United States

Department of

Agriculture

Forest

Service

Northern

Research Station

General Technical 

Report NRS-P-15

SHORTLEAF PINE RESTORATION

AND ECOLOGY IN THE OZARKS: 

PROCEEDINGS OF A SYMPOSIUM
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PESTICIDE PRECAUTIONARY STATEMENT

This publication/database reports research involving pesticides. It does not contain recommendations for their use, 

nor does it imply that the uses discussed here have been registered. All uses of pesticides must be registered by 

appropriate State and/or Federal agencies before they can be recommended. 

CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, and fi sh or other wildlife—if 

they are not handled or applied properly. Use all pesticides selectively and carefully. Follow recommended practices 

for the disposal of surplus pesticides and pesticide containers.
SHORTLEAF PINE RESTORATION

AND ECOLOGY IN THE OZARKS: 

PROCEEDINGS OF A SYMPOSIUM

November 7-9, 2006

Springfi eld, MO

Published by

USDA Forest Service

11 Campus Blvd., Suite 200

Northern Research Station

Newtown Square, PA 19073-3294

September 2007

Edited by

John M. Kabrick

Daniel C. Dey

David Gwaze

Hosted by 

The Missouri Department of Conservation
FOREWORD

The Shortleaf Pine Restoration and Ecology in the Ozarks Symposium was held at the University Plaza Hotel and Convention 

Center in Springfi eld, Missouri, on November 7-9, 2006. The purpose of the symposium was to communicate experiences, 

research, successes, challenges, and inspire inquiries into the ecology, management, and restoration of shortleaf pine 

communities and ecosystems in which shortleaf pine is prominent. The symposium brought together more than 200 registrants 

including private landowners, state and federal resource managers, consultants, members of conservation groups, and scientists 

from public and private institutions to exchange ideas and share knowledge about ecosystems containing shortleaf pine. 

Altogether, the symposium featured eight plenary presentations, 36 oral presentations, and nine poster presentations.

REVIEW PROCEDURES

Submitted manuscripts were peer-reviewed by two or more professionals familiar with the subject matter. The reviewed 

manuscripts were each assigned to one of the editors to render decisions about the review comments and to return the 

manuscripts. Revised manuscripts that were examined by the editors; satisfactory manuscripts were forwarded to the USDA 

Forest Service Northern Research Station for technical editing and publishing. Extended abstracts included herein were 

reviewed by the technical editors. The authors are responsible for the accuracy and content of their papers and extended 

abstracts. 

LIST OF REVIEWERS

The editors sincerely appreciate the efforts of the following colleagues who reviewed one or more manuscripts. Their efforts 

greatly improved the content of this proceeding.

Dirk Burhans

Tom Byram

Rick Clawson

Mark Coggeshall

John Dwyer

Vern Everson

Jim Guldin

George Hartman

Doyle Henken

Jeremy Kolaks

David Larsen

Ron Masters

Ross Melick

Paul Nelson

Daniel Peterson

Bob Pierce

Mark Robbins

Charles Ruffner

Felipe Sanchez

Andy Scott

Michael Shelton

Steve Shifl ey

Mike Stambaugh

Carrie Steen

Hank Stelzer

Michael Stine

Charly Studyvin

Chuck Tauer

Ron Thill

Clint Tramel

Tom Treiman

Jerry Van Sambeek

Doug Wallace

Mike Wallendorf

Steve Westin

Eric Zenner

CONTINUING FORESTRY EDUCATION

For attending this conference, each registrant was eligible for up to 19.5 hours of Continuing Forestry Education (CFE) 

Category 1 credit hours through the Society of American Foresters.

SYMPOSIUM ORGANIZING COMMITTEE

Missouri Department of Conservation:

David Gwaze (chair), Tom Nichols, Mike Huffman, Tom Kulowiec, Duane Parker, Larry Rieken, Rhonda Rimer, Matt Seek

USDA Forest Service:

John Kabrick, David Massengale, Charly Studyvin

University of Missouri-Columbia:

Mark Coggeshall, Richard Guyette, Rose-Marie Muzika

ACKNOWLEDGMENTS

The Symposium Organizing Committee gratefully acknowledges the conference sponsors:

Current River Pole Company

Eastern National Park and Monument Association

Missouri Chapter of the Wildlife Society

Missouri Department of Conservation

Missouri Society of American Foresters

The National Wild Turkey Federation

University of Missouri-Columbia Department of Forestry

U.S. Forest Service, Northern Research Station

U.S. Forest Service, Mark Twain National Forest
CONTENTS

PLENARY

Historical and Social Factors Affecting Pine Management in the Ozarks 

During the Late 1800s Through 1940 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Robert J. Cunningham

The Historical Ecology of Fire, Climate, and the Decline of Shortleaf Pine in the Ozarks . . . . . . . . . . . . . . . .8

Richard P. Guyette, Rose-Marie Muzika, and Stephen L. Voelker

Shortleaf Pine Composition and Structure in the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

W. Keith Moser, Mark Hansen, William H. McWilliams, and Raymond Sheffi eld

Genetic Variation in the Southern Pines: Evolution, Migration, 

and Adaptation Following the Pleistocene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Ronald Schmidtling

Forest Stand Dynamics of Shortleaf Pine in the Ozarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

David R. Larsen

The Importance of Shortleaf Pine for Wildlife and Diversity in Mixed Oak-Pine Forests 

and in Pine-Grassland Woodlands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Ronald E. Masters

Restoration and Management of Shortleaf Pine in Pure and Mixed Stands—

Science, Empirical Observation, and the Wishful Application of Generalities . . . . . . . . . . . . . . . . . . . . . . .47

James M. Guldin

ECOLOGY OF SHORTLEAF PINE SYSTEMS

Successional Trends of Six Mature Shortleaf Pine Forests in Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Michael C. Stambaugh and Rose-Marie Muzika

Shortleaf Pine: A Species at Risk? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68

Charles G. Tauer, Shiqin Xu, C. Dana Nelson, and James M. Guldin

Tree Species Associations of Pinus echinata Mill. Over a Large-Scale Sampling Regime 

on the Interior Highlands of Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76

James F. Rosson, Jr.

GENETICS AND TREE IMPROVEMENT OF SHORTLEAF PINE

Genetic Improvement of Shortleaf Pine on the Mark Twain, Ouachita, 

and Ozark National Forests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84

Charly Studyvin and David Gwaze

Performance of Shortleaf Pine Provenances in Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89

David Gwaze, Jennifer Myszewski, and John Kabrick

Loblolly Pine SSR Markers for Shortleaf Pine Genetics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95

C. Dana Nelson, Sedley Josserand, Craig S. Echt, and Jeff Koppelman

Chromosomal Locations of the Ribosomal DNA Genes in Shortleaf Pine . . . . . . . . . . . . . . . . . . . . . . . . . . . .99

Nurul Islam-Faridi, M. Abdul Majid, and C. Dana Nelson
Shortleaf Pine Hybrids: Growth and Tip Moth Damage in Southeast Mississippi . . . . . . . . . . . . . . . . . . . .102

Larry H. Lott, Maxine T. Highsmith, and C. Dana Nelson

Phylogeographic Analyses and Evaluation of Shortleaf Pine Population Structure in Missouri . . . . . . . . .104

Jeff Koppelman, Emily Parsons, Briedi Scott, Jennifer Collantes, Lori S. Eggert, 

Sedley Josserand, Craig Echt, and C. Dana Nelson

REGENERATING AND MANAGING SHORTLEAF PINE

Regenerating Shortleaf Pine: Results of a 5-Year Cooperative Research Initiative . . . . . . . . . . . . . . . . . . . .105

James P. Barnett and John C. Brissette

Underplanting Shortleaf Pine in the Missouri Ozarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112

Jason Jensen, Cliff Smith, Mark Johanson, and David Gwaze

Underplanting Shortleaf Pine at Coldwater Conservation Area in Missouri . . . . . . . . . . . . . . . . . . . . . . . . .117

Jason Jensen and David Gwaze

Direct Seeding of Shortleaf Pine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119

Corinne S. Mann and David Gwaze

What Fire Frequency is Appropriate for Shortleaf Pine Regeneration and Survival? . . . . . . . . . . . . . . . . .121

Michael C. Stambaugh, Richard P. Guyette, and Daniel C. Dey

Effects of Site Preparation Subsoiling and Prescribed Burning on Survival and Growth 

of Shortleaf Pine in the Mark Twain National Forest: Results After 20 Growing Seasons . . . . . . . . . . . .129

David Gwaze, Ross Melick, Lynn McClure, Charly Studyvin, and David Massengele

The Effects of a Wildfi re on Pine Seedling Recruitment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134

Paula C. Gnehm and Brad Hadley

Hardwood Regeneration Related to Overstory Shortleaf Pine Basal Area and Site Index 

in Arkansas and Eastern Oklahoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137

Douglas J. Stevenson, Thomas B. Lynch, and James M. Guldin

Shortleaf Pine Reproduction Abundance and Growth in Pine-Oak Stands in the Missouri Ozarks . . . . . .138

Elizabeth M. Blizzard, Doyle Henken, John M. Kabrick, Daniel C. Dey, 

David R. Larsen and David Gwaze

Shortleaf Pine Seedling Production and Seeding Trends in Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147

David Gwaze, Greg Hoss, and Dena Biram

The State of Mixed Shortleaf Pine-Upland Oak Management in Missouri . . . . . . . . . . . . . . . . . . . . . . . . . .153

Elizabeth M. Blizzard, David R. Larsen, Daniel C. Dey, John M. Kabrick, and David Gwaze

MAINTAINING PRODUCTIVITY AND PROTECTING WATER QUALITY 

Productivity of Planted Shortleaf Pine in Artifi cially Compacted Clarksville Soil . . . . . . . . . . . . . . . . . . . .158

Felix Ponder, Jr. 

Amounts and Spatial Distribution of Downed Woody Debris, Snags, Windthrow, 

and Forest Floor Mass Within Streamside Management Zones 

Occurring in Shortleaf Pine Stands Five Years After Harvesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165

Hal Liechty
WILDLIFE DIVERSITY IN SHORTLEAF PINE FORESTS AND WOODLANDS

Wildlife Diversity of Restored Shortleaf Pine-Oak Woodlands in the Northern Ozarks . . . . . . . . . . . . . . . .167

Corinne S. Mann and Andrew R. Forbes

Birds of Shortleaf Pine Forests in Missouri: An Historical and Contemporary Perspective . . . . . . . . . . . .168

William R. Eddleman, Richard L. Clawson, and Jody Eberly

Avian Response to Pine Restoration at Peck Ranch Conservation Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . .176

Richard Clawson, Carrie Steen, Kim Houf, and Terry Thompson

ECONOMICS OF MANAGING SHORTLEAF PINE

Timber Harvest Levels and Pressure on Shortleaf Pine in Missouri . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179

Thomas B. Treiman, Ron J. Piva, and W. Keith Moser

Financial Rates of Return on Shortleaf Pine Stands in Arkansas Between 1978 and 1995 . . . . . . . . . . . . . .186

Andrew J. Hartsell

GROWTH AND YIELD OF SHORTLEAF PINE

Branch and Foliage Biomass Relations for Shortleaf Pine in Southeast Oklahoma . . . . . . . . . . . . . . . . . . .192

Charles O. Sabatia, Thomas B. Lynch, and Rodney E. Will

An Individual-Tree DBH-Total Height Model with Random Plot Effects for Shortleaf Pine . . . . . . . . . . . .194

Chakra B. Budhathoki, Thomas B. Lynch, and James M. Guldin

RESTORING SHORTLEAF PINE COMMUNITIES

Shortleaf Pine Natural Community Restoration on Peck Ranch Conservation Area 

in the Missouri Ozarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .196

John G. Tuttle and Kim J. Houf

Glade/Woodland Restoration in the St. Francis Mountain Bird Conservation Area . . . . . . . . . . . . . . . . . . .202

David A. Hasenbeck

The Pineknot Project: Restoration of a Missouri Ozark Pinery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .204

Douglas Ladd, Blane Heumann, and Paul Nelson

Shortleaf Pine-Bluestem Restoration in the Ouachita National Forest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206

Larry D. Hedrick, George A. Bukenhofer, Warren G. Montague, 

William F. Pell, and James M. Guldin

The Ozark Highlands Pine-Oak Woodland Restoration Partnership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .214

Tim A. Nigh
1

INTRODUCTION

Shortleaf pine (Pinus echinata Mill.) in the Missouri 

Ozarks has direct ties to the region’s settlement, industrial 

exploitation, and the development of forest management in 

Missouri. Use of the forest resources have often resulted in 

struggles between the local citizens, wood industries, and 

politicians that benefi ted from the short-term exploitation, 

and citizen groups and agencies seeking long-term 

policies for maintaining the pine resource. Local economic 

conditions will continue to infl uence the extent of shortleaf 

pine and the acceptance of management schemes on both 

public and private lands.

MODEL FOR FORESTRY DEVELOPMENT

Throughout the world, the concepts of silviculture and 

forest management have been around for approximately 

400 years. The development of modern forest management 

in the Missouri Ozarks is tied to activities throughout the 

past century and in particular to the industrial and political 

activities prior to 1940. Kimmins (1997) indicates that 

wherever and whenever forestry is developed, there has 

been a similar sequence of developmental stages: 

• Stage 1: Unregulated exploitation of local forests.

• Stage 2: Regulation of forest exploitation through 

legal and political mechanisms or religious taboos.

• Stage 3: Development of an ecological approach to 

silviculture and timber management.

• Stage 4: Progression toward social forestry to be 

environmentally and ecologically sound but also 

responsive to diverse demands of society and local 

communities.

HISTORICAL AND SOCIAL FACTORS AFFECTING PINE MANAGEMENT 

IN THE OZARKS DURING THE LATE 1800s THROUGH 1940

Robert J. Cunningham1

ABSTRACT.—During the latter part of the 19th century, European descendents migrated to 

the Ozarks seeking employment with large pine-producing sawmills. Within a 30-year period, 

most of the pine resources across six million acres had been exploited and were largely 

replaced by oak-hickory forests. The era ended with residents struggling with economic 

challenges and limited natural resources. Differing values and management philosophies 

toward the forest, and attempts to restore pine communities by creating a system of forest 

management and recovery in Missouri, have been a legacy of confl ict among people.

1

Private Land Services Regional Supervisor (RJC), Missouri 

Department of Conservation, P. O. Box 138, West Plains, MO 

65775: to contact call (417) 255-9561 x 225 or email at Bob.

Cunningham@mdc.mo.gov

The history of forestry in the Ozarks and ultimately the 

history of forest management in Missouri largely follow the 

Kimmins model. The stages are not only continuous but are 

fl uid, overlapping, and often repeating. Historic periods of 

the Ozarks have recorded progress towards the later stages 

of development only to be succeeded by a reversion to 

the primary stages as changes in economic conditions and 

emerging industries challenge the values that society places 

on the forest. 

THE PINE RESOURCE

Even though forests covered 70 percent of Missouri prior 

to settlement, perhaps the most celebrated forest cover was 

the pine-covered hills of the southeastern Ozarks. Known 

as the Courtois Hills, this rugged area has steep-sided 

hills and chert-covered ridges (Fig. 1). The name Courtois 

Hills is derived from the Courtois Creek in Crawford 

County. Courtis Hills extend over all of Carter, Reynolds, 

and Shannon Counties, and parts of Crawford, Dent, Iron, 

Wayne, Oregon, Butler, Ripley, and Madison Counties 

(Hill 1949). 

Presettlement pine was estimated to have occurred across 

6.6 million acres in the Missouri Ozarks (Liming 1946). 

Not all of its range was limited to the Courtois Hills as 

pine was also found in some of Missouri’s south-central 

and southwestern counties. The vast pine forests were 

distributed unevenly – some areas being heavily timbered 

with pine and some mixed with hardwoods, such as white 

oak (Quercus alba L.), post oaks (Q. stellata Wangenh.), 

black oak (Q. velutina Lam.), and blackjack oak (Q. 

marilandica Muenchh.). Pine occupied most of the sandy 

land, and part of the fl int ridges. In the southern counties, 

pine grew profusely on the fl at, clay uplands. White and 

black oak grew commonly on the ridges while post oak and 

blackjack grew on the dry, stony hillsides (Hill 1949). 
2

Pine occurred mostly in clumps or groups, and occasionally 

formed pure stands. One of the most extensive areas was the 

Irish Wilderness in northeastern Oregon County. In general 

pine lands were fairly open, with little or no underbrush 

growing beneath the pines except for little bluestem grass 

(Schizachyrium scoparium) and an occasional oak sprout 

(Martin and Presley 1958). Pine volumes averaged 4,000 

board feet per acre with occasional stands containing 25,000 

board feet per acre (Hill 1949). Rare accounts of huge trees, 

some as large as 7 feet in diameter at the stump, have been 

collected through oral histories (Smith 1959).

THE PEOPLE

European descendents essentially poured into Missouri’s 

agriculturally rich areas during the early 1800s. The hilly 

sections of the Ozarks were the state’s last physical frontier 

and were largely bypassed due to poor transportation routes 

leading into the region and a general lack of fertile farm 

ground (Galloway 1961).

The fi rst arrivals trickled into the Ozarks during the fi rst 

half of the 19th century. Three-fourths of the early residents 

Figure 1.—Southeastern Missouri Ozark counties 

geographically known as the Courtois Hills.

had migrated from Tennessee and Kentucky. For the most 

part, they were Scots-Irish descendents and possessed a true 

frontier spirit (Rafferty 1980). 

Hammar (1935) typifi es four aspects of frontier 

development that had an enduring effect on the Ozarks: 

(1) the dominance of agriculture in the conquest for the 

Middle West, and the corollary assumption that what was 

good for a rich agricultural section was equally good for 

the sections neither agricultural nor rich; (2) the race for 

acquisition based on the idea that he serves (and serves 

well) who merely acquires; (3) a fi erce impatience with any 

government interference in “private” affairs and an almost 

complete disdain for public aspects of conservation; and 

(4) a faith in competition as a suffi cient regulator of 

business, and a great willingness to give free rein to private 

initiative. Nearly 200 years later, these attitudes still embody 

the Ozark spirit. 

The early settlers brought an outlook that all land was 

essentially agricultural land. Their primary occupation 

was subsistence farming; they were poor but nearly selfsuffi cient. The rugged and stony nature of the soils fought 

back against cultivation. When plowed, they were quickly 

worn out and vulnerable to erosion (Hammar 1935). 

Most of the inhabitants were engaged in raising livestock on 

the open range. The pine forests were well suited to produce 

forage because they were naturally open with an understory 

of grasses. So long as the forest remained in its frontier or 

pristine condition, it could continue to support this form of 

agriculture and provide the basic needs for the people—but 

with limitations. As Hammar (1935) suggested, the region’s 

thin and infertile soils were threatened with oversettlement.

A second phase of immigration started after the Civil War. 

Until this time, the Ozarks had been isolated from intensive 

settlement and commercial resource exploitation. The 

earliest pioneers had established small farms primarily in 

the valleys. It was during the second phase that persons 

employed by eastern capitalists penetrated and developed 

much of the region (Galloway 1961). 

Since the demand for forest products was concentrated 

in the more populated eastern United States, Missouri’s 

remote forests had remained uncut. Westward migration of 

people onto the treeless plains quickly drew attention to the 

Ozarks’ forests. During the latter half of the 19th century, 

populations in the heavy pine-bearing counties increased 

from two to fi ve times over the reported population of 

1860 as lumber companies established large operations 

across the southeastern Ozarks (Shoemaker 1943). Carter, 

Oregon, Reynolds, Ripley, Shannon, and Wayne Counties 

best illustrates this since they were the center of the heaviest 

lumbering operations (Table 1).
3

Table 1.—Population trends in selected Missouri Ozarks counties.

*Figures reported for 1860 are listed as free men and do not include slave numbers.

County 1860* 1870 1880 1890 1900 1910 1920 1930 1940

Carter 1,215 1,455 2,168 4,659 6,706 5,505 7,482 5,503 6,226

Oregon 2,983 3,287 5,791 10,467 13,906 14,681 12,889 12,220 13,390

Reynolds 3,135 3,756 5,722 6,803 8,161 9,592 10,106 8,923 9,370

Ripley 3,669 3,175 5,377 8,512 13,186 13,099 12,061 11,176 12,606

Shannon 2,271 2,339 3,441 8,898 11,247 11,443 11,865 10,894 11,831

Wayne 5,368 6,068 9,096 11,927 15,309 15,181 13,012 12,243 12,794

THE EXPLOITATION

Even though the land in the Ozarks was characterized as 

rocky and unproductive, it had standing timber of both oaks 

and pine. Timber was a salable commodity, but it required a 

capital outlay that the ordinary farmer could not afford. As a 

result, much land became tax delinquent until it was picked 

up by speculators and lumbermen starting around the late 

1860s (Hill 1949). 

Missouri’s pine lumber boom started in the late 1880s and 

ended in the 1920s. At its peak in 1899, lumber production 

in Missouri was 724 million board feet (Cunningham and 

Hauser 1989). The largest mills were the Missouri Lumber 

and Mining Company, fi rst at Grandin and then later moved 

to West Eminence; the Holaday-Klotz Land and Lumber 

Company at Greenville; the Clarkson Sawmill at Leeper; 

the Cordz-Fisher Lumber Company at Birch Tree; the Ozark 

Land and Lumber Company at Winona; and the BunkerCuller Lumber Company at Bunker (Fig. 2). Added to these 

larger mills were scores of smaller production sawmills. 

Not all sawmills were engaged in the production of 

pine lumber. Between 1877 and 1898, Missouri had 184 

stationary and 41 portable sawmills with a combined daily 

capacity that fl uctuated between 2 million and 3.8 million 

board feet. Ten companies included logging railroads in 

their inventory (Fernow 1899). 

The Missouri Lumber and Mining Company at Grandin, 

MO, was the fi rst and largest company to begin large-scale 

lumbering in the Ozarks. Its operations were characteristic 

of the era and region with high-capacity milling facilities, 

huge labor forces and railroad logging. Its sawmilling 

operation began in 1887 and lasted until 1909 at Grandin. 

Operations moved to West Eminence in the fall of 1909 

and continued until 1919. At its height of production, the 

Grandin-based sawmill consumed the timber resources 

from 70 acres per day. At the end of its fourteenth year of 

operation, it had cut more than 213,017 acres of forest land 

(Galloway 1961). 

Figure 2.—Towns with large pine sawmilling operations 

between 1880 and 1920.

The turn-of-the-century lumber boom had a devastating 

effect on the pine resource. Lumber company policies and 

practices virtually eliminated pine trees large enough for 

reseeding the forest. The Missouri Lumber and Mining 

Company had required all pines cut to a 12-inch stump 

(Hill 1949). Though not as severe, its competitor, the Ozark 

Land and Lumber Company at Winona, cut all pines to a 

14-inch stump (Martin and Presley 1958).

Uncontrolled burning and timber thieves’ cutting of 

the remaining pine as soon as it reached a minimum 

merchantable diameter further destroyed any chances 
4

of seed or seedlings to develop. As the timber resources 

diminished and the big mills closed, the remaining people 

returned to grazing the open range for an economic base. 

Hardwoods quickly replaced the pine and those trying 

to graze the cutover lands had to contend with regrowth. 

Without fi re, the grass would dwindle. Fire killed pine 

seedlings and caused the hardwoods to vigorously resprout. 

Germinating pine seedlings were unable to survive under the 

prolifi c hardwood canopy (Cunningham and Hauser 1989). 

Prior to organized fi re control in the 1930s, it was estimated 

that the total wooded area of the Ozarks burned over at least 

once every 3 years (Callison 1953). 

The lumber companies were not interested in reforestation. 

Prior to purchase, much of their lands had been tax 

delinquent and was purchased with uncertain titles. Once the 

pine timber had been removed, the taxes would remain high. 

Cutover lands that could not be sold were abandoned and 

again auctioned at public tax sales (Cunningham and Hauser 

1989). 

The big mills had been an economic boon to the people 

living in the Ozarks. They had provided steady employment, 

improved transportation both into and away from the 

region, and enhanced the people’s social connectivity. 

Without the benefi ts afforded by this extractive industry, the 

people remaining after the mills’ closures were once again 

threatened with the prospects of impoverishment and the 

struggle for survival. 

THE CALL FOR REGULATION

Long before Missouri’s lumber boom, there were 

concerns from a few government and industry leaders 

expressed concern that the nation’s timber supply was not 

inexhaustible and that there was a real threat of a timber 

famine (Galloway 1961). By the end of the 19th century, 

nation-wide attention was being drawn to a growing 

conservation movement in the United States. 

The word “reforestation” appeared regularly in Missouri 

newspapers between 1910 and 1940. It was often used 

directly or indirectly in the context of the loss of the pine 

resource in the Ozarks stemming from the earlier lumber 

boom. Reforestation and forest fi re control would become 

the rallying cause for the creation of both a state forestry 

program and establishment of a national forest in Missouri. 

Citizen groups led the fi ght for reforestation in Missouri 

during the fi rst third of the 1900s. This series of 

groundbreaking events was perhaps the most unrecognized 

yet important actions relating to Missouri’s conservation 

movement in the 20th century. With each attempt however, 

the people of the Ozarks largely opposed the prospects of 

reforestation through government intervention, be it the 

institution of agencies, laws, or programs, because of the 

perceived threats they represented to their way of life.

By 1905, conservation leadership was coming from an 

unlikely source: John B. White, president and general 

manager of the Missouri Lumber and Mining Company. 

President Theodore Roosevelt had appointed White to 

investigate problems with lumbermen gaining control over 

valuable forest lands at Cass Lake, MN. White’s ensuing 

recommendations quickly won favor with the President 

and the public. Two years later, the president appointed 

him to the forestry section of the National Conservation 

Commission (Galloway 1961). 

During the May 1908 National Governors’ Conference 

at Washington, D.C., Missouri Governor Joseph Folk 

addressed in his speech the issue of reforestation:

The forestry question is our problem, and it is a 

problem that we must settle, and settle soon.... 

We want to put our forests in proper condition to 

preserve those we have, and to adopt a scheme of 

reforestation. In Missouri we have no state forester, 

but as soon as I go back I am going to appoint 

a State Forestry Commission. I believe every 

Governor ought to do the same thing, and I am sure 

that his State Legislature when he meets will ratify 

his action. 

We want to preserve our forests. Now, I hope I 

am not encroaching upon forbidden ground, but I 

have been wondering why, if it be so necessary to 

preserve our forests, it would not be a good idea 

to put lumber on the free list—make lumber free. 

I hope that is not heresy. It seems to me that for 

every foot of lumber brought here from another 

country we preserve a foot of lumber in our own 

forests. (Folk 1909).

Governor Folk appointed a four-man forestry commission in 

1909. Since the rural-dominated General Assembly failed to 

appropriate funds, the members of the commission, which 

included John B. White, served without pay (Galloway 

1961). A number of similar attempts by Folk’s successors 

would fail as well (Flader 2004). 

The U.S. Congress passed the Weeks Act in 1911 that 

authorized federal acquisition of lands for national forests 

in the eastern states. Suddenly Missouri was in line for a 

national forest, but the Missouri General Assembly would 

have to pass enabling legislation. In 1914, Clifford Hall, 

Forest Examiner for the U.S. Forest Service, completed 

his examination for the potential purchase of two national 

forest units around the St. Francis Mountains and the upper 

Current River drainage. The General Assembly voted 

against the legislation since its constituency was largely 

opposed to federal intervention and control of lands the 

residents were using to suit their needs (Flader 2004). The 

prospect of a “national forest reserve,” or a “national park” 

as it was so often referred to at the time, would be delayed 

for several decades. 
5

The Missouri Forestry Association (MFA) was formed 

in 1922. Its purpose as stated in its constitution was to 

advise the public of the importance of the timber crops in 

economic life so as to insure a supply of timber for future 

generations. Its leadership included President Dr. Hermann 

von Schrenck, timber engineer and plant pathologist for 

the Missouri Botanical Gardens; Vice-Presidents J. W. 

Fristoe, president of the Moss Tie and Timber Company 

of St. Louis; Marie Turner Harvey of the Porter School at 

Kirksville; and Secretary Frederick Dunlap, former head 

of the forestry department of the University of Missouri. 

The MFA also had an advisory council that included 

forest industry leaders such as John Himmelburger of 

Himmelberger-Harrison Lumber Company, Cape Girardeau; 

John B. White, former president of the Missouri Lumber 

and Mining Company, Grandin; and Mrs. W. W. Martin, 

president of the Missouri Federation of Women’s Clubs 

(Current Local, 5 January 1922). 

The MFA opposed regulation at any level but supported 

the formation of a state forestry board and encouraged the 

practice of forestry on private lands. Oddly, it opposed the 

creation of a national forest in Missouri and saw only a very 

limited role for state forests as demonstration areas 

(Flader 2004). 

Forest restoration in Missouri would have to wait until 1924 

when Congress passed the Clark-McNary Act. Matching 

federal funds were afforded to states with forestry programs 

and Missouri was ready for the opportunity. Due to a 

threatened veto by the Governor, the MFA agreed to provide 

the state’s share of the matching funds (Flader 2004). 

After repeated attempts since 1909, the Missouri General 

Assembly fi nally created an offi ce of state forester within 

the Department of Agriculture in 1925 (Keefe 1987). 

Frederick Dunlap, former head of the forestry department of 

the University of Missouri and secretary of the MFA, was 

appointed State Forester and he in turn hired Paul Dunn to 

be his only district forester at Ellington. In 1926, Dunlap 

reported to the General Assembly that the bill for his offi ce’s 

services between Aug. 12, 1925 and Jan. 1, 1927, came 

to $12,817.75, paid with the private funds of the MFA. 

Chapter 1 of his report dealt with the issues of wildfi re and 

fi re protection. Four subsequent sections dealt with forest 

plantings of 70,000 seedlings across several counties, the 

State Nursery on the prison farm at Cedar City, model 

plantings, and appreciation of forestry (Ellington Press, 

3 March 1927). 

From 1925 through 1931, Dunlap and Dunn focused on 

organizing fi re control efforts and reforestation through 

public outreach and education activities. Regular features 

originating from Dunlap’s offi ce appeared in newspapers 

throughout Missouri. These articles discussed forestry issues 

and outlined Dunn’s activities in Reynolds County. 

With cooperative assistance from county extension agents, 

Dunn brought fi lms entitled “Pines Will Come Back” and 

“What Forest Management Means to You” to local schools 

and communities (Ellington Press, 14 November 1929). 

Perhaps in an effort to heal the damage infl icted by the 

earlier timber boom, Dunlap promoted the collecting and 

marketing of shortleaf pine seed. The Ellington Press

(11 September 1930) quoted Dunlap:

People living close to Nature stands of shortleaf 

yellow pine in southern and eastern Missouri have 

a splendid opportunity, at this time, to profi t by the 

sale of the seed of the desirable evergreen...all they 

need to do is to gather, clean, store and market this 

seed....The price last year (1929) was from $8.20 

to $10 per pound and collectors have sometimes 

been paid up to $20...Such prices can be paid, 

because twenty-fi ve acres of land can be seeded 

with one pound of seed.

There was no follow-up report to Dunlap’s feature. One 

can only imagine this as another desperate and frustrating 

attempt to show the General Assembly the possibility for 

success—and all this done with only one fi eld forester and 

a scant budget. Perhaps because of the Great Depression, 

the legislature neglected to appropriate funds for forestry in 

1931 and the forestry division was abolished (Keefe 1987). 

As dejected as Frederick Dunlap and Paul Dunn may have 

felt with their dismissals, the venture was a success as it 

marked the true beginnings of reforestation and recovery in 

the Ozarks. 

The public’s interest in forestry in the 1920s was not limited 

to Dunlap’s effort. By 1929, the General Assembly had 

fi nally passed an enabling act authorizing federal purchase 

of forest land in the state but had restricted acquisition to no 

more than 2,000 acres per county (Flader 2004). In 1930, 

the Missouri Ozarks Chamber of Commerce under the 

leadership of Lon Sanders passed a resolution “...pledging 

the continued agitation for a national park or a national 

forest reserve...” (Ellington Press, 1 May 1930). This 

Chamber of Commerce was an 11-county alliance dedicated 

to promoting the Ozark region (Fuchs 1978).

Throughout 1933, State Senator Carter M. Buford from 

Ellington campaigned on behalf of the national forest. At 

a gathering of 300 boosters at Howes Mill in Dent County, 

Buford was called upon to address the crowd. The Ellington 

Press (30 July 1933) recorded the moment:

The Senator from his widespread experience in 

dealing in lands and timber in this section said that 

he heartily endorsed the proposed plan. He urged 

those present to go home and tell their neighbors 

about it and help to build up sentiment for the 

movement. Senator Buford stated that the counties 

were facing bankruptcy because the owners of 
6

so much of the cut-over lands were unwilling or 

unable to pay the taxes on this land, and were 

letting it sell for prices that will not even pay the 

cost of legal advertisement. He said that if the 

present conditions continue that taxes would be 

raised to an unbearable height on improved farms 

and on city and town property and that these would 

be fi nally sold for taxes.

(That same year, Senator Carter M. Buford’s son, Wilbur C. 

Buford, became the last politically appointed director of the 

Missouri Game and Fish Commission. Wilbur Buford was 

named the fi rst Commissioner of the newly formed Missouri 

Department of Conservation in 1937 [Keefe 1987].)

In August 1933, the National Forestry Commission 

announced plans to purchase 450,000 acres in four units that 

extended over 18 counties in the Missouri Ozarks (Ellington 

Press, 31 August 1933). Eventually the Missouri General 

Assembly removed all acreage limitations and “lands that 

nobody wanted” would become the Mark Twain National 

Forest (Flader 2004).

The fi nal great act for securing both conservation and 

ultimately reforestation in the Ozarks would be the petition 

drive for Amendment 4, calling for the creation of the nonpolitical Conservation Commission, as spearheaded by the 

Conservation Federation of Missouri. On Election Day, 

Nov. 3, 1936, Missouri voters passed the initiative by a 

margin of 897,213 for to 351,962 against. In March 1938, 

George O. White was hired as the state forester. Like his 

predecessor Frederick Dunlap, White saw fi re control and 

landowner education as two of the most important needs 

(Keefe 1987). 

Building citizen support for modern conservation in 

Missouri had taken nearly 40 years. Restoring the shortleaf 

pine component to the Ozarks would be a daunting task that 

continues into the 21st century. 

Liming (1945) reported that the productivity of 5 to 

6 million acres of Ozark forest land can be materially 

increased by raising the proportion of pine in the forest 

cover exclusive of about 1 million acres now adequately 

stocked with pine. He estimated that pine had been 

eliminated by misuse on approximately 3 to 4 million acres, 

and it would take 50 to 100 years to artifi cially reintroduce 

it. The age-old problems of the destruction of seed and 

seedlings by uncontrolled burning and the persistent cutting 

of pine at a minimum merchantable diameter were to blame. 

Fixing these problems would challenge both the Missouri 

Department of Conservation and the U.S. Forest Service for 

decades to come. 

SOCIAL FORESTRY

Kimmins’ (1997) developmental stages can be interpreted 

through psychologist Abraham Maslow’s Hierarchy of 

Human Needs. Human beings are motivated by needs. 

Basic needs such as food, shelter, safety, and security must 

be satisfi ed fi rst. Growth needs such as beauty, goodness, 

meaningfulness or perhaps an interest in natural resources 

conservation, and biodiversity are affordable only after the 

basic needs have been met (Kimmins 1997). 

Limited resources, poor local economies, extractive 

industries and a historical trend of poverty have kept the 

Ozarks’ inhabitants focused on their day-to-day existence. 

Since the people have depended on the lands that support 

forest resources, policies and regulations proposed or 

enacted by government agencies that invoke change are 

often perceived as threats to the satisfaction of their basic 

needs.

The Ozarks can no longer be regarded as the isolated 

frontier of the 1800s. Improved transportation and a higher 

standard of living are making the area more accessible 

for millions of people living well beyond its borders. As 

Missouri progresses toward the social forestry stage, public 

participation will play an increasingly important role in the 

development of forest policies. 

CONCLUSION

The Ozarks’ people were the primary benefactors of the 

lumber boom from 1880 to 1920. Nearly a century later, 

lumbering is still economically important to the region. 

Tourism and other forms of outdoor recreation, however, 

are poised to become the primary drivers of the local 

economies.

Today, Missouri’s forests with pine and oak-pine stands 

cover approximately 600,000 acres (Hahn and Spencer 

1991, Flader 2004). Perhaps the best and most extensive 

pine-bearing lands exist on state and federal ownerships, 

where management over the past 75 years has favored the 

re-establishment or protection of pine. These areas offer 

the best opportunities for creating pine woodlands on a 

landscape scale. 

Pine on private lands in Missouri is often spotty or clumped 

into small, disconnected islands. Oaks and hickories have 

largely replaced most of the historically pine-bearing sites. 

Pine reforestation is critically limited by frequent changes 

in land ownership, lack of landowner knowledge about 

reforestation techniques, lack of pine timber markets, 

and a lack of fi nancial resources available to landowners. 

Until these factors improve, the probability for developing 

landscape-scale pine woodlands on private lands is very 

remote.
7

LITERATURE CITED

Callison, C. 1953. Man and wildlife in Missouri, the 

history of one state’s treatment of its natural resources. 

Harrisburg, PA: The Stackpole Company. 134 p.

Cunningham, R.; Hauser, C. 1989. The decline of the 

Missouri Ozark forest between 1880 and 1920. In: 

Waldrop, T.A., eds. Proceedings, Pine-hardwoods 

mixtures: a symposium on management and ecology 

of the type; 1989 April 18-19; Atlanta, GA: Gen. 

Tech. Rep. SE-58. Asheville, NC: U.S Department 

of Agriculture, Forest Service, Southeastern Forest 

Experiment Station: 34-37. 

Fernow, B. E. 1899. Report upon the forestry investigation 

of the U. S. Department of Agriculture. 1877-1898. 

Washington, DC: [Publisher unknown]. 401 p. 

Flader, S. L. 2004. History of Missouri forests and forest 

conservation. In: Toward sustainability for Missouri 

forests. Gen. Tech. Rep. NC-239. St. Paul, MN: U.S. 

Department of Agriculture, Forest Service, North 

Central Experiment Station. 251 p. 

Folk, J.W. 1909. Address by Joseph W. Folk, Governor of 

Missouri. In: Proceedings of a conference of Governors 

in the White House; 1908 May 13-15; Washington, DC. 

Washington, DC: [Publisher unknown]: 157-161. 

Fuch, J.R. 1978. Oral history interview with Anthony A. 

Buford. Available: http://www.trumanlibrary.org/

oralhist/bufordaa.htm.

Galloway, J.A. 1961. John Barber White: lumberman. 

Columbia, MO. University of Missouri. 267 p. 

Ph.D. dissertation. 

Hammar, C.H. 1935. Institutional aspects of Ozark decline. 

Journal of Forestry. 10(1): 843-850.

Hahn, J.T.; Spencer, J. S. 1991. Timber resources of 

Missouri, statistical report, 1989. Resour. Bull. NC-119. 

St. Paul, MN: U. S. Department of Agriculture, Forest 

Service, North Central Experiment Station. 123 p.

Hill, L.G. 1949. History of the Missouri Lumber and Mining 

Company, 1880-1909. Columbia, MO: University of 

Missouri. 289 p. Ph.D. dissertation. 

Keefe, J.F. 1987. The fi rst 50 years. Jefferson City, MO:

Missouri Department of Conservation. 446 p.

Kimmins, H. 1997. Balancing act. Environmental issues in 

forestry. Vancouver, BC: PBC Press. 305 p.

Liming, F.G. 1945. Natural regeneration of shortleaf pine in 

the Missouri Ozarks. Journal of Forestry. 5(1): 339-345.

Liming, F.G. 1946. The range and distribution of shortleaf 

pine in Missouri. Tech. Pap. No. 106. Columbus, OH. 

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

States Experiment Station. 4 p.

Martin, J.W; Presley, J.J. 1958. Ozark land and lumber 

company: organization and operations: 1887 to 1923. 

Columbia, MO: University of Missouri, School of 

Forestry. 41 p. Unpublished manuscript. 

Rafferty, M.D. 1980. The Ozarks: land and life. Norman, 

OK: University of Oklahoma Press. 368 p. 

Smith, R.C. 1959. Timber in the Ozarks. The Salem Post 

and Democrat – Bulletin. September 4.

Shoemaker, F.C. 1943. Missouri and Missourians: Land 

of contrasts and people of achievements: Volume II. 

Chicago, IL: The Lewis Publishing Company: 587-591. 

The Current Local. 1922. Missouri Forestry Association 

formed at St. Louis. January 5. p 1.

The Ellington Press. 1927. State forester’s report. March 3. 

p 1.

The Ellington Press. 1929. Forestry fi lms shown. November 

14. p 1.

The Ellington Press. 1930. M. O. C. of C. to help obtain 

U. S. Parks. May 1. p 1.

The Ellington Press. 1930. Pine tree seed. September 11. 

p 4.

The Ellington Press. 1933. Interest growing for national 

forest reserve. July 20. p 1.

The Ellington Press. 1933. Government to buy 450,000 

acres of Ozark lands for reserve. August 31. p 1.
8

THE HISTORICAL ECOLOGY OF FIRE, CLIMATE, AND THE DECLINE

 OF SHORTLEAF PINE IN THE MISSOURI OZARKS

Richard P. Guyette, Rose-Marie Muzika, and Steven L. Voelker1

ABSTRACT.—We review studies that have shown reductions in the abundance of shortleaf 

pine (Pinus echinata Mill.) during the last century in the Ozark Highlands. These studies 

indicate that pine abundance is currently 15 to 53 percent of the pine abundance levels before 

major logging activity and fi re suppression, activities dating from the mid- to late 19th century. 

Evidence of pine loss comes from General Land Offi ce notes, the presence of pine remnants, 

and historical documentation that described pine forests. Selective removal of pine, followed 

by intense hardwood competition, reduced shortleaf pine abundance in the Ozarks over the 

past century. In addition, very short fi re intervals (< 3 years) before and after logging reduced 

advanced pine regeneration. More recently (1940-2006), long fi re intervals caused by fi re 

suppression have contributed to a long-term decline in pine abundance. Under continuing fi re 

suppression, vegetation dynamic models predict a decline in abundance that will stabilize in 

about 200 years. Additional, more recent threats to recruitment and maintenance of shortleaf 

pine populations may include global warming-induced insect outbreaks. 

1

Research Professor (RPG), and Associate Professor (RMM), 

Department of Forestry, 203 ABNR, University of Missouri, 

Columbia, MO 65211, and Ph.D. Candidate (SLV), Department of 

Wood Science and Engineering, Oregon State University, Corvallis, 

Oregon 97339. RPG is the corresponding author: to contact call 

(573) 882-7741 or email guyetter@missouri.edu or muzika@

missouri.edu

THE ABUNDANCE AND LOSS 

OF SHORTLEAF PINE

Estimates of shortleaf pine occurrence and loss in Ozark 

forests come from several quantitative and qualitative 

sources, and are best presented in the context of the 

contemporary forest. Among the most recent studies, 

Voelker (2004) measured the diameter and age class 

distribution (Fig. 1) of oak and pine in the Current River 

Hill subsection of Missouri (Nigh and Shroeder 2002), and 

determined their current relative abundance. Shortleaf pine 

has a greater frequency in older age classes due to its greater 

maximum age relative to red oaks. The age class distribution 

of pine on these 1200 randomly chosen plots indicates that 

about 15 percent of the shortleaf pine in this region is over 

90 years in age. Only two studies have evaluated the age 

structure of successional forests of the Ozarks left after 

the exploitation period, both of which were based in single 

stands in order to test silvicultural defi nitions of even-aged 

versus multi-aged forests (Loewenstein and others 2000; 

Shelton and Murphy 1990). It is common knowledge that 

many of the mature oak-pine stands are relatively even 

aged, but knowledge of the actual age distributions across 

the landscape is lacking. 

The most recent forest inventory data indicate that the 

shortleaf pine forest type occurs on approximately 72,000 

hectares or 1 percent of the forested land in Missouri (Moser 

and others 2006). Historically, shortleaf pine was estimated 

to have covered 2.7 million hectares in Missouri (Fletcher 

and McDermott 1957). Using landuse-landcover maps and 

comparing these with General Land Offi ce (GLO) survey 

notes, Hamilton’s (2003) analysis indicated that forests 

with a shortleaf pine component currently occupy about 

36 percent of the landscape that was originally described 

as shortleaf pine forest in the Current and Eleven Point 

rivers region. An estimate by Cunningham and Hauser 

(1989) states that shortleaf pine forest types currently occur 

on approximately 162,000 hectares in Missouri. Despite 

considerable range in data describing current distribution, 

several studies have documented that the abundance of 

shortleaf pine in the Missouri Ozarks has diminished 

(Table 1). Batek and others (1999) quantifi ed GLO note data 

in the Current River watershed of the Missouri Ozarks and 

identifi ed 53 percent of the landscape as having supported 

a shortleaf pine component. Guyette and Dey (1997) 

documented the loss of pine by quantifying long-lasting 

pitch fi lled pine remnants such as stumps, snags and pine 

knots, and comparing that to current overstory composition. 

Additionally, Voelker (2004) found that the red oak group, 

primarily black oak (Quercus velutina) and scarlet oak 

(Q. coccinea) replaced the original shortleaf pine forest in 

the Ozark Highlands as evidenced by current distribution 

patterns of black and scarlet oak relative to occurrence of 

identifi able shortleaf pine remnants. The current diameter 

distribution of overstory shortleaf pines consists of a 

preponderance of small size classes, in contrast with the 

estimated historic distribution of shortleaf pine in the plots 

sampled in the Current River Hills Subsection (Fig. 2).
9

40 50 60 70 80 90 100

0

10

20

30

40

50

60

pine

all oaks

Number of Individuals

Cohort Age

Figure 1.—The age class distribution of pine and upland scarlet and black oaks in the Current River Hill subsection of the Ozark 

Highlands of Missouri (Voelker 2004).

Figure 2.—Current and Historic Diameter Distributions of Shortleaf Pines on MOFEP Site 8. The historic diameter distribution 

was recreated by measuring diameter at root collar of all remaining pine stumps on plots at MOFEP site 8 and converting them 

to DBH from a linear regression model relating diameter at root collar to DBH (Voelker 2004).

15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

30

Relative Frequency (%)

25

20

15

10

5

0

DBH Class (cm)

Historic Pine DBH Current Pine DBH
10

Table 1.—Studies and estimates of shortleaf pine loss in the Missouri Ozarks. The percent of historic condition is the quantity of 

pine or pine forest pre-logginga

 divided by a post-logging quantity times 100. MOFEP 8 is on the Peck Ranch Conservation area 

near Van Buren, Missouri. Integrated moisture index (IMI)b and land use land cover (LULC) present indices of pine abundance.

a

IMI was developed by Iverson and others (1997) and used by Hamilton (2003) to evaluate Ozark shortleaf pine occurrence relative to simulated 

historic occurrence.

b

The historic area of forests with pine is from Liming (1946) and is adjusted from 1.7 million ha by 0.53 (Batek and others 1999) to 2.3 and from 

1 million ha by 0.20 to 194,250 ha and summed. 

c

Estimate is calculated based on approximate scales and areas used in this analysis.

d

VDDT modeling results of percent of landscape with a pine component.

 Percent of

 Current historic

Measure Scale Location Historic and future conditions Source

 Ozark oak Missouri Cunningham and

Area pine forests Ozarks 1.1 million ha2 0.17 million ha 15% Hauser (1989)

Stem density, MOFEP 8 17,143 5,744 Guyette &

no plantations 335 ha SE MO stems ha-1 stems ha-1 34% Dey (1997)

Stem density MOFEP 8 17,381 Guyette &

with plantations 335 ha SE MO stems ha-1 9,239 stems ha-1 53% Dey (1997)

Spatial Oak-pine

occurrence 29,000 km2

 region of MO 47 % (IMI) 9.6 % (LULC) 20%c Hamilton (2003)

 2 ac cut over Reynolds Co.

Wood volume oak-pine forest MO. 11.4 m4 1.5 m3 13% Record (1910)

Predicted % 

of landscape century model Oak-hickory 60% 10% Guyette and

with pine estimated pine forests (with fi re) (with no fi re) 17% others (2004)

 MOFEP 8

Basal area 335 ha ridge tops 2.3 m2 ha-1 0.83 m2 ha-1 35% Voelker (2004)

Mean 22% without plantations

Given all estimates (Table 1), the present abundance of 

shortleaf pine in the Missouri Ozarks is probably between 

20 and 50 percent of the abundance immediately prior to 

the mid 19th century. Much of the accumulated evidence 

suggests that about 50 to 80 percent of Missouri forests 

with a substantial pine component have such a dramatically 

different species composition such that shortleaf pine 

no longer dominates. Moreover, some of the “loss” can 

be attributed to a distinct loss of forested land through 

conversion and shifts in land use. Depending on the 

parameter used, losses of shortleaf pine can be considered 

approximately 15-20 percent of the area once occupied by 

forests dominated by shortleaf pine, while basal area was 

calculated to have been reduced by 35 percent in the past 

150 years.

The reduction in shortleaf pine abundance can be attributed 

hypothetically to the removal of seed source by logging 

and a fi re regime with fi re intervals too frequent for 

optimum pine recruitment. Overall, fi re frequency and 

logging resulted in the removal of seed and advanced 

pine regeneration. For roughly 80 years prior to extensive 

logging of the pine resource (1880 to 1920), very frequent 

fi res occurred in this shortleaf pine-dominated forest type 

of the Ozarks (Mean fi re interval [MFI] < 3 years, Guyette 

and others 2002). The recurrent fi re removed small diameter 

advanced pine regeneration. Logging, especially selective 

pine logging, removed seed sources. Selective pine logging 

in mixed oak pine stands was particularly important in 

favoring succession to hardwoods. Frequent fi re (MFI 

< 3 years) inhibited seedling survival, since a vigorously 
11

conditioned layer of oak root grubs outcompeted pine 

seedlings for light and nutrients. Finally, and more recently, 

fi re suppression has promoted closure of canopy gaps, 

build-up of a deep litter layer, which all but eliminates bare 

mineral soil necessary for epigeous germination of pine 

seeds (Baker 1992, Stambaugh 2001). 

The historic fi re frequency (1880 to 1920), in conjunction 

with xeric sites in higher landscape positions such as upper 

slope or ridges, may have increased the advantage of pines 

once they were in larger diameter classes. Large pines have 

a suite of characteristics that convey advantages over most 

oaks and other hardwoods in the Ozarks. They have thick, 

insulating bark, resistance to rot induced by fi re scars, 

resistance to drought conditions, longer available growing 

season (pines can photosynthesize later in the fall and 

earlier in the spring than deciduous hardwoods in temperate 

climates), and considerable longevity of 250 years or more. 

However, establishment of pine is limited by the proximity 

and timing of seed source as well as the potential seedbed 

conditions (Grano 1949, Lawson 1990, Cain 1991, Shelton 

and Cain 2000, Stambaugh 2001). 

The Infl uence of Site 

on Shortleaf Pine Abundance

In the southeast Missouri Ozarks, Liming (1946), Fletcher 

and McDermott (1957), Batek and others (1999), and 

Voelker (2004) considered soils and bedrock stratigraphy, 

specifi cally residuum over the Roubidoux formation, to be 

the most important factor infl uencing the pre-settlement 

extent of shortleaf pine on the landscape scale. A number 

of mechanisms working at multiple scales, however, can 

select for the success of pines and other tree species at 

any site, i.e., neighborhood effects. Neighborhood effects 

are defi ned here as those infl uences in which the rate or 

probability of change depends on the condition or behavior 

of sites surrounding the site of interest. For example, local 

disturbance history, or the last time a site burned (as well 

as its intensity and magnitude), has a complex interaction 

with prior and present species composition, which in turn is 

infl uenced by edaphic factors. For example, the relation of 

the site on the landscape to elevation, site quality, shape of 

the landform, and local topography all must be considered 

at the appropriate spatial scale. Moreover, the dynamics of 

neighborhood effects, as mediated by the canopy, may be 

signifi cant at a smaller scale. The landscape to elevation 

ratio can be up to 100,000 m2

, whereas the scale of infl uence 

of site quality or local topography could be as small as 10 m2.

Shortleaf pine remnants are the only direct evidence 

indicating the extent of pine dominance in forest structure 

before the exploitation era of logging. Using remnant 

stumps, and estimating the pre-logging relative occupation 

of a site by shortleaf pine, Voelker (2004) found that 

soils derived from the Roubidoux formation have more 

stumps than other geologic strata (Fig. 3), indicating that 

historically this soil-pine relationship was important. 

However, geologic strata are also correlated with slope 

position and elevation, or percent of local relief. The 

Roubidoux was disproportionately associated with upper 

landscape positions (Voelker 2004). At a certain scale 

relative topographic position may infl uence the presence 

of pines due to its relationship with fi re frequency and 

topographic roughness (Guyette and Dey 1997). The 

interrelationship between parent material, topographic 

position, and pine remnants is complex, and cannot be 

easily disentangled.

There is no defi nitive explanation for what constitutes 

a “pine site.” Xeric, exposed conditions on rocky, acid 

soils lead to consistently high evapotranspirative demand 

and water-stress in which shortleaf pine becomes more 

competitive with the hardwoods in the Ozarks. Shortleaf 

pine competes better with oaks on xeric sites, yet it is 

strongly associated with soils of lower base saturation in the 

Missouri Ozarks (Nigh and Schroeder 2002) and appears 

to be found exclusively on sites with acidic soil. Although 

there is no quantitative data clearly show this pattern, 

ecological evidence and strong anecdotal evidence support 

the local and edaphic site association with shortleaf pine in 

the Ozarks.

Radial Variability in Shortleaf Pine Growth

Shortleaf pine growth rates vary greatly in time and space. 

Radial growth rates between trees range widely, from as low 

as 100 rings per 2.5 cm (0.25 mm per year) to higher than 

3 rings per cm (8 mm per year). The oldest, slow-growing 

small trees are found on sandstone outcrops with little soil 

volume while some of the fastest growing shortleaf pines 

grow in deep, acid, and variable depth soils derived from 

sandstone, chert, and igneous bedrocks. The relationship 

30

20

10

0

114

Roub

76

U. Gasc

21

L. Gasc

N =

Geologic Strata

Stumps per Hectare

Figure 3.—The abundance of pine remnants (mean and 

95 percent confi dence intervals) on different geologic strata 

in the Current River Hill subsection. Geologic strata are 

Roubidoux, Upper Gasconade, and Lower Gasconade (from 

Voelker 2004).
12

between the diameter of shortleaf pine and age is strong 

(Voelker 2004), but only for young trees (Fig. 4). For trees 

over 100 years, diameter was not signifi cantly related to 

age (Fig. 5). Additionally, tree-ring width series of shortleaf 

pine often show large abrupt changes in growth within a 

tree. Abrupt, frequent, and persistent growth reductions 

in shortleaf pine growth suggest that these evergreens are 

particularly vulnerable to canopy disturbances, especially 

when tree age is greater than 100 years. Canopy openings 

resulting from fi re, climate, or wind result in radial growth 

declines, and likely mortality. When trees are less than 100 

years, however, canopy openings provide opportunities 

for trees to respond competitively, and radial growth, as 

well as height growth in many cases, increases in response 

to canopy openings of varying sizes, regardless of cause. 

Recruitment and patterns of stand development of shortleaf 

pine, therefore, are strongly infl uenced by dominant cohort 

age and ability to respond to canopy openings. 

Shortleaf Climate Response 

and Climate Change

The relationship between drought and temperature and 

the growth of shortleaf pine has been documented by 

Stambaugh and Guyette (2004). When winter temperatures 

are favorable, evergreen trees such as eastern redcedar and 

shortleaf pine can photosynthesize, and thus demonstrate a 

physiological—and competitive—advantage over deciduous 

trees. With increasing winter temperature, and possibly 

accompanying drying in summers, forest evergreens such 

as shortleaf pine may express a growth advantage. Thus, 

shortleaf pines, unlike many deciduous tree species, may 

be able to compensate for hot dry summers if conditions 

provide for warmer winters with more soil moisture. 

Higher concentrations of atmospheric CO2 are thought 

to have fertilization effects on shortleaf pine, which 

consequently shows an increased growth rate. Although 

deciduous trees may capitalize on increases in CO2 during 

the summer, pines would benefi t from higher CO2 in winter 

as well as summer. Voelker and others (2006) used an 

extensive tree ring data set from the Ozarks to demonstrate 

an increase in pine and oak growth that is hypothesized to 

be the result of putative CO2

 fertilization. This study and 

another (Stambaugh and Guyette 2004) showed increased 

growth rates, especially for younger pines, over the last 

century. These fi ndings have substantial implications for 

tree growth of a younger cohort of shortleaf pine (Fig. 2), 

specifi cally that the growth rates may be increasing. 

Shortleaf Pine Growth and Climate Cycles

The growth of shortleaf pine has been shown to be cyclical 

and related to bi-decadal oscillations in climate (Stambaugh 

and Guyette 2004). This cyclical growth response can 

be further quantifi ed by dating abrupt growth reductions 

in shortleaf pine ring-width series. We used 68 late 

Age (years)

20 40 60 80 100 120 140 160

Diameter (cm)

0

10

20

30

40

50

diameter = -3.54 + 0.292(age)

r

2 = 0.62

Figure 4.—The relationship between tree age and diameter 

for shortleaf pine trees less than about 100 years in age 

(unpublished data, Guyette and Stambaugh).

growth rate = 2.61 -6.48(age)

r

2 = 0.64

Age (years)

100 150 200 250 300 350

Diameter (cm)

30

40

50

60

70

80

Figure 5.—The relationship between tree age and diameter 

for shortleaf pine trees greater than about 100 years in age 

(unpublished data, Guyette and Stambaugh).

successional shortleaf pines from near the Current and Big 

Piney Rivers to examine growth reductions associated with 

climate (Fig. 6). We calculated abrupt growth declines as 

10-year exponentially weighted growth means divided by 

the prior 10-year weighted growth means. Abrupt growth 

reductions in shortleaf pine occurred on a bi-decadal 

frequency (Fig. 6). This cycle is broken by a 35-year hiatus 

in the 300-year-long record of abrupt growth reductions 

circa 1784 to 1820. The most extreme clustering of growth 

reductions usually approximately coincided with extreme 

drought years. Additionally, there were 14 years over the 
13

last 300 years (Fig. 7) in which more than 30 percent of the 

trees had abrupt growth suppressions (> 25 percent growth 

reduction). These years tended to be drought years and 

drought transitions, but winter weather, snow, and early or 

late freezing events may be responsible for some of these 

growth setbacks. 

In the context of stand development of shortleaf-dominated 

forests in the Ozarks, patterns of response to climate likely 

played a signifi cant role. Although we cannot exclude the 

importance of a range of climate effects, there is a strong 

association of development and growth with drought years 

(Guyette and others 2006a). Drought years also co-occur 

with fi res, which may also result in regeneration events 

and recruitment potential. Growth reduction events that 

infl uence the overstory may conincide with development 

events in the understory.

Calendar year

1700 1750 1800 1850 1900 1950 2000

Ring-width reduction (% in 20 year period)

30

40

50

60

70

80

Current River (40 trees)

Big Piney River (28 trees)

1980 1952

1960 1911 1930 1896

1881

1866 1780 1820 1765 1728 1748 1701

1832

1855

Figure 6.—The date and magnitude of ring-width reductions greater than 75 percent at two shortleaf pine sites in the Missouri 

Ozarks. Ring width reductions are calculated as the ring-width mean for 10 years before each date divided by the ring width 

mean after that date (unpublished data, Guyette and others).
14

Calendar year

1650 1700 1750 1800 1850 1900 1950 2000

Percent trees with > 75% growth reductions

0

20

40

60

80

100

1780

1784

1820

1746 1728

1832

1881

1865

1899

1912

1930

1952

1959

1977

Figure 7.—The percent of shortleaf pine trees with abrupt growth declines over the last 350 years (unpublished data, Guyette 

and others).

Dendroecological Inferences 

on Historical Stand Development

The rings of the well preserved wood of shortleaf pine 

have been used to study climate variations, the growth 

response of the species to sites and events, and wildland 

fi res. Thousands of dated fi re scars on shortleaf pine trees, 

cut stumps, and natural snags have led to a detailed, and 

quantitative understanding of Ozark fi re history (Batek 

and others 1999, Guyette and others 2002, Stambaugh and 

others 2005, Guyette and others 2006a). Through the use 

of fi re scars, we have dated fi re occurrence since the 1500s 

in the Missouri Ozarks. Fire scars have been cross-dated 

on the thousands of well preserved pine stumps that have 

survived logging and fi re. These scars, combined with 

those on natural remnants and living pines in the Ozarks, 

have led to a greater understanding of Ozark fi re regimes. 

This knowledge in turn has helped us understand how 

humans, climate, and fi re have interacted to produce the 

contemporary distribution and structure of Ozark oak and 

pine forests (Guyette and others 2002). 

In Missouri, there is dendrochronological evidence for 

both even-aged and mixed-age shortleaf pine regeneration 

(Stambaugh and others 2002). Canopy dominants at two late 

successional, old-growth shortleaf pine forests (Highway 19 

Virgin Pine Forest [HVP] and the Eck Natural Area [ECK]) 

illustrate even-aged and mixed-age regeneration (Fig. 8). A 

historically relevant question may focus on which type of 

regeneration predominated. Data from the ECK site suggest 

that small and large disturbances to the canopy allowed both 

mixed-age and even-aged regeneration, leading to shortleaf 

pine cohorts within a stand. Data from HVP suggest that 

very few events gave rise to regeneration at this site, 

creating essentially an even-aged forest. Both small- and 

large-scale disturbance events were probably important in 

the Ozarks, and there may be no consistent interpretation 

of how ecological site conditions relate to disturbance. The 

HVP and ECK are in similar, albeit not identical, ecological 

landtypes, however the association of Roubidoux strata 

is more evident at ECK. The difference in the effects of 

scale of disturbance may simply relate to fi re interval and 

intensity. Above all, it is important to understand that fi re 
15

contributes to stand initiation through stand replacing events 

and also results in mixed age classes of shortleaf pine 

through small-scale, perhaps surface fi res.

Some support for the role of fi re in shortleaf pine 

recruitment comes from fi re history studies. Evidence 

suggests that the Ozarks had very frequent rotation intervals 

for large-scale fi res (Guyette and others 2006b). Between 

1748 and 1810 fi re scars in Arkansas and Missouri indicate 

that over 310 percent of the landscape burned in 60 years. 

This yields a rotation interval of about 20 years for very 

large fi res that occurred under moderate or severe drought 

conditions. In other words, an area the size of the Ozarks 

(129,500 km2

) burned about every 20 years. Unlike the 

typical characterization of Ozark fi re regimes as having 

frequent low intensity surface fi res, this landscape had 

fi res that occurred over large sections of the Ozarks 

during moderate to extreme drought years. Because of the 

strong association between fi re size and severity, these 

fi res probably caused many small (1 to 10 hectare) standreplacement events in the rough and broken topography of 

the Ozarks. 

Given the large area of the Ozarks under consideration, the 

types of fi res occurring between 1748 and 1810 were highly 

variable and likely dictated by topography as well as climate 

(Guyette and others 2002). The frequency of fi re was in 

part attributable to the discontinuous nature of fuel, varying 

by landform and landscape position. Moreover, a steep, 

highly dissected landscape lends itself to small-scale events 

because fi res are not perpetuated in topographically complex 

areas.

Age class of shortleaf pine dominants

75 95 115 135 155 175 195 215 235 255 275 295 315 335

Frequency of age class

0

2

4

6

8

10

ECK

HVP

Figure 8.—Frequency distribution of pith dates at 1.3 m on 

shortleaf pine canopy dominates at the Eck Conservation 

Area (ECK) (solid bars) and the Highway 19 Virgin Pine 

Natural Area (HVP) (diagonally fi lled bars) (Stambaugh and 

others 2002).

FUTURE ISSUES AND THREATS

The restoration potential for shortleaf pine in part resides 

in selecting the appropriate site and providing necessary 

conditions for regeneration, recruitment, and development 

given the current forest condition. Successional trends in 

extant Ozark forests, even in the absence of management, 

suggest only limited potential for pine regeneration and 

recruitment into the overstory. Following extensive logging 

of the shortleaf pine resource, scarlet oak and black oak 

quickly regenerated many sites. These 90- to 120-year-old 

cohorts of oak have experienced decline since the 1980s, 

supported by ring-width studies from the Missouri Ozarks 

that have shown a pattern of a protracted decrease in 

growth increment, ending in the death of the tree (Dwyer 

et al. 1995, Jenkins and Pallardy 1995, Pederson 1998, 

Voelker 2004). By examining site conditions and shortleaf 

pine remnants, we have established that sites previously 

dominated by shortleaf pine often have the greatest dieback 

and mortality (Voelker 2004, Voelker and others 2007). This 

situation was particularly true on exposed slopes and ridges. 

Characterizing these sites by species composition and 

structure, we found that the successional trends indicate that 

without major disturbance, white oak, not shortleaf pine, 

will gradually replace much of the recent red oak dominance 

within the historic shortleaf pine range in Missouri (Voelker 

and others 2007). 

In recreating historic shortleaf pine distribution using 

remnants, we found that many of the areas with the greatest 

number of shortleaf pine remnants also have the greatest 

amount of shortleaf pine in basal area, although many of 

the individuals are small and may not develop into the 

overstory. Appropriate management of these stands, then, 

can promote existing, developing shortleaf pine. An overall 

directive toward a greater composition of longer-lived, 

drought resistant species, shortleaf pine and white oak, is 

suggested and is already in place on some public lands. A 

specifi c and prerequisite consideration for the regeneration 

and success of shortleaf pine would include prescribed 

burning or some kind of site preparation that disturbs and 

reduces the litter layer (Grano 1949, Stambaugh 2001). 

Increasing the overall vigor of the shortleaf pine and 

shortleaf pine-oak forests of the Ozarks will surely require 

a fl exible combination of even-aged and uneven-aged 

silvicultural techniques for the local site conditions and 

levels of advance regeneration present. Unless silvicultural 

regimes change drastically, shortleaf pine’s inability to 

establish and compete with oaks following cutting, will 

quickly account for its displacement as a signifi cant 

overstory presence in the Ozarks (Stambaugh 2001).

Despite the current presence of scarlet oak and black oak 

in the Ozarks, these oaks historically were probably limited 

by frequent fi re on many sites (Batek and others 1999). It is 

hypothesized, however, that some of the same exogenous 

and endogenous factors (e.g., Armillaria, xeric conditions, 
16

drought, and longevity of pines versus red oaks) which 

selected against oaks in pre-settlement times may also select 

against red oaks currently on pine sites. As an example, 

Bruhn and others (2000) indicated that Armillaria root 

disease is present in almost every case of red oak mortality.

Owing to the relative scarcity of extensive stands of 

shortleaf pine, little is known about pests of shortleaf pine, 

nor has there been much opportunity to examine them in the 

Ozarks. Admittedly, the challenges are greater for restoring 

rather than protecting the shortleaf pine resource. However, 

as shortleaf pine stands develop, it will be critical to 

understand and evaluate the role of biotic challenges to the 

species and forests. Such concerns could include southern 

pine beetle (Dendroctonus frontalis), the most damaging 

insect in eastern pine forests. Southern pine beetle outbreaks 

have increased recently and spread into previously 

uninfested territory, such as the southern Appalachians, 

a phenomenon explained in part by climatic conditions 

(Ungerer and others 1999). Other beetles occurring in 

the Ozarks and for which shortleaf pine serves as a host 

are small southern pine engraver (Ips avulsus) and black 

turpentine beetle (Dendroctonus terebrans). Additional pests 

include insects that target regeneration, e.g., pine webworm 

(Pococera robustella), a defoliating caterpillar known to 

occur in the Ozarks. Annosum root disease (Heterobasidion 

annosum) and littleleaf disease (Phytophthora cinnamomi) 

are persistent diseases of shortleaf pine in the southern 

United States. 

The potential interaction of climate change and insect 

and pest population relative to increasing shortleaf pine 

on the landscape must be considered when managing and 

promoting shortleaf pine. Similarly, the importance of a 

comprehensive understanding of the role of climate in 

determining fi re frequency and severity requires further 

investigation to improve models describing fi re occurrence 

and consequence across the Ozark landscape. 

CONCLUSION

Dendroecological approaches describing shortleaf pine 

growth, climate response, and fi re history provide a longterm perspective on this species’ development, success, 

and sustainability in the Ozarks. We have developed 

an understanding of shortleaf pine life history traits, 

particularly regarding growth and age relationship, and the 

role of fi re in infl uencing stand initiation and development. 

Shortleaf pine trees can live for more than 350 years, but 

such ages are rare. As with most tree species, shortleaf pine 

growth is negatively affected by drought, but unlike other 

deciduous Ozark hardwoods, the growth may be increased 

by winter warming. Shortleaf pine growth can be as little 

as 20 rings per cm or as great as 1 ring per cm. Radial pine 

growth exhibits a 22-year cycle that is tied to drought and 

solar cycles. Although global warming may favor shortleaf 

pine, fi re history in oak-pine forests shows that litter 

accumulation, dense canopies, and hardwood sprouting 

continue to be impediments for recruitment and successful 

regeneration. 

Historic shortleaf pine distribution was associated with 

parent material, fi res, and climate. Parent material, soil 

residuum, and landscape position all seem to play a 

role in explaining historic shortleaf distribution across 

the landscape. We corroborated older fi ndings by close 

examination and analysis of shortleaf pine remnants. An 

extensive size class/age class distribution revealed that most 

contemporary shortleaf pine have developed within the last 

80 years. 

Abundance of shortleaf pine has resulted from large 

drought-driven mixed severity fi res in the Ozarks 

occurring every 10-20 yrs. Both multiple and single cohort 

development of shortleaf pine occurred in the Ozarks. We 

have shown that the remnant late-successional shortleaf pine 

forests in the Missouri Ozarks have developed from a mixed 

disturbance regime. Therefore, a consistent or uniform 

management approach may not satisfactorily reestablish 

shortleaf pine communities. Such fi ndings support earlier 

research such as Brinkman and Liming (1961) and 

Brinkman and Smith (1968).

Shortleaf pine growth setbacks occur frequently in the 

Ozarks, as evidenced by the dendrochronological record 

of radial growth patterns. Climatic conditions, such as 

drought, and canopy opening disturbance, including fi re, 

disease, insects, or windthrow, can infl uence radial growth. 

However, the growth response strongly relates to tree age, 

and a general threshold of about 100 years indicates the 

species age when the tree may either respond positively, 

or be vulnerable to damage or abiotic conditions. This 

vulnerability is expressed by growth losses and an overall 

lack of response occurring in general in trees more than 

100 years old.

Challenges include proper management, restoration of site 

conditions, and re-establishment of missing seed source. 

Although the pine plains supported areas of nearly 100 

percent shortleaf pine, much of the Ozarks supported a 

pre-settlement mixed pine-oak forest, particularly in the 

topographically complex landscape of the river hills and 

breaks. The ecological benefi ts of increased overstory 

diversity in Ozark forests are manifold; therefore, promotion 

of shortleaf pine in oak-dominated landscapes addresses 

concerns of sustainability and ecological integrity. Mixed 

oak-pine forests create a diverse successional, structural, 

and habitat conditions in Ozarks forests. Attributes such as 

canopy cover, wood chemistry and life history help explain 

shortleaf pine’s unique ecological role in oak-pine forests. 

Evergreen canopies provide nesting sites, roosting, and 

primary productivity in the winter and early spring. Toxic 

oleoresins preserve wood and cavities for long periods of 

time relative to other woody debris. Shortleaf pines may be 
17

less susceptible to crown fi res and insect attacks in mixed 

oak-pine stands than in pure pine stands or plantations. 

Shortleaf pine components of oak-hickory-pine forests are 

predicted to diminish without fi re by a coarse-scale, state 

transition model (Guyette et al. 2004). These models are 

validated with Ozark fi re history data (Shlisky and others 

2005) and indicate that without fi re, forests with a shortleaf 

pine component will occupy less than 10 percent of the 

landscape within a few centuries. Thus, in the absence of 

intervention, forests with a shortleaf pine component, which 

once covered more than 53 percent of parts of the Ozark 

landscape (Batek and others 1999) may be confi ned to 

10 percent of the landscapes. Those few sites are characterized by xeric condition and soils with low base saturation. 

The silvicultural and ecological challenges of restoring 

the mixed pine-oak forests require attention, time, and 

evaluation.

ACKNOWLEDGMENT

The authors would like to thank D.C. Dey and M.C. 

Stambaugh for their support and work on numerous 

shortleaf pine projects that have contributed to this work. 

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pine forests of the Ozark highlands. Columbia, MO: 

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growth and climate response of shortleaf pine at the 

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D., et al., eds. Proceedings 14th central hardwoods 

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the pines: a 341-year fi re history of Big Spring, Ozark 

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19

SHORTLEAF PINE COMPOSITION AND STRUCTURE IN THE UNITED STATES

W. Keith Moser, Mark Hansen, William H. McWilliams, and Raymond M. Sheffi eld1

ABSTRACT.—Although shortleaf pine currently occupies a prominent position in many eastern 

forests, particularly on upland sites, many scientists and managers have expressed concern 

about the future of this species in the absence of the disturbance patterns that facilitated its 

establishment up to now. Reductions in timber harvesting and fi re, in particular, may give 

the advantage to competitors such as oaks, sweetgum, and maples. Commercial owners 

have favored the faster-growing loblolly pine over shortleaf pine. Using data from the Forest 

Inventory and Analysis program of the U.S. Forest Service, we looked at current data and 

temporal trends to gauge the trajectory of shortleaf pine forests in the eastern United States. 

The shortleaf pine volume per acre of timberland has decreased over the last two to three 

decades. The shortleaf pine basal area component on forestland has decreased in absolute 

terms and also represents a decreasing proportion of the total basal area, suggesting that 

associated species are increasing in their share of the overstory. The total number of shortleaf 

pine seedlings/saplings in the understory of stands has been decreasing and the proportion 

of all seedlings/saplings that are shortleaf pines has been declining over the last 20 or so 

years. The declining proportion of regeneration represented by shortleaf pine suggests a future 

eastern U.S. forest with substantially reduced proportions of the species in the overstory. 

Reintroducing disturbances, such as fi re, is essential to maintain shortleaf pine’s overstory 

presence and associated biological and economic benefi ts.

1

Research Forester (WKM and MHH), Northern Research Station, 

Forest Inventory and Analysis Program, U.S. Forest Service, 

1992 Folwell Ave., St. Paul, MN 55108; Supervisory Research 

Forester (WMW), Northern Research Station, Forest Inventory and 

Analysis Program, U.S. Forest Service, 200 Campus Blvd, Suite 

200, Newtown Square, PA, 19073; Supervisory Research Forester 

(RMS), Southern Research Station, Forest Inventory and Analysis 

Program, 200 W.T. Weaver Blvd., Asheville, NC, 28804. WKM is 

corresponding author: to contact, call (651) 649-5155 or email at 

wkmoser@fs.fed.us

INTRODUCTION AND METHODS

Southern pines, including shortleaf pine, have had a 

prominent role in eastern U.S. forests for thousands 

of years. While current pine forests evolved through a 

combination of ecological and human-infl uenced factors, 

changes in disturbance patterns are altering both the species 

mix and the structure of the nation’s pineries. Other authors 

at this conference present their interpretation of shortleaf 

pine stand dynamics and infl uences; in this paper, we 

examine trends, status, and implications of the structure and 

composition of shortleaf pine forests in the eastern United 

States.

We examined data from the national Forest Inventory 

and Analysis Program (FIA) of the U.S. Forest Service 

(Frayer and Furnival 1999). The FIA program conducts 

comprehensive forest inventories to estimate the area, 

volume, growth, and removal of forest resources in the 

United States, in addition to taking measurements on the 

health and condition of these resources. The program’s 

sampling design has a base of one plot per approximately 

6,000 acres, which provides a consistent, unbiased sample 

across the entire landscape. The national FIA program 

consists of four regional programs that provide estimates of 

forest area, volume, change, and forest health throughout the 

United States (McRoberts 1999). We used data from two of 

these regional FIA programs—the Northern and Southern 

FIA programs—to depict forest conditions for the eastern 

United States. For historical data, we use data generated 

from past FIA reports for states in the eastern U.S. and data 

generated by the FIA Mapmaker program (Miles 2006). For 

current structure and regeneration, we used data generated 

by the FIA database. The states and inventory dates we used 

in our analysis are listed in Table 1.

Shortleaf pine is found throughout the southeastern quadrant 

of the United States and is the second most important 

southern pine (McWilliams et al. 1986). The species is most 

prevalent in two groups: loblolly-shortleaf pine and oakpine. The loblolly-shortleaf pine forest-type group is the 

predominant forest type group of the southern pine region 

(Walker 2001). As defi ned by the FIA, the two forest-type 

groups included eight detailed types within the oak-pine 

group and eight pine types within the loblolly-shortleaf 

pine group. These groups are defi ned by the proportion of 

total stocking represented by various pine species and their 

associates. The shortleaf pine type is defi ned as forests in 

which pines accounts for at least 50 percent of the stocking 

of all live trees, with shortleaf pine the most common 
20

pine. Mixed pine-hardwood stands are those in which pine 

accounts for 25 to 50 percent of total stocking. Of the major 

forest types in the eastern United States, shortleaf pines are 

common associates of loblolly pine, oaks, hickories, and 

gums. 

RESULTS

Shortleaf pine is found in 22 states and 85 forest-type 

groups. It is most often found in the loblolly-shortleaf 

pine forest-type group, but is also found in such types as 

longleaf-slash pine, pine-oak and several other upland 

hardwood forest types. The latest estimates from each 

of the states in the historic shortleaf pine range add up to 

12.9 billion cubic feet of the species on timberland. 

Shortleaf pine volume has generally decreased across the 

region over time, sometimes at a rapid rate. 

Although the species is present from Pennsylvania to Texas 

and Florida (Fig. 1), it is the most prevalent in the forests of 

Table 1.—FIA statewide inventories used in this study.

 Annual Inventories Periodic Inventories

 Number of Number of Number of

 Timberland Timberland Timberland

State Year Plots Year Plots Year Plots

Alabama 2004 3298 2000 4399 1990 3917

Arkansas 2005 3353 1995 3135 

Florida 2005 1756 1995 5506 1987 5583

Georgia 2004 5209 1997 7045 1989 7522

Illinois 2004 767 1998 1671 1985 1095

Indiana 2005 958 1998 1546 1986 1998

Kansas 2004 374 1994 1676 1981 937

Kentucky 2004 3286 1988 1927 

Louisiana 2005 2443 1991 2413 

Maryland 2004 68 1999 525 1986 653

Mississippi 1994 3185 

Missouri 2004 3706 1989 4673 

New Jersey 2004 56 1999 383 1987 250

North Carolina 2002 3913 1990 5921 1984 5580

Ohio 2004 963 1991 1652 

Oklahoma 1993 1090 

Pennsylvania 2004 3061 1989 2971 

South Carolina 2005 1989 1993 4446 1986 4382

Tennessee 2003 2134 1999 2732 1989 2275

Texas 2005 3066 1992 2056 

Virginia 2003 3151 1992 4399 1984 4432

West Virginia 2004 309 2000 2153 

the south-central states of Arkansas, Oklahoma, Mississippi, 

and Missouri.

The FIA stand-size variable can provide some indication of 

the stages of stand development (Oliver and Larson 1996), 

but the correlation with stand or tree age is less robust, 

because the classifi cation is based solely on tree diameter 

(McWilliams et al. 2002). Each FIA plot has two to three 

“age” trees that are used to develop productivity equations. 

Because only the most dominant overstory trees are 

sampled, the ages may not represent all plot trees, and age 

data will not be considered here. Using the most recent data, 

shortleaf pine timberland area had a stand size distribution 

of 8 percent seedling-sapling, 23 percent poletimber, and 

69 percent sawtimber. The shortleaf pine-oak forest-type 

group had a slightly more balanced stand structure, with 

13 percent of the area in seedling-saplings, 31 percent in 

poletimber, and 56 percent in sawtimber. The predominance 

of larger trees has implications for calculations of growth 

and mortality, as we will see later.
21

Figure 1.—Shortleaf pine as a percentage of total timberland basal area, based on the most recent FIA inventories from 

each state.

Shortleaf Pine Overstory: Status and Trends

Area

Out of approximately 241 million acres of timberland in 

the 22 states of the shortleaf pine range, shortleaf pine and 

shortleaf pine-oak forest types occupy over 7.4 million acres 

(Table 2). Over 4.7 million acres (64 percent) are in largediameter stands and about 738,000 acres (10 percent) are in 

small-diameter stands, with the remaining 2 million acres in 

medium-diameter stands.

Number of trees

Of the 1.9 billion shortleaf pine trees, 791 million, or 

42 percent, are found in the shortleaf pine forest type 

(Table 3). Another 335 million, or 18 percent of all shortleaf 

pine trees, are in the shortleaf pine-oak forest type. Beyond 

these two forest types, shortleaf pine trees do not have a 

prominent presence in any forest type in the United States. 

The fi ve top states, based on number of trees are Arkansas, 

Oklahoma, Mississippi, Alabama, and Georgia (Table 4). 

There are 1.9 billion shortleaf pine trees in the states in the 

species’ range: 785 million are in large-diameter stands, 

685 million in medium-diameter stands and 414 million in 

small-diameter stands. All things being equal, we would 

expect more trees per acre in small-diameter stands than in 

other size classes, so the fact that there are proportionally 

more trees in the large-diameter class reinforces the 

observation that the bulk of shortleaf pine forests are in 

large-diameter stands.
22

Table 2.—Timberland area of shortleaf pine, shortleaf pine-oak, and all forest types in those regions in the eastern United States 

with shortleaf pine forest type, in millions of acres and from the most recent inventory.2

 The most recent inventories for Maryland 

and New Jersey are not complete; completed panels do not list any shortleaf pine volume, so those states were not included in 

calculations. For West Virginia, the 2000 periodic inventory data was used. 

Forest type and region Total Large diameter Medium diameter Small diameter

Shortleaf pine 

Central statesa 218,293 162,375 50,654 5,264

Mid-Atlantic statesb

 7,884 - - 7,884

Atlantic statesc 573,995 341,224 174,667 58,104

Gulf statesd

 3,138,664 2,230,161 686,749 221,754

Total 3,938,836 2,733,760 912,070 293,006

Shortleaf pine-oak 

Central statesa

 382,805 252,923 120,704 9,178

Mid-Atlantic statesb

 106,312 69,046 29,484 7,782

Atlantic statesc 693,560 428,763 171,387 93,410

Gulf statesd 2,315,348 1,239,695 740,687 334,966

Total 3,498,025 1,990,427 1,062,262 445,336

All forest types 

Central statesa 21,974,818 12,978,559 6,872,589 2,031,029

Mid-Atlantic statesb

 16,046,291 9,467,123 4,743,453 1,745,410

Atlantic statesc 97,347,847 44,207,968 27,071,852 24,975,568

Gulf statesd

 105,688,465 48,557,114 30,751,469 25,842,126

Total 241,057,421 115,210,764 69,439,363 54,594,133

Table 3.—Number of shortleaf pine trees by forest type, using the most recent inventories from each state.

 Number of Percent Percent of all

 Growing Stock Trees of all Trees Shortleaf Pine Trees Million

Forest type (millions) in the Type in the Region Acres

Shortleaf pine 791.1 49.4% 42.1% 3.9

Shortleaf pine/oak 335.4 26.7% 17.8% 3.5

Loblolly pine 325.3 1.4% 17.3% 45.6

White oak/red oak/hickory 137.8 1.0% 7.3% 43.0

Loblolly pine/hardwood 63.1 1.1% 3.4% 13.7

Post oak/blackjack oak 41.3 2.1% 2.2% 6.1

Mixed upland hardwoods 39.5 0.6% 2.1% 24.9

Virginia pine 25.3 2.1% 1.3% 2.3

Sweetgum/yellow poplar 17.8 0.7% 0.9% 7.7

White oak 14.6 0.8% 0.8% 5.2

Other types 89.7 0.0% 4.8% 111.7

2

a – Illinois, Indiana, Missouri (Kansas has shortleaf pine volume but no shortleaf pine forest type); b – Pennsylvania (Maryland and New Jersey 

not included due to incomplete inventories); c – Florida, Georgia, Kentucky, North Carolina, South Carolina, Virginia, and West Virginia; 

d – Alabama, Arkansas, Louisiana, Mississippi, Oklahoma, Tennessee, and Texas.
23

Table 4.—Number of shortleaf pine growing stock trees on timberland, by State and stand size class. The most recent 

inventories for Maryland and New Jersey are not complete; completed panels do not list any shortleaf pine volume. For West 

Virginia, the 2000 periodic inventory data was used.

State Total Large diameter Medium diameter Small diameter Nonstocked

Alabama 167,247,530 50,916,318 70,360,118 45,971,094 –

Arkansas 509,819,996 228,566,160 197,829,315 83,424,521 –

Florida 5,941,473 4,193,999 193,772 1,553,702 –

Georgia 141,542,129 63,466,096 51,397,764 26,678,269 –

Illinois 8,582,649 8,300,201 282,448 – –

Indiana 1,297,227 1,258,092 39,135 – –

Kansas 311,943 311,943 – – –

Kentucky 13,220,721 6,846,929 4,057,996 2,315,795 –

Louisiana 33,386,094 24,248,403 3,554,730 5,582,960 –

Mississippi 195,436,442 76,413,093 42,631,002 76,392,347 –

Missouri 134,082,175 69,945,736 49,252,301 14,884,139 –

North Carolina 86,577,023 37,559,019 25,508,996 23,509,008 –

Ohio 135,537 135,537 – – –

Oklahoma 313,421,254 75,708,912 153,153,603 84,558,740 –

Pennsylvania 4,173,670 – 36,719 4,136,952 –

South Carolina 59,302,378 24,593,186 27,251,995 7,457,197 –

Tennessee 32,287,953 18,093,002 11,196,273 2,998,678 –

Texas 127,593,640 71,912,480 26,795,401 28,845,757 40,002

Virginia 43,827,211 19,144,117 20,917,245 3,765,850 –

West Virginia 5,676,645 2,892,416 425,163 2,359,066 –

Total 1,883,863,691 784,505,639 684,883,974 414,434,076 40,002

Volume

Growing stock volume of shortleaf pine in the latest 

inventories was almost 13 billion cubic feet (Table 5). 

Arkansas led the way with 3.4 billion cubic feet, followed 

by Mississippi, Texas, Alabama, and Oklahoma. The state 

with the smallest estimated shortleaf pine volume was 

Pennsylvania with 801 thousand cubic feet. Nationally, 

shortleaf pine volume is much lower compared to historical 

times. Figure 2 displays the nearly universal decline in the 

species’ volume over the last three decades.

Net Growth and Removals

For those states where recent data exist, shortleaf pine 

averaged 428 million cubic feet per year in net growth, 

which is defi ned as gross growth less mortality. This number 

represents less than 4 percent of current volume for those 

states (Table 5). The values ranged from -3.4 percent in 

West Virginia to more than 6 percent in Oklahoma. For the 

states where we have removals data, removals represent 

less than 6 percent of current volume, and ranged from 0 

percent of volume in several states to more than 15 percent 

in Louisiana.

The presence of a particular species is infl uenced not only 

by environmental considerations, but also by how human 

activity impacts the species. Along these lines, a useful 

indicator of shortleaf pine resource dynamics is the net 

growth to removals ratio. Ratios less than 1.0 indicate 

removals exceed growth, while values above 1.0 indicate 

inventory expansion. We examined the latest estimates of 

net volume growth and removal volume for the species. The 

gross growth to removals ratio was 0.58, indicating that our 

estimated removals exceeded the net growth. Among states 

with both positive growth and removals, the ratio ranged 

from 0.23 in Georgia to 4.96 in Missouri.
24

Table 5.—Growing stock volume, mortality, growth and removals, in cubic feet, of shortleaf pine in the eastern United States. 

Data is based on the latest inventory for each state, as of Sept. 1, 2006. Maryland and New Jersey are not listed because these

inventories are only partially completed and completed panels do not list any shortleaf pine volume. For West Virginia, the 2000 

periodic inventory data was used for all estimates. For Virginia, North Carolina, Alabama, South Carolina, Tennessee, Georgia, 

Ohio, and Pennsylvania mortality, growth, and removals estimates were taken from most recent periodic inventories. 

 Total Growing Mortality Growth to

State Stock Volume Mortality Percentage Net Growth Removals Ratio

Alabama 1,098,283,367 26,291,884 2.4 46,197,186 106,398,925 0.43

Arkansas 3,410,072,606 39,214,174 1.1 101,416,898 112,978,627 0.90

Florida 59,225,060 0 0.0 2,982,499 4,818,029 0.62

Georgia 940,083,263 31,900,953 3.4 19,178,706 82,881,734 0.23

Illinois 74,826,427 339,968 0.5 1,787,358 0 --

Indiana 29,960,121 400,852 1.3 748,674 0 --

Kansas 1,889,991 0 0.0 0 0 --

Kentucky 164,265,225 3,685,351 2.2 2,572,188 1,290,085 1.99

Louisiana 371,289,865 4,081,610 1.1 18,133,050 57,278,885 0.32

Mississippi 1,529,628,337 20,996,813 1.4 72,883,929 165,796,601 0.44

Missouri 798,489,530 3,477,856 0.4 25,093,884 5,058,655 4.96

North Carolina 716,936,742 0 0.0 198,984 0 --

Ohio 2,796,283 241,087 8.6 -10,598 17,257 -0.61

Oklahoma 1,019,164,707 2,854,448 0.3 62,573,293 48,419,185 1.29

Pennsylvania 801,685 0 0.0 3,577 0 --

South Carolina 356,902,941 11,228,537 3.1 7,873,755 27,191,035 0.29

Tennessee 437,310,556 8,440,432 1.9 17,588,975 18,070,517 0.97

Texas 1,511,567,329 23,648,948 1.6 45,364,165 88,023,443 0.52

Virginia 351,939,107 7,955,820 2.3 3,971,042 15,794,677 0.25

West Virginia 12,841,996 540,975 4.2 -436,636 0 --

Total 12,888,275,138 185,299,708 1.4 428,120,928 734,017,654 0.58

Status of Proportion of Shortleaf Pine 

in Eastern U.S. Forest Overstory 

As the underlying theme of this paper is “Where is shortleaf 

pine going?”, we examined trends in the percentage of total 

basal area that is in shortleaf pines (Table 6). We looked 

at changes between inventories in the 1980s, 1990s, and 

2000s. All states showed an overall decline during this 

period.

Regeneration is heavily infl uenced by the size and 

composition of the forest overstory (Smith et al. 1996). 

We have seen a declining trend in the proportion of 

total timberland in shortleaf pine overstory, with a few 

exceptions, throughout the eastern United States. Given 

the relative longevity of shortleaf pine, much of the current 

shortleaf pine overstory is likely a refl ection of disturbance 

conditions far in the past. Shortleaf pine regeneration, 

however, should refl ect more recent disturbances. 

Accordingly, we looked at shortleaf pine seedling/sapling 

data from the last one to three inventories in each state to 

gain some insight into the future of shortleaf pine forests 

(Table 6 and Fig. 3).

The eastern U.S. forests are not lacking for tree regeneration 

(Fig. 3). In most states, we have observed the presence of 

shortleaf pine regeneration, although not in large quantities, 

except for Arkansas and Oklahoma. Like overstory 

basal area, shortleaf pine regeneration was also fl at or 

declining over this period. While these numbers do not 

indicate particular areas in the state where regeneration is 

successfully replacing shortleaf pine overstory, the overall 

trends – particularly the smaller proportion of regeneration 

versus overstory basal area – point to a decline in the 

species’ presence in future forests.
25

Growing stock volume (million cu. ft.)

0 1000 2000 3000 4000

State

West Virginia

Virginia

Texas

Tennessee

South Carolina

Pennsylvania

Oklahoma

Ohio

North Carolina

New Jersey

Missouri

Mississippi

Maryland

Louisiana

Kentucky

Kansas

Indiana

Illinois

Georgia

Florida

Arkansas

Alabama

1980s

1990s

2000s

Figure 2.—Shortleaf pine growing stock volume by inventory decade and state. For each state, the bars progress (where data 

exist) from the 1980s on the bottom to 2000s on the top.

Table 6.—Percentage of total basal area in shortleaf pine basal area (“x/”) and shortleaf pine seedlings/saplings as a percentage 

of all seedlings/saplings (“/x”), by state and inventory period. All percentages rounded to nearest whole percent. Percentages 

less than 0.5 percent are shown as “0”.

State 1980s 1990s 2000s State 1980s 1990s 2000s

Alabama 5/2 4/1 Missouri 4/1 5/1

Arkansas 13/4 11/3 New Jersey 1/1 0/0 

Florida 0/0 0/0 0/0 North Carolina 4/1 3/1 2/0

Georgia 4/1 1/0 2/1 Ohio 0/0 0/0

Illinois 1/0 1/0 1/0 Oklahoma 15/9 

Indiana 1/0 1/0 1/0 Pennsylvania 0/0 0/0

Kansas 0/0 0/0 0/0 South Carolina 3/2 2/1

Kentucky 1/1 0/1 Tennessee 3/1 2/0 1/0

Louisiana 3/1 1/0 Texas 10/2 6/1

Maryland 0/0 0/0 Virginia 2/0 2/0 2/0

Mississippi 5/1 West Virginia 0/0 0/0
26

CONCLUSIONS

After reaching a low point in the 1960s and 1970s, 

timberland in the eastern U.S. has recently started to 

increase. Shortleaf pine, however, has been decreasing 

in the number of trees and volume over the last several 

decades. Although we did fi nd shortleaf pine regeneration in 

several states, the proportion was less than shortleaf pine’s 

proportion of overstory basal area. The species is largely 

concentrated in large-diameter stands throughout its range. 

Such stands are likely older; older trees are frequently 

slower growing, which is, in turn, refl ected in turn a smaller 

growth-to-removals ratio.

