United States 

Department of 

Agriculture

Forest 

Service

Northern 

Research Station

General Technical 

Report NRS-P-102

Proceedings of the 4th 

Fire in Eastern Oak 

Forests Conference
Visit our homepage at: http://www.nrs.fs.fed.us/

Published by: For additional copies, contact:

USDA FOREST SERVICE USDA Forest Service

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October 2012 Fax: 740-368-0152

Manuscript received for publication February 2012

Abstract

Contains 14 full-length papers and 40 abstracts of posters that were presented at the 4th Fire in 

Eastern Oak Forests conference, held in Springfield, MO, May 17-19, 2011. The conference was 

attended by over 250 people from 65 different organizations and entities, representing 22 states 

and 1 Canadian province.

Cover Photo

Prescribed burn to restore a Missouri Oak savanna and woodland by Lee Wilbeck, 

Missouri Department of Natural Resources, State Parks; used with permission.

Acknowledgments

The steering committee thanks the Missouri University Conference Office and in particular Angela 

Freemyer, Conference Coordinator, Lindsay Kilgore, Administrative Assistant, and Sharon Rodes, 

Graphic Designer. We also extend our thanks to the management and staff of the University 

Plaza Hotel for our conference and hotel accommodations. Special thanks go to Nancy Bastin, 

Southern Research Station, for formatting all papers and abstracts in this proceedings. Special 

thanks also go to Reggie Bray, Jody Eberly, Paul Nelson, and other staff of the U.S. Forest 

Service Mark Twain National Forests for their leadership and contributions in the Glade Top Trail 

and shortleaf pine restoration field trips, to Ken McCarty, Allison Vaughn, and Tim Smith of the 

Missouri Department of Natural Resources, State Parks for their contributions to the field trip at 

Roaring River State Park, and to Sherry Leis, Missouri State University Biology Department for 

leading a tour on ecosystem restoration at the National Park Service Wilson’s Creek National 

Battlefield Park.

This conference was dedicated to the memory of Alan Zentz (1953-2010), who was a 

long-standing supporter of this gathering.

Alan joined the U.S. Forest Service in 1999 as the Cooperative Fire Program Specialist for 

the Northeastern Area. Throughout his career he worked to improve forest fire protection 

for millions of people in the Northeast. He provided response assistance with the Federal 

Emergency Management Agency at the World Trade Center following the attack of 9/11, 

and on hurricanes Katrina and Rita. His work in the arena of emergency response helped 

provide a foundation for incident management implementation throughout the nation. Alan 

will be missed by all who knew him for his wit, humor, and dedication to his family and the 

fire program he served so well.

The findings and conclusions of each article in this publication are those of the individual author(s) and 

do not necessarily represent the views of the U.S. Department of Agriculture or the Forest Service. 

All articles were received in digital format and were edited for uniform type and style. Each author is 

responsible for the accuracy and content of his or her paper.

The use of trade, firm, or corporation names in this publication is for the information and convenience of 

the reader. Such use does not constitute an official endorsement or approval by the U.S. Department of 

Agriculture or the Forest Service of any product or service to the exclusion of others that may be suitable.
Proceedings of the 4th 

Fire in Eastern Oak Forests Conference

May 17-19, 2011

University Plaza Hotel

Springfield, MO

Edited by

Daniel C. Dey

U.S. Forest Service, Northern Research Station

Michael C. Stambaugh

University of Missouri-Columbia, The School of Natural Resources, Dept. Forestry

Stacy L. Clark

U.S. Forest Service, Southern Research Station

Callie J. Schweitzer

U.S. Forest Service, Southern Research Station

Steering Committee

Mary Arthur, University of Kentucky, Department of Forestry

Reggie Bray, U.S. Forest Service, Mark Twain National Forest

Stacy L. Clark, U.S. Forest Service, Southern Research Station

Daniel C. Dey (Chair), U.S. Forest Service, Northern Research Station

Matthew B. Dickinson, U.S. Forest Service, Northern Research Station

Daniel Drees, USDI National Park Service, Ozark National Scenic Riverways

Jody Eberly, U.S. Forest Service, Mark Twain National Forest

Todd Hutchinson, U.S. Forest Service, Northern Research Station

Sherry Leis, Missouri State University Biology Department

Ken McCarty, Missouri Department of Natural Resources, State Parks

Paul W. Nelson, U.S. Forest Service, Mark Twain National Forest

Tim Perren, U.S. Forest Service, Mark Twain National Forest

Charles Ruffner, Southern Illinois University-Carbondale, Department of Forestry

Callie J. Schweitzer, U.S. Forest Service, Southern Research Station

Martin A. Spetich, U.S. Forest Service, Southern Research Station

Michael C. Stambaugh, University of Missouri-Columbia, 

The School of Natural Resources, Department of Forestry

Allison Vaughn, Missouri Department of Natural Resources, State Parks
Sponsors

Joint Fire Science Program 

Missouri Department of Natural Resources 

Missouri State University, 

Department of Biology 

University of Missouri, 

The School of Natural Resources, 

Department of Forestry

U.S. Forest Service Mark Twain National Forest 

U.S. Forest Service 

Northeastern Area State & Private Forestry 

U.S. Forest Service Northern Research Station 

U.S. Forest Service R9-Eastern Region 

U.S. Forest Service Southern Research Station

National Park Service 

Wilson’s Creek National Battlefield 

In cooperation with the MU Conference Office

Angela Freemyer, Conference Coordinator

Lindsay Kilgore, Administrative Assistant

Sharon Rodes, Graphic Designer for program

Review Process

Each paper was peer-reviewed by two reviewers. The authors worked with the editors to 

revise their manuscripts, based on the reviewer’s comments. Revised manuscripts were 

edited for formatting by Nancy Bastin, U.S. Forest Service, Southern Research Station, 

and then submitted to the Northern Research Station Production Services for technical 

editing and design. Reviewers were: Christopher Webster, Michael Jenkins, Jesse 

Burton, Terry Bidwell, Scott Nielsen, Charles Lafon, Justin Hart, Richard Guyette, Lyndia 

Hammer, Mike Leahy, Ryan McEwan, Joe Marschall, Mike Stambaugh, David Engle, 

Nathan Klaus, David King, Martin Spetich, Susan Loeb, Joy O’Keefe, William Sutton, 

David Steen, Greg Spyreas, and Greg Nowacki.
This conference was a major symposium focused on fire in oak forests, woodlands, and 

savannas where noted experts in research and management gathered to present stateof-the-art information, perspectives and synthesis on key issues. The conference has 

been held previously in:

• Carbondale, IL (2008): Forest and fire management, effects and modeling in the 

Central Hardwood Region 

• Columbus, OH (2005): Delivering science to land managers 

• Richmond, KY (2000): a workshop on fire, people and the Central Hardwoods 

landscape 

This symposium took place in the most western location of the eastern deciduous forests 

in the conference’s history. This is a landscape that is really different than those that 

have been represented at the previous conferences, a land that has a rich history of 

human settlement and fire use, and where managers have been using prescribed fire 

for more than 30 years on large-scale to landscape scale projects. The theme of this 

conference was “Managing Oak Woodlands & Savannas in the Forest-Prairie Region”. 

The conference featured 15 invited presentations and 45 posters by scientists and 

managers from around the United States, who provided information on fire use and 

effects on a wide range of topics including: 

• Human, fire and natural history of the region – foundations of understanding and 

basis for restoration 

• Examples of restoring oak-pine woodlands and savannas from Texas, Arkansas, 

Missouri, and Oklahoma

• The history and current use of fire in natural resource public agencies in the 

Midwest 

• Grazing and fire interactions in grasslands 

• The role of fire in the southern Appalachian Region during the Holocene 

• Managing woodlands and savannas for songbirds, bats, and reptiles 

• Managing invasive species in woodland and savanna restoration 

• Tools for assessing disturbance risk and management options

• Introduction of the Midwest Oak Woodland and Forest Fire Consortium

Many of the presentation topics were reinforced by the four field tours that featured the 

rich and relatively long-term history of using prescribed fire to manage for a wide range 

of natural resource and conservation objectives. There was a mix of topics on using fire 

to manage vegetation and wildlife and restore native ecosystems presented by scientists 

and managers who are noted leaders in the use of prescribed fire in this region.

More than 250 people attended the conference representing 22 states, 1 Canadian 

province, and 65 different organizations, institutions, agencies, and private entities.

We were glad to host you in Missouri. I hope your time here was richly rewarded by the 

fine presentations and field tours, by good fellowship with each other, and by your active 

participation in all our discussions. 

Dan Dey

Welcome
Cloak of Darkness

By Dan Dey

May 9, 2011

Campfire kindled for evening meal,

burns bright to turn back the night intruder.

We stoke the flames with one more branch,

taken from yonder wood.

With deafness to the call for slumber,

we dance as flames in merry delight.

Now in silence, we gaze in eternal wonder,

into the depths of fiery magic.

Drawn close, by visual splendor,

until we cannot stand the heat.

Minds grope for answers to grand questions,

pondered by the generations,

refined like metal through endurance,

we long to find the truth we seek.

Photo by http://armedwithvisions.com
Characteristics of Eastern U.S. Oak Fire Regimes . . . . . . . . . . . . . . . . . . . . . 1

Fire History in a Southern Appalachian Deciduous Forest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Norman L. Christensen, Jr., and Kurt Fesenmeyer

Anthropology of Fire in the Ozark Highland Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

David H. Jurney

History of Fire in Eastern Oak Forests and Implications for Restoration . . . . . . . . . . . . . . . . . . 34

Justin L. Hart and Megan L. Buchanan

Fire and Vegetation Dynamics in the Cross Timbers Forests 

 of South-Central North America . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Steve W. Hallgren, Ryan D. Desantis, and Jesse A. Burton

Fire Ecology of Oak Ecosystems: The Basis for Management . . . . . . . . . 67

Oak Savanna Restoration: Oak Response to Fire and Thinning through 28 Years . . . . . . . . . . 69

Ronald E. Masters and Jack R. Waymire

Fire-adapted Natural Communities of the Ozark Highlands 

 at the Time of European Settlement and Now . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Paul W. Nelson

Fire History, Windstorm Disturbance, and Temporal Change 

 in an Outlier Oak-Shortleaf Pine Community . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

Michael D. Jones and Marlin L. Bowles

An Overview of Prescribed Fire in Arkansas and Oklahoma over the Last 40 Years . . . . . . . . 119

Roger D. Fryar

From the Field: Fire Management In Oak Forest Ecosystems . . . . . . . . . 125

Restoring Fire Suppressed Texas Oak Woodlands to Historic Conditions 

 Using Prescribed Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Jeff C. Sparks, Michael C. Stambaugh, and Eric L. Keith

Fire Management and Woody Invasive Plants in Oak Ecosystems . . . . . . . . . . . . . . . . . . . . . . 142

Joanne Rebbeck

Animal Populations and Fire-Maintained Oak Ecosystems . . . . . . . . . . . . 157

Songbirds in Managed and Non-managed Savannas and Woodlands 

 in the Central Hardwoods Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

Frank R. Thompson III, Jennifer L. Reidy, Sarah W. Kendrick, and Jane A. Fitzgerald

A Review of Fire Effects on Bats and Bat Habitat in the Eastern Oaks Region . . . . . . . . . . . . 170

Roger W. Perry

Responses of Timber Rattlesnakes to Fire: Lessons from Two Prescribed Burns . . . . . . . . . 192

Steven J. Beaupre and Lara E. Douglas

An Emerging Fire Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

Genesis of an Oak-Fire Science Constortium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

Keith W. Grabner, Michael C. Stambaugh, Richard P. Guyette, Daniel C. Dey, and Gary D. Willson

Contents
Extended Abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

Growth Response of Mature Oaks Following TSI and Prescribed Burning Treatments . . . . . 215

Margaret Anderson, Eric J. Holzmueller, Charles M. Ruffner, and John W. Groninger

Using Remotely-sensed Imagery to Monitor Post-fire Forest Dynamics 

 in Upland Oak Forests on the Cumberland Plateau, Kentucky . . . . . . . . . . . . . . . . . . . . . . . . 217

Mary Arthur, Christine McMichael, and Gretchen Sovkoplas

Firestem II - A 2-D Heat Transfer Model 

 for Simulation of Stem Damage in Prescribed Fires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

Efthalia K. Chatziefstratiou, Gil Bohrer, Anthony S. Bova, and Matthew B. Dickinson

Effects of Two Prescribed Fires on Red Maple Regeneration 

 across Four Levels of Canopy Cover in Northern Lower Michigan . . . . . . . . . . . . . . . . . . . . 223

William W. DeBord, David S. Buckley, Terry L. Sharik, Jason P. Hartman, and Jason G. Henning

Tall Larkspur Benefits from Fire in Chinkapin Oak Woodlands . . . . . . . . . . . . . . . . . . . . . . . . . 226

Dan Drees

Local Collared Lizards Needed Landscape-scale Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

Dan Drees

Effects of Wildfires and Liming of Pine-Oak-Heath Communities 

 in the Linville Gorge Wilderness, Western North Carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230

Katherine J. Elliott, James M. Vose, Jennifer D. Knoepp, and William Jackson

Communities and Density Estimates of Historical and Current Missouri Ozarks Forests . . . 235

Brice B. Hanberry, Hong S. He, Daniel C. Dey, John M. Kabrick, and Brian J. Palik

Restoring Oak Regeneration after Overgrazing and Fire in Zagros Forests . . . . . . . . . . . . . . . 237

Azad Henareh Khalyani, Audrey L. Mayer, and Manouchehr Namiranian

Initiating Restoration of Woodland Communities: the Effect of Thinning 

 and Prescribed Fire on Stand Structure in the Ozarks Highlands . . . . . . . . . . . . . . . . . . . . . 241

Carter O. Kinkead, John M. Kabrick, Michael C. Stambaugh, and Keith W. Grabner

Effects of Multiple Intense Disturbances at Manley Woods, 

 Wilson’s Creek National Battlefield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245

Sherry A. Leis and Kevin James

Potential Effects of Fire and Timber Harvest 

 on Terrestrial Salamander Microhabitat Use in a Missouri Ozark Forest . . . . . . . . . . . . . . . . 248

Katherine M. O’Donnell, Frank R. Thompson III, and Raymond D. Semlitsch

Soil and Litter Nutrients Following Repeated and Periodic Burning 

 in the Missouri Ozarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252

Felix Ponder, Jr.

Herbaceous Understory and Seed Bank Response to Restoration Efforts 

 at an Oak-Pine Barrens in Central Wisconsin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255

Jeffrey L. Ralston and James E. Cook

Prescribed Fire and Thinning Impacts on Fine Fuels 

 at the William B. Bankhead National Forest, Alabama . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

Callie Jo Schweitzer and Stacy L. Clark

Simulating Treatment Effects in Pine-Oak Forests of the Ouachita Mountains . . . . . . . . . . . . 259

Ayn Shlisky, Kori Blankenship, and Shawn M. Cochran

Vegetation Structure and Soil Water Content after 60 Years 

 of Repeated Prescribed Burning in the Missouri Ozarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262

Kirsten Stephan and Jason A. Hubbart
Abstracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

Restoration of High Elevation Red Oak with Fire in the Southern Blue Ridge . . . . . . . . . . . . . 267

Peter Bates, Dean Simon, Gary Kauffman, Margit Bucher, Jon Shaffer, and Rob Lamb

Comparing the Importance Value of Overstory and Understory Trees in Oak Forests . . . . . . 268

Chad Bladow

The Effects of Seasonally Prescribed Fire on a Dolomite Glade . . . . . . . . . . . . . . . . . . . . . . . . 269

Mary Ann Blinkhorn and D. Alexander Wait

Researching Effects of Prescribed Fire in Hardwood Forests . . . . . . . . . . . . . . . . . . . . . . . . . . 270

Stacy L. Clark, Kathleen E. Franzreb, Cathryn H. Greenberg, Tara Keyser, Susan C. Loeb, 

David L. Loftis, W. Henry McNab, Joy M. O’Keefe, Callie Jo Schweitzer, and Martin Spetich

Small Mammal Occurrence in Oak Woodlands and Restored Savannas . . . . . . . . . . . . . . . . . 273

Valerie J. Clarkston and Patrick A. Zollner

Vector Analysis of Response of Advance Reproduction 

 to Repeated Prescribed Burning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274

Zhaofei Fan and Daniel C. Dey

Woodland Restoration in the Ozark Highlands of Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275

Allison Fowler, Douglas Zollner, and John Andre

Response of Seasonal Bird Species Densities to Habitat Structure 

 and Fire History along an Open-Forest Gradient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276

Ralph Grundel and Noel B. Pavlovic

The Trace of Fire in Eastern Native America . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277

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

Rose M. Muzika, and Joseph M. Marschall

Climate and Physical Chemistry in Eastern Fire Regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

Richard P. Guyette, Michael C. Stambaugh, Rose M. Muzika, and Daniel C. Dey

Influences of Topography and Fire on Eastern Red Cedar 

 (Juniperus virginiana) Distribution in a Prairie-Forest Transition Zone . . . . . . . . . . . . . . . . . 279

Lyndia D. Hammer and Michael C. Stambaugh

Dendrochronological Determination of Historical Fire Occurrence 

 and Recruitment in a Southern Illinois Oak-Hickory Forest . . . . . . . . . . . . . . . . . . . . . . . . . . 280

J.M. Harris, Charles M. Ruffner, M. Therrell, and C.K. Nielsen

Oak-Grassland Restoration at Land Between the Lakes National Recreation Area: 

 Preliminary Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

Jaime A. Hernandez and Elizabeth F. Danks

The Effects of Prescribed Burning on the Black Kingsnake: 

 Going Beyond the Demographic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

Christopher A.F. Howey and Willem M. Roosenburg

Multiple Burns Pave the Way for Improved Oak-Hickory Regeneration 

 in Canopy Gaps in Southern Ohio Forests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283

Todd F. Hutchinson, Elaine Kennedy Sutherland, Robert P. Long, 

Joanne Rebbeck, and Daniel A. Yaussy

Association of Fire Season, Fire Front, and Fire Temperature 

 on the Mortality of Early Successional Persimmon and Sweetgum Trees . . . . . . . . . . . . . . . 284

Paul Killian, Joe Robb, and Darrin Rubino

Post-fire Susceptibility of Habitats to Invasion by Seed of Oriental Bitter-sweet . . . . . . . . . . . 285

Stacey A. Leicht-Young, Noel B. Pavlovic, and Ralph Grundel
Abstracts (continued)

Determining Lumber Value Changes in Fire-injured Oak Trees . . . . . . . . . . . . . . . . . . . . . . . . . 286

Joseph M. Marshall, Richard P. Guyette, Michael C. Stambaugh, and John Dwyer

Estimating Fuel Consumption during Prescribed Fires in Arkansas . . . . . . . . . . . . . . . . . . . . . 287

Virginia L. McDaniel, James M. Guldin, and Roger W. Perry

Fire Effects on the Resprouting and Total Nonstructural Carbohydrates 

 of the Highly Invasive Oriental Bittersweet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

Noel B. Pavlovic, Stacey A. Leicht-Young, and Ralph Grundel

Changes in Forest Understory Associated with Redcedar Encroachment 

 in Fire Suppressed Quercus stellata Forests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290

Paul van Els, Rodney E. Will, Michael W. Palmer, and Karen R. Hickman

From Spring Ephemerals to Light to Fungi: Plant Dynamics in an Ozark Oak/Hickory- 

 Forest/Woodland Community Managed for Wildlife through Prescribed Burns . . . . . . . . . . . 291

D. Alexander Wait and Mary Ann Blinkhorn

Prescribed Burning in an Upland Oak Forest Reduced Litter N, Soil Organic C, 

 and Gram Negative Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292

Ryan J. Williams and Steve W. Hallgren
Characteristics of 

Eastern U.S. Oak 

Fire Regimes
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Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 

FIRE HISTORY IN A SOUTHERN APPALACHIAN DECIDUOUS FOREST

Norman L. Christensen, Jr. and Kurt Fesenmeyer

Research Professor (NLC), Nicholas School of the Environment, Duke University, A124 LSRC, 

Box 90328, Durham, NC 27708; GIS Specialist (KF). NLC is corresponding author: 

to contact, call 919-613-8052 or email at normc@duke.edu.

