

1, ERRI, The Pennsylvania State University, University Park,

PA. Chapter 18.

THE EFFECTS OF LIME, FERTILIZER, AND HERBICIDE ON

FOREST SOIL SOLUTION CHEMISTRY AND NORTHERN RED OAK

RADIAL GROWTH FOLLOWING SHELTERWOOD HARVEST

Angela M. Happel and William E. Sharpe1

1 Research Assistant and Professor of Forest Hydrology, Environmental Resources Research Institute and School of Forest Resources, The

Pennsylvania State University, University Park, PA 16802 respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.
296

Lyon, J. 1995. The impacts of soils, herbaceous competition, and

soil liming on the growth and nutrition of northern red oak

(Quercus rubra L.) seedlings. University Park, Pennsylvania,

U.S.A.:The Pennsylvania State University. [Not paged]. Ph.D.

dissertation.

Robarge, W.P.; Johnson, D.W. 1992. The effects of acidic

deposition on forested soils. Advances in Agronomy. 47: 1-83.
297

INTRODUCTION

Bole-wood chemistry can be a useful indicator of the nutrient

status of trees. Liming generally increases Ca and/or Mg

and decreases Mn concentrations in bole-wood. Acidifying

treatments, such as ammonium sulfate or nitrogen fertilizers

without lime, generally cause Mn increases and concomitant

decreases in Ca and Mg. Bole-wood concentration ratios of

Ca/Mn have been found to be good indicators of soil alkalinization or acidification trends (DeWalle and others 1999).

Whether the timing of past chemical changes in soil is

accurately preserved in tree rings remains uncertain. In this

study we had an opportunity to study bole-wood chemistry

in Quercus spp. two decades after an acidifying N-only (AR

site) and NPK+liming (MO site) treatment.

METHODS

Multiple wood cores were removed at breast height from

ten trees on control and treated plots at each site in 1995.

At the Arkansas site, 336 kg N/ha had been added as

ammonium nitrate fertilizer to Q. rubra trees in 1977-78.

At the Missouri site, NPK+lime (1345 kg N/ha as urea)

had been added to Q. velutina trees in 1973. Destructive

chemical analysis (ICP) was performed on composite wood

samples for tree core segments formed before and after

treatment. Significant growth responses to fertilization were

previously reported at each site (AR-Graney and Murphy

1993, MO-Harris and others 1980).

RESULTS

Arkansas

At the AR site, fertilization only caused a significant reduction in Ca concentrations in bole-wood formed in the 5-yr

segment after treatment. No other significant changes in Ca

and Mn concentrations and Ca/Mn ratios were detected.

Regardless, Ca/Mn ratios in red oak appeared to be reduced

by treatment in bole-wood formed 5-yr after and up to 20

years prior to treatment (fig. 1).

Missouri

At the MO site, significant decreases in Mn concentrations

and increases in Ca/Mn ratios (fig. 2) occurred in nearly all

segments of bole-wood of black oak due to treatment. Ca/

Mn ratios were increased in bole-wood formed up to 20 years

prior to and up to 20 years after fertilization. Ca concentrations were not significantly affected, but appeared to be

increased by treatment.

OAK BOLE-WOOD CHEMISTRY RESPONSE TO

FERTILIZATION AT TWO OZARK SITES

David R. DeWalle, William E. Sharpe, and Bryan R. Swistock1

1 Professors of Forest Hydrology and Extension Associate, School of Forest Resources and Penn State Institutes of the Environment,

Penn State University, University Park, PA 16801, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Figure 1—Molar Ca/Mn concentration ratios in bole-wood of red

oak in 1995 at an AR site that had been fertilized with ammonium

nitrate in 1977-78.

80

60

40

20

Control

Treated

0

1947-51

1952-56

1957-61

1962-66

1967-71

1972-76

1977-81

1982-85

1986-90

1991-95

Fertilization

Arkansas - ca/mn

Bolewood Ca/Mn ratio

Figure 2—Molar Ca/Mn concentration ratios in bole-wood of black

oak in 1995 at a MO site that had been fertilized with NPK+lime in

1973.

80

60

40

20

0

1953-62 1963-72 1973-74 1975-84 1985-95

Fertilization

Control

Treated

Missouri - ca/mn

Bolewood Ca/Mn ratio
298

CONCLUSIONS

Nitrogen fertilization without liming in AR caused slight,

short-lived soil acidification that could be detected in bolewood of red oak trees 20 years after treatment. In contrast,

urea N-fertilization with lime in MO had a long-lasting effect

on bole-wood chemistry of black oak. Bole-wood chemistry

changes were evident in a wide band of wood formed prior

to treatment, limiting the usefulness of dendrochemistry to

precisely chronicle soil changes.

LITERATURE CITED

DeWalle, D.R.; Tepp, J.S.; Swistock, B.R. [and others]. 1999. Treering cation response to experimental watershed acidification in

West Virginia and Maine. J. Environ. Qual. 28(1): 299-309.

DeWalle, D.R.; Tepp, J.S.; Swistock, B.R. [and others]. [In press].

Dendrochemical response to soil fertilization. In: Spetich, M.A.,

ed. Upland oak ecology symposium: history, current conditions,

and sustainability. Gen. Tech. Rep. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southern Research

Station.

Graney, D.L.; Murphy, P.A. 1993. Growth response of upland oak

stands in the Boston Mountains to nitrogen fertilization. Proc.

7th Biennial Southern Silvicultural Conf., pp. 485-495, USDA,

Gen. Tech. Rep. SO-93.

Harris, A.R.; Urie, D.H.; McQuilkin, R.A.; Sander. I.L. 1980. Water

quality implications of forest fertilization in the Missouri Ozarks.

Proc., Central Hardwood Forest Conf. III, U. Mo., Columbia,

Sept. 16-17, 1980, pp. 21-37.
299

SUMMARY

Acorn insects can have a severe impact on mass production and regeneration. Gibson (1972) reported losses of 10 to

100 percent of acorn crops in stands of white oak, whereas

Gibson (1982) reported losses of up to 96 percent in stands

of northern red oak. Acorn insects can be divided into two

groups: primary and secondary insects. The primary insects

include the Curculio weevils, filbertworms, and gall wasps,

and damage acorns directly to introduce larvae. The secondary insects include acorn moths, midges, and Conotrachelus

weevils, and take advantage of existing holes or damage.

