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The use of trade or firm names in this publication is for reader information and does not

imply endorsement of any product or service by the U.S. Department of Agriculture or

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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

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CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants,

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pesticides and their containers.
i

Slash Pine:

Still Growing and Growing!

Proceedings of the Slash Pine Symposium

Jekyll Island, Georgia

April 23–25, 2002

Edited by

 E.D. Dickens, J.P. Barnett, W.G. Hubbard, and E.J. Jokela

Hosted by

Florida and Georgia Divisions of the Southeastern Society of American Foresters

The University of Georgia, Warnell School of Forest Resources

University of Florida, School of Forest Resources and Conservation

U.S. Department of Agriculture Forest Service, Southern Regional Extension Forestry

Sponsored by

Florida and Georgia Divisions of the Southeastern Society of American Foresters

The University of Georgia, Warnell School of Forest Resources

University of Florida, School of Forest Resources and Conservation

The Florida Division of Forestry

The Georgia Forestry Commission

The Georgia Center of Continuing Education

U.S. Department of Agriculture Forest Service, Southern Regional Extension Forestry

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

Published by

U.S. Department of Agriculture Forest Service

Southern Research Station

Asheville, North Carolina 28804

December 2004
ii

This general technical report on slash pine is printed 20 years after an earlier proceedings, “The Managed

Slash Pine Ecosystem” was published. It was evident in 1983 that loblolly pine was becoming the species

of choice where either species could be planted, especially in areas where fiber-volume production was a

high priority. Since 1997–98, forest industry activities, pine pulpwood stumpage prices, timberland

ownership patterns, and the economics of growing southern pines have dramatically changed in the

Southeastern United States. Many scientists and land managers are rethinking species/site selection, cash

outlays, and forest management intensities. The authors of this proceedings decided to share their new

knowledge of slash pine.

Slash pine continues to be an important species of southern yellow pine on the southeastern Coastal Plain.

While its native range is more limited than any other southern yellow pine, its value as raw material for

wood products ranks third behind loblolly and shortleaf pine. Although slash pine may not produce as much

wood volume or fiber on many of the sites where both loblolly and slash pine are found, it can produce

more high-value, high-grade lumber than loblolly pine. Some of the papers in this proceedings either

compare or include loblolly pine as a research subject, because these two species often are the only

choice of pine species in the southeastern Coastal Plain.

The authors’ intent is to give land managers an up-to-date guidebook on slash pine management. Although

we have learned much in the last 20 years, there is still much we have to learn. The 1983 managed slash

pine ecosystem proceedings has some very valuable information that remains current to this day. The

reader should use his/her best judgment where conflicting opinions are presented; pine study findings may

contradict one another due to several abiotic, biotic, management, and other factors.

The efforts of many people made the slash pine symposium possible. The following is a list of those who

contributed to planning; conference program organization; making local arrangements; lining up sponsors

and exhibits committees; and inviting symposium speakers, moderators, and reviewers.

Planning Committee: Jill Barbour, John Bridges, Chris Carey, Steve Chapman, David Dickens, Mark Frye,

George Hernandez, John Holzaepfel, Bill Hubbard, Eric Jokela, Susan King, Charlie Marcus, Mike Mengak,

Jarek Nowak, and Larry Thompson

Conference Chair: Bill Hubbard

Program Co-Chairs: David Dickens and Eric Jokela

Sponsors and Exhibits Committee: John Bridges, Steve Chapman, and David Dickens

Local Arrangements Committee: Chris Carey, Mark Frye, and Susan King

Preface
iii

Contents

Page

Slash Pine: Characteristics, History, Status,

and Trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

James P. Barnett and Raymond M. Sheffield

Slash Pine Tree Improvement . . . . . . . . . . . . . . . . . . 7

Tim L. White and Tom D. Byram

Slash Pine Establishment: What Has Changed—

1981–2002? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Marshall Jacobson

Competition Control in Slash Pine

(Pinus Elliottii Engelm.) Plantations . . . . . . . . . . . . . 23

J.L. Yeiser and A.W. Ezell

Nutrient Management of Southern Pines . . . . . . . . . 27

Eric J. Jokela

Planting Density Impacts on Slash Pine Stand

Growth, Yield, Product Class Distribution, and

Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

E. David Dickens and Rodney E. Will

Loblolly Versus Slash Pine Growth and Yield

Comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Barry D. Shiver

Species Deployment Strategies for the Southern

Pines: Site Specific Management Practices for the

Flatwoods of Georgia and Florida . . . . . . . . . . . . . . . 50

Thomas R. Fox

An Economic Comparison of Slash and Loblolly

Pine under Various Levels of Management in the

Lower Atlantic and Gulf Coastal Plain . . . . . . . . . . . 56

Coleman W. Dangerfield, Jr., E. David Dickens,

and David J. Moorhead

Page

Wood Quality of Slash Pine and its Effect on

Lumber, Paper, and Other Products . . . . . . . . . . . . . 61

Alexander Clark III and Richard F. Daniels

Prescribed Fire and Slash Pine . . . . . . . . . . . . . . . . . 66

A.J. Long, A. Behm, L. Cassidy, J. DiMartino,

D. Doran, D. Freeman, J. Helmers, K. Keefe, A. Miller,

S. Ranasinghe, C. Randall, M. Rasser, A. Ruth,

D. Shipley, and A. Van Loan

Wildlife Management Issues and Opportunities

in Slash Pine Forests . . . . . . . . . . . . . . . . . . . . . . . . . 79

Michael T. Mengak and Steven B. Castleberry

Insect Enemies of Slash Pine . . . . . . . . . . . . . . . . . . 84

Terry S. Price

Major Disease Issues with Slash Pine

Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Robert. A. Schmidt

Effects of Annual Pinestraw Removal and

Mid-rotation Fertilization on Pine Growth in

Unthinned Plantations . . . . . . . . . . . . . . . . . . . . . . . . 90

E.A. Ogden and L.A. Morris

Slash Pine in Integrated Timber, Forage, and

Livestock Silvopastoral Systems . . . . . . . . . . . . . . . 98

Jarek Nowak and Alan Long

Slash Pine, Pinus elliottii var. elliottii

Select Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Bryan C. McElvany, Kim D. Coder, and

E. David Dickens

Index of Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
iv
1

INTRODUCTION

Typical slash pine (Pinus elliottii Engelm. var. elliottii) is an

excellent timber tree and one of the most important pine

species in the Southern United States. Many prefer it for its

fast growth and excellent utility for fiber, lumber, poles, and

gum naval stores. The habitat and preferred sites within its

natural range include poorly drained flatwoods and stream

edges, as well as seasonally flooded areas such as bays

and swamps.

The ease and success of planting slash pine have significantly increased in its range. Extensive planting and natural

regeneration of open agricultural and forest land brought a

sharp rise in slash pine acreage between 1952 and 1970

(Sheffield and others 1983). Much of the planting was on

sites that did not favor slash pine, and where performance

was less than optimal. As a result, land managers have

planted either loblolly (P. taeda L.) or longleaf (P. palustris

Mill.) after harvesting the slash pine. However, slash pine is

an excellent species and should be favored on appropriate sites.

This paper reviews the important silvical characteristics of

slash pine; provides a history of its development, use, and

management; reviews its status in southern forest ecosystems; and explores trends in managed slash pine forests.

SILVICAL CHARACTERISTICS

Identifying Characteristics

The typical slash pine tree has a long, clear bole and a

relatively short crown, which results from self-pruning. South

Florida slash pine (P. elliottii var. densa) (Little and Dorman

1954) differs from the more northern variety in a number of

ways, primarily because its seedlings go through a dwarf

“grass stage” similar to longleaf pine. Its stem divides into

large, spreading branches that form a flat-topped or

rounded crown. Its uniqueness and limited range have

encouraged neither research nor management of south

Florida slash pine.

The needles and cones of the typical slash pine represent

its primary identifying characteristics. Needles are 7 to 10

inches long in fascicles of two and three on the same tree.

They are dark, glossy green, and tufted at the ends of

tapering branches. They extend back some distance along

the branch and persist until the end of the second season.

Cones are 4 to 6 inches long, ovoid conic, and sessile

(fig. 1). They usually remain on the tree until the second

summer. Cones are reddish brown, lustrous, and armed with

a sharp spine. The seeds are about one-fourth inch long,

dark brown-black mottled, with thin, translucent wings about

1 inch long.

SLASH PINE: CHARACTERISTICS, HISTORY, STATUS, AND TRENDS

James P. Barnett and Raymond M. Sheffield1

1 James P. Barnett, Chief Silviculturist; and Raymond M. Sheffield, Resource Analyst, U.S. Department of Agriculture Forest Service,

Southern Research Station, Pineville, LA 71360 and Asheville, NC 28804, respectively.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Slash pine is the premier tree species on many sites throughout the South. Its ease of establishment and early

growth, however, has extended its range to many sites where its performance has been less than ideal. For that reason, the

acreage and volume of slash pine are declining. Nonetheless, it will continue to be the favored species on many sites where it

is the most appropriate and productive species. This paper reviews slash pine’s important silvical characteristics, its history

of use and management, and the status and trends of this important resource.

Figure 1—(A) mature, 2-year, closed cone (3 to 6 inches long);

(B) mature cone open after shedding seed; (C) tips of cone scale

showing variation in form of apophysis and stout prickle; (D) ventral

side of cone scale with seed in place (left), and dorsal side (right);

(E) and (F) seed and wing detached; (G) seed and wing intact (Mohr

1896).
2

Phenology

Seeds mature in a 3-year period from when the strobili are

initiated. The primordia of new strobili are detectable in late

spring. These cone initials overwinter as buds the first year.

When pollen is shed in late January or February of the

second year, the male strobili are purple and 2 inches long.

The female strobili appear on stalks in the upper crown and

are about 1 inch long and red to purple at the time of pollination. Soon after pollination, the pollen tube stops growing

and appears to remain in a quiescent state for the summer

and winter. During the third growing season fertilization

occurs—some 12 to 14 months after pollination. Cones

enlarge and seeds mature during the third summer. Needles

develop on new growth in spring and persist until the end of

the second growing season.

Distribution

The natural range of slash pine is the most restricted of all

major southern pines, extending from southern South

Carolina to central Florida and westward to southeastern

Louisiana (fig. 2). Although its natural range is relatively

small, slash pine has been planted widely and its range

extended into eastern Texas, southern North Carolina, and

the sandhills between the Coastal Plain and the Piedmont

through much of the Southeast (Fisher 1983).

Slash pine has been introduced into many countries for

timber production. Large-scale introductions have occurred

in Brazil, Chile, Argentina, Venezuela, China, South Africa,

New Zealand, and Australia. In most of these countries, it is

an adequate seed producer, and natural or artificial regeneration continues.

SOILS AND PHYSIOGRAPHY

Soils within the range of slash pine are mostly Spodosols,

Ultisols, and Entisols. It is generally believed that prior to

extensive fire suppression and planting programs, slash

pine was restricted to ponds, pond margins, and Coastal

Plain flatwoods where ample moisture provided some

degree of protection for young trees that are often killed by

fire (Gruschow 1952). Topography varies little throughout the

southeastern Coastal Plain, but small changes in elevation often coincide with abrupt changes in soil and site

conditions.

Although slash pine adapts to a wide variety of conditions, it

grows best on deep, well-aerated soils that supply ample

moisture during the growing season. Generally, growth and

site index increase with depth to a restrictive layer or seasonally high water table, if these features occur within 20 to

30 inches of the soil surface. Where depth to a restrictive

layer exceeds about 30 inches, site index declines with

increasing depth to a reliable source of moisture, such as a

stable water table or a soil horizon with large moistureholding storage capacity. Soil properties useful in estimating site index of slash pine include depth to gray mottles,

depth to a spodic horizon, depth to the least-permeable

layer or to a fine-textured horizon, thickness of the A1 horizon, and texture of the least-permeable or finest textured

horizon (Lohrey and Kossuth 1990, Shoulders and Parham

1983).

SILVICULTURAL CHARACTERISTICS

Slash pine is a subclimax species that without human

intervention and in the absence of fire or other catastrophic

event will proceed to a mixed hardwood forest. Some

authors consider it intermediate in tolerance to shade,

others consider it intolerant. It will reproduce naturally in

small openings and invade poorly stocked longleaf pine

stands, although competition from overstory and understory vegetation reduces growth and causes much mortality. The two varieties of slash pine differ in their patterns of

growth. Typical slash pine makes excellent early height

growth, but south Florida slash pine has a grasslike, almost

stemless stage that lasts from 2 to 6 years. Moreover, south

Florida slash pine lacks the straight axis or stem characteristic of the typical variety and often develops forked boles

with large branches and an open, spreading, irregularly

shaped crown (Little and Dorman 1954).

Figure 2—The current distribution of slash pine.
3

Typical slash pine is slow to express dominance in dense,

even-aged stands. As a result, height growth is slower in

very dense stands than in moderately or lightly stocked

stands. Young stands respond promptly to thinning or

release.

HISTORY

The development of steam-powered sawmills along the

tidewater during the 1830s changed the entire complexion

of timber use. Because the new mills required considerable

timber to maintain continuous operations, they were built at

river estuaries or along the banks of bayous. Slash pine

stands were the most accessible and the first to be cut

(Schultz 1983). However, it was not until post-Civil War times

that more effective timber harvesting, transporting, and

milling technologies were developed. It was about 1880

before more pines were cut for lumber than were being

destroyed for the sake of clearing land (Vance 1935).

Naval Stores

In colonial times, the great wooden ships of domestic and

international commerce needed large quantities of pitch and

tar to seal cracks—and to protect operating lines from the

deteriorating effects of moisture (Schultz 1983). By 1610,

England was importing tree resin from the Colonies, and by

1700 South Carolina had made so-called naval stores its

chief export (Schorger and Betts 1915). Production of this

commodity from the South’s piney woods became the

State’s first full-scale industry.

The primary method for producing naval stores was to tap

standing slash and longleaf pine. For many years the “box”

method was used (Fernow 1899), whereby deep holes were

cut with a boxing ax in the tree’s base and a container, or

box, was attached to catch resin, “chipping” was wounding

the tree surface or face with a hack tool—through the bark

into the phloem. The tree’s surface was chipped weekly to

maintain resin flow, and boxes were emptied every 2 or 3

weeks to prevent resin loss. Because it produced more yield

than longleaf, slash pine was preferred (Forbes 1930,

Mattoon 1922).

Cutting deep cavities into trees for collecting gum caused

significant damage to the trees. Cutting two or more boxes

in larger trees nearly girdled them, causing mortality in a

year or so. Through the untiring efforts of Dr. Charles Herty,

the “boxing” method was largely replaced by the cup-andgutter method around 1910. The new method yielded more

and higher quality resin, killed fewer trees, and left the butt

log in better condition for lumber (Croker 1979).

When U.S. Department of Agriculture Forest Service

research stations were established in the South in 1921, the

Southern Forest Experiment Station assigned Len Wyman

to Stark, FL, to improve chipping technology for the naval

stores industry. His work to reduce the size of the chipping

face resulted in substantial labor savings, reduced tree

mortality, and increased the length of time a tree could be

worked. During World War II, research on naval stores

production was emphasized, and it was determined that

gum production could be stimulated by spraying the chipped

area with sulfuric acid (McReynolds 1983).

Naval stores research continued into the 1980s with the

development of paraquat-induced lightwood (Stubbs 1983).

However, production of naval stores products dropped

significantly as tree availability decreased, costs of laborintensive work increased, and byproducts of the kraft pulping process met most of the need for turpentine and other

products (McReynolds 1983).

The Influence of Railroad Logging

The first generation of logging in pine flatwoods was confined to coastal areas and the immediate vicinity of rivers

and navigable streams. Therefore, much of the slash pine

forest was selectively cut at least once by the late 1880s

(Schutlz 1983). By the middle 1880s, high timber demands

and expanding mill facilities required loggers to exploit new

areas. Railroad logging was an answer to the problem of

accessing forests away from rivers and streams. Wherever

large pines grew, rail spurs were put in to systematically

remove pine timber. Low-speed locomotives were used to

pull cars loaded with timber over the temporary spurs.

Steam skidders were mounted on flatcars, and wire cables

could pull logs to the railcars from about 1,000 feet.

Logging and milling reached their peak in the coastal flatwoods between 1890 and 1914 (Schultz 1983). Once the

logging boom arrived, it took a little more than two decades

to clearcut and decimate the pure pine forests of the flatwoods. Most slash and mixed slash-longleaf pine forests

were cutover in the early logging and rafting days between

1780 and 1860. Fifty to one hundred years later, these

areas had again grown into pure stands of slash pine and

also were logged over, as were virgin longleaf stands. The

complete removal of old-growth pines provided conditions

for slash pine to further dominate many sites formerly occupied by longleaf pine. Large areas of the cutover longleaf

pine type in Alabama, Mississippi, Louisiana, and Texas

were planted to slash pine, thus increasing the range and

prominence of the species (Schultz 1983). Slash pine also

was planted outside its range in Georgia, South Carolina,

and North Carolina in cutover longleaf sites.

STATUS

The natural range of slash pine is more restricted than the

range of other major southern pines (Critchfield and Little

1966), but extensive plantings of slash pine have greatly

extended its range (fig. 2). We have not distinguished typical slash pine from the south Florida variety in these data,

because the latter has very limited occurrence.

While the range of slash pine is small, the species is

intensely managed. Sixty-nine percent of current slash pine

stands are planted compared to 52 percent in 1980. The

proportion of plantations to natural stands continues to rise

with each new inventory.

Slash pine is the primary species on 10.4 million acres

(table 1). The slash pine ecosystem is defined as stands

where yellow pine makes up one-half or more of the stocking, and where slash is the predominant pine.

The most concentrated areas of slash pine are in Florida

and Georgia. These two States contain about 79 percent of

the slash pine ecosystem acreage.
4

Nonindustrial private landowners hold 53 percent of slash

pine stands, the largest proportion of ownership (table 2).

Forest industries own 36 percent, while national forests and

other public agencies control the remaining 11 percent.

The volume of slash pine growing-stock sized trees across

the range totals 10.9 billon cubic feet (table 3). This inventory includes all slash pine growing stock, whether in stands

classified as a slash pine type or in some other type. Growing-stock volume includes the solid wood content between a

1-foot stump and 4.0-inch top on only the central stem in

trees 5.0 inches diameter at breast height (d.b.h.) and

larger. The stated volumes exclude rough and rotten stems,

stumps, tops, limbs, and trees < 5.0 inches d.b.h.

Seventy-two percent of the South’s slash pine volume

(7,830 million cubic feet) is located in Florida and Georgia.

Alabama, Louisiana, and Mississippi account for 22 percent (2,429 million cubic feet) (table 3).

The diameter distribution of slash pine volume reflects the

high proportion of slash pine in plantations and young

natural stands (fig. 3). Volume peaks in the 8-inch diameter

class and declines rapidly through the larger diameters.

Fifty-nine percent of the slash pine volume is in the 6-, 8-,

and 10-inch diameter classes.

The stand-age distribution shows that about 25 percent of

slash pine stands are < 8 years old (fig. 4). This confirms the

notion that the slash pine rotation age is 30 years or

Table 1—Area of timberland classed as a slash pine

forest type, by State, 1980 and 2000

State 1980 2000

- - - - - thousand acres - - - -

Alabama 716 497

Florida 5,298 5,131

Georgia 4,683 3,026

Louisiana 609 631

Mississippi 671 610

North Carolina 91 156

South Carolina 499 136

Texas 212 188

Total 12,779 10,375

Table 2—Area of timberland classed as a slash pine

forest type, by ownership class, 1980 and 2000

Ownership class 1980 2000

- - - - - thousand acres - - - -

National forest 522 493

Other public 569 684

Forest industry 4,649 3,719

Nonindustrial private 7,039 5,479

Total 12,779 10,375

Table 3—Volume of slash pine growing stock on

timberland, by State, 1980 and 2000

State 1980 2000

- - - - million cubic feet - - - -

Alabama 747 868

Florida 3,772 4,305

Georgia 4,644 3,525

Louisiana 748 790

Mississippi 664 771

North Carolina 33 183

South Carolina 592 215

Texas 256 235

Total 11,457 10,891 Figure 4—Stand-age distribution of slash pine, 2000.













        

	











Figure 3—Slash pine growing stock by diameter class, 2000.





 




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5

younger, and that slash pine is intensively managed. Smalldiameter trees make up a large proportion of the slash pine

resource, primarily because forest industry has managed it

for short rotations.

The current (2000) net annual growth of slash pine growing

stock totals 871 million cubic feet (table 4). This is equivalent to a growth rate (growth as a percent of inventory) of 8.0

percent. Annual removals of slash pine growing stock total

927 million cubic feet, or 56 million cubic feet (about 6

percent) over annual growth. The most significant amount of

removals over growth occurs in Florida, where it exceeded

growth by 55 million cubic feet, or nearly 18 percent.

Removal volumes include all slash pine trees removed from

commercial forest land by human activities, regardless of whether the trees actually are used.

TRENDS

Sheffield and others (1983) published 1980 resource data in

the proceedings of the 1981 managed slash pine ecosystem symposium (Stone 1983). These data, paired with

year 2000 data in tables 1 through 4, provide a comparison

of resource issues related to the slash pine ecosystem.

The fact that 69 percent of slash pine stands are planted

indicates that the slash pine ecosystem is intensively

managed. Most of the ecosystem is located in Georgia and

Florida, and largely within areas adjoining the two States.

However, over the last 20 years the area of timberland

classified as slash pine has decreased from 12.8 to 10.4

million acres, or nearly 19 percent (table 1).

The loss of acreage in slash pine has occurred over most of

its range. Data from the two States that show increases—

Louisiana and North Carolina—may not represent current

conditions, because forest survey data in those States have

not been completely updated. Within Florida the acreage

remains stable, whereas in Georgia there has been a 35-

percent decrease over the last two decades.

Long-term trends indicate that slash pine acreage increased

significantly during the 1950s and 1960s, with increases

from about 8.4 to 10.4 million acres (Sheffield and others

1983). Those increases were related to the conversion of

farmland to forests, reforestation of cutover forests, and

planting out of the native range of slash pine. The trend

leveled off in the 1970s and 1980s. Obviously, the trend now

is one of decreasing acreage. This loss is at least partially a

result of longleaf pine restoration efforts on many sites

where slash pine had been planted, the loss of slash pine

sites to urbanization, and the planting of loblolly pine on

forest industry lands where slash was previously planted.

The greatest losses (about 20 percent) in slash pine timberland occurred on private ownership—both forest industry

and nonindustrial private lands (table 2). Slash pine within

the national forests decreased 5 percent, probably as a

result of conversion to longleaf pine on forests outside the

natural slash pine range. The only ownership showing an

increase in slash pine timberland is the “other public”

category.

Table 4—Net annual growth and removals of slash pine

growing stock by State, 1980 and 2000

Net annual growth Annual removals

State 1980 2000 1980 2000

- - - - - - - - million cubic feet - - - - - - - -

Alabama 48 60 35 55

Florida 383 309 262 364

Georgia 405 338 265 316

Louisiana 83 66 41 53

Mississippi 44 45 37 54

North Carolina 9 9 0 18

South Carolina 66 20 23 45

Texas 30 25 12 23

Total 1,068 871 675 927

The volume of slash pine growing stock in the entire ecosystem declined from 11.5 billion cubic feet in 1980 to 10.9

billion cubic feet in 2000 (table 3). It is particularly interesting to note the differing trends in Florida and Georgia.

Although Florida’s proportion of the growing stock increased

12 percent, from 3.8 to 4.3 billion cubic feet, there was a

major decrease in Georgia. A 24-percent reduction in

growing stock occurred in Georgia, with losses of 1.1 billion

cubic feet. Texas and South Carolina were the only other

States with losses of growing stock.

The year 2000 distribution of slash pine growing stock by

diameter classes follows a pattern similar to that of 1980

(Sheffield and others 1983), although 59 percent of the

current volume is in the 6-, 8-, and 10-inch classes compared to 64 percent in 1980 (fig. 3). In 2000, there was a

smaller proportion in the 6-inch and a corresponding

increase in the 14- through 22-inch diameter classes than

there was in 1980. Stand-age data confirm the notion that

older stands continue to be aggressively harvested, and

that the average rotation age is 35 years or less (fig. 4).

A relatively small proportion of stands are older than 40

years.

In contrast to the situation in 1980 when net annual growth

exceeded annual removals, in year 2000 removals

exceeded growth by about 6 percent (table 4). In Florida,

removals far exceeded growth, although the acreage in

slash pine remained relatively constant. This may be

because where slash pine is intensively managed, there are

large numbers of recently harvested stands that have been

regenerated, but where trees have not reached a size that

constitutes significant volume.

CONCLUSIONS

Slash pine is one of the most important pine species in the

Southern United States, and its ecosystem produces a

habitat that favors a wide range of biological diversity. It

produces fast growing stands that are excellent for fiber,

lumber, poles, and gum naval stores. It is adapted to shortrotation forestry, where ease of regeneration and fast early

growth are important. Because of its favorable growth characteristics, the slash pine range has been widely extended.
6

Slash pine has performed less than ideally on many sites,

particularly when rotation is longer than 35 years. However,

on good sites within its natural range, it is the premier

species.

Although it has been planted across the South from eastern

Texas to eastern North Carolina, most slash pine volume

occurs in southern Georgia and northern Florida. Even in

Georgia, the volume of slash pine growing stock has

declined. Many sites in the Southeast that are more adapted

to longleaf pine were converted to slash pine decades ago

because of the ease of regeneration and fast early growth.

Recent interest in and financial support for converting such

sites to longleaf pine have resulted in the reduction of slash

pine acreage and volume.

Although the acreage and volume of growing stock have

declined in recent years, slash pine remains the bestadapted and productive species for many sites within its

range. On appropriate sites, slash pine is an excellent

species that is well adapted for and should be favored in

management.

LITERATURE CITED

Critchfield, W.B.; Little, E.L., Jr. 1966. Geographic distribution of

the pines of the world. Misc. Publ. 991. Washington, DC: U.S.

Department of Agriculture, Forest Service. 97 p.

Croker, T.C., Jr. 1979. The longleaf pine story. Journal of Forest

History. 23: 32-43.

Fernow, B.E. 1899. Report upon the forestry investigations of the

USDA, 1877–1898. Washington, DC: U.S. Department of

Agriculture. 401 p.

Fisher, Richard F. 1983. Silvical characteristics of slash pine (Pinus

elliottii Englem. var. elliottii). In: Stone, E.L., ed. The managed slash

pine ecosystem: Proceedings of a symposium. Gainesville, FL:

University of Florida, School of Forest Resources and

Conservation: 48-55.

Forbes, R.D. 1930. Timber growing and logging and turpentining

practices in the southern pine region. Tech. Bull. 204. Washington,

DC: U.S. Department of Agriculture. 115 p.

Gruschow, G.F. 1952. Effect of winter burning on growth of slash

pine in the flatwoods. Journal of Forestry. 50: 515-517.

Little, E.L., Jr.; Dorman, K.W. 1954. Slash pine (Pinus elliottii), including south Florida slash pine: nomenclature and description. Station

Pap. 36. Asheville, NC: U.S. Department of Agriculture, Forest

Service, Southeastern Forest Experiment Station. 82 p.

Lohrey, R.E.; Kossuth, S.V. 1990. Pinus elliottii Englem. Slash pine. In:

Silvics of North America: conifers. Agric. Handb. 654. Washington,

DC: U.S. Department of Agriculture: 338-347. Vol. 1.

Mattoon, W.R. 1922. Slash pine primer. USDA Farmer’s Bull. 1256.

Washington, DC: U.S. Department of Agriculture. 8 p.

McReynolds, Robert D. 1983. Gum naval stores production from

slash pine. In: Stone, E.L., ed. The managed slash pine ecosystem:

Proceedings of a symposium. Gainesville, FL: University of

Florida, School of Forest Resources and Conservation: 375-384.

Mohr, C. 1896. The timber pines of the Southern United States. Bull.

13. Washington, DC: U.S. Department of Agriculture, Division of

Forestry. 160 p.

Schorger, A.W.; Betts, H.S. 1915. The naval stores industry. Tech.

Bull. 229. Washington, DC: U.S. Department of Agriculture. 58 p.

Schultz, Robert P. 1983. The original slash pine forest—an historical

view. In: Stone, E.L., ed. The managed slash pine ecosystem:

Proceedings of a symposium. Gainesville, FL: University of

Florida, School of Forest Resources and Conservation: 24-47.

Sheffield, R.M.; Knight, H.A.; McClure, J.P. 1983. The slash pine

resource. In: Stone, E.L., ed. The managed slash pine ecosystem:

Proceedings of a symposium. Gainesville, FL: University of Florida,

School of Forest Resources and Conservation: 4-23.

Shoulders, E.; Parham, G. 1983. Slash pine. In: Burns, R.M., tech.

coord. Silvicultural systems for the major forest types in the United

States. Agric. Handb. 445. Washington, DC: U.S. Department of

Agriculture: 161-166.

Stone, E.L., ed. 1983. The managed slash pine ecosystem: proceedings of a symposium. Gainesville, FL: University of Florida, School

of Forest Resources and Conservation. 434 p.

Stubbs, Jack. 1983. Paraquat-induced lightwood in southern pines. In:

Stone, E.L., ed. The managed slash pine ecosystem: Proceedings

of a symposium. Gainesville, FL: University of Florida, School of

Forest Resources and Conservation: 385-393.

Vance, R.B. 1935. Human geography of the South. Chapel Hill, NC:

University of North Carolina Press. 596 p.
7

INTRODUCTION

Large-scale tree breeding programs (also called tree

improvement programs) began in the 1950s. Zobel and

Talbert (1984) cite 23 papers from 14 countries published

in the 1950s that advocate or describe tree improvement

programs. Today, there are breeding programs for nearly

all commercially-important tree species and multiple

programs sponsored by different organizations for some

species in different regions or countries. Breeding of slash

pine (Pinus elliottii Engelm.) also started in the 1950s.

Early on, slash pine was recognized as being second in

importance to only loblolly pine as a target for tree improvement in the southern USA. This was despite the fact that it

has the most restricted range of the four major species of

southern pines (Dorman 1976). Slash pine is adapted to a

variety of difficult sites in the southern most part of the

commercial pine range and has been planted extensively.

It is generally acknowledged to be more resistant to fire

and tip moth than loblolly pine, and to be as well suited for

naval stores production, as is longleaf pine. Its good stem

form and wood quality traits make it extremely valuable for

solid wood products as well as also being an excellent

feedstock for pulp production.

Slash pine tree improvement in the southern USA is mainly

conducted by the members of two regional cooperatives in

which private industry, state agencies and university

personnel all work together cooperatively. The purposes of

this report are to: (1) Describe the nature and infrastructure

of these two tree improvement cooperatives; (2) Summarize the first-generation tree improvement programs of both

cooperatives, which have been completed; (3) Highlight key

features of their on-going second-generation programs;

and (4) Document the genetic gains and genetic diversity

in the operational plantations currently being established

by members of these two cooperatives.

TREE IMPROVEMENT COOPERATIVES OF

SLASH PINE

Organization and Activities of Slash Pine

Cooperatives

Slash pine breeding programs in the southern USA are

conducted cooperatively through two regional tree improvement cooperatives: Cooperative Forest Genetics Research

Program (CFGRP) housed at the University of Florida in

Gainesville, FL and Western Gulf Forest Tree Improvement

Program (WGFTIP) centered at the Texas Forest Service,

Texas A&M University, in College Station, TX. These tree

improvement cooperatives consist of private companies,

state agencies and university personnel all working

together to conduct selection, breeding, progeny testing

and research to genetically improve slash pine. The CFGRP

was initiated in the 1950s and has been conducting slash

pine tree improvement continuously ever since. Tree

improvement started at Texas A&M University in the early

1950s as a cooperative program between the Texas Forest

Service and several organizations in East Texas. Soon

after, there were several other independent programs

operating in the area. WGFTIP was formally founded in

1969 when several of these former programs agreed to

join forces and new members were added to the effort.

The CFGRP and WGFTIP have similar organizational

structures and these structures have changed little since

SLASH PINE TREE IMPROVEMENT

Tim L. White and Tom D. Byram1

1 Tim L. White, Professor of Forest Genetics, School of Forest Resources and Conservation, University of Florida, Gainesville, FL

32611-0410; and Tom D. Byram, WGFTIP Geneticist, Texas Forest Service, and Assistant Professor, Forest Science Department, Texas

A&M University, College Station, TX 77803-2585.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Slash pine breeding programs in the southern USA began more than a half century ago and are conducted

in two tree improvement cooperatives: Cooperative Forest Genetics Research Program, CFGRP, housed at the

University of Florida in Gainesville, and Western Gulf Forest Tree Improvement Program, WGFTIP, centered at the

Texas Forest Service, Texas A&M University, in College Station. These tree improvement cooperatives consist of

private companies, state agencies and university personnel all working together to conduct selection, breeding,

progeny testing and research to genetically improve slash pine. The CFGRP consists of 10 members improving slash

pine in its native range. Six of the 14 members of the WGFTIP participate in the tree improvement program of slash pine

as an exotic for the lower coastal plain areas of TX, LA and MS. Members of both cooperatives are: (1) In the second

generation of breeding and testing; (2) Focusing on improvement of a few key traits, the most important of which are

volume yield and resistance to fusiform rust; (3) Maintaining large breeding populations, consisting of several hundred

selections, to sustain genetic diversity of the species; (4) Establishing operational plantations with expected genetic

gains in total yield of more than 30 percent above plantations established with unimproved material; and (5) Making

genetically-improved slash pine available to non-members and small private landowners through seed and seedling

sales. Nearly 100 percent of all new plantations of slash pine are being planted with genetically-improved material,

although the degree of improvement varies.
8

the inception of the cooperatives. Each cooperative has a

small staff (3 to 4 people centered at the University of

Florida for the CFGRP and at the Texas Forest Service in

College Station for the WGFTIP) which performs the following functions: (1) Provides scientific leadership in developing and implementing breeding strategies; (2) Conducts

research and development in both basic forest genetics

and applied tree improvement; (3) Provides technical

support to cooperative members; and (4) Carries out data

management and data analysis of all cooperative experiments and genetic tests. The latter function is especially

important because both cooperatives have hundreds of

field experiments with data collected every few years. With

personnel changes and corporate mergers, a key function

of the cooperative staff is to provide institutional memory

about when, where and how to measure cooperative field

tests.

The private companies and state agencies that are the

members of the tree improvement cooperatives are active

participants in every phase of cooperative activity. The

members: (1) Set policy and direction of the cooperative

through participation in advisory councils and executive

committees that meet as often as needed, but at least

annually; (2) Provide financial support to the cooperative in

the form of annual dues and in-kind contributions; and,

most importantly, (3) Conduct all field activities of the tree

improvement programs using their personnel and their

equipment on their timberlands (for example, selection,

field testing and breeding). It is an understatement to say

that the southern USA owes much to the foresight of the

founding and continuing members of tree improvement

cooperatives. The private companies compete in most

every other aspect of their business, but decided long ago

to cooperate in the long-term efforts to genetically improve

southern pines for the betterment of the entire region.

Magnitude and Impact of Slash Pine Tree

Improvement Efforts

The CFGRP consists of 10 members improving slash pine

in its native range, principally in the lower coastal plain

regions of GA, FL and AL. These members own or lease

2.7 million acres of slash pine plantations. They produce

50 million genetically-improved slash seedlings each year

that are used to reforest 110,000 acres of their own timberlands. In addition to the seedlings produced for reforestation of their own timberlands, CFGRP members sell 70

million genetically-improved slash pine seedlings and

4,000 pounds of genetically improved seed each year to

non-members.

Six of the 14 members of the WGFTIP (3 private companies

and 3 state agencies) participate in the tree improvement

program of slash pine as an exotic for the lower coastal

plain areas of TX, LA and MS. These six WGFTIP members

own or lease 0.7 million acres of slash pine plantations.

They produce 6.5 million genetically-improved slash seedlings each year that are used to reforest 10,000 acres of

their own timberlands. In addition to the seedlings produced

for reforestation of their own timberlands, WGFTIP members

sell 13.5 million genetically-improved slash pine seedlings

and 1,500 pounds of genetically improved seed each year

to non-members.

For members of both cooperatives, the relative importance

of slash pine has diminished through the years as loblolly

pine (Pinus taeda L.) has become more important, and

both cooperatives also have tree improvement efforts for

loblolly pine. Therefore, it is useful to estimate the total size

of the plantation estate of slash pine being supported by

the breeding efforts of the two cooperatives. One way to

measure this is simply the sum of the slash pine plantations

currently owned or leased by the members (2.7 and 0.7

million acres by the CFGRP and WGFTIP members, respectively). However, these figures suffer in two ways: (1) Current

ownership reflects historical patterns of plantation establishment, not current or future trends (for example, members

could be converting these plantations to loblolly pine as

they reach harvest age); and (2) These ownership figures

do not include slash pine plantations managed by nonmembers who purchase genetically-improved seed or

seedlings from cooperative members. For example, small,

non-industrial landowners who purchase geneticallyimproved seedlings directly benefit from the efforts of the

two cooperatives.

Another way to estimate the current size of the slash pine

plantation estate being supported by the breeding efforts

of the cooperatives is to assume that annual reforestation

rates and seed and seedling sales have reached equilibrium values that are not changing through the years. Then,

if all of the seed and seedlings are being planted in the

southern USA (we ignore the small fraction of seed being

sold internationally), we can calculate the “regulated”

plantation estate assuming a 20-yr rotation. For example,

for the CFGRP, there are 50 million seedlings planted

annually on member timberlands and 70 million seedlings

sold to non-members. In addition, the 4,000 pounds of

seed sold to non-members equates to another 32 million

plantable seedlings (assuming 8,000 plantable seedlings

per pound of seed). Therefore, total annual reforestation of

genetically-improved seedlings of slash pine supported by

CFGRP members is 152 million seedlings (50+70+32)

which means approximately 215,000 acres of annually

reforestation (assuming 700 trees planted per acre).

Assuming a regulated forest with a 20-yr rotation, the total

plantation estate of slash pine being supported by the

CFGRP tree improvement cooperative is 4.3 million acres

(215,000 * 20). Similarly for the WGFTIP, internal seedling

use, seedling sales and seed sales sum to 32 million

seedlings annually which supports a regulated plantation

estate of slash pine of approximately 1 million acres.

To put these numbers in perspective, there were a total of

1.7 billion forest tree seedlings planted in the entire USA in

1999 and 1.2 billion of these were loblolly pine in the

southern USA (http://www.afandpa.org/forestry/forestry.html).

Slash pine reforestation with seedlings bred by the two

cooperatives totals 180 million seedlings each year (150

and 30 for the CFGRP and WGFTIP, respectively) which is

approximately 15 percent of the reforestation of loblolly

pine and 10 percent of all tree seedlings planted nationwide. To our knowledge, these figures account for nearly

all slash pine reforestation in the southern USA.
9

FIRST-GENERATION IMPROVEMENT OF

SLASH PINE

Genetic improvement programs capitalize on the facts that

there is tremendous genetic variation within most tree

species and that family members resemble each other more

closely than do unrelated individuals. One of the oldest

and historically most successful schemes to take advantage of these facts is the method of genetic improvement

referred to as recurrent selection (RS). Recurrent selection

uses repeated cycles of breeding aimed at the gradual and

cumulative improvement of a few traits in a population

(Shelbourne 1969, Namkoong and others 1988 Chapter

3). The benefits of breeding accumulate in each cycle or

generation as improvement builds upon advances made in

prior generations.

The oldest form of RS is called simple recurrent selection

in which each cycle of breeding involves: (1) Mass

selection of individuals based solely on phenotypic appearance; and (2) Breeding of these phenotypically-superior

individuals to produce the offspring available for selection

in the subsequent generation. In this form, the selected

and breeding populations are identical and there is no

genetic testing or pedigree control. Simple recurrent

selection was the method used more than 10,000 years

ago by ancient farmers to improve their field crops (Briggs

and Knowles 1967): seed from phenotypically-superior

individuals was retained for next year’s crop. Simple

recurrent selection is what landowners practice when they

leave the best trees to seed in the next generation.

Simple recurrent selection is rarely used in modern tree

breeding programs, because it is less efficient at achieving

genetic gains than forms of recurrent selection that incorporate genetic testing and pedigree control. The vast majority

of conifer breeding programs employ recurrent selection

for general combining ability (RS-GCA) (Shelbourne 1969,

Namkoong and others 1988). In RS-GCA, genetic testing

follows selection. This generally takes the form of progeny

tests where the breeding values of parents are evaluated

by tracking the performance of their offspring. Selections

with high GCA values for any trait are those that produce

top-performing offspring. To start the next cycle, parents

with high GCAs and their offspring are selected for further

breeding and testing, while poor-GCA selections are eliminated from the program. Genetic testing greatly increases

the genetic gain above that possible from mass selection.

This is especially true for traits with low heritabilities which,

unfortunately, account for most economically-important

traits of conifers.

This section documents the first-generation tree improvement programs of slash pine in the CFGRP and WGFTIP.

These programs began in the 1950s and the CFGRP

first-generation cycle was completed in the 1980s. The

first-generation cycle for the WGFTIP is currently being

completed. Both cooperatives employed similar breeding

strategies involving: (1) Mass selection of outstanding trees

from natural stands and plantations based solely on outward appearance; (2) Grafting a portion of those trees in

clonal seed orchards to produce genetically-improved

seed for operational reforestation, while establishing the

remainder in scion banks for preservation and breeding;

(3) Establishment of progeny tests to rank the selections

based on GCA; and (4) Breeding together of first-generation selections to create new combinations of genes and

planting of these seedlings in tests to make second-generation selections. Details of the first-generation slash pine

tree improvement programs are in tables 1 and 2 for the

CFGRP and WGFTIP, respectively, and the highlights are

summarized below.

Breeding Zones and Base Populations

Tree improvement programs are organized around geographic areas known as breeding zones. These are deployment areas where important economic traits are similar and

in which the performance of the outplanted trees can be

accurately predicted. Thus, the breeding zone is the geographical area for which an improved variety is being

developed. Determining breeding zone boundaries is a

critical decision in tree improvement programs, because

each breeding zone requires a separate improvement

program with its own distinct base, selected, breeding, and

propagation populations. The tendency in conifer breeding

programs is to develop large breeding zones to minimize

costs associated with multiple programs and to breed

improved varieties that have broad adaptability. This

approach is suitable when genotype x environment interaction is not important for most traits across the edaphoclimatic region in the breeding zone and when conserving

natural patterns of geographic variation is not a primary

concern.

For slash pine in the southeastern USA (table 1), the

CFGRP defined a single breeding zone consisting of the

entire natural range of the species, approximately 10 million

acres of timberlands (White and others 1986). A single

program with its base, selected and breeding populations

is being conducted for this zone. Similarly for slash pine in

the Western Gulf, the WGFTIP defined a single breeding

zone consisting of the flatwoods sites that stretch across

the southernmost parts of the coastal plains in Mississippi,

Louisiana, and Texas (table 2). Much of this area is outside

the natural range of the species, but includes large areas

in which slash pine has been planted as an exotic since

the 1930s.

While there are many similarities between the two breeding

zones of the CFGRP and WGFTIP, there are also some

significant differences. In the southeastern USA slash pine

is frequently found on well-drained sandy soils, while in

the Western Gulf region it is favored for planting on poorlydrained, phosphorous-deficient silty clay soils. In the

southeastern USA, there are areas where fusiform rust

(Cronartium fusiforme) and its obligate alternative host, the

red oaks, are present at only low levels. In these areas,

growth rate is the most important economic trait. In the

Western Gulf region, where slash pine has not coevolved

with the endemic pathotypes and red oaks are plentiful,

improving resistance to fusiform rust is the single most

important goal of the tree improvement program.

The base population of a given cycle of improvement consists of all available trees that could be selected if desired

(Zobel and Talbert 1984). It is the population of trees that

will be improved upon through selection and breeding and
10

hence is also called the foundation population. In firstgeneration conifer breeding programs, the base population is typically very large consisting of many thousands or

millions of trees. In the case of the CFGRP, any tree growing

in natural stands within the native range was, at least in

concept, a potential candidate for selection and therefore

inclusion in the program.

The WGFTIP base population drew on native stands of

slash pine from southeastern MS and planted stands in

MS, LA and TX. The intent was to capitalize on the beginnings of a land race that was created when slash pine

was established as an exotic in the Western Gulf region.

However, as most of the WGFTIP first-generation selections originated from populations that were, at most, only

one generation removed from the native range, both

programs originally sampled the same genetic resource.

Selected Population

In the first generation, both the CFGRP and WGFTIP used

a process called mass selection to select outstanding trees

based on their phenotypic, outward appearance. For both

cooperatives, first-generation selections were identified by

comparing growth rates and other characteristics of candidate trees to five comparison trees chosen among the candidate’s neighbors. The selection procedure emphasized

Table 1—First- and second-generation breeding programs for Pinus elliottii as conducted by the Cooperative Forest

Genetics Research Programa

Category First generation Second generation

Breeding Increase volume yield, resistance to Cronartium Increase volume yield, resistance to Cronartium

objectives fusiforme (rust) and stem straightness. fusiforme (rust), stem straightness and wood specific

gravity.

Breeding One large breeding unit encompassing the natural One large breeding unit encompassing the natural

unit range of slash pine. range of slash pine.

Base Ten million acres of predominantly natural stands (1) Field tests containing 2,700 FS families and

population encompassing the entire native range. 200,000 trees available as forward selns; (2) 1,200

FG selns plus 1,250 FG infusions available as

backward selns.

Selected 1955–65: 1,200 intensive selns made by comparison 1987–88: 965 selns: (1) one-third are backwards

population tree method: volume, stem straightness, freedom from selns of top first-generation parents; (2) one-third are

disease, crown form. forward selns; and (3) one-third are untested infusions

not bred in FG.

Propagation 1955–70: 2,500 acres of clonal SO established by 1990–95: 600 acres of clonal SO established by

population CFGRP members. Each member’s SO contained their CFGRP members. Each SO contained the best 20 to

25 to 150 original selns. Bulk collections of wind- 40 backward and forward selns from the selected

pollinated seed used for reforestation. population. Single-family collections of OP seed are

used for reforestation.

Progeny 1965–80: 350 OP field tests (325,000 trees) to rank No separate progeny testing to rank selns prior to

testing 1,200 selns. Seed collected from selns grafted in SOs. breeding and testing described below.

Infusions 1970–85: 1,250 infusions: (1) 850 rust-free selns in 1995: 85 infusions: (1) 70 selns obtained as top forward

highly-infected stands; (2) 125 selns from the southern selns from USDA Forest Service field trials upon

part of the range; (3) 115 selns for high yield of oleo- closure of USFA program; and (2) 15 new backward

resin; (4) 60 selns free of pitch canker fungus; and selns of top first-generation parents after reanalysis of

(5) 100 others. data.

Breeding 1970–85: 820 top selns (600 of 1,200 original selns 1995–2001: 1,050 selns in 24 BGs with 44 selns/BG.

population plus 220 of 1,250 infusions) bred together in 6 parent Complementary mating designs: (1) for ranking,

disconnected diallels and factorials to create 2,700 FS polymix mating of 325 poorly-tested selns planted in

families planted in 225 field tests containing 200,000 16 replicated tests containing 55,000 trees; and (2) for

trees. forward selection, breeding among all 1,050 selns use

to create 1,500 FS families planted in unreplicated

plots in 12 locations with 100,000 trees.

BG = breeding group; FG = first generation; CP = control-pollinated; FS = full-sib; OP = open-pollinated; seln = selection; SO = seed orchard. a The generation intervals were: 1955 to 1985 for the first generation and 1987 to 2003 for the second generation.

Source: White and others (1986), White and others (1993).
11

growth rate, wood specific gravity, stem straightness, and

crown form. Selected trees were required to be free of

fusiform rust, but otherwise no pressure was placed on

improvement of this trait. Most selections were made in low

hazard stands where rust was not prevalent; so, little

advancement in rust resistance was made during the first

round of selection.

From 1955 through 1965, the CFGRP made 1,200 selections in natural stands growing within the native slash pine

range (table 1). These selections were widely distributed

across many counties in FL, GA and AL with fewer from SC

and MS. Most of the 1,000 first-generation slash pine

selections by the WGFTIP were made in areas where slash

pine was planted as an exotic in southern TX and LA.

These selections originated from even aged plantations of

unknown origin. Selection activity began in the mid 1950s

by the Texas Forest Service and other organizations

working independently. Selection continued from 1969

until 1983 as part of the WGFTIP cooperative. The bulk of

the WGFTIP selections were made in the 1970s.

Propagation Populations: Clonal Seed Orchards

Cooperators soon realized that it was critical to capture

value from these selections by establishing them in clonal

seed orchards. A clonal seed orchard is a collection of

selections grafted in one physical location and then

managed to produce genetically-improved seed for operational reforestation. By establishing the selections in a

single location, both male and female parents are selected

and thus theoretical genetic gains are doubled compared

to collecting seed from the selections growing in the original stands. The gains from these original first-generation

clonal seed orchards reflect only the gains from mass

selection. That is, the seed produced from these original

orchards is genetically-improved only to the extent that the

mass selection was successful in identifying geneticallysuperior trees.

Table 2—First- and second-generation breeding programs for Pinus elliottii as conducted by the Western Gulf Forest

Tree Improvement Cooperative

Category First generation Second generation

Breeding Increase resistance to Cronartium fusiforme (rust), Increase volume yield, resistance to Cronartium

objectives volume yield, and stem straightness. Maintain regional fusiforme (rust), stem straightness and wood specific

averages for specific gravity. gravity.

Breeding One large breeding unit encompassing the flatwoods One large breeding unit encompassing the flatwoods

unit of MS, LA, and TX. of MS, LA, and TX.

Base Natural stands in MS and plantations in MS, LA, and (1) Field tests containing 712 FS families and 168,000

population TX where slash pine was planted as an exotic. Most of trees available as potential forward selns; (2) 500 FG

these plantations were of unknown origin, but came selns.

from seed collected in the native range.

Selected 1955–83: 1,000 intensive selns made by comparison Target of 550 selns: (1) 90 will be backwards selns of

population tree method: volume, stem straightness, freedom from top first-generation parents; (2) 460 will be forward

disease, crown form. This was reduced to 500 selns; currently 166 second-generation selections

selections based on performance at the Resistance have been identified. The remainder of the second–

Screening Center. generation selns will be identified by 2010.

Propagation Six organizations currently manage 200 acres of first 130 acres of advanced-generation SO established by

population and 1.5 generation orchards. Bulk and family collec- WGFTIP members. Each SO contained the best 20 to

tions of wind-pollinated seed used for reforestation. 40 backward and forward selns chosen for disease

resistance and volume growth. Bulk and family

collections of OP seed are used for reforestation.

Control-mass pollinated seed and rooted cuttings will

also be used.

Progeny 120 progeny tests established to evaluate 367 parents Currently 3 polymix tests established to evaluate 37

testing in CP tests and 22 parents in OP tests. The last second-generation parents. Eventually there will be

remaining first-generation progeny tests should be approximately 550 parents evaluated in polymix tests.

established in 2003.

Infusions None None

BG = breeding group; FG = first generation; CP = control-pollinated; FS = full-sib; OP = open-pollinated; Seln = selection; SO = seed

orchard.
12

Members of both the CFGRP and WGFTIP cooperatives

used similar processes to establish their clonal seed

orchards involving the following steps: (1) Selections were

made in the base populations as described in the previous

section; (2) Many branch tips (say 100 pieces), called scion

material, were collected from each selection; (3) The scion

pieces from each selection were grafted onto seedling

rootstock to produce the plants for establishing the seed

orchard; (4) All plants originating from a single selection

have the same genotype as that selection, since all

branches have the same genotype, and these plants are

called a clone; (5) Each first-generation seed orchard

established through this means contained 20 to 200 plants

of each clone (that is, grafts from each selection) from a

total of 20 to 150 different selections; (6) The grafted plants

were established in the orchard location at relatively wide

spacing (for example, 15 ft x 30 ft) compared to plantations

to provide full sunlight to the crowns to promote flowering;

(7) Each plant was identified by its clone number, and

ramets of the same clone were maintained at a minimum

distance from each other to reduce selfing; and (8) After

planting, the orchard was managed intensively to produce

mass quantities of open-pollinated seed, and this seed

was used for operational forestation. Cultural management

of clonal seed orchards is completely different than that of

plantations and genetic tests due to the very different

objective: seed production.

CFGRP members established nearly 2,500 acres of firstgeneration seed orchards between 1955 and 1970. These

mainly contained each member’s selections meaning there

was little exchange of selections among cooperators. In

the Western Gulf, some organizations were working independently prior to the formation of the WGFTIP cooperative,

while others were working together from the very beginning.

Early orchards emphasized a variety of different traits. The

Texas Forest Service established its first slash pine orchard

in 1957 selected for growth rate and form. Small orchards

were later established that emphasized high wood density

(1964) and known fiber properties (1966). The Louisiana

Department of Agriculture and Forestry established one of

their first slash pine orchards in 1967 with clones obtained

from the USDA Forest Service that were selected for

enhanced naval stores properties. Crown Zellerbach (now

Weyerhaeuser Company) established their first slash pine

orchard in 1964 with selections made off of their own land.

Organizations establishing orchards in cooperation with

the Texas Forest Service or after the cooperative was

formed in 1969 shared many of the same clones. All of the

later orchards were established with clones selected for

growth and form.

All of these first-generation seed orchards were established solely on the basis of outward appearance of the

trees that were selected and subsequently grafted. That is,

there was no evidence from genetic tests that the selections were, in fact, genetically superior to other candidate

trees that were not selected. As data from genetic tests

began to become available (described in the next section),

it turned out that, in fact, some of the selections were

inferior and some were superior to average, unimproved

trees for the few commercially-important traits being measured. As these data became available, cooperators

rapidly eliminated poor clones (that is, clones whose

offspring had performed poorly in genetic tests) to upgrade

the genetic quality of the orchard seed. This process is

called roguing, and roguing poor clones from a seed

orchard can increase expected genetic gains by 40-50

percent over the initial mean (Talbert and others 1985;

Li and others 1999).

Through the process of roguing, expected gains of CFGRP

first-generation seed orchards went from an average of

9 percent volume yield above unimproved material to

14 percent gain (table 3). These values are averages over

more than 20 first-generation seed orchards owned by different CFGRP members and individual orchard gains vary

markedly depending on the exact composition of selections originally grafted. As more and more data became

available from genetic tests, CFGRP members began to

exchange clones with other members so that all could have

the very best tested clones. Members established, through

grafting, new seed orchards containing these very best

first-generation clones obtained from the pool of 1,200

selected by the entire cooperative. These so-called 1.5-generation orchards averaged 18 percent in volume yield and

also contained selections with considerable rust resistance (table 3). While many clones were common to most

1.5-generation CFGRP seed orchards, some members put

more emphasis on rust resistance and others on growth

rate; so, expected gains and clonal composition did vary.

In the Western Gulf, fusiform rust was increasingly recognized as an important problem, and all orchard clones

were tested for disease resistance at the USDA Forest

Service’s Resistance Screening Center between 1980 and

1983 (Anderson and others 1983; Anderson and Powers

1985). These greenhouse tests, employing artificial inoculation of progeny of the orchard clones, identified susceptible selections, and existing first-generation orchards were

heavily rogued based on this criterion. All subsequent

orchards were established with material selected for both

growth and disease resistance. The WGFTIP now has 194

acres (76 ha) of first and 1.5 generation orchards improved

for rust resistance, growth, and form managed by six organizations. Gain estimates cannot be compared across the

cooperatives because data summarization procedures

differ. The WGFTIP breeding values for volume include a

survival factor to account for less mortality due to improved

rust resistance. R50s, while similar in concept, are also

difficult to compare because the fusiform rust populations

and environmental conditions under which selections from

the two programs were evaluated also differ. Current

WGFTIP production orchards, which include heavily rogued

first-generation orchards and advancing-front orchards

with both backward and forward selections have an estimated breeding value for volume of 30 percent and an R50

of 32. The younger advancing-front orchards that are not

yet into production have an average projected breeding

value for volume of 38 percent and an R50 of 25.

Genetic Testing and Breeding

Genetic tests are central to all tree improvement programs

and are established with pedigreed, well-labeled offspring

or clonal plantlets, such as offspring from the first-generation selections planted in randomized, replicated tests
13

(McKinley 1983; Zobel and Talbert 1984, Chapter 8; van

Buijtenen and Bridgwater 1986; White 1987; Bridgwater

1992). The tests are usually planted in field locations on

forest sites, but may also occur in nurseries, greenhouses

and growth rooms. The idea of these “common garden”

tests is to grow genotypes in replicated environments so

that genetic effects can be isolated from confounding

environmental effects.

Tree improvement programs rely on genetic testing to: (1)

Evaluate relative genetic quality of selections made in any

cycle of selection (that is, progeny testing to rank the GCAs

of first-generation selections based on the performance of

their offspring); (2) Estimate genetic parameters such as

heritabilities, genetic correlations, and genotype x environment interactions for key traits; (3) Provide a base population of new genotypes from which to make the next cycle of

selection; and (4) Quantify or demonstrate genetic gains

made by the program.

The third function of genetic tests mentioned above involves

another activity, called breeding. Some or all of the individuals in the selected population are included in that cycle’s

breeding population and are intermated (cross bred) to

regenerate genetic variability through recombination of

alleles during sexual reproduction. Many different mating

designs are used to intermate the members of the breeding

population, and offspring from these intermatings are

planted in genetic tests that form the next cycle’s base

population. This completes one cycle of the core activities

of the breeding cycle (selection, breeding and testing), and

the next cycle begins with new selections being made from

these genetic tests (that is, from the new base population).

The CFGRP and WGFTIP employed different strategies for

genetic testing and breeding in their first-generation slash

pine programs, emphasizing the myriad of alternative

methodologies available to tree breeders. In the CFGRP,

the progeny testing and breeding phases (functions 1 and

3 of genetic tests mentioned above) were separated in time

by 10 or so years and employed a different set of parents.

Shortly after the original 1,200 selections were made, it

was recognized that it was impossible to rank these selections for their genetic quality, since they were selected in

hundreds of different natural stands growing in 5 states.

Therefore, CFGRP members mounted a large program of

progeny testing with tests established from 1965-1980.