Johnson et al. (2002) emphasize the importance of 

accumulating oak regeneration in the understory and 

outlines the disturbances, anthropogenic and natural, that 

encourage this accumulation. The same principles apply to 

species such as the southern pines, particular shortleaf pine 

and longleaf pine (Moser 2003). Such disturbances promote 

two processes: the concentration of early growth on the pine 

seedling/sapling root system resulting from dieback of the 

above-ground component, and the elimination of less fi reresistant species that would otherwise compete successfully 

for resources. Two of the most prominent disturbances are 

harvesting and fi re. Increasing urbanization and regulation 

have put pressure on both of these disturbance types. 

Furthermore, where shortleaf pine has been harvested, it has 

frequently been replaced by planted loblolly pine.

The declining proportion of regeneration represented by 

shortleaf pine is particularly disquieting, as it provides a 

foretelling of forest overstory composition. It is hard to 

imagine a future eastern U.S. forest landscape with the 

current proportion of shortleaf pine in the overstory, given 

these regeneration trends. While re-instituting large-scale 

disturbances will pose problems in a settled landscape such 

as the South, they should be considered part of the toolbox 

that resource managers use as they seek to maintain this 

important species.

0

200

400

600

800

1000

All species - saplings per acre

Shortleaf pine - saplings per acre

Trees per Acre

State

Alabama

Arkansas

Florida

Georgia

Illinois

Indiana

Kansas

Kentucky

Louisiana

Mississippi

Missouri

North Carolina

Ohio

Oklahoma

Pennsylvania

South Carolina

Tennessee

Texas

Virginia

West Virginia

Figure 3.—Seedlings and saplings of all species and shortleaf pine, per acre, by state. The most recent inventories for Maryland 

and New Jersey are not complete; completed panels do not list any shortleaf pine volume.
27

LITERATURE CITED

Frayer, W.E.; Furnival, G.M. 1999. Forest survey sampling 

designs: A history. Journal of Forestry. 97(12): 4-10.

Johnson, P.S.; Shifl ey, S.R.; Rogers, R. 2002. The ecology 

and silviculture of oaks. New York: CABI Publishing. 

501 p.

McRoberts, R.E. 1999. Joint annual forest inventory and 

monitoring symposium: the North Central perspective. 

Journal of Forestry. 97(12): 27-31.

McWilliams, W.H.; Sheffi eld, R.M.; Hansen, M.H.; Birch, 

T.W. 1986. The shortleaf resource. In: Proceedings of 

the symposium on the shortleaf pine ecosystem; 1986 

March 31 – April 2; Little Rock, AR. Monticello, AR: 

Arkansas Cooperative Extension Service: 9-24.

McWilliams, W.H.; O’Brien, R.A.; Reese, G.C.; Waddell, 

K.L. 2002. Distribution and abundance of oaks in 

North America. In: McShea, W.J.; Healy, W.H., eds. 

Oak forest ecosystems: ecology and management for 

wildlife. Baltimore: Johns Hopkins Press: 13-32.

Miles, P. D. 2006. Forest inventory mapmaker webapplication version 2.1. St. Paul, MN: U.S. Department 

of Agriculture, Forest Service, North Central Research 

Station. [Online only] Available at: www.ncrs2.fs.fed.

us/4801/fi adb/index.htm

Moser, W.K. 2003. Oaks explained. A book review of 

Ecology and Silviculture of Oaks. Forest Science. 

49(2): 377-378(2).

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

2d ed. New York: John Wiley. 

Walker, L.C. 1995. The southern pine region. In: Barrett, 

J.W., ed. Regional silviculture of the United States. 

New York: John Wiley: 271-334.
28

GENETIC VARIATION IN THE SOUTHERN PINES: 

EVOLUTION, MIGRATION, AND ADAPTATION FOLLOWING THE PLEISTOCENE

Ronald Schmidtling1

ABSTRACT.—Climate has certainly changed over time, requiring genetic change or migration 

of forest tree species. Little is known about the location of the southern pines during the 

Pleistocene glaciation, which ended around 14,000 years ago. Macrofossils of spruce (Picea

spp.) dating from the late Pleistocene, which are typical of climates much cooler than presently 

occupied by the southern pines, have been found within the current range of the southern 

pines, indicating that the climate was considerably colder at that time. From this discovery it 

is reasonable to assume that the southern pines were situated south of their present range 

during the Pleistocene and migrated to their current location after the glaciers receded. 

Variation in adaptive and non-adaptive traits of the southern pines suggests that loblolly 

pine (Pinus taeda) existed in two refugia, one in south Texas/north Mexico, and one in south 

Florida. Longleaf pine (P. palustris) probably existed only in the western refugium. Slash pine 

(P. elliottii), on the other hand, presumably resided only in the Florida refugium, whereas 

shortleaf pine (P. echinata) is cold-hardy enough to have existed in a continuous distribution 

across the Gulf Coast. Implications of climate warming on the future of southern pines are 

discussed.

1

Scientist Emeritus, USDA Forest Service, Southern Institute of 

Forest Genetics, SRS, 23332 Hwy 67, Saucier, MS 39574. Email:

rschmidtling@fs.fed.us

INTRODUCTION

There has been a great deal of discussion about “global 

climate change”. An increase in CO2 in the atmosphere 

since industrialization has been well documented and is 

apparently causing an increase in average temperatures. 

A consensus is developing that global temperatures are on 

the increase. Changes in climate, however, are not new, but 

have occurred many times in geological history.

The most drastic climatic changes during the long history of 

the pines have been relatively recent, during the Pleistocene 

Ice Ages. During the 1.6 million years of the Pleistocene, 

large fl uctuations in temperature resulted in the advance 

and retreat of glaciers with a periodicity of a little more 

than 100,000 years. The interglacial periods were short 

compared to the glaciated periods. The current interglacial 

period, the Holocene, began from 10,000 to 14,000 years 

before present (BP); the last interglacial, the Eemian, from 

130,000 to 107,000 years BP (Critchfi eld 1984). The large 

fl uctuations in climate, which resulted in lengthy migrations, 

undoubtedly affected the population structure of temperate 

forest tree species.

Climate during the height of the last of these glaciations, the 

Wisconsin (c. 18,000 years BP), was colder than at present 

in the southeastern United States. The glaciation extended 

as far south as southern Ohio (40°N), overlapping the 

current northern distribution of the most temperate of the 

southern pines (Fig. 1). The southern pines were certainly 

situated south of their current location. The postulated 

palaeovegetation maps of Delcourt and Delcourt (1981) 

show oak, hickory, southern pine as far north as Tennessee 

(36°N). The maps of Webb et al. (1987), on the other hand, 

show southern pines absent at this time, and appearing 

in south Florida only at 12,000 years BP. Palynological 

evidence is diffi cult to interpret. Not only can pine pollen 

travel large distances, but it may be impossible to identify to 

the species level.

Figure 1.—Map of the Southeastern United States showing 

the current natural distribution of shortleaf and slash pines.
29

Macrofossils (including cones and needles) of boreal 

species, spruce (Picea sp.) and jack pine (Pinus banksiana) 

have been identifi ed from several Wisconsin deposits (c. 

14,000 years BP), one as far south as Louisiana (31°N) 

(Critchfi eld 1984). These locations are within the current 

natural ranges of even the more austral of the southern pines 

(Fig. 2). The current natural range of shortleaf pine (Pinus 

echinata) extends as far north as Ohio and New Jersey, but 

is several hundred kilometers south of the nearest jack pine 

in northern Michigan. Shortleaf pine overlaps the natural 

range of red spruce (Picea rubens) in the Appalachian 

Mountains, but shortleaf pine does not occur above 910 m, 

whereas red spruce does not occur below 1370 m (USDA 

1990). Spruce and shortleaf pine do not currently grow on 

the same sites, but “disharmonious” associations could have 

existed during the Pleistocene (Wright 1989).

GENETIC VARIATION IN 

THE SOUTHERN PINES

Genetic variation in the more commercial southern pines 

is well known, especially for the adaptive traits of growth, 

survival, and pest resistance (summarized in Schmidtling 

2001). The results of common-garden experiments as well 

as allozyme studies are available for shortleaf, longleaf 

(P. palustris), loblolly (P. taeda) and slash (P. elliottii) 

pines. These four species exhibit four different patterns 

of variation. The fi rst three occur on both sides of the 

Mississippi River, but the last occurs only to the east of 

the river. This is an important factor in the evolution of the 

species.

Longleaf Pine

Provenance tests have shown that substantial variation in 

growth, survival, and disease incidence exists in longleaf 

Figure 2.—Post-Pleistocene migration route accounting for 

the variation. Adapted from Schmidtling and Hipkins (1998).

pine (Wells and Wakeley 1970). Growth is generally related 

to latitude or temperature at the seed source (Schmidtling 

and Sluder 1995). Geographic variation in longleaf pine 

parallels that of other forest tree species; seedlings from 

warmer climates grow faster than those from colder 

climates, if they are not transferred to greatly differing 

climates. 

In longleaf pine there are no differences in adaptive traits 

among sources east of the river versus those west of the 

river, after the minimum temperature at the seed source 

is taken into consideration (Schmidtling 1999). Given the 

lack of such differences in adaptive traits, it was surprising 

to fi nd a linear decrease in variability from west to east in 

allozyme diversity (Schmidtling and Hipkins 1998). Sixty 

percent of the variation in expected heterozygosity was 

explained by longitude of the seed source (Fig. 3). 

The most attractive explanation for the observed trend in 

variation is that longleaf pine originated from a single, 

limited refugium in southeast Texas or northeast Mexico, 

resulting in a reduced level of genetic variability as the 

rapidly migrating population was affected by stochastic 

events (Fig. 2).

Loblolly Pine

Like longleaf pine, loblolly pine occurs on both sides of the 

Mississippi River Valley (Fig. 4). Provenance tests have 

shown that substantial geographic variation in growth, 

survival, and disease susceptibility exists in loblolly pine 

(Wells and Wakeley 1966). Growth is generally related 

to latitude or temperature at the seed source (Schmidtling 

1997). Geographic variation parallels that of longleaf pine; 

seedlings from warmer climates grow faster than those from 

colder climates, if they are not transferred to very different 

climates.

Figure 3.—Variation in expected heterozygosity by longitude 

in longleaf pine. Adapted from Schmidtling and Hipkins 

(1998).
30

Although east-west variation in adaptive traits such as 

growth, disease resistance and survival is minimal in 

longleaf pine, it is very important in loblolly pine (Wells 

and Wakeley 1966). In loblolly pine, western sources are 

slower growing, survive better, and have greater resistance 

to fusiform rust (Cronartium quercuum f.sp. fusiforme). 

The isolating effect of the Mississippi River Valley has 

often been cited to explain the east-west differences in 

loblolly pine. Pines do not exist in the Valley, because they 

cannot compete with broadleaved trees in the rich, moist 

alluvial soils where fi re is infrequent. There is also an 

obvious difference in cortical monoterpenes between eastern 

and western populations (Fig. 4). Limonene is especially 

high in western populations (Squillace and Wells 1981). 

Although monoterpene composition is often considered a 

non-adaptive trait, it may function in insect resistance. The 

pattern of high limonene among populations on both sides 

of the Mississippi River appears to indicate there is gene 

exchange across the river, at least in the eastward direction. 

This possibility is supported by the existence of rustresistant populations, common in the west, just east of the 

river (Fig. 4). 

In loblolly pine, there was no east-west trend in allozyme 

variation (Schmidtling et al. 1999) and there appears to be a 

tendency for more variation in the central part of the natural 

range. There are some differences in the occurrence of rare 

alleles among populations. Twenty of the rare alleles were 

detected only in the eastern populations whereas only two 

were found exclusively in the western populations. Nearly 

all the alleles that are found in the western populations can 

be found in the eastern populations, but many of the alleles 

found in the eastern populations were not found in the 

western populations.

One of the alleles of enzyme 6PGD-1 is relatively common 

in many populations of loblolly pine east of the river, 

having a frequency as high as 0.29 in one population in 

Maryland, but is very rare west of the river. The distribution 

of allozyme alleles suggests that gene fl ow in a westerly 

direction across the Mississippi River is restricted. On the 

other hand, the continuous clinal variation in limonene 

content (Squillace and Wells 1981) and fusiform rust 

resistance (Wells et al. 1991) across the Mississippi River 

(Fig. 4) suggests that there is no barrier to gene fl ow in 

the eastern direction across the valley. Prevailing winds 

since the beginning of the Holocene 14,000 years ago are 

primarily in the eastern direction, and are certainly a factor 

in this predominantly one-way gene fl ow. 

Some interesting similarities exist between all populations 

of longleaf pine and western populations of loblolly pine. 

Like western populations of loblolly pine, longleaf pine 

is resistant to fusiform rust and much less susceptible to 

tip moth and southern pine beetle (Snyder et al. 1977), 

although the mechanisms probably differ. These similarities 

suggests that western loblolly populations and all longleaf 

populations shared an environment at some time in the past 

where selection for resistance to these pests was important. 

The proposal that longleaf pine and western sources of 

loblolly pine both originated in a common refugium in south 

Texas/northeast Mexico fi ts the circumstantial evidence. The 

present climate in south Texas is too dry for Australes pines, 

but was probably much wetter during the Pleistocene (Watts 

1983). Other pines occur just south of the border in Mexico, 

at high elevations (Critchfi eld and Little 1966).

The lack of a trend in allozymes in loblolly pine, coupled 

with the distinct east versus west variation in fusiform rust 

resistance and other adaptive traits suggests that loblolly 

pine was located in two refugia during the Pleistocene 

(Fig. 4), in Texas/Mexico and Florida/Caribbean as 

proposed by Wells et al. (1991). Using the genetic distances 

from the allozyme data of Schmidtling et al. (1999), I have 

calculated a divergence time of 97,000 years between the 

western and eastern sources, which is a good approximation 

of the time since the last interglacial period, the Eemian, in 

this region.

Shortleaf Pine

Shortleaf pine has the most temperate distribution of the 

major commercial southern pines, extending into Ohio and 

New Jersey to the north, and barely reaching into north 

Florida in the south (Fig. 1). Like longleaf and loblolly 

pines, shortleaf pines occur on both sides of the Mississippi 

River. 

Like longleaf pine, provenance tests have shown that 

substantial variation in growth, survival, and disease 

Figure 4.—Current natural distribution of loblolly pine 

showing the frequency of trees with high cortical limonene 

content. Also shown are the proposed Pleistocene refugia 

and migration routes.
31

incidence exists in shortleaf pine (Wells and Wakeley 1970). 

Growth is generally related to latitude or temperature at the 

seed source (Schmidtling 1995). As with longleaf pine, there 

is no east/west variation in adaptive traits in shortleaf pine.

Unlike longleaf pine, there is no east/west trend in allozyme 

variability (Raja et al. 1997, Edwards and Hamrick 1995). 

There is no trend consistent with a relatively fast migration 

from a restricted refugium. The relative cold-hardiness of 

shortleaf pine may have made such a migration unnecessary. 

It is here proposed that shortleaf pine had a more-or-less 

continuous distribution across the Gulf of Mexico, on the 

exposed continental shelf (Fig. 5). 

Slash Pine

A number of the Australes pines occur only east of the 

Mississippi River Valley, including slash pine, pond pine 

(Pinus serotina), table mountain pine (P. pungens), pitch 

pine (P. rigida) and spruce pine (P. glabra). Slash pine is 

the most austral of the major southern pines and occurs 

mainly in Florida (Fig. 1). Slash pine has obvious affi nities 

to P. caribaea of the Bahamas and Cuba, and before 1954 

they were considered the same species (Little and Dorman 

1954, Farjon and Styles 1997). There is clinal variation in 

many adaptive traits in slash pine in a north-south direction 

(Squillace 1966). It seems logical to assume that slash pine 

existed in a refugium in south Florida, the Bahamas, or 

Cuba, and migrated north after the retreat of the glaciers, 

approaching but not able to cross the Mississippi River 

against the prevailing winds. The expected decrease in 

variability in allozymes from south to north along the 

putative migration route has been documented (Schmidtling 

and Hipkins 2000).

The other southern pines with eastern distributions probably 

resided in refugia in north Florida to North Carolina (Fig. 5). 

Table mountain pine may be an exception. This pine exists 

at high elevations in the Appalachian Mountains and may 

simply have moved to a lower elevation.

THE FUTURE

Consensus is developing that global temperatures are 

on the rise, because of the human-induced increase in 

“greenhouse” gasses such as CO2. During past climatic 

changes, forest trees, as well as other organisms, have been 

able to migrate to areas of favorable climate, or to change 

genetically through natural selection. Evolution is not static 

but is a constantly ongoing process.

Climate has been warmer in the past, such as during the 

Hypsithermal era, about 5,500 years BP. Climate has also 

been colder, e.g., “the Little Ice Age” in medieval times. The 

changes that have been projected by many climatic models, 

however, will be very fast, perhaps too fast for these natural 

processes to occur (Davis 1990). 

Figure 5.—Proposed location of the major southern pines 

during the Wisconsin Glaciation.

The southern pines have a great deal of genetic plasticity 

as is evident in the South Wide Southern Pine Seed Source 

Study (Schmidtling 2001). In this study, it is common for 

even very poorly adapted sources to live past 35 years (and 

reproductive maturity) albeit growing very slowly. Even this 

great plasticity may not be enough.

At some point foresters and other biologists may have 

to intervene in the process to mitigate the effects of this 

human-induced change. In this case, gene conservation 

would become very important.

CONCLUSIONS

In spite of the relative uniformity of the Coastal Plain of the 

southeastern United States, important genetic differences 

exist among the southern pine species in response to the 

last glaciation. Longleaf pine resided in a southwestern 

refugium and slash pine in a Florida refugium. Loblolly 

pine resided in both refugia, the two populations being 

isolated genetically. Shortleaf pine probably resided in a 

continuous population across the exposed continental shelf. 

The many advances and retreats of glaciation during the 

Pleistocene undoubtedly had profound effects on variation 

and speciation in the southern pines. 

LITERATURE CITED

Critchfi eld, W.B.; Little, E.L., Jr. 1966. Geographic 

distribution of the pines of the World. Misc. Pub. 991. 

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

Forest Service.

Davis, M.B. 1990. Climate change and the survival of forest 

species. In: Woodell, G.M., ed. The earth in transition: 

patterns and processes of biotic impoverishment. 

Cambridge, UK: Cambridge University Press: 99-110.
32

Delcourt, P.A. and Delcourt, H.A. 1981. Vegetation maps 

for eastern North America: 40,000 yr BP to the present. 

In: Romans, R.C., ed. Geobotany II. New York: Plenum 

Press: 123-165.

Edwards, M.A.; Hamrick, J.L. 1995. Genetic variation in 

shortleaf pine, Pinus echinata Mill. (Pinaceae). Forest 

Genetics. 2: 21-28.

Farjon, A. and Styles, B.T. 1977. Pinus (Pinaceae). Flora 

Neotropica Monograph 75. Bronx, NY: New York 

Botanical Garden.

Little, E.L., Jr.; Dorman, K.W. 1954. Slash pine (Pinus 

elliottii), including south Florida slash pine. 

Nomenclature and description. Pap. 36. Asheville, 

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

Southeastern Forest Experiment Station.

Raja, R.G.; Tauer, C.G.; Wittwer, R.W.; Huang, Y. 1997. 

Isozyme variation in natural populations of shortleaf 

pine (Pinus echinata). Canadian Journal of Forest 

Research. 27: 740-749. 

Schmidtling, R.C. 1995. Seed transfer and genecology in 

shortleaf pine. In: Edwards, M.B., comp. Proceedings, 

8th biennial southern silviculture conference; 1994 

November; Auburn, AL. Gen. Tech. Rep. SRS-1. 

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

Service, Southern Research Station: 373-378.

Schmidtling, R.C. 1997. Using provenance tests to predict 

response to climatic change. In: Cheremisinoff, P.N., 

ed. Ecological issues and environmental impact 

assessment. Houston, TX: Gulf Publishing Co.: 

621-642.

Schmidtling, R.C. 1999. Genetics of longleaf pine. In: 

Kush, J.S., comp. Proceedings, 2nd longleaf alliance 

conference; 1998 November; Charleston, SC. Rep. 

No. 4. Andalusia, AL: Solon Dixon Forestry Education 

Center: 24-26.

Schmidtling, R.C. 2001. Southern pine seed sources. Gen. 

Tech. Rep. SRS-44. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research Station. 

Schmidtling, R.C.; Carroll, E.; LaFarge, T. 1999. Allozyme 

diversity of selected and natural loblolly pine 

populations. Silvae Genetica. 48: 35-45.

Schmidtling, R.C.; Hipkins, V. 1998. Genetic diversity 

in longleaf pine (Pinus palustris Mill.): Infl uence of 

historical and prehistorical events. Canadian Journal of 

Forest Research. 28: 1135-1145. 

Schmidtling, R.C.; Hipkins, V. 2000. Evolutionary 

relationships of slash pine (Pinus elliottii) with its 

temperate and tropical relatives. South African Forest. 

J.190: 73-78.

Schmidtling, R.C.; Sluder, E.R. 1995. Seed transfer and 

genecology in longleaf pine. In: Weir, Robert J.; 

Hatcher, Alice V., comps. Proceedings of the 23rd 

southern forest tree improvement conference; 1995 

June 20-22; Asheville, NC. Publication No. 45 of the 

Southern Forest Tree Improvement Committee: 78-85.

Snyder, E.B.; Dinus, R.J.; Derr, H.J. 1977. Genetics of 

longleaf pine. Res. Pap. WO-33. Washington, DC: U.S. 

Department of Agriculture, Forest Service.

Squillace, A.E. 1966. Geographic variation in slash pine 

(Pinus elliottii Engelm.). Forest Science Monographs. 

10.

Squillace, A.E.; Wells, O.O. 1981. Geographic variation 

of monoterpenes in cortical oleoresin of loblolly pine. 

Silvae Genetica. 30: 127-135.

Burns, R.M.; Honkala, B.H. tech. coords. Silvics of North 

America. Volume 1. Conifers. Agric. Hndbk. 654. 

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

Forest Service.

Watts, W.A. 1983. A vegetational history of the eastern 

United States 25,000 to 10,000 years ago. In: Porter, 

S.C., ed. The late Pleistocene. Vol. I. Late-quaternary 

environments of the United States. Minneapolis, MN: 

University of Minnesota Press; 294-310.

Webb, T., III; Bartlein, P.J.; Kutzbach, J.E. 1987. Climatic 

changes in eastern North America during the past 

18,000 years; comparisons of pollen data with 

model results. Geology of North America Vol. K-3, 

North America and Adjacent Oceans during the Last 

Deglaciation. Geological Society of America: 447-462.

Wells, O.O.; Switzer, G.L.; Schmidtling, R.C. 1991. 

Geographic variation in Mississippi loblolly pine and 

sweetgum. Silvae Genetica. 40: 105-119.

Wells, O.O.; Wakeley, P.C. 1966. Geographic variation in 

survival, growth, and fusiform rust infection of planted 

loblolly pine. Forest Science Monographs. 11.

Wells, O.O.; Wakeley, P.C. 1970. Variation in shortleaf pine 

from several geographic sources. Forest Science. 16: 

415-423.

Wright, H.E., Jr. 1989. The Quaternary. In: A.W. Bally, 

A.W.; A.R. Palmer, A.R., eds. The Geology of North 

America, Vol. A. An Overview. Boulder, CO: Geologic 

Society of America: 513-536. 
33

FOREST STAND DYNAMICS OF SHORTLEAF PINE IN THE OZARKS

David R. Larsen1

1

Department of Forestry, 203 Natural Resources Building, University 

of Missouri, Columbia, MO 65211. To contact call (573) 882-4775 or 

email larsendr@missouri.edu

EXTENDED ABSTRACT

Forest stand dynamics (Oliver and Larson 1996) examines 

the interactions among woody plants over time. Both the 

silvical requirements of the species present in the forest 

stand and the effects of these plants on each other must be 

understood. The components that are usually considered 

are regeneration, growth (in both diameter and height), 

mortality, and differences in species’ tolerance of shade, 

fi re, and drought. In addition, disturbance tends to shift the 

competitive advantage from one species to another.

Shortleaf pine has many interesting silvical characteristics 

(Burns and Honkala 1990) that distinguish it from the other 

southern pines. It is the most vigorous sprouter, it has the 

most northern range of the southern pines and it seems 

to occupy the marginal sites for southern pines (Record 

1910, Liming 1946, Fletcher and McDermont 1957, 

Dingle and Burns 1954, Nash 1963). The reasons for these 

characteristics are many and but they tend to give shortleaf 

pine a reputation as a slow growing southern pine. Shortleaf 

pine actually has the potential to grow very well given a 

good site and proper levels of composition (Gingrich et al. 

1965, Rogers and Brinkman 1965, Brinkman and Rogers 

1967, Rogers 1982, Rogers and Sanders 1984).

Much has been written on the management of shortleaf 

pine in the Ozarks (Brinkman et al. 1965, Brinkman 1967, 

Brinkman and Smith 1968, Seidel and Rogers 1965, Seidel 

and Rogers 1966). In large portions of the Ozarks, shortleaf 

pine does not grow in pure stands but rather in mixes with 

various oak species. These mixes present unique challenges 

in fi nding the set of conditions that allow both species to 

survive and fl ourish. The author will comment on ideas of 

how these systems research and current work being done to 

quantify these ideas. 

LITERATURE CITED

Brinkman, K.A.; Rogers, N.F.; Gingrich, S.F. 1965. 

Shortleaf pine in Missouri, stand density affects yield. 

Res. Pap. CS-14. Columbus, OH: U.S. Department 

of Agriculture, Forest Service, Central States Forest 

Experiment Station. 14 p.

Brinkman, K.A. 1967. Stand volume equations for shortleaf 

pine in Missouri. Res. Note 24. St. Paul, MN: U.S. 

Department of Agriculture, Forest Service, North 

Central Forest Experimental Station. 4 p.

Brinkman K.A.; Rogers, N.F. 1967. Timber management 

guide for shortleaf pine and oak-pine types in Missouri. 

Res. Pap. NC-19. St. Paul, MN: U.S. Department of 

Agriculture, Forest Service, North Central Forest 

Experiment Station. 15 p.

Brinkman, K.A.; Smith, R.C. 1968. Managing shortleaf pine 

in Missouri. Stn. Bull. 875. Columbia, MO: University 

of Missouri, College of Agriculture, Agricultural 

Experiment Station. 35 p.

Burns, R.M.; Honkala, B.H. 1990. Silvics of North America: 

Volume 1. Conifers. Agric. Hndbk. 654. Washington, 

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

675 p.

Dingle, R.W.; Burns, P.Y. 1954. Relationship of shortleaf 

pine growth to soil properties. Stn. Bull. 541. Columbia, 

MO: University of Missouri, College of Agriculture, 

Agricultural Experiment Station. 11 p.

Fletcher, P.W.; McDermott, R.E. 1957. Infl uence of 

geologic parent material and climate on distribution of 

shortleaf pine in Missouri. Res. Bull. 625. Columbia, 

MO: University of Missouri, College of Agriculture, 

Agricultural Experiment Station. 43 p.

Gingrich, S.F.; Brinkman, K.A.; Rogers, N.F. 1965. 

Shortleaf pine in Missouri, two methods of thinning. 

Research Paper CS-16. Columbus, OH: U.S. 

Department of Agriculture, Forest Service, Central 

States Forest Experiment Station. 9 p.

Liming, F.G. 1946. The range and distribution of shortleaf 

pine in Missouri. Tech. Pap. 106, Columbus, OH: U.S. 

Department of Agriculture, Forest Service, Central 

States Forest Experiment Station. 3 p.

Nash, A. 1963. A method of classifying shortleaf pine sites 

in Missouri. Res. Bull. 824. Columbia, MO: University 

of Missouri, College of Agriculture, Agricultural 

Experiment Station. 53 p.

Oliver, C.D.; Larson, B.C. 1996. Forest Stand Dynamics. 

New York: John Wiley and Sons, Inc. 520 p. 
34

Record, S.J. 1910. Forest Conditions of the Ozark region 

of Missouri. Res. Bull. 89. Columbia, MO: University 

of Missouri, College of Agriculture, Agricultural 

Experiment Station. 280 p.

Rogers, R. 1982. Guides for thinning shortleaf pine. In: 

Proceedings of the 2nd southern silvicultural research 

conference; 1981 November 4-5; Atlanta, GA. Gen. 

Tech. Rep. SE-24. Asheville, NC: U.S. Department 

of Agriculture, Forest Service, Southeastern Forest 

Experiment Station: 217-225.

Rogers, R.; Sanders, I.L. 1984. Intermediate thinning in a 

Missouri shortleaf pine stand: A 30 year history. In: 

Proceedings of the 2nd southern silvicultural research 

conference; 1981 November 4-5; Atlanta, GA. Gen. 

Tech. Rep. SE-24. Asheville, NC: U.S. Department 

of Agriculture, Forest Service, Southeastern Forest 

Experiment Station: 217-226.

Rogers, N.F.; Brinkman, K.A. 1965. Shortleaf pine in 

Missouri, understory hardwoods retard growth. 

Research Paper CS-15. Columbus, OH: U.S. 

Department of Agriculture, Forest Service, Central 

States Forest Experiment Station. 9 p.

Seidel, K.W.; Rogers, N.F. 1966. Shortleaf pine seedling 

inventory methods on broadcast-seeded areas in the 

Missouri Ozarks. Res. Note -19. St. Paul, MN: U.S. 

Department of Agriculture, Forest Service, North 

Central Forest Experiment Station. 2 p.

Seidel, K.W.; Rogers, N.F. 1965. Seeding shortleaf pine in 

the Missouri Ozarks. Res. Pap. CS-21. Columbus, OH: 

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

States Forest Experiment Station. 12 p.
35

THE IMPORTANCE OF SHORTLEAF PINE FOR WILDLIFE AND DIVERSITY 

IN MIXED OAK-PINE FORESTS AND IN PINE-GRASSLAND WOODLANDS

Ronald E. Masters1

ABSTRACT.—Shortleaf pine, by virtue of its wide distribution and occurrence in many forest 

types in eastern North America, is an important species that provides high habitat value for 

many wildlife species. Shortleaf pine functions as a structural habitat element in both mixed 

oak-pine forests and in pine-grassland woodlands. It also adds diversity throughout all stages 

of plant succession and stand development. Within the range of shortleaf pine, wildlife species 

are variously associated with shortleaf based on stand density, the proportion of hardwoods 

within a structural stage of development, and availability of habitat structure within the specifi c 

niche that each wildlife species occupies. Shortleaf also is a key species in ecosystems 

where it occurs naturally because its occurrence and relative dominance are defi ned to a 

large extent by the natural disturbance regime, particularly fi re. Fire frequency and season, 

to some extent, defi ne the understory plant community response and determine shortleaf 

pine’s potential for regeneration, establishment of future codominant and dominant trees, 

and perpetuate a relative mix of pines with other associated tree species within a stand. This 

understory community response to fi re or lack of fi re defi nes much of the ground-dwelling or 

ground-foraging wildlife species populations. This paper discusses wildlife species associated 

with different structural characteristics and fi re regime in mixed oak-shortleaf and shortleafdominated forests and woodlands.

1

Director of Research (REM), Tall Timbers Research Station, 

13093 Henry Beadel Drive, Tallahassee, FL 32312. REM is 

corresponding author: to contact call (850) 893-4153 or email at 

rmasters@ttrs.org

INTRODUCTION

The oak-pine (Quercus-Pinus) forest type is the largest 

cover type in the eastern United States (Lotan and others 

1978). In this area, shortleaf pine (Pinus echinata Mill.) 

is the most prevalent of the southern pines (Lawson and 

Kitchens 1983) and is associated with a wide array of other 

pines and hardwoods. It occurs in some 18 different cover 

types and is dominant in three of these (Eyre 1980). Its 

wide distribution and occurrence across many forest types 

make shortleaf pine of great value to associated wildlife 

species (Wigley 1986). Shortleaf also is a key species in 

ecosystems because its occurrence and relative dominance 

are defi ned by the natural disturbance regime, particularly 

fi re (Masters and others 2003, 2005), which also infl uences 

the distribution and abundance of associated wildlife 

(Masters 1991a).

Shortleaf pine stands develop naturally as even- or unevenaged stands, depending on the nature of the disturbance 

regime that initiated the stand and/or the periodic 

disturbance events that occurred throughout the life of the 

stand (Turner 1935, Bragg 2002, Masters and others 2005). 

Stands that initiate following catastrophic disturbance or 

as small old-fi eld stands typically develop as even-aged 

stands (Turner 1935, Oosting 1942). If reoccurring fi re is 

part of the disturbance regime, however, the stands will 

develop an uneven-aged structure (Masters and others 

2005). As shortleaf pine ages, it becomes less tolerant of 

shade and neighboring crowns. By age 50 the crowns of 

trees develop an irregular shape and the canopy is often 

punctuated by numerous gaps (Mattoon 1915). Depending 

on the biophysical site conditions and fi re frequency, oaks 

(Quercus spp.) and other hardwoods may vary in abundance 

based on their fi re tolerance and site adaptability. 

Stand structure in old-growth shortleaf has been reported as 

uneven-aged to even-aged and variable in density according 

to the frequency and nature of the disturbance pulse (Turner 

1935, Bragg 2002) and also the scale of consideration. 

These forests typically had numerous canopy gaps and an 

open stand structure, depending on site conditions and fi re 

regime (Little 1946, Fryar 1991, Murphy and Nowacki 

1997, White and Lloyd 1998, Bragg 2002, Stambaugh 

and others 2002). However, in old-growth stands where 

anthropogenic disturbance are excluded, canopy-dominant 

old-growth pines eventually reach senescence and become 

prone to attack by various bark beetles, causing them to 

die and allowing midstory hardwoods to supplant pine in a 

relatively short period of time (Kreiter 1994, Masters and 

others 1995, Cain and Shelton 1996). In these senescing 

stands, shortleaf pine regeneration may occur as even-aged 

patches under large canopy gaps, or in several distinct size 

classes of different cohorts, or as individuals (Bragg 2002, 
36

Stambaugh and others 2002, Cassidy 2004). Given enough 

time, mixed oak-pine stands will assume an uneven-aged 

structure with periodic canopy gaps whether initiated in an 

even-aged or uneven-aged fashion. 

The range of structural conditions and successional states 

found in stands containing shortleaf pine provides a variety 

of niches for wildlife. A number of review papers have dealt 

with the infl uence of southern pine management and wildlife 

(e.g., Dickson 1982, Buckner 1982, Owen 1984) but only 

one specifi cally with shortleaf pine and wildlife (Wigley 

1986). For brevity, this paper will focus primarily on habitat 

relations of small mammals, selected other mammals, and 

birds in mixed oak-pine and pine-grassland habitats. 

FOREST SUCCESSION AND WILDLIFE 

HABITAT RELATIONSHIPS

Shortleaf pine either in pure stands or mixed oak-pine stands 

provides habitat for a large number of wildlife species from 

early seral stages through late seral stages. With progressive 

stand development and changes in stand structure comes a 

commensurate succession of wildlife species (Johnson and 

others 1974). Because some species are habitat specialists, 

some habitat generalists, and the remainder somewhere in 

between, structure (vertical and horizontal) and composition 

of a given stand will determine which species will be found 

there. Stand confi guration, size, and the juxtaposition of 

stand ages and stand structures within a given landscape 

matrix also infl uence the occurrence of some wildlife 

species. Earlier literature refers to within-stand diversity, 

between-stand diversity, and landscape diversity (e.g., 

Wigley 1986). The presence of canopy gaps and the mix of 

oaks and other hardwoods in the canopy or in the midstory 

also provide suitable habitat for certain wildlife.

Early Succession

Following a disturbance event that takes a given stand back 

to an early seral stage, a fairly predictable chronosequence 

of vegetation replacement occurs (Johnston and Odum 1956, 

Meyers and Johnson 1978, Masters 1991a,b, Masters and 

others 2006). On old-fi eld lands or following regeneration 

clear-cutting, the fi rst stage is represented by herbaceous 

vegetation with an array of grasses and forbs. If the stand 

was clearcut and the site prepared for planting, the fi rst 

stage may have considerable bare ground. Within 2 years of 

the clearcut, herbaceous vegetation will dominate the site 

and some woody component will have developed (Masters 

1991a,b, Masters and others 2006). Soft mast production, 

important for many mammals and birds, typically has 

recovered by the third growing season and is more abundant 

than in mature mixed pine-hardwood stands (Perry and 

others 2004). Herbaceous and woody current annual growth 

will increase until canopy closure, generally within 6-8 

years (Fenwood and others 1984, Masters and others 1993, 

2006). The forage and browse production will be from 10 

to 25 times greater than that in mature oak-pine stands over 

this short period of time (Masters and others 2006). Within 

4 to 6 years woody vegetation begins to assert dominance 

as a distinct grass-shrub stage (Johnston and Odum 1956, 

Masters and others 2006). Then after 8 to 10 years a 

distinct sapling stage occurs. The replacement sequence 

and relative dominance of woody species can be redirected 

by subsequent disturbances such as fi re (Masters 1991a, 

Masters and others 2005, 2006). 

The chronosequence of mammals and birds that follow 

the stages of vegetation replacement are also somewhat 

predictable and fairly well documented except for mesomammals and herpitofauna. From the fi rst herbaceousdominated stages, small mammals quickly colonize as cover 

develops (Atkeson and Johnson 1979, Thill and others 

2004), and eastern cotton-tailed rabbit2

, white-tailed deer, 

and elk begin using the site (Masters 1991a,b, Masters 

and others 1997) (Fig. 1). Flying squirrel (Taulman and 

Smith 2004), gray squirrel, and fox squirrel, however, 

show dramatic declines compared to those in mature stands 

in these earliest sere stages (Flyger and Gates 1982). 

Nonetheless, squirrels of all three species have been noted 

to forage in early seral openings (Flyger and Gates 1982, 

Taulman and Smith 2004). Mammalian predators also are 

attracted to these sites (Wigley 1986). These groups of 

species continue to use these habitats through the shrub 

stage and into the sapling stage. By the fi fth growing season, 

though, small mammal density (Thill and others 2004) and 

squirrel use declines dramatically (Flyger and Gates 1982). 

Sapling stands provide benefi cial escape and bedding cover 

and browse for white-tailed deer and elk in naturally- or 

artifi cially-regenerated stands, but cottontail use declines 

(Masters 1991a,b, Masters and others 1993, 1997). Deer 

and elk also preferentially use pine saplings over hardwood 

saplings as territorial marking sites or antler rubbing sites 

during the rut. When high stem densities develop, use by 

either species will decline rapidly with canopy closure 

where fi re is excluded (Masters 1991a,b; Masters and others 

1997). As crowns begin to close, herbaceous vegetation 

declines (Masters and others 1993), as do small mammal 

richness and density (Atkeson and Johnson 1979). By age 

10 and at crown closure, rabbit, elk, and deer dramatically 

curtail use of either naturally-regenerated or clearcut stands 

(Masters and others 1997). Use of these stands is extended 

when prescribed fi re is introduced early and at least on a 

3-year late-dormant season cycle (Masters and others 1997) 

(Fig. 2). Prescribed fi re reduces the density of small (< 6.5 

ft) woody stems (Sparks and others 1999) and maintains 

herbaceous understory production at high levels (Masters 

and others 1993, 1996). 

2

Animal species common names and scientifi c names with authority 

are found in the Appendix.
37

Figure 1.—Plant succession and mammal community succession model of selected common species 

occurrence associated with different stages of succession in the absence of fi re. Horizontal lines indicate 

only the presence of the named species at a particular successional stage. Based on Atkeson and 

Johnson (1979), Tappe and others (1994, 2004), Masters and others (1998, 2002).

Figure 2.—Plant succession and mammal community succession model of selected common species 

occurrence associated with different stages of succession with frequent fi re of at least 1- to 5-year 

intervals. Horizontal lines indicate only the presence of the named species at a particular successional 

stage. Based on Masters and others (1998, 2002).
38

From the earliest stages of secondary succession (bare 

ground), mourning dove begin using such sites. When the 

herbaceous stage is extended, such as in old fi eld situations 

or in some clearcuts, eastern meadowlark, fi eld sparrow, 

and grasshopper sparrow have been reported to use this 

stage (Johnston and Odum 1956, Meyers and Johnson 1978, 

Dickson and others 1993). Other early-succession bird 

species such as northern bobwhite, northern cardinal, indigo 

bunting, blue grosbeak, and, less frequently, Bachman’s 

sparrow make some use of the grass-shrub stage found 

in regenerated stands as long as adequate ground cover 

and fairly dense brushy woody plants are present (Fig. 3). 

Eastern bluebird will use these sites where suitable snags are 

found. Where ground cover is predominantly needle litter in 

dense sapling- to post-sized stands, species such as prairie 

warbler and hooded warbler have been noted (Jennelle 

2000). Periodic burning on at least a 3-year rotation in 

young sapling stands extends the period of use by earlysere wildlife species, such as numerous small mammals, 

bobwhite, wild turkey, and numerous songbirds, which will 

continue to use the stands as they develop (Masters 1991a, 

Stewart 1999, Jennelle 2000, Walsh 2004) (Fig. 4). 

Mid-Succession

The mid-succession stage occurs from about 12 to 60 years 

of age. A common characteristic in stands where fi res have 

been excluded are closed canopies with sparse patches of 

relatively few herbaceous plants in the understory (Oosting 

1942, Meyers and Johnson 1978, Masters and others 2006). 

Stand density varies throughout this age span, but dense 

stands generally decline in density over time as competitioninduced mortality takes place. Lower density stands will fi ll 

in during the early part of this stage, becoming more dense 

for a short period. But in either case, density will be similar 

by the later part of this successional stage (Oosting 1942). 

Once a mixed oak-shortleaf or shortleaf stand enters the 

post-size class (4-6 inches, diameter at breast height), use 

by many wildlife species will decline dramatically, as will 

density, especially in dense stands where fi re is excluded. 

By age 15, stands support low numbers of small mammals 

(Atkeson and Johnson 1979). By age 18-20 fl ying squirrels 

begin using these developing mixed stands (Landers and 

Crawford 1995). Only during the latter part of this stage will 

signifi cant numbers of fox or gray squirrels begin using the 

stand, at which time they may be more abundant than in late 

seral stages (Flyger and Gates 1982).

At age 12-15, depending on the site index, some songbird 

species more characteristic of later stages of succession 

will once again begin using the canopies of shortleaf 

stands as well as stands of other southern pine species 

(Engstrom and others 1984, Jennelle 2000). Species such 

as the red-eyed vireo, hooded warbler, and wood thrush 

become increasingly common, but ground-dwelling and 

-nesting species and some shrub-associated species decline 

(Engstrom and others 1984, Landers and Crawford 1995). 

The importance of fi re in retaining early sere wildlife 

species was recently shown in a study on the Ouachita 

National Forest, AR, that examined northern bobwhite use 

of even-aged stands 12-15 years of age. Following only 

3-4 seasons of fi re exclusion, the northern bobwhite began 

avoiding stands that ranged from 600-700 stems/acre and 

that previously had showed extensive use (Walsh 2004).

In stands from about age 25 to 60, low densities of 

breeding birds characterize most dense southern pine 

forests (Johnston and Odum 1956). However, a host of 

songbirds uses the canopies of pole-sized stands and to a 

much greater extent the understory where frequent fi re is 

used and lower stand density (<70 ft2/ac) is maintained 

(Fig. 4). The songbird species complement in pole stands is 

similar to mature stands (Wilson and others 1995, Jennelle 

2000, Masters and others 2002). In mid-succession stands 

excluded from fi re, both species richness and density of 

small mammals and songbirds decline markedly as midstory 

hardwoods develop and as the herbaceous layer declines 

from litter buildup and shading by hardwoods (Engstrom 

and others 1984, Landers and Crawford 1995, Masters and 

others 2002). 

Late Succession

Late seral stage mixed oak-pine stands may be characterized 

by an uneven-aged diameter distribution, sparse herbaceous 

understory, and considerable horizontal and vertical 

structure (Meyers and Johnson 1978, Kreiter 1994, Smith 

and others 1997). Often the canopy may have periodic gaps 

of different sizes. A snag component is evident. 

Small mammal community density, species richness, and 

diversity are typically lower and composition somewhat 

different than in early seral stages (Tappe and others 1994, 

Masters and others 1998, 2002). Southern fl ying squirrel is 

considered to be a small mammal representative of mature 

mixed oak-pine forests (Taulman and Thill 1994), as are fox 

and gray squirrels, depending on the mix of oaks and other 

hardwoods (Flyger and Gates 1982).

Ovenbird, scarlet tanager, summer tanager, great-crested 

fl ycatcher, Acadian fl ycatcher, tufted titmouse, Carolina 

chickadee, Kentucky warbler, pine warbler, worm-eating 

warbler yellow-billed cuckoo, Northern cardinal, pileated 

woodpecker, hairy woodpecker, downy woodpecker, 

chuck-will’s widow, whip-poor-will, wood thrush, tufted 

titmouse, Carolina wren, broad-winged hawk, red-eyed 

vireo, and possibly yellow-throated vireo are characteristic 

species of late succession mixed hardwood-pine hardwood 

stands (Johnston and Odum 1956, Meyers and Johnson 

1978, Wilson and others 1995, Masters and others 2002). 

However, many of these are also characteristic of mature 

hardwood stands (Meyers and Johnson 1978). There is a 

paucity of conifer-specialized bird species in the southern 

forests compared with northern forests (Johnston and Odum 

1956).
39

Figure 3.—Plant succession and breeding bird community succession model of selected common species 

occurrence associated with different stages of succession in the absence of fi re. Horizontal lines indicate only 

the presence of the named species at a particular successional stage. Based on Johnston and Odum (1956), 

Meyers and Johnson (1978), Wilson and others (1995), Jennelle (2000), and Masters and others (2002).

Figure 4.—Plant succession and breeding bird community succession model of selected common species 

occurrence associated with different stages of succession with frequent fi re of at least 1- to 5-year intervals. 

Most of the bird species from Figure 3 will be found here as well if even 15 ft2

 of hardwood basal area per 

acre is present in the stand. Horizontal lines indicate only the presence of the named species at a particular 

successional stage. Based on Wilson and others (1995), Jennelle (2000), and Masters and others (2002).
40

Figure 5.—Response of cotton mouse, cotton rat, and 

golden mouse to different fi re frequencies on the Stoddard 

fi re plots (three replications of 0.5-acre units), Tall Timbers 

Research Station, Tallahassee, FL. These pine-grassland 

stands were dominated by mature (>100 years) old-fi eld 

derived shortleaf and loblolly and in the sub-canopy a 

mixture of oaks and other hardwoods of varying prevalence 

depending on fi re frequency. From Masters (2002), 

L. Perkins, Jr., Tall Timbers Research Station (unpublished 

data).

Pine-bluestem

In ecosystems where natural disturbance processes, 

particularly frequent fi re, are allowed to freely operate, 

old-growth stands may be characterized by open canopy 

(basal areas less than 70 ft2

/ac), pure or nearly pure pine 

stands with limited midstory, and a bluestem-dominated 

understory (See Vogl 1972, Komarek 1974, Fryar 1991, 

Masters and others 1995, Sparks and Masters 1996, Batek 

and others 1999). Oaks and other hardwoods may be present 

to varying degrees depending on site characteristics (Vogl 

1972, Fryar 1991, Kreiter 1994, Masters and others 1995). 

The understory is rich in grass and forb species with grasses 

assuming a dominant aspect following repeated cycles of 

fi re (Masters and others 1996, Sparks and others 1998). A 

distinct woody component will be present but suppressed, 

depending upon the time since last burned and the intensity 

of the fi re (Sparks and others 1999, 2002). With increasing 

time since last burned, understory woody stems gradually 

grow into the lower midstory (Masters and others 2002).

Mature shortleaf pine-bluestem stands with abundant 

herbaceous ground cover and little to no hardwood 

midstory, managed with late-dormant season fi re at 3-year 

intervals, show dramatic increases in both richness and 

density of small mammals and songbirds (Wilson and others 

1995, Masters and others 1998, 2001, 2002). Low basal 

area pine-bluestem stands managed with frequent fi re also 

provide more than adequate high-quality forage for whitetailed deer and elk (Masters 1991a, Masters and others 

1993, 1996, 1997) and are used to a greater extent by both 

species than unburned closed-canopy sites (Masters 1991b, 

Masters and others 1997). Historically, bison and elk likely 

occurred throughout much of the range of the shortleaf 

pine-bluestem type (Smith and Neal 1991). Masters and 

others (1997) found that elk and white-tailed deer were able 

to persist together in areas endemic for the meningeal worm 

(Parelaphostrongylus tenuis) when over 21 percent of an 

area was in early successional openings. The meningeal 

worm can cause signifi cant mortality in elk. In this system 

fi re may have been particularly important for elk to persist 

because fi re in woodlands causes mortality to woodland 

snails that may be the intermediate host to the meningeal 

worm. This hypothesis needs to be tested.

The entire small mammal community is benefi ted by this 

system of management. Both small mammal richness and 

total captures increase in response to thinning and fi re, 

particularly following the fi rst growing season (Masters and 

others 1998, 2001). In those studies, no part of the small 

mammal community was disadvantaged by restoration 

treatments to shortleaf pine-bluestems stands (Masters 

and others 1998, 2002). Exceptions might be the southern 

fl ying squirrel, gray squirrel, and fox squirrel, species which 

those studies did not examine. The most prevalent species 

in restored pine-bluestem stands included white-footed 

mouse and short-tailed shrew. Other species that increased 

in abundance as well but not signifi cantly included the wood 

rat and cotton rat. The cotton mouse and deer mouse were 

found only in restoration treatments (Masters and others 

2002). But perhaps the species that benefi ted the most were 

specialists such as the fulvous harvest mouse and the golden 

mouse (Masters and others 1998). In a pine-grassland 

community, the fi re frequency also infl uences the structure 

of the understory and thus the small mammal community. If 

fi res are very frequent, the cotton mouse and golden mouse 

are disadvantaged, but the cotton rat is distinctly benefi ted 

by frequent fi re (Fig. 5). The golden mouse was more 

prevalent on 3- to 7-year fi re intervals and the cotton mouse 

tolerated a wide range of frequencies from 2-12 years. The 

understory woody structure of each of the burn intervals is 

different, with more frequent fi re causing lower height and 

less percent cover, while less frequent fi re intervals allows 

greater height development and fuller canopies with greater 

percent cover. Small mammal and breeding bird response is 

strongly associated with this change (Masters 2002, Masters 

and others 2002).

At least 10 species of breeding birds are considered pinegrassland obligates and are benefi ted by pine-bluestem 

management (Wilson and others 1995, Conner and others 

2002, Cram and others 2002, Masters and others 2002). 

This group of birds has declined more precipitously than 

any other group of songbirds in eastern North America 

(Jackson 1988). This group includes red-cockaded 

woodpecker, red-headed woodpecker, brown headed 

nuthatch, northern bobwhite, prairie warbler, pine warbler, 

Bachman’s sparrow, chipping sparrow, eastern woodpewee, and indigo bunting (see Wilson and others 1995, 

Cram and others 2002, Masters and others 2002). Other 

0

1

2

3

4

5

6

7

8

Total Captures

1 2 3 4 5 7 9 12

Golden mouse

Cotton rat

Cotton mouse

Burn Interval (yrs)
41

species that have been noted to increase to some extent 

with pine-grassland management include the great-crested 

fl ycatcher, Acadian fl ycatcher, brown-headed cowbird, 

ruby-throated hummingbird, summer tanager, red-eyed 

vireo, yellow-throated vireo, white-breasted nuthatch, 

yellow-billed cuckoo, blue-gray gnatcatcher, hairy 

woodpecker and downy woodpecker (Masters and others 

2002). Of note is the fact that these birds have in many 

cases been considered inhabitants of mixed oak-pine stands 

and hardwood stands. Their presence is likely related to 

retention of oaks and other hardwoods within pine-bluestem 

managed areas and associated hardwoods along ephemeral 

drainages within stands (Masters and others 2002). Size, 

composition, and juxtaposition of surrounding stands, as 

well as size of the stand that has been restored infl uence 

the species abundances found within restored stands. These 

characteristics are important for species that locally are 

sensitive to habitat condition, as has been found true of the 

Northern bobwhite quail (Cram and others 2002).

In pine-bluestem stands, there is a rapid successional 

progression of bird species not considered to be pinegrassland obligates that are associated with increasing 

height of lower-midstory hardwoods and pine depending 

on the duration since the last burn (Masters and others 

2002). Following three or more growing seasons after 

burning, species such as the indigo bunting, yellow-breasted 

chat, common yellow throat, Northern cardinal, and blue 

grosbeak use the shrubs that develop in the lower midstory. 

However, other species like the chipping sparrow, Northern 

bobwhite, prairie warbler, and Eastern wood pewee will 

decline with increased woody cover in the lower midstory 

(Wilson and others 1995, Masters and others 2002). The 

importance of fi re in maintaining suitable habitat structure 

was well illustrated in a recent study by Walsh (2004) in 

which Northern bobwhite avoided early seral stands and 

mature stands when they had not been burned for 3 to 5 

years. These fi ndings may also apply to the total small 

mammal community. A salient point is that the understory 

structure of pine woodlands and forests largely determines 

the composition of the bird community (Johnston and Odum 

1956) and of the small mammal community. Desirable 

woodland and forest structure can be altered or maintained 

naturally by periodic fi re (Masters and others 2002).

Snag retention has been named as a potential problem 

in frequently burned woodlands. Snags are essential for 

primary- and secondary-cavity nesting songbirds (e.g., 

red-headed woodpecker and eastern bluebird, respectively) 

(Masters and others 2002) and for southern fl ying squirrels 

(Taulman and Smith 2004). Periodic low-intensity fi re 

can be of benefi t in creating future snags, but fi re under 

extended dry conditions will consume snags. Burning when 

snags have high moisture content (>25 percent) (Scott and 

Burgan 2005) or when the Keetch-Byram Drought Index 

(KBDI) is low will prevent consumption.

With fi re exclusion and the resultant development of a 

hardwood mid- to upper midstory the pine-grassland 

obligate species will cease to use the stands (Wilson and 

others 1995, Masters and others 2002). Species related to 

a midstory hardwood presence such as the red-eyed vireo, 

black and white warbler, summer tanager, scarlet tanager, 

Acadian fl ycatcher, ovenbird, and worm-eating warbler 

become more prevalent. Midstory hardwood development 

has been directly associated with cavity tree abandonment 

by red-cockaded woodpeckers and subsequent population 

declines (Masters and others 1989, Jackson and others 

1986). 

As a food resource, shortleaf pine seed is an important and 

preferred food source for northern bobwhite (R.E. Masters, 

Tall Timbers Research Station, unpublished data) and for 

numerous small mammals (Stephenson and others 1963), 

including fl ying squirrels, fox squirrels, and gray squirrels 

as well as numerous ground-feeding song birds (Martin and 

others 1951). Shortleaf pine seed production in the southern 

Ozarks and in the Ouachita Mountains may be characterized 

as a “boom” or “bust” phenomenon with about one-third 

of the seed crops considered either good or bumper seed 

crops (Shelton and Wittwer 1996). Extensive consumption 

of shortleaf seed by many songbirds and small mammals 

has been reported as a hindrance to suitable seedling 

establishment from either natural seed fall or direct seeding 

of sites (Lawson 1990). 

SUMMARY AND CONCLUSIONS

Although no wildlife species specifi cally requires shortleaf 

pine as a habitat element, a number of wildlife species do 

require a pine component to their habitats. Because of its 

distribution and abundance, shortleaf pine provides this 

structural and compositional element over a large area. As 

such, shortleaf pine satisfi es habitat requirements for many 

breeding songbirds and is an important cover component 

and food resource for many songbird and mammal species. 

Only the pine warbler, brown-headed nuthatch and redcockaded woodpecker require a pine species, but not 

specifi cally shortleaf. Within the range of shortleaf pine, 

wildlife species are variously associated with shortleaf pine 

based on the structural stage of stand development and 

the specifi c niche that a given wildlife species occupies. 

Specifi cally, stand density and thus understory conditions, 

and the proportion of hardwoods within a stand strongly 

infl uence the distribution and abundance of wildlife species 

associated with shortleaf at a given seral stage.

Fire frequency and season, to some extent, defi ne the 

understory plant community response and determine 

shortleaf pine’s potential for regeneration, establishment, 

and perpetuation within a given stand and the relative 

mix with other associated tree species. This understory 

community response to fi re or lack of fi re defi nes the 
42

response of many of the ground-dwelling or groundforaging wildlife species. However, a number of wildlife 

species are associated with the fi re regime that corresponds 

to the occurrence of shortleaf pine, especially to the 

understory structure which varies with frequency of fi re. 

This association is particularly true for pine-grassland 

obligate songbirds, and numerous small mammals.

ACKNOWLEDGMENTS

I wish to acknowledge the support, fi nancial and otherwise, 

of many organizations that have funded much of the 

research cited in this paper, including Tall Timbers Research 

Station, Oklahoma State University, Oklahoma Department 

of Wildlife Conservation, Oklahoma Forestry Services, and 

the U.S. Forest Service. I am especially grateful to the team 

of graduate students, wildlife biologists, range scientists, 

and foresters who have been partners in the fi eld on many of 

these projects and have enlivened my research experience 

and broadened my thinking. I am grateful to Kaye Gainey, 

who developed the graphics in Figures 1-4 and for helpful 

reviews by J. Cox, and K. Robertson and two anonymous 

reviewers.

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44

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45

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Wildlife Management. 59: 56-67.
46

Common Name Scientifi c Name (authority)

Birds

Acadian Flycatcher Empidonax virescens (Vieillot)

American Crow Corvus brachyrhynchos (Brehm)

American Goldfi nch Carduelis tristis (Linnaeus)

American Kestrel Falco sparverius (Linnaeus)

American Redstart Setophaga ruticilla (Linnaeus)

Bachman’s Sparrow Aimophila aestivalis (Lichtenstein)

Black and White Warbler Mniotilta varia (Linnaeus)

Blue Grosbeak Guiraca caerulea (Linnaeus)

Blue Jay Cyanocitta cristata (Linnaeus)

Blue-gray Gnatcatcher Polioptila caerulea (Linnaeus)

Broad-winged Hawk Buteo platypterus (Vieillot)

Brown Thrasher Toxostoma rufum (Linnaeus)

Brown-headed Cowbird Molothrus ater (Boddaert)

Brown-headed Nuthatch Sitta pusilla (Latham)

Carolina Chickadee Poecile carolinensis (Audubon)

Carolina Wren Thryothorus ludovicianus (Latham)

Chipping Sparrow Spizella passerina (Bechstein)

Common Flicker Colaptes auratus (Linnaeus)

Common Yellowthroat Geothlypis trichas (Linnaeus)

Cooper’s Hawk Accipiter cooperii (Bonaparte)

Downy Woodpecker Picoides pubescens (Linnaeus)

Eastern Bluebird Sialia sialis (Linnaeus)

Eastern Wood Pewee Contopus virens (Linnaeus)

Field Sparrow Spizella pusilla (Wilson)

Great-crested Flycatcher Myiarchus crinitus (Linnaeus)

Great-horned Owl Bubo virginianus (Gmelin)

Hairy Woodpecker Picoides villosus (Linnaeus)

Hooded Warbler Wilsonia citrina (Boddaert)

Indigo Bunting Passerina cyanea (Linnaeus)

Kentucky Warbler Oporornis formosus (Wilson)

Mourning Dove Zenaida macroura (Linnaeus)

Northern Bobwhite Colinus virginianus (Linnaeus)

Northern Cardinal Cardinalis cardinalis (Linnaeus)

Northern Parula Parula americana (Linnaeus)

Ovenbird Seiurus aurocapillus (Linnaeus)

Pileated Woodpecker Dryocopus pileatus (Linnaeus)

Pine Warbler Dendroica pinus (Wilson)

Prairie Warbler Dendroica discolor (Vieillot)

Common Name Scientifi c Name (authority)

Birds (continued)

Red-bellied Woodpecker Melanerpes carolinus (Linnaeus)

Red-cockaded Woodpecker Picoides borealis (Vieillot)

Red-eyed Vireo Vireo olivaceus (Linnaeus)

Red-headed Woodpecker Melanerpes erythrocephalus (Linnaeus)

Ruby-throated Hummingbird Archilochus colubris (Linnaeus)

Scarlet Tanager Piranga olivacea (Gmelin)

Summer Tanager Piranga rubra (Linnaeus)

Tufted Titmouse Baeolophus bicolor (Linnaeus)

Whip-poor-will Caprimulgus vociferous (Wilson)

White-breasted Nuthatch Sitta carolinensis (Latham)

White-eyed Vireo Vireo griseus (Boddaert)

Wild Turkey Meleagris gallopavo (Linnaeus)

Wood Thrush Hylocichla mustelina (Gmelin)

Worm-eating Warbler Helmitheros vermivorus (Gmelin)

Yellow-billed Cuckoo Coccyzus americanus (Linnaeus)

Yellow-breasted Chat Icteria virens (Linnaeus)

Yellow-throated Vireo Vireo fl avifrons (Vieillot)

Small Mammals

Cotton Mouse Peromyscus gossypinus (LeConte)

Deer Mouse Peromyscus maniculatus (Wagner)

Eastern Woodrat Neotoma fl oridana (Ord)

Fulvous Harvest Mouse Reithrodontomys fulvescens (Allen)

Golden Mouse Ochrotomys nutalli (Harlan)

Hispid Cotton Rat Sigmodon hispidus (Say and Ord)

House Mouse Mus musculus (Linnaeus)

Pine Vole Microtus pinetorum (LeConte)

Southern Short-tailed Shrew Blarina carolinensis (Bachman)

White-footed Mouse Peromyscus leucopus (Rafi nesque)

Other Mammals

Bison Bison bison (Linnaeus)

Eastern cotton-tailed rabbit Sylvilagus fl oridanus (Allen)

Elk Cervus elaphus (Linnaeus)

Fox squirrel Sciurus niger (Linnaeus)

Gray squirrel Sciurus carolinensis (Gmelin)

Southern fl ying squirrel Glaucomys volans (Linnaeus)

White-Tailed deer Odocoileus virginianus (Zimmermann)

Appendix.—List of common and scientifi c names of bird and mammal species mentioned in the text and fi gures.
47

RESTORATION AND MANAGEMENT OF SHORTLEAF PINE 

IN PURE AND MIXED STANDS—SCIENCE, EMPIRICAL OBSERVATION, 

AND THE WISHFUL APPLICATION OF GENERALITIES

James M. Guldin1

ABSTRACT.—Shortleaf pine (Pinus echinata Mill.) is the only naturally-occurring pine 

distributed throughout the Ozark-Ouachita Highlands. Once dominant on south-facing and 

ridgetop stands and important in mixed stands, it is now restricted to south- and southwestfacing slopes in the Ouachita and southern Ozark Mountains, and to isolated pure and mixed 

stands in the northern Ozarks. Its position as a minority component in mixed stands has 

declined to the status of relict. Restoration and management of shortleaf pine fall into three 

categories—science, empirical observation, and wishful application of generalities. In science, 

knowledge exists about regenerating pure stands of shortleaf pine through plantation forestry 

or natural regeneration, about managing second-growth stands to restore pine-bluestem 

communities, and about applying growth and yield models for pure stands of the species. 

Empirically, evidence suggests that relying on advance growth rather than seedfall will 

better regenerate shortleaf pine naturally over time, in conjunction with prescribed burning. 

Generalities become more wishful when considering the use of herbicides to supplement 

fi re, and when thinking about effective ways to underplant a minor and varying shortleaf pine 

component in hardwood stands so as to recover the dramatically depleted area of oak-pine 

woodlands—the omitted step in restoring this species fully in the Ozark-Ouachita Highlands.

1

Supervisory Ecologist and Project Leader, Southern Research 

Station, USDA Forest Service, 607 Reserve Street, Hot Springs AR 

71902. To contact, call 501-623-1180 ext. 103 or email at jguldin@

fs.fed.us

INTRODUCTION

Shortleaf pine (Pinus echinata Mill.) is the most widely 

distributed and least well understood of the four major 

southern pines. The natural range of shortleaf pine 

encompasses 22 states from New York to Texas, second 

only to eastern white pine in the eastern United States (Little 

1971). It is a species of minor and varying occurrence in 

most of these States, and is usually found in association 

with other pines. But in the Ouachita Mountains of 

western Arkansas and eastern Oklahoma, and in the 

Boston Mountains and Springfi eld Plateau of the Ozark 

Mountains in northern Arkansas and southern Missouri, it 

is the only naturally-occurring pine. Here, shortleaf pine, 

pine-hardwood, and hardwood-pine stands once covered 

extensive areas. 

Pine-dominated stands were and still are common in the 

Ouachitas. The folding and faulting of these heavily-eroded 

mountains date to late Paleozoic origin. The main axis of 

the Ouachitas runs east to west, which creates broad Ushaped valleys, long ridges, and hillside slopes dominated 

by northern and southern aspects. Site productivity is 

generally correlated with topographic position and colluvial 

pedogenesis, such that the ridgetops are the poorer sites 

and the lower slopes and valleys the better sites. The 

ridgetops and south-facing slopes in particular feature 

xeric conditions promoted by thin rocky soils and a high 

level of incident solar radiation, which favor microclimatic 

conditions under which the establishment and development 

of shortleaf pine is favored. Anthropogenic activity prior to 

European settlement kept fi re on the landscape in a regular 

way. Periodic fi re promoted shortleaf pine, perhaps at the 

expense of other pines, through shortleaf pine’s adaptation 

of sprouting if the stem is killed or cut, a trait noted early on 

as an adaptation to surface fi res (Mattoon 1915). Nowhere 

in the natural range of shortleaf pine does the species so 

dominate a landscape, and especially the stands on ridgetops 

and south-facing slopes within the landscape, as in the 

Ouachitas. 

But shortleaf pine was also a dominant pine on the Ozark 

Plateau. Unlike the Ouachitas, the Ozarks are an uplifted 

calcareous plateau that has weathered over time into a 

landform that features benches underlain by resistant rocks 

at varying elevations. Due to vagaries of weathering and 

the distribution of underlying geology, slope aspect is 

distributed around all points of the compass. Site quality 

in the Ozarks is dependent on soil depth, which can vary 

considerably by slope position, depending on the presence 

or absence of these benches at differing elevations. As a 

result, site conditions are far more heterogeneous in the 

Ozarks than the Ouachitas. The Ozarks have many varied 

aspects rather than a few. Uniform site conditions are 
48

featured in a much smaller area, and where the best sites 

on a hillside might be on a bench toward the upper end 

of the slope. These conditions are suited to a pine that is 

very much a generalist, which is more the typical pattern 

of shortleaf pine throughout its natural range. Again, under 

the actions of drought and fi re, shortleaf pine undoubtedly 

was and is found in pure stands in the Ozarks, but these 

stands are less contiguous than in the Ouachitas. Moreover, 

shortleaf probably existed as a varying majority or minority 

component in mixture with hardwoods across the Ozarks, 

depending on site conditions and disturbance history.

For those interested in the ecological restoration of shortleaf 

pine, a key question concerns restoring the mixed pinehardwood and especially the hardwood-pine stands where 

shortleaf was found. The heyday of lumbering in the Interior 

Highlands was highlighted by high-grading shortleaf pine. 

The Missouri Mining and Lumber Company operated 

shortleaf pine mills at Grandin, MO, from 1888 to 1909 and 

cut about 75 million board feet (bf) annually (Flader 2004). 

Roughly speaking, that mill alone cut from 1.2 to1.5 billion 

bf from southern Missouri—a volume exceeding one-third 

of the standing sawlog volume in the shortleaf-loblolly pine 

species group in the Missouri Ozarks today (Miles 2006). 

That quantity speaks to a ruthless high-grading of shortleaf 

pine throughout the southern part of Missouri. Operationally 

speaking, this pine harvest could not have been taken simply 

from pure stands. Logging crews for the Grandin mill and 

others must have cut shortleaf pine trees wherever they were 

found, whether in pure stands on southerly aspects or even 

just a few trees in an oak-dominated stand.

If a stand was dominated by shortleaf pine before being 

high-graded, it had at least a chance of returning to 

shortleaf. Pines smaller than the accepted merchantable size 

would not have been cut; those small trees were probably 

mature, and would have dispersed seed on a recently 

harvested site that had suffi cient exposure from logging and 

skidding so as to present a relatively favorable seedbed for 

shortleaf regeneration, especially if surface fi res contributed 

to site preparation and competition control. Similar natural 

dynamics undoubtedly followed harvest of pure stands 

of shortleaf throughout the Interior Highlands, and must 

have been effective judging by the extent of second-growth 

shortleaf pine stands throughout the region. 

But a different dynamic arguably ensued in hardwooddominated stands. There, loggers looking for pines would 

not have cut the hardwoods, they would have cut only the 

few pines sought by their mill. A high-grading that took fi ve 

or ten shortleaf pines per acre and left all the hardwoods 

would not have caused a suffi ciently intensive disturbance 

to result in a new age cohort of shortleaf pine. These stands 

probably responded to pine logging as essentially a crown 

thinning, resulting in more growing space for the overstory 

hardwoods. Far fewer shortleaf pines were probably left as 

a seed source, and overstory hardwood shade would likely 

inhibit development of any shortleaf that persisted or were 

newly established in the understory. These speculations 

lead us to suspect that local extirpation of shortleaf pine 

was more likely in mixed stands than in pure stands, and 

especially in the oak-pine stands where pine was a minor 

component initially. Evidence of that extirpation exists 

today in stands that contain no shortleaf pine, but in which 

we can still fi nd scattered shortleaf pine stumps. Such stands 

are not uncommon in the Missouri and Arkansas Ozarks.

The implications of this are interesting in light of the fact 

that restoration of shortleaf pine is moving forward. The 

silvicultural basis of ecological restoration includes reinitiation of suppressed ecological processes (e.g., fi res), 

removal of encroaching native and exotic species, and the 

establishment of the native species that once dominated the 

landscape. This prescription is fairly straightforward when 

the native species is in relatively pure stands, as seen in the 

pine-bluestem restoration projects being undertaken by each 

of the three national forests in the Interior Highlands, and by 

the oak woodland restoration projects under way on the two 

national forests in the Ozarks. There are also opportunities 

in the restoration of mixed pine-oak and oak-pine stands in 

the region. 

However, the research to support restoration of shortleaf 

pine is incomplete. Some elements are fi rmly established in 

the scientifi c literature and in practice, but other elements 

are based on empirical silvicultural tactics that we think 

we know but that are not yet fi rmly established in the 

literature. And some elements are unusually speculative, 

based on what could be considered the wishful application 

of generalities (WAGs) that can be derived from the silvics 

and silviculture of shortleaf pine. In this paper, elements 

important to consider in application of silvicultural concepts 

to shortleaf pine will be reviewed for each of these three 

elements—science, empiricism, and WAGs.

SCIENCE UNDERLYING SHORTLEAF PINE 

SILVICULTURE

A number of elements of shortleaf pine silviculture that can 

be applied in restoration prescriptions are drawn from good 

scientifi c fi ndings fi rmly accepted in the literature. One 

set of fi ndings can be taken from existing science that was 

originally intended to support productive management of 

shortleaf pine for timber products. The other set has been 

developed largely in direct support of pine-grassland habitat 

restoration, of direct benefi t to the endangered red-cockaded 

woodpecker but also of great value in bringing back a suite 

of associated species originally found in pine-bluestem 

woodlands. 

Planting Shortleaf Pine for Restoration

 If a restoration decision is made to reforest or afforest 

a site with shortleaf pine where no natural seed source 

is available, the most direct approach is to use artifi cial 

regeneration. The science that supports artifi cial shortleaf 
49

pine regeneration is well established, largely through the 

actions of the shortleaf pine artifi cial regeneration task 

force of the late 1980s and reviewed elsewhere in these 

proceedings (Barnett and Brissette, this volume). In a 

nutshell, planting works well with shortleaf pine, especially 

when incorporating advances in seed and seedling quality 

(Barnett 1992). Among the important considerations 

for success was development of target seedlings in the 

nursery that were larger than had been produced previously 

(Brissette and Carlson 1992), which is consistent with 

commonly-accepted general trends that point to greater 

success with larger planting stock for any number of pine 

and hardwood species in the South over the past decade. 

A second key factor in successful plantation establishment 

on the Ouachita NF was the site preparation treatment of 

ripping or subsoiling, in which a vertical steel bar is used 

to essentially plow a furrow from 12 to 18 inches deep in 

the rocky hillside soil during the late summer of the year 

prior to planting. Data suggest that ripping alone increased 

seedling survival by 10 to 30 percent (Walker 1992), from 

roughly 50 percent to 80 percent. Ripping is typically used 

to ameliorate planting conditions in soils with a prominent 

fragipan, but Ouachita soils do not have fragipans. 

Inspection of the rips suggests why they might be effective. 

During the 6 months between ripping and planting, rainfall 

dislodges soil particles l from the sides of the furrow toward 

the bottom, a microcolluvial effect that fi lls the cracks and 

fi ssures in the base of the furrow with several inches of soil 

fi nes (Fig. 1a). The seedlings are then planted in that thin 

layer of soil. Subsequently, when temperature and drought 

stresses reach their maximum late in the summer during the 

fi rst growing season, that small amount of soil in the furrow 

provides a rooting medium for the seedling that moderates 

extremes of temperature and soil moisture defi cit compared 

with a seedling planted directly in these rocky soils (Fig. 

1b). These conditions contribute greatly to reduced seedling 

mortality.

Restoration Prescriptions

The prescription applied to immature and mature shortleaf 

pine stands for restoration or recovery of shortleaf pine 

woodlands is essentially a series of intermediate treatments 

(sensu Smith and others 1997). Those treatments are 

intended to promote habitat favorable to the endangered redcockaded woodpecker, with attendant benefi ts to a number 

of associated woodland fl ora and fauna (Fig. 2). Hedrick and 

others (this volume) summarize that work with a synthesis 

of empirical treatments needed to execute the prescription, 

and a summary of numerous studies that have quantifi ed 

fi re occurrence and treatment effects on fl ora and fauna 

(Masters and others 1995, 1996, 1998; Sparks and others 

1998, Wilson and others 1995, Cram and others 2002) 

and related ecological, economic, and silvicultural effects 

(Huebschmann 2003, Thill and others 2004, Guldin and 

others 2005, Liechty and others 2005). 

Figure 1a.—Ripping promotes fi rst-year survival of planted 

seedlings through microcolluvial deposition within the rip. 

Ripped furrow shortly after being created in the summer prior 

to planting (photo by James M. Guldin).

Figure 1b.—Shortleaf pine seedling planted in the ripped 

furrow, in August of its fi rst growing season (photo by James 

M. Guldin).
50

The key elements in this prescription, in order of 

implementation, are using tree cutting to simulate natural 

disturbance patterns, removing the midstory hardwoods that 

have encroached upon the stand in the absence of fi re for the 

past seven decades, and increasing the use of prescribed fi re 

(Bukenhofer and Hedrick 1997, Guldin and others 2005). 

The studies cited have all explored the separate or combined 

effects of the thinning, midstory reduction, and burning, and 

it appears that in practice all three treatments are required to 

consistently give best results.

Restoration Applications of 

Growth and Yield Models

Finally, there are opportunities in restoration prescriptions 

to apply existing growth and yield models, especially 

individual-tree models that generate stand tables by 

diameter class. This is not the fi rst time that timberbased models of stocking and growth have been of use to 

ecologists, because they can be used to quantify biomass, 

snags, woody debris, and other tree-based attributes that can 

be effi ciently modeled with an understanding of tree size. In 

the Ouachitas and southern Ozarks, the Shortleaf Pine Stand 

Simulator model (Huebschmann and others 1987) provides 

a fi rst-rate tool to model the development of naturally 

regenerated shortleaf pine stands, whether even-aged (Lynch 

and others 1999) or uneven-aged (Huebschmann and others 

2000). The model requires input of stem density by diameter 

class and gives users a tool to predict growth over different 

time horizons of different intensities of treatment. 

While growth and yield models have traditionally been 

interpreted from a timber-based perspective, it is equally 

appropriate to use a model such as this to evaluate 

stand development alternatives under different levels of 

commercial thinning in a restoration prescription. Individual 

tree models generate stand and stock tables that contain 

data on diameter distributions in terms of stem density by 

size class. To apply growth and yield models in the context 

of restoration, foresters should quantify desired future 

conditions using stem density by diameter class, and then 

apply the growth and yield models to analyze the degree to 

which different treatments might develop the target diameter 

distribution. These models might be especially meaningful 

in prescriptions that seek to accelerate mean stand diameter 

growth past a minimum threshold in a managed old growth 

context, to calculate changes in volume over time if leaving 

living relicts or snags of a given size and density, and so on. 

EMPIRICAL EVIDENCE SUPPORTING 

SHORTLEAF PINE SILVICULTURE

The creative application or extension of known silvicultural 

practices and refi nement of new practices for restoration of 

shortleaf pine fall less into the realm of known science and 

more into the realm of well-founded empirical experience. 

Some of these empirical advances relate to using old 

authorities in new ways and under new interpretations. 

Others relate to no less than the practical development of 

new techniques by personnel in the fi eld rather than by 

scientists in a lab or academic setting. 

Reinvestment of Harvest Proceeds 

in Restoration Treatments

The example of old authorities being interpreted and 

applied in new ways to new situations is nowhere more 

apparent than on National Forest System lands. Here, 

the old authority was the Knutsen-Vandenberg (KV) Act 

of 1933, which allowed Forest Service land managers to 

reinvest a portion of the harvest proceeds in reforestation 

of harvested areas. The reinterpretation of the authorities 

under the KV Act to allow for not only reforestation but also 

for general improvement of forest stand conditions within 

the sale area has opened the door for KV funds to be spent 

on reforestation not only by artifi cial regeneration, but also 

by natural regeneration. In addition, activities undertaken 

to improve forest conditions such as treatments to promote 

specifi c habitat conditions have also come to be interpreted 

as within the scope of the KV Act. 

This is important because the KV Act provides funds 

beyond those appropriated funds authorized for annual 

agency activities. Because of competing agency priorities 

for increasingly limited appropriated funds on an 

annual basis, it is diffi cult to achieve restoration goals 

over ecologically signifi cant areas through reliance on 

appropriated funds alone. The concept of the KV Act is 

also meaningful to private landowners, whose sole source 

of funding for treatments they choose is frequently a 

reinvestment of harvest proceeds.

Nowhere has a more creative blending of these authorities 

been practiced than in the shortleaf pine-bluestem 

restoration prescription in the National Forests of 

the Interior Highlands, especially the activities under 

Figure 2.—Restored stand in the pine-bluestem restoration 

area on the Ouachita NF, Scott County, Arkansas (photo by 

James M. Guldin).
51

Management Area 22 on the Ouachita NF (Bukenhofer and 

Hedrick 1997, Guldin and others 2005, Hedrick and others, 

this volume). The commercial thinning of shortleaf pine in 

the restoration prescription provides appropriations-strapped 

National Forests with KV-based funds to support follow-up 

midstory and burning treatments. Those treatments can then 

occur for a longer time (as much as 10 years for followup prescribed burning) and over a much wider geographic 

area than could be afforded using appropriated dollars 

alone. In essence, part of the value of the standing volume 

of shortleaf pine sawlogs in excess of that needed for 

restoration is used to fund the restoration prescription. 

This management tactic works as well as it does in western 

Arkansas because of the continued presence of a strong and 

viable local lumber manufacturing industry in the region. 

A model of timber sales for the region shows that bids are 

correlated to both the volume of pine sawtimber offered in 

the sale and to the ratio of the prevailing dimension lumber 

price index to the sawlog price index, a factor affecting mill 

conversion opportunities in a given market (Huebschmann 

and others 2000). The existence and proximity of lumber 

mills that manufacture pine dimension lumber from pine 

sawlogs are a key elements to the success of this tactic.

Use of Prescribed Burning

Prescribed burning has increased dramatically on National 

Forest lands in the region, but few others on forest 

industry or private lands apply the technique. A wider 

use of prescribed burning on other land ownerships in the 

region is not likely to occur because of legal issues that 

surround liability for prescribed fi re, the perception that 

burning results in some minor growth loss, concerns about 

smoke management, and a still-strong attitude within the 

professional community that fi res should be controlled 

rather than set. Even within Federal ownership, burning 

can vary by district because of differences in planning, 

application, and commitment of district personnel to the 

effort.

Prescribed burning requires considerable expertise to 

employ effectively. Probably no element of silvicultural 

practice is more diffi cult to translate from the classroom 

to the woods. Much of the education obtained when using 

prescribed fi re occurs when things do not go quite as 

planned. The accumulated wisdom of the professional and 

technical personnel who conduct this burning program is an 

invaluable asset for meeting the commitments required for 

effectively using this tool on a landscape scale. 

As with many agencies, however, U.S. Forest Service 

personnel represent a graying workforce and the districts 

that employ them are increasingly on limited budgets. 

District professionals also have responsibility for larger 

areas than a decade ago because of the prevailing trend for 

consolidation of ranger districts over that period of time. 

Ideally, the tenure of the old, outgoing professional would 

overlap with that of the young, incoming professional, 

to allow for translation of some of the experience-based 

knowledge from predecessor to new employee. But 

that situation is nearly impossible to achieve under the 

budgets with which the agency is working. Consequently, 

retirements and changes of duty station often diminish 

the district’s capability to maintain a prescribed burning 

program. The technicians often become the bridge, and they 

are graying also.

Reproduction Cutting Methods 

other than Clearcutting

The use of reproduction cutting methods other than 

clearcutting is on the rise on National Forest land in the 

Interior Highlands, a trend mirrored by the use of natural 

regeneration rather than planting for reforestation after 

reproduction cutting (Guldin and Loewenstein 1999). The 

shift away from clearcutting and toward methods of cutting 

that rely on natural regeneration was triggered by the Walk 

in the Woods on the Ouachita NF (Robertson 1999). Recent 

forest planning activities on the Ouachita NF, OzarkSt.Francis NF, and Mark Twain NF suggest that this trend 

will continue. 

Research on reproduction cutting methods that rely on 

natural regeneration has not kept pace with the application 

of the practice. Interim results 5 years after reproduction 

cutting in the Ouachita Mountains Ecosystem Management 

Research Project (EMRP) suggest that all reproduction 

cutting methods can be made to work, but that some work 

better than others (Guldin and others 2004a, 2004b). 

Regeneration in the shelterwood stands has not yet been 

subject to damage commonly associated with the partial 

removal cut of residual overstory trees, nor has the 

regeneration in the uneven-aged stands experienced the 

subsequent cutting cycle harvest; both of these activities are 

known to cause mortality that in the long term might affect 

sapling survival. Moreover, this study was installed without 

the use of prescribed fi re as part of the site preparation, and 

different results are expected in the presence or absence of 

prescribed fi re when conducting reproduction cutting. To be 

useful on both public and private forest lands in the region, 

robust silvicultural tactics associated with reproduction 

cutting must be developed in situations where fi re can be 

used, and also where it cannot be used. 

The lag between research and practice is evident in the 

preference of practicing silviculturists to employ the seedtree and group selection methods, which interim research 

results suggest might be less effective than the shelterwood 

and single-tree selection methods (Guldin and others 2004a, 

2004b). Practicing silviculturists point to the advantage of 

using prescribed fi re as a site preparation tool in seed-tree 

stands to prepare a seedbed for pine seedfall. They also 

suggest that administrative advantages of group selection 
52

relative to single tree selection include greater effi ciency in 

(1) contracting site preparation and release treatments; (2) 

logging (groups serve as logging decks); and (3) retention of 

hardwoods for wildlife and aesthetic reasons in the matrix 

between the group openings. These elements suggest that 

research scientists have more work to do to better quantify 

regeneration dynamics and development under these popular 

methods for application, especially if there are some yet-tobe-answered questions about stocking and distribution of 

regeneration resulting from their application. 

Shortleaf Pine Seedfall

An understanding of seed production in natural stands 

of shortleaf pine is important in managing for natural 

regeneration of the species, and recent work had added 

to our understanding of this. Shelton and Wittwer (1995) 

analyzed 9 years of shortleaf pine seedfall data collected 

in the 1960s to 1970s. The study suggested that three to 

fi ve adequate or better seed crops per decade, with an 

average of 100,000 seed annually. There was considerable 

geographic variation in seedfall, with higher amounts in 

the eastern Ouachitas and lower amounts in the western 

Ouachitas. Seedfall was also positively related to stand age 

and negatively related to pine and hardwood basal area, 

suggesting that overstocking and competition inhibit crown 

expansion and cone production in the pine component. 

Wittwer and others (2003) reported on a more recent 

seedfall study within the Ouachita EMRP; over a four-year 

period, seed crops were good, poor, poor, and bumper, 

with differences by reproduction cutting method in the fi rst 

good crop but not the last. Their results suggest a crown 

response in shortleaf pine to cutting methods that reduce 

canopy competition, which was also noted by Wittwer and 

others (1997) when comparing seed tree versus single-tree 

selection stands. In summary, these studies suggest that in 

shortleaf pine stands, especially those that have been thinned 

prior to harvest (but not late in the rotation), adequate or 

better seed crops suffi cient to regenerate shortleaf pine can 

probably be expected in two of three chances when using 

the seed-tree method (Shelton and Wittwer 1995). The odds 

are longer farther to the west of the Interior Highlands.

The commonly used subjective empirical tools for seed 

prediction—such as cone counts with binoculars, or 

inspection of the crowns of pines harvested in logging jobs, 

during the summer before seedfall—do not allow foresters 

to predict an average or better seed crop in a given season 

more than a few months in advance, or to make plans to take 

advantage of a forecast for a good seed crop. For example, 

logging activity is known to scarify the forest fl oor, and the 

exposed bare mineral soil that results is an excellent seedbed 

for natural seedfall of southern pines (Baker and others 

1996). But a forester will have only a few months between 

prediction of a bumper seed crop and the seedfall itself. 

On private lands with limited acreage, landowners or the 

foresters who advise them can often arrange a small timber 

sale on short notice in a stand where reproduction cutting is 

desired, so as to catch a predicted seed crop on the freshly 

exposed soil of the forest fl oor. 

But silvicultural operations take place more or less 

continually on larger holdings such as national forest 

lands or forest industry lands, and there is less opportunity 

to tailor a silvicultural treatment to take advantage of 

an ephemeral window for seedfall. Provisions in timber 

sale contracts on national forests often allow a multi-year 

window (3 years is typical in the South) for completion of 

the harvesting; loggers are free to operate at any time within 

that window provided that conditions are appropriate for 

forest operations. Timber sale contracts can and often do 

specify the months during which operations can and cannot 

occur, so as to avoid detrimental impacts of harvesting 

at specifi c times of the year (such as during the breeding 

season for wild turkey). But those contracts cannot specify 

the exact year within the multi-year window of the contract 

that harvesting is to occur, and this inability makes it risky 

for a forester to rely on the silvicultural tactic of having 

natural seedfall occur immediately after a logging operation. 

The remedy is to plan for supplemental site preparation 

independent of the logging job, where we can better control 

the timing of the operations through contracts for specifi c 

treatments within a given year.

WAGS ABOUT SHORTLEAF PINE 

SILVICULTURE

There is no shortage of topics for advances to be made 

by silviculturists either in research or active management 

positions. Some of these opportunities for advancement 

transcend the Interior Highlands—such as managing mixed 

stands, especially those having a minor and varying pine 

component. Others are unique to shortleaf pine, including 

answers to basic questions about the biology and silvics of 

this species. The topics that are proposed are interesting in 

that if shown to be true, they might fi nd wide application in 

developing and using silvicultural practices in shortleaf pine 

management and restoration.

The Natural Range of Loblolly Pine

There are curious elements about the natural range of 

loblolly and shortleaf pine that suggest ecologists and 

silviculturists have incompletely understood these species 

and the ecological circumstances and adaptations that 

govern their distribution. The northwesterly limit of the 

natural range of loblolly pine in the region coincides with 

the limit of the upper West Gulf Coastal Plain and the 

Athens Piedmont Plateau, where it is found as a dominant 

pine in stands having a minor and varying shortleaf pine 

component. There is some evidence to suggest that perhaps 

this mixture was dominated by shortleaf pine 70 years 

ago, mostly evident through the persistence of early forest 

scientists in the region referring to those Coastal Plain 

stands as “shortleaf-loblolly pine” stands (Reynolds and 

others 1944, Reynolds 1947).
53

Interestingly, the transition from mixed pine stands to pure 

shortleaf pine stands occurs within a range of about 20 

miles, with a few scattered loblolly pine-dominated stands 

in transition. This is an unusually rapid ecological transition, 

which, while certainly infl uenced by the rise of the southern 

part of the Ouachita Mountains in that area, cannot be 

solely explained by the obvious actions of climate, weather, 

geology, fl ora, fauna, or humans. We might speculate that 

fi re played a role, or ice storms, or anthropogenic burning 

prior to European colonization. While these factors might 

explain a gradual change across the Ouachitas generally, 

they do not explain the sharp transition that actually exists. 

If a causal ecological agent for this disappearance of 

loblolly from mixed pine stands could be elucidated and 

quantifi ed, it might be of considerable ecological interest 

in the context of shortleaf pine restoration. It might also 

be possible to use that knowledge to develop silvicultural 

restoration tactics that favor shortleaf pine in stands that 

had been converted to loblolly pine by forest industry 

landowners, especially on that portion of the industry land 

base that has been reacquired by Federal land managers 

through purchase or exchange.

Advantages of the Sprouting Habit 

of Shortleaf Pine

 The sprouting habit of shortleaf pine (Fig. 3) might be 

useful in silvicultural applications for natural regeneration 

in pure and mixed stands beyond that for which it is being 

used today. In an environment that features frequent 

surface fi res, logic suggests that any given fi re will result in 

topkilled seedlings that subsequently resprout, and might 

also create seedbed conditions favorable to germination 

of new seedlings. The sprouts and seedlings combine to 

create a new cohort that persists in the understory until a 

subsequent surface fi re, which again promotes resprouts of 

the previous cohort as well as new germinants in the burned 

seedbed. Over time, this process of seedling establishment 

and resprouting after a series of fi res should result in a 

bioaccumulation of pine seedlings and sprouts, constituting 

a stored seedling bank awaiting overstory disturbance to 

develop into the pine component of a new stand. 

If properly applied, this stored seedling bank could make 

natural regeneration of shortleaf pine in managed pine 

stands more certain in any given year, even those in which 

an adequate or better seed crop is not expected. Applying 

late-rotation prescribed fi re would be instrumental in 

development of the seedling bank. This prescription would 

be useful to circumvent the problems in seedfall timing 

promoted by the multi-year logging windows of modern 

timber sale contracts. It would be especially useful in the 

seed-tree method to circumvent problems of understocking 

due to limited seedfall. 

In principle, this tactic might be applied to any of the evenaged or uneven-aged reproduction cutting methods used for 

natural regeneration. Several cycles of prescribed burning in 

Figure 3.—Shortleaf pine seedling sprouts emerging several 

weeks after the shoot was topkilled by a growing season 

prescribed fi re, Ouachita NF, Scott County, Arkansas (photo 

by Richard Straight).

properly-thinned stands prior to reproduction cutting would 

initiate the process. Executing the reproduction cutting 

would require suspension of the burning program for a cycle 

or two, so that the saplings could grow suffi ciently so as 

not to be topkilled when prescribed fi re is returned to the 

stand. This approach is being studied in the pine-bluestem 

management area on the Ouachita National Forest, and in 

a study of prescribed fi re in seedling stands on the OzarkSt.Francis National Forest, as fi rst steps in quantifying 

whether this bioaccumulation is silviculturally feasible.

Mixed Pine-Oak and Oak-Pine Stands

Very little is known about the silvicultural practices needed 

to manage mixed stands of shortleaf pine and hardwoods in 

the region (Fig. 4). The fundamental premise in managing 

mixed stands is to use silvicultural practices that can be 

successfully applied for each of the species in the mixture, 

and to avoid those practices that discriminate against the 

species sought in mixture. Conceptually, the simplest 

approach to regenerating a mixed stand is to successfully 
54

regenerate each of the species that are sought, and then 

to use individual-stem release treatments to adjust the 

proportions of species in the mixture to some desirable 

standard. This approach has been used in empirical practice 

on national forest lands, especially in pine-oak stands 

where pines are either planted or obtained through natural 

regeneration and where oaks are brought in through stump 

sprouts or advance-growth seedling sprouts. 

Management of mixed oak-pine stands is more diffi cult 

because it is inherently diffi cult to regenerate just a few 

pines in a cohort dominated by oaks and other hardwoods. 

A stand being regenerated to hardwoods in the region 

is not likely to have a nearby pine seed source, either 

because pines may not be adapted to that particular site or 

because the pines that were adapted to that site may have 

been removed decades ago through partial cuttings. Nor 

has it been a traditional practice to plant just a few dozen 

pines per acre in a stand being regenerated to hardwoods. 

And even if a small number of pines were established 

naturally or by planting following a reproduction cut, they 

would be at a competitive disadvantage relative to sproutorigin hardwoods because sprouts grow more rapidly than 

seedlings.

If we accept the premise that mixed oak-pine stands were 

once common in the region and are no longer, and that 

efforts should be made to restore them, the silvicultural 

tactics for restoration of a minor pine component in an oakhickory stand become of more than academic interest. To 

do so, we should separate establishment of pine seedlings 

and their development. Establishment will probably require 

direct silvicultural intervention, and development dictates 

using an advance growth strategy to promote the pines as 

well as the oaks. 

To get pines established, we would rely on happenstance 

establishment of pine seedlings and on artifi cial 

regeneration. We might start by promoting the survival and 

growth of any pine seedlings or saplings that might exist 

in the stand understory. We would also plan to retain any 

existing natural seed sources in or adjacent to stands being 

regenerated in case seedlings appear through rare longdistance dispersal processes such as wind dissemination 

of seed over extraordinary distances, or through animal 

activity. And, we would probably work to successfully plant 

or underplant a few pines prior to or during harvest. But 

recommendations have yet to be established about planting 

density, pattern, or spacing. There might be some wisdom 

inherent in clustered planting of pines in a small multi-stem 

cohort such that pines in the center of the cohort would be 

subject only to intraspecifi c competition rather than the 

interspecifi c competition of hardwoods. 

Further development of the mixed-species regeneration 

cohort through the sapling stage, especially in oak-pine 

mixtures, will certainly require individual-stem release 

treatment to obtain the desired proportion of oaks and 

pines in the mixed stand. Since we know so little about 

regenerating only a few pines in an oak-pine stand, we could 

always fall back on the most traditional silvicultural tactic 

based on practices intended to achieve pine dominance. 