The most damaging of all these insects are the Curculio

weevils, with 23 species recorded on oak in North America,

often accounting for most, if not all, damage caused by

acorn insects. Myers (1978) found that weevils accounted

for half of the 62 percent loss of acorns in stands of white,

black, northern red, and scarlet oaks in Missouri between

1973 and 1976; wildlife only took 11 percent. Three or four

species of Curculio weevils can be present at the same time

in a forested stand or seed orchard. Currently, there are no

registered control products or tactics for acorn insects,

although various pesticides are registered and used for

related Curculio weevils in pecan and chestnut orchards.

Adult weevils generally emerge from the forest floor in

August and September, climb trees, mate, and lay eggs

inside acorns. Larvae feed freely within acorns, often with

numerous larvae inside the same acorn, until the acorns fall

and larvae leave the acorns to burrow into the ground to

depths approaching 12 inches. Larvae remain underground

for about 2 years, pupate, and re-emerge as adults.

Our objective was to examine the level of acorn losses

in a northern red oak seedling orchard in northeastern

Tennessee, looking for relationships of damage with the

size of acorn crops and time of acorn fall. In summer of

2000, 42 northern red oaks bearing acornets were selected

at the Watauga Seedling Orchard in northeastern Tennessee.

During the fall of 2000, all acorns falling from each tree

were collected at 2-week intervals and floated to determine

damage levels. Damaged acorns float while healthy acorns

sink. Prior to floating, a subsample of 100 acorns was taken

and dissected for comparison with the floating method. The

level of damage to acorns at the Watauga Seedling Orchard

in 2000 was 42 percent (SE = 2 percent), with 67 percent of

the damage caused by weevils. Floating overestimated

damage by 36 percent. Acorns that fell in early fall were

more likely to be damaged by weevils (39 percent) than

acorns that fell in late fall (10 percent). The levels of damage

by weevils were higher in trees with small acorn crops than

in those with large acorn crops (r2 = 0.418; P < 0.01).

LITERATURE CITED

Gibson, L.P. 1972. Insects that damage white oak acorns. Res.

Pap. NE-220. U.S. Department of Agriculture, Forest Service.

Gibson, L.P. 1982. Insects that damage northern red oak acorns.

Res. Pap. NE-492. U.S. Department of Agriculture, Forest

Service.

Myers, S.A. 1978. Insect impact on acorn production in Missouri

upland forests. University of Missouri. Ph.D. dissertation.

SPATIAL AND TEMPORAL DISTRIBUTION OF WEEVILED ACORNS

WITHIN A NORTHERN RED OAK SEEDLING ORCHARD

D.R. Miller and S.E. Schlarbaum1

1 Research Entomologist, USDA Forest Service, Southern Research Station, Athens, GA 30602-2044; and Professor, Department of Forestry,

Wildlife and Fisheries, University of Tennessee, Knoxville, TN 37901-1071, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.
300
301

Closing Remarks
302
303

INTRODUCTION – MARTIN L. BLANEY

In the process of putting this symposium together with a

diverse group of conservation partners, a momentum of

purpose and resolve developed that seems to be unprecedented in our region. Upon witnessing our upland oak

forests and woodlands slowly degrade in health and vigor

through the last decades of our collective careers and then

to watch their accelerated decline in the last three years

has brought us to the same question. Can we continue in

our own spheres of responsibilities and allow such a shift in

forest communities to occur without our concerted efforts

to find and affect solutions? With defiant conviction, the

response was a collective “not on our watch.” A strategy

formed around the oak sustainability issue that had its

beginnings in the Forestry Subcommittee of the Arkansas

Wildlife Federation with the formation of a coalition of

partners. At the same time, acting as a catalyst, an issue of

the Arkansas Wildlife magazine focusing on oak decline

was printed and widely circulated. The many and widely

favorable responses received from the widespread distribution of this publication, further heightened the resolve of the

coalition to the possibility of changing public opinion regarding the need for human intervention into the oak communities. With the onset of the red oak borer outbreak, questions

from the public regarding hardwood forest management

began to accelerate and the obvious gaps and conflicts in

our professional understandings was apparent. These

events lead to the eventual need of assembling the various

resource professions to gain a cohesive awareness and

understanding of oak ecology to both provide answers to

the public and affect management solutions through better

techniques. It was clear that we, as resource professionals,

were quite divided in our understandings of how these

systems worked and what were and were not appropriate

recommendations when lending technical assistance to the

inquiring public. Once assembled at the conference and

with the quality of presentations and subject matter, it was

easy to see that we also needed to capture more of the

expertise attending this event.

We chose to conclude the symposium with a panel discussion focusing our attention upon what needs to happen for

oak sustainability to occur. For the purposes of addressing

this we divided the issues surrounding oak ecosystem

restoration into four broad categories affecting oak restoration and provide a presentation on each by a qualified

panelist. These categories are (1) an understanding of the

history, ecology and restoration requirements, (2) what

research needs and challenges await us, (3) the important

public attitudes that will influence us and the policies that

present hurdles, and (4) the importance of trying and finding appropriate management tools and affecting solutions

on landscape scales. The session then concluded by polling the audience with two questions regarding barriers they

perceive stand in the way of restoring our upland oak communities. The responses are summarized at the end of the

paper. Following are the panel presentations as witnessed

by the conference participants.

WHERE DO WE GO FROM HERE?