Open-pollinated (OP) seed was collected from each of the

grafted selections growing in seed orchards and kept

labeled by the clone (that is, selection) that produced the

seed. As seed from 20 to 100 selections became available,

these were planted into randomized, replicated field tests

located on members’ timberlands throughout the slash pine

native range. Altogether 350 separate field tests containing

more than 325,000 OP progeny from the 1,200 selections

were established (table 1). The performance of OP progeny

was used to rank the 1,200 selections, mainly for volume

growth and rust resistance (for example, a selection producing offspring that consistently grew well and were rust

resistant in several replications on each of several field

sites was judged as a top performer).

Table 3—Genetic gains from CFGRP slash pine seed orchards in

volume and rust resistancea

Years seed Rust

Type of seed planted Volume gain resistanceb

percent (R50)

Unimproved <1960 0.0 50

1.0 Generation

orchard unrogued 1965–1985 9.0 49

1.0 Generation

orchard rogued 1975–1995 14.0 41

1.5 Generation

orchard unrogued 1985–2005 18.0 35

Advanced-generation

orchard >2002 30 20

CFGRP = Cooperative Forest Genetics Research program.

a All gains are expressed relative to plantations established with unimproved

material as it existed before domestication began in 1950. Volume gain is in

percent above unimproved.

b Rust resistance is expressed in R50: the percentage of trees in a stand

that would be infected with rust when 50 percent would be infected in an

unimproved plantation (for example, R50 = 35 means that 35 percent of the

trees would be rust-infected in plantations that would have had 50 percent

infection if planted with unimproved material). All gain values are averages

of 10 or more seed orchards of different members, and gains of the

individual orchards vary markedly depending on clonal composition.
14

As soon as rankings became available from OP progeny

tests (beginning in 1970 for the earliest OP tests), CFGRP

members began to breed together top-ranking selections

through control pollination. The idea was to increase

genetic gain from the breeding efforts by eliminating poorperforming selections before breeding. The top 600 of the

1,200 original selections were combined 220 new infusions chosen as superior rust-free trees in high-hazard

stands (see below) to create a breeding population of 820

parents (table 1) that were bred together to create 2,700

full-sib families that were established in 225 field tests containing 200,000 full-sib, pedigreed offspring. These tests

were established from 1970 through 1985. The second

generation of slash pine tree improvement began in 1987

(table 1) with selection of superior trees from top families in

these selection tests.

In the WGFTIP, the plan initially adopted by the cooperative

was to include each of the 1,000 first-generation selections

in control-pollinated breeding where each selection would

be in at least four crosses with other selections and each

cross would be evaluated at three different locations for

growth and form. By the late 1970s, it became apparent from

analyzing the older test data that rust-related mortality was

so significant that the best predictor of volume at age 15 was

rust infection levels at age five. It also became apparent

that parents selected only for good growth and form were

frequently poor performers in the field when exposed to

fusiform rust infection. This led to two changes in the

WGFTIP breeding and progeny-testing programs. The first

was a change in the evaluation criteria in progeny tests.

The second was the adoption of a two-step screening

procedure.

Rust-related mortality was the most significant factor

causing changes in family ranks for volume production

between ages five and 15. Therefore, the evaluation

scheme was altered to use rust infection at age five as the

indirect selection criterion for final volume. In order to have

confidence that all families had been exposed to rust, only

those tests in which the average rust infection of the test or

that of the unimproved checklots exceeded 30 percent were

used. At later ages (10 and 15 years), much of the rustrelated mortality had already occurred, and both growth

rate and infection levels were deemed to be important in

determining final volume (Lowe and van Buijtenen 1991).

The second change in the first-generation progeny-testing

program involved the adoption of a two-step screening

procedure. This scheme combined greenhouse screening

for disease resistance followed by breeding and testing of

the most disease-resistant parents in field tests for growth

and yield (Lowe and van Buijtenen 1989). All 1,000 firstgeneration selections were first crossed with a polymix of

ten parents chosen because they lacked resistance in field

tests. Rust-susceptible parents were chosen in order to

ensure that any resistance apparent in the greenhouse

tests would originate from the female parent under evaluation (Byram and Lowe 1987). The WGFTIP eliminated

approximately half of its first generation breeding population on the basis of resistance screening at the USDA

Forest Service Resistance Screening Center. The 500

remaining selections were divided into groups of six to

nine parents that are being crossed in a modified halfdiallel scheme in which each parent is included in four

crosses. The current progeny test design consists of establishing each cross in three locations with each location

containing 50 replications of single-tree plots. Growth and

disease incidence are evaluated at five-year intervals.

These tests are used both to rank parents and as a source

for second-generation selections. To date, there have been

120 long-term first-generation progeny tests established to

evaluate 389 parents. Twenty-two of these parents are only

in open-pollinated tests, while 367 parents are evaluated

in control-pollinated tests containing 712 full-sib families.

WGFTIP anticipates that the last of the required first-generation progeny tests will be established in 2003.

Infusions

Some years after initial selections are made, many tree

improvement programs add new selections into the breeding population that were not part of the original selected

population. These infusions can be aimed specifically at

improving a single trait or at generally broadening the

genetic diversity existing in the program. The WGFTIP did

not make any infusions in the first-generation slash pine

program; however, the CFGRP doubled the size of the firstgeneration selected population by infusing 1,250 new

selections obtained through several different opportunities

(table 1): (1) 850 new selections were obtained to increase

rust resistance in the program by selecting phenotypicallysuperior trees that were free of disease in natural stands

that had 85 percent or more of the trees rust infected

(Goddard and others 1975); (2) 125 new selections were

made in central Florida in the counties near Orlando (the

southern part of the natural range of the northern variety of

slash pine) to broaden genetic diversity; (3) 115 new selections were made from diallels originally established by the

USDA Forest Service as part of their program for naval

stores production (that is, high yields of oleoresin); and

(4) 60 selections were added to increase pitch canker

resistance by selecting disease-free trees in natural stands

heavily infected with the pitch canker fungus (Fusarium

circinatum which was formerly F. subglutinans) (Rockwood

and Blakeslee 1988).

ADVANCED-GENERATION BREEDING OF

SLASH PINE

In both the CFGRP and WGFTIP, the goals of the advancedgeneration breeding programs of slash pine include: (1)

Achieving maximum short-term genetic gains in a few traits

of high economic importance, mainly volume growth and

rust resistance with less emphasis on stem form and wood

specific gravity; (2) Maintaining sufficient genetic diversity

in the breeding population to ensure near-optimal longterm genetic gains in the same or different traits as markets,

products, technologies and environments change in the

future; (3) Ensuring sufficient flexibility in program design

to facilitate change in direction and incorporation of new

technologies (such as biotechnologies); (4) Conserving

genetic diversity in the species; and (5) Conducting all of

these activities in a timely, cost-effective way that yields

appropriate economic returns.
15

Because of the similar goals of the two cooperative programs, there are many similarities in second-generation

breeding strategy and program implementation. There are

also some differences. Details of the two second-generation programs are summarized in the following sections,

but points of strong concurrence are: (1) Focus on improvement of two key traits, volume and rust resistance, with

lesser emphasis on a few others; (2) Large selected and

breeding populations designed to maintain sufficient levels

of genetic diversity; (3) Use of overlapping generations in

which excellent first-generation selections (called backward selections) are retained in the program and included

in the selected population with forward selections of the

top offspring from first-generation selections; (4) Reliance

on a strategy aimed at improving the overall mean general

combining ability (GCA) of the breeding population (which

implies genetic testing to rank selections); (5) Subdivision

of the breeding population into smaller sub-groups, called

sublines or breeding groups, to manage inbreeding; (6)

Use of complementary mating designs in which a polymix

design is used for progeny testing and full-sib designs are

employed to create a base population in which to make

third-generation selections; (7) High quality field tests

employing modern experimental designs in field sites that

are intensively managed to minimize competition and

maximize early expression of genetic differences in growth

and rust resistance; and (8) Reliance on wind-pollinated

seed orchards as the principle form of producing genetically-improved seed for operational reforestation.

Base Populations

The base population for the second generation consists

of all possible selections from both the original first-generation selections that could be retained in the program

(backward selections) and progeny from breeding of those

selections growing in genetic tests. When the secondgeneration CFGRP program began in 1987 (table 1), the

base population consisted of all of the following materials

that could have been selected: (1) The original 1,200 firstgeneration selections; (2) 1,250 infusions that had been

accumulated during implementation of the first-generation

program and either had to be utilized or discarded; and

(3) 200,000 progeny from 2,700 full-sib families growing

in 225 field tests, all of which were available as potential

forward selections. The base population for the WGFTIP

second-generation program will include the approximately

500 first-generation parents and 168,000 progeny of those

parents growing in first-generation genetic tests. Secondgeneration selections will be identified on the basis of rust

resistance as progeny tests reach age 5 and these same

tests will be screened again at age 10 on the basis of

volume growth and rust resistance. The bulk of the tests

will be screened during the next ten years.

For two reasons, the advanced-generation base populations for the two cooperatives will begin to diverge as the

programs mature. First, each program started with a slightly

different founder population, because different samples

from the slash pine species were drawn for the first generation. Second, the populations will diverge as each

program develops different land races as a result of testing

in different environments and from selecting for slightly

different traits to meet the specific requirements of their

respective breeding zones. This will be a very slow process

as many similarities exist in testing and selection criteria of

the two programs and many generations of breeding and

selection will be required to make large genetic differences

in the two base populations. Therefore, opportunities for the

two cooperatives to enrich each other’s breeding programs

through exchange of improved material will exist for the

foreseeable future.

Selected Population

In 1987, the CFGRP initiated the second-generation slash

pine program by predicting breeding values for volume and

rust resistance of all trees in the base population (that is, of

all backward and forward candidates for selection) using

an analytical methodology called Best Linear Prediction

(White and Hodge 1988). Next, using a growth and yield

model (Nance and others 1983), economic weights for

volume and rust resistance were estimated (Hodge and

others 1989). Due to the imprecision of these estimated

weights and the differences among CFGRP members in

the relative importance of volume and rust, 3 indices were

developed for each tree: IB, IG and IR where the first index

(B for both) weights volume and rust resistance according

to their economic weights, IG puts predominant weight on

growth performance and IR puts most emphasis on rust

resistance. Generally, if any candidate (backward or

forward) was excellent for any of the three indices, it was

included in the second-generation selected population.

This is similar to the multiple index selection strategy

(Namkoong 1976) and aims to develop breeds for growth,

rust and both within the CFGRP (Carson and others 1991).

To balance the objectives of maximizing genetic gain while

maintaining adequate genetic diversity, the maximum

number of relatives (full-sib, half-sib or parent-offspring)

allowed in the CFGRP selected population was set at 7,

and this number decreased with decreasing predicted

genetic value. So, more second-generation selections

were included from top families, in keeping with the principle of placing more emphasis on higher-ranking materials

(Lindgren 1986). In addition, untested infusions were also

included in the second-generation selected population,

and many of these were infusions for rust resistance from

the first generation (table 1) that had not been tested or

utilized.

In summary, the CFGRP second-generation breeding population for slash pine was formed in 1987, and contained a

total of 933 total selections with the following composition

(White and others 1993): (1) 395 backward selections of

the very best first-generation selections; (2) 318 top forward

selections from the 225 field tests containing 200,000 trees

from 2,700 full-sib families; and (3) 220 infusions from the

first-generation. With a census number of N=933 total selections, there were 850 unrelated individuals that contributed

genes to the selected population and the population had an

inbreeding-effective population size of Ne

=625 (which is lower

than 933 due to relatedness, Falconer and Mackay 1996).

The genetic gain for this genetically-diverse population is

approximately 20 percent for volume and an R50=35 meaning 35 percent rust-infected trees in stands where unimproved material would have 50 percent of the trees infected.

Subsequent to 1987, 30 or so new second-generation
16

selections were added to bring the total to 965 and 85 new

infusions were added to take advantage of special opportunities (table 1).

The WGFTIP program currently has 166 second-generation

selections. It is anticipated that an additional 300 secondgeneration selections (forward selections) and approximately 90 proven first generation parents (backwards

selections) will be added to this total. The WGFTIP secondgeneration population will then be approximately 550.

Second-generation selections will be identified based on

mid-parent values for rust resistance (age 5) and a combination of volume and rust resistance (ages 10 and older).

Data summarization procedures for estimating these breeding values were reported by Lowe and van Buijtenen (1991).

Propagation Populations: Clonal Seed Orchards

In the second-generation, members of both the CFGRP

and WGFTIP cooperatives are relying almost exclusively

on open-pollinated clonal seed orchards to produce genetically-improved seed for reforestation. Control mass pollination (CMP), an alternative to seed orchards in which top

parents are crossed together on an operational scale, is

currently being used on a limited basis to capture additional

genetic gain in the operational plantations by planting fullsib families (Bridgwater and others 1998), but plantations

established through CMP account for less than 2 percent

of current annual reforestation in the southern USA.2 Operational planting of tested clones, produced either through

tissue culture or rooted cuttings, is another alternative to

seed orchards that is being explored by some companies.

However, to date clonal forestry is still in the development

stage. It is likely that operational deployment in the future

will include all three of these options (open-pollinated seed

orchards, CMP, and clonal forestry), but through 2010, the

large majority of plantations will be established from seed

orchard seed.

The designs and compositions of the clonal seed orchards

vary between the 2 cooperatives and are described below;

however, in both cooperatives a major change has occurred

in how seed is collected and deployed from those orchards.

In the 1970s and 1980s, most companies collected bulk

seed from their orchards and, therefore, established operational plantations that were mixtures of many families.

Currently, it is much more common to collect seed in one

of two ways: (1) By groups of clones (for example, some

organizations divide clones in the orchard into three groups,

such as top growers, rust resistant and other, and collect

seed according to this grouping); or (2) By clone (so if there

are 20 clones in an orchard there are 20 bags of seed and

each bag contains the OP family seed of a given mothertree clone). Both options increase genetic gain in operational plantations in 2 ways. First, seed is not collected from

less-desirable clones in an orchard, and second, seed is

deployed to sites for which it is most suited (such as rust

resistant material to high hazard sites). With the second

option, operational plantations are established with single

OP families (that is, all trees in a plantation have a common

female parent). Approximately half of all slash pine plantations are now established with single OP families and a

given company might deploy from 2 to nearly 25 different

families (see footnote 2).

In terms of the details of advanced-generation slash pine

seed orchards, most CFGRP members established orchards

shortly after 1987 when the second-generation selected

population was formed. They employed a systematic design

(Hodge and White 1993) in which 40 or so clones were

grafted in the same order in each block of the orchard.

Approximately half of the clones are backward, tested

selections and half are forward, untested progeny. Thus,

there can be parents and offspring in the same orchard.

When data are available from second-generation genetic

tests, the poorer clones can be rogued from orchard leaving a mix of unrelated forward and backward selections.

CFGRP members currently manage about 600 acres of

these second-generation clonal seed orchards, and the

genetic gains are expected to be 30 percent for volume

and R50=20 (table 3).

In the WGFTIP program, the second-generation clonal

seed orchards are designed as advancing-front orchards

where blocks are established on a periodic schedule that

allows new material to be incorporated from the breeding

program as it becomes available. Older blocks can also be

removed from management as better material becomes

available. In general, blocks for these advanced-generation orchards are established on a five-year cycle with the

best 20 clones currently available. This strategy was

adopted because different member’s programs are at

different stages and as a result, advances in the breeding

program occur annually rather than in evenly-timed

generational intervals. The WGFTIP cooperative currently

has 140 ac (55 ha) of advanced-generation orchards

under management.

Breeding and Progeny Testing

All advanced-generation breeding programs must cope

with the fact that the number of relatives increases in

closed populations through selection and breeding. This

can have dire consequences in outbred species, such as

pines, because matings among relatives frequently reduce

family performance (called inbreeding depression) and

confound the ability to accurately predict parental breeding

values if families being tested suffer from different levels of

inbreeding. The WGFTIP and CFGRP have adopted very

similar strategies to deal with these problems. Namely,

both breeding populations have been sib-divided into

smaller subsets, called breeding groups or sublines, such

that all relatives are assigned to and managed within the

same breeding group (van Buijtenen 1976, Burdon and

others 1977, van Buijtenen and Lowe 1979). This allows

inbreeding to be concentrated in the breeding population

by making only crosses within breeding groups to produce

the next generation. At the same time, this ensures that

unrelated individuals (from different breeding groups) will

always be available to establish the propagation population. For example, the best selection from each breeding

group could be grafted into a clonal seed orchard and

2 McKeand, S.E.; Mullin, T.J.; Byram, T.D.; White, T.L. Deployment

of genetically-improved loblolly and slash pine in the Southern

U.S. Manuscript in preparation.
17

since all breeding groups are unrelated to each other, the

seed from the seed orchard would be completed

outcrossed.

Another important commonality between the 2 cooperatives is the use of complementary mating and field designs.

These schemes use one set of crosses and field designs to

rank parents and another set of crosses and field designs

to produce the base population from which third-generation

forward selections will be made. To rank parents, selections

are being bred with a pollen mix and the polymix families

are being planted in well-replicated field tests planted in

single-tree plots. The second type of design makes controlpollinated crosses among the selections and the full-sib

families are then planted in essentially unreplicated block

plots of 50 to 100 trees per family. These full-sib families

are ranked for their predicted performance based on the

parental breeding values obtained from polymix tests.

Selections for the next cycle of breeding will then be made

from within the block plots.

In the CFGRP, the breeding population consisting of 1,050

selections (table 1) was divided into 24 breeding groups

with each group containing approximately 44 selections.

All selections were grafted into clone banks on members’

timberlands in 1988 and 1989, and members began breeding as soon as the grafts began to flower. For the polymix

breeding, the CFGRP decided not to re-test backward

selections that already had been adequately tested in firstgeneration tests. In addition, many of the 220 infusions

were not included in the polymix testing. The first series of

polymix tests contained 138 PM families planted in 1998

on 8 sites with 20 replications per site. The second polymix

series was planted in 2001 with 177 PM families on 8 sites

with 20 replications. No other polymix testing is planned for

the second generation meaning that 315 (138+177) of the

1,050 selections will be ranked in these tests. In the second

part of the complementary designs, members have made

1,500 full-sib families using a flexible crossing design that

makes more crosses among top selections within each

breeding group and crosses the lowest ranking selections

only once (White and others 1993). These crosses are

being planted in selection blocks of 50 to 100 trees as

crosses become available from 1995 through 2003. In

total, more than 100,000 pedigreed trees will be available

in these selection plots to begin making third-generation

selections in 2003.

The WGFTIP advanced-generation breeding population has

been divided into 35 breeding groups of approximately 18

to 25 individuals. The complementary mating scheme uses

polymix seedlings planted at 3 locations, each with 50

single-tree plot replications, to rank parents. Block plots of

control-pedigree crosses among members from the same

breeding groups are also being established. Breeding and

testing for the second generation is just beginning within

the WGFTIP as first-generation testing was drawn out to

allow screening at the RSC. Currently, there are 3 polymix

tests established to evaluate 37 second-generation selections. Three of the six slash pine members are currently

producing crosses for the control-pollinated selection

population.

Genetic Gains and Genetic Diversity

Genetic diversity and gain are conflicting objectives for all

tree improvement programs. In particular, it is impossible to

make gains without reducing genetic diversity and genetic

diversity decreases in all closed breeding populations

during the course of many cycles of recurrent selection. In

the current slash pine breeding population of both cooperatives, high levels of genetic diversity are being actively

maintained by managing extremely large populations (500

to 1,000 selections) and by limiting the number of related

selections. Since both programs are only in the second

generation of breeding and both are improving only a few

key traits, diversity levels have changed little in the breeding populations compared to the natural species. These

breeding populations are large enough to sustain excellent genetic gains for many generations of breeding and

contain sufficient levels of genetic diversity to provide

considerable flexibility to changing climates, markets and

technologies.

Genetic gain and diversity are also important in operational

plantations. Most organizations want to maximize genetic

gain in operational plantations and accomplish this by

using only the best material available each generation.

For example, a clonal seed orchard might contain the top

20 out of nearly 1,000 selections available in any generation, and the organization might chose to plant single OP

families collected from that orchard. Most organizations are

willing to take more risk in a plantation that exists for a

single rotation compared with a breeding population that

must sustain a program for many generations of improvement. Still, it is important to quantify the gains and risk

associated with different options for operational deployment of genetically-improved material.

Genetic gains from different types of CFGRP seed orchards

are shown in table 3. It is clear that steady gains have been

made throughout the years as breeding technologies, data

analysis methods and genetic testing have advanced. For

the CFGRP, seed being planted from advanced-generation

seed orchards is expected to have volume gains of 30 percent above unimproved material when planted on low

hazard sites for fusiform rust. These yield gains will be

enhanced on high hazard sites since the average orchard

contains clones with mean R50=20 (so, seedlings from

these orchards are expected to have 20 percent of the

trees infected in stands that would be 50 percent infected

were unimproved seedlings planted).

As mentioned earlier, many organizations are now planting

single OP families on portions of their timberlands to capture maximum genetic gains. Further, some organizations

are piloting or developing programs to deploy single fullsib families or single tested clones to increase genetic gains

still further in operational plantations. Since each of these

options decreases genetic diversity to increase genetic

gain, it is important to analyze the implications of these

alternatives: bulk mixtures of seed from seed orchards,

single OP families from seed orchards, single full-sib family

from unrelated parents and single, non-inbred clone.

McKeand and others2 recently approached this issue

through a survey of all major organizations in the south to

see if any plantation failures had been reported. First, 31
18

state and private companies returned the surveys (100

percent of all the members in the 3 tree improvement

cooperatives in the southern USA) and these companies

are directly or indirectly responsible for at least 90 percent

of the annual reforestation southwide. None of these

organizations had experienced in unexpected environmental or pest problems in plantations established with

single OP families. The only problem mentioned was that

of a family being deployed that had not been adequately

tested for cold or drought tolerance, but this was extremely

rare. Since clonal plantations have not been planted on a

wide scale, experience is limited.

Unfortunately, there is never any perfect way to assess risk

(for example, how much home, car and life insurance is

enough?). Extremely diverse populations of American

Chestnut and American Elm were decimated by introduced

fungal pathogens while Chardonnay grapes, which have

very little if any genetic diversity, have been grown worldwide for over 400 years. Still, it is clear both theoretically

and empirically that single OP families retain the large

portion of genetic diversity in the species (75 percent of the

additive genetic variance and 100 percent of the dominance

genetic variance) and have been used safely for many

years. As organizations employ clonal forestry, genetic

diversity of the deployment population will decrease.

Deployment strategies will need to balance the need to

maintain genetic diversity against the desire for maximizing

genetic gain in determining the number of clones to plant

and their arrangement across the landscape.

ACKNOWLEDGMENTS

The authors thank the members of the Cooperative Forest

Genetics Research Program and the Western Gulf Forest

Tree Improvement Program who have supported tree

improvement of slash pine for a half century. This publication was approved by the Florida Agricultural Experiment

Station as Journal Series No. R-10442.

LITERATURE CITED

Anderson, R.L.; Powers, H.R., Jr. 1985. The Resistance Screening

Center - screening for disease as a service for tree improvement programs. In: Barrows-Broaddus, J. and Powers, Jr., H.R.

eds. Rusts of Hard Pines IUFRO Working Party Conference:

proceedings. University of Georgia. Athens, GA. 59-63.

Anderson, R.L.; Young, C.H.; Triplett, J.D. 1983. Resistance

screening center procedures manual: a step-by-step guide

used in operational screening of southern pines to fusiform rust.

Forest Pest Management Report 83-1-18. U.S. Department of

Agriculture, Forest Service. 55 p.

Bridgwater, F.E. 1992. Mating designs. In: L. Fins, S. T. Friedman,

and J. V. Brotschol, eds. Handbook of Quantitative Forest

Genetics. Boston, MA. Kluwer Academic Publishing. 69-95.

Bridgwater, F.E.; Bramlett, D.L.; Byram, T.D.; Lowe, W.J. 1998.

Controlled mass pollination in loblolly pine to increase genetic

gains. Forest Chronicles 74: 185-189.

Briggs, F.N.; Knowles, P. 1967. Introduction to plant breeding.

Reinhold Publishing Corporation. 426 p.

Burdon, R.D.; Shelbourne, C.J.A.; Wilcox, M.D. 1977. Advanced

selection strategies. In: Third World Conference on Forest Tree

Breeding: proceedings. March 21-26. Canberra, Australia.

1133-1147.

Byram, T.D.; Lowe, W.J.; McKinley, C.R. 1987. Polymix crosses

for rust resistance screening. In: 19th Southern Forest Tree

Improvement Conference: proceedings. June 16-18. College

Station, TX. 39-44.

Carson, M.J.; Burdon, R.D.; Carson, S.D. [and others]. 1990.

Realizing genetic gains in production forests. In: 11th RWG1

(Forest Genetics) Meeting: proceedings. Coonawarra, SA.

170-173.

Dorman, K.W. 1976. The genetics and breeding of southern pines.

Handbook No. 471. U.S. Department of Agriculture, Forest

Service. Washington, DC. 407 p.

Falconer, D.S.; Mackay, T.F.C. 1996. Introduction to quantitative

genetics. Essex, England. Longman Press. 464 p.

Goddard, R.E.; Schmidt, R.A.; Vande Linde, F. 1975. Effect of differential selection pressure on fusiform rust resistance in phenotypic selections of slash pine. Phytopathology 65: 336-338.

Hodge, G.R.; White, T.L. 1993. Advanced-generation windpollinated seed orchard design. New Forests 7: 213-236.

Hodge, G.R.; White, T.L.; De Souza, S.M.; Powell, G.L. 1989.

Predicted genetic gains from one generation of slash pine tree

improvement. Southern Journal of Applied Forestry 13: 51-56.

Li, B.; McKeand, S.E.; Weir, R.J. 1999. Tree improvement and

sustainable forestry - impact of two cycles of loblolly pine

breeding in the U.S.A. Forest Genetics 6: 229-234.

Lindgren, D. 1986. How should breeders respond to breeding

values? In: IUFRO Conference on Breeding Theory, Progeny

Testing and Seed Orchards: proceedings. October 13-17.

Williamsburg, VA. 361-372.

Lowe, W.J.; van Buijtenen, J.P. 1989. Early testing procedures

applied to tree improvement programs. In: 20th Southern Forest

Tree Improvement Conference: proceedings. June 26-30.

Charleston, SC. 250-258.

Lowe, W.J.; van Buijtenen, J.P. 1991. Progeny test data summarization procedures in the Western Gulf Tree Improvement

Program. In: 21st Southern Forest Tree Improvement

Conference: proceedings. June 17-20, Knoxville, TN. 303-310.

McKeand, S.E.; Mullin, T.J.; Byram, T.D.; White, T.L. 2003. Deployment of genetically-improved loblolly and slash pines in the

Southern US. Journal of Forestry (In preparation).

McKinley, C.R. 1983. Objectives of progeny tests. In: Progeny

Testing of Forest Trees. Southern Cooperative Series Bulletin

275. Texas A & M University, College Station, TX. 2-13.

Namkoong, G. 1976. A multiple-index selection strategy. Silvae

Genetica 25: 199-201.

Namkoong, G.; Kang, H.C.; Brouard, J.S. 1988. Tree breeding:

principles and strategies. New York, NY. Springer-Verlag

Publishing. 180 p.

Nance, W.L.; Froelich, R.C.; Dell, T.R.; Shoulders, E. 1983. A

growth and yield model for unthinned slash pine plantations

infected with fusiform rust. In: 2nd Biennial Southern Silviculture

Research Conference. November 4-6. Atlanta, GA. 275-282.

Rockwood, D.L.; Blakeslee, G.M. 1988. Genetic strategies for

reducing pitch canker incidence in slash pine. Southern Journal

of Applied Forestry. 12: 28-32.

Shelbourne, C.J.A. 1969. Tree breeding methods. Forest Research

Institute Technical Paper 55. New Zealand Forest Service.

Wellington, NZ. 4 p.

Talbert, J.T.; Weir, R.J.; Arnold, R.D. 1985. Costs and benefits of a

mature first generation loblolly pine tree improvement program.

Journal of Forestry. 83: 162-165.
19

van Buijtenen, J.P. 1976. Mating designs. In: IUFRO Joint Meeting

on Advanced Generation Breeding: proceedings. June 14-18.

Bordeaux, France. 11-27.

van Buijtenen, J.P.; Bridgwater, F. 1986. Mating and genetic test

designs. In: Advanced Generation Breeding of Forest Trees.

Southern Cooperative Series Bulletin 309. Louisiana Agricultural

Experiment Station. Baton Rouge, LA. 5-10.

van Buijtenen, J.P.; Lowe, J. 1979. The use of breeding groups in

advanced generation breeding. In: 15th Southern Forest Tree

Improvement Conference: proceedings. June 19-21. Mississippi

State, MS. 59-65.

White, T.; Flinchum, M.; Rockwood, D. [and others]. 1986. 28th

progress report, Cooperative Forest Genetics Research

Program. University of Florida. Gainesville, FL. 35 p.

White, T.L. 1987. A conceptual framework for tree improvement

programs. New Forests 4: 325-342.

White, T.L.; Hodge, G.R. 1988. Best linear prediction of breeding

values in a forest tree improvement program. Theoretical

Applied Genetics 76: 719-727.

White, T.L.; Hodge, G.R.; Powell, G.L. 1993. Advanced-generation

breeding strategy for slash pine in the Southeastern United

States. Silvae Genetica 42: 359-371.

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

York, NY. John Wiley and Sons. 505 p.
20

INTRODUCTION

Major changes have occurred since the last Slash Pine

Symposium held in 1981, including changes in industry,

new silviculture options, long-term research data, and new

opportunities for landowners to profit from products such

as pine straw. Forest industry consolidation has had a major

impact on the companies that have historically planted

slash pine in Georgia and Florida, where about 80 percent

of the slash pine timberland is located (Barnett and

Sheffield, 2004). At least ten companies actively planted

slash pine in 1981. Due to consolidation and changes in

management strategies, only three to four companies

actively plant slash pine in 2002. Slash pine remains

popular with non-industrial private landowners.

SLASH PINE PLANTING SITES

Slash pine is largely native to south Georgia and north

Florida, but was planted extensively in central Georgia

and many other areas outside its original range in 1981.

A number of companies planted slash pine on 90 to 100

percent of their reforestation area. In 2002, slash pine is

planted mostly within its original range, and much less is

planted in central Georgia and other areas outside the

natural range. Forest industry now regenerates using a

higher proportion of loblolly than slash, even within the

primary natural range of slash pine (Shiver and others

2000). This shift of industry to loblolly pine on typical slash

pine sites may be related to the almost universal use of

bedding and other intensive management practices on

these sites. Outcalt (1984) has shown that loblolly pine can

perform as well or better than slash pine when grown on

poorly and very poorly drained sites that are bedded.

SLASH PINE STANDS HAVE CHANGED

Existing slash pine stands were a mix of plantations and

natural stands in 1981, and rotation ages were commonly

over 30 years. Today, most slash stands are plantation

originated, and rotation ages on industrial land are often

close to 20 years. Small private landowners are more likely

to use longer rotations in order to obtain additional returns

from selling poles or pilings or harvesting pine straw. These

facts are particularly relevant to establishment because the

residual cleanup and subsequent site preparation and

planting are affected by the conditions just after harvest,

being generally, easier following plantations.

EXPECTATIONS FROM ESTABLISHMENT

TECHNOLOGY

For forest industry, which needs a future supply of wood,

expectations for results from establishment practices have

changed a great deal. Whether we plant slash pine or

loblolly pine, the expectations have changed. In 1981, we

had what we believed were adequate nursery and planting

practices, and genetically improved trees were becoming

available in large quantities. However, our expectations,

and often our financial justifications were based primarily

on survival. In fact, a large amount of time and effort went

into monitoring and collecting data to track our survival

performance. In 2002, in the north Florida and south

Georgia area, we nearly take survival for granted, and we

have added early growth as a major expectation. With

improved establishment techniques, it is common to have

slash pine seedlings reach 2 to 3 feet in average height in

the first year (Vardaman 1989). This has become an

expected result from our establishment technology.

SEEDLING PRODUCTION

In 1981, seedlings were produced from a mix of seed

orchard seed and seed collected from natural stands.

Today, all seedlings are grown from seeds collected from

seed orchards, and many companies maintain orchard

seed identity through establishment by family. Nursery

seedbed densities have also changed. In the early 1980s,

nurseries usually grew crops at 28 to 32 seedlings per

square foot, but now 20 to 24 per square foot spacings are

more typical. This change is due to research that shows

better survival and early growth results from producing

larger seedlings in the nursery (South 1993).

PLANTING TECHNOLOGY

Planting techniques have changed little since the early

1980s, and a three-point hitch planter attached to a farm

tractor remains the normal technique on the flat land

typical of the slash pine range. Numbers of seedlings

planted per acre, however, continue to undergo change. In

1981, you could find planting densities from 400 to well

over 1000 trees per acre, occasionally reaching 1200 to

SLASH PINE ESTABLISHMENT:

WHAT HAS CHANGED—1981–2002?

Marshall Jacobson1

1 Marshall Jacobson, Manager, Forest Productivity, Plum Creek Timber Company, Watkinsville, GA 30677.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Practices for the establishment of slash pine in 1981 are compared to current practices in that portion of

slash pine range located in Georgia and Florida. About 80 percent of slash pine timberland is concentrated in these two

states. Establishment and management of slash is most intensively practiced in south Georgia and Florida.
21

1300. In 2002, we find a range of 450 to 850 stems per

acre covering most of the slash pine planting prescriptions

by forest industry. Other landowners, who have different

product objectives, may plant at a closer spacing with the

goal of obtaining early thinning and having a longer

rotation (Bailey 1986).

SITE PREPARATION TECHNOLOGY

Equipment

The type of site preparation equipment and the number of

options have changed significantly since the early 1980s.

During the 1980s, industry in particular, was still cutting a

large amount of natural stands, and this involved a high

degree of land clearing with large tracked equipment.

Some of this activity still exists, but in the North Florida and

Coastal Georgia region preparation is predominantly done

with rubber-tired equipment, some of which is designed

specifically for the site preparation activity. Due to these

changes, site preparation has become somewhat less

expensive, and more acres can be done in a given amount

of time.

Harvesting

Harvesting is very relevant to the establishment phase for

two reasons: we now cut mostly plantations, and utilization

has become much more efficient. In 1981, harvesting of

older stands, mostly of natural origin, left large amounts of

debris, both pine and hardwood, on the ground and standing resulting in high cleanup and site preparation costs. In

2002, we are harvesting many more plantations that are

predominantly pine with small hardwood component. Trees

that were once left standing are harvested, often leaving a

very clean site to begin site preparation.

Bedding Practices

Bedding has become a nearly universal treatment on most

coastal slash pine plantations in the Georgia and Florida

coastal flatwoods, and is often used in middle coastal plain

sites. In 1981, there were still a lot of plantations that were

simply burned and planted, and many that were disked.

Bedding raised the seedling root system above the high

water table on many poorly drained sites, and may reduce

woody-plant competition.

Silvicultural Herbicides

Twenty years ago, virtually all site preparation was done

by mechanical methods, which included a burn to reduce

debris remaining from the harvest. Herbicides for site

preparation were largely still in the research phase. Management in 2002 includes a larger mix of chemical and

mechanical site preparation as well as less use of fire.

Herbaceous weed control after planting is a very common

treatment, and in many cases, an industrial company may

treat all of its regenerated property to reduce competing

herbs and grasses during the first year, and sometimes the

second year. This will increase the likelihood of obtaining

the early height growth that is now expected with slash

pine (Shiver and others 1990).

Establishment Fertilization

Fertilizing slash pine at establishment in 1981 was restricted

to a few wet clay soils in the flatwoods. Fertilization was

predominantly with phosphorus utilizing ground rock phosphate or triple super phosphate. Since 1981, the fertilization of young stands has expanded a great deal. Sandy

spodosols as well as wet ultisols are now commonly fertilized (Shiver and others 1990). The predominant treatment

is now diammonium phosphate, and it is most often

combined with herbaceous weed control.

Use of Fire

Fire was a universal practice in 1981, being used both at

establishment and for prescribed fire during the rotation.

During the 1980s, concerns about smoke management

and safety has greatly reduced the use of fire. There is also

an increasing forestry-suburban interface in the slash pine

range (Butry and others 2002). These changes result in a

very small use of fire in reforestation of slash pine in 2002.

With good mechanical, and often, chemical site preparation, excellent plantations can be established with no fire.

Fire remains an important treatment in management

strategies used for natural regeneration, or where nonpine objective may be important.

WHY DID WE CHANGE?

When looked at collectively, one could make the argument

that everything has changed in slash pine regeneration.

Better research information, increased focus on environmental protection, and a focus on productivity have driven

change in this 20-year time span.

Research at University of Georgia, University of Florida,

and Auburn University have provided long-term information to prove beyond any doubt that we can increase per

acre yields, and do it within a disciplined economic

environment.

Increased requirements for environmental protection are in

place in 2002. Water quality protection, in particular, is a

much larger program in 2002. BMP updates and audits are

common, and compliance is very high in the South.

There is a much stronger focus on productivity in 2002, and

our regeneration practices are prescribed as a part of a

silviculture regime that should double or triple the per acre

yields that the South has seen historically.

CONCLUSIONS

Through the combined use of operational experience,

research from our universities, and an increased focus on

environmental issues, foresters have changed nearly every

aspect of slash pine regeneration in the past 20 years.

Slash pine remains an important commercial species in

the south, but is planted on fewer acres today than in 1981.

Planting today is largely within the natural range of the

species in Georgia and Florida.
22

LITERATURE CITED

Bailey, R.L. 1986. Rotation age and establishment density for

planted slash and loblolly pines. Southern Jour. Applied

Forestry 10: 162-168.

Barnett, J.P.; Sheffield, R.M. 2004. Slash pine: characteristics,

history, status, and trends. In: Dickens, E.D.; Barnett, J.P.;

Hubbard, W.G.; Jokela, E.J., eds. Slash pine: still growing and

growing! Proceedings of the slash pine symposium. Gen. Tech.

Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southern Research Station: 1-6.

Butry, David T.; Pye, John M.; Prestemon, Jeffrey P. 2002.

Prescribed fire in the interface: separating the people from the

trees. Outcalt, K.W., ed. Proceedings of the eleventh biennial

southern research conference. Gen. Tech. Rep. SRS-48.

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

Southern Research Station: 132-136.

Outcalt, K.W. 1984. Influence of bed height on the growth of slash

and loblolly pine on a Leon fine sand in northeast Florida.

Southern Jour. Applied Forestry 8: 29-31.

Shiver, Barry D.; Rheney, John W.; Hitch, Kenneth L. 2000. Loblolly pine outperforms slash pine in southeastern Georgia and

northern Florida. Southern Jour. Applied Forestry 24: 31-36.

Shiver, Barry D.; Rheney, John W.; Oppenheimer, Michael J. 1990.

Site-preparation methods and early cultural treatments affect

growth of flatwoods slash pine plantations. Southern Jour.

Applied Forestry 14: 183-188.

South, D.B. 1993. Rationale for growing southern pine seedlings at

low seedbed densities. New Forests 7: 63-92.

Vardaman, J.M. 1989. How to make money growing trees. New

York, NY: John Wiley & Sons Publishing. 296 p.
23

INTRODUCTION

The South leads the United States in production forestry,

but on a global scale, growth rates and yields of southern

pines are moderate. To meet the challenge of foreign

competition in markets, southern forests must be managed

more efficiently and productively. Research indicates

intensive and cost-effective management can potentially

increase growth 50 to 70 percent (Pienaar and Rheney

1996) or more (Stanturf and others 2003) when compared

to current conventional plantation management. Vegetation

management, specifically chemical site preparation, plus

woody shrub and herbaceous weed control, has an

important role in increased plantation productivity.

Within the South, slash pine (Pinus elliottii Engelm.) is a

major contributor to overall fiber production with more than

1.5 million seedlings planted annually (McKeand and

others 2003). Slash pine plantation establishment commonly includes either or both mechanical and chemical

site preparation. Post preparation sites are typically planted

with genetically improved seedlings, fertilized, and treated

for herbaceous weeds.

Slash pine responds to competition control (Swindel and

others 1988; Shiver and others 1990). Cognoscience of

species composition of the competitor community, growth

state of the competition, the efficacy of the treatment, and

duration of treatment effect contributes to wise treatment

selection and justification.

HARVESTING CONSIDERATIONS

The best competition control often begins with utilization of

both the crop and weed species on any given harvesting

site. Thus, harvesting intensity, subsequent site preparation

alternatives, revegetating plant community, and resultant

slash pine seedling performance are all related. Increasing

harvesting intensity can impact the method of post-harvest

preparation, the quality of post-harvest treatments, and

seedling response. However, harvesting intensity does not

reduce the need for good site preparation if aggressive

species occupy the site (Miller and Zhijuan 1994). For

example, hard-to-control competitors such as gallberry

(Ilex glabra (L) Gran), sawpalmetto (Serenoa repens

(Bartram) Small), vacciumium (Vaccimium spp.), waxmyrtle

(Myrica cerifera L), fetterbursh (Lyonia lucida (Lam)

K.Koch) staggerbush ((Lyonia ferruginea (Walter) Nutall),

sweetbay (Magnolia virginiana L.), and titi (Cyrilla racemiflora L.) commonly occupy poorly drained slash pine sites

and will not be controlled by harvesting activities. An

appropriate site preparation method addresses these

competitors, else they will persist into the rotation, complicate midrotation control, and reduce pine growth. The

importance of selecting the appropriate site preparation

treatment cannot be overstated. The growth gain associated with site preparation can be detected 20 years later

(Shiver and Harrison 2000).

HERBICIDE TREATMENTS

When applied prior to planting, Arsenal® AC, Chopper® EC,

Tordon® K, Garlon® 4, Accord® concentrate, Accord® SP,

Tordon® 101M, Escort® XP and Velpar® L may be used for

the control of labeled grasses, broadleaf weeds, vines and

brambles, and woody brush or trees on forest sites (BASF

2000, 2001; Dow AgroSciences 1999, 2001a-b, 2003;

DuPont 2003a, 2003c). Slash pine seedlings may exhibit

damage symptoms if planted too soon after certain chemical

site preparation treatments. Minimum intervals between

treatment and planting include: one month after Garlon® 4 at

less than 4 quarts per acre, two months after Garlon® 4 at 4

to 8 quarts per acre (Dow AgroSciences 2001a), and six

months after Tordon® K or Tordon® 101M (Dow AgroSciences

1999, 2003). If a Velpar® L treatment is to be followed with a

second mechanical, chemical, or burning treatment, the

second treatment should be delayed until competitors

exhibit two complete defoliations (DuPont 2003c). Efficacy

of specific herbicide stand-alone and tank mixtures are

presented in Minogue 1985, Shiver and others 1991, and

Minogue and Zutter 1986.

COMPETITION CONTROL IN SLASH PINE

(PINUS ELLIOTTII ENGELM.) PLANTATIONS

J.L. Yeiser and A.W. Ezell1

1 J.L. Yeiser, Professor, Arthur Temple College of Forestry, Stephen F. Austin State University, Nacogdoches, TX 75962; and A.W. Ezell,

Professor, Department of Forest Resources, Mississippi State University, Mississippi State, MS 39762-9681.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Harvesting intensity impacts the composition of the post-harvest recolonizing community and thereby

influences the method and quality of post-harvest site preparation and resultant slash pine (Pinus elliottii Engelm.)

response. Knowledge of the composition of the competitor community, growth state of the competition, and the efficacy

and duration of the treatment contributes to appropriate treatment selection. A variety of chemical or mechanical

treatments are available for pre-plant, post-plant or midrotation slash pine competitor control. Slash pine responds to

weed control, bedding, and fertilization with significant increases in basal area, and total and merchantable volume per

acre on many spodosols and nonspodosols. These treatments are the standard for contemporary slash pine plantation

management. Control of arborescent, woody shrub, and herbaceous species is a vital part of increased slash pine

plantation productivity.
24

REVEGETATION

Following site preparation, lower Coastal Plain flatwood

sites rapidly revegetate (Conde and others 1983a, 1983b,

1986; Miller and Zhijuan 1994). Relationships between

pre- and post-preparation communities have been noted

(Schultz and Wilhite 1974; Conde and others 1983a, 1983b,

1986; Miller and Zhijuan 1994). First, with minimum preparation, the most abundant pre-preparation species may

also be the most abundant post-preparation species (Conde

and others 1986). Second, woody shrubs and herbaceous

species differ in their response to site preparation treatments. Mechanical bedding disturbs roots and slows the

re-establishment of woody shrubs (Schultz 1976, Conde

and others 1986). Treatments with increased root disturbance provide slow recovery of woody shrubs and decrease

the resultant density of the shrubs (Schultz 1976; Conde

and others 1983a, 1983b, 1986; Miller and Zhijuan 1994).

Thus, shrub recovery following a double bed operation is

slower than following a single bed (Lauer and Zutter 2001).

In each example, herbs proliferate in the absence of woody

shrubs (Schultz 1976, Conde and others 1986, Miller and

Zhijuan 1994, Lauer and Zutter 2001). Third, post-mechanical recolonizing herb communities may shift from grass

towards forbs and blackberry (Miller and Zhijuan 1994).

Collectively, this information suggests that a pre-harvest

woody shrub and herb inspection can be used as an

indicator of the post-harvest competitor communities yet to

develop. Accordingly, the manager can prescribe a preparation method, timing, and sequence for woody shrub and

herb control based on the impact each has on subsequent

slash pine growth.

PRE-PLANT VEGETATION CONTROL

Herbicide Treatments

Pre-plant herbicide applications are less restrictive than

post-plant applications because they can accommodate a

broader array of rates and products. With proper herbicide

selection and application, pre-plant treatments can potentially provide broader control than post-plant treatments

(Lauer and Zutter 2001). However, timing of pre-plant

applications is critical for overall efficacy and the planting

restrictions associated with some herbicides.

Pre-plant, fall-applied (Oct and Nov) herbicide treatments

following early bedding improve control of woody shrubs

over that of a double bed and provide some first-year

herbaceous vegetation control (Lauer and Zutter 2001).

Examples of herbicide treatments and per acre rates successfully used as pre-plant fall applications with 20 gallons

per acre of total spray volumes are: Garlon® 4+Arsenal® AC+

Accord® concentrate+Timberland 90 (2qt+10oz+24oz+0.75

percent v/v), Garlon® 4+Arsenal® AC+Escort®+Kinetic

(1qt+8 oz+2 oz+0.1 percent v/v), Garlon® 4+Arsenal® AC+

Timberland 90 (2qt+8 oz+0.96 percent v/v), Garlon® 4+

Chopper®+Escort® (2qt+24oz+1oz) (Lauer and Zutter 2001).

The planting delay restrictions apply in this example (Dow

AgroSciences 1999; 2001a,b; 2003; DuPont 2003a,c). The

improved competition control from early bedding followed

by pre-plant, fall-applied herbicide versus early bedding

alone results in better pine growth (4.9 ft versus 4.0 ft after

two growing seasons) (Lauer and Zutter 2001).

Pre-plant treatments may be a manager’s last opportunity

to focus on specific weed problems prior to the midrotation

thinning. If not controlled early, difficult-to-control weeds may

increase in the early stand, reduce growth, and increase

the difficulty of midrotation control. To reduce total costs,

managers should combine pre-plant treatments with herbaceous weed control. Managers may select between a band

on beds and a broadcast application for the herbaceous

control treatments.

Mechanical Treatments

Slash pine is commonly managed on poorly drained sites,

thus, bedding is the most common mechanical treatment

used. Bedding is either single pass or double pass and

rarely conducted without the use of herbicides. Thus, what

becomes critical is the proper selection of herbicides and

application timing if the land manager is to optimize the

benefit of the bedding operation. On single bedded sites,

vegetation control can be enhanced with a pre-plant or

post-plant herbaceous treatment. Post-plant Arsenal®

AC+Oust® (4+2 ounces per acre) controls herbs and suppresses shrubs (Lauer and Zutter 2001). Escort® mixtures

(correctly timed) are appropriate if bracken fern, woody

vines, or blackberry are issues. Timing is critical for herbaceous treatments that are used also for the control or suppression of woody shrubs. Good herbicidal coverage of

foliage prior to the first flush of growth is essential. May or

June applications will likely provide poor control (Kline

and others 1994).

Shrub cover is reduced more with a double bed than with a

single bed treatment (Lauer and Zutter 2001). Controlled

shrubs are rapidly replaced by herbs. Double bedding

without post-plant herbaceous control may not result in

enhanced seedling performance because the short-term

impact of woody shrub and herbaceous vegetation on

seedling growth is similar (Lauer and Glover 1998).

POST-PLANT VEGETATION CONTROL

Post-plant vegetation management takes the form of either

herbaceous or woody release. Some treatments have the

capacity to control herbaceous and woody competitors.

Perhaps the best management strategy is to control the

woody competition prior to planting and the herbaceous

competition after planting. However, when one or both

types of control are needed, release operations in slash

pine increase growth. After five growing seasons, slash

pine total height responses average 2.8, 5.4, and 6.7 feet

due to first-year herbaceous control alone, shrub control

alone, and both herbaceous and shrub control, respectively (Lauer and Glover 1998). Good first-year shrub

control can eliminate the need for follow-up or annual

shrub control treatments (Lauer and Glover 1998, Zutter

and Miller 1998). Following initial control, woody shrubs

do not respond to herbaceous weed control (Lauer and

Glover 1998, Zutter and Miller 1998), remain suppressed

for years (Zutter and Miller 1998), and do not rapidly

recolonize from seed. Recolonization is of interest because

woody vegetation has the potential to limit growth in midrotation stands (Pienaar and others 1983, Oppenheimer

and others 1989). Therefore, managers should carefully

select site preparation treatments for shrub control and
25

long-term pine growth. Lack of shrub control at the onset of

the rotation (1) means reduced early pine growth, (2) allows

shrubs to increase throughout early stand development,

(3) complicates midrotation control, and (4) contributes to

reduced late rotation growth. Although Lauer and Glover

(1998) reported that pine response to shrub control was

large compared to herbaceous weed control, it does not

reduce the significant contribution of herbaceous weed

control to slash pine seedling performance (Lauer and

Glover 1998).

Herbaceous species will typically proliferate on prepared

sites, especially if the woody shrubs are controlled. Accordingly, managers commonly select a herbicide treatment for

herb control. When used properly, herbaceous release

significantly enhances slash pine growth. For example, in

a recent study, Ezell and Yeiser (2003) tested a number of

herbaceous release treatments and found that 13 oz. Oustar®

per ac provided the best overall competition control and

growth response over a two-year period on sites in Alabama

and Louisiana. Some trees were as much as nine feet tall

after two growing seasons. By comparison, Lauer and Zutter

(2001) noted that broad-spectrum control of herbs could be

difficult with Oustar®. Thus, the species composition on the

site is extremely important in determining final results.

Arsenal® AC, Oust® XP, Oustar®, Escort® XP, and Velpar®

(L or DF) are all used successfully to control herbaceous

competition in slash pine plantations (BASF 2000; DuPont

2002a-b, 2003a, c). Proper use of herbicides includes a

thorough familiarity with herbicide labels. Herbicide labels

should always be consulted for any restrictions to applications or site conditions. Examples of application restrictions

include the lack of an approved label for applying Arsenal®

AC+Oust® XP and Arsenal® AC+Escort® XP tank mixtures

over the top of slash pine seedlings. Interestingly, individual

products (Arsenal® AC, Oust® XP, and Escort® XP), and a

pre-mix blend of Oust® XP and Escort® XP (Oust® Extra) are

labeled for use in slash pine (BASF 2000; DuPont 2002a,

2003a; DuPont 2003b). Furthermore, site conditions, such

as water, can limit applications of Oust® XP, Escort® XP, or

Velpar®. For specific details on water restrictions, see

product labels (DuPont 2002a, 2003a-c).

VEGETATION CONTROL AND FERTILIZATION

Slash pine seedlings respond to bedding, vegetation control and fertilization (Colbert and others 1990, Shiver and

others 1990, Shiver and Harrison 2000). At age 8, complete

vegetation control in the flatwoods of southeast Georgia

and Florida provided the most consistent improvement in

slash performance (Shiver and others 1990). Bedding and

fertilization provided significant growth improvement regardless of soil group. At age 20, bedding provided a total

height gain of 1.50 feet. Total vegetation control increased

total height 5.35 feet and d.b.h 0.9 inches. Fertilization

enhanced total height 5.11 feet and d.b.h 0.6 inches.

Projections from this study show intensified silvicultural

practices can boost volume over conventional practices by

128 percent with a rate of return of 12 percent (Yin and

others 1998). Slash pine responses to vegetation control

and fertilization are additive (Baker 1973, Swindel and

others 1988) although synergistic responses have been

reported (Tiarks and Haywood 1981). In the latter case,

vegetation control (hoeing) and fertilization together

increased total biomass 347 percent, 207 percent more

than expected if the two treatments had been additive

(Tiarks and Haywood 1981). Although response to phosphorus commonly follows soon after application, it may not

significantly affect pine growth for many years (Tiarks 1983;

Haywood 1995).

MIDROTATION OPTIONS

Midrotation competition control treatments in slash pine

are increasing across the South. Research shows slash

pine responds very well to competition control in stands 10

to 15 years old. Oppenheimer and others (1989) controlled

the vegetation in 9 to 15 year old slash pine plantations for

10 years. In response, height, basal area, total volume,

and merchantable volume all increased significantly. While

this type of control may not be operationally feasible, the

results demonstrate that the species will respond to midrotation treatments.

Shiver (1994) examined the response of a slash pine plantation 14 years after it had received a midrotation competition control treatment. The plantations were 10 to 12 years

old at the time of treatment and were located on a range of

drainage categories. Overall, the worst results were generated on the poorly drained sites. However, on the sites

with adequate drainage, volume was increased by 0.25

cords per acre per year.

Zutter (1999) noted similar results on a well-drained site.

He studied slash pine plantations four years after an age

12 treatment of hexazinone at a rate of 1.4 lbs active ingredient per acre. Basal area, average d.b.h., and volume all

increased. In his study, merchantable volume increased

0.33 cords per acre per year after the treatment.

Overall, it appears that midrotation competition control can

be a cost-effective treatment in slash pine plantations.

Applications will generate best results on better-drained

sites and on those where the pre-treatment level of competition is restricting pine growth.

LITERATURE CITED

Baker, J.B. 1973. Intensive cultural practices increase growth

of juvenile slash pine in Florida sandhills. Forest Science 19:

197-202.

BASF. 2000. Arsenal applicators concentrate herbicide. BASF

Corporation. Research Triangle Park, NC. 6 p.

BASF. 2001. Chopper herbicide. BASF Corporation. Research

Triangle Park, NC 27709. 5 p.

Colbert, S.R.; Jokela, E.J.; Neary, D.G. 1990. Effects of annual

fertilization and sustained weed control on dry matter partitioning, leaf area, and growth efficiency of juvenile loblolly and

slash pine. Forest Science 36(4): 995-1014.

Conde, L.F.; Swindel, B.F.; Smith, J.E. 1983a. Plant species cover,

frequency, and biomass: early responses to clearcutting, chopping, and bedding in Pinus elliottii flatwoods. Forest Ecology and

Management 6: 307-317.

Conde, L.F.; Swindel, B.F.; Smith, J.E. 1983b. Plant species cover,

frequency, and biomass: Early responses to clearcutting, chopping, and bedding in Pinus elliottii flatwoods. Forest Ecology

and Management 6: 319-331.
26

Conde, L.F.; Swindel, B.F.; Smith, J.E. 1986. Five years of vegetation changes following conversion of pine flatwoods to Pinus

elliottii plantations. Forest Ecology and Management 15:

295-300.

Dow AgroSciences. 1999. Tordon K specialty herbicide. Dow

AgroSciences. Indianapolis, IN. 6 p.

Dow AgroSciences. 2001a. Accord Concentrate herbicide. Dow

AgroSciences. Indianapolis, IN. 14 p.

Dow AgroSciences. 2001b. Forestry Garlon 4 specialty herbicide.

Dow AgroSciences. Indianapolis, IN. 4 p.

Dow AgroSciences. 2003. Tordon 101 Mixture specialty herbicide.

Dow AgroSciences. Indianapolis, IN. 7 p.

DuPont. 2002a. DuPont Oust XP herbicide. E.I. du Pont de Nemours

and Company. Wilmington, DE. 11 p.

DuPont. 2002b. DuPont Oustar herbicide. E.I. du Pont de Nemours

and Company. Wilmington, DE. 7 p.

DuPont. 2003a. DuPont Escort XP herbicide. E.I. du Pont de

Nemours and Company. Wilmington, DE. 11 p.

DuPont. 2003b. DuPont Oust Extra herbicide. E.I. du Pont de

Nemours and Company. Wilmington, DE. 11 p.

DuPont. 2003c. DuPont Velpar L herbicide. E.I. du Pont de

Nemours and Company. Wilmington, DE. 19 p.

Ezell, A.W.; Yeiser, J.L. 2003. Preemergent vs. postemergent weed

control applications in slash pine plantations: second year

results. Proceedings Southern Weed Science Society 56:

124-125.

Haywood, J.D. 1995. Responses of young slash pine on poorly

drained to somewhat poorly drained silt loam soils to site

preparation and fertilization treatments. USDA Forest Service

Southern Forest Experiment Station Research Note SO-379.

5 p.

Kline, W.N.; Troth, J.L.; Shiver, B.D. 1994. Maximizing pine yields in

the southern flatwoods using Garlon herbicide. Down to Earth

49(2).

Lauer, D.K.; Glover, G.R. 1998. Early pine response to control of

herbaceous and shrub vegetation in the flatwoods. Southern

Journal of Applied Forestry 15(4): 201-208.

Lauer, D.K.; Zutter, B.R. 2001. Vegetation cover response and

second-year loblolly and slash pine response following bedding

and pre- and post-plant herbicide applications in Florida.

Southern Journal of Applied Forestry 25(2): 75-83.

McKeand, S.; Mulliin, T.; Byram, T.; White, T. 2003. Deployment of

genetically improved loblolly and slash pines. Southern Journal

of Applied Forestry 101(3): 32-37.