Arguably, the most certain way of regenerating a small 

pine component in oak-pine stands is to aggressively work 

to establish a much larger number of pines than desired, 

and then aggressively kill most of them during a cleaning 

or release treatment. Admittedly, this is the costliest and 

least clever way to achieve this silvicultural objective, 

but it might serve as an interim measure until a better 

understanding of the natural oak-pine regeneration dynamic 

is obtained, which can then be emulated silviculturally.

The sprouting ability of shortleaf pine offers extraordinary 

potential along these lines also. This habit has much 

in common with the advance growth dynamic of oaks, 

and could possibly be developed as a legitimate pinehardwood—or, more importantly, a hardwood-pine—

regeneration prescription. The silviculture of oak requires 

planning for regeneration on the order of two decades in 

advance of harvest, with late-rotation thinning doubling 

as preparatory cutting and midstory removal of competing 

hardwoods required to promote advance regeneration 

of oaks (Johnson and others 2002, Loftis 1990). Adding 

prescribed burning to this prescription might be useful 

in promoting oak advance growth through topkilling and 

resprouting of seedling sprouts of oak. If a shortleaf pine 

seed source is available, some pines might be recruited and 

promoted in the mixed-species advance growth cohort. If no 

pines are present, and silviculturists seek a pine component 

in such a stand, they might be planted in conjunction with 

the prescribed fi re program (such as immediately following 

or in the dormant season following a given fi re, depending 

on when the burn is conducted) at whatever density the 

silviculturist seeks. 

When this mixed-species regeneration cohort is ultimately 

released for recruitment into the overstory, the pines should 

respond much as do the hardwoods—which would give the 

pines a stronger competitive position with respect to the 

Figure 4.—A westerly view in the eastern Ouachita 

Mountains, Saline County, AR. The view illustrates the 

dominance of pines on south-facing slopes and the 

dominance of hardwoods on north-facing slopes in these 

east-west oriented ridges (photo by Rudy Thornton).
55

hardwoods than new seedlings would have, because they 

would have larger root systems built during their time as 

advance growth. Fine-tuning the mixture would also then 

be possible during precommercial release treatments 5 to 

10 years after the initial overstory recruitment treatment 

(Fig. 5). Considerable research would be needed to precisely 

quantify the number, density, and timing of advance 

planting of shortleaf pine to attain given levels of shortleaf 

pine in mixture with hardwoods a decade or two after being 

released, especially for the oak-pine management objective. 

But using fi re to deliberately trigger the topkill and 

resprouting would be consistent with the natural ecological 

dynamic for both pines and oaks, which seems not unlike 

the prevailing ecological infl uence in these forests in 

presettlement conditions.

Finally, there may be potential in retaining part of the pine 

overstory for an extended period of time. The straight-line 

and tornadic windstorms that periodically disturb pine 

stands in the Ouachitas occasionally leave a minor and 

varying overstory pine component on the site after the 

disturbance. Those escapees from the disturbance may 

have an important role in subsequent seeding of pines, 

and development of a mixed pine-hardwood regeneration 

component, over time. We might speculate that this new 

cohort might tend more to the pine component if fi re had 

recently occurred in the understory prior to the wind event, 

to the hardwood component if fi re had not recently preceded 

the windstorm, or again to the pine component if fi re 

followed soon after the windstorm. The balance between 

use of fi re to promote a mixed pine-hardwood regeneration 

cohort and the retention of pines and hardwoods as an older 

age cohort will be of interest to foresters in the 21st century, 

but much work remains to be done to better quantify these 

ideas.

CONCLUSION

Planting shortleaf pine will be required to restore the 

species on sites where it currently is not, such as abandoned 

agricultural or cutover land in the Interior Highlands. 

Ripping has been shown to be essential to improve survival 

of planted shortleaf pine. But the site-wide disturbance of 

the soil associated with ripping may be inconsistent with 

other restoration objectives, such as minimal disruption 

of the forest fl oor. Site preparation techniques must 

be developed that have the advantages of ripping for 

seedling survival but not the adverse effects on the forest 

fl oor throughout the stand. It seems that a localized soil 

disturbance of 3 feet or less in size might achieve the same 

advantages as ripping in microcolluvial soil deposition, and 

might better emulate a common natural soil disturbance 

event in nature—the uprooted root ball of a windthrown 

tree. Proper development of this site preparation treatment 

would also offer potential for localized collection of water, 

which might be useful for local populations of herpetofauna 

as well.

Figure 5.—A precommercially-thinned regeneration cohort 

beneath a shortleaf pine shelterwood in Scott County, 

Arkansas. The deliberate objective was to release both pines 

and oaks to promote a mixed pine-hardwood regeneration 

cohort (photo by Richard Straight).

The treatments associated with the shortleaf pine-bluestem 

restoration prescription to convert immature and mature 

second-growth shortleaf pine stands to pine-bluestem 

woodlands have to date relied upon the use of cutting and 

burning to remove the midstory hardwoods that built up in 

the stand through the period of fi re exclusion over the past 

seven or so decades. But chainsaw felling and restoration of 

cyclic prescribed fi res have not been suffi cient to remove the 

rootstocks of those midstory hardwoods, and sprout clumps 

associated with those rootstocks persist in restored stands 

though multiple prescribed fi res (Fig. 6). A more complete 

removal of these stems might be possible using herbicides 

Figure 6.—A stand that meets the goals of pine-bluestem 

restoration in the western Ouachita Mountains growing 

seasons after prescribed burning, Scott County, Arkansas; 

hardwood resprouting is prominent (photo by Richard 

Straight).
56

that target mortality of the entire plant, not just the aboveground part. Herbicide use admittedly is unpopular on 

Federal ownerships, but there might be a place for limited 

stem-specifi c applications such as when the initial midstory 

removal treatment is implemented. More information is 

needed as to different qualities of understory condition in 

the presence or absence of these resprouting rootstocks to 

make better decisions about whether to remove them with 

unpopular herbicide prescriptions. That information could 

be especially useful in extending the restoration to private 

lands, where a carefully timed herbicide application might 

be less constrained than on public forest land.

Successful restoration over a broad area requires a thriving 

local timber industry. No doubt some might feel this is 

oxymoronic, but strong mill capacity and a regional market 

for pine sawtimber create opportunities for national forest 

land managers to provide commercial timber for sale; 

they can then use some of the profi ts from those sales to 

restore larger areas of a landscape than would be possible 

without those markets. Interestingly, many of these mills 

also purchase sawtimber from adjacent forest industry 

lands, which can in part provide alternative sources of 

supply for those mills when sales on national forest land 

become limiting. Thus, an intermingled ownership that 

allows local sawmills to buy timber from private lands when 

national forest timber sales are periodically limited may 

also be a positive element that promotes large-scale habitat 

restoration on the federal land base in the region.

Silviculture has been defi ned as both an art and a science, 

and there is probably no element of the body of silviculture 

more characteristic of the art than the application of 

prescribed burning as an intermediate treatment and in 

reproduction cutting. Efforts should be developed, perhaps 

through cooperation with state forestry or heritage agencies 

and conservation organizations, to develop regional 

prescribed fi re training academies in the Forest Service 

that would provide some of the practical experience that 

seems to be more critical in application of burning than any 

other silvicultural practice. The staff of the academy could 

in part be composed of recent retirees from these agencies 

experienced in the use of the tool, and rehired to work in 

the incident command structure for wildfi res and disaster 

response.

The broad set of reproduction cutting methods imposed in 

the Ouachita Mountains EMRP was constrained by their 

size and breadth of scope. The infl uence of prescribed 

fi re on pine seedling recruitment and on the balance of 

regeneration through sprouting and new seedlings must 

be understood. Research should concentrate on the full 

spectrum of mixed-species stand dynamics as well, with 

efforts to quantify the effect of supplemental pine planting 

in advance of harvest under a burning program for goals of 

restoring both pine-hardwood and hardwood-pine stands 

on appropriate sites. An advance-growth seedling bank 

approach to shortleaf pine silviculture offers tremendous 

opportunity for silvicultural application in pure and mixed 

stands, and provides tactical advantages in simplifying 

regeneration establishment and development under the 

uncertainty of shortleaf pine seed crops and the timing of 

harvesting operations.

ACKNOWLEDGMENTS

Thanks to the many research foresters and resource 

managers in both the public and private sectors who have 

been willing to entertain abstract discussions about shortleaf 

pine ecology and silviculture over the years, including Jim 

Baker, Mike Shelton, Tom Foti, Louis Rainey, Gary Arpin, 

Ernest Lovett, Gerald Heath, John Strom, Ray Yelverton, 

Bill Walker, John Andre, and Larry Hedrick. Thanks also to 

Eric Zenner, whose review comments helped to markedly 

improve this paper. 

LITERATURE CITED

Baker, J.B.; Cain, M.D.; Guldin, J.M.; Murphy, P.A.; 

Shelton, M.G. 1996. Uneven-aged silviculture in the 

loblolly and shortleaf pine forest types. Gen. Tech. 

Rep. SO-118. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research Station. 

65 p. 

Barnett, James B. 1992. History of the shortleaf pine 

artifi cial regeneration task force and objectives of the 

workshop, In: Brissette, John.C.; Barnett, James.B., 

comps. Proceedings of the shortleaf pine regeneration 

workshop; 1991 October 29-31; Little Rock, AR. Gen. 

Tech. Rep. SO-90. New Orleans, LA: U.S. Department 

of Agriculture, Forest Service, Southern Forest 

Experiment Station: 2-6. 

Barnett, James .B.; Brissette, John C. Regenerating shortleaf 

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proceedings of a symposium; 2006 November 7-9; 

Springfi eld, MO. Gen. Tech. Rep. Newtown Square, 

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

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Bukenhofer, G.A.; Hedrick, L.D., 1997. Shortleaf pine/

bluestem grass ecosystem renewal in the Ouachita 

Mountains. In: Wadsworth, K.G., ed. Transaction of the 

62nd North American Wildlife and Natural Resources 

Conference; 1996 March 14018; Washington, DC. 

Washington, DC: Wildlife Management Institute: 

509-515.

Cram, D.S.; Masters, R.E.; Guthery, F.S.; Engle, D.M.; 

Montague, W.G. 2002. Northern bobwhite population 

and habitat response to pine-grassland restoration. 

Journ. Wildlife Management. 66(4): 1031-1039.
57

Flader, Susan L. 2004. History of Missouri forests and 

forest conservation. In: Flader, Susan L, ed. Toward 

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73-102

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15-20.

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2003 National Silviculture Workshop; 2003 September 

8-12, Granby CO. Proceedings, RMRS-P-34. Ft. 

Collins, CO: U.S. Department of Agriculture, Forest 

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A bid price equation for national forest timber sales 

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fi re history of McCurtain County Wilderness Area 

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eds. Red-cockaded woodpecker recovery, ecology and 

management. Nacogdoches, TX: Stephen F. Austin 

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red-cockaded woodpeckers on white-tailed deer forage 

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148-158.

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244. Washington, DC: U.S. Department of Agriculture. 

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of Agriculture, Forest Service, North Central Research 

Station. [Online only]. Available at: www.ncrs2.fs.fed.

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Reynolds, R.R. 1947. Management of second-growth 

shortleaf-loblolly pine-hardwood stands. Journal of 

Forestry. 45(3): 181-187.

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aspects of selective cutting in the management of 

second-growth pine-hardwood forests west of the 

Mississippi River. Tech. Bull. 861. Washington, DC: 

U.S. Department of Agriculture. 118 p. 

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and ecosystem management, p. 3-7. in: Guldin, James 

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symposium: ecosystem management research. Gen. 

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Shelton, Michael G.; Wittwer, Robert F. 1996. Shortleaf 
58

pine seed production in natural stands in the Ouachita 

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Ashton, Peter M.S. 1997. The Practice of Silviculture, 

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and late dormant-season prescribed fi re on herbaceous 

vegetation in restored pine-grassland communities. 

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pine-bluestem restoration for red-cockaded 

woodpeckers in the Ouachita Mountains: Implications 

for other taxa. In: Costa, R.; Daniels, S., eds. 

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symposium; 2003 Jan. 27-31; Savannah, GA. Blaine, 

WA: Hancock House Publishers: 657-671.

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Breeding bird response to pine-grassland community 

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59

SUCCESSIONAL TRENDS OF SIX MATURE SHORTLEAF PINE FORESTS IN MISSOURI

Michael C. Stambaugh and Rose-Marie Muzika1

ABSTRACT.—Many of Missouri’s mature oak-shortleaf pine (Quercus-Pinus echinata) forests 

are in a mid-transition stage characterized by partial pine overstory, limited pine recruitment, 

and minimal pine regeneration. Restoration of shortleaf pine communities at a large scale 

necessitates the understanding and management of natural regeneration. To understand 

late-successional conditions of shortleaf pine forests, we conducted a complete survey of 

woody vegetation and canopy openings at six uncut and old second-growth oak-pine stands 

in southeastern Missouri. A total of 121 canopy gaps were mapped and measured in terms of 

their size, age, and vegetation structure. Shortleaf pine was a common canopy replacement 

tree along with black oak (Quercus velutina), white oak (Quercus alba), and hickories (Carya

spp.). The abundance of shortleaf pine appears to be diminishing, however, owing to the 

absence of shortleaf in understory and regeneration layers. The resulting forest probably will 

consist almost exclusively of hardwoods. Shortleaf pine regeneration in canopy openings 

was limited by aspect, seed source, and litter depth. In addition to their current conditions, 

information from these forests provides insight into the future development and management 

needs of younger oak-pine communities. In forests where regeneration and recruitment of 

shortleaf pine are lacking, restoration efforts require timely action because the overstory 

seed source is crucial to preserving the shortleaf pine component. These fi ndings contribute 

to an understanding of shortleaf pine forests, and can ultimately determine restoration and 

management guidelines for shortleaf pine forests in the Missouri Ozarks. 

1

Senior Research Specialist (MCS), Department of Forestry, 

University of Missouri-Columbia, Columbia, MO 65211; and 

Associate Professor (R-MM), Department of Forestry, University of 

Missouri-Columbia, Columbia, MO 65211. MCS is corresponding 

author: to contact, call (573)882-8841 or email at stambaughm@

missouri.edu

INTRODUCTION

Although historic evidence suggests that oak-shortleaf 

pine (Quercus-Pinus echinata Mill.) forests of the Ozark 

region were strongly infl uenced, if not perpetuated, by 

recurring fi res for at least 300 years prior to the 16th 

century (Masters and others 1995, Guyette and others 

2002, Guyette and others 2006), contemporary policies 

and logistics often reduce the occurrence of burning. This 

situation is an important issue to the conservation of many 

fi re adapted species, including shortleaf pine. In general, 

the disturbance regime of shortleaf pine forests has changed 

from one that included fi re to one that primarily excludes 

fi re and is represented by small-scale events (Stambaugh 

and others 2002) that result in canopy gap openings. In 

an attempt to understand the effects of these changes on 

species composition and forest succession, we examined 

canopy gap disturbances and forest stand dynamics of six 

representative uncut and old second-growth oak-shortleaf 

pine forests. Our objectives were to: 1) describe the current 

overstory composition, 2) characterize and quantify the 

frequency of canopy gap disturbances, and 3) identify trends 

in vegetation development within canopy gaps, specifi cally 

addressing the potential for shortleaf pine regeneration and 

recruitment to the overstory.

METHODS

Study Site Descriptions

Study sites were located throughout the Ozark Highlands 

region of southeastern Missouri in an area that occurs 

within the natural shortleaf pine range (Liming 1946). 

Investigations were conducted at the Eck Natural Area, 

Alley Spring, Indian Trails Conservation Area, Greer 

Spring, and two sites on the Mark Twain National 

Forest—one near the town of Bixby and another near 

Slabtown (Table 1). Detailed descriptions of study areas 

were presented in Stambaugh (2001). Study sites were 

selected non-randomly due to the limited availability of 

shortleaf pine forests exhibiting late-successional forest 

characteristics. Guidelines for selecting study sites were: 

1. Average age of dominant overstory shortleaf pines 

> 100 years

2. Forested area greater than 10.1 hectares

3. A minimum of 25 percent overstory composition in 

shortleaf pine

4. No apparent anthropogenic disturbances, i.e., logging 

operations or prescribed burning

5. Some evidence of canopy gap disturbances, as 

refl ected in a multi-structured canopy
60

Data collection

Canopy gap sampling was conducted during 1999 and 2000 

in accordance with guidelines established by Runkle (1992), 

with modifi cation. All gaps were located by systematically 

traversing the study sites. Canopy gaps were defi ned as 

the opening in the overstory forest canopy caused by the 

death of 1-10 trees. All observed canopy gaps 6 years 

old and less were sampled; therefore the data represent a 

complete “inventory” of gaps for each site. For each gap, 

measurements taken included gap size, gap maker(s) (i.e., 

trees that formed the gap), gap age, woody species, litter 

depth, and trees adjacent to the canopy opening. Expanded 

gap size was measured as the distance across the length 

and width of the gap to and from the boles of the trees 

surrounding the gap. Gap size was determined using the 

area of an ellipse. Using these data, we calculated rotation 

interval by summing the entire area in gaps, and dividing by 

six (the number of years in which gaps were considered) to 

create an annual gap area. Annual gap area was then divided 

into the total area of the site to determine the rotation 

interval. Rotation interval represents the number of years 

required for the entire area to be replaced by canopy gaps 

(i.e., disturbance frequency).

Basal increment cores were taken from at least one 

understory shortleaf pine > 1.37 m in height in each gap. 

Increment cores from various trees within the canopy gap 

provided an accurate determination of gap age and were 

used in analyzing recruitment years, growth rates, and the 

potential for shortleaf pine recruitment to the overstory. 

Vegetation Sampling

At randomly determined distances (between 150 and 300 m) 

along transects, the overstory was sampled using the point 

centered quarter method (Cottam and Curtis 1956). The 

nearest live tree to plot center that was > 25 cm diameter at 

breast height (DBH) was measured in each quadrant. The 

tree species, DBH (to the nearest 0.1 cm), and horizontal 

distance from plot center to the center of the stem (to the 

nearest 0.1 m) were recorded. Importance values were 

calculated by summing the relative density, frequency, and 

dominance values (i.e., basal area) for each tree species. 

In canopy gaps all woody stems > 1.37 m in height 

occurring within the expanded gap area were considered 

to be in the understory; stems were identifi ed by species 

and recorded in 2 cm diameter classes. The tallest 

individuals were considered the most probable gap 

replacements if the individual tree had at least 20 percent 

live crown ratio and was well positioned within the 

canopy opening. Replacement tree species were noted, 

and DBH measurements (to the nearest 0.1 cm) and height 

measurements (to the nearest 1 m) were made. If the 

replacement tree was a shortleaf pine, a basal core was taken 

to determine age and growth rate. 

All woody stems < 1.37 m in height occurring within the 

expanded gap area were considered to be in the regeneration 

layer, and four 1-m2

 circular regeneration subplots were 

located equidistant between gap center and the expanded 

gap edge in the four cardinal directions. Within subplots 

all woody species were tallied. Additionally, a one-minute 

timed count was used to determine the number of pine 

seedlings occurring in both the southern and northern half of 

the expanded gap area in order to quantify pine regeneration 

in gaps. The average litter depth of subplots was measured 

(four measurements per subplot) to the nearest cm from the 

top of the O horizon to the top of the litter. The percentage 

of the forest fl oor covered in leaves, needles, and exposed 

area was estimated for the ground surface of the expanded 

gap area. 

RESULTS AND DISCUSSION

Gap Dynamics and Canopy Gap 

Characteristics

Across all six sites, we identifi ed 121 gaps, and the Eck 

Natural Area had the greatest number of canopy gaps of 

any site (n = 48) as well as the greatest mean gap size 

(table 1). The Alley Spring site had the greatest area in gaps 

(522 m2 ha-1). Gap sizes were normally distributed at the 

Eck Natural Area and gaps constituted 4.0 percent of the 

total area. Mean gap size was 421 m2 and sizes ranged from 

104 - 1583 m2. Unlike other sites, the Eck Natural Area 

had a relatively high number of gaps > 500 m2. Canopy 

gap ages showed increasing frequency from recent gaps to 

gaps 6 years old. The majority of the identifi ed canopy gaps 

at Eck Natural Area were created during 1993 and 1994. 

At the Alley Spring site, 28 canopy gaps were identifi ed, 

accounting for 5.2 percent of the total area. Mean gap size 

was 322 m2 and sizes ranged from 105 to 847 m2. 

Indian Trails, Greer Spring and Bixby each had nearly the 

same area in gaps, although we identifi ed 13, 9, and 9 gaps 

respectively from these three sites. Canopy gaps constituted 

1.6 percent of the total forested area at Indian Trails, Greer 

Spring, and Bixby. At Indian Trail, mean expanded gap 

size was 247 m2

 and sizes ranged from 87 to 394 m2. Mean 

expanded gap size for Greer Spring was 323 m2 and sizes 

ranged from 261 to 419 m2, therefore generally larger than 

at Indian Trail. At Bixby, mean expanded gap size was 

241 m2 and gap sizes were more variable than at any other 

site, ranging from 15 to 404 m2.

Fourteen canopy gaps were identifi ed from the Slabtown 

site, constituting 1.8 percent of the total area or 186 m2 ha-1. 

Mean expanded gap size was 148 m2

 and sizes ranged from 

30 to 280 m2. Despite its proximity to the Eck Natural Area 

(~4 km) the relative abundance of gaps from year to year 

showed no similarities between the two sites. Patterns of 

gap formation may be strongly autogenically controlled and 

infl uenced by local weather patterns. 
61

Gap rotation ranged from 115 years to 385 years. Alley 

Spring site had the lowest value and thus would completely 

regenerate via gaps in 115 years. Eck Natural Area would 

regenerate in 152 years. Our estimates indicate that 

Slabtown would regenerate in 323 years, Greer Springs and 

Bixby in 377. Indian Trails has the most protracted turnover 

Site Eck NA Alley Spring IndianTrails Greer Spring Bixby Slabtown

Area (ha) 50.8 17.2 19 18.3 13.6 11.1

Forest Age (~years) 320 200 125 120 160 150

Canopy gaps (n) 48 28 13 9 9 14

Area in gaps (m2

 ha-1) 405 522 156 159 159 186

Mean gap size (m2) 421 322 247 323 241 148

Rotation interval (yrs) 152 115 385 377 377 323

 

Overstory species importance values

Pinus echinata 94.7 93.3 210.1 65.5 71.9 93.3

Quercus velutina 79.3 37.6 37.7 58.2 39.7 82.3

Q. alba 54.5 70.2 32.5 57.2 68.4 57.3

Q. stellata 26.1 40.5 11.9 0 0 28.4

Q. rubra 18.6 0 7.8 0 0 10.1

Q. coccinea 0 22.3 0 34.8 116.2 0

Carya tomentosa 0 0 0 28.5 0 0

C. texana 0 0 0 0 3.8 0

 

Gap replacement trees: sum of trees in all gaps (total number of gaps)

Pinus echinata 43 (19) 15 (10) 11 (5) 0 (0) 5 (4) 5 (3)

Quercus velutina 34 (24) 9 (9) 11 (7) 1 (1) 2 (2) 2 (2)

Q. alba 44 (22) 5 (4) 16 (9) 6 (6) 10 (7) 5 (5)

Q. stellata 5 (4) 2 (2) 0 (0) 1 (1) 0 (0) 0 (0)

Q. rubra 5 (4) 3 (2) 2 (1) 1 (1) 0 (0) 0 (0)

Q. coccinea 0 (0) 6 (5) 1 (1) 0 (0) 4 (4) 0 (0)

Carya spp. 31 (20) 10 (7) 0 (0) 3 (3) 0 (0) 10 (8)

Acer rubrum 1 (1) 0 (0) 2 (1) 0 (0) 0 (0) 0 (0)

Ulmus spp. 4 (2) 1 (1) 0 (0) 1 (1) 0 (0) 0 (0)

 

Percentage of regeneration by tree species in all gaps

Pinus echinata 12.9 0 0 0 0 11

Quercus velutina 16.4 13.6 16.1 10.1 17.4 14.7

Q. alba 13.3 8.1 10.8 0 0 16.6

Q. stellata 0 0 17.2 0 0 0

Q. coccinea 0 0 0 0 12.8 0

Carya spp. 0 13.3 0 8.3 9.3 0

Acer rubrum 0 0 0 17.4 22.1 14.7

Sassafras albidum 19 20.4 8.6 10.1 16.3 15.3

Cornus fl orida 12.3 13.6 20.4 14.7 0 0

Prunus serotina 0 0 0 8.3 0 0

Table 1.—Study site characteristics, overstory composition, canopy gap replacement trees, and percentage of trees species 

regenerating in gaps.

rate. Although calculated, rotation interval represents a 

theoretical successional timeframe. Variation in disturbance 

or stochastic events can alter the rotation interval. Since 

canopy gaps are evident for less than about 10 years in these 

sites, a decadal rotation interval recalculation would provide 

greater predictability of stand dynamics.
62

Vegetation Structure – Existing Overstory 

The fi ve most important overstory species at the Eck Natural 

Area site, in order of importance, were shortleaf pine, black 

oak (Q. velutina Lam.), white oak (Q. alba L.), post oak 

(Q. stellata Wangenh.), and northern red oak (Q. rubra L.) 

(Table 1). Although shortleaf pine made up almost 1/3 of the 

total importance values (IV), as a group, the oaks comprised 

the majority (IV = 59.5). The average DBH of overstory 

trees was 38.2 cm and the largest individual was a black oak 

at 89.0 cm DBH. The majority of the trees were between 

26 and 40 cm DBH. Shortleaf pine was the most abundant 

species at the site followed by black oak. Shortleaf pine was 

the most abundant species in the 25 to 40 cm DBH class, 

and the largest individual was represented in the 55 cm 

DBH class. 

The fi ve most important overstory species at the Alley 

Spring site, in decreasing order of importance, were 

shortleaf pine, white oak, post oak, black oak, and scarlet 

oak (Q. coccinea Muenchh.) (Table 1). As with the Eck 

Natural Area site, shortleaf pine comprised almost 1/3 of 

the total importance values, but the oak group made up the 

majority of total IV. Average DBH of the overstory trees 

was 41.4 cm and the largest individual was a 75.0 cm DBH 

white oak. Shortleaf pine was the most abundant species 

at the site, followed by white oak was. The bell-shaped 

diameter distribution of shortleaf pine (Fig. 1) suggests that 

recent recruitment to the overstory is less than historical. 

At Indian Trails, the overstory consisted only of shortleaf 

pine, black oak, white oak, post oak and northern red oak. 

Shortleaf pine was clearly dominant at the site comprising 

over 2/3 of the total overstory importance values, and 

black oak was second in abundance. Average size of the 

overstory trees was 40.7 cm DBH and the largest individual 

was a 60.8 cm DBH black oak. The most abundant species 

across all size classes was shortleaf pine and its diameter 

distribution was somewhat bell-shaped (Fig. 1) with its 

greatest abundance occurring in the 40 cm DBH class. 

The fi ve most important overstory species at the Greer 

Spring site, from most to least important, were shortleaf 

pine, black oak, white oak, scarlet oak, and mockernut 

hickory (Carya tomentosa [Poir.] Nutt.) (Table 1). Similar 

to the Eck Natural Area and Alley spring sites, shortleaf 

pine was the most important species, but oaks constituted a 

majority (IV = 50.1 percent). Average size of the overstory 

trees was 38.3 cm DBH and the largest individual was 

a white oak at 74.7 cm DBH. The bell-shaped overstory 

distribution of shortleaf pine was best represented by the 35 

cm DBH class (Fig. 1). 

Scarlet oak dominated the Bixby site and comprised over 

1/3 of the total importance values (Table 1). Shortleaf 

pine, white oak, black oak, and black hickory followed 

in importance. As a group, oaks accounted for nearly 75 

percent of IV totals. Average size of the overstory trees was 

34.3 cm DBH and the largest individual was a 55.6 cm DBH 

white oak. Shortleaf pine had the highest abundance in the 

smallest DBH class (Fig. 1), and its abundance decreased 

sharply until the 40 cm DBH class, above which it was 

absent. 

The fi ve most important overstory species at the Slabtown 

site, listed from most to least important, were shortleaf 

pine, black oak, white oak, post oak, and northern red oak 

(Table 1). Similar to the Eck Natural Area, Alley spring, 

and Greer spring sites, shortleaf pine made up almost 1/3 of 

all importance values, however oaks made up the majority 

of all importance values (59.4 percent). Average size of the 

overstory trees was 35.1 cm DBH and the largest individual 

was a white oak at 61.7 cm DBH. Shortleaf pine was the 

most abundant species in the smallest size class and its 

diameter distribution resembled a reverse J-shape (Fig. 1). 

Vegetation Structure – Canopy Gap 

Understory and Regeneration

Eck Natural Area

Shortleaf pine was the most abundant gap replacement tree 

species at the Eck Natural Area followed by white oak and 

black oak; however, black oak occurred in more canopy 

gaps than did any other species (Table 1). Other overstory 

trees that occurred in gaps included hickories (Carya spp.), 

black tupelo (Nyssa sylvatica Marsh.), post oak, and elm 

(Ulmus spp). Post oak and shortleaf pine both showed 

somewhat bell-shaped diameter distributions (Fig. 1), 

suggesting that levels of current recruitment to the overstory 

are reduced compared to historical levels. Shortleaf pine 

exhibited the greatest number of stems in the 2- to 12-cm 

DBH classes. White oak had the second highest abundance 

in the smallest diameter class of all other tree species. 

Both white oak and black oak showed an approximately 

75 percent reduction in stem density from the 0- to 2-cm 

DBH class with stem density from the 2- to 12-cm DBH 

class was relatively consistent. 

Regenerating tree species at the Eck Natural Area included 

sassafras (Sassafras albidum Nees and Eberm.), black oak, 

white oak, shortleaf pine, and fl owering dogwood (Cornus 

fl orida L.) (Table 1). Sixteen other species accounted for the 

remaining 26.1 percent of the regeneration. 

Pith dates of shortleaf pines occurring in canopy gaps at 

the Eck Natural Area site were concentrated around the 

years 1935 to 1950, an era following the Dust Bowl and 

corresponding with a signifi cant reduction in state-wide 

wildland fi re occurrences. Shortleaf pine establishment in 

gaps decreased gradually both prior to and following this 

period. Other than one individual, no pines dated prior to 

1920 or after 1965. The average diameter and height of 

understory shortleaf pines that were recruiting to canopy 

openings was 10.1 cm DBH and 13.6 m, respectively. 
63

Figure 1.—Diameter distributions of shortleaf pine in the overstory (left column) and understory (right column) 

of the six study sites. DBH classes begin with the label value.
64

Average age of these trees was 59 years old and ranged from 

38 to 80 years, with the exception of one individual at 147 

years old. Twelve of 31 understory shortleaf pines cored 

showed a growth release due to canopy gap disturbances. 

Released trees occurred in canopy gap sizes that ranged 

from 200 to 700 m2

 in size.

Alley Spring 

The most abundant species in the understory of canopy 

gaps of Alley Spring were hickories, black tupelo, shortleaf 

pine, white oak, scarlet oak, black oak, and elms. This is the 

same suite of species that was identifi ed at the Eck Natural 

Area site but with the addition of scarlet oak. Similar to 

the Eck Natural Area site, shortleaf pine’s abundance was 

characterized by a bell-shaped distribution. It was the 

most abundant gap replacement tree species, followed by 

hickories and black oak (Table 1). Shortleaf pine was also 

found in more gaps than any other species, though it was 

absent from the regeneration.

At Alley Spring, sassafras, fl owering dogwood, black 

oak, hickories, and white oak (Table 1) were present 

as regeneration in gaps. Twenty-two other tree species 

accounted for the remaining 31 percent of regenerating tree 

species identifi ed at Alley Spring.

Pith dates of shortleaf pines occurring in canopy gaps were 

most frequent during 1925 and 1935 and all understory 

pines sampled were established between 1915 and 1955. 

The bell-shaped diameter distribution (Fig. 1) and pith 

dates were similar to those from the Eck Natural Area, 

again suggesting a recent decrease in pine regeneration or 

successful recruitment to the understory. The average age 

of understory pines was 55 years and ranged from 31 to 84 

years. Annual growth rates of understory pines ranged from 

0.02 to 6.77 mm/yr and the average annual growth rate was 

1.00 mm/yr, an extremely slow growth rate compared to its 

potential. Six of 24 understory shortleaf pines cored showed 

growth releases as result of the canopy opening and these 

trees occurred in gaps ranging from the 200 to 500 m2

.

Indian Trails 

The most abundant tree species occurring in the understory 

of canopy gaps at the Indian Trails site were red maple 

(Acer rubrum L.), hickories, black tupelo, shortleaf pine, 

white oak, black oak, and post oak. Shortleaf pine and post 

oak diameter distributions were similar to those at the Eck 

Natural Area and Alley Spring sites. White oak and black 

oak showed bimodal distributions. Overall, black oak was 

the most common species found in canopy gaps at the 

Indian Trails site. Post oak, with a similar distribution to 

shortleaf pine, was represented by increasing abundance 

from the 0- to 10-cm DBH class with the majority of the 

stems occurred from the 6- to 10-cm DBH classes. White 

oak was the most abundant gap replacement tree species 

(n = 16) followed by shortleaf pine and black oak (n = 11) 

equally. White oak was found in more gaps than any other 

species followed by black oak and shortleaf pine (Table 1). 

The most abundant regenerating tree species in canopy gaps 

at the Indian Trails site, listed from most to least abundant, 

were fl owering dogwood, post oak, black oak, white oak, 

and sassafras (Table 1). Five other species comprised 

the remaining 26.9 percent of regenerating tree species 

identifi ed. The diameter distribution of understory shortleaf 

pine was bell-shaped (Fig. 1) with no individuals recorded 

in the 0- to 6-cm DBH class.

Greer Spring

Shortleaf pine was absent as a gap replacement species 

in canopy gaps at Greer Spring. Red maple, sugar maple 

(A. saccharum Marsh.), hickories, black tupelo, white 

oak, northern red oak, and elm spp. were common. The 

dominance of mesic species such as red maple and sugar 

maple and the absence of shortleaf pine (Fig. 1) and post 

oak in canopy gaps distinguish this site from the others. 

Black tupelo showed the greatest abundance in the smallest 

diameter class; red maple and hickory had similar, yet 

smaller abundance. White oak was the most abundant gap 

replacement tree species followed by hickories.

The fi ve most abundant regenerating tree species in canopy 

gaps at Greer Spring, listed from most to least abundant, 

were red maple, fl owering dogwood, sassafras, black 

oak, and hickories and black cherry (Table 1). Twelve 

other species comprised the remaining 31.1 percent of the 

regenerating tree species.

Bixby 

Red maple, hickories, black tupelo, shortleaf pine, white 

oak, scarlet oak, and black oak were the most commonly 

occurring species in canopy gaps at the Bixby site (Table 1). 

Shortleaf pine and white oak distributions were somewhat 

bimodal, both showed greatest abundance at the 0- and 6- to 

10-cm DBH range. With the exception of species occurring 

only in the understory, red maple was the most abundant, 

followed by hickories and shortleaf pine. White oak and 

shortleaf pine were the only species represented in all DBH 

classes and they were the fi rst and second most abundant 

species in diameter classes > 6 cm DBH. White oak was the 

most abundant gap replacement tree species, followed by 

shortleaf pine, scarlet oak, and black oak (Table 1). 

The fi ve most abundant regenerating tree species in 

canopy gaps at the Bixby site, listed from most to least 

abundant, were red maple, black oak, sassafras, scarlet 

oak, and hickories (Table 1). Five other species comprised 

the remaining 22.1 percent of regenerating tree species 

identifi ed.

Pith dates of shortleaf pines occurring in canopy gaps of the 

Bixby site were most abundant in the 1940s, though only 
65

10 trees were sampled from the understory layer because 

of the small number of gaps. Average age of shortleaf pines 

in the understory was 55 years. The abundance of pine 

regeneration was greatest between 1930 and 1940, as with 

the Eck Natural Area and Alley spring sites. No pith dates 

were represented prior to the 1930 class. Annual growth 

rates of understory shortleaf pines ranged from 0.03 to 3.66 

mm/yr and the average annual growth rate was 0.96 mm/yr. 

Two of nine understory shortleaf pines cored showed growth 

releases as result of the canopy gap opening. Both trees 

were located in gaps with areas of 100 m2

.

Slabtown

The most abundant tree species occurring in the understory 

layer in canopy gaps at the Slabtown site were red maple, 

hickories, shortleaf pine, white oak, black jack oak, black 

oak, and elm species (Table 1). This site is the only one 

to include black jack oak among the seven most abundant 

overstory tree species occurring in the understory of gaps; 

its presence is indicative of a site with dry, sterile soils 

(Harlow and others 1991). Diameter distributions were 

somewhat similar for all species; and hickories, shortleaf 

pine, black jack oak, and elm species. were represented by 

a reverse J-shaped distribution. Hickories were the most 

abundant gap replacement species, followed equally by 

shortleaf pine and white oak (Table 1). Hickories were 

found in more gaps than were any other species (n = 8), 

followed by white oak (n = 5) and shortleaf pine (n = 3). 

The fi ve most abundant regenerating tree species in canopy 

gaps at the Slabtown site, from most to least abundant, were 

white oak, sassafras, black oak and red maple, and shortleaf 

pine. Thirteen other species comprised the remaining 

27.7 percent of the regenerating tree species identifi ed. 

The greatest number of pith dates of shortleaf pines in 

canopy gaps at Slabtown occurred in the 1970 class. 

Average age of shortleaf pines in the understory of canopy 

gaps was 43 years. The oldest pith date was represented in 

the 1890 class and the youngest in the 1980 class. Pith dates 

occurring in the last 30 years were more common at the 

Slabtown site than at any other site. Pith dates of shortleaf 

pines at the Slabtown site were represented during the years 

of common regeneration at other sites (1930 to 1940); 

however, the greatest number was from 1960 to 1975. 

Annual growth rates of understory shortleaf pines ranged 

from 0.03 to 3.91 mm/yr and the average annual growth 

rate was 0.90 mm/yr. Two of 12 understory shortleaf pines 

cored showed growth releases as result of the canopy gap 

disturbance. Released understory shortleaf pines occurred in 

gaps with areas of 200 m2

.

Shortleaf Pine Regeneration

Shortleaf pine regeneration was absent from all canopy 

gaps at four of the six study sites. Despite the presence of 

shortleaf pine in the overstory, the two sites with shortleaf 

pine regeneration had a substantial component of black 

oak, white oak, and, in one case, red maple regeneration. 

Sassafras and fl owering dogwood were abundant in 

the regeneration layer and likely imparted competitive 

effects (e.g., shading, resource competition) on shortleaf 

regeneration. Interestingly, several of these species (e.g., 

sassafras, fl owering dogwood, red maple) are very fi re 

intolerant and could be effectively reduced through 

prescribed burning. 

Gap size is likely one of the most important variables 

controlling pine regeneration. We observed that the 

maximum number of shortleaf pine seedlings regenerating 

can increase by approximately eight times from smaller 

(e.g., 400 m2

) to larger (1700 m2) canopy openings 

(Stambaugh and Muzika 2004). Larger gaps likely increase 

the potential for shortleaf pine regeneration because there 

is lowered leaf area, increased light, less leaf litter limiting 

seedling establishment, and increased temperatures at the 

forest fl oor that perhaps accelerate litter decomposition 

and minimize damping-off (Liming 1945). Certainly, an 

important consideration for regeneration is the presence 

of available seed trees. Seedling abundance in subplots 

increased with the number of overstory pines surrounding 

the canopy gap. The average number of pine seedlings 

increased by approximately three seedlings per 100 m2 as 

the number of overstory shortleaf pine trees surrounding 

the gap increased from zero to one tree. Additionally, the 

average number of shortleaf pine seedlings per 100 m2

increased by approximately nine seedlings as the number of 

overstory shortleaf pine trees surrounding the gap increased 

from two to three trees.

Shortleaf pine regeneration was highest near azimuth of 

200 degrees (SSW) and decreased consistently as aspects 

deviated from 2000 (Fig. 2). The majority of shortleaf 

pine regeneration occurred on aspects between 150 to 

2600 (e.g. south southwest to west), and no regeneration 

occurred between approximately 325 and 1100 (north 

northwest to northeast). Outlying regeneration data were fi t 

to a third-order polynomial to show the potential bound of 

regeneration by aspect (Fig. 2).

Litter depth plays an important role in limiting shortleaf 

pine regeneration (Grano 1949). Shortleaf pine seedlings 

were found on litter depths of 0 to 6 cm and the greatest 

abundance of shortleaf pine regeneration was found on a 

litter depth of 2.5 cm (Fig. 3). The number of regenerating 

pine seedlings continually decreased as litter depth 

increased from 2.5 to 6 cm. No pine regeneration was found 

in subplots where litter depths exceeded 6 cm, and the type 

of litter was not found to be important.
66

Shortleaf Pine Recruitment

The relationship between diameter and height was analyzed 

for shortleaf pines occurring in the understory layer of 

canopy gaps. For trees from all sites that were probable gap 

replacements, a positive linear relationship existed (r2 = 

0.72; p < 0.01). The size of gap-replacing trees was variable, 

depending on the size of all other competitors. For this 

reason the variability in trees sizes was large ranging from 

1.7 to 24.9 cm DBH and from 2 to 17 m in height. Nongapreplacing trees showed a diameter-height relationship 

similar to gap-replacing trees up to about 10 cm DBH or 

10 m in height. Few nongap-replacing pines were 

represented above this size. 

Shortleaf has the potential to persist in the understory for 

long periods of time (e.g., 80+ years) (Stambaugh 2001). 

Many of these trees have weak epinastic control as result 

of a prolonged suppression beneath high shade (Oliver and 

Larson 1996) resulting in “crooked” or fl at tops. Much 

of the understory shortleaf pine observed in canopy gaps 

originated between 1930 and 1955. An informal survey of 

many more understory pines throughout the Ozarks found 

similar periods of origin and growth form (Stambaugh, 

unpublished data). Not only was this period relatively dry, 

but it also corresponded with extensive burning. Ringwidths of shortleaf pine trees growing in gaps were about 

1 mm/year on average. This rate is extremely slow 

compared to the potential rates of open-grown pines (i.e., 

ring-widths of 5 mm/year). Shortleaf pine trees showed 

growth increases in response to small (e.g., 200 m2

) canopy 

openings, which result from mortality of a single-tree. 

However, the duration of increased growth was not tracked 

and is likely short-term, particularly in smaller gap sizes. 

Figure 2.—Shortleaf pine seedling abundance and aspect 

of the subplots. Data are from all sites combined. The 

polynomial line was fi t to outlying regeneration points to 

show the potential bound of regeneration across subplots.

Figure 3.—Relationship between litter depth and shortleaf 

pine abundance in regeneration subplots. Data are from all 

sites; each point represents an individual subplot.

CONCLUSIONS

This study describes the vegetative status of six pine 

forests that are in mid-transition towards being replaced 

by hardwoods. Overall, this study suggests that natural, 

noncatastrophic canopy gap disturbances are not suffi cient 

to maintain an overstory composition of shortleaf pine. In 

general, canopy gap disturbances do not have the effects on 

the understory or regeneration layer needed for sustaining 

the processes of regeneration and recruitment of shortleaf 

pine to the overstory. Small-scale disturbances such as 

canopy gaps appear to support the transition to forests 

dominated by hardwood species, particularly black oak, 

white oak, and hickories. The forest stand dynamics of 

these forests are similar to a mature pine stand studied by 

Shelton and Cain (1999), in which pines were described 

as being rapidly replaced by shade-tolerant hardwoods. 

This transition in forest composition is relatively common 

throughout the Ozark Highlands and likely represents an 

effect of lowered disturbance frequency, primarily fi re.

ACKNOWLEDGMENTS

This study was partially funded by the Natural History 

Division of the Missouri Department of Conservation and 

the University of Missouri Conservation Biology Program. 

The authors thank Karen Kramer and the Missouri Natural 

Areas Committee for their commitment and support for this 

research; Richard Guyette, Dan Dey, and Gary Oakley for 

guidance and technical support; and Justin Wiles and Erin 

McMurry for fi eld assistance.
67

LITERATURE CITED

Cottam, G.; Curtis, J.T. 1956. The use of distance measures 

in phytosociological sampling. Ecology. 37: 451-460.

Grano, C.X. 1949. Is litter a barrier to the initial 

establishment of shortleaf and loblolly pine 

reproduction? Journal of Forestry. 47: 544-548.

Guyette, R.P.; Muzika, R.; Dey, D.C. 2002. Dynamics of an 

anthropogenic fi re regime. Ecosystems. 5: 472-486.

Guyette, R.P.; Spetich, M.A.; Stambaugh, M.C. 2006. 

Historic fi re regime dynamics and forcing factors in the 

Boston Mountains, Arkansas, USA. Forest Ecology and 

Management. 234: 293-304.

Harlow, W.M.; Harrar, E.S.; Hardin, J.W.; White, F.M. 1991. 

Textbook of dendrology. New York, NY: McGraw-Hill. 

501 p.

Liming, F.G. 1945. Natural regeneration of shortleaf pine 

in the Missouri Ozarks. Journal of Forestry. 43(5): 

339-345.

Liming, F.G. 1946. The range and distribution of shortleaf 

pine in Missouri. Tech. Pap. 106. Columbus, OH: U.S. 

Department of Agriculture, Forest Service, Central 

States Experiment Station. 4 p.

Masters, R.E.; Skeen, J.E.; Whitehead, J. 1995. Preliminary 

fi re history of McCurtain County Wilderness Area 

and implications for red-cockaded woodpecker 

management. In: Kulhavy, D.L.; Hooper, R.G.; Costa, 

R., eds. Redcockaded woodpecker: recovery, ecology 

and management. Nacogodoches, TX: Stephen F. 

Austin State University,Center for Applied Studies, 

College of Forestry: 290-302.

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

New York, NY: John Wiley and Sons. 520 p.

Parker, A. 1982. The topographic relative moisture index: 

an approach to soil-moisture assessment in mountain 

terrain. Physical Geography. 3: 160-168.

Runkle, J. 1992. Guidelines and sample protocol for 

sampling forest gaps. Gen. Tech. Rep. 283. Portland, 

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

Pacifi c Northwest Research Station. 44 p.

Shelton, M.G.; Cain, M.D. 1999. Structure and short-term 

dynamics of the tree component of a mature pine-oak 

forest in southeastern Arkansas. Journal of the Torrey 

Botanical Society. 126(1): 32-48.

Stambaugh, M.C. 2001. Forest canopy gap dynamics 

in shortleaf pine forests of the Ozark Highlands. 

Columbia, MO: University of Missouri. M.S. thesis. 

186 p. 

Stambaugh, M.C.; Muzika, R.; Guyette, R.P. 2002. 

Disturbance characteristics and overstory composition 

of an old-growth shortleaf pine (Pinus echinata Mill.) 

forest in the Ozark Highlands, Missouri, USA. Natural 

Areas Journal. 22: 108-119.

Stambaugh, M.C.; Muzika, R. 2004. Promoting shortleaf 

pine: canopy openness and pine regeneration in 

closed canopy forests. Forestry Research Note, Report 

#7. Jefferson City, MO: Missouri Department of 

Conservation. 2 p.
68

SHORTLEAF PINE: A SPECIES AT RISK?

Charles G. Tauer, Shiqin Xu, C. Dana Nelson, and James M. Guldin1

1

Professor (CGT), Department of Natural Resource Ecology and 

Management, Oklahoma State University, Stillwater, OK 74078; 

PhD student (SX), Department of Natural Resource Ecology and 

Management, Oklahoma State University, Stillwater, OK 74078; 

Research Geneticist and Project Leader (CDN), Southern Institute 

of Forest Genetics, USDA Forest Service, Saucier, MS 39574, 

Supervisory Ecologist and Project Leader (JMG), Southern 

Research Station, USDA Forest Service, P.O. Box 1270, Hot 

Springs, AR 71902. CGT is corresponding author: to contact, call 

(405) 744-5462 or email at chuck.tauer@okstate.edu

ABSTRACT.—Since the 1950s the existence of natural hybrids between shortleaf pine 

and loblolly pine has been recognized and reported in the literature. In a range-wide study 

of isoenzyme diversity in shortleaf pine, we found 16 percent of the trees from western 

populations were hybrids, based on the isocitrate dehydrogenase (IDH) locus. In stands 

thought to be pure shortleaf pine in west central Arkansas (Mt. Ida), we found 15 percent of the 

trees were hybrid. As a follow-up study to confi rm or discount these results, we sampled native 

stands across Montgomery County, Arkansas, including the Mt. Ida area. These stands were 

mixed loblolly pine and shortleaf pine in the southeast part of the county and pure shortleaf 

pine in the northwest corner. In these stands we again found (1) a relatively high percentage 

of hybrid trees (14 percent); (2) hybrids in shortleaf pine stands beyond the natural range of 

loblolly pine; (3) introgression occurring in both directions; and (4) the IDH locus a reliable 

marker for species and hybrid determination. We are now engaged in a range-wide study 

of both loblolly pine and shortleaf pine to examine the cause and consequences of natural 

hybridization between these two species.

INTRODUCTION

Both loblolly pine (Pinus taeda L.) and shortleaf pine 

(Pinus echinata Mill.) have extensive ranges across the 

southeastern United States. A large portion of these ranges 

are sympatric, allowing for possible hybridization between 

the two species. The probable existence of natural hybrids 

between loblolly pine and shortleaf pine has been a topic 

of discussion and concern since at least the early 1950s 

(Zobel 1953). Prior to the 1950s, Schreiner (1937) reported 

that viable artifi cial hybrids of shortleaf pine X loblolly 

pine had been produced at the Institute of Forest Genetics 

in California. In a later report, Little and Righter (1965) 

documented that this cross was fi rst made in 1933. These 

artifi cially produced crosses demonstrated the possibility 

that naturally occurring hybrids might exist. These two 

species are normally isolated from each other by time of 

strobili maturity (Mergen and others 1963), but early on 

Zobel (1953) noted the possibility of environmentally 

induced overlapping maturity. The questions then became, 

how high is the level of hybridization across the ranges of 

loblolly pine and shortleaf pine, and what effect, if any, 

will hybridization have on the long-term integrity of each 

species?

Early Morphological Studies

Artifi cial Hybrids

Early studies of shortleaf pine X loblolly pine hybrids 

necessarily relied on morphological traits. Characterization 

of artifi cial hybrids showed that the F1 trees were generally 

intermediate formany of the traits examined. Little 

and Righter (1965) described the F1 hybrids as looking 

something like a loblolly pine with small cones with stout, 

sharp prickles, intermediate needle anatomy, and two or 

three needles per fascicle. Snyder and Hamaker (1978) 

reported shortleaf pine X loblolly pine hybrids to be 

distinct and intermediate using a multivariate trait value 

based on needle characteristics. They reported that the 

traits most useful in identifying individuals as hybrids were 

needle length, fascicle sheath length, number of rows of 

stomata, needle diameter, and stomata/cm. In a summary 

paper, Schultz (1997) reported that the hybrids tend to be 

intermediate to their parents for growth and survival.

Perhaps the most extensive and thorough study of artifi cial 

hybrids was conducted by Mergen and others (1965). They 

examined nine needle traits, fi ve twig traits, six bud traits, 

three male strobili traits, and three cone traits on 40 F1

trees grown across three locations. They compared these 

F1 hybrids to an approximately similar number of open 

pollinated parent tree offspring at each site. They reported 

several interesting results, including a large environmental 

effect, such that mean values for traits in one environment 

for either parent or F1 could overlap values for the other 

groups in other environments. At the same time, they noted 

a general tendency for intermediate values for the hybrids 

for most traits. They also noted, as had Little and Righter 
69

(1965), that for vegetative traits the hybrids tended to look 

more like loblolly pine than shortleaf pine. Mergen and 

others (1965) then examined all possible combinations of 

traits using pictorialized scatter diagrams (Anderson 1949) 

to determine which best distinguished the hybrids and the 

two parents. They found that by using needle length and 

fascicle sheath length as the two axes, and sheath type 

(smooth to rough), length to width ratio of the axillary 

scale, and twig color for the plotted points, the parents were 

clearly separated on the plots. They also reported that these 

scatter diagrams resulted in the hybrids being placed in a 

generally intermediate position. They concluded that in spite 

of large environmental infl uences on trait variability, the F1

hybrids could be distinguished from the parent species using 

this combination of traits.

It is of interest to note that all the reported studies of 

artifi cial hybrids were of trees from the cross of shortleaf 

pine X loblolly pine, i.e., with shortleaf pine as the 

female parent. Various levels of diffi culty in making the 

reciprocal cross have been reported, from no seed (our data, 

unpublished) to few (0.2 seed/fl ower) seed (Snyder and 

Squillace 1966), to not a serious problem (Richard Bryant, 

pers. commun. 2003). Little and Righter (1965) did report 

that the Institute of Forest Genetics in California produced 

the reciprocal cross in 1948, but apparently no information 

has been published concerning growing the offspring. 

Clearly, since loblolly pine male strobili shed pollen several 

weeks earlier than shortleaf pine, using shortleaf pine as the 

female is the easier cross, as pollen storage is not required. 

What is not clear is if the reciprocal cross is diffi cult 

because of logistics, or if some sort of incompatibility is 

involved. 

Putative Hybrids

When putative hybrid individuals were found in the fi eld, 

the use of morphological traits deemed useful for artifi cial 

hybrids was not as defi nitive. For example, when Mergen 

and others (1965) applied their set of traits to putative 

hybrids from two fi eld populations, they were able to clearly 

separate the parents, but only 14 of the 62 individuals 

identifi ed as putative hybrids fell in their hybrid category. 

They noted that the putative hybrids, although generally 

intermediate, tended to be similar to shortleaf pine in 

reproductive morphology, but resembled loblolly pine in 

vegetative traits. They speculated that some of the putative 

hybrids were backcrosses, as had Zobel (1953) in his report 

concerning the possible existence of natural shortleaf pine X 

loblolly pine hybrids.

Hicks (1973) took a statistical approach to the question 

of the most appropriate traits to use in identifying hybrid 

individuals. He measured six needle traits, three twig traits, 

and three cone traits, then calculated within-tree means 

and variances to allow estimation of sample sizes required 

to estimate within-tree means to within 5 percent of the 

original sample mean. He concluded that needle width, 

axillary scale width, and cone width required prohibitively 

large sample sizes, while terminal bud length and number 

of stomatal rows showed limited variability. Of the traits he 

measured, he found needle length, fascicle sheath length, 

number of needles per fascicle, terminal bud width, cone 

length, and seed weight to be most useful in distinguishing 

shortleaf pine, loblolly pine, and their hybrids.

One of the reasons the existence of these hybrids was of 

interest is illustrated by the work of Abbott (1974). Based 

on the presence of an “atypical” loblolly selection in the 

Oklahoma State University seed orchard, he examined 19 

loblolly and 12 shortleaf orchard selections as possible 

hybrids. It is generally agreed that hybrids are undesirable in 

seed orchards. All the trees he examined were from extreme 

southeast Oklahoma (i.e., McCurtain County), or adjacent 

counties in Oklahoma, Texas, or Arkansas. This area 

represents the far northwestern edge of the range of loblolly 

pine. Based on the work of Hicks (1973), and conversations 

with him, Abbott chose to measure needle length, number 

of needles per fascicle, cone length, number of seeds per 

gram, and fascicle sheath length, and then constructed a 

hybrid index. He found that the atypical loblolly pine was 

intermediate for all traits, as were three of the shortleaf pine 

orchard selections. He concluded that hybridization must 

occur relatively frequently in the sample area.

Cotton and others (1975), looking for the existence of 

natural hybrids, conducted a study of trees from 16 stands 

within a 60-mile radius of Nacogdoches, TX. They used 

the same traits as Abbott (1974), except terminal bud width 

instead of number of seeds per gram. They concluded that 

hybrids may exist, but at a low frequency, and attributed 

the existence of intermediate types to the natural range in 

variation found in loblolly pine and shortleaf pine. This 

conclusion would agree with a report by Schoenike and 

others (1977), who found that on the Clemson Experimental 

Forest, SC, putative hybrids occur at a frequency of about 

one in 10,000 trees.

Early Chemical and Molecular Studies

Clearly, either the frequency of hybridization is highly 

variable, or the use of morphological traits is limiting our 

ability to distinguish hybrids from their parent species. 

Researchers thus turned to chemical and molecular methods 

to attempt to resolve these questions. One of the early works 

in this arena was that of Hare and Switzer (1969). They 

conducted an analysis of seed proteins using acrylamide gel 

electrophoresis to compare eastern and western sources of 

loblolly pine to shortleaf pine. With an analysis of banding 

patterns, they reported that eastern loblolly pine showed 34 

percent similarity to shortleaf pine while western sources 

of loblolly pine showed 88 percent similarity to shortleaf 

pine. They concluded that introgression of loblolly pine with 

shortleaf pine is much more frequent in western sources, 

such as in Oklahoma and Texas. Hare and Switzer’s (1969) 

results would suggest that the frequency of hybridization 
70

is variable across the sympatric portion of these species’ 

ranges, in particular, higher in the western part than in the 

eastern part.

Florence and Hicks (1980) used seed megagametophyte 

protein banding patterns to examine putative hybrids of 

these two species sampled in east Texas. Their intent was 

to relate hybridization to fusiform rust resistance, but in the 

process they also were able to use the banding patterns to 

support the hybrid nature of putative hybrids identifi ed by a 

morphology-based hybrid index. They further suggested that 

introgression does occur, and probably in the direction of 

shortleaf pine.

Huneycutt and Askew (1989) screened both species with 20 

isoenzyme systems in an attempt to identify a marker useful 

in distinguishing hybrids. They discovered that the isocitrate 

dehydrogenase (IDH) marker was monomorphic (a single 

allele) and monomeric (a single band) in both species, but 

differed between species by migration distance. They further 

tested the marker in the parent species and known hybrids 

and demonstrated that this was a simple and reliable marker 

to identify fi rst-generation hybrids between loblolly pine 

and shortleaf pine. They also noted that the marker’s utility 

in later generations and backcrosses would be limited by 

normal Mendelian segregation.

Edwards and Hamrick (1995) examined allozyme diversity 

in a wide-ranging sample of shortleaf pine. They screened 

22 loci, including IDH, so they were able to estimate 

the level of hybridization in the 18 populations sampled. 

Of the populations they sampled, 11 were from east of 

the Mississippi River and seven from west of the river. 

They reported a generally high level of genetic similarity 

among all shortleaf pine populations, with one important 

distinction, that the eastern and western populations 

differed signifi cantly in the level of hybridization to loblolly 

pine. The western populations had a higher percentage of 

hybrids (4.58 percent) than the eastern populations (1.09 

percent). What is of considerable interest to us, but was 

not addressed, is that all but one of the western populations 

sampled were outside the accepted range of loblolly pine. 

These shortleaf pine populations are approximately 35 

miles to well over 200 miles distant from the nearest 

natural loblolly pine populations. It is intriguing that these 

populations would show high levels of hybrids. 

In an apparent follow-up study, Edwards and others (1997) 

used IDH to examine hybridization frequency in two 

naturally occurring, sympatric populations of loblolly pine 

and shortleaf pine in northern Georgia. They sampled all 

trees in both populations and reported 8 percent hybrids at 

one site and 0.4 percent hybrids at the second site. Using a 

chloroplast marker, they determined that shortleaf pine was 

the paternal parent (Wagner and others 1992) of all hybrids 

at both sites. They noted that all hybrid trees were juvenile, 

and spatially distant from mature shortleaf pines, supporting 

the paternal contribution of shortleaf pine. Interestingly, 

they also reported that morphologically, the hybrids were 

easily distinguished from loblolly, but not from shortleaf, 

which is contrary to morphological descriptions of artifi cial 

hybrids discussed above. They recognized this discrepancy, 

and suggested that tree morphology may change as the 

hybrid trees matured, or that the hybrids they described 

were backcrosses. Since no mature hybrids were found, 

however, they discounted the second possibility. Perhaps the 

IDH locus is not a reliable marker.

Recent Studies at OSU

At Oklahoma State University (OSU) in the early 1990s, we 

initiated studies (reported by Raja and others 1997, 1998) 

to examine the effect of various management strategies on 

genetic diversity in shortleaf pine. These studies were in 

cooperation with the USDA Forest Service’s Ecosystem 

Management Research on the Ozark and Ouachita National 

Forests. Since this work was started before the Edwards and 

Hamrick (1995) work was reported, we needed to conduct 

an isoenzyme study to characterize the shortleaf pine species 

to support the management study. Our range-wide study of 

isoenzyme diversity in shortleaf pine turned out to be very 

similar to that of Edwards and Hamrick (1995). We sampled 

six western populations and nine eastern populations, and 

although these populations were entirely different from 

the Edwards and Hamrick (1995) samples, our results, in 

terms of the general genetic characterization of the species, 

were in close agreement with their results. However, we 

did note that, based on the IDH locus, more than 16 percent 

of the trees from western populations were hybrids (they 

reported 4.58 percent), while eastern populations showed 

4.45 percent hybrids (they reported 1.09 percent). Although 

three of the western populations were outside the natural 

range of loblolly pine, we found evidence of hybridization, 

on average 10 percent, as did the Edwards and Hamrick 

(1995) study (although their percent of hybrids was lower). 

We cannot explain these differences in estimated level 

of hybridization between the two studies, except to point 

out that the populations sampled were different in number 

of trees sampled per stand, stand locations sampled, and 

time of sampling (we sampled trees from the South-wide 

Southern Pine Seed Source Study [SSPSSS] plantings, 

trees from seed collected in 1951-1952). Consequently, 

we speculated that IDH may not be a reliable marker for 

determining species or degree of hybridization. We then 

sampled stands of shortleaf pine in the Mt. Ida, AR area for 

the Ecosystem Management study, and again noted a high 

number (15 percent) of hybrid trees based on IDH. These 

were trees in what were thought to be pure shortleaf pine 

stands, several miles north of any native loblolly pine trees 

or stands. 

As a follow-up study (Chen and others 2004) to confi rm 

or discount these results, we sampled native pine stands 

across a southeast to northwest transect of Montgomery 

County, AR, which includes Mt. Ida. These stands were 
71

mixed loblolly pine/shortleaf pine in the southeast part of 

the county and pure shortleaf pine, up to 20 miles north of 

the closest known loblolly pine stands, in the northwest 

corner of the county. In this study we used a codominant 

nuclear marker and a chloroplast marker to identify hybrids 

and their paternity, respectively. Of the 80 trees sampled, 

ten (12.5 percent) were found to be heterozygous at the 

nuclear marker locus, i.e. hybrids. Seven of these were 

also confi rmed to be hybrid using the IDH locus. Of the 

remaining three, one was not tested, and one each was 

homozygous for loblolly pine or shortleaf pine. We also 

found one tree heterozygous at the IDH locus, but not at 

the nuclear marker. Since we concluded that some of the 

hybrids were not F1

s, a few of these genotypes would be 

expected. The chloroplast marker showed some of the 

hybrids to be of loblolly pine paternity and some of shortleaf 

pine paternity. Morphological data agreed with the paternity 

analysis in that those of shortleaf pine paternity looked 

more like shortleaf pine, and those of loblolly pine paternity 

looked more like loblolly pine. In this confi rmation study, 

we found (1) a relatively high percentage of hybrid trees 

(14 percent); (2) hybrids in shortleaf pine stands beyond the 

natural range of loblolly pine; (3) introgression occurring in 

both directions; and (4) the IDH locus apparently a reliable 

marker for species and F1

 hybrid determination.

Current Study at OSU

The obvious next questions are: Is this level of hybridization 

management induced, and what effect will such levels 

of hybridization have on the long-term integrity of these 

species? If the current intensive management of loblolly 

pine throughout the sympatric range of these two species 

is in part responsible for the relatively high level of 

hybridization found, there are serious implications regarding 

shortleaf pine management. Since the USDA Forest Service, 

by mandate, is one of only a few organizations in the South 

regenerating shortleaf pine stands, and most often relies on 

forms of natural regeneration to do so, will the potentially 

overwhelming loblolly pine background pollen cloud put the 

future of the shortleaf species at risk? The outcomes from 

this research project will begin to answer these questions, 

and may point to management strategies designed to 

maintain the integrity and diversity of the shortleaf pine 

species. Loblolly pine will probably not be at risk because 

of its varied and active tree improvement and artifi cial 

regeneration programs.

Based on the research and results described above, we 

initiated a study to examine the cause and consequences of 

introgression between shortleaf pine and loblolly pine. The 

objectives of the research are to:

1. Estimate the level of hybridization present in today’s 

native populations of loblolly pine and shortleaf pine.

2. Estimate the level of hybridization present in 1950s 

range-wide samples of loblolly pine and shortleaf 

pine. Samples from the SSPSSS are being used.

3. Compare levels of hybridization from objectives 1 

and 2.

4. Estimate the present day level and direction of 

introgression occurring between these two species.

5. Compare the level of hybridization present in native 

shortleaf pine stands from an area of intensive 

loblolly pine management to that in shortleaf pine 

from relatively undisturbed, continuous, native, 

mixed shortleaf pine/loblolly pine stands. 

STUDY AREAS

Field tissue (needle) collections have been made from 

remaining SSPSSS plantings of both shortleaf pine and 

loblolly pine. These trees represent seed collected in 1951 

and 1952, some 54 years ago, formed at a time when man’s 

infl uence, at least in reference to vast plantings of loblolly 

pine, was minimal. We will match these collections with 

collections from loblolly pine and shortleaf pine trees found 

currently in the “wild” on sites as close as possible to the 

original collection sites of the SSPSSS, at least to within the 

same county. This current day collection will be made from 

the youngest trees found on the site to represent the most 

recent seed fall. These collections will allow us to estimate 

the level of hybridization in these species at present and 

approximately 50 years ago.

METHODS

To meet objective four, we will use the data from the present 

day shortleaf pine and loblolly pine collections and subject 

it to an appropriate analysis (e.g., Anderson and Thompson 

2002). 

To meet objective fi ve, we intend to identify two stands 

meeting the following set of conditions. One stand will be 

native shortleaf pine which has been essentially undisturbed 

by humans, and is surrounded by a large area (thousands 

of acres) also fairly undisturbed, ideally consists of mixed 

shortleaf pine/loblolly pine. The second stand will also be 

an undisturbed native shortleaf pine stand, but this stand 

(100 acres or so) will be surrounded by mostly planted 

loblolly pine (thousands of acres). From these stands we 

will collect seed of about 100 trees each and this seed and 

the resultant offspring will be screened to determine the 

level of hybridization. These comparison stands will both be 

in relatively close vicinity (the same or adjoining counties) 

to avoid problems associated with natural variation in 

hybridization levels observed in stands from across the 

species’ native ranges (Raja and others 1997, Edwards 

and Hamrick 1995). Such stands have tentatively been 

identifi ed.

To date we have characterized the hybrid nature of 

individuals using the IHD isoenzyme locus (Huneycutt and 

Askew 1989), a codominant nuclear ribosomal DNA marker 
72

from the ITS-1 region and a chloroplast marker, both of 

which we developed (Chen and others 2004), and a number 

of simple sequence repeat (SSR) markers developed in Dr. 

Clare Williams’s lab. We intend to utilize these markers in 

this study. We are also evaluating additional SSR markers 

screened at the Southern Institute of Forest Genetics in 

Mississippi, and we have developed a large set of amplifi ed 

fragment length polymorphism (AFLP) markers to ensure a 

comprehensive characterization of every genotype. 

RESULTS TO DATE

To develop our AFLP data set, we screened 48 primer pairs. 

Eighteen of these primer pairs were selected for producing 

multiple and clear bands. These primer pairs were then 

used to screen the SSPSSS shortleaf pine and loblolly pine 

collections. These primers produced polymorphic and 

monomorphic AFLP bands at 794 loci in the shortleaf pine 

samples and 647 loci in the loblolly pine samples. These 

AFLP makers were used to estimate the genetic diversity of 

natural shortleaf pine and loblolly pine populations sampled 

prior to extensive forest management.

The average heterozygosity of shortleaf pine throughout its 

range, west of the Mississippi River, and east of the river 

is 15 percent, 17 percent, and 15 percent, respectively. The 

heterozygosity value of the populations west of the river is 

a little higher than that of populations east of the river. This 

result agrees with the studies of Raja and others (1997) and 

Edwards and Hamrick (1995). The average heterozygosity 

of loblolly pine throughout its range, west of the Mississippi 

River, and east of the river is 12 percent, 12 percent, and 13 

percent, respectively, based on the 647 loci. Both shortleaf 

pine and loblolly pine are outcrossing species, and it is not 

surprising to fi nd high levels of heterozygosity in the natural 

populations especially given that hybridization between 

these two species may contribute to this high heterozygosity. 

Of the numerous AFLPs produced by the 18 primer pairs, 

96 were polymorphic among both the shortleaf pine and 

loblolly pine samples. These 96 AFLPs were produced 

by 17 primer pairs and should be useful in examining the 

hybridization level and the pedigree of hybrids, given the 

appropriate analysis. Preliminary analyses of these data do 

suggest that some of the sample trees are hybrids.

The IDH isoenzyme locus is being screened for all trees 

as a second indicator of trees which may be hybrids. With 

only some of the trees characterized to date, the IDH locus 

has also identifi ed several trees as hybrids. The results from 

IDH and the AFLP markers will be compared to see whether 

these markers are reliable to distinguish shortleaf X loblolly 

hybrids.

By comparing the SSPSSS trees with contemporary trees 

from the same counties, we will be able to estimate with 

considerable reliability the preintensive forestry level of 

hybridization in loblolly pine and shortleaf pine (1950s), 

and the postintensive forestry level of hybridization (2000s) 

across the range of the two species. Sampling of current 

natural regeneration in the SSPSSS counties has just begun.

By comparing seed fall from shortleaf pine in a relatively 

undisturbed area with that of shortleaf pine in an area 

essentially surrounded by loblolly pine plantings, we will 

also be able to compare the level of hybridization which 

occurs under these scenarios. These data will allow some 

insight into the present and potential effect that intensive 

management of loblolly pine is having on the genetic 

integrity of shortleaf pine throughout their sympatric region. 

The pedigree of the hybrids will also be determined, at least 

to the F2

 and BC1 level, or further if the available analytical 

methods and software allow. These samples have not yet 

been collected.

DISCUSSION AND CONCLUSIONS

Since Zobel’s (1953) report of suspected hybrids, the 

collective evidence has proven that natural hybrids between 

loblolly pine and shortleaf pine exist, and that the frequency 

of occurrence of hybrids is greater in populations west of 

the Mississippi River (Edwards and Hamrick 1995, Raja 

et al. 1997, Chen et al. 2004, among others). If the IDH 

locus is a reliable indicator of hybrid trees, it would appear 

that in general all populations of shortleaf pine west of 

the Mississippi River contain some hybrids. Our study 

demonstrating bidirectional introgression would suggest 

that loblolly pine populations are also affected, but to what 

degree is not as well documented. In retrospect, Zobel was 

correct in his suspicion of the existence of natural hybrids 

between these two pine species. We suspect he did not 

know what the consequences of these hybrids might or will 

be, nor do we; however, there are some possibilities worth 

discussion and further study.

It is well known that the natural ranges of loblolly and 

shortleaf pine overlap throughout the South (Little 1971). 

For example, stands in the upper west Gulf Coastal Plain in 

northern Louisiana and south Arkansas, such as are found 

in the Reynolds Research Natural Area on the Crossett 

Experimental Forest in Ashley County, AR, contain both 

species, and loblolly pine dominates these stands while 

shortleaf pine is a minor component of varying occurrence 

(Cain and Shelton 1994). However, early publications based 

on studies at the Crossett Experimental Forest describe the 

stands as “shortleaf-loblolly pine stands” (Reynolds and 

others 1944, Reynolds 1947), which suggests that shortleaf 

pine dominated the mixture in the 1930s. Unwritten 

marking guides for lumber company crews working in these 

mixed forests encouraged retention of the loblolly pine 

and removal of the shortleaf pine, all other things being 

equal, because loblolly pine grows at a slightly faster rate 

than shortleaf pine. But trees one would identify clearly as 

shortleaf pine remain common in these mixed stands. An 
73

interesting question about these stand histories: What are the 

hybridization rates in shortleaf pine in the upper West Gulf 

Coastal Plain? Such a study might be included in the current 

OSU study or a follow-up study as a point of comparison 

with data from the pure shortleaf stands in the Ouachitas.

In this context, the ability of shortleaf pine to retain its 

independent identity in mixed stands on the upper west 

Gulf Coastal Plain suggests that it might also do so in the 

Ouachitas. In both situations, some attributes of shortleaf 

pine per se are ecologically advantageous, or were so prior 

to extensive forest management activity in this region. One 

unusual difference is shortleaf pine’s ability to resprout 

if topkilled by fi re (Mattoon 1915), which confers an 

advantage in establishment if fi re burns through young 

stands containing both species. Shortleaf pine grows more 

slowly but endures competition longer than loblolly pine 

(Lawson 1990). It also is considered to be more tolerant of 

drought and of xeric sites than loblolly pine, which might 

lead to different survival probabilities for the respective 

species if a young mixed-species cohort experienced 

drought, or was established on a xeric site, or both.

It would also seem that the success of a hybrid might relate 

to the attributes that the hybrid inherits from its respective 

parents. A hybrid might grow more rapidly than a pure 

shortleaf pine, or might be slightly less tolerant of fi re or 

drought than its shortleaf pine parent. One can imagine 

ecological circumstances that might discriminate in favor of 

or against the hybrid—such as a reduced ability (compared 

to shortleaf pine) to resprout if top-killed by fi re, or a greater 

ability than a loblolly pine to tolerate drought. Since the 

most interesting silvical difference between shortleaf pine 

and loblolly pine is the aforementioned resprouting ability 

of shortleaf pine, it would be interesting to quantify this 

trait in hybrids. It might also be interesting to follow the 

percent survival of hybrids over time from seed fall, through 

seedling establishment to stand maturity, in stands on xeric 

and mesic sites, to determine if the percent of hybrids 

surviving increases or decreases during stand development.

The pattern of distribution of naturally-regenerated stands 

of shortleaf pine relative to loblolly pine plantations 

throughout the Ouachitas might also affect pollen 

distribution. Generally speaking, loblolly pine plantations 

in the region are on the lower slopes and valleys in the 

region: those lands were the acquired originally by timber 

companies for managing naturally regenerated shortleaf pine 

stands during the 1930s and 1940s because of their higher 

productivity than the stands on upper slopes and ridges, 

which remained (and still exist) in Federal ownership. Thus, 

on landscapes where the two species co-occur today, the 

loblolly pine plantations planted by those timber companies 

or their successors tend to be on lower slopes, whereas 

the shortleaf pine stands tend to be on upper slopes or 

ridges. Position may affect the degree to which natural 

introgression from the earlier shed loblolly pine pollen 

cloud to receptive shortleaf pine fl owers can occur, since the 

introgressing loblolly pine pollen would generally have to 

fl oat uphill. A recent study by Dyer and Sork (2001) showed 

limited pollen movement in a continuous forest due to both 

distance and vegetative structure, but they did not address 

pollen movement in actively managed forests with changing 

canopy structure.

Finally, the major seed orchard for shortleaf pine on federal 

lands in the western Gulf region is located at Mount Ida, 

AR, in terrain not unlike that from which we collected 

samples for the introgression results in the recent OSU 

study. If the prevailing pollen cloud from the hundreds 

of thousands of acres of loblolly pine plantations in the 

region is suffi cient to be considered prevalent at a landscape 

scale, the protective buffers that surround this seed orchard 

might actually provide limited to no protection against 

the possibility of introgression in the dominant source of 

genetically improved shortleaf pine seed for the mid-South. 

Assays of IDH in seed from that orchard or the planting 

stock being raised in nurseries for outplanting might be 

interesting, especially if a test could be produced that might 

be used to cull hybrids from planting stock being distributed 

for outplanting. 

ACKNOWLEDGMENTS

This study is supported by the USDA Forest Service, 

Southern Research Station, Cooperative Agreement SRS 05-

CA-11330126-168 and by the Oklahoma State University 

Agricultural Experiment Station.

LITERATURE CITED 

Abbott, J.E. 1974. Introgressive hybridization between 

shortleaf and loblolly pine in southeast Oklahoma. 

Stillwater, OK: Oklahoma State University. 31 p. 

M.S. thesis.

Anderson, E. 1949. Introgressive hybridization. New York. 

NY: Wiley Publishing Co. 109 p.

Anderson, E.C.; Thompson, E.A. 2002. A model-based 

method for identifying species hybrids using multilocus 

data. Genetics. 160(3): 1217-1229.

Cain, M.D.; Shelton. M.G. 1994. Indigenous vegetation 

in a southern Arkansas pine-hardwood forest after a 

half century without catastrophic disturbances. Natural 

Areas Journal. 14(3): 165-174.

Chen, J.; Tauer, C.G.; Bai, G.; Huang, Y; Payton, M.E.; 

Holley, A.G. 2004. Bidirectional introgression between 

Pinus taeda and Pinus echinata: Evidence from 

morphological and molecular data. Canadian Journal of 

Forest Research. 34(12): 2508-2516.
74

Cotton, M.H.; Hicks, R.R.; Flake, R.H. 1975. Morphological 

variability among loblolly and shortleaf pines of east 

Texas with reference to natural hybridization. Castanea. 

40: 309-319.

Dyer, R.J.; Sork, V.L. 2001. Pollen pool heterogeneity in 

shortleaf pine, Pinus echinata Mill. Molecular Ecology. 

1094(4): 859-866.

Edwards, M.A.; Hamrick, J.L. 1995. Genetic variation in 

shortleaf pine, Pinus echinata Mill. (Pinaceae). Forest 

Genetics. 2(1): 21-28.

Edwards-Burke, M.A.; Hamrick, J.L.; Price, R.A. 1997. 

Frequency and direction of hybridization in sympatric 

populations of Pinus taeda and P. echinata (Pinaceae). 

American Journal of Botany. 84(7): 879-886.

Florence, L.Z.; Hicks, R.R., Jr. 1980. Further evidence 

for introgression of Pinus taeda with P. echinata: 

electrophoretic variability and variation in resistance to 

Cronartium fusiforme. Silvae Genetica. 29(2): 41-43.

Hare, R.C.; Switzer, G.L. 1969. Introgression with shortleaf 

pine may explain rust resistance in western loblolly 

pine. Res. Note SO-88. New Orleans, LA: U.S. 

Department of Agriculture, Forest Service, Southern 

Forest Experiment Station. 2 p. 

Hicks, R.R. Jr., 1973. Evaluation of morphological 

characters for use in identifying loblolly pine, shortleaf 

pine and loblolly X shortleaf hybrids. Castanea. 38: 

182-189.

Huneycutt, M.; Askew, G.R. 1989. Electrophoretic 

identifi cation of loblolly pine-shortleaf pine hybrids. 

Silvae Genetica. 38(3-4): 95-96.

Lawson, E.R. 1990. Pinus echinata Mill., shortleaf pine. 

In: Burns, R.M.; Honkala, B.H., tech cords. Silvics 

of North America: volume 1, Conifers. Agric. Hndbk. 

654. Washington, DC: U.S. Department of Agriculture, 

Forest Service: 316-326. 

Little, E.L., Jr. 1971. Atlas of United States Trees, Volume 

1: Conifers and important hardwoods. Misc. Publ. 1146. 

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

Forest Service. 9 p. plus 200 maps.

Little, E.L., Jr.; Righter, F. I. 1965. Botanical descriptions 

of forty artifi cial pine hybrids. Tech. Bull. No. 1345. 

Washington, D.C., U.S. Department of Agriculture, 

Forest Service. 45 p.

Mattoon, W.R. 1915. Life history of shortleaf pine. Bull. 

244. Washington, D.C.: U.S. Department of Agriculture. 

46 p.

Mergen, F.; Stairs, G.R.; Snyder, E.B. 1963. 

Microsporogenesis in Pinus echinata and Pinus taeda. 

Silvae Genetica. 12: 127-129.

Mergen, F.; Stairs, G.R.; Snyder, E.B. 1965. Natural 

and controlled loblolly x shortleaf pine hybrids in 

Mississippi. Forest Science. 11(3): 306-314.

Raja, R.G.; Tauer, C.G.; Wittwer, R.F.; Huang, Y. 1997. An 

isoenzymatic study of the genetic structure in natural 

populations of shortleaf pine, Pinus echinata Mill. 

Canadian Journal of Forest Research. 27(5): 740-749.

Raja, R.G.; Tauer, C.G.; Wittwer, R.F.; Huang, Y. 1998. 

Regeneration methods affect genetic variation and 

structure in shortleaf pine (Pinus echinata Mill.) Forest 

Genetics. 5(3): 171-178.

Reynolds, R.R. 1947. Management of second-growth 

shortleaf-loblolly pine-hardwood stands. Journal of 

Forestry. 45(3): 181-187.

Reynolds, R.R.; Bond, W.E.; Kirkland, B.P. 1944. Financial 

aspects of selective cutting in the management of 

second-growth pine-hardwood forests west of the 

Mississippi River. Tech. Bull. 861. Washington, DC: 

U.S. Department of Agriculture. 118 p. 

Schoenike, R.E.; Van Lear, D.H.; Benson, J.D. 1977. 

Comparison of shortleaf, loblolly, and putative hybrid 

pines in the piedmont of South Carolina. Silvae 

Genetica. 26(5-6): 182-184.

Schreiner, E.J. Improvement of forest trees. 1937 Yearbook 

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

Agriculture: 1242-1279.

Schultz, R.P. 1997. Loblolly pine: the ecology and culture 

of loblolly pine (Pinus taeda L.). Agric. Handb. 713. 

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

Forest Service: 7–17 and 7–18.

Snyder, E.B.; Hamaker, J.M. 1978. Needle characteristics 

of hybrids of some species of southern pine. Silvae 

Genetica. 27(5): 184-188.

Snyder, E.B.; Squillace, A.E. 1966. Cone and seed yields 

from controlled breeding of southern pines. Res. 

Pap. SO-22. New Orleans, LA: U.S. Department 

of Agriculture, Forest Service, Southern Forest 

Experiment Station. 7 p.
75

Wagner, D.B.; Nance W.L.; Nelson C.D.; Li T.; Patel R.N.; 

Govindaraju, D.R. 1992. Taxonomic patterns and 

inheritance of chloroplast DNA variation in a survey 

of Pinus echinata, Pinus elliottii, Pinus palustris, and 

Pinus taeda. Canadian Journal of Forest Research. 

22(5): 683-689.

Zobel, B.J. 1953. Are there natural loblolly-shortleaf 

hybrids? Journal of Forestry. 51(7): 494-495.
76

TREE SPECIES ASSOCIATIONS OF PINUS ECHINATA MILL. OVER A LARGE-SCALE 

SAMPLING REGIME ON THE INTERIOR HIGHLANDS OF ARKANSAS

James F. Rosson, Jr.1

ABSTRACT.—The Interior Highlands physiographic province of Arkansas is considered the 

ecological center of the geographic distribution of shortleaf pine (Pinus echinata Mill.). I used 

data from the U.S. Forest Service, Forest Inventory and Analysis (FIA) program to identify the 

major tree species associates of P. echinata across this 66,700-km2 landscape. Across the 

region, 41,207 km2 were covered by timberland. The study population was represented by 

434 relatively undisturbed upland sample plots from the 1995 forest survey of Arkansas. 

P. echinata ≥12.7 cm in diameter at breast height (DBH) occurred on 211 of these sample 

plots. Additionally, it ranked fi rst in basal area on 119 plots, second on 39 plots, and third on 19 

plots. Where P. echinata was dominant, stand basal area averaged 23.1 m2 ha-1 (± 0.57 SEM). 

I used chi-square to test for degree of association between the stand dominants and to test 

for positive and negative associations. There was a positive association between P. echinata

and Quercus alba L. (χ2

 = 0.490; 1df). In contrast, there was a negative association between 

P. echinata and Q. velutina Lam. (χ2

 = 15.571; 1df). These results demonstrate that the chisquare test of association is effective even on the larger scales of sampling where lack of 

sample homogeneity may sometimes complicate analysis. Such quantitative tests for species 

associations offer meaningful insights into P. echinata communities at the landscape scale of 

sampling.

1

Research Forester, Southern Research Station, USDA Forest 

Service, 4700 Old Kingston Pike, Knoxville, TN 37919. Author 

contact: call (865) 862-2067 or email at jrosson@fs.fed.us

INTRODUCTION

Shortleaf pine (Pinus echinata Mill.) has an extensive range 

that covers an area from New Jersey to southeast Texas. In 

the northern part of its range, it stretches from New Jersey 

to southern Missouri and eastern Oklahoma. In the southern 

portion of its range, it is found from South Carolina all 

the way to east Texas. Much autecological work has been 

done on P. echinata and a summarization of its silvics can 

be found in Burns and Honkala (1990). Somewhat lacking, 

however, are detailed descriptions of species associates in 

specifi c P. echinata communities. Some of the few botanical 

and silvical descriptions of this species typically offer only 

brief general listings of community associates (Barrett 1995, 

Fralish and Franklin 2002, Harlow and others 1996, Burns 

and Honkala 1990, Eyre 1980, Braun 1950, Vankat 1979). 

Tree species associations are a theme central to much of 

ecological community analysis. These repeating patterns 

of species associations are the basis of the classifi cation 

of vegetation communities. However, species with wide 

ecological amplitude, such as P. echinata, may often have 

different associates over different parts of their range. 

Usually, detailed descriptive work is done on small localized 

studies, often of stands that are unique in some respect such 

as stand history, species rareness, possibility of becoming 

endangered, etc. Lacking are studies that outline specifi c 

tree species associations over large geographic areas. Such 

studies will add to the full complement of information 

necessary to classify vegetation composed of species with 

wide ecological amplitude.

The center of highest ecological development of P. echinata

is in the Interior Highlands physiographic province of 

Arkansas. This area contains the highest concentration of 

P. echinata volume in the U.S. As of the 1995 survey of 

Arkansas, there were 3.8 billion cubic feet of volume in 

P. echinata (Rosson 2002), far above any other state in the 

U.S. Most of the volume is concentrated in Montgomery, 

Scott, Yell, Perry, and Polk Counties, accounting for 43 

percent of all P. echinata volume in Arkansas. Volume and 

relative ecological importance of P. echinata decreases 

north and south of this area. For instance, moving north onto 

the Salem-Plateaus province, the volume of P. echinata in 

Missouri is only 0.8 billion cubic feet (Miles 2006). The 

ecological importance of P. echinata in Arkansas on the 

Interior Highlands presented an opportunity to study its 

primary species associations across this large landscape. The 

objectives of the study were to determine the common tree 

associates of P. echinata across this region and determine 

whether these associations are positive or negative.

METHODS

The inclusive area of the study is the Interior Highlands 

Physigraphic Division in Arkansas (Fenneman 1938). This 
77

Springfi eld-Salem Plateaus

Boston Mountain

Arkansas Valley

Ouachita Mountains

Figure 1.—The four physiographic sections on the Interior 

Highlands of Arkansas (after Fenneman 1938).

area is divided into two provinces, the Ozark Plateaus 

Province and the Ouachita Province. These two provinces 

contain two Sections: the Springfi eld-Salem Plateaus and 

the Boston Mountains Sections in the Ozark Plateaus 

Province, and the Arkansas Valley and Ouachita Mountains 

Sections in the Ouachita Province (Fig. 1). The Interior 

Highlands covers approximately 66,700 km2

 of which 

41,207 km2 are forested. Using GIS software, I selected U.S. 

Forest Service Inventory and Analysis (FIA) plots that fell 

within each of these physiographic regions.

The data came from forest surveys conducted by FIA 

in 1968, 1978, 1988, and 1995. The sample plot study 

population was extracted from these four surveys by the 

following criteria. First, a plot had to fall within the Interior 

Highlands. Second, the plot had to be forested during all 

four surveys. Third and fourth, plots that showed evidence 

of disturbance (e.g. cutting) or were artifi cially regenerated 

were excluded. Fifth, the plot had to occur on an upland site. 

Evidence of cutting disturbance or planting was obtained 

by examination of the repeated-measures plots over time, 

where individual trees were tracked with descriptive tree 

histories. There were 1,179 plots that met the fi rst two 

criteria, and 434 that met all fi ve.

The total plot population, from which the 434 study plots 

were selected, came from a 4.8 km square sample grid. The 

same plots were visited and measured at each of the four 

surveys. Only trees ≥12.7 cm in diameter at breast height 

(DBH) were included in the study. These trees were tallied 

using an 8.6 m2

 per hectare basal area factor (BAF) prism 

on 10 points dispersed over an area of approximately 0.4 

hectares (see Rosson 2002 for more details on sampling 

methods for these Arkansas surveys). Nomenclature follows 

Little (1979).

A 2 x 2 contingency table was used to defi ne the tree species 

associations. The data entry for each cell was the presence 

or absence of two select species on each plot. In this study 

all species that occurred in the 434 sample plots across the 

Interior Highland were compared with P. echinata in the 

contingency table. 

 Species B

 P A 

 Species A P a b m

 A c d n

 r s tot

Where

P = plots where species is present

A = plots where species is absent

a = number of plots species where A and B co-occur

b = number of plots where species A is present and 

species B is absent

c = number of plots where species A is absent and 

species B is present

d = number of plots where species A and species B are 

both absent

m = a + b

n = c + d

r = a + c

s = b + d

tot = total number of plots in sample ( a + b + c + d)

The chi-square test statistic was then applied to the data in 

the 2 x 2 contingency table. This formula includes the Yates 

correction that corrects for bias when any cell in the 2 x 2 

contingency table has an expected frequency of <1 or if two 

or more of the table cells have expected frequencies of <5 

(Zar 1984). 

χ2 = 

The null hypothesis is that the species are independent, 

i.e., there is no association between the two species being 

tested. If the chi-square value is >3.84, the null hypothesis is 

rejected and it is concluded that the species are associated. 

In addition, the chi-square value may be used as a measure 

of the degree of association, the higher the value the 

stronger the association (Causton 1988). There are two types 

of association possible (see Ludwig and Reynolds 1988):

Positive—the pair of species occurred more often than 

expected if independent. a > E(a)

Negative—the pair of species occurred less often than 

expected if independent. a < E(a)

Where

 E(a) = (a+b)(a+c)

N

N[|(ad) – (bc)| – (N/2)2

mnrs
78

Goodall (1953) was the fi rst to measure the association 

between species. The 2 x 2 contingency table with chisquare test of signifi cance is the most commonly used 

approach. Testing for association between species has been 

called association analysis, species association analysis, 

interspecifi c association analysis, and species correlation 

analysis (Ludwig and Reynolds 1988, Causton 1988, 

Kershaw 1973, Greig-Smith 1983). Such species association 

constructions have been used in a variety of contexts beyond 

association analysis. One application is in multivariate 

analysis, where it is commonly applied in various ordination 

techniques. The association between two species is the 

degree and measure to which they occupy the same sample 

sites across the landscape and is an extremely important 

ecological indicator in multivariate techniques (Pielou 1984, 

Gauch 1982, Greig-Smith 1983).

RESULTS AND DISCUSSION

Overstory stand basal area averaged 19.3 m2 ha-1 in the 434 

post-stratifi ed plots on the Interior Highlands. Fifty-two 

tree species ≥12.7 cm DBH were recorded. Often, these 10 

species accounted for just over 90 percent of overstory basal 

area. P. echinata was the most dominant species, accounting 

for 22 percent of basal area, followed by Quercus alba L., 

Q. rubra L., Carya spp. Nutt., Q. stellata Wangenh., 

Q. velutina Lam., Nyssa sylvatica Marsh., Liquidambar 

styracifl ua L., Q. falcata Michx., and Juniperus virginiana

L. (Table 1).

There were some shifts in dominance by physiographic 

regions. P. echinata was strongly dominant in the Ouachita 

Mountains, accounting for 41 percent of basal area. 

Q. alba was second, accounting for 17 percent of basal area. 

Across the Arkansas Valley, P. echinata shared dominance 

with Q. stellata, each species accounting for 20 percent of 

stand basal area. Stand basal area in the Boston Mountains 

averaged 19.5 m2

 ha-1. Q. alba was dominant there, followed 

by Q. rubra, accounting for 25 and 16 percent of basal area, 

respectively. P. echinata was fi fth in dominance, accounting 

for 8 percent of stand basal area in this region. On the 

Salem-Plateaus, Q. velutina was dominant, with 22 percent 

of basal area, followed by Q. alba and Q. stellata with 16 

and 14 percent, respectively. P. echinata ranked sixth there, 

accounting for 9 percent of basal area.

P. echinata’s adaptation to a wide range of soils and sites 

contributes to its wide distribution. It favors and is most 

prevalent on acid soils, but is also very competitive on 

other soils with southern aspects, drier sites, and nutrientdefi cient soils (Burns and Honkala 1990). P. echinata is 

most common on the Ouachita Province, where it is most 

competitive on the numerous southern exposure slopes 

and more acidic soils derived from sandstone bedrock. It 

declines in importance in the provinces to the north probably 

because of habitat limitations—fewer south-exposed slopes 

and more limestone-derived soils. In addition, the degree of 

past disturbance (fi re and cutting) has played a large role in 

the trajectory of forest composition that currently occupies 

the Interior Highlands of Arkansas (Batek and others 1999, 

Chapman and others 2006, Stambaugh and others 2002).

Across the Interior Highlands, P. echinata occurred on 

211 of the 434 upland plots and was the stand dominant 

on 119 plots (Table 2). Q. alba was the leading, second 

dominant tree, on these plots, occurring on 37 sample 

plots. Ranked third in dominance was Q. stellata, occurring 

on 25 plots. By physiographic region within the Interior 

Highlands, P. echinata occurred on 130 of the 152 Ouachita 

Mountain plots, on 26 of the 55 Arkansas Valley plots, on 

41 of the 159 Boston Mountain plots, and on 14 of the 68 

Salem-Plateaus plots.

Across the Interior Highlands the relative stand dominance 

of P. echinata varied. Thirty-eight percent of the plots 

had 50 to 75 percent of basal area in P. echinata, while 

35 percent had basal area in the 25 to 50 percent range. 