Martin L. Blaney, Scott Simon, James M. Guldin,

Tom Riley, Donny Harris, and Rebecca McPeake1

1 Habitat Coordinator, Wildlife Management Division, Arkansas Game and Fish Commission, Russellville, AR 72802; Director of Conservation

Programs, Arkansas Chapter of The Nature Conservancy, Little Rock, AR 72205; Project Leader, USDA Forest Service, Southern Research

Station, Hot Springs, AR 71902; Extension Specialist, Environmental Policy and Section Leader, Environmental and Natural Resources,

University of Arkansas Cooperative Extension Service, Little Rock, AR 72203; Chief, Wildlife Management Division, Arkansas Game and Fish

Commission, Little Rock, AR 72205; and Associate Professor and Extension Specialist - Wildlife, University of Arkansas Cooperative

Extension Service, Little Rock, AR, respectively.

Citation for proceedings: Spetich, Martin A., ed. 2004. Upland oak ecology symposium: history, current conditions, and sustainability.

Gen. Tech. Rep. SRS–73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 311 p.

Abstract—The structure and diversity of the upland oak ecosystem has changed significantly, primarily caused by fire

suppression and historic forestry practices, leaving the ecosystem vulnerable to outbreaks of pathogens and insects.

These conditions, coupled with periods of drought, have caused significant oak mortality throughout the Interior Highland

region shifting the communities to different forest types. There is great concern among conservationists that a shift in

forest type will cause declines in wildlife populations and rare species dependent upon these ecosystems. Upon witnessing this continued degradation of upland oak forests and woodlands, a momentum of purpose and resolve became

established among a diverse group of conservation partners that lead to the idea of gathering various resource disciplines

to this “state of our understanding” conference. Once assembled and with the quality of papers presented, it was easy to

see that it would be beneficial to capture more of the expertise attending the event. Many of the research findings

presented by the scientists can now be used by those in positions of management authority to make better decisions

about the resources entrusted to their professional care. In keeping with the overall strategy of the symposium, the

conference committee attempted to take advantage of the expertise gathered at the conference by polling the audience

for ideas of “where we go from here.” In concluding the symposium, the last session’s focus was to provide closing

comments by a panel of experts in each of four broad categories that encompass the various issues surrounding oak

sustainability; restoration, research, policy and management. Audience responses to posed questions were then collected

and tabulated. It was agreed by many present that information exists to restore the ecosystem, but political and economic

barriers must be overcome for landscape level restoration to occur.
304

RESTORATION – SCOTT SIMON

Historically, the interior highlands landscape consisted of a

mosaic of prairies, savannas, woodlands, and forests.

Based on Government Land Office survey (GLO) records

interpreted by Tom Foti, only 33 percent of the Ozarks was

described as closed forest (much of this in the steep slopes

of Arkansas’ Boston Mountains and Current River Hills in

southeast Missouri), with the remaining 67 percent of the

landscape described as open forest, savanna, and prairie.

Densities calculated from the GLO records indicate average

densities per subsection ranging from 38 trees per acre in

the Central Plateau subsection to 76 trees per acre in the

Upper Boston Mountains subsection per acre. Average density in the Upper and Lower Boston Mountain subsections

combined is 54 trees per acre. Underneath these forest,

woodland, and savanna communities was a diverse herbaceous understory that supported wildlife of elk, bear, bison,

turkey, deer and over 150 species of plants and animals

found no where else in the world.

The Ozarks was a landscape extensively maintained by fires

and adapted to disturbance. Ignition sources from Native

Americans and lightning strikes created fire frequencies

that Richard Gyette and others estimated ranged from 1 to

6 years in prairie communities, 2 to 7 years in open woodlands and 5 to 50 years in the closed forest communities on

steep slopes. These regular understory fires maintained a

relatively open tree structure and a diverse herbaceous

layer. What we’ve learned is that to this ecosystem, fire is

as essential as rainfall.

Eventually with some of the changes in European settlement and extensive cutting that followed, the fires stopped

and the forests, woodlands, savannas, prairie, and forests

grew up (densified) before our generations’ eyes. The new

Ozark landscape was now much denser. Nearly all of the

forested areas could be classified as closed forest. Historically there were 52 trees per acre in the Boston Mountains

there are now 148 trees per acre based on Jim Guldin’s

data from the Ozark Ouachita Highlands Assessment.

A threefold increase over what the historic landscape

contained. An even greater increase has occurred in the

sapling and shrub layer with 300 to 1,000 stems per acre

currently—a staggering increase.

As David Van Lear, Michael Steele, James Fralish, and

others described, this densification has had some effects.

Very little light reaches the forest floor in the summer in the

Ozarks. Because of the shade, oak regeneration is negligible, herbaceous layer diversity abundance is low (typically 20 to 40 plant species per acre compared to 150 to

200 species per acre in open, restored stands) and a new

forest of shade intolerant woody species with maples, ashes

and ostrya is the dominant understory. We really don’t know

what the future overstory would be. Moving us from an

overstory of oaks to some other forest type, Tom Foti asked

me to mention, isn’t going to be a moist or a mesophytic

forest that typically occurred on the moist lower north-facing

slopes. It’s going to be a subset of that historical forest

type, it’s going to be junk.

Because there are so many trees per acre that are competing

for the same amount of nutrients and water, the ecosystem

is under stress. Just like when humans are stressed, we’re

vulnerable to any individual pathogen and we get sick. Our

oak ecosystem is susceptible to an epidemic of native

insects like the red oak borer that as Rose-Marie Muzika

described, had never been reported at epidemic levels in

the history she was able to derive from tree ring data.

Although there are many contributing factors to oak decline,

it seems the root cause is too many trees per acre. There is

nothing in the post-glacial record that suggests that the Ozark

ecosystems have been previously impacted by changes of

this magnitude or rapidity. These changes and their impacts

to soils, water and other habitat conditions, may be occurring at a rate that is too fast for many of the species to adapt.

Animal species are dependent on the plants. If plant communities change, we can assume that there are going to be

changes in the animal population and wildlife populations.

Of particular concern to us at The Nature Conservancy are

those species adapted to the Ozark and Ouachita ecosystems found nowhere else in the World.

Over the millennia, this system has been maintained and

stewarded by humans for about 12,000 years. In recent

years with all good intentions, we have probably failed it

and ultimately ourselves, our children, and grandchildren.