Abstract.—Because there are few long-term dendrochronological and lake sediment data 

for the southern Appalachians, little is known regarding the history of fire in this region’s 

forests through the Holocene. Radio-carbon ages for 82 soil charcoal samples collected 

from local depositional sites along a topographic gradient from mixed hardwood 

(Liriodendron tulipifera and Quercus spp.) to oak-pine (Quercus prinus and Pinus rigida) 

forest provide a coarse-grained picture of changes in fire frequency within a 10-ha area 

during the Holocene. Fires were frequent over the past 4,000 years, and their frequency 

appears to have increased significantly about 1,200 years before present (YBP), 

coinciding with the advent of the Mississippian Native American culture in this region. 

Our results are consistent with the widely held view that fires have become less frequent 

in this region over the past 250 years. The inbuilt error associated with estimating actual 

fire dates from charcoal fragments inherently limits our ability to infer the specifics of 

and changes in fire regime over time. Notwithstanding these uncertainties, it is clear that 

fire has been an important part of eastern deciduous forest ecosystems through much of 

the Holocene. Nevertheless, fire regimes and forest composition have likely changed 

during this time owing to changes in human activities and climate. These facts have 

important consequences for restoration and fire management.

Introduction

Up to the late 20th century, most ecologists tacitly 

assumed that fire was not an important factor in 

eastern deciduous forests. Nowhere is fire mentioned 

in E. Lucy Braun’s monographic treatment of this 

biome (Braun 1950). Oosting (1942) likewise omitted 

any mention of fire in his survey of the successional 

and mature communities of the eastern Piedmont. 

Whittaker (1956) speculated that wildfire played an 

important role in the maintenance of ridge top shrub 

and pine dominated communities of the southern 

Appalachians but not in deciduous hardwoods. 

Nevertheless, early explorers and settlers often 

described the vegetation of these regions as woodlands 

with open grassy understory conditions indicative of 

high frequency, low intensity fire regimes (Bartram 

1791, Lawson 1701). The prevalence of fire-adapted 

oaks (Quercus), hickory (Carya) and chestnut 

(Castanea) supports this assessment. Occasional stand 

replacement fires may have been important during 

times of severe drought, particularly if occurring after 

canopy disturbance (e.g., blowdown) when dead and 

down fuel levels were high (Abrams 1992, Brown 

2002). 

Nowadays, there is general agreement that fire played 

an important role in presettlement deciduous forests, 

and debate has shifted to the nature and frequency 

of fire in the array of mixed pine-hardwood and 

hardwood communities along topographic and 

moisture gradients (Brose and others 2001, Delcourt 

and Delcourt 1997, Runkle 1985, van Lear and 

Waldrop 1989). It is almost certainly the case that 

fire regimes changed through the Holocene with 
GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

changes in climate and use of fire by Native Americans 

(Delcourt and Delcourt 1997, Delcourt and others 

1986, Gragson and others 2008, Springer and others 

2010), and the changes following European settlement 

were even more pronounced (MacCleery 1996, 

Nowacki and Abrams 2008, Yarnell 1998). During the 

17th and 18th centuries, increased human access, land 

clearing, and altered fuel conditions likely increased 

the frequency of fires (Jurgelski 2008). Over most of 

the last century, however, active fire suppression and 

landscape fragmentation have reduced fire frequency 

in most areas (Jurgelski 2008). Nowacki and Abrams 

(2008) argue that successional change in the absence 

of fire has “mesophied” eastern deciduous forests, that 

is, it has altered forest composition and structure in 

ways that have greatly diminished flammability and, 

therefore, fire likelihood across this entire region.

The nature of presettlement fire regimes and 

the changes that have occurred in those regimes 

since European settlement are quite relevant to 

modern forest management. They are key to our 

interpretation of the likely composition and structure 

of presettlement forests and, thus, to the establishment 

of targets for forest restoration (Nowacki and Abrams 

2008, Scharf 2010). They are important to our 

understanding of the likely responses of species to 

the increased use of prescribed fire for understory 

fuel management and forest restoration. Finally, land 

managers need such information in order to emulate 

historic disturbance regimes through silvicultural 

practices (Engstrom and others 1999, Kimball and 

others 1995, Vose and others 1999). While regional 

understanding of fire occurrence and frequency is 

useful, we are most in need of stand-level information 

on fire return intervals and fire behavior.

Dendrochronological studies in the Appalachians have 

provided useful information regarding fire frequency 

in oak-pine dominated forests during the past several 

centuries (Abrams and others 1995, Guyette and Cutter 

1991, Nowacki and Abrams 1997, Ruffner and Abrams 

2002, Schuler and McClain 2003, Shumway and 

others 2001). However, fire-scarred trees older than 

400 years are exceedingly rare in this region.

Charcoal in wetland or lake sediments has been 

used to evaluate changes in fire occurrence at 

watershed or regional scales (Delcourt and Delcourt 

1997, Delcourt and others 1986), but appropriate 

depositional environments are rare over much of 

this biome. Springer and others (2010) combined 

analyses of isotopic anomalies in stalagmite carbon 

with radiocarbon dates of sediment charcoal from a 

West Virginia cave to infer changes in fire regimes 

and human land use in the area surrounding the cave. 

These studies provide insights into long-term changes 

in the frequency of fire on landscapes surrounding the 

sample sites. They do not reveal much information 

about fire regimes at the scale of individual stands or 

variation in fire regimes among forest communities 

within a watershed. Welch (1999) used soil charcoal 

to verify the past occurrence of fire in southern 

Appalachian pine stands, but charcoal fragments were 

not carbon dated and it is not clear when these fires 

occurred.

Here we summarize our recent study (Fesenmeyer 

and Christensen 2010) in which we used radiocarbon 

dating of small pieces of charcoal in soil to reconstruct 

the presettlement, stand-level fire history along a 

topographic gradient in a southern Appalachian forest. 

We discuss both the limitations and the values of that 

study both to our understanding of the changing role 

of fire during the Holocene and the application of that 

understanding to restoration management. 

METHODS

Our study was carried out in the Wine Spring Creek 

Ecosystem Management Area (WSCEMA) of the 

Nanatahala National Forest in Macon County, North 

Carolina (35°N latitude, 83°W longitude). The 

WSCEMA is located on the western slope of the 

Nantahala Mountains. Sampling was done over an area 

of approximately 10 ha at 1,280-1,430 m elevation, 

extending from a perennial stream across a southsouthwest-west facing slope to a ridge top. The sample 

area was selected because it included the gradient of 

vegetation from hemlock-hardwood cove near streams 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102

through mixed-oak hardwood on hill slopes to chestnut 

oak-pine forests on the ridge top. Live pitch pine trees 

were widely scattered on the ridge top; dead boles and 

logs of this species were more abundant, suggesting 

that its abundance has decreased over the past several 

decades. The well-developed soil A horizon indicated 

that this site had never been subjected to agriculture. 

A 1997 prescribed fire at this site provided abundant 

charcoal of recent age for comparison. Other research 

from WSCEMA has focused on the effects of this 

prescribed fire and is described in Elliott and others 

(1999) and Vose and others (1999). There was no 

record nor was there any evidence at this site of any 

other fires in the past century.

Wood charcoal is an inert and recalcitrant form of 

carbon that can persist in soils for millennia following 

fires (De Lafontaine and others 2011). Although 

charred material may be transported significant 

distances by wind and water, the vast majority of 

charcoal that accumulates in depositional locations 

(such as small depressions) within a forest likely 

originated within a few tens of meters of those 

locations (Blackford 2000, Higuera and others 2007). 

Thus, the range of charcoal ages at sites likely reflects 

the history of fire at or very near that site. 

Sediments containing significant amounts of 

charcoal often accumulated immediately upslope and 

downslope from rock outcrops (height = 0.5 to 3 m) 

scattered across the study area. Using a slide hammer 

soil sampler, we obtained 5 cm diameter intact soil 

cores from 33 rock-outcrop locations. After removing 

the O horizon (duff layer), we collected soil cores 

varying from 10 to 30 cm depending on the depth 

to bedrock at each sample location. For purposes 

of comparison, sample sites were divided into two 

groups—xeric (ridge top and upper slope oak-pine 

sites) and mesic (downslope hardwood sites)—based 

on overstory vegetation cover.

In the laboratory, soil cores were divided into 2 cm 

sections, taking care to preserve the stratigraphy of 

the sample. The details of laboratory treatment and 

selection of charcoal fragments (1-50 mg each) are 

described in Fesenmeyer and Christensen (2010). 

A total of 82 individual charcoal fragments from 18 

sample locations were selected for carbon dating. 

This number was determined by funding available for 

carbon dating. Fragments were selected to represent 

entire core horizons among different vegetation types 

on the site. The calibrated 14C radiocarbon date and 

radiometric error of each fragment was determined 

using accelerator mass spectrometry (AMS) (Reimer 

and others 2004). The radiometric (2 sigma) error 

associated with AMS dates varied among samples 

from as little as 20 years to as much as 400 years. 

These data were subjected to cumulative probabilities 

analysis (Meyer and others 1992) using the “sum 

probabilities” option in CALIB 5.0.1 (Lafortune and 

others 2006, Stuiver and others 2005). This analysis 

allowed us to represent for a given year the relative 

probability that any fire represented in our dataset 

occurred at the site.

The calibrated radiometric age and error of a charcoal 

fragment corresponds not to the age of a fire event, 

but to the time when the wood that comprises a 

charcoal fragment was actually produced. The socalled “inbuilt error” of a date is estimated by the 

probability distribution of the difference between the 

date of carbon assimilation into wood and the date of 

the fire event that consumed and converted the wood 

to charcoal (Carcaillet 1998, Gavin 2001). The inbuilt 

error is additive to the radiometric error, and it is 

typically assumed to depend on stand age structure and 

the rate of wood decay in the ecosystem (Gavin 2001, 

Gavin and others 2003). However, the age distribution 

of charcoal remaining after a fire is also influenced by 

the prevailing fire regime itself, because fire frequency 

and intensity affect both the amount of available fuel 

and how much is actually charred (Higuera and others 

2005). 

RESULTS

Calibrated carbon dates ranged in age from 0 

(probably corresponding to the 1997 prescribed fire 

in this area) to 4,000 years before present (YBP), 
GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

with the exception of one fragment dated at 10,560 

±120 years. This was so far outside the range for all 

other samples that it was not considered in subsequent 

analyses. However, this very old fragment is evidence 

that fires occurred at this site in the early Holocene at 

about the same time that humans first occupied this 

region (Gragson and others 2008). Charcoal sample 

ages (± 2 sigma) are arrayed according to age and site, 

and the summed probability distributions for the two 

site groups are plotted in Figure 1. This distribution of 

relative probabilities suggests that fires have regularly 

occurred at xeric oak-pine sites over the past 4,000 

years. The record of fire events at mesic hardwood 

sites begins about 2,000 yr ago. There is a relatively 

abrupt increase in the relative probability of a year 

being represented in our charcoal sample at about 

1,000 YBP in both xeric and mesic sites. 

Figure 1.—A) Ages of 82 charcoal fragments arrayed by calibrated ARM date with 2-sigma error bars. Note that 2-sigma 

errors are discontinuous for some ages. B) The frequency of charcoal ages in 250 year time bins. C) The summed probability 

that any fire represented in our dataset occurred at the site. (Figure used with permission from Fesenmeyer and Christensen 

2010).
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102

Using Gavin’s methodology and age-distributions 

(Gavin 2001, Gavin and others 2003) for existing 

forests and wood decay rates for this region suggested 

by Harmon and others (1986), the inbuilt error for 

the oak-pine forests is likely between +50 and +100 

years, although without knowledge of the actual fire 

regime, this estimate is quite uncertain. Therefore, 

the most probable dates of fire events are, on average, 

50-100 years younger than the most probable 

radiometric dates of charcoal fragments. Furthermore, 

the radiometric errors used in the summed probability 

analysis underestimate the total error surrounding 

estimated dates of fire events. Thus, it is not possible 

to determine whether charcoal fragments with ages 

that differ by less than 150-200 years are products of 

the same fire or of different fires.

Fires clearly have occurred regularly on this forested 

slope over the past 4,000 years. Furthermore, fires 

were not confined to ridge top sites that currently 

support oak-pine forests, but they extended into 

areas that are today dominated by mesic hardwood 

communities. That no charcoal fragments > 2020 YBP 

were found in mesic hardwood sites may have been 

due to unequal sampling effort rather than inherent 

differences in fire regime between site types. However, 

it is well established that their moist, flaccid litter 

renders mesic hardwood ecosystems more resistant 

to fire than other forest types (Nowacki and Abrams 

2008). 

The number of samples represented in particular age 

bins diminishes with increasing charcoal age. This 

pattern of diminishing data with time is inherent in 

virtually all historical data sets (Egan and Howell 

2001). However, the abrupt appearance 4,000 YBP of 

regular fires and the marked increase in the summed 

relative probability of charcoal ages at 1,000 years 

are consistent with historical trends in human activity 

and fire frequency hypothesized for the southern 

Appalachians by Delcourt and Delcourt (1986, 1998). 

DISCUSSION AND MANAGEMENT

IMPLICATIONS

Abrams and Nowacki (2008) argued that Native 

Americans used fire widely to manipulate vegetation 

in the eastern United States. Delcourt and Delcourt 

(1986, 1998) noted that Native Americans of the 

Woodland Tradition appeared in the vicinity of our 

study area about 4,000 years ago, and they attribute 

fires during that period to these hunter-gatherers. 

Mississippian people appeared in this area about 1,000 

YBP, coinciding with the appearance of Zea maize

and a number of weedy herbs in the pollen record. 

The widespread use of fire by Mississippian Native 

Americans is well documented (Delcourt and others 

1998, Hatley 1993). 

In eastern Kentucky, Delcourt and others (1998) linked 

Native American use of fire to the dominance of oakhickory forests starting 3,000 yrs ago (also see Ison 

2000). Springer and others (2010) recent analysis of 

pollen and charcoal deposits in a West Virginia cave 

suggests an increase in fire in that location beginning 

4,000 YBP and lasting until the arrival of Europeans. 

Here, too, Native Americans were implicated. In the 

only additional soil charcoal study in the southern 

portion of the Eastern Deciduous Biome, Hart and 

others (2008) described a comparable range of fire 

occurrence (events spanning 6785 to 174 YBP) in a 

hardwood deciduous forest on the Cumberland Plateau 

of middle Tennessee (located 185 km from our study 

area).

Because of the uncertainties associated with 

radiometric and inbuilt errors, it was not possible 

to estimate fire return intervals for our study area. 

Nevertheless, the summed probability plot (Fig. 1c) 

is consistent with frequent, low severity fires during 

the past millennium. This time period coincides with 

the expansion of Mississippian people into this area. 

If our charcoal samples are representative of the fire 

events during the period 4,000-1,000 YBP, then we 

might speculate that fires during that period were less 

frequent and, therefore, more severe during that time 

interval. 
GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

After accounting for the prescribed fire, a simple 

histogram of charcoal ages suggests that fires may 

have become less frequent during the past 250 

years (Fig. 1b). This coincides with the decline in 

Native American populations in this region after the 

beginning of European exploration and settlement. 

Changes in fire frequency over the past millennium 

were undoubtedly influenced by changes in climate as 

well.

The actual composition of the forests that burned 

during the past four millennia remains unknown. 

However, this amount of fire suggests that pines were 

likely far more abundant in presettlement times than 

today. The nature of presettlement fires (e.g., their 

seasonality and severity) also remains unknown. 

But these data suggest that fire regimes changed 

considerably from Woodland to Mississippian to 

European Settlement times. 

These results eliminate any doubt about whether fire 

played a significant role in presettlement deciduous 

forest ecosystems; it most certainly did. Given its 

historical importance, we can also presume that many 

deciduous forest species are in various ways adapted 

to fire regimes of one kind or another. Although the 

specifics are far from clear, changes in fire regimes 

(fire frequency and severity) undoubtedly caused 

changes in the relative abundance of different tree 

species from one time period to another. As fires 

became more common during the past 4,000 years, 

they likely contributed to increased prevalence of 

pines and fire tolerant hardwoods such as oaks and 

hickories. The significant diminution in fire occurrence 

over the past two centuries has contributed to the 

increased prevalence of fire intolerant species such as 

red maple (Abrams 1992) and to the “mesophication” 

of eastern forests (Nowacki and Abrams 2008). 

These very general conclusions are directly relevant to 

restoration and fire management in eastern deciduous 

forests. First, the historic range of variation in fire 

regimes and ecosystem structures over the past several 

millennia appears to have been very large compared to 

the expected range of variation in these features over 

decadal time intervals. It is variation over these shorter 

time intervals that is most relevant to restoration 

and fire management today. Second, even though 

the specifics are vague, changes in fire regimes over 

time suggests that the choice of particular historical 

restoration targets, whether for forest composition or 

fire prescriptions, is arbitrary. Furthermore, even if we 

knew the specifics of the relationship between forest 

composition and fire regime change, restoration to a 

particular historical target may not be possible. Given 

ongoing climate change, land fragmentation, and 

abundant non-native species, restoration of a particular 

fire regime will not necessarily restore the community 

of species that were historically associated with it. 

This does not mean that detailed information on 

past fire regimes and their relationship to forest 

composition is not important. The end goal of fire 

restoration management is not fire itself, but the 

diversity, structure and key processes in eastern 

deciduous forest ecosystems. A clear understanding 

of the details of the historical relationship between 

fire regimes and these ecosystem features is critical to 

achieving that goal, and we have much yet to learn.

ACKNOWLEDGMENTS

We thank Dr. James Vose and Dr. Katherine Elliot for 

advice and assistance in locating our field site. We are 

also grateful to Dr. Jim Clark and Dr. Ben Poulter for 

helpful advice on analyses and data interpretation. Paul 

Heine provided assistance with laboratory analyses. 

We are especially appreciative of the thoughtful 

comments and criticisms we received from reviewers. 

Funding for this research was provided by the U.S. 

Forest Service, Southern Research Station.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102

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The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
12 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

ANTHROPOLOGY OF FIRE IN THE OZARK HIGHLAND REGION

David H. Jurney

Heritage Program Manager, Ozark-St. Francis National Forests, U.S. Forest Service, 

605 West Main, Russellville, AR 72801. To contact, call 479-964-7237 or email at djurney@fs.fed.us.

Abstract.--Native Americans are often considered to have exploited available natural 

resources rather than modifying their environments to maximize yields. As simpler 

societies evolved into more complex ones, there is a consensus that intensification of 

habitat modifications also increased. However, landscape scale archeological inventories 

now show relatively intensive modifications of specific landscapes through most of 

human history, including so-called simpler societies. Records of these modifications 

are difficult to obtain. Archeological site distributions can be used to understand human 

settlement and selection of particular ecosystems. Another method uses tree-ring dating 

(dendrochronology) on fire-scarred trees that recorded fire frequencies and fire return 

intervals at points on the landscape that frequently burned due to natural and cultural 

processes. General Land Office records (1815-1840) provide firm evidence for culturallyinduced changes in species distribution and historical landscape vegetation mosaics for 

the Ozark Highlands and Arkansas River valley.

Introduction

The Ozark Highlands have for a long time been 

considered a “marginal” region marked by cultural 

conservatism and lack of developed prehistoric 

agricultural and urban settlement (Sabo 1986). This 

concept has also been applied to humans practicing 

a hunting and/or gathering subsistence strategy, 

and so-called “primitive” societies are considered 

to lack sophisticated environmental management 

skills. Through the study of human use of fire and 

inter-regional comparisons of patterns of cultural 

development, the “marginal-primitive” view of Ozark 

prehistory and history is now challenged. The theme 

of this paper is that fire use by native people at various 

stages of cultural complexity indicates landscape scale 

manipulation of natural resources, implying greater 

environmental sophistication of hunter-gatherers than 

previously supposed.