Twenty-seven percent had basal area ranging from 75 to 

100 percent. Less than 1 percent of the plots had P. echinata

basal area in the 0 to 25 percent range. In the order of 

ranked dominance, 119 plots had P. echinata as the number 

1 stand dominant, 39 plots had P. echinata ranked second in 

dominance, 19 plots had P. echinata ranked third, and the 

remaining 34 plots had a ranking of fourth or higher in 

P. echinata dominance. (Table 2).

One of the strongest patterns of group associations was 

in the P. echinata—Q. alba—Carya spp. type. Twelve 

percent of all plots were in this category. Stand composition 

of shade-intolerant pine in association with shade-tolerant 

species (oaks and hickories) is most likely a result of stand 

initiation from past disturbance. P. echinata probably 

became established after past logging or natural 

disturbance, but if succession proceeds without further 

disturbance, it will begin to drop out of these stands. 

P. echinata is moderately intolerant as a seedling but 

loses that tolerance after just a few years. Without major 

disturbance, hardwoods will take over the site. P. echinata

may maintain some minor presence by taking advantage 

of canopy gaps and the ability to reach the canopy by high 

growth rates (Barrett 1995). P. echinata stands >100 years 

old begin to deteriorate rapidly and more tolerant hardwoods 

will take over the site without some kind of disturbance 

(Walker 1999). Table 2 illustrates other strong patterns 

described by the fi rst three ranked species. These involve 

P. echinata, Q. alba, Carya spp., and Q. stellata. Involving 

fi rst and second ranked species, there were 32 plots with 

Q. alba, 25 plots with Q. stellata, and 21 plots with Carya

spp. (Table 2), together accounting for 66 percent of all plots 

dominated by P. echinata. Although Table 2 shows only the 

top three dominant species, it illustrates the high variability 

in dominance ranking, especially in the third dominant 

position, and beyond.
79

 Arkansas Boston Salem- Interior

FIA species code and name Ouachita Valley Mountains Plateaus Highland

Average basal area (m2 ha-1)

68 Juniperus virginiana L. 0.153 1.126 0.249 0.847 0.420

110 Pinus echinata Mill. 8.515 3.503 1.585 1.050 4.171

131 Pinus taeda 0.215 0.000 0.027 0.000 0.085

311 Acer barbatum Michx. 0.000 0.000 0.005 0.000 0.002

313 Acer negundo L. 0.000 0.000 0.011 0.000 0.004

316 Acer rubrum L. 0.164 0.109 0.281 0.051 0.182

318 Acer saccharum L. 0.000 0.000 0.325 0.190 0.149

341 Ailanthus altissima (Mill.) Swingle 0.000 0.000 0.005 0.013 0.004

381 Bumelia sp. 0.000 0.000 0.000 0.013 0.002

400 Carya sp. Nutt. 1.256 2.220 2.585 1.669 1.930

404 Carya illinoensis (Wangenh)K.Koch 0.000 0.000 0.005 0.000 0.002

420 Castanea sp. Mill. 0.000 0.000 0.005 0.000 0.002

461 Celtis laevigata Willd. 0.017 0.000 0.000 0.000 0.006

462 Celtis occidentalis L. 0.000 0.000 0.022 0.013 0.010

471 Cercis canadensis L. 0.000 0.000 0.038 0.051 0.022

491 Cornus fl orida L. 0.011 0.000 0.022 0.063 0.022

521 Diospyros virgininana L. 0.017 0.016 0.016 0.000 0.014

531 Fagus grandifolia Ehrh. 0.011 0.000 0.335 0.000 0.127

541 Fraxinus Americana L. 0.057 0.078 0.227 0.266 0.155

544 Fraxinus pennsylvanica Marsh. 0.034 0.031 0.016 0.025 0.026

546 Fraxinus quadrangulata Michx. 0.000 0.000 0.000 0.025 0.004

552 Gleditsia triacanthos L. 0.011 0.031 0.005 0.000 0.010

602 Juglans nigra L. 0.006 0.031 0.076 0.139 0.055

611 Liquidambar styracifl ua L. 0.656 0.891 0.633 0.038 0.581

621 Liriodendron tulipifera L. 0.000 0.000 0.000 0.025 0.004

651 Magnolia acuminata L. 0.000 0.000 0.049 0.025 0.022

682 Morus rubra L. 0.017 0.016 0.011 0.025 0.016

693 Nyssa sylvatica Marsh. 0.549 0.563 0.952 0.392 0.674

731 Platanus occidentalis L. 0.023 0.109 0.059 0.013 0.046

762 Prunus serotina Ehrh. 0.124 0.188 0.130 0.126 0.135

802 Quercus alba L. 3.491 1.673 4.911 2.795 3.672

812 Quercus falcata Michx. 0.436 0.579 0.254 0.683 0.426

813 Quercus falcata var. pagodifolia Ell. 0.023 0.360 0.005 0.000 0.055

823 Quercus macrocarpa Michx. 0.000 0.000 0.000 0.025 0.004

824 Quercus marilandica Muenchh. 0.232 0.266 0.114 0.468 0.230

825 Quercus michauxii Nutt. 0.000 0.000 0.000 0.013 0.002

826 Quercus muehlenbergii Engelm. 0.006 0.063 0.141 0.443 0.131

827 Quercus nigra L. 0.011 0.031 0.005 0.000 0.010

830 Quercus palustris Muenchh. 0.000 0.000 0.005 0.000 0.002

831 Quercus phellos L. 0.028 0.000 0.000 0.000 0.010

833 Quercus rubra L. 1.709 0.813 3.132 1.518 2.087

834 Quercus shumardii Buckl. 0.000 0.016 0.011 0.013 0.008

835 Quercus stellata Wangenh. 1.765 3.440 1.028 2.491 1.821

837 Quercus velutina Lam. 0.837 0.797 1.801 3.832 1.655

901 Robinia pseudoacacia L. 0.006 0.031 0.114 0.038 0.054

931 Sassafras albidum (Nutt.)Nees 0.000 0.000 0.005 0.051 0.010

951 Tilia americana L. 0.017 0.000 0.054 0.051 0.034

971 Ulmus alata Michx. 0.192 0.219 0.103 0.152 0.157

972 Ulmus americana L. 0.062 0.047 0.049 0.051 0.054

973 Ulmus crassifolia Nutt. 0.000 0.016 0.005 0.000 0.004

975 Ulmus rubra Muhl. 0.000 0.031 0.022 0.000 0.012

976 Ulmus serotina Sarg. 0.000 0.078 0.000 0.000 0.010

999 Unidentifi ed trees 0.000 0.016 0.038 0.025 0.020

All species 20.651 17.388 19.472 17.706 19.344

Table 1.—Basal area (m2 ha-1) by species, Interior Highland Physiographic Division, and four Interior Highland Sections; n=434 

for the Interior Highlands, n=152 for the Ouachita Mountains, n=55 for the Arkansas Valley, n=159 for the Boston Mountains, and

n=68 for the Salem-Plateaus. Data are from 1995.
80

 Number Percent of No. 1 No. 2 No. 3

 of plots all plots dominant dominant dominant

 14 11.8 110 802 400

 6 5.0 110 802 835

 5 4.2 110 802 833

 4 3.4 110 802 693

 3 2.5 110 802 837

 1 0.8 110 802 812

 1 0.8 110 802 131

 1 0.8 110 802 611

 1 0.8 110 802 531

 1 0.8 110 802 316

 8 6.7 110 835 400

 5 4.2 110 835 802

 1 0.8 110 835 833

 1 0.8 110 835 693

 3 2.5 110 835 0

 2 1.7 110 835 812

 1 0.8 110 835 131

 1 0.8 110 835 611

 2 1.7 110 835 68

 1 0.8 110 835 762

 7 5.9 110 400 802

 4 3.4 110 400 835

 1 0.8 110 400 833

 1 0.8 110 400 693

 2 1.7 110 400 837

 2 1.7 110 400 131

 1 0.8 110 400 611

 1 0.8 110 400 68

 2 1.7 110 400 824

 1 0.8 110 68 400

 1 0.8 110 68 802

 1 0.8 110 68 835

 1 0.8 110 68 491

 1 0.8 110 68 521

 2 1.7 110 833 400

 1 0.8 110 833 802

 1 0.8 110 833 835

 1 0.8 110 833 0

 1 0.8 110 837 400

 3 2.5 110 837 802

 1 0.8 110 837 693

 1 0.8 110 611 400

 1 0.8 110 611 802

 1 0.8 110 611 833

 1 0.8 110 611 693

 1 0.8 110 611 831

 2 1.7 110 812 802

 1 0.8 110 812 835

 1 0.8 110 812 813

 1 0.8 110 693 835

 1 0.8 110 693 837

 1 0.8 110 693 824

 1 0.8 110 824 835

 1 0.8 110 824 833

 2 1.7 110 131 812

 2 1.7 110 0 0

 1 0.8 110 541 611

 1 0.8 110 971 400

 1 0.8 110 316 0

Table 2.—The number of plots by dominant species. Listed 

are all plots where P. echinata was dominant. The species 

codes in the three dominant categories are identifi ed in the 

species list, Table 1. Data are from 1995; n = 119.

Table 3 shows the chi-square values and the type of 

association for each species in relation to its occurrence 

(or lack thereof) with P. echinata. This chi-square value is 

a measure of the degree of association, where the higher 

the value, the stronger the association (Causton 1988). It is 

also important to consider the number of plots that contain 

neither species. If this cell is 0, then a chi-square value 

cannot be calculated (Kershaw 1973). So, species with wide 

amplitude (typically those that occurred on every plot or a 

high number of plots) may demonstrate a weak chi-square 

value. Examples are Carya spp., where 352 of the 434 plots 

were occupied by this genus; and Q. alba, which occurred 

on 332 sample plots.

Of the 52 tree species tallied on various portions of the 

434 sample plots, P. echinata had a positive association with 

20 of them. The strongest positive associations were with 

P. taeda, Liquidambar styracifl ua, and Q. stellata. In 

contrast, P. echinata had a negative association with 32 

species. However, many of these are the result of much 

too small of a tally. For example, see Acer negundo, 

where it was tallied on only one sample plot. Some of the 

stronger negative associations were A. saccharum, Cercis 

canadensis, Fraximus Americana, Q. muehlenbergii, 

Q. rubra, Q. velutina, and R. pseudoacacia.

An interesting fi nding is that even though different species 

may have the same affi nity for particular site and habitat 

conditions, the species associations between the two may be 

negative. The two species may be in direct competition for 

resource space or there may be something in the past history 

of the site that has given advantage to one species over the 

other. For example, both P. echinata and Q. velutina. prefer 

the same xeric sites and soils, but studies on the Interior 

Highland have shown that P. echinata dominance increased 

with increasing fi re frequency while Q. velutina decreased 

with increasing fi re frequency (Batek and others 1999, 

Chapman and others 2006, Stambaugh and others 2002). 

Selective cutting with preference for P. echinata arguably 

could produce an opposite effect, where Q. velutina

dominance would then prevail on such sites. 

When the chi-square coeffi cient is used to study species 

associations it is important to be aware of the scale of the 

sample domain from which the sample is drawn because 

sample plots without either species in the test are construed 

as similar (Causton 1988). Therefore, the larger the domain 

that contains plots outside the range of interest, the more 

artifi cially similar the chi-square values will be. While this 

situation will not directly impact the results of studies that 

stand alone, comparing studies from different size sample 

domains and varying degrees of species homogeneity across 

the landscape would result in a less rigorous comparison. 

The sample domains should be as close to the same size 

and homogeneity as possible for direct comparison of chisquare values. Unfortunately, sample homogeneity (or lack 

thereof) is a problem for all aspects of multivariate analyses, 
81

 Chi-sq. Plots both Total plots

Species value Association present present

Juniperus virginiana L. 0.071 – 40 86

Pinus echinata Mill. 211

Pinus taeda L. 11.014 + 12 12

Acer barbatum Michx. 2.081 – 0 3

Acer negundo L. 0.001 – 0 1

Acer rubrum L. 4.413 – 38 98

Acer saccharum L. 12.740 – 5 31

Ailanthus altissima (Mill.) Swingle 0.449 – 0 2

Bumelia sp. 0.449 + 1 2

Carya sp. Nutt. 0.161 + 169 352

Carya illinoensis (Wangenh)K.Koch 0.449 + 1 2

Castanea sp. Mill. 0.001 + 1 1

Celtis laevigata Willd. 0.005 + 4 7

Celtis occidentalis L. 5.856 – 0 8

Cercis canadensis L. 17.228 – 1 23

Cornus fl orida L. 9.162 – 46 125

Diospyros virgininana L. 0.142 + 8 14

Fagus grandifolia Ehrh. 3.474 – 4 17

Fraxinus americana L. 24.175 – 11 60

Fraxinus pennsylvanica Marsh. 0.009 – 6 11

Fraxinus quadrangulata Michx. 0.449 + 0 2

Gleditsia triacanthos L. 0.200 – 1 4

Juglans nigra L. 9.955 – 4 25

Liquidambar styracifl ua L. 10.473 + 59 92

Liriodendron tulipifera L. 0.449 + 1 2

Magnolia acuminata L. 1.359 – 1 6

Morus rubra L. 0.214 – 5 13

Nyssa sylvatica Marsh. 1.263 – 88 194

Platanus occidentalis L. 0.763 – 6 17

Prunus serotina Ehrh. 1.557 + 30 52

Quercus alba L. 0.490 + 165 332

Quercus falcata Michx. 0.795 + 44 82

Quercus falcata var. pagodifolia Ell. 0.118 + 3 6

Quercus macrocarpa Michx. 0.449 – 0 2

Quercus marilandica Muenchh. 0.617 + 33 61

Quercus michauxii Nutt. 0.449 – 0 2

Quercus muehlenbergii Engelm. 12.131 – 7 36

Quercus nigra L. 0.004 + 3 5

Quercus palustris Muenchh. 0.001 – 0 1

Quercus phellos L. 0.312 + 3 4

Quercus rubra L. 23.669 – 90 238

Quercus shumardii Buckl. 0.117 – 2 6

Quercus stellata Wangenh. 5.453 + 122 226

Quercus velutina Lam. 15.571 – 83 214

Robinia pseudoacacia L. 14.189 – 1 20

Sassafras albidum (Nutt.) Nees 0.763 – 6 17

Tilia americana L. 3.028 – 2 11

Ulmus alata Michx. 0.001 + 59 121

Ulmus americana L. 4.716 – 6 24

Ulmus crassifolia Nutt. 0.449 + 1 2

Ulmus rubra Muhl. 5.856 – 0 8

Ulmus serotina Sarg. 0.449 – 0 2

Table 3.—Chi-square values and species association of 52 tree species with P. echinata on the Interior Highland of Arkansas. 

Data are from 1995; n = 434. A + indicates a positive association, a – indicates a negative association. Column labeled ‘Plots 

both present’ indicates the number of plots where the respective species occurred with P. echinata. ‘Total plots present’ indicates 

the total number of plots where each species occurred.
82

especially where endpoint references are essential (Legendre 

and Legendre 1998).

Studies such as this are important in uncovering specifi c 

species associations, especially those species with wide 

ecological amplitude such as P. echinata. Further work is 

needed on species associations of P. echinata across the 

eastern and southern part of its range to compare patterns of 

association with those of the Interior Highlands of Arkansas. 

LITERATURE CITED

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T.L.; Compas, E.; Guyette, R.P. 1999. Reconstruction 

of early nineteenth-century vegetation and fi re regimes 

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397-412.

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America. Philadelphia, PA:The Blakiston Co. 596 p.

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America: Volume 1, conifers. Agric. Hndbk. 654. 

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Forest Service. 675 p.

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principles, practice, and interpretation. London: Unwin 

Hyman. 342 p.

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Long-term changes in forest structure and species 

composition of an upland oak forest in Arkansas. Forest 

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Eyre, F.H., editor. 1980. Forest cover types of the Unites 

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ecology. Cambridge, UK: Cambridge Cambridge 

University Press. 298 p.

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1: 39-63.

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edition. Berkeley and Los Angeles, CA: University of 

California Press. 359 p.

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1996. Textbook of dendrology. 8th edition. New York :

McGraw-Hill. 534 p.

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ecology. Second edition. New York: American Elsevier 

Publishing Co. 308 p.

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Second English edition. Amsterdam: Elsevier, B.V. 

853 p.

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Conifers and important hardwoods. Misc. Publ. 1146. 

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Forest Service.

Little, E.L., Jr. 1979. Checklist of United States trees. 

Agriculture Handbook No. 541. Washington, DC: U.S. 

Department of Agriculture, Forest Service. 375 p.

Ludwig, J.A.; Reynolds, J.F. 1988. Statistical ecology: a 

primer on methods and computing. New York: John 

Wiley and Sons. 337 p.

Pielou, E.C. 1984. The interpretation of ecological data: 

a primer on classifi cation and ordination. New York: 

Wiley and Sons. 255 p.

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of Agriculture, Forest Service, North Central Research 

Station. [Online only.] Available at: www.nrcs2.fs.fed.

us/4801/fi adb/index.html

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of Agriculture, Forest Service, Southern Research 

Station. 82 p.

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Disturbance characteristics and overstory composition 

of an old-growth shortleaf pine (Pinus echinata Mill.) 

forest in the Ozark Highlands, Missouri, USA. Natural 

Areas Journal. 22: 108-119.
83

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America: an introduction. New York: John Wiley and 

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84

GENETIC IMPROVEMENT OF SHORTLEAF PINE ON THE MARK TWAIN, 

OUACHITA, AND OZARK NATIONAL FORESTS

Charly Studyvin and David Gwaze1

ABSTRACT.—A genetic conservation and breeding program for shortleaf pine (Pinus echinata

Mill.) was initiated in the 1960s by the Mark Twain National Forest in Missouri. Superior trees 

were selected from natural stands throughout the Forest. Fifty of the top-ranked superior trees 

were grafted into a fi rst generation seed orchard at the Ouachita National Forest in central 

Arkansas. Major seed collections from the clonal seed orchard were made in 1981, 1983, 1986 

and 2003. Thirteen open pollinated progeny tests were established in the early to mid-1980s to 

evaluate orchard parents and obtain data to rogue the orchard. About half of these tests were 

lost or severely damaged by severe heat and drought in 1980 and 1983. A control pollinated 

progeny test was established in 2002 to further evaluate parents in the seed orchard, and 

to develop a second generation seed orchard. Progeny test results suggested that genetic 

variation exists in shortleaf pine, and genetic gain is predicted to be signifi cant. 

Improvement of shortleaf pine by the Ouachita and Ozark National Forests in Arkansas began 

in the early 1960s with the selection of superior shortleaf pine trees on the Ouachita and Ozark 

National Forests. Fifty superior trees were selected from each of the following geographic 

sources: East Ouachita, West Ouachita, and Ozark. Scions were collected from these superior 

trees and grafted to root stock at the orchard. Once established, these grafts were outplanted 

into their respective blocks of the Ouachita seed orchard. Eighty-four progeny tests were 

established from controlled pollinated crosses in breeding population one of the Region 8 

shortleaf pine breeding program. Several of these progeny tests were lost for a variety of 

reasons, including fi re, animal damage, and unfavorable weather conditions. However, data 

from over 60 valid full-sib progeny tests were used to choose selections to be established 

in the second-generation orchard. Challenges and opportunities of the shortleaf pine tree 

improvement programs on the three National Forests are discussed.

1

Silviculturist (CS), Mark Twain National Forest, 401 Fairgrounds 

Road, Rolla, MO 65401, Resource Scientist (DG), Missouri 

Department of Conservation, 1110 S. College Avenue, Columbia, 

MO 65201. CS is corresponding author: to contact, call (573)364-

4621 ext. 430 or email at cstudyvin@fs.fed.us 

INTRODUCTION

Shortleaf (Pinus echinata Mill.) is one of the four major 

southern pines in the United States. Shortleaf pine has the 

most extensive natural range of any southern pine (Lawson 

1990). The natural range of the species extends from New 

York to Oklahoma and Texas over a very wide range of 

sites. Because of its wide distribution, considerable genetic 

variation exists (Lawson 1990). Shortleaf pine’s genetic 

diversity makes it amenable to genetic improvement.

Shortleaf pine is important for both wildlife habitat and 

timber products. For example, red-cockaded woodpeckers 

(Picoides borealis) prefer mature or over-mature 

shortleaf pine forests and are endangered because of the 

overexploitation of mature shortleaf pine trees (Cunningham 

1940). Shortleaf pine has excellent stem form yielding highvalued posts and poles. It has dense, strong, and easy to 

work wood valued as sawn timber and pulpwood. 

Its ecological and economic importance, coupled with 

its genetic diversity, makes shortleaf pine an excellent 

candidate for genetic improvement. It has been the object 

of genetic breeding since 1959, when the selection and 

grading plans for shortleaf pine for the U.S. Forest Service’s 

southern region (Region 8) were fi nalized (Kitchens 1986). 

Selection of superior shortleaf pine trees by the Mark Twain 

National Forest in southern Missouri, the Ozark National 

Forest in northwestern Arkansas, and the Ouachita National 

Forest in west-central Arkansas and southeastern Oklahoma 

began in the early 1960s. 

The objective of this paper is to give a historical account of 

the shortleaf pine tree improvement activities on the Mark 

Twain, Ouachita, and Ozark National Forests and to discuss 

future options for the genetic improvement of shortleaf pine.
85

FIRST-GENERATION SELECTIONS AND SEED 

ORCHARD ESTABLISHMENT

Region 8 tree improvement work with shortleaf pine 

in Arkansas and Oklahoma began with the selection of 

superior shortleaf pine trees on the Ouachita and Ozark 

National Forests. Selections were made on the following 

criteria: growth and form, insect and disease resistance, 

fl owering and cone production, specifi c gravity, and 

relative location (FSH 2409.26g TREE IMPROVEMENT 

HANDBOOK R8 AMENDMENT 94-1). Fifty superior 

trees were selected from each of the following geographic 

sources: East Ouachita, West Ouachita, and Ozark (the 

dividing line between East and West Ouachita was US 

Highway 71). Region 9 decided to cooperate with Region 8 

and use the facilities in Arkansas, since the Mark Twain was 

the only forest in Region 9 to plant shortleaf pine. A few 

years later superior trees were also selected from the Mark 

Twain National Forest in Missouri. Scions were collected 

from the superior trees and grafted to root stock at the 

orchard. Once established, these grafts were outplanted into 

their respective blocks of the Ouachita Seed Orchard located 

on the Womble District of the Ouachita National Forest. 

The seed orchard for the Mark Twain National Forest was 

located in Arkansas, rather than Missouri, because it was 

thought that establishing the orchard in a more southerly 

location would increase cone production and reduce age 

of fl owering. It was also less expensive to establish a seed 

orchard on the Ouachita National Forest, where an active 

tree improvement program with necessary personnel, 

facilities, and equipment already existed. Grafts were 

planted at a spacing of 15 x 30 feet. When establishment 

was complete, the orchard contained over 35,000 grafted 

trees. 

Acreage of orchard located on the Womble Ranger District, 

Ouachita National Forest, Mount Ida, Arkansas, by species 

and geographic source were:

East Ouachita 138 acres

Ozark 101 acres

West Ouachita 74 acres

Missouri-Mark Twain 85 acres

The total acreage inside the fence, including the buffer 

strips, is approximately 696 acres.

MANAGEMENT AND MAINTENANCE 

OF THE OUACHITA SEED ORCHARDS 

A 400-foot-wide buffer strip surrounds the exterior of the 

orchard and separating the geographic sources. This buffer 

is for pollen exclusion and fi re protection, and it is burned 

each year in the late winter. After the buffer strip was burned 

each year, and the stumps and holes could be clearly seen, 

it was bushhogged to knock down the brush and hardwood 

sprouts. Additional acreage surrounding the exterior of the 

orchard is burned every other year for fuel reduction. 

The interior of the orchard was bushhogged at least once 

and preferably twice during the year. Herbicide was used 

along the rows where the trees were spaced too closely 

to allow bushhogging without damaging the trees. The 

orchard was fertilized once a year with 300 lbs per acre of 

Ammonium Nitrate (34-0-0). This fertilization increased 

cone production, but it also seemed to increase the incidence 

of pitch canker. Fertilizer applications were discontinued 

after 1986, and problems with pitch canker decreased 

noticeably.

Insecticide was used for protection from cone and seed 

insects. The main problems were the Nantucket pine tip 

moth, cone worms of the Dioryctria species, and the 

shieldback and leaffooted pine seed bugs. In the early years 

Furadan® and Guthion® were used. A granular formulation 

of Furadan® was applied with a modifi ed power till seeder, 

and Guthion® was applied with a mist blower sprayer. 

However, due to the uneven terrain and large size of the 

orchard, timing the applications for maximum effectiveness 

with these methods was extremely diffi cult; it took more 

than a month to treat the entire orchard. A cone inventory 

system was implemented to monitor insect damage, 

evaluate treatments, and estimate cone crops. Starting in 

1983, a helicopter was used for aerial application of the 

insecticides Guthion® and Pydrin®. With aerial application 

the orchard could be sprayed in 4 or 5 hours. A degreeday model was used to time the sprays to the life cycle of 

the target insects, and the effectiveness of the treatments 

increased dramatically. We normally sprayed the orchard 

4 to 5 times each year. Pydrin® was originally used for 

the fi rst spray of the season, when the timing was the most 

critical, because of its longer residual effects. However, 

after it was discovered that Pydrin® caused a huge buildup 

of scale insects, its use was discontinued. The ability to 

effectively control the insects increased production of seed 

tremendously.

During large cone harvests, most of the 25 to 30 Womble 

district employees were assigned to the orchard. This 

arrangement helped to get the cones picked and also 

fi nanced the district out of the “Working Capital” fund 

for about a month. Some of the employees worked on 

rental bucket trucks as cone-pickers, some worked to 

clean and measure cones, and some worked to administer 

the cone-picking contract. In the cone harvest of 1986 

approximately 100 people (cone-picking contractors plus 

district employees) worked at the orchard during the conepicking season, which lasted about 30 days. A harvest of 

4,973 bushels of the Ouachita/Ozark and 1,506 bushels of 

Mark Twain shortleaf pine cones was produced. To anyone 

who has ever picked a bushel of shortleaf pine cones, that 

total of 6,479 bushels is an almost unbelievable quantity. It 

amounts to approximately 7 million pine cones, picked off 

the trees one at a time, cleaned, measured, crated, loaded 

on trucks and shipped to the extractory. The seed yield 

was very good at nearly 1.8 pounds per bushel, and more 
86

than 11,000 lbs of pine seed was extracted and placed in 

storage. The Ouachita/Ozark source was stored at the Forest 

Service’s Ashe Nursery in Brooklyn, MS, and the Mark 

Twain source was stored at the Missouri Department of 

Conservation’s George O. White State Forest Nursery in 

Licking, MO. Twenty years later, this seed is still being used 

for reforestation on national forests in Arkansas, Oklahoma, 

and Missouri, on state and private lands in Missouri, and in 

other states with need for shortleaf pine seedlings. After the 

large 1986 crop, no cones were picked at the orchard until 

2003. Shortleaf pine does not regularly produce large cone 

crops, and few cones were available for picking during that 

time, partly due to lack of fertilization and attacks from cone 

and seed insects. 

BREEDING AND PROGENY TESTING 

The Ouachita was the fi rst orchard in Region 8 to complete 

its breeding program (Shortleaf Pine Breeding Population 

1). The breeding program consisted of twenty-fi ve 6 x 6 

disconnected partial diallel crossing groups, each with 15 

crosses, for a total of 375 crosses. Sausage casings were 

used to enclose the fl owers prior to pollen shed. Pollen 

catkins from the desired families were collected and dried, 

and the pollen was extracted. The bagged fl owers were 

then pollinated with the appropriate pollen. The controlled 

pollinated fl owers were tagged and efforts were made to 

protect them until they were mature cones ready to be 

picked approximately 18 months later. At maturity the cones 

were picked and the seed was extracted by hand. The seed 

was shipped to the Ashe Nursery in Mississippi for storage. 

The seed was later planted in separate lots to grow seedlings 

for planting in progeny tests. It was quite a logistical 

effort to maintain the integrity of each cross throughout 

the process. Note that one of the major problems with 

successful breeding in shortleaf pine is timing the controlled 

pollinations to the maximum receptivity of the fl owers. A 

large surplus freeze dryer was acquired from the National 

Tree Seed Lab to store pollen so it would be available when 

needed, and just a few years later the breeding program was 

completed. 

Progeny tests were planted and evaluated on the Ouachita 

and Ozark National Forests. The families evaluated in 

these tests were replicated in space and time. Eighty-four 

progeny tests were established. Several of these progeny 

tests were lost from a variety of reasons, including fi re, 

animal damage, and unfavorable weather conditions. 

However, data from over 60 valid full-sib progeny tests 

were used to choose selections to be established in the 

second-generation orchard. Measurements included FYS 

(fi rst year survival), FIE (fi rst interval evaluation at 5 years 

of age), and SIE (second interval evaluation at 10 years 

of age). Approximately 20 percent of the families were 

selected to be represented in the second-generation orchard. 

These families were selected on the basis of survival, insect 

and disease resistance, straightness and form, and height 

and volume growth. A portion of the original orchard was 

cleared and both a breeding orchard and a production 

orchard were established. Scions were taken from the 

appropriate families in selected progeny tests, grafted to 

root stock, and planted at the orchard. The production 

orchard consists of 16 acres with 65 families represented. 

The breeding orchard consists of 11 acres with 61 families 

represented. 

The Mark Twain breeding program consisted of eight 6 x 6 

disconnected partial diallel Crossing Groups, each with 15 

crosses, plus a single-pair mating design, for a total of 305 

crosses. An additional 200 crosses between Mark Twain and 

Ozark material were planned, but only a few were actually 

accomplished. Of the nine open pollinated progeny tests (of 

Mark Twain parents at the Ouachita Orchard) established by 

the Mark Twain National Forest at 8 ft x 10 ft spacing from 

1980 -1983, only two had good survival (Boiling Springs, 

Houston Ranger District, 1982 and 1983). A third (Enough 

Plantation, Potosi Ranger District, 1982) had moderate 

survival and may help corroborate longer-term growth and 

form data. The original four evaluation plantations on the 

Mark Twain were established in the spring of 1980, and 

subsequently died in that summer’s severe heat and drought. 

Five more plantations were established, two in 1982, and 

three in 1983. Due to unfavorable weather conditions and 

episodic insect damage from pine sawfl ies, only two of 

those tests had acceptable survival. Of four additional close 

spacing progeny tests of both containerized and bareroot 

seedlings established at the George O. White State Forest 

Nursery at Licking, MO, and on the Shawnee National 

Forest in Illinois in 1986, the Licking tests have provided 

some useful information. No full sib progeny test data are 

available for the Mark Twain material. 

In 2002 a full-sib progeny test was planted at the George O. 

White State Forest Nursery at Licking, MO, with controlled 

crosses from the Mark Twain breeding program. Plans are 

to rogue and thin this progeny test to convert it to a seedling 

seed orchard. 

U.S. Forest Service Eastern Region (Region 9) progeny tests 

indicate that all growth traits are strongly inherited, with 

age 17 family heritability estimates for height, diameter, and 

volume being 0.46, 0.31 and 0.46, respectively (Gwaze et 

al. 2005). Genetic correlations between growth traits were 

highly positive, suggesting that one can select and breed for 

one trait without affecting the others. Genetic gain estimates 

for volume are high (Gwaze et al. 2005). If the seed orchard 

is not rogued and all families are allowed to cross pollinate 

genetic gain in volume production is predicted to be 6.7 

percent and 27.2 percent for 10-year and 17-year volume, 

respectively. Roguing the seed orchard by leaving the top 

50 percent of the families results in a 17.8 percent and 37.6 

percent gain in volume at 10 and 17 years, respectively. 

Genetic gains in 5-year volume of 10-15 percent from the 

fi rst generation unrogued shortleaf pine seed orchard have 
87

been predicted in Arkansas (Kitchens 1986). Analyses of 30 

full-sib progeny tests on the National Forests in Arkansas 

revealed that 5-year height and survival among the three 

seed sources—East Ouachita, West Ouachita and Ozark—

were not signifi cantly different (La Farge 1991). It was 

recommended not to keep these sources as separate breeding 

populations.

POLITICS AND ADMINISTRATION

In August 1990, Forest Service Chief Dale Robertson took 

the famous “walk in the woods” with Arkansas Senator 

David Pryor and decided that the major emphasis on 

clearcutting was a thing of the past. Almost overnight, 

the status of tree improvement went from favorite son 

to bastard child. Artifi cial regeneration and genetically 

improved seedlings became politically incorrect. Ecosystem 

management was the new buzzword, along with natural 

regeneration and uneven-aged management. The use of 

artifi cial regeneration was reduced dramatically, along with 

the need for shortleaf pine seed. 

A few years later the Forest Service changed its budget 

process. Previously, funds identifi ed for tree improvement 

were sent to the forests from the Regional Offi ce. Now, each 

year the forests would prioritize funding requests to the 

Regional Offi ce, and projects low on the priority list might 

not be funded. Tree improvement did not compete well in 

an era of shrinking budgets and immediate needs because 

of its lowered status and the long-term nature of the effort. 

In effect, tree improvement has nearly been unfunded out 

of existence. The Region 8 geneticist has stated that the tree 

improvement program’s objective for quality timber became 

obsolete, and as a result some orchard components and all 

progeny testing were terminated (Crane 2005).

THE PENDULUM SWINGS BACK

A major epidemic of southern pine beetle occurred in the 

mid to late 1990s. Damage occurred on forests throughout 

Region 8, including the thousands of acres affected by 

southern pine beetle on the Ouachita National Forest. In 

December of 1999 a severe ice storm damaged or destroyed 

large acreages of timber in Arkansas. Serious problems 

with oak decline developed in both Arkansas and Missouri. 

Thousands of acres of black, red, and scarlet oaks growing 

on dry, rocky sites on the Mark Twain National Forest are 

at severe risk of oak decline. These sites were historically 

populated by shortleaf pine, and the new forest plans on 

the Mark Twain, Ouachita, and Ozark National Forests 

emphasize the restoration of historic vegetation. Once 

again, there was a need for reforestation using shortleaf pine 

seedlings. The value of the shortleaf pine tree improvement 

program became more evident with the realization that 

appreciable quantities of improved shortleaf pine seed of 

suitable geographic origin were not available anywhere—

except at the Ouachita Seed Orchard. 

During the ice storm in 1999, many trees at the orchard 

were damaged or destroyed. A large cleanup was required. 

The Missouri source had been in need of a thinning for 

several years. However, the Mark Twain did not want to 

thin until progeny test data for rouging were available. 

Missouri progeny test data became available about this 

time, and in the Missouri portion of the orchard a major 

rouging operation was accomplished along with the cleanup. 

Seventeen of the original 50 clones were removed. Partly 

as a result of the opening up of the orchard, a good cone 

crop was available for picking in 2003. The Ouachita and 

the Mark Twain National Forests were able to successfully 

collect a large number of these cones and now have a large 

supply of fresh shortleaf pine seed. The Ouachita picked a 

total of 1000 bushels from the Ozark, West Ouachita, and 

East Ouachita sources, with a seed yield of 1.34 lbs per 

bushel, for a total of 1343 lbs of seed. The Mark Twain 

picked 1100 bushels with a seed yield of 1.385 pounds/

bushel for a total of 1523 lbs of seed. Soon after the Mark 

Twain seed was safely stored at the nursery in Watersmeet, 

MI, an agreement was initiated to transfer the remaining 

inventory of 1986 seed in storage at the Licking Nursery 

to the Missouri Department of Conservation. In return the 

Missouri Department of Conservation agreed to produce 

shortleaf pine seedlings for the Mark Twain National Forest. 

What’s Next for Shortleaf Pine Tree 

Improvement in Arkansas?

• Continue to maintain the Ouachita Seed Orchard for 

future seed collections.

• Use the wealth of data available from the Ouachita 

and Ozark progeny tests to study the genetics of 

shortleaf pine. 

• Manage selected progeny tests for future seed 

collection areas.

• Use genetic resource management to focus on genetic 

diversity and to meet the seed needs for restoration of 

endangered ecosystems.

• Manage the Second Generation production and 

breeding orchards for future seed collections and 

breeding work.

• DNA testing? New selections?

What’s Next for Shortleaf Pine Tree 

Improvement in Missouri?

• Convert the full-sib progeny test established in 2002 

at Licking Nursery to a seedling seed orchard.

• Establish another progeny test/seedling seed orchard 

on the Mark Twain with some of the remaining seed 

from controlled crosses.

• Develop a strategy to obtain shortleaf pine seed for 

direct seeding, either from surplus seed orchard seed, 

or perhaps from seed production areas established 

in 1967 or subsequent progeny tests, if they can be 

managed effectively for seed production.
88

• Evaluate the genetic variation and population 

structure in shortleaf pine using micro-satellite 

genetic markers to help manage and maintain genetic 

diversity.

LITERATURE CITED

Crane, B.S. 2005. From tree improvement to species 

improvement: restoration and conservation efforts on 

the Forest Service’s Southern National Forests. Proc. 

Southern Forest Tree Improvement Conference: 168.

Cunningham, J.W. 1940. Birds of the southeast. Bluebird. 

7: 67.

Gwaze, D.P.; Melick, R.; Studyvin, C.; Coggeshall, M. 

2005. Genetic control of growth traits in shortleaf pine 

in Missouri. Southern Journal of Applied Forestry. 

29(4): 2000-2004.

Kitchens, R.N. 1986. Trends in shortleaf pine tree 

improvement. In: Murphy, P., ed. Proc. Symp. on the 

shortleaf pine ecosystem. Little Rock, AR: Cooperative 

Extension Service, University of Arkansas: 89-100.

La Farge, T. 1991. Are there signifi cant differences among 

the three shortleaf pine seed sources on the National 

Forests in Arkansas? In: Proceedings of the fi rst 

northern forest genetics association conference: 40-47.

Lawson, E.R. 1990. Shortleaf pine. In: Silvics of North 

America, Volume 1. Conifers. Agric. Hndbk. 654. 

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

Forest Service: 316-326.
89

PERFORMANCE OF SHORTLEAF PINE PROVENANCES

IN MISSOURI

David Gwaze, Jennifer Myszewski, and John Kabrick1

ABSTRACT.—Two shortleaf pine (Pinus echinata Mill.) provenance tests established by the 

USDA Forest Service North Central Research Station as part of the South-wide Southern 

Pine Seed Source Study were examined to determine the most suitable seed sources for 

planting in Missouri. Each test comprised seven different provenances from six to seven 

states in the natural shortleaf pine distribution. Signifi cant provenance differences in survival 

and height growth were found in both tests and a strong north-south trend was observed. 

More northernly sources (New Jersey and Tennessee provenances) had the best survival 

and greatest height growth while southern sources (Georgia and Louisiana) had the poorest 

survival and lowest height growth. Regression estimates of slope indicate that New Jersey 

and Tennessee provenances have the highest relative growth rates. Both survival and height 

were highly correlated with latitude at the seed source. Results from this study suggest that 

the best seed sources for planting in central Missouri are not those from Arkansas, as current 

practice suggests, but instead are in states in the northern portion of the natural shortleaf pine 

distribution.

1

Resource Scientist (DG), Missouri Department of Conservation, 

1110 S. College Avenue, Columbia, MO 65201; Geneticist (JM), 

Southern Institute of Forest Genetics, 23332 Hwy. 67, Saucier, 

MS 39574-9344; Research Forester (JK), U.S. Forest Service, 

North Central Research Station, 202 Natural Resources Building, 

Columbia, MO 65211. DG is corresponding author: to contact call 

(573)882-9909 ext. 3320 or email at David.Gwaze@mdc.mo.gov

INTRODUCTION

Shortleaf pine (Pinus echinata Mill.), whose natural range 

extends from New York and New Jersey south to Florida 

and west to Oklahoma and Texas, is the most widely 

distributed of the southern pines (Fig. 1, Lawson 1990). It is 

the only pine species native to Missouri and its restoration 

there is important for mitigating chronic oak decline (Law et 

al. 2004). Shortleaf pine is also an important source of food 

and habitat for many birds and mammals, and it produces 

high quality sawtimber on dry, nutrient-poor sites.

Efforts to restore shortleaf pine in Missouri are ongoing, but 

seed supply is sometimes limited. When seedling shortages 

occur, Arkansas seed sources are often used in place of 

locally-adapted stock. It is not known whether Arkansas 

sources are the most appropriate non-local seed sources for 

planting in Missouri. However, region-wide seed transfer 

guidelines for shortleaf pine suggest that Arkansas sources 

could suffer from cold injury when planted in central 

Missouri. 

Studies such as the South-wide Southern Seed Source Study 

have shown that local sources are not always the best source 

of planting stock for afforestation (Wells and Wakeley 1966, 

Wells 1983). For example, loblolly pine seed originating in 

Livingston Parish, LA, tends to be fast growing and more 

resistant to fusiform rust than other sources (Wells 1985). 

As a result, Livingston Parish stock has been widely planted 

in Georgia, north Florida, and Alabama in lieu of stock from 

local sources. Likewise, seeds originating on the coastal 

plain of North Carolina and South Carolina are frequently 

planted in Arkansas, where they outgrow local sources 

(Lambert et al. 1984). 

Figure 1.—Natural distribution of shortleaf pine (Pinus 

echinata Mill.) (Lawson 1990).
90

In this study, the performance of seed sources from 

across the natural range of shortleaf pine are compared 

to determine which sources are best adapted to the 

environmental conditions in Missouri. The stability of 

provenance performance across ages is also examined.

MATERIALS AND METHODS

Materials

Two Dent County, Missouri provenance tests (441 and 

444) were included in this study. Both were originally 

established by the USDA Forest Service’s North Central 

Research Station in collaboration with the Committee on 

Southern Forest Tree Improvement as part of the Southwide Southern Pine Seed Source Study. In 1951 and 1955, 

seed was collected from multiple sources within the eastern 

part of the natural range of shortleaf pine (table 1). Source 

locations from as far north as New Jersey, south to Georgia 

and west to Louisiana were selected based primarily on 

their average annual temperatures (which ranged from 11.7 

to 19.4 °C). At each source, seed were collected from 20 or 

more average-appearing trees to produce a representative 

sample of genotypes from each location. Each source 

collection was then mixed together and assigned a 

provenance number.

Table 1.—Description of the shortleaf pine provenances planted in two tests in Dent County, Missouri.

*Average annual minimum temperature

 Year of Provenance Lat. Temp.*

Test collection Number State County/Parish (North) (°C)

441 1951 429 Arkansas Ashley 33° 02’ -11.6

 427 Arkansas Clark 34° -11.8

 421 Louisiana St. Helena 31° -8.1

 419 Mississippi Lafayette 34° 18’ -13.8

 433 Missouri Dent 37° 31’ -20.2

 403 New Jersey Burlington 39° 41’ -18.9

 435 Tennessee Morgan 36° -16.2

 

444 1955 465 Georgia Webster 32° -9.3

 473 Louisiana St. Helena 31° -8.1

 485 Missouri Dent 37° 31’ -20.2

 453 New Jersey Burlington 39° 41’ -18.9

 457 South Carolina Union 35° -12.0

 487 Tennessee Anderson 36° -16.2

 455 Virginia Southampton 36° -14.1

Seed for the two tests were sown and bedded at the George 

O. White Forest State Nursery near Licking, MO. After 

1 year in the nursery, bare-root seedlings were lifted 

and graded. Then, seedlings were root pruned to about 

20 cm and the best trees were outplanted on the Sinkin 

Experimental Forest located 5 miles northwest of Bunker 

in Dent County, Missouri (Lat. 91° 15’; Long. 37° 30’, 

Alt. 380 m above sea level). In Spring 1953, Test 441 was 

planted using the seed collected in 1951 and in Spring 1957, 

Test 444 was planted using seed collected in 1955.

Test Design and Measurement

Test 441 and Test 444 were both established using a 

randomized complete block design (Snedecor and Cochran 

1980). For each test, there were four blocks comprising 

seven provenances. Each provenance was planted in square 

plots of 11 x 11 tree planted at 1.8 x 1.8 m spacing. To 

minimize edge effects, only the center 49 trees in each 

square plot were measured. Tests 441 and 444 were assessed 

at ages 1, 3, 5, 10, 15, 20, 25, and 30. Because of large 

differences in survival and the sensitivity of diameter to 

competition, only survival and height were analyzed in this 

study.
91

Statistical Analyses

Using the SAS PROC GLM procedure (SAS Institute 

1985), analyses of variance (ANOVAs) were used to test 

for signifi cant differences in height among provenances and 

blocks. To increase statistical power, we used P = 0.10 for 

all tests. Because the two provenance tests were established 

in different years, the data were analyzed separately by 

provenance test. Where signifi cant differences were detected 

among provenances, Duncan’s Multiple Range Test was 

used to compare means.

The stability of provenance growth rates was determined by 

regressing the provenance mean height against the overall 

test mean height at each age. The slope of the regression 

evaluates the provenance height growth trend in relation 

to the average trend and can be considered as a temporal 

stability parameter for the given provenance (Finlay and 

Wilkinson 1963). A value close to 1 indicates an average 

trend, values over 1 indicate a higher growth rate, and 

values below 1 indicate a lower growth trend.

Survival was analyzed using a chi-squared test. Only 

survival data for ages 1 through 15 were analyzed because 

the tests were thinned after collection of the 15-year data. 

We used the Kaplan-Meier method (Kaplan and Meier 

1958) to compare the survival functions of the different 

provenances.

To determine the importance of climatic variables, simple 

linear regression analyses were performed with survival 

and height as dependent variables and latitude as the 

independent variable.

RESULTS AND DISCUSSION

Provenances had signifi cantly different mean heights at age 

30 (P < 0.1, Tables 2 and 3). Height ranged from 14.4 m 

for the Louisiana provenance to 16.2 m for the New Jersey 

provenance in Test 441 and from 13.0 m for the Louisiana 

provenance to 15.6 m for the New Jersey provenance in 

Test 444. In both tests, the New Jersey provenance was 

signifi cantly taller than the local Missouri provenance and 

the Missouri provenance was signifi cantly taller than the 

Arkansas provenances.

The north-south trend is supported by a high positive 

correlation between height and latitude in both tests 

(Table 4). The superior performance of northern sources 

observed in this study is not consistent with the results of 

provenance studies in other states. In Oklahoma, Tauer 

(1980) found that southern sources of shortleaf pine 

were more productive at age 20 than northern sources of 

shortleaf pine. Similarly, Schmidtling (1995) and Wells 

and Wakeley (1966) found that seeds moved a modest 

distance northward out-performed seeds from local sources. 

According to Schimdtling (2001) seedlings will survive and 

grow well if they come from any area having a minimum 

Table 2.—Summary of the analyses of variance for age 30 

height in two shortleaf pine provenance tests in Missouri+.

+Signifi cance level: *P < 0.1; ns = not signifi cant

Test Source DF Mean Square

441 Block 3 2.5*

 Provenance 6 1.9*

 Residual 18 0.7

444 Block 3 2.4ns

 Provenance 6 3.3*

 Residual 18 1.2

Table 3.—Provenance means for age 30 height growth in 

two shortleaf pine provenance tests in Missouri+.

+Means with the same letter are not signifi cantly different at the 10% 

level on a Duncan’s Multiple Range Test.

 Provenance Provenance 

Test Number (Country/Parish) HT (m)

441 429 Ashley, AR 14.9cd

 427 Clark, AR 14.9abc

 421 St. Helena, LA 14.4d

 419 Lafayette, MS 15.9abc

 433 Dent, MO 15.2abc

 403 Burlington, NJ 16.2a

 435 Morgan, TN 16.1ab

 

444 465 Webster, GA 13.6b

 473 St. Helena, LA 12.2c

 485 Dent, MO 13.5bc

 453 Burlington, NJ 15.2a

 457 Union, SC 13.7ab

 487 Anderson, TN 14.3ab

 455 Southampton, VA 14.8b

temperature within 2.8 °C of the planting site’s minimum 

temperature. Seedlings from an area with cooler winters 

will grow slower than seedlings from local sources. In our 

study, the provenance from New Jersey was collected on 

sites with annual minimum temperatures within 2.8 °C of 

those in Dent County, Missouri. Provenances collected in 

Mississippi, Tennessee, South Carolina, and Virginia came 

from sites within 2.8 to 8.4 °C higher than those of Dent 

County in Missouri. However, provenances collected in 

Arkansas, Georgia, and Louisiana came from sites with 

annual minimum temperatures 8.4 to 14 °F higher than those 

of Dent County, Missouri. It appears that the north-south 
92

Table 4.—Estimated regression coeffi cients based on linear models for survival and latitude, and height and latitude of shortleaf 

pine in two provenance tests in Missouri.

 Dependent Independent Regression Residual 

Test variable variable coeffi cient (slope) mean square DF R2

441 Height Latitude 0.18 0.10 5 0.62

 Survival Latitude 4.19 63.88 5 0.76

444 Height Latitude 0.26 0.44 5 0.56

 Survival Latitude 3.63 47.40 5 0.77

trend observed in this study is the result of moving seed to a 

site with much colder annual minimum temperatures. 

A similar north-south trend was found in percent survival 

(Figs. 2 and 3). The survival functions were signifi cantly 

different in Test 441 (χ2

 = 388.3, P = <0.001) and in Test 

444 (χ2 = 297.9, P = <0.001). Similarly, the chi-square test 

at age 15 showed signifi cant survival differences among 

provenances in Test 441 (χ2 = 27.8, P = <0.001) and in Test 

444 (χ2 = 13.9, P = 0.031). In Test 441, survival at age 15 

ranged from 23.5 percent for the Louisiana provenance to 

62.2 percent for the New Jersey provenance and in Test 

444, from 31.1 percent for the Georgia provenance to 

69.4 percent for the Missouri provenance. Survival was 

positively correlated with latitude (r = 0.76 and 0.77 for 

Tests 441 and 444, respectively) (Table 4). In the past, 

Missouri has obtained seed from Arkansas for its restoration 

programs. Results from this study suggest that while 

northern Arkansas sources may survive well, the more 

southern sources break the seed transfer guidelines and 

could have poor survival.

Stability of Provenances Across Ages

When the mean heights of each provenance were regressed 

on the overall test means, the linear equations were highly 

signifi cant (R2

 = 1.00). Differences in the relative growth 

rate of the provenances were evidenced by differences in 

the slopes of the regression lines for each provenance (Table 

5). Growth rate is important as it can be a more effi cient 

selection parameter than early total height because some 

provenances can be slow starters and outperform the early 

starters with time. In this study, provenances with high early 

height growth also had the highest relative growth rates.

Correlations

Correlations between height at the oldest assessed age 

in each test and height at earlier measurement ages are 

presented in Table 6. As expected, the correlations increased 

as the time between ages decreased. Correlations involving 

heights at a young age were very low, with a negative 

correlation between heights at age 1 and 30 in Test 444. 

In general, heights assessed prior to age 10 years were not 

reliable predictors of height at the oldest assessed age. These 

fi ndings are in close agreement with those of Lambeth 

(1980), who reported poor age-age correlations in several 

Pinaceae species when heights at ages less than 4 years 

were used. Possible explanations for the low correlations in 

this study include post-planting stress and browsing.

0

10

20

30

40

50

60

70

80

90

100

1 3 5 10 15

Years after field establishment

Survival (%)

Figure 3.—Survival of shortleaf pine provenances 

established in Missouri in Test 444.

LA

MO

NJ

TN

VA

SC

GA

0

10

20

30

40

50

60

70

80

1 3 5 10 15

Years after field establishment

Survival (%)

Figure 2.—Survival of shortleaf pine provenances 

established in Missouri in Test 441.

NJ

TN

MO

Clark, AR

MS

LA

Ashley, AR

←
93

 Provenance Provenance Regression Residual 

Test number coeffi cient (slope) mean square DF R2

441 429 Ashley, AR 0.972 0.0045 6 1.00

 427 Clark, AR 0.968 0.0286 6 1.00

 421 St. Helena, LA 0.958 0.0003 6 1.00

 419 Lafayette, MS 1.019 0.0149 6 1.00

 433 Dent, MO 0.998 0.0088 6 1.00

 403 Burlington, NJ 1.050 0.0106 6 1.00

 435 Morgan, TN 1.037 0.0026 6 1.00

 

444 465 Webster, GA 0.929 0.0706 6 1.00

 473 St. Helena, LA 0.909 0.0201 6 1.00

 485 Dent, MO 0.985 0.0019 6 1.00

 453 Burlington, NJ 1.102 0.0045 6 1.00

 457 Union, SC 0.998 0.0381 6 1.00

 487 Anderson, TN 1.035 0.0136 6 1.00

 455 Southampton, VA 1.039 0.0076 6 1.00

Table 5.—Estimated regression coeffi cients based on linear models for mean height of each provenance and test mean height 

for two shortleaf pine provenance tests in Missouri.

*Signifi cant at 0.05 or lower

Table 6.—Pearson product-moment correlation coeffi cients 

between heights at age 30 and heights at earlier measurement ages in two provenance tests in Missouri.

 Test 441 Test 444 

 Age Correlation Age Correlation

 1 0.16* 1 -0.13*

 3 0.40* 3 0.10

 5 0.54* 5 0.23*

 10 0.69* 10 0.57*

 15 0.83* 15 0.70*

 20 0.88* 20 0.83*

 25 0.94* 25 0.90*

CONCLUSION

Signifi cant differences in the survival and height growth 

of trees with different seed origins were identifi ed in two 

shortleaf pine provenance tests established in Dent County, 

Missouri. There was a north-south trend in survival and 

height growth with the northern sources tending to have 

better survival and height growth than the southern sources. 

In both tests, trees from New Jersey and Tennessee had the 

highest rate of survival and the greatest height growth while 

trees from Louisiana and Georgia performed the poorest. 

Results from this study suggest northern seed sources 

should be favored for planting in Missouri.

ACKNOWLEDGMENTS

The study was supported by the USDA Forest Service 

North Central Research Station and the Southern Forest 

Tree Improvement Committee. We thank Ken Davidson 

for providing information on the study and Jillian Lane for 

assistance with statistical analyses.

LITERATURE CITED

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

pines. Agric. Handbook 471. Washington, DC: U.S. 

Department of Agriculture, Forest Service. 407 p.

Finlay, K.W.; Wilkinson, G.N. 1963. The analysis of 

adaptation in a plant breeding programme. Aust. Journal 

of Agricultural Science. 14: 742-745.

Kaplan, E. L.; Meier, P. (1958). Nonparametric estimation 

from incomplete observations. Journal of American 

Statistical Association. 53: 457-481.

Lambert, C.C.; Dougherty, P.M.; Gladstone, W.T.; 

McCullough, R.B.; Wells, O.O. 1984. Large-scale 

planting of North Carolina loblolly pine in Arkansas 

and Oklahoma: a case of gain versus risk. Journal of 

Forestry. 82: 736-741.

Lambeth, C.C. 1980. Juvenile-mature correlations in 

Pinaceae and implications for early selection. Forest 

Science. 26: 571-580.
94

Law, J.R.; Melick, R.; Studyvin, C.; Steinman, J.R. 2004. 

Oak decline in Missouri: History revisited. In Spetich, 

M.A., ed. Upland oak ecology symposium: history, 

current conditions, and sustainability. Gen. Tech. 

Rep. SRS-73. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research Station: 

257-258.

Lawson, E.R. 1990. Pinus echinata Mill. shortleaf pine. In: 

Burns, R. M.; Honkala, B.H., tech. cords. 1990. Silvics 

of North America. Volume 1, Conifers. Agric. Hndbk. 

654. Washington, DC: U.S. Department of Agriculture, 

Forest Service: 316-326.

SAS Institute Inc. 1985. SAS Language Guide for Personal 

Computers, Release 6.03 Edition. Cary, NC: SAS 

Institute. 558 p.

Schmidtling, R.C. 1995. Seed transfer and genecology in 

shortleaf pine. In: Boyd, E.M., comp. Proceedings 

of the eighth biennial southern silvicultural research 

conference; 1994 November 1-3; Auburn, AL. Gen. 

Tech. Rep. SRS-1. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research Station: 

373-378.

Schmidtling, R.C. 2001. Southern pine sources. Gen. Tech. 

Rep. SRS-44. Asheville, NC: U.S. Department of 

Agriculutre, Forest Service, Southern Research Station. 

27 p.

Rink, G.; Wells, O.O. 1988. Productivity comparison of 

37-year-old loblolly-shortleaf pine seed sources in 

southern Illinois. Northern Journal of Applied Forestry. 

5(2): 155-158.

Tauer, C.G. 1980. Twenty-year results of a shortleaf pine 

seed source study in Oklahoma. Oklahoma State Univ. 

Agric. Exp. Sta. Bull. B-752. Stillwater, OK: Oklahoma 

State University. 12 p.

Wells, O.O. 1983. Southwide pine seed source study 

loblolly pine at 25 years. Southern Journal of Applied 

Forestry. 7: 63-71.

Wells, O.O. 1985. Use of Livingston Parish, Louisiana 

loblolly pine by forest products industries in the South 

east. Southern Journal of Applied Forestry. 9: 180-185.

Wells, O.O.; Wakeley, P.C. 1966. Geographic variation 

in survival, growth and fusiform infection of planted 

loblolly pine. Forest Science Monographs. 11. 40 p.

Wells, O.O.; Wakeley, P.C. 1970. Variation in shortleaf pine 

from several geographic sources. Forest Science. 16: 

415-423.
95

LOBLOLLY PINE SSR MARKERS FOR SHORTLEAF PINE GENETICS

C. Dana Nelson, Sedley Josserand, Craig S. Echt, and Jeff Koppelman1

ABSTRACT.—Simple sequence repeats (SSR) are highly informative DNA-based markers 

widely used in population genetic and linkage mapping studies. We have been developing 

PCR primer pairs for amplifying SSR markers for loblolly pine (Pinus taeda L.) using loblolly 

pine DNA and EST sequence data as starting materials. Fifty primer pairs known to reliably 

amplify polymorphic markers in loblolly pine were screened for their use in shortleaf pine 

(P. echinata Mill.), longleaf pine (P. palustris Mill.), and slash pine (P. elliottii var. elliottii

Engelm.). Thirty-four of these generated “high-quality” marker data for a small range-wide 

sample of shortleaf pines and 32 were polymorphic. Expected heterozygosities for the 

polymorphic markers averaged 0.71 and ranged from 0.40 to 0.88. A subset of the polymorphic 

markers should be very useful for determining identity or parentage of unknown trees while the 

whole set should provide excellent information on genetic diversity, gene fl ow, and population 

structure in shortleaf pine.

1

Research Geneticist and Project Leader (CDN), Biological Science 

Technician (SJ), and Research Geneticist (CSE), Southern Institute 

of Forest Genetics, USDA Forest Service, 23332 Mississippi 67, 

Saucier, MS 39574; Resource Scientist (JK), Missouri Department of 

Conservation, Columbia, MO 65201. CDN is corresponding author: 

to contact call (228) 832-2747 or email at dananelson@fs.fed.us

INTRODUCTION

Microsatellite, or simple sequence repeat (SSR), markers 

have been used to characterize factors affecting pollen fl ow 

in shortleaf pine stands in southern Missouri (Dyer and 

Sork 2001), and to study local and range-wide population 

histories in loblolly pine (Al-Rabab’ah and Williams 2002, 

2004). Although isozyme markers have proven useful in 

studying shortleaf pine populations (Edwards and Hamrick 

1995, Huneycutt and Askew 1989, Raja and others 1997), 

it is desirable to develop DNA-based markers for use in 

detailed studies of local and/or range-wide population 

dynamics. Most SSR marker development work in pines to 

date has centered on loblolly pine (Pinus taeda L.), a close 

relative of shortleaf pine (P. echinata Mill.). Given these 

facts, we have begun developing SSR markers for use in 

various other southern pine species. In the current study 

we tested a selected set of 50 loblolly pine SSR markers 

on a sample of 6 shortleaf pine trees. In addition, our test 

included a loblolly pine control sample and two samples 

each of longleaf pine (P. palustris Mill.) and slash pine 

(P. elliottii var. elliottii Engelm.). 

MATERIALS AND METHODS

Fifty SSR primer pairs that were developed from loblolly 

pine DNA and characterized as high-quality genetic markers 

based on their reliable and repeatable amplifi cation and 

detection in loblolly pine were tested in this study (Tables 

1 and 2). Six shortleaf pine, two longleaf pine, two slash 

pine and two loblolly pine trees were used in testing the 

50 primer pairs. The six shortleaf pine trees were all 

growing on the Harrison Experimental Forest in southeast 

Mississippi. Four trees were selected from four different 

provenances that were growing in a range-wide provenance 

test (Wells and Wakeley 1970). The sources included 

Southampton County, VA (source 455), Putnam County, 

GA (463), St. Helena Parish, LA (473), and Dent County, 

MO (485). The remaining two shortleaf pine trees were 

fi rst-generation parent trees growing in a clone bank. Both 

of these trees originated in the Ozark National Forest in 

Arkansas. 

Genomic DNA was isolated from fresh leaf samples from 

each tree using a DNeasytm 96 Plant Kit (Qiagen cat. no. 

69181). The 50 primer pairs were screened with genomic 

DNA using the following PCR protocol for each 12 μl total 

volume reaction: 20 ng genomic DNA, 200 μM of each 

primer, 200 μM dNTPs, 1x Taq buffer (2.0 mM MgCl2

, 

10 Mm Tris-HCl, 50 mM KCl), and 0.5 U Taq DNA 

polymerase (Promega). The PCRs were completed using the 

following touchdown protocol on PTC-200 thermal cyclers 

(MJ Research): 2 min at 94 °C; followed by 20 cycles of 30 

s at 94 °C, 30 s at X, and 30 s at 72 °C, where X = 65 °C in 

the fi rst cycle, decreasing by 0.5 °C every cycle thereafter; 

followed by 15 cycles of 30 s at 92 °C, 30 s at 55 °C, and 

1 min at 72 °C; followed by a 15-min extension at 72 °C 

and an indefi nite hold at 4 °C. The resulting PCR products 

were separated on an ABI PRISM 3100 Genetic Analyser 

(Applied Biosystems) as recommended by the manufacturer. 

ABI PRISM LIZ500 was used as an internal size standard. 

Allele sizes (in base pairs [bp]) were determined using 

the local southern algorithm implemented by ABI Prism 
96

Table 1.—Allelic summary for 34 loblolly pine SSR markers screened for variability in shortleaf pine (n=6 trees), longleaf pine

(n=2), and slash pine (n=2). Loci prefi xes PtTX (Auckland and others 2002), ript (Echt and Nelson unpublished), and RPtest 

(Echt and Burns 1999). Min and max are range of allele sizes (base pairs), He

 is Nei’s (1978) genetic diversity, and An is total 

number of alleles observed.

Note: SSR markers tested and not recommended for use in shortleaf pine: PtTX3047, PtTX3063, PtTX3087, PtTX3110, ript0032, ript0106, 

ript0123, ript0158, ript0255, ript0263, ript0287, ript0647, ript0649, ript0814, ript0990, and ript1077.

1

poly = polymorphic score: 1 = more than 1 allele observed, 0 = 1 allele, . = 0 alleles.

2

32 of these 34 markers are polymorphic in shortleaf pine.

 Shortleaf Longleaf Slash

Marker min max He An min max poly1

 min max poly1

PtTX2123 188 197 0.40 3 197 197 0 194 197 0

PtTX3011 160 212 0.70 5 160 185 1 160 . 0

PtTX3013 121 137 0.63 4 131 140 1 137 141 1

PtTX3029 258 261 0.49 2 267 271 1 262 . 0

PtTX3034 188 208 0.81 7 217 225 1 200 208 1

PtTX3052 239 259 0.70 4 239 259 1 240 259 1

PtTX4058 125 156 0.83 7 146 148 1 146 . 0

PtTX4093 170 323 0.84 8 474 . 0 319 . 0

PtTX4181 368 415 0.83 9 387 411 1 375 . 0

PtTX4205 134 153 0.78 5 134 146 1 . . .

PtTX4221 177 193 0.47 2 195 . 0 195 199 1

PtTX4228 141 166 0.76 5 156 160 1 158 162 1

ript0031 243 282 0.82 7 228 228 0 234 . 0

ript0065 130 145 0.51 4 142 142 0 142 144 1

ript0066 117 117 0 1 110 . 0 106 . 0

ript0079 136 171 0.74 4 142 159 1 146 152 1

ript0126 162 214 0.76 6 184 186 1 180 200 1

ript0165 196 209 0.61 3 192 200 1 194 198 1

ript0171 203 213 0.66 4 201 218 1 193 207 1

ript0211 144 160 0.74 5 148 157 1 138 154 1

ript0293 178 189 0.42 2 . . . 183 . 0

ript0367 191 213 0.74 4 189 209 1 191 . 0

ript0369 165 178 0.72 4 159 171 1 182 . 0

ript0376 185 200 0.81 7 196 200 1 181 196 1

ript0388 192 212 0.82 7 200 204 1 . . .

ript0467 158 185 0.88 9 153 169 1 186 . 0

ript0567 150 180 0.61 5 . . . . . .

ript0619 184 206 0.80 6 200 208 1 208 212 1

ript0629 153 167 0.78 6 147 165 1 157 175 1

ript0852 199 205 0.74 5 191 . 0 203 209 1

ript0968 177 222 0.78 6 206 210 1 198 214 1

ript0984 212 237 0.75 6 217 . 0 217 . 0

RPtest9 273 295 0.79 5 278 . 0 257 . 0

RPtest11 218 218 0 1 218 . 0 218 . 0

Mean 0.67 4.9 

Total2

 22 16
97

GeneMapper® software version 3.7. Due to mobility shift 

problems associated with the 250 bp and 340 bp bands, 

these sizes were excluded from all sizing calls. Allelic data 

were analyzed by standard genetic methods using SAS 

(SAS Institute). 

RESULTS AND DISCUSSION

Of the 50 SSR primer pairs tested, 34 were characterized 

as “high quality” for use in population genetic analyses 

of shortleaf pine (Table 1; GenBank and dbSTS accession 

numbers for previously unreported loci are given in 

Table 2). These markers met criteria based on clean PCR 

amplifi cation with low failure rates. Of the 32 markers 

that were polymorphic in shortleaf pine (Table 1), 30 and 

29 cleanly amplifi ed longleaf pine and slash pine DNA, 

respectively. Within this select group, 22 markers for 

longleaf pine and 16 markers for slash pine appeared to be 

polymorphic within these two species (Table 1). Although 

our diversity measure (i.e., expected heterozygosity, He) 

is based on only six shortleaf pine trees, it does suggest 

that these markers are at least as heterozygous as they are 

for loblolly pine. In fact, the average diversity of the 32 

polymorphic markers is 0.71 for this sample of shortleaf 

Table 2.—GenBank accession and dbSTS numbers for 

markers not previously described.

Marker Acc# dbSTS#

ript0031 BV683043 814084

ript0065 BV683047 814088

ript0066 BV683048 814089

ript0079 BV683053 814094

ript0126 BV683062 814103

ript0165 BV683070 814111

ript0171 BV683072 814113

ript0211 BV683076 814117

ript0293 BV683078 814119

ript0367 BV683081 814122

ript0369 BV683082 814123

ript0376 BV683083 814124

ript0388 BV683084 814125

ript0467 BV683150 814191

ript0567 BV683089 814130

ript0619 BV683091 814132

ript0629 BV683094 814135

ript0852 BV683115 814156

ript0968 BV683124 814165

ript0984 BV683125 814166

pine compared to 0.68 for a similar range-wide sample 

of loblolly pine (Nelson unpublished). The correlation 

between shortleaf pine and loblolly pine diversity values is 

0.42, suggesting that one cannot predict with any certainty 

diversity rates for individual SSR markers between these 

two species. Genetic drift since divergence from a common 

ancestor is a likely explanation for these results. 

The transferability of loblolly pine SSR markers to 

shortleaf pine, longleaf pine, and slash pine was evaluated 

by comparing amplifi cation and polymorphism results 

for two samples from each species. Four shortleaf pine 

trees were evaluated—two from Arkansas and one each 

from Louisiana and Georgia. As described in the Materials 

and Methods, two each of longleaf pine and slash pine 

trees of Mississippi origin were evaluated. Results of 

this comparison are provided in Table 3. Transfer rate of 

polymorphic markers was higher for shortleaf pine (70 

percent and 72 percent) than for longleaf pine (54 percent) 

or slash pine (44 percent). The rate for longleaf pine is 

comparable to that reported by Shepherd and others (2002), 

who found 53 percent (19 of 36) of loblolly pine SSR 

markers polymorphic in slash pine and Caribbean pine 

(P. caribea Morelet). In contrast, Liewlaksaneeyanawin 

and others (2004) reported only 22 percemt (23 of 107) 

to be polymorphic in lodgepole pine (P. contorta Dougl. 

ex Loud.). The close phylogenetic relationship of loblolly 

pine to the other southern U.S. pines, particularly shortleaf 

pine, and the more distant relationship of loblolly pine 

to lodgepole pine (Little and Critchfi eld 1969) is a likely 

explanation for these results.

Polymorphism (i.e., two or more alleles detected) rates 

based on pairs of trees from the same area are also higher 

for shortleaf pine from the two sample areas (78 and 81 

percent, calculated from Table 3) than for longleaf pine 

and slash pine (68 and 54 percemt, respectively). These 

rates are consistent with previous isozyme data that show 

longleaf pine to be less genetically diverse than shortleaf 

pine (Schmidtling and Hipkins 1998). The degree to which 

polymorphism can be predicted based on only two samples 

(four chromosomes in a diploid species) was evaluated by 

Table 3.—Transfer of 50 loblolly pine SSR markers to 

shortleaf pine, longleaf pine, and slash pine.

 Origin of Number (%) Number (%)

Species Sample Pair Amplifi ed Polymorphic

Shortleaf Arkansas 46 (92) 36 (72)

Shortleaf Louisiana 

 and Georgia 43 (86) 35 (70)

Longleaf Mississippi 40 (80) 27 (54)

Slash Mississippi 41 (82) 22 (44)
98

comparing the two-sample estimates from shortleaf pine 

with the six-sample (12 chromosomes) estimate. Based on 

six samples, 46 of the 50 markers were cleanly amplifi ed 

and 41 were polymorphic (data not shown), indicating that 

the two-sample data underestimated the polymorphism 

rate by about 10 percent. Thus we might expect the actual 

polymorphism rates for these markers in longleaf pine and 

slash pine to be higher.

CONCLUSION

Loblolly pine SSR primer pairs proved to be a very good 

source of genetic markers for shortleaf pine, as well as 

for longleaf pine and slash pine. Thirty-two out of 50 

PCR primer pairs successfully amplifi ed high quality, 

polymorphic SSR markers in shortleaf pine. We are 

currently evaluating additional loblolly pine SSR markers. 

Based on the results of this study, we expect that a relatively 

high proportion of these markers will be transferable to 

shortleaf pine. With an average expected heterozygosity of 

about 0.70, these markers should provide a valuable tool in 

species restoration and conservation programs that require 

population genetic data and analysis.

ACKNOWLEDGMENTS

We thank Larry Lott and Dennis Deemer (Southern Institute 

of Forest Genetics), respectively, for making sample 

collections and assisting in scoring with GeneMapper, and 

Tom Kubisiak for helpful comments in review.

LITERATURE CITED

Al-Rabab’ah, M.A.; Williams, C.G. 2002. Population 

dynamics of Pinus taeda L. based on nuclear 

microsatellites. Forest Ecology and Management. 163: 

263-271.

Al-Rabab’ah, M.A.; Williams, C.G. 2004. An ancient 

bottleneck in the Lost Pines of central Texas. Molecular 

Ecology. 13: 1075-1084.

Auckland L.D.; Bui T.; Zhou Y.; Shepherd M.; Williams 

C.G. 2002. Conifer microsatellite handbook. College 

Station, TX: Texas A&M University. 57 p.

Dyer, R.J.; Sork, V.L. 2001. Pollen pool heterogeneity in 

shortleaf pine, Pinus echinata Mill. Molecular Ecology. 

10: 859-866.

Echt, C.; Burns, R. 1999. SSR derived from Pinus taeda

ESTs. [online]. Available: http://dendrome.ucdavis.

edu/dendrome_genome/ssr-est.html.

Edwards, M.A.; Hamrick, J.L. 1995. Genetic variation in 

shortleaf pine, Pinus echinata Mill. (Pinaceae). Forest 

Genetics. 2: 21-28. 

Huneycutt, J.L.; Askew, G.R. 1989. Electrophoretic 

identifi cation of loblolly pine – shortleaf pine hybrids. 

Silvae Genetica. 38: 95-96. 

Liewlaksaneeyanawin, C.; Ritland, C.E.; El-Kassaby, Y.A.; 

Ritland, K. 2004. Single-copy, species-transferable 

microsatellite markers developed from loblolly pine 

ESTs. Theoretical and Applied Genetic. 109(2): 

361-369.

Little, E.L., Jr.; Critchfi eld, W.B. 1969. Subdivisions of the 

genus Pinus (pines). Misc. Publ. 1144. Washington, 

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

Nei, M. 1978. Estimation of average heterozygosity and 

genetic distance from a small number of individuals. 

Genetics. 89: 583-590.

Raja, R.G.; Tauer, C.G.; Wittwer, R.F.; Huang, Y. 1997. An 

isoenzymatic study of the genetic structure in natural 

populations of shortleaf pine, Pinus echinata Mill. 

Canadian Journal of Forest Research. 27(5): 740-749.

Schmidtling, R.C.; Hipkins V. 1998. Genetic diversity in 

longleaf pine (Pinus palustris): infl uence of historical 

and prehistorical events. Canadian Journal of Forest 

Research. 28: 1135-1145.

Shepherd, M.; Cross, M.; Maguire, T.L.; Dieters, M.J.; 

Williams, C.G.; Henry, R.J. 2002. Transpecifi c 

microsatellites for hard pines. Theoretical and Applied 

Genetics. 104(5): 819-827.

Wells, O.O.; Wakeley, P.C. 1970. Variation in shortleaf pine 

from several geographic sources. Forest Science. 16(4): 

415-423.
99

CHROMOSOMAL LOCATIONS OF THE RIBOSOMAL DNA GENES IN SHORTLEAF PINE

Nurul Islam-Faridi, M. Abdul Majid, and C. Dana Nelson1

ABSTRACT.—A reference karyotype (i.e., chromosome-specifi c description of a species’ 

chromosomal complement) is a pre-requisite for advanced genetic and genomic studies. The 

Southern Institute of Forest Genetics has initiated a project to develop reference karyotypes 

for each of the major southern U.S. pine species, including shortleaf pine, using AT-rich 

chromosomal banding and fl uorescent in situ hybridization (FISH). About half of the project has 

been completed to date, including the development of karyotypes for loblolly pine and slash 

pine, with the remaining experiments being directed towards shortleaf pine and longleaf pine. 

Preliminary FISH results for rDNA genes in shortleaf pine show that there are seven major, and 

as many as eight medium-to-minor centromeric 18S-28S rDNA sites. In addition, one major 

and one minor 5S rDNA sites were observed and most of the chromosomes showed AT-rich 

bands. A complete shortleaf pine karyotype is being developed for comparison with other pine 

and conifer species.

1

Research Geneticist (NI-F), US Forest Service, Southern Institute 

of Forest Genetics, Forest Tree Molecular Cytogenetics Laboratory, 

Texas A&M University, College Station, TX 77843; Research 

Associate (MAM), Department of Forest Science, Texas A&M 

University, College Station, TX 77843; Research Geneticist and 

Project Leader (CDN), US Forest Service, Southern Institute of 

Forest Genetics, Harrison Experimental Forest, 23332 Mississippi 

67, Saucier, MS 39574. NI-F is corresponding author: to contact call 

(979) 862-3908 or email nfaridi@tamu.edu

INTRODUCTION

The genus Pinus (2n = 2x = 24), originally confi ned 

almost entirely to the northern hemisphere, includes 

many economically and ecologically important species. 

Loblolly pine (Pinus taeda L.), slash pine (P. elliottii var. 

elliottii Englm.), shortleaf pine (P. echinata Mill.), and 

longleaf pine (P. palutris Mill.) are the four Pinus species 

most commonly planted in the southern U.S. All Pinus

species studied have 12 pairs of chromosomes with 10 or 

11 pairs of long metacentric chromosomes and one pair of 

short sub-metacentric chromosomes (Sax and Sax 1933). 

Conventional cytogenetics has been used in studying the 

pines (Mergen 1958, Borzan and Papes 1978, MacPherson 

and Filion 1981, Hizume and others 1990). However, 

combining molecular cytology, in situ hybridization (ISH), 

and conventional cytological techniques provides more 

accurate information about genomes (Heslop-Harrison 1991, 

Leitch and Heslop-Harrison 1992, Leitch and others 1992, 

Hizume and others 2002, Doudrick and others 1995). We 

recently completed a reference karyotype and cytomolecular 

map for loblolly pine (Islam-Faridi and others 2007), as 

part of our institute’s southern pine karyotyping project at 

the Southern Institute of Forest Genetics. In this paper, we 

present some preliminary data from our investigation of 

shortleaf pine.

MATERIALS AND METHODS

Plant Material

Seeds from an open-pollinated shortleaf pine clone, WO5, were treated with 1 percent hydrogen peroxide to break 

dormancy and then germinated in the dark on moist fi lter 

paper in petri-dishes at 24  ̊C. Germinated seedlings were 

transferred to potting mix in pots and allowed to grow in a 

greenhouse prior to harvesting of root tips for cytogenetic 

analysis.

Slide Preparation

Actively growing roots tips, about 1.5 cm long, were 

excised and pretreated in 0.15 percemt colchicine (Sigma, 

P-9754) for 7 h at room temperature in the dark and then 

fi xed in 2:1:1 ethanol (95 percent)-acetic acid-double 

distilled water. The fi xed roots were treated enzymatically 

as described by Jewell and Islam-Faridi (1994). The 

digested root tips were macerated on a cleaned slide in 3:1 

ethanol-acetic acid and squashed in 45 percent acetic acid 

with a cover glass (Islam-Faridi and others 2007). Finally, 

chromosome spreads were stored at -80  ̊C until used for 

fl uorescence in situ hybridization (FISH).

Probe DNA and Nick Translation

Whole plasmids containing 18S-28S rDNA or 5S rDNA 

inserts were labeled by nick translation using biotin-16-

dUTP (Biotin-Nick Translation Mix, Roche Diagnostics).

Fluorescent In situ Hybridization

A standard in situ hybridization technique was followed 

(Islam-Faridi and Mujeeb-Kazi 1995). Probe hybridization 

sites were detected with Cy3 fl uorochrome conjugated 
100

streptavidin. The chromosome preparations were also 

counterstained with 4’-6-Diamidino-2-phenylindole (DAPI, 

4 μg/ml) and mounted by Vectashield (Vector Laboratories) 

to prevent fl uorochrome bleaching.

Microscopy

Digital images were recorded from an Olympus AX-70 epifl uorescence microscope with suitable monochrome fi lter 

sets (Chroma Technology) using a 1.3 MP Sensys (Roper 

Scientifi c) camera and a MacProbe v4.2.3 digital image 

system (Applied Imaging). Images were processed with 

MacProbe v4.2.3 and Adobe Photoshop CS 8.

RESULTS AND DISCUSSION

We modifi ed a technique for preparing pine chromosomes 

that consistently provides a high number of metaphase 

chromosome spreads in various pine species, including 

shortleaf pine. When our modifi ed technique was employed, 

a single root tip yielded as many as 650 metaphase cells 

with as many as 40 of these containing well separated 

chromosomes that are ideal for DAPI and FISH analysis.

Various patterns of DAPI bands occurred near or around 

the centromere of most shortleaf pine chromosomes. Some 

of the centromeric DAPI bands appeared at both sides 

of the centromere, while others were clearly on one side 

or the other. Intercalary (the area between a centromere 

and a telomere) DAPI bands were also observed in some 

chromosomes. Similar results have been obtained for 

loblolly pine (Islam-Faridi and others 2007).

In shortleaf pine, we observed 13 major and 17 medium-tominor 18S-28S rDNA signals (Fig. 1). All major and one 

medium (Fig. 1a and 1b, arrowheads) signals are located at 

intercalary positions, representing seven homologous loci, 

with one locus containing a major and a medium signal. A 

similar observation was also reported and has been observed 

for slash pine (Doudrick and others 1995, Islam-Faridi 

and others unpublished). In contrast, loblolly pine shows 

14 major signals, two each for the seven homologous loci 

(Jacobs and others 2000, Islam-Faridi and others 2007). This 

observation suggests that the shortleaf pine and slash pine 

homologues with the medium signal lack several hundreds 

to thousands of copies of the highly repetitive 18S-28S 

rDNA gene. The remaining medium-to-minor intensity 

signals are located at or near centromeric positions. Taken 

together, these observations indicate that the shortleaf pine 

karyotype is more similar to slash pine than it is to loblolly 

pine.

The longest chromosome (i.e., chromosome 1) in shortleaf 

pine can easily be identifi ed by its 5S rDNA signal (Figs. 

1a and 1b, arrows), which appears to be the major 5S rDNA 

site. In addition, a minor 5S rDNA site was observed (Fig. 

1a, insert). This second 5S rDNA site appeared toward the 

end of a different chromosome, which also showed a major 

intercalary 18S-28S rDNA site located on the opposite arm. 

Chromosome 2 of the loblolly pine reference karyotype has 

the same distinguishing characteristics (Islam-Faridi and 

others 2007).

Further studies including use of an Arabidopsis–type 

telomere repeat sequence (A-type TRS) probe are being 

carried out to develop a comprehensive shortleaf pine 

karyotype for comparison with our loblolly pine reference 

karyotype (Islam-Faridi and others 2007) and two slash 

pine karyotypes (Doudrick and others 1995, Islam-Faridi 

and others unpublished). Cytogenetic analyses including 

karyotype comparisons are useful in identifying structural 

rearrangements (i.e., large translocations and/or inversions) 

within and between species which can be used to infer 

evolutionary relationships, to inform gene conservation 

efforts, and to guide interspecies breeding projects. 

ACKNOWLEDGMENT

We thank Gay Flurry (Southern Institute of Forest Genetics, 

Saucier, MS) for processing the shortleaf pine seeds and for 

his assistance in growing the seedlings.

Figure 1.—FISH with 18S-28S rDNA and 5S rDNA probes 

on somatic metaphase chromosome spread of shortleaf 

pine, clone WO-5. The major 5S rDNA site is located on 

chromosome 1 (arrows, a and b). Also shown is a medium 

intercalary 18S-28S rDNA signal (arrowheads, a and b). 

The second 5S rDNA site is shown in the insert of a (arrow). 

Bar = 10 μm.
101

LITERATURE CITED

Borzan, Z.; Papes, D. 1978. Karyotype analysis in Pinus: 

A contribution to the standardization of the karyotype 

analysis and review of some applied techniques. Silvae 

Genetica. 27: 144-150.

Doudrick, R.L.; Heslop-Harrison, J.S.; Nelson, C.D.; 

Schmidt, T.; Nance, W.L.; Schwarzacher, T. 1995. 

Karyotype of slash pine (Pinus elliottii var. elliottii) 

using patterns of fl uorescence in situ hybridization 

and fl uorochrome banding. Journal of Heredity. 86: 

289-296.

Heslop-Harrison, J.S. 1991. The molecular cytogenetics of 

plants. Journal of Cell Science. 100: 15-21.

Hizume, M.; Arai, M.; Tanaka, A. 1990. Chromosome 

banding in the genus Pinus. III. Fluorescent banding 

pattern of P. luchuensis and its relationships among the 

Japanese diploxylon pines. Botanical Magazine, Tokyo. 

103: 103-111.

Hizume, M.; Shibata, F.; Matsusaki, Y.; Garajova, Z. 2002. 

Chromosome identifi cation and comparative karyotypic 

analyses of four Pinus species. Theoretical and Applied 

Genetics. 105: 491-497.

Islam-Faridi, M.N.; Mujeeb-Kazi, A. 1995. Visualization of 

Secale cereale DNA in wheat germplasm by fl uorescent 

in situ hybridization. Theoretical and Applied Genetics. 

90: 595-600.

Islam-Faridi, M.N.; Nelson C.D.; Kubisiak, T.L. In press. 

Reference karyotype and cytomolecular map for 

loblolly pine (Pinus taeda L.). Genome.

Jacobs, M.D.; Gardner, R.C.; Murray, B.G. 2000. 

Cytological characterization of heterochromatin and 

rDNA in Pinus radiata and P. taeda. Plant Systematics 

and Evolution. 223: 71-79.

Jewell, D.C.; Islam-Faridi, M.N. 1994. Details of a 

technique for somatic chromosome preparation and 

C-banding of maize. In: Freeling, M.; Walbot, V., eds. 

The maize handbook. New York: Springer-Verlag: 

484-493.

Leitch, I.J.; Heslop-Harrison, J.S. 1992. Physical mapping 

of the 18S-5.8S-25S rRNA genes in barley by in situ

hybridization. Genome. 35: 1013-1018.

Leitch, I.J.; Mosgoller, W.; Shi, M.; Heslop-Harrison, 

J.S. 1992. Different patterns of rDNA organization at 

interphase in nuclei of wheat and rye. Journal of Cell 

Science. 101: 751-757.

MacPherson, P.; Filion, W.G. 1981. Karyotype analysis and 

the distribution of constitutive heterochromatin in fi ve 

species of Pinus. Journal of Heredity. 72: 193-198.

Mergen, F. 1958. Natural ploidy in slash pine. Forest 

Science. 4: 283-295.

Sax, K.; Sax, H.J. 1933. Chromosome number and 

morphology in the conifers. Journal of the Arnold 

Arboretum. 15: 356-375.
102

EXTENDED ABSTRACT

It is well known that shortleaf pine (Pinus echinata Mill.), 

loblolly pine (Pinus taeda L.), and Virginia pine (Pinus 

virginiana Mill.) sustain signifi cantly more Nantucket pine 

tip moth (Rhyacionia frustrana Comst.) damage than do 

slash pine (Pinus elliotti var. elliotti Engelm.) and longleaf 

pine (Pinus palustris Mill.) (Berisford and Ross 1990, 

Wakeley 1928). Understanding the cause of this difference 

in susceptibility is important since tip moth can be a serious 

pest, especially in commercial pine plantations. This study 

provides further information about the inheritance of 

susceptibility to tip moth damage in southern pine trees.

Three shortleaf pine x loblolly pine inter-specifi c F1 hybrid 

trees were control pollinated with shortleaf pine, loblolly 

pine, and slash pine trees and fi eld tested at two sites in 

southeast Mississippi—Harrison Experimental Forest and 

Erambert Seed Orchard. In addition to the control-pollinated 

families, each parent was also tested as an open-pollinated 

(OP) family. Nineteen families were evaluated for height 

growth, number of branches, and percent of trees damaged 

by tip moth over 2 years (Table 1).

Overall, test trees were almost twice as tall at Erambert 

(129 cm vs. 70 cm). Both sites exhibited a relatively low 

amount of tip moth damage, although there was signifi cantly 

more damage at Harrison (35.4 percent trees infested vs. 

26.2 percent). F1 x OP families had the highest tip moth 

damage at both sites (46 percent and 38 percent), while the 

slash pine x OP families had the lowest (<10 percent). The 

average number of branches per tree was similar at each 

site, but slightly higher at Erambert (19.7 vs. 17.7). Interspecies crosses having lesser amounts of shortleaf pine per 

family were taller than those with larger amounts (Figure 

1A), and, as expected, the opposite was true for loblolly 

pine. For tip moth, crosses with intermediate amounts 

(~50 percent) of shortleaf pine or loblolly pine were most 

damaged (Figure 1B). 

SHORTLEAF PINE HYBRIDS: GROWTH AND TIP MOTH DAMAGE 

IN SOUTHEAST MISSISSIPPI

Larry H. Lott, Maxine T. Highsmith, and C. Dana Nelson1

1

Biological Science Technician (LHL), U.S. Forest Service, Southern 

Institute of Forest Genetics, Harrison Experimental Forest, Saucier, 

MS 39574; Associate Professor (MH), Department of Natural Science 

and Mathematics, Shaw University, Raleigh, NC, and Department 

of Forestry and Environmental Resources, North Carolina State 

University, Raleigh, NC; Research Geneticist and Project Leader 

(CDN), U.S. Forest Service, Southern Institute of Forest Genetics, 

Harrison Experimental Forest, 23332 Mississippi 67, Saucier, MS 

39574. CDN is corresponding author: to contact, call (228) 832-2747 

or email dananelson@fs.fed.us

These fi ndings are in keeping with results of other coastal 

plain experimental plantings of susceptible and resistant 

pines and their inter-specifi c hybrids (Highsmith and others 

2001, Highsmith and others 2003, Highsmith and Lott, 

unpublished), as well as earlier reports by Chapman (1922) 

and Grano and Grigsby (1968). Although this study is small 

and only 2 years old, it suggests that tip moth resistance 

in shortleaf pine might be advanced through hybridization 

and backcrossing with slash pine. The usefulness of this 

approach should be tested using many parents and crosses, 

preferably in BC1 intercrosses (BC1 x BC1) to allow for 

selection for tip moth resistance and adaptability to shortleaf 

pine environments.

LITERATURE CITED

Berisford, C.W.; Ross, D.W. 1990. Conifer shoot borers: a 

review of some major forest pests. Science in Forestry: 

IUFRO’s Second Century, IUFRO World Congress 

XIX, Montreal, Canada: 5-11.

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

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

Grano, C.X.; Grigsby, H.C. 1968. Spraying southern pines 

not practical for tip-moth control. Research Note 

SO-77, New Orleans, LA: U.S. Department of 

Agriculture, Forest Service, Southern Forest 

Experiment Station. 2 p.

Highsmith, M.T.; Frampton, J.; O’Malley, D.; Richmond, 

J.; Webb, M. 2001. Susceptibility of parent and 

interspecifi c F1 hybrid pine trees to tip moth damage in 

a coastal North Carolina planting. Canadian Journal of 

Forest Research. 31: 919-923.

Highsmith, M.T.; Lott, L.H.; Gwaze, D.P.; Lominy, D.; 

Nelson, C.D. 2003. Evaluation of the inheritance of 

tip moth susceptibility using pine hybrids planted in 

southeast Mississippi. In: Proceedings of the 27th 

southern forest tree improvement conference; 2003 

June 24-27; Stillwater, OK. Stillwater, OK: Oklahoma 

State University: 208. Available at: http://digital.library.

okstate.edu/Forestry/index.html

Wakeley, P.C. 1928. Preliminary observations on the pine tip 

moth (Rhyacionia frustrana Comst.) on southern pines. 

Fourth International Congress of Entomology: 865-868.
103

Table 1.—Means for height, number of branches, and tip moth damage over both planting sites.

1

Means followed by the same letter are not signifi cantly different at p < .05. 2

 ‘.’ indicates that tip moth damage was not evaluated due to small sample size.

Family Type Families Trees Height1 Branches1 Tip Moth1

 number number cm number % damage

Slash x OP 4 254 97.4 b 13.2 c 5.1 b

Loblolly x OP 5 315 114.1 a 21.7 a 39.7 a

Shortleaf x OP 3 169 78.8 c 18.5 ab 34.9 a 

(Shortleaf x Loblolly) x OP 3 170 92.2 b 19.2 ab 49.4 a

(Shortleaf x Loblolly) x Slash2

 1 12 112.3 a 16.3 bc .

(Shortleaf x Loblolly) x Loblolly 2 124 97.6 b 22.2 a 36.3 a

(Shortleaf x Loblolly) x Shortleaf2 1 18 78.1 c 16.9 b .

0

50

100

150

0 25 50 75 100

Shortleaf Percent

0

20

40

60

80

0 25 50 75 100

Shortleaf Percent

Figure 1.—Mean tree heights and mean tip moth damage by percent shortleaf pine in the cross after 2 years in the fi eld at 

Erambert (EM) and at Harrison (HEF).

Tip moth (% damage)

Height (cm)

Year 2

Year 2

Site EM

Site HEF

Site EM

Site HEF

1A 1B
104

PHYLOGEOGRAPHIC ANALYSES AND EVALUATION OF SHORTLEAF PINE 

POPULATION STRUCTURE IN MISSOURI

Jeff Koppelman, Emily Parsons, Briedi Scott, Jennifer Collantes, Lori S. Eggert, 

Sedley Josserand, Craig Echt, and C. Dana Nelson1

1

Missouri Department of Conservation (JK, EP, BS, JC), Columbia, 

MO 65201; Biological Sciences Division (LSE), University of 

Missouri, Columbia, MO 65211; Southern Institute of Forest 

Genetics (SJ, CE, CDN), U.S. Forest Service, Saucier, MS 39574. 

JK is corresponding author. JK is corresponding author: to contact 

call (573) 882-9880 or email jeff.koppelman@mdc.mo.gov

EXTENDED ABSTRACT

A great expanse of shortleaf pine in Missouri was logged 

before the mid-20th century, and since that time, seedlings 

of the species have been planted. Due to large-scale decline 

in oak trees occupying previous shortleaf pine range, 

restoration of the shortleaf pine is a priority in Missouri. 

Restoration can be enhanced through the use of locally 

adapted trees that have the genetic background to endure 

the nutrient- and water-limited environment of the Ozark 

hillsides of southern Missouri. This study’s objective 

was to document the distribution of genetic diversity and 

population structure in natural, remnant shortleaf pine 

stands. Based on the geographic level of genetic structuring, 

the results will be used in combination with ecological and 

silvicultural results to formulate a conservation-oriented 

seed management strategy for effective restoration of the 

species.

Genetic diversity in the form of SSR (microsatellite) allelic 

variation was documented for shortleaf pine growing in four 

stands in east-central and southern Missouri. Those stands 

were selected because (1) they possessed a high abundance 

of large shortleaf pine trees, and hence were assumed to 

be natural rather than planted; and (2) they represented the 

extent of geographic distribution of the species in Missouri. 

Results from the fi rst 10 polyallelic loci examined showed 

large amounts of diversity, although results for fi ve of 

the loci were not suffi cient (< 80 percent of individuals 

resolved) to be included in population diversity analyses. 

From the second fi ve loci, sample size per site averaged 39 

and results were obtained for an average of 36 trees per site. 