We have the information to restore the structure, diversity,

and sustainability of the oak ecosystem through the use

of prescribed fire and silvicultural treatments utilized on

numerous successful, small restoration projects conducted

by many agencies and organizations. We need to utilize

what we learned from these pilot projects and expand to

selected larger areas on the landscape. It is up to our generation to restore the sustainability of the system. We don’t

want to restore the system to keep it in a box, with some

preconceived idea of what it should look like. We need to

restore its historical structure and diversity so that as the

climate changes and the world changes, this system can

change and adapt in a resilient way with the full complement of species for future generations to benefit from and

enjoy. Future generations will have as many options in

addressing their future as we have.

RESEARCH – JAMES M. GULDIN

Before reviewing the scientific high points that emerged

from presentations during this symposium, a few comments

are in order regarding the role of the scientist in matters of

forest policy.

First, scientists are not decision makers. The work of the

scientist is to develop the conceptual and quantitative

understanding of natural resource issues—essentially, to

add tools to the toolbox of the decision-maker. The many

research findings presented by the scientists who spoke at

this symposium can now be used by those in positions of

management authority to make better decisions about the

resources entrusted to their professional care.

Second, definitive research on natural resource issues

does not and will never exist. This enhances, rather than

diminishes, the responsibilities of the scientist and the decision maker. For example, some would argue that decisions

should be deferred if the science about the issue is incomplete. But the ultimate costs of deferring decisions may

frequently be greater than the costs of executing them,
305

especially in the long term. A case in point has been repeatedly discussed during this symposium—the decline in the

health of Interior Highlands forest stands attributable to

stand age in a forest landscape that has been under-managed for decades, especially on Federal lands.

Scientists will continue to study questions of forest health,

sustainability, productivity, and diversity in the Interior

Highlands from our comfortable ivory towers. Some of the

products produced by this process may be informative,

some will be useful, and a few will enable major scientific

and conceptual understandings of the ecology and management of oak ecosystems. This process is maddeningly inefficient and seems conspiratorially independent of details

such as decision deadlines and timely public discourse. As

a result, the decisions that are made by those responsible

for making them will continue to fall short of definitive scientific support. But a decision made without definitive science

is not necessarily bad. There are a host of legal, political,

economic, biological, and social considerations that bear

upon a decision, many of which might be contrary to

accepted scientific findings—and which nevertheless might

result in an excellent decision in the public policy context or

for a private landowner.

With respect to the scientific findings presented at this symposium, suffice it to say that the decision maker’s toolbox

has become heavier. A number of points deserve recapitulation for both the scientists and the decision-makers in

attendance. These points were jotted down as speakers

made their presentations, and in some instances the

speaker’s name appears in parenthesis after the salient

point. The reader might refer to the appropriate paper in

this proceedings for further detail.

The importance of fire in oak ecosystems is becoming

increasingly appreciated, and speakers at this symposium

suggested that its use could be expanded considerably. It

was suggested that fire could be of great benefit in maintaining species and habitats (Ladd). Research opportunities

to refine the influence of fire include the effects of fire on

soil dynamics, the importance of growing season burns,

and the manner by which fire influences landscape pattern

(Foti, Heitzman, Benac). In addition, the role of fire in wood

quality and utilization requires additional research

(Patterson). Finally, the influence of fire, or lack thereof,

was discussed in reference to stand recovery after exploitation; this was especially prominent in southeastern Missouri,

where the acreage of land on which shortleaf pine was

dominant has declined from 6 million acres at the turn of

the century to less than 600,000 today (Benac). Certainly

one part of the question regarding the fire-mediated restoration of the upland oak ecosystem is the degree to which

shortleaf pine should be favored, either in mixture with hardwoods or as a dominant forest type on appropriate sites.

Conversely, several speakers observed that the limitations

to broader application of fire in the oak ecosystem are real.

Those constraints to burning more frequently over larger

areas include the increasing human population in the region,

both in absolute terms and in distribution through the wildland-urban interface, and the associated increased fragmentation of forests (Guyette, Fralish). These considerations

suggest that less fire, not more, is likely in the future. This

also speaks to the continued importance of research on fire

surrogate treatments that emulate the ecological effects of

fire in oak ecosystems.

A third topic of considerable interest to the research

community at this symposium is wildlife, specifically deer.

Several speakers pointed to the fact that numbers were

fewer 200 years ago than today (Van Lear, Dickson), and

there are implications regarding the adequacy of oak

regeneration related to this point (Miller, Brose, Healy). It’s

too bad deer don’t leave tree scars as fires do, so we can

quantify their effects. But just because we can’t quantify the

effect doesn’t mean the increase hasn’t been ecologically

significant. Among the reasons for the higher deer numbers

may be loss of predators (Healy). An interesting question

raised by these ideas is whether the detrimental influence

of high deer populations exceeds that resulting from the

lack of fire as a primary factor limiting oak sustainability.

That would be easy to test—exclude deer from one area,

increase cyclical burning in another, do both in a third, and

see what happens.

There have been many advances in oak silviculture over

the past several decades, and more are needed. Speakers

identified a number of areas where advances might be in

order, including study of stand dynamics in oaks under

decline (Kabrick), oak seedling silvics, and regeneration

potential under various fire prescriptions (Brose). The

potential for the application of uneven-aged silviculture in

oak stand, especially on the better sites, remains to be

established (Loftis); group selection probably works better

than single-tree selection, but more data are needed.

However, the potential inherent in the single-tree selection

method was convincingly shown by the 50-year, 150,000-

acre case study at Pioneer Forest (Trammel).

A number of speakers mentioned the fact that the knowledge base for better management of oaks exists, but that

knowledge may not be getting into the hands of users.

Better approaches to technology transfer are being sought.

Scientists will need to translate results from research studies

into practical application for a wider variety of research

data. Several good examples of this were presented, such

as the ingenious planting guidelines for oaks based on

survival probabilities (Spetich) and the development of oak

regeneration models (Loftis, Schweitzer).