Throughout the history of anthropology, cultural 

anthropologists and archeologists were bounded by 

theoretical assumptions that reflected the accepted 

norms of European and Euro-American societies; 

primarily those of colonial powers. Julian Steward, 

for example, popularized the notion of “cultural 

ecology” but viewed Indians, particularly hunters and 

gatherers, as living fossils representing an earlier, 

more “primitive” stage of human evolution (Steward 

1955). Cultural ecology became the dominant 

paradigm in North American prehistoric archaeology, 

where “all cultures are adaptations to their specific 

environments” (Cande 2008). A few voices in the 

wilderness, particularly Day (1953) and Stewart (1956, 

2002), challenged both ecological and anthropological 

theorists with field data on Native American use of 

fire, cultural and subsistence practices, and the broader 

environmental consequences resulting from burning 

particular habitats at certain times of the year. 

Miller (1972) employed the hypothesis that huntergatherers were totally dependent, and agriculturalists 

partially dependent, on the available natural vegetation 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 13

and fauna. Citing Steward (1955), Miller posited 

that “fire was the prime tool available” to native 

North Americans, and his work using General Land 

Office (GLO) records and historical accounts of 

northwestern Arkansas and the Ozarks has become 

a seminal environmental reference for archeologists 

working in the region. Miller hypothesized that several 

plant communities (and associated fauna), especially 

prairies (upland and lowland), barrens (open areas with 

frequent fire regime), and open oak woodlands, were 

maintained for at least the last 1500 years by Native 

Americans (see Curtis 1959, Miller 1972, Sears 1925), 

and substantiated this inference with the prehistoric 

floral and faunal materials recovered from bluff 

shelters in the Ozarks (Cande 2008). Similar patterns 

of human use of fire are known from the Cumberland 

Plateau (Delcourt and others 1998). Ecological 

communities such as open oak woodlands, barrens, 

and prairies were maintained by Native American 

burning, and possibly natural fires, and were rapidly 

replaced by full forest vegetation (Kay 2003) after 

Euro-American settlement by the relative suppression 

of fire and landscape fragmentation. In another study, 

Jurney and Stahle (2004) found that some Ozark 

Highland prairies found in the GLO records are 

located on soils that formed under hardwood forest, 

suggesting that these prairies may have been culturally 

induced. During the 19th century, dendrochronological 

(tree-ring dating) data from fire-scarred trees indicate 

burning was conducted in some forested areas (e.g., 

Cross Timbers of western Ozarks) to improve range 

(Clark and others 2007, Griffin 2002), while other 

areas (e.g., central Ozarks) received less burning 

(Guyette and others 2002, Guyette and Spetich 2003). 

In the 20th century, fire was removed from many areas 

of the Ozark ecosystem, particularly where national 

forests were established and fire was considered 

counterproductive for timber management (Bass 

1981).

The ecological role of fire and human influences over 

the structure and distribution of plants has and will 

continue to be controversial. Two extremes in this 

debate argue that: 1) fire is destructive and should not 

be (or never was) applied by humans to the landscape, 

and 2) fire is an essential management tool to restore 

forests and grasslands to more natural, ecologically 

healthy, or desired historical reference conditions. The 

use of long-term, longitudinal ecological studies has 

challenged the traditional “succession” paradigm of 

“let Mother Nature take her course”, or “study only 

the wilderness”, and the human role in vegetation 

changes through time is now a generally accepted fact 

(Anderson 2006, Denevan 1992, Mann 2005, Raup 

and Carlson 1941). The anthropological assumption 

that hunter-gatherers were “primitive,” ecologically 

inept, and bound to the resources available to them 

(Anderson 2006) is central to the hypothesis that the 

origins of agriculture constituted a “revolutionary 

change” in how humans related to their particular 

environments. This theoretical bias persists today 

in archaeology and is challenged by the evidence 

presented in this paper.

STUDY AREA

The study area falls primarily in the Ozark Plateau of 

north-central Arkansas, with outliers in the Mississippi 

Embayment and Gulf Coastal Plain, the Arkansas 

River Valley, and the northern uplift of the Ouachita 

Mountains (Magazine Mountain). The Arkansas 

Valley consists of Pennsylvanian-age clastic sediments 

arranged into broad synclines (troughs) with relatively 

narrow intervening anticlines (arches). The synclines 

are most conspicuous and are formed when the 

capping sandstones are breached, resulting in a more 

rapid erosion of underlying shale. The Ozark Plateau 

is made of generally level-bedded Paleozoic age strata 

divided into the Salem Plateau, the Springfield Plateau, 

and the Boston Mountains (USDA FS 2005). All these 

plateaus are deeply dissected by numerous streams. 

The St. Francis National Forest is located on Tertiary 

marginal marine and coastal plain continental deposits 

with a veneer of Quaternary terrace and alluvial 

deposits. Crowley’s Ridge, formed by aeolian loess, 

runs through the center of this forest adjacent to the 

floodplains of the St. Francis River and the Mississippi 

River.
14 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Land managers, archaeologists, and geoscientists 

need to develop sound baseline historical data on 

plant distributions and ecological processes over 

entire landscapes (Bragg 2002, 2004; Warren 1984; 

Warren and O’Brien 1984) as an aid to current forest, 

shrubland, and grassland ecosystem management 

and paleoenvironmental reconstruction. The National 

Hierarchical Framework of Ecological Units (NHFEU) 

is a standardized classification and mapping system for 

dividing the earth’s biota into progressively smaller 

areas of increasingly similar ecology, providing 

baseline management information for each unit. It 

is derived from patterns of climate, soils, air quality, 

hydrology, geology, landforms and topography, 

potential natural plant communities, and natural 

disturbances. The Ozark-St. Francis National Forests 

in Arkansas (OSFNF) have completed (USDA FS 

2005) an approximation of land type associations 

(LTAs) tiered to the NHFEU. This Forest has 

management units falling in the northern Ouachita 

Mountains (Magazine Mountain), the Ozark highlands 

and the Arkansas River valley rolling hills (Wedington 

Unit, Bayou, Buffalo, Pleasant Hill, Boston Mountain), 

and the Mississippi (St. Francis NF) alluvial valley 

(Fenneman 1938, Thornbury 1965). The LTAs 

generally trend east-to-west following the sloping 

trend of the underlying geology, with some orientation 

along streams that drain the interior Ozarks.

The maximum southern advance of glaciers (northern 

Missouri) occurred around 18,000 years before 

present (YBP, 1950 as datum). Pleistocene records 

from various paleoenvironmental contexts (pollen 

in adjacent areas, solution cavern speleothems, 

dendroclimatology) indicate the Ozark forests were 

composed of boreal species, predominantly spruce 

(Picea spp.). Summers were substantially cooler 

than present. Faunal species included the Columbia 

mammoth (Mammuthus columbi), American mastodon 

(Mammut americanum), ground sloth (Megalonyx 

jeffersonii), and horse (Equus spp.). Around 14,000 

YBP, more mixed boreal forest developed with spruce 

and jack pine (Pinus banksiana), and the addition 

of oak (Quercus spp.), hickory (Carya spp.), ash 

(Fraxinus spp.), and maple (Acer spp.) as minor 

components. This mosaic of boreal and deciduous 

ecosystems has no modern analogue in present 

North America (Denniston and others 2000), and 

large scale herbivory may also have contributed to 

the vegetation mosaics of this period (Collins 1992, 

Nelson 2005). A brief cooling retrenchment occurred 

between 12,900 and 11,500 YBP, referred to as the 

Younger Dryas (Dansgaard and others 1989), which 

abruptly terminated with warming up to 7 °C (12.6 

°F) in just a few years. Many large herbivores became 

extinct just prior to or following this event. Dry 

westerly winds increased, with eventual intrusion of 

prairie grasses into the Ozarks (Denniston and others 

2000). Around 9,500 YBP oak savannah was well 

established across the Ozarks. A rapid decrease in 

speleothem values ca. 9,500 YBP indicates an increase 

in deciduous vegetation (Denniston and others 2000), 

followed by a prairie dominated environment about 

7,500 YBP. Nelson (2005) attributes the spread of 

prairie ecosystems from the Great Plains to Ohio 

during this period to the combined effects of warming 

conditions, increased aridity, and Native American 

fire sets. This climatic episode was interrupted by 

increased deciduous forest ca. 4,500 and 3,000 YBP. 

Prairie returned between 3,000 and 1,500 YBP, 

with the establishment of current deciduous forest 

(Denniston and others 2000). The climate record 

shows that radical environmental and climatic shifts 

(Stahle and others 2000) have occurred in the Ozarks, 

with commensurate changes in fire ecology. Periods 

with expansion of grasslands were probably most 

pyrogenic, followed (in descending order of fire 

frequency) by pine forests, open oak woodlands, 

and closed deciduous forest. Humans were present 

throughout the last 18,000 years, with increased 

population spikes ca. 4,500 and 1,500 years ago 

(Sabo and Early 1990), domestication of wild plants 

and use of tropical cultigens ca. 4,200 YBP, and 

the introduction of maize agriculture ca. 750 YBP. 

These population spikes occurred during shifts from 

grassland to deciduous forest, and from forest to 

grasslands.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 15

The modern climate is characterized as temperate, with 

west-to-east moving atmospheric circulation of air 

masses originating from the eastern Pacific, western 

United States, the Gulf of Mexico, and Canada. 

During winter, extreme north-to-south temperature 

variations occur. During summer, daily variations are 

less significant from north-to-south. Rainfall averages 

114.3-139.7 cm (45-55 inches) per year, with March, 

May, and November the wettest and July, August, and 

January the driest (USDA FS 2005). Thunderstorms 

are greatest during the spring, summer, and fall, 

averaging 10-25 events during each season. Tropical 

cyclone and frontal passages are most severe in winter 

and spring. Tornados have been reported every month 

but are most frequent in April and May. Nine major 

droughts (reconstructed below average June-July 

rainfall) have occurred during the last 308 years (1703-

1704, 1727-1741, 1780-1789, 1831-1840, 1855-1866, 

1886-1887, 1923-1925, 1950-1957, and 1963-1965), 

generally lasting 2 to 3 years in duration (Blasing and 

others 1988). 

Increased wildfires of human origin and lightning 

ignitions are noted for these periods, with some 

corresponding to drought episodes (Clark and others 

2007, Jurney and others 2004). Florida and Texas 

experience more lightning strikes than any other areas 

of the United States (Orville 1992, Silver and Orville 

1994), yet Florida’s fire records indicate an average 

of 15 lightning-caused fires per million acres per 

year (437.56 lightning fires per year; 8.2 percent of 

total). Texas fire records indicate an average of one 

lightning fire per million acres per year (23.5 fires 

per year; 1 percent of total); and Florida has almost 

three times as much rainfall (Jurney and others 2004). 

Arkansas fire records indicate an average of 4.3

lightning fires per million acres per year (93.5 fires 

per year; 2.6 percent of total). Only during exceptional 

climatic episodes does lightning match the frequency 

of human-caused fires (Jurney and others 2004). In 

Arkansas from 1916-1990, the mean lightning-caused 

fire frequency was 2.78 lightning fires per year (range 

0-25.7 percent). In this 75-year period of record, 26 

years had greater than average numbers of lightningcaused fires, 15.4 percent of which were drought years 

(1956, 5.7 percent of total; 1954, 4 percent; 1964, 

3 percent; 1923, 2.8 percent) with less than average 

tree-ring growth. In the 49 years of less than average 

numbers of lightning-caused fires, 8.2 percent were 

drought years (1924, 2.7 percent of total; 1925, 2.7 

percent; 1965, 2.6 percent; 1957, 1.8 percent; 1952, 

1.7 percent; 1953, 1.7 percent; 1963, 1.6 percent; and 

1951, 1.1 percent). These data suggest that during 

drought years there is a greater chance for lightningcaused fires; however, during some drought years, 

human-caused fires also proportionately increased.

Another aspect of climatic cycles is the El NinoSouthern Oscillation (ENSO) which are short duration 

3-7 year events which intensify both droughts and wet 

periods. ENSO events are known in the Pleistocene 

(radiometrically dated to at least 10,770 YBP), and 

it is possible that they can trigger broader patterns 

of climate change (Dunbar 2006, Guyette and others 

2006). In the Ozarks, ENSO events are marked by the 

presence of 70 frost-damaged growth rings (spring 

wood) in oaks over the last 330 (AD 1650-1980) 

years that formed from false spring events (late spring 

severe frost damage captured in tree growth rings), 

correlating with the La Nina phase of ENSO (Stahle 

1990). In 2007, such a false spring hit Arkansas during 

a La Nina year and produced extensive damage to both 

white oak (subgenera Leucobalanus with an annual nut 

mast) and red oak (subgenera Erythrobalanus with a 

2-year nut mast) acorn yields, with lag effects lasting 

into the spring of 2008. Thus, periods of drought and 

false spring events that show the influence of ENSO 

have the potential to increase the effects of wildland 

fire ignitions (Clark and others 2007, Guyette and 

others 2006) and allow humans to further influence the 

spread of landscape scale fires. Also, climate changes 

and fluctuations influence the annual yields of nut mast 

and other natural resources, as well as predisposing the 

landscape to large scale fire ignition and fire spread.
16 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

PREHISTORIC AGROFORESTRY

Native agroforestry practices are increasingly 

recognized through archaeological research, use of 

aerial and satellite imagery, and paleoenvironmental 

reconstruction around the planet. Many Native 

American elders report that plants benefit from human 

use, and many may actually depend on humans using 

them to fully function in the ecosystem (Anderson 

2006). Denevan (1992) argues that the forest structure 

and landscapes of North and South America were 

greatly influenced by humans through the widespread 

use of fire to concentrate food resources. Forests of 

widely spaced trees with grass and herb understory 

were observed in New England, the Midwest, 

and southeastern North America upon European 

introduction but have vanished today (Black and 

others 2006, Denevan 1992). Data compiled from 

modern vegetation studies (Guldin and others 1999) 

compared to GLO spatial data (Foster and others 2004, 

Foti 2004) indicate that the Ozark Highlands forest 

of Arkansas is 2.3-2.8 times denser today than 180 

years ago. Davies (1994) suggests that periodic lowintensity fires, particularly between November and 

April, increased vegetation yield from 20-100 percent 

and increased large birds and mammals by 100-400 

percent. Humans used fire to concentrate foods on 

highly productive portions of the landscape (Williams 

1993) and may have used similar strategies to achieve 

a “primary forest efficiency,” a phrase coined by 

Caldwell (1958) and amplified in the works of Smith 

(1974, 1975, 1978) in the Mississippi Valley and in 

the Ozarks by Raab (1976) and Lockhart and others 

(1995). My discussion of Ozark Native American use 

of fire to modify their environment summarizes known 

information relating to archaeological finds of plants 

whose life histories suggest some form of human 

intervention in the ecosystem (Nowacki and Abrams 

2008), dendrochronology, and proxy records of 

vegetated landscapes. Many species that are rare today 

appear to be artifacts of such fire regimes, including 

the federally endangered red-cockaded woodpecker 

(Picoides borealis) and Indiana bat (Myotis sodalis).

Beginning with the prehistoric archaeological record 

in the Arkansas Ozarks, dry rockshelter deposits 

preserve perishable material culture and food remains 

and provide empirical evidence for anthropogenic 

landscapes. Figure 1 shows giant cane (Arundinaria

spp.) remains from the Penhook Rockshelter (3PP402) 

on the Middle Fork Illinois Bayou in the Lower Atoka 

Hills and Mountains LTA. This species is rare in the 

vicinity of this shelter today. Cane was a ubiquitous 

material found in dry shelter deposits that was used 

for food, basketry, tools, and other functions. It 

is dependent on fire to maintain habitat and stand 

viability. For the Late Prehistoric and Historic periods, 

the GLO surveys and some historical accounts provide 

data on landscape-scale vegetation patterns and 

disturbance regimes. General Land Office records 

indicate extensive stands of fire-dependent cane 

(Arundinaria spp.) were present in early 19th century 

Ozark valleys (Fig. 2) in the Lee Creek Rolling Hills, 

Lee Creek Atoka Hills, Atoka Mulberry Mountain 

Valleys, Arkansas Valley Hills, Lower Atoka Hills 

and Mountains, Bloyd Mountain Valleys, White River 

Rolling Hills, Wedington Boone Hills, and Mississippi 

Bottomlands LTAs. The floodplain landtypes within 

these LTAs require a 5-10 year fire return interval 

for health of cane stands (Brantley and Platt 2001, 

Frost and others 1986, Frost 1995, Gagnon 2006) and 

were probably influenced by, if not created by, late 

prehistoric burning practices.

Figure 1.—Giant cane (Arundinaria spp.) fragments from the 

Penhook Rockshelter (3PP402).
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 17

Figure 2.—General Land Office information related to vegetation and cultural and natural disturbances on the Lee Creek Unit 

of the Ozark-St. Francis National Forests.

Most evidence for prehistoric manipulation of their 

environments is derived from the excavation of 

perishable food and material culture remains from 

Ozark rockshelters, focused primarily in northwestern 

Arkansas. Most of the excavations were done in 

the 1930s and lack firm chronological and spatial 

controls. Since these sites have suffered over 100 

years of looting, few remain that can be scientifically 

investigated today. Therefore, the studies of Gayle 

Fritz provide the best chronological control for Native 

American agroforestry, domestication of native wild 

plants, and adoption of tropical maize-bean-squash 

agriculture. Of particular note is the domestication 

of two native plants: Iva annua (sumpweeed) which 

favors floodplains, and Phalaris caroliniana (May 

grass or canary grass) which favors sandy soils and 

canopy disturbances from floodplains to uplands. 

Fritz (1986a, 1986b, 1990, 1994, 1997) argues they 

were domesticated because they have larger seeds 

than modern varieties and were recovered from 

archaeological contexts outside their modern ranges. 

Unfortunately, the paleobotanical literature lists 

species by presence/absence with little quantitative 

information on species abundance.

The life histories of other flora and fauna species 

strongly associated with fire-adapted ecosystems 

(e.g., shortleaf pine [Pinus echinata], various white 

and red oaks, bison [Bison bison], and elk [Cervus 

elaphus]) and their distributions confirm that native 

fire use played a role in ecosystem structure and 

function. Table 1 is a list of 64 plants found in 

Ozark rockshelters (Gilmore 1931) and provides 

a rough assessment of the ratio of fire-adapted to 
18 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Table 1.—List of plant species recovered from Ozark rockshelters and identified by Gilmore in 1931. Theo 

Witsell (Arkansas Department of Natural Resources) provided updates to the scientific nomenclature. Fire 

code denotes species response to fire (1 = responds favorably; 0 = fire intolerant) as determined from the 

Fire Effects Information System database (USDA FS 2012). Note that many species respond favorably to 

environments cleared by fire. The last column lists any quantified information provided by Gilmore (1931).

Scientific Name Common Name Fire Code Quantitation Information

Pinus echinata shortleaf pine 1 one specimen

Pinus taeda loblolly pine 1 one specimen twisted cord

Juniperus virginiana red cedar 0 common in graves 

Typha latifolia cattail 1 abundant 

Tripsacum dactyloides gama grass 1 no data

Zea mays Indian Corn 1 abundant all sites

Andropogon furcatus big bluestem 1 many specimens (Andropogon gerardii)

Andropogon scoparius little bluestem 1 no data (Schizachyrium scoparium)

Sorghastrum avenaceum Indian grass 1 1 specimen (Sorghastrum nutans)

Phalaris caroliniana Carolina canary grass 1 many sheaves

Elymus arkansanus slender wild rye 1 no data (Elymus villosus)

Arundinaria macrosperma giant cane 1 no data (probably Arundinaria gigantean)

Arundinaria tecta switch cane 1 no data

Scirpus validus great bulrush 1 1 specimen (Schoenoplectus tabernaemontani)

Acornus calamus calamus sweet flag 0 abundant all sites

Allium sp. wild onion 1 no data

Yucca sp. Spanish bayonet 1 no data 

Populus deltoides cottonwood 0 many specimens

Salix nigra black willow 1 1 bundle 

Juglans nigra black walnut 1 no data

Carya illinoiensis pecan 0 no data

Carya cordiformis

Carya laciniosa shagbark hickory 0 many specimens

Carya alba mockernut hickory 1 no data

Corylus americana hazelnut 0 many specimens

Castanea pumila chinquapin 1 no data 

Quercus falcata/rubra red oak 1 no data

Quercus alba white oak 1 no data

Quercus marilandica blackjack oak 1 no data

Quercus imbricaria shingle oak 0 no data

Quercus macrocarpa bur oak 1 no data 

Ulmus fulva slippery elm 0 no data

Morus rubra red mulberry 0 no data

Maclura pomifera bois d’arc 0 1 specimen bark cord

Amaranthus spp. pigweed 1 many sheaves

Chenopodium sp. lambsquarters, goosefoot 1 many sheaves

Asimina triloba pawpaw 0 1 seed 

Platanus occidentalis sycamore 0 1 specimen

Prunus chicasa chickasaw plum 1 1 specimen (probably P. angustifolia) 

Gleditsia triacanthos honey locust 0 1 specimen

Lespedeza capitata rabbitfoot clover 1 no data

Phaseolus vulgaris garden bean 1 varieties all sites 

Rhus glabra smooth sumac 1 many empty panicles 

(Table 1 continued on next page)
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 19

non-fire-adapted plants exploited by Ozark Native 

Americans. Since full quantitative information was not 

available from the literature, each species was coded 

to indicate species with a favorable response to fire 

(coded as 1) and species that grow in non-pyrogenic 

ecosystems or that respond unfavorably to fire (coded 

as 0) based on the Fire Effects Information System 

(USDA FS 2012). Species that are favored by fire 

dominate (70 percent) over species that are from nonpyrogenic ecosystems or that do not respond favorably 

to fire (30 percent). Table 2 lists the plant remains 

found in the intestines of an elderly woman whose 

remains were exposed in the drip line of a rockshelter. 