Miller, J.H.; Zhijuan, Qiu. 1994. Pine growth and plant community

response to chemical vs. mechanical site preparation for establishing loblolly and slash pine. In: Edwards, M.B., Ed. Proceedings

of the eighth biennial southern silvicultural research conference;

1994 November 1-4; Auburn, AL. General Technical Report

SRS-1, Ashville, NC; USDA Forest Service, Southern Forest

Experiment Station: 537-548.

Minogue, P.J. 1985. Second-year results of 1983 flatwoods site

preparation herbicide screening trials. Auburn University Silvicultural Herbicide Cooperative Research Note 85-13, Auburn

University, AL. 35 p.

Minogue, P.J.; Zutter, B.R. 1986. Second-year results of herbicide

screening trials for forest site preparation in the flatwoods.

Proceedings Southern Weed Science Society 39: 219.

Oppenheimer, M.J.; Shiver, B.D.; Rheney, J.W. 1989. Ten-year

growth response of midrotation slash pine plantations to control

of competing vegetation. Canadian Journal Forest Research

19: 329-334.

Pienaar, L.V.; Rheney, J.W. 1996. Potential productivity of intensively managed pine plantations. A Report to the Georgia

Consortium for Technological Competitiveness in Pup and

Paper Fiber Supply. 41 p.

Pienaar, L.V.; Rheney, J.W.; Shiver, B.D. 1983. Response to

control of competing vegetation in site-prepared slash pine

plantations. Southern Journal of Applied Forestry 7(1): 38-45.

Schultz, R.O.; Wilhite, L.P. 1974. Changes in a flatwoods site

following intensive preparation. Forest Science 20(3): 230-237.

Schultz, R.P. 1976. Environmental change after site preparation

and slash pine planting on a flatwoods site. USDA Forest

Service Research Paper SE-156. 20 p.

Shiver, B.D. 1994. Response and economics of midrotation

competition control in southern pine plantations. Proceedings

Southern Weed Science Society 47: 85-92.

Shiver, B.D.; Harrison, W.M. 2000. Slash pine site preparation

study: age 20 results. Plantation Management Research

Cooperative Technical Report 2000-4. pp 17.

Shiver, B.D.; Knowe, S.A.; Edwards, M.B.; Kline, W.N. 1991.

Comparison of herbicide treatments for controlling common

Coastal Plain flatwoods species. Southern Journal of Applied

Forestry 15(4): 187-193.

Shiver, B.D.; Rheney, J.W.; Oppenheimer, M.J. 1990. Site-preparation method and early cultural treatments affect growth of

flatwoods slash pine plantations. Southern Journal of Applied

Forestry 14(4): 183-188.

Stanturf, J.A.; Kellison, R.C.; Broerman, F.S.; Jones, S.B. 2003.

Productivity of southern pine plantations: where are we and

how did we get here? Journal of Forestry 101(3): 26-31.

Swindel, B.F.; Neary, D.G.; Comerford, N.B.; Blakeslee, G.M. 1988.

Fertilization and competition control accelerate early southern

pine growth on flatwoods. Southern Journal of Applied Forestry

12(2): 116-121.

Swindel, B.F.; Neary, D.G.; Comerford, N.B. [and others]. 1988.

Fertilization and competition control accelerate early southern

pine growth on flatwoods. Southern Journal of Applied Forestry

12(2): 116-121.

Tiarks, A.E. 1983. Effect of site preparation and fertilization on

slash pine growing on a good site. In: Jones, Earle P., Jr., ed.

Proceedings of the second biennial southern silvicultural

research conference; 1982 November 4-5; Atlanta, GA.

General Technical Report SE-24. Asheville, NC: USDA Forest

Service, Southeastern Forest Experiment Station: 34-39.

Tiarks, A.E.; Haywood, J.D. 1981. Response of newly established

slash pine to cultivation and fertilization. USDA Forest Service

Southern Forest Experiment Station Research Note RN-272.

4 p.

Yin, R.; Pienaar, L.V.; Aronow, M.E. 1998. The productivity and

profitability of fiber farming. Journal Forestry 11(11): 13-18.

Zutter, B.R. 1999. Response of a midrotation slash pine stand to

hexazinone. In: Haywood, James D. ed. Proceedings of the

tenth biennial southern silvicultural research conference; 1999

February 16-18; Shreveport, LA. General Technical Report

SRS-30. Asheville, NC: USDA Forest Service, Southern

Research Station: 446-448.

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

pine and competing vegetation to woody and herbaceous plant

control on a Georgia flatwoods site. Southern Journal of Applied

Forestry 22(2): 88-95.
27

INTRODUCTION

In the southeastern United States the dominant plantation

species are slash (Pinus elliottii Engelm.) and loblolly pine

(P. taeda L.), occupying approximately 13 and 30 million

acres, respectively (Sheffield and Knight 1982; Sheffield

and others 1983). The productivity of these even-aged,

single-species plantations can be influenced by a wide

spectrum of processes, including soil nutrient supply, genetics, and pest dynamics (fig. 1). Early site occupancy and

the development of a large and functioning leaf area represent important strategies for enhancing pine productivity,

and fertilization is one of the most cost-effective silvicultural treatments that forest landowners can apply to increase

growth rates and financial returns. As many forest soils

throughout the South tend to be infertile, fertilizers are

commonly applied to southern pine stands at-time-ofplanting and at mid-rotation (6 to 15 yr) to enhance and

sustain rapid tree growth. Recent statistics suggest that the

area of southern pine stands receiving fertilizer additions

in 2001 was about 1.3 million acres, down slightly from an

annual peak of 1.5 million acres in 1999 (NCSFNC 2002).

Levels of financial return associated with fertilizer applications depend on the magnitude and duration of growth

responses, costs associated with the fertilizer investment,

and product values. It is safe to say that the potential

productivity of most sites in the South is not being realized,

and that nutrient limitations are largely responsible.

Effective operational use of fertilizers requires diagnostic

systems, used individually or in combination, which accurately identify site nutrient status, needs, and potential

responsiveness. Soil classification, visual criteria, foliage

and soil testing, and growth and yield models can all aid

decision making. Each of the methods has operational

advantages and limitations because of differences in reliability, costs, and technical skills required for application

(see Pritchett and Comerford 1981; Jokela and others

1991a; Amateis and others 2000). Understanding stand

development dynamics and interactions among silvicultural treatments can also aid interpretations and the evaluation of treatment efficacy (Albaugh and others 1998;

Jokela and Martin 2000). This paper addresses issues of

soil fertility, growth-limiting nutrients, and fertilizer recommendations for slash and loblolly pine. Although many of

the principles discussed in this paper are applicable across

the South for these species, emphasis will be placed on

lower Coastal Plain sites of Florida and Georgia where

both slash and loblolly pine are commonly planted.

PRINCIPAL DIAGNOSTIC TOOLS

Soil Groups

As a diagnostic tool, soil descriptions are commonly used

for characterizing and classifying sites as potential candidates for forest fertilization. Soil groupings, based on easily

recognizable features, are used to identify sites where

available nutrient supplies are low, or where other site

factors (for example, moisture availability) influence growth.

CRIFF soil groups (A-H), defined using soil drainage,

texture and depth of the subsurface soil layers (Fisher and

Garbett 1980; see also description in Fox 2004; Jokela and

Long 2000) have found application in guiding operational

fertilization efforts in the South. Average stand responses to

fertilizers differ significantly among soil groups and, in some

cases, knowing the soil type (for example, CRIFF A) is

adequate for making fertilization decisions and estimating

NUTRIENT MANAGEMENT OF SOUTHERN PINES

Eric J. Jokela1

1 Eric J. Jokela, Professor of Silviculture and Forest Nutrition, School of Forest Resources and Conservation, University of Florida,

Gainesville, FL 32611.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Fertilization of slash (Pinus elliottii Engelm.) and loblolly pine (P. taeda L.) stands has increased dramatically

over the last two decades. As a cost effective silvicultural tool, fertilization has been successfully applied for increasing

forestland productivity. Effective operational use of fertilizers relies on a variety of diagnostic systems to identify site

nutrient status and potential responsiveness of candidate stands. General principles of forest nutrition, including guides

for implementing fertilization prescriptions, are discussed.

Figure 1—Processes and interactions that affect the

productivity of southern pine stands.

Processes Controlling/Limiting 

Stand Productivity

LAI

relationships

Light use efficiency

Dry matter

allocation

Nutrient demand

Pest Size-density

GENOTYPE

soil
28

response. In other cases, responses may vary significantly

within a soil group, indicating that current groupings oversimplify important factors influencing response, and that

additional information is necessary to increase prediction

accuracy. Soil maps have been prepared for many industrial lands and they have been broadly integrated and

applied to aid management decisions on a variety of issues

such as management intensity, fertilization rates, species

selection, site preparation, site quality (productivity classes),

and disease hazard ratings.

Foliar and Soil Testing

Chemical analyses of soils and foliage have been widely

used to evaluate the potential response of sites to fertilizer

treatments. These techniques are based on the assumption

that a stand will respond to an added nutrient when foliar

or soil concentrations fall below established critical levels.

The reliability of these techniques increase as the similarity between the candidate stands and reference stands

used to derive the relationships increase. Although critical

foliage nutrient concentrations have been published for

southern pines (table 1), they are not known with any

exactness, especially for elements other than N and P.

Hence, they are used principally as qualitative guides.

Variation in nutrient levels due to foliage age, sampling

position within the crown, sampling date and analytical

procedures can complicate interpretations, particularly

when values are near the critical levels. Standardized sampling (for example, dormant season, upper third of the crown,

fully elongated current-year needles) and analysis procedures are, therefore, essential for successful use of either

foliar or soil analysis. The critical level concept further

assumes that other elements are not limiting. Experience

has revealed that multiple nutrient deficiencies can exist

on some sites (see discussion below), and that evaluating

the balance of nutrients can improve diagnostic capabilities (Comerford and Fisher 1984; Adams and Allen 1985).

Visual Symptoms and Fertilizer Field Trials

The inherent appeal of using visual symptoms for guiding

fertilizer prescriptions reside in the potential simplicity of

making quick field diagnoses without the need for laboratory determinations. Foliar discoloration (chlorosis, necrosis), needle twisting, irregular branching patterns (e.g., lack

of apical dominance (fig. 2), premature needle fall, and dieback of young shoots are among the variety of symptoms

used to describe nutrient deficiencies in conifers (Stone

1968). However, as multiple nutrient deficiencies (for example, N, P, K, micronutrients) are possible in southern pine

stands, foliar analyses are often used in conjunction with

visual symptoms and soil groups to confirm initial interpretations. To be reliable, visual criteria must be calibrated

with stand response data.

Over the last decade, interpretations of what is considered

“normal growth” among land managers have also changed

dramatically. Prior to the implementation of intensive silvicultural growing systems, that include improved seedling

quality, proper planting techniques, superior genotypes,

site preparation, competition control and fertilization treatments, expectations were that 3-yr-old trees would average

Table 1—Foliar nutrient guidelines (minimum)

for southern pines

Nutrient Slash pine Loblolly pine

- - - - - - - - - percent - - - - - - - - -

N 1.0 1.2

P 0.09 0.12

K 0.25 – 0.30 0.30

Ca 0.08 – 0.12 0.15

Mg 0.06 0.08

S 0.08 0.10

- - - - - - parts per million - - - - - -

B .04 – 8 4 – 8

Zn .10 – 20 10 – 20

Cu 1.5 – 3 2 – 3

Mn .20 – 40 20 – 40

Fe .15 – 35 20 – 40

Source: Allen (1987); Pritchett and Comerford (1983);

Wells and others (1973).

Figure 2—Copper deficiency in young loblolly pine growing on a

sandy Spodosol in north central Florida. Note: deficiency is

expressed in lack of apical dominance of the terminal and leading

lateral shoots.
29

about five ft tall. Currently, when using a variety of the

treatment combinations listed above, it is not uncommon to

have stands average 10 to 12 ft tall during the same time

period. These well-established plantations also tend to be

quite uniform in height and character across the site.

Experimental field trials have undoubtedly been the most

reliable approach for estimating fertilizer responses. The

fertilizer rate-growth response relationships commonly

used today were largely developed through regional

experiments established by cooperative forest research

programs involving forest industry and southern universities (for example, University of Florida, North Carolina

State University). In addition, operational monitoring plots

have been used by many companies to corroborate

suspected nutrient deficiencies and to estimate growth

responses on a variety of soil types. These “in-house”

plots, that include replicated fertilized and non-fertilized

treatments (strips), are monitored over time, and their

results are incorporated into geospatially based maps.

Response Models

A variety of models (primarily for mid-rotation aged stands)

have been developed for slash and loblolly pine that relate

tree and stand level responses (for example, dominant

height, basal area, stand volume) to fertilization. Predictor

variables have included site index, soil drainage class, fertilizer treatment, stand age, number of surviving trees and

dominant height at time of treatment (Bailey and others

1989; Martin and others 1999; Amateis and others 2000).

Response models, based on site and stand conditions,

predict average growth responses for broad site types and

can be useful for identifying potentially responsive stands,

and selecting appropriate fertilizer treatments. Independent

field testing and calibration by users is still required, however, as empirical models may not accurately account for

changes in future conditions.

Process-based computer simulation models are also

becoming available to aid site-specific fertilizer decisions

by forest managers. The SSAND (Soil Supply and Nutrient

Demand) model, for example, was recently developed at

the University of Florida to diagnose nutrient limitations

and determine fertilization regimes necessary to achieve

preset stand production goals (Adegbidi and others 2002).

With this type of model, the user determines a desired level

of productivity. Simulations of soil nutrient supply, based on

input variables, are compared with the stand nutrient

demand estimates. If stand nutrient demand exceeds soil

supply, fertilization regimes can be tested to determine the

most efficient treatment for meeting production goals and

plant nutrient demands.

RATES OF FERTILIZER APPLICATION

Fertilizer recommendations for southern pine stands have

not been determined as precisely as those for agronomic

crops. Rapidly growing southern pine stands place high

nutrient demands on the soil, especially during the early

stages of canopy development. Yet, few estimates of uptake

exist for such stands, but these data are critical for quantifying plant nutrient demands and developing fertilizer

prescriptions based on soil nutrient supply. Recently,

Adegbidi and others (2003) reported that rapidly growing

(aboveground biomass ~16 tons per ac) 4-yr-old loblolly

pine stands (CRIFF C soils) had accumulated about 175

lbs N per ac and 20 lbs P per ac, with the crown (foliage,

branches) being the dominant pools (52 to 59 percent) for

these elements. About 23 percent of the N and 29 percent

of the P was accumulated in roots. Cation (K, Ca, Mg)

accumulations were also highest in the aboveground

components (~50 percent). Approximately 77 lbs per ac K,

65 lbs per ac Ca, and 25 lbs per ac Mg had accumulated in

the total tree biomass by age 4 yr. In contrast, Colbert

(1988) reported that aboveground nutrient accumulations

were considerably lower for extensively managed, slowgrowing (aboveground biomass ~ 1 ton per ac) loblolly

pine stands on similar soils. For example, aboveground

accumulations of N, P K, Ca, and Mg at age 4 yr averaged

about 9, 1, 3.5, 3, and 2 lbs per ac, respectively. These

results clearly indicate that rapidly growing stands place

correspondingly higher levels of demand on soil nutrient

pools and, in comparison to extensively managed stands,

will require more frequent fertilizer additions to sustain

high levels of production. Frequent removal of pine straw

from the site may also necessitate the need for more

frequent additions of fertilizers (Morris and others 1992).

When developing fertilizer prescriptions, practitioners must

be aware that past management practices will influence

both the timing and rates of future fertilizer treatments. In

addition, trees are generally inefficient in terms of fertilizer

recovery. For example, Fisher and Binkley (2000) suggested

that less than 25 percent of the fertilizers applied to forest

stands are taken up by trees, with about 25 percent being

immobilized in soil microbes and organic matter, and an

equally large but variable pool being lost through volatilization and leaching. Removal of understory vegetation

may improve nutrient retention by the trees and additional

research is required to determine if low application rates or

repeated applications substantially improve fertilizer

recovery by trees.

Described below are fertilizer recommendations commonly

used across a variety of soil types in the Coastal Plain of

Florida and Georgia. Treatment rates are presented for both

young and established (after crown closure) stands and it

is assumed that the stands have received effective understory competition control treatments at establishment. As

with any silvicultural treatment, local conditions may cause

results to deviate from those reported here. Therefore, the

recommendations listed below should be used as general

guides only. For example, as additional nutrient ramping

studies are completed with southern pines, the sequence

and amount of fertilizers required to sustain desired growth

rates may change. Also, variable timber markets will directly

affect the economic viability of different treatment regimes.

Phosphorus plus N, and P alone, are the nutrient elements

that tend to be the most widely applied to southern pine

stands. Application of N alone is not generally recommended

in young stands because it often stimulates competing

vegetation. In some cases, K and other macronutrients may

also limit growth once N and P demands have been met

(table 2). The fertilizer rate prescription ratio for southern

pines is approximated as 100:10:35 (N,P,K). Similarly, examples of micronutrient deficiencies have been documented
30

(for example, B, Cu, Mn, Zn) in southern pine stands, and

are often induced when intensive silvicultural practices

accelerate early stand growth. It should be noted that recommended fertilizer application rates for micronutrients are

not known with any exactness and care should be taken

to avoid possible toxicities in southern pine stands. For

example, elemental application rates of B should not

exceed about 1 lb per ac.

CRIFF A AND B SOILS

(Very Poorly to Somewhat Poorly Drained -

Bays and Wet Savannas)

These soils are typically found in nearly level depressions,

stream terraces, and broad wet flats. Excessive soil moisture and lack of available P commonly limit pine growth.

Without adequate P nutrition, the pines often are no more

than 40-45 feet in height after 25 years, and the stand leaf

area is very sparse and consists of short, yellowish needles.

Young Stands

Fertilization with P or a combination of P and N is recommended at planting and growth responses can be dramatic

on these soils. Yield differences of 2-3 fold have been

documented following fertilization. For example, a 25-yrold slash pine stand growing in the Panhandle of Florida

produced about 4500 ft3

 per ac of wood with fertilization

(50 lbs per ac P) compared to 2040 ft3 per ac without fertilizer additions (Jokela and others 1989). Delaying fertilizer

applications on such sites will cause significant growth

losses.

If these sites have never had a history of fertilizer applications, approximately 40 to 50 lbs per ac of elemental P and

40-50 lbs per ac of elemental N are recommended rates.

The superphosphates are the principal P fertilizers used

when only P is required (triple superphosphate (0-44-0) and

normal superphosphate (0-20-0). If a combination of N and

P is desired, diammonium phosphate - (DAP) (18-46-0)

represents an excellent fertilizer choice. An application

rate of 250 lbs per ac DAP would, for example, provide an

elemental equivalent of 45 lbs per ac N and 50 lbs per ac

P. If stands growing on these soils received P applications

late in the previous rotation, then 125-150 lbs per ac DAP

would be applied at establishment.

When used in conjunction with N + P fertilization, herbaceous weed control treatments can augment pine growth

responses on these soils. Results recently showed that

volume growth of 8-yr-old loblolly pine stands growing on

A group soils averaged 713 ft3 per ac when no fertilizer or

weed control treatments were applied (Jokela and others

2000). In contrast, volume was doubled (1430 ft3 per ac)

when herbaceous weed control was combined with 250

lbs per ac DAP. Volume growth for the fertilizer and herbaceous weed control treatments, when applied alone at

planting, averaged 1202 ft3 per ac and 803 ft3 per ac,

respectively. It is clear that on these soils weed control

alone did not elicit much growth response, presumably

because of the overarching limitations due to P deficiency.

Established Stands

Fertilizer requirements for older stands are based on the

same principles as young stands. However, it is often more

difficult to predict the need for fertilizers in older stands

because deep root penetration may allow absorption of

nutrients from subsoil horizons, even though surface

horizons are low in available nutrients. Surface layers of

organic debris (for example, pine needles) also serve as a

nutrient reservoir, and can release nutrients for the pines

as the material slowly decomposes (Polglase and others

1992). Deficiencies of N and P are most pronounced following crown closure. Decomposition processes generally

slow down and nutrient availability decreases because

they are immobilized in the stem, bark, branches, roots

and foliage of the pines and understory plants.

Fertilization with combinations of N and P are recommended

for closed canopy stands. The combined elemental treatment gives larger and more consistent responses than

either element applied alone. Application rates of approximately 150 - 200 lbs per ac elemental N and 25 lbs per ac

elemental P at about age 10 on A group soils and about 6-

8 years on the sandier textured B group soils will usually

result in growth responses averaging 50 ft3 per ac per yr or

more. Fertilizer responses normally last for about 6 - 8

years. Although N application rates above 200 lbs per ac

(with P) can result in higher levels of growth response, they

are not generally economically justifiable on most soils.

Common fertilizer sources would include DAP, superphosphates, and urea.

Table 2—Recommended fertilizer application rates (elemental – pounds per acre) for loblolly and slash

pine when diagnosed as limiting for growth

Species Stand phase N P K Ca, Mg, S, B, Cu, Mn, Fea

Loblolly At planting 40 – 50 25 – 50 50 – 80 As needed based on foliar analysis (table 1)

or other diagnostics

Canopy closure 175 – 200 25 – 50 50 – 80 As above

Slash At planting 40 – 50 25 – 50 50 – 80 As above

Canopy closure 150 – 200 25 – 50 50 – 80 As above

a Approximate application rates based on stand needs: 25 to 40 pounds Ca per acre, 25 pounds Mg per acre, 25 to 40

pounds S per acre, 0.5 to 1 pound B per acre, 3 to 5 pounds Cu per acre, 3 to 5 pounds Mn per acre, and 10 to 15 pounds

Fe per acre.

Source: Allen (1987), Jokela and others (1991), South and others (2003).
31

Evidence from six fertilizer trials suggested that land managers have flexibility in applying fertilizers either as a single

or split mid-rotation fertilizer treatments without impacting

the biological magnitudes of response or longevity (Jokela

and Stearns-Smith 1993). For example, if 200 lbs per ac N

and 25 lbs per ac P was the recommended treatment, it

could be applied at age 10 years as a single combined

treatment (DAP + urea). Alternatively, 125 lbs per ac DAP

(equivalent to 22.5 lbs per ac N + 25 lbs per ac P) could be

applied at age 10 years with a follow-up urea treatment

(178 lbs N per ac; 395 lbs per ac urea) within 2 years. The

split N treatment has the potential to provide economic

benefits because a significant portion of the capital costs of

fertilizer can be postponed for up to 2 years, and thereby

reduce the total carrying costs over the investment period.

It should be noted that mid-rotation fertilizer applications

that include urea are generally recommended for all soils

between January and May to avoid volatilization losses of

N. In addition, if the stand is being managed for sawtimber,

a second mid-rotation fertilizer application (150-200 lbs

per ac N + 25 lbs per ac P) would typically be prescribed

the year after thinning to sustain acceptable growth rates

until rotation age is achieved. The actual age for the thinning treatment will vary among sites, but commonly occurs

when merchantable height of the stand is > 40 ft.

CRIFF C AND D SOILS

(Very Poorly to Moderately Well Drained -

Flatwoods Spodosols)

The Flatwoods represent one of the most extensive groups

of forest soils in the Coastal Plain. The somewhat poorly to

moderately well drained C and D group soils (Spodosols)

developed in coarse textured sediments (acidic, sand to

loamy sand texture) low in native fertility. Nitrogen and P

fertilizer additions commonly elicit significant growth

response in both slash and loblolly pine stands.

Young Stands

Fertilizer and herbaceous weed control treatments applied

alone or in combination at time of planting can significantly

increase pine growth on C and D group soils. These soils

tend to be deficient in both N and P, although levels of K

and micronutrients (B, Mn, Cu and Zn) are also in marginal

supply. Broadcast applications of approximately 200 to 250

lbs per ac DAP (40 to 50 lbs per ac elemental N and 40 to

50 lbs per ac elemental P) represents the most common

treatment for these soils if the sites have not previously

received fertilizer additions. Pre-plant chemical site preparation or herbaceous weed control treatments applied in the

spring of the first growing season can also enhance the

probability and magnitude of growth responses derived

from fertilizer applications. Loblolly pine, because of higher

nutrient demands, has generally been more responsive

than slash pine to fertilizer and weed control treatment on

these soils. For example, 8th year volume response of loblolly pine on C and D group soils averaged 32 percent when

45 lbs per ac N + 50 lbs per ac P was applied at planting

(Jokela and others 2000). Growth responses to the combination treatment of fertilizer + herbaceous weed control

averaged 52 percent. Slash pine treatment responses were

generally smaller in magnitude and averaged 10 percent

for the combined treatment.

With the application of more intensive management systems, foresters must recognize that rapid growth rates can

result in induced deficiencies (dilution effects) of other

elements (for example, micronutrients) on these sandy

soils, and periodic monitoring is warranted to avoid subacute deficiencies (fig. 2). Subacute deficiencies of Mn, Cu,

B, and Zn on CRIFF B, C and D group soils appear to be

easily corrected from a single application of a needed

micronutrient at time of planting, and it may suffice for the

entire rotation. For example, slash pine responses to Mn

additions averaged 32 ft3 per ac per yr above the control

over 16 years (Jokela and others 1991). If deficiencies of K

and micronutrients are suspected, on the basis of soil or

foliar tests, a mixed fertilizer such as 10-10-10 + micronutrients should be applied at rates of 500 to 600 lbs per

ac rather than the DAP treatment. Custom blended fertilizers, that contain both macro- and micronutrients, are also

an option.

Established Stands

Older southern pine stands (post crown closure) growing

in the Flatwoods are commonly deficient in both N and P.

Typically, these sites are fertilized at about age 6 years with

150 lbs N per ac and 25 lbs P per ac. Growth responses

average approximately 55 ft3 per ac per yr when both N and

P are applied. Note that the application of N or P alone is

not recommended on these soils because growth responses

have been largest and most consistent to the combined N

+ P treatment. Fertilizer responses on these soils commonly

persist for 6-8 years. A second mid-rotation application of

N and P (200 N, 25 P per ac) may be applied at age 12-13

years to sustain growth through rotation (perhaps following

the first thinning). The most common fertilizer sources used

for this prescription are a combination of DAP and urea.

Where K is deficient, it should be included in the fertilizer

program at rates ranging from 50 to 80 lbs K per ac.

Common K fertilizer sources would include KCl (muriate of

potash), KSO4 or a mixed fertilizer material. A foliar test

should be used to confirm suspected deficiencies of these

elements, including micronutrients.

CRIFF E AND F SOILS

(Moderately Well to Well Drained - Uplands)

These Coastal Plain soils are found in upland areas and

range from relatively deep, moderately well-drained sands

to well-drained loamy sands and sandy clays. Many of the

existing stands planted on these soils were established on

abandoned farmlands, which have been seriously eroded.

Unless the site has been in recent agricultural production,

these soil groups tend to be naturally deficient in N and P.

Young Stands

These upland soils often receive combinations of mechanical tillage and chemical site preparation treatments. With

good initial weed control, pine stands would typically

receive N and P fertilization (100-150 N per ac, 25 P per ac)

at about age 5 years. In some cases, DAP (200 lbs per ac)

applications are made at establishment and the efficacy of

fertilizer additions are enhanced when combined with herbaceous weed control. For example, when compared to

untreated plots, 8th year loblolly pine volume on E group

soils averaged 33 percent more on plots receiving 45 lbs
32

per ac N + 50 lbs per ac P (DAP – 250 lbs per ac), and 53

percent more on plots that received the same fertilizer

treatment + herbaceous weed control (Jokela and others

2000).

Established Stands

Nitrogen and P tend to be the most limiting nutrients for

loblolly pine on upland sites, although K and micronutrient

deficiencies may also exist. Foliar analysis is recommended

to delineate deficient areas among older stands (post crown

closure). Where a deficiency is indicated, elemental application rates of 200 lbs N per ac and 25 lbs P per ac are

recommended, often at about age 12 to13 years (assuming

earlier treatment at age 5 to 6 years). On responsive sites,

especially those that have a well-developed, shallow,

clayey subsoil, volume gains due to fertilization can range

from 70 - 90 ft3 per ac per yr and persist for 6 to 8 years. A

second mid-rotation fertilizer treatment may be warranted

on sites being thinned and managed for sawtimber

production.

CRIFF G SOILS

(Excessively Drained - Sandhills)

Extensive areas of deep sands, with little soil profile development, occur in north Florida, Georgia and the Carolina

Sandhills. These soils often formed on former sand dunes

and beach ridges. Sand pine (Florida) and longleaf pine

are commonly planted on these soils. Management practices that conserve organic matter are recommended for

these soils. As water deficits and competition generally

limit pine productivity, intensive management that includes

fertilizer applications are not generally recommended for

these soils.

CRIFF H SOILS

(Very Poorly Drained - Depressions)

Soils of the H group are typically found in isolated, verypoorly drained depressions throughout the savannas and

flatwoods (for example, cypress ponds or strands, bottomlands along rivers). They contain high levels of organic

matter in the surface horizon, with little or no sand or clay

present. Excessive wetness and frequent flooding, due to

landscape position, limit their potential for intensive pine

plantation management and forest fertilization is rarely

recommended.

APPLICATION METHODS

The method of application (in other words, banding vs.

broadcast) does not appear to affect growth responses to

fertilization. Factors such as equipment availability, costs,

terrain, uniformity of spread, and timeliness of the operation should be considered when formulating a prescription.

Banding involves selective fertilizer placement, usually 3-4

ft wide over the recently planted row of trees. By comparison, broadcast methods spread fertilizers in swaths across

the entire stand. Tractor-mounted spreaders are suitable

for easily traversed areas, whereas rubber-tired skidders

equipped with fertilizer spreaders or aerial application systems (helicopter, fixed-wing) may be more effective on wet

or rough sites. Regardless of the application method, uniformity and rate control are important. Unequal distribution

of fertilizers may contribute to irregular growth patterns.

Therefore, care should be exercised in applying fertilizers,

particularly when micronutrient additions are made because

they are applied in only modest amounts across the site.

FERTILIZATION EFFECTS ON SITE AND STAND

PROPERTIES

Fertilizer additions can result in both short and relatively

long-term changes in site and stand properties. Several

long-term experiments have been established and maintained throughout the South, and they have been invaluable in understanding the effects of intensive management

on stand dynamics. Results from one such trial series

established on a CRIFF C group soil (Spodosols) in north

central Florida will be used to illustrate these effects for

both slash and loblolly pine. At this location, rotation-long

nutrient management (macro- and micronutrient additions)

was practiced, along with understory competition control

(Jokela and Martin 2000). In general, growth responses to

the various nutrient amelioration treatments were immediate, obvious and directly related to the intensity of management inputs (fig. 3). Stemwood growth responses were

driven by large increases (2x) in LAI. Without nutrient

additions or competition control, slash pine generally outperformed loblolly pine. The opposite was true, however,

under an intensive management regime.

Fertilizer induced growth responses were associated with

temporary increases in site quality and accelerated patterns of stand development. For example, when measured

at age 18 years, site index varied from 58 to 82 for loblolly

pine and from 72 to 84 for slash pine for the control (C;

bedded and planted) and combination fertilizer plus weed

control (FW) treatments, respectively. The levels of basal

area supported on this unthinned site were also directly

related to management intensity. The upper levels of basal

area, hence stand density, accrued on the FW treatment

was 193 ft2 per ac for loblolly pine compared to 82 ft2 per

ac for the control (C) treatment. In contrast, basal area

levels for slash pine were lower than loblolly pine on the

FW treatment (168 ft2 per ac), but comparatively higher on

the C treatment (97 ft2 per ac) (fig. 4). Culmination of stemwood mean annual increment for both species occurred at

age 13 years for the FW treatment, but had not reached a

maximum on the C treatment at age 18 yr. Hence, fertilization not only increased stand yields, but also shortened the

rotation length and increased stand value. These effects

were especially evident in the diameter distributions for

each treatment (fig. 5). Fertilization significantly improved

stand value by increasing the proportion of “grade” material

produced. For example, the C treatment had 17 percent of

the stems in 9-12 inch trees compared to 48 percent for the

FW treatment. It should be noted that density control treatments, such as thinning, will be required sooner in fertilized stands to avoid reductions in diameter increment due

to overstocking and selfthinning.

CONCLUSIONS

Large gains have been made in the South over the last two

decades in identifying responsive sites for forest fertilization.

Site classification is central to the wise use of fertilizers in

forest stands. The development of cost-efficient, biologically

sound fertilizer prescriptions will require integration of site,

stand, and economic considerations. To aid site-specific
33

fertilizer prescriptions in the future, additional technological

advances will be required to improve the accuracy of

diagnosing nutritional problems and accurately predicting

stand responses. For example, a better understanding of

soil nutrient supply (immobilization, retranslocation, mineralization) in relation to stand nutrient demand would aid

both the timing and quantity of fertilizer applications necessary to sustain a desired level of growth. Intensive management and rapid growth rates may also induce (dilution)

multiple nutrient limitations, especially during the early

stages of stand development. As such, multiple element

Figure 3—Standing aboveground biomass vs. stand age for

control (C), weed control (W), fertilization (F) and combination (FW) treatments for loblolly and slash pine growing on

Spodosols in north central Florida. Each point is the mean

of three replicate plots, along with standard errors. Figure 4—Basal area accretion vs. stand age for control (C),

weed control (W), fertilization (F) and combination (FW)

treatments for loblolly and slash pine growing on Spodosols

in north central Florida. Each point is the mean of three

replicate plots, along with standard errors.

fertilization may be necessary in southern pine stands, and

additional research on nutrient balance, especially for

elements other than N and P, will be required to support

management applications. Finally, in order to achieve

continued success in managing the nutrition of southern

pine stands, foresters will require not only technical skill for

developing prescriptions, but also appreciation of other

environmental and silvicultural interactions with forest

fertilization (for example, pest management, understory

competition, wood properties, water quality).



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34

LITERATURE CITED

Adams, M.B.; Allen, H.L. 1985. Nutrient proportions in foliage of

semimature loblolly pine. Plant and Soil 86: 27-34.

Adegbidi, H.G.; Comerford, N.B.; Hua, L. [and others]. 2002.

Determining nutrient requirements for intensively managed

loblolly pine stands using the SSAND (soil supply and nutrient

demand) model. In: Outcalt, K.W., ed. Proceedings of the

eleventh biennial southern silvicultural research conference.

Gen. Tech. Rep. SRS-48. Asheville, NC: U.S. Department of

Agriculture, Forest Service, Southern Research Station:

26-30.

Adegbidi, H.G.; Jokela, E.J.; Comerford, N.B. 2003. Factors influencing growth efficiency patterns in an intensively managed

loblolly pine chronosequence. [In preparation].

Albaugh, T.J.; Allen, H.L.; Dougherty, P.M. [and others]. 1998.

Leaf area and above- and belowground growth responses

of loblolly pine to nutrient and water additions. For. Sci. 44:

317-328.

Allen, H.L. 1987. Forest fertilizers: nutrient amendment, stand

productivity, and environmental impact. J. For. 85: 37-46.

Amateis, R.L.; Liu, J.; Ducey, M.J.; Allen, H.L. 2000. Modeling

response to midrotation nitrogen and phosphorus fertilization in

loblolly pine plantations. South. J. Appl. For. 24: 207-212.

Bailey, R.L.; Burgan, T.M.; Jokela, E.J. 1989. Models to predict

changes in stand structure and yields of fertilized mid-rotationaged slash pine plantations. South. J. Appl. For. 13: 13-17.

Comerford, N.B.; Fisher, R.F. 1984. Using foliar analysis to classify

nitrogen-responsive sites. Soil Sci. Soc. Am. J. 48: 910-913.

Fisher, R.F.; Binkley, D. 2000. Ecology and management of forest

soils. John Wiley & Sons. New York. 489 p.

Fisher, R.F.; Garbett, W.S. 1980. Response of semimature slash

and loblolly pine plantations to fertilization with nitrogen and

phosphorus. Soil Sci. Soc. Am. J. 44: 850-854.

Fox, T.R. 2004. Species deployment strategies for the southern

pines: site specific management practices for the flatwoods of

Georgia and Florida. In: Dickens, E.D.; Barnett, J.P.; Hubbard,

W.G.; Jokela, E.J., eds. Slash pine: still growing and growing!

Proceedings of the Slash Pine Symposium. Gen. Tech. Rep. 76.

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

Southern Research Station: 50-55.

Jokela, E.J.; Allen, H.L.; McFee, W.W. 1991a. Fertilization of

southern pines at establishment. IN Duryea, M. L.; Dougherty, P.

M. eds. Forest Regeneration Manual. Kluwer Academic

Publisher, Dordrecht, The Netherlands. 263-277.

Jokela, E.J.; Harding, R.B.; Nowak, C.A. 1989. Long-term effects

of fertilization on stem form, growth relations, and yield estimates of slash pine. For. Sci. 35: 832-842.

Jokela, E.J.; Long, A.J. 2000. Using soils to guide fertilizer recommendations for southern pines. University of Florida, Institute of

Food and Agricultural Sciences Extension Circular 1230. 11 p.

D.b.h. class (inches)

2 4 6 8 10 12 14

0

200

400

600

800

1,000

D.b.h. class (inches)

2 4 6 8 10 12 14

0

200

400

600

800

1,000

D.b.h. class (inches)

2 4 6 8 10 12 14

0

200

400

600

800

1,000

D.b.h. class (inches)

2 4 6 8 10 12 14

0

200

400

600

800

1,000

Stem volume

(cubic feet per acre)

Stem volume

(cubic feet per acre)

Control

83% < 9"

17% 9-12"

Weed control

64% < 9"

36% 9-12

Fertilized

56% < 9"

35% 9-12"

9% > 12"

Fertilized + weed

52% < 9"

40% 9-12"

8% > 12"

Figure 5—Effects of silvicultural treatments on the distribution of stem volume by diameter class

for 18-year-old loblolly pine growing on Spodosols in northcentral Florida. Trees < 9 inches were

considered pulpwood; trees 9 to 12 inches were considered chip&saw; and trees > 12 inches

were sawlogs.
35

Jokela, E.J.; Martin, T.A. 2000. Effects of ontogeny and soil nutrient supply on production, allocation, and leaf area efficiency in

loblolly and slash pine stands. Can. J. For. Res. 30: 1511-1524.

Jokela, E.J.; McFee, W.W.; Stone, E.L. 1991b. Micronutrient deficiency in slash pine: response and persistence of added

manganese. Soil Sci. Soc. Am. J. 55: 492-496.

Jokela, E.J.; Stearns-Smith, S.C. 1993. Fertilization of established

southern pine stands: effects of single and split nitrogen treatments. South. J. Appl. For. 17: 135-138.

Jokela, E.J.; Wilson, D.S.; Allen, J.E. 2000. Early growth responses

of slash and loblolly pine following fertilization and herbaceous

weed control treatments at establishment. South. J. Appl. For.

24: 23-30.

Martin, S.W.; Bailey, R.L.; Jokela, E.J. 1999. Growth and yield predictions for lower Coastal Plain slash pine plantations fertilized

at mid-rotation. South. J. Appl. For. 23: 39-45.

Morris, L.A.; Jokela, E.J.; O’Connor, J.B. 1992. Silvicultural guidelines for pinestraw management in the Southeastern United

States. Georgia Forest Res. Pap. No. 88. Georgia Foresty

Commission. 11 p.

North Carolina State Forest Nutrition Cooperative. 2002. 31st

annual report. Dept. of For., Coll. Nat. Resour., North Carolina

State Univ., Raleigh. 21 p.

Polglase, P.J.; Comerford, N.B.; Jokela, E.J. 1992. Mineralization

of nitrogen and phosphorus from soil organic matter in

southern pine plantations. Soil Sci. Soc. Am. J. 56: 921-927.

Pritchett, W.L.; Comerford, N.B. 1981. Nutrition and fertilization of

slash pine. In: Stone, E.L., ed. The managed slash pine ecosystem. 1981 June 9-11; Gainesville, FL: School of Forest.

Resources and Conservation, Univ. of Florida: 69-90.

Pritchett, W.L.; Comerford, N.B. 1982. Long-term response of

phosphorus fertilization on selected southern Coastal Plain

soils. Soil Sci. Soc. Am. J. 46: 640-644.

Sheffield, R.M.; Knight, H.A. 1982. Loblolly pine resource: southeast region. In: Symp. on the loblolly pine ecosystem-east

region; 1982 December 8-10; Raleigh, NC: School of Forest

Resources, North Carolina State University: 7-24.

Sheffield, R.M.; Knight, H.A.; McClure, J.P. 1983. The slash pine

resource. In: Stone, E.L., ed. The managed slash pine ecosystem. 1981 June 9-11; Gainesville, FL: School of Forest.

Resources and Conservation, Univ. of Florida: 4-23.

South, D.B.; Carey, W.A.; Johnson, D.A. 2003. Copper deficiency

in pine plantations in the Georgia Coastal Plain. In: Proceedings

of the 12th Biennial Southern Silvi. Res. Conf., Biloxi, MS Feb 24-

27, 2003.

Stone, E.L. 1968. Micronutrient nutrition of forest trees: a review.

In: Forest fertilization – theory and practice. 1967 April 18-21;

Gainesville, FL: Tennessee Valley Authority, Knoxville: 132-175.

Wells, C.G.; Crutchfield, D.M.; Berenyi, N.M.; Davey, C.B. 1973.

Soil and foliar guidelines for phosphorus fertilization of loblolly

pine. USDA Forest Serv., Southeast Forest Exp. Sta., Asheville,

N.C. Res. Pap. SE-110.
36

INTRODUCTION

Recent decreases in pine pulpwood demand and stumpage prices to near record lows (TMS 2002) in the southeastern U.S., along with increased demand and prices for

pine straw (Doherty and others 2000), has made many

forest and land managers re-evaluate initial planting densities. Some forest landowners and foresters are interested

in delaying a thinning or forgoing thinning to rake pine

straw for a longer period of time. Lower initial densities

may help achieve those goals. Conversely, some forest

product companies are currently investigating the potential

benefits of high initial densities and intensive management

for earlier first thinnings, smaller intervals between thinnings, and shorter rotations. The focus of this paper is to

discuss the impacts of planting density on stand biology

and yields as well as the economic ramifications for stands

growing under different levels of site productivity and

management.

Choosing a planting density for slash pine (Pinus elliottii

var. elliottii, Engelm.) plantations has important economic

and biological ramifications. In slash pine, and conifers in

general, increasing planting density decreases tree diameter growth (Ware and Stahelin 1948, Worst 1964, Jones

1987). However, at high stand densities, (greater than

1200 trees per acre), tree height may be suppressed

relative to stands planted at wider spacings, but to a lesser

extent than is diameter growth (Rahman 1969, Jones

1987). In contrast to the growth of individual trees, total

wood production per unit of land area increases as stand

density increases because volume associated with the

additional trees more than compensates for the decreases

in the size of individuals. As stands age, however, convergence of wood production often occurs between different

density stands because the growth rate of high density

stands reaches a maximum and begins to decline earlier

than lower density stands. In addition, greater density

dependant mortality in the denser stands may hasten this

convergence.

Site productivity, land use history (cut-over, old-field, or

pasture), and management intensity have a large influence

on how much wood is produced and the timing of growth

convergence between different density stands. In general,

the faster the growth rate the sooner this growth convergence between different density stands occurs. Some longterm slash pine spacing studies on former old-field sites

(Bowling 1987, Jones 1987) have shown that resultant

wood yields without thinning were similar by age 20- to 25-

years for initial planting densities between 400 to 800 trees

per acre (TPA). This rapid convergence of stem production

between different density stands on old-field sites may be

associated with rapid growth due to low initial hardwood

competition, a residual fertilizer effect, and typically good

soil tilth.

In contrast, convergence of wood production between

different density stands takes longer on cut-over sites due

to slower overall growth, but also due to a greater intensity

of interspecific competition in the lower density stands.

Sarigumba (1984) found that slash pine volume production

on cut-over sites planted at 436 TPA was lower than wood

volume production of stands planted at 605 TPA by age

25-years on sites of marginal productivity (MAI of 1.25 to

1.70 cords per ac per yr). These sites received low levels of

site preparation and management. Borders and Bailey

(1985) also found that wood yields on cut-over sites from

lower planting densities (400 to 436 TPA) were lower (by

3 to 5 cords per acre) than higher planting densities (800

TPA) through age 25-years. Pienaar and others (1996)

PLANTING DENSITY IMPACTS ON SLASH PINE STAND GROWTH,

YIELD, PRODUCT CLASS DISTRIBUTION, AND ECONOMICS

E. David Dickens and Rodney E. Will1

1 E. David Dickens, Associate Professor; and Rodney E. Will, Assistant Professor of Forest Productivity and Tree Physiology, Daniel B.

Warnell School of Forest Resources, The University of Georgia, Statesboro, GA 30460, and Athens, GA 30602-2152, respectively.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—The establishment phase is a very critical decision-making phase in the life of a pine plantation. Key choices

in site preparation intensity and type, pre-plant competition control, species selection, seedling genetic quality and size,

fertilization, and first year post plant herbaceous weed control have large and long lasting effects on wood yields,

rotation length, and products grown. Within a level of forest management, planting density, spacing configuration, and

subsequent survival rate can affect stand access, time of canopy closure, time to first pine straw harvest, age to first

thinning, number of thinnings, and product class distributions over time. Initially, higher planting densities yield more

volume. Eventually, without thinning, stand volumes converge between lower and higher initial stand densities. The more

intensive the management and the higher the site productivity the sooner this convergence occurs. An attractive initial

spacing for slash pine (Pinus elliottii Engelm. var. elliottii) may not be so attractive for loblolly pine (Pinus taeda, L.) or

longleaf (Pinus palustris, Mill.). This is due to differences in self-pruning characteristics, branch base diameter, number

of branches, branch angle, or potential survival differences by species on certain sites. This paper will discuss the

impacts of planting density under different levels of site productivity and management on slash pine stand biology,

yields, and economic returns using several long-term studies.
37

modeled slash pine planted at two densities on cut-over

sites. They predicted that the wood volume production of

400 TPA stands (3300 and 3900 ft3

 per acre) was lower

than wood volume production from 800 TPA stands (3850

and 5075 ft3 per acre) through age 35-years on site index

60 and 70 feet (base age 25-years) sites, respectively.

When considering economic returns related to planting

density, however, factors in addition to total wood production need to be considered; timing and intensity of thinning,

tree size distribution and resultant product classes, cost of

planting, cost of site preparation, potential for pine straw

production, and ease of stand access. In two old-field site

studies, for instance, planting at lower densities (400 and

436 TPA) resulted in larger diameter, more valuable wood

and greater total economic return than the traditional 600

to 800 TPA planting densities under a no thin management

regime by age 20- and 25-years (Bowling 1987, Jones

1987).

EFFECT OF PLANTING DENSITY OF

INTENSIVELY MANAGED STANDS

Experimental studies have indicated that slash pine yield

can be pushed to exceed 3 cords per acre per year with

the application of complete control of interspecific competition and fertilization (Borders and Bailey 2001). The incorporation of intensive forest management may impact the

relationship between stand density and stem growth, particularly if carrying capacity is altered. To address this question, the Plantation Management Research Cooperative

(based at the Warnell School of Forest Resources, The

University of Georgia) and its industrial cooperators installed

a series of slash pine studies to examine the interaction

between stand density and management intensity. Following

six growing seasons, the more intensive forest management treatments (complete control of interspecific competition and multiple fertilization) significantly increased tree

size. However, the effects of stand density were similar

regardless of management intensity (fig. 1). Therefore, the

effects of stand density appear to be consistent across a

broad range of management intensities and environments.

Although the timing of when convergence in wood production occurs among different density stands is affected by

site quality and management intensity, the nearly universal

phenomenon of convergence in wood production raises

the question as to what resource or biological mechanism

limits stem growth as stand density increases. By identifying the limiting processes or resources, these limiting functions hopefully can be addressed through silvicultural inputs,

genetic selection, or genetic manipulation. This question

was addressed using the intensively managed (multiple

fertilizer applications and complete control of interspecific

competition) set of Plantation Management Research

Cooperative studies discussed above. Given the intensive

management and very fast growth rates, stand growth was

becoming limited in the higher density stands very early

during stand development. For instance, stem growth

during the fourth growing season increased only about 3.5

times when planting density was increased five-fold from

300 to 1500 trees per acre (Burkes and others, in press).

One possibility for the limitation of stem growth per unit of

land area in the high density stands was that either the

ability of foliage to gain carbon through photosynthesis

decreased or the rate of carbon loss via respiration

increased such that less photosynthate was available for

stem growth. However, photosynthetic capacity and respiration rates were not affected by stand density (Will and

others 2001). Another possibility was that the slowing of

stem growth in higher density stands resulted from more

photosynthate being partitioned to root or foliage and less

to stem as the competition for above and below ground

resources intensified. However, biomass partitioning to

stem relative to other stand components did not decrease

as stand density increased. Rather, growth efficiency (stem

production per unit of leaf biomass) and the ratio between

stem growth and standing fine root biomass increased as

stand density increased (fig. 2) (Burkes and others, in

press), indicating a greater fraction of fixed carbon was

used for stem growth at higher stand densities.

What did appear to limit stem growth per unit land area

was canopy size, which drives both radiation interception

and photosynthetic surface area (fig. 3) (Will and others

2001). The initial greater stem growth rates in denser stands

and later slowing of stem growth was well correlated to the

development of leaf area. Therefore the limitation in stand

growth as planting density increases appears related to a

site’s capacity to support leaf area which in turn is a function of nutrient and water availability. As a result, silvicultural activities should focus on increasing leaf area.



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Figure 1—Effect of planting density on the height and diameter of

slash pine stands following the sixth growing season. Intensive

stands received multiple fertilization and complete interspecific

competition control.
38

Overall, increasing planting density has multiple benefits,

including: accelerating early volume production, increasing the efficiency of stem production relative to other stand

components, and early site occupancy. The declines in

stand growth rate that occur at high stand densities as stand

development progresses, combined with economics of

stand establishment and product distribution (discussed

below), can result in moderate stand densities as the best

choice for planting. Higher intitial stocking densities may

be financially attractive if aggressive thinning regimes and

other silvicultural practices can be employed.

POTENTIAL PINE STRAW PRODUCTION OF

INTENSIVELY MANAGED STANDS

Of great interest to some growers of slash pine plantations

is the production of pine straw. Intensive forest management,

including fertilization and competition control, results in

larger canopies and greater potential pine straw production.

Intensive management also facilitates pine straw production by keeping the stand clean to maximize rakable area

(Morris and others 1992, Dickens 1999, 2001). Overall,

intensive forest management results in very high potential

pine straw production. Intensively managed stands planted

at 1500 TPA produced 380 bales per acre during the sixth

growing season (assuming 17.7 lbs per acre) (Morris and

others 1992). In comparison, the stands containing 300 TPA

(only one-fifth the number of trees) produced approximately

260 bales per acre during the sixth growing season (fig. 4).

Canopy closure was realized at age 4-years in the 1500

TPA planting density, at 5-years for the 900 TPA density,

and had not yet been reached through age 6-years for the

300 TPA stands. Early canopy closure at the higher initial

densities provides forest landowners with pine straw raking

income opportunities sooner than the lower initial planting

densities. However, pine straw production per tree is greater

in the lower density stands and given enough time, pine

straw production will be fairly similar among stand densities.

Time of first rake, bale per acre production, and number of

years of raking are important factors if pine straw production is a high priority. In addition to total production, access

between rows is an important consideration for pine straw

raking operations and should be considered when choosing

a planting density.

LONG-TERM EFFECTS OF PLANTING DENSITY

FOR SITES WITH LOW TO MODERATE

MANAGEMENT INTENSITY AND LOW TO

MODERATE SITE PRODUCTIVITY

Several spacing studies were established in the 1950s

and 1960s that provide an opportunity to examine the

long-term impacts of planting density on stand growth.

Since these stands were established in an era before

intensive management, they reflect conditions that today

would be considered low to moderate productivity.

Effects of Spacing on Low Productivity Sites —

Brunswick Pulp and Paper Study

The Brunswick Pulp and Land Company slash pine spacing

study was established in 1957 on four Flatwoods soil

series on cut-over sites: the moderately well drained Orsino

(Spodic Quartzipsamments), somewhat poorly drained Leon

(Aeric Alaquods), poorly drained Mascotte (Ultic Alaquods),

and poorly drained Pelham (Arenic Paleaquults). Four site





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Figure 2—Growth efficiency (stem production per unit of leaf

biomass) during the fourth growing season for slash pine stands

planted in 1996 at different densities.
















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Figure 3—Relationship between leaf biomass and stem biomass

growth during the fourth growing season for slash pine stands

planted in 1996 at different densities. Leaf biomass was

calculated using litter traps. Stem biomass growth was calculated

using allometric equations.











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Figure 4—Annual litter production from intensively managed slash

pine stands planted in 1996 at different densities. Litter was

estimated using traps.
39

preparation levels were applied: burn (control), burn-scalp,

burn-bed, and burn-harrow. Four spacings included 6x6

(1210 TPA), 6x12 (605 TPA), 10x10 (436 TPA), and 12x12

feet (302 TPA). The experimental design was split-plot

randomized complete block with two replications for each

of the four drainage classes. Only pre-plant site preparation was performed with no subsequent weed control,

fertilization, or thinning during the 25-year study period.

Merchantable volume (3 inch top outside bark) mean

annual increment ranged from 1.0 to 1.7 cords per acre per

year (where 86 ft3

 outside bark per cord) during the 25-

year study period (Sarigumba 1984, Borders and Bailey

1985). Merchantable volume mean annual increment (MAI)

culmination occurred between ages 20 and 25 on all soils

but the Pelham. Generally the bed and harrow treatments

and 6x6 and 6x12 spacing basal area and volume MAI

culminated earlier across the soils than the control and

scalp treatments and 10x10 and 12x12 feet spacing.

Age 25-years data from this study for the 6x12 and 10x10

feet spacings are summarized here, assuming that a mixed

product class distribution of pulpwood and chip&saw and

culmination of merchantable volume MAI are forest management goals. Data from the best site preparation treatment

for each soil series were used at age 25-years to calculate

stand parameters. These were the bed (Pelham soil) or

harrow (Orsino, Leon, and Mascotte) site preparation

treatments.

There was little difference in mean percent survival for the

6x12 and 10x10 feet spacing at age 25-years across the

four soils. Survival ranged from 76 to 88 percent. Mean

d.b.h. for the 10x10 feet spacing was significantly greater

than the than the 6x12 spacing on the Leon (difference of

0.9 inch), Mascotte (difference of 0.6 inch), and Pelham

(difference of 0.7 inch) soils (table 1). Diameter distributions from the 10x10 spacing produced more trees per

acre of the larger diameter classes than the 6x12 spacing

(fig. 5). Basal area for the 6x12 spacing was significantly

greater than the 10x10 spacing on two of the four soils

(table 1). Mean heights for the 6x12 spacing (60 feet) and

10x10 spacing (61 feet) were not significantly different

across the four soils at age 25-years.

Merchantable volume (Bailey and others 1982, Borders

and Bailey 1985) per acre followed the same pattern as

basal area with the 6x12 feet spacing producing significantly greater volume by an average of 4.9 cords after 25-

years than the 10x10 spacing. Merchantable volume MAI

for the 6x12 spacing was greater than the 10x10 on the

Orsino and Mascotte, but was not significantly different on

the Leon and Pelham soils through age 25-years (table 1).

The 6x12 spacing produced significantly greater pulpwood

volume (5 to 9 inch d.b.h class) than the 10x10 spacing by

age 25-years on each soil series (table 1). The 10x10

spacing chip&saw volumes (≥ 9 inch d.b.h class) were not

significantly greater than the 6x12 spacing on each individual soil (table 1), but was significantly greater when averaged across the four soils. Using stumpage prices of $20

per cord for pulpwood and $75 per cord for chip&saw

(TMS 2000) the 10x10 spacing dollar per acre revenue

was 7 percent greater (an average of $109 per acre) than

the 6x12 spacing. This per acre value difference is minor

and the financial picture may change if a fertilization and

thinning regime were employed.

Table 1—Slash pine spacing effects on mean stand

parameters at age 25-years on four Georgia flatwoods

soils—the Brunswick Pulp and Land Company study

Stand Spacing (feet)

parameter Soil 6 x 12 10 x 10

inches

D.b.h.a Orsino 7.4a 7.6a

Leon 6.6b 7.5a

Mascotte 6.6b 7.2a

Pelham 6.1b 6.8a

square feet per acre

Basal area Orsino 142a 121b

Leon 112a 107a

Mascotte 131a 99b

Pelham 107a 96a

cords per acre per year

Merchantable Orsino 1.70a 1.38b

volumeb MAI Leon 1.34a 1.34a

Mascotte 1.57a 1.19b

Pelham 1.17a 1.10a

cords per acre

Pulpwood volume Orsino 22.0a 12.9b

Leon 16.1a 11.3b

Mascotte 25.5a 12.2b

Pelham 20.0a 12.8b

 Chip&saw volume Orsino 20.6a 21.5a

Leon 17.3a 22.3a

Mascotte 13.9a 17.5a

Pelham 9.3a 14.8a

dollars

Value per acre Orsino 1,985c 1,871

Leon 1,620 1,899

Mascotte 1,553 1,557

Pelham 1,098 1,366

d.b.h. = diameter at breast height; MAI = merchantable volume

mean annual increment.

a Within a stand parameter and soil treatment means followed by

the same letter are not significantly different at the 5-percent

alpha level using Duncan’s Multiple Range Procedure test.

b 86 cubic feet outside bar per cord and 75 cubic feet inside bar

per cord are assumed.

c Stumpage value based on $20 per cord for pulpwood and $75

per cord for chip&saw (TMS 2000) with a 15-percent defect for

chip&saw assumption (PW = 5 to 9 and CNS ≥ 9 inch d.b.h.

class).
40

I. Effects of Spacing on Moderately Productive

Sites — USFS Dooly County, GA Study

The United States Forest Service (USFS) slash pine spacing

study in Dooly County, Georgia was initiated in 1952 on an

old-field site. Nursery-grown 1-0 seedlings from the Georgia

Forestry Commission nursery in Albany were planted in

January 1952, with replanting in March and May 1952 to

replace dead seedlings. The soil series represented were

Lakeland (sandy Typic Quartipsamments) and Gilead (fine

Aquic Halpudults) (Harms and Collins 1965, Jones 1987).