We observed a mean of 8.1 alleles per locus and direct-count 

heterozygosity of 0.56. At individual loci, stand genotype 

proportions ranged from 40 to 100, with an average of 58, 

meaning that more than half of the trees in the stand had 

unique genotypes.

y = 0.0012x - 0.1571

R2 = 0.6122

0

0.1

0.2

0.3

0.4

0.5

0 50 100 150 200 250 300

Geographic Distance (km)

Genetic Distance (Rst)

Figure 1.—The relationship between genetic distance and 

geographic distancefor four stands of native shortleaf pine 

representing range extremes for the species in Missouri.

Fixation index (FST) among the stands was low at all loci 

due to the great amount of among-tree (total) diversity. 

To improve our ability to diagnose relationships between 

the old native stands, the next stage of analyses will 

include adding fi ve more loci that are not as polymorphic 

as those in the fi rst stage. In addition, the stands will be 

resampled, expanding their geographic limits and focusing 

on larger trees (>18 in DBH) to help ensure native origins. 

Geographically intermediate stands will also be selected for 

sampling to refi ne genefl ow limits, although the relationship 

between genetic diversity and geographic distance will 

likely prove to be on a scale that excludes all but the most 

distant remaining sites (Fig. 1). 
105

INTRODUCTION

A limited number of studies have focused on the 

regeneration of shortleaf pine (Pinus echinata Mill.). Many 

sites that were originally forested with shortleaf pine have 

been regenerated with loblolly pine (P. taeda L.) because 

of loblolly’s higher productivity on Coastal Plain soils. 

As a result, shortleaf pine has received little research and 

operational emphasis. During the 1970s and 1980s, the 

Ouachita National Forest in Arkansas and Oklahoma, 

and Ozark National Forest in Arkansas, developed major 

artifi cial regeneration efforts with shortleaf pine on 

their diffi cult highland sites. Traditionally, loblolly pine 

reforestation techniques were used as a model for shortleaf 

pine reforestation. Resulting regeneration success of this 

species was poor with survival typically averaging 50 

percent or less (Walker 1992). The low success achieved 

with this loblolly pine-oriented approach became a major 

concern of U.S. National Forest System silviculturists, 

who concluded that there were research opportunities for 

developing the knowledge necessary to improve the fi eld 

performance of planted shortleaf pine.

THE SHORTLEAF PINE ARTIFICIAL 

REGENERATION TASK FORCE

In late 1984, a group of 18 specialists representing USDA 

Forest Service management and research, the Weyerhaeuser 

Company, the Arkansas Forestry Commission, Oklahoma 

State University, and Louisiana State University met in 

Hot Springs, AR, to discuss the problems of shortleaf pine 

regeneration. The objectives of the session were (1) to 

identify causes of poor survival of planted shortleaf pine 

seedlings in the Ouachita and Ozark Mountains; (2) to 

determine research priorities for solving the problems of 

poor survival; and (3) to determine who could best work on 

each of the priority problems. The group agreed to form an 

ad hoc effort, the Shortleaf Pine Artifi cial Regeneration Task 

Force to be led by James Barnett and John Brissette of the 

USDA Forest Service’s Southern Forest Experiment Station 

laboratory in Pineville, LA, to address these research needs.

The areas of research considered to be productive included: 

forest genetics, seed processing and handling, seedling 

production, seedling handling and storage, and stand 

establishment. Although all of these concerns had merit, 

the task force members felt that seed and seedling quality 

should have the highest research priority, and the initial 

research emphasized these topics. Determining optimum 

stratifi cation or prechilling lengths was the highest-priority 

topic under seed quality. Identifying and evaluating 

seedlings that would perform well under stressful fi eld 

conditions was considered important. So was determining 

differences in growth responses to nursery culture by 

families, so that families with similar growth patterns 

could be grouped together for improved seed effi ciency 

and seedling uniformity. Another high-priority question 

concerned the best timing (as determined by budset and 

root growth potential) of lifting and storage to ensure good 

performance under stressful conditions. 

During the 5+ years of the Task Force’s effort, most of these 

topics were addressed to some extent. The purpose of this 

paper is to present a summary of these (Brissette and Barnett 

1992) and other pertinent study results.

REGENERATING SHORTLEAF PINE: RESULTS OF 

A 5-YEAR COOPERATIVE RESEARCH INITIATIVE

James P. Barnett and John C. Brissette1

ABSTRACT.—Shortleaf pine (Pinus echinata Mill.) is unique among the southern pines. It has 

the widest natural range and thrives on shallow rocky soils of the Interior Highlands, where 

most other pine species perform poorly. Although wood quality is excellent, it has been one of 

the most neglected species from both research and operational standpoints. It has a history of 

poor performance following outplanting with survival of less than 50 percent. The technology 

to change this situation was developed after formation of the Shortleaf Pine Artifi cial 

Regeneration Taskforce in 1984. Over a 6-year period, 15 studies were installed in Arkansas 

and Oklahoma to address seedling production and establishment. Information resulting 

from these studies resulted in increased seedling survival in both the Ozark and Ouachita 

National Forests. This paper summarizes research from these and other studies that led to the 

improved success in reforestation of the species.

1

Emeritus Scientist (JPB), Southern Research Station, U.S. Forest 

Service, Pineville, LA 71360; and Project Leader (JCB), Northern 

Research Station, U.S. Forest Service, Durham, NH 03824. JPB 

is corresponding author: to contact call (318) 473-7214 or email 

jpbarnett@fs.fed.us
106

SEED PRODUCTION

An early consideration in any reforestation program is the 

selection of superior seed sources for the region. Wells 

and Wakeley (1970) published guidelines for moving 

shortleaf pine seed. Most sites in the Arkansas and Missouri 

highlands should be replanted from local sources, or 

seed from east and north of the planting sites (Lantz and 

Kraus 1987). Tauer and McNew (1985) found relatively 

small variability among provenances and large variability 

among families. Schmidtling (2001) recently updated the 

recommendations for moving shortleaf pine seed sources 

(Fig. 1). Seedlings will survive and grow well if they come 

from any area having a minimum temperature within 

5 oF of the planting site’s minimum temperatures. Eastwest transfers within temperature isotherms are usually 

successful. Southern movement of sources across one 5 oF 

isotherm will generally result in faster growing seedlings 

(Schmidtling 2001).

Suffi cient seed orchards are present to provide genetically 

improved sources (Mexal 1992). Seed collecting, handling, 

and processing may affect seed quality. Seed maturation 

varies by half-sib family and there is variation in dormancy, 

which can be measured by speed of germination (Barnett 

and McLemore 1970, McLemore 1969). Few studies have 

evaluated the effects of cone maturity on seed extraction and 

viability, and guidelines (when cone specifi c gravity reaches 

0.89 or less) by Wakeley (1954) are generally followed.

Seed storage for shortleaf pine is usually not a problem. 

Barnett and Vozzo (1985) reported the maintenance of 

viability for 50 years under less than ideal conditions. 

Proper seed treatment maximizes the proportion of seed 

resulting in seedlings optimal for the outplanting site—

target seedlings. Treatments include: clonal collection, 

sizing seed to improve uniformity, and prechilling to speed 

emergence. Implementing these techniques improves not 

only nursery practices, but also improves long-term growth 

and yield (Mexal 1992).

Figure 1.—Shortleaf pine distribution with seed transfer guidelines based on minimum temperature isotherms. 

Within isotherms movement east-west is usually successful (Schmidtling 2001).

Minimum temperature isotherms (°F)

Natural distribution of shortleaf pine

Seed transfer guidelines
107

NURSERY PRODUCTION

Signifi cant advances in shortleaf pine seedling culture 

have been made over the last 40 years. As a result, target 

seedling specifi cations for bareroot stock have become more 

restrictive (Table 1). Standards for root/shoot (R/S) ratios 

and number of lateral roots have been developed (Mexal 

1992). These data have been compiled from a number of 

studies over the years. Early studies were infl uenced by 

the small seeds of the species. Seedlings were grown at 

high seedbed densities (>500/m2

) (Wakeley 1954). As a 

result, seedlings were small when lifted, and survival after 

outplanting was often low.

Seed Treatment

Seed treatments should maximize the proportion of the 

seed that uniformly germinates and results in target 

seedlings (Barnett 1996). If collecting, processing, and 

storing activities result in good initial seed quality, seed 

treatments can enhance seed performance. Treatments may 

include: clonal collection and sowing, removal of empty 

and damaged seeds, sizing to improve uniformity, and 

stratifi cation to speed emergence. Clonal collection, removal 

of empty and damaged seeds, and sizing are techniques 

commonly used to improve the uniformity of seedling 

germination and development of any southern pine species. 

Although seed sizing may improve germination of some 

portion of the seed lot, seed sizing improves uniformity of 

germination within the different sizing categories. 

Stratifi cation or prechilling recommendations are 

specifi cally developed for each species. However, this 

treatment is often inappropriately applied. Stratifi cation 

treatments are usually based on laboratory tests that 

invariably indicate that 30 days of treatment result in the 

highest germination (Barnett 1992). However, the minimum 

length of stratifi cation is longer, often 60 days, if the tests in 

the laboratory are conducted under lower temperatures that 

refl ect actual nursery conditions.

The objective of stratifi cation is to overcome dormancy and 

thus improve both amount and uniformity of germination, 

thereby increasing the number of target seedlings in the 

nursery. Stratifi cation speeds germination, which permits 

earlier seedling establishment. Seedlings that emerge earlier 

in the season are more likely to survive and meet target 

seedling standards at harvest (Fig. 2). Seedlings emerging 

during the fi rst 2 weeks after sowing were the largest at the 

end of the growing season, and accounted for 60 percent 

of the germinants meeting planting specifi cations (Barnett 

1992).

Parameter Mexal and South 1991 Anon. 1989 Barnett et al. 1986 Wakeley 1954

Shoot height (cm) 15-25 20 15-25 10-30

Root collar dia. (mm)

Cull <4.0 -- <2.5 <3.0

Optimum <5.0 <4.8 2.5-5.0 >3.0

Root/shoot ratio >0.4 0.4 0.4 --

Lateral roots (no.) >7 >5 7 --

Tap root length (cm) -- 15 10-20 --

Terminal bud -- Present Well developed Present

Mycorrhizae Many Abundant -- --

Table 1.—Changes in target shortleaf pine bareroot seedling specifi cations from 1954 to 1991 (Mexal 1992).

Figure 2.—Effect of time of emergence on mortality and 

height after one growing season of shortleaf pine seedlings 

(after Barnett 1992).
108

Seedling Quality

Seedling quality refers to seedlings that when planted will 

survive and show acceptable growth. The nursery system 

that produces quality stock incorporates the latest research 

information and applies it through the best technology 

available. Such technology for shortleaf pine includes: 

seed treatment as discussed in the previous section (Barnett 

1992), sowing early and growing at low seedbed densities 

(about 200/m2

) (Brissette and Carlson 1987), and fertilizing 

at moderate rates of nitrogen (Brissette et al. 1989). 

The aforementioned recommended nursery practices usually 

increase the size of shortleaf pine seedlings, and improve 

the balance between R/S biomass (Mexal 1992). The 

importance of the R/S in survival of loblolly pine seedlings 

was demonstrated by Mexal and Dougherty (1982). 

Research by Brissette and Barnett (1989) indicates it can 

also predict early growth of shortleaf pine (Fig. 3).

Shortleaf pine seeds collected from six half-sib families 

were grown as both bare-root and container stock and 

outplanted on two sites in the Ouachita Mountains of 

Arkansas. Survival and growth were measured at years 

1, 3, 5, and 10 after planting. When outplanted, the bareroot seedlings had greater mean height and root-collar 

diameters than the container seedlings. However, the 

container seedlings had greater mean root volume and more 

favorable R/S ratios than the bareroot stock. Height growth 

of container and bareroot seedlings was correlated with R/S 

ratio following planting. Survival of both stock types was 

excellent, exceeding 90 percent after 10 years. The container 

stock performed consistently better than the bareroot at each 

interval measured, but there were no statistically signifi cant 

interactions between stock type and half-sib family at 3, 5, 

or 10 years (Barnett and Brissette 2004).

Although visible presence of mycorrhizae on pine seedling 

roots has been known to improve survival for many decades 

(Jorgensen and Shoulders 1967), inoculation of seedlings 

in the nursery usually is not necessary (Mitchell and South 

1992). Inoculation by airborne spores occurs in most 

nurseries within pine forest types. Harsh nursery lifting 

techniques can strip much of the visible mycorrhizae from 

seedlings and reduce survival.

SEEDLING CARE AND HANDLING

Care and handling activities include timing of lifting, 

sorting, length of storage, method of storage, and 

transportation. The handling practices for shortleaf pine 

might be expected to be similar to loblolly pine (Mexal 

1992); however, Venator (1985) found shortleaf pine was 

sensitive to storage. Although unstored seedlings maintained 

fairly uniform survival when outplanted from early 

November through early April, seedlings stored 30 days at 

36 oF survived poorly when planted in November, March, 

and April (Hallgren 1992). Survival of seedlings stored 30 

days averaged 10 percentage points lower than just-lifted 

seedlings during the optimum planting season (Fig. 4). 

Ability to regenerate new roots is apparently correlated 

with survival of shortleaf seedlings. Brissette and others 

(1988) found root growth potential (RGP) of shortleaf pine 

sensitive to chilling hour accumulation (0 to 8 oC at 200 

mm above the ground). When lifting date was expressed 

in accumulated chilling hours, maximum RGP after lifting 

occurred after 610 hours, but no strong interaction occurred 

with cold storage. Hallgren (1992) did report maximum 

RGP following storage for seedlings lifted after 700 hours 

of chilling.

Improving storage life of shortleaf pine seedlings by treating 

the roots with a clay slurry-fungicide (Benomyl®) coating 

at packing signifi cantly increased fi eld survival. Barnett and 

others (1988) reported that treated seedlings could be stored 

for 6 weeks with no reduction in survival (Fig. 5). Survival 

Figure 3.—Relationship between R/S and fi rst-year height 

growth of bareroot and container shortleaf pine seedlings 

(after Brissette and Barnett 1989).

Figure 4.—Effect of lift date and 0-day or 30-day storage 

on the survival of shortleaf pine seedlings in Arkansas and 

Oklahoma (after Hallgren 1992).
109

of nontreated seedlings was reduced 15 percent after only 

3 weeks, and 60 percent after 6 weeks of storage. These 

results with shortleaf pine were confi rmed in a study by 

Hallgren (1992).

Although there was a strong effect of seedling storage on 

survival, growth following outplanting was not related to 

storage period or time (Hallgren 1992). Seedling heights 

after 2 years appeared more closely related to planting date. 

Maximum growth occurred for the December, January, 

and February plantings. Early planted seedlings provided 

greater opportunity for height growth the following spring 

and summer (South and Mexal 1984). In addition to reduced 

growth, planting late (mid-March and April) reduced growth 

10 to 30 percent (Hallgren 1992).

SITE PREPARATION

Site preparation can be the most expensive activity in 

establishing a southern pine forest (Dougherty 1992). As 

with most expenditures, you usually get what you pay for. 

The key is to select those practices that are most appropriate 

for the site and species. Two practices that are commonly 

used for shortleaf pine regeneration on mountainous sites 

are ripping and chemical weed control (Mexal 1992). 

Ripping has been a common practice in the Ouachita 

Mountains for the last three decades (Sossaman and others 

1980). The ripper blades tend to pull large rocks from the 

trench and increase the proportion of soil in the opening. 

Ripping usually improves plantability and soil moisture as 

the trench serves as a catchment basin for water fl ow (Mexal 

1992). However, results of some long-term evaluations 

of ripping indicate that site preparation burning alone is 

equally effective in improving seedling survival and growth 

(Gwaze and others, in press).

Mountainous sites are typically droughty, and chemical 

weed control improves soil moisture by removing the 

Figure 5.—Improvement in survival of stored shortleaf pine 

seedlings following treatment with Benomyl® (after Barnett 

and others 1998).

vegetation that would otherwise increase stress due to 

competition. Yeiser and Barnett (1991) found that the 

growth response of shortleaf pine to weed control will last 

2 years following either spot or total chemical application. 

The improved performance is likely due to improved water 

relations and light availability. In this study, total weed 

control was superior to spot control, but some weeds may 

actually protect shortleaf from severe infestations of tipmoth 

(Rhyacionia frustrana Cornstock) (Mexal 1992). 

PLANTING

Successful reforestation requires a system of quality control 

through all phases of establishment. Poor planting can result 

in poor survival and reduced growth and yield, or both. 

Early evidence of poor planting is not always apparent 

(Mexal 1992). Harrington and others (1987) found that 30 

percent of planted shortleaf pine seedlings lacked a taproot 

compared to 15 percent for seedlings seeded in place. 

Seedlings with a vertical taproot exhibited greater height 

growth than trees with root systems deformed by spiraling 

or shallow planting. 

Harrington and others (1989) conducted additional studies 

on root orientation of surviving trees, but did not relate 

root deformation to survival. Brissette and Barnett (1989) 

found that deformation decreased survival of loblolly pine 

seedlings. Shallow planting was most detrimental, but 

J-rooting also decreased survival. Proper planting is key to 

improving survival and early seedling growth. 

POST-PLANTING CARE

Regulating competition is probably the most important 

issue to address after planting to help achieve a successful 

plantation. Early weed control increases survival and growth 

(Yeiser 1992). Competition is commonly from grass, 

hardwood sprouts, and other planted pines. In a 12-year 

study reported by Cain and Barnett (2002), competition 

control from grasses and forbs increased survival by 68 

percentage points for natural pines and 47 percent for 

planted pines. Volume gains of 150 to 200 percent were 

achieved after 12 years within the regeneration techniques 

as a result of release. 

CONCLUSIONS

Successful artifi cial regeneration of shortleaf pine requires 

production of consistently uniform seedlings by either 

bareroot or container methods, adequate site preparation 

that improves the planting site, proper planting techniques, 

and control of competition for 1 or 2 years after outplanting. 

Successful establishment of shortleaf pine on its native sites 

is an accomplishment that is satisfying to many landowners 

in the highland areas of the South. 
110

LITERATURE CITED

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Shortleaf Pine Regeneration Workshop; 1991 October 

29-31; Little Rock, AR. Gen. Tech. Rep. SO-90. New 

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

Service, Southern Forest Experiment Station: 20-31.

Barnett, J.P. 1996. How seed orchard culture affects seed 

quality: experience with the southern pines. Forestry 

Chronicle. 72: 469-473.

Barnett, J.P.; Brissette, J.C. 2004. Stock type affects 

performance of shortleaf pine planted in the Ouachita 

Mountains through 10 years. In: Connor, Kristina F., ed. 

Proceedings of the 12th biennial southern silvicultural 

research conference. Gen. Tech. Rep. SRS-71. 

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

Service, Southern Research Station: 420-422.

Barnett, J.P.; Brissette, J.C.; Carlson, W.C. 1986. Artifi cial 

regeneration of shortleaf pine. In: Proceedings, 

Symposium on the Shortleaf Pine Ecosystem; 1986 

March 31-April 2; Little Rock, AR. Little Rock, AR: 

Arkansas Cooperative Extension Service: 64-88.

Barnett, J.P.; Brissette, J.C.; Kais, A.G.; Jones, J.P. 1988. 

Improving fi eld performance of southern pine seedlings 

by treating with fungicides before storage. Southern 

Journal of Applied Forestry. 12: 281-285.

Barnett, J.P.; McLemore, B.F. 1970. Storing southern pine 

seeds. Journal of Forestry. 68: 24-27.

Barnett, J.P.; Vozzo, J.A. 1985. Viability and vigor of slash 

and shortleaf pine seeds. Forest Science. 31: 316-320.

Brissette, J.C.; Barnett, J.P. 1989. Comparing fi rst-year 

growth of bare-root and container plantings of shortleaf 

pine half-sib families. In: Proceedings of the 20th 

Southern Forest Tree Improvement Conference, 1989 

June 26-30; Charleston, SC. Atlanta, GA: Southern 

Forest Tree Improvement Committee: 354-361.

Brissette, J.C.; Barnett, J.P., editors. 1992. Proceedings 

of the Shortleaf Pine Regeneration Workshop, 1991 

October 29-31; Little Rock, AR. Gen. Tech. Rep. SO90. New Orleans, LA: U.S. Department of Agriculture, 

Forest Service, Southern Forest Experiment Station. 

236 p.

Brissette, J.C.; Barnett, J.P.; Gramling, C.L. 1988. Root 

growth potential of southern pine seedling grown at the 

W.W. Ashe Nursery. In: Lantz, C.W., ed. Proceedings of 

the Southern Forest Nursery Association, 1988 July 25-

28, Charleston, SC. Atlanta, GA: U.S. Department of 

Agriculture, Forest Service, Southern Region: 173-183.

Brissette, J.C.; Carlson, W.C. 1987. Effects of nursery 

density on shortleaf pine. In: Landis, T.D., tech. coord. 

Proceedings International Forest Nursery Association; 

1987 August 10-14; Oklahoma City, OK. Gen. Tech. 

Rep. RM-151. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Forest 

and Range Experiment Station: 36-41.

Brissette, J.C.; Tiarks, A.E.; Carlson, W.C. 1989. Comparing 

the effects of equal versus increasing application rates 

of nitrogen on the quality of shortleaf pine seedlings. 

In: Miller, J.H., compl. Proceedings of the Fifth 

Biennial Southern Silvicultural Research Conference. 

Gen. Tech. Rep. SO-74. New Orleans, LA: U.S. 

Department of Agriculture, Forest Service, Southern 

Forest Experiment Station: 95-100.

Cain, M.D.; Barnett, J.P. 2002. Effects of early release 

on natural versus container loblolly pines 12 years 

after fi eld establishment. Southern Journal of Applied 

Forestry. 26: 173-180.

Dougherty, P.M. 1992. Site preparation. In: Brissette, J.C.; 

Barnett, J.P., eds. Proceedings of the Shortleaf Pine 

Regeneration Workshop; 1991 October 29-31; Little 

Rock, AR. Gen. Tech. Rep. SO-90. New Orleans, 

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

Southern Forest Experiment Station: 58-66.

Gwaze, D.P.; Melick, R.; McClure, L.; Studyvin, C. Effects 

of site preparation sub-soiling and prescribed burning 

on survival and growth of shortleaf pine in the Mark 

Twain National Forest: results after 20 growing seasons. 

In: Shortleaf pine restoration and ecology in the Ozarks: 

proceedings of a symposium; 2006 November 7-9; 

Springfi eld, MO. Gen. Tech. Rep. Newtown Square, 

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

Northern Research Station. 

Hallgren, S.W. 1992. The impact of lift and store practices 

on fi eld performance of shortleaf pine seedlings. In: 

Brissette, J.C.; Barnett, J.P., eds. Proceedings of the 

Shortleaf Pine Regeneration Workshop; 1991 October 

29-31; Little Rock, AR. Gen. Tech. Rep. SO-90. New 

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

Service, Southern Forest Experiment Station: 46-57.

Harrington, C.A.; Carlson, W.C.; Brissette, J.C. 1987. 

Relationships between height growth and root system 

orientation in planted and seeded loblolly and shortleaf 

pines. In: Proceedings, Fourth Biennial Southern 

Silvicultural Research Conference; 1986 November 

4-6; Atlanta, GA. Gen. Tech. Rep. SE-42. Asheville, 

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

Southeastern Forest Experiment Station: 53-60.
111

Harrington, C.A.; Brissette, J.C.; Carlson, W.C. 1989. Root 

system structure in planted and seeded loblolly and 

shortleaf pine. Forest Science. 35: 469-480.

Jorgensen, J.R.; Shoulders, Eugene. 1967. Mycorrhizal root 

development vital to survival of slash pine nursery 

stock. Tree Planters’ Notes. 18 (2): 7-11.

Lantz, C.W.; Kraus, J.F. 1987. A guide to southern pine seed 

sources. Gen. Tech. Rep. SE-43. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, Southeastern 

Forest Experiment Station. 34 p.

McLemore, B.F. 1969. Long stratifi cation hastens 

germination of loblolly pine seed at low temperatures. 

Journal of Forestry. 67: 419-420.

Mexal, J.G. 1992. Artifi cial regeneration of shortleaf pine. 

Put it all together for success. In: Brissette, J.C.; 

Barnett, J.P., eds. Proceedings of the Shortleaf Pine 

Regeneration Workshop; 1991 October 29-31; Little 

Rock, AR. Gen. Tech. Rep. SO-90. New Orleans, 

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

Southern Forest Experiment Station: 172-186.

Mexal, J.G.; Dougherty, P.M. 1982. Growth of loblolly pine 

seedlings. In: IV. Performance in a simulated drought 

environment. Res. Pap. 050-1422/6. Federal Way, WA: 

Weyerhaeuser Company. 24 p.

Mexal, J.G.; South, D.B. 1991. Bareroot seedling culture. 

In: Duryea, M.L.; Dougherty, P.M., eds. Forest 

regeneration manual. Dordrecht, The Netherlands: 

Kluwer Acad. Publishers: 89-115.

Mitchell, R.J.; South, D.B. 1992. Cultural enhancement of 

mycorrhizal fungi on southern pines? In: Chiang, C.H.; 

Wang, Y.N., eds. Proc. Joint International Symposium 

on Air Pollution, Soil Microbiology and Biotechnology 

of Forestry; 1992 June 1-5; Taipei, Taiwan. Taipei, 

Taiwan: National Taiwan University: 145-153.

Schmidtling, R.C. 2001. Southern pine seed sources. Gen. 

Tech. Rep. SRS-44. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research Station. 

25 p.

Sossaman, E.C., Mexal, J.G.; Bailey, R.L. 1980. Responses 

of loblolly pine seedlings to soil ripping—fourth year 

update. Forest Res. Pap. 042-211/80/21. Federal Way, 

WA: Weyerhaeuser Company. 8 p.

South, D.B.; Mexal, J.G. 1984. Growing the “best” 

seedlings for reforestation success. Forestry Department 

Series No. 12. Auburn, AL: Auburn University, 

Alabama Agric. Experiment Station. 11 p. 

Tauer, C.G.; McNew, R.W. 1985. Inheritance and correlation 

of growth of shortleaf pine in two environments. Silva 

Genetica. 34: 5-11.

U.S. Forest Service. 1989. A guide to the care and planting 

of southern pine seedlings. Bull. R8-MB39. Atlanta, 

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

Southern Region. 44 p.

Venator, C.R. 1985. Survival of shortleaf pine (Pinus 

echinata Mill.) seedlings as infl uenced by nursery 

handling and storage. Tree Planters’ Notes. 36: 17-19.

Wakeley, P.C. 1954. Planting the southern pines. Monograph 

18. Washington, D.C. U.S. Department of Agriculture. 

233 p.

Walker, W.D. 1992. Historical perspectives on regeneration 

in the Ouachita and Ozark Mountains—the Ouachita 

National Forest. In: Brissette, J.C.; Barnett, J.P. 

eds. Proceedings of the shortleaf pine regeneration 

workshop; 1991 October 29-31; Little Rock, AR. 

Gen. Tech. Report SO-90. New Orleans, LA: U.S. 

Department of Agriculture, Forest Service, Southern 

Forest Experiment Station: 12-17.

Wells, O.O.; Wakeley, P.C. 1970. Variation in shortleaf pine 

from several geographic sources. Forest Science. 16: 

415-423.

Yeiser, J.L. 1992. Post-estabishment weed control for 

shortleaf pine. In: Brissette, J.C.; Barnett, J.P. eds. 

Proceedings of the shortleaf pine regeneration 

workshop; 1991 October 29-31; Little Rock, AR. 

Gen. Tech. Report SO-90. New Orleans, LA; U.S. 

Department of Agriculture, Forest Service, Southern 

Forest Experiment Station: 77-100.

Yeiser, J.L.; Barnett, J.P. 1991. Growth and physiological 

response of four shortleaf pine families to herbicidal 

control of herbaceous competition. Southern Journal 

Applied Forestry. 15: 199-204.
112

UNDERPLANTING SHORTLEAF PINE IN THE MISSOURI OZARKS

Jason Jensen, Cliff Smith, Mark Johanson and David Gwaze1

ABSTRACT.—A study was established on Clearwater Conservation Area in the Missouri 

Ozarks in which shortleaf pine (Pinus echinata Mill.) seedlings were underplanted in mature 

mixed oak and oak/pine stands. Overstory trees were harvested a few months after planting, 

leaving different levels of residual overstory stocking. The different overstory treatments 

included 1) uneven-aged management with group openings; 2) clearcut; 3) shelterwood 

treatment with overstory reduction to B-level stocking; and 4) shelterwood treatment with 

overstory reduction to C-level stocking. Seven years after treatment application, clearcut 

stands had the best stocking and growth of planted shortleaf pine seedlings. The clearcut 

stands also had the highest number of free-to-grow seedlings. The higher the retained 

overstory stocking, the lower the number of free-to-grow shortleaf pine seedlings, and the 

lower the stocking and growth of underplanted shortleaf pine seedlings. Group openings 

established in uneven-aged management treatments appear to work, but the results suggest 

that they should be much larger to effectively regenerate pine. Growth of natural advance 

reproduction while in the understory, and released after clear cut harvesting was similar to 

growth of underplanted shortleaf pine seedlings and released after clearcut harvest, seven 

years after planting. This suggests that underplanting was effective in allowing planted pine 

seedlings time to become established and, therefore, capable of responding once released. 

Findings of this study suggest that clearcutting is the best method of regenerating pine, and 

that the higher the stocking rate of the residual overstory, the poorer the growth and stocking 

of the underplanted seedlings. The results also suggest that retaining the overstory for 7 years 

adversely affects stocking and growth of shortleaf pine seedlings and, thus, early release of 

underplanted seedlings is likely to result in a greater increase in stocking and growth.

1

Resource Forester (JJ), Missouri Department of Conservation, 

RR 4 Box 1002, Piedmont, MO 63957; Resource Forester (CS), 

Missouri Department of Conservation, Ellington, MO 63638; Private 

Lands Conservationist (MJ), Missouri Department of Conservation, 

PO Box 248, Sullivan, MO 63080; Resource Scientist (DG), Missouri 

Department of Conservation, 1110 S. College Avenue, Columbia, 

MO 65201.DG is corresponding author: to contact call (573)882-

9909 ext. 3320 or email at David.Gwaze@mdc.mo.gov

INTRODUCTION

Shortleaf pine is an important source of food and habitat 

for many birds and mammals and it produces high quality 

sawtimber on dry, nutrient-poor sites (Lawson 1990). 

Shortleaf pine forests in Missouri have declined from 

6.6 million acres to 397,100 acres since Euro-American 

settlement (Essex and Spencer 1976) The recent oak decline 

has underlined the importance of maintaining the shortleaf 

pine component in the pine-hardwood forests of Missouri 

because loss of oaks is greatest on sites that once had greater 

shortleaf pine stocking, and pine is well adapted to these 

sites for which they are considered a desirable species.

Currently, there is considerable interest in restoring 

shortleaf pine into areas where it has been lost due to past 

excessive logging, fi re suppression, annual burning by 

farmers, highgrading, conversion to range and overgrazing. 

Underplanting is a potentially viable silvicultural option 

for restoring shortleaf pine. Underplanting is useful to 

establish advance reproduction where natural reproduction 

of shortleaf pine is lacking. Conceptually, underplanting 

will result in vigorous root systems that will provide the 

growth potential for seedlings when the mature trees are 

removed provided there is adequate light for net positive 

biomass production (Johnson 1993). Underplanting allows 

the control of the potential grow surge of competing 

hardwoods and allows removal of the overstory when the 

pine is established. Herbicide release may not be needed for 

underplanted seedlings. It is also easier, and hence cheaper, 

to hand plant before harvest because of lack of physical 

barriers at planting. Success of underplanting pine is not 

well known, and could be limited by the fact that shortleaf 

pine requires abundant light for rapid growth (Lawson 

1990). However, Becton (1936) reported that shortleaf pine 

seedlings can become established under a dense canopy and 

persist for several years before dying, suggesting that newly 

established pine seedlings are moderately shade tolerant but 

become more shade intolerant with age. 

The objectives of the study were to 1) compare seven-year 

stocking and growth of shortleaf pine seedlings planted 

underneath various overstory densities; and 2) evaluate 

infl uence of hardwood competition on growth and stocking 

of underplanted shortleaf pine seedlings.
113

MATERIALS AND METHODS

Site Description

The study was located in compartment 7 on the Clearwater 

Conservation Area of the Missouri Department of 

Conservation. The Clearwater Conservation Area (CCA) 

is located in the Reynolds and Shannon Counties located 

in southeast Missouri. The study site is located completely 

within the Current River and Black River oak-pine 

woodland/forest hills Land Type Association (Nigh and 

Schroeder 2002). These land types are characterized by hilly 

landscapes with narrow ridges, narrow valleys and steep 

slopes with 150 to 250 feet of local relief. The ridges and 

upper slopes are formed from the Roubidoux Formation 

whereas the lower hillslopes and valleys cut into the 

Gasconade Formation. Historically, this area was dominated 

by shortleaf pine and shortleaf pine-oak woodland 

complexes.

The compartment was managed to favor pine in the late 

1990s. March 23 through March 29, 1998, 234.6 acres were 

planted with 97,741 shortleaf pine 1-0 bare-root seedlings. 

In May of 1998 the Conservation Commission approved 

the sale of 1,085,391 board feet of mixed hardwood saw 

timber from this compartment. The forester administering 

the sale used different management prescriptions to monitor 

pine seedling response to increasing overstory density 

and to determine the optimal overstory density for pine 

regeneration development. Overstory manipulations per 

stand were as follows: clearcut, unevenaged management 

with group openings, shelterwood treatment with overstory 

reduction to B-level stocking and shelterwood treatment 

with overstory reduction to C-level stocking. 

Sampling Procedure

In November 2005, we assessed these stands to learn more 

about the successes and failures of the artifi cial regeneration 

techniques. We surveyed stands each with the following 

treatments:

1) Clearcut and planted with 1-0 shortleaf pine seedlings 

at 12 x 12 ft (CC). 

2) Clearcut and not planted (CCN). 

3) Thinned using uneven aged management guidelines 

(UAM) (see Missouri Department of Conservation 

Guidelines 1986) and planted with 1-0 shortleaf pine 

seedlings at 12 x 12 ft. UAM guidelines include 

group openings.

4) Thinned to B-level stocking (Gingrich 1967) and 

planted with 1-0 shortleaf pine seedlings at 12 x 12 ft 

(B-level). 

5) Thinned to C-level stocking (Gingrich 1967) and 

planted with 1-0 shortleaf pine seedlings at 12 x 12 ft 

(C-level).

The goal was to retain a residual basal area of approximately 

70 ft2

/acre for B-level and UAM treatments, and 55 ft2/acre 

for C-level treatments. Group openings were one tree height 

(70 feet) in diameter. In the clearcut stands, all trees were 

cut except shortleaf pine trees.

In each stand we established six plots along one or more 

transects. Each transect followed the slope. Each plot 

was 60 ft x 40 ft and was meant to include 20 planted 

shortleaf pine seedlings. The stocking and height of each 

planted shortleaf pine seedling was assessed. Competition 

was assessed several ways. First, overstory basal area 

was measured by a prism count at the center of each plot. 

Second, number of hardwoods midstory species were 

counted within a 1/100th acre plot located within the center 

of each plot. Third, competition was assessed by measuring 

free-to-grow status of pine seedlings. Pine seedlings were 

assessed as being overtopped by hardwood competition or 

free-to-grow. Vegetation was considered competing with 

shortleaf pine seedlings if a leaf or branch of competing 

vegetation covered the pine’s terminal leader or was close 

to the terminal leader; otherwise the shortleaf pine seedlings 

were judged as free-to-grow. 

Statistical Analyses

Plot means were used for all analyses. Using the PROC 

GLM procedure in SAS Version 9.1 (SAS Institute Inc., 

Cary, NC), one-way analyses of variance (ANOVAs) were 

used to test for signifi cant differences among treatments for 

growth and competition. All analyses were carried out at 

the P ≤ 0.05 probability level. Where signifi cant differences 

were detected among treatments, Duncan’s Multiple Range 

Test was used to compare means.

RESULTS

Stocking of Shortleaf Pine Seedlings

After seven growing seasons, stocking of planted shortleaf 

pine was highest in the clearcut treatment and least in the 

unevenaged management treatment (Fig. 1). Stocking of 

shortleaf pine seedlings was estimated to be 12 percent 

in the UAM, 28 percent in the C-level, 52 percent in the 

B-level and 63 percent in the clearcut stand. The few 

trees observed in the UAM stand were in group openings, 

particularly in the center of the opening. The unplanted 

clearcut stand had a signifi cantly higher stocking of 

shortleaf pine seedlings than planted stands with high 

residual overstory densities (UAM, B-level and Clevel). Stocking of shortleaf pine seedlings did not differ 

signifi cantly in unplanted (CCN) and planted clearcut (CC) 

treatments. The unplanted clearcut stand was not planted 

due to adequate advanced pine regeneration. 

Growth of Shortleaf Pine Seedlings

Height of planted shortleaf pine seedlings was best in the 

clearcut treatment (Fig. 2). Height of planted shortleaf 

pine seedlings in clearcuts was more than twice the height 
114

of those in the other treatments. Group openings made a 

difference in the UAM because the tallest seedlings were 

found in the center of the group openings. These seedlings 

were as tall as those in the clearcut stand. In clearcuts, 

planted and naturally regenerated shortleaf pine seedlings 

were not signifi cantly different in height.

Competition

Overstory competition consisted of hardwoods and mature 

shortleaf pine trees retained as seed trees. As expected, the 

overstory competition was lowest in the clearcut stands 

(Fig. 3) and consisted of few scattered shortleaf pine seed 

trees. Midstory competition was inversely related to the 

amount of residual overstory trees, being highest in the 

clearcut treatments and least in the treatments with higher 

amount of residual overstory (Fig. 4). The high number of 

midstory trees in the UAM compared to the B and C-level 

stocking was due to high density of midstory trees in group 

openings. 

Many of the shortleaf pine trees in clearcuts were judged 

as free-to-grow while the majority of the trees in the other 

treatments were suppressed (Fig. 5). While over 65 percent 

of the planted shortleaf pine seedlings were judged as 

free-to-grow in the clearcut stands, less than 25 percent 

were judged as free-to-grow in stands with a high residual 

overstory density. Shortleaf pine seedlings in the clearcuts 

were mainly overtopped by midstory hardwood sprouts, 

while those in the other treatments were overtopped by 

overstory hardwoods. 

231

42

102

187

203

0

50

100

150

200

250

CC UAM C-level B-level CCN

Seedlings/ac

Figure 1.—Stocking of underplanted shortleaf pine 

seedlings 7 years after establishment. CC = clearcut and 

planting; UAM = uneven-aged management and plant; Clevel = thin to C-level stocking and plant, B-level = thin to 

B-level stocking and plant; CCN = clearcut and no planting. 

Numbers on bars are treatment means. Different letters 

indicate signifi cant differences among treatments based on 

the Duncan’s Multiple Range Test. Same or shared letters 

indicate no signifi cant difference at α = 0.05 level.

a

c

bc

ab

ab

8.81

4

2.57

1.46

7.24

0

1

2

3

4

5

6

7

8

9

10

CC UAM C-level B-level CCN

HT (ft)

Figure 2.—Height growth of shortleaf pine trees 7 years 

after establishment. CC = clearcut and planting; UAM = 

uneven-aged management and plant; C-level = thin to 

C-level stocking and plant, B-level = thin to B-level stocking 

and plant; CCN = clearcut and no planting. Numbers on bars 

are treatment means. Different letters indicate signifi cant 

differences among treatments based on the Duncan’s 

Multiple Range Test. Same or shared letters indicate no 

signifi cant difference at α = 0.05 level.

a

b

bc

c

a

43.3

78.3 75

86.7

31.7

0

20

40

60

80

100

CC UAM C-level B-level CCN

Basal area (ft 2

)

Figure 3.—Basal area of overstory trees 7 years after 

establishment. CC = clearcut and planting; UAM = unevenaged management and plant; C-level = thin to C-level 

stocking and plant, B-level = thin to B-level stocking and 

plant; CCN = clearcut and no planting. Numbers on bars 

are treatment means. Different letters indicate signifi cant 

differences among treatments based on the Duncan’s 

Multiple Range Test. Same or shared letters indicate no 

signifi cant difference at α = 0.05 level.

b

a a

a

b
115

65.3

20

23.5

8.1

42.9

0

20

40

60

80

CC UAM C-level B-level CCN

Free-to-grow seedlings (%)

Figure 5.—Free-to-grow shortleaf pine seedlings 7 years 

after establishment. CC = clearcut and planting; UAM = 

uneven-aged management and plant; C-level = thin to 

C-level stocking and plant, B-level = thin to B-level stocking 

and plant; CCN = clearcut and no planting. Numbers on bars 

are treatment means.

6250

3400

1700

530

4750

0

2000

4000

6000

8000

CC UAM C-level B-level CCN

No. of midstory hardwoods/ac

Figure 4.—Density of midstory hardwoods 7 years after 

establishment. CC = clearcut and planting; UAM = unevenaged management and plant; C-level = thin to C-level 

stocking and plant, B-level = thin to B-level stocking and 

plant; CCN = clearcut and no planting. Numbers on bars 

are treatment means. Different letters indicate signifi cant 

differences among treatments based on the Duncan’s 

Multiple Range Test. Same or shared letters indicate no 

signifi cant difference at α = 0.05 level.

a

bc

cd

d

ab

DISCUSSION AND CONCLUSION

Results from our study indicate that shortleaf pine seedlings 

in the clearcuts had higher stocking than those in other 

treatments. Brinkman and Liming (1961) underplanted 

1-0 shortleaf pine seedlings in 40-year-old oak-pine forest 

on the Mark Twain National Forest and removed the 

overstory leaving different residual densities (0, 27, 53 

and 79 ft2/acre). When they removed the overstory in the 

year of planting they found no signifi cant differences in 

survival 11 years after planting. However, they found that 

survival of underplanted shortleaf pine was drastically 

reduced from 74 percent to 10 percent when the overstory 

release by clearcutting was delayed one year after planting. 

According to Liming (1946), complete release of overstory 

by clearcutting is an unsatisfactory method of releasing 

shortleaf pine one or more growing seasons after planting. 

Results from our study further suggest that shortleaf pine 

seedlings in clearcuts developed more rapidly than those 

planted in other treatments. This is expected because there 

was less shading in clearcuts. Our results are consistent 

with reports by Brinkman and Liming (1961) and Guldin 

and Heath (2001) who reported that growth of underplanted 

shortleaf pine seedlings in clearcuts was superior to those 

where partial overstory was retained.

Because midstory competition was highest and growth 

was best in the clearcut treatments our study suggests that 

overstory competition is the main factor affecting stocking 

and growth of underplanted seedlings. Overstory vegetation 

has a substantial infl uence on underplanted seedlings by 

reducing light intensity, intercepting a signifi cant proportion 

of precipitation and increasing competition for soil moisture 

and nutrients by roots (Anderson et al. 1969). Underplanted 

shortleaf pine seedling growth was found to be inversely 

related to increasing overstory retention after seven growing 

seasons (Guldin and Heath 2001).

Our study and previous studies indicate that clearcutting 

is the best for regenerating shortleaf pine. Brinkman and 

Liming (1961) further observed that delaying complete 

overstory removal by one year after planting reduced 

survival of planted shortleaf pine substantially. Liming 

(1946) recommended spring planting of pine and 

clearcutting the overstory the following dormant season. 

Certainly, early removal of the overstory appears to match 

the silvics of the species because shortleaf pine is generally 

considered a shade-intolerant species (Lawson 1990). Group 

openings (small clearcuts) established in uneven-aged 

management treatments appear to work, but our results 

suggest that they should be much larger to allow successful 

establishment and development of planted shortleaf pine 

seedlings for more than 7 years. Underplanted seedlings 

in the clearcut treatment had a similar growth response to 

advanced regeneration in unplanted clearcut treatment, 7 

years after planting. This suggests that underplanting was 

effective in allowing planted pine seedlings time to become 

established and, therefore, capable of responding once 

released. 
116

Possible future studies utilizing existing underplanted 

stands include determining the response of underplanted 

shortleaf pine seedlings to canopy removal and determining 

the more effective recruitment method for planted shortleaf 

pine seedlings in clearcuts. The fi rst study should provide 

information about whether the underplanted seedlings in 

partial overstory retention treatments, particularly those 

in B-level and C-level treatments, will respond to release 

after seven or more years after planting. Some studies in 

Missouri carried out from the 1930s to 1960s indicated 

that underplanted shortleaf pine seedlings respond well 

to release even at a late stage such as 30 years (Brinkman 

and Smith 1968). The new studies will provide up-to-date 

information to supplement or confi rm the historical studies. 

The second study may determine if there are any differences 

in stocking and growth of shortleaf pine trees in clearcuts 

released using different methods—mechanical, chemicals 

and fi re—providing important information to resource 

managers on which method is best at recruiting shortleaf 

pine trees.

LITERATURE CITED

Anderson, R.C.; Loucks, O.L.; Swain, A.M. 1969.

Herbaceous response to canopy cover, light intensity, 

and throughfall precipitation in coniferous forests. 

Ecology. 50: 255-263.

Becton, W.R. 1936. Effects of varying densities of 

hardwood cover on growth and survival of shortleaf 

pine reproduction. Journal of Forestry. 34: 160-164.

Brinkman, K.A.; Liming, F.G. 1961. Oak and pine 

reproduction to over head release. Journal of Forestry. 

59: 341-346.

Brinkman, K.A.; Smith, R.C. 1968. Managing shortleaf pine 

in Missouri. Stn. Bull. 875. Columbia, MO: University 

of Missouri Agricultural Experiment Station. 33 p. 

Gingrich, S.F. 1967. Measuring and evaluating stand density 

in upland hardwood forests in Central States. Forest 

Science. 13: 38-53.

Guldin, J.M.; Heath, G. 2001. Underplanting shortleaf 

pine seedlings beneath a residual hardwood stand in 

the Ouachita Mountains: Results after seven growing 

seasons. Res. Note. SRS-09. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, Southern 

Research Station. 8 p.

Johnson, P. 1993. Sources of oak reproduction. In: Loftis, 

D.L.; McGee, C.E., eds. Proceedings, oak regeneration: 

serious problems, practical recommendations; 1992 

September 8-10; Knoxville, TN. Gen. Tech. Rep. SE84. Asheville, NC: U.S. Department of Agriculture, 

Forest Service, Southeastern Forest Experiment Station: 

112-131.

Law, J.R.; Melick, R.; Studyvin, C.; Steinman, J.R. 2004. 

Oak decline in Missouri: History revisited. In: Spetich, 

M.A., ed. Upland oak ecology symposium: history, 

current conditions, and sustainability. Gen. Tech. 

Rep. SRS-73. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research Station: 

257-258. 

Lawson, E.R. 1990. Pinus echinata Mill. shortleaf pine. 

In: Burns, R.M.; Honkala, B.H., tech. coords. Silvics 

of North America. Volume 1, Conifers. Agric. Hndbk. 

654. Washington, DC: U.S. Department of Agriculture, 

Forest Service. 

Liming, F.G. 1945. Natural regeneration of shortleaf pine 

in the Missouri Ozarks. Journal of Forestry. 43(5): 

339-345. 

Liming, F.G. 1946. Response of planted shortleaf pine to 

overhead release. Tech. Pap. No. 105. Columbus, OH: 

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

State Experiment Station. 20 p.

Missouri Department of Conservation. 1986. Forest land 

management guidelines. Jefferson City, MO: Missouri 

Department of Conservation. 86 p.

Nigh, T.A.; Schroeder, W. A. 2002. Atlas of Missouri 

ecoregions. Jefferson City, MO: Missouri Department 

of Conservation. 212 p.
117

UNDERPLANTING SHORTLEAF PINE 

AT COLDWATER CONSERVATION AREA IN MISSOURI

Jason Jensen and David Gwaze1

1

Resource Forester (JJ), Missouri Department of Conservation, 

RR 4 Box 1002, Piedmont, MO 63957; Resource Scientist (DG), 

Missouri Department of Conservation, 1110 S. College Avenue, 

Columbia, MO 65201; JJ is corresponding author: to contact call 

(573)223-4525 or email at Jason.Jensen@mdc.mo.gov

EXTENDED ABSTRACT

Restoring shortleaf pine throughout its native range in the 

Ozark Highlands is a high priority in Missouri. Restoring 

shortleaf pine on former pine and oak-pine sites is a longterm strategy for mitigating chronic oak decline (Law et al. 

2004). Underplanting or preharvest planting is one method 

that has potential for restoring shortleaf pine. Conceptually, 

underplanting will result in vigorous root systems that will 

provide the growth potential for seedlings when the mature 

trees are removed (Johnson 1993). Underplanting allows 

the control of the potential growth surge of competing 

hardwoods and allows removal of the overstory when the 

pine is established. It is also easier, and hence cheaper, 

to hand plant before harvest because of lack of physical 

barriers at planting. One of the potential advantages of 

underplanting is that release herbicide may not be needed. 

Success of underplanting is not well known, and could be 

limited by shortleaf pine’s requirement for abundant light 

for rapid growth. The objectives of the study were (1) to 

compare survival and growth of shortleaf pine seedlings 

planted underneath various overstory densities; (2) to 

compare survival and growth of shortleaf pine seedlings 

planted before and after clearcutting; and (3) to evaluate the 

infl uence of hardwood competition on growth and survival 

of planted shortleaf pine. 

The study was located on the Coldwater Conservation 

Area of the Missouri Department of Conservation and 

on the adjacent property owned by the Williams Family 

Limited Partnership. The three treatments applied after 

underplanting shortleaf pine seedlings underneath a mature 

overstory in March 2002 were clearcut, uneven-aged with 

group selection (UAM), and shelterwood. The fourth 

treatment consisted of planting shortleaf pine seedlings in 

March 2002 after clearcut. In April 2006, we assessed the 

study. In each treatment, we established six plots along one 

or more transects. Each plot was 60 ft x 40 ft and was meant 

to include 20 planted shortleaf pine seedlings. Survival and 

height of each planted shortleaf pine seedling was assessed. 

Four years after treatments, shortleaf pine seedlings 

planted in clearcuts had moderate survival and the best 

growth (Figs. 1 and 2). Seedlings planted before and after 

clearcutting were not signifi cantly different in both survival 

and growth. Seedlings underplanted in the shelterwood 

treatment had the poorest survival and growth. Seedlings 

planted in shelterwood treatment were 84 percent shorter 

than those planted in clearcuts. Seedlings underplanted 

in the UAM treatment had the best survival but had poor 

growth. Within the UAM treatment, group openings 

behaved like small clearcuts. Height of seedlings in group 

openings (4.43 ft) was as good as that in clearcuts, and 

height in single tree selection (2.27 ft) was as low as that 

in shelterwood treatment. The basal area was least in the 

clearcut treatments (3 to 8 ft2

/ac), and highest in the UAM 

(23 ft2/ac) and the shelterwood treatment (28 ft2/ac). 

Results from this study suggest that clearcutting is the best 

method to regenerate shortleaf pine, and planting before 

or after clearcutting does not affect survival or growth 

of planted shortleaf pine seedlings. However, planting 

after harvest is more diffi cult than planting before harvest 

because of planting in and around logging debris. Thus, 

planting before harvest and clearcutting the overstory in the 

same year the shortleaf seedlings are planted appear to be a 

good regeneration strategy for shortleaf pine.

LITERATURE CITED

Law, J.R.; Melick, R.; Studyvin, C.; Steinman, J.R. 2004. 

Oak decline in Missouri: history revisited. In: Spetich, 

M.A., ed. 2004. Upland oak ecology symposium: 

history, current conditions, and sustainability. Gen. 

Tech. Rep. SRS-73. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research Station: 

257-258. 

Johnson, P. 1993. Sources of oak reproduction. In: Loftis, 

D.L.; McGee, C.E., eds. Proceedings, oak regeneration: 

serious problems, practical recommendations; 1992 

Sept. 8-10; Knoxville, TN. Gen. Tech. Rep. SE-84. 

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

Service, Southeastern Forest Experiment Station: 

112-131.
118

Treatment

CCP PCC SW UAM

Pine seedlings per acre

0

50

100

150

200

250

300

350

P < 0.0001

Figure 1.—Stocking of planted shortleaf pine seedlings 

5 years after establishment. CCP = clearcut and plant; 

PCC = plant and clearcut; SW = shelterwood; UAM = 

uneven-aged management. Error bars are standard errors 

of the mean.

Treatment

CCP PCC SW UAM

Total height (ft)

0

1

2

3

4

5

6 P < 0.0014

Figure 2.—Total height of shortleaf pine trees 5 years after 

establishment. CCP = clearcut and plant; PCC = plant 

and clearcut; SW = shelterwood; UAM = uneven-aged 

management. Error bars are standard errors of the mean.
119

DIRECT SEEDING OF SHORTLEAF PINE

Corinne S. Mann and David Gwaze1

1

Resource Scientist-Intern (CSM) and Resource Scientist (DPG), 

Missouri Department of Conservation, 1110 S. College Avenue, 

Columbia, MO 65201. DPG is corresponding author: to contact call 

(573)882-9909 ext. 3320 or email at David.Gwaze@mdc.mo.gov

EXTENDED ABSTRACT

Direct seeding is a potentially viable method for 

regenerating shortleaf pine, but it has not been used 

extensively. In Missouri, an estimated 10,000 acres have 

been direct-seeded with shortleaf pine; half of which are 

at Mark Twain National Forest. Direct seeding offers a 

fl exible and effi cient alternative to planting as a way to 

restore shortleaf pine in the Ozarks. The poster reviews the 

potential use of direct seeding for shortleaf pine restoration 

in Missouri.

Direct seeding affords many advantages, including: 

1) initial costs are reduced; 2) natural root systems are 

developed on site; 3) transplant shock is avoided; 4) seeding 

is easier on sites with limited access, diffi cult terrain, or 

rocky, shallow soils; 5) it can be done during different times 

of the year (unstratifi ed seed is sown in autumn; stratifi ed 

seed is sown in late winter or early spring); and 6) it can be 

used to supplement natural regeneration in an area where 

few or no seed trees exist. Potential limitations of direct 

seeding include: 1) a large amount of seed is required; 

2) low seedling survival rates; 3) reduced control over 

spacing of trees; 4) costly pre-commercial thinning; 

5) potential for seed loss due to predation and rain washout; 

and 6) severe competition with other vegetation. Early 

growth of seeded seedlings is lower than that of planted 

seedlings (Fig. 1, Brunk 1977).

Proper seedbed conditions are critical for germination and 

survival of direct-seeded shortleaf pine. Shortleaf pine direct 

seeding is most successful on exposed mineral soils with 

suffi cient light. Fire or mechanical disturbances are effective 

site-preparation methods. Seedlings were prohibited from 

establishing on litter depth exceeding 3 inches (Fig. 2, 

Grano 1949) and at least three times as many seedlings 

emerged on burned sites as on unburned sites (Fig. 3, Boggs 

and Wittwer 1993).

The following is recommended when sowing shortleaf pine 

seed: 1) treat seeds with repellents to prevent predation; 

2) sow half a pound of shortleaf pine seed per acre; 3) mix 

pine seed with wheat seed (40 lbs per ac) to spread the pine 

seed evenly; 4) sow seed in spots or rows; or broadcast 

mechanically, by hand, or aerially. 

0

20

40

60

80

100

Direct2 yrsPlanted2 yrsDirect5 yrsPlanted5 yrs

Height (inches)

Figure 1.—Comparison of direct seeded and planted 

seedlings at Indian Trail Conservation Area, Dent County 

(Brunk 1977).

0

5

10

15

20

25

30

01234

Litter depth (inches)

Seedlings per milacre

plot

Figure 2.—Relationship between average litter depth and 

establishment of pine seedlings (adapted from Grano 1949).

0

1

2

3

4

5

January March

Sowing date

No. of seedlings (%)

Hot burn

Medium burn

No burn

Figure 3.—Number of established seedlings as a 

percentage of seeds sown (Boggs and Wittwer 1993).
120

The fi rst year is the most critical for establishment and 

survival; mortality after the fi rst year is low. Establishment 

is best if a small amount of overstory shade is present to 

prevent desiccation. However, the species becomes less 

shade tolerant with age and benefi ts from a reduction of 

canopy cover and release of competition with understory 

vegetation once it is established. Inventories are 

recommended during summer and again at the end of the 

growing season in the fi rst year: minimum acceptable is 

1,400 seedlings per acre at the end of the fi rst growing 

season.

Direct seeding is a simple, fast, economical, and fl exible 

method that can supplement natural shortleaf pine 

reproduction or regeneration. It has the potential to make a 

signifi cant contribution to shortleaf pine restoration efforts 

in the Missouri Ozarks. 

LITERATURE CITED

Boggs, J.A.; Wittwer, R.F. 1993. Emergence and 

establishment of shortleaf pine seeds under various 

seedbed conditions. Southern Journal of Applied 

Forestry. 17(1): 44-48.

Brunk, E.L. 1977. Summary of fi fth-year results for 

shortleaf pine provenance tests. Study Rep. 8. Tree 

Improvement Project. Jefferson City, MO: Missouri 

Department of Conservation. 7 p.

Grano, C.X. 1949. Is litter a barrier to the initial 

establishment of shortleaf and loblolly pine 

reproduction? Journal of Forestry. 47: 544-548.
121

WHAT FIRE FREQUENCY IS APPROPRIATE 

FOR SHORTLEAF PINE REGENERATION AND SURVIVAL?

Michael C. Stambaugh, Richard P. Guyette, and Daniel C. Dey1

ABSTRACT.—Shortleaf pine community restoration requires an answer to the question, “What 

fi re frequency is appropriate for shortleaf pine regeneration and survival?” The answer to this 

question is one of the most critical to successful restoration through fi re management. We 

used three sources of information from Missouri to determine appropriate burning frequencies: 

a 400-yr historic shortleaf pine growth and fi re-scar database, fi re effects data from 

prescribed burning sites, and a vegetation dynamics prediction model that is widely used for 

characterizing fi re regimes. The historic shortleaf pine and fi re scar database provides actual 

past scenarios of regeneration dates, growth, survival, and associated fi re events. Shortleaf 

pine regeneration established most commonly during the 4 years following fi re events and 

generally decreased in abundance with years since fi re. Surviving seedlings were those that 

were not fi re scarred the year following establishment, and the mean number of years to a 

subsequent fi re was about 7 years. Fire effects data from prescribed burn sites revealed that 

both hardwood and pine regeneration showed substantially increased mortality after four 

consecutive dormant season burns, but oak and hickory species were more likely to survive 

frequent fi re. Mortality of advance regeneration was generally low in all hardwood species 

after one burn, while shortleaf pine seedlings had high mortality rates. The model showed 8 

to 15 yr intervals are likely best for balancing both continual regeneration and recruitment. 

Model prediction runs for 500 years showed a signifi cantly decreased pine component in the 

absence of burning. Conversely, long-term frequent burning (1- to 3-yr intervals) resulted in 

abundant regeneration, but poor survival and ultimately decreased abundance in mid- and 

late-successional forests. In summary, all three sources support the effi cacy of frequent 

burning (1 to 4 yrs) in promoting pine regeneration, but survival and continued recruitment 

require longer fi re intervals (8 to 15 yrs). Fire management prescriptions that incorporate both 

frequent burning and longer intervals will likely provide for the most long-term regeneration and 

recruitment success.

1

Senior Research Specialist (MCS), Department of Forestry, 

University of Missouri-Columbia, Columbia, MO 65211; Research 

Associate Professor (RPG), Department of Forestry, University of 

Missouri-Columbia, Columbia, MO 65211; and Research Forester 

(DCD), U.S. Forest Service, Northern Research Station, Columbia, 

MO 65211. MCS is corresponding author: to contact, call (573)-882-

8841 or email at stambaughm@missouri.edu

INTRODUCTION

It is widely recognized that fi re is critical to shortleaf 

pine forest ecosystems (Cooper 1989, Bukenhofer and 

others 1994, Masters and others 1996, Stanturf and others 

2002, Rimer 2003, USDA 2003). However, shortleaf pine 

restoration through fi re management begs the answers to 

questions such as “What fi re frequency is appropriate for 

shortleaf pine regeneration and survival?” Much of the 

information about shortleaf pine and fi re comes from fi eld 

trials and lies with experienced individuals while relatively 

little is published about experimental fi ndings. Because of 

the dynamic conditions of fi re events (due to fuels, weather 

and climate, vegetation, topography, burning technique, 

etc.), it is diffi cult to relate single experimental results to the 

management of large and different forested landscapes.

The historic role of fi re within shortleaf pine communities 

of the Ozark Highlands has been well established and 

described (Guyette and others 2002, Guyette and others 

2006) (Fig. 1). The pre-Euro-American dominance of 

shortleaf pine in the region was negatively related to 

historic mean fi re intervals (Batek and others 1999). 

Wildfi res likely maintained many of the presettlement 

shortleaf pine communities and, though at times severe, 

were predominantly non-stand-replacing surface fi res 

resulting from anthropogenic ignitions. Mixed severity fi res 

resulting in small stand-replacement events likely occurred 

within the region about every 20 years (Guyette and others 

2006). Today, wildfi res typically consist of small-scale, low 

severity surface fi res (Westin 1992, Stambaugh and others in 

press) that are rarely stand-replacing events.

METHODS

In an attempt to provide regionally derived information 

on fi re regime and shortleaf pine dynamics, we chose 

to summarize results of fi re events and shortleaf pine 

regeneration and survival from many locations and time 
122

periods within the natural range of shortleaf pine in the 

Ozark Highlands of Missouri and Arkansas. We used three 

approaches to determine appropriate burning frequencies for 

promoting shortleaf pine regeneration and recruitment. The 

approaches were: analysis using a 400-yr historic shortleaf 

pine growth and fi re scar database (Stambaugh and Guyette 

2004), a summary of fi re effects data from prescribed 

burning sites (Dey and Hartman 2005), and model 

simulations using the Vegetation Dynamics Development 

Tool (VDDT) (Essa Technologies Ltd. 2005).

Historic Shortleaf Pine Growth 

and Fire Scar Database

This database consists of approximately 600 cross sections 

cut from the base of shortleaf pine remnant trees, live trees, 

and existing stumps that were collected from throughout the 

Ozark Highlands region during the past 20 years (Guyette 

1994, Guyette and others 2002, Guyette and Spetich 2003) 

(Fig. 1). This database represents trees that survived fi re 

events and does not contain those that were killed and 

have since decomposed. Tree-ring data from cross sections 

span the past four centuries and the database was queried 

for those trees that had both pith dates (stem ages) and fi re 

event dates. The query resulted in 96 trees with pith dates 

ranging from 1585 to 1896 (Fig. 2). Of these, 64 trees had 

information about the number of years since fi re as derived 

from fi re history studies at their respective sites. Ninetyone trees contained information about the number of years 

from the pith to the fi rst fi re scar on that tree and 95 had 

information about the number of years from the pith to the 

fi rst fi re event that occurred within the vicinity (less than 1 

km2

). It is important to note that pith dates refl ect the fi rst 

year of growth of the stem and that it is not known whether 

stems initiated from a seedling or a sprout.

Figure 1.—Locations of shortleaf pine fi re history sites 

(white circles), the Chilton Creek Preserve (black star), the 

boundary Ozark Highlands ecoregion (white line) (Bailey 

1998), and the approximate range of shortleaf pine (stippled 

area). Fire history sites are where shortleaf pine specimens 

used in the growth and fi re scar analysis were collected. The 

Chilton Creek Preserve is the location from which fi re effects 

data were summarized.

Figure 2.—Bar graph of the number of shortleaf pines regenerating during the years following fi re 

events. Data were generated from a historic shortleaf pine specimen database (see methods). 

Years of regeneration of these trees are shown as pith dates (upper right of graph).

Fire Effects

Fire effects data for shortleaf pine were summarized from 

the Chilton Creek Preserve, a 2289 ha site located along the 

Current River in Shannon and Carter Counties, Missouri. 

The preserve has been divided into fi ve management units 

of approximately 200 ha each. All units were burned in 

the spring of 1998 and then burned during the dormant 
123

season on a randomly determined 1- to 4-yr return interval 

basis. One management unit (Kelly North) has been burned 

annually. Pre- and post-burn information is available for 

fuels and fi re behavior, and fi re effects information is 

available for herbaceous, seedling, and sapling vegetation 

layers (Sasseen 2003, Dey and Hartman 2005). Here, we 

summarize the fi re effects fi ndings of Dey and Hartman 

(2005) as they relate to the survival of shortleaf pine 

regeneration and compare their fi ndings to those generated 

from the historic shortleaf pine database and VDDT 

modeling approaches.

VDDT Model

VDDT is a model developed for examining the infl uence of 

various disturbance and management actions on vegetation 

development (Essa Technologies Ltd. 2005). The model is 

a state and transition model that was developed for use in 

the Landfi re project, a federally funded project producing 

consistent and comprehensive maps and data describing 

vegetation, wildland fuel, and fi re regimes across the 

United States (Rollins and others 2003). VDDT has a suite 

of reference models that have been developed for many 

different vegetation types, including oak-hickory-pine 

forests, based on information from published literature, 

expert input, and peer review. We used a fi ve-box model 

developed for oak-pine forests to explore the effects of 

different fi re frequencies on the regeneration and survival 

of shortleaf pine communities, particularly over extended 

time periods (e.g., 500+ years). Details of this model can be 

found in Guyette and others (2004) and Shlisky and others 

(2005). In general, the model simulates the survivorship 

and transition of oak-hickory-pine forests as a result of 

fi re disturbances (and other disturbances if chosen) which 

can be changed by the user. The model contains fi ve 

forest seral states (Table 1). In subsequent model runs we 

decreased the fi re frequency to understand the effects of 

fi re on various forest states, particularly the maintenance 

of two states: an early seral mixed forest (i.e. regeneration) 

and late-seral forest with greater than 2 percent shortleaf 

pine (i.e., survivorship of shortleaf pine) (Table 1). Model 

simulations were generated using fi re frequencies of annual 

burning, 2-yr, 4-yr, 8-yr, 15-yr, and 40-yr fi re intervals, 

and no fi re disturbance. For each scenario the model was 

run for 500 timesteps using 10 simulations. Initial model 

conditions began with equal area (20 percent of landscape) 

represented by each seral stage. VDDT calculates the 

percentage of area occupied by each seral state, and model 

results were produced for the 100 and 500 timesteps. No 

model modifi cations were made other than fi re disturbance 

frequencies. 

RESULTS

Historic Shortleaf Pine Growth 

and Fire Scar Database

The mean number of years from a pith date to a fi re event 

was 6.8 years. The abundance of shortleaf pine regenerating 

fell sharply with time since fi re; the majority occurred 

within the fi rst 8 years from a fi re event (Fig. 2). Much of 

the regeneration that survived underwent another fi re within 

the fi rst 12 years of regenerating (Fig. 3). The mean number 

of years from regeneration to the fi rst fi re scar was 45.5 

years and the majority of trees survived at least one fi re in 

the fi rst 20 years of growth. No trees were represented as 

having survived a fi re injury during the fi rst year of growth. 

Fire Effects

First year burning effects resulted in shortleaf pine having 

the highest seedling and sapling layer percent mortality 

(38 percent) of any species recorded (see Table 3 in Dey 

and Hartman 2005). Despite high initial mortality, shortleaf 

pine had only 1 percent additional mortality in subsequent 

fi res, while all other species sustained higher mortality rates. 

Following 3+ burns (annual burning frequency), shortleaf 

pine showed the lowest percent total damage calculated as 

the sum of the percent mortality and percent shoot dieback. 

The probability of shortleaf pine seedlings and saplings 

(advance reproduction) in the understory of a mature oakpine forest surviving a spring surface fi re was signifi cantly 

related to initial stem size (i.e., basal diameter and height). 

Small-diameter shortleaf pine advance reproduction had the 

Table 1.—Forest developmental states of coarse (south central U.S.) and empirically-driven (Current River Hills, MO) oakhickory-pine VDDT models developed by Guyette and others (2004) and validated by Shlisky and others (2005). The effects of 

different fi re disturbance frequencies on the development and success of each seral state are shown in Figure 4.

Seral State Age range (yrs) Code

Early seral mixed forest 0-12 A

Mid-seral mixed forest; canopy cover >55% 13-70 B

Mid-seral mixed forest; canopy cover <55% 13-70 C

Late-seral forest; >55% canopy cover; <2% shortleaf pine >70 D

Late-seral forest; >55% canopy cover; >2% shortleaf pine >70 E
124

lowest survival probabilities compared to similarly sized 

hardwood seedlings. Shortleaf pines that were less than 

2 cm in basal diameter had less than 40 percent chance of 

surviving a single spring surface fi re. In contrast, pines that 

were greater than or equal to 10 cm in basal diameter had 

a 90 percent or greater probability of surviving burning. 

Large diameter (greater than 5-cm basal diameter) pines 

that survived one fi re had high probabilities of surviving 

repeated dormant-season surface fi res. Overall, repeated 

burning in the dormant season reduced the height of 

understory trees and favored oak reproduction. Fire effects 

data from Chilton Creek demonstrated that the success 

of fi re treatments may be better assessed after conducting 

multiple burns as high mortality may occur in the initial 

burn and not be representative of long-term repeated 

burning.

VDDT Model

Model simulations demonstrated that forest developmental 

states are highly sensitive to small changes in burning 

frequency. Simulations of annual burning allowed for the 

greatest proportion (nearly 60 percent) of the landscape to 

be in an early seral state (Fig. 4). The effect of decreasing 

the burning frequency from annual burning to 40-year fi re 

intervals was a transition in the amount and types of seral 

states occupying the landscape. For example, the percent of 

area in early seral states decreased dramatically (60 to 

4 percent) while mid-seral closed canopy developmental 

states slightly increased (Fig. 4). Forest developmental 

states that likely represent shortleaf pine success (i.e., 

classes C and E) showed different responses. Mid-seral open 

canopy states slightly decreased in percent area from 2-year 

to 40-year burning intervals. Percentage area of late-seral 

open canopy states with > 2 percent shortleaf pine (i.e., 

class E) increased from 2-yr to 8-yr burning intervals. The 

percent area of this late-seral state decreased as fi re intervals 

Figure 3.—Bar graph showing the historic shortleaf pine specimen trees and the number of years 

to the fi rst fi re they survived as documented by a scarring injury. Two types of fi res are shown: fi res 

that were recorded on that individual tree and fi res that scarred other trees in the vicinity (within 

about 1 km) of where the tree grew.

increased beyond 15 years. The “no fi re disturbance” 

scenario resulted in a dominance of the late-seral state with 

no shortleaf pine component on nearly 80 percent of the 

area at timestep 500 (Fig. 4). 

DISCUSSION

Shortleaf Pine Regeneration and Survival

In this study the regeneration success of shortleaf pine 

appeared to be related to time since fi re. Much of the 

regeneration summarized from the historic shortleaf pine 

database showed that regeneration following fi re occurred 

within the fi rst 10 to 15 years. This time period is likely 

related to many of the factors essential to regeneration 

establishment such as available light, nutrient release, 

and litter cover, as well as ability to resprout. In the 

Ozarks, litter and duff are important barriers to shortleaf 

regeneration (Grano 1949, Shelton and Wittwer 1992) and 

time since fi re and shortleaf pine regeneration are inversely 

related (Ferguson 1958). Stambaugh and others (2006) 

estimated litter in Ozark forests accumulates to a maximum 

equilibrium within about 12 years post-fi re. It is common for 

current Ozark oak-pine forests to have undergone decades 

of fi re exclusion resulting in maximum litter accumulation 

levels, the development of a substantial duff layer, and 

ultimately large scale preclusion of shortleaf pine seedling 

establishment. 

Although shortleaf pine regeneration showed a positive 

response to fi re events, shortleaf pine’s survival following 

regeneration appeared to necessitate recurring fi re (Fig. 3). 

The results suggest that following regeneration, immediate 

burning and repeated frequent burning (annual to 2-yr 

frequency) do not support shortleaf pine survivorship. 

Although shortleaf pine seedlings can resprout vigorously 

following topkill (Walker and Wiant 1966, Keeley and 
125

Figure 4.—Bar graphs of percent area of landscape (VDDT 

model simulated) that is comprised in fi ve forest seral states 

(coded A through E, Table 1). The percent area in each seral 

state is shown for seven different fi re frequency scenarios. 

Initial forest conditions (timestep 0) contain equal amounts of 

each seral state, and results are shown for 100 yr and 500 yr 

timesteps. Class codes are: A = Early seral mixed forest, 

B = Mid-seral mixed forest; canopy cover >55%, C = Midseral mixed forest; canopy cover <55%, D = Late-seral 

forest; >55% canopy cover; <2% shortleaf pine, E = Lateseral forest; >55% canopy cover; >2% shortleaf pine.

Zedler 1998), it is not known how many successive 

resprouting events can occur from the same root stock 

during a frequent burning regime; therefore, repeated 

frequent fi re may prohibit survival of seedlings. In a study 

that compared a remnant stand of shortleaf pine with the 

existing stand at the same site, Guyette and Dey (1997) 

concluded that 100 years of burning with a mean fi re return 

interval of 3.1 years contributed to the elimination and 

reduction of advanced pine regeneration. 

A recurring question is “what amount time of does it take 

for a pine to gain some degree of fi re resistance?” It appears 

from our analysis that this is within a range of 8 to 15 years, 

depending on stand and environmental conditions. Wade 

and others (2000) reported a range of 6 to 15 years for drier, 

nutrient poor sites and a 2- to 6-yr range on more fertile 

sites. Walker and Wiant (1966) showed comparable results 

based on tree size and Baker (1992) reported supporting 

results based on tree height. Respectively, they reported 

that shortleaf trees larger than about 2 to 10 cm diameter at 

breast height (DBH) and 4 to 5 m in height are somewhat 

resistant to surface fi res. The range in tree height and size 

likely varies based on fi re environment and behavior. 

Brinkman and Smith (1968) reported that “free growing” 

trees in Missouri within this fi re-resistant size class were 

about 7 years old. Similarly, shortleaf growing in different 

regions (e.g., Arkansas and Oklahoma Ozarks and Ouachita 

Mountains) may reach resistance earlier than more northerly 

populations because of increased growth rates. Denser 

overstory stockings that cause decreased pine growth would 

also increase the age to resistance. Suppressed understory 

trees may be particularly problematic as they may be 30 

years old or greater and still within a size range susceptible 

to fi re kill (Brinkman and Smith 1968, Stambaugh 2001). 

Along the lines of Dey and Hartman (2005), more 

information is needed to determine the different 

probabilities of survivorship by tree characteristics (e.g., 

tree size, growth, age) that exist between shortleaf pine and 

hardwood competitors. It is likely that shortleaf pine has 

a higher probability of surviving repeated fi res compared 

to hardwood competitors, particularly over long periods of 

time and within a smaller diameter range (e.g., 4 to 20 cm 

basal diameter). Identifying the period of development in 

which shortleaf has a higher probability of surviving fi res 

compared to hardwoods would help to develop prescribed 

fi re management guidelines for shortleaf pine restoration. 

From the results of this and other studies mentioned above, 

it appears that shortleaf is tolerant of low-intensity surface 

fi res within a specifi c diameter-height window (e.g., 4- to 

20-cm basal diameter, 4 to 5 m in height) (Walker and Wiant 

1966, Baker 1992) that corresponds to a specifi c range of 

tree ages and fi re frequencies (8 to 15 yrs). 

Long-term effects (e.g., 50+ years) of repeated burning 

on oak-pine forest dynamics are not well understood 

partly because few locations have been monitored for this 
126

length of time. However, much of this pine growth and fi re 

information already exists in the historic record and can 

be gleaned from pine remnants that date to presettlement 

time periods (prior to 1820). Pieces of remnant wood are 

relatively common throughout the entire Ozark region and 

beyond and indicate locations of previous pine sites. The 

success and dominance of pine at time of settlement in the 

Ozarks (e.g., 2 to 6 million acres in Missouri) resulted from 

fi re disturbances that favored shortleaf pine regeneration and 

survival. It is for these reasons that the historic information 

is relevant and perhaps critical to understanding present day 

shortleaf pine community restoration. It should be noted 

that results from the historic shortleaf pine database used in 

this study are based on wildfi re events. More information is 

needed that compares fi re effects resulting from prescribed 

fi res versus wildfi res (see Gnehm and Hadley, this 

proceedings). 

Survivorship of shortleaf pine is not only reduced by short 

time lags to the next fi re and repeated frequent burning, but 

also long-term suppression of fi re. VDDT model simulations 

illustrated that long fi re intervals (e.g., 40+ years) do not 

promote seral states containing shortleaf pine. VDDT 

estimates that long-term suppression of fi re promotes 

the dominance (>80 percemt, Fig. 4) of hardwoods over 

shortleaf pine. In late-successional forests in the Ozarks 

little shortleaf pine regeneration is allowed by small-scale 

disturbances (Shelton and Cain 1999, Stambaugh 2001, 

Stambaugh and Muzika, this proceedings). 

Fire Management

Fire management implications of these results pertain to 

burning frequencies and generalized effects on shortleaf 

pine. One important point is that burning frequencies 

represent mean fi re intervals that are a result of variation in 

years between subsequent fi res. Burning that incorporates 

variability in years between fi res more closely mimics the 

historic fi re regime and the results presented in this study. 

Initial burn effects from decades of litter accumulation may 

not represent those following repeated fi res. 

In young oak-pine forests in the Ozarks, conditions of fi re 

suppression commonly result in pine being overtopped by 

hardwoods. This situation may be less common further 

south in the region, where the species attains greater height 

growth rates. In Missouri underplanting of pine prior to 

overstory removal has been used to enhance shortleaf’s 

competitive ability. However, even under this condition, 

additional hardwood control may be required, further 

emphasizing the species’ need for repeated disturbance. 

Along with frequency, the timing of burning treatments 

is likely a critical consideration for promoting shortleaf 

pine. Regional fi re scar histories show that fi re events 

occurred almost exclusively during the dormant season 

(i.e., approximately October to March). Timing of burns 

should precede the timing of seed dissemination (late 

October, November) and seedling development (early spring 

season) to maximize regeneration survival. Information 

or monitoring of the timing of critical life stages and the 

fi re environment would be of particular value towards 

understanding the appropriate season of fi re for shortleaf 

pine restoration. 

CONCLUSION

The three methods used to determine the appropriate 

burning frequencies for promoting shortleaf pine 

regeneration and survival all resulted in similar conclusions. 

Frequent burning (1- to 4-yr frequency) likely promotes 

regeneration, but a lowered frequency (8 to 15 yrs) promotes 

survival and recruitment into the overstory. We hypothesize 

that an 8- to 15-yr fi re frequency may be a range where 

shortleaf has a higher probability of recruitment than many 

hardwood competitors, especially after longer periods of 

continuous burning. Additional information on fi re effects 

(both prescribed fi re and wildfi re) specifi c to oak-pine 

forests and historic pine growth with corresponding fi re 

information would aid in further defi ning appropriate fi re 

frequencies.

ACKNOWLEDGMENTS

Data used in this study were generated from past studies that 

were funded by the Missouri Department of Conservation, 

Mark Twain National Forest, Ozark National Scenic 

Riverways-National Park Service, U.S. Forest Service 

Northern Research Station, and The Nature Conservancy. 

We are grateful for the many individuals involved in the 

data collection and analysis, particularly George Hartman, 

Adam Bale, and University of Missouri forestry students. 

In addition we thank Erin McMurry and two reviewers for 

their contributions to this manuscript.

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129

EFFECTS OF SITE PREPARATION SUBSOILING AND PRESCRIBED BURNING 

ON SURVIVAL AND GROWTH OF SHORTLEAF PINE IN THE MARK TWAIN 

NATIONAL FOREST: RESULTS AFTER 20 GROWING SEASONS

David Gwaze, Ross Melick, Lynn McClure, Charly Studyvin, and David Massengele1

ABSTRACT.—The objective of this study was to evaluate the effect of subsoiling (ripping) 

and prescribed burning on height, survival, diameter, volume, and competition of planted 

shortleaf pine (Pinus echinata Mill.). The study was established at the Salem Ranger District, 

Mark Twain National Forest. The treatments were subsoil/burn, burn, and control with no 

site preparation. Height was assessed at 5 and 20 years; survival, diameter, volume, and 

competition were assessed at 20 years. Survival rate was only 469 trees/ha in the control 

treatment, while the survival rate was 1680 trees/ha in the burn treatment and 1600 stems/ha 

in the subsoil/burn treatment. Subsoil/burn treatment improved height growth by 55.8 percent 

at 5 years, and 32.3 percent at 20 years over the control treatment. Although, subsoil/burn 

treatment improved volume by 46.5 percent over the control, and burn treatment improved 

volume by 30.6 percent at age 20 over the control, these improvements were not statistically 

signifi cant. Twenty years after planting, these results suggest that site preparation is critical for 

regenerating shortleaf pine and that subsoiling after burning does not provide additional growth 

responses or increased survival to that attributed to burning.

1

Resource Scientist (DG), Missouri Department of Conservation, 

1110 S. College Avenue, Columbia, MO 65201; Former Silviculturist 

(RM) and Silviculturist (CS), Mark Twain National Forest, 401 

Fairgrounds Road, Rolla, MO 65401, Former Silviculturist (LM) and 

Silviculturist (DM), Mark Twain National Forest, 1301 South Main, 

Salem, MO 65560. DG is corresponding author: to contact call 

(573)882-9909 ext. 3320 or email at David.Gwaze@mdc.mo.gov

INTRODUCTION

Shortleaf pine forests in Missouri have been severely 

altered by logging, grazing and fi re suppression, prompting 

restoration efforts within the state. The future success of 

these restoration efforts requires a better understanding 

of site preparation methods. Many of the shortleaf pine 

sites being restored have a dense soil layer (fragipan) 

at soil depths near 18 inches, and hardwoods present 

serious competition problems for the planted shortleaf 

pine seedlings. Subsoiling (ripping) the soil may provide 

openings in the fragipan that allow root growth into and 

below this dense layer. In addition, subsoiling may reduce 

soil bulk density, improve overall root development, and 

increase nutrient uptake. Subsoiling reduces hardwood 

competition around the seedling during the fi rst few years 

after planting, eliminating the need for follow-up release 

treatment from competing hardwoods (Wittwer et al. 1986). 

Subsoiling can be done alone, but is usually easier, safer, 

and more uniform if preceded by a slash-reduction treatment 

such as prescribed burning. Burning prior to subsoiling 

reduces slash, improves the visibility of stumps and other 

obstacles, reduces equipment wear and tear, and reduces the 

time spent freeing ripper teeth of accumulated slash, which 

hinders and reduces subsoiling depth (Fryar 1984). Burning 

reduces competition from grass, forbs and hardwoods. Few 

reports quantify benefi ts of subsoiling on shortleaf pine in 

the USA. In Georgia, subsoiling increased height growth 

by 17 percent, root-collar diameter by 15 percent and tree 

volume by 38 percent fi ve years after planting compared to 

the control (Berry 1979). In Arkansas, subsoiling improved 

survival by 20-25 percent and competition from weeds and 

other vegetation was reduced (McClure 1984). In Missouri, 

subsoiling improved volume by 41.2 percent after two 

growing seasons, but reduced it by 10.2 percent at 16 years 

(Gwaze et al. 2006). 

Prescribed burning is used for regenerating southern pines 

by direct seeding, planting, or natural regeneration (Pritchett 

1979). It is probably the most economical site preparation 

tool (KcKee 1982). Fire alone can control competing 

vegetation until seedlings become established. Prescribed 

fi re has an advantage over mechanical site preparation 

methods such as subsoiling in that less accessible sites 

(e.g., steep slopes) can easily be prepared using burning. 

Although site preparation burning is used in Missouri, 

there is no existing documentation of its effect on survival 

and growth of planted shortleaf pine. In Florida, burning 

improved neither survival nor growth of slash pine 10 years 

after planting (Outcalt 1982). Generally, prescribed burning 

is believed to be most effective when used in conjunction 

with chemical or mechanical site preparation methods (Frey 

1984).
130

The objective of the study is to quantify the long-term 

effects of subsoiling and prescribed burning on survival and 

growth of planted shortleaf pine seedlings at Mark Twain 

National Forest.

MATERIALS AND METHODS

Study Site

The study is located in stand 15, compartment 169, on 

the Salem Ranger District, Mark Twain National Forest. 

The compartment is located in SE of SW 1/4 Section 23, 

T32N, R3W in Reynolds County, southeast Missouri. 

The stand is 17 acres, has a SW aspect, and runs from a 

gentle ridgetop on the NE to a drainage on the SW. Slopes 

exceed 35 percent on spots, but the slope average is 20 

to 25 percent. Soils on the ridge tops are Captina series, 

which characteristically have a fragipan at a depth around 

18 inches. Clarksville soils are generally found on the side 

slopes, and these soils are excessively drained and lack 

fragipans. The original stand was a 60-year-old oak-pine 

stand, dominated by black oak (Quercus velutina), scarlet 

oak (Q. coccinea), post oak (Q. stellata), white oak (Q. 

alba), hickory (Carya spp.) and some scattered shortleaf 

pine (Pinus echinata). The overall site index for the stand is 

60 based on black oak. The stand was clearcut in 1983. 

Site Preparation, Planting, and Assessment

The southeast 6 acres of the stand (control) received no site 

preparation. In June 1984, the northwest 11 acres received a 

good, hot burn. Approximately half of the burned area was 

subsoiled to a depth of 20 inches in fall 1984. The other half 

of the burned area was not subsoiled. The subsoiling was 

done using a single-toothed 25-inch ripper with furrows 

spaced 8 feet apart. Unimproved 1-0 shortleaf pine seedlings 

were planted on a spacing of 8 x 8 feet in spring 1985. 

In June 1989, “V”- shaped transects, with the point of the 

“V” down hill, were established in the burned plus subsoiled 

area and the control area. Transects in both areas ran from 

the ridge on the NE side at an azimuth of 2700 and returned 

at an azimuth of 300. The point of the “V” was located on 

about the same contour line in both treatments. Transects 

were designed to sample across possible variation in slope 

position. A total of 44 trees and 27 trees located along 

the transect were measured for height in subsoil/burn and 

control treatments, respectively. In July 2004 approximately 

the same trees were assessed for height. Because the 

“V” transects did not allow assessment of survival and 

competition, fi ve random plots in each treatment (subsoil/

burn, burn, and control) were established to assess survival 

and hardwood competition in July 2004. Each plot was 100 

square meters (10 m x 10 m). The number, species, height, 

and diameter at breast height of all trees in a plot were 

measured. Height was measured using a height pole and 

diameter at breast height (DBH, cm) using a diameter tape. 

Conical volume (V, dm3

 per tree) was calculated for all trees 

using the following equation:

V = —π(—)

2

H

where D = diameter at breast height (cm), and H = height 

(m).

Statistical Analysis

Analyses were carried out for survival, height, diameter, 

and volume for each age separately. Survival and stocking 

were analyzed using chi-squared tests. Growth data from 

the “V” transects were analyzed using pooled T-tests. The 

assumptions of equal variances and normality were tested 

prior to the pooled T-tests, and were accepted. Growth data 

from plots were analyzed using the PROC GLM procedure 

in SAS Version 9.1 (SAS Institute Inc., Cary, NC). The 

following linear model was used for analyzing the data from 

plots: 

Yij = μ + Ti

 + eij

where Yij is the jth observation on the ith treatment, μ is the 

population mean, Ti is the fi xed effect of treatment, and eij is 

the error term. All analyses were carried out at the P ≤ 0.05 

probability level.

D

2

1

3

RESULTS

Survival

After 20 growing seasons, planted shortleaf pine had 

an average density of only 469 stems/ha in the control 

treatment, a signifi cantly lower density (P < 0.001) than in 

the burn treatment (1680 stems/ha) and in the subsoil/burn 

treatment (1600 stems/ha) (Fig. 1). Survival in the areas 

that were prepared (burn and subsoil/burn treatments) was 

not signifi cantly different, suggesting that subsoiling after 

burning does not provide additional increase in survival to 

that attributed to just burning. Pine stocking in the control 

treatment was 469 trees per ha (190 trees per acre), a 

4.69

16.8 16

0

2

4

6

8

10

12

14

16

18

Control Burn Subsoil/Burn

Trees/100 m2

Figure 1.—Survival of shortleaf pine trees after 20 growing 

seasons.
131

stocking below the minimum required for a fully stocked 

shortleaf pine stand in Missouri.

Growth

Transects 

Trees in the subsoil/burn treatment had signifi cantly greater 

height growth (P < 0.001) than those in the control treatment 

at 5 and 20 years (Fig. 2). Subsoiling after burning increased 

height growth by 55.8 percent and 32.3 percent at age 5 

and 20, respectively. The increased height advantage of 

subsoiling appears to decline with age.

Random Plots

Trees in the subsoil/burn and burn treatments had 

signifi cantly greater height growth than those in the control 

treatment at 20 years (Table 1). However, no signifi cant 

improvement in height growth was attributable to subsoiling 

over that obtained from burning alone. Burning alone 

increased height by 23.4 percent, while burning plus 

subsoiling increased height by 24.2 percent (Table 1). 

Although subsoiling after burning increased diameter 

and volume over the control treatment by 17.2 percent 

and 46.5 percent, respectively, these improvements were 

not statistically signifi cant because of a large variation in 

diameter measurements in the control treatment. 

Hardwood Competition

Twenty years after planting, naturally regenerated hardwood 

species had an average density of 1988 stems/ha in the 

control treatment, a much higher number than in the burn 

treatment (1422 stems/ha) and in the subsoil/burn treatment 

(1244 stems/ha) (Table 2). The differences between 

treatments were not statistically signifi cant (P = 0.100). 

1.6

2.4

7.8

10.3

0

2

4

6

8

10

12

01 01

Height (m)

5 years 20 years

Figure 2.—Treatment effects (0 = control, 1 = subsoil/burn) 

on height growth at 5 and 20 years estimated from “V” 

transects.

Table 1.—Treatment effects on height, diameter, and volume at 20 years estimated from square plots. Standard errors of the 

means are in parentheses.

Trait Subsoil/Burn Increase Burn Increase Control P-value

 (percent) (percent)

Height (m) 9.76 (0.22) 24.2 9.69 (0.23) 23.4 7.86 (0.47) < 0.001

Diameter (cm) 11.83 (0.47) 17.2 11.38 (0.39) 12.8 10.09 (0.92) 0.174

Volume (dm3) 46.04 (3.48) 46.5 41.05 (2.83) 30.6 31.43 (5.51) 0.088

Table 2.—Status of naturally regenerated hardwood vegetation 20 years after planting.

Subsoil/burn Burn Control P-value

Stocking (trees/ha) 1244 1422 1988 0.100

Height (m) 6.32 7.09 6.45 0.03

Diameter (cm) 4.79 6.38 6.56 < 0.001

Hardwoods were signifi cantly taller in the burn treatment 

than in the control and subsoil/burn treatments (P = 0.03). 

Hardwoods in the subsoil/burn treatment were smaller 

in diameter compared to those in the burn and control 

treatments (P < 0.001). 

DISCUSSION

Twenty years after fi eld establishment, subsoiling improved 

survival compared to the control. Results from this study are 

consistent with other studies in Georgia (Berry 1979) and 

Missouri (Gwaze et al. 2006) which showed that subsoiling 

improved survival of shortleaf pine. The improvement in 

survival in this study was much higher than that reported by 
132

Gwaze et al. (2006) partly because the control was treated 

differently in the two studies. In Gwaze et al.’s study, the 

control treatment was bulldozed, while in this study the 

control treatment did not receive any site preparation. 

Because of the more intensive site preparation method in 

the control treatment in their study, the improvement in 

survival due to subsoiling was unimportant 16 years after 

planting. Despite the low survival in the control treatment 

in this study, the stocking of pine (190 stems per acre) may 

be acceptable given Mark Twain National Forest’s current 

emphasis on pine-oak mixtures rather than pine plantations. 

Subsoiling did not provide benefi ts in survival beyond 

those provided by burning alone. Because the number of 

trees in the burn and subsoil/burn was more than 1500 trees 

per hectare (607 trees per acre), fewer seedlings need to 

be planted in both treatments to achieve a stocking of 400 

seedlings at 5 years. In Missouri, a pine stand is considered 

fully stocked if it has 400 shortleaf pine seedlings per acre at 

3-5 years (Gwaze et al. 2006). 

When compared to the control, height growth was 

signifi cantly improved by subsoiling at 5 and 20 years, a 

result consistent with other studies in the United States. 

Berry (1979) reported that height of shortleaf pine was 

improved by 17 percent by subsoiling at 5 years of age in a 

Piedmont site in Georgia. In Oklahoma, subsoiling increased 

height of loblolly pine by 10 percent after two growing 

seasons (Wittwer et al. 1986). In contrast, long-term 

results from studies in Missouri revealed that subsoiling 

at 16 years had no signifi cant effect on height of shortleaf 

pine (Gwaze et al. 2006). Burning alone improved growth 

equally as well as subsoiling and burning. The increased 

growth in the burn/subsoil treatment in this study resulted 

from improved soil physical properties, improved short-term 

nutrient availability, improved soil-water extraction, and/or 

reduced hardwood competition. The increased growth in the 

burn treatment the result of improved short-term nutrient 

availability and reduced hardwood competition. Because 

productivity on the two prepared treatments was similar, the 

increased height growth on prepared treatments compared 

to the control treatment is likely to be the result of reduced 

hardwood competition. 

Hardwood competitors reinvaded regardless of the site 

preparation treatment. However, competing hardwoods 

were fewer and smaller when the site was prepared by 

burning or burning and subsoiling. Burning is likely to 

have killed many hardwoods, and subsoiling damaged root 

systems, which probably reduced the vigor of subsequent 

hardwood sprouts. Survival of trees planted in the control 

treatment (unprepared site) could have been improved by 

follow-up release to control the hardwood competition a 

few years after planting. However, follow-up release may 

not be necessary when the site is prepared using burning or 

subsoiling after burning.

Our results are not consistent with other studies in Florida 

where burning did not improve survival or growth of 

slash pine 10 years after planting (Outcalt 1982). The 

relative effectiveness of prescribed burning depends on 

site characteristics and burn conditions. It is not clear 

why subsoiling after burning provided no benefi t in 

survival, growth and hardwood competition beyond what 

was provided by burning in our study. It may be that the 

subsoiling depth was not suffi cient to break the fragipan or 

that there are other limiting factors below the fragipan that 

restrict tree growth in the subsoiling treatment. It is diffi cult 

to relate the results to soil properties because information 

on soil properties is absent. Results from this study suggest 

that burning can be an effective site preparation method. 