All identified plant remains of this person’s last meal 

were fire-adapted (100 percent) species. Ants, fruit 

beetles, and mites were found in the unidentified 

fruity substances. The ingestion of charcoal and 

sumac (Rhus glabra) suggests that the woman may 

have been ill, since sumac was used for food as well 

as medicine to stop vomiting (Hamel and Chiltosky 

1975). Food residues from a ceramic vessel at the open 

air Copperhead Site (AD 819-1299), 3CW951 in the 

Atoka Hills and Valleys LTA (Cummings and Yost 

2009), indicate cooking of squash/pumpkin (Curcubita 

pepo), sunflower (Helianthus spp.), oak acorns, beans 

(Phaseolus sp.), and sumac berries (Rhus spp.). All of 

these species (100 percent) were fire-adapted. Table 3

lists the plant remains from three rockshelters on Lee 

Creek in western Arkansas identified by Fritz (1986a). 

Scientific Name Common Name Fire Code Quantitation Information

Sapindus drummondii soapberry 0 1 specimen 

Vitis spp. wild grape 0 abundant all sites 

Tilia americana basswood, linden 0 no data 

Dirca palustris leatherwood 0 no data 

Cornus florida dogwood 1 no data 

Diospyros virginiana persimmon 1 no data 

Fraxinus spp. ash 0 no data 

Apocynum cannabinum Indian hemp 1 many specimens

Onosmodium subsetosum Ozark false gromwell 1 no data (O. molle var. subsetosum)

Dasistoma sp. false foxglove 1 1 specimen (may be Aureolaria sp.), some 

Dasistoma spp. (moved to Aureolaria)

Catalpa speciosa catalpa 0 specimens

Viburnum sp. viburnum 1 1 seed

Cucurbita maxima winter squash 1 1 shell, 1 peduncle, several seeds

Cucurbita ovifera egg gourd 1 1 complete shell

Cucurbita pepo pumpkin/summer squash 1 1 complete shell

Iva xanthifolia marsh elder 1 quantities

Ambrosia trifida giant ragweed 1 considerable quantities, large seeds

Liatris squarrosa blazing star 1 no data

Liatris pycnostachya Kansas gayflower 1 no data

Helianthus annuus sunflower (two cultivated varieties 1 quantities

Cirsium altissium thistle 1 1 leaf

Rudbeckia sp. cone flower 1 1 seed head disc

Table 1 (continued).—List of plant species recovered from Ozark rockshelters and identified by Gilmore 

in 1931. Theo Witsell (Arkansas Department of Natural Resources) provided updates to the scientific 

nomenclature. Fire code denotes species response to fire (1 = responds favorably; 0 = fire intolerant) as 

determined from the Fire Effects Information System database (USDA FS 2012). Note that many species 

respond favorably to environments cleared by fire. The last column lists any quantified information 

provided by Gilmore (1931).
20 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Table 2.—Listing of materials recovered from the feces of an elderly prehistoric woman indicating 

consumption of fruits with pests, oak acorns, and sumac (from Wakefield and Dellinger 1936). At least half 

of the remains provide evidence of fire use or fire-adapted habitats. Quantitative data were not provided. 

Species that respond favorably to fire are denoted by 1, and species that are fire intolerant are denoted by 

0, however note that many species respond favorably to environments cleared by fire.

Scientific Name Type of Material Fire Code Quantity

Rhus glabra sumac 1 no data

Quercus velutina black oak 1 no data

Nitidulidae fruit beetles 2 specimens

Tyroglyphidae mite in decaying matter a number

Formicidae ant 1 specimen

- - - - - fruit substance

- - - - - charcoal 1 mixed throughout

fungus growth on materials

Table 3.—Plant list from three rockshelters in Lee Creek (Fritz 1986b). Quantitative data were not 

provided, but are inferred by site catalog numbers provided in Fritz 1986a. Species that respond favorably 

to fire are denoted by 1, and species that are fire intolerant are denoted by 0; however, note that many 

species respond favorably to environments cleared by fire.

Scientific Name Common Name Fire Code Quantitation Information

Zea mays Indian corn 1 37 specimens

Cucurbita maxima winter squash 1 38 specimens

Cucurbita ovifera egg gourd 1 12 specimens

Cucurbita pepo pumpkin/summer squash 1 lumped with winter squash

Laegenaria bottle gourd 1 12 specimens

Phaselous vulgaris garden bean 1 11 specimens

Phaselous polystachios wild bean 1 1 specimen

Strophostyles helvula wild bean 1 1 specimen

Helianthus sp. sunflower 1 16 specimens

Helianthus tuberosus “Jerusalem artichoke” 1 lumped with sunflower

Iva annua sumpweed\polygonum 1 4 achenes

Phalaris caroliniana maygrass 1 1 specimen

Hordeum pusillum little barley 1

Amaranthus sp. amaranth 1 1 specimen

Ambrosia trifida ragweed 1 1 specimen

Nuphar luteum spatterdock/water lily 0 1 specimen

Optunia sp. cactus 0 3 specimens

Citrullus lanatus watermelon 0 3 specimens

Juglans nigra walnut 0 11 specimens

Carya spp. hickory 1 8 specimens

Quercus spp. oak 1 19 specimens

Fagus grandifolia beech 0 1 specimen

Prunus spp. plum 1 10 specimens

Prunus virginiana chokecherry 1 lumped with plum

Diospyros virginiana persimmon 1 4 specimens

Platanus occidentalis sycamore 0 2 specimens

Ostrya virginiana ironwood (hophornbeam) 0 3 specimens

Acer sp. maple 0 1 specimen

(Table 3 continued on next page)
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 21

Here, species that are favored by fire comprise 76.2 

percent of the plants recovered while fire sensitive 

plants comprise 23.8 percent of the assemblage. 

Primary occupations date to the Late ArchaicWoodland periods (3000-1000 YBP) for these species. 

Table 4 lists nine plants identified by Fritz (1997) 

that were recovered from a cache (radiocarbon 

dated 1301-898 BC, Fritz 1986b) in the Marble 

Falls Rockshelter on Mill Creek in north-central 

Table 3 (continued).—Plant list from three rockshelters in Lee Creek (Fritz 1986b). Quantitative data were 

not provided, but are inferred by site catalog numbers provided in Fritz 1986a. Species that respond 

favorably to fire are denoted by 1, and species that are fire intolerant are denoted by 0; however, note that 

many species respond favorably to environments cleared by fire.

Scientific Name Common Name Fire Code Quantitation Information

Nyassa sylvatica sourgum 0 2 specimens

Compositae spp. (Asteraceae sp.) 1 1 specimen

Arundinaria sp. Cane 1 15 specimens

Juniperus sp. Juniper 0 9 specimens

Pinus spp. Pine 1 5 specimens

Vitis spp. Grape 1 4 specimens

Asimina triloba pawpaw 0 1 specimen

Vaccinium spp. Blueberry 1 1 specimen

Rubus spp. blackberry/bramble 1 2 specimens

Celtis occidentalis hackberry 1 8 specimens

Viburnum sp. Haw 1 4 specimens

Viburnum prunifolium black haw 1 lumped with viburnum

Crataegus spp. Hawthorn 1 1 specimen

Rhus spp. Sumac 1 1 specimen

Arkansas. Fritz interprets that four species of wild 

plants (Curcurbita pepo spp. ovifera, Chenopodium 

berlanderi spp. jonesianum, Iva annua var. 

macrocarpa, and Helianthus annus var. macrocarpus) 

were domesticated and, along with Ambrosia trifida, 

were harvested from a garden and stored to be planted 

or eaten the following spring. All of these species (100 

percent) are fire-adapted.

Table 4.—Listing of domesticated wild plants from seed cache at Marble Bluff (Fritz 1997). Species that 

respond favorably to fire are denoted by 1, and species that are fire intolerant are denoted by 0; however, 

note that many species respond favorably to environments cleared by fire.

Scientific Name Common Name Fire Code Quantity

Chenopodium berlandieri Lambsquarters, goosefoot 1

Ambrosia trifida giant ragweed (stored in bags) 1

Lamiaceae mint 1 capsules

Helianthus sunflower 1 58 seeds

Amaranthus amaranth 1 18 achenes

Polygonum knotweed 1

Curcubita pepo gourd/squash 1 8 seeds 

Iva annua sumpweed 1

Phalaris caroliniana canary grass 1 least common
22 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Other indicators suggesting Native American 

ecosystem modifications include the presence of large 

herbivores such as bison and elk in Arkansas (Collins 

1992, Nuttall 1821, Schroeder 1981). Bison and elk 

remains are known from rockshelter and open site 

deposits in the Ozark Highlands (Cleland 1965, Sabo 

and others 1990, Scott 1993, Trubowitz 1980). Six 

bison images painted by Native Americans are present 

in the dark zone of Gustafson Cave (3ST70) on a 

tributary of the White River on the eastern front of the 

Ozarks in the Sylamore Hills LTA. Three images have 

fletched arrows extending through the torso of the 

animal, matching ethnohistorical evidence (Swanton 

1942) of the use of bois d’arc (Maclura pomifera) for 

bows by the Caddo Indians that shot arrows through 

the animal. Schambach (2000, 2001b) argues that 

the Spiroans of the Arkansas Valley near Fort Smith 

were key participants in interregional exchange 

during the last 1500 years. Bow wood from the bois 

d’arc collected in northern Texas (Jurney 1994) was 

exchanged for seed corn (stored in specialized ceramic 

vessels) and turquoise (Jurney and Young 1995) from 

the Pueblos of the Southwest and bison meat and hides 

from the Plains nomads (Schambach 2001b). These 

goods were then routed into the Mississippi Valley, and 

thence to the southeastern Gulf region. Bois d’arc has 

been found under Caddoan mounds in Louisiana, at the 

Lyons Bluff site in Mississippi, and at Fort Toulouse 

in Alabama (Jurney 1994), all areas where it was not 

a major constituent of the original plant landscape 

after the terminal Pleistocene. The Gustafson Cave 

rock art also is the first written record (ca. AD 200-

900) of bison in Arkansas and suggests some form 

of human manipulation of this species. During the 

middle 1700s, Le Page Du Pratz (Du Pratz 1774) 

observed that the bottomland forest and canebrakes 

at the mouth of the St. Francis River (the St. Francis 

National Forest) were “always covered with herds of 

buffalo, notwithstanding they are hunted every winter 

in those parts” (see Key 2001). Among the Quapaw 

Indians and throughout Arkansas, these prairies were 

maintained by fire, “attracting grazers like bison” (Key 

2001). In northwest Arkansas, historical accounts of 

bison in 1829 estimated one head for every 3 acre 

density, with the last bison observed in 1832 (Miller 

1972). Patch burning of grasslands has shown that, 

given the choice, bison will only graze in burned areas 

with incipient revegetation (Kerby and others 2007), a 

behavioral response which was undoubtedly noted by 

Native Americans.

There was a heavy dependence on oak acorns found at 

all rockshelter sites (Harrington 1960) in the Ozarks 

and adjacent areas. The relative abundance of white 

oak and red oak (Jurney and Stahle 2004) mirrors 

that of the 1815-1840 reference conditions found in 

GLO surveys. Fritz (1986b) found that oak (Quercus

spp.) acorns were the most abundant plant remains 

from the Lee Creek Valley, a tributary of the Arkansas 

River in the Lee Creek Atoka Hills LTA. These 

remains were apparently associated with Caddoanaffiliated farmer-hunters and their Fourche Maline 

(Woodland, 350 BC-AD 950) predecessors (Gilliland 

and others 2009; Schambach 2001a; Trubowitz 1980, 

1983). In the Lee Creek area, Hilliard (1986) found 

dominance (67 percent) of red/black oak species 

(Quercus shumardii, Q. veluntina, and Q.rubra) in 

archeological sites, with high frequencies of white 

oak species (Q. alba, Q. stellata) growing in the 

same area. General Land Office records dating to the 

early 19th century indicate an opposite trend, with 

62 percent white oak group species and 38 percent 

red/black oak species (Foti and others 2007). Hilliard 

hypothesized the dominance of red/black oak species 

was due to human selection. Since red/black oaks 

germinate in spring and white oaks in the fall, white 

oaks are preferred by wildlife competitors, and are 

more susceptible to insect infestation. All oak acorns 

found in archaeological storage contexts had been 

scorched or parched to prevent insect infestation and 

germinated before the acorns were consumed. This 

same phenomenon could occur if Native Americans 

burned the woods during the fall, halting insect entry 

and allowing humans to more easily find acorns in 

forest litter; thereby out-competing wildlife such as 

turkey, deer, blue jay, squirrel, and passenger pigeon 

(Ellsworth and McComb 2003, James and Neal 1986) 

that feed on acorns. If humans did not collect acorns 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 23

soon after they fell, competing wildlife, insects, 

molds, and unfettered germination would greatly 

reduce the amounts available for human consumption. 

Such adaptive use of fire is known to be used by the 

Cherokee Indians who collected large quantities of 

chestnuts (Castanea spp.) in this manner (Fowler 

and Konopik 2007). Life history studies of oaks 

point to fire adaptations with oak stand development 

dependent on advanced regeneration coupled with 

sprout-generated cohorts (Guyette and Dey 2004, 

Guyette and others 2004). It is possible that Native 

American agroforestry practices were based on similar 

observations.

Sabo and others (2004) estimate that an average 

community of 20 during the Archaic (7550-600 BC) 

would require 5 acres of openings in forest canopy 

for camps per 4.7 square mile catchment across the 

Ozarks (see also Lockhart and others 1995). By using 

these data, approximately 7,960 people occupied over 

2,000 acres of camps on the Ozark National Forest 

(1.2 million acres). By the Woodland transition (600 

BC-AD 600), with the use of adopted horticulture of 

native plants, Sabo and others (2004) estimate that an 

average community of 250 would require 62.5 acres 

of garden space per 4.7 square mile catchment. Using 

these data, an Ozark NF-wide population of 99,734 

people farmed over 25,000 acres of gardens. With the 

development of sedentary agriculture ca. AD 600-

1500, Sabo and others (2004) estimate an average 

community of 400 would require 125 acres of garden 

space per 4.7 square mile catchment. Using these data, 

a population of 158,200 people farmed over 376,000 

acres of gardens (Fritz 1994) on the Ozark National 

Forest. However, these estimates do not include nut, 

animal, and plant food collecting across the landscape 

that may have included the broadcast use of fire. An 

estimated population of 2.26 people/square mile was 

present on the Ozark National Forest during the late 

prehistoric/protohistoric periods ca. AD 1500-1700 

(Sabo and others 2004). During the historic periods, 

land was purchased in up to 160 acre grants by 40 ac 

parcels at $1.25/acre (Rafferty 2001), and the nature of 

the rectangular land surveys (AD 1815-1840) greatly 

affected the size and shape of farmstead allotments. 

Rafferty (2001) presents population data that indicates 

by 1930, the interior highlands of the Ozark-St. 

Francis National Forests (OSNF) were settled by 

6-8 people/square mile, the lower Atoka Hills and 

Arkansas Valley by 18-45 people/square mi, and the 

St. Francis/Mississippi valley by 45-90 people/square 

mi. Using these data, in the uplands of the OSNF 

approximately 15,000 people were present, the Atoka 

Hills and Arkansas Valley had approximately 84,375 

people, and the smaller St. Francis National Forest had 

2812 people. Thus, during the early 20th century, from 

8-20 times more people were present on the Forests 

than during the late prehistoric/protohistoric periods at 

or near the time of European contact.

Human use of fire is now receiving attention 

through the reconstruction of fire regimes by using 

dendrochronology for the study of fire-scarred trees. 

Clark and others (2007) found that the mean fire 

return interval for all fires from AD 1772-2002 was 

2.0 years and 7.0 for moderate-scale (more than 25 

percent of sampled trees have that fire-scar year) fires 

in the Cross Timbers of Oklahoma. Low intensity 

fires probably were not recorded as fire scars on oak 

trees unless there was a pre-existing wound on the 

tree (Clark and others 2007). This fire return interval 

decreased following Euro-American settlement of the 

area, probably due to heavy grazing practices (Lane 

1939). Oak recruitment was also found to increase 

with shorter fire return intervals (Clark and others 

2007). In the lower Boston Mountains of the Ozarks, 

Guyette and Spetich (2003) found that between the 

years 1670-2000, the mean fire return interval ranged 

from 4.6 years (1680-1820), to 3.1 years (1821-1880), 

to over 80 years (1921-2000). This trend was opposite 

that of Clark and others (2007) until 1921 and may be 

due to sampling vagaries, such as temporal factors and 

number of long-lived trees, and landscape differences, 

such as topography, slope, aspect, and local climate 

variability. Fire scar records indicate that between 

1748-1881 (excluding those low intensity fires that 

may not have left tree-ring evidence), an area about 

the size of the Ozarks burned every 20 years under 
24 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

moderate to severe drought conditions (Guyette 

and others 2006, Spetich and He 2008), producing 

a mosaic of burned and non-burned areas due to 

topographic roughness, fuels variability, and localized 

conditions (Collins 1992, Frost 1995, Frost and others 

1986).

PREHISTORIC SITE DISTRIBUTIONS

Table 5 lists the Landtype Associations (Fig. 3) on the 

Ozark-St. Francis National Forests with the number 

of prehistoric and historic components in each. 

Examination of the topographic distribution (Fig. 4) 

of historic and prehistoric sites across all Landtype 

Associations on the Ozark-St. Francis National Forests 

reveals that relatively more prehistoric sites are found 

in the Floodplain, South Aspect Lower Slope, and 

South Aspect Middle Slope landtypes than historic 

sites. The south aspect is the most pyrogenic landtype 

in the Ozark Highlands. Relative frequencies are 

nearly identical in the North Aspect Upper Slope and 

North Aspect Lower Slope landtypes. Historic sites 

exceed prehistoric sites in the Ridge and Flat Upper 

Slope landtypes.

In addition to the frequency distribution discussed 

above, a component density value is calculated for 

each by dividing the various acreages surveyed within 

each LTA by the number of sites discovered. Five 

LTAs have the densest number of both prehistoric and 

historic sites; Boone Mountain Valleys, Lee Creek 

Limestone Valleys, White River Rolling Hills, Lee 

Creek Atoka Hills, and Mesic Limestone Mountain 

Valleys.

Table 5.—Landtype Associations (LTAs) and Prehistoric and Historic Archeological Site Component 

Density Values (CDV) on the Ozark-St. Francis National Forests, Arkansas.