Two replications of initial spacings included 6x6 (1,210

TPA), 6x8 (908 TPA), 5x10 (871 TPA), 8x8 (681 TPA), 6x12

(605 TPA), 10x10 (436 TPA), 7.5x15 (387 TPA), and 15x15

feet (194 TPA). The few invading volunteer pines, hardwood, and other woody vegetation were removed from the

study area. No fertilizers were applied during the study.

Survival was excellent from study inception, averaging 97

percent by age 4-years (Harms and Collins 1965) and 93

percent at age 12-years. Bennett (1960) noted that by age

5-years, trees were significantly larger in the 10x10 feet

and wider spacings than the denser spacings. In this case,

Bennett postulated that age 5-years marked the beginning

of intraspecific competition for growing space. Harms and

Collins (1965) noted that 58 percent of the 6x6 spacing

trees reached merchantability compared to 85 percent of

the 6x8 spacing by age 12 years old. In subsequent years,

a sub-sample of total heights, d.b.h., survival, and live

crown ratio were tallied at ages 15-, 20-, 25-, and 30-years

(Jones 1987).

This is a brief summary comparing all spacings from age

15- to 30-years. Merchantable volume (4 inch top outside

bark) mean annual increment culminated at age 20-years

for all initial densities except the widest spacing (15x15 feet),

which peaked at age 25 years old (Jones 1987). Merchantable volume MAI at age 20-years ranged from 1.8 cords

per acre per year for the 6x6 spacing to 2.10 cords per

acre per year for the 6x8 and 8x8 feet spacing. However,

merchantable volumes at age 20-years were not significantly different among spacings except that the volume of

the 15x15 feet spacing was significantly less than the other

spacings (Jones 1987).

Examination of the intermediate spacings (5x10 (871 TPA

at planting), 8x8 (681 TPA), 6x12 (605 TPA), and 10x10

(436 TPA), revealed that percent survival was not significantly different among the four spacings at age 20-, 25-, or

30-years (table 2). At age 15-years, the mean d.b.h. for the

10x10 spacing was significantly greater than the three

denser spacings. The average d.b.h. of the 6x12 spacing

and 8x8 spacing were not significantly different from one



















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Figure 5—Slash pine diameter distributions by spacing at age 25-years on four Georgia cutover flatwoods soils:

Orsino, Leon, Mascotte, and Pelham.
41

another, but were significantly greater than the average

d.b.h. of the 5x10 spacing (table 2). This d.b.h. trend

continued though age 30-years. Diameter distributions at

ages 20- and 25-years (fig. 6) illustrate that the 10x10

spacing produced more chip&saw sized trees compared to

the higher densities. Basal area per acre of the different

spacings was not significantly different between 15- and

30-years and converged by age 30-years. Basal area per

acre decreased for all four spacings by 5 to 13 feet2

 per

acre between ages 25- and 30-years (table 2) due to

increased mortality of the larger diameter trees. Eighteen

Table 2—Mean stand parameters by spacing and age from the old-field slash pine

spacing study in Dooly County, GA

Age (years)

Spacing 15 20 25 30 15 20 25 30

feet - - - - - Arithmetic d.b.h. (inches)a - - - - - - - Basal area (square feet per acre) - -

10 x 10 7.3a 8.2a 9.0a 9.7a 111a 134a 141a 136a

6 x 12 6.4b 7.1b 7.9b 8.5b 118a 134a 140a 133a

8 x 8 6.2b 6.9bc 7.6bc 8.1bc 133a 151a 153a 143a

5 x 10 5.6c 6.2c 6.9c 7.5c 133a 147a 148a 134a

- - - - - - - - - Percent survival - - - - - - - - - Merchantable volumeb (cords per acre)

10 x 10 86a 83a 72a 60a 26.7a 40.5a 48.4a 50.0a

6 x 12 85a 77a 66a 55a 26.2a 37.0a 44.6a 46.6a

8 x 8 92a 84a 71a 58a 29.3a 41.8a 48.3a 48.6a

5 x 10 86a 78a 63a 48a 26.8a 38.2a 43.9a 44.2a

Dominant, codominant total height (feet) - - - - Live crown ratio (percent) - - - -

10 x 10 48a 58a 66a 70a 44a 35a 27a 25a

6 x 12 46ab 55ab 62ab 67ab 42ab 31b 25b 24a

8 x 8 46ab 55ab 62ab 66ab 38bc 30b 23c 22a

5 x 10 45b 53b 60b 64b 36c 31b 24bc 23a

a Within an age and stand parameter treatment means followed by the same letter are not significantly

different at the 5-percent alpha level using Duncan’s Multiple Range Procedure test.

b 86 cubic feet outside bar per cord and 75 cubic feet inside bar per cord are assumed.

trees in the > 8 inch d.b.h. classes died between ages 20-

and 25- compared to 66 trees between ages 25- and 30-

years across the four spacings.

At age 15-years, mean live crown ratio (LCR) followed a

similar pattern as d.b.h. among spacings with the greatest

LCR’s found in the wider spacings (table 2). However, by

age 30-years, LCR of all spacings had decreased and was

similar among spacings (table 2). An LCR of 33 percent is

generally considered the threshold to maintain fast growth

rates. The 5x10, 8x8 and 6x12 spacing trees should have













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Figure 6—Diameter distributions by spacing and age on the old-field slash pine U.S. Department of Agriculture Forest Service spacing

study in Dooly County, GA.
42

been thinned between age 15- and 20-, while the 10x10

spacing trees thinning could be delayed to maintain LCR

greater than 33 percent (table 2) providing a wider thinning window. The mean total height for codominants and

dominants was significantly lower in the highest density

(5 x 10 feet spacing) compared to trees in the widest

spacing (10x10) starting at age 15-years (table 2). This

difference was maintained though age 30-years. There

were no significant differences in merchantable volume

per acre among the four intermediate spacings at age 15-,

20-, 25-, or 30-years (table 2).

II. Effects of Spacing on Moderately Productive

Sites — International Paper Study

A slash pine spacing study was initiated by the International

Paper Company in 1964. The study area is located in

Decatur County, Georgia on an old-field site (Orangeburg

soil series - fine-loamy Typic Kandiudults) (Bowling 1987).

The study area had six replications of four spacings (400,

600, 800, and 1000 TPA in square configurations), with

three of six replications thinned at age 15-years. The study

was followed in five year intervals for 20-years (Bowling

1987). Bowling reported that by age 5-years intraspecific

competition had not yet occurred as there were no significant differences in mean total height or d.b.h. across the

four initial densities. Percent survival ranged from 95 to 98

percent by age 5-years. Basal area per acre was a direct

function of surviving TPA (Bowling 1987).

Age 10-years mean d.b.h for the 400 TPA initial density

was 0.6, 0.9, and 1.3 inches greater than the 600, 800, and

1000 TPA initial density, respectively, with these differences

increasing with stand age (table 3). Basal area peaked in

the 800 TPA plots at age 20-years (174 square ft2 per acre)

surpassing the 1000 TPA basal area. The basal area of the

400 TPA and 600 TPA plots were starting to converge with

those of the 800 and 1000 TPA plots between ages 15- and

20-years. At age 10-years, mean height increased with

decreasing stand density by approximately one foot per

two hundred TPA decrease in planting density (table 3).

These differences remained fairly stable except for a relative decrease in height increment for the 1000 TPA plot trees

at age 20-years. Merchantable volumes were within two

cords per acre among the four planting densities by age

10- and 15-years (table 3). By age 20-years, merchantable

volume was greatest in the 800 TPA plots (45 cords per

acre). The 400 and 600 TPA densities had intermediate

volumes (42 cords per acre), while the 1000 TPA had the

lowest volume (38 cords per acre).

ECONOMICS OF PLANTING DENSITY UNDER

VARIOUS LEVELS OF SITE PRODUCTIVITY

The lower 436 TPA planting density on the relatively low

productivity cutover sites (Brunswick Pulp and Land Study)

produced 4.9 cords per acre less volume than the 605 TPA

planting density. However, the proportion of pulpwood (5 to

9 inch d.b.h. classes) and chip&saw (≥ 9 inch d.b.h. class

less a 15 percent defect assumption) varied with density.

An average 8.1 cords per acre less pulpwood, but an

average 3.7 cords per acre more chip&saw volume were

produced at the lower planting density (436 TPA) by age

25-years.

The lower densities (400 and 436 TPA) on the two old-field

site study areas (IP and USFS) produced similar merchantable volumes as the higher, traditional planting densities

(600 to 605 TPA) during the study periods. However, the

lower planting densities (400 to 436 TPA) produced much

greater volumes in the chip&saw class, 9 to 13 cords per

acre for the IP and USFS studies using a 15 percent defect

assumption. Value per acre for the lower planting densities

(400 to 436 TPA) was greater than the higher planting

Table 3—Mean stand parameters by spacing and age from the International Paper old-field slash pine spacing study in Decatur County, GA

Planting Age (years)

density 5 10 15 20 5 10 15 20

TPA - - - - - - D.b.h. (inches) - - - - - Basal area (square feet per acre)

400 2.3 6.1 7.6 8.4 12 77 115 144

600 2.3 5.5 6.7 7.3 17 95 136 156

800 2.2 5.2 6.2 6.9 22 112 150 174

1,000 2.1 4.8 5.8 6.4 24 122 154 166

- - - - Total height (feet) - - - - - - - Merchantable volumea b - - -

400 12 34 53 63 — 10 27 42

600 12 33 51 62 — 10 28 42

800 12 32 51 61 — 9 28 45

1,000 12 31 50 58 — 8 26 38

TPA = trees per acre; d.b.h. = diameter at breast height.

a Cords per acre.

b Eighty-six cubic feet outside bark per cord and 75 cubic feet inside bark per cord

are assumed.

Source: Bowling (1987).
43

densities (600 or greater TPA) on the two old-field sites

discussed here (table 4).

Value per acre increases associated with the lower planting densities ranged from $109 (7 percent gain) on the

relatively low productivity cutover sites, $500 to $750 (25

to 92 percent gain) on the USFS old-field study area, and

$500 to $900 per acre (31 to 75 percent gain) on the IP

old-field site (table 4). Because there was a greater total

volume production in the higher density stand on the cutover site and similar volumes on the old-field sites, the

greater value of the lower density stands resulted from the

large price disparity between pulpwood and chip&saw.

Therefore, for all three long-term studies, the value per

acre was higher at the lower planting density.

The best planting density can depend largely on future

product prices as well as landowners needs and objectives. If the price disparity between pine pulpwood and

chip&saw continues to be large, then the combination of

maximizing wood volume production, product class distribution to favor higher valued products, and wood quality

will be high priorities. Maximizing wood volume alone may

not be as high a priority that is once was in the mid-1990s

when pulpwood prices reached all time highs (TMS 1998).

DISCUSSION

Forest landowners, practicing foresters, and land managers

should address the following when choosing a spacing for

slash pine plantations: (1) rotation age, (2) products grown

(pulpwood, chip&saw, sawtimber, poles, pine straw), (3)

product prices, (4) thinning timing, number, and intensity,

and (5) equipment access needs. In addition, the intensity

of forest management also must be considered since growth

within a planting density can be dramatically affected by

activities such as site preparation, competition control, and

fertilization.

Higher density plantings achieve canopy closure, site utilization, and pine straw production earlier than lower density

plantings under the same level of management. An early

first thinning (as early as age 8- to 10-years-old assuming

the removed stems are merchantable) may be warranted

to maintain stand vigor, diameter growth, and volume production in the intensively managed higher density stands.

Generally stands are operationally thinned later, between

ages 12- to 18-years or when average total tree height is

at least 40 feet. The higher planting densities thinning

window to optimize growth rates are narrower than for the

lower planting densities. Higher planting densities also

may be beneficial on cut-over sites with low site preparation and management inputs. The higher planting densities

help crop trees occupy the site, whereas the lower planting

densities may permit high interspecific competition until

much later during stand development, reducing early stand

volume production.

In contrast, for those forest landowners whose objective is

delaying or forgoing a thinning, raking pine straw as long

as possible, and growing mostly chip&saw and larger sized

wood, lower planting densities may be the best choice. A

disadvantage though is a time delay in canopy closure with

lower planting densities, increasing the time to first pine

straw revenue. The lower planting densities (400 and 436

TPA) produced the same or greater volume as the higher

planting densities (600 to 800 TPA) by age 20-years and

much more chip&saw volume on the two old-field sites (IP

and USFS studies). Excellent pre- and early post-establishment competition control to maximize survival, growth,

and site occupancy should be a high priority for lower density stands. In addition, stand access for ground equipment

will often dictate row width and depends on equipment

size and operator experience.

LITERATURE CITED

Bailey, R.L.; Pienaar, L.V.; Shiver, B.D; Rheney, J.W. 1982. Stand

structure and yield of site prepared slash pine plantations. UGA

College of Ag. Exp. Stn. Res. Bull. 291. 83 p.

Bennett, F.A. 1960. Spacing and early growth of planted slash

pine. Journal of Forestry Vol. 58: 966-967.

Borders, B.E.; Bailey, R.L. 1985. Stand density effects in slash

and loblolly pine plantations. PMRC res. Paper. 1985-1. 149 p.

Borders, B.E.; Bailey, R.L. 2001. Loblolly pine: pushing the limits of

growth. South. J. Appl. For. 25: 69-74.

Bowling, D. 1987. Twenty year slash pine spacing study: what to

optimize? In: Proceedings of the 4th Biennial So. Silvi. Res. Conf.,

Atlanta, GA. Nov 406, 1986. SRS GTR SE-42. pp. 300-304.

Table 4—Product class distributions and value per acrea

for the slash pine spacing studies

Study Age TPA PW CNS Value

years Cords per acreb $ per acre

BP&LC 25 605 20.9a 15.3a 1,564

436 12.3b 19.0b 1,673

USFS 20 871 37.2a 0.74b 800

681 37.5a 3.4b 1,002

605 31.2a 4.9b 989

436 21.6b 14.8a 1,540

25 871 35.5a 6.2c 1,174

681 33.2a 11.1bc 1,498

605 26.3b 13.8b 1,558

436 14.3c 26.9a 2,302

30 871 28.2a 11.7c 1,439

681 26.4a 16.7bc 1,776

605 21.4b 21.4b 2,035

436 11.1c 30.8a 2,535

IP 20 1,000 30 8 1,200

800 31.5 13.5 1,643

600 27 15 1,665

400 17.5 24.5 2,188

TPA = initial planting density per acre; PW = pulpwood; CNS =

chip&saw; BP&LC = Brunswick Pulp and Land Company; USFS =

U.S. Department of Agriculture Forest Service; IP = International

Paper Company.

a At $20 per cord pulpwood and $75 per cord chip&saw (TMS

2000) and a 15-percent chip&saw defect assumption.

b Within a study, age and product class treatment means followed

by the same letter are not significantly different at the 5-percent

alpha level using Duncan’s Multiple Range Procedure test.
44

Burkes, E.C.; Will, R.E.; Barron, G.A. [and others]. [In press]. Biomass partitioning and growth efficiency of intensively managed

Pinus taeda and Pinus elliottii stands of different planting densities. Forest Science.

Dickens, E.D. 1999. Effect of inorganic and organic fertilization on

longleaf pine tree growth and pine straw production. In: Proceedings of the 10th Biennial So. Silvi. Res. Conf. Shreveport, LA,

February 16-18, 1999. USDA Forest Service GTR SRS-30.

Pp. 464-468.

Dickens, E.D. 2001. Fertilization options for longleaf pine stands

on marginal soils with economic implications. In: Proceedings of

the 31st Annual So. Forest Econ. Workshop. March 27-28, 2001.

Pp. 67-72.

Doherty, B.A.; Teasley, R.J.; McKissick, J.C.; Givan, B. 2000.

Nineteen ninety-nine farmgate value report. UGA CAES Center

for Agribusiness and Econ. Dev., Center Staff Report No. 6.

Athens, GA 160 p.

Harms, W.R.; Collins, A.B. 1965. Spacing and twelve-year growth

of slash pine. Journal of Forestry. Vol. 63: 909-912.

Harms, W.R.; DeBell, D.S.; Whitsell, C.D. 1994. Stand and tree

characteristics and stockability in Pinus taeda plantations in

Hawaii and South Carolina. Canadian Journal of Forest

Research. 24: 511-521.

Jones, E.P. 1987. Slash pine plantation study – age 30. Proceedings of the Fourth Biennial Southern Silviculture Conference.

USDA Forest Service Gen. Tech. Rep. SE-42. pp. 45-49.

Mann, W.F.; Dell, T.R. 1971. Yields of 17-year-old loblolly pine

planted on a cutover site at various spacings. USDA Forest

Service Research Paper SO-70. 9 p.

May, J.T.; Rahman, S.; Worst, R.H. 1973. Effects of site preparation and spacing on planted slash pine. J. of For. 71: 333-335.

Morris, L.A.; Jokela, E.J.; O’Connor, J.B., Jr. 1992. Silvicultural

guidelines for pine straw management in the southeastern

United States. Georgia Forest Res. Paper. #88, Georgia

Forestry Commission, Macon, GA. 11 p.

Rahman, S. 1969. Effects of site preparation and spacing on

planted slash pine. MS Thesis. UGA. 41 p.

Ross, S.M.; McKee, W.H., Jr.; Mims, M. 1995. Loblolly and longeaf

pine responses to litter raking, prescribe burning, and fertilization. In: Proceedings of the 8th Biennial So. Silvi. Res. Conf.

Auburn, AL. Nov. 1-3, 1994. Pp. 220-224.

Sarigumba, T.I. 1984. Sustained response of planted slash pine to

spacing and site preparation. In: Proceedings of the 3rd Biennial

So. Silvi. Res. Conf. USDA Forest Service. So Exp. Stn. Gen.

Tech. Rep. SO-34, pp. 79-84.

Sarigumba, T.I.; Anderson, G.A. 1979. Response of slash pine

to different spacings and site preparation treatments. SJAF 3:

91-94.

TMS. 1998. Timber Mart South stumpage prices – 2nd qrtr for

south GA 1998. Warnell School of Forest Resources. UGA,

Athens, GA.

TMS. 2000. Timber Mart South stumpage prices – 2nd qrtr for

south GA 2000. Warnell School of Forest Resources. UGA,

Athens, GA.

Ware, L.M.; Stahelin, R. 1948. Growth of southern pine plantations

at various spacings. Journal of Forestry. 46: 267-274.

Will, R.E.; Barron, G.A.; Burkes, E.C. [and others]. 2001. Relationship between intercepted radiation, net photosynthesis, respiration, and stem volume growth of Pinus taeda and Pinus elliottii

stands of different densities. Forest Ecology and Management.

154: 155-163.

Worst, R.H. 1964. A study of effects of site preparation and

spacing on planted slash pine in the Coastal Plain of southeast

Georgia. Journal of Forestry 62: 556-560.
45

INTRODUCTION

Slash pine (Pinus elliottii Engelm.) has the smallest natural

range of the four major southern pines. The range extends

from Georgetown, SC south to Central Florida and west to

Louisiana across the lower and middle coastal plains.

Slash pine has been planted extensively outside it’s native

range as far north as Tennessee and as far west as east

Texas. Loblolly pine (Pinus taeda L.) by comparison has

the largest range of the southern pines. It’s range extends

from southern New Jersey south to central Florida and

west to East Texas. It has proven to be a very adaptable

species widely planted outside it’s native range and even

internationally. Loblolly is also very responsive to cultural

practices such as fertilization and weed control.

Since the ranges of slash and loblolly overlap to a great

extent and since they are both proven valuable commercial

species, a major decision that must be made by foresters

is which of the two to plant on a given site. There are many

different factors that can possibly play a role in this decision,

but one factor that is usually important is the differential

volume or weight per acre yield for the species.

In an attempt to answer the species-site question, I looked

at estimated expected yield values for slash and loblolly

pine, published studies in the literature comparing yields

of slash and loblolly pine on the same site, and data from

Warnell School of Forest Resources Plantation Management

Research Cooperative (PMRC) plots where loblolly and

slash pine are being intensively managed on the same

sites. The objective was to determine the current state of

our knowledge of species preference by site based only on

volume and weight yield. Other factors did not enter into

the decision, though they should be considered along with

yields in an attempt to best meet landowner objectives.

GROWTH AND YIELD MODELS

Growth and yield models provide estimated volumes or

weights at different ages. Most of the models in the Southeast have been developed for plantations. In addition to

age, the quality of the site, the number of trees per acre,

and the basal area per acre are typical inputs to predict the

yield. Growth and yield models are developed from plots

established in operational plantations. On the plots, each

tree is measured for diameter at breast height (D) and total

height (H) and crown class is noted. The volume and/or

weight of each tree is predicted using an equation that

uses D and H as inputs. The volume and weight equation

was developed from cutting down hundreds of trees, weighing them in sections, measuring their taper from butt to tip,

and fitting an equation to these data. From the diameters

and plot size, basal area per acre can be calculated. From

the frequency of trees on the plot, trees per acre can be

calculated. The heights of all dominant and codominant

trees are averaged to obtain the average dominant height

used to estimate site index. The volumes and/or weights

are summed for the plot and expanded to an acre basis.

The result is a dataset that has age, average dominant

height, basal area per acre, trees per acre, and volume and

weight per acre. If the plots are measured at more than one

point in time, it is possible to not only model the expected

yield at any age in the dataset, but also to model the development of the different model inputs such as dominant

height, basal area per acre, and trees per acre over time.

The difference in expected yield between two ages represents growth. Good growth and yield models have been

developed for both slash and loblolly pine for the coastal

plain region where the ranges of the two species overlap.

If we begin with individual trees, the weight models that

have been developed indicate that for trees of the same

size (same D and H), slash pine will have a higher weight

than loblolly pine. For example, the PMRC weight equations for trees with D of 10 inches and H of 60 ft predict a

weight of 865 lbs for slash pine compared to 817 lbs for

loblolly pine. The reasons for this discrepancy are twofold.

Slash pine has slightly less taper than loblolly pine (it is

more cylindrical). For the tree size in our example, the

expected diameter at 20 ft for slash pine is 8.4 in vs 8.3 in

for loblolly. In addition, the specific gravity of slash pine is

LOBLOLLY VERSUS SLASH PINE GROWTH AND YIELD COMPARISONS

Barry D. Shiver1

1 Barry Shiver, Professor of Timber Management and Silviculture, Warnell School of Forest Resources, University of Georgia, Athens, GA

30602.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Growth and yield of slash (Pinus elliottii Engelm.) and loblolly pine (Pinus taeda L.) were compared where

both were grown on sites within the native range of slash pine. Comparisons were made using growth and yield models

developed for each species, using published studies from the literature, and by evaluating means from studies where

both species are being grown at a variety of densities and at different levels of management intensity. Results indicate

that even on sites that are considered to be slash pine sites, loblolly produces as much or more wood than slash pine.

When intensively managed, the gap between loblolly and slash pine increases. Though there are other good reasons to

grow slash pine, and some of these are discussed, landowners and foresters should not choose slash pine because

they believe it will produce more total or merchantable fiber than loblolly pine.
46

slightly higher than for loblolly pine. Given this, if slash

pine plantations grew at the same rate as loblolly plantations from planting, we would expect slash pine to have

higher yields than loblolly. As we will see, however, the

yield models indicate that the growth from planting is not

equal.

Table 1 presents the expected basal area values for the two

species if both the site index and the basal area values are

held constant. For both site 60, about an average site index,

and site 70, an above average site index, loblolly produces

more basal area than slash pine. This indicates that diameter growth for loblolly, under the same competition as

slash pine as measured by trees per acre, is higher than

for slash pine.

Values for trees per acre in table 2 indicate that even when

the two species have the same number of trees per acre

after regeneration mortality (age 2), the mortality rate is

higher on average for slash pine than for loblolly pine over

the rest of the rotation. This trend, in combination with the

higher d.b.h. growth for loblolly as evidenced in table 1

overcomes the slight advantage of slash pine from taper

and specific gravity. As a result, the growth and yield

models predict that loblolly pine has a distinct advantage

to slash pine in expected yield when both species start at

about the same density and are growing on the same site.

The reasons for the higher mortality rate for slash pine are

not clear, but there is at least some evidence to suggest

that for the same rate of fusiform rust (Cronartium fusiforme

Hedg. and Hunt) infection, the slash pine mortality rate is

higher than it is for loblolly pine. The expected yields in

table 2 indicate almost 20 percent more wood expected on

the same site for loblolly pine than for slash pine on a site

index 60 site.

These yield models do not have site specific information as

inputs. There is no soil classification information involved.

Many proponents of slash pine would say that there are

definite slash sites and loblolly sites. To evaluate these

claims, we first look to the literature and then to some specific studies that have evaluated the two species on a site

by site basis. The attempt here is not to present a complete

literature review of species comparison studies, but to

present results from those that have included a range of

different soil types in an attempt to identify “slash” sites and

“loblolly” sites.

LITERATURE REVIEW

Cole (1975) reported nine year results of a study on which

slash pine was planted at five locations and loblolly was

planted at seven locations across South Carolina, Georgia,

and north Florida. Across all sites, loblolly was more productive averaging 49 percent to 61 percent more volume

per acre than slash. Slash was more productive at only one

location, a poorly drained flatwoods site.

Shoulders (1975) reported 15 year results of a study established by the Southern Forest Experiment Station at 113

locations in Louisiana and Mississippi. Across all locations,

loblolly survival was better by 10 percent and loblolly had

lower fusiform rust infection and lower mortality of infected

stems. Slash pine height growth was greater than or equal

to loblolly height growth only on wet sites. Height growth

was about equal on intermediate or dry sites. Using growth

and yield models and the age 15 stand characteristics as

inputs, volumes of loblolly pine were projected to surpass

slash pine volumes at age 25 on all but the wet sites.

Haines and others (1981) reported seven year results of a

species comparison study on nine sites across the South.

Survival was much higher on average for loblolly than for

slash pine. Slash pine height growth exceeded loblolly at

only one location. Five of the nine sites were cutovers and

four were old fields. Loblolly outgrew slash pine by 2 to 1 on

the old field sites. On the cutover sites, the loblolly volume

exceeded the slash pine volume by 57 percent. This study

also contained a fertilizer treatment and loblolly had a

higher response to this treatment. Slash pine was recommended only on spodosols with no argillic (fine textured

loam or clay) horizon.

Shiver and others (2000) reported on a 14 year old PMRC

species comparison study with 160 locations spread across

eight soil groups. All sites were cutovers and there was no

fertilization, no herbaceous weed control, no chemical site

preparation, no release, and no thinning. All site preparation was mechanical site preparation and on the wetter soil

Table 1—Basal area (square feet per acre)

for slash and loblolly pine as predicted by the

Plantation Management Research Cooperative yield models given the same site

index and trees per acre

Species Age Trees Basal area

years square feet per acre

Site index 60

Slash 20 400 95.6

Loblolly 20 400 119.8

Site index 70

Slash 20 400 124.6

Loblolly 20 400 140.7

Table 2—Green weight (tons per acre) for

slash and loblolly pine at age 25 as predicted

by the Plantation Management Research

Cooperative yield models given the same

trees per acre at age 2 and the same site

index

Trees

Species Age 2 Age 25 Green weight

- - - per acre - - - tons per acre

Slash 500 320 121

Loblolly 500 352 151

Slash 600 383 130

Loblolly 600 400 154
47

groups most areas were bedded. Loblolly pine yields were

as high or higher than slash pine yields on all soil groups.

Table 3 values indicate that even though the average

percentage of stems with fusiform rust is slightly higher for

loblolly than for slash, the survival is higher for loblolly. The

higher infection rate at age 14 for loblolly may be due to

the infected slash stems dying. Once dead they are no

longer included in the dataset as infected and the percent

infection goes down. The basal area and volume averages

follow the same trends as on the other studies cited.

The Shiver and others (2000) study soil groups are

presented in table 4. The poorly drained and very poorly

drained soils, especially those without an underlying

argillic horizon, would be considered classic slash pine

sites. The only soil group on which slash wood production

is higher than loblolly is the very poorly to poorly drained

soil with no underlying argillic, and that difference is not

statistically significant (fig. 1). In other words there is so

much variability from one site to another within that soil

group that the amount by which slash pine is larger is not

different from zero. All other soil groups have loblolly equal

to or greater than the slash volume, though many of them

are also not significantly larger.

Another soil classification that is widely used in the slash

pine native range is the Cooperative Research in Forest

Fertilization (CRIFF) classification developed at the University of Florida. We regrouped our installations in the PMRC

study into CRIFF groups as described in table 5. Of these,

soil group D would be considered a slash pine site by conventional wisdom. Figure 2 indicates that loblolly produces

more merchantable weight by age 14 across all CRIFF

groups though the differences for B, C, and D soils are

minimal.

An evaluation of the differences in species production over

time indicates that the difference in total green weight from

age 5 to age 14 is diverging (fig. 3). At age five the differences were minimal, but since age 5 loblolly has increased

it’s weight per acre advantage over slash pine at every

measurement. This indicates that the differences in species

over time do not diminish, but rather increase in favor of

loblolly pine.

Table 3—Average values for stand characteristics of the Plantation Management Research

Cooperative species comparison study at age 14

across all soil classes

Characteristic Loblolly Slash

Stems with Cronartium (percent) 20 18

Survival (percent) 71 66

Basal area (square feet per acre) 98 81

Trees per acre 516 479

Merchantable volumea (cubic

feet per acre) 1,497 1,310

Merchantable green weightb

(tons per acre) 45 35

a Volume of all trees > 4.5 inches d.b.h. to a 3-inch top

diameter outside bark.

b Green weight of all trees > 4.5 inches d.b.h. to a 3-inch

top diameter outside bark.

Table 4—Soil groups on the Plantation Management Research Cooperative species comparison

study

Soil group Drainage Description

1 P, VP Spodosol with argillic

2 P, VP Spodosol, no argillic

3 P, VP Nonspodosols

4 SP, MW Spodosol with argillic

5 Sp, MW Spodosol, no argillic

6 Sp, MW Nonspodosols

7 W Nonspodosols

8 SE, E Nonspodosols

P = poorly drained; VP = very poorly drained; SP = somewhat poorly drained; MW = moderately well drained; W = well

drained; SE = somewhat excessively drained; E =

excessively drained.







#







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*


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Figure 1—Average merchantable green weight (tons per acre)

for trees > 4.5 inches d.b.h. to a 3.0-inch top (outside bark) by

PMRC soil group for slash and loblolly pine.

Table 5—Soil group descriptions for the Cooperative

Research in Forest Fertilization soil classification

system

Soil group Drainage Description

A P, VP, SP Argillic < 20 inches

B P, VP, SP Argillic > 20 inches

C P, VP, SP Spodosol with argillic

D P, VP, SP Spodosol, no argillic

F MW, W Argillic > 20 inches

G SE, E None or deep argillic

P = poorly drained; VP = very poorly drained; SP = somewhat

poorly drained; MW = moderately well drained; W = well

drained SE = somewhat excessively drained; E = excessively

drained.
48

INTENSIVE MANAGEMENT STUDIES

What about changes in management? In the last decade,

pine has been planted on many acres in the CRP program.

Those acres typically lack the hardwood component found

on cutover sites and the ability of those sites to provide

nitrogen and other nutrients to pines without fertilization is

high. Concurrently, the level of management intensity has

risen on cutover sites. Many cutover sites routinely now

receive chemical site preparation to largely eradicate

woody competition, at least early in the rotation. Many also

receive herbaceous weed control in the first growing

season and may receive fertilization at some point in the

first few years.

The PMRC has an intensive culture density study in the

coastal plain with both slash and loblolly present across a

range of soil classes. The study is 6 years old. The species

can be compared on plots that have planting densities of

300, 900, and 1500 trees per acre. There are two levels of

culture. On the intensive level, all of the competing vegetation, both herbaceous and woody, is removed from the site

and kept off as much as possible at all times. This requires

a great deal of work for the first two or three years, but once

crown closure is established the shade does the work of

keeping the plots clean. Plots were fertilized at planting

with 500 pounds of 10-10-10 fertilizer per acre and have

been fertilized since then at least every two years. On the

operational culture plots, there was both chemical and

mechanical site preparation, one year of banded weed

control, and fertilization only at planting with five hundred

pounds of 10-10-10 fertilizer per acre.

Figure 4 shows that there is an effect on height growth from

both culture and species. Loblolly has the ability to respond

to the added nutrients, moisture, etc. afforded by the intensive culture and it responds with greatly increased height

growth. It is 5 to 7 ft. taller than loblolly growing in operational stands. Slash, by comparison, adds about 2 ft. to the

average height it obtains with operational culture with all of







#







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Figure 2—Average merchantable green weight (tons per acre)

for trees > 4.5 inches d.b.h. to a 3.0-inch top (outside bark) by

CRIFF soil group for slash and loblolly pine.







#







  

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Figure 3—Average total green weight production by species over

time and across all soil groups for the PMRC species comparison

study.







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Figure 4—Average height by species, planting density, and

management intensity for 6-year-old loblolly and slash pine on the

PMRC culture/density trials.

Figure 5—Average d.b.h. by species, planting density, and

management intensity for 6-year-old loblolly and slash pine on the

PMRC culture/density trials.
49

the added benefits from intensive culture. In fact, the intensive slash pine height is about equal to the operational

loblolly pine height. By comparison, the average d.b.h.

values at age 6 are roughly equal for the two species across

all densities when both receive the same culture (fig. 5).

The total green weight at this young age shows the same

pattern we have seen on the other studies discussed (fig. 6).

On the operational culture plots, the loblolly has slightly

more green weight per acre than the slash pine. On the

more intensively managed plots, loblolly’s ability to use

more nutrients and moisture when they are provided

results in a larger difference between species.

CONCLUSIONS

We have seen that on virtually all soil types evaluated in

the native slash pine range loblolly produces more wood

than slash pine. Does this mean that everyone who is

planting slash pine is making a mistake? I would say no for

several reasons. One is that the difference between the

species is very small on what we would say are classic

slash pine sites that will receive operational management.

On CRIFF B, C, and D soil groups slash will produce on

average about the same amount of wood as loblolly. Though

this has not been verified with research data, some foresters

believe that there is less risk with slash pine on these sites.

If management will be more intensive, then the decision swings more toward loblolly on any of these sites

because of it’s superior ability to take advantage of weed

control and fertilization. Intensively managed slash pine

sites can produce about 7 green tons per ac per yr whereas

intensively managed loblolly stands can produce about

10-12 green tons per ac per yr.

Foresters and landowners may favor slash pine over loblolly for reasons other than wood yields. Slash pine would

be the favored species for landowners who want to sell

pinestraw for instance. Slash pine also prunes itself much

better than loblolly, and for solid wood products the lumber

grade will probably be higher for slash pine. This means

that loblolly would have to produce more lumber quantity

to stay even on value. Based on the differences in production on at least some of the soil types, loblolly may be able

to produce enough more wood to still be favored. That will

depend somewhat on the soil group and how the stand is

to be managed. Slash pine is more resistant to southern

pine beetle attack than loblolly and it is rarely bothered

with pine tip moth which can decimate young loblolly

stands. Planting both species across the landscape may

afford an ownership with less risk and the opportunity to

participate in different markets than going with either

species alone. As with most decisions in life, the choice of

species rarely rests with a comparison of only one characteristic. However, in terms of tons of wood produced, on

most sites loblolly pine will produce more wood than slash

pine. The decision to plant slash pine must then be made

because of it’s superiority by some other criterion.

LITERATURE CITED

Cole, D.E. 1975. Comparisons within and between populations of

slash and loblolly pine. Georgia For. Res. Counc. Pap. No. 81.

Macon, GA. 12 p.

Haines, L.W.; Gooding, J.; Wilhite, L. 1981. Site selection: slash

pine versus the other species. In: The managed slash pine

ecosystem. Sponsored by Institute of Food and Agric. Sci.,

Univ. of Florida, Gainesville, FL. 47 p.

Shiver, B.D.; Rheney, J.W.; Hitch, K.L. 2000. Loblolly pine outperforms slash pine in southeastern Georgia and northern

Florida. South. J. Appl. For. 24(1): 1-6.

Shoulders, E. 1976. Site characteristics influence relative performance of loblolly and slash pine. USDA For. Serv. Res. Pap.

SO-115, 16 p.







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Figure 6—Average total green weight (tons per acre) by species,

planting density, and management intensity for 6-year-old loblolly

and slash pine on the PMRC culture/density trials.
50

INTRODUCTION

Implementing site-specific silvicultural prescriptions is the

key to optimizing stand growth and financial returns in pine

plantations in the South. Selecting the appropriate species

of pine to plant on each site is perhaps the most difficult

decisions facing foresters during the regeneration process

in the Coastal Plain of Georgia and Florida. It is also the

most important decision, because the ultimate success or

failure of a plantation usually depends on this decision,

which is irrevocable.

The Coastal Plain of Georgia and Florida is characterized

by generally level topography with soils derived from relatively recent marine sediments (Huddlestun 1988, Randazzo

and Jones1997). This region is generally referred to as the

Flatwoods. Soils in the Flatwoods vary from excessively

well-drained sands to very poorly drained clays. These soil

differences frequently occur over very short distances, with

drastically different soils existing adjacent to one another

on the landscape. Minor changes in elevation of only a few

feet, have major impacts on soil drainage class, site quality

and tree growth. Disease hazard, including fusiform rust,

and annosus root rot, also varies widely across the region

(Anderson and Mistretta 1982). These factors contribute to

the diverse mosaic of site types in the region. Planting the

same species on all sites across the Flatwoods is almost

certainly going to produce poorly growing plantations or

even failures on many sites. Unfortunately, this approach

was employed by numerous organizations throughout the

South for many years. The legacy of this “one size fits all”

approach is evident in the number of poorly growing “off

site” plantations that still exist across the region.

The complexity of the species deployment decision in the

Flatwoods is greater than in other regions of the South

because four different species of southern pine are viable

alternatives. Slash pine (Pinus elliottii), loblolly pine (P.

taeda), longleaf pine (P. palustris), or sand pine (P. clausa)

may be the best species for a particular site. In other regions,

there are usually only two alternative pine species suitable

for planting, and in many cases only one.

The species deployment decision is also influenced by

changes in growth rate and disease resistance resulting

from tree improvement efforts. This is particularly true for

slash and loblolly pine. As gains from tree improvement

become available in genetically improved seedlings, the

deployment options for a given species change. For example, significant gains in fusiform resistance in slash pine

have been made through tree breeding , which now permits

successful deployment of slash pine to sites with higher

fusiform rust hazard (Hodge and others 1993). As advanced

generations of improved species produced through control

pollination, rooted cuttings and somatic embryogenesis

become available, the deployment decision will likely shift

from a species decision to a specific family or clone decision. In this scenario, an individual family or clone of a

given species may be best for a given site while a different

family or clone of the same species is not suitable.

THE CRIFF SOIL CLASSIFICATION SYSTEM

Soil properties determine site quality and thus strongly

influence the species deployment decision. Forest soils in

the Flatwoods of Georgia and Florida are classified taxonomically into six major soil orders including Alfisols,

Entisols, Histosols, Inceptisols, Spodosols, and Ultisols.

A large number of individual soil series are identified and

mapped by the USDA Natural Resource Conservation

Service, based on the physical and chemical properties of

the various soil horizons present. Unfortunately, the general soil maps that are prepared based on established soil

series are often not well suited for forestry applications

because soil properties important for silvicultural decisions

are not recognized. Consequently, forest site quality often

varies greatly within one soil series while different soil

series may have similar site qualities. It is often difficult to

SPECIES DEPLOYMENT STRATEGIES FOR THE SOUTHERN PINES:

SITE SPECIFIC MANAGEMENT PRACTICES FOR THE FLATWOODS OF

GEORGIA AND FLORIDA

Thomas R. Fox1

1 Thomas R. Fox, Associate Professor of Silviculture and Forest Soils, Department of Forestry, Virginia Polytechnic Institute and State

University, Blacksburg, VA 24061.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Four species of southern pine are commonly planted in the Coastal Plain of Georgia and Florida: slash pine

(Pinus elliottii), loblolly pine (P. taeda), longleaf pine (P. palustris), or sand pine (P. clausa). These species vary greatly in

their site requirements and growth rates. Appropriate deployment decisions must be made in order to insure adequate

survival, growth and yield of plantations. Species deployment options based on the silvical characteristics of the four

species and soil properties in the Flatwoods are discussed. A species deployment decision key is presented that

provides site specific recommendations for in the planting southern pines in the Flatwoods based on the CRIFF soil

group classification system.
51

accurately interpret existing soil maps and use the information to assist with silvicultural decisions without special

training in forest soils or considerable experience in the

area. Compounding the problem, published soil maps are

not available for large areas in the Flatwoods where row

crop agriculture is a minor land use. To overcome these

limitations, many industrial forest products companies

mapped soils on their own land to provide foresters the

tools needed to make site-specific silvicultural decisions.

However, these maps are proprietary and not usually

available to the general public.

The Cooperative Research in Forest Fertilization (CRIFF)

program at the University of Florida, recognized the need

for a simplified soil classification system that could be used

to improve silvicultural decisions. They developed a classification system that divides soils in the Flatwoods into 8

broad classes based on soil drainage class, soil texture

and depth to the B horizon (Fisher and Garbett 1980). These

CRIFF soil groups are useful tools in making site-specific

silvicultural decisions, including species deployment.

The properties of the eight CRIFF soil groups are presented

schematically in figure 1. The CRIFF A and B groups soils

are found in wet, mineral flats. They are very poorly to somewhat poorly drained and contain a fine textured B horizon

(clayey subsoil). In the CRIFF A group, the clayey subsoil

occurs within 20 inches of the surface while in the CRIFF B

group it is deeper than 20 inches. CRIFF A group soils are

locally referred to as “gumbo clays”. The CRIFF C and D

group soils are very poorly to moderately well drained soils

of the Flatwoods that contain a spodic horizon, which is a

reddish brown to black subsurface horizon containing

organic matter, iron and aluminum. This subsurface horizon

is often referred to locally as a “hardpan”. The surface soil

in CRIFF C and D group soils are sandy textured. The distinguishing feature separating CRIFF C and D group soils

is the presence of a clay horizon below the hardpan in the

CRIFF C group soil. CRIFF E and F soils are moderately

well drained to well drained soils that occur on uplands

that contain a fine textured B horizon (clay subsoil). They

are distinguished from one another by the depth to the clay

subsoil. In the CRIFF E group soil, the clay subsoil is within

20 inches of the surface while in the CRIFF F group it is

deeper than 20 inches. The CRIFF G group soils are well to

excessively well drained sandy soils, with no subsurface

horizons. These are the sandhill soils in the region. CRIFF

H group soils are muck (organic) soils that are very poorly

drained. They typically occur in hardwood swamps and

cypress ponds and strands.

Results from soil-site comparisons conducted as part of

large scale forest land classification programs in the

Flatwoods indicate that site quality, as measured by site

index, varies considerably within the CRIFF soil groups.

Site quality is related to soil drainage class (fig. 2). The

most productive soils tend to be somewhat poorly drained.

Site index decreases slowly as soils get wetter and more

rapidly as soils get drier.

SPECIES CHARACTERISTICS AFFECTING THE

DEPLOYMENT DECISION

The silvical characteristics of a species determine its ability

to survive, grow and compete on a particular site. The most

important silvical characteristics of slash, loblolly, longleaf

and sand pine affecting the deployment decision in the

Flatwoods include tolerance to anaerobic soil conditions,

drought tolerance, soil fertility requirements, relative growth

rate throughout the life of the tree, and insect and disease

resistance. The following discussion summarizes the important characteristics of each species that influences the

deployment decision using CRIFF soil groups to classify

sites.

Sand Pine

Sand pine is adapted to grow on excessively drained, infertile, deep sandy soils (Brendemuehl 1990). These soils are

included in the CRIFF G group. Sand pine is susceptible to

root rot diseases when it is planted on soils where fine textured horizons or a fluctuating water table occur within the

rooting zone. Stands planted where these conditions exist

within 10 feet of the soil surface almost always fail. Therefore, care must be exercised to insure that sand pine is

planted only on the deepest, driest sandhill soils. Sites

A BC D E F GH

0

20

40

60

VP to SWP VP to W MW to W E VP

Drainage class

Sand

Clay

Spodic

Organic

Depth (inch)

Figure 1—CRIFF soil groups.

X W M S P VP

Site index

Soil drainage class

Figure 2—Relationship between soil drainage class and site index

for slash pine on CRIFF soil groups in the flatwoods.
52

suited for sand pine are often smaller areas within larger

tracts. The presence of rosemary (Ceratiola ericoides) and

lichen mats (Cladonia spp.) are useful indicators of sites

suited for sand pine. In most cases, no other species of

pine will produce merchantable stands on the sites best

suited for sand pine. Although sand pine grows remarkably

well on these sites, it is often difficult to sell sand pine

stumpage, except during extremely wet periods. Therefore,

sand pine stumpage must be marketed opportunistically.

Longleaf Pine

Longleaf pine naturally occurs on a wide variety of sites in

the Flatwoods, from excessively drained, deep sandy soils

to poorly drained clay flats (Boyer 1990). Longleaf pine will

even occur on hummocks and other elevated micro topographic features in cypress ponds and muck swamps.

Although it occurs on a wide variety of sites, the growth rate

of longleaf pine is slower than that of slash and loblolly pine

except on moderately well, well drained and excessively

drained sandy soils with low site index (Wilhite 1976,

Shoulders 1990). These sites include CRIFF G group soils

and the moderately well and well drained CRIFF D group

soils. Longleaf is also suited for the well drained to excessively well drained soils in the CRIFF F group where the

clay is deeper than 5 feet. Longleaf is less susceptible to

insect and diseases than the other pines. Most importantly,

it is practically immune to fusiform rust, which is a serious

problem on the dry sandy sites best suited to longleaf pine.

Southern pine beetle is also seldom a serious problem in

longleaf pine. Longleaf does not tolerate competition,

whether from herbaceous vegetation or hardwoods (Boyer

1990). On sites with even moderate amounts of competing

vegetation, longleaf pine will remain in the grass stage for

extended periods. In the presence of competing hardwoods,

growth and yield of longleaf pine stands will be drastically

reduced. In the absence of competition, longleaf pine can

grow fairly rapidly on relatively poor sites. It has excellent

form and high stumpage value. Longleaf pine straw is an

important product in many stands. The value of pine straw

can exceed the timber value in some stands.

Slash Pine

Slash pine occurs on most soil types throughout the

Flatwoods, with the exception of the driest sandhill soils

(Lohrey and Kossuth 1990). Slash pine is often preferred

in local markets because it tends to have good form and

self prunes well (Koch 1972). Slash pine is less nutrient

demanding than loblolly pine and grows well on the infertile, wet, sandy soils that naturally occur in the region. Slash

pine is best suited to poorly drained to moderately well

drained soils in the CRIFF B, C and D groups. Slash pine

tends to be more plastic in its site requirements than loblolly pine in the Flatwoods. Consequently, the growth of

slash pine is more consistent than loblolly across the soil

and site differences that occur with minor topographic

changes in this region. For example, slash grows better in

the small, minor depressions that are common in this landscape where poorly and very poorly drained soils develop.

It appears to tolerates flooding better than loblolly pine,

although this may be an interaction with soil fertility because

many of the very poorly drained soils that flood periodically

tend to have low available phosphorus (Jokela 2004).

Susceptibility to fusiform rust is the most important factor

limiting slash pine deployment. Although genetically

improved slash pine are more rust resistant than non

improved sources, fusiform rust infection rates are unacceptably high on high rust hazard sites, even with genetically

improved families (Schmidt and others 1986). On well

drained soils in the CRIFF D and G groups, where rust

hazard is usually fairly high and site quality is poor, longleaf pine should be considered as an alternative to slash

pine. Slash pine is more resistant than loblolly to tip moth

and southern pine beetle attack. Anecdotal observations

comparing slash and loblolly pine in operational plantations

suggest that slash pine is less susceptible to nutrient deficiencies, and diseases such as needle cast. Slash pine is

very susceptible to ice and snow damage. Rust and glaze

hazards are the main factors limiting the slash pine deployment outside the Lower Coastal Plain of Georgia and

Florida.

Loblolly Pine

Loblolly pine is native throughout the Flatwoods region;

however, historically it was much less common than longleaf and slash pine in this region, occurring mostly on wetter sites along pond margins (Baker and Langdon 1990).

Loblolly pine was probably most prevalent in stands growing on wet clay soils where calcareous deposits such as

limestone and shell fragments were present in the rooting

zone. These sites, often locally referred to as hammocks,

typically supported stands containing mesic hardwoods

and included a significant component of cabbage palm

(Sabal palmetto). Loblolly pine has been widely planted on

a variety of soils types in the Flatwoods in recent years.

Loblolly pine tends to be more nutrient demanding than

slash or longleaf pine. On high fertility sites, or in stands

that are intensively managed, loblolly grows very well.

Loblolly grows best in the Flatwoods on CRIFF A group

soils, provided that the severe phosphorus deficiencies

commonly occurring on these soils are corrected through

fertilization (Jokela and others 1991). Loblolly also appears

well suited to the drier soils in the CRIFF E and F groups

where an argillic horizon is present. These soils are more

typical of the Upper Coastal Plain and Piedmont. However,

most soils in the Flatwoods, including CRIFF B, C and D

group soils, suffer from deficiencies of multiple nutrients,

including nitrogen, phosphorus, and potassium. Growth of

loblolly pine on these soils is generally poor unless balanced fertilizers are applied throughout the rotation. It may

be necessary to fertilize as often as every three to five years

to maintain acceptable growth rates in loblolly pine because

these sandy soils do not retain nutrients (Ballard and Fiskell

1974). On moderately well drained and well drained CRIFF

C and D group soils, loblolly pine tends to grow very poorly

even when intensively managed. Several instances of

sudden and complete mortality of young loblolly pine stands

in intensively managed research plots have been observed

on these soils. Loblolly pine should not be planted on these

soils. Fortunately, these drier sites can be recognized relatively easily using gallberry (Ilex glabra) as an indicator

species. Galberry becomes much less common and grows

less vigorously as drainage class changes from somewhat

poorly drained to moderately well drained. It tends to disappear completely from the understory shrub community on

well drained and drier sites in the Flatwoods.
53

Loblolly pine is much more resistant to fusiform rust than

slash pine, which is especially important because rust

hazard is usually high on CRIFF A, E and F soils where

loblolly grows best. Loblolly is much more susceptible than

slash and longleaf pine to southern pine beetle attack

(Thatcher and others 1980). Southern pine beetle hazard

is related to stand density, with increased susceptibility in

loblolly pine stands with basal areas greater than 100 ft2

per acre (Belanger and others 1993). Thinning dense loblolly stands and maintaining a mixture of loblolly and slash

pine stands across the landscape in the Flatwoods are

effective strategies for reducing southern pine beetle

incidence (Belanger and others 1993)

GROWTH RATE OF SLASH VERSUS

LOBLOLLY PINE

It is easy for most foresters to recognize the deep, droughty,

sandy soils where longleaf pine or sand pines are best

suited. In this regard, it is unfortunate that these dry, sandy

sites usually occur on a fairly small percentage of the landscape in the Flatwoods. On most sites in the Flatwoods,

foresters are faced with a more difficult species deployment

decision regarding slash versus loblolly pine. The fundamental question that continues to perplex foresters faced

with this decision in the Flatwoods is ‘What is the relative

growth rate of the two species?”. Over the years, numerous

studies have been published that compare the growth rate

of the two species (Wakely 1954, Shoulders 1976, Wilhite

1976, Haines and Gooding 1981, Shiver and others 2000).

The data from Shiver and others (2000) clearly demonstrates the effect of soil type on relative growth of slash and

loblolly pine (fig. 3). On the CRIFF A group soils (poorly

drained gumbo clays), loblolly pine grows much better

than slash pine. Loblolly also grows better than slash pine

on the upland well drained clay soils in the CRIFF F group.

On the CRIFF B, C and D group soils, that represent the

majority of sites in the Flatwoods, the growth of slash and

loblolly pine are similar. This occurred in spite of somewhat

lower overall survival of slash than loblolly pine on these

soil groups due to higher rust related mortality in the slash

pine (Shiver and others 2000).

At one time, site index was considered a fixed property

determined by the interaction of climate and soil properties.

It is now recognized that site index is strongly affected by

silvicultural inputs. For example, a stand growing on an

infertile soil with an inherently low natural site index, may

have a high “expressed” site index if an appropriate fertilization regime is employed. The expressed site index for a

stand is still an important property because it significantly

affects growth and yield in the stand. Results from Jokela

and others (2000) illustrate the impact of management

intensity on the relative growth of the two species and how

that would likely change the expressed site index (table 1).

On the CRIFF A and B group soils, which are inherently

very productive once phosphorus deficiencies have been

corrected, loblolly pine grew better than slash pine, regardless of treatment. However, it is clear that loblolly responded

more than slash pine to weed control and fertilization on

these soil types. Expressed site index will be much greater

on CRIFF A groups following phosphorus fertilization.

Volume growth through age 8 more than doubled from 713

ft3 per acre in the control to 1430 ft3 per acre in the weed

control plus fertilization treatment with loblolly pine while

growth increased much less in slash pine (499 ft3 per acre

vs 645 ft3 per acre), respectively in the two treatments. However, slash pine grew as well or better than loblolly on the

CRIFF C and D group soils. Again, both species positively

responded to fertilization and weed control and these silvicultural practices will significantly alter expressed site index

of the stand.

The above results illustrate how the relative growth rate of

the two species, and thus expressed site index, varies

depending on the soil type and the intensity of silviculture

used to manage the stand (Jokela and others 2000, Shiver

and others 2000). A general conclusion from these data is

that on better quality sites or those sites that are more intensively managed, loblolly pine generally grows better than

slash pine. On poorer quality sites, or those sites with less

intensive management, slash pine grows better than loblolly pine. On intermediate sites or with moderate levels of

silvicultural input, the growth of the two species will likely

be similar. Graphical site index comparisons for several

species have been developed in other parts of the United

States (Dolittle 1958). Figure 4 illustrates the generalized

relationship between the site index for slash pine and

loblolly pine in the Flatwoods. The dashed one-to-one line

Table 1—Stand volume after eight growing seasons for

slash and loblolly pine receiving fertilization and weed

control at establishment

CRIFF A and B soil CRIFF C and D soil

Treatment Loblolly Slash Loblolly Slash

- - - - - - - cubic feet per acre - - - - - - -

Control 713 499 452 733

Fertilization 1,202 605 598 761

Weed control 803 694 521 707

Fertilization plus

weed control 1,430 645 688 805

CRIFF = cooperative research in forest fertilization.

Source: Jokela and others (2000).

Figure 3—Merchantable volume production of loblolly and slash

pine through 14 years on different CRIFF soil groups in the

flatwoods of Georgia and Florida (Shiver and others 2000).





1

1

1

1

(',	 6

,=4..


 
*




*
0





8* 

.
54

represents points where the expressed site index of slash

and loblolly pine would be equivalent. The solid line represents the author’s view of the growth of the two species

based on observations in research trials and operational

plantations throughout the Flatwoods. At low expressed

site index (SI25 < 60), slash pine will generally grow better

than loblolly pine. At intermediate site index values (60 <

SI 25 <70), the growth of the two species will be about the

same. At high expressed site index values (SI25 > 70),

loblolly pine will grow better than slash pine.

SPECIES DEPLOYMENT DECISION KEY

A decision key for selecting the appropriate species to plant

in the Flatwoods is presented in figure 5. The decision key

consists of a series of questions that leads the user to a

recommended species. The decision key is based on CRIFF

soil groups, expressed site index (base age 25), depth to

subsurface soil clay or spodic horizons, and fusiform rust

hazard. The decision key is not intended to serve as a cookbook to be followed blindly. Rather, it provides a way to

systematically consider these factors that affect the decision

on which species to plant. Numerous factors can influence

which species is best suited for a particular site including

growth rate of previous stand, desire for species diversity

across the landscape, local rust hazard, projected silvicultural practices, genetic quality of the seed lots available for

planting, and local stumpage markets or mill requirements.

Several conventions and assumptions are used in the

decision key that should be recognized. The key frequently

requires the user to estimate site index. The key assumes

that this is the expressed site index (base age 25) for slash

pine. It used the relationship in figure 3 to determine which

species will grow better, and thus be the preferred species.

30

40

50

60

70

80

90

30 40 50 60 70 80 90

Slash pine site index

Loblolly pine site index

Figure 4—Relationship between slash pine and loblolly pine site

index (solid line) on CRIFF soils in the Flatwoods. The dashed line

represents the one-to-one relationship where site index of the two

species are equal. Below a site index of 60, slash pine will grow

better than loblolly pine. Between site index 60 and 70, growth of

the two species is equivalent. Above a site index of 70, loblolly

pine will grow better than slash pine.

Figure 5—Species deployment decision key for southern pines in the Coastal Plain of Florida and Georgia.

Species deployment decision key for southern pines in the 

Coastal Plain of Georgia and Florida

CRIFF soil group and drainage class

CRIFF G

Excessive and

somewhat excessive CRIFF E and F

Well, moderately well 

CRIFF C and D

Site index

< 40 >40

Sand

Rust Hazard 

Depth to clay

Longleaf

Low

Site index

< 60

Slash

> 70

Loblolly

Moderate 

to high 

Loblolly

Slash

Well to moderately 

well Loblolly

Loblolly

Slash Loblolly

> 5 feet < 5 feet

Drainage class

CRIFF A 

Somewhat poorly 

to very poorly

Somewhat

poorly to 

very poorly Rust hazard

< 60 > 70

Site index 

CRIFF B

Somewhat poorly

to very poorly

Rust hazard 

Low to 

moderate

High 

Slash or 

longleaf

Low to High 

moderate

Slash or 

loblolly

60 – 70

Loblolly 

or slash

(Note: Soils in CRIFF Group H are generally not well suited for pine management.)

60 – 70

.
55

Because expressed site index is so strongly affected by

management intensity, it assumes that the silvicultural treatments, such as weed control and repeated fertilization,

required to maintain that expressed site index will be maintained throughout the rotation. If future silvicultural inputs

are uncertain, it would be wise to use a conservative value

for the estimate of expressed site index.

The use of the key is illustrated in the following examples.