Burning as a site preparation technique also can be 

unpredictable, however, due to varying amounts and types 

of fuel, variations in slope and aspect, and unstable weather 

conditions. Subsoiling might provide additional benefi ts on 

poorer sites which are either severely compacted or rocky.

CONCLUSION

This study demonstrated that site preparation is an important 

factor in regenerating shortleaf pine successfully. Without 

site preparation, high mortality and poor growth can be 

expected from the planted shortleaf pine. The study suggests 

that at 20 years after planting, subsoiling after burning 

does not provide additional growth responses or increased 

survival over that attributed to burning alone. Thus, burning 

might be the preferred site preparation method because the 

extra cost of subsoiling may not be justifi ed.

ACKNOWLEDGMENTS

The work reported here was supported by the Mark Twain 

National Forest. We thank students Brandon Kell and John 

Muehlman for plot installation and measurements. We thank 

Jillian Lane for her assistance in the statistical analysis.

LITERATURE CITED

Berry, C.R. 1979. Subsoiling improves growth of pine on a 

Georgia Piedmont site. Res. Note SE-284. Asheville, 

NC: U.S. Department of Agriculture, Southeastern 

Research Station. 3 p.

Frey, C.J. 1984. Prescribed burning as a site preparation 

method for artifi cial regeneration of shortleaf pine. In: 

Artifi cial reforestation of shortleaf pine: a Missouri 

seminar; 1984 May 9; Salem, MO. Rolla, MO: U.S. 

Department of Agriculture, Forest Service, Mark Twain 

National Forest: 18-36.

Fryar, R. 1984. Ripping on the Ouachita. Presented at the 

silvicultural recertifi cation meeting in Augusta, GA. 

7 p.
133

Gwaze, D.; Hauser, C.; Johanson, M. 2006. A 16-year 

evaluation of effects of ripping on shortleaf pine on a 

Missouri Ozarks site. In: Connor, Kristina F., ed. 2006. 

Proceedings of the 13th Biennial Southern Silvicultural 

Research Conference. Gen. Tech. Rep. SRS-92. 

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

Service, Southern Research Station: 195-199.

KcKee, W.H. 1982. Changes in soil fertility following 

prescribed burning on coastal plain sites Res. Paper 

SE-234. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southeastern Research 

Station. 23 p.

Law, J.R.; Melick, R.; Studyvin, C.; Steinman, J.R. 2004. 

Oak decline in Missouri: history revisited. In: Spetich, 

M.A., ed. Upland oak ecology symposium: history, 

current conditions, and sustainability. Gen. Tech. 

Rep. SRS-73. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research Station: 

257-258.

McClure, L. 1984. Mechanical site preparation. In: Artifi cial 

reforestation of shortleaf pine: a Missouri seminar;1984 

May 9; Salem, MO. Rolla, MO: U.S. Department of 

Agriculture, Forest Service, Mark Twain National 

Forest: 50-60.

Pritchett, W.L. 1979. Properties and management of forest 

soils. New York: John Wiley and Sons. 500 p.

Outcalt, K.W. 1983. Mechanical site preparation improves 

growth of genetically improved and unimproved 

slash pine on a Florida fl atwoods site. In: Jones, 

P., ed. Proceedings of the second biennial southern 

silvicultural conference; 1982 November 4-5; Atlanta, 

GA: Gen. Tech. Rep. SE-24. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, Southeastern 

Research Station: 11-13.

Wittwer, R. F.; Dougherty, P.M.; Cosby, D. 1986. Effects 

of ripping and herbicide site preparation treatments on 

loblolly pine seedling growth and survival. Southern 

Journal of Applied Forestry. 10: 253-257.
134

THE EFFECTS OF A WILDFIRE ON PINE SEEDLING RECRUITMENT

Paula C. Gnehm and Brad Hadley1

ABSTRACT.—We investigated the effects of a single arson wildfi re by comparing its impact 

on pine seedling recruitment with that of both prescribed fi re and unburned compartments. 

Although a t-test detected no signifi cant difference in pine seedling recruitment (p = 0.38), the 

“wildfi re” treatment produced 127 more seedlings than the unburned treatment, and 96 more 

seedlings than the prescribed fi re treatment. Managers should consider using burn conditions 

similar to a wildfi re when the primary objective is a simple increase in the pine component of a 

particular stand.

1

Resource Assistant (PCG), Peck Ranch Conservation Area, 

Missouri Department of Conservation, PO Box 180, Jefferson 

City, MO 65102; and Conservation Agent (BH), Shannon County, 

Missouri Department of Conservation, PO Box 181, Birch Tree, MO 

65438; Biology Department Adjunct Faculty (BH), Drury University, 

900 N. Benton Ave., Springfi eld MO 65802. PCG is corresponding 

author: to contact call (573) 300-9572 or email at tattat1@hotmail.com

INTRODUCTION

Wildfi res are not an uncommon occurrence in the Missouri 

Ozarks. The differences between their effects and those 

of prescribed fi re on shortleaf pine (Pinus echinata Mill.) 

seedling recruitment are unknown. 

Shortleaf pine is one of the many pine trees that can be 

found in Missouri, but it is the only pine tree that is native to 

the state. It takes approximately 2 years for a shortleaf pine 

seed to germinate naturally. Shortleaf pine seedlings have 

a persistent J-shaped crook at the ground level (Lawson 

2006). A shortleaf pine’s above-ground growth during the 

fi rst year is very minimal compared to the root system it 

is putting in the ground. A year-old seedling can easily be 

overlooked because even with its needles, it is only about 

1 to 1.5 inch in diameter, and about the same in height. 

Shortleaf’s intense need for full sunlight will allow it to 

grow only in open areas. Throughout the tree’s life this need 

for sunlight continues; as the tree grows taller, the limbs at 

the top of the tree shade the older branches on the bottom. 

The older branches consequently wither and die, giving 

the tree its characteristic form of bare stems and leafy tops 

(Dorst and Crandall 2005).

Like other conifers, shortleaf pines are generally prolifi c 

seed producers. However, site preparation is usually 

necessary for natural regeneration. The small, winged seeds 

must come into direct contact with the soil on the forest 

fl oor to effectively germinate and grow. Usually a thick 

layer of litter deposits, such as leaves, grasses, branches, 

and weeds, will produce a barrier between the seeds and the 

soil. Prescribed burning is an excellent method to remove 

this barrier. This method is used to help promote the natural 

regeneration of many plants, including shortleaf pine. Fire 

will also eliminate most of the hardwood and vegetative 

competition and some of the standing dead trees, ultimately 

opening the canopy and allowing penetration of the direct 

sunlight the seedlings need to grow (Zimmerman 2006). 

In April 2003, a very intense arson wildfi re on Birch Creek 

Conservation Area burned approximately 160 acres. Four 

agencies were on site for approximately 8 hours, with an 

estimated total labor force of 25 people. The roughly 7,000 

acres of the Birch Creek Conservation Area are under a 

15-year management rotation. The particular area burned 

had received no management treatments in the recent past 

(since 1994), leaving it fully stocked with trees but little 

to no slash. In the 2 years since the fi re, the area has had a 

salvage timber sale. 

We investigated the effects of the wildfi re by comparing 

its impact on pine seedling recruitment with that of both 

prescribed fi re and unburned compartments.

STUDY AREA

Three study sites were located within the Current River 

Hills Subsection of the Ozark Highlands Ecological 

Section (Nelson 2005) on Birch Creek and Peck Ranch 

Conservation Areas. The primary study site was the site 

of the wildfi re burn; it had been subject to wildfi re 2 years 

prior to the study period, and was located within an existing 

pine stand. This site had a slightly north-facing slope. In our 

choice of comparison sites, we made every effort to match 

their attributes to those of the primary study site. Variation 

within a specifi c stand is always apparent, however, and it is 

therefore virtually impossible to perfectly “match” attributes 

among disjunct stands. Nevertheless, the two comparison 

sites were selected from those available with similar 

attributes, including aspect, slope, natural community 

types, seed source availability, and soil type. Beyond these 
135

attributes, the second site was within a prescribed burn 

compartment and had been subject to prescribed fi re under 

conditions that were mild, compared to the wildfi re site. 

The site was located on Peck Ranch Conservation Area. The 

third site was within an unburned compartment, which was 

also located on Peck Ranch Conservation Area. 

METHODS

Randomly selected plots of approximately 1 acre were 

chosen within each treatment type. Twelve randomly 

selected (using random number key for bearing and distance 

from center) subplots 12 ft in diameter (≈ 113.25 square 

feet) within each treatment type plot were sampled. Subplots 

were sampled by driving a rebar stake with a 6-ft length of 

rope attached into the ground and pivoting around that stake 

to the true place of beginning, counting all seedlings (fi tting 

subjective assessment as being ≤ 2 years old) observed. 

Statistical analysis of sample means (t-test[α.05]) was 

performed using Minitab® 12.1 software (Minitab®, State 

College, PA) on a standard PC.

RESULTS

Twenty-six seedlings were counted for all three of the study 

sites. Their distribution in the sample is illustrated in Figure 1. 

The calculated average number of seedlings per subplot was 

extrapolated to estimate the number of seedlings per acre by 

treatment type (Fig. 2). Although the “wildfi re” treatment 

produced 127 more seedlings than the unburned treatment, 

and 96 more seedlings than the prescribed fi re treatment, 

the t-test detected no signifi cant difference in pine seedling 

recruitment (p = 0.38).

DISCUSSION

The t-test’s failure to detect a signifi cant difference may be 

an artifact of sample size, in that only 3 percent of each of 

the study sites was sampled. It is possible that by chance 

alone the least intensely burned areas were sampled in the 

wildfi re area, and the most productive pine seedling areas 

were sampled in the unburned area. The outcome of such 

chance events would tend to bias the sample towards no 

signifi cant difference between treatments. Another factor 

that could have infl uenced this study is the fact that the 

wildfi re-burned area had been subjected to a salvage sale. 

As stated earlier, removal of standing dead trees “opens” 

the ground to sunlight. This increase in sunlight could 

have contributed disproportionately to the greater seedling 

recruitment on the wildfi re-burned area. However, the fact 

remains that this wildfi re and its subsequent management 

resulted in the recruitment of an estimated 127 more pine 

seedlings per acre on the wildfi re burned area than on 

the unburned area. Managers should consider using burn 

Unburned, 0.0052

27%

Wild, 0.0081

42%

Prescribed, 0.0059

31%

Figure 1.—Average pine seedling recruitment per square 

foot by fi re treatment type, and percent of total number of 

seedlings in sample. Seedlings per subplot

Seedlings per subplot

Seedlings per acre

Seedlings per acre

Figure 2.—Number of seedlings per acre as estimated from 

number per subplot by treatment type.

Wild Prescribed Unburned

conditions similar to a wildfi re if and when affecting a 

simple increase in the pine component of a particular stand 

is their primary objective.

Timing, intensity, and frequency of prescribed burns are 

critical to establish and develop successful shortleaf pine 

stands (Cain and others 1998). Our results suggest that 

to best achieve initial ecological release, prescribed fi res 

should be performed under parameters that allow for intense 

heat, such as those in “wildfi re” conditions.

ACKNOWLEDGMENTS

We thank the Peck Ranch Wildlife Division staff of Dan 

Drees, Kim Houf, Marshall Price, Patti Vessels, and Leta 

Hightower, and Eminence District Forestry staff of Johnny 

Tuttle and Gary Gognat for their time, effort, and support. 

We also thank reviewers of this manuscript for suggestions 

that resulted in its improvement.

LITERATURE CITED

Cain, M.D.; Wigley, T.B.; Reed, D.J. 1998. Prescribed fi re 

effects on structure in uneven-aged stands of loblolly 

and shortleaf pines. Wildlife Society Bulletin. 26(2): 

209-218.
136

Dorst, H.; Crandall, J. 2005 retrieval. An introduction to 

Ozark trees. [online]. Available: http://www.watersheds.

org/nature/trees.htm

Lawson, E.R. 2006 retrieval. Pinus echinata Mill. [online]. 

Available: http://www.na.fs.fed.us/spfo/pubs/silvics_

manual/volume_1/pinus/echinata.htm

Nelson, P.W. 2005. The terrestrial natural communities of 

Missouri. Jefferson City, MO: The Missouri Natural 

Areas Committee. 550 p.

Zimmerman, M.L. 2006. The effects of prescribed fi re 

on the herbaceous layer in the southern Appalachian 

Mountains. Johnson City, TN: East Tennessee State 

University. 111 p. M.S. thesis.
137

HARDWOOD REGENERATION RELATED TO OVERSTORY SHORTLEAF PINE 

BASAL AREA AND SITE INDEX IN ARKANSAS AND EASTERN OKLAHOMA

Douglas J. Stevenson, Thomas B. Lynch, and James M. Guldin1

1

Senior Research Specialist (DJS), Natural Resource Ecology and 

Management, Oklahoma State University, Stillwater, OK 74078; 

Professor, Natural Resource Ecology and Management, Oklahoma 

State University, Stillwater, OK 74078; Supervisory Ecologist and 

Project Leader, Southern Research Station, USDA Forest Service, 

P.O. Box 1270, Hot Springs, AR 71902. DJS is corresponding author: 

to contact call (405) 744-5515 or email doug.stevenson@okstate.edu

EXTENDED ABSTRACT

Shortleaf pine (Pinus echinata Mill.) grows in association 

with many other woody species, particularly understory 

hardwoods, which compete with it, limiting its productivity. 

Along with other species, sweet-gum (Liquidambar 

styracifl ua L.) is a major competitor on better-quality sites 

but decreases rapidly in importance as pine site index (SI) 

decreases and pine overstory increases.

Over 200 fi xed-radius 0.2-acre plots were permanently 

established in naturally-occurring shortleaf pine stands 

located in the Ozark and Ouachita National Forests during 

the period 1985 to 1987 as part of a forest growth study. 

Five trees per plot were sampled using increment borers 

to determine age. Height measurements were made on 

two trees in each one-inch diameter class on each plot and 

diameter at breast height (DBH) was measured on all trees. 

SI was calculated using Graney and Burkhardt’s (1973) 

equation for each SI sample tree and averaging the result for 

each plot.

Initially plots were thinned to assigned basal area levels 

and hardwoods were treated with chemical herbicide. 

During the 1995-1997 re-measurement of these plots, two 

0.005-acre subplots were established within each of the 

shortleaf growth plots to assess shortleaf regeneration and 

abundance of understory hardwoods. During the 2000-2001 

remeasurement, an additional two 0.005-acre subplots were 

added. At each re-measurement, saplings over 4.5 feet tall 

were tallied by plot and species.

Each plot was an observation. Shortleaf pine basal area 

(square feet per acre) and SI (50-year basis) were used as 

environmental (dependent) variables. Seedling counts by 

plot were used as species (independent) variables. Thinning 

treatment was used as a co-variable (dummy variable). 

There were 52 sapling species in the sample.

Analysis was carried out using partial Canonical 

Correspondence Analysis (pCCA) as described by Leps and 

Smilauer (2003). Analysis indicates that most associated 

hardwood species are sensitive to pine site quality as 

determined by SI and shade under shortleaf pine canopies 

using overstory basal area as a proxy for shade.

SI and basal area explained 12.9 percent of total variation 

in species composition. The fi rst pCCA axis accounted for 

4.5 percent of variation, the second for an additional 3.1 

percent and the third for another 2.4 percent. Species vs. SI 

and basal area correlation was 0.551, 0.554 and 0.445 for 

the fi rst, second and third axes, respectively.

Sweet-gum was the major hardwood species on the SI scale 

on sites above SI 85. Green ash (Fraxinus pennsylvanica

Marsh.), red maple (Acer rubrum L.), dogwood (Cornus

spp. L.), winged elm (Ulmus alata Michx.) and black oak 

(Quercus velutina Lam.) were common species on sites 

above 60 SI. Dogwood was the most common species 

on sites between 65 and 75 SI. Red maple was common 

throughout all sites but was the predominant hardwood 

species on sites below 65 SI.

All species responded along a decay curve related to pine 

basal area. Sweet-gum and black-gum (Nyssa sylvatica

Marsh.) were the most-common species with almost 

identical curves. Both were strongly infl uenced by pine 

basal area. Mockernut hickory (Carya tomentosa Nutt.) was 

the species least affected by basal area, occurring at low 

levels on all sites.

ACKNOWLEDGMENTS

The cooperation of personnel on the USDA Forest Service 

Ozark and Ouachita National Forests greatly facilitated 

collection of data used for this project. The support and 

assistance of the USDA Forest Service Southern Research 

Station is also appreciated.

LITERATURE CITED

Graney, D.L.; Burkhardt, H.E. 1973. Polymorphic site index 

curves for shortleaf pine in the Ouachita Mountains. 

Res. Pap. SO-85. New Orleans, LA: U.S. Department 

of Agriculture, Forest Service, Southern Research 

Station. 12 p.

Leps, J.; Smilauer, P. 2003. Multivariate analysis of 

ecological data using CANOCO. New York: Cambridge 

University Press: 180-188.
138

SHORTLEAF PINE REPRODUCTION ABUNDANCE AND GROWTH 

IN PINE-OAK STANDS IN THE MISSOURI OZARKS

Elizabeth M. Blizzard, Doyle Henken, John M. Kabrick, 

Daniel C. Dey, David R. Larsen and David Gwaze1

ABSTRACT.—We conducted an operational study to evaluate effect of site preparation 

treatments on pine reproduction density and the impact of overstory basal area and understory 

density on pine reproduction height and basal diameter in pine-oak stands in the Missouri 

Ozarks. Stands were harvested to or below B-level stocking, but patchiness of the oak decline 

lead to some plots having no overstory and some having over 200 ft2/ac basal area at the 

end of the study. In all stands, the midstory and understory were chainsaw felled. If stands 

were inadequately stocked with pine reproduction, then mechanical scarifying or prescribed 

burning treatments were applied to increase the density of shortleaf pine reproduction. Pine 

reproduction basal diameter, height, and crown class within the understory were measured 

three to eight growing seasons later. 

We found no long-term difference in pine reproduction density by treatment. Overstory density 

and reproduction competition both affected the growth of shortleaf pine seedlings. The basal 

diameter and height of pine reproduction were greatest when overstory basal area was low, 

reproduction density was low, and pine seedlings were dominant or codominant to competitors 

within the understory. Pines had an 80 percent chance of being dominant/codominant with 

2,000 TPA of mixed-species reproduction with no overstory, but only a 50 percent probability 

with 6,000 TPA of reproduction and 70 ft2

/ac of overstory basal area.

1

Graduate Research Assistant (EMB), Department of Forestry, 

203 Natural Resources Building, University of Missouri, Columbia, 

MO 65211; Silviculturist (DH), USDA Forest Service, Houston/

Rolla/Cedar Creek Ranger District, 108 S Sam Houston Blvd., 

Houston, MO 65483; Research Forester (JMK and DCD), USDA 

Forest Service, Northern Research Station, 202 Natural Resources 

Building, Columbia, MO 65211; Professor (DRL), Department of 

Forestry, 203 Natural Resources Building, University of Missouri, 

Columbia, MO 65211 and Resource Scientist (DPG), Missouri 

Department of Conservation Resource Science Center, 1110 South 

College Ave., Columbia, MO 65201. JMK is the corresponding 

author: to contact call (573) 875-5341 or email at jkabrick@fs.fed.us 

INTRODUCTION

Foresters, conservationists and ecologists have expressed 

interest in restoring shortleaf pine (Pinus echinata Mill.) 

throughout its native range in the Ozark Highlands. 

Restoring shortleaf pine is a long-term strategy for 

mitigating chronic oak decline and bringing back natural 

mixed species forests and woodland communities that are 

important to wildlife (Nelson 2005, Dickson et al. 1995). 

At varying times throughout the Missouri Ozarks, patches 

of oak decline have resulted in 30 to 70 percent mortality in 

the overstory. Scarlet oaks (Quercus coccinea Muenchh.) 

and black oaks (Q. velutina Lam.) , especially those that 

are older than 70 years, are particularly susceptible to oak 

decline (Starkey et al. 1989). Shortleaf pine and white oak 

(Q. alba L.) are longer-lived than scarlet and black oak, and 

where present they can lengthen the biological rotation age 

of mixed-species stands.

Shortleaf pine once was extensive in the Ozarks and was 

a major component of most forest types. Past forest uses 

have resulted in even- and mixed-aged scarlet, black, and 

white oak stands dominating former shortleaf pine sites. 

Mortality from oak decline is exacerbated in scarlet and 

black oaks grown on these poor sites (Starkey et al. 1989). 

Oaks on poor quality, droughty sites have slow growth due 

to nutrient and moisture defi ciencies. Drought and insect 

defoliation and wood boring insects in turn weaken oaks, 

making them more susceptible to Armillaria root disease, 

which further weakens or damages black, scarlet, and some 

white oak trees. Shortleaf pine is not affected by most oak 

pests and pathogens, but it is susceptible to annosum root 

disease (Heterobasidion annosum) and southern pine beetle 

(Dendroctonus frontalis Zimmermann), among others 

(Woodward et al. 1988). However, shortleaf pine pathogens 

and pests tend to not be a problem in natural pine and pinehardwood stands (Brinkman and Smith 1969).

There is growing interest in restoring pine and pine-oak 

mixes because of their ecological importance and their 

capacity to mitigate oak decline. Mixed species stands have 

several advantages. A mixed species stand may decrease 
139

the continuity of food sources for species-specifi c pests and 

decrease the occurrence of root grafts, thereby limiting the 

spread of pathogens. A mixed species stand may provide 

managers more options in the case of an insect or disease 

outbreak by allowing for partial thinnings. Although there 

is much research about growing pine monocultures, there 

is little information about restoring and managing pine and 

oak mixes. Pines and oaks have very different ecological 

strategies that makes regenerating them together a 

challenge, as upland oaks often readily regenerate on former 

pine sites in the Ozarks, whereas shortleaf pine may require 

some site preparation and release treatments. 

Stands that were salvaged due to oak decline between 1997 

and 2000 were selected for an operational management 

study as part of a collaboration between forest managers 

and researchers to evaluate success of site-preparation 

treatments and to begin evaluating the effects of retained 

overstory trees and same-age reproduction on pine 

reproduction growth. This paper has three objectives: 

1) to evaluate pine reproduction densities several years 

after scarifying or burning compared with stands that had 

adequate pine reproduction densities after harvest; 

2) to analyze the roles of overstory density and understory 

competition on growth of pine reproduction; and 3) to 

analyze the roles of overstory and understory densities on 

the density of oak and other hardwood species that were 

within 5.3 ft of the pine.

METHODS

Study Sites

Study sites were located in northern Texas County on the 

Houston Ranger District of the Mark Twain National Forest 

in Missouri. Sites fall within the Big Piney River Oak-Pine 

Woodland/Forest Hills within the Gasconade River Hills 

Subsection of the Ozark Highlands (Nigh and Schroeder 

2002). Ecological land types included narrow to broad 

ridges, and slopes on all aspects. Soils are mostly mapped 

as Coulstone (loamy-skeletal, siliceous, semiactive, mesic 

Typic Paleudults), and include Clarksville (loamy-skeletal, 

siliceous, semiactive, mesic Typic Paleudults), Hobson 

(fi ne-loamy, siliceous, active, mesic Oxyaquic Fragiudalfs), 

and Lebanon (fi ne, mixed, active, mesic Typic Fragiudults). 

Slopes range from 6 to 32 percent with a mean of 15 

percent. Growing seasons last 210-230 days with a mean 

annual temperature of 54-57 °F (Wendland et al. 1992). 

Shortleaf pine site indices range from 51 to 64 ft, with a 

mean of 58 ft (Table 1).

We classifi ed stands with 25 to 48 percent pine as pine/oak 

and stands with more than 49 percent pine as pine (Table 

2). Stands were fully stocked prior to salvaging, but had 

varying degrees of oak decline (Rogers 1982). Oak decline 

salvage operations left mature pine and pine/oak stands at or 

below B-level. 

Table 1.—Acreage, ecological land types, site indices, and soil types of stands in the study.

 Compartment- Size Ecological Site Index 

 Stand (ac) Landtype (ft at age 50 yr) Soil Type

 2-21 4 narrow ridge Black Oak 55 Clarksville

 2-25 9 narrow ridge Shortleaf P 60 Clarksville

 2-29 10 south or west slope Shortleaf P 55 Coulstone

 2-33 11 south or west slope Shortleaf P 60 Coulstone

 2-34 4 narrow ridge Shortleaf P 59 Clarksville

 2-45 7 south or west slope Shortleaf P 56 Coulstone

 2-46 7 north or east slope White Oak 58 Coulstone

 2-48 13 north or east slope Shortleaf P 64 Coulstone

 2-74 16 south or west slope Shortleaf P 60 Lebanon

 13-36 47 north or east slope Shortleaf P 51 Clarksville

 13-58 8 narrow ridge Shortleaf P 64 Hobson

 16-04 19 north or east slope Shortleaf P 55 Coulstone

 16-27 8 broad ridge Shortleaf P 58 Coulstone
140

1

Pine/Oak = 25-48 percent pine; Pine = >49 percent; Black oak = >50 percent

2

Cut undesired trees and sprouts

3

Also fi lled in with pine seed

Table 2.—Overstory stocking and stand treatments.

Timeline (yr)

Compartment 

Stand Type1

Post-Harvest 

Basal Area 

(ft2

/ac)

Harvested

Shelterwood

Chainsaw 

Follow-up2

Site-Preparation

Uneven Scarifi ed Burned

 2-21 Pine/Oak3

 50 1997 2000, 2002 2000

 2-25 Pine 80 1997 2000, 2002 2000

 2-29 Pine/Oak 80 1997 2000, 2002 2000

 2-33 Pine/Oak 40 1997 2000, 2002 2000

 2-34 Pine 80 1997 2000, 2002 2000

 2-45 Pine 70 1997 2000

 2-46 Black Oak 40 1997 2000

 2-48 Pine/Oak 40 1997 2000

 2-74 Pine/Oak 80 2000 2000 2000

 13-36 Pine/Oak 92 1996 1998 1998

 13-58 Pine 103 1996 1998 1998

 16-04 Pine 70 1998 20003

 2000

 16-27 Pine/Oak 100 1998 2000

2

Contact Doyle Henken for more information on building the anchor 

chain scarifi er.

Site Preparation

We surveyed shortleaf pine reproduction after loggers 

completed the overstory salvage harvests. Even-aged stands 

with 435 shortleaf pine seedlings per acre and uneven-aged 

stands with a growing stock in 60 percent of the 0.2-ac 

openings were adequately stocked, received no further 

treatments, and are used as a benchmark in this study. 

Stands with inadequate stocking were either mechanically 

scarifi ed or burned (Table 2). 

The site was mechanically scarifi ed to improve the 

seedbed in stands that had patches of pine reproduction 

already established. To scarify, we pulled an anchor chain 

assembly—two 25-lb anchor chains with round rods welded 

across the links—behind a bulldozer at about 5 ac/hr, 

focusing on areas within the stand that were inadequately 

stocked2. The anchor chain assembly appears to be less 

damaging to hardwoods than the heavy disk method 

recommended by Haney (1962). We then used chainsaws 

to fell residual unmerchantable mid- and understory trees 

according to even-aged or uneven-aged (removing the worst 

and leaving the best) guidelines after scarifying or before 

burning. 

Burning was used in stands that required additional pine 

reproduction throughout. Logistic delays resulted in an 

ineffective initial burn, requiring a second prescribed fi re 

(Table 2). We burned fi ve stands 2 years after harvest to 

allow slash to decompose prior to burning. Unfortunately, 

the burn occurred after seed fall, so we did not expect much 

seedling establishment. The burn did not control hardwoods 

very well but did establish some pine reproduction. We 

conducted a second (and fi nal) burn in November of 2002. 

Data Collection

We inventoried the stands in the winter of 2005-2006. We 

ran transects with data collection nodes every 100 ft, used a 

10 BAF prism to measure the overstory, and collected pine 

reproduction data using the point-centered quarter method 

(Fig. 1; Mitchell 2001). At each node, we recorded the 

distance to the closest pine in each of four quadrants. We 

measured the height and basal diameter of the tallest of the 

four pines and tallied understory competition within a 5.3-ft 

radius. Then, we recorded height and species of the tallest 

understory competitor within the circle. 
141

Figure 1.—Example of four-quarter sampling. Distance from 

the transect node to the closest pine seedling or sapling 

(*) in each quadrant was measured. The circled pine is the 

tallest of the four measured pines; all pine, oak, and other 

hardwood competition was tallied within a 5.3-ft radius of 

the tallest pine. Height of the tallest competitor was also 

recorded.

Data Analysis

We used linear and logistic regression to analyze the data 

(Proc Reg, Proc Logistic, SAS 2003). We used Y = β0 + β1X1

+ β2X2 + ... + βiXi for all models, except the probability of a 

given pine being dominant/codominant for which we used P 

= (e^(β0 + β1X1 + β2X2 + ... + βiXi))/(1+ e^(β0 + β1X1 + β2X2

+ ... + βiXi)). We tested combinations of indicator variables 

that we thought best modeled the stand dynamics that occur 

between a given pine seedling/sapling, the overstory and 

other reproduction. Some of the models tested are shown 

in Table 3. Most models tested had three components: 

overstory basal area, reproduction density, and age. Pine 

growth and density models included combinations of the 

following predictor variables: the pine’s crown class within 

the understory, total basal area (or oak, other hardwood, 

and pine basal areas; ft2/ac), density of total reproduction 

(TPA), density of non-pine reproduction (oak and other 

hardwoods; TPA), and age (yrs). Age was designated as the 

number of growing seasons since last treatment. Oak and 

other hardwood density models included the above predictor 

variables except pine crown class.

We differentiated the signifi cant stand dynamics models 

using Akaike Information Criterion (AIC) scores (Table 3; 

Burnham and Anderson 2003, Proc Mixed, Proc Logistic, 

SAS 2003). Models with the lowest AIC scores best 

describe the stand dynamics with the fewest indicator 

variables. We considered models ≥ 2 AIC units apart to be 

different (Burnham and Anderson 2003). 

RESULTS

Indicator Variables

We selected stands to include a wide range of overstory 

densities at the plot level. Overstory basal area at the plot 

level ranged from 0 to 200 ft2

/ac, with a mean of 63 ft2/ac 

3 to 8 years after regeneration (Table 4). Because of 

the wide range in basal area, the density of understory 

competitors with pine ranged considerably from 0 to 20,732 

TPA, with a mean of 4,615 TPA. Understory competitor 

heights ranged from 0 to 19 ft, with heights relative to the 

sample pine of -10 ft to 15 ft.

Pine Density

Prescribed burning and mechanical scarifi cation both 

maintained stocking levels comparable to stands that 

were adequately stocked after harvest (Benchmark, 

Fig. 2). Benchmark stands had a mean of 201 ±98 TPA, 

prescribed burned stands had a mean of 345 ±98 TPA, and 

mechanically scarifi ed stands had a mean of 257 ±126 TPA. 

Thus, both prescribed burning and mechanical scarifi cation 

operation treatments were successful. 

Pine Basal Diameter

The basal diameter of pine reproduction increased as its 

crown class in the understory improved, and as the overstory 

basal area decreased (Fig. 3). Canopy class (within the 

understory), overstory basal area, and height of the tallest 

competitor were the strongest predictors of pine basal 

diameter (Table 5). The total reproduction density was not 

found to be a signifi cant factor affecting the basal diameter 

of pine reproduction. Models with overstory basal area 

and/or other reproduction specifi ed by species group did not 

improve the prediction of pine basal diameter based upon 

AIC scores. These results suggest that the basal diameter 

of pine is primarily affected by its crown class within the 

understory but also by the basal area of the overstory.

Pine Height

Pine height increased with increasing crown class and 

decreased with increasing overstory basal area (Fig. 4). 

A combination of crown class, overstory basal area, age, 

density of reproduction, and height of the tallest competitor 

best predicted pine height (i.e., lowest AIC value) and 

had an R2

 of 0.47 (Table 5). The species of neither the 

overstory nor the understory added suffi cient information 

to warrant their inclusion in the model based upon AIC. 

The results also show that relatively large changes in 

overstory basal area are required to have the same impact 

on pine reproduction height compared to the effect of crown 

position.

Probability of a Given Pine 

Being Dominant/Codominant

Because of the importance of crown class for predicting 

height and diameter growth, we examined factors related 

to the crown position of the pine reproduction. Crown 

class is determined in part by the density of reproduction 

in the understory and by density of the overstory. Factors 

included in modeling crown class were density of non-pine 

5.3-foot radius plot 

centered on the tallest 

of the four pines measured
142

Table 3.—Linear and logistic models with diagnostic statistics for measures of pine growth and density of competition around 

the pine. Models are ordered by inclusion of components. Models with the lowest Akaike Information Criterion (AIC) scores best 

describe the stand dynamics with the fewest indicator variables. Models with < 2 AIC units apart were similar (∆AIC). 

1

Abbreviations: Age = number of growing seasons since regeneration treatment; BA = Basal area (ft2/ac); CompHt = height (ft) of the tallest 

competitor within the understory; Dom., Codom., Inter. = dominant, codominant, or intermediate pine within the understory, use 1 if true, 0 

otherwise; Int. = y-intercept; Over. = overstory; Oth. Hwd. = other hardwood tree species; and Repro = density of reproduction (TPA). 2

All parameters and statistics are signifi cant except those followed by an “ ’ ”. 3

Model: Y = β0 + β1X1 + β2X2 + ... + βiXi. 4

Model: P = (e^(β0 + β1X1 + β2X2 + ... + βiXi))/(1+ e^(β0 + β1X1 + β2X2 + ... + βiXi)).

Statistics

MODELS1,2 AIC ∆AIC F-value R2

PINE BASAL DIAMETER3

OverBA Age TotalRepro. Compht’ 464 146 10 0.12

Dom Codom Inter OverBA Age TotalRepro.’ 354 36 32 0.38

Dom Codom Inter OverBA Age TotalRepro.’ Compht 318 0 39 0.46

Dom Codom Inter OverBA Age Nonpinecomp’ Pine’ Compht 325 7 34 0.46

Dom Codom Inter OakBA PineBA HwdBA Age PineRepro.’ Non-PineRepro.’ Compht 345 27 27 0.47

PINE HEIGHT3

OverBA Age TotalRepro. Compht’ 1377 159 11 0.12

Dom Codom Inter OverBA Age TotalRepro.’ Compht 1218 0 40 0.47

Dom Codom Inter OverBA Age Non-PineRepro.’ PineRepro.’ Compht’ 1223 5 35 0.47

Dom Codom Inter OakBA PineBA HwdBA’ Age NonPineRepro.’ PineRepro.’ Compht 1237 19 28 0.48

DENSITY OF NON-PINE3

OverBA’ Age’ PineRepro.’ 1859 0 2’ 0.01

OakBA HwdBA’ PineBA’ Age’ 1861 2 3 0.04

OakBA HwdBA’ PineBA’ Age’ PineRepro. 1860 1 3 0.05

DENSITY OF OAK3

OverBA’ Age’ 1567 23 1’ 0.01

OverBA’ Age’ Non-OakRepro.’ 1552 9 8 0.07

OakBA Age’ 1561 18 3 0.02

OakBA Age’ Non-OakRepro.’ 1544 0 10 0.09

OakBA PineBA’ HwdBA’ Age’ PineRepro. HwdRepro. 1555 12 6 0.11

DENSITY OF HWD3

OverBA’ Age’ Non-HwdRepro. 1817 4 67 0.06

OakBA PineBA’ HwdBA’ Age 1835 22 2’ 0.03

OakBA Age 1825 12 3 0.02

OakBA Age Non-HwdRepro 1813 0 8 0.07

OakBA PineBA’ HwdBA’ Age Non-HwdRepro 1824 11 5 0.07

PROBABILITY OF A GIVEN PINE BEING DOM./CODOM.4

 Chi-Square

OverBA Age’ TotalRepro.’ Compht 298 0 73

OverBA Age’ Non-PineRepro Pine Compht 298 0 105

OakBA PineBA HwdBA’ Age’ TotalRepro.’ Compht 330 32 75

OakBA PineBA HwdBA’ Age’ Non-PineRepro. Pine Compht 300 2 107
143

reproduction, density of pine reproduction, overstory basal 

area, and age and height of the tallest competitor; the model 

had a Chi-square of 105.2 (Table 5). 

The probability of a given pine being dominant or 

codominant increased with decreasing overstory density 

and with decreasing reproduction density (Fig. 5). To have a 

greater than 50/50 chance of a given pine being dominant or 

codominant the overstory basal area must be less than 

70 ft2

/ac with 2,000 TPA or less in the understory, or less 

than 10 ft2/ac overstory basal area with 6,000 TPA or less in 

the understory. 

Table 4.—Winter 2006 overstory basal area (ft2/ac), understory density (TPA), height (ft) of the tallest competitors, and height (ft) 

of the tallest competitor relative to the pine reproduction.

All Species 63 (0 – 200) 4,615 (0 – 20,732) 0.0 – 18.5 -10.4 to 14.5

Pine 38 (0 – 190) 1,020 (0 – 19,251) 0.8 – 18.5 -3.0 to 11.9

Oak 23 (0 – 130) 1,228 (0 – 8,391) 2.1 – 16.6 -10.4 to 14.5

Other Hardwoods 1 (0 – 40) 2,368 (0 – 7,404) 1.4 – 15.9 -9.2 to 13.9

Overstory Understory Competitors

Basal Area 

Mean (Range) 

(ft2

/ac)

Density Mean 

(Range) 

(TPA)

Height 

Range 

(ft)

Relative Height of Tallest 

Competitor Range 

(ft)

Figure 2.—Density of pine reproduction by site preparation 

treatment. Error bars represent 1 standard deviation. 

Mechanical scarifi cation treatments were applied as needed, 

rather than uniformly, across the stand. There was no 

signifi cant difference in pine density at the stand level by 

treatment.

Figure 3.—Basal diameter of pine reproduction at age 10 

yr based upon the pine’s crown class, height (ft) of its tallest 

competitor and 5,000 TPA competitors (all species) by 

overstory basal area (ft2

/ac). Dominant pine reproduction had 

twice the basal diameter of intermediate pine reproduction.

Density of Non-Pine Competitors

We also examined factors potentially affecting the density 

of non-pine competition around sampled pines. Density of 

non-pine competitors was related to overstory oak basal 

area and density of non-pine understory competition 

(other hardwoods for oak or oaks for other hardwoods) 

(Table 5). However, the models failed to account for much 

of the variance in the data, as indicated by the low R2

 values 

of 0.05 and 0.10. 
144

Table 5.—Linear models with growth of pine reproduction dependent upon crown class within the understory, overstory density, 

understory density, height of the tallest competitor and age; crown class within the understory dependent upon density of nonpine reproduction, pine reproduction, overstory basal area, age and height of the tallest competitor, and age; and density of 

understory competitors dependent upon overstory basal area and density of understory by species. There were 320 observations 

of each dependent variable.

1

Abbreviations: Age = number of growing seasons since regeneration treatment; BA = Basal area (ft2/ac); CompHt = height (ft) of the tallest 

competitor within the understory; Dom., Codom., Inter. = dominant, codominant, or intermediate pine within the understory, use 1 if true, 0 

otherwise; Int. = y-intercept; Over. = overstory; Oth. Hwd. = other hardwood tree species; and Repro = density of reproduction (TPA). 2

Parameter estimates differ from zero at the following alphas: † = <0.0001, ‡ = ≤0.001, * = ≤0.01, ¤ = ≤0.05, ’ = not signifi cant (>0.05). 3

Model: Y = β0 + β1X1 + β2X2 + ... + βiXi. 4

Model: P = (e^(β0 + β1X1 + β2X2 + ... + βiXi))/(1+ e^(β0 + β1X1 + β2X2 + ... + βiXi)).

 Parameter Estimates (X)1,2 Statistics

 Over. Total Comp. FDependant variable Int. Dom. Codom. Inter. BA Age Repro. Ht value R2

β0 β1 β2 β3 β4 β5 β6 β7

Pine Basal Diameter3 -0.055’ 1.078† 0.658† 0.246† -0.002* 0.019* -0.000’ 0.052† 39† 0.46

Pine Height3

 -0.006’ 4.505† 2.957† 1.067† -0.012† 0.091† 0.000’ 0.233† 40† 0.47

 Parameter Estimates (X)1,2 Statistics

 Non-Pine Pine

Dependant variable Int. Repro. Repro. Over. BA Age Comp. Ht Chi-Square

β0 β1 β2 β3 β4 β5

Probability of a Given Pine

 Being Dom./Codom.4

 2.8228† -0.0005† 0.0002¤ -0.0236† 0.0980’ -0.2378† 105†

 Parameter Estimates (X)1,2 Statistics

 Oak Oth. Hwd. Pine Pine Oak Oth. Hwd. FDependant Variable Int. BA Age BA BA Repro. Repro. Repro. value R2

β0 β1 β2 β3 β4 β5 β6 β7

Density of Oak 

 and Oth. Hwd. 3750.5† -19.75‡ 67.25’ 0.623’ -0.575’ -0.136¤ 3* 0.05

Density of Oak 2004.3† -10.12† -5.333’ -0.074’ -0.182† 9† 0.10

Density of Oth. Hwd. 2793.1† -14.88¤ 77.86¤ -0.101’ -0.419† 9† 0.10

DISCUSSION

Shortleaf pine-upland oak mixtures occur naturally in 

Missouri, but foresters would like to better understand 

the stand dynamics in order to more predictably achieve 

these mixtures. While stand-wide regeneration events are 

natural—the tornado near Poplar Bluff being an excellent 

example—widespread and chronic oak decline has provided 

an opportunity to study regeneration and growth of shortleaf 

pine under a thinned canopy. Our results show that given 

these stand structures, overstory retention results in slowed 

shortleaf pine growth.

Both mechanical scarifi cation and prescribed burning 

increased pine reproduction densities to levels similar to 

stands that had adequately reproduction stocking without 

treatment. Scarifi cation is more practical than burning in 

small stands or when there are smoke management issues. 

Scarifi cation treatments by skilled operators may cause less 

damage to crop oak trees than prescribed fi re, particularly 

in stands that have not been burned for decades. Prescribed 

fi res can cover large areas in a day or two, and proper 

timing and fi re techniques aid in reducing or increasing oak 

reproduction (Dey and Hartman 2005, Van Lear et al. 2000).

Overstory densities must be kept low to recruit seedlings, 

especially shortleaf pine (Larsen et al. 1997, Baker 1992, 

Liming 1945). Shortleaf pine seedlings are moderately 

shade tolerant, but become shade intolerant with age (Baker 

1992). Thus, if shortleaf pine is being recruited, then the 
145

mature overstory basal area should be kept low during 

seedling establishment and even lower after establishment to 

promote maximum reproduction height growth (Fig. 5).

In addition to reductions to overstory density, periodic 

releases have long been recognized as key to reliably 

recruiting shortleaf pine among oak reproduction (Brickman 

and Smith 1969, Baker 1992, Liming and Seizert 1943). 

Our data suggest that recruiting pine under a thinned canopy 

requires a commitment to periodic release from oak and 

other hardwood reproduction, particularly where there is a 

high density of hardwood competition (Fig. 5). While oaks 

also grow best in the open, they are more shade tolerant 

than shortleaf pine. Even under low overstory stocking 

levels, a high density of oaks in the reproduction cohort can 

greatly reduce the likelihood that pine reproduction will 

successfully compete for growing space and grow into the 

overstory. 

ACKNOWLEDGMENTS

The USDA Forest Service’s Mark Twain National Forest 

and North Central Research Station, and Missouri 

Department of Conservation Resource Science Division 

funded this project. Thank you to Eli Engelken and Mark 

Peeper for data collection.

Figure 4.—Height (ft) of pine reproduction at age 10 yr 

based upon the pine’s crown class, height (ft) of its tallest 

competitor, and 5,000 TPA competitors (all species) by 

overstory basal area (ft2

/ac). 

Figure 5.—Probability of a given pine being dominant/

codominant for a given understory density (TPA) by 

overstory basal area (ft2

/ac). There is a 50 percent probability 

of a given pine being dominant/codominant with 2,000 TPA 

mixed-species reproduction at 70 ft2

/ac basal area and with 

6,000 TPA mixed-species reproduction at 10 ft2

/ac basal 

area.

LITERATURE CITED

Baker, J.B. 1992. Natural regeneration of shortleaf pine. 

In: Brissette, John C.; Barnett, James P., comps. 

Proceedings of shortleaf pine regeneration workshop; 

1991 October 29-31; Little Rock, AR. Gen. Tech. 

Rep. SO-090. New Orleans, LA: U.S. Department of 

Agriculture, Forest Service, Southern Research Station: 

102-112.

Brinkman, K.A.; Smith, R.C. 1969. Managing shortleaf 

pine in Missouri. Station Bull. No. 875. Columbia, 

MO: Agricultural Experiment Station, University of 

Missouri. 35 p.

Burnham, K.P.; Anderson, D.R. 2003. Model selection and 

multimodel Inference: a practical information-theoretic 

approach. New York, NY: Springer. 488 p.

Dey, D.C.; Hartman, G. 2005. Returning fi re to Ozark 

Highland forest ecosystems: Effects on advance 

regeneration. Forest Ecology and Management. 217: 

37-53.
146

Dickson, J.G.; Thompson, F.R., III; Connor, R.N.; Franzreb, 

K.E.. 1995. Silviculture in central and southeastern 

oak-pine forests. In: Ecology and Management of 

Neotropical Migratory Birds – a synthesis and review 

of critical issues. New York, NY: Oxford University 

Press. 489 p.

Haney, G.P. 1962. Seedbed scarifi cation aids regeneration of 

shortleaf pine. Journal of Forestry. 60(6): 400-402.

Larsen, D.R.; Metzger, M.A.; Johnson, P.S. 1997. Oak 

regeneration and overstory density in the Missouri 

Ozarks. Canadian Journal of Forest Research. 27: 

869-875.

Liming, F.G.; Seizert, B.F. 1943. Relative height growth of 

planted shortleaf pine and cut-back and uncut hardwood 

reproduction after release. Journal of Forestry. 41(3): 

214-216.

Liming, F.G. 1945. Natural regeneration of shortleaf pine 

in the Missouri Ozarks. Journal of Forestry. 43(5): 

339-345.

Mitchell, K. 2001. [Revised June 2005]. Quantitative 

analysis by the point-centered quarter method. William 

Smith’s, NY: Hobart and William Smith College, 

Department of Mathematics and Computer Science,. 

http://people.hws.edu/mitchell/PCQM.pdf.

Nelson, N.W. 2005. The Terrestrial natural communities of 

Missouri. Jefferson City, MO: Missouri Department of 

Natural Resources. 550 p.

Nigh, T.A.; Schroeder, W.A. 2002. Atlas of Missouri 

ecoregions. Jefferson City, MO: Missouri Department 

of Conservation. 212 p.

Rogers, Robert. 1982. Guides for thinning shortleaf pine. In: 

Jones, Earle P., Jr., ed. Proceedings of the 2nd Biennial 

Southern Silvicultural Research Conference; 1982 

November 4-5; Atlanta, GA. Gen. Tech. Rep. SE-24. 

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

Service, Southeastern Research Station: 217-225.

SAS. 2003. Getting started with SAS version 9. SAS 

Institute Incorporated. Cary, NC: SAS Institute.

Starkey, D.A.; Oak, S.W; Ryan, G.W.; Tainter, F.H.; 

Redmond, C.; Brown, H.D. 1989. Evaluation of oak 

decline areas in the south. Protection Rep. RB-PR 17. 

Atlanta, GA: U.S. Department of Agriculture, Forest 

Service, Southern Region.

Van Lear, D.H; Brose, P.H.; Keyser, P.D. 2000. Using 

prescribed fi re to regenerate oaks. In: Yaussy, D.A., ed. 

Proceedings: workshop on fi re, people, and the central 

hardwoods landscape; 2000 March 12-14; Richmond, 

KY. Gen. Tech. Rep. NE-274. Newton Square, PA: U.S. 

Department of Agriculture, Forest Service, Northeastern 

Research Station: 97-102.

Wendland, W.M.; Kunkel, K.E.; Conner, G.; Decker, 

W.L.; Hillaker, H. Naber-Knox, P.; Nurnberger, F.V.; 

Rogers, J.; Scheeringa, K.; Zandlo, J. 1992. Mean 

1961-1990 temperature and precipitation over the 

Upper Midwest. Research Report 92-01. State Water 

Survey Miscellaneous Publication 136. Champaign, IL: 

Midwest Climate Center.

Woodward, S.; Stenlid, J.; Karjalainen, R.; Hutterman, A., 

eds. 1988. Heterobasidion annosum: Biology, ecology, 

impact, and control. New York, NY: CABI. 589 p.
147

SHORTLEAF PINE SEEDLING PRODUCTION AND SEEDING TRENDS IN MISSOURI

David Gwaze, Greg Hoss, and Dena Biram1

ABSTRACT.—The Missouri Department of Conservation operates the only nursery that 

supplies bare-root shortleaf pine seedlings in Missouri. Seedlings and seed have been sold 

to landowners since 1935. Prior to 1981 most seed was locally collected wild seed, some was 

purchased from neighboring states. After 1981, most of the seed for artifi cial regeneration was 

improved orchard seed. The highest production of shortleaf pine seedlings occurred prior to 

1987 with at least 2 million seedlings being produced annually. Today less than half a million 

seedlings are produced at the nursery. Before 1990 most of the seedlings were delivered to the 

Mark Twain National Forest, but now it is a minor player in artifi cial regeneration of shortleaf 

pine. Trends in seed distributed for direct seeding followed those of seedling production. 

This paper discusses factors that infl uenced the trends in shortleaf pine seed distribution and 

seedling production, and makes suggestions for future direction.

1

Resource Scientist (DG), Missouri Department of Conservation, 

1110 S. College Avenue, Columbia, MO 65201; Nursery Supervisor 

(GH) and Computer Operator (DB), Missouri Department of 

Conservation, 14027 Shafer Road, Licking, MO 65542. DG is 

corresponding author: to contact call (573) 882-9909 ext. 3320 or 

email at David.Gwaze@mdc.mo.gov

INTRODUCTION

George O. White Nursery, which is operated by the Missouri 

Department of Conservation (MDC), is the only nursery 

that produces bareroot shortleaf pine for use by private 

landowners and state and federal agencies. This nursery was 

owned and operated by the U.S. Forest Service from 1935 to 

1946 with assistance from the Civilian Conservation Corps 

(CCC) employees. The goal of the nursery in its inception 

was to grow shortleaf pine seedlings for reforestation efforts 

at the Clark and Mark Twain National Forests, to ensure 

continuous supply of timber production. In 1947 the nursery 

was leased to MDC by the U.S. Forest Service; in 1976, 

MDC obtained ownership of the site (Mugford 1984). The 

nursery currently occupies about 748 acres of which 50 

acres are a seedbed production area.

Shortleaf pine seedlings and seed have been sold to 

landowners to improve habitat, increase biodiversity and 

produce timber since 1935. From 1935 to 1981 most 

shortleaf pine seed was locally collected wild seed or 

purchased from neighboring states, particularly Arkansas. 

After 1981, most of the seed for artifi cial regeneration 

came from a grafted seed orchard established in Mt. Ida, 

AR, using Missouri superior trees. Today all planting and 

seeding needs in Missouri are being met from genetically 

improved seed collected from this grafted seed orchard.

All shortleaf pine seedlings produced at the George O. 

White nursery are 1-year-old bareroot seedlings. Shortleaf 

pine is stratifi ed and sown in nursery beds in spring. Seed 

for direct seeding is stratifi ed, repellent-coated, and sown 

in late March or early April. Seed germination will begin 

about 4 weeks after sowing as temperature and moisture 

conditions become favorable. 

The objective of this study is to summarize trends in 

shortleaf pine seedling production and seeding in Missouri.

SEEDLING PRODUCTION

At least 2 million shortleaf pine seedlings were produced 

each year at the George O. White Nursery from 1960 to 

1987, except in 1977 and 1984 (Figure 1). The highest seed 

production was between 1963 and 1966, when at least 

6 million seedlings were produced each year, reaching a 

peak of nearly 9 million seedlings in 1965. After 1987, 

seedling production decreased exponentially to about 

400,000 seedlings in 2005. Since 1990 annual seedling 

production levels have stayed below 1 million, where they 

remain to this day. This more recent production fi gure is 

well below the 45-year long-term average annual seedling 

production of 2.7 million.

Seedling Distribution by Land Owner Group

Federal 

Although the Mark Twain National Forest (MTNF) owns 

only 9.9 percent of Missouri’s forest land, most of the 

shortleaf pine seedlings produced by the George O. White 

Nursery were delivered to MTNF from 1960 to 1989 

(Figure 2). The biggest orders from MTNF were in the 

1960s, particularly from 1963 to 1968, when between 2.5 

million and 5 million seedlings were delivered annually. 

The second biggest orders were in the early 1980s, when 

4.4 million were delivered in 1980 and 2.5 million in 1985. 
148

Figure 1.—Number of shortleaf pine seedlings produced at the George O. White Nursery 1960-2005.

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

8,000,000

9,000,000

10,000,000

Number of seedlings

1960 1970 1980 1990 2000 2005

Figure 2.—Number of shortleaf pine seedlings distributed by the George O. White Nursery by ownership group 1960-2005. 

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Number of seedlings

Federal

Private

←State

←

←
149

After 1985, the seedlings ordered by MTNF never exceeded 

1 million, and since 1990 the orders have remained below 

0.2 million. Since 1990, MTNF has been a minor player in 

artifi cial regeneration of shortleaf pine. In 2005, it ordered 

only 46,000 seedlings, representing a dramatic drop in 

shortleaf pine planting from the 1 to 2 million seedlings 

planted annually during the 1980s. 

Several factors profoundly infl uenced the trend in shortleaf 

pine seedling demand by MTNF. Changes in policies by 

the Federal government caused less demand for seedlings 

from MTNF. In the early 1990s, the U.S. Forest Service 

adopted the concept of ecosystem management, which 

called for a reduction in the practice of clearcutting. As a 

result, timber harvesting practices on the National Forests 

shifted to favor methods using natural regeneration, such as 

seed tree, shelterwood, and uneven-aged management. This 

policy shift led to less timber harvesting and dramatically 

reduced artifi cial regeneration. In general, fewer old fi elds 

were purchased after the 1980s, which also meant fewer 

plantings. The new initiatives such as the Healthy Forest 

Initiative are unlikely to greatly accelerate seedling and 

seed demand on MTNF. The 2005 Forest Plan, however, 

emphasizes restoration and enhancement of natural 

communities, and an increase in pine planting will be 

required to restore shortleaf pine in parts of its former range. 

Private Landowners 

Generally, private landowners ordered the second largest 

quantity of seedlings, particularly prior to 1990 (Fig. 2), 

but there were a number of years in this period when their 

orders surpassed those from MTNF. Since 1990, private 

landowners have taken the lead, but the amount ordered 

has dropped sharply. The biggest order from private 

landowners was in 1983 when 4 million were ordered, and 

between 1960 and 1970, they consistently ordered more 

than 1 million seedlings per year. Since 1987, the private 

landowners never ordered more than 1 million seedlings in 

any year, and more recently they have ordered less than 0.5 

million have been ordered annually. 

Shortleaf pine seedling distribution to private landowners 

has been a response to major federal planting programs. 

The major federal program that assisted with tree planning 

from the 1970s to the present were the Forestry Incentive 

Program (FIP) and Forestland Enhancement Program 

(FLEP). FIP was originally authorized in 1978 to share 

up to 65 percent of the costs of tree planting, timber stand 

improvements, and related practices on nonindustrial private 

forest lands, and was terminated in 2002. FLEP replaced FIP 

in 2002 and its objective is to provide educational, technical, 

and fi nancial assistance to help private forest landowners 

implement their sustainable forestry management objectives. 

The maximum FLEP cost-share payment for any practice 

may be up to 75 percent. Despite the existence of these 

federal programs, demand for shortleaf pine seedlings by the 

private landowners continues to decrease perhaps because of 

the limited markets for shortleaf pine products in Missouri. 

With 85 percent of the forest lands in Missouri in private 

landowners’ hands, efforts should be made to identify 

solutions for increasing shortleaf pine seedling demand by 

the private landowners.

State 

Finally, the smallest number of seedlings was distributed 

to MDC (Fig. 2). The seedlings delivered to MDC never 

exceeded 1 million in any year, and only exceed 0.5 million 

in 1963. The small amount of seedlings distributed to MDC 

could be due to the fact that the state only owns 3 percemt 

of the forested lands in Missouri. 

In 2005, 59 percent of the seedlings were delivered to the 

MDC, 29 percent to private landowners and 12 percent 

to federal government (Fig. 3). That year was the fi rst 

time MDC had ordered more seedlings than the federal 

government and the private landowners.

DIRECT SEEDING

Direct seeding received a lot of attention during the 1960s 

and 1970s, and peaked between 1960 and 1964 when 4,500 

pounds of seed was distributed for direct seeding by the 

George O. White Nursery (Fig. 4). The largest amount of 

seed for direct seeding in a single year was 1200 pounds, 

which was delivered to MTNF in 1963. Seed distributed 

for direct seeding decreased during the 1980s and 1990s. 

The relatively large amount of seed distributed between 

1995 and 1999 was due to aerial seed requirements for the 

Eminence District of MDC in 1997. 

The reduction in demand of seeds for direct seeding at the 

MTNF could be attributed partly to reduction in the practice 

of clearcutting and the diffi culty in using herbicides. The 

reduction in demand for seeds for direct seeding by the 

private landowners may be attributed to shrinking markets 

for shortleaf pine timber products.

Federal

State

Private

Figure 3.—-Seedling purchase by land owner group in 2005.
150

SEED SUPPLY AND REQUIREMENTS

Most of the seed collected between the 1960s and early 

1980s was collected in Missouri by local contract pickers. 

Some seed was obtained from other states such as Arkansas 

(e. g. Arkansas Forestry Commission, Ouachita National 

Forest, and Ozark National Forest), Oklahoma and 

Louisiana. Seed collections by the U.S. Forest Service for 

operational planting in Missouri date back to 1967 when 

unimproved seed was collected from Ozark National Forest, 

AR and given to MDC for storage (Table 1). 

Beginning in 1981, improved seed was used mostly for 

artifi cial regeneration of shortleaf pine. The improved seed 

came from an 85-acre clonal seed orchard, located on the 

Womble Ranger District of the Ouachita National Forest, 

Mount Ida, AR. This seed orchard was established using 50 

superior trees selected from the MTNF. These trees were 

grafted into a clonal seed orchard between 1969 and 1971. 

Seed was fi rst collected from the Mt. Ida orchard in 1981, 

when 215 pounds were collected. A total of 1,578 pounds 

were harvested in 1983. After this second collection, there 

was an ample supply of seed in storage and a decision was 

made to collect only when there was a good seed crop. The 

third collection was made in 1986, when a massive 2,554 

pounds were collected. The bumper harvest in 1986 is 

attributed partly to the use of pesticides and fertilizers. After 

this large harvest, no cones were picked from the orchard 

until 2003. In 2003, 1,500 pounds of seed were collected. 

This harvest was attributed partly to favorable weather 

conditions and partly to the thinning and rouging carried out 

in 2000. The only improved seed not collected from the seed 

0

1,000

2,000

3,000

4,000

5,000

1960-4

1965-9

1970-4

1975-9

1980-4

1985-9

1990-4

1995-9

2000-4

Years

Seed used (pounds)

orchard in Mt. Ida was supplied by the Arkansas Forestry 

Commission in 1986 and 1987.

Currently, all planting and seeding needs in Missouri are 

being met from genetically improved seed collected from 

the grafted seed orchard in Mt. Ida. The State of Missouri 

has used 34 to 80 pounds of seed for planting and 0-109 

pounds for seeding per year over the past 8 years (Fig. 5). 

Seed requirements for direct seeding fl uctuate greatly while 

seedling production needs are more stable. Thus, average 

annual seed requirements are approximately 100 pounds for 

both direct seeding and seedling production. Based on this 

seed requirement fi gure, MTNF and Missouri Department 

of Conservation in combination have about a 30-year supply 

of shortleaf seed available for future afforestation needs. 

Storing shortleaf pine for 30 years should not present any 

problems as shortleaf pine is known to store well for up to 

35 years (Wakeley and Barnett 1968). However, recent tests 

in Arkansas have shown that viability decreases rapidly 

after 10 years of storage (Barbara Crane, USDA Regional 

Geneticist, pers. comm.).

OUTLOOK

Restoring shortleaf pine throughout its native range in the 

Ozark Highlands is a top priority in Missouri. Restoring 

shortleaf pine on former pine and oak-pine sites is a 

long-term strategy for mitigating chronic oak decline 

(Law et al. 2004). To restore the ecological and economic 

importance of shortleaf pine, several restoration efforts were 

established, including the U.S. Forest Service Pine Knot 

Figure 4.—Shortleaf pine seed distributed by the George O. White Nursery for direct seeding, 1960-2005. 
151

*Genetically improved seed

Table 1.—Details of seed collections for shortleaf pine restoration in Missouri. All seed was stored at George O. White State 

Nursery except for the 2003 collection, which is stored in Watersmeet, MI.

Seed source Year of collection Lot Number Amount (pounds)

Ozark National Forest, AR 1967 MT617 842

Northwest Arkansas, AR 1972 MT618 400

Mark Twain National Forest, MO 1975 MT613 49

Ouachita National Forest, AR 1975 - 941

Mark Twain National Forest, MO 1979 MT614 1793

Seed Orchard, Mt Ida, AR* 1981 MT619 215

Seed Orchard, Mt Ida, AR* 1983 MT621 1578

Arkansas Forestry Commission, AR 1984 - 110

Seed Orchard, Mt Ida, AR* 1986 MT625 2554

Arkansas Forestry Commission, AR* 1986 - 350

Arkansas Forestry Commission, AR* 1987 - 510

Missouri Department of Conservation, MO 1995 - 43

Unknown supplier, MO 1997 - 31

Louisiana Forest Seed Company, LA 1997 - 48

Seed Orchard, Mt Ida, AR* 2003 - 1500

0

20

40

60

80

100

120

1996

1998

2000

2002

2004

Year

Seed used per year (pounds)

Plant

Seeded

Figure 5.—-Trend in the amount of seed used for seeding 

and planting, 1996 to 2004.

restoration project, and MDC’s Peck Ranch Conservation 

Area (CA), Birch CA, Rocky Creek CA and Sunklands CA, 

restoration projects. More restoration projects are expected 

to be developed. These projects will increase the demand 

for shortleaf pine seedlings and seed for direct seeding. The 

demand is likely to increase because natural regeneration 

in most cases is inadequate. Moreover, the increased 

concern about global warming could prompt a major 

federally funded restoration program, thereby increasing 

demand for seeds and seedlings. The seedling production 

and seed demand for direct seeding are expected not come 

anywhere near the pre-1990s however, because 1) current 

policies have shifted from timber production to ecosystem 

restoration; 2) clearcutting and use of herbicides have been 

signifi cantly reduced on MTNF; and 3) markets for shortleaf 

pine are weak. 

We propose the following options to ensure seedling and 

seed demand for shortleaf pine are maintained or increased 

in the future:

• Develop markets for shortleaf pine and small 

diameter hardwoods. As markets are developed, 

demand for shortleaf seedlings by the private 

landowners is likely to greatly increase. Small 

increases in demand for seedlings will be expected 

from public agencies given their increased emphasis 

on forest values other than timber production.

• Educate the private landowners who own the bulk 

of the forested lands in Missouri about the benefi ts 

of shortleaf pine restoration. The public should be 

provided with 1) a simple defi nition of what shortleaf 

pine restoration is; and 2) a demonstration of the 

economic and ecological viability of shortleaf pine 

restoration, including aesthetics.
152

• Every effort should be made to make seed available 

to those who want to regenerate shortleaf pine 

by direct seeding. Direct seeding is desirable for 

landowners and resource managers who prefer lowcost artifi cial regeneration methods.

• We highly recommend that two shortleaf pine seed 

orchards be established, one close to the George O. 

White State Nursery in Licking and the other on the 

MTNF using existing surplus seed from controlled 

crosses. This will ensure that all seed needs are met 

from seed orchards in Missouri. In addition, if the 

current second–generation seed orchard established 

the George O. White State Nursery in Licking in 

2002 is destroyed by fi re or drought, an alternative 

seed supply of improved seed will be available.

LITERATURE CITED

Law, J.R.; Melick, R.; Studyvin, C.; Steinman, J.R. 2004. 

Oak decline in Missouri: History revisited. In: Spetich, 

M.A., ed. Upland oak ecology symposium: history, 

current conditions, and sustainability. Gen. Tech. 

Rep. SRS-73. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research Station: 

257-258.

Mugford, D.G. 1984. The nurseryman’s manual. Missouri 

Department of Conservation. 70 p.

Wakeley, P.C.; Barnett, J.P. 1968. Viability of slash and 

shortleaf pine seed stored for 35 years. Journal of 

Forestry. 66: 840-841.
153

THE STATE OF MIXED SHORTLEAF PINE-UPLAND OAK MANAGEMENT IN MISSOURI

Elizabeth M. Blizzard, David R. Larsen, Daniel C. Dey, John M. Kabrick, and David Gwaze1

ABSTRACT.—Mixed shortleaf pine-upland oak stands allow fl exibility in type and timing of 

regeneration, release, and harvesting treatments for managers; provide unique wildlife and 

herbaceous community niches; and increase visual diversity. Most of the research to date 

focused on growing pure pine or oak stands, with little research on today’s need to grow 

pine-oak mixtures. Despite this lack of information, resourceful foresters are using various 

regeneration treatments in even- and uneven-aged stands to increase the density of shortleaf 

pine among oaks. In this paper, we discuss past and current regeneration treatments applied 

by Missouri Department of Conversation and USDA Forest Service foresters.

1

Graduate Research Assistant (EMB) and Professor (DRL), 

Department of Forestry, 203 Natural Resources Building, University 

of Missouri, Columbia, MO 65211; Research Forester (DCD and 

JMK), USDA Forest Service, Northern Research Station, 202 

Natural Resources Building, Columbia, MO 65211; and Resource 

Scientist (DPG), Missouri Department of Conservation Resource 

Science Center, 1110 South College Avenue Columbia, MO 65201. 

EMB is the corresponding author: to contact call (573) 882-7242 or 

email at embvf2@mizzou.edu

INTRODUCTION

Mixed species forests are common in the Missouri Ozarks 

and there is increasing interest in regenerating mixed stands 

of shortleaf pine (Pinus echinata P. Mill.) and upland oak 

(white oak, Quercus alba L.; black oak, Q. velutina Lam. 

and scarlet oak, Q. coccinea Muenchh.). Mixed pine-oak 

stands are used by neotropical migratory birds, game 

animals and other fauna and may be managed to promote 

a rich herbaceous layer (Dickson et al. 1995, Nelson 

2005). Restoring pine-oak mixes may be an alternative to 

maintaining oak-dominated stands suffering from chronic 

oak decline (Law et al. 2004). In declining oak stands, 

merchantable scarlet and black oaks, which are at high risk 

of dying, can be harvested, leaving white oak, shortleaf 

pine and some younger scarlet and black oaks. Much of the 

land area affected by chronic oak decline is within shortleaf 

pine’s native range (Nigh and Schroeder 2002). These 

salvage operations can be combined with treatments to 

regenerate shortleaf pine and restore pine-oak mixes to their 

historic importance in Missouri’s Ozarks. 

Little research has been conducted in Missouri on 

regenerating shortleaf pine under varying levels of 

understory competition and overstory density/composition 

that result from salvage cuts in oak decline stands. 

Hardwood competition reduces pine growth, and the shadeintolerant pine reproduction does poorly in heavy shade 

from the overstory (Brinkman and Smith 1969). Overstory 

composition may also affect light quantity and quality, as 

well as the presence of shortleaf pine seed sources. The 

existence of mature pine-oak stands, however, indicates that 

the two species are not incompatible.

Foresters have begun exploring regeneration methods 

in pine-oak and oak-pine combinations by modifying 

regeneration techniques traditionally used for pine or oak. 

Some foresters have had success, but no one has developed 

reliably consistent management practices for regenerating 

pine with hardwoods in natural stands. We surveyed 

Missouri Department of Conservation (MDC) and U.S. 

Forest Service (USFS) foresters to get an overview of how 

they were trying to regenerate shortleaf pine in hardwood 

dominated stands. The purpose of this paper is: 1) to present 

variations we observed in how foresters are regenerating a 

mixture of pine and oak forests; 2) to discuss the need to 

control hardwood competition in the regeneration layer; and 

3) to discuss the need to release shortleaf pine reproduction 

from the overstory. Results are presented based upon the 

order of activities in a typical stand.

METHODS

MDC and USFS foresters who had shortleaf pine on their 

areas or who worked with private landowners to regenerate 

shortleaf pine were asked to provide examples of mixed 

pine and oak stands to assess current pine-oak regeneration 

practices in Missouri. Stand history data were collected to 

document the management activities. Examples of recent 

reproduction (0- to 25-years-old) were easy to come by in 

some areas and non-existent in others. Where examples 

of recent regeneration were available, the regeneration 

techniques and release treatments were recorded. Then 

the foresters were asked what they would prescribe 

next. Mature stands provided an opportunity to discuss 

regeneration cuts and options for seedling establishment. 
154

RESULTS

Pine and Oak Mixtures

Pine-oak mixtures generally occur as even-aged stands or 

as two-aged stands where oaks grew into a pine stand. In 

some stands, pines grew into large gaps within oak stands. 

The ridges and sideslopes near Buzzards’ Roost Cave on 

the Big Piney River in northern Texas County are examples 

of variation in spatial distribution. Pines and oaks occur as 

small groups of single species and as more even mixtures 

(Fig. 1). 

Regeneration Cuts

Regeneration cuts applied to regenerate shortleaf pineoak combinations include both even- and uneven-aged 

methods. The cuts include clearcut, typically with reserves; 

seedtree; shelterwood; and group selection. The range of 

regeneration cuts refl ects the variation in owner objectives 

and the impact of oak decline. The interest in maintaining 

continuous canopy cover in tourism corridors and centers 

and the extensiveness of oak decline are causing some 

foresters to use uneven-aged methods in pine-oak stands. 

Some research on uneven-aged management has taken place 

in the Ouachita Mountains of Arkansas. However, the sites 

differ greatly in geology and climate, and the stands are 

generally fi re-maintained woodlands with few oaks. Oaks 

are important economically and ecologically; therefore, 

research should be done to help foresters meet their goals of 

managing pine-oak combinations in uneven-aged cycles.

Site Preparation

Site preparation for pine-oak stands is not much different 

from that for pine stands as practiced in Missouri. Chainsaw 

felling is the most common site preparation practice. All 

stems above a given height, such as 4.5 ft, are removed to 

help prevent shading of the next generation. Burning and 

scarifying are used to allow pine seeds access to mineral 

Figure 1.—Variations in spatial distribution of pines and oaks on a ridge near Buzzards’ Roost Cave on the Big Piney River in 

northern Texas County. Pines and oaks occur both as single-species groups and as mixtures. Fall foliage helps to distinguish the 

hardwoods (light-colored foliage) and pines (dark-colored foliage).

soil. Burning removes most or all of the duff layer prior 

to seedfall. Scarifying disturbs the leaf and duff layers 

suffi ciently to incorporate fallen seed with bare mineral soil; 

thus, it is applied in the fall or winter after seedfall. Foliar 

herbicide is sometimes applied to retard hardwoods and 

other plants.

Shortleaf Pine Seedling Sources

Shortleaf pine seedlings come from three basic sources: onsite seedtrees, direct seeding, and planting. Ideally seedtrees 

are the best phenotype and genotype that grew in the 

previous generation on that site. Short of hand-pollinating 

the cones, there is little room for introduction of more 

disease-resistant trees. Seed for both direct seeding and 

planting came from superior trees located throughout what 

is now the Mark Twain National Forest (Fig. 2; Gwaze et 

al. 2005, Studyvin and Gwaze this volume). Some foresters 

prefer direct seeding, especially in very rocky soils. It can 

be expensive at over $100 per pound and often results in 

dense stands. Mixing the pine seed with native grass seed 

helps avoid overstocking the stands and provides additional 

habitat for early successional wildlife. Pine planting in 

mixed stands is commonly practiced at wider spacings than 

in a pure pine plantation, and like direct seeding, it is a way 

to restore genetic diversity to a stand. Both direct seeding 

and planting may be used to augment natural regeneration 

and speed up the process.

Release from Understory

Foresters regenerating pine-oak stands face the challenge 

caused by the rapid early growth of oak sprouts and the 

slower early growth of shortleaf pine. Competition from 

non-pine reproduction can dramatically slow growth of 

pine reproduction, thereby shifting the species mixture 

(Fig. 3). Most foresters follow regeneration cuts with 

chainsaw felling of residual trees, including understory 

stems. Some foresters also release clearcuts 3 to 5 years after 
155

Figure 2.—Superior trees once used for genetic improvement of Missouri’s shortleaf pine. Stands of planted and 

tagged superior trees like this one in the Willow Springs 

Ranger District can still be found on the Mark Twain 

National Forest.

regeneration, even in their pine-oak stands. Unfortunately, 

most foresters interviewed did not plan a second release 

treatment in canopy gaps. During this investigation we 

found that understory competition had unexpectedly 

overshadowed the pine seedlings in canopy gaps. An 

operational study by Doyle Henken (silviculturist, Mark 

Twain National Forest) confi rms that understory competition 

plays an important role in slowing pine growth (Blizzard 

et al. this volume). Canopy openings allow hardwood 

sprouts and other understory vegetation to take advantage of 

the direct sunlight and compete for growing space with pine 

reproduction. Foresters should consider releasing pines from 

competitors in the reproduction cohort at 3-5 years after 

regeneration, just as they do in clearcuts.

Release from Retained Overstory

Shortleaf pine has been known to remain in the 

midstory/understory for over 50 years. For instance, 

Stambaugh (2001) found a live, 55-year-old stem that 

was approximately 3 inches DBH. While this discovery 

shows that shortleaf pine can be somewhat persistent in 

the understory, this slow diameter growth may not be 

commercially sustainable. Studies are needed to determine 

how long pine reproduction can remain in the understory 

and still grow well after release from the overstory. 

A study under way on MDC’s Piedmont District by Jason 

Jensen examines underplanting (Jensen this volume). Figure 

4a shows a stand underplanted in 1998 and then clearcut 

less than a year later; and Fig. 4b shows a stand also planted 

in 1998, but under C-level stocking. The reproduction in the 

clearcut stand appears to have grown roughly twice as tall 

as the reproduction in the stand thinned to C-level stocking. 

This difference shows the dynamic impact of a partial 

canopy on shortleaf pine seedling growth. 

Figure 3.—Shade slows height growth of shortleaf pine.

Timber Stand Improvement

Release from competition continues in even-aged stands 

through the fi rst 20-25 years after regeneration. Chainsaw 

fellers are given decision rules to rank stems by species, 

form and spacing for target stand conditions. This thinning 

may shift the balance toward pine or retain more of a 

mixture of pine and oak. A typical species ranking is: 

shortleaf pine, white oaks and then red oaks. This ranking 

is used particularly in declining red oak stands that have a 

component of shortleaf pine, and shifts the mix towards the 

longer-lived shortleaf pine and white oak group.

CONCLUSION

All studies on shortleaf pine-upland oak must be evaluated 

based upon the starting condition of the stand as well as 

the moisture regimes, desired fi re regimes, and soils to 

determine how the stands and treatments fi t the conditions 

in a local area. Not all potential pine-oak sites are the 

same. Some pine-oak sites are currently fi re-maintained as 

early successional open woodlands, while others have not 

been burned recently, receive more rain, or have a higher 

proportion of non-oak hardwood sprouts. Both even- and 

uneven-aged regeneration cuts are being applied due to oak 
156

Figure 4.—Positive impact of overstory release on shortleaf 

pine growth underplanted in 1998 and clearcut within 1 year 

(a). Shortleaf pines appear to be over twice as tall as those 

planted under a C-level stocking (b). Both pictures were 

taken in late spring 2006.

4a

4b

decline and increased tourism. There are examples of 20- to 

25-year-old even-aged pine-oak stands in the Missouri 

Ozarks. Examples of 20-25 year-old uneven-aged pine-oak 

stands are less common, owing to past management trends 

and lack of information about the timing of applicable 

regeneration and release treatments. 

While shortleaf pine can remain alive in shade, the species 

is generally considered intolerant of shade and grows more 

vigorously in full sunlight. Release from both the overstory 

and the understory may be required to provide suffi cient 

sunlight. Studies are being developed and are underway to 

further understand the role that overstory and understory 

shade combinations play in shortleaf pine growth in mixed 

pine-oak stands. 

ACKNOWLEDGMENTS

Funding was provided by the Missouri Department of 

Conservation Resource Science Division in collaboration 

with the U.S. Forest Service North Central Research 

Station and the University of Missouri – Columbia 

Forestry Department. To all of the Missouri Department 

of Conservation and U.S. Forest Service foresters who 

participated in this management review: Thank you!

LITERATURE CITED

Blizzard, E.M.; Henken, D.; Kabrick, J.M.; Dey, D.C.; 

Larsen, D.R.; Gwaze, D.P. 2007. Shortleaf pine 

reproduction abundance and growth in pine-oak 

stands in the Missouri Ozarks. In: Shortleaf pine 

restoration and ecology in the Ozarks: proceedings 

of a symposium; 2006 November 7-9; Springfi eld, 

MO. Gen. Tech. Rep. Newtown Square, PA: U.S. 

Department of Agriculture, Forest Service, Northern 

Research Station.

Brinkman, K.A.; Smith, R.C. 1969. Managing Shortleaf 

Pine in Missouri. Stn. Bull. 875. Columbia, MO: 

Agricultural Experiment Station, University of 

Missouri. 35 p.

Dickson, J.G.; Thompson, F.R., III; Connor, R.N.; Franzreb, 

K.E. 1995. Silviculture in central and southeastern 

oak-pine forests. In: Ecology and management of 

neotropical migratory birds – a synthesis and review of 

critical issues. New York, NY: Oxford University Press. 

Gwaze, D.P.; Melick, R.; Studyvin, C.; Coggeshall, M.; 

2005. Genetic control of growth traits in shortleaf pine 

in Missouri. Southern Journal of Applied Forestry. 

29(4): 200-204.

Jensen, J. 2007. Underplanting shortleaf pine in the 

Missouri Ozarks. In: Shortleaf pine restoration and 

ecology in the Ozarks: proceedings of a symposium; 

2006 November 7-9; Springfi eld, MO. Gen. Tech. Rep. 

Newtown Square, PA: U.S. Department of Agriculture, 

Forest Service, Northern Research Station.

Law, J.R.; Melick, R.; Studyvin, C. and Steinman, J.R. 

2004. Oak decline in Missouri: History revisited. 

In: Spetich, M.A., ed. Proceedings, upland oak 

ecology symposium: history, current conditions, 

and sustainability; 2002 October 7-10; Fayetteville, 

AR. Gen. Tech. Rep. SRS-73. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, Southern 

Research Station: 257-258.
157

Nelson, N.W. 2005. The terrestrial natural communities of 

Missouri. Jefferson City, MO: Missouri Department of 

Natural Resources. 550 p.

Nigh, T.A.; Schroeder, W.A. 2002. Atlas of Missouri 

ecoregions. Jefferson City, MO: Missouri Department 

of Conservation. 212 p.

Stambaugh, M. C. 2001. Forest canopy gap dynamics in 

shortleaf pine forests of the ozark highlands. Columbia, 

MO: University of Missouri. 186 p. M.S. thesis.

Studyvin, C. and Gwaze, D. 2007. Genetic improvement of 

shortleaf pine on the Mark Twain, Ouchita and Ozark 

National Forests. In: Shortleaf pine restoration and 

ecology in the Ozarks: proceedings of a symposium; 

2006 November 7-9; Springfi eld, MO. Gen. Tech. Rep. 

Newtown Square, PA: U.S. Department of Agriculture, 

Forest Service, Northern Research Station.
158

PRODUCTIVITY OF PLANTED SHORTLEAF PINE 

IN ARTIFICIALLY COMPACTED CLARKSVILLE SOIL

Felix Ponder, Jr.1

ABSTRACT.—After 9 years, tree survival was 72, 65, and 70 percent for not compacted, 

medium compacted, and severely compacted treatments, respectively, for shortleaf pine (Pinus 

echinata Mill.) planted in a forest clearcut on the Carr Creek State Forest in Shannon County, 

Missouri. The study is in one of the USDA Forest Service’s Long-term Soil Productivity Sites to 

assess the effects of soil disturbance on site productivity across a range of forest sites. 

Both total height growth and diameter growth of shortleaf pine at breast height were markedly 

higher for compacted treatments than for treatments not compacted. Controlling understory 

vegetation also increased both tree height and diameter at breast height growth. Soil bulk 

density differences were signifi cant only for the 10-20 cm depth, which were 1.40 and 1.84 

g•cm3 for not compacted and compacted plots at the beginning of the study, were 1.32 

and 1.80 g/cm3

 for the same depth and treatments after 8 years. Results suggest that soil 

compaction associated with tree harvesting on this soil persisted at some depths for more 

than 5 years. Soil compaction benefi ted both survival and growth of shortleaf pine. Further 

discussion is warranted as to how soil physical properties associated with compaction are 

advantageous to shortleaf pine growth.

1

U.S. Forest Service, Northern Research Station, 208 Foster Hall, 

Lincoln University, Jefferson City, MO 65102; contact at: fponder@

fs.fed.us

INTRODUCTION

Compaction is perceived as one of the leading causes of soil 

degradation resulting from forest operations (Brais 2001, 

Froehlich 1988, Powers and others 1990). Soil compaction 

commonly reduces the growth of young trees that 

regenerate on sites following harvesting with ground-based 

machines (Greacen and Sands 1980). Tree susceptibility 

to compaction, however, has been shown to be speciesspecifi c (Wästerlund 1985, Mohering and Rawls 1970, 

Froehlich and others 1986, Corns 1988) and different soils 

compacted to the same degree may induce different growth 

responses (Wästerlund 1985, Powers 1999). For example, 

shoot and root weight of Douglas-fi r (Pseudotsuga menziesii 

var. gluca [Beissn.] Franco) and western white pine (Pinus 

monticola Dougl. Ex D. Don) seedlings were not affected 

by compaction after one growing season, but root volume 

was 41 percent less for the Douglas-fi r seedlings and 

seedling height was 6 percent greater for western white pine 

(Page-Dumerose and others 1998). Corns (1988) reported 

that lodgepole pine (P. contorta Dougl. var.) root weight, 

shoot weight, stem diameter, and stem height declined due 

to compaction on all four soils tested, yet white spruce 

[Picea glauca (Moench) Voss] growth on two of the soils 

did not decline but increased twofold. Wästerlund (1985) 

also reported species differences with Norway spruce 

[Picea abies (L.) Karst] growth being more impeded by 

compaction than Scotch pine (P. sylvestris L.) growth.

Once compacted, forest soils can remain compacted for 

decades (Froehlich and others 1985). Even in cold climates 

where freezing and thawing are assumed to loosen soil 

to considerable depths, the bulk density of compacted 

soil decreases slowly (Voorhees 1983, Corns 1988). The 

persistence of soil compaction over several decades has 

been shown to reduce the growth of Douglas-fi r for similar 

periods of time (Wert and Thomas 1981, Heninger and 

others 2002).

The effects of compaction in forest soils are not always 

associated with reduce tree growth. On several California 

sites, Gomez and others (2002) reported that compaction 

effects on 4-year-old ponderosa pines (Pinus ponderosa) 

varied with soil texture and soil water regime. Stem volume 

on compacted soils was less, the same, and higher on clayey, 

loamy, and sandy loam soils, respectively. Powers and 

others (2005) reported that soil compaction signifi cantly 

improved tree performance in 10-year-old Long-term Soil 

Productivity Study (LTSP) installations. Compaction was 

also found to be benefi cial to black spruce (Picea mariana

Mill.) and jack pine (Pinus banksiana Lamb.) growing on 

coarse-textured soils classifi ed as humo-feric podzols in 

northwestern Quebec (Brais 2001). Growth increases on 

these soils were linked to harvest traffi c compaction causing 

a more favorable pore-size distribution, which improved 

the balance between aeration porosity and available water 

holding, similar to the fi ndings by Gomez and others (2002). 

The effect of harvest traffi c on soils was described earlier 

by Hyder and Sneva (1956) and Rashid and Sheikh (1977). 
159

They concluded that compaction generally reduces the 

available water-holding capacity of fi ne-textured soils, but 

in coarse-textured soils, compaction can reduce the size of 

very large pores and increase water retention.

The LTSP, composed of large-scale fi eld experiments 

located at sites across the United States, was developed to 

assess the effects of soil compaction and surface organic 

matter removal on site productivity across a range of 

forest sites (Powers and others 1990). Similar projects 

on industry lands have also been developed. This paper 

examines (1) the effect of three levels of soil compaction 

on the 9-year growth of young planted shortleaf pine (Pinus 

echinata Mill.); and (2) soil bulk density 1 and 8 years after 

harvesting and site preparation in the Missouri LTSP.

MATERIALS AND METHODS

Site Description

The study was implemented in 1994 in the Ozark Region 

of southeastern Missouri on the Carr Creek State Forest in 

Shannon County, on northeastern aspects on sideslopes of 

two ridges. Before harvesting, the study site was occupied 

by a mature, second-growth oak-hickory forest with a site 

index ranging from 22.6 to 24.4 m based on black oak 

(Quercus velutina Lam.) at 50 years (Hahn 1991). Slopes 

of 20-28 percent are characteristic of the site. Soils are silt 

loams that developed from cherty residuum, primarily of 

the Clarksville series (loamy skeletal mixed mesic Typic 

Paleudults) (Gott 1975). 

Experimental Design

Main soil treatments (3 x 3 factorial design) were three 

levels of organic matter removal (boles-only removal, whole 

tree removal, and whole-tree plus forest fl oor removal) 

and three levels of compaction (none, moderate, and 

severe) applied to the soil surface. Main treatments were 

split in half to provide a weed versus no weed (herbicide) 

comparison. All treatments were replicated three times. 

The desired compaction level was achieved by driving 

over plots multiple times with a 14-ton vibrating sheepfoot roller. Logging debris and forest-fl oor material were 

removed before compaction so that mineral and organic 

components would not be mixed. Severe compaction was 

intended to approach 80 percent of the approximate growthlimiting bulk densities in the surface 10 cm of soil (Daddow 

and Warrington 1983). Moderate compaction levels were 

designed to come close to the midpoint between no and 

severe compaction. Soil bulk density measurements were 

taken after one, three, fi ve, and eight passes (Blake and 

Hartge 1986). Bulk density samples were collected from 

the 0-10, 10-20, and 20-30 cm depths. After mineral soil 

compaction was complete, forest fl oor and logging debris 

were returned, as needed, to achieve each plot treatment 

combination. Following treatment installation, 1-0 seedlings 

of red oak (Q. rubra L.), white oak (Q. alba L.), and 

shortleaf pine were planted in rows at a spacing of 3.66 m 

apart in and between rows at a ratio of three oaks of each 

oak species to one shortleaf pine. The oak to shortleaf pine 

ratio approximated the preharvest oak to shortleaf ratio. 

Complete description of the site and the LTSP installation 

are provided elsewhere (Ponder and Mikkelson 1995).

For this report, only shortleaf pine and the three levels of 

soil compaction with and without weed control were used. 

For the fi rst 2 years after planting, a 0.5-m-radius area 

around all seedlings was sprayed annually in the spring 

with a mixture of glyphosate and simazine to control weeds. 

Thereafter, weeds were controlled in only half of all plots. 

Post-harvest (after 8 years) bulk density measurements 

were collected from no and severe compaction treatments 

only, using the method described by Page-Dumroese and 

others (1999). Generally, Page-Dumroese and others (2006) 

reported that differences between the moderate and severe 

compaction levels have been small, if detectable at all, after 

5 years for LTSP installations. An irregularly shaped hole 

was carefully excavated to the desired soil depth. Soil from 

the hole was placed in zip-locked plastic freezer bags. Once 

excavated, the hole was fi lled with expanding polyurethane 

foam, and a plywood plate weighted with a rock was placed 

on the surface. The plate ensured that continued expansion 

of the foam would fi ll any irregularities in the hole. The 

foam was left to cure for at least 8 hours. The foam cast was 

then removed from the hole and returned to the laboratory 

where excess soil, small rocks, and roots were removed 

from the outside of the foam. Foam cast volume was 

determined by water displacement. 

Seedling survival, height, and diameter were measured after 

planting and annually thereafter. Diameter at 2.54 cm above 

the soil surface, which is not presented here, and diameter at 

breast height (DBH), when trees reached at least 1.4 m tall, 

were measured.

Statistical Analyses

The experiment was analyzed as a randomized complete 

block design. Survival was analyzed using the PROC 

LIFETEST procedure (Allison 1995). Growth and bulk 

density data were analyzed using analysis of variance with 

the PROC GLM procedures in SAS Version 8.2 (SAS 

Institute 1999). All statistical tests were performed at the 

α = 0.05 level of signifi cance. Because organic matter was 

removed prior to compaction, then returned to each plot, 

1- and 8-year bulk density results were assumed to be 

unaffected by organic matter removal treatments. Therefore, 

results from the different organic matter removal treatment 

plots were combined for each level of compaction.
160

RESULTS

Bulk Density

Eight years after applying compaction treatments, soil bulk 

densities for the 0- to 10- and the 20- to 30-cm depths did 

not differ (p = 0.0991 and p = 0.6202) between no and 

severe compaction. Compaction was only 5 and 14 percent 

higher than no compaction for the two depths (Table 1). 

But at 10 to 20 cm depth, average bulk densities for severe 

compaction were 24 percent higher (p = 0.0041) than for 

no compaction. Average bulk densities were not affected by 

weed control. 

Survival and Growth

After the fi rst 9 years following planting, survival of 

shortleaf pine averaged 70 percent (Table 2) and has not 

been affected by compaction or weed control treatments 

(p = 0.2781 and 0.1102). Most of the 30-percent mortality 

occurred during the fi rst growing season. 

Table 1 .—Average bulk density of a Clarksville cherty silt 

loam soil 9 years after soil compaction and weed control 

treatments. Standard deviations are in parentheses.

1

Mean of 12 samples.

2

Within the column, for each treatment and depth combination, 

values with the same letter are not signifi cantly different. 

Table 2. --Average survival, total height, and diameter at 

breast height (DBH) of shortleaf pine as affected by three 

levels of soil compaction and weed control, 9 years after 

planting.

1

In each column, within compaction and weed control levels, 

values followed by the same letters are not signifi cantly 

different according to Duncan Multiple Range test.

Treatment Depth Bulk density1

cm Mg/m3

Compaction

None 0-10 1.37(0.33)a2

Severe 0-10 1.60(0.28)a

p value 0.0991

Weed control

With 0-10 1.47(0.39)a

Without 0-10 1.49(0.25)a

p value 0.9967

Compaction

None 10-20 1.40(0.24)a

Severe 10-20 1.84(0.41)b

p value 0.0041

Weed control

With 10-20 1.71(0.48)a

Without 10-20 1.53(0.30)a

p value 0.1931

Compaction

None 20-30 1.70(0.44)a

Severe 20-30 1.79(0.40)a

p value 0.6202

Weed control

With 20-30 1.79(0.27)a

Without 20-30 1.70(0.53)a

p value 0.6085

Although bulk density for the moderate compaction level 

was not measured, total height and DBH were. Shortleaf 

pine in moderate and severe compaction plots averaged 

41 cm taller and 12 mm larger in diameter than trees in 

the no compaction treatment plots (Table 2). Total height 

growth and DBH differences between moderate and 

severe compaction were not signifi cant. Vegetation control 

increased both height and DBH (p = 0.0202 and p = 0.0001) 

compared to no vegetation control (Table 2). Interactions 

between vegetation control and compaction for total height 

growth and DBH were not signifi cant (p = 0.1009 and 

p = 0.5434).

DISCUSSION

Coarse fragments (rocks, stones, chert, etc.) and large roots 

make it extremely diffi cult to accurately determine bulk 

density on these soils. Bulk density measurements taken 

immediately after treatment application were accomplished 

using soil cores (30 cm in length x 9 cm in diameter) 

extracted from plots using a newly developed soil-coring 

device (Ponder and Alley 1997). A subset of the bulk density 

data showed that the compaction increased bulk density for 

the 0-10 cm depth approximately 8 percent (to 1.65 Mg/

m3

) for moderate treatments and approximately 15 percent 

(to 1.78 Mg/m3) for severe treatments. However, upon 

examination of the complete data set, it was discovered 

that the sampler introduced error during the coring 

process, causing an overestimation of bulk density (Lichter 

and Costello 1994). The magnitude of error cannot be 

determined because the sampler error was not discovered 

until several years later, by which time plots may have 

begun to recover from compaction. Although the error is 

now apparent, there is no reason to believe that levels of 

Treatment Survival Total height DBH

 Percent cm mm

Compaction

None 72a 586.3a1 96.5a

Medium 65a 613.7b 103.3b

Severe 70a 641.0b 112.9b

p value 0.2781 <0.0001 0.0019

Weed control

With 69a 632.9a 131.3a

Without 70a 603.5b 82.1b

p value 0.1102 <0.0202 0.0001
161

soil compaction based on earlier bulk density measurements 

were not achieved. Large-scale fi eld plots similar in size to 

those in the current study have been successfully compacted 

to different levels using ground-based equipment (PageDumroese and others 2006) with several years of vegetation 

development and measurements (Fleming and others 2006). 

The polyurethane foam method was used for remeasuring 

bulk density in year 8.

Once compacted, forest soils usually require several decades 

to recover to undisturbed levels of bulk density (Sands 

and others 1979, Tiarks and Haywood 1996). Recovery 

rates depend on many factors, including the frequency of 

harvest cycles, soil moisture conditions during harvest, soil 

texture, and rock-fragment content (Miller and others 1996, 

Williamson and Neilsen 2000, Liechty and others 2002). 