 LTA LTA Name Acreage Pre CDV Hist CDV

0 Private 8695.57 414.1 44.4

1 Boone Mtn. Valleys 739.15 369.6 24.6

2 Mesic Limest. Mtn. Valleys 5934.4 197.8 131.9

3 Mesic Morrow Mtn. Uplands 50935.72 134.4 125.5

4 Mesic Atoka Mtn. Uplands 37909.24 972 170.8

5 Hale Mtn. Valleys 32208.34 1073.6 187.3

6 Bloyd Mtn. Valleys 84279.92 726.6 233.5

7 Atoka Mulberry Mtn. Valleys 55574.1 805.4 243.7

8 Lower Atoka Hills & Mtns. 85770 779.7 196.3

9 Arkansas Valley Hills 12628.76 451 157.9

10 Lee Creek Rolling Hills 4036.12 807.2 36.4

11 Lee Creek Atoka Hills 18555.78 343.6 51.1

12 Lee Creek Limest. Valleys 2641.99 188.7 41.9

13 Wedington Calc. Uplands 1590.72 113.6 56.8

14 Wedington Boone Hills 12663.6 107.3 58.9

15 Sylamore Boone Hills 21256.27 250.1 110.7

16 Sylamore Hills 10904.09 340.7 139.8

17 White R. Rolling Hills 19649.74 194.6 99.2

18 Magazine Rolling Valley Hills 42387.45 399.9 129.2

19 Magazine Valley Ridge 13612.08 1944.6 349

20 Magazine Valley Hills 41403.76 828.1 221.4

21 Magazine Mtn. Uplands 5969.06 663.2 170.5

22 Mississippi Bottomlands 10539.3 619.9 107.5

23 Crowley’s Ridge 10350.8 2587.7 145.8

24 Bear/Storm Ck. Lakes 761.69 0 152.3
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 25

Figure 3.—Ozark-St. Francis National Forests Land Type Associations.

Figure 4.—Percentages of sites among landtypes on the Ozark-St. Francis National Forests. Landtype codes are: US = upper 

slope, ToeSL = toe slope, LS = lower slope, MS = mid slope, Flplain = Floodplain, Nasp = north aspect, Sasp = south aspect. 

Method: 1 = shovel probing, 2 = walkover survey.

0

5

10

15

20

25

Uplands

FlatUS

ToeSL

Ridge

FlatMS

Flplain

NaspUS

SaspUS

SaspLS

NaspLS

NaspMS

SaspMS

1 1 1 1 1 1 2 2 2 2 2 2

Series1

Series2

Series3

Percentage

Prehistoric

Historic

Prehistoric

/ Historic

Method

Landtype
26 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

The five LTAs with the densest prehistoric sites are 

Wedington Boone Hills, Wedington Calcareous 

Uplands, Mesic Morrow Mountain Uplands, Lee 

Creek Limestone Valleys, and White River Rolling 

Hills. This greater density correlates with the local 

prevalence of naturally occurring chert (Burlington/

Keokuk/Cotter, Reeds Spring, and Pitkin) for 

manufacture of stone tools within or immediately 

adjacent to all of these LTAs. As noted earlier, the 

Wedington unit has extensive prairies dervied from 

the field notes and maps of the GLO surveys, with 

some prairies located on soils that developed under 

hardwood forest. Thus the LTAs with the highest 

density of sites are also the ones that have the most 

evidence of fire. The five least dense LTAs with 

prehistoric sites include Crowley’s Ridge, Magazine 

Valley Ridge, Hale Mountain Valleys, Mesic Atoka 

Mountain Uplands, and Magazine Valley Hills. These 

areas lack local stone suitable for tool manufacture 

and lack readily available or permanent water sources. 

These areas also have the least evidence of fires, 

derived from the GLO field notes and maps.

The five LTAs with densest historic sites are Boone 

Mountain Valleys, Lee Creek Rolling Hills, Lee 

Creek Limestone Valleys, Lee Creek Atoka Hills, and 

Wedington Calcareous Uplands. The greater density 

correlates with more open woodlands and prairies, as 

well as dependable water flow in local streams and 

spring recharge rates. The five LTAs with the least 

dense historic sites include Magazine Valley Ridge, 

Atoka Mulberry Mountain Valleys, Boyd Mountain 

Valleys, Magazine Valley Hills, and Lower Atoka 

Hills and Mountains. These are the least arable LTAs 

with steep slopes, cobble-laden stream heads, and 

remoteness from established transportation routes.

CONCLUSIONS

Fire is one of the oldest tools known to man and his 

relatives, dated in archeological contexts for Homo 

erectus to at least 780,000 years ago at Zhoukoudian 

Cave, ca. 48 km southwest of Beijing in China (Jia 

and Huang 1990). The contextual associations of 

man and fire at Zhoukoudian Cave are in dispute, 

with some insisting that lightning could have caused 

archaeological evidence for fire, therefore absolute 

proof of early man’s deliberate manipulation of fire is 

still in question (James 1989). 

The widespread use of nut (acorns, hickory, 

chinquapin/chestnut, walnut) resources in the eastern 

Woodlands in general, and the Ozark Highlands 

specifically, is evident in the archaeological records, 

written accounts, and land surveys. Mature oaks and 

hickories yield more mast than younger trees, and the 

seasonal use of fire to collect and preserve mast in 

quantities of chestnut suitable to feed large populations 

is known among the Cherokees of the southern 

Appalachians (Fowler and Konopik 2007). Based on 

the archeological evidence in rockshelters (Hilliard 

1986), it is also highly likely seasonal fire was used by 

the Ozark Native Americans to collect and preserve 

oak as well. Fire was used to open grasslands and alter 

cover to increase nutrient cycling and also created the 

edge environment where prey could be concentrated. 

Canebrakes require periodic burning to maintain 

equilibrium and prevent floodplain canopy closure 

(Brantley and Platt 2001) and are an excellent example 

of high-yield, fire-adapted grasslands that are suitable 

for tools, fiber, food, and ceremonial use. Due to lack 

of fire in modern floodplain forests, cane is rapidly 

facing extirpation. 

Although fire is a natural component of a disturbance 

regime in ecosystems of the Arkansas Ozarks, it 

appears that humans greatly extended the intensity 

and coverage of burns to collect and concentrate 

resources, beginning with hunter-gatherers and 

culminating with agriculturalists. This inference 

is based on the ethnohistorical evidence as well as 

direct archaeological evidence from dry rockshelter 

deposits, General Land Office field notes and maps, 

and dendrochronological evidence from fire-scarred 

trees for the Ozarks. It is now recognized that 

disequilibrium in ecological communities is more 

common than equilibrium (Pielou 1991). Healthy 

forests and ecosystems contain mosaics of stands at 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 27

different ages and compositions, reflecting the vagaries 

of disturbances (Nelson 2005, Oliver and Larson 

1996). Therefore, humans, and possibly ancestral 

humans, introduced disequilibrium into ecosystems 

with experiential knowledge designed to provide edge 

environments and maximize yields from hunting and 

gathering as well as incipient agroforestry. 

The Native Americans of the Ozarks were historically 

seen as marginal participants in broader cultural 

developments. However, archaeological investigations 

have now covered a greater part of the region, and 

the marginality theme is now in question. During 

the earliest human occupations from ca. 18,000-

6,000 YBP, population was low, but two important 

circumstances occurred that affected ecosystems: large 

herbivores became extinct, and prairies expanded from 

the Great Plains to the Ohio River. Several species of 

wild plants became domesticated ca. 4,200-3,000 YBP 

due to human manipulation, and intensive collection of 

other plants, including mast crops, indicate extensive 

agroforestry during this period.

The presence of Mesoamerican tropical plants such 

as maize (Sabo and Early 1990) and cotton (Horton 

2008) in the Ozarks, and the distribution of large 

population centers indicate that ca. AD 1200-1500, an 

agricultural revolution did occur in the study area. The 

people of the Ozarks participated actively in regional 

exchanges and were not the conservative isolationists 

described in popular myth. Wild plant data (pollen, 

archaeological excavations, fire-scarred trees, and 

General Land Office records) from the Ozarks and 

Cumberland Plateau indicate genetic manipulation of 

a suite of species prior to the adoption of full-scale 

agriculture (Gremillion 1997). Native Americans in 

southeastern North America as early as 4000 BC had 

developed sophisticated knowledge of plants’ life 

histories, and a form of agroforestry was developed to 

maximize the yield of oak (both regions) and chestnut 

(east of Mississippi River) for developing populations. 

In this paper, several types of proxy information are 

presented. However, three time capsules are noted 

where human consumption of fire-adapted species 

is clearly demonstrated. In one, the food items were 

taken from the intestines of a prehistoric woman. In 

another, food residues were identified from a single 

ceramic vessel. Finally, in the Marble Bluff seed 

cache, domesticated wild plants were clearly collected 

and stored for spring planting or consumption. In all 

three instances, all species are fire-adapted. 

As a result of more intensive and extensive 

archaeological investigations, and the recordation of 

traditional Native American ecological knowledge, it 

is now recognized that most biotic communities are in 

a constant state of change due to natural and humancaused disturbances. In successional communities, it 

is necessary to manage the habitat to achieve stability 

or a desired stage of development (Anderson 2006). 

Fire use was the principal tool of Native Americans 

to achieve landscape scale modification of plant and 

animal communities.

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34 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

HISTORY OF FIRE IN EASTERN OAK FORESTS 

AND IMPLICATIONS FOR RESTORATION

Justin L. Hart and Megan L. Buchanan

Assistant Professor (JLH), Department of Geography, University of Alabama, Box 870322, 

Tuscaloosa, AL 35487. Graduate Student (MLB). JLH is corresponding author: 

to contact, call 205-348-4190 or email hart013@bama.ua.edu.

Abstract.—Our understanding of long-term fire history in the eastern United States 

is derived from the interpretation of a variety of archives. While cultural records are 

available for some sites, biological archives are most frequently used to reconstruct longterm historical fire regimes. The three most commonly used biological archives in eastern 

oak forests include: the relative abundance of micro- and macroscopic charcoal found in 

lake and wetland sediment cores, charcoal macrofossils recovered from mineral soil, and 

dated fire scars on tree cross-sections. Quantitative data from these biological records 

are essential to fully elucidate the relationships between fire and oak forest dynamics. In 

addition to providing a basis for the development and refinement of ecological theory, 

these data have practical utility as they can be used in restoration planning to set desired 

future conditions and establish silvicultural treatments that maintain oak dominance or 

mimic historical disturbance regimes. Here we review the three biological archives most 

commonly used to reconstruct historical fire regimes in the Central Hardwood Forest 

Region, synthesize results of investigations that have relied upon these techniques, and 

discuss the implications of these findings for restoration efforts. At present, ca. 100 fire 

reconstructions have been developed from fire scarred trees and soil and sedimentary 

charcoal in the region. Results from the reviewed published studies reveal that fire 

histories are site specific. Therefore, managers focused on ecological restoration are best 

advised to construct a place-based history rather than rely solely on results from other 

studies to set restoration targets and monitor treatment success.

Introduction

Over the past several decades the role of fire in oak 

(Quercus) forests throughout the eastern United States 

has received increased attention driven largely by 

successional changes hypothesized to be caused by 

20th century human alteration of fire regimes (Abrams 

and Downs 1990, Cho and Boerner 1991, Goebel 

and Hix 1997, Lorimer 1993). In addition, concern 

that fuel loadings have exceeded the historic range 

of variability has generated interest in the history of 

fire in oak forests (Brose and others 2001, Graham 

and McCarthy 2006, Loucks and others 2008). 

Vast areas of the eastern United States landscape 

are characterized by oak forest cover (Braun 1950, 

Dyer 2006). Paleoecological investigations indicate 

that oak has dominated forest communities of the 

region throughout much of the Holocene. However, 

a widespread pattern of forest composition change 

is evident throughout eastern oak forests. Oak 

regeneration failure has been reported from oakdominated stands over a variety of site types. Coupled 

with this regeneration failure is an increase in the 

density and dominance of mesic species, particularly 

sugar maple (Acer saccharum Marsh.) and red maple 

(Acer rubrum L.) (Abrams 1998, Fei and Steiner 2009, 

Lorimer 1984).
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 35

The profusion of quantitative data reported from sites 

throughout the eastern United States has led many 

researchers to project a pervasive and inevitable 

transition from oak systems to those dominated by 

maple and other mesic taxa (Abrams and Nowacki 

2008, Nowacki and Abrams 2008). This change in 

species dominance will undoubtedly have major 

ramifications for biodiversity, wildlife population 

densities, timber production, and a host of ecosystem 

processes such as forest hydrology, nutrient cycling, 

and fuel loading (Alexander and Arthur 2010, McShea 

and others 2007, Nowacki and Abrams 2008). Active 

fire suppression that began in the early 20th century 

is the most often cited explanation for the oak 

replacement pattern. While variability exists at the 

species level, oaks are considered tolerant of fire and 

only moderately tolerant of shade. Adaptations to fire 

include thick bark, the ability to stump sprout, and 

resistance to rot after scarring (Abrams 1992, Smith 

and Sutherland 1999). In contrast, maple and other 

mesic taxa have morphological characteristics such as 

thin bark and shallow rooting that make them firesensitive. Therefore, it is hypothesized that historic 

surface fires maintained oak dominance by removing 

more mesophytic, shade-tolerant, and fire-sensitive 

competition from the understory (Abrams 1992, 

Lorimer 2001, Nowacki and Abrams 2008). While 

alternative hypotheses have been proposed to explain 

this successional shift (e.g., climate change, alterations 

in land use, facilitative processes, extirpation of 

American chestnut (Castanea dentata [Marsh.] 

Borkh.), and changes in wildlife population densities 

(Hart and others 2008b, Lorimer 1993, McEwan and 

others 2011), the oak-fire hypothesis is undoubtedly 

the dominant paradigm. As such, quantification of 

historical fire regimes of oak ecosystems is essential.

Our understanding of the history of fire in eastern oak 

systems is derived from the interpretation of a variety 

of archives. To reconstruct fire history, researchers 

have relied upon witness tree analyses, field notes from 

land surveyors, early explorer and European settler 

accounts, and other land-use records (Ruffner 2006, 

Russell 1983, Whitney 1994). While documentary 

or cultural archives such as these are available for 

some sites, reconstructions of long-term historical 

fire regimes are typically developed using biological 

archives. Biological records used to document past fire 

events include dendrochronology or fire scar analysis; 

charcoal analysis of lake sediments, wetlands, or peat 

bogs; black carbon analysis of marine sediments; 

pedanthracology or macroscopic charcoal analysis in 

mineral soil; molecular markers of combustion; fuel 

and soil magnetism; and sedimentology (Conedera 

and others 2009). The three most commonly used 

biological archives of fire history in eastern oak forests 

include: the relative abundance or influx of microand macroscopic charcoal found in lake and wetland 

sediment cores, charcoal macrofossils recovered from 

mineral soil, and dated fire scars on tree cross-sections. 

Quantitative data from these biological records are 

essential to fully elucidate the relationships between 

fire and oak forest dynamics. In addition to providing a 

basis for the development and refinement of ecological 

theory, these data have practical utility as they can 

be used in restoration planning to set desired future 

conditions and establish silvicultural treatments 

that maintain oak dominance or mimic historical 

disturbance regimes.

The goal of this paper is to review the three biological 

archives most commonly used to reconstruct historical 

fire regimes, synthesize results of investigations that 

have relied upon these techniques, and discuss the 

implications of these findings for restoration efforts. 

We limited our review to the Central Hardwood Forest 

Region (CHFR) because a formal eastern oak forest 

unit is not recognized, the CHFR is a well established 

spatial unit, and oak is the dominant genus of the 

region. Several CHFR boundaries are accepted and we 

chose those defined by Fralish and Franklin (2002) and 

Fralish (2003). 
36 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

BACKGROUND ON BIOLOGICAL FIRE 

RECONSTRUCTION TECHNIQUES

Sedimentary Charcoal Analysis

Charcoal is produced during fire events as organic 

material is partially combusted. This combustion 

results in black pyrogenic carbon ranging from soot 

and graphite particles to coarse charcoal fragments 

and charred wood (Conedera and others 2009, Ohlson 

and others 2009). Microscopic (ca. 10-200 μm length) 

and macroscopic (ca. >100-200 μm length) charcoal 

in sediment cores retrieved from lakes, wetlands, 

and peat bogs may be used to reconstruct historical 

fire characteristics (e.g., Delcourt and Delcourt 

1997, 1998; Delcourt and others 1998). In these 

paleoecological analyses, the relative abundance or 

influx of charcoal is used to assess fire frequency and/

or magnitude. The primary advantage of this biological 

archive is the depth of record, as it is possible to 

document variability in vegetation composition and 

fire spanning the Holocene (Clark and others 1996, 

Delcourt and others 1998). These records reveal 

periods, rather than dates, when fire was more or less 

common based on the relative position and abundance 

of the quantified charcoal in the varved (i.e., layered) 

sediment core. Consequently, temporal resolution is 

coarse relative to macroscopic soil charcoal or fire 

scar analyses. In fact, the temporal resolution of this 

biological archive exceeds the hypothesized return 

interval of fire in many oak forests. In addition, 

sedimentary charcoal records are not spatially explicit 

as lakes receive charcoal inputs from broad source 

areas (Clark 1988, Clark and Royall 1996). Calibration 

studies have demonstrated that macroscopic charcoal 

particles typically originate within a few hundred 

meters of deposition sites while microcharcoal may 

originate up to 100 km from the deposition site (Clark 

1989, 1990; Clark and others 1998; Patterson and 

others 1987). Thus, documented microcharcoal could 

in fact have originated in a non-oak dominated stand 

kilometers from the study site and even macrocharcoal 

could originate from fire in xeric, pine (Pinus)-

dominated stands that may not be representative of 

local forest composition. Furthermore, fires in oak 

forests are typically low intensity burns, and the 

quantity of charcoal produced from such events may 

be negligible and undetectable in the sedimentary 

record (Abrams and Seischab 1997). Therefore, 

sediment cores from lakes and wetlands may not 

provide accurate records of fire frequency and be 

biased towards the documentation of intense and/or 

high magnitude events. Nonetheless, these records are 

useful to understand long-term patterns of oak forest 

composition and the relative importance of fire in these 

systems.

Soil Charcoal Analysis

Macroscopic (generally considered >2 mm length) 

charcoal fragments recovered from soil cores 

provide historical fire data at fine spatial resolutions. 

Macroscopic charcoal particles are sufficiently large 

to resist entrainment by wind during or after fires and 

by overland flow on hillslopes. These macrofossils 

are considered primary charcoal and provide evidence 

of historical fire at the stand-scale (Gavin and others 

2003, Hart and others 2008a, Talon and others 2005) 

though even larger pieces of charcoal are likely formed 

in situ and indicate fire at the exact location of the 

soil core sample (Gavin and others 2003, Ohlson and 

Tryterud 2000). In addition to fine spatial resolution, 

macroscopic soil charcoal provides long-term fire 

records. Mean residence time of macroscopic charcoal 

varies by geographic location, but charcoal may 

be preserved in mineral soils of the eastern United 

States for up to ca. 10,000 years (Fesenmyer and 

Christensen 2010, Hart and others 2008a). Therefore, 

charcoal macrofossils may provide fire history records 

at the stand-scale throughout the Holocene. While 

the utility has not been fully explored in eastern oak 

systems, charcoal macrofossils can be identified to 

species or genera providing information on taxa that 

inhabited stands that were disturbed by fire. The 

major limitations to this biological archive include 

the inbuilt age error (Gavin 2001) associated with 

accelerator mass spectrometry (AMS) 14C dating of 

the charcoal macrofossils. This technique actually 

provides the date that carbon was assimilated by the 

plant rather than the time of the fire event. This dating 

analysis is also cost prohibitive, and many samples are 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 37

required to develop robust fire histories. Macroscopic 

soil charcoal analysis may indeed be the best method 

to reconstruct long-term fire histories in mesic oak 

stands. However, more methodological studies in the 

eastern United States are warranted (e.g., inbuilt age 

error estimates by species and site type, charcoal loss 

during subsequent fire, and charcoal transport by size 

and site condition).