On a CRIFF G group soils that is excessively well drained

with an estimated slash pine site index of 45, longleaf pine

would be the recommended species. On a site with a

CRIFF C group soil that is somewhat poorly drained with

an expressed site index of 60, slash pine would be the

preferred species. On this same site, if more intensive silvicultural inputs were anticipated and the expressed site

index were estimated to be 68, the growth of slash and

loblolly would be roughly equal and either species would

be acceptable. If very intensive silvicultural practices were

applied and the expressed site index was expected to be

higher than 70, loblolly pine would be the preferred species

because at this level of productivity loblolly would produce

greater stand volume than slash pine.

LITERATURE CITED

Anderson, R.L.; Mistretta, P.A. 1982. Management strategies for

reducing losses caused by fusiform rust, annosus root rot, and

littleleaf disease. Agricultural Handbook No. 597. U.S. Department

of Agriculture, Forest Service. Cooperative State Research

Service. 30 p.

Baker, J.B.; Langdon, O.G. 1990. Pinus taeda L.: loblolly pine. In:

Silvics of North America: Volume 1. Conifers. Burns, Russell M.;

Honkala, Barbara H., tech. cords. Agricultural Handbook No. 654.

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

DC. 675 p.

Ballard, R.; Fiskell, J.G.A. 1974. Phosphorus retention in Coastal

Plain forest soils: I. relationship to soil properties. Soil Sci. Soc.

Am. Proc. 38: 250-255.

Belanger, R.P.; Hedden, R.L.; Lorio, P.L., Jr. 1993. Management

strategies to reduce losses from the southern pine beetle.

South. J. Appl. For. 17(3): 150-154.

Boyer, W.D. 1990. Pinus Palustris Mill. longleaf pine. In: Silvics of

North America: Volume 1. Conifers. Burns, Russell M.; Honkala,

Barbara H., tech. cords. Agricultural Handbook No. 654. U.S.

Department of Agriculture, Forest Service, Washington, DC.

675 p.

Brendemuehl, R.H. 1990. Pinus clausa (Chapm. ex Engelm.)

Vasey ex Sarg. sand pine. In: Silvics of North America: Volume 1.

Conifers. Burns, Russell M.; Honkala, Barbara H., tech. cords.

Agricultural Handbook No. 654. U.S. Department of Agriculture,

Forest Service, Washington, DC. 675 p.

Dolittle, W.T. 1958. Site index comparisons for several forest

species in the Southern Appalachians. Soil Sci. Soc. Am. Proc.

22: 455-458.

Fisher, R.F.; Garbett, W.S. 1980. Response of semimature slash

and loblolly pine plantations to fertilization with nitrogen and

phosphorus. Soil Sci. Soc. Am. J. 44: 850-854.

Haines, L.W.; Gooding, J. 1981. Site selection: slash pine versus

other species. In: Stone, E.L., ed. The managed slash pine

ecosystem. 1981 June 9-11; Gainesville, FL.: School of Forest

Resources and Conservation, University of Florida: 112-130.

Hodge, G.R.; White, T.L.; Schmidt, R.A.; Allen, J.E. 1993. Stability

of rust infection ratios for resistant and susceptible slash and

loblolly pine across rust hazard levels. South. J. Appl. For. 17(4):

188-192.

Huddlestun, P.F. 1988. A revision of the lithostratigraphic units of

the Coastal Plain of Georgia. The Miocene through Holocene.

Bull. 104. Dept. of Natural Resources, Environ. Protection Div.,

Georgia Geol. Surv. Atlanta, GA. 162 p.

Jokela, E.J. 2004. Nutrient management of southern pines. In:

Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds.

Slash pine: still growing and growing! Proceedings of the slash

pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southern Research

Station: 27-35.

Jokela, E.J.; Allen, H.L.; McFee, W.W. 1991. Fertilization of southern

pines at establishment. In: Duryea, M.L.; Dougherty, P.M. eds.

Forest Regeneration Manual. Kluwer Academic Publishers,

Dordrecth, The Netherlands. 263-280.

Jokela, E.J.; Wilson, D.S.; Allen, J.E. 2000. Early growth responses

of slash and loblolly pine following fertilization and herbaceous

weed control treatments at establishment. South. J. Appl. For.

24(1): 23-30.

Koch, P. 1972. Utilization of the southern pines. Vol. 1. The Raw

Material. Agricultural Handbook No. 420. U.S. Department of

Agriculture, Forest Service, Washington, DC. 734 p.

Lohrey, R.E.; Kossuth, S.V. 1990. Pinus elliottii Engelm. slash pine.

In: Silvics of North America: Volume 1. Conifers. Burns, Russell

M.; Honkala, Barbara H., tech. cords. Agricultural Handbook

No. 654. U.S. Department of Agriculture, Forest Service,

Washington, DC. 675 p.

Randazzo, A.F.; Jones, D.S., eds. 1997. The geology of Florida.

The University of Florida Press. Gainesville, FL 327 p.

Schmidt, R.A.; Holley, R.C.; Klapproth, M.C.; Miller, T. 1986.

Temporal and spatial patterns of fusiform rust epidemics in

young plantations of resistant slash and loblolly pines. Plant

Disease 70: 661-666.

Shiver, B.D.; Rheney, J.W.; Hitch, K.L. 2000. Loblolly pine outperforms slash pine in southeast Georgia and northern Florida.

South. J. Appl. For. 24(1): 31-36.

Shoulders, E. 1976. Site characteristics influence the relative

performance of loblolly and slash pine. Res. Pap. SO-115. U.S.

Department of Agriculture, Forest Service, New Orleans, LA.

16 p.

Shoulders, E. 1990. Identifying longleaf pine sites. In Farrar, R.M.

ed. Proceedings of the symposium on the management of

longleaf pine. Gen. Tech. Rep. S0-75. U.S. Department of

Agriculture, Forest Service. New Orleans, LA. 23-37.

Thatcher, R.C.; Searcy, J.L.; Coster, J.E.; Hertel, G.D., eds. 1980.

The southern pine beetle. Science and Educational Admin.

Tech. Bull. 1631. U.S. Department of Agriculture, Expanded

Southern Pine Beetle Research Applications Program. 266 p.

Wakely, P.C. 1954. Planting the southern pines. Agricultural

Monorgraph No. 18. U.S. Department of Agriculture, Forest

Service. Washington, DC. 233 p.

Wilhite, L.P. 1976. Slash, loblolly, longleaf and Sonderegger pines

20 years after planting on Leon sand in northeastern Florida.

Res. Pap. SE-153. U.S. Department of Agriculture, Forest

Service. Asheville, NC. 8 p.
56

INTRODUCTION

Private non-industrial forest (NIPF) landowners in the

Atlantic and Gulf Coastal Plain from South Carolina to

Mississippi question whether to plant loblolly or slash pine

on cut-over and old-field sites. They also question spending

moderate to relatively large sums of money in intensive

forest management under the current and anticipated

stumpage prices and economic uncertainty. To address

these questions, we used the Georgia Pine Plantation

(GaPPs 4.20) growth and yield Model developed by Bailey

and Zhao (1998). The data to develop the growth and yield

models for loblolly and slash were constrained to data up

to age 25-years. Therefore we used a 24-year rotation age

that had a mixed product class distribution of pulpwood,

chip&saw (C-N-S) and small sawtimber (ST). Generally

culmination of merchantable volume mean annual increment occurs for both species on average to good sites and

management in the early 20-years (Pienaar and others

1996). Older rotation ages are often financially attractive

but will not be addressed in this paper.

METHODOLOGY

Common Assumptions

The rotation age was set at 24-years for loblolly and slash

pine plantations. A discount rate of 8 percent was used to

calculate soil expectation value (SEV), annual equivalent

value (AEV), and internal rate of return (IRR). Fire protection cost was assumed to be $2 per ac. per yr., stand management at $2 per ac per yr and property taxes at $5 per

ac per yr. Thus, the total annual costs for each year of the

rotation was $9 per acre. This value cost goes in the transaction table as an annual cost during the rotation. The

present value of this net, annual cost flow is $94.75 during

the 24-year rotation. Results are reported in constant

dollars, before taxes.

Site preparation and planting costs totaled $250 per acre.

This cost could include a mechanical site prep treatment,

burn and plant or a herbicide, burn, plant, and herbaceous

weed control (Dubois and others 1999). Site preparation

options and associated costs vary extensively by location,

prior stand history, harvesting utilization, landowner objectives and monies available. The assumption used was that

level of site preparation intensity was matched to level of

competition control needed so that wood-flows were comparable within site productivity levels, after site preparation

and planting.

South Georgia stumpage Prices, reported through Timber

Mart-South© (TMS) for 4th quarter year 2000 average, used

in this analysis for loblolly and slash were net of property

taxes at harvest (2.5 percent) and net of marketing costs (8

percent). The low TMS prices for pulpwood and chip&saw

were used for thinning prices and average TMS prices for

pulpwood, CNS, and ST are used for the clearcut. Net converted prices are found in table 1. Product class specifications are: pulpwood at a d.b.h. of 4.5 to 9 inches to a 3 inch

top; CNS at a d.b.h of 9 to 12 inches to 6 inch top; and, ST

with a d.b.h greater than 12 inches to a 10 inch top (inside

bark). Product class stumpage prices are listed in table 2.

A fertilizer and application cost of $100 per ac for slash and

loblolly per application at age 6-years (slash) or 8-years

(loblolly) and 15-years-old was assumed. Fertilization with

150 then 200 N + 40 P (as diammonium phosphate and

urea) per acre was part of this scenario to maintain pine

straw production rates (Dickens 1999), to enhance wood

volume (NCSUFNC 1998), and change product class

distribution (Peinaar and Rheney 1996, Dickens 2001).

Fertilization timing at age 6-years-old was 2 years prior to

the initiation of straw raking (just prior to canopy closure).

The second application 7 to 9 years later was just after a

AN ECONOMIC COMPARISON OF SLASH AND LOBLOLLY PINE

UNDER VARIOUS LEVELS OF MANAGEMENT IN

THE LOWER ATLANTIC AND GULF COASTAL PLAIN

Coleman W. Dangerfield, Jr., E. David Dickens, and David J. Moorhead1

1 Coleman W. Dangerfield Jr., Forest Economics Professor; E. David Dickens, Associate Professor; and David J. Moorhead, Silviculture

Professor, Daniel B. Warnell School of Forest Resources, The University of Georgia, Athens, GA 30602-2152.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Non-industrial private forest (NIPF) landowners have perceived reduced product market availability and

increased price uncertainty since late 1997 in the southeastern United States. Lower Atlantic and Gulf Coastal Plain

NIPF landowners seek management options utilizing two commonly available pine species; loblolly (Pinus taeda L.) and

slash (Pinus elliottii, Engelm.) to enhance feasibility, profitability, and cash-flow of production forestry enterprises. At the

same time, NIPF landowners desire heightened flexibility across time required to achieve marketable forest products.

This study examines feasibility, profitability, and cash-flow of short-rotation management options affecting wood-flow for

slash and loblolly pine plantations including thinning, fertilization, and pine straw harvests under alternative levels of

stocking, productivity and product prices. Financial measures of profitability calculated include soil expectation value

(SEV), annual equivalent value (AEV), and internal rate of return (IRR).
57

thinning (thinning scenario)and after the response (wood

and straw) to the first application has become negligible.

The periodic fertilizer application costs are converted to

present values (PV) in year one, then re-computed as

annual equivalent values (AEV). These AEVs were then

put in the transaction table as annual expense cash-flows.

The pine straw income assumptions included were as follows: $50 and $100 per ac per yr raking income for slash

scenarios, and $25 and $50 per ac per yr for loblolly has

been noted in south (slash) and central (loblolly) Georgia

between 1998 and 1999 (Doherty 2000). Pine straw raking

starts in year 8 for slash and two years later (year 10) for

loblolly due to less contractor demand. Periodic pine straw

income was converted to present values (PV) in year one,

then re-computed as annual equivalent values (AEV) at the

discount rate of 8 percent. These AEVs were then put in the

transaction table as annual income cash-flows (table 3).

Table 1—Fertilizer periodic, per acre cost levels expressed as

present values and annual equivalent values as used in the

profitability analysis of slash and loblolly scenarios

Present value of AEV of the

Species Cost per acre Age a periodic cost periodic cost

years - - - - - - - cost per acre - - - - - - -

Loblolly 100 8, 15 81.05 7.70

Slash 100 6, 15 94.54 8.98

AEV = annual equivalent values.

Table 2—Cash and net (net of property taxes and marketing

costs) per cord stumpage prices used in the profitability analysis

of slash and loblolly scenarios

Price level Cash or net Pulpwood Chip&saw Sawtimber

 - - - - - - - - - cost per cord - - - - - - - - - -

Low Cash 18.36 83.96 88.65

Net 16.43 75.14 79.34

Medium Cash 24.15 92.85 107.51

Net 21.61 83.10 96.22

Source: TMS (2000).

Table 3—Pine straw periodic per acre income levels expressed as

present values and annual equivalent values as used in the profitability

analysis of slash and loblolly pine scenarios

Periodic income

per acre per Present value of AEV of

Species/scenario year raked periodic income periodic income

- - - - - - - - cost per acre - - - - - - - -

Loblolly w/thin 25 81.41 7.73

50 162.82 15.46

Loblolly w/o thin 25 95.47 9.07

50 190.93 18.13

Slash w/thin 50 208.75 19.83

100 417.50 39.65

Slash w/o thin 50 239.11 22.71

100 478.21 45.42

AEV = annual equivalent values.
58

The thinning scenarios include no thinning or one thinning

at 15-years-old. Total woodflow of scenario with thinning is

approximately 95 percent of total woodflow of scenario

without thinning for slash and loblolly without fertilization,

and 100 percent with fertilization. Residual basal area,

after thinning (5th row with selection from below) is set at

65 sq. ft per ac.

Species Specific Assumptions

The slash pine scenarios assumed 500 living trees per acre

(TPA) at age 5-years-old and a mean annual increment of

2.09 cds per ac per yr at age 24-years-old without fertilization. The base slash scenario woodflow was 15 percent

less than base loblolly woodflow (Shiver and others 1999)

at age 24-years. The assumed fertilizer applications will

conservatively increase merchantable volume by 0.4 cd

per ac per yr during for nine years following treatment

(Jokela and Stearns-Smith 1996).

The following are the nine slash pine scenarios: (a) no thinning, no pine straw income, and no fertilization costs, (b) thin

(at age 15-years to 65 ft2 per ac), no straw, no fertilization,

(c) no thin, fertilize at age 6- and 15-years-old, no straw,

(d and e) no thin, fertilize,(as c), and rake pine straw in

years 8 - 14 & 17 - 23 at $50 or $100 per ac per yr, (f) thin,

fertilize, no straw, (g and h) thin, fertilize, and rake straw

(as d and e), and (i) thin, fertilize, and pine straw at $100

per ac in years 8 through 14.

The loblolly pine survival was assumed to be the same as

slash (500 TPA at age 5-years-old). The mean annual

increment for loblolly was assumed to be 2.35 cds per ac

per yr through age 24-years-old without fertilization. The

base loblolly woodflow is approximately 15 percent greater

than the slash base woodflow (Shiver and others 2000) at

age 24. The assumed fertilizer applications will conservatively increase merchantable volume by 0.5 cd per ac per

yr for nine years (NCSUFNC 1998).

The following are the nine loblolly pine scenarios: (a) no

thin, no pine straw income, and no fertilization costs, (b)

thin (at age 15-years to 65 ft2 per ac), no straw, no fertilization, (c) no thin, fertilize at age 8- and 15-years-old, no

straw, (d and e) no thin, fertilize,(as c), and rake pine straw

in years 10 through 14 and 17 through 23 at $25 or $50

per ac per yr (f) thin, fertilize, no straw (g and h) thin,

fertilize, and rake straw (as d and e), and (i) thin, fertilize,

rake pine straw at $50 per ac in years 10 through 14.

RESULTS

The 2.09 and 2.35 cd per ac per yr productivity levels at age

24-years-old for slash and loblolly, respectively, are very

realistic on most cut-over sites with chemical site preparation and post-plant herbaceous weed control (Pienaar and

Rheney 1996) and is very conservative on most old-field

sites. The 0.4 (slash) and 0.5 (loblolly) cds per ac per yr

increase in wood production is conservative compared to

other published reports (Jokela and Stearns-Smith 1993,

Martin and others 1999, NCSFNC 1999) with nitrogen plus

phosphorus fertilization at ages 6 or 8 and 15-years. No

increase in pine straw income per acre was assumed with

fertilization. Fertilization studies (Blevins and others 1996,

Dickens 1999) illustrate that pine straw production can be

increased by an average of 40 to 50 percent over unfertilized stands. Fertilization was included in the pine straw

production scenarios to maintain straw production as

nutrients are removed/displaced with each raking.

All scenarios for both species achieved an internal rate of

return of 8 percent or better using the aforementioned

assumptions. Generally, the levels of forest management

are economically justifiable in these cases, even using low

to medium 2000 stumpage prices (TMS 2000) for South

Georgia.

Thinning loblolly and slash pine stands increased internal

rate of return by 11⁄2 percent (slash) to 2 percent (loblolly)

over unthinned stands (without pine straw income, tables 4

and 5). Thinning also increased total cash flow by $450

(slash) to $730 per acre (loblolly) compared to the

unthinned counterpart with no additional cost.

The addition of pine straw income for slash pine increased

rate of returns from 8.17 and 8.24 percent to 12.24 and

18.13 percent in unthinned stands (table 4). In thinned

slash pine stands, pine straw income increased rate of

returns from 9.71 to 13.84 percent and 19.62 percent

(table 5). Pine straw raking in the slash scenario prior to

thinning only (age 8 through 14-years) at $100 per ac per

yr produced a rate of return of 15.55 percent. Pine straw

raking in Georgia and North Florida typically does not

continue after a thinning, but often continues in South and

North Carolina.

Pine straw income in the loblolly scenarios increased rate

of returns from 8.91 and 8.96 percent in the unthinned

scenario to 10.10 and 11.36 percent (table 5). In the

thinned loblolly scenarios, pine straw income increased

rate of returns from 10.79 to 11.80 and 12.89 percent. Pine

straw raking in the loblolly scenario prior to thinning only

(ages 10 through 14-years) at $50 per ac per yr produced

a rate of return of 11.94 percent.

Fertilization with 150 N+40 P and 200 N + 40 P per acre at

ages 6 or 8-years (approaching canopy closure) and 15-

years-old, respectively in the unthinned slash and loblolly

scenarios increased cash flows by approximately $700 per

acre over the unfertilized scenario but at a cost of $200 per

acre. The highest SEV, AEV, IRR, and cash flow came from

the slash pine scenario with a thinning, fertilization, and

pine straw at $100 per ac per yr realized both pre- and

port-thinning. The unthinned, fertilized slash pine scenario

with pine straw income at $100 per ac had the second

highest SEV, AEV, IRR, and cash flow. The thinned,

fertilized, and pine straw raked prior to thinning produced

the third highest SEV, AEV, and IRR. When wood value

only is considered, loblolly produced more wood, more

wood value (a diameter driven function),a higher SEV,

AEV, IRR and cash flow with the aforementioned assumptions. Recent studies (Shiver and others 1999) have

shown that loblolly will grow more wood than slash on a

number of soils where both species are grown. Loblolly’s

superior wood volume yields do not necessarily equate to

higher per acre or per unit wood stumpage prices. Clark

(2002) noted that slash pine yielded more number one
59

Table 4—A comparison of slash pine plantation management scenariosa under a

24-year rotation and their effect on economic variables

Pine

Fertilization Thin straw Pulpwood MAI SEV AEV IRR

year 15 cost per acre percent cost per acre percent

N N N 62 2.09 20 2 8.24

N Y N 44 2.01 153 12 9.72

Y N N 48 2.33 18 1 8.17

Y N 50 48 2.33 365 29 12.24

Y N 100 48 2.33 711 57 18.13

Y Y N 38 2.37 179 14 9.71

Y Y 50 38 2.37 526 42 13.84

Y Y 100 38 2.37 873 70 19.62

Y Y 100b 38 2.37 641 51 15.55

MAI = mean annual increment of wood growth, cord equivalents per acre per year; SEV = soil

expectation value, calculated from perpetual rotations; AEV = annual equivalent value, net

present worth expressed as an annual annuity; IRR = internal rate of return of the investment

scenario (percent).

a Uninflated, 8-percent discount rate, before taxes, Georgia pine plantation v 4.20, general

Plantation Management Research Cooperative (PMRC) model with treatment.

b Age 8 to 15 years.

Table 5—A comparison of loblolly pine plantation management scenariosa under

a 24-year rotation and their effect on economic variables for southeast Georgia

Pine

Fertilization Thin straw Pulpwood MAI SEV AEV IRR

15 years cost per acre percent cost per acre percent

N N N 61 2.35 81 7 8.91

N Y N 38 2.32 300 24 11.07

Y N N 49 2.69 105 8 8.96

Y N 25 49 2.69 219 18 10.10

Y N 50 49 2.69 332 27 11.36

Y Y N 38 2.68 313 25 10.79

Y Y 25 38 2.68 410 33 11.80

Y Y 50 38 2.68 506 40 12.89

Y Y 50b 38 2.68 423 34 11.94

MAI = mean annual increment of wood growth, cord equivalents per acre per year; SEV = soil

expectation value, calculated from perpetual rotations; AEV = annual equivalent value, net

present worth expressed as an annual annuity; IRR = internal rate of return of the investment

scenario (percent).

a Uninflated, 8-percent discount rate, before taxes, Georgia pine plantation v 4.20, general

Plantation Management Research Cooperative (PMRC) model with treatment.

b Age 10 to 15 years.

lumber, had a slightly greater (4 to 11 percent greater)

density, and 4 percent less moisture content than loblolly

pine in growing in the same stand.

Non-industrial private forest landowners do have some

attractive forest management options with both slash and

loblolly pine even when using low to medium stumpage

prices. Until pine straw contractor preferences and pricing

change, where both slash and loblolly pine are grown,

slash pine is preferred where pine straw can be raked for

the higher per acre price.

LITERATURE CITED

Bailey, R.L.; Zhao, B. 1998. GaPPS 4.20 model. Warnell School of

Forest Resources- UGA, Athens, GA.

Blevins, D.; Allen, H.L.; Colbert, S.; Gardner, W. 1996. Nutrition

management for longleaf pinestraw - woodland owner notes.

NC Coop. Ext Serv. Paper.

Clark A., III; Daniels, R.F. 2002. Wood quality of slash pine and its

effect on lumber, paper, and other products. Presentation at the

Slash Pine Symposium. Jekyll Island, GA. April 23-25, 2002.
60

Dickens, E.D. 1999. The effect of inorganic and organic fertilization

on longleaf tree growth and pine straw production. In: Proceedings of the 10th Biennial So. Silvi. Res. Conf., Shreveport, LA,

Feb 16-18, 1999. pp. 464-468.

Dickens, E.D. 2001. The effect of one-time biosolids application in

an old-field loblolly pine plantation on diameter distributions,

volume per acre, and value per acre. In: Proceedings of the 11th

Biennial So. Silvi. Res. Conf., Knoxville, TN. March 19-22, 2001.

pp.

Doherty, B.A.; Teasley, R.J.; McKissick, J.C.; Givan, B. 2000.

Nineteen ninety-nine farmgate value report. UGA CAES Center

for Agribusiness and Econ. Dev., Center Staff Report No. 6.

Athens, GA. 160 p.

Dubois, M.R.; McNabb, K.; Straka, T.K. 1999. Costs and cost

trends for forestry practices in the South. Forest Landowner

Magazine. March/April 1998. pp. 3-8.

Jokela, E.J.; Stearns-Smith, S.C. 1993. Fertilization of established

southern pine stands: effects of single and split nitrogen treatments. SJAF 17(3): 135-138.

Martin, S.W.; Bailey, R.L.; Jokela, E.J. 1999. Growth and yield predictions for lower Coastal Plain slash pine plantations fertilized

at mid-rotation. SJAF 23(1): 39-45.

Morris, L.A.; Jokela, E.J.; O’Connor, J.B., Jr. 1992. Silvicultural

guidelines for pinestraw management in the SE US. GA Forest

Res. Paper #88. GFC, Macon, GA. 11 p.

NCSFNC. 1998. North Carolina State University Forest Nutrition

Coop - 26th annual report. School of Forest Resources, NCSU,

Raleigh, NC. 23 p.

Pienaar, L.V.; Rheney, J.W. 1996. Potential productivity of intensively managed pine plantations - final report. The GA

Consortium for Tech. Competitiveness in Pulp and Paper. 41 p.

Peinaar, L.V.; Shiver, B.D.; Rheney, J.W. 1996. Yield prediction for

mechanically site-prepared slash pine plantations in the southeastern Coastal Plain. PMRC Tech. Rep. 1996-3. 57 p.

Shiver, B.D.; Rheney, J.W.; Hitch, K.L. 1999. Loblolly pine outperforms slash pine in southeast Georgia and northern Florida.

SJAF 24(1) pp. 31-36.

TMS. 2000. Timber Mart South stumpage prices - 2nd quarter

south Georgia 2000.
61

INTRODUCTION

The South is the woodbasket for the United States, producing 58 percent of the timber harvested in the United States

and 16 percent of the World’s timber harvest (Wear and

Greis 2002). Most timber harvested in the South is southern pine, and slash pine (Pinus elliottii Engelm.) is one of

the more important pine species. Its wood properties make

it a desired species for manufacturing structural lumber,

structural plywood, poles, pilings, posts, pulp, and paper

products. This paper discusses those properties and considers why they are so important in lumber and paper

production.

WOOD PROPERTIES

Slash pine wood consists principally of closely packed

tracheid cells that run vertically up the stem, and parenchyma tissue or rays that extend horizontally from the pith

toward the bark. Tracheids make up more than 90 percent

of southern pine wood volume (Koch 1972) and, thus, the

properties of the tracheids determine the properties of the

wood. Tracheids are like long straws with tapered ends,

and whose cell walls surround an air space or cell lumen.

Cell walls have two major constituents—cellulose and

lignin.

Because the specific gravity (SG) of cellulose is almost

identical to that of lignin, the SG of cell wall substance is

considered to be constant for all wood species. Thus, wood

SG is an excellent and simple measure, independent of

species, of a wood’s total cell wall substance (Megraw

1985) and a moderate-to-high SG is universally accepted

as a desirable wood quality trait. The cell wall of a mature

tracheid consists of a primary wall or middle lamella,

composed largely of lignin, and a secondary wall that has

three layers: (1) the S1 (outer), (2) S2 (middle), and (3) S3

(inner) (Koch 1972). The S2, or secondary layer, makes up

the bulk of the tracheid wall. Cave (1976) showed that the

middle lamella and S1 and S3 layers remain essentially

fixed, while variation in volume of the S2 layer is solely

responsible for change in tracheid wall thickness. The

secondary wall layer consists of helically arranged cellulose microfibrils oriented in the long axis of the tracheid.

The orientation of the microfibrils relative to the long axis of

the tracheid is known as the microfibril angle (MFA). The

MFA is an important property in determining the stiffness

and dimensional stability of solid wood products.

When assessing wood properties of a species for end use,

it is important to consider SG, tracheid length, MFA, alpha

cellulose content, and lignin content. Each plays an important role in determining the suitability of a species for a

specific end use (table 1). Slash pine mature wood has SG,

tracheid length, MFA, alpha cellulose, and lignin contents

that make it highly desirable for solid wood products, such

as structural lumber and veneer. It also has wood properties that make it desirable for paperboard production, such

as kraft paper and sack paper. Slash pine mature wood is

less suitable for production of fine papers because of its

long tracheids with thick walls and corresponding high SG.

The weighted stem SG of slash pine wood, when averaged

across the species’ geographical range, is 0.53, compared

to 0.47 for loblolly pine (P. taeda L.) (Wahlgren and others

1975). The difference in SG between species is due to both

genetic and environmental factors. The weighted stem SG

of pine is determined by the amount of thick-walled, high

WOOD QUALITY OF SLASH PINE AND ITS EFFECT ON

LUMBER, PAPER, AND OTHER PRODUCTS

Alexander Clark III and Richard F. Daniels1

1 Alexander Clark III, Research Wood Scientist, U.S. Department of Agriculture Forest Service, Southern Research Station, Athens, GA

30602–2044; and Richard F. Daniels, Professor, University of Georgia, Warnell School of Forest Resources, Athens, GA 30602.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—The majority of timber harvested in the South, the woodbasket for the United States, is southern pine. Slash

pine (Pinus elliottii Engelm.) is one of the more important pine species harvested. Its wood has high specific gravity, long

tracheids, low microfibril angle, high alpha cellulose, and medium lignin content. The high specific gravity and branching

habit of slash pine make it an excellent species for manufacturing dimension lumber. When planted at wide spacings,

slash pine will produce a higher proportion of No. 1 and better lumber than loblolly pine (P. taeda L.) because of its

natural pruning and smaller diameter branching habit. The tracheid characteristics of slash pine make it an excellent

species for linerboard and sack paper production.

Table 1—Slash pine wood properties and desired wood

properties for southern pine wood products

Species Wood properties

and Specific Tracheid Alpha Lignin

product gravity length MFA cellulose contents

Slash pine High Long Low High Medium

Solid wood High Long Low High Medium

Paperboard High Long Low High Low

Fine paper High Short Low High Low

MFA = microfibril angle.
62

SG latewood tracheids produced each growing season.

The natural range of loblolly pine is large and extends from

Virginia to Texas and north to Tennessee and Arkansas,

whereas the range of slash pine is smaller and extends

only from the lower Coastal Plain of southeastern South

Carolina to the eastern Gulf Coastal Plain of Louisiana.

The SG of southern pines decreases from the Atlantic or

gulf coast inland because the inland trees have less

summer precipitation and a shorter growing season for

latewood production (Clark and Daniels 2004). Thus, the

SG of slash pine when averaged across its range is 11

percent higher than that of loblolly when averaged across

its range. However, differences between the species are

not as great when the species are growing in the same

geographic region.

To minimize the effect of environmental factors or geographic location on SG, we sampled slash and loblolly

pines planted in a study established by the Plantation

Management Research Cooperative (PMRC) administered

by the University of Georgia. That study’s objective was to

compare the growth of slash and loblolly pine when the

two species are growing together at 141 locations in south

Georgia and north Florida (Shiver and others 1996). Results

of the PMRC study at age 14 show that loblolly pine produced more volume per acre, had better survival because

of less Cronartium infection, and displayed less ice damage

compared to slash pine. We felled three trees of each species in each of six stands at age 21. The diameter of the

largest live or dead branch in each 8-foot section was

recorded, and cross-section disks were harvested from

along the stem for wood and bark SG, and moisture content

determination. Preliminary results show that when the two

species are growing together, the slash pine’s weighted

stem average SG was 4 percent higher than that of loblolly,

and its SG average was 0.51 compared to 0.49 for loblolly.

Thus, it appears that approximately 4 percent of the reported

difference in species average SG is probably related to

genetic or species differences and 8 percent is related to

environmental factors.

When pine tree-length logs are purchased at a mill yard

they are bought and sold on a weight basis, and a weightscaling factor is used to convert the weight of a truckload of

logs to cubic feet of wood. The weight-scaling factor is the

weight of wood and bark per cubic foot of wood. Based on

disks collected from the two species where they were growing together, we found that the slash contained 4 percent

more dry wood because of its higher SG, 12 percent less

water, and 3 percent more bark than the loblolly trees

(table 2). The average weight-scaling factor for slash was

72.5 pounds per cubic foot compared to 70.4 pounds per

cubic foot for loblolly when the two species were growing

in the same stands. Although loblolly has a higher wood

moisture content than slash pine, the weight-scaling factor

for slash pine is higher because it has a higher SG and,

thus, contains more oven-dry wood per cubic foot and

more bark per cubic foot than loblolly.

LUMBER GRADE YIELD

When visually grading southern pine structural lumber, one

of the most important defects to evaluate is diameter of

knots in relation to width of a board. In a No. 1 grade 2 by

4, the largest centerline knot allowed under southern pine

dimension grading rules (Southern Pine Inspection Board

1994) is 1.5 inches width, and the largest centerline knot

allowed in a No. 2 grade 2 by 4, is 2.0 inches. When growing

in fully stocked stands, slash pine generally has smaller

diameter branches and is a better natural pruner than

loblolly pine, and, thus, it produces a greater proportion of

higher grade lumber.

The diameter of the largest branch in each 8-foot saw-log

stem section was plotted over stem height for 21-year-old

slash and loblolly pine trees growing in the same stand

planted at the same spacing (fig. 1). On average, the loblolly trees had larger diameter knots than the slash trees.

Based on average maximum knot size, No. 1 or better 2 by

Table 2—Average wood and bark properties for

planted 21-year-old slash pine compared to

loblolly pine when the species are growing in the

same stand

Slash Loblolly

Property pine pine

Wood specific gravity 0.51a 0.49b

Wood oven-dry weight per

cubic foot (pounds) 31.9a 30.5b

Wood green weight per

cubic foot (pounds) 63.0a 63.7a

Wood moisture content

(percent) 97a 108b

Bark content (percent) 13.3a 9.8b

Within a property, values with a different letter are statistically different at the 0.05 level.

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

0–8 8–16 16–21 24–32 32–40 40–48

Height level (feet)

Branch diameter (inches)

Loblolly

Slash

Figure 1—Average maximum branch diameter by 8-foot intervals

up the stem of slash pine compared to loblolly pine when both

species are growing in the same 21-year-old stand.
63

4 lumber could be manufactured from the butt 16-foot saw

log of both species. The second 16-foot slash pine saw log

could also produce all No. 1 and better 2 by 4 lumber; however, the second loblolly log would produce some No. 2

grade 2 by 4 lumber because of the knots > 1.5 inches in

diameter. The third 16-foot slash log could produce all No.

2 and better 2 by 4 lumber; however, in the loblolly trees a

portion of the 2 by 4 lumber from the third log would have

to be trimmed back to remove knots larger than 2.0 inches

to make No. 2 grade 2 by 4 lumber. Thus, the slash trees

generally produced a higher proportion of No. 1 and better

lumber.

The branching habit and natural pruning of slash pine also

affect lumber yield, as illustrated in the lumber grade yield

of a first thinning in a 17-year slash and 14-year loblolly

pine stand.2

 The loblolly pine was planted at 600 trees per

acre (TPA) in 1983 in a planting density plus competition

control study on the University of Georgia, B.F. Grant

Memorial Forest in the Piedmont of Georgia (Pienaar and

Shiver 1993). In 1997, when the loblolly plantation was 14

years old, the study plots were marked for thinning. The

slash pine trees came from the site-preparation and soiltype study planted in 1979 at 545 TPA by the PMRC in the

lower Coastal Plain (Shiver and others 1994). The study

was established at 20 sites ranging from Savannah, GA, to

Apalachicola, FL.

In 1997, when the plantation was 17 years old, four trees

from each of eight locations were marked for thinning from

the site-preparation plus competition control study plots.

The 32 loblolly and 32 slash trees were processed into 2-

by 4-inch and 2- by 6- inch lumber at the same chipping

sawmill on the same day. The lumber produced from each

log was followed through the mill, kiln dried, planned, and

graded using Southern Pine Inspection Bureau (Southern

Pine Inspection Bureau 1994) lumber grades. When a

board did not make a No. 2 or better, the reason for the

downgrade was recorded.

Ninety-seven percent of the lumber produced from the 17-

year slash pine was No. 2 or better compared to only 80

percent for the 14-year loblolly pine. The slash pine produced a significantly higher proportion of No. 1 and better,

a lower proportion of No. 2, and a significantly lower proportion of No. 3 and No. 4 lumber compared to that of the

loblolly pine (table 3). Three percent of the slash pine lumber and 3 percent of the loblolly lumber was downgraded

below a No. 2 because of manufacturing defects (wane and

skip). The proportion downgraded below a No. 2 because

of drying defects (bow, twist, or crook) was 4 percent for

loblolly compared to 2 percent for slash. Lumber that contains < 15 percent latewood is classified as exceptionally

light weight and cannot be included in No. 2 nondense or

higher grades of stress-rated lumber (Southern Pine

Inspection Bureau 1994). Less than 1 percent of the slash

pine lumber was downgraded because of insufficient latewood compared to 5 percent of the loblolly lumber. A significantly larger proportion of loblolly lumber was downgraded because of drying defects or insufficient latewood,

because the loblolly trees were growing in the Piedmont

and contained twice as much juvenile wood as the slash

pine growing in the lower Coastal Plain (Faust and others

1999). The Piedmont loblolly pine produced juvenile wood

with thin-walled tracheids, wide MFA, and a small proportion of thick-walled latewood tracheids for 9 to 10 years

compared to the lower Coastal Plain slash, which produced

juvenile wood for only 5 to 6 years. The difference in time

until mature wood production is probably more related to

physiographic region than to species. Clark and Daniels

(2003) showed that loblolly pine grown in the Coastal Plain

also transitioned to mature wood production in the 5- to 6-

year range. Less than 0.5 percent of the slash pine lumber

was downgraded below a No. 2 because of knot size,

compared to 7 percent of the loblolly lumber. A significantly

higher proportion of the loblolly lumber was downgraded,

because the average loblolly log had more knots (24 knots

vs. 17 knots for slash pine), and the maximum diameter

knot was significantly larger for the loblolly (1.7 inches

compared to 1.3 inches).

When loblolly pine is planted at wide spacings, the trees

produce large diameter branches that result in a high proportion of No. 3 and worse lumber and a low proportion of

No. 1 and better (Clark and others 1994). A simulated final

harvest of loblolly pine at age 38 showed stands planted at

6 by 6 feet and thinned to ≤ 100 square feet basal area (BA)

at age 18 produced ≥ 60 percent No. 2 and better lumber

compared to ≤ 42 percent No. 2 and better lumber from

stands planted 12 by 12 feet and thinned to the same BA.

In contrast, when slash pine is planted at wide spacings

and harvested at age 40, the trees produced 90 to 95 percent No. 2 and better lumber (fig. 2). When initial spacing is

increased from 8 by 8 feet to 10 by 10 or 15 by 15 feet, the

proportion of No. 2, No. 1, and dense grade lumber remains

relatively constant because of slash pine’s characteristic

2 small diameter branches and early natural pruning. Clark, A., III; Shiver, B.D.; Pienaar, L.V. 2004. Effect of initial

spacing and competition control on lumber grade yield of young

fast-growing southern pine. 20 p. Unpublished report. On file with:

A. Clark, III, U.S. Department of Agriculture Forest Service,

Southern Research Station, 320 Green Street, Athens, GA

30602.

Table 3—Average proportion of dimension

lumber produced by grade for 17-year slash

pine planted at 545 TPA in the lower Coastal

Plain compared to 14-year loblolly pine planted

at 600 TPA in the Piedmont

Lumber grade Slash pine Loblolly pine

 - - - - - - - - percent - - - - - - - -

No. 1 and better 53 21

No. 2 44 59

Nos. 3 and 4 3 20

TPA = trees per acre.
64

PULP AND PAPER YIELDS

Slash pine is not only an excellent species for structural

lumber production, it is also good for linerboard and sack

paper manufacturing. Wood for paper production can come

from the whole stem, saw-log residues, or topwood above

the saw-log stem. The 17-year-old slash pine trees harvested

for lumber-yield analysis from the PMRC site-preparation

and soil-type study were subsampled for pulp and paper

analysis (Courchene and others 2000). Cross-section disks

were cut at the butt, the top of each saw log, and from the

6-, 4-, and 3-inch diameter outside bark top. The chipping

saw chips (CSC) were collected when the saw logs were

sawn into lumber. The disks were chipped to provide pulp

chips representing the whole tree and tops, and the CSC

represented sawmill residue. The weighted whole stem SG

averaged 0.52, saw-log stem SG averaged 0.53, and the

topwood SG averaged 0.45. The SG of topwood was significantly lower because of the large proportion of thin-walled

juvenile wood tracheids present. The packed bulk density,

a measure of the weight of chips that can be packed into

unit area for digesting, was highest for the whole stem

(175 kg/m3) and CSC (189 kg/m3), and significantly lower

for the topwood chips (157 kg/m3

).

One-half of the chips from each wood source were pulped

in a batch digester to a kappa no. 90 for linerboard production, and the other half was pulped to a kappa no. 60 for

sack paper production. Because slash pine is a high SG

southern pine species, it has a high yield when pulped.

Pulp yields for the kappa no. 90 cooks averaged 54 percent

for the whole stem and CSC, compared to only 51 percent

for the topwood chips. The pulp yields for the kappa no. 60

averaged only 47 percent for topwood compared to 50 percent for the whole stem and CSC. The weighted average

tracheid lengths for the CSC, composed primarily of mature

wood, averaged 4.1 mm for the kappa no. 90 and 3.9 mm

for the kappa no. 60. The average length of tracheids in the

topwood, composed primarily of juvenile wood, was significantly shorter averaging 3.3 mm for the kappa no. 90 and

3.5 mm for the kappa no. 60.

To test paper properties, hand sheets were made from the

sack paper and linerboard pulps. The topwood chips produced linerboard that was higher in short span compression, burst strength, tensile strength, and specific modulus

compared to the linerboard made from the whole stem or

CSC (table 4). The topwood hand sheets were higher in

strength properties because of the higher percentage of

thinner walled juvenile tracheids in topwood. The thinwalled tracheids collapsed around each other and, thus,

increased bonding and corresponding higher burst,

tensile, and compression strength.

The sack paper hand sheets made from the topwood chips

were higher in sheet density, short span compression, burst,

tensile strength, and specific modulus, but significantly

lower in tear resistance than the sheets made from the

whole stem or CSC (table 5). The sack paper hand sheets

were significantly lower in tear resistance because of the

significantly shorter tracheids in the topwood compared to

that of the whole stem or CSC.

0

10

20

30

40

50

60

70

80

90

100

8 X 6 8 X 8 10 X 10 15 X 15

Spacing (feet)

Lumber recovery (percent)

Dense

No.1 and btr.

No. 2

No. 3 and 4

Figure 2—Effect of initial spacing on dimension lumber grade

recovery for 40-year-old unthinned slash pine.

Table 4—Average properties of linerboard hand sheets manufactured from

whole stem chips, chipping saw chips, and topwood chips produced from

17-year-old slash pine growing in the lower Coastal Plain

Short-span

Sheet compressive Burst Tensile Specific

Chip source density test index index modulus

kg/m3 N m/g kPa m2 /g N m/g N m/g

Whole stem chips 715 26.7 5.20 54.2 5550

Chipping saw chips 645 27.2 5.13 49.6 5260

Topwood chips 717 30.02 5.53 72.5 7010

kg/m3 = kilograms per cubic meter; N m/g = Newtonmeters per gram;

kPa m2/g = kilopascals square meters per gram.
65

SUMMARY

Slash pine wood SG is higher, wood moisture content is

lower, and bark content higher than that of loblolly pine.

Thus the weight-scaling factor, weight of wood, and bark

per cubic foot of wood is higher for slash pine than loblolly

pine. The high SG and branching habit of slash pine make

it an excellent species for manufacturing dimension lumber.

Because of the small diameter branches and early natural

pruning, slash pine produces more No. 1 and better dimension lumber and less No. 3 and No. 4 lumber than loblolly

pine. When planted at wide spacings, slash pine will produce a higher proportion of No. 1 and better lumber than

loblolly pine because of its natural pruning and smaller

diameter branching habit. The tracheid characteristics of

slash pine make it an excellent species for linerboard and

sack paper production. The lower SG, thin-walled tracheids

of topwood chips produce linerboard with higher strength

properties than those of whole stem or CSC. However, the

whole stem and CSC produced sack paper with higher

tear resistance than topwood chips because of the longer

tracheids.

LITERATURE CITED

Cave, I.D. 1976. Modeling the structure of the plant cell wall. Wood

Science Technology. 2: 268-278.

Clark, A.; Daniels, R.F. 2004. Modeling the effect of physiographic

region on wood properties of planted loblolly pine in the

Southern United States. In: Nepveu, G., ed. Proceedings, connection between forest resources and wood quality, modeling

approaches and simulation software. IUFRO WP S5.01.04.

Nancy, France: LERFoB/2004 INRA-ENGREF: 54-60.

Clark, A., III; Saucier, J.R.; Baldwin, V.C.; Bower, D.R. 1994. Effect

of initial spacing and thinning on lumber grade, yield and

strength of loblolly pine. Forest Products Journal. 44 (11/12):

14-20.

Table 5—Average properties of sack paper hand sheets manufactured

from whole stem chips, chipping saw chips, and topwood chips

produced from 17-year-old slash pine growing in the Lower Coastal

Plain

Sheet Tear Burst Tensile Specific

Chip source density index index index modulus

Kg/m3 mN m2 /g kPa m2/g N m/g N m/g

Whole stem chips 630 19.9 5.80 73.7 6690

Chipping saw chips 618 20.0 6.03 68.3 6320

Topwood chips 670 17.6 7.03 88.5 7570

Kg/m3 = kilograms per cubic meter; mN m2/g = milliNewtons square per gram;

kPa m2/g = kilopascals square meters per gram; N m/g = Newtonmeters per gram.

Courchene, C.E.; Clark, A., III; Belli, M.L. [and others]. 2000. Effect

of intensive silvicultural treatments on kraft pulp quality of

loblolly and slash pine. In: Proceedings, 2000 TAPPI pulping/

process & product quality conference. Boston: TAPPI Press:

210-219.

Faust, T.D.; Clark, A., III; Courchene, C.E. [and others]. 1999.

Effects of intensive forest management practices on wood

properties and pulp yield of young, fast growing southern pine.

In: 1999 Proceedings, TAPPI international environmental

conference. Atlanta: TAPPI Press: 501-512.

Koch, P. 1972. Utilization of the southern pines. The raw material.

Agric. Handb. 420. Washington, DC: U.S. Department of

Agriculture, Forest Service. 734 p. Vol. I.

Megraw, R.A. 1985. Wood quality factors in loblolly pine. Atlanta:

TAPPI Press. 88 p.

Pienaar, L.V.; Shiver, B.D. 1993. Early results from an old-field

loblolly pine spacing study in the Georgia Piedmont with

competition control. Southern Journal of Applied Forestry. 17(4):

193-196.

Shiver, B.D.; Pienaar, L.V.; Hitch, K.L.; Rheney, J.W. 1994. Slash

pine site preparation study results at age 14. PMRC Tech. Rep.

1994-2. Athens, GA: University of Georgia, Warnell School of

Forest Resources. 32 p.

Shiver, B.D.; Rheney, J.W.; Hitch, K.L.; Shackelford, L. 1996. 14

year results of the PMRC species comparison study. PMRC

Tech. Rep. 1996-4. Athens, GA: University of Georgia, Warnell

School of Forest Resources. 15 p.

Southern Pine Inspection Bureau. 1994. Standard grading rules

for southern lumber. Pensacola, FL: Southern Pine Inspection

Board. 133 p.

Wahlgren, H.E.; Schumann, D.R.; Bendtsen, B.A. [and others].

1975. Properties of major southern pines: part I–wood density

survey; part II–structural properties and specific gravity. Res.

Pap. FPL 176–177. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 76 p.

Wear, D.N.; Greis, J.G. 2002. Southern forest resource assessment: summary of findings. Journal of Forestry. 100(7): 6-14.
66

HISTORICAL PERSPECTIVES

Role of Fire in Natural Slash Pine Ecosystems

Wildland fires have been a prominent force shaping the ecosystems of the southeastern United States for thousands of

years. Evidence suggests that Native Americans set fires for

centuries before the arrival of European settlers (Robbins

and Myers 1992). Even before humans began using fire as

a tool in North America, the climate and vegetation of the

southeastern United States supported frequent wildfires

ignited by lightning during the growing season (Frost 1998).

The climate in the Southeast is characterized by long, hot

growing seasons with thunderstorms, annual cycles of wet

and dry seasons, and periodic extended droughts (Wade

and others 2000). After thousands of years of exposure to

frequent fires, plant communities evolved mechanisms to

survive fire, and in some cases, they developed a dependence on fire for their maintenance.

In pine flatwoods forests of the southeastern Coastal Plain,

fire frequency, which is related to site hydrology, influences

the natural distribution of slash pine (Pinus elliottii), longleaf pine (Pinus palustris) and many other species. The two

pines often occur together on the landscape with slash

pine occupying wetter sites. Slash pine develops naturally

in poorly drained, low elevation areas that frequently flood

during major rain events (Abrahamson and Hartnett 1990,

Lohrey and Kossuth 1990), while longleaf pine occurs on

better-drained sites (Monk 1968). Due to moist site conditions and fewer fine (grass) fuels, natural slash pine communities burn less frequently and completely than the drier,

surrounding longleaf pine communities (Christensen 1981).

Historically, probable fire return intervals in slash pine were

6 to 10 years, while longleaf pine burned every 2 to 4 years

(Landers 1991). South Florida slash pine (P. elliottii var.

densa) inhabits sites with similar conditions and fire frequencies (every 3 to 7 years) as longleaf pine.

Longer fire return intervals on typical moist slash pine sites

are important for slash pine regeneration because seedlings are not fire resistant during their first four years of

growth. Their fire resistance increases once they reach a

height of 10 to 15 feet (Lohrey and Kossuth 1990), with 10-

to 12-year-old slash pine capable of surviving many surface

fires (Wright and Bailey 1982). Historically, the susceptibility of young slash pine seedlings to fire precluded their

encroachment into adjacent longleaf pine stands where

shorter fire return intervals were common. South Florida

slash pine seedlings are more resistant to fire than the

typical variety; they have thicker bark and enter a grass

stage similar to longleaf pine (Ketcham and Bethune 1963,

Abrahamson 1984). As slash pine matures, it is able to

survive moderately intense fires. The species characteristically has thick bark with platy layers that overlap to provide

substantial insulation from fire (Landers 1991). In addition,

slash pine has the capacity to recover from 70 to 100 percent crown scorch (de Ronde 1982, Wade 1983).

Different fire frequencies in pine flatwoods ecosystems

lead to differences in understory vegetation, fuel loading

and fire intensities. Fires in typical slash pine stands are

more intense than in longleaf pine or South Florida slash

pine due to the presence of highly flammable shrubs such

as palmetto (Serenoa repens) and gallberry (Ilex glabra),

greater vertical structure, and heavy needle drape (Hough

and Albini 1978). However, crown fires are rare in natural

slash pine stands because trees self-prune the lower

PRESCRIBED FIRE AND SLASH PINE

A.J. Long, A. Behm, L. Cassidy, J. DiMartino, D. Doran, D. Freeman, J. Helmers, K. Keefe,

A. Miller, S. Ranasinghe, C. Randall, M. Rasser, A. Ruth, D. Shipley, and A. Van Loan1

1 A.J. Long, Associate Professor, School of Forest Resources and Conservation, University of Florida, Gainesville, FL 32611-0410; Behm,

Cassidy, DiMartino, Doran, Freeman, Helmers, Keefe, Miller, Ranasinghe, Randall, Rasser, Ruth, Shipley, and Van Loan, Graduate

Students, University of Florida, Gainesville, FL 32611-0410.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Fire has been a significant ecosystem process in the Southeast for thousands of years. It kept slash pine in

the wetter parts of the flatwoods pine forests historically. Today, when slash pine covers a much larger landscape, fire

still plays an integral role in its management. Wildfire has had some extreme moments in slash pine plantations where

understory shrubs were dense from a lack of prescribed fire or other treatment. However, prescribed fire has also been

an important tool for regenerating natural and plantation slash pine as well as for restoring longleaf pine in place of

slash. Prescribed fire is also used in slash pine systems for reducing fuel accumulations, improving wildlife and range

habitat, and enhancing accessibility. Fire will continue to be an essential, and sometimes critical, element in the slash

pine system. Wildfires in the wildland-urban interface and smoke management are significant public issues and

influence opportunities for prescribed burning. Future application of prescribed fire will be dependent on policies and

issues related to public acceptance, health and safety. Landowner and public education will be critical components of

future fire management programs. Since the last Slash Pine Symposium, research, objectives for fire management, and

the wildland fire environment have changed substantially. This paper will build on the excellent baseline provided by

Wade (1983) at that Symposium. We will repeat some of the important principles outlined in earlier work, but our focus is

on new information and challenges in the last two decades.
67

branches, frequent fires prevent heavy fuel buildup, and

stands are open (Hough and Albini 1978, Abrahamson

1984). Other natural disturbances, such as hurricanes and

pest outbreaks, can also affect fire behavior and severity

by changing the fuel structure and loads. The shorter fire

return intervals in longleaf pine maintain an understory of

grasses and forbs that burn with low intensities

(Abrahamson and Hartnett 1990). South Florida slash pine

has an understory composed of various species of

subtropical hardwoods, shrubs, and palms in addition to

grasses (Abrahamson and Hartnett 1990, Landers 1991).

In the absence of fire, slash pine ecosystems may develop

along one of several successional pathways, depending

on site conditions (Abrahamson and Hartnett 1990). On

wetter sites, plant succession moves toward cypress or hardwood swamps, cabbage palm hammocks (Edmisten 1963),

or bayheads (Monk 1968, Peroni and Abrahamson 1986).

Better drained sites may develop into mesic southern

mixed hardwoods.

Human Management and Consequences

Presettlement—Human occupation of the southeastern

United States began approximately 12,000 years ago. The

environment they encountered was probably vastly different

from the one with which we are familiar, with indications that

the area was then a semi-arid savannah. Climate changes

since then included a period approximately 7,000 years

ago that was much wetter than the present (Brown 1994).

As was the case elsewhere in the pre-Columbian Americas,

one of the first uses of fire was to promote growth of favored

food plant species over less desirable plants (Lentz 2000).

Anthropological records suggest that fire may have been

used for maize production and swidden (slash and burn)

farming around 1,200 years ago. Fire was also used in

hunting to flush out game, primarily deer. These two activities were often done jointly: when an area needed to be

cleared for fields, fires would be lit in a circle, and the game

would be hunted as it was driven out of the enclosed area

by the fire (Brown 1994). Fire was also used to attract game

to areas with new succulent grass and forbs, to improve

accessibility, and possibly in warfare (Wade 1983).

Studies in the Mississippi River Valley suggest that most

large fires were not anthropogenic. Fires set by people

tended to be localized. Hunting fires as well as those set to

alter vegetation, while frequent, were typically less than

3 miles wide (Fritz 2000). Another human effect on fire

regimes might have been through the collection of dead

wood for domestic fuel, resulting in lower fire intensities

(Fritz 2000).

Early 1900s vs late 1900s—wildfire vs prescribed

burning—Like the Native Americans, the earliest European

settlers were more interested in farming than in forestry

(Wade 1983). In the South, the local custom was to burn in

forests every winter, to remove litter and dead grass and to

make new spring grass available for cattle grazing. Fire was

also used to: protect fences, farm buildings, and turpentine

orchards from high intensity wildfires; control insects and

pests; and to maintain an open landscape for hunting.

Between the late 1800s and early 1900s the indiscriminate

use of fire after timber harvesting often resulted in high

intensity burns and damage to residual timber and human

settlements. As a result, federal and state policies in the

early 1900s focused on protecting forests from all fires.

During this period of blanket fire suppression, the benefits

of ‘controlled’ fire were noted by various authors (for example, Demmon 1935, Stoddard 1931) and by professional

foresters such as Austin Cary and H.H. Chapman. Apparent

contradictions in the effects and benefits, coupled with some

disastrous wildfires in the 1940s, contributed to the recognition of a need for balance between the use and suppression

of fire. The need for balance between suppression and use

was highlighted in the longleaf-slash pine ecosystem,

where fire suppression allowed slash pine to expand into

the drier areas historically dominated by longleaf pine. By

the mid 1940s prescribed fire was acknowledged as a necessary tool for managing vegetative fuels and ecosystems.

ENVIRONMENTAL EFFECTS OF FIRE

Vegetation Communities

Effect of fire on species composition—With the suppression of fires and expansion of plantations, slash pine now

occupies a greater range and variety of sites than it did

naturally. In most of these areas, fire is a very important

ecological factor that determines forest structure and species

composition. In typical flatwoods, the primary understory

species include: gallberry, saw palmetto, wax myrtle (Myrica

cerifera), Vaccinium spp, fetterbush (Lyonia lucida) and

persimmon (Diospyros virginiana). In wetter areas species

such as red maple (Acer rubrum), sweetgum (Liquidambar

styraciflua), black gum (Nyssa sylvatica), water oak (Quercus

nigra) and laurel oak (Q. laurifolia) gradually dominate the

midstory.

Periodic fires prevent the less fire adapted hardwood species from invading and maintain an understory comprised

of grasses, especially wiregrass (Aristida stricta) and bluestem (Andropogon spp.), forbs and a few shrubs that are

well adapted to such disturbances. Prescribed burns can

maintain the grass and forb understory if frequent enough

to reduce existing shrub species. Depending on site characteristics, prescribed fire applied in different seasons

affects the understory in different ways. Kush and others

(2000) found that winter burns resulted in a greater increase

in overall species diversity than summer or spring burns.

On the other hand, experience on the Apalachicola Ranger

District in Florida indicates that growing season burns

(compared to dormant season) have substantially increased

the flowering and spread of wiregrass and a number of

threatened and endangered species, reduced the frequency

and size of saw palmetto, gallberry and hardwoods, and

pushed titi species (Cliftonia monophylla, Cyrilla racemiflora, and Cyrilla parvifolia) back into their natural wet

habitats (Ferguson 1998). These changes in vegetation

communities have had the added benefit of reducing wildfire intensity, which improves firefighter safety and reduces

suppression costs.

Effect of fire on slash pine growth, damage and

mortality—A fine line separates the positive and negative effects of prescribed fire on growth and yield. Fuel
68

reduction has two primary advantages with respect to

growth: it reduces the ability of wildfire to cause damage or

mortality; and it reduces understory plant competition for

nutrients and water.

Negative effects on growth occur when moisture conditions

are low and temperatures are high enough to result in crown

scorch or needle consumption. Trees respond by using

stored resources to replace the needles at the expense of

annual growth. For example, a January prescribed burn

under 25-year old planted slash pine resulted in up to 100

percent crown scorch, but no tree mortality. Subsequent

evaluation of diameter growth indicated that total crown

scorch resulted in a 60 percent growth loss over the next

two years (Johansen and Wade 1987). Even slightly

scorched (< 10 percent of needles) trees showed a growth

loss of 15 percent during the same period. Following a

prescribed burn in a nine-year-old slash pine plantation,

Johansen (1975) found similar growth losses on trees with

a high percentage of needle scorch. However, trees with

only small percentages of needle scorch (< 15 percent)

actually grew better than unburned check trees.