Natural soil processes such as swelling and shrinking due 

to moisture changes, movement of soil particles by freezing 

and thawing (including frost heave), and biological activity 

tend to restore soil physical properties to predisturbance 

conditions (NCASI 2004). Froehlich and McNabb (1984) 

described three criteria necessary for these processes to 

be effective: 1) the soil must be sensitive to the process; 

2) the climate must produce the temperature and moisture 

regimes necessary for the process to occur; and 3) the 

cycles or processes must occur with suffi cient frequency 

and duration. The extent of compaction, initial bulk density, 

depth of impact, and subsequent soil recovery are all factors 

that determine the consequences of timber harvesting or 

site preparation on productivity (Page-Dumroese and others 

2006). In the case of the present study, although some 

amelioration of initial treatment bulk density has probably 

occurred over time, the amount cannot be adequately 

measured because of errors in the initial measurements. Any 

future recovery should be detected in the next round of bulk 

density measurements.

 

Snow and ice damaged some trees during the winter 

of 2000-2001. Thirty-four trees (14, 9, and 12 trees 

respectively, in no, moderate, and severe compaction 

treatments) with crooked main stems, broken and deformed 

branches, and broken tops were removed in the summer 

of 2002. The number of trees damaged did not vary with 

compaction, but all except one of the trees removed were 

in the weed control plots. Apparently, the damage occurred 

when the build-up of snow and ice in tree crowns became 

greater than what trees could bear without bending. The 

duration of the snow and ice weight was suffi cient to cause 

breakage and permanent bending. Subsequently, when 

trees resumed springtime growth, new growth added to 

the already crooked stems, deforming them more. Trees 

receiving weed control were 29 cm taller and had more 

diameter growth (table 2) and their crowns were larger and 

could collect more snow and ice than smaller crowned trees 

in no weed control subplots. Hence, trees in no weed control 

subplots had very little damage.

The better shortleaf pine growth in the compacted treatments 

as compared to trees in the no compacted treatment is not 

completely understood. Compaction can alter the waterholding capacity of soils and has different effects depending 

on the texture of the soil. Compaction generally reduces 

the available water holding capacity of fi ne-textured soils; 

in coarse-textured soils, compaction can reduce the size of 

very large pores and increase water retention (Hyder and 

Sneva 1956, Rashid and Sheikh 1977). Shortleaf pine is a 

species that is found across a broad range of sites due to its 

tolerance of a wide range in soil conditions; however, it does 

best on soils with silt loam and fi ne sandy loam textures 

(Lawson 1992). The soil in this study was a silt loam 

(Clarksville cherty silt loam with ~ 40-70 percent angular 

fragments by volume < 15 cm in diameter). The impact of 

coarse fragments on properties of the Clarksville due to 

compaction is questionable. Once compacted, does it behave 

as a fi ne-textured or somewhat coarse-textured soil? Rock 

fragments alter the physical properties of soils in ways that 

can increase water availability. Surface and subsurface rock 

fragments can act as mulch, reducing evaporation from soils 

primarily in the upper 25 cm of the profi le (van Wesemael 

and others 1995). Soils containing signifi cant rock 

fragments have lower fi ne-earth water content in their top 

layer due to the small water retention capacity of stony soils 

(Childs and Flint 1990, van Wesemael and others 1995). 

Therefore, evaporation rates are lower in soils containing 

rock fragments compared with stone-free soils. The soil 

compaction process for the Missouri study pressed the rock 

fragments on the soil surface, which ranged from 30 to 50 

percent, into the upper soil layer, which already contains 15 

to 25 percent by volume chert fragments, greatly increasing 

rock fragment content in that soil layer. A 15-cm thick layer 

of rock fragment mulch reduced evaporation compared with 

a non-stony soil (van Wesemael and others 1995). 

In a greenhouse experiment using sieved Clarksville 

silt loam soil, shortleaf pine root growth was limited by 

compaction due to reduced aeration (Siegel-Issem and 

others 2005). Although the study demonstrated how 

shortleaf root growth is inhibited in the compacted sieved 

or the fi ne-earth fraction of the soil, it does not contribute 

to the understanding of how compaction of unsieved 

Clarksville soil, as in the present study, affects tree growth. 

Brais (2001) reported that the 5-year mean height of planted 

white spruce [Picea glauca (Moench) Voss] on fi ne textured 

soils free of coarse fragments in response to soil compaction 

due to skidding during timber harvesting was only 28 

percent higher in the between track areas and 25 percemt 

higher in the track areas than in undisturbed areas. But the 

relative productive rate of trees growing in between track 

areas (0.44 per year) was higher than that for trees growing 

in undisturbed areas (0.26 per year), while no signifi cant 

differences were found between undisturbed and wheel 

track areas. Moreover, vegetation competition rather than 

skid trail traffi c explained over 40 percent of the differences 

in total tree height and root collar diameter (Brais 2001).
162

Compaction has been shown to reduce vegetative 

competition and increase moisture availability at several 

LTSP locations and improve survival or growth (Powers 

and Fiddler 1997, Gomez and others 2002, Li and others 

2003, Page-Dumroese and others 2006). Compaction has 

also been found to increase growing-season soil temperature 

at many of the LTSP locations (Fleming and others 1999, 

Kranabetter and Chapman 1999, Page-Dumroese and 

others 2006). At the Missouri site, both average fi fth-year 

soil water and temperature were higher (14 and 16 percent, 

respectively), for the severe compacted treatment than 

for the no compaction treatment (Ponder 2004). Further 

differences in soil water and temperature were manifested 

by controlling weeds, which also affected growth. The 

greater height of trees in the absence of weeds compared 

to the presence of weeds can likely be attributed to better 

soil water because the no weed treatment had higher soil 

water. Five-year seasonal soil water content was 64 percent 

higher for no weed subplots than for subplots with weeds 

(Ponder 2004). The difference in mean 5-year seasonal soil 

water content for no weed subplots was 6 percent higher for 

severely compacted plots compared to plots not compacted 

and 34 percent higher for plots with weeds for plots severely 

compacted, compared to plots not compacted. Also, during 

the dry, hot season, soil temperatures at the Missouri site 

were higher in no weed subplots than in subplots with 

weeds (20.2  ̊C versus 13.4  ̊C, respectively). 

CONCLUSIONS

After 8 years, differences in bulk density were present 

for no compaction and severe compaction treatments for 

the 10-20 cm depth only. Weed control did not affect bulk 

density. After 9 years, neither soil compaction nor weed 

control affected shortleaf pine survival but both benefi ted 

growth. Growth differences attributed to compaction and 

weed control can generally be explained by the increase in 

soil water. Factors not measured may also be at work such 

as rooting depth, rooting pattern, and impact of compaction 

on the soil matrix to infl uence soil moisture availability. 

Nine years is a short time in the development of a Missouri 

shortleaf pine plantation and current rate of growth can 

change, especially as canopy expansion continues placing 

greater demand on soil water and nutrients. 

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165

AMOUNTS AND SPATIAL DISTRIBUTION OF DOWNED WOODY DEBRIS, SNAGS, 

WINDTHROW, AND FOREST FLOOR MASS WITHIN STREAMSIDE MANAGEMENT ZONES 

OCCURRING IN SHORTLEAF PINE STANDS FIVE YEARS AFTER HARVESTING

Hal Liechty1

1

Associate Professor (HOL), School of Forest Resources, University 

of Arkansas at Monticello, P.O. Box 3468, Monticello, AR 71656. To 

contact call (870) 460-1452 or email liechty@uamont.edu

EXTENDED ABSTRACT

Shortleaf pine (Pinus echinata Mill.) is a dominant tree 

species in pine and pine-hardwood forest communities 

located on ridges and upper- to mid-slope positions in the 

Ouachita Mountains. The stream reaches located in these 

stands fl ow infrequently and are classifi ed as ephemeral or 

intermittent, have low stream orders, and have relatively 

narrow channels and fl oodplains. Land management 

agencies, such as the Ouachita National Forest, typically 

establish buffers or streamside management zones (SMZs) 

along these streams to protect water quality and other 

riparian functions within as well as downstream of these 

reaches. Since channels and fl oodplains are narrow, SMZ 

width is also narrow along these headwater streams. Given 

the high edge-to-interior ratios of these riparian zones, I 

was interested in 1) how forest characteristics such as stand 

density, forest fl oor mass, and coarse wood debris (CWD) 

volumes differ between SMZs and adjacent upland locations 

in these stands; and 2) how forest harvesting outside SMZs 

affect tree density, forest fl oor mass, CWD volume, snag 

density, and windthrow density. 

Eleven shortleaf pine stands in the Ouachita National Forest 

in Arkansas were included in this study. They were between 

14 and 16 ha in size, mature with dominant tree ages >70 

years, and located on south- to west–facing slopes. In 1993 

three of the stands were clearcut and planted to loblolly 

pine, four of the stands were cut using a shelterwood 

reproductive harvest with the intent to retain 6.8 m2/ha of 

pine and 2.3 m2

/ha of hardwoods, and the other four stands 

were uncut and used for controls. Streams in these stands 

generally extended from the upper slopes of the stand to the 

bottom of the slope. Prior to the 1993 harvest, SMZs were 

established along each stream channel in each stand. Five 

years after harvesting, two to four plots were established 

within the SMZs of each stand. The plots spanned the 

entire width of a SMZ. In addition a plot was established 

adjacent to each of the SMZ plots in the upland portion of 

the uncut stands. Tree density, forest fl oor mass, and coarse 

woody debris (CWD) volumes were measured in the plots. 

Transects were located every 30 to 50 m along all SMZs in 

the stands. Each transect extended across the entire width of 

a given SMZ. Location and characteristics of each snag and 

windthrow within 10 m of each transect was recorded.

Total basal area was signifi cantly greater in the SMZs than 

in the upland portions of the uncut control stands (Table 1). 

Differences were due to the higher numbers of hardwoods 

in the SMZs plots than the upland plots. Although tree basal 

area was higher in the SMZs, forest fl oor mass in the uncut 

control stands was 23 percent greater in the upland portion 

of stands than in the riparian zones. These differences 

appear to refl ect a higher rate of decomposition in the SMZs 

due to the greater levels of hardwood litter or soil moisture 

within the riparian zones. CWD volumes were very similar 

in the upland and riparian areas of the stands.

Reproductive cutting methods had little infl uence on tree 

basal area or CWD volumes within the SMZs (Table 

2). Differences in living overstory and midstory basal 

area among cutting methods were generally less than 10 

percent. Mean CWD volume was nearly twice as high in 

the clearcuts compared to the uncut or shelterwood stands. 

Because of the high variability in CWD volumes and the 

potentially low power of these tests, however, differences 

among volumes were not signifi cant.

A total of 160 snags were located in the 5.6 ha of SMZs 

that were inventoried. Snags were equally distributed as 

pine and hardwoods. The average diameter at breast height 

(DBH) of the snags was 17.5 cm. Snag densities were 

signifi cantly lower in the SMZs that were located in the 

clearcut and shelterwood stands than in the uncut stands 

(Table 2). Harvesting forests can increase the wind speed, 

solar radiation, air temperature, and soil temperature in 

riparian zones (Moore and others 2005). This alteration 

in microclimate is likely responsible for an accelerated 

deterioration of snags and thus a reduction in snag density in 

the clearcut and shelterwood stands. The reduction in snag 

density was greatest in narrower SMZs. In the uncut stands, 

snag densities rapidly decreased with increasing SMZ 

widths up to 40 to 50 m. In the clearcut and shelterwood 

stands, however, snag density was not signifi cantly 

correlated with SMZ width. Although other studies have 

found increased mortality and snag recruitment along edges 

of harvested stands, this study indicated no increase but 

rather a decrease in snags during the fi rst 5 years following 

harvesting. 
166

Twelve windthrows were located in the SMZs. All but two 

of the windthrows occurred in the clearcut stands and only 

one of the windthrown trees was a hardwood. The average 

DBH of the windthrows was 25.8 cm, which was much 

larger than the average DBH of the snags. Windthrow 

densities were signifi cantly greater in the SMZs within the 

clearcut stands than in either of the other stand types (Table 

2). Alteration of the microclimate, especially windspeed, in 

the SMZs with clearcutting appears to have increased the 

windthrow susceptibility of large pine trees. In the clearcut 

stands, nine of the 10 windthrows were located in SMZs that 

had widths less than 29 m. The high edge-to-interior ratio 

of these narrow SMZs also appears to have an impact on 

windthrow occurrence with clearcutting.

These results suggest that land managers who wish to retain 

snags in SMZs located in upper- to mid-slope shortleaf 

pine stands, should minimize tree removal outside these 

riparian zones. To reduce windthrow of large pine trees, land 

managers should also refrain from clearcutting stands. Some 

evidence indicates that widening SMZs may also reduce 

snag deterioration and windthrow susceptibility in these 

SMZs following harvesting operations.

LITERATURE CITED

Moore, Dan R.; Spittlehouse, D.L.; Story, A. 2005. Riparian 

microclimate and stream temperature response to forest 

harvesting: a review. Journal of the American Water 

Resources Association. 41(4): 813-834.

Table 1.—Mean (standard deviation) living tree basal area, forest fl oor mass, CWD volume, and P-values associated with SMZs 

and upland plot comparisons in four uncut shortleaf pine stands in the Ouachita Mountains.

Stand Characteristic SMZ Upland P-Value

Tree basal area (m3/ha)

 Pine 22.4 (9.4) 22.2 6.2) 0.955

 Hardwood 11.8 (4.5) 7.6 (2.7) 0.006

 Total 34.2 (7.2) 29.8 (5.6) 0.092

Forest fl oor (kg/m3

) 2.2 (0.4) 2.7 (0.5) 0.049

CWD Volume (m3/ha) 8.9 (13.1) 9.3 (10.3) 0.922

Table 2.—Mean (stand deviation) living tree basal area, CWD volume, and snag density; median forest fl oor mass, median 

windthrow density, and P-values associated with the comparisons of SMZ 5 years following application of three reproductive 

shortleaf pine regeneration cutting methods in the Ouachita Mountains.

Stand Characteristic Uncut Shelterwood Clearcut P-Value

Tree basal area (m3/ha)

 Pine 20.8 (2.2) 19.5 (6.4) 18.8 (4.2) 0.661

 Hardwood 9.7 (1.6) 9.9 (2.6) 10.2 (1.6) 0.501

 Total 34.2 (2.1) 29.4 (5.7) 29.0 (3.3) 0.403

Forest fl oor (kg/m3) 2.2 2.4 2.7 0.422

CWD Volume (m3/ha) 8.9 (7.9) 7.6 (2.0) 16.1 (8.1) 0.331

Snags (#/ha) 38.9 (9.7) 22.7 (11.3) 25.7 (10.2) 0.014

Windthrow (#/ha) 0.3 0.0 11.8 0.020
167

WILDLIFE DIVERSITY OF RESTORED SHORTLEAF PINE–OAK WOODLANDS

 IN THE NORTHERN OZARKS

Corinne S. Mann and Andrew R. Forbes1

1

Ornithologist (ARF), Missouri Department of Conservation and 

Audubon Missouri, 2620 Forum Blvd., Suite C-1, Columbia, 

MO 65203; and Wildlife Intern (CSM), Missouri Department of 

Conservation, P.O. Box 180, Jefferson City, MO 65102. ARF is 

corresponding author: to contact call (573) 447-2249 or email at 

Andrew.Forbes@mdc.mo.gov

EXTENDED ABSTRACT

Historic changes in land use have altered the plant 

composition and structure of shortleaf pine-oak woodlands 

in the northern Ozarks. As a result, the composition of 

wildlife communities in these landscapes has shifted 

to species that are more associated with closed canopy 

oak forests. For example, the red-cockaded woodpecker 

(Picoides borealis) has been extirpated from much of 

its former range in the Ozarks, and the pine buck moth 

(Hemileuca maia) has declined in numbers, while other 

species associated with closed canopy forests have become 

more abundant. 

Managing tree density with silvicultural practices and 

recovering characteristic ground fl ora with prescribed fi res 

will restore habitat and result in a shift in the composition 

of wildlife species in pine-oak woodland communities. 

Landscape-scale habitat restoration is a major emphasis 

of Missouri’s Comprehensive Wildlife Conservation 

Strategy (CWS), which also focuses on preserving healthy 

landscapes. The goal of the CWS is to conserve all wildlife, 

which includes plants, animals, and natural communities. 

Central to the CWS are a statewide network of Conservation 

Opportunity Areas (COA), which have been identifi ed as the 

best landscapes in Missouri to focus on conservation of all 

wildlife. Shortleaf pine woodland restoration is an objective 

in several of the COAs in the Missouri Ozarks. The 

Current River Hills COA includes the forests, woodlands, 

glades, fens, and caves surrounding the Current and Jacks 

Fork Rivers. Once the site of Missouri’s most extensive 

shortleaf pine woodlands, the Eleven Point Hills COA lies 

in some of the most rugged and least developed portions 

of the Missouri Ozarks. Historically, pine-oak woodlands 

occupied high elevations in the North Fork COA, which 

today is dominated by dense second-growth forest with 

only scattered pine plantations. The success of our efforts 

to conserve all wildlife in these COAs can be assessed by 

monitoring for the suite of animal and plant species that 

require a healthy pine-woodland community for survival.

The restoration of shortleaf pine woodlands will benefi t 

many species of birds, including Partners in Flight Watchlist 

Species, such as red-headed woodpecker (Melanerpes 

erythrocephalus), Bachman’s sparrow (Aimophila 

aestivalis), and brown-headed Nuthatch (Sitta pussilla). 

However, red-cockaded woodpeckers will only return 

in the Missouri Ozarks with intentional reintroductions. 

While many species such as these probably will benefi t 

from shortleaf pine restoration, it is likely that many others 

that thrive in closed canopy forests, such as wood thrush 

(Hylocichla mustelina) and ovenbird (Seirus aurocapilla), 

will decline, at least locally in the restored pine woodlands. 

Fortunately, birds will not be the only benefi ciaries of 

habitat restoration. Other animal species that are expected to 

benefi t include ringed salamander (Ambystoma annulatum), 

northern fence lizard (Sceloporus undulatus), wood frog 

(Rana sylvatica), and plains spotted skunk (Spilogale 

putorius interrupta) (Nigh 2005). 

Plants that are expected to benefi t include lowbush 

blueberry (Vaccinium pallidum), big-fl owered gerardia 

(Aureolaria grandifl ora), farkleberry (V. arboreum), lead 

plant (Amorpha canescens) and goat’s rue (Tephrosia 

virginiana) (Nelson 1985). The Missouri CWS outlines 

research and inventory needs, current and potential 

conservation partners, and overall conservation strategies 

that will work toward restoration of shortleaf pine woodland 

communities in the Missouri Ozarks.
168

BIRDS OF SHORTLEAF PINE FORESTS IN MISSOURI: 

AN HISTORICAL AND CONTEMPORARY PERSPECTIVE

William R. Eddleman, Richard L. Clawson, and Jody Eberly1

ABSTRACT.—Knowledge of the original bird communities in Missouri’s shortleaf pine (Pinus 

echinata) is limited to accounts of early travelers, and infrequent observations between 1907 

and 1946. Prior to logging and fi re protection, red-cockaded woodpecker (Picoides borealis), 

pine warbler (Dendroica pinus), and Bachman’s sparrow (Aimophila aestivalis) were common 

in shortleaf pine forests; while the sycamore warbler (yellow-throated warbler) (D. dominica) 

was uncommon. Two brown-headed nuthatches (Sitta pusilla) collected in 1907 represent 

the only records for the region. Recent information on the composition of breeding bird 

communities in Missouri shortleaf pine forests is available from a point count data set collected 

in 1984 from a search for red-cockaded woodpeckers in a 15-county area, and from Breeding 

Bird Survey-type routes through the 4,400-ha Pineknot Shortleaf Pine Restoration Project in 

the Mark Twain National Forest in Carter County. Contemporary second-growth pine forests 

are invaded by hardwoods and lack the open nature of the original forests. Consequently, pine 

warbler, yellow-throated warbler, and chipping sparrow are the only species unique to pine 

habitats that remain in Missouri pine forests; other birds breeding in pine forests are also found 

in deciduous forests. The Pineknot site has greater species richness than other Missouri pine 

forests, had higher detection rates of pine warblers and chipping sparrows, and is beginning to 

attract small numbers of bird species characteristic of open habitats. As this habitat improves 

over the next couple of decades, reintroduction of red-cockaded woodpecker and brownheaded nuthatch might be feasible using methods developed in other areas, but there are 

currently no reintroduction methods for the migratory Bachman’s sparrow.

1

Professor of Biology (WRE), Southeast Missouri State University, 

Department of Biology, MS 6200, Cape Girardeau, MO 63701; 

Wildlife Research Biologist (RLC), Missouri Department of 

Conservation, 1110 S. College Ave., Columbia, MO 65201; and 

Wildlife Biologist (JE), Mark Twain National Forest, U.S. Forest 

Service, 401 Fairgrounds Road, Rolla, MO 65401. WRE is 

corresponding author: to contact call (573) 651-2170 or email 

weddleman@semo.edu

INTRODUCTION

Missouri’s shortleaf pine avifauna has undergone profound 

but poorly documented changes during the time since 

presettlement. Little information is available because few 

trained observers visited the area in the settlement era of 

1790-1880 because this ecosystem was lost fairly early 

(1880-1909); remnant stands were logged up to 1946 

(Cunningham 1946, Hill 1949). As one example of how 

poorly the birds of Missouri’s shortleaf pine forests were 

known historically, Widmann (1907) listed the pine warbler 

(see Appendix Table 1 for list of common and scientifi c 

names of birds) as a rare summer resident when in fact, it 

was likely a very common breeder in the pine forests of the 

Missouri Ozarks.

Robbins and Easterla (1992) list red-cockaded woodpecker, 

brown-headed nuthatch, yellow-throated warbler, pine 

warbler, Bachman’s sparrow, and chipping sparrow as 

species of shortleaf pine forest that have declined in 

Missouri since 1900 due to human’s alteration of their 

primary breeding habitat. Since local information on 

these species is lacking, there are few benchmarks against 

which any efforts at restoration of the ecosystem could be 

measured. Thus, synthesis of available information is crucial 

to the restoration of Missouri’s shortleaf pine avifauna.

In this paper, we seek to: review historical information 

on birds in shortleaf pine forests in Missouri; describe 

historic and contemporary bird communities in Missouri 

shortleaf pine forests; compare bird communities of secondgrowth shortleaf pine and oak-pine stands with those of 

the Pineknot Shortleaf Pine Restoration Project; and make 

recommendations for future restoration actions for selected 

bird species in Missouri shortleaf pine forests.

STUDY AREAS

Birds were counted in pine and oak-pine forests in a 

15-county area throughout the range of shortleaf pine in 

Missouri in June 1984 (Eddleman and Clawson 1987), 

and at the Pineknot Shortleaf Pine Restoration Project site 

in Carter County, Missouri, in 2004-2006. Shortleaf pine 

forests in Missouri occur in the Salem Plateau and St. 

Francis Mountains sections of the Ozark Plateau (Liming 

1946, Eddleman and Clawson 1987, Nelson 2005). Old-
169

growth pine forests were cleared in the region from 

1880-1950. Subsequently, annual burning and open range 

livestock grazing through the 1950s, followed by complete 

protection from fi re were the primary land management 

activities in the region. Modern timber management began 

in much of the area with the establishment of Clark and 

Mark Twain National Forests (now Mark Twain National 

Forest). As a result, the area of pine has been reduced, many 

pine stands have been replaced with oak or oak-pine forest, 

and many open-pine forest areas have been converted to 

closed-canopy forests. Other characteristics of the region 

have been previously described (Eddleman and Clawson 

1987).

The Pineknot Shortleaf Pine Restoration Project site is 

a 4,400-ha area in the Current River drainage south of 

Fremont, MO, and southwest of Van Buren, MO, in T26N, 

R1W, sections 18-20 and 29-32; and T26N, R2W, sections 

13-16 and 21-36, Fifth Principal Meridian (Eberly 2001). 

It was established in 2001 to restore a landscape-level area 

to the open pine woodland described by early European 

visitors to the area. Management activities to restore the 

open nature of the forest began in the 1990s and have 

included reduction of canopy cover of overstory trees and 

reintroduction of prescribed fi re. The area is characterized 

by relatively extensive coverage by pine and oak-pine 

forest (almost 50 percent), good accessibility, presence of 

natural fi re control lanes, and a high percentage of public 

land. Vegetation of the area is similar to that of the entire 

range of shortleaf pine in Missouri, but generally there is 

greater coverage by grass and more open understory than in 

other portions of the pine range. The project is a partnership 

among the U.S. Forest Service, Mark Twain National Forest; 

The Nature Conservancy; National Wild Turkey Federation; 

Bat Conservation International; Missouri Department of 

Conservation; National Park Service, Ozark National Scenic 

Riverways; private landowners; and others.

METHODS

Information on the original avifauna of Missouri’s shortleaf 

pine forests was gleaned from published information. In 

addition, literature from other portions of the shortleaf pine 

range was consulted to determine the primary species in the 

habitat, and to provide comparative information.

Point Counts

Birds were counted in mature pine stands in 1983-1984 

as part of a project to assess the population status and 

potential habitat of red-cockaded woodpeckers in Missouri 

(Eddleman and Clawson 1987). Pine and oak-pine stands 

were selected for visits by obtaining information from 

the USDA Forest Service, Mark Twain National Forest; 

National Park Service; Missouri Conservation Department, 

and Missouri Department of Natural Resources, Division 

of State Parks. Of particular assistance in the Mark Twain 

National Forest were the Timber Management Information 

System and Wildlife Management Information System, 

which were used to select all pine stands (≥ 50 percent pine 

stems) in the heart of the shortleaf pine range in the central 

Ozarks of Missouri (Liming 1946). Compartments where 

point counts were conducted had at least 20 ha of 70-yearold pine, and had trees averaging > 25.4 cm diameter at 

breast height. Sites were located using USGS topographic 

maps or compartment maps, or from discussions with 

resource agency personnel.

Point count sites were selected using randomly-generated 

Universal Transverse Mercator coordinates within each 

compartment. One point was generated per 5 ha (12 a) 

of potential habitat. Point counts followed Reynolds and 

others (1980). Each observer used an optical rangefi nder 

to determine distance between himself or herself and the 

bird. He then used a clinometer to determine the vertical 

angle to the bird. Point counts lasted 8 minutes, and all 

birds seen and heard were included. Counts were conducted 

from 0.5 hr before local sunrise until 5 hr after local sunrise. 

Vegetation data were also collected at each point, and results 

have been reported elsewhere (Eddleman and Clawson 

1987). To make data from this part of the study more 

comparable to that collected at Pineknot, only June 1984 

point data are included.

Two roadside routes were used to determine bird species at 

Pineknot in 2000-2006, but only data from 2004-2006 are 

presented. The two routes, Ridgetop and Big Barren, had 

25 and 10 stops, respectively. The Breeding Bird Survey 

methodology was used to assess species present (Sauer 

and others 1997). Running of routes began at 0.5 hr before 

local sunrise, and ended within 4.5 hr. All birds heard, and 

all birds seen within 0.25 mi, were tallied at each point for 

5 min. These data were treated as point counts to make 

them comparable to data from the 1984 part of the study. 

Counts are summarized by species as mean number detected 

(averaged across 2004-2006) ± standard error of the 3 years 

for that species. 

Data were summarized for each species detected using 

Microsoft Excel, and are presented as mean number 

detected ± standard error. 

RESULTS AND DISCUSSION

Historical Accounts of Birds 

in Missouri Shortleaf Pine Forests

No systematic surveys of birds in Missouri’s shortleaf 

pine ecosystem were undertaken prior to the beginning 

of logging in the 1880s. Most early travelers who wrote 

of their experiences tended to stay near rivers or larger 

settlements. This also appears to be the case in neighboring 

Arkansas (Smith and Petit 1988, Smith and Neal 1991). 

Henry Rowe Schoolcraft documented open pine forests in 
170

the region, but he mentions only game species, and does 

not make specifi c reference to the habitats in which these 

species occurred (Schoolcraft 1821, Rafferty 1996). For 

example, Schoolcraft commonly mentions wild turkeys, 

but not in relation to the habitats in which they were most 

abundant. Other birds mentioned included ducks (species 

not identifi ed), wild geese (probably Canada goose), pigeon 

(probably the extinct passenger pigeon), swan (probably 

trumpeter swan), and prairie-hen (greater prairie chicken).

George W. Featherstonhaugh, a U. S. government geologist, 

traveled through the eastern edge of the region in November 

1834 while he was examining the area for mineral and 

metallic resources (Featherstonhaugh 1844). He noted not 

only “pine barrens” in the area between Fredericktown, 

Madison County, and Greenville, Wayne County, but also 

passed through one burned-over area near Fredericktown 

and an active fi re in southern Butler County. He often 

mentions park-like forests, but not the dominant tree species 

in these forests.

The fi rst and sole thorough description of the original 

avifauna of Missouri’s shortleaf pine was made when most 

of the habitat had been lost, in 1907. E. Seymour Woodruff, 

a forester from New York who was also interested in birds, 

visited Shannon and Carter counties from March 7 to 

June 8, 1907 (Woodruff 1907, 1908). At that time, virgin 

pine forest still remained in the most rugged portions 

of Shannon County along the upper Current River, in 

Townships 29 and 30, Ranges 5 and 6 West. There, 

Woodruff observed the avifauna from March 10 to May 15, 

and gave us the best “snapshot” of what the original bird 

community must have been in Missouri’s shortleaf pine 

forests. Pines were restricted to the tops of ridges and the 

plateau of this area. He also commented that the understory 

was open, perhaps because local settlers annually burned the 

ground to improve grazing. He states that the “characteristic 

birds were turkeys, red-cockaded woodpeckers, Bachman’s 

sparrows, and pine warblers.” Woodruff moved to 

the Grandin area in Carter County after May 16, and 

commented that all of the pine and oak had been cut-over, 

leaving only young second-growth woodland.

Woodruff (1908) also recorded small fl ocks of red crossbills 

until May 1, and found one female white-winged crossbill 

feeding with two red crossbills on April 18. He also found a 

number of pine siskins, including one late one on June 4 in 

Carter County. He found no evidence of breeding, and it is 

possible the year 1907 might have been an irruption year for 

northern fi nches. 

James W. Cunningham was the next observer to report birds 

from pine forests in Missouri (Cunningham 1940). Although 

there was a 33-year gap between Woodruff’s (1908) 

observations and Cunningham’s, red-cockaded woodpeckers 

still persisted in the one known virgin pine forest west of 

Highway 19 near Round Spring, Shannon County. Pine 

warblers and yellow-throated warblers were also in the 

same area, but pine warblers were also recorded in small 

pine stands in Carter, Wayne, and Reynolds counties 

(Cunningham 1940).

The species composition of birds present in Missouri’s 

historic shortleaf pine forest is known from the few studies 

reviewed, but we will probably never know the relative 

abundance of bird species in this habitat. Of the pinedependent birds in Missouri, two are extirpated, one no 

longer occurs in contemporary pine habitat, and three are 

common because they are not dependent on open pine 

forest. The history and habitat of the pine-dependent species 

is probably best reviewed on an individual species basis.

Red-cockaded Woodpecker

This endangered woodpecker was apparently “fairly 

common” in Missouri pine forests prior to logging 

(Woodruff 1907, 1908). They were seen “constantly” after 

April 10 in Shannon County pine woodlands, and Woodruff 

collected 5 birds (Robbins and Easterla 1992), two of which 

were in breeding condition. The species was found again 

near the northern border of Carter County (Township 27, 

Range 2 E), but Woodruff commented that they would, “be 

driven out of this region as fast as these woods are cut off.” 

It disappeared in 1946 after all large virgin pine forests 

were logged (Cunningham 1946). Subsequent searches in 

the area in the 1950s (Robbins and Easterla 1992) and a 

search throughout the range of shortleaf pine in the state 

(Eddleman and Clawson 1987) failed to locate this species, 

and it is presumed to be extirpated in the state. The loss 

of this species refl ects what occurred in the neighboring 

states of Arkansas and Oklahoma, where the woodpecker 

persisted only because there were areas that escaped 

logging and the effects of fi re suppression (Smith and Neal 

1991). The habitat needs of red-cockaded woodpeckers are 

well-documented after nearly 40 years of intensive study 

throughout its range (Jackson 1994). These requirements 

include mature pine trees infected with heart rot, open pine 

habitat with little hardwood encroachment, regular fi res 

to prevent hardwood encroachment, and a high degree of 

connectivity with other suitable habitat areas.

Brown-headed Nuthatch 

This species was never proven to breed in Missouri, but 

Woodruff (1907, 1908) collected a pair in some “yellow” 

pines on the edge of a small clearing in Black Valley, 

Shannon County on March 19, 1907. Robbins and Easterla 

(1992) consider its past status “perplexing” because (1) 

there are only two records; (2) none were found during the 

1940s, when red-cockaded woodpeckers were still present 

in the Missouri Ozarks (Cunningham 1940); and (3) they 

are thought to have less exacting habitat requirements than 

red-cockaded woodpeckers. Seemingly suitable habitat is 

found across the Missouri Ozarks today, but the nearest 

populations are in central Arkansas, there is a hiatus in 
171

pine habitat between Missouri and central Arkansas, and 

the species is a poor colonist (Robbins and Easterla 1992, 

Withgott and Smith 1998). It does prefer open, older pine 

stands, however (O’Halloran and Conner 1987), and is more 

abundant in burned stands than unburned stands (Wilson 

and others 1995). Suggested limiting factors in other parts 

of its range may include loss of mature pine habitat, fi re 

suppression, habitat fragmentation, lack of suitable nesting 

snags, cone crop fl uctuations, and nest predation (Jackson 

1988, Withgott and Smith 1998).

Yellow-throated Warbler

This warbler was most common in pristine shortleaf pine, 

“invariably found high up in pines on top of the ridges,” and 

not in sycamores (Platanus occidentalis) in valley bottoms 

(Woodruff 1908). Today this species is locally common in 

three separate habitats in Missouri: rivers with sycamores, 

baldcypress (Taxodium distichum) stands, and shortleaf pine 

(Robbins and Easterla 1992). Little study has focused on 

the species in shortleaf pine. It is possible it may have been 

more abundant in open pine forests, but this needs more 

study (Jackson 1988). It seems to have survived the loss of 

the original pine forests rather well, although density could 

be lower than in the past.

Pine Warbler

Widmann (1907) considered this species a rare summer 

resident and common transient in Missouri. Widmann 

probably made this mistake because he did not visit the 

Ozark area where it nests. Woodruff (1908) considered pine 

warbler common and they are still fairly common where 

there is shortleaf pine (Robbins and Easterla 1992). A few 

overwinter. While it is possibly less common and widely 

distributed than before the pine was harvested at the turn of 

the century (Robbins and Easterla 1992), it seems to occur 

wherever pines are a component of the overstory. Thus, it is 

one of the few pine-dependent species in Missouri to have 

persisted through the loss of open pine forests. Rangewide, 

pine warblers have increased (Rodewald and Smith 

1995). They are most abundant in pure pine, but use pine 

plantations ≥ 40 years old. They become less abundant with 

increasing deciduous overstory and understory.

Bachman’s Sparrow

Most indications are that this sparrow was common in 

Missouri’s pristine open shortleaf pine forest, but clearing 

of pine and fi re protection has resulted in succession and 

loss of its habitat (Woodruff 1907, 1908, Cunningham, 

1941, 1945, Robbins and Easterla 1992). Today, the only 

known breeding Bachman’s sparrows in Missouri are on 

limestone glades, although isolated glades are unlikely to 

support them (Hardin and others 1982, W. R. Eddleman 

and B. Stratton, unpublished data). Range-wide, the species 

occurs in a variety of habitats that have grassy ground cover 

or understory, including glades, old fi elds, pine plantations, 

clearcuts, and open pine forests, although it is likely to avoid 

isolated habitat parcels (Dunning 1993, Hammerson 1997). 

Open pine forests apparently supported the highest density, 

and percent coverage by grass has the strongest infl uence 

on habitat occupancy (Tucker and others 2004). Bachman’s 

sparrow underwent a substantial range expansion in 1890-

1920, but the range then contracted to its present limits 

prior to 1960 (Dunning and Watts 1990, Dunning 1993). 

Reduction of litter, low tree and shrub density, and good 

growth of forbs and grasses such as Andropogon and 

Aristida are recommended management in pine plantations 

in Arkansas (Haggerty 1998).

Chipping Sparrow

In 1907, chipping sparrows were found, “everywhere—in 

the depths of the pine woods on top of the plateaus, and in 

the open stretches in the valley bottoms” (Woodruff 1908). 

This sparrow remains most common in open stands of 

conifers, but also is common in residential areas (Robbins 

and Easterla 1992). It seems to prefer open areas in pine 

forests, or roadsides in heavily forested areas. It is unknown 

how much the species has declined in natural habitats, but 

any decline has been more than offset by its tolerance for 

suburban habitats.

Contemporary Bird Communities 

in Missouri Shortleaf Pine Forests

Forty species were detected during point counts across 

the range of shortleaf pine in Missouri in 1984 (Table 1). 

The principal species detected (≥ 0.2 per point) included 

red-eyed vireo, blue jay, tufted titmouse, pine warbler, 

and ovenbird. In contrast, 60 species were detected on the 

Pineknot routes in 2004-2006 (Table 1). Those species 

averaging ≥ 1.0 detected per stop included red-eyed vireo, 

American crow, blue-gray gnatcatcher, pine warbler, and 

indigo bunting. Only 2 species—red-headed woodpecker 

and brown thrasher—were found at points in 1984 but not 

on the Pineknot routes. In contrast, 22 species occurred on 

the Pineknot routes, but not on the point counts done in 

1984 (Table 1). Most species detected at Pineknot but not on 

the 1984 point counts were species found in open habitats. 

Of particular note is that three of the species of pinedependent bird were not detected in either set of counts: 

red-cockaded woodpecker, brown-headed nuthatch, and 

Bachman’s sparrow. No chipping sparrows were detected 

during the 1984 study, but they were present on the routes at 

Pineknot; possibly the location of most points in the interior 

of forest stands may have avoided them. Yellow-throated 

warblers were present in low frequencies in both studies, 

with slightly more detected per point in 1984. Pine warblers, 

however, were detected at Pineknot at nearly three times the 

level of the 1984 study (Table 1).

Bird species richness and number of birds detected were 

lower at the pine and oak pine forests visited in the 1984 

study than at Pineknot in 2004-2006 (Table 1). Most sites 

visited during the 1984 study were too densely stocked 
172

Table 1.—Summer birds detected on point counts in pine and oak pine forests in Missouri in June 1984, and on Breeding Bird 

Survey (BBS) mini-routes in the Pineknot Shortleaf Pine Restoration Project in June 2004-2006.

a

Standard error calculated from all points

b

Standard error calculated from means among all 3 years

 1984 point counts Pine Knot BBS routes,

 (n=130) 2004-2006 (n=35)

 No. per point Mean No. per point % freq.

Species n + SEa

 % freq. detected + SEb + SEb

Wild Turkey 2 0.015 ± 0.009 1.5 0.7 0.019 ± 0.019 1.9 ± 1.9

Northern Bobwhite 0 0 0 2.3 0.067 ± 0.067 4.8 ± 48

Turkey Vulture 0 0 0 0.3 0.010 ± 0.010 1.0 ± 1.0

Red-shouldered Hawk 1 0.008 ± 0.006 0.8 1.0 0.029 ± 0.016 2.9 ± 2.9

Broad-winged Hawk 1 0.008 ± 0.006 0.8 0.7 0.019 ± 0.019 1.9 ± 1.9

Red-tailed Hawk 2 0.015 ± 0.009 1.5 0.3 0.010 ± 0.010 1.0 ± 1.0

Mourning Dove 1 0.008 ± 0.006 0.8 4.3 0.124 ± 0.124 9.5 ± 9.5

Yellow-billed Cuckoo 23 0.177 ± 0.028 16.9 21.0 0.600 ± 0.214 47.6 ± 17.5

Great Horned Owl 0 0 0 0.7 0.019 ± 0.010 1.9 ± 1.0

Barred Owl 0 0 0 9.7 0.276 ± 0.158 21.0 ± 10.6

Whip-poor-will 1 0.008 ± 0.006 0.8 1.3 0.038 ± 0.019 2.9 ± 1.6

Ruby-throatedHummingbird 3 0.023 ± 0.010 2.3 2.7 0.076 ± 0.025 4.8 ± 1.0

Red-headed Woodpecker 2 0.015 ± 0.006 0.8 0 0 0

Red-bellied Woodpecker 7 0.054 ± 0.016 5.4 2.0 0.057 ± 0.028 5.7 ± 2.8

Downy Woodpecker 8 0.062 ± 0.019 5.4 3.7 0.105 ± 0.062 9.5 ± 5.3

Hairy Woodpecker 2 0.015 ± 0.009 1.5 2.3 0.067 ± 0.038 5.7 ± 2.8

Northern Flicker 1 0.008 ± 0.006 0.8 0.3 0.010 ± 0.010 1.0 ± 1.0

Pileated Woodpecker 5 0.038 ± 0.016 3.1 6.7 0.190 ± 0.148 18.1 ± 13.8

Eastern Wood-pewee 11 0.085 ± 0.019 8.5 11.7 0.333 ± 0.010 32.4 ± 1.0

Acadian Flycatcher 19 0.146 ± 0.029 10.8 10.0 0.286 ± 0.129 21.0 ± 9.4

Eastern Phoebe 1 0.008 ± 0.006 0.8 2.3 0.060 ± 0.067 5.7 ± 5.7

Great Crested Flycatcher 13 0.100 ± 0.023 9.2 1.7 0.048 ± 0.025 3.8 ± 2.5

Eastern Kingbird 0 0 0 4.7 0.133 ± 0.069 11.4 ± 5.9

White-eyed Vireo 0 0 8.0 0.229 ± 0.033 14.3 ± 2.8

Yellow-throated Vireo 0 0 0 1.7 0.048 ± 0.034 2.9 ± 1.6

Red-eyed Vireo 35 0.269 ± 0.033 25.4 69.7 1.990 ± 0.149 91.4 ± 3.3

Blue Jay 82 0.631 ± 0.069 36.2 10.7 0.305 ± 0.119 24.8 ± 10.5

American Crow 13 0.100 ± 0.031 6.9 69.3 1.981 ± 0.050 90.5 ± 3.4

Barn Swallow 0 0 0 6.0 0.171 ± 0.033 4.8 ± 1.0

Carolina Chickadee 6 0.046 ± 0.021 2.3 18.0 0.514 ± 0.141 33.3 ± 6.9

Tufted Titmouse 44 0.338 ± 0.042 27.7 22.7 0.648 ± 0.069 49.5 ± 8.3

White-breasted Nuthatch 13 0.100 ± 0.023 9.2 17.0 0.486 ± 0.119 40.0 ± 10.3

Carolina Wren 0 0 0 6.0 0.171 ± 0.044 15.2 ± 5.0

Blue-gray Gnatcatcher 13 0.100 ± 0.023 9.2 40.0 1.143 ± 0.119 57.1 ± 3.3

Eastern Bluebird 0 0 0 3.0 0.086 ± 0.033 5.7 ± 1.6

Wood Thrush 7 0.054 ± 0.016 5.4 1.0 0.029 ± 0.028 1.9 ± 1.9

Brown Thrasher 1 0.008 ± 0.006 0.8 0 0 0

Cedar Waxwing 0 0 0 0.3 0.010 ± 0.010 1.0 ± 1.0

Blue-winged Warbler 0 0 0 5.3 0.152 ± 0.025 10.5 ± 1.0

Northern Parula 3 0.023 ± 0.010 2.3 3.0 0.086 ± 0.049 7.6 ± 5.0

Yellow-throated Warbler 9 0.069 ± 0.018 6.9 1.7 0.048 ± 0.034 4.8 ± 3.4

Pine Warbler 73 0.562 ± 0.047 46.9 44.0 1.257 ± 0.129 61.9 ± 2.5

Prairie Warbler 0 0 0 5.0 0.143 ± 0.016 13.3 ± 1.9

Black-and-white Warbler 11 0.085 ± 0.019 8.5 10.3 0.295 ± 0.025 21.9 ± 2.5

Worm-eating Warbler 13 0.100 ± 0.021 10.0 6.7 0.190 ± 0.069 16.2 ± 6.7

Ovenbird 109 0.838 ± 0.058 61.5 8.7 0.248 ± 0.053 21.0 ± 4.8

Kentucky Warbler 3 0.023 ± 0.010 2.3 2.7 0.076 ± 0.019 7.6 ± 1.9

Common Yellowthroat 0 0 0 4.0 0.114 ± 0.028 9.5 ± 1.0

Yellow-breasted Chat 0 0 0 15.0 0.429 ± 0.119 30.5 ± 5.8

Summer Tanager 25 0.192 ± 0.030 17.7 22.7 0.648 ± 0.053 56.2 ± 4.2

Scarlet Tanager 19 0.146 ± 0.025 14.6 24.0 0.686 ± 0.072 48.6 ± 3.3

Eastern Towhee 12 0.092 ± 0.025 6.9 2.3 0.067 ± 0.034 4.8 ± 2.5

Chipping Sparrow 0 0 0 9.0 0.257 ± 0.072 18.1 ± 3.4

Field Sparrow 0 0 0 3.0 0.086 ± 0.016 5.7 ± 0.0

Northern Cardinal 13 0.100 ± 0.023 8.5 7.7 0.219 ± 0.042 19.0 ± 2.5

Blue Grosbeak 0 0 0 0.3 0.010 ± 0.010 1.0 ± 1.0

Indigo Bunting 16 0.123 ± 0.026 10.8 39.7 1.133 ± 0.182 68.6 ± 5.7

Red-winged Blackbird 0 0 0 2.7 0.076 ± 0.010 3.8 ± 1.0

Eastern Meadowlark 0 0 0 4.3 0.124 ± 0.034 5.7 ± 1.6

Brown-headed Cowbird 16 0.123 ± 0.024 11.5 0.7 0.019 ± 0.010 1.9 ± 1.0

Orchard Oriole 0 0 0 0.7 0.019 ± 0.010 1.9 ± 1.0

American Goldfi nch 0 0 0 3.0 0.086 ± 0.044 6.7 ± 2.5
173

in terms of number of stems, especially hardwoods, and 

basal area in comparison to ideal red-cockaded woodpecker 

habitat (Eddleman and Clawson 1987). Pines of the correct 

age for red-cockaded woodpeckers are present, but thinning 

of hardwood understory trees would be necessary to make 

the habitat suitable. A particular problem in these sites was 

a dense understory of tall hardwood saplings and shrubs. As 

a result, birds more often found in hardwood forests, such 

as Acadian fl ycatcher, red-eyed vireo, and ovenbird, were 

among the most common on the 1984 point counts (Pagen 

and others 2000).

Smith and Petit (1988) state that coniferous habitats in the 

Ozarks have a depauperate avifauna. It is possible, however, 

that this situation is a combination of degraded forests due 

to hardwood invasion, low productivity with fi re exclusion, 

and the relatively young age of many coniferous habitats 

(e.g., pine plantations). Most stands included in the 1984 

portion of the study were heavily invaded by hardwoods and 

were not burned (Eddleman and Clawson 1987). 

CONCLUSIONS AND 

MANAGEMENT RECOMMENDATIONS

Three pine-dependent bird species have been extirpated or 

nearly extirpated from Missouri. All were common at one 

time except possibly the brown-headed nuthatch. Today, 

yellow-throated warbler, pine warbler, and chipping sparrow 

remain common, but available information indicates these 

species might become more common in open pine stands 

(Wilson and others 1995).

Many of the species present on the routes at Pineknot, 

but absent from the 1984 study, were those that increase 

after pine forests are thinned and burned, such as northern 

bobwhite and prairie warbler (Dram and others 2002). 

Suggested mechanisms by which bird species increase or 

decrease depend on the species: removal of hardwoods, 

increase in grassy vegetation and arthropod abundance, 

increased low shrubs (the latter two associated with 

increased light) (Conner and others 2002). Thinning and 

prescribed fi re should continue to improve the habitat. 

Summer fi res are thought to be the primary type of fi res that 

occurred in pristine Southeast pine forests (Jackson 1988), 

so restoration should incorporate a variety of fi re regimes.

The extirpated bird species of pine forests would have to 

be restored to Missouri. It will probably be many years 

before habitat is suitable on a large enough scale to maintain 

populations of these species, however. Any such restoration 

should include intensive habitat assessment prior to the 

attempt, and assurance that management for producing high 

quality habitat would continue (Jackson 1994). Methods 

for moving red-cockaded woodpecker colonies have been 

developed and have enjoyed some degree of success. These 

methods include cavity restrictors to exclude competitors, 

movement of young females from natal sites to clans 

lacking a female, and artifi cial cavity construction methods 

(Jackson 1994). Brown-headed nuthatch reintroduction 

may be feasible, but only one large-scale project has been 

undertaken with this species (Slater 2004). In 1997-2001, 

53 were released in Everglades National Park, and the 

project was judged to be a success because the population 

increased and demographic measures were similar to those 

in a high-quality reference population. Prior to the attempt, 

the forest in the area had matured, snags were present 

due to Hurricane Andrew in 1992, and the area could 

support an estimated 200 territories. Burning had also been 

implemented (Slater 2004).

Bachman’s sparrow management includes prescribed fi re 

and maintenance of core areas of mature pine forest to 

provide for colonization of ephemeral habitats such as 

abandoned fi elds and certain clearcuts (Hammerson 1997). 

Reintroduction should not be undertaken, however, until 

dispersal in this species is better understood. The species is 

also migratory in Missouri, and methods for reintroduction 

of migratory songbirds do not exist at present. A more 

likely scenario is that Bachman’s sparrows will disperse 

into suitable habitat when a large enough block is created 

through appropriate management (Dunning and Watts 

1990).

ACKNOWLEDGMENTS

We thank K. Kelley and C. Price, U.S. Forest Service, 

Doniphan Ranger District, for conducting point counts at 

Pineknot.

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463-472.

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Mark Twain National Forest, Carter County, Missouri. 

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Universities Press. 164 p.

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sparrow breeding habitat and its relationship to home 

range. Journal of Field Ornithology. 69(1): 45-50.

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VA: The Nature Conservancy. 9 p.

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Company, 1880-1909. Columbia, MO: University of 

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Press: 119-159.

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and Washington, DC: The American Ornithologists’ 

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Liming, F.G. 1946. The range and distribution of shortleaf 

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Missouri. Jefferson City, MO: Missouri Natural Areas 

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brown-headed nuthatches. Bulletin of the Texas 

Ornithological Society. 20(1): 7-13.

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variable circular-plot method for estimating bird 

numbers. Condor. 82(3): 309-313.

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abundance and distribution. Columbia, MO: University 

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abstract: pine warbler (Dendroica pinus). Arlington, 

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B.G. 1997. The North American Breeding Bird Survey 

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of Missouri and Arkansaw. London, UK: Sr. Richard 

Phillips and Company. 102 p.

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Park: an evaluation of the brown-headed nuthatch and 

eastern bluebird reintroduction program during the 

2-year post-translocation period (2002-2003), fi nal 

report. Mount Vernon, WA: Ecostudies Institute. 35 p.

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mammals of the Interior Highlands. In: Henderson, D.; 

Hedrick, L.D., eds. Restoration of old growth forests in 

the Interior Highlands of Arkansas and Oklahoma; 1990 

September 19-20; Morrilton, AR. [Place of publication 

unknown]:[Publisher unknown]: 77-103.

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practices in the Ozarks: past present, and future 

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North American songbirds. Journal of Wildlife 

Management. 68(4): 1114-1123.

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Breeding bird response to pine-grassland community 

restoration for red-cockaded woodpeckers. Journal of 

Wildlife Management. 59(1): 56-67.

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(Sitta pusilla). In: The Birds of North America, 

No. 349. Philadelphia, PA: The Academy of Natural 

Sciences; and Washington, DC: The American 

Ornithologists’ Union. 24 p.

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Shannon and Carter counties, Missouri. Auk. 25(2): 

191-214.

Acadian Flycatcher (Empidonax virescens)

American Crow (Corvus brachyrhynchos)

American Goldfi nch (Carduelis tristis)

Bachman’s sparrow (Aimophila aestivalis)

Barn Swallow (Hirundo rustica)

Barred Owl (Strix varia)

Black-and-white Warbler (Mniotilta varia)

Blue Grosbeak (Passerina caerulea)

Blue Jay (Cyanocitta cristata)

Blue-gray Gnatcatcher (Polioptila caerulea)

Blue-winged Warbler (Vermivora pinus)

Broad-winged Hawk (Buteo platypterus)

Brown Thrasher (Toxostoma rufum)

Brown-headed Cowbird (Molothrus ater)

Brown-headed Nuthatch (Sitta pusilla)

Canada Goose (Branta canadensis)

Carolina Chickadee (Poecile carolinensis)

Carolina Wren (Thryothorus ludovicianus)

Cedar Waxwing (Bombycilla cedrorum)

Chipping Sparrow (Spizella passerina)

Common Yellowthroat (Geothlypis trichas)

Downy Woodpecker (Picoides pubescens)

Eastern Bluebird (Sialia sialis)

Eastern Kingbird (Tyrannus tyrannus)

Eastern Meadowlark (Sturnella magna)

Eastern Phoebe (Sayornis phoebe)

Eastern Towhee (Pipilo erythrophthalmus)

Eastern Wood-pewee (Contopus virens)

Field Sparrow (Spizella pusilla)

Great Crested Flycatcher (Myiarchus crinitus)

Great Horned Owl (Bubo virginianus)

Greater prairie chicken (Tympanuchus cupido)

Hairy Woodpecker (Picoides villosus)

Indigo Bunting (Passerina cyanea)

Kentucky Warbler (Oporornis formosus)

Mourning Dove (Zenaida macroura)

Appendix Table 1.—Scientifi c names of birds mentioned in the text.

Northern Bobwhite (Colinus virginianus)

Northern Cardinal (Cardinalis cardinalis)

Northern Flicker (Colaptes auratus)

Northern Parula (Parula americana)

Orchard Oriole (Icterus spurius)

Ovenbird (Seiurus aurocapilla)

Passenger Pigeon (Ectopistes migratorius)

Pileated Woodpecker (Dryocopus pileatus)

Pine Siskin (Carduelis pinus)

Pine Warbler (Dendroica pinus)

Prairie Warbler (Dendroica discolor)

Red Crossbill (Loxia curvirostra)

Red-bellied Woodpecker (Melanerpes carolinus)

Red-cockaded Woodpecker (Picoides borealis)

Red-eyed Vireo (Vireo olivaceus)

Red-headed Woodpecker (Melanerpes erythrocephalus)

Red-shouldered Hawk (Buteo lineatus)

Red-tailed Hawk (Buteo jamaicensis)

Red-winged Blackbird (Agelaius phoeniceus)

Ruby-throated Hummingbird (Archilochus colubris)

Scarlet Tanager (Piranga olivacea)

Summer Tanager (Piranga rubra)

Trumpeter Swan (Cygnus buccinator)

Tufted Titmouse (Baeolophus bicolor)

Turkey Vulture (Cathartes aura)

Whip-poor-will (Caprimulgus vociferus)

White-breasted Nuthatch (Sitta carolinensis)

White-eyed Vireo (Vireo griseus)

White-winged Crossbill (Loxia leucoptera)

Wild Turkey (Meleagris gallopavo)

Wood Thrush (Hylocichla mustelina)

Worm-eating Warbler (Helmitheros vermivorum)

Yellow-billed Cuckoo (Coccyzus americanus)

Yellow-breasted Chat (Icteria virens)

Yellow-throated Vireo (Vireo fl avifrons)

Yellow-throated Warbler (Dendroica dominica)
176

AVIAN RESPONSE TO PINE RESTORATION AT PECK RANCH CONSERVATION AREA

Richard Clawson, Carrie Steen, Kim Houf, and Terry Thompson1

1

Missouri Department of Conservation (RC), Columbia, MO; 

Missouri Department of Conservation (CS), West Plains, MO; 

Missouri Department of Conservation (KH), Winona, MO; 

Missouri Department of Conservation (TT), Eminence, MO. RC is 

corresponding author: to contact call (573) 882-9880 or email 

rick.clawson@mdc.mo.gov

EXTENDED ABSTRACT

Midco Pine Flats is a 2,223-acre region of Peck Ranch 

Conservation Area (CA) that is classifi ed as a pine-oak 

plains land type association. Extensive logging in the early 

1900s removed most overstory shortleaf pine allowing 

oak to become the primary overstory component. In 2000, 

Missouri Department of Conservation staff initiated a pineoak woodland restoration project with the primary goal of 

determining whether management practices (selective black 

oak harvest, fi re, leave pine) in the pine-oak-vaccinium 

natural community at Peck Ranch are restoring the natural 

community. The study used prescribed fi re, harvest, or both 

as primary restoration tools.

In 2004, a concurrent study was initiated to focus more 

directly on pine regeneration. The Midco Pine Flats area 

was divided into 10 treatment units to examine the effects 

of different competition control methods used to advance 

pine regeneration. Three units were assigned to each of three 

treatments (chemical, mechanical, and prescribed fi re), and 

the remaining unit was left untreated as the control. Within 

these units, restoration is focused on areas characterized 

by pine-oak/vaccinium Dry Ultic and mixed oak-pine/

Desmodium, vaccinium chert natural communities. Some 

of the area was planted in pine, while the rest was deemed 

adequate in natural regeneration. These sites also were 

slashed and site preparation prescribed burning was applied.

Methods

To monitor the effects of pine restoration on migrant and 

resident birds, a modifi ed breeding bird survey (BBS) 

(Anonymous 1970) is conducted annually at Peck Ranch 

CA. The BBS route consists of 25 points, approximately 0.5 

mi apart, on gravel roads and woods trails that are accessible 

by vehicle. At each point, observers exit the vehicle, stand 

for 5 minutes, and record all birds heard and seen. This 

route is run twice from May 15 to June 30. Data have been 

collected via this BBS since 2000. From these data, indexes 

to bird distribution and abundance have been generated.

Vegetation has also been sampled within the shortleaf pine 

restoration project area. Twenty-four permanent vegetation 

sampling plots (0.2 ac) were established randomly in 2000, 

stratifi ed by four ecological land types (ELT) (Rimer 2003.) 

Thirty additional plots were established in 2005 within 

designated pine restoration sites. Vegetation sampling 

includes percent class of ground fl ora/ground cover; sapling 

species, height and diameter at breast height (DBH); and 

overstory species and DBH. Initial plots were sampled 

in 2000, 2002 and 2006; sampling for ground fl ora and 

saplings began in 2006 for additional plots.

Results and Discussion

Fifty-two species of birds have been detected on the Peck 

Ranch CA BBS between 2000 and 2006 (Table 1). The 

number of species detected each year has trended upward, 

primarily because canopy-dwelling birds have remained 

on the site and early-successional species have responded 

positively to the treatment. Only one species has apparently 

disappeared from the survey. The rates and frequency of 

detection for these birds are varied (Table 1.)

Pine warbler was common prior to the pine restoration 

project (Table 1) but retention of pine in the overstory, along 

with opening the canopy, probably enhanced its habitat. This 

is consistent with increases in overstory pine throughout this 

period. Northern parula prefers large tree crowns that stick 

out from their surroundings; opening the canopy enhanced 

habitat for this species. One canopy dweller, red-eyed vireo, 

decreased, probably because of the reduction of deciduous 

trees in the canopy as evidenced by the overall decrease in 

stem density of overstory trees.

Mixed forest/open habitat-dweller Mourning Dove and 

early successional habitat-dwellers yellow-breasted chat, 

white-eyed vireo, and prairie warbler all increased (Table 1). 

At the same time, overstory density decreased, allowing an 

increase in sapling stem density. These species probably 

benefi ted from the more open canopy and the increased 

herbaceous and shrub vegetation at ground level. Earlysucessional habitat-dweller indigo bunting has remained 

essentially unchanged. This species already was abundant in 

the area when the pine restoration project began.

Finally, subcanopy-dweller yellow-billed cuckoo has 

disappeared from the survey (Table 1), probably as a result 

of a more open canopy and a reduction in midstory saplings. 

This change can be seen in the frequency of saplings 

occurring by foot class: Vegetation sampling from 2006 

shows that the greatest number of saplings range from only 

5 to 8 feet tall, creating more “brushy” habitat rather than a 

developed midstory at this time.
177

Although vegetation sampling is still in the preliminary 

stage, we are fi nding that structural changes due to 

management activities may account for changes in avifauna 

in the pine restoration area of Peck Ranch CA.

LITERATURE CITED

Anonymous. 1970. An international standard for a 

mapping method in bird census work recommended by the 

international Bird Census Committee. Audubon Field Notes. 

24: 722-726.

Rimer, R.L. 2004. Project evaluates burning and timber 

harvest for restoring Ozark pine-oak woodlands (Missouri). 

Ecological Restoration. 22: 3.

 Mean number of stops

 Mean number of birds per stop at which birds were detected

Species 2000 2001 2002 2003 2004 2005 2006 2000 2001 2002 2003 2004 2005 2006

Turkey vulture 0 0 0.04 0.02 0 0 0 0 0 0.5 0.5 0 0 0

Red-tailed hawk 0 0 0.04 0.02 0.04 0 0.04 0 0 1 0.5 1 0 1

Red-shouldered hawk 0 0.04 0 0 0 0.1 0.02 0 1 0 0 0 2.5 0.5

Broad-winged hawk 0 0 0 0 0.04 0 0 0 0 0 0 0.5 0 0

Wild turkey 0.08 0.04 0.08 0.14 0.02 0.12 0 1.5 0.5 2 2.5 0.5 2.5 0

Mourning dove 0.08 0.04 0.12 0.1 0.22 0.22 0.32 1.5 1 2.5 2.5 4.5 5 7

Yellow-billed cuckoo 0.4 0.68 0.64 0.5 0.2 0.06 0 9 12 12.5 9 4.5 1.5 0

Chimney swift 0 0 0 0.04 0 0 0 0 0 0 0.5 0 0 0

Ruby-throat. hummingbird 0.04 0.06 0.04 0.1 0.06 0.02 0.08 1 1.5 1 2 1.5 0.5 1.5

Pileated woodpecker 0.46 0.7 0.94 0.84 0.5 0.76 0.52 8 14 15.5 14 10 13.5 8.5

Red-bellied woodpecker 0.16 0.14 0.16 0.2 0.12 0.24 0.16 3.5 3.5 4 5 2.5 5.5 4

Red-headed woodpecker 0 0.02 0 0 0 0.06 0.06 0 0.5 0 0 0 1.5 1.5

Hairy woodpecker 0 0 0.02 0.02 0.08 0.02 0 0 0 0.5 0.5 1.5 0.5 0

Downy woodpecker 0.02 0.2 0.06 0.04 0.02 0.06 0.1 0.5 4 1.5 1 0.5 1.5 2.5

Great-crested fl ycatcher 0.26 0.2 0.24 0.34 0.12 0.08 0.14 6 4 5.5 7 3 1.5 3.5

Acadian fl ycatcher 0.08 0 0.02 0.04 0.04 0.04 0.08 2 0 0.5 1 1 1 2

Eastern wood pewee 0.54 0.68 0.54 0.64 0.66 0.74 0.5 12.5 16 11.5 11.5 13 16 11.5

Purple martin 0 0 0 0.02 0 0 0 0 0 0 0.5 0 0 0

Blue jay 0.02 0.1 0.12 0.12 0.06 0.26 0.04 0.5 2.5 1 2 1.5 6 1

Common crow 0.94 1.12 0.88 1.2 0.74 0.94 0.98 12.5 18 14 18 10.5 16.5 16

Carolina chickadee 0.08 0.14 0.14 0.14 0.12 0.2 0.04 1 2.5 2.5 2.5 2.5 3.5 0.5

E. tufted titmouse 0.36 0.32 0.7 0.38 0.42 0.24 0.34 8 5.5 11.5 7.5 8.5 6 7

White-breasted nuthatch 0.42 0.12 0.3 0.2 0.4 0.36 0.32 8 3 7 5 8 6.5 6.5

Carolina wren 0.12 0 0.06 0.08 0.24 0.2 0.28 3 0 1.5 2 5 4 6

Wood thrush 0.02 0 0.04 0 0.02 0.02 0.04 0.5 0 1 0 0.5 0.5 1

Table 1.—Mean number of birds and detection frequency per stop, 2000-2006.

(Table 1 continued on next page)
178

 Mean number of stops

 Mean number of birds per stop at which birds were detected

Species 2000 2001 2002 2003 2004 2005 2006 2000 2001 2002 2003 2004 2005 2006

Eastern bluebird 0 0 0 0.04 0 0.12 0 0 0 0 0.5 0 1.5 0

Blue-gray gnatcatcher 0.44 0.56 0.62 0.64 0.44 0.3 0.54 10.5 11 13.5 10.5 9.5 6 11

White-eyed vireo 0 0 0.08 0.08 0.38 0.32 0.48 0 0 2 2 8 6.5 8.5

Yellow-throated vireo 0.08 0.04 0.1 0.02 0.1 0 0.08 2 1 2 0.5 2.5 0 2

Red-eyed vireo 1.38 1.32 1.66 1.34 1.34 1.04 0.92 21 21.5 20.5 24 18.5 18.5 15.5

Black and white warbler 0.08 0.06 0.06 0.24 0.2 0.14 0.1 2 1.5 1.5 6 5 3.5 2.5

Worm-eating warbler 0.04 0 0 0 0.04 0 0 1 0 0 0 1 0 0

Blue-winged warbler 0 0.02 0 0.04 0.04 0.12 0.06 0 0.5 0 1 1 3 1.5

Northern Parula 0.18 0.12 0.3 0.4 0.62 0.48 0.6 4.5 3 6.5 4 11 9.5 12

Cerulean warbler 0 0 0.02 0 0.02 0 0 0 0 0.5 0 0.5 0 0

Yellow-throated warbler 0.5 0.42 0.56 0.38 0.58 0.36 0.34 11 9 11 9 11.5 8 7

Pine warbler 0.78 0.56 1.12 0.82 1.24 1.12 1.08 16 11 17.5 15.5 20 17 18

Prairie warbler 0.16 0.12 0.36 0.48 0.46 0.4 0.22 4 3 8 10.5 10.5 8.5 5.5

Ovenbird 0 0.04 0 0.02 0 0.04 0.02 0 1 0 0.5 0 1 0.5

Common Yellowthroat 0 0 0 0 0.06 0.04 0.06 0 0 0 0 1.5 1 1.5

Yellow-breasted Chat 0.22 0.62 0.82 0.96 1.32 1.22 1.24 5 12.5 13.5 17 19 20 19

Kentucky Warbler 0 0 0 0.02 0.02 0.1 0.08 0 0 0 0.5 0.5 2 2

Orchard Oriole 0 0 0 0 0.02 0.02 0 0 0 0 0 0.5 0.5 0

Brown-headed Cowbird 0.26 0.08 0.4 0.16 0.12 0.16 0.12 6 2 8.5 3.5 3 3.5 3

Scarlet Tanager 0.22 0.46 0.26 0.36 0.26 0.34 0.16 4 9.5 5.5 8.5 6 8 3.5

Summer Tanager 0.56 0.64 0.74 0.3 0.22 0.44 0.34 11.5 13.5 14.5 7.5 5 10.5 7

Northern Cardinal 0.2 0.12 0.28 0.14 0.26 0.28 0.18 5 2.5 7 3.5 5.5 7 3.5

Indigo Bunting 1.24 1.52 1.88 1.7 1.54 1.36 1.44 20.5 22.5 22.5 22 20 21 19

American Goldfi nch 0 0 0 0.04 0.06 0.04 0 0 0 0 0.5 1.5 0.5 0

Eastern Towhee 0.04 0.06 0.12 0.12 0.16 0.14 0.18 1 1.5 3 3 3.5 3.5 4

Chipping Sparrow 0 0.06 0 0 0.02 0.1 0.06 0 0.5 0 0 0.5 2 1

Field Sparrow 0 0.02 0.04 0.1 0.06 0.04 0.2 0 0.5 1 2 1.5 1 5

Total No. 

Species Observed 33 35 38 43 45 44 40

Table 1.—Mean number of birds and detection frequency per stop, 2000-2006. (continued)
179

TIMBER HARVEST LEVELS AND PRESSURE ON SHORTLEAF PINE IN MISSOURI

Thomas B. Treiman, Ron J. Piva, and W. Keith Moser1

1

Natural Resource Economist (TBT), Missouri Department of 

Conservation, Columbia 1110 S. College Ave., MO 65201; Research 

Forester (RJP and WKM), Northern Research Station - USDA 

Forest Service, St. Paul, MN 55108. TBT is corresponding author: to 

contact call (573) 882-9909 or email at tom.treiman@mdc.mo.gov

ABSTRACT.—Data from two sources are used to estimate the harvest pressure on Missouri’s 

shortleaf pine (Pinus echinata Mill.) resource. By overlapping Timber Product Output (TPO) 

and Forest Inventory and Analysis (FIA) inventory data, we examine utilization pressure on 

shortleaf pine and the residual inventory. Conducted every three years in Missouri, the TPO 

survey consists of a complete census of all primary mills and is a snapshot in time of timber 

use. TPO data from 1969 to 2003 show that annual shortleaf pine harvest has varied between 

4.0 and 8.9 million cubic feet. Most of the shortleaf pine harvested in the State was processed 

in Missouri. FIA fi eld plots offer another method of estimating both shortleaf pine growth and 

removals on an annual basis using plot and tree measurements over time. In 1989, FIA data 

estimated annual removals of shortleaf pine growing stock at 6.8 million cubic feet (including 

both harvest and land use changes); in 2004, annual removals of shortleaf pine growing stock 

were 5.0 million cubic feet. In both 1989 and 1999-2003, most of the removals came from the 

medium- and small-size classes. FIA data also show overall sustainable utilization pressure, 

with annual net growth of shortleaf pine growing stock that has increased from 18.5 million 

cubic feet in 1989 to 25.1 million cubic feet in 2003. Questions of long-term ecological and 

economic sustainability and impacts are also addressed using these data sets.

INTRODUCTION

When early European settlers fi rst reached Missouri, there 

were an estimated 6.6 million acres of shortleaf pine (Pinus 

echinata Mill.), concentrated particularly in the Ozarks. 

By 2003, shortleaf pines occupied only about 163,500 

acres, a net loss of approximately 6.4 million acres (Moser 

et al. 2005). This decrease has substantially changed the 

appearance and ecology of the forests once dominated by 

the species (Stambaugh and Muzika 2001). Shortleaf pine 

was a primary source of timber in Missouri from the late 

1800s until the early 1920s, when millions of board feet 

were harvested for large sawmills in the southern Missouri 

Ozarks. Railroad networks reached from the woods to the 

sawmills. Where railroads were lacking, oxen pulled wagons 

loaded with large pine logs to the mills. Missouri’s timber 

production peaked in 1899. By 1910, nearly all the pine had 

been cut (Palmer 2000). Over the last century, the economic 

importance of shortleaf pine to Missouri has declined along 

with the area of the state dominated by pine forest.

Gwaze (2005) notes that the current population structure of 

shortleaf pine has been heavily infl uenced by past human 

activities. Shortleaf pine forests in Missouri have been 

reduced by the combined effects of 1) uncontrolled logging 

and high-grading between 1880 and 1920; 2) excessive 

surface fi res in the fi rst half of the 20th century that were 

used to encourage the growth of pasture but which also 

discouraged pine regeneration; 3) open-range grazing; and 

4) effective fi re suppression by state and federal agencies 

since 1950, preventing the periodic fi res necessary for 

regeneration of shortleaf pine, a fi re-dependent species. 

These disturbance patterns resulted in establishment of 

millions of acres of oak-dominated forest on areas that 

previously were dominated by shortleaf pine.

Shortleaf pine used to be a major component of Missouri’s 

economy, and remains important to the state’s biodiversity 

and natural heritage. The economic, ecological, and 

scientifi c importance of shortleaf pine has spurred the active 

promotion of both natural and artifi cial regeneration of the 

species to restore former pineries, increase forest diversity, 

and mitigate oak decline on sites better adapted to shortleaf 

pine. Over the last decades, natural resource management 

agencies have developed strategies and projects to restore 

shortleaf pine in areas of its previous range (Missouri 

Department of Conservation 2005). Indeed, shortleaf pine 

restoration on oak sites that are better suited to pine and 

have a high potential for future oak decline may be one way 

to deal with forest health issues. But such efforts may not 

be successful or sustainable, especially on private land, if 

the economic incentives of restoring shortleaf pine, and the 

harvest pressure it faces, are not well understood. 

DATA AND METHODS

Forest Inventory and Analysis Methods

The national Forest Inventory and Analysis (FIA) program 

provides estimates of forest area, volume, change, and forest 
180

health throughout the United States (McRoberts 1999). The 

FIA sampling design consists of a random, equal probability 

sample with a base intensity of one plot per approximately 

6,000 acres. Beginning with the 1999 inventory, Missouri 

was one of the fi rst states in the nation to be inventoried 

with the new annualized FIA system (Moser et al. 2005). 

The FIA annual inventory system measures approximately 

one-fi fth of all fi eld plots each year. After 5 years, an entire 

inventory cycle will be completed. After the fi rst 5 years, 

FIA will report and analyze results as a moving 5-year 

average. We used data from the 1999-2003 and the 2000-

2004 inventories of Missouri to analyze the shortleaf pine 

resource. For estimates of both growth and removals these 

inventories demonstrate wide variation because of the 

long time gap between the last periodic inventory (1989) 

and the fi rst full 5-year annualized inventory as well as 

changes in defi nitions and methods over that time period. In 

addition, the 2000-2004 inventory, although using consistent 

defi nitions and methods relies on the remeasurement of only 

one year’s worth of data (the plots taken in 1999 and again 

in 2004) for growth and removals estimates.

Timber Product Output Data

Periodic Timber Product Output (TPO) survey is an ongoing cooperative effort between the Missouri Department 

of Conservation (MDC) and the USDA Forest Service’s 

Northern Research Station (NRS) (Treiman and Piva 2005). 

Consulting foresters from Missouri and MDC personnel 

visit all primary wood-using mills within the State every 

3 years. They use questionnaires designed and supplied 

by MDC to determine the size and composition of the 

resources that are utilized by the State’s primary woodusing industry, its use of roundwood, and its generation 

and disposition of wood residues. Survey questions and 

reports refer to wood-use during the previous calendar year. 

Follow-up visits are made as needed in an effort to achieve 

a 100-percent response. Completed questionnaires are sent 

to MDC for data entry and then electronically forwarded 

to NRS for editing and processing. As part of data editing 

and processing, roundwood volumes are converted to 

standard units of measure using regional conversion factors. 

Timber removals by source of material and harvest residues 

generated during logging are estimated using factors 

developed from logging utilization studies previously 

conducted by NRS. Finalized data on Missouri’s industrial 

roundwood receipts are loaded into a national timber 

removals database along with data from TPO studies from 

other States to provide a complete assessment of Missouri’s 

timber product output.

Missouri Timber Price Data

MDC surveys Missouri foresters, loggers, and members of 

the forest industry on a quarterly basis to determine current 

price trends in the state. Survey response is voluntary and 

confi dential; MDC has no statutory or regulatory power to 

compel sale reporting. For this reason, most reported sales 

tend to be reported by professional foresters and the results 

must be interpreted with that caveat in mind. We surmise 

that forester-assisted sales, which tend to be inventoried, 

marked, and bid out, represent the upper range of prices paid 

for stumpage. MDC publishes the survey results quarterly 

as Missouri Timber Price Trends and makes the publication 

available to landowners and the forest industry in paper and 

on the web: http://mdc.mo.gov/forest/products/prices/index.

htm (Treiman and Tuttle 2006). Foresters turning in reports 

are free to lump species together in sale reports, and often 

do. Consequently, detailed price data for shortleaf pine is 

not available for all reporting periods.

RESULTS

Forest Inventory and Analysis Data

The 1972 Forest Inventory and Analysis plots in Missouri 

showed total annual removals of 167.7 million cubic feet 

(Spencer et al. 1976). Shortleaf pine accounted for 6.9 

million feet per year (4 percent of the total). About 30 

percent of the removals were from the Eastern Ozarks 

Forest Survey Unit (Table 1 and Figure 1). 

The results from the 1989 forest inventory in Missouri show 

6.8 million cubic feet of annual removals of shortleaf pine, 

representing about 6 percent of the 116.6 million cubic feet 

of total annual removals of all species in the State. The 

inventory found that over half (53 percent) of the removals 

came from the Eastern Ozarks unit with the rest coming 

from the Southwest Ozark unit. About two-thirds of the 

removals were from National Forest land with most of 

the remainder coming from private lands. Between 1972 

and 1989, there was an average net annual growth of 19.6 

million cubic feet of shortleaf pine. Sixty-two percent of 

Figure 1.—A map of the FIA analysis units for Missouri. 

Counties with tree symbols had shortleaf pine or shortleaf 

pine/oak forest types in the 2000-2004 FIA inventory.
181

the growth occurred in the Eastern Ozarks unit with most 

of the rest coming from the Southwest Ozark unit. Some 

net growth also occurred in the Northwest Ozarks and 

Riverborder units (Spencer et al. 1992).

Results from the 1999-2003 annual inventory show an 

increase of annual removals of shortleaf pine to 8.6 million 

cubic feet, but shortleaf pine still makes up around 7 percent 

of the total 118.6 million cubic feet of annual removals in 

the state. Almost 40 percent of the removals were in the 

Eastern Ozarks unit. Average net annual growth was 18.5 

million cubic feet for shortleaf pine. About 60 percent of 

the growth occurred in the Eastern Ozarks unit (Moser et al. 

2007). Table 1 also shows results labeled “2004”, based on 

the continuing annual FIA plots. For removals, the fi gures 

vary widely from the “2003” fi gures (based on 5 years of 

plots, 1999-2003) and those labeled “2004” because they 

represent only a 20 percent sample—those plots measured 

in 1999 and remeasured in 2004.

In addition, FIA plot data can be analyzed to show growth 

and removals by public and private ownerships, and acreage 

in each ownership category (see Table 2). Note that although 

83 percent of timberland in Missouri was privately owned 

(1999-2003) and 85 percent of all growth of growing stock 

volume occurred on that private land, only 45 percent of 

shortleaf pine growth occurred on private land. Similarly, 

although 69 percent of all removals came from private 

land only 55 percent of shortleaf pine removals were from 

private land. These fi ndings accord with overall volume on 

private land: 8 percent of all growing stock volume was on 

private land while only 42 percent of shortleaf pine growing 

Table 1.—Average net annual growth and average annual removals of shortleaf pine on timberland by survey year and Forest 

Survey Unit, Missouri (in thousand cubic feet).

na = Not available

1

Converted from cords at 79 cubic feet per cord.

2

From Forest Inventory Mapmaker version 2.1 at: http://www.ncrs2.fs.fed.us/4801/FIADB/index.htm

Forest Inventory Unit

 Eastern Southwestern Northwestern

 Total Ozarks Ozarks Ozarks Riverborder

 Pct. of

Survey Year Growth Removals Growth Growth Removals Growth Removals Growth Removals Growth Removals

19591 15,642 5,000 32% na na na na na na na na

19721

 10,718 6,854 64% 8,241 2,060 2,256 4,704 141 3 79 88

1989 19,618 6,788 35% 12,138 3,613 5,761 3,175 1,432 -- 287 --

1999-20032

 18,480 8,560 46% 11,028 4,513 5,500 4,047 1,798 -- 155 --

2000-20042 25,094 5,059 20% 17,842 3,864 6,925 1,195 -- -- 327 --

Table 2.—Removals, growth, and growth removed by ownership type (percent of cubic foot volume).

Inventory Year and Species

 1999-2003 2000-2004

 All Species Shortleaf Pine All Species Shortleaf Pine 

Removals Private Land 69% 55% 83% 90%

 Public Land 31% 45% 17% 10%

Growth Private Land 85% 45% 82% 48%

 Public Land 15% 55% 18% 52%

Removals/Growth Private Land 15% 56% 31% 38%

 Public Land 39% 38% 28% 4%

 Overall 19% 46% 30% 20%
182

stock volume was on private land. Given these volume 

percentages growth and removals fi gures for shortleaf pine 

by ownership are not surprising. In addition, FIA plots show 

that in both 1989 and 1999-2003 most of the removals came 

from the medium- and small-size classes.

Timber Product Output Data

In TPO surveys conducted between 1969 and 2003, total 

production of industrial roundwood in Missouri ranged 

from a low of 87.6 million cubic feet (1980) to 139.6 

million cubic feet (1997). During this period, shortleaf 

pine remained in the top fi ve species harvested, peaking at 

number three from 1987 to 1997. In 2000, shortleaf pine 

fell to the fourth most harvested species. Red and white 

oaks have always had much higher harvest levels. The total 

harvest of shortleaf pine varied from a low of 4.0 million 

cubic feet in 1969 to a high of 8.9 million cubic feet in 1991 

(Table 3).

The Eastern Ozark Unit has historically contained most 

of the harvest volume of shortleaf pine in the State. The 

highest harvest in the region was 6.5 million cubic feet in 

1994, about 80 percent of all shortleaf pine harvested that 

year. The low came in 2003, 3.4 million cubic feet or 75 

percent of the total shortleaf pine harvest for that year. Since 

1980, the Southwestern Ozark Unit has had the second 

highest shortleaf pine volume harvested, with an average of 

just over 20 percent of the State’s harvest.

Historically, more than 95 percent of the shortleaf pine 

harvested in Missouri was processed in Missouri and the 

majority has been used for sawlogs. The percentage used 

for other purposes (mostly posts) has varied from a low of 9 

percent in 1987 to a high of 34 percent in 1969. Since 1969, 

posts have remained as the second most processed product 

in the State using shortleaf pine. The production of poles 

from shortleaf pine reached its peak in the 1969 survey, and 

has since disappeared from TPO reports. This situation may 

change with the opening in 2006 of a pole mill near Licking, 

MO (John Tuttle, MDC Forest Products Supervisor, pers. 

commun. with the author).

In 1987, a logging utilization study was conducted which 

lets us estimate of the volume of industrial roundwood that 

is removed during harvest and the volume that is left on 

the ground as harvest residue. The volume of shortleaf pine 

harvest residues since 1987 has ranged from a high of 5.3 

million cubic feet in 1997 to a low of 3.1 million cubic feet 

in 2000. About two-thirds of the volume of the trees that are 

cut is utilized for products. Ninety percent of the volume 

that is utilized comes from growing stock sources (Blyth 

and Massengale 1972, Blyth et al. 1983, Smith and Jones 

1990, Hackett et al. 1993, Piva and Jones 1997, Piva and 

Treiman 2003, Treiman and Piva 2005). 

The most recent TPO data from 2003 were also used to 

compile a directory of Missouri’s primary wood processing 

mills which showed that 92 out of 444 processed some 

shortleaf pine (Jones et al. 2004).

Missouri Timber Price Data

Stumpage prices for shortleaf pine sawlogs have ranged 

between $90 and $155 per International 1⁄4” MBF, according 

to sales reports collected for Missouri Timber Price Trends. 

Fence post prices have ranged between $0.20 and $0.65 per 

post over the same period (see Figure 2).

Combining the TPO results with these price data allows 

the calculation of the total value of all shortleaf pine sales, 

assuming that all landowners receive the forester-assisted 

Table 3.—Total industrial roundwood production and shortleaf pine industrial roundwood production by year and Forest Survey 

Unit, Missouri (in thousand cubic feet).

na = Not available

 Shortleaf Pine Production

Forest Inventory Unit

 Total Pct. of

 Survey Total Shortleaf Total Eastern Southwestern Northwestern 

 Year Roundwood Pine Roundwood Ozarks Ozarks Ozarks Prairie Riverborder

 1969 123,546 4,023 3.2% na na na na na

 1980 87,558 5,450 6.2% 3,642 1,633 88 0 87

 1987 99,932 7,114 7.1% 5,860 1,153 55 0 46

 1991 121,392 8,865 7.3% 5,520 2,790 54 0 501

 1994 132,593 8,127 6.1% 6,472 1,489 132 12 23

 1997 139,643 8,723 6.2% 6,022 2,380 209 0 112

 2000 128,974 5,239 4.1% 4,496 652 64 0 27

 2003 128,106 4,560 3.6% 3,442 869 84 17 147
183

prices represented by the Missouri Timber Price Trends

data. The Missouri Timber Price Trends reports prices for 

sawlogs, posts, and pulpwood. Volumes for these species 

and products are also reported in the TPO surveys. The 

value of shortleaf pine products peaked in the 1990s at $7.5 

million. After 1997, the value of the shortleaf pine harvest 

has continued to fall to the 2003 level of $3.5 million. These 

values are in Figure 3 as the line labeled “production”. All 

annual totals have been converted into 2006 dollars.

Using FIA data, the potential value for the shortleaf pine 

resource in Missouri can be calculated. Assuming the 

maximum sustainable cut would be no more than total 

annual growth, and the highest value (price) is for the 

highest value product, which proves to be sawlogs, a 

theoretical upper bound to the sustainable total value of 

shortleaf pine can be calculated (Fig. 3). 

Shortleaf Pine Prices

$0

$40

$80

$120

$160

$200

1994 1996 1998 2000 2002 2004 2006

Year

Sawlogs - Avg.

Price/Int.-MBF

$0.00

$0.20

$0.40

$0.60

$0.80

Fence Posts - Avg.

Price/Each

Sawlogs Fence Posts

Figure 2.—Shortleaf pine prices for sawlogs (Int-MBF) and fence posts (each) in Missouri. Prices are based on reports received 

for the Missouri Timber Price Trends publication. These reports are voluntary and come from sales assisted by a professional 

forester. As such, the price trends shown tend towards the price for a well planned sale that is bid out to multiple loggers. (Prices 

were not available for posts from 2004-2006.)

Past, Present, and Potential Values of SLP Production

$0

$5

$10

$15

$20

$25

1970 1975 1980 1985 1990 1995 2000 2005

Millions

Year

Value (at TPT prices)

Production Potential

Figure 3.—Calculated present values of shortleaf pine industrial roundwood production1 and potential production2 in Missouri by 

year. 

1

Production is the value of product based on products and volumes harvested from TPO studies and Missouri Timber Price Trends reports in 

2006 dollars.

2

Potential is based on the maximum sustainable cut, which would be no more than total annual growth, and the highest value (price) for the 

highest value product.
184

DISCUSSION

From a low point in the early 20th century, shortleaf pine 

has been making a slow return to Missouri’s forests. To 

date, more of this return (growth) has occurred on public 

land than on private land (Table 3). If shortleaf pine is to 

return to its historical prominence as a component of both 

the state’s biodiversity and its economy, the role of private 

landowners will take on ever greater importance. Financial 

incentives are of paramount importance to many private 

forest landowners, so profi table markets for shortleaf pine 

will also be essential to the species’ return.

Shortleaf pine is growing faster than it is being harvested 

in Missouri, a clear indicator of sustained yield. Shortleaf 

pine’s rate of growth increased dramatically between 1972 

and the 1999-2003 and the 2000-2004 FIA inventories. In 

1972, 64 percent of shortleaf pine growth was removed, 

while for the 1989, the 1999-2003 and the 2000-2004 FIA 

inventories this percentage varied between 20 percent and 

46 percent. For all species combined 30 percent of growth 

is being removed. Utilization of shortleaf pine is relatively 

high compared to all other species.

The 1999-2003 inventory estimates removals of shortleaf 

pine occur disproportionately on private land; 56 percent 

of private land shortleaf pine growth is being removed 

compared with 38 percent on public land. The 2000-2004 

inventory estimates removals of shortleaf pine of only 4 

percent of public land shortleaf pine growth compared with 

38 percent on private land. (Note the high variation between 

the two, in part because of the earlier mentioned issues 

with switching inventory systems.) Many factors contribute 

to forest utilization, including markets, availability, and 

operability. The lower rate of utilization (as a percentage 

of growth) on public lands may indicate that public lands 

managers may have a valuable role to play in helping 

develop and improve markets for shortleaf pine. The higher 

rate of utilization of shortleaf pine on private lands may 

indicate that private forest landowners will be willing to 

take advantage of such markets for the product. Our rough 

calculation of the upper bound, “potential”, also shows that 

the full economic benefi ts that might be reaped from this 

softwood are not yet being realized by landowners and as 

such, shortleaf pine may not be a fully thought-out part of 

many land management plans.

These results suggest a potentially fruitful area for further 

research: How does shortleaf pine potential (as defi ned in 

this paper) compare to that of other commercial species in 

the state? What is the relative economic position of shortleaf 

pine? Answers to these questions may help professional 

foresters working with private landowners to better 

understand why shortleaf pine is not in many management 

plans, and how to get it there. Some of this work may 

best be accomplished after another full 5-year annualized 

inventory is complete, allowing for more precise estimates 

of growth and removals. 

LITERATURE CITED

Blyth, J.E.; Jones, S.G.; Smith, W.B. 1983. Primary forest 

products industry and timber use, Missouri, 1980. 

Resour. Bull. NC-71. St. Paul, MN: U.S. Department 

of Agriculture, Forest Service, North Central Forest 

Experiment Station. 22 p.

Blyth, J.E.; Massengale, R.A. 1972. Missouri’s primary 

forest products output and industries, 1969. Resour. 

Bull. NC-16. St. Paul, MN: U.S. Department of 

Agriculture, Forest Service, North Central Forest 

Experiment Station. 19 p.

Gwaze, D. 2005. Shortleaf Pine (Pinus echinata Mill.): A 

selected bibliography. Jefferson City, MO: Missouri 

Department of Conservation. 24 p.

Hackett, R.L.; Jones, S.G.; Piva, R.J. 1993. Missouri timber 

industry: an assessment of timber product output and 

use, 1991. Resour. Bull. NC-15. St. Paul, MN: U.S. 

Department of Agriculture, Forest Service, North 

Central Forest Experiment Station. 46 p.

Jones, S.; Hauser, C.; Brookshire, B.; Foster, H. 2004. 

Missouri forest industry 2004 – directory of primary 

wood processors. Jefferson City, MO: Missouri 

Department of Conservation. 45 p.

Mangold, R.D. 1998. Forest health monitoring fi eld methods 

guide (National 1998). Research Triangle Park, NC: 

U.S. Department of Agriculture, Forest Service, 

National Forest Health Monitoring Program. 429 p. 

(Revision 0, April 1998)

McRoberts, R.E. 1999. Joint annual forest inventory and 

monitoring system, the North Central perspective. 

Journal of Forestry. 97(12): 27-31.

Miles, Patrick D. 2006. Forest inventory mapmaker webapplication version 2.1. St. Paul, MN: U.S. Department 

of Agriculture, Forest Service, North Central Research 

Station. Available only on internet: www.ncrs2.fs.fed.

us/4801/fi adb/index.htm

Missouri Department of Conservation. 2005. Eleven 

Point Hills Conservation Opportunity Area. [Online]. 

Available: http://www.mdc.mo.gov/documents/coa/31.

pdf [accessed June, 2006]. 

Moser, W.K.; Hansen, M.H.; Treiman, T.B.; Jepsen, E.; 

Leatherberry, E.C.; Liknes, G.; Olson, C.; Perry, C.H.; 

Piva, R.J.; Woodall, C.W.; Brand, G.J. 2006. Missouri’s 

forests 1999-2003. Resour. Bull. NRS-10. Newtown 

Square, PA: U.S. Department of Agriculture, Forest 

Service, Northern Research Station. 79 p.
185

Moser, W.K.; Treiman, T.B.; Moltzan, B.; Lawrence, R.; 

Brand, G.J. 2005. Missouri’s forest resources in 2003. 

Resour. Bull. NC-243. St. Paul, MN: U.S. Department 

of Agriculture, Forest Service, North Central Research 

Station. 42 p.

Palmer, B. 2000. Back from the ashes. Missouri 

Conservationist. October, 2000.

Piva, R.J.; Jones; S.G. 1997. Missouri timber industry—an 

assessment of timber product output and use, 1994. 

Resour. Bull. NC-184. St. Paul, MN: U.S. Department 

of Agriculture, Forest Service, North Central Forest 

Experiment Station. 54 p.

Piva, R.J.; Jones, S.G.; Barnickol, L.W.; Treiman, T.B. 

2000. Missouri timber industry—an assessment of 

timber product output and use, 1997. Resour. Bull. 

NC-197. St. Paul, MN: U.S. Department of Agriculture, 

Forest Service, North Central Research Station. 53 p.

Piva, R.J.; Treiman, T.B. 2003. Missouri timber industry—

an assessment of timber product output and use, 2000. 

Resour. Bull. NC-223. St. Paul, MN: U.S. Department 

of Agriculture, Forest Service, North Central Research 

Station. 75 p.

Spencer, J.S.; Essex, B.L. 1976. Timber in Missouri, 1972. 

Resour. Bull. NC-30. St. Paul, MN. U.S. Department 

of Agriculture, Forest Service, North Central Research 

Station. 115 p.

Spencer, J.S.; Roussopoulos, Sue M.; Massengale, Robert 

A. 1992. Missouri’s forest resource, 1989: an analysis. 

Resour. Bull. NC-139. St. Paul, MN: U.S. Department 

of Agriculture, Forest Service, North Central Forest 

Experiment Station. 84 p.

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an assessment of timber product output and use. 

Resour. Bull. NC-120. St. Paul, MN: U.S. Department 

of Agriculture, Forest Service, North Central Forest 

Experiment Station. 51 p.

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dwindling shortleaf. Missouri Conservationist. 

December, 2001. 

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an assessment of timber product output and use, 2003. 

Resour. Bull. NC-250. St. Paul, MN: U.S. Department 

of Agriculture, Forest Service, North Central Research 

Station. 74 p.

Treiman, T.B.; Tuttle, J. 2006. Missouri timber price 

trends. Jefferson City, MO: Missouri Department of 

Conservation. 8 p.