Fire Scar Analysis

Forest fire histories are often reconstructed by 

assigning the calendar year and often the season of 

formation to fire scars found on tree cross-sections 

(Fritts and Swetnam 1989, Kipfmueller and Swetnam 

2001). Fire scar analysis provides the finest spatial 

and temporal resolution of the three biological 

archives most commonly used. As trees are sessile, 

the spatial resolution is known to the exact location 

of the sampled individual (Kipfmueller and Swetnam 

2001, Swetnam and others 1999). This allows for 

reconstruction of the spatial extent of past fires. Along 

with forest composition and age structure data, the 

magnitude of the historical disturbances can also be 

documented which provides information on the role 

of fire in forest community organization. Annual 

resolution allows researchers to analyze historic fires 

with regard to short-term forcing factors that may 

influence fire characteristics (e.g., contemporaneous 

and previous climate characteristics, land-use change). 

Furthermore, intra-annual resolution allows for the 

documentation of fire seasonality, shifts in which 

may provide information on ignition sources (Lafon 

2010). Though fire scar analysis provides annual 

or intra-annual resolution of fire data at fine spatial 

resolution, this line of evidence is inherently limited 

by the occurrence of old trees. Thus, the temporal 

depth of record is constrained by the age of the 

trees or remnant wood on the site. In the eastern 

United States, this archive provides records typically 

extending to a maximum of 400 years and often much 

less. Fire scar analyses are further constrained by 

tree selection and sample extraction. Long fire-free 

periods allow for wounds from prior fires to heal, 

and damaged trees may, therefore, not reveal external 

diagnostic characteristics of the records contained 

within. In addition, tree morphology (e.g., thick bark) 

may prevent scarring from low intensity surface 

fires (Guyette and others 2006a, McEwan and others 

2007a, Smith and Sutherland 1999), resulting in an 

underrepresentation of these fires in the reconstructed 

dataset. Similarly, stand-replacing fires are also likely 

to be underrepresented in historical fire datasets as 

these events remove wood thereby destroying direct 

dendroecological evidence of the disturbance (Guyette 

and others 2006a). Fire scar analysis typically requires 

that complete cross-sections or partial wedges are 

removed from trees (Arno and Sneck 1977, Baisan 

and Swetnam 1990). While logs and standing dead 

trees can be sampled, attaining an appropriate sample 

depth may require the partial destruction of living 

trees. Even if only partial wedges are collected, this 

sampling scheme is restricted on many sites because it 

affects the structural integrity of stems and causes the 

trees to be more susceptible to pathogens. 

GENERAL TRENDS

Sedimentary Charcoal Analysis

In the CHFR, fewer than 10 published studies 

have used charcoal analyzed from sediment cores 

to discern information on the long-term patterns 

of vegetation and fire (Table 1); however, several 

important sedimentary charcoal studies (e.g., Clark 

and others 1996, Clark and Royall 1996) have been 

conducted just outside the bounds of the CHFR. 

Collectively, studies from within the CHFR have 

Table 1.—Descriptive data for all sedimentary 

charcoal sites from published studies in the 

Central Hardwood Forest Region

Reference State Length of record

Delcourt and others 1998 KY 9,500 YBP

Delcourt and Delcourt 1997 NC 3,900 YBP

Cridlebaugh 1984 TN 900 YBP

Cridlebaugh 1984 TN 2,800 YBP

Haas 2008 TN 425 YBP

Haas 2008 TN 2,800 YBP

Kneller and Peteet 1999 VA 17,345 YBP

Kneller and Peteet 1993 VA 17,130 YBP

White 2007 WV 8,180 YBP
38 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

reported nine sedimentary charcoal records from six 

different sites (multiple studies were conducted at 

the same site). The sedimentary charcoal studies for 

the CHFR are clustered in the central and southern 

Appalachian Highlands (Fig. 1). The longest record 

from this archive extends over 17,000 years before 

present (YBP) and shows an increase in charcoal 

abundance coincident with the rise of the oak-hickory 

(Carya) forest type in the central Appalachians at the 

beginning of the Holocene (Kneller and Peteet 1999). 

This marks the beginning of the Holocene and rapid 

climate change and does not provide that increased fire 

frequency was a causal factor. 

No clear ubiquitous patterns were evident as the 

results from the studies revealed unique fire histories 

based on the abundance of charcoal in the sedimentary 

record. The results emphasize that fire history is 

region, landscape, and even site specific. Nonetheless, 

useful information on the relationships between 

humans, fire, and vegetation was gleaned from these 

studies. In all these paleoecological investigations, 

charcoal recovered from sediment cores exceeded the 

amounts the authors hypothesized would be produced 

by natural ignitions, leading them to speculate that 

most of the fires were from human ignitions. Working 

from this assumption, human use of fire generally 

Figure 1.—Map of the Central Hardwood Forest Region (Fralish 2003, Fralish and Franklin 2002) and the location of sites with 

fire reconstructions based on analysis of soil and sedimentary charcoal.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 39

increased during the Woodland cultural period (ca. 

3,000 YBP) (Delcourt and Delcourt 1998). The 

abundance of charcoal from a site in the Ridge and 

Valley of east Tennessee peaked at the transition from 

Woodland to Mississippian periods (ca. 1,000 YBP) 

and from Mississippian to historic periods (ca. 300 

YBP) (Delcourt and Delcourt 1998). Delcourt and 

Delcourt (1997) hypothesized that fires, at least of 

the southern Appalachian Highlands, were largely 

restricted to ridgetops and upper slopes and that lower 

slope positions supporting more mesic species were 

relatively protected from Native-set fires prior to 

European settlement. Additionally, they speculated 

that human-set fires in the southern Appalachians 

represented intermediate-scale disturbances that 

emphasized ecotones, increased gamma diversity, 

and increased the abundance of oak species on upper 

slope positions. Aboriginal fires would have likely 

facilitated and maintained oak dominance (and that 

of other disturbance dependent taxa as well) on 

ridgetops and upper slopes. Even at a local scale, these 

anthropogenic disturbances may have resulted in a 

patchwork of forest types that included fire-adapted 

and fire-tolerant species at various stages of succession 

(Delcourt and Delcourt 1997, Delcourt and others 

1998).

Soil Charcoal Analysis

To date, macroscopic charcoal recovered from soil 

samples has been used in three published studies to 

reconstruct fire history in the CHFR (Table 2). These 

three studies presented data from nine different sites 

located in the southern Appalachian Highlands (Fig. 

1). However, only Hart and others (2008a) work 

exclusively in oak dominated stands. Dated fire 

events (from AMS 14C analyses) were only reported 

in two of these studies (Fesenmyer and Christensen 

2010, Hart and others 2008a). Collectively, these 

two studies reported 87 AMS dates from charcoal 

macrofossils recovered from soil samples; however, 

only Fesenmyer and Christensen (2010) had sufficient 

dating to provide meaningful information on changes 

in fire frequency for their study site. Nonetheless, 

each of these studies made contributions to our 

understanding of historic fire regimes and the use of 

this method in the CHFR.

Welch (1999) established that macroscopic charcoal 

could be recovered from mineral soil in the temperate 

region of North America, that charcoal was abundant 

in pine and mixed pine-oak dominated stands of the 

southern Appalachians, and that charcoal accumulation 

did not vary by slope position indicating its presence 

is evidence of local fire. Hart and others (2008a) were 

the first to use macroscopic soil charcoal in mineral 

soils to elucidate fire history information in oak stands. 

Their study established that charcoal could be used 

to reconstruct stand-scale fire history in mesic oak 

systems, that charcoal macrofossils can be preserved 

in mineral soils of the region for millennia, and that 

macroscopic charcoal fragments could be identified 

to document taxa of the region that previously 

Table 2.—Descriptive data for all soil macrocharcoal sites from published studies in the Central Hardwood 

Forest Region

a

Only a single date was older than 4,000 YBP.

Reference State Length of record Number of radiocarbon dates

Welch 1999 GA na 0

Welch 1999 KY na 0

Welch 1999 KY na 0

Welch 1999 NC na 0

Fesenmyer and Christensen 2010 NC 10,570 YBPa 82

Welch 1999 TN na 0

Hart and others 2008a TN 6,735 YBP 5

Welch 1999 VA na 0

Welch 1999 VA na 0
40 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

inhabited sites that burned during previous fires. To 

date, Fesenmyer and Christensen (2010) published 

the most extensive macroscopic soil charcoal study 

in the CHFR. They provided that even protected 

microsites devoid of trees (e.g., near rock outcrops) 

still had sufficient mixing of soil to require AMS 

dating of charcoal (i.e., depth does not correspond 

to charcoal age), that differences in fire frequency 

could be detected with this archive between mesic and 

xeric sites, and that fire frequency increased ca. 4,000 

YBP (during the late Archaic period) and increased 

drastically ca. 1,000 YBP for their study site in the 

Blue Ridge physiographic province. In fact, only one 

charcoal date was older than 4,000 YBP. This drastic 

increase in fire frequency at 1,000 YBP was attributed 

to the rise of the Mississippian cultural tradition.

Fire Scar Analysis

We reviewed fire scar-based data from more than 70 

sites in the CHFR representing 35 different published 

studies (Fig 2, Table 3). Of all biologically derived 

fire histories in the region, over 80 percent have 

been developed using fire scarred trees. The longest 

tree ring based fire records begin in 1581 (located in 

Figure 2.—Map of the Central Hardwood Forest Region (Fralish 2003, Fralish and Franklin 2002) and the location of sites with 

fire reconstructions based on dated fire scars in tree cross-sections. White circles represent temporally delineated fire history 

records that pre-date European settlement. Black circles represent all other fire scar records.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 41

Missouri), but the mean initiation date for the total 

fire scar network is in the mid-1700s. Regional fire 

scar chronologies extend to the 17th century for 21 

sites and to the 18th century for 50 sites, cumulatively. 

Approximately 35 percent of the fire scar records in 

the CHFR begin post-800. Fire frequency statistics 

of some form (e.g., mean fire return intervals) are 

available for the overwhelming majority of sites.

Jenkins and others 1997 AR 1770-1993 6

Guyette and Spetich 2003 AR 1680-1820 5

1821-1880 3

1881-1920 5

Guyette and Spetich 2003 AR 1680-1820 16

1821-1880 3

1881-1920 2

Guyette and Spetich 2003 AR 1680-1820 13

1821-1880 2

1881-1920 1

Guyette and others 2006b AR 1810-1830 2†

1821-1880 2†

1881-1920 2†

Guyette and others 2006b AR 1810-1830 1†

1821-1880 2†

1881-1920 2†

Guyette and others 2006b AR 1810-1830 2†

1821-1880 4†

1881-1920 5†

Stambaugh and Guyette 2006 AR 1670-1820 8

1821-1880 2

1881-1920 3

Engbring and others 2008 AR 1820-1900 2

1901-1930 2

1931-2003 3

McClain and others 2010 IL 1776-1850 2

1851-1884 No fires

1885-1996 1

Guyette and others 2003a IN 1693-1801 No fires

1888-1929 2

Henderson and Long 1984 IN 1929-1981 5

Henderson and Long 1984 IN 1933-1981 2

Cole and Taylor 1995 IN 1900-1990 5

McEwan and others 2007b KY 1885-1954 9

McEwan and others 2007b KY 1893-1954 12

McEwan and others 2007b KY 1879-1900 2

Shumway and others 2001 MD 1616-1992 8†

Guyette and Cutter 1991 MO 1710-1810 4

1810-1989 6

Guyette and Cutter 1997 MO 1821-1940 5

Guyette and Cutter 1997 MO 1581-1700 10

1701-1820 3

1821-1940 4

Guyette and Cutter 1997 MO 1581-1700 8

1701-1820 4

1821-1940 4

Guyette and Cutter 1997 MO 1701-1820 9

1821-1940 3

Guyette and Cutter 1997 MO 1581-1700 6

1701-1820 5

1821-1940 5

Guyette and Cutter 1997 MO 1581-1700 30

1701-1820 7

1821-1940 2

Guyette and Cutter 1997 MO 1701-1820 9

1821-1940 2

Guyette and Cutter 1997 MO 1581-1700 30

1701-1820 13

1821-1940 4

Guyette and Cutter 1997 MO 1581-1700 21

1701-1820 13

Guyette and Cutter 1997 MO 1701-1820 11

1821-1940 2

Guyette and Cutter 1997 MO 1581-1700 >37

1701-1820 4

1821-1940 2

Guyette and Cutter 1997 MO 1581-1700 12

1701-1820 3

1821-1940 2

Guyette and Cutter 1997 MO 1701-1820 12

1821-1940 4

Guyette and Cutter 1997 MO 1701-1820 6

1821-1940 2

Guyette and Cutter 1997 MO 1581-1700 19

1701-1820 6

1821-1940 3

Guyette and Cutter 1997 MO 1701-1820 13

1821-1940 4

Guyette and Cutter 1997 MO 1701-1820 20

1821-1940 5

Guyette and Cutter 1997 MO 1581-1700 7

1701-1820 6

1821-1940 2

Guyette and Cutter 1997 MO 1701-1820 16

1821-1940 7

Guyette and Cutter 1997 MO 1701-1820 >45

1821-1940 4

Guyette and Cutter 1997 MO 1701-1820 >50

1821-1940 8

Guyette and Cutter 1997 MO 1701-1820 9

1821-1940 6

Period

Reference State of record MFI

Period

Reference State of record MFI

Table 3.—Descriptive data for fire scar based reconstruction sites from published studies in the Central 

Hardwood Forest Region. Only time periods with provided mean fire interval (MFI) values are reported. All 

MFI values are rounded to the nearest integer.

(Table 3 continued on next page) †

Weibull median or Weibull modal fire interval
42 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Guyette and Cutter 1997 MO 1701-1820 10

1821-1940 4

Guyette and others 2003b MO 1700-1780 10

1781-1820 3

1821-1850 2

1851-1890 2

1891-1940 3

Guyette and others 2003b MO 1700-1780 16

1781-1820 4

1821-1850 1

1851-1890 1

1891-1940 2

Guyette and others 2003b MO 1700-1780 13

1781-1820 3

1821-1850 3

1851-1890 2

1891-1940 6

Guyette and Dey 1997a MO 1700-1820 7

1821-1930 2

Guyette and Dey 1997b MO 1701-1820 6

1821-1900 3

Stambaugh and others 2005 MO 1634-1780 22

1780-1850 2

1851-1930 2

Cutter and Guyette 1994 MO 1740-1850 3

1850-1991 24

Guyette and Stambaugh 2004 MO 1604-1700 7

1701-1820 4

1821-1940 4

Dey and others 2004 MO 1705-1830 4

1831-1960 8

Table 3 (continued).—Descriptive data for fire scar based reconstruction sites from published studies in 

the Central Hardwood Forest Region. Only time periods with provided mean fire interval (MFI) values are 

reported. All MFI values are rounded to the nearest integer.

Period

Reference State of record MFI

Period

Reference State of record MFI

Buell and others 1954 NJ 1627-1950 >10

McCarthy and others 2001 OH 1624-1997 2

McEwan and others 2007b OH 1917-1936 2

McEwan and others 2007b OH 1875-1934 8

McEwan and others 2007b OH 1878-1931 7

McEwan and others 2007b OH 1900-1936 9

McEwan and others 2007b OH 1889-1931 6

McEwan and others 2007b OH 1889-1931 5

Hutchinson and others 2008 OH 1855-1935 9

Hutchinson and others 2008 OH 1858-1935 9

Hutchinson and others 2008 OH 1844-1935 15

Sutherland 1997 OH 1856-1995 5

Guyette and Stambaugh 2005 TN 1740-2002 5

Armbrister 2002 TN 1837-1934 7

Feathers 2010 TN 1685-2008 6

Feathers 2010 TN 1678-2008 3

Harmon 1982 TN 1856-1940 13

Laforest and others 2007 TN 1836-1929 7

Aldrich and others 2010 VA 1704-2003 5-17

DeWeese 2007 VA 1779-1934 3

DeWeese 2007 VA 1758-1934 4

DeWeese 2007 VA 1810-1934 2

DeWeese 2007 VA 1789-1934 3

Hoss and others 2008 VA 1794-2005 3

Sutherland 1993 VA 1765-1993 9-11

Wolf 2004 WI 1829-1839 4

1840-1871 20

1871-2004 5

Maxwell and Hicks 2010 WV 1898-2005 5

Schuler and McClain 2003 WV 1846-2002 18

Similar to the soil and sedimentary charcoal based 

fire networks, the fire scar based network is spatially 

clustered within certain subregions of the CHFR 

(Fig. 2). While both charcoal-derived records are 

concentrated in the Appalachian Highlands, over 

half of the published fire scar based histories have 

been focused in the Interior Highlands. Of all states 

that occupy a portion of the CHFR, Missouri has the 

highest number of site-specific fire scar reconstructions 

followed by Ohio (Table 3). A total of 12 states which 

comprise a portion of the CHFR have at least one fire 

scar based reconstruction. The Appalachian Plateaus 

(Mixed Mesophytic Forest Subdivision) and the Ridge 

and Valley (Appalachian Oak Forest Subdivison) 

provinces had the second and third highest occurrences 

of fire scar reconstructions. The longest fire scar 

records were reported from the Interior Highlands, 

with a mean record initiation date in the late-1600s 

(the oldest being 1581). The Appalachian Plateaus 

region supported the shortest fire records with a mean 

fire chronology start date in the mid-1800s (although 

the longest record for the province extended to 1616).

Of all site-specific fire scar datasets, slightly more 

than half report a temporally delineated fire frequency 

record based on human settlement and land-use 

patterns. Temporal delineation allows for comparisons 

between periods with different human population 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 43

densities and land-uses, factors which are major 

influences on historic fire regimes (Guyette and others 

2002, Guyette and Spetich 2003). Throughout the 

CHFR, indeed throughout the eastern United States, 

population density has widely fluctuated over the last 

four centuries. Within the depth of record afforded 

by fire scar analysis, changes in human population 

density and fire are commonly represented by four 

periods: 1) Native American depopulation (ca. mid1500s to 1800); 2) Native American repopulation 

(not a full recovery but population increase above the 

minimum) and early European settlement (ca. 1800 to 

1850); 3) widespread European settlement (ca. 1850 

to 1930); and 4) fire suppression (ca. 1930 to present). 

The timing of these events differed between regions 

(Denevan 1992, Millner and others 2001, Ramenofsky 

1987).

Decimation of Native American populations by the 

spread of alien contagious infectious diseases in 

the eastern United States began as early as the 16th 

century in the Mississippi River Valley but was not 

widespread throughout the region until the mid17th century (Denevan 1992, Millner and others 

2001, Ramenofsky 1987). The timing of widespread 

European settlement and intensive land use also 

differed significantly between regions. For example, 

areas of the mid-Atlantic, the Northeast, and portions 

of Kentucky and Ohio were settled by 1800 whereas 

broad-scale settlement of the eastern United States 

was not complete until 1850 (Gerlach 1970). In fact, 

widespread European settlement on the Cumberland 

Plateau, located only ca. 550 km from major eastern 

port cities, did not occur until well into the 1800s. In 

summary, the commonly used temporal designations 

are site-specific based on local population densities 

and culture. Of the common temporal delineations, 

only the onset of the fire suppression period has a 

largely static date (between 1920 and 1940).

Within the CHFR fire scar record, 25 sites provide 

explicit fire data for portions of the Native American 

depopulation period. The overwhelming majority 

of records that extend to this period are located in 

Missouri and Arkansas. This period is characterized by 

relatively long fire-free intervals. For example, during 

the Native American depopulation period, no fires 

were recorded for over a century in an Indiana barren 

(Guyette and others 2003a), and the mean fire return 

interval (MFI) was more than 37 years in a Missouri 

hardwood savanna (Guyette and Cutter 1997). The 

vast majority of the temporally delineated records that 

extend to this period display longer fire return intervals 

as compared to the subsequent period of repopulation 

and early European settlement. This pattern has been 

explained by low human population density and thus 

fewer ignitions. However, this pattern was not evident 

in two Appalachian Highland fire reconstructions. 

Shumway and others (2001) sampled on side slopes of 

Savage Mountain in western Maryland and obtained a 

fire scar record extending to 1616. The authors did not 

find differences in fire importance between the preEuropean and post-European settlement periods. They 

mention direct evidence of Native American activity 

downslope from the sample sites. During the period of 

aboriginal depopulation, Native American settlements 

were sparsely scattered throughout the eastern United 

States (Millner and others 2001). It is therefore 

possible that the sample site was located near a Native 

American settlement location that was not completely 

eradicated by the infectious diseases that decimated a 

majority of Native American populations in the region. 