In addition to growth loss, defoliation in the late summer or

fall is generally after the last growth flush and may preclude

the ability of the tree to survive until the following spring.

Weise and others (1990) observed 40 percent mortality in

slash pine and 93 percent in loblolly pine (P. taeda) when all

the needles of four-year-old trees were manually removed

in October. In contrast, all trees survived after complete

needle removal in January, April or July.

Prescribed fire and exotic species—Fire is a common

mode of disturbance in the Southeast that can promote the

spread of invasive exotic species. Cogongrass (Imperata

cylindrica) is a good example. It is aggressive, well adapted

to varying site conditions, and has invaded natural forests

and agricultural lands. Prescribed fire generally burns off

cogongrass shoots, but the effect is short lived unless combined with an herbicide treatment, as it resprouts vigorously

from rhizomes (Bryson and Carter 1993). In addition, volatiles in the foliage and accumulated thatch raise fire intensity, often killing the overstory trees. Cogongrass thrives in

open sunlight and one method for controlling it is to promote

shading by other desirable plants. Unfortunately, frequent

prescribed fire may eliminate shade-providing undergrowth, thus enabling the proliferation of cogongrass.

Japanese climbing fern (Ophioglossum japonicum) and

old world climbing fern (Lygodium scandens) occur in

slash pine systems in the Coastal Plain and south Florida,

respectively. Both create ladder fuels into tree canopies that

can be problems for prescribed burning or wildfire. Both can

also be killed back, but not eliminated, by fire. Melaleuca

quinquenervia is another aggressive non-native species

that invades South Florida slash pine stands following a

fire.

Animals

General populations—Many animals and insects native to

the Southeast depend, at least partly, upon pine forest ecosystems for their habitat needs. Some species benefit from

frequent fires; others need very little fire; and many species

require a mix of fire regimes to meet their food, breeding

and cover habitat requirements. Certain species, such as

red-cockaded woodpecker (Picoides borealis), bobwhite

quail (Colinus virginianus), and gopher tortoise (Gopherus

polyphemus), will decline or disappear completely from

areas where fire is excluded, forest canopies close, and

dense, brushy understories develop (USFWS 2000). Conversely, species which prefer a dense or brushy habitat

structure increase in abundance where fire has been

absent (Breininger and Smith 1992). In general, fire tends

to increase species richness and abundance by creating

habitat heterogeneity and increased forage.

Food availability—Fire affects animals through changes in

food quantity and quality. Fire stimulates the regrowth of

plant shoots that are available to browsing animals. After

fire, many plant species are more palatable and of higher

nutrient quality than in unburned areas (Carlson and others

1993). The type and quantity of food also varies with the

season in which fire occurs. Kush and others (2000) found

that dormant season burns in longleaf pine forests resulted

in more legume production than unburned controls, while

growing season fires tended to increase grass biomass. In

both cases, fires resulted in additional forage. The benefits

of fire to birds and small animals are three-fold: enhanced

foraging access, increased insect abundance, and higher

nutritional value of insects (Landers 1987, USFWS 2000).

Fire can also negatively impact animals by changing food

availability. Florida black bears (Ursus americanus floridanus) depend upon acorns as a food source in the fall.

Growing-season fire can topkill or eliminate oaks and

reduce acorn production for several years (Maehr and

others 2001).

Habitat structure—Animals react in different ways to firealtered groundcover, woody understory and canopy cover.

Bobwhite quail require patches of brushy habitat as nesting

and brooding cover. However, coverage of dense undergrowth beyond a minimum threshold leads to excessive

predation rates (Brennan 1991). As understory fills in with

woody shrubs and trees, quail and red-cockaded woodpeckers leave and the area becomes suitable for a different

suite of bird species (Breininger and Smith 1992). Fire which

opens the area and reestablishes plants to an earlier successional stage favors recolonization by open habitat bird

species (Fitzgerald and Tanner 1992). Growing season

burns, in particular, tend to reduce total numbers of hardwood stems and are more likely to topkill brushy vegetation than will dormant season burns (Haywood and others

2001). A varied burn regime in relation to size of burns,

season of burn, and fire return interval creates a mosaic of

successional stages which tend to favor the greatest diversity of animal species.

Threatened and endangered species—Red-cockaded

woodpeckers nest in cavities or artificial boxes in living

longleaf and slash pine trees (USFWS 2000). They inhabit

open, park-like forests with little or no understory vegetation. Frequent, growing season fire maintains these habitat

characteristics (Loeb and others 1992).
69

Another endangered species which benefits from fire in pine

ecosystems is the Florida panther (Felix concolor coryi)

(USFWS 1995). Panthers are attracted to burned pinelands

up to one year after fire because of increased prey browsing

in the burned areas (Dees and others 2001). In contrast,

panthers tend to seek areas of dense vegetative growth for

denning sites. Dense areas are those that have not burned

in several years or patches of vegetation that tend not to

burn due to hydrology or fuel breaks. Fire-maintained slash

pine forests comprise the bulk of panther habitat in south

Florida.

Florida black bears also prefer to locate denning sites in

densely vegetated areas in wetlands and pine forests, but

they forage for soft mast in a variety of burned habitats

(Maehr and others 2001, Schaefer and Sargent 1990).

Current burning recommendations avoid winter burning to

prevent cub mortality and favor a growing-season fire

return interval of five to seven years to allow oaks to produce acorn crops at least once before being burned again.

Saw palmetto fruit production is considered the single most

important food component of Florida black bear diets and

growing-season burns every four to nine years should

promote optimum palmetto berry production.

Slash pine forests also support threatened and endangered

amphibians and reptiles. The flatwoods salamander (Ambystoma cingulatum) breeds in ephemeral ponds, but adults

and sub-adults spend much of their lives in open longleaf

and slash pine forests (Means and others 1996). They

benefit from frequent fires which maintain an open understory and diverse herbaceous groundcover.

Soils, Nutrients and Microorganisms

The soils of the Lower Coastal Plain and flatwoods vary

considerably in pH and nutrient content. They are, however,

characteristically poorly drained soils composed of lightly

textured sands resulting in acidic conditions with low cation

exchange capacity, low organic matter, and low clay content (Abrahamson and Hartnett 1990).

Fire can affect many soil characteristics including organic

matter (litter and humus), water repellency, nutrient dynamics, and soil moisture. Burning the forest floor obviously

results in a depletion of litter organic matter (Bell and

Binkley 1989, McKee 1987). However, the loss of forest

floor biomass does not necessarily translate to a loss of

soil organic matter. In McKee’s (1987) prescribed fire study

in Alabama, Florida and South Carolina, organic matter in

the top 3 inches of mineral soil increased between 0.4 percent and 2.6 percent, most likely due to transport of fine

particulate matter from the ash into the soil. Nonetheless,

caution must be exercised to protect soil organic matter,

especially on deep sandy soils.

After fire, water repellency is typically found as a discrete

layer of variable thickness and spatial continuity on, or a

few inches below, the soil (DeBano 2000). When fire burns,

hydrophobic substances are vaporized and may move

downward along temperature gradients until they condense.

The effects of fire on soil nutrient dynamics can be described

in generalities, but they also vary depending on fuel loads,

fire severity and how much of the duff and other surface

organic matter remains after the fire. In general, fire affects

the following nutrient-related processes:

• Nutrients stored in plants and the forest floor are transferred from living tissue, litter and duff to soil and air;

• Nutrients change from organic to inorganic forms;

• Volatilized nutrients are lost to the atmosphere in smoke;

• Precipitation may erode or leach ash and nutrient-rich

surface soil;

• N-fixing systems (microbes and plants) are altered;

• The decomposition process of litter and soil organic

matter is modified;

• Nutrient availability more than 2 inches below the soil

surface changes little, except with severe fires.

Specific increases associated with fire include: soil pH;

cations of K, Ca and Mg; and volatilization of N, K, P, Ca

and Mg. Specific decreases include: total nitrogen; P and S

anions lost as particulates or volatiles; and cation exchange

capacity. Nitrogen effects are especially important, but variable. Most of the N is tied up in organic forms; some of that

is contained in burned fuels and is converted to inorganic

ammonia or nitrate products during a fire. The result is often

a short-term increase in inorganic N (either as it is leached

into the soil or generated by new microbial activity). Both

inorganic forms (NO3

, NH4) are used by plants or other

organisms as the ecosystem changes after a fire, but they

generally return to pre-burn levels within one or two years

after a fire.

Several recent studies with southern pines help to demonstrate the variety of these nutrient responses. Following

prescribed fire under loblolly pine, Bell and Binkley (1989)

found that significant losses of forest litter (and therefore

forest litter nitrogen) led to a higher rate of nitrogen immobilization by microbial populations than in the unburned

soils. The resulting decrease in available nitrogen in the

soil contrasts with Boyer and Miller’s study (1994) in which

low intensity biennial winter burns in longleaf pine did not

significantly affect the total nitrogen or available phosphorous levels within the soil when compared with similar

stands that had not been burned in 22 to 24 years. A comparable study of Coastal Plain soils similarly demonstrated

that there were no statistically significant differences in the

amount of total nitrogen and available phosphorous in the

mineral soil after burning (McKee 1982).

Fire may also influence water retention in the soil profile

through changes in surface and/or soil organic matter.

Boyer and Miller (1994) found that the moisture holding

capacity of soils exposed to biennial winter fires was 27 percent less in the surface soil (0 to 2 inches) and 18 percent

less in the subsurface soil (6 to 8 inches) than in unburned

soils.

Effects of Fire on Water and Air Quality

Water quality—Fire effects on water quality are highly

dependent on soil, weather, topography and fire characteristics. In general, fire has not produced appreciable impacts
70

on water quality in terms of soil and nutrient influx in the

Atlantic and Gulf Coastal Plains, perhaps because of the

relatively flat terrain (Richter and others 1982, Douglas

and Van Lear 1983).

However, fire does have the potential to impact water

quality both chemically and physically. Chemical changes

occur when soil particles, particulate matter, and soluble

compounds enter water bodies after a fire and are directly

related to the effects of fire on vegetation and ground

cover, especially in riparian zones. Physical effects of fire

on water quality include temperature, flow rates, and timing

of peak flows. Stream temperatures can change when

vegetative cover that shades the water is reduced by fire

(LaFayette 1995, Pyne and others 1996). Reduction of

vegetative ground cover throughout a burned area increases

potential runoff by decreasing rainfall interception, evapotranspiration, and infiltration (LaFayette 1995). Peak flow

often occurs earlier following a rain event because of the

increased runoff.

These hydrological effects have been observed in monitored watersheds after severe fire events (Helvey and

others 1974). Most prescribed burning in the Southeast is

far less severe, and if these hydrological effects are detectable, they are temporary as new vegetation establishes

pre-fire hydrology within a few years.

Other fire management practices can also impact water

quality. Fire line construction and site preparation following

a fire increase opportunities for erosion, sedimentation

and altered hydrological flow. Similarly, constructing fire

lines around the perimeters of cypress domes embedded

in slash pine plantations may alter the direction of sheet

flow into and out of the wetlands. Nonpoint-source pollution is minimized in pine flatwoods silviculture with Best

Management Practices that minimize disturbance near

streams, protect riparian zones, and restrict prescribed

burning on steep slopes adjacent to streams (Riekerk 1985).

When different units within the same watershed are scheduled for prescribed burning they should be separated

spatially and temporally in order to minimize potential

impacts (LaFayette 1995).

Air quality—Air quality concerns are directed primarily to

human health and safety issues. Air-borne particulate

matter is regulated at the state and federal level by the

Clean Air Act and the Environmental Protection Agency

(EPA), and managed locally through State Implementation

Plans. In many cases, wildland fires can contribute significantly to total particulate matter production. Particulate

matter released per acre from prescribed fires is significantly less than wildfires (Peterson and Ward 1990, Core

1995).

Smoke has the potential to affect the public more than any

other aspect of burning through its impacts on air quality,

health and safety at distances far removed from the fire. In

the last ten years, special attention has focused on the

health effects of particulate matter less than 2.5 microns in

size. The high proportion of elderly people who have moved

to the South increases the potential for respiratory complications from the inhalation of smoke particulate matter. Yet

some smoke is necessary if the benefits from burning are

to be realized, and this message must be shared with the

public (Monroe 1999).

For a land manager, air quality is addressed in terms of

smoke management. Smoke production and dispersion

depend on weather, fuel, and burning technique (Johansen

and Phernetton 1982). Emissions can be reduced by proper

burning techniques and prompt mop-up. For example,

backing fires typically produce much less smoke than

heading fires due to more complete fuel consumption by a

slow moving flame front. Dispersion conditions should

move smoke away from smoke sensitive areas such as

roadways, airports, schools and hospitals. Slightly

unstable atmospheric conditions are also helpful.

Roadway accidents that result from smoke-impaired visibility are of great concern. Many smoke-related accidents

occur at night or during early morning hours (Mobley 1991)

when smoke or smoke/fog mixtures stay close to the ground.

Windrow and pile burning is especially dangerous due to

the residual smoke from long smoldering fires in compact

fuels which often have high moisture contents. Large burns

and aerial burns can also present smoke hazard situations

due to residual smoke where complete mop-up is not

feasible.

MANAGING FIRE IN NATURAL SLASH PINE

SYSTEMS

Uses in Natural Stands and Public Land

Management

Natural stands of slash pine occur on both public and privately owned land, often as a result of reseeding of cutover

lands in the early 1900s. Although natural stands were

originally limited to the mesic areas lying between welldrained upland and poorly drained lowland habitats, they

cover much larger flatwoods areas today and even occur

in upland areas that have remained unburned for at least

10 years. Depending on landowner objectives, managing

those stands may focus either on retaining slash pine as a

dominant species in the overstory or replacing it with longleaf pine.

Promoting slash pine regeneration—Slash pine seed

production is frequent and abundant. The seeds germinate

in conditions of bare mineral soil, sparse canopy cover and

high light levels, which are typical after a fire (Lohrey and

Kossuth 1990). However, regeneration under natural slash

pine will usually only be successful with fire intervals of 8

to 10 years after seedling establishment. Maintaining that

interval allows shrubs and hardwoods to become well

established. If desired future conditions for the stand include

an open understory, fire management under natural stands

will probably have to include a long fire-free interval to

establish a new seedling crop, followed by a series of

shorter intervals to control shrubs and promote grass and

forbs.

Prescriptions for burning to achieve regeneration standards

should be based on the seasonal effects of fire, on local

experience, and on state and regional guidelines (such as

Wade and Lunsford 1989). A few important guidelines
71

point out the types of information that should be considered

for burning under natural slash pine stands:

• Burns are more detrimental to plant material that is

physiologically active at the time of the fire rather than

dormant

• Moisture content of needles is lowest in spring (Robbins

and Myers 1990)

• Winter burns generally result in less root kills — both

hardwood and pine

• Defoliation in autumn is detrimental to slash pine

(Robbins and Myers 1990)

• Spring and summer fires may leave trees susceptible to

insect attack; winter and autumn burns can give trees

more time to recover before peak insect activity.

Hazard reduction—Accumulation of litter and development

of a thick vegetative understory creates conditions that can

lead to intense wildfires during droughts or lightning storm

seasons. Large quantities of litter and flammable vegetation may build up rapidly in Coastal Plain pine forests and

can reach serious threat levels within 5 to 6 years after a

disturbance (Wade and Lunsford 1989). Although some

plantation owners may have reservations about using fire

in managed stands, fire is a practical way to reduce hazardous fuel buildup in natural stands and plantations.

Hazard reduction was cited as the greatest resource benefit of prescribed burning in the South from 1985 to 1994 by

federal, state, and private forest managers and 72 percent

of the total area prescribed burned was for this reason

(Haines and others 2001). The amount of burning conducted

for this purpose has increased in the last ten years, and

survey respondents expect it to continue increasing. The

increase reflects a shift in public land management goals

away from post-harvest slash reduction toward managing

at an ecosystem level to accommodate the habitats of firedependant and/or threatened and endangered species.

However, the survey results described by Haines and

others (2001) also listed “excessive fuel loading” as a

barrier to using fire as a management tool. A standard

practice for burning dense shrub understories is to conduct

a winter burn before switching to growing season burns in

order to reduce fuel loads during favorable conditions

(Robbins and Myers 1990) and to minimize pine damage

(Crow and Shilling 1980). If possible, stands might be

ignited aerially when they are burned for the first time, with

close spacing of ignition spots to deplete fuels before fires

can reach unmanageable levels. Subsequent burns can

be smaller, with the end result being a patchy distribution

of burned areas that reduce fuel continuity in future fires

(Wade and Lunsford 1989).

Aesthetics and access—Access and appearance are

also increasingly important considerations in forest management. Recreation users vary from hunters and bike

riders to canoeists and wildlife observers. All have their

particular perceptions about how the forest should look,

and those ideas usually do not include burned landscapes.

Precautions can be taken when burning to reduce the

visual impacts of fires, such as burning under conditions

that will minimize scorch in areas of high visibility interest.

In addition, areas can be burned in patches to leave some

unburned areas and create visual diversity (Wade and

Lunsford 1989).

Ecosystem management and restoration—Restoration

of longleaf pine to areas it once occupied is probably the

most widespread ecosystem restoration concern in southern forests today. Although many private lands are contributing to this effort, public lands are particularly focused on

the goal of restoring longleaf pine. For example, one U.S.

Forest Service goal is to restore between 10,000 and

15,000 acres of longleaf pine which now contain offsite

slash pine on National Forests in Florida (USFS 1999).

Prescribed fire is a key tool in the management plans for

longleaf restoration. According to the interim report on

restoring longleaf pine at Eglin Air Force Base: “As a

general rule, apply fire to longleaf pine and associated

communities when you can, where you can, and as

frequently as you can” (Provenchar and others 2001). The

U.S. Forest Service has established the goal of burning

National Forests in Florida on a variable 3-year cycle with

half of the fires conducted during the growing season.

Vegetation control methods other than fire have been used

to prevent hardwood encroachment and maintain pine

savanna. Among these are herbicides, chain saw felling

and girdling, and mechanical clearing. Each provides

certain benefits in terms of duration of shrub control or

flexibility for when they can be conducted. However, in

most situations fire is the most economical management

prescription. In a study conducted at Eglin Air Force Base

in the Florida panhandle, prescribed burns with ground

ignition cost approximately $9 per acre and aerial ignition

as little as $4 per acre. By comparison, herbicide applications cost about $90 per acre and chainsaw felling/girdling

$60 per acre (Provencher and others 2001). Each of the

methods (including fire) has various risks or undesirable

effects that need to be weighed in planning restoration

activities.

Wildlife management—Wildlife populations generally

benefit from habitat improvements caused by fire (Main

and Tanner 1999). Most wildlife management practices

focus on particular species of interest whether the property

is publicly or privately owned. Prescribed fire is used to

reduce woody vegetation and increase both herbaceous

biomass and species diversity in southern pine forests

(Moore and others 1982b).

Bobwhite quail, white-tailed deer (Odocoileus virginicus),

and wild turkey (Meleagris gallopavo) are important game

species in slash and other southern pines. Bobwhite quail

benefit from frequent fires (every 1 to 3 years) that keep

midstory vegetation low and increase the quantity and variety of seeds available for foraging (Evans 1989, Block and

others 1995). However, burning should also leave unburned

thickets for nesting and protective cover. Prescribed fires

for quail management should avoid the March through

September breeding and nesting season (Wade 1983),

although quail will renest within the same season (Moser

and Palmer 1997).
72

Wild turkeys require a mosaic of habitat types. Turkeys

need open habitats for seed and insect foraging and brood

rearing. They benefit from management practices that

include frequent burning (every 2 to 4 years) to reduce

midstory vegetation. However, they also use thicker vegetation for nesting from March to June.

White-tailed deer also benefit from periodic fires in both

natural and planted slash pine. They prefer the lush new

growth of grasses, herbaceous plants, berries, woody

species and vines that follows burning (Hurst 1989). Fire

improves the nutritive quality of deer browse for up to

eleven months after a fire (Carlson and others 1993).

Prescribed fires in the winter are best to promote shrub

and hardwood resprouting, usually at a 2 to 3 year interval

(Hurst 1989).

Management for non-game wildlife species is also important in slash pine forests. Forest management practices

that improve the habitat of the red-cockaded woodpecker

also benefit the Bachman’s sparrow (Aimophila aestivalis).

Both species prefer open old-growth pines with open

midstories and dense herbaceous vegetation (Plentovich

and others 1998). Frequent prescribed fires in the growing

season are necessary to maintain these habitat qualities.

Bald eagles utilize the southern pine ecosystem for nesting

and roosting in mature trees in open forests. Forest management practices that benefit eagle habitat include thinning

younger pines (Chester and others 1990) either mechanically or with careful use of prescribed fire. Emphasis should

be placed on minimizing fire damage to mature trees.

Many species of neotropical migratory birds stop in southern pinelands on their journeys north and south each year

(Dickson and others 1995). They require a variety of different habitats (Block and others 1995). Using prescribed fire

to manage for a heterogeneous blend of different habitat

types will benefit these neotropical migrants.

MANAGING FIRE IN SLASH PINE PLANTATIONS

Effects of Plantations on Fire Regimes

The extensive conversion from acres dominated by longleaf pine to domination by slash pine has had a concurrent

impact on landscape level fire potential including likelihood

of occurrence, intensity, severity, and area burned. One of

the factors that has favored regeneration of slash and loblolly pine over longleaf pine is the need for frequent, specifically timed prescribed fire for successful longleaf pine

establishment (Hedman and others 2000, Boyette 1996).

While recognized as beneficial for management and wildfire prevention in slash and loblolly pine stands, prescribed

fire is applied much less frequently than might be recommended due to a combination of factors:

• Sensitivity of young slash pine to fire-induced mortality

or damage;

• Accumulation of ground fuels and vegetation;

• Complexity of applying prescribed fire given urbanization, smoke considerations, training, and available burn

days;

• Risk of losses in wood volume production.

Slash pine management and fuels—Fire exclusion from

plantations allows a dense shrub or hardwood midstory to

develop which shades out native grass and herbaceous

groundcover species (particularly wiregrass). These ground

cover species could comprise a significant component of

the fine fuels on such sites (Clewell 1989). Standard site

preparation techniques, such as chopping, root raking, and

bedding, can also significantly alter native groundcover

species (Shultz and Wilhite 1974, Moore and others 1982a,

Swindel and others 1983). Wiregrass is of particular importance because of its apparent influence on fire spread and

effects (Clewell 1989). Wiregrass seed production is also

directly dependent upon occurrence of lightning season fire

(Clewell 1989). Therefore, the standard dormant season

fire regime utilized in most managed slash pine systems,

while effective for fuel reduction, does not contribute significantly to the maintenance of the critical wiregrass fine fuel

component.

Hedman and others (2000) attempted to specifically address

the question of the impact of longleaf, slash, and loblolly

pine plantations on native groundcover species. Findings

included: longleaf stands had significantly more herbaceous

species and cover than slash or loblolly sites; loblolly sites

had significantly greater overstory and midstory density;

and longleaf and slash pine stands were otherwise similar

in species richness and stand structure. A significant and

logical observation was that land-use history, particularly

transition from agriculture to forestry, had the most significant impact on groundcover structure and composition with

former agricultural field sites supporting lower species

diversity than cutover sites.

Traditional silvicultural recommendations for slash pine

management have centered on even-aged management,

intensive site preparation and commercial thinning of dense

stands. Stands treated with intensive site preparation techniques may be burnable by ages 10- to 15-years-old if

understories are mainly grasses and herbs. Plantations with

excessive shrubby fuel accumulations generally require

low intensity winter burns, or preclude safe application of

fire.

Fire behavior—The Florida Fire Behavior training course

recognizes the complexities and influences of pine management on wildfire behavior through designation of “Dense

Pine” as a major fuel group with four size classes: young

trees up to 10 feet tall, saplings 10 to 20 feet tall (stem

d.b.h. 3 to 5 inches), pulpwood (at least 20 feet tall, stem

d.b.h 5 to 9 inches), and poles (d.b.h. 9 inches or greater).

Typical fire behavior in the sapling class includes “crowning

even under moderate weather conditions”. Behavior in the

pulpwood class is described as being the “most intensive”

and releasing the “greatest amount of energy when the

crown becomes involved”, leaving standard control measures highly ineffective and presenting hazardous firefighting conditions (Parry and others, date unknown). This fire

behavior can result from a high density of pines, hardwood

trees, shrubs, palmetto, climbing vines and other fuels

typical of unburned slash pine flatwoods forests and

plantations. The palmetto-gallberry shrub community

characteristic of many slash pine plantations is listed as a

second major fuel type in Florida.
73

In contrast, complete canopy closure and/or intensive vegetation control may result in low intensity fire due to reduction

of herbaceous groundcover (Means 1997) and midstory

species. Periodic dormant season prescribed fires can also

maintain woody shrubs at a lower height and fuel hazard

than would occur in the absence of fire.

Herbicide use—The increasing use of herbicides for

vegetation management and restoration also offers an

opportunity to alter fire regimes. For example, chemicallytreated shrubs will leave standing dead fuels for one to

three years, but as the dead shrubs break down, grass and

herbs increase and become the dominant understory fuel.

The extent of these fuel conversions will depend on plant

communities and specific herbicides. As application of

prescribed fire becomes more challenging, it is likely that

fuel reductions with herbicides will continue to increase.

Primary Objectives for Prescribed Fire in

Plantations

The primary reasons for application of fire in managed slash

pine stands include: fuel/hazard reduction, site preparation,

and control of understory hardwoods and shrubs which

compete for resources and limit access by forest managers

(Williams 1985). Additional objectives may include pest

management in certain situations, range improvement

where cattle grazing and pine trees are managed together,

and preparation of old field plantations for pine straw

collection. The following discussion elaborates on several

of these objectives that were not covered previously in the

Managing Fire in Natural Slash Pine Systems section.

Hazard reduction—Wildfires are a significant hazard in

almost all natural ecosystems in the South, endangering

homes, people, and timber investments. In Florida in 1998,

over 500,000 acres burned in wildfires in a matter of weeks,

with losses totaling over $1 billion. Many of these fires

burned through pine plantations which had dense understory vegetation.

Prescribed burning is an effective and efficient technique

to reduce the quantity of dead debris and fine fuels (Hunt

and Simpson 1985). Prescribed burning before stand

establishment can reduce the risk of wildfire when slash

pine stands are young and at the greatest mortal risk from

wildfires. A study in Australia demonstrated that the use of

low intensity prescribed burning every three years reduced

fine fuels and had no effect on the diameter or growth of

slash pine in southeast Queensland (Hunt and Simpson

1985).

The effect of invasive exotic grasses such as cogongrass

and silk reed (Neyraudia reynaudiana) can also influence

fire behavior. In South Florida slash pine savannas these

grasses increase fine fuel loads and litter and change fire

behavior by increasing the fire intensity 1 to 2 m above the

ground (Platt and Gottschalk 2001). Prescribed burning

will have to be combined with other treatment methods to

help keep these new fuel load additions in check.

Site preparation—Reforestation objectives were the

second most common reason for prescribed fire on state

and private forests in the South (Haines and others 2001).

Mechanical treatments, herbicides, and burning all have

advantages and problems related to site preparation

objectives of reducing competition, exposing mineral soil,

and keeping young pine seedling roots above standing

water. In recent years the liability associated with prescribed

burning, smoke regulations, and public perception has

considerably curbed the use of burning in commercial site

preparation prescriptions. However, burning is still an

economical alternative for site preparation.

Pines are best planted on mineral soil. Successive summer

fires before planting can be used to expose mineral soil

and temporarily reduce the amount of hardwood and herbaceous competition. For example, Harrington and others

(1998) found that the abundance of vines and hardwoods

after a site preparation treatment of herbicides plus burning

was approximately half of the abundance in untreated areas.

Pest management—Prescribed fire can be used to curb the

hazards of certain diseases and insects, but should not be

applied if a stand is already stressed by drought, disease

or other conditions. Prescribed fire before and after thinning

reduces the infection of annosum root rot (Heterobasidion

annosum) by destroying the litter associated with this fungus

(Froelich and others 1978). Fungal sporophores are normally produced in the litter at the base of infected trees and

serve as a spore source for fresh stumps after thinning.

Froelich and others (1978) noted that a fungal competitor

of root rot also increased in the soil after burning and may

have helped reduce the infection of root rot.

Fire will control the spread of bark beetles from infested

trees that are cut and piled, but it is unclear if prescribed

burning has any other effects on southern pine beetles in

slash pine plantations unless it is to stress trees and

increase their susceptibility during times of high beetle

populations. Some other pests that are controlled by regular

prescribed burning are the ticks and chiggers that await

forest workers and recreationists.

Range improvement—Fire objectives for range management are two fold: prescribed burning may be used to

improve range resources; at the same time, livestock grazing can keep fuel loads low enough for protection from wildfires. Regular burning (two to four year intervals) improves

forage quality and quantity for livestock. Forage utilization

is greatest the year following burning with new shrub, herb,

and grass sprouts that capture the quick flush of nutrients

into the soil after a fire and are often more nutritious and

palatable than older plants. Common slash pine planting

densities (600 to 800 trees per acre) usually shade out

herbaceous plants necessary for grazing by the tenth year

after planting. Only if stands are thinned early and kept

fairly open by frequent burning can forage be maintained

(Grelen 1978).

Although grazing in plantations is not as common as in the

past, increasing interests in silvopasture will probably lead

to more prescribed burning to accommodate land-use combinations of cattle and pine plantations (Nowak and Long

2004). Fire is widely used in southern Florida slash pine

prairies to support large grazing operations in those areas

with low pine densities.
74

Pine straw management—Pine straw has become an

important product from many old field plantations. By raking

and selling the straw, landowners receive a financial return

through the midyears of the timber rotation. Raking can

begin between ages six to eight, but is most productive

around age 15. Prescribed fire does not play a role in the

management of pine stands during the years of pine straw

collection. However, prescribed burns before raking begins

can consume shrubs, grasses, and debris that make baling

difficult.

IMPORTANT CONSIDERATIONS AND ISSUES

FOR PRESCRIBED BURNING

The ability of natural resource managers to take advantage

of prescribed burning as a land management tool is an

undeniable benefit. To maintain that benefit, a number of

special considerations need to be addressed prior to prescribed burning. Some of the most important issues are

described in this section.

Best Management Practices

Best Management Practices are guidelines that are

designed to protect water quality, riparian zones and

related resources during forestry activities. These guidelines assist forest managers in defining sensitive areas

and in the proper use of various practices or operations,

including prescribed burning.

Best Management Practices regarding prescribed fire

primarily address the construction and maintenance of

firelines: utilize natural boundaries or roads as much as

possible; construct lines with the minimum acceptable plow

depth; do not run lines directly into waterways; follow contours; and avoid streamside management zones. Prescribed

burning is also generally restricted on slopes greater than

18 to 20 percent adjacent to waterways. Many of the states

in the Southeast have similar BMPs, although specifications vary with differences in topography and soils.

Evaluation

Evaluation of a prescribed fire is as important as the planning stages. The primary purpose of the evaluation process

is to determine if the burn met the objectives set by the

managers and to serve as a learning tool for future burns

(Wade and others 1989). The experience gained through

monitoring and evaluation will improve planning and

predictions for future burns. The evaluation process should

consider air quality and smoke management, soil and root

damage, needle scorch, and the overall impact of the burn

on vegetation and wildlife.

Smoke Management and Liability Concerns

Prescribed burn plans incorporate weather conditions and

fuel loads that will generally result in less smoke than wildfires. A variety of forecasts are now available through the

National Weather Service and state forestry offices and

should be used to avoid the unfortunate “wind changes”

that moved smoke to unplanned areas in the past. Nevertheless, the number of smoke-related lawsuits against landowners has increased (Brenner and Wade 1992). Smoke

management laws and the risk of liability were rated in the

top four barriers to prescribed burning in the recent survey

of foresters in the South (Haines and others 2001).

Burning permits are required by law in most states and their

issuance is dictated, to some degree, by State Implementation Plans. Many states have also followed Florida’s lead in

developing statutes or rules that provide liability protection

for burners who have been certified through a prescribed

fire training program. Despite these legal supports for prescribed burning, a major concern for many practitioners is

still the possibility of civil or criminal lawsuits, in spite of the

fact that negligence must be proven before property owners

can be found responsible for damage or injury from the fire

(Siegel 1984). State laws are increasingly declaring that

the standard for liability in prescribed burning cases will be

based on simple (carelessness) or gross (willful and wanton)

negligence rather than strict liability. According to Stanton

(1995), “In strict or unlimited liability situations, a defendant

may be morally blameless and the act fully unintentional;

nevertheless, the defendant is legally at fault and will be

required to satisfy any judgments created.” When the situation is not within the strict or unlimited liability guidelines

the court has to determine if the defendant was indeed

negligent, and if so to what extent. Given the litigious

nature of the general public, landowners and resource

managers should be knowledgeable about legal requirements and liability issues before becoming involved in

prescribed burning practices (Eshee 1995).

Just as with poorly placed smoke, prescribed fires that

escape the intended boundaries can be devastating. Incidents of escape can happen even with perfect planning

and execution of a prescribed burn. Burn plans are not

complete without a contingency plan for how to respond

and who to contact in case of an escape.

Public Perceptions about Prescribed Burning

The biggest challenge facing land management practices,

such as prescribed fire, is often public perception and

actions that emanate from those perceptions. Land managers and decision-makers need to understand how citizens

perceive fire to build support for their programs (Lichtman

1998). Despite an often negative perception of fire, the

public’s tolerance and knowledge of prescribed fire have

increased over the past several decades, especially when

the participants were provided with educational materials

(including various media sources) on prescribed burning

and wildfires (Loomis and others 2001).

One survey of Florida residents assessed their awareness

and attitudes dealing with fire. The results indicated that

“There is a somewhat schizophrenic perspective on fire in

Florida” (Monroe and others 1999). The general public

knows the benefits of prescribed burning; they believe

tolerance of smoke should be higher; and they understand

prescribed burning versus wildfire. However, they also

supported stricter burning regulations. Maybe some of the

confusion in the respondents’ preferences arises from misconceptions of terminology. For example, the survey also

showed that only 40 percent of the respondents defined

the term “prescribed fire” correctly (Monroe and others 1999).

Educational programs will play a key role in clarifying such

misunderstandings.
75

Wildland-Urban Interface and Prescribed Burning

The increasing popularity of homes in natural settings has

resulted in an expanding wildland-urban interface. Yet many

people living next to wildlands are unaware of the risks of

fire to their homes, they value the ambience of their surroundings, and they expect emergency services to take

responsibility for fire threats (Feary and Neuenschwander

1998). Issues arising at the wildland/urban interface are

related to both the risk from dangerous wildfires and the

use of prescribed burns to minimize those risks.

Fragmented forest landscapes have increased opportunities for wildland fires to cross paths with human development. Some of the most acute problems occur in residential

areas in, or adjacent to, slash pine plantations. Many

property owners in the wildland-urban interface have preconceived notions about fire and tend to oppose prescribed

fires. They may view prescribed fire as a threat to public

health and safety concerns, a source of liability, evidence

of lack of landowner management savvy, or a threat to

community development (Macie 2001). Their perceptions

and attitudes may limit the use of prescribed fire as an

interface management tool.

The role of public education in addressing fire at the wildland/urban interface is crucial to limiting the impacts on

people’s lives. Education has become a valuable tool for

increasing public understanding of the role of fire in nature

and the opportunities to use prescribed burning (Monroe

and others 1999). Education can change knowledge and

attitudes about prescribed fire (Loomis and others 2001),

and introduces homeowners to practices that will reduce

the risk of fire to their property, homes, and lives. A diverse

set of educational materials are now available or being

developed for landowners.

Just as landowners need to be persuaded to take responsibility for making their homes firesafe, developers need to

accommodate wildfires in their plans. Subdivision infrastructure should be able to limit wildfires and provide for

evacuation and control operations when fires do occur.

Buffer zones, firewise structures, multiple access routes

and water resources for fire fighting are crucial, as are open

communications among neighbors, resource managers, and

community/business members (Monroe and Marynoski

1999). FireWise workshops are becoming a valuable mechanism for encouraging that communication and planning.

ADVANCES IN FIRE CONTROL AND MANAGEMENT

Fire Behavior Modeling

Classifying fuel and weather characteristics according to

spatial and temporal scales facilitates our ability to understand and predict fire behavior. Fuel classification and fire

modeling have been evolving at a rapid pace. In the last

20 years, developments in computers, software and fuel

classification systems have greatly increased the number

of tools used to quantitatively assess fire behavior and

plan fire control operations.

Fire behavior prediction models are used to provide realtime support for suppression tactics, safety, and prescribed

fire planning. The Windows® based wildland fire prediction

tool Behave was developed by the USDA Forest Service,

Rocky Mountain Research Station and Systems for Environmental Management. Predictions are developed from user

inputs on fuel, weather, topography, and fire characteristics. Fire behavior estimates include: surface fire spread,

fireline intensity, spotting, flame length, scorch, tree mortality, and probability of ignition (Andrews 1986). Several

versions of this software are now available from different

vendors. Other fire forecasting models and fire information

resources, ranging from pollutant emissions applications

to emergency incident tools for Geographic Information

Systems (GIS), are described at www.fire.org.

Fuel Loads

Accurate information about woody fuel size classes and

fuel loads are needed to run BehavePlus and smoke

dispersion models. The U.S. Forest Service and National

Wildfire Coordinating Group have recently published photo

series for estimating fuel loads in the Southeast (Ottmar

and Vihnanek 2000, Scholl and Waldrop 1999). These

photo series focus primarily on longleaf and loblolly pine

and can be used to quickly estimate fuel load characteristics in a variety of stand conditions. Fuel loads are also

being assessed on a much larger scale through the use of

satellite imagery, GIS and ground truthing. The resulting

state and regional models will be an important tool in planning fire mitigation and control operations in the future.

Fire Weather

Weather forecasting and fire modeling have a direct influence on prescribed fire planning. For example, the Florida

Division of Forestry manages an online resource (http://

flame.fl-dof.com) that houses current fire weather information used to forecast weather and predict fire danger levels.

Daily readings of temperature, relative humidity, surface

winds, mixing height, transport winds, dispersion index,

Keetch-Byram Drought Index (KBDI), Haines index, low

visibility risk index, and fire weather indices are available.

The Division of Forestry also updates a “spot forecasting

system” that produces hourly estimates of temperature,

relative humidity, and wind speed and direction 20 ft above

the vegetative surface for a landowner’s specific location.

These outputs are an efficient way of obtaining requirements for the BehavePlus modules and other fire prediction software.

CONCLUSION

Wildfire is a significant public issue for natural resource

management and it will be even more so in the future,

especially where it becomes a serious threat near the wildland-urban interface or in slash pine plantations. However,

prescribed fire will also remain as an important and strategic tool for both plantation and natural stand management; but its application will be dependent on policies and

issues related to public acceptance, health and safety.

Landowner and public education will be critical components of future fire management programs.
76

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79

INTRODUCTION

Slash pine (Pinus elliottii) has been a favorite tree species

for plantation management in Georgia with some plantations dating back to 1925 (Jones 1979). From 1956 to 1960,

slash pine was widely planted in the Soil Bank Program.

Slash pine often grows with longleaf pine (Pinus palustris)

and currently the longleaf-slash pine cover type occupies

over 13.17 million acres (8.7 percent of total forested

acres) in the southeastern United States (USFS 2002).

The majority of the acreage is in the south Atlantic Coastal

Plain (87.1 percent).

The range of slash pine extends from east Texas to

Georgetown County, South Carolina (USDA Forest Service

1965). Slash pine occurs naturally in all or part of 179

counties across the south and is more restricted than that

of other major southern pines (Critchfield and Little 1966).

Slash pine grows naturally on sandy soils that are poorly

drained with 18-24 inches (46-61 cm) to a clay hardpan.

Pond margins are well suited to slash pine whereas pure

sand or poorly drained sites are least productive. Slash

pine seedlings and young trees are susceptible to fire

damage. Frequent fires tend to favor longleaf, but slash

pine may out compete longleaf if given adequate fire

protection (Jones 1979).

Because of the regional coverage of the slash pine type,

wildlife managers frequently encounter both planted and

natural stands. Wildlife rarely uses slash pine trees directly.

Direct use includes cavity construction by woodpeckers in

mature trees and feeding on cones by squirrels. Information on wildlife use of slash pine stands is important for

managers. However, only a limited number of studies have

examined wildlife utilization of slash pine stands. In the

absence of specific information from slash pine stands,

inferences often are drawn from studies where the

dominant pine type was loblolly (P. taeda) or longleaf.

WILDLIFE NEEDS

Wildlife management activities are often directed toward

supplying target species with the necessary resources to

meet their survival needs. For any species of wildlife, the

fundamental rules of survival are: 1) get energy; 2) store or

conserve energy; and 3) reproduce. Generally, wildlife management involves increasing populations or decreasing

populations. Increasing the population size has more often

been the objective for most wildlife management. Examples

include threatened and endangered species management,

stocking to reestablish populations and management to

increase hunting or viewing opportunities. Often habitat

management is the means for increasing population size.

Habitat management techniques include burning, thinning,

conversion to another forest type, food plot establishment,

fertilization, herbicide treatment or a combination of

techniques.

Wildlife habitat must supply space, cover, food and water.

Space means an adequate area for obtaining life needs

and avoiding stress from crowding. Cover includes the

vegetative or physical features of a landscape that are

used for hiding (adults and young or nests) and protection

for weather (wind, rain, sun or snow). Food must be adequate in calories (energy) and nutrients to insure growth

and survival and to maintain good health. Water is necessary but rarely limiting in the southeast. Increasing these

elements raises carrying capacity of the environment.

Decreasing the population size balances the number of

animals with the available resources. Either strategy, alone

WILDLIFE MANAGEMENT ISSUES AND OPPORTUNITIES

IN SLASH PINE FORESTS

Michael T. Mengak and Steven B. Castleberry1

1 M.T. Mengak, Assistant Professor of Wildlife Service and Outreach; and S.B. Castleberry, Assistant Professor of Wildlife Management in

the Daniel B. Warnell School of Forest Resources at the University of Georgia, Athens, GA 30602.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—The slash pine (Pinus elliottii)-longleaf pine (P. palustris) cover type currently occupies over 13 million acres

(8.7 percent of total forested acres) in the southeastern United States. Despite the large acreage and numerous studies

in longleaf forests, only a limited number of studies have examined wildlife utilization and management of slash pine

stands. Natural slash pine sites are low in soil phosphorous and have low potential as white-tailed deer (Odocoileus

virginianus) habitat. Regular prescribed fire improves the palatability and nutritional content of forage for deer. Similarly,

thinning and burning slash pine plantations improves habitat for turkey (Meleagris galapavo) and quail (Colinus

virginianus). The gopher tortoise (Gopherus polyphemus) is a keystone species found in the slash pine ecosystem.

Burrows dug by gopher tortoises are used by over 50 other species of vertebrates and invertebrates. The flatwoods

salamander (Ambystoma cingulatum), a federally threatened species, has experienced a rangewide population decline

that is thought to be related to habitat conversion and fragmentation as longleaf pine stands are converted to slash and

loblolly pine. Management for slash pine and wildlife are compatible but managers and landowners should manipulate

vegetation to mimic natural conditions. Unfortunately, few studies examine the financial trade-offs between timber

production and wildlife.
80

or in combination, can be employed in a wildlife management plan.

SUCCESSION

Succession involves the gradual change in plant and animal

communities over time. Many wildlife species of the southeast such as deer, northern bobwhite, eastern cottontail

(Sylviligus floridana), mourning dove (Zenaida macroura)

and many small mammal species are considered early

successional species and require frequent disturbances to

the forest cover. These species respond well to forest management activities such as clearcutting or selection harvest.

Other species are late successional species that require

less frequently disturbed vegetation or undisturbed vegetation. Examples include wild turkey, eastern gray squirrel

(Sciurus carolinensis), fox squirrel (S. niger), red cockaded

woodpeckers (Picoides borealis), and many songbirds.

Hawks, owls and meso-mammalian predators require a

mix of early and late successional habitat for hunting and

nesting or denning. In reality, most species also utilize a

variety of forest cover types in various stages of plant

succession.

Succession occurs at both a forest stand and landscape

level. At the stand level, succession is localized and impacts

fewer species. At the landscape level the impacts are larger,

involve more species, last longer and are more difficult to

manage. From a management perspective, part of the difficulty in managing wildlife species arises from diverse ownership patterns and an incomplete knowledge of the life

history requirements of many species, especially non-game

species including threatened and endangered species.

While forest cover type is important to the abundance and

distribution of wildlife species, other factors are involved.

These include such concepts as edge and interspersion or

juxtaposition of habitats. Thus, wildlife management is an

inexact science and wildlife managers often work behind

forest managers especially when the landowners’ objectives include financial returns from timberland.

WILDLIFE MANAGEMENT ACTIVITIES

Numerous tools are available to the wildlife manager or

landowner for manipulating forest stands to enhance or

decrease wildlife populations. These tools include prescribed burning, thinning, regeneration method, increasing

snags and down material (course woody debris – CWD),

use of herbicides in site preparation or intermediate stand

management, fertilizing often at time of stand establishment,

maintaining streamside management zones (SMZ’s), and

more. Each tool can be used alone or in combination. Each

will have different results depending on the site, season

and wildlife species involved.

Numerous researchers have examined the impacts of intensive pine plantation management on wildlife. In general,

wildlife populations are abundant in the first few years

following stand establishment. Wildlife populations, both

small mammals and game species, decline as the stand

ages and canopy closure occurs. Closed canopy pine plantations limit sunlight from reaching the forest floor that in

turn prevents grasses, forbs, or woody understory from

developing. A thinning and burning regime is required in

order to maintain habitat conditions favorable for wildlife.

This level of management could decrease overall timber

yield but may increase income from lease fees and nonconsumptives uses. However, the financial trade-offs

between timber production and wildlife management are

largely unknown.

WILDLIFE SPECIES

Game

White-tailed deer—Natural slash pine forests typically

occur on sites low in soil phosphorous and have low

potential as deer habitat (Buckner 1983). The understory

contains many xeric species due to prolonged dry periods

and low fertility to mesic and hydric species as landscape

position changes to lower lying areas. There is abundant

food biomass but of low quality due to soil phosphorous

deficiency or an imbalance in the calcium: phosphorous

(Ca:P) ratio. The Ca:P ratio could be as high as 5:1 in slash

pine flatwoods sites whereas the optimum ratio for deer

diet is 2:1 or 1:1 (Buckner 1983). Buckner (1983) concluded

that available phosphorous is not sufficient to maintain a

“large healthy herd” (p. 370).

Fertilization of slash pine stands with phosphate fertilizers

may improve forage quality. Wood (1986) reported that

growing season applications of phosphate fertilizer

improved the nutritional value of selected forage species

for one to two seasons. He also found that the nutritional

gain was greater on Coastal Plain than Piedmont sites in

South Carolina. However, fertilizer uptake and competition

between planted pines and understory forage have not

been tested.

Time to crown closure affects use by deer in plantation

slash pine. Clearcuts make large amounts of browse available to deer. Most deer use of clearcuts is only along the

outer 100 yards (Buckner 1983). Additionally, shape of the

clearcut determines the amount of edge created and influences deer utilization. Edge is important because most

activity is concentrated in the transition zone between

stands. After crown closure, most plantations provide little

more than escape cover because the pine canopy shades

out understory vegetation. Time to crown closure is inversely

related to pine density in planted stands.

Thinned plantations can resemble natural stands and thinning will improve the site for use by deer. Thinning opens

the canopy allowing sunlight to reach the forest floor, which

in turn stimulates understory growth. Thinning plantations

to 60 to 70 feet of basal area is recommended for deer.

Burning alters vegetation by controlling density and composition (Buckner 1983). Regular prescribed fire improves

forage quality by setting back succession and stimulating

new growth following the fire and promotes many fireadapted species. This improves the palatability and nutritional content of forage for deer (Wood 1981, 1988). As a

rule of thumb, understory production peaks in 2 to 3 years

following fire while browse production peaks in five years.

Burning at 3 to 4 year intervals is recommended.
81

Frequent prescribed burns will control hardwood midstory

(Tanner 1987), which improves pine growth by reducing

competition, and stimulating understory development.

Understory shrubs can produce 200 to 300 lbs per ac of

forage. Common shrubs include gallberry (Ilex vomitoria),

runner oak (Quercus pumila) and greenbrier (Smilax spp.)

Herbaceous biomass can reach 2500 lb per ac in natural

slash pine (Tanner 1987). Biomass production tends to

decrease following establishment of planted slash on cutover sites because of changes in overstory composition

and light intensity at the forest floor. Browse cover was

greatest in plantations greater than 38 years old but herbaceous cover was greatest in natural slash pine stands

(Tanner 1987). Tanner (1987) reported that overstory cover

in natural slash pine was 58 percent. This level of canopy

allows light to reach the forest floor and increases the

production on herbaceous and woody browse.

In addition to thinning, burning and fertilizing plantations

and natural stands, maintaining openings is beneficial to

deer populations. Wildlife plantings can be established in

utility rights-of-way, logging roads and decks, old house

sites or similar areas. Mowing and maintaining edges

improves cover and forage for deer and other early

successional wildlife.

Quail—Quail (Colinus virginiana) are weak scratchers and

need open ground for travel and foraging but with clumps

of taller vegetation. However, they require moderately dense

cover for nesting. Overhead cover is critical in reducing

avian predation. Foraging, nesting, loafing, and dusting

cover must be provided in close proximity to each other.

Burning pine stands at 1 to 2 year intervals often provides

the necessary cover especially on the sandy soils where

slash pine is the dominant overstory pine. Management

should favor natural vegetation and succession. Food plot

establishment and maintenance (usually on an annual

basis) is costly and not always successful in increasing

quail abundance. Newer research seems to indicate that

food plots reduce the population lows frequently seen in

quail population dynamics but do not substantially increase

carrying capacity (Personal communication. 2002. Dr. L.M.

Connor, Associate Scientist, Joseph W. Jones Ecological

Research Center at Ichauway, Rt. 2, Box 2324, Newton, GA

39870). Management activities that encourage weeds and

early successional stages include burning and rotational

disking and rotational mowing (Jackson 1993, Thackston

and Whitney 2001). These activities can take place in slash

pine plantations especially if pine stem density is reduced

through a thinning regime.

Turkey—Turkey (Meleagris galapavo) respond to many of

the same management activities as deer and, to a lesser

degree, quail. Turkeys consume the green succulent new

growth of grasses, forbs, and legumes especially in winter

and early spring (Hurst 1981). Food plots, along with thinning and burning can provide significant habitat improvement for turkeys. However, tree density in plantations also

has a significant impact on turkey habitat quality.

Turkeys nest in openings or along the edge of clearcuts,

forest roads, old fields and utility rights-of-way (Speake

1975). In slash pine plantations, tree seedlings should be

planted on an 8 x 10 ft or 8 x 12 ft (545 or 455 trees per acre,

respectively) spacing. Logging operations should leave

streamside management zones (SMZ) at least 300 feet

wide. A general management recommendation is to maintain 20 to 30 percent of the ground in direct sunlight at noon.

Timber density objectives should maintain basal area at 10

to 15 ft2 below site index (SI) at base age 50 years. In plantations, this can be achieved by maintaining a 12-foot wide

skidder corridor at 70-foot intervals among the pine rows.

Thinning and burning regimes for turkey management in

slash pine plantations should be similar to those recommended for deer. Numerous studies indicate that prescribed

fire is an important management tool for maintaining turkey

habitat in the southeastern Coastal Plain (Hurst 1981).

Burning reduces cover making seeds and insects more

readily available especially to poults. Burning also improves

the nutritional status of forage including palatability, digestibility, nutrient content and mineral ratios.

WILDLIFE SPECIES

Non-game

Small mammals—Small mammals (for example, mice,

voles, shrews and rats) are abundant in the early years of

pine stands. The origin of the stand, natural or planted, has

little influence on the mammal community (Mengak 1987).

In managed stands (in other words plantations), herbaceous

seed production is greatly reduced compared to natural

stands and the granivore (seed eaters) and herbivore

(grazers) community is missing or greatly altered compared

to natural stands. Insectivores (shrews and some birds) are

more dominant in managed stands (Buckner 1983, Mengak

and others 1989). Small mammal populations may reach

their peak between stand age 2 to 3 years depending on

site factors and then decline steadily through canopy

closure (fig. 1).

Songbirds—Songbird management is very difficult to summarize in relation to pine plantations. Songbirds are often

characterized as early successional, edge species, or

forest interior species. While mammals often show similar

preference, songbirds have not been as widely studied.

Slash pine plantations will provide suitable habitat for early

successional songbirds. Those species that nest or forage

on or near the ground will utilize pine plantations and

young natural stands. Plantation management favors edge

and early successional species. Cavity nesters can be

accommodated if sufficient snags are left during logging.

Canopy nesters will be eliminated from the harvest area

until stands reach maturity.

Management recommendations vary by species but include

such general guidelines as maintain a range of stand ages;

keep harvest areas small (< 50 acres); maintain SMZ’s;

maintain snags; and, maintain dense understory. Generally,

excluding fire can enhance songbird habitat.

Reptiles—Many reptiles are found on sites associated

with slash pine. However, relatively little literature exists

on management guidelines for reptiles. The indigo snake

(Drymarchon corais) and gopher tortoise are significant
82

inhabitants of slash pine stands because of their conservation status. Gopher tortoises (Gopherus polyphemus) are

the more conspicuous and frequently studied of the two

species.

The gopher tortoise is considered a keystone species in

the Southeastern Coastal Plain. Burrows dug by gopher

tortoises are used by over 50 other species of vertebrates

and invertebrates. The tortoise itself is long-lived reaching

ages of 50-60 years. Gophers are herbivores that prefer an

open understory and well-drained loose soil (Breininger

and others 1994). Foods include wiregrass, broad-leaf

grasses, succulent forbs and fruit. Their limited mobility

prevents them from venturing far from their burrows.

Gopher tortoises are most commonly found on the driest

sites in southern Georgia where sand depth exceeds 3 ft.

(Landers and Speake 1980). Slash pine plantations with

wide spacing of trees and abundant ground cover can

provide suitable habitat. Tortoise home range is inversely

related to ground cover density (Landers and Speake

1980).

Burrow activity and burrow abandonment is related to tree

density and canopy closure. In south-central Alabama,

Aresco and Guyer (1999) found that total tree basal area

was two times greater at abandoned burrows than at active

burrows (305 ft2 per ac versus 125 ft2 per ac, respectively).

Slash pine made up one-half of the total basal area. Tree

density was one and one-half times greater at abandoned

burrows vs. active burrows (590 trees per ac versus 323

trees per ac, respectively). Hardwood basal area was four

times greater at abandoned burrows versus active burrows

(Aresco and Guyer 1999). Canopy shading also contributes

to abandonment as the understory is lost (Aresco and Guyer

1999). In fact, burrows were abandoned at the same rate

as canopy closure. Burning without thinning was found to

eliminate understory thus reducing the suitability of the site

for tortoises. Burning and thinning should be used in

combination for gopher tortoise management.

Management objectives for gopher tortoises should be to

mimic natural canopy and understory conditions. For example, thinning stands improves overstory by removing hardwood competition and allowing light to reach the ground

surface and burning is essential to control understory

density and composition (Aresco and Guyer 1999). Gopher

tortoise habitat should be burned during the growing

season at 1 to 3 year intervals (Aresco and Guyer 1999).

Amphibians—The southeastern United States supports a

rich amphibian fauna and the highest number of species in

the country (Harris 1984:45). Hanlin and others (2000)

working on the Savannah River Site (SRS) in the South

Carolina upper coastal plain collected 1,788 individual

amphibians from 12 species during 3 summers (1994

through 1996). Fifty-seven percent of individuals were

collected from an oak-hickory forest (7.9 acre), 24 percent

from a loblolly pine forest (405. acre) and 19 percent from

a slash pine forest (42 acre). Amphibians were more

numerous in the mixed hardwood forest but slash pine had

the highest diversity of species in all 3 years of their study.

The flatwoods salamander (Ambystoma cingulatum) is a

federally threatened species that inhabits mesic longleaf/

slash pine flatwoods. This species has experienced a

rangewide population decline that is thought to be related

to habitat conversion and fragmentation of the longleaf

pine ecosystem (Palis 1997). It is now considered rare in

Georgia, Florida and Alabama; endangered in South

Carolina; and is a federally listed species (Palis 1997).

The flatwoods salamander is an autumn breeder. Breeding

migration from upland sites to ponds is correlated with rainfall and air temperature. The salamander inhabits fire-maintained, open canopy longleaf and slash pine savannahs.

Dense stands, roads, and lack of fire reduce site suitability

for this salamander. In 1987, slash pine accounted for 69

percent of all commercial pine forest in Florida; two-thirds in

plantations. This degree of habitat conversion from mature

open stands to short-rotation plantations is considered

,+



&

&

&

&

&

&

         





8

Figure 1—General model showing the decline in small mammal capture success with increasing age of

the pine stand, either natural or plantation (from Mengak 1987).
83

detrimental to flatwoods salamander populations. Means

and others (1996) found that converting native longleaf

pine savannah to bedded slash pine on the Apalachicola

National Forest may interfere with migration, successful

hatching, larval life, feeding and location of suitable postmetamorphosis cover. They concluded that longleaf pinewiregrass flatwoods have been severely reduced and

degraded throughout the coastal plain and this has contributed to the decline in flatwoods salamander populations.

CONCLUSION

Slash pine and longleaf/slash pine forests once occupied

a large area in the Atlantic Coastal Plain. Agriculture, development and intensive plantation forestry have replaced

much of the original forest. Wildlife can survive and, perhaps,

thrive in managed forests but landowners and foresters

must manipulate the vegetation to mimic natural conditions.

Manipulations include thinning, burning, and creating

openings in forest stands. Fertilization can also improve

habitat for some wildlife species. Large-scale conversion

with or without site preparation can have negative impacts

on vegetation and associated wildlife.

Landowners and foresters, who include wildlife in their

management plan, must be willing to forego some timber

revenue in exchange for increased wildlife populations.