Finally, several speakers pointed to key challenges for oak

management, especially regarding undesirable consequences in the absence of change. Speakers questioned

whether management for oak sawtimber is consistent with

oak ecosystem sustainability. Two emerging themes that

captured this pessimism were that the next century will be

a tough time to be an oak tree (Shifley), and that extraordinary efforts to modify the structure of Interior Highlands

oak forests to resist gypsy moth appear to be justified

(Gottschalk).

In summary, the research perspective points to many interesting directions and avenues of continued research. But

one cannot help but be concerned that continuing the

present course of affectionate, laissez-faire, hands-off
306

development of the upland oak forests of the Interior

Highlands may essentially be little more than loving them to

death.

POLICY – TOM RILEY

My challenge was to talk about the policy issues that we

have to deal with related to management of the oak forest.

First of all, I want to ask a question of the audience – maybe

you can just give me a show of hands – how many of you

have as your primary responsibility water quality protection? How many of you have air quality protection as one of

your primary responsibilities? I think that is a challenge for

all of us because I think everybody should raise your hands

in both questions (three people in an audience of 200 raised

their hands). We have a natural resource management

responsibility and forestry is a part of that. We all have a

responsibility to resource, to the implications of what we do

relative to that resource and there are a lot of people out

there who are looking at what we do, not from the standpoint of “what are you doing to my forest?” but “what are

the actions that you are taking on that forest doing to my

water quality, what’s it doing to the quality of my air?” If

you’re living in Memphis, you are in an air of quality attainment zone, so anything that you do within that airshed is

going to be influenced by what the city of Memphis says it

wants to do. Those are the regulations, those are the rules

that are going to apply. If you are in Little Rock or if you are

in the vicinity of Little Rock, that same circumstance is going

to apply. The numbers are getting so large now in terms

of air quality that Fort Smith and Fayetteville may also be

included. Think about it, in Arkansas, a million people, over

40 percent of the population of this state, resides in about

five counties in northwest Arkansas. When you think about

the future of that in terms of the population dynamics

between the people and the resource, what we do out there

on that resource is very much influenced by what it is those

people think, what they understand. The question would be

“how can you have an educated policy if you don’t have an

educated public?” If you don’t have a public that understands exactly what you are doing, if you don’t have a

public that trusts you, trusts you and believes that what you

are doing is actually right for the resource that’s going to be

a benefit to them. We’ve got a lot of opportunity, we have a

lot of tools that are available to us. We’ve got one of the

best conservation provisions in the Farm Bill that we’ve had

in my memory, and I’ve done a lot of historical work associated with the history of farm conservation legislation. We

can treat this in a lot of different ways: we can regulate,

we’ve got all kinds of tools, we can do an incentive-based

program, we can change our tax structure, we can also be

influenced by the courts. If you’ve paid any attention to the

way we have come to do some of the things we’ve done in

the state of Arkansas, you’ve got a pretty sound logic if you

think about a lot of the things that we do being influenced

or directed by the courts. I’ll guarantee if we don’t do this

right, if we don’t do it with an educated public, that’s where

we will be. We’ll be directed by one federal judge from some

court somewhere. So we have to pay close attention to that

as one of the policy options that’s out there. We can use

markets, economies, we can pay attention to landowners,

and we have heard something about private landowners, a

lot about moving private landowners to do things. What

motivates the private landowners? What is the policy issue

that they’re going to be most concerned about? Most of

them, it’s a bottom line thing, it’s a dollars and cents thing,

or it’s a social thing. It’s something having to do with what I

want to do on my property or what I believe my property

rights to be. We talk a lot about the concepts of watershed

management, of ecosystem management, and we use a lot

of our scientific terms in that process and it scares individual

private forest landowners and they become so distrusting

that they won’t listen to the logic. So we have to understand

and deal with the language issue, the way we approach,

and the way we communicate with individual landowners.

We have this mix of resources that are available to us if you

think about the Farm Bill and all the opportunities that are

there: EQIP, the Environmental Quality Incentives Program,

CRP, Wetlands Reserve, all of these include in them forest

management opportunity, new forest potential within those

different programs. We’ve got the FLEP (Forest Land

Enhancement Program) that’s specifically for private landowners. But where is the NRCS relationship that guarantees that fire is one of the management alternatives that’s

provided to the individual private forest landowner? If it’s

not in their tech guide, if it’s not in their set of tools that they

have available to them, working with that private landowner

on an individual daily basis, it’s not coming to ground, it’s

not going to be used. If those individual resource people

who are out there working day to day with landowners don’t

know how to use fire, don’t trust that concept in management, it’s never going to be used in a private setting the

way it ought to be used. Those are circumstances that we

have an opportunity to overcome, but we can’t overcome

them in this audience – we have to broaden it. We have to

broaden the audience, we have to broaden the understanding, that’s how policy change gets made. It won’t get made

in this room. It gets made in taking this knowledge, this

understanding, to another step and another step. There is a

poet I think a lot of (Shel Silverstein) who says a lot of things

– he wrote a poem that’s very short and it kind of fits here:

You, all of us, have a magic carpet that will whiz you

through the air

To Spain, to Maine, to Africa, you just tell it where

So will you let it take you where you have never been

before?

Or will you just buy drapes to match and use it on your

floor?

MANAGEMENT – DONNY HARRIS

I’m not sure I even understand that... but I’m sure it’s all

good. A few months ago, Martin Blaney approached me and

asked me if I would be willing to serve on this panel and I

said, “Man I’d be honored.” I said, “Who’s on the panel and

what’s my role gonna be?” and Martin said, “Well we’ve got

Scott Simon, we got Jim Guldin and we got Tom Riley. Those

people are extremely intelligent and very articulate. However, since you possess neither of those qualities, I’d like

for you to serve on the panel to represent some balance.” I

said, “if you’re tellin’ me you need somebody to dumb it

down, I’m your man.” After all, as Bob McAnally so eloquently

put it, “I was sixteen years old before I found out my name

wasn’t “get wood.” And uh, for my Game and Fish brethren

in the audience if I get to talkin’ too fast, raise your hand

and I’ll slow it down just a little bit.
307

As we started this symposium, Paul Johnson enlightened

us about oak forests and, how they’re actually created by

disturbance influences, and that we can actually perceive

management activities as planned disturbances. Tom Foti

went on to give us a historical perspective of how these oak

forests, evolved and what the influence of fire was and what

the influence of fire suppression was. Additionally Jim

Dickson, Joe Clark and others spoke to, wildlife populations

and how they’ve evolved in these habitat types and their

dependence on the benefits derived from those habitat types.