Aldrich and others (2010) reconstructed fire history at 

Mill Mountain, a xeric ridgetop site in the Ridge and 

Valley of Virginia. Similar to Shumway and others 

(2001), the fire regime did not differ significantly 

between the pre-European and post-European 

settlement periods. However, throughout the extent of 

the record (beginning ca. 1700), European influence 

was documented in the area (e.g., hunting, trading, 

and raiding parties), and the site was then settled 

in the mid-1700s. Therefore, these pre-European 

settlement fires may have been either anthropogenic 

ignitions or natural ignitions from terrain-induced 

thunderstorms during dry conditions (Aldrich and 

others 2010), a distinction that is indiscernible in the 

fire scar record alone. Though this study is beneficial 

for understanding ridgetop pine-oak communities in 

the Central Appalachians, the findings may not be 

representative of the broader eastern oak forest region.
44 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

The Native American repopulation and early European 

settlement period is short (e.g., some studies classify 

this period as lasting 20 years), variable, and not used 

in all fire reconstructions. Aboriginal populations 

rebounded from the decimation at different speeds 

(Denevan 1992, Ramenofsky 1987). Similarly, early 

European settlement was variable in extent and 

intensity. Generally, fire during this period was more 

frequent than the preceding depopulation period but 

less frequent than the subsequent period of widespread 

European settlement. The fire return intervals during 

this transitional period were variable and typically 

ranged from a low of 1 to a high of 12 years between 

fire events. Two studies in the Central Lowlands 

documented anomalous fire histories during the early 

European settlement period. McClain and others 

(2010) and Wolf (2004) documented fire-free periods 

at the onset of early European settlement. This pattern 

was attributed to a purposeful avoidance of fire by 

European settlers as they feared destruction of crops, 

fences, buildings, and other property (McClain and 

others 2010).

During widespread European settlement, the spatial 

extent and intensity of human impacts on forest 

communities increased throughout the eastern United 

States (Cronon 1983, Motzkin and others 1999, 

Whitney 1994). This period was typified by frequent 

fires, more frequent than those during the preceding 

periods. Indeed, many studies documented fire 

return intervals as short as 1 to 3 years. In contrast 

to many presettlement fires, fires during this period 

were typically smaller in extent because of fuel 

fragmentation and fire breaks (Guyette and others 

2002). However, Shumway and others (2001) found 

that presettlement fires were smaller in relative extent 

but greater in relative intensity than postsettlement 

fires. This period of frequent fire ended in the early 

20th century with the onset of active fire suppression.

Regional patterns of fire occurrence are difficult to 

discern because many records are not temporally 

delineated, include depopulation and fire suppression 

periods, and fire histories are site specific. However, 

some general spatial trends are evident. As compared 

to eastern portions of the CHFR, fire return intervals 

were generally shorter in the western portions of 

the region. Many studies conducted in the western 

portions documented fire return intervals of less 

than 3 years with some annual fires. In contrast, the 

mean fire return interval in eastern portions was ca. 7 

years with some longer fire free intervals. Again, we 

stress that fire histories are site specific and that, with 

the distribution of fire scar studies, this comparison 

is largely between the Interior Highlands and the 

Appalachian Highlands.

SYNTHESIS OF FIRE HISTORY

Elucidation of broadscale historical fire regime 

characteristics in the CHFR was difficult because 

each of the reviewed biological archives provided 

information with different spatial and temporal 

resolutions. Nonetheless, some general patterns could 

be gleaned from these records. Based on charcoal data, 

fire frequency in the CHFR increased during cultural 

transition periods (i.e., from Archaic to Woodland 

and from Woodland to Mississippian). These results 

could be interpreted that fire return intervals were 

shorter during these transition periods, that fire was 

more widespread, or both. Regardless, the increase 

in fire (as evidenced by an increased in charcoal) 

during these periods may have resulted in long-lasting 

legacies in some oak ecosystems. The fire scar record 

provided more detailed fire history information, albeit 

over a shorter period of history. In general, fire-free 

intervals were longest during the Native American 

depopulation period. Fire was more common during 

the Native American repopulation and early European 

settlement period, but did not drastically increase 

until the period of widespread European settlement. 

Many studies during the widespread European 

settlement period revealed MFIs of 1 to 3 years. These 

fires were typically smaller in extent than those of 

prior periods because of fire breaks caused by forest 

fragmentation. This trend illustrated the influence 

of human population density and land use, which 

differed by culture, on fire regimes. Certainly there 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 45

were exceptions to these general trends, and notably 

some of the outliers were clustered spatially in distinct 

physiographic provinces. We suggest fire historians 

continue to analyze temporally delineated fire history 

characteristics. The dates of cultural milestones (e.g., 

European settlement) differ across the CHFR, and sitespecific temporal delineations allow for comparison of 

historical periods across a multitude of sites and thus, 

allow for a clearer interpretation of broadscale trends. 

Without question, additional fire histories developed 

from each of these archives are needed to understand 

past fire regimes and the influence of those events 

on oak ecosystems, especially in regions where fire 

reconstructions are sparse or on site types where fire 

history is poorly understood (e.g., mesic and submesic 

sites).

RESTORATION IMPLICATIONS

Ecological restoration is the act of returning an 

ecosystem to a prior state (Egan and Howell 2001). 

The practice of restoration implies that the site has 

been degraded and that the previous condition is more 

desirable based on management goals (Swetnam 

and others 1999). Fire has been incorporated into a 

variety of restoration plans (Pyke and others 2010) as 

prescribed fires can be used in structure- or processbased restoration activities (Parsons and others 1986, 

Swetnam and others 1999, Vale 1987). In the former, 

fire is used as a silvicultural tool much like thinning or 

herbicide application to shape species composition and 

stand structure to that of the target reference conditions 

(Brose and others 2001). In the latter, prescribed fire is 

used to mimic historical disturbance from an identified 

time period (e.g., aboriginal burning) (Brose and 

others 2001). Certainly, prescribed fire is being used 

by forest managers for purposes other than ecological 

restoration. However, if fire is to be used in ecological 

restoration to achieve management goals, certain 

procedures should be regarded. First, a reference 

model should be developed by identifying a discrete 

time period that represents the desired conditions for 

the site (Landres and others 1999). Second, managers 

should implement a multi-proxy reconstruction of 

site history using cultural and biological archives. 

During this process, the historic range of variability 

(HRV), which is the range of conditions within which 

ecosystems are in dynamic equilibirum, should 

be quantified as it provides the restoration targets 

(Egan and Howell 2001, Swetnam and others 1999). 

The HRV refers to both pattern and process and 

incorporates many variables including composition 

and structure measures and information regarding 

disturbance type, frequency, extent, and magnitude. 

Third, a silvicultural prescription should be developed 

to restore the site to the target conditions (i.e., within 

the HRV). Fire can be implemented as either a 

structure- or process-based treatment. Finally, criteria 

should be developed to monitor restoration success 

(Egan and Howell 2001). While reference models can 

be developed using ecological theory or environmental 

reconstructions, results from the published studies 

reviewed in this manuscript reveal that fire histories 

are site specific. Therefore, managers focused on 

ecological restoration are best advised to construct a 

place-based history and not rely on results from other 

studies alone to set restoration targets and monitor 

treatment success.

ACKNOWLEDGMENTS

We thank R. Pine, S. Rhine, J. Richards, and C. 

Turberville for assistance with locating published fire 

histories. We also thank the many contributors to the 

fire history network in the Central Hardwood Forest 

Region, and we apologize for missing works.

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The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
52 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

FIRE AND VEGETATION DYNAMICS IN THE CROSS TIMBERS FORESTS 

OF SOUTH-CENTRAL NORTH AMERICA

Steve W. Hallgren, Ryan D. DeSantis, and Jesse A. Burton

Associate Professor (SWH), Department of Natural Resource Ecology and Management, 

Oklahoma State University, 008C Ag Hall, Stillwater, OK 74078; Postdoctoral Research Associate 

(RDD); Fire Ecologist (JAB). SWH is corresponding author: to contact, call 405-744-6805 

or email at steve.hallgren@okstate.edu.

Abstract.—The vegetation of the Cross Timbers forests was maintained for thousands 

of years by fire; the historic fire return interval was likely 1 to 10 years. Fire suppression 

over the past century led to a doubling of stand basal area, increased diversity of tree 

species, reduced dominance of oak, and increased mesic species intolerant of fire. 

Dendrochronological studies suggested tree mortality from severe droughts opened stands 

and accelerated recruitment of eastern redcedar (Juniperus virginiana L.) where fire was 

suppressed. Without reintroduction of fire, Cross Timbers forests will become denser and 

more diverse with a less diverse understory of herbaceous species, and in many locations, 

eastern redcedar may become dominant. Research showed prescribed burning every 

4 years was sufficient to control understory hardwoods and benefit herbaceous plant 

cover and diversity which increased with fire up to a burn interval of 2 years. Because 

low intensity surface fires characteristic of the region usually do not remove established 

trees, mechanical or chemical methods may be necessary to restore open forests and 

savannas. Further research is warranted to determine how restoring Cross Timbers forests 

and savannas to more open conditions will affect ecosystem services including carbon 

storage, water supply, biological diversity, and wildlife resources.

Introduction

The ecotone between the eastern deciduous forest 

and southern Great Plains is a patchwork of forest, 

savanna, and prairie. This vegetation type, known as 

the Cross Timbers (Fig. 1), is believed to have once 

covered nearly 8 million ha from southern Kansas to 

north-central Texas (Küchler 1964, Therrell and Stahle 

1998). The forests of the Cross Timbers may contain 

some of the least disturbed primary forest in the 

eastern United States (Therrell and Stahle 1998). Large 

tracts of what appear to be old-growth forests are still 

found throughout the region where they have remained 

relatively undisturbed due to their location on poor 

shallow soils with rocky outcrops and steep slopes. 

These areas were rarely logged due to the timber 

having low commercial value, and they were rarely 

cultivated for crops due to the poor soil. Many of these 

forests contain 200 to 400 year-old post oaks (Quercus 

stellata Wangehn.) and 500 year-old eastern redcedar 

(Juniperus virginiana L.).

The Cross Timbers provides ecosystem services to 

a regional population of over 7 million persons, and 

this number is expected to grow to over 17 million by 

2040 (Texas Forest Service 2008). The capacity of the 

ecosystem to provide services is threatened by many 

factors including changes in land use, urbanization, 

pollution, overgrazing, global climate change, invasive 

species, and changes in the fire regime. A study of 

143 Cross Timbers stands found that over the past 

50 years, approximately 50 percent of the forest 

area was lost, mostly to agriculture (Stallings 2008). 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 53

Figure 1.—Geographic extent of the Cross Timbers.
54 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Encroachment by eastern redcedar due mainly to fire 

suppression has become one of the major threats to 

sustainable management in the region (Drake and Todd 

2002). When eastern redcedar invades grasslands, 

it reduces plant species richness (Briggs and others 

2002, Gehring and Bragg 1992, Linneman and Palmer 

2006) and forage production for livestock and wildlife 

(Briggs and others 2002) and creates more dangerous 

fuel conditions for wildfire (Drake and Todd 2002). 

It seems likely eastern redcedar encroachment in 

the forest would have similar results, but research 

to confirm this assumption has not been done. There 

is strong interest in maintaining and restoring Cross 

Timbers forests to pre-Euro-American settlement 

(EAS) conditions, and prescribed fire is considered 

to be an important tool to achieve this objective. 

Unfortunately, there is relatively little research to 

provide guidance for prescribed burning of forests.

This paper presents the current knowledge of the role 

of fire in shaping the forest vegetation of the Cross 

Timbers. It describes an anthropogenic landscape 

where thousands of years of human fire created a 

vegetation type that is changing rapidly to more dense 

mesophytic forests due to fire suppression. This new 

trajectory cannot be altered without the reintroduction 

of fire and substantial mechanical reduction of woody 

vegetation. The success of Cross Timbers vegetation 

restoration will be measured by a return to and 

maintenance of the savanna, woodland, and open 

upland oak forests last observed at the beginning 

of Euro-American settlement. 

PHYSICAL SETTING

Low elevation and low relief characterize the Cross 

Timbers Region. Elevation ranges from a low of 

approximately 150 m along the Red River to a high 

of 430 m in the Arbuckle Mountains and 755 m in 

the Wichita Mountains (Johnson 2006b). The rock 

outcrops are mainly horizontal or slightly dipping 

sandstones and shales of the Pennsylvanian, Permian, 

Cretaceous, and Tertiary age. Ridges are formed by 

the more resistant sandstones. Because most of the 

surface rock is not very resistant to erosion, much of 

the area is low rolling hills and broad flat valleys, and 

the maximum relief rarely exceeds 180 m (Johnson 

2006a).

The mean annual temperature decreases from 18 °C 

in the south to 13 °C in the north, and the mean 

annual rainfall increases from 600 mm in the west to 

1010 mm in the east. Precipitation is well distributed 

throughout the year with a maximum in May. Wide 

swings in precipitation can result in severe droughts. 

The most remarkable recent droughts for the region 

occurred in the 1930s and 1950s. The summers are hot 

and the temperature can exceed 40 °C, and winters are 

generally mild, but when cold arctic air intrudes, the 

temperatures drop to -25 °C (Arndt 2011). 

Vegetation

The vegetation has undergone many changes during 

the Holocene. Pollen studies at a site near the eastcentral part of the Cross Timbers in Oklahoma 

suggested that as the climate changed following the 

last retreat of the glaciers, the initial vegetation was 

grassland that began to give way to oaks about 9000 

years before present (YBP) (Bryant and Holloway 

1985). For thousands of years the vegetation appeared 

to be oak savanna, and during mid postglacial times 

about 5000 YBP, the increase in oak dominance led 

to the development of oak woodlands. Pines arrived 

about 2100 YBP and an oak-hickory-pine forest finally 

developed approximately 1200 YBP, but pine never 

developed dominance and is restricted to isolated 

pockets and the eastern edge of the Cross Timbers 

forests. Charcoal was present indicating fire was an 

important disturbance force since at least 5000 YBP 

(Albert 1981).

Forest canopy vegetation is dominated by post oak 

and blackjack oak (Quercus marilandica Muenchh.) 

and subdominant species include black hickory 

(Carya texana Buckl.) and black oak (Q. velutina

Lam.) (Ewing and others 1984, Rice and Penfound 

1959). The overstory trees are small in stature; the 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 55

top of the canopy is usually between 12 and 14 m 

(Fig. 2). Closed stands can attain a basal area of 23 to 

27 m2

/ha with 1400 to 1800 trees/ha and an average 

stand diameter at breast height (d.b.h.) of 14 to 17 cm 

(Karki 2007). The understory shrubs include poison 

ivy (Toxicodendron radicans [L.] Kuntze), rough-leaf 

dogwood (Cornus drummondii Meyer), redbud (Cercis 

canadensis L.), and coralberry (Symphoricarpus 

orbiculatus Moench) (Ewing and others 1984). 

Common herbaceous plants in the forest understory 

and prairies include bluestems (Schizachyrium 

scoparium [Michx.] Nash and Andropogon spp. L.), 

Indiangrass (Sorghastrum nutans [L.] Nash), and 

rosette grasses (Dichanthelium spp. [Hitchc. & Chase] 

Gould) (Ewing and others 1984, Tyrl and others 2002). 

The Cross Timbers ecotonal position contributes to its 

high taxonomic diversity. A study of the The Nature 

Conservancy’s Tallgrass Prairie Preserve found 763

species in 411 genera and 109 families (Palmer 2007). 

Over 1100 plant species were found at the Lyndon B. 

Johnson (LBJ) National Grasslands in north-central 

Texas (O’Kennon, pers. comm., Botanical Research 

Institute of Texas, 2009).

The dominant forces shaping the vegetation of the 

ecotone include soils, climate, and fire. The savannah 

and forest vegetation occur mostly on the coarse 

textured soils derived from sandstones or granites 

(Dwyer and Santelmann 1964, Rice and Penfound 

1959). Grasslands occur predominantly on fine 

textured soil derived from shale and limestone. 

That means the climate is not a true grassland or 

Figure 2.—Typical Oklahoma Cross Timbers forest in dormant season.
56 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

forest climate, because either vegetation type can be 

supported depending on the soil texture and its effects 

on water relations (Rice and Penfound 1959). The 

region-wide gradient of decreasing moisture from east 

to west is strongly manifested in the vegetation that 

decreases in stature and richness from east to west 

as the forests give way to savannas, and eventually 

to grasslands. Fire is a major force in shaping the 

vegetation mosaic. 

FIRE

The potential vegetation of the region as mapped and 

defined by Küchler (1964) was assumed to support 

understory fires with a return interval of 0 to 10 

years (Brown 2000). It is commonly held that fire 

suppression has effectively ended wildland fire as 

a force in shaping the ecosystems. However, recent 

evidence suggested fire suppression may not have 

been effective everywhere. Fire scar analysis found the 

mean fire interval (MFI) in some locations decreased 

after Euro-American Settlement (Allen and Palmer 

2011, Clark and others 2007, DeSantis and others 

2010b) or changed very little (Stambaugh and others 

2009). This may indicate fire suppression has been 

spatially highly variable. It was shown for similar 

forest vegetation in Missouri that MFI declined soon 

after EAS because settlers learned to use fire for many 

of the same purposes as the Native Americans. MFI 

did not increase until there was a substantial increase 

in human population in the 20th century that brought 

an end to fire use and resulted in strong support for fire 

suppression to protect property (Guyette and others 

2002). Perhaps variability in human population density 

and land use across the Cross Timbers landscape 

has resulted in a patchwork of vegetation with very 

different MFIs.

Based on fire scar analysis of the dominant oaks that 

extends back to the early 18th century (Table 1), it 

seems likely most of the fires were human caused 

and occurred during the dormant season. From 80 to 

97 percent of the fires were classified as occurring 

during the dormant season because the scars were 

located at the boundary between annual rings. A 

recent study determined the dormant season for 

cambial activity in post oak and blackjack oak was 

from mid-August to late March (Thapa, pers. comm., 

Oklahoma State University, 2010). This means scars 

during that period were caused by dormant season 

fires. Historical records of 418 dated fires in the Great 

Plains over the period 1535 to 1890 mentioned only 

one lightning fire. Lightning is abundant in the region, 

but most of it occurs with heavy rainfall which is not 

advantageous for igniting wildland fires. The most 

common reasons for Native Americans to set fires 

were for communication and warfare. In contrast, most 

fires started by settlers were accidental (Moore 1972). 

Approximately 60 percent of the fires occurred during 

the dormant season, mid-August to late March, and 

40 percent were recorded during the growing season 

for the entire Great Plains and for the Cross Timbers 

Region. Another study of records of 590 fires in the 

Great Plains found 50 percent of the fires occurred 

in September and October, the dormant season 

(Gaskill 1906). These reports support the conclusion 

that although a substantial number of fires occurred 

during the growing season, slightly more than half of 

Table 1.—Mean fire interval (MFI) and prevalence of dormant season fires for selected sites pre- and postEAS (Euro-American settlement)

MFI (years) Dormant season

Location1 Pre-EAS Post-EAS2 (percent) Reference

TGPP 3.4 1.3* 77 Allen and Palmer 2011

OWMA 4.0 2.0* 95 DeSantis and others 2010b

KAFP 4.9 2.1* -- Clark and others 2005

WMWR 4.4 5.2 97 Stambaugh and others 2009

1 TGPP = Tallgrass Prairie Preserve; OWMA = Okmulgee Wildlife Management Area; KAFP = Keystone Ancient Forest Preserve; and WMWR 

= Wichita Mountains Wildlife Refuge. 

2

 * = Pre- and post-EAS MFI different at P=0.05.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 57

fires occurred in the dormant season. There is some 

evidence that fires burn more frequently (Stambaugh 

and others 2009) or to a greater extent (Clark and 

others 2007) during periods of severe drought. But the 

link between fire frequency and extent and weather 

has not been established. Most often correlation 

analyses with drought indices show no relation to fire 

occurrence (Allen and Palmer 2011, Clark and others 

2005, DeSantis and others 2010b, Stambaugh and 

others 2009).