Other papers in this volume examine financial returns from

slash pine for timber and supplemental products like pine

straw. Unfortunately, few studies examine the trade-offs in

timber production and wildlife. Such studies must include

non-timber revenue such as non-consumptive recreation,

hunting leases and aesthetic considerations. We acknowledge that such variables are not easily measured. Additional research is suggested to address non-timber values

associated with southern pines in general and slash pine

in particular.

ACKNOWLEDGMENTS

We thank Mac Lentz for obtaining the literature.

LITERATURE CITED

Aresco, M.J.; Guyer, C. 1999. Burrow abandonment by gopher

tortoises in slash pine plantations of the Conecuh National

Forest. Journal of Wildlife Management 63: 26-35.

Breininger, D.R.; Schmalzer, P.A.; Hinkle, C.R. 1994. Gopher

tortoise (Gopherus polyphemus) densities in coastal scrub

and slash pine flatwoods in Florida. Journal of Herpetology 28:

60-65.

Buckner, J.L. 1983. Wildlife concerns in the managed slash pine

ecosystem. Pp. 369-374, In: E.L. Stone, editor. The Managed

Slash Pine Ecosystem Symposium. School of Forest Resources

and Conservation, University of Florida, Gainesville, FL.

Critchfield, W.B.; Little, E.L., Jr. 1966. Geographic distribution of

the pines of the world. USDA Forest Service, Misc. Pub. 991,

97 p. Hanlin, H.G.; Martin, F.D.; Wike, L.D.; Bennett, S.H. 2000.

Terrestrial activity, abundance, and species richness of

amphibians in managed forests in South Carolina. American

Midland Naturalist 143: 70-83.

Harris, L.D. 1984. The fragmented forest: island biogeography

theory and the preservation of biotic diversity. University of

Chicago Press, Chicago, IL. 211 pp.

Hurst, G.A. 1981. Effects of prescribed burning on the eastern

wild turkey. Pp. 81-88. In: Gene. W. Wood, editor. Prescribed fire

and wildlife in southern forests. Belle Baruch Forest Science

Institute, Clemson University, Georgetown, S.C. 170 pp.

Jackson, J.J. 1993. Bobwhite quail on your land: tips on management for Georgia and the Southeast. Cooperative Extension

Service, College of Agricultural and Environmental Sciences,

University of Georgia, Athens, Ga. Bulletin 1013. 23 pp.

Jones, E.P., Jr. 1979. Slash pine. Pages 6-10. In: Brender, E.V.;

McComb, W.H.; and Hofeldt, V.H., editors. Silvicultural guidelines for forest owners in Georgia. Georgia Forest Research

Paper-6, Research Division, Georgia Forestry Commission.

Landers, J.L.; Speake, D.W. 1980. Management needs of sandhill

reptiles in southern Georgia. Proc. Annual Conf. SE Assoc. Fish

and Wildlife Agencies 34: 515-529.

Means, B.D.; Palis, J.G.; Baggett, M. 1996. Effects of slash pine

silviculture on a Florida population of flatwoods salamander.

Conservation Biology 10: 426-437.

Mengak, M.T. 1987. Impacts of natural and artificial regeneration

of loblolly pine on small mammals in the South Carolina

Piedmont. Ph.D. Dissertation, Clemson University, Clemson,

SC. 97 pp.

Mengak, M.T.; Guynn, David, C., Jr.; Van Lear, D.H. 1989. Ecological implications of loblolly pine regeneration for small mammal

communities. Forest Science 15: 503-514.

Palis, J.G. 1997. Breeding migration of Ambystoma cingulatum in

Florida. Journal of Herpetology 31:71-78.

Speake, D.W.; Lynch, T.E.; Fleming, W.J. [and others]. 1975.

Habitat use and seasonal movements of wild turkey in the

Southeast. Pp. 122-130. In: Halls, L.K., editor, Proc. Third

National Wild Turkey Symposium, Texas Chapter, The Wildlife

Society.

Tanner, G.W. 1987. Soils and vegetation of the longleaf/slash pine

forest type, Apalachicola National Forest, Florida. Pages 186-

200. In: USDA Forest Service, GTR-SO-68. Asheville, NC.

Thackston, R.; Whitney, M. 2001. The bobwhite quail in Georgia:

history, biology and management. Ga. Department of Natural

Resources, Wildlife Resources Division, Game Management

Section, Social Circle, GA. 48 pp.

USDA Forest Service. 1965. Slash pine. Pages 458-463, In:

Fowells, H.A. compiler. Silvics of forest trees of the United

States, Agric. Handbook No. 271, USDA Forest Service,

Washington, D.C.

USDA Forest Service. 2002. FIA data, www.cast.uark.edu/pif/

tables/10.html.

Wood, G.W., ed. 1981. Prescribed fire and wildlife in southern

forests. Belle Baruch Forest Science Institute, Clemson

University, Georgetown, S. C. 170 pp.

Wood, G.W. 1986. Influences of forest fertilization on South

Carolina deer forage quality. Southern Journal of Applied

Forestry 10: 203-206.

Wood, G.W. 1988. Effects of prescribed fire on deer forage and

nutrients. Wildlife Society Bulletin 16: 180-186.
84

THE ENGRAVERS AND DENDROCTONUS BEETLES

The small southern pine engraver (lps avulsus), prefers to

attack the upper portions of large trees and the main stem

of sapling-sized trees as well as logging slash. It is often

associated with Ips calligraphus which prefers the main bole

of pulpwood and sawtimber-sized trees. Ips grandicollis

prefers logging slash and the main stems of pulpwood to

sawtimber-sized trees (fig. 1). Lightning strikes, drought

stressed trees, fire damaged timber and stands infected

with annosum root disease are often focal points for Ips

infestations. Maintaining healthy stands (proper stocking,

treating stumps with Sporax® to prevent annosum root rot),

keeping stands burned and removing lightning strikes are

ways to prevent Ips infestations.

The black turpentine beetle, Dendroctonus terebrans, is

another bark beetle that frequents slash pine. This beetle is

attracted to lightning struck trees, recently thinned stands,

naval stores operations and stands damaged by fire.

The southern pine beetle, Dendroctonus frontalis, will

attack slash pine but damage is greatest when slash is

grown in mixture with loblolly. Pure stands of slash pine

are more likely to be attacked by the Ips engraver beetles

and black turpentine beetle than the southern pine beetle.

Old growth slash pine is certainly more susceptible to

southern pine beetles than young, fast growing stands.

However, southern pine beetle spots don’t grow at the

phenomenal rates in slash pine as they do in loblolly.

Currently, Onyx® (bifenthrin), is a registered insecticide that

is effective for control of pine bark beetles. Research is

underway to find other suitable replacements for Lindane

and chlorpyrifos (Dursban®, Cyren®). The new bark beetle

insecticides of the future will be more environmentally

friendly but the costs will limit the use of them.

Verbenone Pouch is an antiaggregation pheromone that

works to reduce attacks by southern pine beetles. When too

many southern pine beetles attack a tree, overcrowding

can jeopardize brood development. To prevent overcrowding the resident beetles, particularly the males, produce

verbenone that redirects incoming attacks to other nearby

trees. This behavior pattern of redirecting incoming beetle

attacks can now be used to disrupt spot growth. It is not

effective for individual tree protection. The verbenone

pouch method is currently registered by the Environmental

Protection Agency as a management technique for southern pine beetles. Additional information may be found on

the following website: http://www.bugwood.caes.uga.edu/

INSECT ENEMIES OF SLASH PINE

Terry S. Price1

1 Terry S. Price (retired), Associate Chief, Forest Management, Georgia Forestry Commission, Macon, GA 31202-0819.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Slash pine is attacked by many species of insects but only a few cause economic losses in growth and

mortality. The five species of southern pine bark beetles are without a doubt the most damaging insects affecting slash

pine. These include: the southern pine engravers (Ips avulsus, Ips calligraphus, Ips grandicollis), the black turpentine

beetle (Dendroctonus terebrans), and the southern pine beetle, Dendroctonus frontalis.

Figure 1—From top to bottom; Ips avulsus, Ips grandicollis, Ips

calligraphus, Dendroctonus frontalis, D. terebrans. (Photo by

Gerald Lenhard LSU) www.forestryimages.org.
85

OTHER SLASH PINE INSECT PESTS

Several species of conifer sawflies are capable of causing

severe defoliation and growth loss in slash pine but such

outbreaks are sporadic and usually decline on their own in

one to two years. The red-headed pine sawfly, Neodiprion

lecontei, the slash pine sawfly, N. merkeli, and the blackheaded pine sawfly, N. excitans, are common species in

the South that feed on slash pine as well as other pine

species (fig. 2). The red-headed and slash pine sawflies

prefer to feed on young trees less than ten years of age

and the blackheaded pine sawfly prefers sapling to

mature, sawtimber-sized trees.

An interesting beetle that is often found attacking the charred

bark of slash and other southern pines is the bostrichid

beetle Rhyzopertha dominica. This insect is probably

native to India and will feed on all kinds of stored grains and

a wide variety of foods, chiefly cereals. When it attacks the

bark of burned pines it produces a reddish-brown, powdery

boring dust that resembles that of Ips species (fig. 3). The

beetle does not harm trees and therefore, no control is

necessary. It feeds only in the outer bark and does not

enter the cambium.

Weevils that often debark slash pine seedlings are the

pales, Hylobius pales, and pitch-eating, Pachylobius

picivorus. These weevils damage seedlings by chewing

bark from the stem above and below ground (figs. 4 and 5).

Seedlings are often girdled and killed. Damage can be

prevented or reduced when conditions favoring weevil

development are avoided. Both species are attracted to

recently logged areas with fresh pine stumps and buried

logging slash. Adult weevils deposit eggs in the roots of

freshly cut pine stumps or buried logging slash. The larvae

hatch in a few days and begin feeding beneath the bark.

Upon emergence the new adults will seek out seedlings to

feed on. The newly emerging weevils and older adults

attack seedlings planted on or adjacent to these cut over

areas. The following guidelines will help reduce weevil

damage:

• Delay planting one year on cutover pine sites if harvest

cannot be completed before July.

• If planting cannot be delayed, the seedlings should be

dipped in an approved insecticide or top sprayed in the

nursery before lifting.

• Delay cuttings/thinnings that are adjacent to recently

planted pines until seedlings are 3 to 4 years old.

• Planted seedlings can be sprayed in the field with an

approved insecticide if weevils begin to appear.

In general, slash pine has two distinct forest health advantages over loblolly pine. Slash pine is less susceptible to

attacks from the southern pine beetle and is seldom seriously damaged by the Nantucket pine tip moth. This should

be considered when selecting a pine species to plant.

Figure 2—Red-headed pine sawfly larvae. Photo by Ron Billings,

Texas Forest Service, www.forestryimages.org.

Figure 3—Boring frass from Rhyzopertha dominica (a bostrichid

beetle). Photo by Stan Moore, GFC.

Forest Inventory and Analysis (FIA) data for 1972 and 1997

for a few selected Georgia counties indicate a decline in

slash pine acreage and an increase in loblolly pine acreage

(table 1). If this trend continues, that is, the replacement of

slash with loblolly, we may see an increase in the incidence

and severity of southern pine beetle outbreaks and other

insects simply because we have changed the pine component from a less susceptible host to a more susceptible,

one which is loblolly.
86

Figure 4—Pitch-eating weevil feeding on pine seedling. Photo by

Robert L. Anderson, USDA Forest Service,

www.forestryimages.org.

Figure 5—Pales weevil. Photo by Clemson University-USDA

Cooperative Extension Slide Series, www.forestryimages.org.

Table 1—Change in loblolly and slash pine acreage in selected Georgia counties

based on FIA data

Loblolly +/- Slash +/-

County 1972 1997 Change 1972 1997 Change

Appling 11,800 39,400 +27,600 128,342 99,578 -28,764

Atkinson 11,200 18,800 +7,600 88,958 71,762 -17,196

Bacon 4,400 18,000 +13,600 72,308 57,906 -14,402

Baker 17,600 14,200 - 3,400 17,036 12,313 -4,723

Ben Hill 10,000 37,800 +27,800 71,874 37,353 -34,521

Berrien 12,500 21,100 +8,600 77,483 68,169 -9,314

Brantley 4,100 10,800 +6,700 137,495 111,598 -25,897

Brooks 12,800 22,500 +9,700 18,061 34,671 +16,610

Charlton 14,100 11,200 - 2,900 187,245 227,707 +40,462

Clinch 24,800 28,300 +3,500 280,575 295,983 +15,408

Coffee 7,100 44,500 +37,400 124,521 91,056 -33,465

Cook 6,300 12,400 +6,100 15,810 11,379 -4,431

Echols 3,800 7,800 +4,000 128,324 122,106 -6,218

Irwin 10,000 15,300 +5,300 42,380 34,606 -7,774

Jeff Davis 16,600 35,700 +19,100 56,388 65,417 +9,029

Lanier 10,200 7,800 - 2,400 29,911 40,884 +10,973

Laurens 42,600 102,300 +59,700 111,509 48,012 -63,497

Lowndes 34,900 13,400 - 21,500 52,128 65,275 +13,147

Miller 0 10,100 +10,100 18,786 8,893 -9,893

Pierce 8,900 10,500 +1,600 59,330 52,539 -6,791

Seminole 4,100 12,200 +8,100 12,378 7,644 -4,734

Tift 0 8,500 +8,500 33,918 10,479 -23,439

Treutlen 0 19,400 +19,400 54,602 50,647 -3,955

Turner 7,700 17,200 +9,500 31,473 31,699 +226

Ware 15,900 31,100 +15,200 218,834 260,776 +41,942

Wheeler 3,300 50,000 +46,700 68,622 42,312 -26,310

Worth 10,100 36,700 +26,600 86,399 40,941 -45,458

Total 304,800 657,000 +352,200 2,224,690 2,001,705 -222,985
87

INTRODUCTION AND

HISTORICAL PERSPECTIVES

The previous slash pine symposium contained a comprehensive review of diseases of slash pine. Major disease

occurrence was discussed by Blakeslee (1983) and disease management was detailed by Belanger and others

(1983). These papers and an earlier report (Schmidt and

Wilkinson 1979) serve slash pine disease management

well today and here there is a need only to update the

previous recommendations.

The 1970s, 1980s and early 1990s were dynamic and

productive years for forest pathology in the South and for

disease management of slash pine, in particular. The

forest industry sought information on major diseases,

especially in intensively managed pine plantations and

they were significantly engaged in cooperative research in

pest management (Miller and Schmidt 1987). State and

federal agencies were responsive to public and private concerns and research and extension programs were staffed

with forest pathologists. Now, priorities have changed.

Public agencies are espousing forest health with the

emphasis on the environment. They have renewed interests in longer rotation and restoration of longleaf pine and

have relegated productivity to a lesser priority. Forest

industry, while still interested in productivity, is now more

driven by environmental issues, company image and

business decisions and, collectively is less involved in

woodland research, including research on tree diseases.

Many companies no longer own the land necessary for

long-term research. At educational institutions, once viable

graduate programs in forest pathology now languish for

lack of students, especially domestic students and those

interested in the ecology of disease (epidemiology).

On the positive side, new technology, for example, biotechnology, is contributing to basic research, and researchers

are attempting to understand the basic processes underlying the great store of empirical relations developed in the

last four decades. If this quantum leap is successful, rapid

advances can be made in forest management, including

disease management.

DISEASE MANAGEMENT

While there has been significant research findings on several slash pine pathosystems since the 1981 Slash Pine

Symposium, disease management recommendations have

changed little in the interim. Current recommendations are

available in recent research and extension publications

and only a cursory treatment of new information which

affects or could potentially affect disease management

issues are noted herein.

Fusiform Rust

Fusiform rust, caused by Cronartium quercuum f. sp. fusiforme remains the most important disease in slash pine

plantations. Updated regional rust hazard maps and associated analyses (Starkey and others 1997) show current

rust distribution and recent changes occurring in rust incidence in the southeastern USA. Guidelines for rust hazard

prediction at the stand level, including oak abundance, rust

in adjacent stands, soil type and site quality are summarized by Schmidt (1998). Studies indicate that inoculum from

surrounding oaks within one-half mile can cause significant rust incidence in adjacent pine plantations (Froelich

and Snow 1986) and that removal of on-site oaks have little

effect on disease incidence on pine in high-rust-hazard

areas (Schmidt and others 1995). Genetic disease resistance has proven to be the best rust management practice

(Powers and others 1976; Schmidt and others 1981, 1985;

Schmidt and Allen 1997), and major advances have

occurred in characterizing this resistance in both slash and

loblolly pine (Walkinshaw and others 1980, Schmidt and

others 2000), including the identification of major genes

associated with resistance (Wilcox and others 1996). But it

remains to determine the number and effects of genes

associated with resistance and to determine the stability of

host resistance and of pathogen adaptation and frequency

of virulence in the slash pine ecosystem. Current rust

management recommendations are published (Powers

and others 1993, Schmidt 1998, Schmidt 2001), including

guidelines for sanitation-salvage thinning of rust-infected

stands (Belanger and others 2000). Bayleton® provides

effective control of fusiform rust in nurseries and disease

resistant planting stock provide the best control of rust in

newly established plantations.

MAJOR DISEASE ISSUES WITH SLASH PINE MANAGEMENT

Robert A. Schmidt1

1 Robert A. Schmidt, Professor of Forest Pathology, School of Forest Resources and Conservation, University of Florida, Gainesville FL

32611.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—The major disease problems related to slash pine management are well documented. However, as forest

management practices evolve, pest management issues are changing. The potential effects of these changing issues

on forest conditions are discussed.
88

Pitch Canker

Pitch canker of pines caused by Fusarium subglutinens,

while of sporadic and unpredictable occurrence and incidence, is an important disease of slash pine, as it causes

significant damage to seeds, seed orchards, nurseries and

plantations of all ages (Blakeslee and others 1980). Genetic

resistance to the pathogen occurs in slash pine (Blakeslee

and Rockwood 1978) but resistant seedlings for planting

are not readily available. Pitch canker occurrence, incidence

and severity are often closely related to environmental factors such as fertilization and drought. Insects often can play

an important role since wounds are required for infection.

Infected stands have been associated with commercial

chicken houses, where high levels of chemicals deposited

in the soil or on needles may dispose trees to pitch canker.

Precommercial thinning in loblolly plantations reduced

subsequent pitch canker incidence and severity, especially

during conditions of severe pitch canker outbreaks

(Blakeslee and others 1999).

Annosum Root Decay

Short rotations and clear-cutting have all but eliminated

annosum root decay from the slash pine plantation

ecosystem. However, if longer rotations and associated

thinning become more prevalent, this once feared and

important disease will likely rear it’s ugly head once again,

especially on moderately to well-drained sandy soils

common to slash pine cultivation. Spraying bonax on

freshly-cut stumps is an effective control, (Froelich and

others 1977) otherwise infected stands should be partially

or completely harvested.

Planting Survival on Converted Agricultural

Croplands

Planting previously cultivated fields, especially pasture

land, as was often done during the Conservation Reserve

Plantings (CRP), frequently resulted in poor seedling

survival. “Scalping” down to bare soil in the planting row

prior to planting alleviates this problem, as competitive

vegetation, insects and fungal pests are removed from the

near vicinity of young seedling stems and roots (Barnard

and others 1995).

FUTURE SLASH PINE DISEASE ISSUES

As future forest management priorities and practices

evolve, pest management issues will change. Witness the

introduction of the red heart pathogen (Phellinus pini) into

longleaf pine to create nesting cavities for the red

cockaded woodpecker. Presently, several potential issues

include:

Biotechnology

Biotechnology will create new synthetic genotypes

improved for desired traits. These new plant materials

should be field-tested for their reaction to forest pests.

Clonal Forestry

When clonal forestry becomes a reality, new pest issues

will accompany vegetative propagation, container-grown

planting material and genetic diversity. Clonal forestry

without safeguards against pathogen adaptation will be

risky.

Intensive Culture

Fertilization and competition control promote rapid, succulent growth, which in turn can predisposes pines to some

pathogens and/or create physiological disorders. Fastergrowing trees are not necessarily healthier trees.

Longer Rotations

Short rotations and clear-cutting have reduced or eliminated some diseases, for example, stem and root decays.

Longer rotations with associated thinnings will likely see

an increase in these problems, for example, annosum root

rot.

Geographic Information Systems (GIS)

New technology in GIS will improve our ability to detect and

inventory disease occurrence, thereby improving opportunities for timely pest management. The interactive capabilities of GIS can help to better understand disease ecology,

that is, climatic, edaphic and biotic effects on forest tree

diseases.

Global Forestry Markets

The global marketplace affects and, in turn, is affected by

forest tree pathogens. Export markets take issue with

southern pine products infected or potentially infected with

pathogens, for example, the pinewood nematode and pitch

canker. Likewise, the importation of wood and fiber raises

issues of the potential introduction of exotic plant pathogens into the slash pine ecosystem. Such introductions

can have significant, even disastrous impacts.

Slash Pine in the Urban Environment

Slash pine used as shade and landscape trees in yards,

golf courses and municipal settings suffer unique diseases

associated with anthropogenic effects, for example, wounding, excess or deficiencies of water, use of chemicals for

weed control, soil compaction and soil nutrient and pH

imbalance. As populations and urbanization expand these

problems will become more prevalent.

Methyl Bromide Replacement

With the impending removal of methyl bromide from the

marketplace, finding a replacement for use in slash pine

nurseries is an important issue.

Wood Preservation

As chromated copper arsenate (CCA) is removed from the

marketplace because of concerns regarding arsenic toxicity, a suitable replacement will be needed, especially for

residential construction. Currently, disposal of CCA-treated

wood is an important issue, especially for municipal

landfills.

Climate Change

Who knows what evils lurk behind the potential threat of

climate change? We do know that temperature and moisture (both soil and leaf surface moisture) can profoundly

affect pathogens and the incidence and severity of the

diseases they incite.
89

Education and Training of Forest Pathologists

Retirements have greatly thinned the ranks of forest

pathologists. The educational pipeline for traditional forest

pathologists in the South is essentially dry, appropriately

so in view of the lack of jobs. If new positions become

available, they will likely be filled with laboratory-oriented

biotechnologists. Where will the traditional research forest

pathologists come from, for example, those trained in

etiology and epidemiology?

LITERATURE CITED

Barnard, E.L.; Dixon, W.N.; Ash, C.E. [and others]. 1995. Scalping

reduces impact of soilborne pests and improves survival and

growth of slash pine seedlings on converted agricultural croplands. South. J. Appl. For. 19: 49-59.

Belanger, R.P.; Miller, T.; Schmidt, R.A. 1983. Pest management in

slash pine. Pp. 273-287 in: E. L. Stone (ed.). Proceedings June

1981, The Managed Slash Pine Ecosystem Symposium, School

of Forest Resources and Conservation, University of Florida.

434 p.

Belanger, R.P.; Miller, T.; Zarnoch, S.J. [and others]. 2000. An

integrated approach toward reducing losses from fusiform

rust in merchantable slash and loblolly pine plantations. U.S.

Department of Agriculture, Forest Service, Southern Research

Station.

Blakeslee, G.M. 1983. Major diseases affecting slash pine. Pp.

257-272. In: E.L. Stone (ed.). Proceedings June 1981. The

Managed Slash Pine Ecosystem Symposium, School of Forest

Resources and Conservation, University of Florida. Fla. 434 p.

Blakeslee, G.M.; Dwinell, L.D.; Anderson, R.L. 1980. Pitch canker

of southern pines: identification and management considerations. U.S. Department of Agriculture, Forest Service. Southeastern Area Forest Report SA-FR11.

Blakeslee, G.M.; Jokela, E.J.; Hollis, C.H. [and others]. 1999. Pitch

canker in young loblolly pines: influence of precommercial

thinning and fertilization on disease incidence and severity.

South. J. Appl. For. 23: 139-143.

Blakeslee, G.M.; Rockwood, D.L. 1978. Pitch canker resistance in

slash pine. Cooperative Forest Genetics Research Progress

Report No. 28. School of Forest Resources and Conservation

University of Florida, Gainesville.

Froelich, R.C.; Kuhlman, E.G.; Hodges, C.S. [and others]. 1977.

Fomes anosus root rot in the South: guidelines for prevention.

Southeastern Area. U. S. Department of Agriculture, Forest

Service.

Froelich, R.C.; Snow, G.A. 1986. Predicting site hazard to fusiform

rust. For. Sci. 32: 21-35.

Miller, T.; Schmidt, R.A. 1987. A new approach to forest pest

management. Plant Dis. 71: 204-207.

Powers, H.R.; Kraus, J.F.; Duncan, H.J. 1976. Development of

rust resistant slash and loblolly pines in Georgia. Georgia

Forestry Research Council Paper No. 87.

Powers, H.R.; Miller, T.; Belanger, R.P. 1993. Management strategies to reduce losses from fusiform rust. South. J. Appl. For. 17:

146-149.

Schmidt, R.A. 1998. Fusiform rust disease of southern pines:

biology, ecology and management. Technical Bulletin 903.

Agricultural Experimental Station, Institute of Food and

Agricultural Sciences, University of Florida. Gainesville.

Schmidt, R.A. 2001. Fusiform rust of southern pines: preventing

and minimizing financial loss. For. Landow. 60(3): 18-21.

Schmidt, R.A.; Allen, J.E. 1997. Fusiform rust epidemics in family

mixtures of susceptible and resistant slash and loblolly pines.

In: pp. 309-319, Proceedings 24th Biennial Southern Forest

Tree Improvement Conference. Orlando FL.

Schmidt, R.A.; Allen, J.E.; Belanger, R.P.; Miller, T. 1995. Influence

of oak control and pine growth on fusiform rust incidence in

young slash and loblolly pine plantations. South. J. Appl. For. 19:

151-156.

Schmidt, R.A.; Gramacho, K.P.; Miller, T.; Young, C.H. 2000. Components of partial resistance in the slash pine - fusiform rust

pathosystem. Phytopathology 90: 1005-1010.

Schmidt, R.A.; Holley, R.C.; Klapproth, M.C. 1985. Results from

operational plantings of fusiform rust resistant slash and loblolly pines in high rust incidence areas in Florida and Georgia.

In: pp. 33-41. J. Barrows-Broaddus and H.R. Powers (eds.).

Proceedings of the International Union of Forest Research

Organizations. Rust of hard pines Working.. Party Conference

S2.06-10. Athens, Ga. 331 p.

Schmidt, R.A.; Powers, H.R., Jr.; Snow, G.A. 1981. Application

of genetic disease resistance for the control of fusiform rust

in intensively managed southern pine. Phytopathology 71:

993-997.

Schmidt, R.A.; Wilkinson, R.C. 1979. Prospects for integrated pest

management in slash pine ecosystems in Florida. Proceedings

August 5-11, Washington, D.C. Symposium of the Ninth

International Congress Plant Protection.

Starkey, D.A.; Anderson, R.L.; Young, C.H. [and others]. 1997.

Monitoring incidence of fusiform rust in the South and change

over time. U.S. Department of Agriculture, Forest Service.

Southern Region Forest Health Protection Report. PR-XXX.

Atlanta, GA.

Walkinshaw, C.H.; Dell, T.R.; Hubbard, S.D. 1980. Predicting field

performance of slash pine families from inoculated greenhouse

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

Southern Forest Experiment Station Research Paper SO-160.

6 p.

Wilcox, P.L.; Amerson, H.V.; Kuhlman, E.J. [and others]. 1996.

Detection of a major gene for resistance to fusiform rust

disease in loblolly pine by genomic mapping. In: Proceedings p.

3859-3864. Applied Biological Sciences. National Academy of

Sciences. U.S.A.
90

INTRODUCTION

Demand for pinestraw for use in landscaping has resulted

in a market niche for the procurement, harvest and distribution of pinestraw. Anticipated growth in the market for

baled pinestraw, coupled with an attractive income opportunity prior to timber harvest, offers forest landowners an

incentive to include pinestraw in their management plans.

Potential benefits to the landowner do not come without

potential costs to the site. Pinestraw plays an important

role in maintaining the productivity of relatively infertile

soils supporting southern pine forests. Harvest of pinestraw

interrupts the cycling of nutrients in the forest ecosystem

and may lead to reduced tree growth, reduced needle

production and poor stand condition. The impacts of pinestraw removal and nutrient depletion have been observed

and questioned for over a century (Ebermayer 1876), and

it is generally accepted that repeated pinestraw removal

without nutrient amendment can decrease growth (Jemison

1943). Although more recent studies have addressed the

effects of forest floor removal on nutrient cycling (Blevins

1994) and management practices for pinestraw production

(Duryea and Edwards 1984, Mills and Robertson 1991),

few have specifically investigated shorter term growth

responses to pinestraw removal in fertilized stands (McNeil

and others 1984, McLeod and others 1979). Typically,

southern pine plantations are thinned and fertilized at midrotation to encourage growth on the residual stand. When

managed for pinestraw production, thinning is postponed

or skipped entirely because of its detrimental effect on

pinestraw production and recovery. Thinning drops limbs

and debris, reduces basal area which results in reduced

straw fall, and opens gaps in the canopy allowing for competing vegetation which interferes with the raking process.

Without thinning, competition among trees for available

resources is intensified, and growth of individual stems is

not as responsive to fertilization as in less competitive

environments.

The objective of this study was to measure the effects of

annual pinestraw removal and mid-rotation fertilization on

unthinned slash and loblolly stands. Comparisons of

timber and pinestraw yields provide an economic analysis

of one common approach to pinestraw management.

MATERIALS AND METHODS

The effects of straw removal and fertilization were assessed

in replicated experiments during a 5-year period in slash

and loblolly pine plantations. Experimental treatments consisted of a factorial combination of two levels of pinestraw

removal (no removal and annual removal) and two fertilization treatments (no fertilization and fertilization with 224

kg ha-1 nitrogen (N), 56 kg ha-1 phosphorus (P), and 56 kg

ha-1 potassium (K) for a total of four treatments. Each plantation began with at least three replications in complete

blocks.

Five study sites were established in Georgia: two loblolly

sites located in the Upper Coastal Plain, two slash pine

sites also in the Upper Coastal Plain, and an additional

loblolly site in the Lower Coastal Plain flatwoods (table 1).

Areas determined to be commercially rakeable were

selected, and 0.1 ha treatment plots were established.

Responses were measured on plots of 0.04 ha nested

within the gross treatment plots.

Foliar samples were collected from each plot prior to fertilization, and again at the end of the third growing season.

Samples were oven dried at 70°C, ground and sieved to

pass through a 1 mm mesh screen. Nitrogen and P concentrations were determined colorimetrically by the Technicon

Auto Analyzer II (Industrial Method No.334-7A and 144-

71a 1972) following block digestion (Isaac and Johnson

1976). Potassium, Ca, and Mg concentrations were determined following perchloric acid digest (Georgia Cooperative

Extension Service 1970) by atomic absorption spectroscopy (Perkin-Elmer 1987).

EFFECTS OF ANNUAL PINESTRAW REMOVAL AND MID-ROTATION

FERTILIZATION ON PINE GROWTH IN UNTHINNED PLANTATIONS

E.A. Ogden and L.A. Morris1

1 Lee Ogden, Research Coordinator; and Larry Morris, Professor of Forest Soils, University of Georgia, Daniel B. Warnell School of Forest

Resources, Athens, GA 30602-2152.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Harvesting of pinestraw in southern pine plantations provides landowners an opportunity to increase income

but also may result in decreased growth due to nutrient removal. A factorial experiment combining two levels of

pinestraw removal (none and annual) and two levels of fertilization (none and a single NPK fertilization) was replicated in

five unthinned planted slash (Pinus elliotii Engelm.) or loblolly (Pinus taeda L.) pine stands located on cut-over and oldfield sites. Fertilization in the first year with 224, 56 and 56 kg ha-1 of N, P and K, respectively, did not significantly

increase stem volume growth, and on one site, was associated with reduced volume due to increased mortality.

Pinestraw yields generally increased as a function of basal area. Although fertilized plots produced more pinestraw,

increases in understory vegetation hampered pinestraw harvest. Annual pinestraw removal did not significantly reduce

pine volume growth during the five-year period of study. Green foliar nutrient contents were above critical levels and did

not differ among treatments.
91

Soil series were determined from county soils maps and

confirmed by on-site examination. Soil characteristics were

considered when prescribing fertilizer and herbicide application rates. Fertilizer was applied at rates of 224-56-56

kg ha-1 of N-P-K, respectively. These rates were close to

rates applied in operational mid-rotation fertilization and

exceeded the projected nutrient removal in five years of

annual pinestraw harvest. Dry formulations of commercially

available urea (46-0-0), triple superphosphate (0-46-0),

and muriate of potash (0-0-60) were the applied in the first

dormant season. Sites varied widely in severity of vegetative competition, especially after fertilization. Hardwood

sprouts were cut repeatedly. Heavy grass and blackberry

infestations were treated with backpack spray applications

of Velpar® and Roundup®.

Manual raking was conducted by crews as part of commercial operations or by University personnel so as to emulate

commercial harvesting. Only fresh, “clean” straw (free of

leaves, sticks, cones, or weeds) from readily accessible

areas was harvested. Raking occurred annually, usually in

the fall. Bale counts and weights, or weights of straw raked

from subplots randomly located within the measurement

plots, were used to quantify removals from the sites. Subsamples of straw from the harvest were collected for nutrient content analysis to determine actual nutrient removal

from the site.

Height and diameter measurements were taken at the time

of experimental blocking, and annually thereafter. Basal

area and volume of individual stems were calculated based

upon species and location, and used to compare growth

over time (Bailey and others 1985, Belcher and Clutter

1977). Differences in growth and nutrient concentration

among treatments were tested using a general linear

models procedure (SAS 1987) with and without initial plot

basal area as a covariate.

RESULTS AND DISCUSSION

Growth and Yield

Growth response to fertilization was expected to be most

evident on sites that were not raked. These trees would

benefit from additional nutrients without any losses from

pinestraw removal. Since these plots were undisturbed

after the fertilizer application, the trees may also have

benefitted from the mulching effect of the intact forest floor

and improved soil microclimate and moisture availability.

Plots that were fertilized but also raked were expected to

show some fertilizer response compared with the control

plots, due to the addition of nutrients to supplement losses

through pinestraw harvest. Any negative response to

raking would have been most evident on plots which were

raked but received no fertilization.

Generally, heights and diameters increased with fertilization, and were unaffected by raking (table 2). However,

these differences were not statistically significant among

any of the treatments at any of the sites. Loblolly pine

growth at the Rincon and Louisville sites followed the hypothesized response to fertilization and raking. A non-significant positive diameter response to raking was observed in

slash pines at Wrightsville and Albany. A negative response

of average tree height to fertilization at Wrightsville was

also observed. Basal area and stand volume calculations

followed similar patterns (table 2). Volume response of

loblolly pine to N or NP fertilization generally lasts for a five

to seven year period with maximum response occurring

during the first three years following application (Fisher

and Garbett 1980). Observed volume responses were

within documented ranges (McNeil and others 1984).

Analysis of variance for stand volume revealed that neither

raking nor fertilization treatments were significantly different

(at the .05 confidence level) from the control. The results

were similar to findings reported by McKee and Mims (1995).

The positive effect of raking at Wrightsville is not easily

explained and may be spurious. Raking can reduce

Table 1—Characteristics of five mid-rotation plantations used to evaluate growth response to

pinestraw harvest with and without mid-rotation fertilization

Status at study establishment

Location Species Soil series Age Site index Stocking Basal area

years m @ age 25 stems/ha m2/ha

Rincon Loblolly Rigdon sand 21 19.2 1,262 32.35

Olustee fine sand 18.3

Louisville Loblolly Dothan sandy loam 19 18.3 1,442 36.13

 old-field

Louisville Loblolly Dothan sandy loam 16 18.3 1,670 29.88

 cut-over Faceville fine sandy loam 17.7

Albany Slash Tifton sandy loam 15 18.3 1,764 23.71

Wrightsville Slash Dothan sandy loam 12 18.3 1,772 21.96

Fuquay sand 18.3
92

interception of precipitation by the forest floor and increase

soil temperatures leading to more rapid decomposition

and nutrient mineralization potentially contributing to shortterm improvements in tree growth.

Since tree growth is dependent upon various stand characteristics, a covariant analysis, using initial basal area as

the covariant with subsequent basal area, was applied in

an attempt to remove natural variation caused by initial

differences in stocking or tree size at the start of the study.

As in previous analyses, none of the treatments were

statistically significantly different in height, diameter, basal

area, or volume.

Mortality in several of the treatment plots decreased stand

basal area and volume (table 2). On all sites except Rincon,

mortality was higher on fertilized plots, with statistically

significant losses occurring at the Albany site. Fertilization

accelerates stand development (Allen 1987) and in these

unthinned stands, some increased mortality was expected.

A relationship between fertilization (tree vigor) and

increased mortality due to fusiform rust also exists, particularly in slash pine (Dinus and Schmidtling 1971). Fusiform

rust in the slash pines at Albany and Wrightsville caused

high mortality and reductions in basal area and volume,

especially after fertilization.

Table 2—Mean annual growth of unthinned loblolly and slash pine stands

with or without fertilization and annual raking for a 5-year period

Management Height Diameter Basal area Volume Mortality

m/yr cm/yr m2 /ha/yr m3/ha/yr trees/ha/yr

Rincon loblolly pine

Not fertilized

Not raked 0.58 0.43 0.66 12.3 28

Raked 0.52 0.43 0.78 9.0 41

Fertilized

Not raked 0.76 0.59 1.25 18.7 14

Raked 0.74 0.60 0.75 14.2 48

Louisville old-field loblolly pine

Not fertilized

Not raked 0.82 0.29 0.75 16.8 41

Raked 0.79 0.28 0.82 19.4 70

Fertilized

Not raked 0.87 0.38 0.81 15.7 41

Raked 0.77 0.31 0.61 14.7 74

Louisville cut-over loblolly pine

Not fertilized

Not raked 0.76 0.45 1.64 18.5 44

Raked 0.74 0.43 1.34 16.7 21

Fertilized

Not raked 0.91 0.60 2.04 22.9 54

Raked 0.93 0.61 1.41 19.1 65

Albany slash pine

Not fertilized

Not raked 0.44 0.78 1.83 19.2 54

Raked 0.37 0.86 2.05 19.8 44

Fertilized

Not raked 0.58 0.97 0.32 11.8 142

Raked 0.49 0.91 0.29 12.1 98

Wrightsville slash pine

Not fertilized

Not raked 0.55 0.82 1.82 19.4 25

Raked 0.80 0.85 2.31 24.1 33

Fertilized

Not raked 0.73 0.82 1.43 17.0 49

Raked 0.83 0.81 2.47 23.3 33
93

At the Louisville and Rincon loblolly sites, mortality

increases were observed on raked plots. At the Albany and

Wrightsville slash stands, there was no increase in mortality associated with raking.

Site Conditions

No soil erosion or compaction was observed as a result of

either raking or fertilizing activity on any of these sites. This

may be attributed to the low slope gradients (0-3 percent)

and relatively sandy nature of the surface soils. It does not

appear that pinestraw removal activity or the application of

fertilizer or herbicide adversely affected the physical attributes of the soil. Although these experimental sites were

fertilized by hand spreader, herbicided by backpack sprayer,

and raked and baled by hand, machine operation would

probably not be precluded.

Tree Nutrition

Pre-treatment foliar analyses showed that trees on all sites

had sufficient concentrations of macro- and micro nutrients

for tree growth (table 3). No significant changes in foliar

nutrient concentrations could be attributed to either raking

or fertilization before or after treatments. Foliar nutrient

analysis performed in year 3 showed that on most sites

and most treatments, trees had levels of N, P, K, Ca, and

Mg at or above sufficiency levels considered necessary for

tree growth (Allen 1987, NCSFNC 1991, Blevins 1994).

The only exceptions were a slight nitrogen deficiency on

control treatments at four of the five sites, and a slight

potassium deficiency on control and rake-only treatments

at the Louisville cut over site.

Table 3—Nutrient content of green foliar samples before and 3 years

after treatment

Management Period N P K Ca Mg

years percent - - - - - - parts per million - - - - - -

Rincon loblolly pine

Not fertilized

Not raked 1990/91 0.85 1,017 2,967 2,230 692

1993/94 0.98 1,017 3,000 2,175 648

Raked 1990/91 0.88 919 2,900 2,256 643

1993/94 0.95 1,002 3,000 2,200 637

Fertilized

Not raked 1990/91 0.87 976 2,933 2,250 747

1993/94 0.95 1,006 3,033 2,175 733

Raked 1990/91 0.80 953 3,008 2,831 738

1993/94 0.93 1,017 3,133 2,350 761

Louisville old field loblolly pine

Not fertilized

Not raked 1990/91 1.37 1,400 3,600 2,350 1,200

1993/94 1.33 1,383 3,583 2,325 1,258

Raked 1990/91 1.31 1,450 3,650 2,200 1,200

1993/94 1.21 1,400 3,467 2,092 1,192

Fertilized

Not raked 1990/91 1.35 1,400 3,400 2,050 1,200

1993/94 1.34 1,400 3,433 1,983 1,142

Raked 1990/91 1.40 1,350 3,700 2,150 1,250

1993/94 1.42 1,300 3,708 2,267 1,275

Louisville cut-over loblolly pine

Not fertilized

Not raked 1990/91 0.98 1,450 2,567 2,525 1,200

1993/94 1.03 1,450 2,542 2,475 1,217

Raked 1990/91 1.10 1,500 2,900 2,975 1,200

1993/94 1.19 1,517 2,967 3,008 1,192

Fertilized

Not raked 1990/91 1.18 1,300 3,500 3,117 1,200

1993/94 1.23 1,300 3,683 3,142 1,150

Raked 1990/91 1.25 1,300 3,100 2,700 1,217

1993/94 1.27 1,317 3,067 2,617 1,167

continued
94

Pinestraw Production

Fertilization of slash pine stands increases straw production approximately 1150 kg ha-1 yr-1 for the first three years

following mid-rotation fertilization (NC State Forest Tree

Nutrition Cooperative and Cooperative Research in Forest

Fertilization (CRIFF) (NCSFNC 1991)). Pinestraw yield in

young stands is closely correlated with basal area (DallaTea and Jokela 1991). For slash pines grown in fully

stocked plantations, there is an increase of about 1010 kg

ha-1 yr-1 for every additional 1.7 m2 of basal area, up to a

maximum of about 5050 kg ha-1 at around age 15 (Gholz

and others 1985). In loblolly pines, straw production will

reach 5050 to 5615 kg ha-1 at 9.3 to 10.2 m2

 of basal area

(Gresham 1982, Switzer and Nelson 1972). For less

intensively managed or more mature stands, the rates are

lower for a given basal area (Hennessey and others 1992).

Since only the RAKE-ONLY and RAKE&FERT plots were

actually raked, only a fertilizer response can be evaluated

here. Significant differences between the RAKE&FERT

plots (mean 696 kg ha-1 increase) compared with the

RAKE-ONLY plots (mean 414 kg ha-1 increase) occurred.

Straw yield response varied significantly between sites: the

only sites not statistically significantly different were the two

Louisville sites. Loblolly pines at the Rincon site exhibited

the largest response to fertilization, yielding 2140 kg ha-1 in

the third year in conjunction with a 5 m2 increase in basal

area (table 4). Non-fertilized plots yielded 1010 kg ha-1 of

straw and a basal area increase of 3 m2 in the same period.

At the two Louisville sites, loblolly pines responded less

dramatically: fertilized plots on old field and cut-over sites

increased only 110 and 680 kg ha-1, respectively, despite

basal area gains of 1.7 and 6.2 m2

. Although the Rincon

and Louisville old field sites were the oldest stands in the

study, and past what would normally be considered the

peak of pinestraw production (Gresham 1982), non-fertilized plots at the old field site still yielded 650 kg ha-1.

Slash pines at Wrightsville exhibited a similar straw yield

response to fertilization (table 4). Though the RAKE&FERT

plots gained 5.7 m2 of basal area over 3 years, they yielded

960 kg ha-1 more straw in the third year. The RAKE-ONLY

plots gained 9.5 m2 of basal area in the same period, but

yielded only 560 kg ha-1 more straw. Differences in basal

Table 3—Nutrient content of green foliar samples before and three

years after treatment (continued)

Management Period N P K Ca Mg

years percent - - - - - - parts per million - - - - - -

Albany slash pine

Not fertilized

Not raked 1990/91 0.97 1,400 3,500 2,600 1,005

1993/94 0.96 1,317 3,458 2,675 992

Raked 1990/91 1.00 1,400 3,700 3,200 1,175

1993/93 1.05 1,300 4,058 3,325 1,200

Fertilized

Not raked 1990/91 0.96 1,400 3,400 2,600 1,000

1993/94 1.07 1,500 3,558 2,625 992

Raked 1990/91 1.00 1,400 3,300 2,400 900

1993/94 1.07 1,300 3,200 2,008 875

Wrightsville slash pine

Not fertilized

Not raked 1990/91 0.90 1,300 3,200 2,300 1,000

1993/94 0.92 1,300 3,100 2,200 1,167

Raked 1990/91 0.99 1,300 3,150 2,300 1,075

1993/94 1.07 1,200 3,383 2,233 1,150

Fertilized

Not raked 1990/91 1.00 1,300 3,350 2,000 1,003

1993/94 1.09 1,250 3,617 1,875 958

Raked 1990/91 1.10 1,300 3,350 2,300 1,033

1993/94 1.05 1,083 3,358 2,317 1,050

Sufficiencya 1.0–

 1.1 1,000 3,000 1,000 600

a Source: Allen (1987), Blevins (1994), NCSFNC (1991).
95

area growth are attributed to higher mortality on the fertilized plots. Pinestraw theft confounded straw yield estimates here and at Albany. At Albany, where tree mortality

was high and severe weed infestation prevented optimal

straw recovery, slash pines showed decreased straw yield

on both treatments despite gains of 6.2 m3

 and 1.2 m2 of

basal area over 3 years on the RAKE-ONLY and

RAKE&FERT treatments, respectively. The slash pines at

Albany and Wrightsville were the youngest stands in the

study, and should have been near their maximum straw

yield (Gholz and others 1985).

Nutrient Removal

Based upon the nutrient content of grab samples of straw

raked from the Rincon, Albany, and Louisville sites, an

average of 38.2 kg of N, 1.4 kg of P, 3.1 kg of K, 9.2 kg of

Ca, and 3.6 of Mg ha-1 yr-1 were removed in pinestraw

harvest. These amounts are within the ranges observed in

previous research (Morris and others 1992). Assuming that

volatile losses and leaching of N were low, the application

of 224-56-56 kg ha-1 NPK fertilizer more than adequately

compensated for the removal of these elements over the 5

years of raking involved in this study.

Economic Considerations

On healthy, well-stocked sites, the value of pinestraw sales

alone or in conjunction with the value of increased wood

volume can exceed the cost of fertilizer application, and

produce an attractive return on investment. To compare the

economic returns from management for pinestraw production with traditional timber management (mid-rotation

thinning and fertilization), one must consider a number of

Table 4—Pinestraw yields from raked plots before and 3 years

after fertilization

Treatment

Raked Raked and fertilized

Site Basal area Yield Basal area Yield

m2/ha kg/ha m2 /ha kg/ha

Rincon

1991 33.1 4380 31.3 3590

1994 36.1 5390 36.3 5730

Louisville old-field

1991 34.5 3930 33.1 4040

1994 36.8 4580 34.8 4150

Louisville cut-over

1991 29.0 4210 30.6 3700

1994 33.1 4150 36.8 4380

Albany

1991 22.8 3260 23.2 2920

1994 29.0 3030 24.4 2530

Wrightsville

1991 21.6 2250 21.9 3030

1994 31.1 2810 27.6 3990

factors including stand characteristics, management costs

and value of increased straw and wood volume.

On the Rincon site, for example, fertilization cost approximately $180 ha-1 at the time of treatment (1990). An additional cost of about $5 ha-1 was incurred for foliar sampling

and analysis. These loblolly pines, age 17 at treatment,

showed significant increases in both straw production and

volume growth following fertilization. Assuming 7.5 kg bales

of straw at $0.40 bale-1, pulpwood prices of $35 cord-1, and

a discount rate of 4 percent, the value of the additional

4500 kg per ha of straw harvested and estimated 11.7

cords of wood produced at the end of the 5 year period

(stand age 22-years) was $147.50 ha-1. If chip&saw prices

of $81 cord-1 were applied to the increased volume, the

value of the additional wood and straw would be $256 ha-1.

This is an uninflated (nominal) return on the investment of

42 percent.

Had this stand not been raked and fertilized for pinestraw

production, but instead, thinned at age 17 and then fertilized, a GAPPS analysis (Burgan and others 1989) predicted a yield at thinning of approximately 27.2 cords ha-1,

worth $1,478 ha-1 (table 5). The yield of the residual stand

5 years later, at harvest age 22, would be approximately

81 cords ha-1, valued at $6,079 ha-1. If the same stand had

not been raked or thinned, there would be 116 cords ha-1

at age 22, at a value of $8,265 ha-1. Depending upon the

landowner’s cash flow needs, pinestraw management

appears to be a viable economic option for a stand such as

this one.
96

At the Louisville old-field site, fertilization at age 15-years

did not produce statistically significantly different treatment

means. Although fertilized trees grew slightly larger than

non-fertilized trees, there was no increase in pinestraw yield

(tables 2 and 4). The lower return on fertilizer investment,

and the lack of increased needle production indicates that

fertility was good and foliage yield at or near its expected

maximum.

At the Louisville cut-over site, age 12 at treatment, the

observed fertilizer response of 3.4 additional cords ha-1 yr-1

(1.4 cords ac-1 yr-1) is not expected to continue through

rotation age 22-years. The value of additional wood and

straw produced during the first 5 years after fertilization

would still offset the initial investment cost of the fertilizer

and foliar testing. Under the current recommendation of

fertilization at mid-rotation (Morris and others 1992), this

site would not have been fertilized until four years later in

the rotation, shortening the length of time over which the

investment would be held, and increasing the return on the

investment.

The potential for timber volume losses due to increased

mortality from fusiform rust and pitch canker associated

with fertilization should be considered in financial analysis

of fertilizer investment. Stands with high fusiform infection

should be considered higher risk for fertilization in

conjunction with raking due to their propensity to lose

trees, which opens gaps in the canopy, permitting

understory invasion, and reduces straw production and

recovery. Fertilization and raking should be avoided in

slash pine stands with rust incidence greater than 25

percent. Although fertilization can increase straw yields

there is little additional volume growth benefit associated

with fertilization in unthinned pine plantations that are

candidates for pinestraw harvesting. Such sites appear to

be self-selecting for sites that already have high fertility,

high leaf areas and canopy closure which allows for little

understory. On these sites, raking can be safely conducted

without fertilization.

Managers are encouraged to monitor the progress and

health of stands after treatment. The flexibility to adjust

raking frequency, herbicide prescriptions, and other activities with changing stand conditions should be part of the

pinestraw management plan.

ACKNOWLEDGMENT

This research was initially funded by the Georgia Forestry

Commission, with continued support from the University of

Georgia Daniel B. Warnell School of Forest Resources. A

special thanks to Union Camp Corporation for providing

manpower, data and research sites, and to F & W Forestry

Services, and Drs. Cubbage and Newman for use of their

lands.

Table 5—Cash flows associated with traditional vs. pinestraw management at two contrasting sites (rotation

age 22)

Age

Management 12 13 14 15 16 17 18 19 20 21 22

- - - - - - - - - - - - - - - - - - - - - - - - net revenue ($/ha) - - - - - - - - - - - - - - - - - - - - - - - -

Rincon loblolly sitea

None 0 0 0 0 0 8265

Raked 137 166 197 240 279 8265

Fertilized -180 0 0 0 0 8676

Fertilized/raked -180 191 227 267 306 8676

Thinned 1478 0 0 0 0 6079

Thinned/fertilized 1297 0 0 0 0 6489

Louisville cut-over loblolly siteb

None 0 0 0 0 0 0 0 0 0 0 4585

Raked 165 171 170 167 174 165 171 171 171 171 4585

Fertilized -180 0 0 0 0 0 0 0 0 0 5180

Fertilized/raked -180 197 208 221 234 229 224 224 224 224 5180

Thinned 0 0 0 676 0 0 0 0 0 0 4047

Thinned/fertilized 0 0 0 496 0 0 0 0 0 0 4646

a Based on 3590, 4250, 5000, and 5730 kg/ha straw harvested during the years following fertilization (increases of 1015, 1235,

1125, and 1125 kg/ha); mean bale weight of 7.5 kg; price per bale of $0.40. Assumes a 5-year timber volume response to

fertilization at 11.7 cords/ha at $35.00 per cord.

b Based on 3700, 3900, 4140, 4380, 4300, and 4200 kg/ha straw harvested during the first 6 years following fertilization

(increases of 500, 700, 1000, 1120, 1200, and 1000), returning to an annual yield of 3500 kg/ha. Assumes a 5-year timber volume

response to fertilization of 17 cords/ha.
97

LITERATURE CITED

Allen, H.L. 1987. Forest fertilizers: nutrient amendments, stand

productivity, and environmental impact. J. For. 85(2): 37-46.

Bailey, R.L.; Grider, G.E.; Rheney, J.W.; Pienaar, L.V. 1985.

Volume, weight and diameter distribution and yield equations for

site-prepared loblolly pine plantations in the Piedmont and

upper Coastal Plain of Alabama, Georgia, and South Carolina.

Univ. Ga., Sch. of For. Resources Plantation Management

Research Coop. Tech. Rep. No. 1985-3, Sch. of Forest

Resources, Univ. Ga., Athens, Ga.

Belcher, D.M.; Clutter, J.L. 1977. Yield of slash pine plantations in

the Georgia and north Florida Coastal Plain. Univ. Ga., Sch. of

For. Resources Plantation Management Research Coop. Tech.

Rep. No. 1977-2, revised Feb. 15, 1979. Sch. of Forest

Resources, Univ. Ga., Athens, GA.

Blevins, D.P. 1994. Pinestraw raking and fertilization impacts on

the nutrition and productivity of longleaf pine. Thesis. North

Carolina State University, Sch. of For. Resources, Raleigh, NC.

Burgan, T.B.; Bailey, R.L.; Brooks, J.R. 1989. GAPPS (Georgia

Pine Plantation Simulator). Version 3.0. Sch. of Forest

Resources, Univ. Ga., Athens, GA.

Dalla-Tea, F.; Jokela, E.J. 1991. Needle fall canopy light interception and productivity of young intensively managed slash

and loblolly pine stands. For. Sci. 37: 1298-1313.

Dinus, R.J.; Schmidtling, R.C. 1971. Fusiform rust in loblolly and

slash pine after cultivation and fertilization. USDA For. Serv.

Res. Pap. 50-68. 10 p.

Duryea, M.L.; Edwards, J.C. 1989. Pine-straw management in

Florida’s forests. Fla. Coop. Ext. Serv. Circ. 831, Univ. Florida,

Gainesville.

Ebermayer, E. 1876. Die gesamte lehre der waldstreu mit

ruchsicht auf die chemische statik des waldbaues. J. Spring,

Berlin.

Fisher, R.F.; Garbett, W.S. 1980. Response of semimature slash

and loblolly pine plantations to fertilization with nitrogen and

phosphorus. Soil Sci. Soc. Amer. J. 44: 850-854.

Georgia Cooperative Extension Service. 1970. Lab procedures -

soil testing and plant analysis laboratory.

Gholz, H.L.; Perry, C.S.; Cropper, W.P.; Hendry, L.C. 1985. Litterfall

decomposition and nitrogen and phosphorus dynamics in a

chronosequence of slash pine (Pinus eliottii) plantations. For.

Sci. 31: 463-478.

Gresham, C.A. 1982. Litterfall patterns in mature loblolly and longleaf pine stands in coastal South Carolina. Forest Science. 28:

223-231.

Hennessey, T.C.; Dougherty, P.M.; Cregg, B.M.; Wittwer, R.F.

1992. Annual variation in needle fall of a loblolly pine stand in

relation to climate and stand density. For. Ecol. and Manage. 51:

329-338.

Isaac, R.A.; Johnson, W.C. 1976. Determination of total nitrogen in

plant tissue using a block digestor. Journal of the Association of

Official Analytical Chemists. 59: 98-100.

Jemison, G.M. 1943. Effects of litter removal on diameter growth

of shortleaf pine. Journal of Forestry. 41(3) 213-214.

McKee, W.H., Jr.; Mims, M. 1995. Effect of forest floor removal and

nitrogen fertilization. Center for Forested Wetlands Research,

SE For. Exp. Station, Charleston, SC. Submitted to Biennial

Silviculture Conference Proceedings.

McLeod, K.W.; Sherrod, C., Jr.; Porch, T.E. 1979. Response of

longleaf pine plantations to litter removal. For. Ecol. and Manage.

2(1): 1-12.

McNeil, R.C.; Ballard, R.; Duzan, H.W., Jr. 1984. Prediction of midterm from short-term fertilizer responses for southern pine

plantations. Forest Science 30(1): 264-269.

Mills, R.; Robertson, D.R. 1991. Production and marketing of

Louisiana pinestraw. Preliminary report. Louisiana Cooperative

Extension Service, Louisiana State University Agricultural

Center, Baton Rouge, LA. 11 pp.

Morris, L.A.; Jokela, E.J.; O’Connor, J.B., Jr. 1992. Silvicultural

guidelines for pinestraw management in the Southeastern

United States. Georgia For. Res. Paper No. 88, Jul 1992.

NCSFNC. 1991a. Descriptive statistics and relationships among

soil and foliar characteristics in mid-rotation loblolly pine plantations. NCSFNC Res. Note No. 7. North Carolina State Forest

Nutrition Cooperative. College of Forest Resources. North

Carolina State University. Raleigh, NC.

NCSFNC. 1991b. Leaf area variation in mid rotation loblolly pine

plantations. NCSFNC Research Note 6. North Carolina State

Forest Nutrition Cooperative. North Carolina State University,

Raleigh, NC. 25 p.

Perkin-Elmer. 1987. Analytical methods for atomic absorption

spectrophotometry.

SAS Institute, Inc. 1987. SAS/STAT guide for personal computers.

version 6 edition. SAS Institute, Inc. Cary, NC.

Switzer, G.L.; Nelson, L.E. 1972. Nutrient accumulation and

cycling in loblolly pine (Pinus taeda L.) plantation ecosystems:

the first twenty years. Soil Sci. Soc. Amer. Proc. 36:143-147.