I said that to say this, I believe that we have the science.

It’s pretty obvious if you’ve set in the sessions and read the

abstracts you have to come to that point that you believe

we have adequate science, while it’s not what we would

desire, I believe it to be adequate. But science alone is not

enough. Paul Sears in his book entitled Deserts on the

March, which he actually wrote in 1947 said this and I

quote, “Science has the power to illuminate, but not solve

the deeper problems of mankind. For always after knowledge comes choice and action, both of which are intensely

personal and individual.” In keeping with that, in my closing

remarks I’d like to extend this challenge. I believe we are at

a fork in the road and must make a choice. We can leave

here from this symposium and hope that through some

factor of osmosis, a miraculous healing will take place in

our ailing ecosystems. If that is our choice, future generations will sit in judgment and we’ll be indicted and actually

found guilty of negligence and outright malfeasance. Unfortunately those future generations will have to suffer the

consequences of the choices that we make. On the other

hand, if we link arms fortified with good science and bring

the collective expertise, energy and resolve to bear on the

issue at hand the outcome will not be the same. Those same

future generations will sit in judgment, but I believe the conclusion will be much different. They may say in October 2002,

in Fayetteville an assemblage of resource professionals

decided that the upland oak ecosystems, we have come to

love and appreciate, are worth everything we can do to save

and perpetuate them, therefore we conclude that these

professionals were responsible stewards of the resources

that were placed in their care. And in summary I believe the

acorn is truly in our court.

SUMMARY OF AUDIENCE COMMENTS –

REBECCA MCPEAKE

After panelists responded to questions from the audience,

the audience was asked their perceptions about sustaining

the upland oak ecosystem. Notecards were distributed and

audience members responded to two questions: (1) what

are the barriers to sustaining upland oak ecosystems, and

(2) what strategies or actions or solutions are needed to

restore upland oak ecosystems?

Barriers

Barriers identified by many respondents were (1) a lack

of recognition and support by the general public about

managing oak ecosystems, particularly the importance of

fire and tree harvest, (2) a lack of funding and resources to

adequately implement prescribed fire treatments, given the

large number of acres, limited timeframe within which

controlled burns are optimally implemented, and smoke

management regulations, and (3) an economic climate

which favors landowners making short-term profits over

long-term gains.

Respondents indicated a number of conflicting agendas

between forestry professionals and public opinion, particularly those of landowners, radical environmentalists,

politicians, urbanites, and the media. Examples of their

comments are as follows:

The Forest Service is perceived as timber beasts, not an

interdisciplinary group of conservation professionals.

The... national forests should dedicate a large amount of

resources to changing public opinion or they will fight us

every step of the way.

The power of the decision makers is largely in the hands

of non-informed or non-scientists – landowners - judges.

We are allowing environmental advocacy groups to educate our educators. I am continually stricken with Muirist

philosophy from third graders.

Public opinion – not landowners’ opinion necessarily –

that prevents the use of good management and fire.

Diversity of owners and in turn diversity of needs/

objectives.

Radical environmentalism... we need to collectively

utilize the media to get a clear message to the public

about the need to actively manage forest resources.

Media, the corporate media (all owned by very few corporations) is reactionary and very focused on blame –

natural resource professionals tend to get a bad rap.

Other respondents noted that not only conflicts exist

between different stakeholder groups, but that forestry

professionals themselves debate the various practices for

oak sustainability:

Poor research or lack of research or conflicting research

has led to opposition among scientists.

Like panelist said, NRCS has programs which do not

include fire programs for private landowners. Agencies

such as NRCS were not included/represented in this

symposium.

Knowledge: I think our information on past history is still

a little thin in certain areas. Too much dependence on old

records.

Gap in total understanding of the upland oak landscape

with regards to all its components and users, e.g., plants,

animals, etc.

Many conference participants indicated a lack of public

support for various fire management strategies. Some

respondents linked this lack of support with policies, rules,

and regulations counter to management strategies that

enhance oak sustainability.

[A barrier is a] Smokey Bear fear of fire by Baby Boomers.

Public aversion to fire, smoke management programs,

public aversion to fire surrogates (e.g., chemicals). [Another
308

barrier is] environmentalists’ aversion to active management of forests. Doing nothing is not the solution.

Public perception about negative effects of fire.

Another category of responses dealt with a lack of funding

and resources to adequately implement prescribed fire

treatments, given the large number of acres, limited timeframe within which controlled burns are optimally implemented, and smoke management regulations. Examples of

these comments were:

Not enough resources, $, or manpower to address acres

at risk even without considering policy or social barriers.

Not all resource management agencies have adequate

manpower, equipment and dollar resources to be as

effective as they could be.

Lastly, many noted that landowners are responding to an

economic climate which favors making short-term profits

over long-term gains, which are not conducive to sustainable oak ecosystems.

The majority of the land is in private ownership. Currently,

all private landowners consider is selling timber. As a private consultant, timber sales are basically the only services

I can sell because it puts dollars in the owner’s pockets.

Human nature focusing on personal gain over decisions

which could improve the big picture.

Management of forests that focus strictly on lumber/timber

production and the political and social procedures that push

only for production.

Strategies/Actions/Solutions

The second question asked audience members what strategies/actions/solutions they recommended for restoring upland

oak ecosystems. Responses can be broadly categorized as

(1) public education directed towards youth and private

landowners, (2) political influence to facilitate the use of fire

management, redesign the decision process for public forest

management, leverage monetary support for landowner

incentive programs, (3) a need for leadership and partnerships to direct and/or influence policy, education, and

research, (4) improved technology transfer, and (5) increased

awareness of the impact of deer and invasive plant species

on the oak ecosystem.