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MO: Missouri Department of Conservation. 34 p. 
186

FINANCIAL RATES OF RETURN ON SHORTLEAF PINE STANDS 

IN ARKANSAS BETWEEN 1978 AND 1995

Andrew J. Hartsell1

ABSTRACT.—The objectives of this study are to estimate the annual rate of change in 

value of Arkansas’ shortleaf pine forests using fi nancial maturity concepts and to compare 

it to the change in other forest types and alternative investment options. Timber Mart-South 

stumpage price data were combined with inventory data spanning 17 years from the USDA 

Forest Service, Southern Research Station, Forest Inventory and Analysis (FIA) unit. Two 

distinct FIA survey periods were utilized, resulting in a study period ranging from 1978 to 

1995. The average annual real rate of return on all Arkansas timberland investments during 

this time frame was 5.8 percent using simple fi nancial maturity and 3.3 percent using adjusted 

fi nancial maturity. Stands comprising primarily of shortleaf pine outperformed these state 

averages during this period, averaging 6.5 percent and 3.9 percent annually using simple and 

adjusted fi nancial maturity models, respectively. Average annual rates of change in value were 

computed and compared for shortleaf pine and four other forest-type groups. Additionally, 

comparisons were made between forest type and ecoregion to determine which scenario 

produced the maximum rate of return. The highest earning shortleaf stands were found in the 

Arkansas Valley section of the State, with value changes of 8.2 percent per year for the simple 

fi nancial maturity model and 6.9 percent per year for the adjusted model.

1

Research Forester, Forest Inventory and Analysis, Southern 

Research Station, USDA Forest Service, 4700 Old Kingston Pike, 

Knoxvillle, TN 37919. To contact call (865) 862-2032 or email at 

ahartsell@fs.fed.us

INTRODUCTION

Historically, shortleaf pine (Pinus echinata Mill.) 

ecosystems have played an important role in Arkansas forest 

lands, supporting hundreds of plant and animal species. 

Because of its many timber, nontimber, and ecosystem 

benefi ts, there is strong interest in maintaining and restoring 

shortleaf pine ecosystems. For this to happen, shortleaf 

pine must be viewed as a viable fi nancial investment 

by forest managers and landowners, particularly the 

private landowners who control 58 percent of the state’s 

timberlands (Rosson 2002). 

This study investigates biological and fi nancial growth 

rates of undisturbed stands in Arkansas by applying Timber 

Mart-South (TMS) stumpage prices to Forest Inventory 

and Analysis (FIA) sample trees. Each FIA sample tree 

was assigned a dollar value based on species, size, and 

condition. Saw-log trees were divided into multiple products 

(saw log and topwood) and rough cull trees were treated as 

pulpwood. The tree values were summed for each plot to 

derive the total plot stumpage value in dollars per acre. 

STUDY AREA

The study area consists of the 75 counties of Arkansas, 

with the emphasis on timberlands. Timberland is defi ned 

as land that is at least 10 percent stocked by trees of any 

size, or formerly having such tree cover, and not currently 

developed for nonforest uses (Fig. 1). Minimum area 

considered for FIA classifi cation and measurement is 1 acre.

Figure 1.—Ecoregions (by section) of Arkansas (Bailey 

1996).
187

METHODS

Two time periods coinciding with FIA surveys of Arkansas 

were investigated: 1978-1988 and 1989-1995. Plots had 

to meet the selection for both time periods in order to be 

included in the study.

Plot Selection

Value change computations require input from two points 

in time. Therefore, when the 1978-1995 period is discussed, 

1978-1988 is time 1 and 1989-1995 is time 2.

All plots must be classifi ed as forested for all survey 

periods in question. All time 2 plots must be classifi ed 

as saw log-size stands, while time 1 plots may be either 

poletimber-size or sawtimber-size stands. Stands classifi ed 

as seedling/sapling in either survey are omitted. All time 2 

stands must have at least 5,000 board feet per acre. Several 

plots classifi ed with forest types of elm-ash-cottonwood 

were excluded because of insuffi cient sample size (less than 

10 plots for each survey period). All stands with evidence 

of management, disturbance, or harvesting for the survey 

periods in question, as well as the previous survey period, 

were excluded. This exclusion was necessary, as total plot 

values and volumes depend on the inventory of the stand 

when visited by cruisers. In almost every case, stands 

had less volume and value after undergoing management 

practices such as thinnings. Therefore, these stands are 

dropped from the study and only those stands that remained 

relatively undisturbed were included. A total of 330 plots 

met the selection criteria (Table 1).

Tree Selection

All live trees greater than or equal to 5.0 inches diameter 

at breast height (DBH) were included in the sample 

set, except rotten cull trees. Rough cull tree volumes 

were given pulpwood value. No cull trees were used in 

sawtimber computations. Tree selection was performed 

by variable radius sampling (37.5 basal area factor). Since 

tree selection was performed by variable radius sampling, 

new trees appear over time. These new trees were included 

in all computations and therefore affect growth and value 

changes. Trees that died between survey periods were 

included only in the survey year(s) in which they were 

alive. This approach could create negative biological and 

economic value growth between surveys.

Timber Mart-South Data

This study uses TMS price data to calculate individual 

tree values. TMS has been collecting delivered prices and 

stumpage prices for 11 southern states since December 

1976. All TMS price data are nominal. Real prices were 

calculated using the U.S. Bureau of Labor Statistics all 

commodities producer price index. As 1987 was the 

midpoint of the study period, all TMS prices were infl ated/

defl ated to 1987 levels.

Tree Products and Values

The algorithm used for determining tree products was: 1) all 

poletimber-size trees are used for pulpwood; 2) the entire 

volume of rough cull trees, even sawtimber-size trees, is 

Table 1.—Average annual biological growth percent (BGP)1, real timber value growth percent (TVG)2, and real forest value 

growth percent (FVG)3 by forest type, Arkansas 1978-1995.

1

The average annual change in volume expressed as a percentage.

2

The unadjusted annual real rate of return.

3

The adjusted annual real rate of return uses land value to account for opportunity costs.

Land Value

Dollars per Acre 

Forest Type N BGP TVG 250 500 750 1000 1250 1500

percent

Loblolly pine 11 4.92 8.47 6.99 6.06 5.39 4.88 4.47 4.13

Shortleaf pine 54 3.22 6.50 5.26 4.49 3.94 3.53 3.19 2.92

Shortleaf pine-oak 35 2.38 5.04 4.11 3.50 3.05 2.71 2.44 2.22

Loblolly-hardwood 18 3.40 7.70 5.95 4.96 4.29 3.79 3.41 3.10

Oak-hickory 122 2.50 5.72 4.31 3.53 3.01 2.63 2.34 2.12

Oak-gum-cypress 90 2.28 5.07 4.13 3.52 3.09 2.76 2.49 2.28

Statewide 330 2.67 5.80 4.57 3.84 3.34 2.96 2.66 2.42
188

used for pulpwood; 3) the saw-log section of sawtimbersize trees is used for sawtimber; and 4) the section between 

the saw-log top and 4-inch DOB pole top is used for pulp 

and often referred to as topwood. Poletimber-size trees are 

softwoods 5.0 to 8.9 inches DBH and hardwoods 5.0 to 10.9 

inches DBH. Sawtimber-size trees are all softwoods that are 

at least 9.0 inched DBH and hardwoods that are at least 11.0 

inches. Cull trees are trees that are less than one-third sound.

In 1981, TMS began to report southern pine chip-n-saw 

prices. Therefore, the two survey periods after this time 

included a third product, southern pine chip-n-saw. Chipn-saw trees are southern pines 9.0 to 12.9 inches DBH. All 

trees less than 9.0 inches are still treated as pulpwood, and 

trees greater than or equal to 13.0 inches DBH are treated as 

sawtimber trees. This modifi cation was made for the 1988 

and 1995 survey periods. 

FIA traditionally computes all board foot volumes in 

International 1/4-inch log rule. Most of the TMS price data 

is in Doyle log rule. To accommodate the price data, all FIA 

tree volumes were recalculated using the Doyle formula. In 

a few instances, prices are reported in Scribner log rule. To 

accommodate this, the Doyle prices for these few instances 

were converted to Scribner prices by multiplying the Doyle 

price by 0.75 (Timber Mart-South 1996).

The TMS reports include a low, high, and average price 

for standing timber for various products. This report does 

not consider peeler logs or poles and piling as possible 

products because determining these products from FIA 

data is questionable. Omitting these classes allows for a 

slightly conservative approach to estimating tree and stand 

value. FIA data contain information on species, product 

size (poletimber or sawtimber), and quality (tree class and 

tree grade). Prices for each section of the tree were assigned 

based on these factors. These prices were then applied to the 

different sections of a tree. 

Growth Models

Timber volumes and values are summed for each plot. These 

totals are then used as inputs for the growth models. Three 

growth models were used in this study. Each is based on the 

formula used in determining average annual change. 

Timber value growth (TVG) is a simple fi nancial maturity 

model that considers only the actual change in value for a 

plot for the survey period in question. Incomes derived from 

future stands are ignored (Hartsell 1999). The basic formula 

for TVG is: 

TVG = [(TVF/TVP)

1/t – 1] * 100

where 

TVG = timber value growth percent

TVF = ending sum of tree value on the plot at time 2 

TVP = beginning sum of tree value on the plot at time 1

t = number of years between surveys

Forest value growth (FVG) includes the value of land in 

the computation of economic value change (Hartsell). The 

formula for FVG is:

FVG = [((TVF + LVF) / (TVP + LVP))1/t – 1] * 100

where 

FVG = forest value growth percent

TVF = ending sum of tree value on the plot at time 2 

LVF = ending land value

TVP = beginning sum of tree value on the plot at time 1

LVP = beginning land value

t = number of years between surveys

FVG is an adjusted fi nancial maturity model. Adjusted 

fi nancial maturity concepts account for all implicit costs 

associated with holding timber. These are sometimes 

referred to as opportunity costs. In doing so, revenues from 

future stands are accounted for. One method of adjusting 

the model is to include bare land value (LV) in the equation, 

because bare LV accounts for future incomes and the 

inclusion of LV adjusts the simple fi nancial maturity model. 

This study computes multiple FVGs using LVs ranging from 

$250 per acre to $1500 per acre in $250 increments.

Biological growth percent (BGP) is similar to TVG, except 

it uses timber volumes instead of timber values. The BGP 

model accounts for the actual annual change in tree volume 

for a plot over a survey period. The BGP model is the same 

as the TVG model, except it uses the sum of tree volumes 

on the plot instead of the sum of tree values (Hartsell 1999).

RESULTS AND DISCUSSION

Initial investigations analyzed value growth based on 

various plot strata such as county, ownership, and forest 

type. Table 1 details the sample size, BGP, TVG, and FVG 

of Arkansas timberlands by forest type. FVG is computed in 

$250 increments ranging from $250 to $1,500. This sample 

set is more likely to represent true trend for the extended 

period as it contains only plots that met the selection criteria 

for all three surveys. All fi nancial rates of return are real, 

meaning that infl ation has been removed, and all returns are 

over and above infl ation. Table 1 reveals that loblolly pine 

(Pinus taeda L.) stands outperformed all other stands in 

terms of biological and economic growth. Average loblolly 

stand volume increased 4.9 percent per year, while these 

stands earned nearly 8 percent per year using the simple 

model. The adjusted rates of return for mature loblolly 

stands ranged from 4.1 percent to almost 7 percent per year, 

depending on land value. 

While stands comprising primarily shortleaf pine generally 

failed to outperform loblolly pine, it is not to the degree that 

many would expect. Additionally, shortleaf pine stands grew 

at a faster rate (3.2 percent) than the statewide average (2.7 

percent). Shortleaf pine stands outperformed the statewide 

averages in terms of economic rates of return as well. 
189

Shortleaf pine stands earned 6.5 percent per year using the 

simple fi nancial maturity model, while the statewide average 

for all stands was 5.8 percent. The same pattern holds true 

for the adjusted model at all land values.

Landowners may use Table 1 as a guideline for the rates 

they might expect to earn on their timberlands if they know 

the value of their land or nearby parcels. They should use 

an estimate representing the average land value of their 

tract for the time period. Table 1 illustrates the effect 

that land value has upon rates of return and management 

decisions. The interaction of land value and timber value is 

an interesting dynamic. As land value increases, the rate of 

return decreases. There may come a point where land value 

will play a greater role than timber values in determining 

land use. 

Another avenue of investigation involves stratifying value 

change not on a plot or condition level variable such as 

ownership or forest type, but on ecoregion. Bailey (1966) 

classifi ed six different ecoregions for the State (Fig. 1). The 

Arkansas Valley section proved to have the highest rates of 

return, both biologically and economically. Stands in this 

section grew on average 3.3 percent per year and earned 

almost 7 percent per year using the simple model and 4 

percent per year using the adjusted model with a $750 per 

acre land value (Table 2). The Ozark Highlands section was 

the second fastest growing region, growing 2.9 percent per 

year. However, this section’s economic performance did 

not refl ect its growth rates. This section was ranked third 

in terms of TVG and last in FVG for a number of reasons, 

including species, quality, tree size, and possible products.

Stratifying the data by both forest type and ownership 

reveals that shortleaf pine is generally the best performing 

forest type in those ecoregions where loblolly pine is 

absent. In fact, the Mid Coastal Plains section is the only 

ecoregion where there is more than one pure loblolly stand 

in the data set (Table 3). Shortleaf pine stands are the 

top ranked species in the Arkansas Valley section in both 

biological and fi nancial growth. And while shortleaf pine 

stands are only ranked third in both BGP and FVG in the 

Ouachita Mountains section, the top two types, loblollyhardwood and oak-gum-cypress, have only two and three 

plots, respectively, in the data set. The 4.6 percent FVG for 

shortleaf pine stands in the Arkansas Valley section is the 

second highest annual rate of return of any forest type that 

has at least fi ve plots in any ecoregion. 

Comparing the rates of return from timberlands to other 

investment options yields interesting results (Table 4). 

Using the simple fi nancial maturity model (TVG), shortleaf 

pine stands outperforms all other investment options except 

the Dow Jones Industrial Average and the S&P 500 Stock 

Index. The results differ, however, when using the adjusted 

model. Arkansas’ shortleaf pine timberlands continue to 

rank higher than certifi cates of deposits and U.S. Treasury 

Bills, but fail to match the returns found in stocks and 

bonds. However, the 3.9 percent real annual rate of return 

on shortleaf stands for this period occurred on unmanaged 

stands. It is important to note that forest management has 

the potential to increase the earnings on these lands.

This study did not consider the effects of taxes. The impacts 

of taxes paid or tax exemptions for the various investment 

options were not taken into account. These have the 

potential to affect the fi nal rates of return. The stands must 

be completely liquidated to meet the specifi ed rate of return. 

The landowner maintains possession of the land. Income 

from selling the land is not included. Bare LV change over 

time is not considered. The purpose for holding LV constant 

is to help determine the rate of return from the timber on the 

Table 2.—Average annual biological growth percent (BGP)1, real timber value growth percent (TVG)2, and real forest value 

growth percent (FVG)3

 by ecoregion, Arkansas 1988-1995.

1

The average annual change in volume expressed as a percentage.

2

The unadjusted annual real rate of return.

3

The adjusted annual real rate of return with land value = $750 per acre.

Bailey’s ecological section N BGP TVG FVG

Arkansas Valley 41 3.35 6.96 3.95

Boston Mountains 56 2.42 5.62 3.02

Mid Coastal Plains 72 2.82 6.43 3.83

Mississippi Alluvial Basin 68 2.33 4.94 2.98

Ouachita Mountains 65 2.57 5.36 3.26

Ozark Highlands 28 2.89 5.89 2.85
190

Table 3.—Average annual growth percent (BGP)1, real timber value growth percent (TVG)2, and real forest value growth percent 

(FVG)3

 by forest type and ecoregion, Arkansas 1988-1995.

1

The average annual change in volume expressed as a percentage.

2

The unadjusted annual real rate of return.

3

The adjusted annual real rate of return with land value = $750 per acre.

Forest type N BGP TVG FVG

percent

Arkansas Valley Section

Shortleaf pine 20 4.10 8.18 4.60

Shortleaf pine-oak 7 1.86 4.45 2.75

Oak-hickory 8 3.27 6.63 3.79

Oak-gum-cypress 6 2.65 6.23 3.36

Boston Mountains Section

Shortleaf pine 2 3.43 7.51 4.32

Shortleaf pine-oak 4 4.14 7.99 4.26

Oak-hickory 50 2.25 5.35 2.87

Mid Coastal Plains Section

Loblolly pine 9 4.97 8.51 5.50

Shortleaf pine 1 4.21 5.99 4.49

Shortleaf pine-oak 2 1.48 5.66 3.27

Loblolly-hardwood 15 3.36 7.56 4.25

Oak-hickory 17 2.44 5.93 3.45

Oak-gum-cypress 28 2.12 5.54 3.33

Mississippi Alluvial Basin Section

Loblolly pine 1 4.65 7.35 3.23

Shortleaf pine-oak 1 0.73 4.05 2.66

Loblolly-hardwood 1 2.51 7.96 3.86

Oak-hickory 14 2.54 6.35 3.47

Oak-gum-cypress 51 2.25 4.46 2.84

Ouachita Mountains Section

Shortleaf pine 30 2.62 5.37 3.48

Shortleaf pine-oak 18 2.14 4.47 2.82

Loblolly-hardwood 2 4.10 8.63 4.77

Oak-hickory 12 2.82 5.91 3.00

Oak-gum-cypress 3 2.56 6.33 3.85

Ozark Highlands Section

Loblolly pine 1 4.72 9.21 6.60

Shortleaf pine 1 2.10 5.33 3.26

Shortleaf pine-oak 3 3.82 5.83 3.54

Oak-hickory 21 2.66 5.53 2.42

Oak-gum-cypress 2 3.44 8.41 4.26
191

tract. Including changing land values is a study in real estate 

or land plus timber. Landowners and resource mangers need 

to know if managing for timber is a wise investment option 

for their holdings. 

Regeneration costs, and other silvicultural practices, 

are excluded from the analysis as well. Returns from 

intermediate harvests, thinning, and costs of land 

improvements are not included. Therefore, foresters and 

land managers have the potential to improve upon these 

rates through species selection, intermediate practices, and 

fi nal products the stands produce. 

The results of this study indicate that shortleaf pine stands 

can be profi Table. In certain areas of the State, the Arkansas 

Valley section in particular, shortleaf appears to be the 

species of choice. This observation is particularly true when 

one considers that the rates discussed were from unmanaged 

stands and do not include changes in land value. Both of 

these factors have the potential to greatly improve upon 

the fi nancial gain and make Arkansas’ shortleaf pine stands 

competitive with other investment options.

Table 4.—Average annual real rates of return, expressed 

as a percentage, for Arkansas timberlands and alternative 

investment option, 1978-1995.

1

The unadjusted annual real rate of return.

2

The adjusted annual real rate of return with land value = $750 

per acre.

 Average annual

Investment options rate of return

Timber value growth percent (TVG)1 – 

all stands 5.80

Forest value growth percent (FVG)2

 – 

all stands 3.34

Timber value growth percent (TVG)1 – 

shortleaf stands 6.50

Forest value growth percent (FVG)2 – 

shortleaf stands 3.94

1-month certifi cate of deposit 2.68

6-month certifi cate of deposit 2.89

1-month treasury bill 2.10

6-month treasury bill 2.09

AAA corporate bonds 4.40

Dow Jones industrial average 5.61

S&P 500 stock index 5.92

LITERATURE CITED

Bailey, R.G. 1996. Ecosystem geography. New York: 

Springer-Verlag. 216 p.

Hartsell, Andrew J. 1999. Financial rates of return on 

timberlands in Mississippi between 1977 and 1994. 

Starkville, MS: Mississippi State University. 84 p. 

M.S. thesis.

Rosson, James F., Jr. 2002. Forest resources of Arkansas, 

1995. Resour. Bull. SRS-78. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, Southern 

Research Station, 82 p. 

Timber Mart-South. 1978. Arkansas stumpage prices, 1st 

quarter 1978. Athens, GA: Daniel B. Warnell School of 

Forest Resources, University of Georgia.

Timber Mart-South. 1988. Arkansas stumpage prices, 1st 

quarter 1988. Athens, GA: Daniel B. Warnell School of 

Forest Resources, University of Georgia.

Timber Mart-South. 1996. Arkansas stumpage prices, 1st 

quarter 1996. Athens, GA: Daniel B. Warnell School of 

Forest Resources, University of Georgia.

U.S. Bureau of Labor Statistics. Producer Price Index. 

[online]. Available at ftp://ftp.bls.gov/pub/time.series/

wp/wp.data.1.AllCommodities. 
192

BRANCH AND FOLIAGE BIOMASS RELATIONS 

FOR SHORTLEAF PINE IN SOUTHEAST OKLAHOMA

Charles O. Sabatia, Thomas B. Lynch, and Rodney E. Will1

1

Graduate Research Assistant (COS), Department of Natural 

Resource Ecology and Management, Oklahoma State University, 

008C Agricultural Hall, Stillwater, OK 74078; Professor (TBL), 

Department of Natural Resource Ecology and Management, 

Oklahoma State University, 008C Agricultural Hall, Stillwater, 

OK 74078; and Associate Professor (REW), Department of 

Natural Resource Ecology and Management, Oklahoma State 

University, 008C Agricultural Hall, Stillwater, OK 74078. TBL is the 

corresponding author: to contact call (405) 744-5447 or email at 

tom.lynch@okstate.edu

EXTENDED ABSTRACT

Data from 36 shortleaf pine trees, sampled from thinning 

study plots in even-aged naturally regenerated shortleaf pine 

forests in Southeast Oklahoma, were used to fi t tree branch 

and foliage biomass equations. In 1989 sample plots were 

thinned to 50 percent stocking or 70 percent stocking, with 

the remainder as unthinned controls; basal areas ranged 

from about 16 m2/ha to 44 m2/ha. Three hundred seventy 

branches sampled on the basis of one branch per whorl, 

and the terminal branch, on the 36 trees, were used to fi t 

regression equations to predict branch wood and branch 

foliage biomass. The best equations are shown in Table 1, 

with parameters fi tted by weighted nonlinear regression 

using SAS PROC NLIN (SAS Institute). The variables in 

these equations were selected from the log-transformed 

form of the model 

w = b0

db1Rb2 Sb3

using stepwise selection procedure of SAS PROC REG 

(SAS Institute). In this model, w is the branch or branch 

foliage dry weight in grams; d is the diameter at the base of 

the branch in centimeters; R is the relative branch height, 

in meters, obtained as (H – h) where h is height to the 

branch and H is the total height of the tree; S is the ratio 

(H/D) where D is the DBH of the tree in centimeters, and 

H is the total height of the tree, in meters; b0, b1, b2, and b3

are parameters. The model is that proposed by Ek (1979) 

for estimating branch weight and branch foliage weight in 

biomass studies.

Tree level estimates of branch and foliage biomass, obtained 

by summing up individual estimates obtained using the 

equations in Table 1, were regressed on tree dendrometric 

variables to obtain tree level branch and foliage biomass 

equations. Using stepwise selection procedure of SAS 

PROC REG (SAS Institute), to select variables from the 

log-transformed form of tree biomass models of the form 

w = b0

X1

b1X2b2...Xnbn, DBH alone was found to be the best 

predictor of tree foliage biomass. Stand density was found 

to have an effect on the b1 parameter. DBH and crown 

width were found to be the best predictors for tree branch 

biomass; stand density appeared not to have an effect on 

the parameters. DBH and crown width together were also 

observed to be good predictors of foliage biomass. The tree 

level biomass equation forms are shown in Table 2.

In the equation forms in Table 2, w is the tree level biomass 

in kilograms, D the DBH in centimeters, CW the crown 

width in meters, and X1 a dummy variable—1 if the tree is 

from an unthinned stand and 0 otherwise. The parameters b0

, 

b1, and b2 are fi tted by weighted nonlinear regression using 

SAS PROC NLIN (SAS Institute). 

The model: 

w = ξdobβCh

τ

[2(1-e-γl)-γl(γl+2)e-γl], 

developed by Zhang et al. (2004) for predicting tree foliage 

biomass, was found to provide the best fi t to the foliage 

biomass data, with a Fit Index of 0.940. The model was 

slightly modifi ed by replacing dob (diameter at crown base) 

with D (DBH):

w = ξD(β+δX1)Ch

τ

[2(1-e-γl)-γl(γl+2)e-γl] 

The model was fi tted to the pine data by weighted nonlinear 

regression using SAS PROC NLIN (SAS Institute). In the 

modifi ed form, w, D, and X1 are as in Table 2 above; Ch is 

the height of the crown while l is the length of the crown, 

both of them in meters; ξ, β,δ,τ, and γ are parameters; e 

is the base of the natural logarithm. These models will be 

used to predict individual tree biomass components on the 

thinning study plots to obtain per-unit area biomass values. 

ACKNOWLEDGMENT

The invaluable assistance of R. Heinemann, R. Holeman, 

D. Wilson, G. Campbell and K. Anderson of OSU Kiamichi 

Forest Research Station in the data collection for this project 

is acknowledged.
193

Table 1.—Equations for predicting branch and branch foliage biomass in shortleaf pine.

 Branch Foliage

Stand Type Equation form Fit Index Equation form Fit Index

Thinned to 50 percent stocking w = b0db1 0.8876 w = b01db11Rb21 0.6354

Thinned to 70 percent stocking w = b0db1Sb3 0.9687 w = b02db12Rb22 0.6220

Unthinned w = b0db1 0.9670 w = b03db13Sb3 0.3746

Table 2.—Equations for predicting tree level branch and 

foliage biomass in shortleaf pine.

Tree part Equation Fit Index

Branch w = eb01Db11CWb21 0.956

Foliage w = eb02Db12CWb22 0.894

Foliage w = eb03D(b13+b22X1) 0.919

LITERATURE CITED

Ek, A.R. 1979. A model for estimating branch weight and 

branch leaf weight in biomass studies. Forest Science. 

25(2): 303-306.

Zhang, Y.; Borders, B.; Will, R.E.; De Los Santos Posadas, 

H. 2004. A model for foliage and branch biomass 

prediction for intensively managed fast growing 

loblolly pine. Forest Science. 50(1): 65-80.
194

AN INDIVIDUAL-TREE DBH-TOTAL HEIGHT MODEL 

WITH RANDOM PLOT EFFECTS FOR SHORTLEAF PINE

Chakra B. Budhathoki, Thomas B. Lynch, and James M. Guldin1

1

Formerly Graduate Research Assistant, Dept. NREM Oklahoma 

State University (CBB), now Division of Cardiology/School of 

Medicine, University of Colorado at Denver and Health Sciences 

Center, 4200 East 9th Ave, B-139, Denver, CO 80262, Professor 

(TBL), Department of Natural Resources Ecology and Management, 

Oklahoma State University, Ag Hall Room 008C, Stillwater, OK 

74078, Supervisory Ecologist and Project Leader (JMG), Southern 

Research Station, USDA Forest Service, P.O. Box 1270, Hot 

Springs, AR 71902. TBL is corresponding author: to contact call 

(405) 744-5447 or email at tom.lynch@okstate.edu

EXTENDED ABSTRACT

Individual tree measurements were available from over 200 

permanent plots established during 1985-1987 and later 

remeasured in naturally regenerated stands of shortleaf pine 

(Pinus echinata Mill.) in western Arkansas and eastern 

Oklahoma. The objective of this study was to model 

shortleaf pine growth in natural stands for the region. As 

a major component of the shortleaf modeling effort, an 

individual-tree diameter at breast height (DBH)-total height 

model was developed in which random parameters were 

estimated for plots. The model predicts total tree height 

based on DBH and dominant stand height (which could 

be obtained from a site index model). The mixed-effects 

model approach was found to predict the total height better 

than similar models developed previously for this species. 

Moreover, such a model has the appeal of generalization of 

the results over a region from which the plots were sampled; 

and also of calibration of parameters for stands with 

minimal measurements.

The following DBH-total height model was developed by 

Lynch and Murphy (1995) and provides a starting point for 

development of a random effects model:

 (Hi

 – 4.5) = b0(HD – 4.5)b1 exp(–b2Di

–b3) (1)

where Hi is the total height of tree i in feet; HD is the 

dominant height of the stand in feet; Di is the DBH of tree i

in inches; and b0, b1, and b3 are parameter estimates which 

Lynch and Murphy (1995) obtained using generalized least 

squares. For predictive applications, HD can be obtained 

using site index relationships for shortleaf pine developed 

by Graney and Burkhart (1973). This equation is used to 

obtain individual tree total heights in the Shortleaf Pine 

Stand Simulator, an individual-tree growth simulator for 

even-aged shortleaf pine stands (Lynch et al. 1999).

The parameters in equation 1 were estimated using the fi rst 

two measurements on shortleaf pine trees in the shortleaf 

pine growth study discussed above. The availability of a 

third measurement of the permanently established plots 

in this study provided the opportunity to apply mixedmodel or random parameter methods of estimation to 

develop an improved DBH-total height model. A random 

parameter model is able to represent the situation in which 

the parameters in Equation 1 may change in different 

forest stands. When a stand is selected at random from 

the total population of stands, the parameters representing 

this change can be termed random parameters. Lappi 

(1997) provided an early application of mixed-model 

estimation with random parameters for tree height models. 

Budhathoki’s (2006) analysis of these shortleaf pine data 

indicated that there was a signifi cant random component 

associated with the b2

 parameter estimate in equation 1. This 

fi nding leads to the following equation: 

 (Hi – 4.5) = b0(HD – 4.5)b1 exp(–(a2j + b2)Di

–b3) (2)

where a2j is a plot-level random effect associated with plot 

j and fi xed-effects parameter estimates are b0, b1, and b2. 

Conceptually, fi xed-effects parameters remain the same for 

all forest stands while random-effects parameters vary by 

stand; in our data, stands are represented by plots. Mixedeffects estimation techniques can be used to estimate fi xed 

and random effects simultaneously. SAS PROC NLMIXED 

(SAS 2000-2006) was used to estimate parameters in 

equation 2 for our data. Statistics of fi t including the Akaike 

Information Criterion (AIC), the Bayesian Information 

Criterion (BIC), and the log-likelihood indicated that 

inclusion of a random parameter associated with b2

improves the fi t of the model to our DBH-total height data 

for shortleaf pine natural stands. Additionally, a variety 

of residual plots from the model indicated that the model 

performs well for these data since no pronounced biases or 

trends were evident.

Mixed-effects modeling improved the performance of a 

DBH-total height model for naturally-occurring shortleaf 

pine forests by including a random parameter that 

refl ects changes in the equation for different forest stands 

(represented by plots). This approach also provides the 

opportunity to calibrate the model for a particular stand 

by collecting a small amount of data used to estimate the 

random parameter associated with that forest stand. Lappi 

(1991) indicated how random parameter models can be used 

to calibrate height and volume equations. Recently Lynch et 

al. (2005) fi tted a random parameter DBH-height model for 

cherrybark oak (Quercus pagoda Raf.) and demonstrated the 

procedure used to calibrate the model for particular forest 

stands of interest.
195

ACKNOWLEDGMENTS

The cooperation of personnel on the U.S. Forest Service’s 

Ozark and Ouachita National Forests greatly facilitated 

collection of data used for this project. The support and 

assistance of the USDA Forest Service Southern Research 

Station are also appreciated.

LITERATURE CITED

Budhathoki, C.B. 2006. Mixed-effects modeling of shortleaf 

pine (Pinus echinata Mill.) growth data. Stillwater, OK: 

Oklahoma State University. 168 p. Ph.D. dissertation.

Graney, D.L.; H.E. Burkhart. 1973. Polymorphic site index 

curves for shortleaf pine in the Ouachita mountains. 

Res. Pap. SO-85. New Orleans, LA: U.S. Department 

of Agriculture, Forest Service, Southern Research 

Station. 12 p.

Lappi, J. 1991. Calibration of height and volume equations 

with random parameters. Forest Science 37: 781-801.

Lappi, J. 1997. A longitudinal analysis of height-diameter 

curves. Forest Science. 43: 555-570.

Lynch, T.B.; Murphy, P.A. 1995. A compatible height 

prediction and projection system for individual trees in 

natural even-aged shortleaf pine stands. Forest Science. 

41:194-209.

Lynch, T.B.; Hitch, K.L.; Huebschmann, M.M.; Murphy, 

P.A. 1999. An individual tree growth and yield 

prediction system for even-aged natural shortleaf pine 

forests. Southern Journal of Applied Forestry. 23: 

203-211.

Lynch, T.B.; Holley, A.G.; Stevenson, D.J. 2005. A randomparameter height-dbh model for cherrybark oak. 

Southern Journal of Applied Forestry. 29: 22-26.

SAS Institute Inc. 2000-2006. SAS 9.1.3 Help and 

Documentation, Cary, NC: SAS Institute Inc.
196

INTRODUCTION

This article explores the forest management activities taking 

place on Peck Ranch Conservation Area (CA). Through 

careful planning, Natural Community management is 

starting to enhance the forest community that was once 

dominant on the area. The shortleaf pine-oak/vaccinium 

dry ultic woodland natural community encompasses 

approximately 4,000 acres on the southern portion of 

Peck Ranch. The main objective for the area managers is 

to create the desired natural community and to determine 

the most effi cient way of carrying out the management by 

taking into account time, money, and all the resources on 

site. The desired future condition 40 years from present is a 

sparsely stocked stand of mostly shortleaf pine (60 percent 

or greater), with scattered white and post oak trees and a 

diverse component of herbaceous/forbs in the understory. 

This project is being monitored for overstory, ground 

vegetation, and wildlife responses. 

The current Peck Ranch CA forest is a result of actions that 

began around 1900, when most of the virgin pine forest was 

cut to provide lumber for a growing nation. This activity 

left few shortleaf pine trees on the southern portion of the 

Ranch, where the land is mostly fl at with rolling hills. 

SHORTLEAF PINE NATURAL COMMUNITY RESTORATION ON PECK RANCH 

CONSERVATION AREA IN THE MISSOURI OZARKS

John G. Tuttle and Kim J. Houf1

ABSTRACT.—Oak decline has become a signifi cantly increasing problem on Peck Ranch 

Conservation Area over the last several years. Most of the oak decline problems exist on past 

shortleaf pine sites. To address this issue, the area managers wrote a natural community 

restoration plan for 2,233 acres located on the Current-Eleven Point Oak-Pine Woodland 

Dissected Plain land type association. The goal of this plan is to restore the shortleaf pineoak/vaccinium natural community on appropriate sites. Timber harvesting activities occurred 

between 1999 and 2003 on most of the restoration area. The silvicutural prescriptions used 

were a combination of pine seed tree and irregular shelterwood seed cuts. Three different 

treatments are being used to achieve the desired results. These treatments will be replicated 

on three different areas. A combination of artifi cial and natural tree regeneration along with 

mechanical thinning, herbicide release, and prescribed fi re is being used to achieve the 

desired natural community. One additional area is a control that received the same type of 

harvests but will not be planted or receive any post harvest pine seedling releases. Most of 

the artifi cial tree regeneration occurred on the pine sites between 2004 and 2006. The entire 

project area is being monitored by the Resource Science Division to see which technique 

works best for restoring the appropriate natural community. 

1

Forestry Field Program Supervisor (JGT), Missouri Department of 

Conservation, P.O. Box 180, Jefferson City, MO 65102; and Wildlife 

Biologist (KJH), Missouri Department of Conservation, RR1, P.O. 

Box 1395, Winona, MO 65588. JGT is corresponding author: to 

contact call (573) 522-4115 Ext. 3304 or email at john.tuttle@

mdc.mo.gov 

Around 1917, the Mid-Continent Iron Company began 

operation near Fremont, MO. The small town that sprang up 

was called Midco. To fuel the smelting furnaces each day, 

180 cords of wood were required to produce 100 tons of pig 

iron. Most of the southern half of Peck Ranch was clearcut 

to provide wood for the iron company.

The Griffi th Stave Company bought the remaining timber 

rights sometime after the end of Prohibition from George 

Peck, the previous owner. Most of the white oak trees that 

were big enough to make whiskey barrels were cut at this 

time.

In this era wildfi res were frequent; many were to enhance 

grass for livestock grazing on open range. This burning 

often occurred during the driest time of the year, when 

trees were most susceptible to damage from fi re. This 

burning caused oaks to re-sprout many times and the small 

pine seedlings simply did not have the resources to keep 

sprouting. These types of activities led to the present scarlet 

oak, black oak, and hickory forest located on past shortleaf 

pine growing sites.

The current condition of the forest is such that many acres 

of scarlet and black oak trees are declining in health, 

exhibiting symptoms caused mostly by age. Most of the 

problems occur in the southern portion of Peck Ranch 

primarily because of soil conditions. Where the former 

shortleaf pine forest existed, fragipan soils are typically 

found, leading to very dry conditions during droughts and 
197

very wet conditions during periods of heavy rain. The recent 

drought years and soil conditions have proved to be very 

hard on the aging scarlet and black oak trees. 

In 1999, the Peck Ranch Planning Team wrote an area 

plan that included Natural Community management. The 

Ecological Classifi cation System was used to identify land 

type associations (LTA), ecological land types (ELTs), and 

each natural community represented on the area. In the 

plan, the team described natural community management 

groups, objectives, and strategies to achieve the structure 

and composition of the natural communities located on 

the area. In addition to the area plan, managers also wrote 

a restoration plan for 2,223 acres focused on restoring 

the shortleaf pine-oak/vaccinium natural community on 

appropriate sites.

The restoration plan focused on three management 

approaches. The fi rst management emphasis identifi ed was 

artifi cial/natural shortleaf pine regeneration accompanied 

by mechanical release on three management units. Mexel 

(1991) stated that mechanical control is not feasible from 

an economic standpoint. However, mechanical release is to 

be monitored to determine whether shortleaf pine seedlings 

can be released without damaging the herbaceous/forb 

component of the area. 

The second management emphasis identifi ed was artifi cial/

natural shortleaf pine regeneration accompanied by 

prescribed fi re on three management units. This combination 

of treatments will demonstrate whether prescribed fi re can 

be used in conjunction with regenerating shortleaf pine trees 

while enhancing herbaceous diversity. In this treatment, 

two of the units will have fi re withheld until the pine trees 

reach approximately 6 feet tall. Waiting for the trees to reach 

this height will prevent the terminal bud from being killed, 

which typically causes the trees to die. Shortleaf pine is 

unique in its ability to sprout prolifi cally when the crown is 

killed or badly damaged (Lawson 1990). The one remaining 

unit will be burned as needed to retard the oak sprouts and 

to enhance the herbaceous/forb component of the area.

Artifi cial/natural shortleaf pine regeneration accompanied 

with herbicide release was the third management emphasis 

involving three management units. The objective is to 

see whether herbicide can be used without damaging the 

herbaceous/forb component and the residual oak trees that 

were left scattered throughout the stands. Miller et al. (1999) 

found that after herbicide was used in site preparation 

in Georgia, the herbicide had little infl uence on total 

(herbaceous) species numbers or diversity 11 years after 

treatments. We hope to have the same results in species 

diversity and richness on our study site. 

STUDY AREA

Peck Ranch Conservation Area is located in the northwest 

corner of Carter County, Missouri. The largest portion of 

Peck Ranch CA was purchased in 1945 by the Missouri 

Department of Conservation from George Peck. The area 

encompasses 23,048 acres and is about 95 percent forested. 

This Conservation Area has four LTAs. The Current 

River Oak-Pine Woodland/Forest Hills is the largest LTA, 

comprising 47 percent of the area. The second largest is the 

Eminence Igneous Glade/Oak Forest Knobs (20 percent). 

Another 17 percent of the area is in the Current-Eleven 

Point Oak-Pine Woodland Dissected Plains, where the pineoak/vaccinium community restoration work is taking place. 

The smallest LTA is the Current River Oak Forest Breaks, 

which makes up 14 percent of the area. 

The study area is located on the southern portion of the 

Ranch. In 2004, area managers wrote a restoration plan 

for a portion of this area. This plan addressed different 

management ideas and concerns such as the lack of shortleaf 

pine on historical pine sites, the lack of good quality 

wildlife habitat, and the need to restore degraded natural 

communities. The Midco Pine Flats Restoration Area 

encompasses 2,223 acres of mostly high quality pine-oak/

vaccinium restoration sites.

METHODS

The project is being conducted on Peck Ranch Management 

Compartments 10, 13, and 17. These three compartments 

have been further divided into 10 management units for 

planning and implementing monitoring activities. All 10 

management units have had a salvage timber harvest carried 

out on them, leaving shortleaf pine for seed trees and about 

20 feet2 of basal area per acre of white and post oak trees, 

when possible. The logging occurred between 1999 and 

2003. Following logging, all stands were slashed to kill 

remaining suppressed oak and hickory trees. Since 2005, 

568 acres (171,537 seedlings) have been planted to shortleaf 

pine on the study area. The next step is to control hardwood 

and herbaceous competition on the seedlings. Hardwood 

competition that is effectively managed can result in 40 

percent volume increases on pine crop trees (Lowery 

1986). Cain (1991) stated that even when an area has 

adequate numbers of pine seedlings, a rank ground cover 

of herbaceous species can reduce pine growth and may 

dictate the application of release treatments. The other nine 

management units were logged and artifi cial regeneration 

was used to supplement natural shortleaf pine regeneration. 

These latter nine units were subdivided into groups of three; 

one group received an additional treatment with prescribed 

fi re, one group received herbicide release, and one group 

received mechanical release. One management unit was 

logged and follow-up slashing was conducted; the only 

shortleaf pine regeneration in this unit is that which occurs 
198

naturally. Missouri Ozark Forest Ecosystem Project site 

number 8 is adjacent to the study area and is being used 

as a control; this area had previously been set aside as an 

unmanaged site.

In the herbicide release area a spot treatment method using 

Arsenal® AC and Escort® XP was used on 181 acres to 

release the shortleaf pine and preserve the herbaceous 

component. The application rate was 4 oz/100 gallons water 

for Escort® XP, and 1 oz /100 gallons of water for Arsenal® 

AC. All vegetation within a 6 foot radius of a shortleaf 

pine equal to or less than 4 inches diameter at breast height 

(DBH), was chemically treated. No chemical application 

was directly applied to any shortleaf pine trees or within 

the drip line of any residual tree equal to or greater than 10 

inches DBH.

MONITORING AND EVALUATION

Vegetation

All 10 management units will be monitored to learn which 

technique works best and is the most cost effective. Our 

goal is to produce a pine stand with a diverse understory that 

will enhance wildlife habitats.

During the year following shortleaf pine seedling planting, 

a seedling survival inventory was implemented to determine 

how many planted seedlings survived after the initial 

planting. This inventory was conducted by establishing 

fi xed 100th-acre plots throughout the area and counting the 

number of seedlings that survived within each plot. 

To evaluate vegetative response, a fi xed plot design is used 

for long-term data collection. In each of the 10 management 

units, three random points were placed within areas that 

were designated for restoration work. These points were 

used to establish 0.2-acre circular plots. Within each plot, 

all overstory trees are tagged and species and DBH are 

recorded.

Tenth-acre subplots consisting of the northeast and 

southwest plot quadrants are used for sampling pine 

seedlings and all saplings. For all non-pine species, we 

record species, height, and DBH. All pine saplings are 

tagged and the height and DBH are measured. For pine 

seedlings (< 4.5 ft height) we record height and basal 

diameter. Up to 60 seedlings are also tagged to track 

survival. Of the tagged seedlings, a sub-sample is selected to 

collect data on competition. 

To track competition, a circular subplot of 3.5-foot radius is 

centered on a pine seedling. We then identify each woody 

plant to species and record the height. For dense shrub or 

vine species (Rubus, Vaccinium, Vitis, etc.) a stem count is 

recorded.

Twelve 1-m2

 quadrats are placed within the plot (three in 

each cardinal direction) to sample ground fl ora and ground 

cover. For ground cover, percent classes are used to measure 

the percent cover of bare ground, dead wood, litter, lichen, 

rock, and vegetation. Ground fl ora are identifi ed to species 

and recorded in percent classes. For seedlings of any woody 

species, a stem count is also recorded.

Pretreatment data collection is under way and post-treatment 

data collection is scheduled to occur at 3-year intervals. In 

addition, we will continue to collect the same overstory, 

sapling, and ground fl ora data on 20 plots previously placed 

randomly according to the initial harvest areas.

Wildlife

The Peck Ranch Pine Management Zone Breeding Bird 

Survey (BBS) was patterned after the national BBS, but 

was modifi ed to meet management objectives. The roadside 

survey has been conducted annually since 2000. The 

Pine Management BBS is conducted two to three times a 

year during the peak of nesting season, primarily in May 

and June. The route is 12 miles and encompasses all 10 

management units. Twenty-fi ve stops are located at 0.35- 

to 0.5-mile intervals along the route. Starting half an hour 

before sunrise, a fi ve minute point count is conducted at 

each stop, during which the observer records all birds heard 

or seen. The objective of the Pine Management BBS is 

to monitor the composition and relative abundance of the 

songbird community within the management zone.

A northern bobwhite quail (Colinus virginianus) survey 

is also conducted within the management units. The 

roadside quail survey has been conducted since 2005 and is 

performed two to three times a year from June 15 to 

July 15. The quail survey consists of three routes, each of 

which is 7 miles long. Route 1 is located along the North 

Boundary Road and has 15 stopping points. Route 2 is 

located along Road 1 and has 14 stopping points. Route 3 is 

located along the South Boundary Road and has 13 stopping 

points. All stopping points are located at 0.35- to 0.5-mile 

intervals along each route. Starting half an hour before 

sunrise, a 

5-minute point count is conducted at each stop, during 

which the observer records all quail heard or seen. The 

objective of the quail survey is to assess the relative 

abundance and spatial distribution of bobwhite quail. 

RESULTS

Vegetation

During the summer of 2005, a pine survival survey was 

done on all areas that were planted on units 7-9. The pine 

seedlings that were planted on 12 x 12 foot spacing at a rate 

of 302 trees per acre averaged 40 percent survival overall 

(mean = 40, standard error ± 4.9). The lowest survival was 

on stand 27 on unit 8, which was only 23 percent. The 

highest survival was on stand 14 on unit 7, which was 60 
199

percent survival. The expected survival rate before planting 

was 50 percent. 

We are just now fi nishing data collection and data entry for 

the fi rst season pre-treatment data on the treatment areas. So 

far it is too early to make any comparisons to show which 

treatment is working best.

Wildlife

The efforts to restore a unique natural community type 

have affected a suite of bird species. Over the past 6 years, 

the mean number of species detected on the route has 

increased from 30 birds to more than 40 birds, perhaps 

due to the infl ux of early-successional habitat species. 

Several early successional habitat species, such as the 

indigo bunting (Passerina cyanea), yellow-breasted chat 

(Icteria virens) and prairie warbler (Dendroica discolor), 

have shown evident increases (Fig. 1). The mean number 

of individuals per stop for the indigo bunting has increased 

from 1.24 in 2000 to 1.44 in 2006, while the yellowbreasted chat increased from 0.22 to 1.24 and the prairie 

warbler increased from 0.16 to 0.22. Mature-forest species, 

such as the eastern wood pewee (Contopus virens), which 

lives on ridge tops and has a moderate density, seem to 

have shown little population change, whereas the red-eyed 

vireo (Vireo olivaceus) has decreased in the mean number 

of individuals per stop from 1.38 to 0.92, perhaps due to the 

reduction in deciduous forest canopy. Target pine savanna 

species, such as the pine warbler (Dendroica pinus) and 

chipping sparrow (Spizella passerine), have also responded 

well to the management practices. The increase in the mean 

number of individuals per stop for each species from 2000 

to 2006 is: pine warbler 0.78 to 1.08 and chipping sparrow 

0.0 to 0.06. Other target species such as the yellow-throated 

warbler (Dendroica dominica) have kept a steady level with 

no signifi cant increase or decrease.

We have only 2 years of data collection from the quail 

census. Although no quail have been recorded, it is too early 

to make any conclusions on abundance, spatial distribution, 

or to compare treatments.

DISCUSSION

The purpose of the study is to evaluate methods for restoring 

the shortleaf pine/oak/vaccinium natural community. In 

addition managers want to restore the forest communities 

that once existed on the site in order to enhance wildlife 

benefi ts and forest health. If oak is allowed to grow on 

historical pine sites, a manager can expect to have oak 

decline problems as the trees become older, particularly 

following droughts, and attacks by insects and pathogens.

Herbicide in combination with planting and natural tree 

regeneration is probably the best and most effi cient way of 

regenerating trees. Success depends on the size of the area 

treated and type of application. 

Prescribed fi re accompanied with planting and natural tree 

regeneration is a technique that appears to work well for 

shortleaf pine as long as the trees reach a suffi cient height 

before burning. Burning, however, may encourage a singlespecies stand of trees, which could create problems with 

insect infestation or disease outbreaks. Fire can enhance 

forbs and herbaceous vegetation, which in turn can lead to 

severe competition to the shortleaf pine seedlings.

Mechanical control in combination with planting and 

natural tree regeneration appears to be labor intensive. We 

located each tree and released a circle around it by cutting 

all the oak sprouts. Without herbicide, the oaks immediately 

sprouted back and within one growing season were again 

competing with the pine seedling. Managers have observed 

that in stands with many suppressed oak trees, delaying the 

slashing or cutting of these trees allows the pine seedlings 

time to get established. When pine seedlings were already 

established in the understory and the suppressed hardwood 

trees were cut, pine trees competed much better. In stands 

where very few pine seedlings were present and where the 

suppressed oak trees were immediately cut after logging, 

pine trees appeared to respond more slowly.

In the 10th unit the main factor affecting pine establishment 

is how much advance pine regeneration was present on the 

forest fl oor before logging took place. We have observed 

that where advance regeneration was located, pine trees 

are doing well. We have also observed that the herbaceous 

component is starting to diminish as the canopies start to 

close.

Many stands received a salvage harvest in which all 

shortleaf pine and 20 basal area of white and post oak trees 

were retained. We have observed an increase in many early 

successional species as a result of the sunlight reaching the 

forest fl oor. Quail, turkey, and many migratory birds use 

early successional grasses as nesting habitat, while forbs 

and legumes offer abundant food throughout the year. The 

variety of mature oaks provides mast crops to serve as 

high energy food for wild turkey, white-tailed deer, and 

squirrels. As some of these stands begin to have a more 

closed overstory, we are beginning to see a different suite 

of species favored, such as sedges, grasses, low shrubs, and 

wildfl owers. 

It is too early in the process to know which combinations 

of management techniques are going to work the best. 

Resource Science Division has only completed the 

initial layout of the plots and collected the baseline data. 

A literature review of published research suggests that, 

depending on the goal, each technique has its benefi ts and 

disadvantages. The role of the research is to determine 

the best technique to achieve our goal of restoring and 

managing the shortleaf pine-oak/vaccinium dry ultic 

woodland natural community.
200

Figure 1.—Mean number of birds per stop from annual breeding bird surveys conducted in the restoration area.

2000 2001 2002 2003 2004 2005

2000 2001 2002 2003 2004 2005

2000 2001 2002 2003 2004 2005

2000 2001 2002 2003 2004 2005

2000 2001 2002 2003 2004 2005

2000 2001 2002 2003 2004 2005

2000 2001 2002 2003 2004 2005

Year

Mean No. Per Stop

Year

Mean No. Per Stop

Year

Mean No. Per Stop

Year

Mean No. Per Stop

Year

Mean No. Per Stop

Year

Mean No. Per Stop

Year

Mean No. Per Stop

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

0.6

0.5

0.4

0.3

0.2

0.1

0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

Indigo Bunting Yellow-breasted Chat

Eastern Wood Pewee

Pine Warbler

Yellow-throated Warbler

Prairie Warbler

Red-eyed Vireo
201

ACKNOWLEDGMENTS

We thank Carrie Steen from Missouri Department of 

Conservation’s Resource Science Division for writing the 

paragraphs describing data collection methods and design. 

We thank Rick Clawson from Missouri Department of 

Conservation’s Resource Science Division for sharing his 

information on the Breeding Bird Survey. 

LITERATURE CITED

Cain, M.D. 1991. Hardwoods on pine sites: competition 

or antagonistic symbiosis. Forest Ecology and 

Management. 44: 147-160.

Lawson, E.R. 1990. Shortleaf pine (Pinus echinata Mill.). 

In: Burns, R.M.; B.H. Honkala, B.H., tech. coord. 

Silvics of North America. Vol 1. Conifers. Agric. 

Handb. 654. Washington, DC: U.S. Department of 

Agriculture, Forest Service: 316-326.

Lowery, R.F. 1986. Woody competition control. In: Murphy, 

P.A. (ed.) Symposium on the Shortleaf Pine Ecosystem. 

[Publisher unknown]: 147-158.

Mexal, John G. 1991. Artifi cial regeneration of shortleaf 

pine: put it all together for success. In: Shortleaf pine 

regeneration workshop; 1991 October 29-31. New 

Mexico Agric. Exp. Sta. Scientifi c Paper No. 409: 

172-186.

Miller, James H.; Boyd, R.S.; Edwards, M.B. 1999. Floristic 

diversity, stand structure, and composition 11 years 

after herbicide site preparation. Canadian Journal of 

Forest Research. 29: 1073-1083.
202

GLADE/WOODLAND RESTORATION IN THE ST. FRANCIS MOUNTAIN 

BIRD CONSERVATION AREA

David A. Hasenbeck1

1

Private Land Conservationist (DAH), Missouri Department of 

Conservation, RT 4 Box 1002, Piedmont, MO 63957. To contact call 

(573) 223-4525 or email at David.Hasenbeck@mdc.mo.gov

EXTENDED ABSTRACT

The Missouri Department of Conservation (MDC), the 

Missouri Department of Natural Resources, the U.S. 

Forest Service, and American Bird Conservancy, share 

goals to restore and manage high quality glade, savanna, 

and woodland habitats within the Saint Francis Bird 

Conservation Area. The partnership endeavors to maintain 

and enhance an ecosystem with native glade and pine 

woodland components across a large landscape in which 

private and public land management work together to 

contribute to the overall habitat goals. 

The primary purpose of this project is to increase habitat 

available to grass-shrub bird species. Species targeted 

have declined signifi cantly since the inception (1966) 

of the annual North American Breeding Bird Survey. A 

secondary goal of the project is to develop contractors 

capable of delivering prescribed fi re management in the 

Ozark Mountains of southeastern Missouri by utilizing grant 

dollars. The project also will increase landowner awareness 

and foster cooperation through outreach and technical 

assistance with the public and through interagency partner 

planning and coordination.

The St. Francis Mountains Bird Conservation Area 

(SFBCA), established in 2003, lies in the eastern Ozarks 

of southeastern Missouri and located within an ecological 

subsection known as the St. Francois Knobs and Basins 

(Fig. 1). It comprises portions of St. Francois, Madison, and 

Iron Counties and minor portions of Washington, Reynolds, 

Wayne, Bollinger. and Ste. Genevieve counties. The SFBCA 

supports a diverse array of habitat types, including igneous 

glades, oak savannas, and oak and oak-pine woodlands. 

This project seeks to secure and expand declining bird 

species within the St. Francois mountain region through 

the restoration of glade, woodland, and grass habitats on 

public and private lands. Partner agency staff and resources, 

coupled with grant dollars, were used to implement the 

management plan. 

Key private land parcels were identifi ed and prioritized. 

Highest priority was placed on cooperative public-private 

land restoration. The second priority was private land 

restoration adjacent to or nearby publicly-owned glade 

complexes. Private lands were selected by MDC cooperators 

or by partner agency referrals and by landowner interest. 

Three contracts of 800 to 1200 acres with an average of 10 

units per package were developed and implemented with 

grant dollars with mixed success.

In an attempt to ensure long-term success of the restoration 

units, federal costshare will be utilized to implement followup burns. 

Facilitation of public burn units was accomplished through 

contracted snag felling and line construction to best 

complement limited labor.

Partners met formally on an annual basis to better 

coordinate restoration work. Several cooperative projects 

have been identifi ed.

During the granting period, more than 5000 acres of habitat 

were treated using prescribed fi re within the SFBCA (>2200 

acres on private land). Approximately 350 acres (>110 

acres on private land) of eastern red cedar were removed 

from habitats within the SFBCA. Twelve miles of fi reline 

was contracted. Eight workshops were conducted by MDC 

and other project partners within the SFBCA. Increased 

opportunity for cooperation was created via interagency 

planning.

Figure 1.—Project Area
203

We have achieved success in habitat improvements, but 

maybe equally important is the continued development of 

fi re contractors and administrative mechanisms to have 

contractors conduct prescribed burns on large private 

parcels. It will be necessary to coordinate several burn units 

each spring (1000 acres or more) to ensure adequate acreage 

to continue to attract contractors capable of conducting 

large woodland burns. Coordination of multiple-ownership 

restoration involves communication between private 

landowners, natural resource agencies, and contactors. 

This is especially evident in situations where large tracts 

of public land encompass small private parcels. At times, 

private inheld parcels preclude conducting landscape-level 

burn units. It is necessary to target these key inholdings 

and actively assist with facilitation of the burn between 

landowner, agency, and contractor to ensure successful 

restoration efforts. We found that contracting woodland fi re 

units cost at least $1000 to $1200 per day. For this reason, 

we selected units over 30 acres in size. More contractors are 

needed. Timber stand improvement allows fi re contractors 

crews to stay busy while in the area and minimize down 

time when weather is not conducive to burning or line 

construction. Private land-burn costs averaged $45/acre 

for a burn plan, line installed, and a burn conducted. Costs 

averaged $30/acre for woodland burns when the lines were 

installed and a plan provided to the contractor. Follow-up 

burns are ongoing and typically occur 2 to 3 years after the 

initial prescribed fi re and periodically thereafter.

ACKNOWLEGMENTS

I would like to thank the National Fish and Wildlife 

Foundation, Missouri Bird Conservation Initiative, and 

Missouri Conservation Heritage Fund for funding much of 

this management. 
204

EXTENDED ABSTRACT

Pine dominated more than 4 million acres of the Missouri 

Ozarks prior to European settlement. These pineries 

supported a diverse array of plants and animals, including 

several taxa no longer present in the state (e.g., Desmodium 

ochroleucum, Picoides borealis, Sitta pusilla). Intensive 

logging activity and subsequent land management practices 

at the close of the 19th century resulted in a complete loss of 

functional pinery systems, although shortleaf pines continue 

to be a common component of mixed woodlands in the 

region.

Prior to European settlement, these pineries consisted of 

relatively uniform pine or pine-oak dominated canopies 

over large expanses of well-drained rolling to dissected 

uplands, with minimal subcanopy and shrub development. 

As is the case with structurally similar hardwood systems 

in the Ozarks, and many pine woodlands elsewhere in the 

New World, we postulate that most of the vegetational 

diversity in these systems existed in the ground layer. 

This ground layer consisted of a diverse assemblage 

characterized by perennial herbaceous forbs and a smaller 

number of graminoid species that were disproportionately 

prevalent and shaped the fuel characteristics of the system. 

These pineries require frequent, low-intensity, prevailingly 

dormant-season fi re events to maintain the open structure 

and facilitate canopy replacement dynamics. 

In 1998, the U.S. Forest Service and The Nature 

Conservancy initiated a partnership to restore a functional 

pinery system within a landscape producing both ecological 

and economic outputs, and capable of eventually sustaining 

viable populations of the full array of indigenous pineland 

biodiversity. Initial phases of the work have consisted of: 

(1) identifi cation of historically appropriate sites of suitable 

scale and continuity; (2) rapid ecological assessment 

of candidate sites and the resulting area delineation of 

the Pineknot Pine Restoration Project; (3) presettlement 

vegetation analysis and detailed baseline assessment 

of current vegetation; (4) derivation of an ecological 

model for Ozark pinery vegetation; (5) development and 

implementation of silvicultural and fi re management 

treatments; and (6) initial post-treatment vegetation 

assessment and data analysis.

THE PINEKNOT PROJECT: RESTORATION OF A MISSOURI OZARK PINERY

Douglas Ladd, Blane Heumann, and Paul Nelson1

1

Director of Conservation Science (DL), The Nature Conservancy, 

St. Louis, MO, 63144; Director of Stewardship (BH), The Nature 

Conservancy, Van Buren, MO, 63965; and Ecologist (PN) Mark 

Twain National Forest, U.S. Forest Service, Rolla, MO 65401. 

DL is corresponding author: to contact call (314) 968-1105 or email 

dladd@tnc.org

The Pineknot site consists of 12,419 acres in southwestern 

Carter County, on a rolling upland plain with moderate 

topographic relief. Soils are derived from clay and chert 

residuum, and are xeric, acidic, and nutrient limited. 

Vegetation monitoring was established using 100 permanent 

points randomized within area-proportional representation 

for each of the four landform classes at the site. These 

selections were stratifi ed to ensure area-proportional 

representation of even-aged stands <15 years old, and 

buffered to exclude roads, ponds, and other anthropogenic 

attributes. Canopy vegetation was sampled for the fi rst 50 

points using 0.1-acre square macroplots. Each of the 100 

points was sampled for ground cover vegetation using fi fty 

0.25-m2 square quadrats randomized within intervals along 

radial line transects. 

Presettlement vegetation analysis indicates a heavily pinedominated woodland in the region, with an open canopy 

of moderately large trees. At the Pineknot site, most of the 

landscape in 1821 had a canopy cover of 40-80 percent, 

with a mean stocking rate of 45 trees per acre and an 

average distance of 27 feet from a survey point to a witness 

tree. Shortleaf pine comprised 76 percent of the witness 

trees, with a mean DBH of 17 inches. Virtually all the other 

witness trees in the site were various upland oak species, 

with slightly smaller mean DBH.

This situation contrasts dramatically with the pretreatment 

condition of abundant, smaller, more closely spaced 

trees, increased canopy cover, and a dominant hardwood 

component. In contrast to 1821, when the site composition 

was entirely pine types, less than half the site is currently 

classifi ed as pine, with the remainder consisting of oakdominated hardwoods. Although current canopy patterns 

suggest a relationship between topographic position and 

hardwood composition and abundance, none of these stand 

trends, such as greater hardwood component on northeastfacing or bottom stands, was evident in 1821. As contrasted 

with the open woodland structure in 1821, pre-treatment site 

vegetation consisted of more abundant, closed canopy with 

more trees and a much higher proportion of hardwoods.

Floristic models indicate that Missouri Ozark pineries were 

composed of a diverse but relatively consistent assemblage 

of about 300 predominantly perennial upland herbaceous 

vascular taxa, including several conservative species with 

high local fi delities to pineland systems. Mean per-unit area 

ground cover diversity in intact Ozark pineries probably 

exceeded 10 (perhaps approaching 15) native taxa per 0.25 m2

; 

pretreatment baseline data reveal 2.2 taxa per 0.25 m2

. 
205

Most of the conservative fl oristic cohort of these pineries 

(C values ≥6) are associated with relatively high light 

intensities and are currently absent or sparse over the 

Pineknot site. Analysis of vegetation monitoring data reveals 

that initial, largely fi re-based site treatments have increased 

native ground cover diversity (2.2 to 3.1), fl oristic quality 

(6.0 to 7.4), and abundance (11,245 to 15,503). 

These increases have been attenuated by remaining high 

hardwood cover and consequent shading levels through 

most of the site. A compelling need is indicated for 

increased intensity of silvicultural treatments and 

hardwood sprout reduction to advance restoration goals 

from current condition towards a compositional and 

structural state more evocative of the vegetation model. 

Restoration of a diverse, sustainable pinery community 

will require: (1) adoption of intensive treatments to 

secure canopy cover and composition within the range of 

natural variation resembling General Land Offi ce data; (2) 

restoration of a fi re regime encompassing both the mean and 

extremes within the prevailing presettlement fi re dynamics; 

and (3) recruitment or reintroduction of an abundant, diverse 

ground layer dominated by herbaceous perennials, including 

a prominent graminoid component and a high diversity and 

presence of a suite of conservative taxa.

Pinelands once occupied a substantial portion of the 

Missouri Ozarks. From the perspective of both global and 

local conservation value and irreplaceability, it is imperative 

that we actively restore functional examples of this legacy 

of our natural heritage, while sustaining the full array of 

biota characteristic of these systems.
206

SHORTLEAF PINE-BLUESTEM RESTORATION IN THE OUACHITA NATIONAL FOREST

Larry D. Hedrick, George A. Bukenhofer, Warren G. Montague, William F. Pell, and James M. Guldin1

ABSTRACT.—The fi re-dependent shortleaf pine-bluestem ecological community, once 

common in the Ouachita Mountains, had all but disappeared by 1970. This absence was due 

to the cutting of the original forests in the early part of the 20th century followed by effective 

fi re suppression since the late 1930s. With the adoption of Forest Plan amendments in 1994, 

1996, and 2002, and a Forest Plan revision in 2005, the Ouachita National Forest committed 

to restore the shortleaf pine-bluestem ecosystem on some 250,000 acres. Restoration 

treatments include thinning pine stands to a residual basal area of about 60 ft2 per acre, felling 

most of the woody midstory stems, and prescribed burning at 3- to 4-year intervals. Achieving 

conditions similar to those depicted in historic photographs normally requires a thinning, a 

midstory reduction treatment, and three prescribed fi res over about 10 years. Since 1994 some 

52,992 acres have been thinned, 42,948 acres have received midstory reduction, and 143,233 

acres have received one or more prescribed burns. Managers estimate that 18,653 acres are 

presently in a substantially restored condition. During this time the endangered red-cockaded 

woodpecker (Picoides borealis Vieillot) population has more than doubled, and populations of 

several other previously declining species of conservation concern have increased markedly.

1

Team Leader, Integrated Resource Management (LDH), 

Ouachita National Forest, P.O. Box 1270, Hot Springs, AR 71902; 

Endangered Species Coordinator (GAB), Southern Region, USDA 

Forest Service, 1720 Peachtree Rd. NW, Atlanta, GA 30309; District 

Wildlife Biologist (WGM), Ouachita National Forest, P.O. Box 2255, 

Waldron, AR 72958; Team Leader, Planning and Recreation (WFP), 

Ouachita National Forest, P.O. Box 1270, Hot Springs, AR 71902; 

and Supervisory Ecologist and Project Leader (JMG), Southern 

Research Station, USDA Forest Service, P.O. Box 1270, Hot 

Springs, AR 71902. LDH is corresponding author: to contact call 

(501) 321-5270 or email at lhedrick@fs.fed.us

PRE-EUROPEAN SETTLEMENT AND 

CURRENT ECOLOGICAL CONDITIONS

The Ouachita Mountains of west-central Arkansas and 

southeastern Oklahoma encompass 6.6 million acres, 

and together with the Boston Mountains and Ozark 

Plateaus to the north and east, form the Interior Highlands 

physiographic region (USDA Forest Service 1999). The 

Ouachitas are an eroded mountain system that originated 

in the late Paleozoic period some 280 million years ago 

through tectonic activity that folded and faulted the ocean 

sediments of the area from south to north, resulting in an 

unusual east-west orientation with broad long aspects facing 

south and north. Elevations range from 500 to 2,700 feet. 

Travelers, settlers and scientists in this region during the 

1800s and early 1900s described open pine (Pinus echinata

Mill.) and hardwood forests with fl oristically rich understory 

vegetation of grasses and forbs (Nuttall 1999, Jansma and 

Jansma 1991, Palmer 1924, Little and Olmstead 1931, 

Cogburn 1976, McBride 1978) (Fig. 1). Elk (Cervus elaphus

L.) and bison (Bison bison L.) once found suitable habitat 

in these open woodland communities (Smith and Neal 

1991), and are enshrined in local names such as Buffalo 

Creek. Fires were common (Nuttall 1999, Featherstonhaugh 

1844, Little and Olmstead 1931) and maintained the open 

condition (Foti and Glenn 1991). In a typical Ouachita 

Mountain area in Oklahoma, fi res occurred at an average 

return interval of less than 10 years for most sites (Masters 

and others 1995). Tree densities then averaged 170 trees 

per acre and the average diameter was 11.4 inches (Kreiter 

1995).

While the Ouachita Mountain landscapes of today are still 

dominated by forests, the composition and structure of these 

forests are much different. Many hundreds of thousands 

of acres of shortleaf pine-hardwood forests have been 

Figure 1.—Historic conditions in the Ouachita National 

Forest circa 1920 (US Forest Service fi le photo).
207

converted to loblolly pine (Pinus taeda L.) plantations on 

industry lands. The remaining second-growth stands of 

shortleaf pine and hardwood today on average have more 

trees and smaller trees than pre-European settlement stands. 

Today in the Oklahoma study area, for example, the average 

number of trees per acre ranges from 200 to 250, and their 

diameters average 9 inches (Kreiter 1995). Average fi re 

return intervals now range from 40 to more than 1200 

years (Masters and others 1995). Throughout the region 

understory vegetation is now dominated by woody species, 

and once-common grasses and forbs are scarce (Fenwood 

and others 1984, Masters 1991, Sparks 1996). Bison and 

elk have been extirpated. Other species such as Bachman’s 

sparrow (Aimophila aestivalis Lichtenstein), brown-headed 

nuthatch (Sitta pusilla Latham), and northern bobwhite 

(Colinus virginiana L.) have been negatively affected by 

the loss of habitat (Jackson 1988), and the red-cockaded 

woodpecker (Picoides borealis Vieillot) has become 

endangered (Neal and Montague 1991).

Historic and present-day forests of the 1.78 million 

acre Ouachita National Forest (ONF) very much fi t the 

descriptions above. The typical shortleaf pine-hardwood 

stand today ranges from 70-90 years old and comprises 

90 to 100 ft2

 basal area of pine, and 30 ft2 basal area of 

hardwoods per acre (Fig. 2). Of the hardwood basal area, 

two-thirds is in trees 3 to 9 inches in diameter (Guldin and 

others 1994). The condition of today’s stands derives largely 

from two factors: the cutting of the original trees and more 

than 60 years of fi re suppression. Large-scale exploitation of 

the original forests began in the early 1910s and was largely 

fi nished by 1940 (Smith 1986). Under U.S. Forest Service 

stewardship, the period of regeneration that followed the 

cutting was marked by a strict policy of fi re suppression 

that continued well into the 1980s. The ecological upshot is 

that by about 1970, the shortleaf pine-bluestem woodland 

community had all but disappeared from the Ouachita 

Mountain landscapes (Foti and Glenn 1991).

PLANNING FOR RESTORATION

The ONF initiated large-scale restoration efforts for the 

shortleaf pine-bluestem ecosystem with the adoption in 

1994 of a forest plan amendment to restore old-growth 

shortleaf pine stands on some 54,000 acres (USDA Forest 

Service 1994). In 1996 a forest plan amendment was 

adopted to restore another 120,000 acres of this ecosystem 

in west-central Arkansas to aid recovery of the endangered 

red-cockaded woodpecker (USDA Forest Service 1996). In 

2002 still another forest plan amendment allocated 30,000 

acres in McCurtain County, OK, for recovery of the redcockaded woodpecker (USDA Forest Service 2002). Finally, 

a recently adopted revised forest plan (USDA Forest Service 

2005) designated an additional 50,000 acres, unrelated 

to either old-growth forests or red-cockaded woodpecker 

recovery, to receive restoration treatments. Thus the total 

acreage allocated to shortleaf pine-bluestem ecosystem 

restoration is 254,000 acres, about 25 percent of the total 

Figure 2.—Typical unrestored mature second-growth 

shortleaf pine-hardwood stand on the Ouachita NF today 

(photo by Joe Neal).

pine-dominated acreage on the ONF and about 14 percent of 

the entire forest.

RESTORATION PRESCRIPTIONS

Restoration treatments vary somewhat between stands of 

native second-growth shortleaf pine and artifi cial plantations 

of loblolly pine. In the Ouachita Mountains the latter species 

was originally naturally distributed in narrow bands along 

larger stream corridors, mostly along the southern edge of 

the mountains. Since the late 1960s, however, the trend 

on private industrial forest lands has been to replace the 

shortleaf pine forests on upland sites with loblolly pine 

plantations, thus increasing loblolly pine’s acreage far in 

excess of its original extent. Some of these formerly private 

lands have been acquired for the National Forest system 

by purchase or exchange. Each of the areas now dedicated 

to restoration of the shortleaf pine-bluestem ecosystem 

contains some loblolly pine plantation acreage. 

Native Second-Growth Shortleaf Pine

For typical second-growth shortleaf pine stands, the 

restoration prescription requires thinning to a residual basal 

area of about 60 ft2 per acre, felling most of the woody 

midstory stems in a treatment known within the agency as 

wildlife stand improvement (WSI), followed by prescribed 

burning at 3- to 4-year intervals. Overstory hardwoods, 

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

are retained as individuals or clumps within pine stands, 

and as entire stands throughout the landscape. Flowering 

trees and fruiting shrubs such as dogwood (Cornus fl orida

L.), serviceberry (Amelanchier arborea (Michx. f.) Fern.), 

and wild plum (Prunus spp.) are retained during midstory 

reduction treatments. Implementation of these treatments 

will result in substantially restored conditions in about a 

decade (Fig. 3). 
208

When stand regeneration is desired, advantage can be taken 

of shortleaf pine’s ability to resprout following fi re, a habit 

noted early on by Mattoon (1915). The repeated prescribed 

burning should serve to provide advanced regeneration of 

shortleaf pine through resprouting of existing seedlings as 

well as recruitment of new seedlings over time. Thus, when 

a decision is made to regenerate these stands, foresters 

should be able to rely on release of adequate numbers of 

seedlings from the advance-growth seedling bank, rather 

than simply upon seedfall and germination of new seedlings, 

which can be uncertain in shortleaf pine. Reproduction 

cutting methods utilizing either irregular seedtree (seedtree 

with reserves) or irregular shelterwood (shelterwood with 

reserves) methods will be employed to naturally regenerate 

these stands. Nominal rotation lengths are 160 years for 

old-growth restoration units, 120 years in areas managed 

for red-cockaded woodpecker recovery, and 70 years for the 

remainder.

Loblolly Pine Plantations

Restoration treatments for loblolly pine plantations include 

thinning to a residual basal area of about 60 ft2 of basal area 

to encourage development of the desired understory grasses 

and forbs, and prescribed burning at 3- to 4-year intervals to 

maintain the understory vegetation and discourage loblolly 

pine reproduction. The loblolly pines will be carried to ages 

and sizes that are economically effi cient. The stands will 

then be clearcut and replanted with native shortleaf pines, 

which will then be managed as described above.

The Role for Timber Sales

The ability to sell valuable wood products is at the very 

heart of restoration efforts regardless of whether the 

stand currently consists of native second-growth shortleaf 

pines or planted loblolly pines. All commercial thinning 

or regeneration cutting is accomplished through the use 

of timber sales that are advertised and sold to the highest 

Figure 3.—Restored shortleaf pine-bluestem community on 

the Ouachita NF (photo by James M. Guldin).

bidder. Further, under authority of the Knutson-Vandenberg 

Act of 1933 and the National Forest Management Act of 

1976, portions of the proceeds from these timber sales 

are retained to pay for most of the follow-up midstory 

reduction and prescribed burning needed to restore the 

stands. The upshot is this: timber purchasers are willing 

to pay a substantial price for the privilege of cutting 

and removing trees under the Forest Service restoration 

prescription, helping us achieve desired conditions across 

many landscapes. The use of sale proceeds to pay for 

midstory reduction and prescribed burning reduces the 

need to rely upon scarce federal appropriated dollars for 

these treatments, and results in the ability to restore much 

larger areas than would be possible through expenditure 

of appropriated dollars alone. In this ecological context, 

timber sales are a means to an end rather than an end unto 

themselves.

ENVIRONMENTAL EFFECTS 

OF RESTORATION

While understanding the essential need for restoration in 

order to recover the endangered red-cockaded woodpecker 

(Fig.4), and sensing the ecological correctness of restoring 

an ecosystem that was once widespread but had practically 

vanished, Forest Service planners and land managers 

acknowledged that there were unanswered questions 

about the environmental effects of restoration activities. 

Studies designed to answer many of these questions were 

undertaken in cooperation with Oklahoma State University, 

the University of Arkansas, and the Southern Research 

Station of the Forest Service. These studies were based on 

a completely randomized experimental design with three 

to four replications depending on the study. All studies 

included treatments of 1) thinning, WSI and burning with 

measurements taken 1, 2, and 3 years after the burn; and 

2) an untreated control. Some of the studies also included 

a thinning, WSI, and no burn treatment. The experimental 

units were all typical mature second-growth stands of 

mostly shortleaf pines ranging in age from 70 to 90 years, 

and averaging about 40 acres in size.

Biological and Physical Environmental Effects

Birds

Wilson and others (1995) studied the effects of restoration 

on populations of breeding birds. They found populations 

of 10 species signifi cantly greater in the treatments than 

the untreated controls, indicating benefi cial treatment 

effects. Among these species are the eastern wood-peewee 

(Contopus virens L.), a declining neotropical migrant, and 

the brown-headed nuthatch, a non-migratory species of 

conservation concern. Two neotropical migrant species of 

concern, the ovenbird (Seiurus aurocapillus L.) and blackand-white warbler (Mniotilta varia L.) had signifi cantly 

lower numbers in the treatments than the controls, indicating 

adverse effects. Some 27 species showed higher but non-
209

signifi cant population numbers in the treatments than in the 

controls, suggesting the possibility of benefi cial treatment 

effects. Among this group are the neotropical migrants 

Kentucky warbler (Oporornis formosus Wilson), rubythroated hummingbird (Archilocus colubris L.), greatcrested fl ycatcher (Myiarchus crinitus L.), yellow-breasted 

chat (Icteria virens L.), common yellowthroat (Geothlypis 

trichas L.), white-eyed vireo (Vireo griseus Boddaert), 

yellow-throated vireo (V. fl avifrons Vieillot), blue-gray 

gnatcatcher (Polioptila caerulea L.), and prairie warbler 

(Dendroica discolor Vieillot). Other species of conservation 

concern in this group were the red-cockaded woodpecker, 

Bachman’s sparrow, northern bobwhite, wild turkey 

(Meleagris gallopavo L.), and red-headed woodpecker 

(Melanerpes erythrocephalus L.). Some 10 species had nonsignifi cantly lower population numbers in treated stands, 

suggesting the possibility of adverse effects. Species of 

conservation concern in this group include the neotropical 

migrants scarlet tanager (Piranga olivacea Gmelin), 

Acadian fl ycatcher (Empidonax virescen Vieillot), and 

whip-poor-will (Caprimulgus vociferous Wilson). However, 

in a follow-up songbird study Masters and others (2002) 

found that the rate of occurrence of the Acadian fl ycatcher 

increased in the second and third year post-burn treatments 

as compared to the untreated control. In a subsequent study 

of northern bobwhites in the restoration area, Cram and 

others (2002) detected population increases ranging from 

5-fold to 19-fold in treated stands as compared to untreated 

controls, confi rming the benefi cial effects of treatments on 

this important game bird. 

In yet another study focused on habitat quality for early 

successional songbirds, Jennelle (2000) concluded that 

pre-commercial thinning and burning in stands of young 

trees, and commercial thinning and burning in stands of 

mature trees, provided suitable foraging and nesting habitat 

for several such species of conservation concern, including 

the prairie warbler, yellow-breasted chat, and common 

yellowthroat. Of special importance was the presence of 

hardwoods in the shrub layers of both treatments.

In response to restoration efforts and an aggressive 

translocation program, the red-cockaded woodpecker 

population has increased from about 32 adult birds and 13 

active territories in 1990, to some 88 adults and 37 active 

territories in 2006 (Figs. 5 and 6). Further, 40 or more young 

have been fl edged in fi ve of the last six breeding seasons 

(Fig. 6). 

Figure 4.—The red-cockaded woodpecker on a shortleaf 

pine, Ouachita NF (photo by Joe Neal).

Figure 5.—Changes in number of red-cockaded woodpecker 

territories and nesting attempts, 1990-2006, Ouachita NF.

Figure 6.—Changes in number of red-cockaded woodpecker 

adults and fl edglings, 1990-2006, Ouachita NF. 
210

Mammals

Masters and others (1998) found that populations of 

small mammals in treated stands increased in abundance 

and diversity; no species was adversely affected. Total 

community abundance, richness, and diversity were lowest 

in untreated controls. The authors concluded that restoration 

efforts may be particularly benefi cial to the white-footed 

mouse (Peromyscus leucopus Rafi nesque), golden mouse 

(Ochrotomys nuttalli Harlan), and fulvous harvest mouse 

(Reithrodontomys fulvescens Allen), species that may have 

historically depended on pine-grassland habitats. In a study 

to determine the effects of restoration on the production 

of forage for white-tailed deer (Odocoileus virginianus

Zimmermann), Masters and others (1996) found that 

preferred deer forage in treated stands was 6 to 7 times 

greater than untreated controls. Another mammal study 

currently underway is investigating habitat quality for the 

eastern spotted skunk (Spilogale putorius L.) in shortleaf 

pine-bluestem landscapes (Leismeister, unpublished data). 

Restored areas apparently are among the few places in 

Arkansas where this species of conservation concern can be 

regularly found. 

Other Taxa

Thill and others (2004) studied the effects of restoration 

on populations of amphibians and reptiles, butterfl y 

fauna and nectar sources, and moth fauna. In most years 

amphibian relative abundance, richness and diversity 

were comparable to or higher in restoration treatments 

than in untreated controls. Overall, values for reptile 

relative abundance, richness, and diversity were greater 

in the restoration treatments than in the controls, though 

the differences were generally not statistically signifi cant. 

Numbers of adult butterfl ies were lowest in the untreated 

controls, highest in the treated stands the fi rst year after 

burning, and intermediate in the second and third years after 

burningpresumably due to available nectar sources, which 

exhibited treatment effects nearly identical to numbers 

of adult butterfl ies. A butterfl y species of conservation 

concern, the Diana fritillary (Speyeria diana Cramer), was 

signifi cantly more abundant in treated stands. The moth 

fauna study yielded different results. For late summer 

and autumn, moth numbers showed a response similar to 

butterfl ies with higher relative numbers in the treatments 

than in the controls. However, the pattern in spring was 

reversed, with higher relative numbers of moths in the 

controls. Additional work is necessary to explain these 

differing seasonal responses.

Vegetation

Sparks and others (1998) identifi ed more than 150 

herbaceous species in their prescribed-burn study stands 

that were generally absent from untreated controls. Among 

these were some 40 species of native legumes whose 

nitrogen-fi xing activities augment soil fertility, and whose 

foliage and seeds provide an important source of food 

for wildlife. Species richness increased in restored stands 

after both late growing-season and late dormant-season 

prescribed fi res, and was lowest in unburned stands. Overall, 

herbaceous species richness, diversity, and total forb and 

legume abundance increased in treated stands as opposed to 

untreated controls. A key fi nding in the study is that season 

of burn infl uenced the numbers of fewer than 10 percent of 

the herbaceous species, and none were excluded by season 

of burning (Sparks and others 1998). It appears that none of 

the herbaceous species in the Ouachitas depend exclusively 

on summer burning to maintain their presence in these 

restored stands.

Soil and Foliar Nutrients

Liechty and others (2005) compared soil chemistry and 

foliar nutrients of treated stands with untreated controls. 

Mineralizable N, total N, C, Ca, and pH of surface soils 

were higher in treated stands than in the untreated controls. 

Foliar concentrations of N, P, and K were signifi cantly 

higher in treated stands for at least a year after burning, 

though only K concentrations remained higher for the entire 

3-year post-burn period. The authors concluded that surface 

soil fertility and productivity had improved in treated stands. 

Tree Growth

Over 4 years of a study comparing tree growth in restored 

and untreated controls, Guldin and others (2005) found no 

signifi cant differences in tree growth between treatments 

and controls. However, growth in both treated and untreated 

stands was substantially less than that predicted by a 

regional shortleaf pine growth model (Lynch and others 

1999); observed growth was 70 percent less than predicted 

by the model in treated stands, and 50 percent less than 

predicted in the controls (Guldin and others 2005). This 

unexpected outcome is possibly due to generally drier-thannormal weather conditions during the tree growth study. At 

any rate, the lower than expected tree growth rates were not 

due to treatment effects. 

ECONOMIC EFFECTS

Before considering the economic effects of restoration 

treatments, it should be understood that there is no law 

requiring that National Forest lands be managed for profi t. 

In fact, there is specifi c language in the National Forest 

Management Act of 1976 directing that managers should 

not select treatments based on a “greatest return” criterion. 

Nevertheless, it is useful to describe economic effects in 

terms of opportunities foregone so as to private landowners 

an idea of costs and returns should they be interested in 

applying these restoration prescriptions. 

Huebschmann (2000) used an input-output model to 

estimate the economic effects of shortleaf pine-bluestem 

restoration for red-cockaded woodpecker recovery over a 

100-year simulation period for a 155,000-acre study area in 
211

Scott County, AR. He compared present net value (PNV) 

for the area if managed under the restoration prescription 

with a 120-year rotation and low tree density, to what 

its PNV might be under a more traditional management 

prescription with a 70-year rotation and heavier stocking. 

He estimated that after 100 years the PNV for the restored 

area would be $111 million less than the PNV for the area 

had it been managed in a more traditional manner. This 

value translates into an opportunity cost of about $9.25 per 

year for each acre of pine in the study area. Most of this 

opportunity cost is attributable to the fact that old pine trees, 

of which there are many more on the landscape under a 

long-rotation restoration prescription, do not grow as fast as 

younger trees. The economic model was based on present 

average stumpage value for pines, and thus overestimates 

the economic costs if the future value of large old trees is 

signifi cantly greater, which is a distinct possibility. At this 

point, there is no reason to believe that an area managed 

under a restoration prescription would produce any 

dramatically different economic value than an area under 

traditional management provided that the rotation lengths 

are the same.

RESTORATION PROGRESS 

AND FUTURE CHALLENGES

From the work that began in the late 1970s as a treatment 

applied to a few acres surrounding red-cockaded 

woodpecker cavity tree clusters, the restoration efforts 

today have burgeoned to encompass landscapes at a scale 

of hundreds of thousands of acres. Since the adoption of 

the fi rst formal shortleaf pine-bluestem restoration decision 

document in 1994, the Ouachita National Forest has thinned 

52,992 acres, conducted mid-story reduction treatments on 

42,948 acres, and applied prescribed burning at least once 

on some 143,233 acres within restoration areas. Managers 

estimate that 18,653 acres are currently in a substantially 

restored condition.

Because of the scale of the undertaking, however, there are 

signifi cant challenges to achieving restoration objectives. 

Ultimately, almost 85,000 acres will likely have to be 

burned annually in order to maintain desired conditions 

in the restoration areas. State smoke management plans 

currently being implemented in Arkansas and under 

development in Oklahoma may limit the acreage that can 

be ignited in a single burn, and/or limit the total acreage 

that can be burned in a single day. Furthermore, the forest’s 

work force is aging, with fewer individuals able to meet 

the physical fi tness requirements each year for prescribed 

burning. These changes could make it more diffi cult to 

burn suffi cient acreage each year. Though herbicides have 

been used only sparingly to date, their use might have to 

be increased substantially if prescribed burning capability 

erodes. Further, prescribed burning which has historically 

been done only by Forest Service employees might have to 

be done by outside contractors.

SUMMARY

This conservation effort, which had its fi rst stirrings as 

a concern for an endangered species on a few scattered 

parcels of land, has grown with public support to encompass 

a commitment to restore a quarter million acres—a pace 

and a scale scarcely imaginable 15 years ago. It proceeds 

by utilizing elements of landscape ecology and restoration 

ecology supported by local research results published, 

for the most part, in peer-refereed scientifi c journals. It 

promises to substantially restore an ecosystem that was 

once widespread but is now rare. It offers the opportunity 

to develop self-sustaining populations of an endangered 

species and several other species of conservation concern 

that are presently underrepresented on the landscape. At the 

same time, the work maintains all of the traditional human 

uses of the land from logging and fi rewood gathering to 

hunting, hiking, and camping. This work enjoys the support 

of the conservation and lumber manufacturing communities, 

in addition to the general public. It integrates all of the 

conservation laws that govern management of National 

Forest lands. Finally, we and others think it restores an 

aesthetic beauty to the land not seen in many decades. 

As a result, we believe this work serves as an example 

of ecosystem renewal and as a showcase for appropriate 

management of National Forest lands. 

ACKNOWLEDGMENTS

We wish to acknowledge the efforts of the district rangers, 

foresters, wildlife biologists, and many technicians on the 

Ouachita National Forest who are primarily responsible for 

the day-to-day activities in implementing this extraordinary 

conservation work. We also acknowledge the assistance 

and support of our partners: Oklahoma State University, 

the University of Arkansas, the University of Missouri, 

the Southern Research Station of the USDA Forest 

Service, the Arkansas Game and Fish Commission, the 

Arkansas Natural Heritage Commission, the Oklahoma 

Department of Wildlife Conservation, the Oklahoma 

Biological Survey, The Nature Conservancy, Arkansas 

Audubon Society, National Wild Turkey Federation, and 

Quail Unlimited. Finally, we salute the contribution of the 

Ouachita Timber Purchasers Group who cheerfully compete 

among themselves to buy our timber and thereby make 

the entire restoration enterprise economically feasible and 

implementable on a large scale.

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214

THE OZARK HIGHLANDS PINE-OAK WOODLAND RESTORATION PARTNERSHIP

Tim A. Nigh1

ABSTRACT.—A partnership of more than 20 state, federal, and nongovernmental 

organizations has been formed to pursue and promote restoration of Shortleaf Pine-Oak 

Woodland ecosystems throughout the Ozark Highlands. This paper provides a brief overview 

of the partnership, its goals and strategies, partner organizations, and current activities.

INTRODUCTION

Shortleaf pine and shortleaf pine-oak woodlands once 

covered millions of acres in the Ozark Highlands and 

Boston Mountains of southern Missouri and northern 

Arkansas. Wholesale logging around the turn of the century 

and subsequent fi re suppression has signifi cantly reduced the 

acreage and quality of this ecosystem throughout the region. 

The Comprehensive Wildlife Conservation Strategies in 

both Missouri and Arkansas recognize this ecosystem and 

the numerous species it supports as a target for restoration 

efforts. Signifi cant interest and activity surrounds shortleaf 

pine-oak woodland restoration throughout the region on 

state, federal and private lands. 

Obstacles to successful region-wide restoration of this 

system are many. Principle among these obstacles is a 

lack of manpower and dollars to adequately carry out the 

management, including thinning, commercial harvest 

and prescribed fi re. In addition, creating markets and 

management techniques that allow harvest and utilization 

of small or sub-standard trees in the restoration process is 

also a challenge. Other challenges include inventory and 

monitoring, and the development of educational materials. 

PARTNERSHIP GOALS AND STRATEGIES

The Ozark Highlands Shortleaf Pine-Oak Woodland 

Restoration Partnership is a consortium of state, federal, and 

nongovernmental organizations dedicated to the region-wide 

restoration of shortleaf pine-oak woodlands. 

The goal of this partnership is to promote the development 

of a network of restored shortleaf pine-oak woodlands 

throughout the Ozarks at scales suitable to support 

populations of the numerous species it supports.

Principle strategies include:

1. Identify and map potential restoration sites 

throughout the region

2. Seek grants to support restoration activities

3. Develop sustainable harvest techniques that allow 

economically viable thinning and commercial harvest

4. Promote markets for small-diameter and substandard 

materials resulting from restoration activities

5. Promote markets for commercial pine sawlogs

6. Develop standard monitoring protocols, especially for 

target wildlife species

7. Develop and disseminate educational materials

8. Share information among partners

INITIAL PROJECT PARTNERS

The partnership is currently composed of 24 state, federal, 

and nongovernmental organizations. The cumulative 

knowledge and experience of the partners has established 

a foundation upon which the restoration of these valuable 

ecosystems can proceed. 

Missouri

Missouri Chapter – The Nature Conservancy

Missouri Audubon

Pioneer Forest

Mark Twain National Forest

U.S. Fish and Wildlife Service

Ozark National Scenic Riverways

Missouri Department of Natural Resources

Missouri Department of Conservation

Eastern Ozark Forest Consortium

Missouri Chapter National Wild Turkey Federation

American Bird Conservancy

1

Resource Scientist, Missouri Department of Conservation, 

1110 South College Ave., Columbia, Mo 65201. To contact or call: 

(573) 882-9909 Ext. 3244; Timothy.Nigh@mdc.mo.gov
215

Arkansas

Arkansas Chapter – The Nature Conservancy

Arkansas Audubon

Ozark National Forest

USDA Southern Research Station

U.S. Fish and Wildlife Service

Natural Resource Conservation Service

U.S. Army Corps of Engineers

Buffalo National Scenic Riverways

Arkansas State Parks

Arkansas Game and Fish Commission

Arkansas Natural Heritage Commission

Arkansas Chapter Quail Unlimited

Arkansas Chapter National Wild Turkey Federation

In addition to providing the land base, these partners will 

provide individual commitment to restoring pine oak 

woodlands and associated habitats through ongoing annual 

programs tied to comprehensive long range management 

plans. These partners will also provide the tools and 

technical experience essential for success. In summary, 

partners and plans are in place to make this project a success 

while making the most effi cient use of funding.

CURRENT AND FUTURE ACTIVITIES

Thirty-four pine-oak woodland restoration sites, 

encompassing more than 230,000 acres, were identifi ed by 

the partnership at its fi rst meeting (Fig. 1). A dozen sites 

were included in a grant request to the National Fish and 

Wildlife Foundation for 2006 restoration activities on more 

than 6500 acres. The partnership was awarded a $100,000 

grant in August 2006. In addition to initiating management, 

the funds will be used to create an informational brochure 

and to host fi eld tours.

The partnership is having its second annual meeting in 

conjunction with this symposium. We plan to pursue 

additional grants to continue restoration activities. We also 

hope to fund an economic analysis of restoration benefi ts 

and a fi eld demonstration of various alternative harvest 

techniques.

If you are interested in participating in the Ozark Highlands 

Pine-Oak Restoration Partnership, please contact the author 

(TN).

Figure 1.—Ozark highlands pine-oak woodland restoration 

sites. 
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and 

activities on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, 

sexual orientation, and marital or family 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 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 provider and employer.

Printed on recycled paper

Kabrick, John M.; Dey, Daniel C.; Gwaze, David, eds. 2007. Shortleaf pine 

restoration and ecology in the Ozarks: proceedings of a symposium. Gen. 

Tech. Rep. NRS-P-15. Newtown Square, PA: U.S. Department of Agriculture, 

Forest Service, Northern Research Station. 215 p.

Contains 27 papers and 14 extended abstracts from the symposium “Shortleaf 

Pine Restoration and Ecology in the Ozarks” held November 7-9, 2006, at the 

University Plaza Hotel and Convention Center in Springfi eld, MO. 

Keywords: woodland restoration, southern pines, pine regeneration and 

management, tree improvement, wildlife diversity
Capitalizing on the strengths of existing science capacity 

in the Northeast and Midwest to attain a more integrated 

cohesive landscape scale research program