Technicon Industrial Systems. 1972. Preliminary for Technicon

Auto Analyzer II.
98

INTRODUCTION

Grazing of slash pine (Pinus elliottii Engelm.) forests in the

Lower Coastal Plain dates back to around 1520, when cattle

were first brought to Florida by Ponce de Leon from Spain

(Lewis 1983). However, the history of modern day silvopasture in the Southeast began in the early 1950s, when pine

trees were first planted in improved pastures as part of the

Conservation Reserve Soil Bank Program. In this paper,

silvopasture is defined as intentional combination of trees,

forage plants and livestock in an integrated, and intensively

managed system (fig. 1). Once known as tree-pasture, or

pine-pasture, this agroforestry practice continues to attract

non-industrial private forest landowners as well as livestock

operators who want to diversify their enterprise (Kalmbacher

2000, Nowak and Blount 2002). Production of high quality

timber is usually the ultimate goal in silvopastures located

in temperate climates (Sharrow 1999).

Pine-based silvopasture has potential to be more profitable

than traditional plantation forestry under most economic

circumstances and management regimes studied to date

(Dangerfield and Harwell 1990, Clason 1995, Grado and

others 2001, Husak and Grado 2002). The key to improved

cash flow of combined enterprise is the annual income

derived from livestock, forage and hunting leases, which

supplements long-term, periodic income from timber sales.

The multi-product nature of silvopastoral systems provides

safeguards against unfavorable single-commodity markets,

weather conditions, or agricultural policy decisions (Sharrow

1999). Silvopasture can be practiced on small tracts or

large landholdings. It could be a stand-alone operation, or

part of a mosaic of land-uses that include improved

pastures and diverse timberlands. There is also a potential

for partnerships between forestland and livestock owners.

The forest owners could gain annual income; the livestock

owners would have access to an additional grazing

resource.

Silvopasture is different than forest range, or woodlot

grazing in that it employs improved forages. Forest range

management relies on native forages. Open forest range

grazing and management were thoroughly investigated

into the mid-1980s (for example, Pearson and others 1971,

Pearson and Whitaker 1974, Clary 1979, Byrd and others

1984, Lundgren and others 1984, Grelen and others 1985).

Prescribed grazing of young slash pine and other coniferous

SLASH PINE IN INTEGRATED TIMBER, FORAGE, AND

LIVESTOCK SILVOPASTORAL SYSTEMS

Jarek Nowak and Alan Long1

1 J. Nowak, Assistant Professor of Forestry, University of Florida, North Florida Research and Education Center, Quincy, FL 32351-5677;

and A.J. Long, Associate Professor of Forestry, University of Florida, School of Forest Resources and Conservation, Gainesville, FL

32611-0410.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.

Abstract—Establishment of slash pine-based silvopastoral systems either by (1) planting trees on agricultural lands, or

(2) thinning of mid-rotation age pine plantations has been reviewed. The high suitability of typical slash pine variety in

silvopastoral systems is contrasted to that of south Florida slash pine and other commonly planted southern pine species.

Lack of apparent long-term impact of cattle grazing on slash pine growth and quality is discussed. Past research has

shown that silvopastures established in 12x12 ft spacing produced twice as much wood and 33 percent less total beef

cattle liveweight gains than those planted in 20x20 ft spacing (Lewis and others 1983). Wood volume was higher in

bahiagrass silvopastures than when dallisgrass was grown under slash pine canopies. Total beef cattle liveweight gains

were higher in bahia- and dallisgrass than in bermudagrass silvopastures. Silvopastures planted at 12x12 ft produced

39 percent and those planted at 20x20 ft, 59 percent of total beef cattle liveweight gains attained on open pastures. The

4x8x40 ft tree spacing has been shown to facilitate simultaneous timber and forage production from the same acreage

(Lewis and others 1985). This spacing continues to be popular in Florida for silvopasture planting. To date no other viable

tree spacing configurations or forage species/varieties have been experimentally tested in silvopastures established in

the southeastern U.S. Conversion of mid-rotation age slash pine plantations to silvopastures is deemed possible based

on documented similar conversions in loblolly pine plantations. However, this also requires experimental testing.

Figure 1—Seventeen-year-old slash pine, bahiagrass,

crimson clover, and cattle silvopasture near Chipley, Florida.

Trees were planted in double-row 4x8 ft spacing with 40 ft

pasture alleys between the double rows. Bahiagrass

dominates alleys during summer and crimson clover

during winter months. Credits: Todd Groh, August 2001.
99

plantations has also been used for understory vegetation

control in the stand establishment phase (Pearson and

others 1971, Doescher and others 1987, Karl and Doescher

1993). While grazing of public and industrial forestlands is

generally a practice of the past, farmers and other private

landowners continue to use their forests and small woodlots for livestock. Silvopasture offers an opportunity for a

more intensive management of integrated timber, forage

and livestock resources than the systems employed in the

previous decades and centuries.

The objective of this paper is to familiarize practicing foresters, non-industrial private forest landowners, livestock

operators, and other natural resource managers, with

slash pine-based silvopasture establishment and basic

management considerations, based on the available

literature on this subject.

SUITABILITY OF SLASH PINE VARIETIES FOR

SILVOPASTURE

Among the southern pine species commercially grown in

the South, the typical slash pine variety (Pinus elliottii

Engelm. var. elliottii) possesses traits that make it uniquely

suitable for silvopastures. When mature, slash pine has a

straight, long and clear bole. These traits make it an

excellent species for high value timber production. This

variety is known for fast height growth in early years. This

contributes to successful stand establishment even in the

presence of onsite competition from grasses or other vegetation. Branches are relatively few, thin, and they self-prune

easily, which results in short and narrow crowns. The

branching habits and crown characteristics contribute to

high timber value, but also facilitate forage production

underneath the tree canopy. On the other hand, the south

Florida slash pine variety (Pinus elliottii var. densa Little

and Dorman) has many undesirable traits for use in silvopastures. Seedlings of this variety undergo a dwarf stage

similar to the “grass stage” of longleaf pine (Pinus palustris

Mill.). When the height growth resumes, south Florida

slash pine often forms forks or lacks the straightness of the

typical slash pine variety. In later years, south Florida slash

pine stems tend to divide into large spreading branches,

which produce flat-topped or rounded crowns (Barnett and

Sheffield 2004). Such crowns are likely to impede forage

production underneath the tree canopy.

Other commonly planted southern pines can be used in

silvopastures; however, they do not display traits as desirable as the typical slash pine variety. Loblolly pine (Pinus

taeda L.) produces more volume than other southern pines.

This species tends to have more and thicker branches than

slash pine, which makes it less suitable for silvopastures.

Longleaf pine has good crown characteristics and can

produce high value timber; however, it is also the hardest

species to establish, especially in grass. Discussion in the

reminder of this article is concerned with typical slash pine

variety, unless stated otherwise.

ESTABLISHMENT OF SILVOPASTURE

Silvopasture establishment requires a number of different

management steps depending on previous land use.

Planting trees in an existing improved pasture is the easiest way to start the system. Slash pine-based silvopastures

have also been established on forest cutover sites by

planting trees first, and establishing improved forages in

the fourth growing season (Lewis and others 1983). Establishment of silvopastures on old agricultural fields is also

possible. Old-fields do not need as intensive site preparation as cutover sites, but may require vigorous herbaceous

weed control. On both, cutover sites and old-fields, improved

grasses should be established in the spring following tree

planting, or as soon after tree planting as practical. Another

possible scenario is to thin existing timber stands and plant

or seed forage species among the remaining trees. Although

this approach to silvopasture establishment has been documented in mid-rotation loblolly pine stands in Louisiana

(Clason 1995, 1999), similar conversions of slash pine

stands were not attempted or documented in the available

literature. Most of this review concentrates on pasture to

silvopasture conversion, as this is the most straightforward, and cost effective process in which many of the

same general plantation forestry concepts apply.

Converting Pastures to Silvopastures

Silvopastures are the easiest to establish by planting trees

in existing pastures. This eliminates costs of forage planting, shrub and brush control, and removal of timber harvest

residues. Well-established and managed bahiagrass,

bermudagrass or other similar pastures are most suitable.

Tree planting density varies from 100 to 450 stems per acre

depending on product objectives, and anticipated level of

management intensity (Lewis and others 1983, 1985). If

fewer trees are planted, thinning of pulpwood size trees

may not be necessary. However, trees grown at wider

spacings require pruning for quality timber production

(Lewis and others 1983). Standard tree planting methods

and equipment can be used, as described below.

Site preparation—Site preparation before tree planting

improves seedling survival and early growth by reducing

competition from grasses and other vegetation for water,

nutrients and light. Proper site preparation can be achieved

by chemical, mechanical or prescribed fire treatments

applied alone or in combination. The method of choice

depends on site conditions, vegetation to be controlled,

treatment costs, and other considerations such as herbicide

acceptability or objections to smoke from prescribed fires.

Chemical site preparation consists of herbicide applications before trees are planted. Herbicides are most often

sprayed in bands along planting rows or around planting

spots. Pre-planting treatments allow for higher application

rates, and therefore greater possibility of success in controlling unwanted vegetation. Chemical site preparation offers

the longest lasting competition control where it is needed

most, within rows of planted trees. Reduction of competition is essential to rapid seedling establishment. Broadcast

herbicide application is usually not necessary, unless the

current pasture is to be replaced with more suitable forage

species. Under most circumstances, banded application, or

even spot application, should be sufficient to control vegetation competing with trees at a lower cost than broadcast

application. Some common herbicide treatments include:

Arsenal®, or Velpar® with Oust® in the spring, or tank mixes of

Accord® with Arsenal® in the fall. In bermudagrass pastures,

Arsenal® or Accord® must be used. One should read the
100

herbicide label prior to application for recommended rates,

mixing instructions, and species recommendations.

Scalping is a very effective mechanical site preparation technique on pastures. By exposing the mineral soil, scalping

prepares a furrow for tree planting machines and generally

reduces weed competition during the next growing season.

Sod and grass are stripped along intended tree rows by a

tractor-pulled scalping plow. Some sites may also require

subsoiling before planting to break existing “plow pans” or

other “hard pans”. This is accomplished by a metal shank

pulled behind a tractor at soil depths up to 24 inches. As a

result, increased tree root penetration leads to better tree

survival and establishment after planting. Scalping and

subsoiling, or scalping and tree planting are sometimes

combined into one operation with the right implements

attached to a tractor. Disked strips can also be used to

break up sod and prepare planting rows. As with scalping,

untreated areas are left between planting rows to protect

soil and provide forage. On slopes, disking and scalping

should always follow contours to limit the possibility of soil

erosion.

Prescribed fire recycles nutrients and temporarily reduces

competition from herbaceous and other vegetation. It has

an added benefit of increasing forage palatability. It should

be applied shortly before tree planting. Fire alone has been

shown to be sufficient site preparation for good slash pine

survival and growth (Lewis 1985). Prescribed fire is usually

the cheapest site preparation option (Dubois and others

1999), but most pasture grasses resprout quickly after it is

applied.

Combination of methods, such as broadcast herbicide application followed by prescribed fire, or banded herbicide

application along scalped rows, may be necessary if

shrubs, undesirable perennials and/or vines need to be

controlled. Prescribed fire (with or without prior herbicide

application) may be followed by mechanical site preparation.

Seedling types—Genetically improved tree seedlings are

preferred for establishment of silvopastures. Planting stock

recommended for typical slash pine plantations (White and

Byram 2004) is also best for silvopasture establishment.

It is especially important to use fusiform rust resistant

seedlings whenever slash pine is planted. Large caliper

seedlings have much more desirable shoot and root characteristics than seedlings produced at high sowing densities, such as once common 28 seedlings per ft2

 of nursery

bed (Rowan 1986). Well-developed, fibrous root systems

allow rapid seedling establishment, increasing survival

and growth in the field. Bareroot slash pine seedlings 0.4

inch in diameter at the root collar (the juncture between

seedling tap root and the shoot) have been found to survive

and grow better than typically produced 0.2 inch caliper

seedlings (South and Mitchell 1999). Planting of large

caliper seedlings has been more likely to result in better

early survival and growth compared to application of either

double bedding or Arsenal herbicide to control competition

on flatwoods sites in Georgia. Bareroot seedlings are

cheaper than those produced in containers, but they need

to be planted during winter. Containerized seedlings work

well, and they can be planted either during winter or after

the start of the summer rainy season.

Tree spacing at planting—Silvopasture requires tree spacing that allows for sufficient timber and forage yields. A 4x8

ft tree spacing with 40 ft forage alleys between pairs of tree

rows has been found to best satisfy these requirements in

previous Georgia and Florida experiments (Lewis and

others 1985). The double-row 4x8x40 ft tree spacing (fig. 2)

produced both high wood volumes and forage yields (table

1). This tree-planting configuration continues to be popular

for establishment of silvopastures in Florida (Kalmbacher

2000).

Other tree arrangements in silvopastures are also possible.

Trees have been planted in single wide-spaced rows such

as 12x12 or 20x20 ft in Georgia experiments (Lewis and

others 1983). In the northwestern U.S., tree planting in

multiple rows with wide alleys between the sets, or in clusters have been suggested by Sharrow (1999). In any tree

arrangement, open areas between trees allow for forage

production. Planting trees in rows facilitates access for

future forage and silvicultural operations, and therefore is

preferred over random tree placement or planting tree

clusters. Generally, wider spacing between single rows, or

wider alleys between sets of multiple rows support higher

levels of forage production. However, too much open pasture space also means less wood production on a per acre

basis. The trade-offs between timber and forage production

are well illustrated by comparing yields of both commodities in double-row 4x8x40 and 2x8x88 ft spacings. The

4x8x40 ft tree pattern produced twice as much wood as the

2x8x88 tree spacing, whereas the opposite was true for

forage production (table 1).

Tree spacing at planting for silvopasture establishment

requires further experimental testing. Besides single- and

double-row configurations used by Lewis and others

(1983, 1985), no other silvopastoral tree spacings have

been documented in the Southeastern U.S. to date.

Tree planting—Trees are best planted with a mechanical

planter, but hand planting is also possible, especially on

smaller or irregular tracts of land. Machine planting

produces straight rows and uniform spacings, which is

Figure 2—Double-row 4x8 ft tree spacing with 40 ft wide alleys

between pairs of tree rows was found to satisfy both timber and

forage growth requirements as documented by Lewis and others

(1985).

4 x 8 x 40 feet tree spacing

Tree placement

40 ft

4 ft

8 ft
101

important in silvopastoral systems. General guidelines for

planting trees in silvopastures are the same as for establishing tree plantations. Plant trees on the contour wherever pastures are on slopes to limit the possibility of soil

erosion. Staying in scalps and furrows while planting trees

should not pose any difficulties. However, more effort may

be needed to plant trees within herbicided bands if the

treated vegetation has not yet discolored. At planting, care

needs to be exercised not to bend roots upwards, which

causes “j-rooting”, and may lead to low seedling survival.

Soil should be firmly packed around roots of each seedling

to avoid air pockets, and the seedlings should be planted

deep enough to cover root collars. If planting bareroot

stock, keep seedlings and roots moist and in the shade

from the time they are lifted from nursery beds until planted

in the field (Duryea and Edwards 1987).

Tree survival and establishment—Post-planting treatments are often necessary for best tree survival and establishment results. Grasses and weeds often quickly reoccupy

scalped or disked rows and they need to be controlled

with herbicides during the first and/or second year after

planting. Banded or spot herbicide applications along tree

rows (up to 4 feet across) are most effective in controlling

unwanted vegetation. The following herbicides can be used:

(1) Oust®, Arsenal® or Accord® on bahiagrass; (2) Arsenal®,

Accord®, or Fusilade® 2000 on bermudagrass; (3) Arsenal®,

Oust®, or Oustar®, as single herbicide treatments; or (4) tank

mixes of Oust® with Velpar®, Arsenal®, or Accord® for other

grasses and herbaceous vegetation. Consult labels prior to

herbicide applications for appropriate rates, mixing instructions and plant species that can be controlled with each

herbicide. It is best to protect tree seedlings from direct

contact with the herbicides, although some are labeled for

“over the top applications”. Stressed seedlings are more

prone to herbicide-caused damage than healthy and vigorous ones. Tank mixes may be more damaging than any of

the herbicides applied alone. For example, applying

Velpar® or Arsenal® with Oust® may increase damage to

young slash pine seedlings.

Mowing between the rows of trees is advised several times

a year during the first three growing seasons after tree

planting. Mowing helps to further reduce the competition

from grasses and increase light available to tree seedlings.

If the grass yield is sufficient, mowing can be part of haying

operations to provide revenue or forage during the years

before livestock are allowed to graze on the site. Avoid

hitting the seedlings or scuffing off the bark when mowing,

hay cutting or during any other operation that requires

driving equipment between the rows of trees.

Preventing livestock injury to young trees—Livestock is

best introduced into the system when the trees reach sufficient heights to prevent damage to terminal buds from

browsing. Seedling mortality is most likely when the

terminal bud and needles are both browsed off (Pearson

and others 1990). In one study, up to 34.5 percent of planted

slash pine seedlings showed moderate to severe damage,

and 4 percent were dead in the first growing season after

planting under yearlong grazing regime (Pearson and

others 1971). The remaining 61.5 percent of seedlings

showed none-to-light damage. In all, this study showed

that slash pine height growth was negatively impacted by

grazing for the first five years. However, differences in wood

volume between grazed and ungrazed treatments were

not significant in the same plantations at 18 years (Grelen

and others 1985). This was attributed to larger diameters of

the fewer remaining trees in the heavily grazed plots. None

of the parameters measured at 30 years: tree height, diameter at breast height, diameter growth rate, tree grade,

amount of latewood, wood specific gravity or fiber length

were statistically different between grazed and ungrazed

plots (Cutter and others 1999). The reader is cautioned that

these slash pine plantations were established at 908 trees

per acre, twice the number of trees in 4x8x40 ft spacing.

Therefore, they could absorb more initial cattle-caused

damage than silvopastures planted at lower initial tree

densities, and still produced wood volumes and quality

comparable to ungrazed plantations. Nevertheless, slash

pine is quite resilient and is able to recover from physical

damage. Hughes (1976) and Lewis (1980a, 1980b, 1980c)

Table 1—Average tree and forage responses of slash pine at age 13 yearsa

Tree spacing (feet)

8 x 12 4 x 24 2 x 48 6 x 8 x 24 4 x 8 x 40 2 x 8 x 88

Tree survival (percent) 61 68 68 67 67 74

Tree height (feet) 35 35 36 32 36 34

Tree diameter (inches) 5.7 5.2 5.1 5.0 5.5 4.3

Stand basal area (square

feet per acre) 50 49 52 40 59 33

Wood volume (cubic feet

per acre) 903 866 973 658 1086 580

Total forage yieldb (pounds

per acre per year) 1,138 542 1,069 1,347 1,264 2,573

a Trees were planted in single (8 x 12, 4 x 24, or 2 x 48 feet) and double-row (6 x 8 x 24, 4 x 8 x 40, or 2 x 8

x 88 feet) configurations at 454 trees per acre (modified table adopted from Tanner and Lewis 1984).

b Native forage yields are reported, yields would most likely be higher if improved fertilized forages were

employed.
102

studied simulated cattle injury to planted slash pine, and

generally found that trees survived and recovered from all

but the most severe types of artificially inflicted injuries.

Young pine plantations suffer little damage if cattle stocking

rates are in balance with forage available for grazing (Lewis

1984). However, injuries repeated over an extended period

of time can potentially reduce wood volume production,

especially when fewer trees are planted per acre. Therefore, the lower the number of trees, the greater care needs

to be exercised to protect young trees from cattle inflicted

damage or mortality. It follows, that grazing could be initiated earlier where cattle-caused damage to timber can be

offset by greater number of trees per acre.

Establishment of Silvopasture on Forest Cutover

Sites

Silvopasture establishment on forest cutover sites requires

a considerable amount of site preparation work followed

by tree and forage planting. Lewis and others (1983) prepared a cutover site intended for silvopasture in the following manner. First, trees and stumps were removed with a

bulldozer. Other woody material worked to the surface by

repeated disk harrowing and raking with farm implements

was also removed from the site. Liming and N-P-K fertilizer

requirements were determined by soil testing. Appropriate

amounts of lime and mineral fertilizer were incorporated

into the soil during the final disking and leveling. Slash pine

seedlings were planted in one of two spacings: 12x12 or

20x20 ft. In the fourth growing season, coastal bermudagrass (Cynodon dactylon (L.) Pers.), dallisgrass (Paspalum

dilatatum Poiret) or Pensacola bahiagrass (Paspalum notatum Flügge) were established between rows of trees and

in a tree-less area. The silvopastures and open pastures

were fertilized (100-22-42 lbs per acre of elemental N-P-K,

respectively), grazed by yearling heifers, and burned

annually every March for 15 years. Some of the results of

this study are summarized in table 2. In short, silvopastures

planted in 12x12 ft spacing produced twice as much wood,

but 33 percent less cattle beef liveweight gains compared

to those planted in 20x20 ft spacing. Cattle grazed on

bahiagrass and dallisgrass under slash pine canopies,

gained more liveweight than when grazed on bermudagrass. More wood was produced when bahiagrass was

grown under tree canopies compared to dallisgrass. Wood

volume in bermudagrass silvopastures was not significantly different from the bahiagrass or dallisgrass silvopastures (table 1). Total beef cattle liveweight gains on

open pasture were 1.7 and 2.6 times more than those in

silvopastures with 100 and 300 trees per acre, respectively

(table 1). Forage available for grazing was declining with

the passage of time in all treatments. However, only in

silvopastures planted at 12x12 ft, and thinned to spacing of

18x18 ft at age10, there was not enough forage to support

cattle in the 19th year since trees were planted (table 2).

The acceptable trade-offs between wood, forage and livestock production need to be decided on a case by case

basis by landowners, who will be financially affected by

these decisions.

Establishment of Silvopasture on Old-Fields

Specific examples of slash pine silvopasture establishment

on old-field sites were not found in the subject literature.

However, one can assume that similar procedures to those

described above for the forest cutover sites could be

followed for tree and forage establishment on old-fields.

Scalping before tree planting and other site preparation

techniques recommended for pastures would be suitable

for old-fields as well. Barnard and others (1995) found

scalping to be especially effective site preparation technique on old-fields. In their study, slash pine seedlings in

scalped rows almost always survived and grew better than

seedlings in nine other treatments. Those results were

based on five different slash pine plantations established

in two different years across western half of Florida’s panhandle. Barnard and others (1995) attributed the improved

seedling performance in scalped rows to the combined

effects of reduced weed competition, improved moisture

regimes, reduced pressure from root pathogens, reduced

insect-caused seedling damage, and improved tree

planting quality facilitated by exposed mineral soil. Recent

cropping history that includes leguminous and other row

crops such as soybeans, peanuts, and cotton, often creates

Table 2—Tree survival, wood yield, beef cattle stocking, and liveweight gains in slash pine-based

silvopastures at two tree spacings (20x20 or 12x12 ft) with bermudagrass, dallisgrass or bahiagrass

under tree canopiesa

Tree spacing (feet) Forage grasses

Noneb 20 x 20 12 x 12 Bermuda Dallis Bahia

Tree survival at age 10-years (percent) — 61 66 65 71 55

Wood yield at age 20-years (cubic feet per acre) — 1,296 2,593 1,979 1,728 2,124

Cattle stocking 7th yearc (animals per acre) 1.9 1.6 1.4 1.6 1.6 1.7

Cattle stocking 19th yeard (animals per acre) 1.3 0.2 0.0 0.2 0.5 0.8

Total liveweight gainse (pounds per acre) 3,506 2,053 1,353 1,905 2,348 2,656

a The silvopasture results are contrasted to cattle stocking and liveweight gains on open pastures. (Based on results of

Lewis and others 1983).

b None refers to open pasture condition, averages for the three improved grasses are reported.

c Cattle stocking in the 7th year of the study reached maximum number of animals per acre in all treatments (based on

forage availability).

d Cattle stocking in different treatments based on forage availability at the end of the study.

e Sum of cattle liveweight gains starting in year 5 through year 19 in each treatment are reported.
103

conditions favorable to buildup of certain soilborne agricultural pests linked to slash pine seedlings mortality. Among

those pests, whitefringed beetles (Graphognathus spp.) and

the charcoal root rot fungus (Macrophomina phaseolina

[Tassi] Goid.) seem to be successfully neutralized by

scalping before tree planting (Barnard and others 1995).

Similarly to other silvopastures, trees may be planted in

the 4x8x40 ft or other suitable configurations as described

in the section on pasture to silvopasture conversion.

Improved forages could be established in the spring

following tree planting, or as soon as practical thereafter.

Soil cultivation will generally be needed before grasses

can be seeded or sprigged between the rows of trees. Pine

plantations established on freshly converted croplands

often look “clean” of herbaceous weeds. This should not be

misleading, as the weeds will develop and interfere with

survival and growth of newly planted pines in the vegetative season following planting. Appropriate herbaceous

weed control measures as described above for converted

pastures will be needed on old-fields as well.

Conversion of Pine Plantation to Silvopasture

First thinning of a pine plantation offers an excellent opportunity for conversion of timber only operations into a silvopasture. This conversion into a silvopasture is a multi-step

process composed of tree harvest, understory suppression,

debris removal, seedbed preparation and forage planting.

The overall objective is to open up the stand and create

conditions for forage production underneath the tree canopy.

There are no documented examples of mid-rotation slash

pine plantation conversion into a silvopasture through thinning and forage establishment in the available literature.

However, such conversions were successfully attempted

in loblolly pine plantations (Clason 1995, 1999). Twentyyear-old overstocked loblolly pine stands in northwest

Louisiana were thinned in two steps, first to 250 and five

years later to 125 trees per acre (Clason 1999). Appropriate tree density through thinning is the first step in

creating conditions for improved forage planting or seeding.

Understory vegetation suppression is achieved by herbicide applications, as needed. Seedbed is prepared by

prescribed fire and/or mechanical debris removal and

disking. Warm season forages are sown in the spring,

followed by N, P, K fertilization, and top dressing with N in

early summer. Local fertilization rates will vary depending

on soil testing results, species planted and other considerations. Costs of forage establishment will also depend on

forage species and other local factors. If a legume is

desired, it could be seeded in the fall, after the warmseason forage is grazed or harvested, to facilitate seed

contact with the soil. In cases where trees were planted in

improved pastures, understory vegetation removal or

suppression after thinning may promote the return of the

forage to grazing condition.

Introduction of Livestock and Silvopasture

Management

The introduction of livestock into a tree and forage system

needs to be carefully planned with respect to timing, appropriate animal species or variety, stocking rates, and grazing

management scheme. To a large extent these decisions

depend on the kind and quality of forage available for

grazing. Water availability in each pasture and appropriate

fencing are also important before livestock is integrated

into the system. There are many other livestock management considerations dependent on the animal species that

are beyond the scope of this publication. Beef cattle management in pine-pasture systems is described by a number

of authors (Byrd and others 1984, Lundgren and others

1984, Tyree and Kunkle 1995). Lundgren and others (1984)

pointed out that among five forest-grazing management

systems studied, multi-pasture rotational grazing was more

economical than yearlong, continuous grazing. After livestock are integrated into the silvopasture, continued intensive management of all three components: livestock,

forage(s) and trees is needed. Trees do not need to be

fertilized separately if the forage is routinely fertilized.

Additional nutrients are supplied from animal wastes by

livestock utilizing the site. Weed suppression may be

needed if not enough grazing pressure exists to eliminate

unwanted vegetation. In wider spacings, trees need to be

pruned for quality timber production. Timing and number of

thinnings depends mostly on the tree species planted,

initial spacing and product objectives. To avoid overgrazing,

silvopastures must not be overstocked or grazed too close

to the ground. Damage to forage, trees, soils, and water

resources might result if proper animal husbandry practices are not followed. On the other hand, if designed and

managed wisely silvopasture can provide many of the

economic and environmental benefits of the integrated

system (Nowak and Blount 2002).

CONCLUSIONS

Silvopastures are intentional, integrated and intensively

managed systems designed to optimize timber, forage and

livestock production from the same acreage at the same

time. Silvopastoral systems offer the possibility of forestlandderived annual revenue and diversification of farm income.

A silvopasture can be most easily established by planting

trees in an existing improved pasture. Planting trees on

well prepared forest cutover sites, or old-fields and establishing forages in subsequent years is also possible.

Conversion of mid-rotation loblolly pine plantations to

silvopastoral systems has been shown to be successful in

northwest Louisiana. Similar conversions are deemed

possible in mid-rotation slash pine plantations, but that

requires further experimental testing. Open forest range

grazing was thoroughly investigated in the past; however,

more research is needed to test optimal tree configurations,

forage and livestock selections, as well as overall management of integrated silvopastoral systems employing

improved forages. No matter what approach is taken,

continuous intensive management of tree, forage and livestock components is needed if the potential economic and

environmental benefits of a silvopasture are to be realized.

ACKNOWLEDGMENTS

The reviews and improvements suggested to the original

manuscript by Drs. Bob Myer, Michael Bannister, and Ann

Blount are greatly appreciated.

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Lewis, C.E.; Burton, G.W.; Monson, W.G.; McCormick, W.C. 1983.

Integration of pines, pastures, and cattle in south Georgia,

USA. Agroforestry Systems. 1: 277-297.

Lewis, C.E.; Tanner, G.W.; Terry, W.S. 1985. Double vs. single-row

pine plantations for wood and forage production. Southern

Journal of Applied Forestry. 9(1): 55-61.

Lundgren, G.K.; Conner, J.R.; Pearson, H.A. 1984. An economic

analysis of five forest-grazing management systems in the

southeastern United States. MP-1551. College Station, TX The

Texas Agricultural Experiment Station, The Texas A&M

University System. 8 p.

Nowak, J.; Blount, A. 2002. Silvopasture-more than cattle grazing

in pine plantations. Forest Landowner. 61(2): 10-14.

Pearson, H.A.; Baldwin, V.C.; Barnett, J.P. 1990. Cattle grazing and

pine survival and growth in subterranean clover pasture.

Agroforestry Systems 10: 161-168.

Pearson, H.A.; Whitaker, L.B. 1974. Yearlong grazing of slash pine

ranges: effects on herbage and browse. Journal of Range

Management. 27(3): 195-197.

Pearson, H.A.; Whitaker, L.B.; Duvall, V.L. 1971. Slash pine

regeneration under regulated grazing. Journal of Forestry. 69:

744-746.

Rowan, S.J. 1986. Seedbed density affects performance of slash

and loblolly pine in Georgia. International symposium on

nursery management practices for the southern pines:

proceedings; 1985 August 4-9; Montgomery, AL: Auburn

University: 126-135.

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between trees, livestock and improved grass-clover pastures

on temperate rainfed lands. In: Buck, L.E.; Lassoie, J.P.;

Fernandes, E.C.M., eds. Agroforestry in Sustainable

Agricultural Systems. Boca Raton, FL: CRC Press LLC. 416 p.

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pine seedling size for use with four levels of vegetation management on a flatwoods site in Georgia, U.S.A. Canadian

Journal of Forest Research. 29: 1039-1046.

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wood and forage production in Florida. Florida Cooperative

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Extension Service, IFAS, University of Florida. Circular 1154.

10 p.

White, T.L.; Byram, T.D. 2004. Slash pine tree improvement. In:

Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds.

Slash pine: still growing and growing! Proceedings of the slash

pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southern Research

Station: 7-19.
105

INTRODUCTION

Slash pine (Pinus elliottii var. elliottii) is a major forest

product species. The research literature is voluminous and

diverse. This publication was compiled to assist slash pine

managers and forest landowner consultants to better

appreciate and access important information in the

literature. This is not a comprehensive review but a

selection from among papers in the last 22 years (1981

through 2002 inclusive). These citations were checked and

proofed to assure minimal errors, but undoubtedly some

errors remain. Also note that inclusion or exclusion of a

paper is not a judgement upon value, but a selection by the

authors for the most germane papers on slash pine culture

and an avenue into the literature.

BIBLIOGRAPHY

Abbott, J.E. 1982. Operational planting of container grown

slash pine seedlings on problem sites. Gen. Tech. Rep.

SO-GTR-37. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station.

115-116.

Abrahamson, W.G. 1991. South Florida slash pine mortality

in seasonal ponds. Florida Scientist. 54(2): 80-83.

Adams, D.E.; Lenhart, J.D.; Vaughn, A.B.; Lapongan, J.

1996. Predicting survival of east Texas loblolly and slash

pine plantations infected with fusiform rust. Southern

Journal of Applied Forestry. 20(1): 30-35.

Airhart, D.L.; Natarella, N.J.; Pokorny, F.A. 1981. Electron

microprobe analysis of calcium solution penetration into

milled pine bark particles. Communications in Soil Science

and Plant Analysis. 12(4): 319-329.

Alig, R.J.; Kurtz, W.B.; Mills, T.J. 1981. Financial return

estimates of alternative management strategies for 9- to 15-

year-old southern pine plantations in Mississippi. Southern

Journal of Applied Forestry. 5(1): 3-7.

Allan, R. 1998. A report on pit size treatments and how

these impact on tree growth and survival. ICRF Bulletin

Series. 4: 18p.

Allen, P.J. 1985. Estimation of genetic parameters for wood

properties in slash pine in south east Queensland. Research

Note, Department of Forestry, Queensland. 41: 15p.

Allen, P.J. 1993. Stem profile and form factor comparisons

for Pinus elliottii, P. caribaea and their F1 hybrid. Australian

Forestry. 56(2): 140-144.

Anderson, R.L. 1986. New method for assessing contamination of slash and loblolly pine seeds by Fusarium moniliforme var subglutinans. Plant Disease. 70(5): 452-453.

Anderson, R.L.; Belcher, E.; Miller, T. 1984. Occurrence of

seed fungi inside slash pine seeds produced in seed orchards in the United States. Seed Science and Technology.

12(3): 797-799.

Anderson, R.L.; Cost, N.D.; McClure, J.P.; Ryan, G. 1986.

Predicting severity of fusiform rust in young loblolly and

slash pine stands in Florida, Georgia and the Carolinas.

Southern Journal of Applied Forestry. 10(1): 38-41.

Anderson, R.L.; Knighten, J.L.; Powers, H.R., Jr. 1984. Field

survival of loblolly and slash pine seedlings grown in trays

and leach containers. Tree Planters’ Notes. 35(2): 3-4.

Anderson, R.L.; McCartney, T.C.; Cost, N.D. [and others].

1988. Fusiform-rust-hazard maps for loblolly and slash pines.

Res. Note. SE-RN-351. Ashville, NC: U.S. Department of

Agriculture, Forest Service, Southeastern Forest Experiment

Station. 7p.

Anderson, R.L.; McClure, J.P.; Cost, N.; Uhler, R.J. 1986.

Estimating fusiform rust losses in five Southeast States.

Southern Journal of Applied Forestry. 10(4): 237-240.

Anderson, R.L.; Mistretta, P.A. 1982. Integrated pest management handbook. Management strategies for reducing

losses caused by fusiform rust, annosus root rot and littleleaf disease. Agriculture Handbook 597. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastern

Area State and Private Forestry. 30p.

Aoki, H.; Cruz, S.F. 1998. New methods for resin tapping in

Pinus. Revista do Instituto Florestal. 10(2): 123-126.

Arabatzis, A.A.; Gregoire, T.G.; Lenhart, J.D. 1991. Fusiform

rust incidence in loblolly and slash pine plantations in east

Texas. Southern Journal of Applied Forestry. 15(2): 79-84.

Arvanitis, L.G.; Godbee, J.F., Jr.; Porta, I. 1984. Pitch canker

impact on volume growth: a case study in slash pine plantations. Southern Journal of Applied Forestry. 8(1): 43-47.

SLASH PINE PINUS ELLIOTTII VAR. ELLIOTTII

SELECT BIBLIOGRAPHY

Bryan C. McElvany, Kim D. Coder, and E. David Dickens1

1 Bryan C. McElvany, Research Coordinator; Kim D. Coder, Forest Ecology Professor; and E. David Dickens, Forest Productivity Associate

Professor, Daniel B. Warnell School of Forest Resources, The University of Georgia, Athens, GA 30602-2152.

Citation for proceedings: Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J., eds. 2004. Slash pine: still growing and growing!

Proceedings of the slash pine symposium. Gen. Tech. Rep. SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 148 p.
106

Atkinson, P.R.; Laing, M.D. 1996. First results of investigations into fungal diseases of pines at establishment. ICFR

Bulletin Series. 6: 13.

Atkinson, T.H.; Foltz, J.L.; Connor, M.D. 1988. Bionomics of

Pissodes nemorensis Germar (Coleoptera: Curculionidae)

in northern Florida. Annals of the Entomological Society of

America. 81(2): 255-261.

Atkinson, T.H.; Foltz, J.L.; Connor, M.D. 1988. Flight patterns

of phloem- and wood-boring Coleoptera (Scolytidae,

Platypodidae, Curculionidae, Buprestidae, Cerambycidae)

in a north Florida slash pine plantation. Environmental

Entomology. 17(2): 259-265.

Auer, C.G.; Grigoletti, A., Jr. 1997. The occurrence of

Sphaeropsis sapinea on Pinus in the states of Parana and

Santa Catarina. Boletim de Pesquisa Florestal. 34: 99-101.

Bacon, G.J.; Hawkins, P.J.; Ward, J.P. 1982. Productivity of

commercial thinning operations in Queensland plantations:

influence of alternative silvicultural options. New Zealand

Journal of Forestry Science. 12(2): 308-323.

Bailey, R.L. 1986. Rotation age and establishment density

for planted slash and loblolly pines. Southern Journal of

Applied Forestry. 10(3): 162-168.

Bailey, R.L. 1994. A compatible volume-taper model based

on the Schumacher and Hall generalized constant form

factor volume equation. Forest Science. 40(2): 303-313.

Bailey, R.L.; Abernethy, N.C.; Jones, E.P., Jr. 1981. Diameter distribution models for repeatedly thinned slash pine

plantations. Gen. Tech. Rep. SO-GTR-34. New Orleans, LA:

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

Forest Experiment Station. 115-126.

Bailey, R.L.; Borders, R.E.; Ware, K.D.; Jones, E.P., Jr. 1985.

A compatible model relating slash pine plantation survival

to density, age, site index, and type and intensity of thinning. Forest Science. 31(1): 180-189.

Bailey, R.L.; Brooks, J.R. 1994. Determining site index and

estimating timber volumes without measuring heights.

Southern Journal of Applied Forestry. 18(1): 15-18.

Bailey, R.L.; Burgan, T.M.; Jokela, E.J. 1989. Fertilized

midrotation-aged slash pine plantations - stand structure

and yield prediction models. Southern Journal of Applied

Forestry. 13(2): 76-80.

Bailey, R.L.; Da Silva, J.A. Aleixo. 1988. Compatible models

for survival, basal area growth, and diameter distributions of

fertilized slash pine plantations. Gen. Tech. Rep. NC-GTR120. St. Paul, MN: U.S. Department of Agriculture, Forest

Service, North Central Research Station. 538-546.

Bailey, R.L.; Pienaar, L.V. 1983. An experiment to evaluate

row, selection, and combination thinning: design and

installation results. Gen. Tech. Rep. SE-GTR-24. Ashville,

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

Southeastern Forest Experiment Station. 213-216.

Bailey, R.L.; Ware, K.D. 1983. Compatible basal-area

growth and yield model for thinned and unthinned stands.

Canadian Journal of Forest Research. 13(4): 563-571.

Baker, F.A.; Verbyla, D.L.; Hodges, C.S., Jr.; Ross, E.W. 1993.

Classification and regression tree analysis for assessing

hazard of pine mortality caused by Heterobasidion

annosum. Plant Disease. 77(2): 136-139.

Baldwin, V.C., Jr. 1985. Survival curves for unthinned and

early-thinned direct-seeded slash pine stands. Gen. Tech.

Rep. SO-GTR-54. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment

Station. 460-465.

Baldwin, V.C., Jr.; Busby, R.L. 1993. A comparison of predicted mensurational and economic performance of thinned

Louisiana loblolly and slash pine plantations. Gen. Tech.

Rep. SO-GTR-93. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment

Station. 573-584.

Baldwin, V.C., Jr.; Feduccia, D.P.; Haywood, J.D. 1989. Postthinning growth and yield of row-thinned and selectively

thinned loblolly and slash pine plantations. Canadian

Journal of Forest Research. 19(2): 247-256.

Ball, M.J., III; Hunter, D.H.; Swindel, B.F. 1981. Understory

biomass response to microsite and age of bedded slash

pine plantations. Journal of Range Management. 34(1): 38-

42.

Ballard, R. 1981. Urea and ammonium nitrate as nitrogen

sources for southern pine plantations. Southern Journal of

Applied Forestry. 5(3): 105-108.

Balmer, W.E.; Mobley, H.E. 1983. Damaged stands:

appraisal of damages, recovery potential and management

decisions. In: The Managed Slash Pine Ecosystem.

Proceedings of a symposium held at the University of

Florida. June 9-11, 1981. 288-303.

Banfield, D.W. 1983. Direct seeding of pines by machine in

rows on lignite mine-spoils and abandoned agricultural

fields. Forestry Abstracts. 44(11): 706.

Bao, F.C.; Jiang, Z.H.; Jiang, X.O. [and others]. 1998.

Comparative studies on wood properties of juvenile vs.

mature wood and plantation vs. natural forest of main

plantation tree species in China. Scientia Silvae Sinicae.

34(2): 63-76.

Barnard, E.L.; Dixon, W.N.; Ash, E.C. [and others]. 1995.

Scalping reduces impact of soilborne pests and improves

survival and growth of slash pine seedlings on converted

agricultural croplands. Southern Journal of Applied

Forestry. 19(2): 49-59.

Barnard, E.L.; Gilly, S.P.; Dixon, W.N. 1991. Incidence of

Heterobasidion annosum and other root-infecting fungi in

residual stumps and roots in thinned slash pine plantations

in Florida. Plant Disease. 75(8): 823-828.
107

Barnard, E.L.; Hollis, C.A.; Pritchett, W.L. 1981. A comparative evaluation of seedling quality in commercial forest

nurseries in Florida. Tech. Pub. SA-TP-17. Atlanta, GA: U.S.

Department of Agriculture, Forest Service, Southeastern

Area State and Private Forestry. 34-41.

Barnard, E.L.; Kannwischer-Mitchell, M.E.; Mitchell, D.J.;

Fraedrich, S.W. 1997. Development and field performance

of slash and loblolly pine seedlings produced in fumigated

nursery seedbeds and seedbeds amended with organic

residues. In: National Proceedings: Forest and

Conservation Nursery Association. 32-37.

Barnard, E.L.; Miller, T. 1999. Southern cone rust: a growing

problem in need of attention? Gen. Tech. Rep. SRS-GTR30. Ashville, NC: U.S. Department of Agriculture, Forest

Service, Southern Research Station. 569-572.

Barnard, E.L.; Yin, M.; Ash, E.C., III [and others]. 1996. Aerial

application trial for control of southern cone rust in a slash

pine seed orchard using triadimefon. Tree Planters’ Notes.

47(4): 126-131.

Barnes, R.D.; Plumptre, R.A.; Quilter, T.K. [and others].

1999. The use of stem dissection to sample trees of different

ages for determining pulping properties of tropical pines.

IAWA Journal. 20(1): 37-43.

Barnett, J.P. 1981. Imbibition temperatures affect seed

moisture uptake, germination and seedling development.

Gen. Tech. Rep. SO-GTR-34. New Orleans, LA: U.S.

Department of Agriculture, Forest Service, Southern Forest

Experiment Station. 41-45.

Barnett, J.P. 1983. Freeze- and kiln-drying of slash pine

cones and seeds. Gen. Tech. Rep. SE-GTR-24. Asheville,

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

Southeastern Forest Experiment Station. 387-389.

Barnett, J.P. 1996. How seed orchard culture affects seed

quality: experience with the southern pines. Forestry

Chronicle. 72(5): 469-473.

Barnett, J.P.; Brissette, J.C.; Kais, A.G.; Jones, J.P. 1988.

Improving field performance of southern pine seedlings by

treating with fungicides before storage. Southern Journal of

Applied Forestry. 12(4): 281-285.

Barnett, J.P.; McLemore, B.F. 1984. Germination speed as a

predictor of nursery seedling performance. Southern

Journal of Applied Forestry. 8(3): 157-162.

Barnett, J.P.; Vozzo, J.A. 1985. Viability and vigor of slash

and shortleaf pine seeds after 50 years. Forest Science.

31(2): 316-320.

Barrett, R.L. 1983. Raising pines in planter flats. South

African Forestry Journal. 125: 58-67.

Barrows-Broaddus, J.; Dwinell, L.D. 1983. Histopathology of

Fusarium moniliforme var. sublgutinans in four species of

southern pines. Phytopathology. 73(6): 882-889.

Barrows-Broaddus, J.; Dwinell, L.D.; Kerr, T.J. 1985. Evaluation of Arthrobacter sp. for biological control of the pitch

canker fungus on slash pine. Canadian Journal of

Microbiology. 31(10): 888-892.

Barrows-Broaddus, J.B. 1981. Histopathology of Fusarium

moniliforme var. sublutinans in slash and loblolly pine.

Phytopathology. 71(8): 858.

Baynes, J.; Dunn, G.M. 1997. Estimating foliage surface

area index in 8-year-old stands of Pinus elliottii var. elliottii x

Pinus caribaea var. hondurensis of variable quality.

Canadian Journal of Forest Research. 27(9): 1367-1375.

Beeson, R.C., Jr. 1993. Benefits of progressively increasing

container size during nursery production depend on fertilizer regime and species. Journal of the American Society of

Horticultural Science. 118(6): 752-756.

Belanger, R.P. 2001. An integrated approach toward reducing losses from fusiform rust in merchantable slash and

loblolly pine plantations. Res. Pap. SRS-RP-23. Asheville,

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

Southern Research Station. 14p.

Belanger, R.P.; Godbee, J.F.; Miller, T.; Webb, R.S. 1983.

Salvage cutting in southern pine forests. Gen. Tech. Rep.

SE-GTR-24. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southeastern Forest Experiment Station.

382-386.

Belanger, R.P.; Miller, T.; Godbee, J.F. 1985. Fusiform rust:

guidelines for selective cutting of rust-infected trees in

merchantable slash pine plantations. Gen. Tech. Rep. SOGTR-56. New Orleans, LA: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station. 254-257.

Belanger, R.P.; Miller, T.; Schmidt, R.A. 1983. Pest management in slash pine. In: The Managed Slash Pine Ecosystem.

Proceedings of a symposium held at the University of

Florida. June 9-11, 1981. 273-287.

Belcher, E.W.; Leach, G.N.; Gresham, H.H. 1984. Sizing

slash pine seeds as a nursery procedure. Tree Planter’s

Notes. 35(3): 5-10.

Belmont, R.A.; Habeck, D.H. 1983. Parasitoids of Diooryctira

spp. (Pyralidae: Lepidoptera) coneworms in slash pine seed

production areas of north Florida. Florida entomologist.

66(4): 399-407.

Bengston, G.W.; Smart, G.C., Jr. 1981. Slash pine growth

and response to fertilizer after application of pesticides to

the planting site. Forest Science. 27(3): 487-502.

Bennett, F.A. 1983. Managing natural stands. In: The

Managed Slash Pine Ecosystem. Proceedings of a

symposium held at the University of Florida. June 9-11,

1981. 314-326.

Bennett, F.A.; Jones, E.P., Jr. 1983. Thinning and its effect

on growth. In: The Managed Slash Pine Ecosystem.

Proceedings of a symposium held at the University of

Florida. June 9-11, 1981. 304-313.
108

Berisford, C.W.; Turnbow, R.H., Jr.; Brady, U.E. 1982. Selective application of insecticides for prevention of southern

pine beetle attack. Journal of Economic Entomology. 75(3):

458-461.

Berry, C.R. 1981. Sewage sludge affect soil properties and

growth of slash pine seedlings in a Florida nursery. Tech.

Pub. SA-TP-17. Atlanta, GA: U.S. Department of Agriculture,

Forest Service, Southeastern Area State and Private

Forestry. 46-51.

Biblis, E.J. 1990. Properties and grade yield of lumber from

a 27-year-old slash pine plantation. Forest Products

Journal. 40(3): 21-24.

Binkley, D.; Johnson, D.W. 1992. Regional evaluations of

acid deposition effects on forest. Ecological Studies:

analysis and synthesis. 91: 534-543.

Birchem, R.; Sommer, H.E.; Brown, C.L. 1981. Comparison

of plastids and pigments of Pinus palustris Mill. and Pinus

elliottii Engelm. in callus tissue culture. International Journal

of Plant Physiology. 102(2): 101-107.

Birchfield, W.B.; McGawley, E.C.; Jones, J.P.; Yik, C.P. 1982.

Pinewood nematode identified in Louisiana. Louisiana

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Birdsey, R.A.; Van Hees, W.W.S.; Beltz, R.C. 1981. Pine

regeneration in southwest Arkansas. Res. Pap. SO-RP-165.

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

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Blakeslee, G.M. 1983. Major diseases affecting slash pine.

In: The Managed Slash Pine Ecosystem. Proceedings of a

symposium held at the University of Florida. June 9-11,

1981. 257-272.

Blanche, C.A.; Elam, W.W.; Hodges, J.D. [and others]. 1989.

Accelerated aging: a potential vigor test for longleaf and

slash pine seedlings. Gen. Tech. Rep. SO-GTR-74. New

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

Southern Forest Experiment Station. 107-114.

Boden, D.I. 1982. The relationship between timber density

of the three major pine species in the Matal Midlands and

various site and tree parameters. Report - Wattle Research

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Bonner, F.T. 1986. Measurement of seed vigor for loblolly

and slash pines. Forest Science. 32(1): 170-178.

Bonner, F.T. 1987. Effect of storage of loblolly and slash

pine cones on seed quality. Southern Journal of Applied

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mineralization in an acid sandy forest soil. In: Proceedings:

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Borders, B.E.; Bailey, R.L. 1986. A compatible system of

growth and yield equations for slash pine fitted with

restricted three-stage least squares. Forest Science. 32(1):

185-201.

Borders, B.E.; Bailey, R.L.; Ware, K.D. 1984. Slash pine site

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Forest Science. 30(2): 411-423.

Borders, B.E.; Harrison, W.M. 1989. Comparison of slash

pine and loblolly pine performance on cutover siteprepared sites in the Coastal Plain of Georgia and Florida.

Southern Journal of Applied Forestry. 13(4): 204-207.

Borders, B.E.; Jordan, J.B. 1999. Loblolly and slash pine

growth and yield prediction for regional timber supply

projection algorithms. Southern Journal of Applied Forestry.

23(4): 230-237.

Borders, B.E.; Shiver, B.D. 1995. Board foot volume estimation for southern pines. Southern Journal of Applied

Forestry. 19(1): 23-28.

Borders, B.E.; Souter, R.A.; Bailey, R.L.; Ware, K.D. 1987.

Percentile-based distributions characterize forest stand

tables. Forest Science. 33(2): 570-576.

Bower, R.C.; McKinley, C.R. 1987. Effects of related and

unrelated graft partners in slash pine (Pinus elliottii

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Brasil, M.A.M.; Montagna, R.G.; Coelho, L.C.C.; Veiga, R.A.

1982. Basic wood density of Pinus elliottii, var. elliottii in

three regions of the state of Sao Paulo. Boletim tecnico -

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weight of dry matter of Pinus elliottii Engelm. var. elliottii

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for diameter measurements in millimeters. South African

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pine flatwoods of east-central Florida. Natural Areas

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of a workshop. Tech. Pub. R8-TP-4. Atlanta, GA: U.S.

Department of Agriculture, Forest Service, Southern

Region. 303-305.

Brissette, J.C.; Vande Linde, F.; Barnett, J.P. 1983. Producing, storing, and handling quality of slash pine seedlings. In:

The Managed Slash Pine Ecosystem. Proceedings of a

symposium held at the University of Florida. June 9-11,

1981. 150-164.

Broerman, F.S.; Sarigumba, T.I.; Immel, M.J. 1983. Site

preparation and slash pine productivity. In: The Managed

Slash Pine Ecosystem. Proceedings of a symposium held at

the University of Florida. June 9-11, 1981. 131-149.

Bronson, M.R.; Dixon, R.K. 1988. In-vitro plantlet formation

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pine cotyledons. New Forests. 5(4): 277-288.

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vitro host-pathogen interactions of Pinus elliottii calli and

Fusarium moniliforme var. subglutinans. European Journal

of Forest Pathology. 22(6): 432-440.

Brooks, J.R.; Borders, B.E.; Bailey, R.L. 1992. Predicting

diameter distributions for site-prepared loblolly and slash

pine plantations. Southern Journal of applied forestry.

16(3): 130-133.

Brown, C.L.; Pienaar, L.V. 1981. Observations on growth of

paraquat-treated slash pine. Southern Journal of Applied

Forestry. 5(3): 145-150.

Buckner, J.L. 1983. Wildlife concerns in the managed slash

pine ecosystem. In: The Managed Slash Pine Ecosystem.

Proceedings of a symposium held at the University of

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146

Index of Authors

Page

B

Barnett, James P. 1

Behm, A. 66

Byram, Tom D. 7

C

Cassidy, L. 66

Castleberry, Steven B. 79

Clark, Alexander III 61

Coder, Kim D. 105

D

Dangerfield, Coleman W., Jr. 56

Daniels, Richard F. 61

Dickens, E. David 36, 56, 105

DiMartino, J. 66

Doran, D. 66

E

Ezell, A.W. 23

F

Fox, Thomas R. 50

Freeman, D. 66

Page

H

Helmers, J. 66

J

Jacobson, Marshall 20

Jokela, Eric J. 27

K

Keefe, K. 66

L

Long, A.J. 66

Long, Alan 98

M

McElvany, Bryan C. 105

Mengak, Michael T. 79

Miller, A. 66

Moorhead, David J. 56

Morris, L.A. 90

N

Nowak, Jarek 98

O

Ogden, E.A. 90

Page

P

Price, Terry S. 84

R

Ranasinghe, S. 66

Randall, C. 66

Rasser, M. 66

Ruth, A. 66

S

Schmidt, Robert A. 87

Sheffield, Raymond M. 1

Shipley, D. 66

Shiver, Barry D. 45

V

Van Loan, A. 66

W

White, Tim L. 7

Will, Rodney E. 36

Y

Yeiser, J.L. 23
Dickens, E.D.; Barnett, J.P.; Hubbard, W.G.; Jokela, E.J. 2004. Slash pine: still

growing and growing! Proceedings of the slash pine symposium. Gen. Tech. Rep.

SRS-76. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern

Research Station. 145 p.

This volume presents the experiences of scientists and land managers over a 20-

year period in managing southern pine ecosystems. In 17 research papers the

authors explore a renewed interest in managing slash pine over its natural and

expanded range, but particularly within the southeastern Coastal Plain, with a focus

on that species’ ability to produce high-grade, high-value lumber.

Keywords: Coastal Plain, growth and yield, high-grade lumber, pinestraw, seedling

production, slash pine, species deployment, tree improvement.

ENGLISH TO METRIC CONVERSION TABLE

Symbol When You Know Multiply by To Find Symbol

LENGTH

in inches 25.40 millimeters mm

in inches 2.54 centimeters cm

ft feet 30.48 centimeters cm

yd yards 0.9144 meters m

mi miles 1.609 kilometers km

AREA

in2 square inches 6.452 square centimeters cm2

ft2 square feet 0.0929 square meters m2

yd2 square yards 0.8361 square meters m2

mi2 square miles 2.590 square kilometers km2

acres 0.4047 hectares h

MASS (weight)

oz ounces 28.35 grams g

lb pounds 0.4536 kilograms kg

short tons 0.9072 metric tons t

(2,000 lb)

VOLUME

pt pints 0.4732 liters L

qt quarts 0.9464 liters L

gal gallons 3.785 liters L

ft3 cubic feet 0.0283 cubic meters m3

yd3 cubic yards 0.7646 cubic meters m3

TEMPERATURE

o

F degrees subtract 32, degrees oC

Farenheit multiply by 5/9 Celsius

METRIC TO ENGLISH CONVERSION TABLE

Symbol When You Know Multiply by To Find Symbol

LENGTH

mm millimeters 0.0394 inches in

cm centimeters 0.3937 inches in

m meters 3.281 feet ft

m meters 1.094 yards yd

km kilometers 0.6214 miles mi

AREA

cm2 square centimeters 0.1550 square inches in2

m2 square meters 1.196 square yards yd2

km2 square kilometers 0.3861 square miles mi2

ha hectares 2.471 acres

(10 000 m2

)

MASS (weight)

g grams 0.0353 ounces oz

kg kilograms 2.205 pounds lb

t metric ton 1.102 short tons

(1 000 kg)

VOLUME

mL milliliters 0.0338 fluid ounces fl oz

mL milliliters 0.0610 cubic inches in3

L liters 2.113 pints pt

L liters 1.057 quarts qt

L liters 0.2642 gallons gal

m3 cubic meters 35.315 cubic feet R3

m3 cubic meters 1.308 cubic yards yd3

TEMPERATURE

oC degrees multiply by 9/5, degrees o

F

Celsius add 32 Farenheit
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 The Forest Service, United States Department of 

 Agriculture (USDA), is dedicated to the principle of 

 multiple use management of the Nation’s forest 

 resources for sustained yields of wood, water, 

 forage, wildlife, and recreation. Through forestry 

research, cooperation with the States and private forest 

owners, and management of the National Forests and National 

Grasslands, it strives—as directed by Congress—to provide 

increasingly greater service to a growing Nation.

The USDA prohibits discrimination in all its programs and 

activities on the basis of race, color, national origin, sex, religion, 

political beliefs, sexual orientation, or marital or familial status 

(not all prohibited bases apply to all programs). Persons with 

disabilities who require alternative means for communication 

of program information (Braille, large print, audiotape, etc.) 

should contact the USDA’s TARGET Center at 202-720-2600 

(voice and TDD).

To file a complaint of discrimination, write USDA, Director, 

Office of Civil Rights, Room 326-W, Whitten Building, 1400 

Independence Avenue, SW, Washington, DC 20250-9410 or call 

202-720-5964 (voice and TDD). USDA is an equal opportunity 

employer.