Responses pertaining to public education identified increased

educational efforts focusing on school-aged children. Justifications included presenting a counter-balance to some of

the messages that are in opposition to management practices promoting oak sustainability. Examples of these comments were:

Fund early educational programs to re-educate our

young people. At best, they presently hear one radical

point of view in the media, at school, and from parents

who truly think they understand.

Get a mascot for the oak ecosystem like Smokey Bear is

for fire. Maybe an oak tree that talks!

Programs for school kids that will let kids see that cutting

trees is not bad and may even be needed.

Several audience members recommended that the next

step after this symposium was to focus on NIPF (non-industrial private forest) landowner education as a large-scale

effort. One proposed that the message should be to “convince landowners that we can deal with these problems

through proper management.” Other specific recommendations were:

Disseminate information by special article: stateside

papers, agency/NGO (Inc), publications.

Involve private landowners in information gathering and

implementation plans. Have similar symposia to this one

(small scale, not so intense) for interested landowners (at

reduced cost, of course) to educate them in their importance of achieving overall goal(s).

We want to educate the public. Would it have been a step

in the right direction to have given a free pass to this symposium to the network press, local legislators, local mayors,

local chamber of commerce, executives, etc., representative of governor’s office? Every AR Legislator and the

Governor and others listed above need to have a copy of

the final report.

Respondents indicated that they expected the outcomes

from educational efforts would result in support for oak

ecosystem management. Specifically, two audience

members stated:

We know what to do in many cases but what we often do

not have is public support (which mandates to political

support). We need to reach the public and inform them

on principles of forest ecology and what our options are.

Build on renewed “pride” of our homeland. Engage the

community of the public/private/landowners to take

actions. The Ozarks aren’t a tree museum - it’s a dynamic

community that requires action on a landscape scale.

Some linked educational efforts to improved political influence. Targeted policies were those that facilitate the use of

fire management, redesign the decision-making process for

public forest management, and leverage monetary support

for landowner incentive programs. One respondent stated,

This isn’t a problem of science, it is a political problem. It

can only be won in the political arena.

Respondents indicated that for policy changes to occur,

partnerships are needed that directly address specific regulatory, legal, technical, and financial hurdles. Several recognized the need for legislation that facilitated implementation

of prescribed fire, for example legislation that would reduce

liability and risk. Examples of comments were:

ID agencies and groups that can provide technical and

financial assistance to private landowners to use recommended practices. Get $ for landowner education programs. Quantity economic value of environmental assets

(plant and animal, soil, water, air, etc). Must have a credible link (organization) between the scientific community,

conservation community, state and federal agencies and
309

private landowners. Must develop mechanism that facilitates payment for environmental assets to private

landowners.

There is a national initiative to restore ecosystems to a

healthy level. There will be competition to direct the

funding associated with the initiative to the protection of

communities at risk while this is important, it will take

funding away from those programs designed to restore

the landscape on a broad scale. We must correctly

identify to our political leaders the importance of landscape management.

Many comments indicated a need for leadership to form

partnerships and make progress in addressing oak ecosystem management. A couple of these statements were:

Some of the brain trust needs to come up with a wellconceived long-term (no flash in the pan) political and

educational initiatives to take this body of issues to the

public, to congress to NGO’s to other agencies more

marginal, etc. As Donnie Harris says, “future generations

depend on us and will judge us.”

It seems to me that there needs to be a board (committee?)

of informed, landscape-scale decision makers that is

comprised of representatives from each of the public land

agencies. This needs to be a group of small number that

can actually begin to (1) prioritize manageable areas

(2) develop integrated restoration/maintenance methods.

This group will interface with private landholders in those

target areas; also interface with politicians and media to

affect decision - making and public education/outreach

(television!).

Use current tools available and move forward in area

where we can make immediate changes. For those areas

where barriers are too great, work to make changes in

policies, [and] partnerships, partnerships, partnerships.

I think we can under current policies get a good start on

restoring oak ecosystems. Policy changes would certainly

help us be more efficient in making changes. If past

related matter is a barrier, if there is a policy change

would we have the resources available to take advantage

of those changes?

Develop the Oak alliance association to develop strategic

plan to sustain Oak Ecosystems. This alliance would

provide leadership - be the catalyst - form partnerships,

statewide, regionally, nationally - move us forward NOW

without delay. It would be representative of the natural

resources agencies, landowners, conservation groups,

industry etc. that own, manage and are stewards.

Many recognized the importance of “technology transfer” as

a solution to restoring upland oak ecosystems. Some audience members focused specifically on prescribed fire for

restoring and improving forest health in upland oak ecosystems. Other audience members emphasized the need to

conduct research and educate private landowners about

“ALL available tools, thin, fire, herbicide, etc.” Specific

recommendations were establishing demonstration and

interpretive areas that applied a variety of management

treatments.

Begin establishing testing sites to showcase various burn,

burn trials to show landowners what it looks like, how to do

it, and focus on fire surrogates which will be more popular.

Design a landowner kiosk that pinpoints the problems

existing in the non-oak understory and tells how to identify

when an establishment problem may be serious.

Designate a land (e.g., a watershed 10,000+ acres) and

designate a management team to implement the best ideas

(the current best science-based adaptive management) to

create a healthy landscape (diverse, sustainable) and a

productive one (in terms of timber, wildlife, and other commodities) Demonstrate what can be (free from administrative barriers). Natural Forest Planning is a good way to get

public ideas but management on Natural Forests is too

constrained by the appeals process. Do such a demonstration on state lands or on a private - public partnership. Get

the best minds in the state together and implement, demonstrate, and educate.

Establish what regeneration techniques work within particular areas and prepare to implement them. This will require

some specific, short-term research coordination... Enlist the

public in our efforts. Show them the value of these methods

on private and industry property.

One audience member challenged participants individually

to put into practice the information presented at the symposium. The audience member stated,

Become an advocate for sustainability. Take some of that

retirement money and buy forestland yourself. Invest in

what you are trying to do.

A few indicated the need for continued research about fire

surrogates, restoration of tree composition, and restoration

of forest structure in the sustainability of an oak ecosystem.

Even though specific information about management practices may be incomplete, audience members recommended

that demonstrations and public education efforts should

continue. As one respondent explained,

Research [will] focus on the problem which will be a

function of $ available, hence must get political support,

forest industries, NGO’s etc public awareness.

Another commented,

Assuming that control of species composition in oak

stands is an action that is needed to achieve desired

conditions, we should begin to allocate/identify lands

where fire can be used and where a fire surrogate like

cutting or herbicides would be more appropriate. This is

the first step in a strategy, and it can be started now by all

agencies, organizations, and landowners while other

details are being worked out by researchers and land

managers. The public should be made aware that the

resource professionals here are in agreement with this

strategy.

Lastly, a couple respondents noted other influences should

not be ignored when addressing strategies for restoring
310

upland oak ecosystems, particularly the control of expanding deer herds and invasive plant species.

In summary, it was agreed by many present that information

exists to restore the ecosystem, but political and economic

barriers must be overcome for landscape-level restoration

to occur. Audience members were fairly consistent in their

recognition of needs for education, policy, and research in

addressing barriers and developing strategies for restoring

upland oak ecosystems. This included developing a largescale public education effort coupled with targeted landowner

education efforts through demonstrations and workshops.

Audience members recommended forming multi-stakeholder partnerships to affect policy that is more amenable

to forest management practices and landowner incentive

programs, and the need for leadership to develop strategies for addressing education, policy, and research.
311

INDEX OF AUTHORS

Page

B

Benac, David 36

Berg, Erik C. 143

Blaney, Martin L. 303

Bragg, Don C. 57

Brose, Patrick 123, 263

C

Carlson, John E. 72

Clark, Joseph D. 116

Clark, S.L. 160

Colbert, Jimmie J. 259

Contreras, Thomas 72

Crook, Damon 223

D

Demchik, Michael C. 154

DeWalle, David R. 297

Dey, Daniel C. 128, 132, 168,

206

Dickson, James G. 106

Dolan, Benjamin J. 285

F

Fierke, Melissa 223

Flader, Susan 36

Foti, Thomas L. 21

Fralish, James. S. 78

G

Gottschalk, Kurt W. 182, 259

Grabner, Jennifer K. 94

Graham, Russell T. 292

Graney, David L. 206

Groninger, John W. 177

Guldin, James M. 259, 264, 303

Guyette, Richard P. 102, 128, 132,

138

H

Haggerty, Thomas M. 243

Hallgren, S.W. 160

Happel, Angela M. 295

Harris, Donny 303

Hartman, George 168

Heitzman, Eric 53

Hilliard, Jerry E. 30

Hocut, Tamara R. 243

Hutchinson, Todd F. 190

I

Iverson, Louis R. 190

Page

J

James, Douglas A. 120, 253

Janzen, Greg C. 269

Jensen, Randy G. 94

Johnson, Paul S. 13, 206

Jurney, David H. 42

K

Kabrick, John 138

Kabrick, John M. 94

Kinney, Dana 223

Kochenderfer, James N. 182

L

Larsen, David R. 94

Law, Jay R. 257

Lhotka, John M. 292

Lockhart, Jami Joe 30

Loewenstein, Edward F. 264

Loftis, David L. 88, 163, 269

Long, Robert 275

M

Mangini, Alexander 217

McEuen, Amy 72

McNab, W. Henry 88

McPeake, Rebecca 303

Melick, Ross 257

Mielke, Manfred 217

Miller, D.R. 299

Miller, Gary W. 182

Mlodinow, Michael 243

Muzika, Rose-Marie 102, 138

N

Nebeker, T. Evan 150

O

Oak, Steven W. 236

Oliveria, Forrest 217

P

Parker, George R. 285

Patterson, C. Joan 120

Patterson, David W. 212

Prasad, Anantha M. 190

R

Rebbeck, Joanne 190, 275

Riley, Tom 303

Rosson, James F., Jr. 229

Ruffner, Charles M. 177

Page

S

Sabo, George III 30

Salisbury, Vaughn 223

Schiefer, Terence L. 150

Schlarbaum, S.E. 299

Schweitzer, Callie J. 88

Schweitzer, Callie Jo 269

Self, Janet S. 243

Sharpe, William E. 154, 295, 297

Sheffield, Raymond M. 88

Shifley, Stephen R. 94, 198

Simon, Scott 303

Smallwood, Peter 72

Smith, Kimberly G. 243

Soucy, Rick 53

Spetich, Martin A. 3, 53, 206

Stahle, David W. 42

Stambaugh, Michael C. 132, 138

Starkey, Dale A. 217, 236

Steele, Michael A. 72

Steinman, James R. 236, 257

Stephen, Fred 223

Studyvin, Charly 257

Swistock, Bryan R. 297

T

Terzaghi, William B. 72

Tucker, Steven A. 150

V

Van Lear, D.H. 65

Van Lear, David 123

W

Wang, Yong 269

Warriner, Michael D. 150

Y

Yaussy, Daniel 275

Yaussy, Daniel A. 190

Yockey, Edwin K. 236

Z

Zaczek, James J. 292
312
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 herbicides selectively and carefully. Follow recommended practices for the disposal of

surplus pesticides and their containers.

Papers published in these proceedings were submitted by authors in electronic media. Some editing was done to ensure a

consistent format. Authors are responsible for content and accuracy of their individual papers and the quality of illustrative

materials.

April 2004

Southern Research Station

P.O. Box 2680

Asheville, NC 28802

Cover photo: Boston Mountain Range in northwest Arkansas.
Spetich, M.A., ed. 2004. Upland oak ecology symposium: history, current

conditions, and sustainability. Gen. Tech. Rep. SRS-73. Asheville, NC:

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

Station. 311 p.

Fifty-one papers address the ecology, history, current conditions, and

sustainability of upland oak forests—with emphasis on the Interior

Highlands. Subject categories were selected to provide focused coverage

of the state-of-the-art research and understanding of upland oak ecology

of the region.