STAND DEVELOPMENT

In addition to fire there are numerous natural 

disturbance forces acting on these forests including 

tornados, straight-line wind, drought, hail, and ice that 

kill or damage large branches, single trees, and small 

groups of trees (Clark 2003). Large-scale catastrophic 

disturbances are not common. Tornados, one of the 

few forces to create large disturbances, are rare (return 

interval ~2000 years [NOAA 2011]) relative to the 

lifespan of the major tree species (300 to 500 years 

[Therrell and Stahle 1998]). The fires typical of the 

region are low intensity, rarely kill individual trees 

>5 cm d.b.h. (Burton and others 2010), and are not 

stand replacing events. Although the canopy trees are 

considered to be relatively intolerant of shade, there is 

evidence of continuous replacement of canopy trees by 

growth of understory saplings into the canopy without 

gaps (Clark and others 2005, Karki 2007). There are 

also small gaps that facilitate growth of saplings into 

the canopy (Karki 2007). Research suggested gapphase regeneration was the major type of canopy 

replacement in these xeric oak forests, as most trees 

had rapid growth from the pith indicating they started 

in a gap (Clark 2003).

Recent research found no evidence for change in 

overstory composition in Cross Timbers forests 

where gap-phase regeneration was occurring with 

frequent burning (Karki 2007). Although blackjack 

oak contributed a higher percentage of the gap makers 

than its proportion of the canopy, it and all the other 

species had replacement probabilities sufficient to 

maintain their relative abundance in the canopy. In 

contrast, there was strong evidence for major changes 

in forest composition and density where fire had been 

suppressed. Remeasurement in the 2000s of plots first 

measured in the 1950s (Fig. 3) found basal area had 

doubled, oak dominance had declined, mesophytic 

and fire-intolerant species including eastern redcedar 

had increased, and tree species richness had increased 

(DeSantis and others 2010a). Dendrochronological 

studies showed a large increase in eastern redcedar 

recruitment beginning in the 1960s and declining oak 

recruitment in the 1970s (Fig. 4). There was strong 

evidence the combination of oak mortality from severe 

Figure 3.—Map of Cross Timbers with research sites. Black 

dots show locations of 30 forest stands measured by Rice 

and Penfound (1959) in the 1950s and again by DeSantis 

and others (2010a) in 2008 and 2009. Blue triangle = 

Tallgrass Prairie Preserve (Allen and Palmer 2011, Karki 

2007); green triangle = Okmulgee Wildlife Management Area 

(Burton and others 2010, Burton and others 2011, DeSantis 

and Hallgren 2011, DeSantis and others 2010b, Karki 2007); 

red triangle = Keystone Ancient Forest Preserve (Clark and 

others 2005, Karki 2007); and purple triangle = Wichita 

Mountains National Wildlife Refuge (Stambaugh and others 

2009). Adapted from Therrell and Stahle (1998).
58 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

droughts, mostly in the 1950s, and fire suppression 

were responsible for the changes (DeSantis and 

others 2011). The mortality of mainly blackjack oak 

from the 1950s drought (Rice and Penfound 1959) 

opened the stands for recruitment of new cohorts of 

forest tree regeneration. Fire suppression removed the 

control on eastern redcedar encroachment and ended 

the stimulation of oak sprouting. Eastern redcedar 

had always been a minor component in riparian 

zones and on ridges where fire burned infrequently. 

It is disseminated widely and effectively by birds 

(Holthuijzen and Sharik 1984, Holthuijzen and others 

1986) and cannot tolerate fire when small (Engle 

and Stritzke 1995). It appeared suppression of fire 

may have contributed to eastern redcedar becoming 

widespread and may lead to its dominance in some 

forests.

Regeneration of the dominant oaks, post oak and 

blackjack oak, is highly adapted to fire. Although 

successful reproduction by seedlings is very rare 

(Backoulou 1998, Clark and Hallgren 2003, DeSantis 

and Hallgren 2011), both species sprout prolifically. A 

burn frequency of 1 in 10 years was found to produce 

the highest number of sprouts, up to 22,000 stems/

Figure 4.—Recruitment year for Juniperus virginiana, 

Quercus marilandica, and Quercus stellata, and instrumental 

Palmer Drought Severity Index (PDSI) in Cross Timbers 

forests of Oklahoma. Data represent sums of number of 

stems for three Oklahoma regions and average of regional 

PDSI (from DeSantis and others 2011).

ha of both species combined. Mortality thinned the 

sprouts over time since the last burn. Apparently these 

oak species are capable of accumulating reproduction 

over time even without fire, as stands not burned for 

over 20 years were found to have sprout densities as 

high as 11,000 stems/ha. Although the average age of 

sprouts in nonburned stands was only 5.5 years and the 

height was only 40 cm, some of the sprouts were 20 

years old (DeSantis and Hallgren 2011). 

Regeneration in these post oak-blackjack oak forests 

can be characterized as auto-accumulating (Clark and 

Hallgren 2003, Johnson 1993). There can be four or 

more cohorts of reproduction that accumulate over 

at least 20 years. Most sprouts are from stumps and 

seedlings (d.b.h. <5 cm), and both species produce a 

substantial number of root sprouts (attachment to root 

>25 cm from proximal end). Post oak can produce 

30 percent root sprouts, and blackjack oak around 

20 percent (Clark and Hallgren 2003, DeSantis and 

Hallgren 2011). A recent study found high density 

sprouting 6 years after a fire where none of the 

reproduction dated before the fire, and many of the 

root systems of young plants were much older, up 

to 67 years. The height growth of both species is 

relatively slow due to low moisture and light in these 

closed xeric stands, attaining 6 to 10 cm per year over 

the first 6 years (Clark and Hallgren 2003, DeSantis 

and Hallgren 2011). This slow growth means the 

sprouts may not become large enough to resist even 

the low intensity burns until after many years.

Post oak and blackjack oak dominance of these forests 

is well documented. A study of Oklahoma’s forests 

in the 1950s found them to be the most important 

species on a statewide basis by every ecological 

measure including presence, constance, frequency, 

density, and basal area (Rice and Penfound 1959). 

Species of secondary importance were black oak 

and black hickory in the eastern Cross Timbers. A 

remeasurement in the 2000s of 30 of the 208 original 

stands measured in the 1950s found post oak was 

still the most important canopy tree across the state, 

but blackjack oak had decreased in importance, and 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 59

the second most important species had changed to 

eastern redcedar in the west and central regions and 

black hickory in the east. The species shift was even 

greater in the saplings which reflect composition of 

the future canopy. The relative density of post oak 

and blackjack oak saplings dropped by nearly twothirds across the Cross Timbers. The replacement 

species included eastern redcedar in the west and black 

hickory and winged elm (Ulmus alata Michx.) in the 

east (DeSantis and others 2010a).

PRESCRIBED FIRE

Taken together the vegetation type and climate suggest 

the Cross Timbers forests supported frequent low 

intensity fires pre-EAS. The fine fuels in the grasslands 

were easier to ignite than the oak leaf litter, so fires 

likely started there and burned into forests. When 

Native Americans were managing the landscape, 

fires occurred year-round. At present, there is very 

little information about fire effects on vegetation to 

help make decisions about prescribed fire. The most 

common type of prescribed fire is a low intensity 

dormant season burn (Fig. 5) (Weir 2011).

Prescribed fire both kills oak sprouts and stimulates 

sprouting. Although Cross Timbers forests produce 

abundant oak sprouts even without fire, infrequent 

prescribed burning (one fire per decade [FPD]) was 

found to increase the density of sprouts. Sprouts 

are susceptible to high mortality from burning, and 

because they are slow growing, it takes many years 

to become resistant to fires (DeSantis and Hallgren 

2011). When oak sprouts grow above 1.4 m after 10 

to 15 years, they begin to show resistance to burning, 

and trees >5 cm d.b.h. easily survive the low intensity 

dormant season fires commonly prescribed for Cross 

Timbers forests. In contrast, understory non-oak 

saplings and shrubs (>1.4 m tall and <5 cm d.b.h.) 

were strongly reduced by prescribed burning two or 

more times per decade, dropping from nearly 1,300 to 

200 stems/ha (Fig. 6). Woody plant species richness 

was greatest when there were no burns in 20 years 

and dropped by 50 percent when fire frequency was 

increased to 5 FPD (12 vs. 6 species per treatment). 

Eventually, the small diameter non-oak saplings in 

the unburned stands may recruit into the larger size 

classes and change the overstory composition (Fig. 7). 

It appears that prescribed burning at two or more FPD 

may be effective in maintaining oak dominance in 

these stands (Burton and others 2010).

Figure 5.—Low-intensity dormant season prescribed fire 

typical for Cross Timbers forests. Prescribed fire was set 

when relative humidity ranged from 30 to 50 percent, 

temperature was <27 °C, and winds were <25 kph. The 

forest was burned every 4 years.

Figure 6.—Effect of fire frequency on sapling density of oak 

(Quercus spp.) and non-oak tree and shrub species (Burton 

and others 2010).
60 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Figure 7.—Effect of fire frequency (fires per decade, 

FPD) and years since last fire (YSLF) on tree diameter 

distributions in terms of stems per ha by 4-cm diameter 

classes. Prescribed burning treatments were applied for 20 

years (Burton and others 2010).

Despite the low light and strong competition for 

moisture and nutrients under the closed canopy of 

Cross Timbers forests, the herbaceous layer can be 

very responsive to prescribed burning (Fig. 8). This 

contrasts with the common belief that the understory 

herbaceous layer in oak forests will not respond to 

fire under a closed canopy (Franklin and others 2003, 

Harrington and Kathol 2009, Hutchinson and others 

2005). In Cross Timbers forests with canopy closure 

of 88 to 96 percent, the understory <1.4 m tall was 

dominated by woody reproduction followed by forbs, 

C3

 graminoids, C4 grasses, and legumes (Burton and 

others 2011). The cover of woody reproduction did 

not change with fire frequency, most likely due to its 

propensity to replace reproduction killed by fire with 

more sprouts. Forb cover increased threefold and C3

graminoid cover increased twofold over the range of 

0 to 5 FPD. Both plant functional groups increased 

in richness over the same range of fire frequencies. 

Fire frequency did not affect the cover or richness 

of C4

 grasses likely due to the low light intensity 

under the full canopy. Biomass of combined C4

 and 

C3

 graminoids increased nearly fourfold from 0 to 5 

FPD. The direct reduction in litter by burning may 

contribute to the increased herbaceous cover at high 

fire frequencies (Hiers and others 2007). In addition, 

the frequent fires reduced the density of non-oak 

shrubs and saplings thereby indirectly reducing litter 

production and reducing competition (Burton and 

others 2010).

RESTORATION OF CROSS TIMBERS 

VEGETATION

Research conducted nearly 40 years ago presented 

a likely scenario of changes in forest and savanna 

vegetation resulting from fire suppression in the 

Cross Timbers (Johnson and Risser 1975). The forest 

appeared to have been a savanna that had filled in 

with trees over 80 to 90 years to become a forest. 

Comparison of the size class distribution of trees in 

the forest with a contemporary savanna showed nearly 

identical numbers of trees in the large size classes 

and a much larger number of small trees in the forest. 

It appeared the small post oaks had recruited in the 

period 1910 to 1940 and the blackjack oaks in the 

period 1890 to 1920. As a consequence of recruitment 

of these two oak species, the basal area of the forest 

was double that of the savanna. These results were 

interpreted to show that when fire use ended and 

fire suppression began after EAS, oak encroachment 

changed the savanna to a forest. 

The savanna can be kept open by fire because the high 

production of herbaceous fine fuels creates conditions 

for fires hot enough to reduce and kill woody plants 

(Johnson and Risser 1975). Once the savanna becomes 

a forest, the fuel type changes to tree leaf litter that 

produces a less intense fire, and the closed canopy 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 61

Figure 8.—Typical forests on the Okmulgee Wildlife Management Area, Oklahoma where prescribed burns have been 

conducted for over 20 years at the rate of 0, 1, 2.5, and 5 fires per decade (FPD).

prevents production of large quantities of fine fuels. 

As a consequence, fire intensity in the forest is too low 

to kill established trees, and fire alone cannot restore 

closed forest to open savanna. A likely force to thin 

forests to savanna density is severe drought, and the 

last century had two very severe droughts in the 1930s 

and 1950s; however, neither of these disrupted the 

conversion of savanna to forest. The severe drought 

of the 1950s, which was acknowledged to have killed 

many oaks (Rice and Penfound 1959), appeared 

to open the forest to encroachment by non-oak 

mesophytic and fire sensitive species because there 

was no fire to control their establishment and stimulate 

the oak sprouts (DeSantis and others 2011). The 

mortality suffered in the 1950s drought was more than 

replaced over the next 50 years, and today these stands 

have twice the basal area they had then. The general 

belief is that without fire use in the Cross Timbers, 

woody encroachment will convert the grasslands to 

savannas, savannas to forests, and forests to denser and 

more diverse mesophytic forests.

Restoration of Cross Timbers vegetation to pre-EAS 

conditions will require treatments to reverse the 

encroachment of woody plants and increase grasslands 

and savannas and more open forests. Research has 

shown as few as two FPD can control the composition 

and structure of woody vegetation. When fire 

frequency is increased to five FPD, herbaceous plant 

diversity and grass biomass will strongly increase 
62 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

even under a closed canopy (Burton and others 2010, 

Burton and others 2011). Although fire can maintain 

the open grassland, savanna, and woodland, it rarely 

kills established trees (Briggs and others 2005, Burton 

and others 2010, Engle and others 2006). Opening the 

forests and savannas will require treatments to first 

reduce tree density, and second to maintain the open 

condition long-term. Both mechanical removal plus 

frequent fire (Masters and others 1993) and chemical 

thinning plus frequent fire (Scifers and others 1981, 

Stritzke and others 1991) have been successful at 

reducing overstory tree density and stimulating 

herbaceous biomass production. Although the dormant 

season is the most common time for prescribed 

burning in the region (Weir 2011), research has 

shown growing season burning may be more effective 

in controlling woody plants which may be more 

susceptible to damage when actively growing (Engle 

and others 1996, Waldrop and others 1992).

The pre-EAS Cross Timbers region was an 

anthropogenic landscape with more grasslands, 

savannas, and open forests than found today. Restoring 

the current vegetation to that condition will require 

treatments to remove woody vegetation and prescribed 

fire to prevent its return. Successful restoration will 

result in an oak dominated forest with only a minor 

component of eastern redcedar and mesophytic tree 

species. The woody vegetation will be less diverse, 

and herbaceous vegetation will be more diverse and 

abundant. Further research is warranted to increase 

the understanding of the most effective tools for Cross 

Timbers forest restoration and to gain the confidence 

of land managers in their use. The knowledge of 

mechanical and chemical control of woody plants 

needs to be increased. The current understanding of 

effects of prescribed burning is based almost entirely 

on research with low intensity dormant season fire in 

rangelands. The effects of growing season prescribed 

burning are poorly understood, and managers are 

reticent to employ it. Research on growing season 

prescribed burning has the potential to greatly increase 

the capability to restore Cross Timbers vegetation 

because its use will expand the window for prescribed 

burning and contribute to better control of woody 

plants (Weir 2011).

The woody encroachment of Cross Timbers plant 

communities over the past 100 years has changed more 

than the vegetation. Carbon storage, hydrologic cycles, 

biogeochemical cycles, and wildlife populations have 

also changed. Restoring the current landscape to 

pre-EAS vegetation may reverse these changes, and 

there is very little understanding of the consequences. 

Vegetation type and land use can have large effects 

on carbon storage. Forest lands can have much larger 

stocks of biomass carbon than grasslands, whereas 

grasslands can have larger stocks of soil organic 

carbon (SOC) (Jackson and others 2002, Post and 

Kwon 2000). Not only do grasslands allocate more 

net primary production (NPP) below ground, the 

distribution of carbon to the soil recalcitrant pools 

can be much higher in grasslands. The hydrologic 

and biogeochemical cycles are strongly affected by 

the type and density of vegetation (Huxman and 

others 2005, Wilcox and others 2006, Zhang and 

others 2001). Some wildlife benefit from the denser 

woody vegetation of a landscape without fire while 

others favor the vegetation produced by frequent fire, 

and landscape level species richness may be greatest 

where there is a patchwork of fire regimes (Engle and 

others 2008, Fuhlendorf and others 2006, Fuhlendorf 

and others 2009, Leslie and others 1996). Restoring 

the Cross Timbers to pre-EAS vegetation will require 

substantial efforts and major changes in land use. 

Intelligent and sustainable management of the Cross 

Timbers cannot be attained without more complete 

understanding of factors and forces controlling all its 

component resources and ecosystem services.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 63

ACKNOWLEDGMENTS

The authors’ research of the ancient Cross Timbers 

forests was inspired and encouraged by David 

Stahle, Distinguished Professor and Director, TreeRing Laboratory, University of Arkansas. Financial 

support was provided by the Oklahoma State 

University Department of Natural Resource Ecology 

& Management and the Oklahoma State University 

Cooperative Extension Service and Agricultural 

Experiment Station through a Division of Agricultural 

Sciences and Natural Resources Team Initiative 

Project grant and Centennial Scholarship. In addition, 

funding was provided by the Federal Aid PittmanRobertson Wildlife Restoration Act under Project 

W-160-R of the Oklahoma Department of Wildlife 

Conservation and Oklahoma State University. The 

project was administered through the Oklahoma 

Cooperative Fish and Wildlife Research Unit 

(Oklahoma Department of Wildlife Conservation, 

Oklahoma State University, United States Geological 

Survey, United States Fish and Wildlife Service, and 

Wildlife Management Institute).

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The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Fire Ecology of Oak 

Ecosystems: The Basis 

for Management
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Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 69

OAK SAVANNA RESTORATION: OAK RESPONSE TO FIRE AND THINNING

THROUGH 28 YEARS

Ronald E. Masters and Jack R. Waymire

Associate Professor (REM), University of Wisconsin - Stevens Point, 

Stevens Point, WI 54481; Senior Biologist (JRW), Oklahoma Department of Wildlife Conservation. 

REM is corresponding author: to contact, email at ron.masters@uwsp.edu.

Abstract.—We used a small plot study on Pushmataha Wildlife Management Area 

in southeast Oklahoma to determine the efficacy of fire frequency and thinning as 

management tools for restoration of oak savanna, oak woodlands, pine-bluestem 

woodlands, and pine savanna for application on a landscape scale. On selected 

experimental units, we initially reduced stand density to favor either oak canopy 

dominance or pine dominance to near presettlement stand density. Thinned stands were 

then subjected to 0-, 4-, 3-, 2-, and 1-year late dormant season (late February - early 

April) fire frequency regimes for 26 years. For comparison, we withheld control units 

from treatment and also included unthinned but with 4-year burn regime treatment 

units. We included two additional thinning treatments, the oak-savanna and pinebluestem treatments, both with annual burn regimes; the oak-savanna had all pine 

removed (approximately 50 percent of the basal area) and the pine-bluestem had half of 

the hardwood thinned (approximately 25 percent of the pre-treatment basal area). We 

compared mortality rate, acorn production, and growth response of selected post oaks 

and blackjack oaks. We also assessed nutrient content of post oak acorns to determine 

prescribed fires potential influence on nutrient status. We found a differential response 

by species to presence or absence of fire; but all selected trees responded favorably in 

diameter growth to thinning. Blackjack oak mortality was highest on unthinned and 

unburned sites versus any of the fire treatments because of hypoxylon cancer, an indirect 

result of high stand density (competition) and drought stress. Mortality of post-oaks 

was related to initial burns, and to some extent, cumulative effects of fire frequency 

interacting with fuel loads. Although thinning efforts on a landscape level were applied 

on the Wildlife Management Area beginning in 1978, fire frequency was >4-year 

intervals, inadequate for maintenance of savanna and woodland structure. Based on small 

plot study results we begin landscape application of frequent fire on a 1-3 year cycle in 

1997 and increased thinning in 1999-2001. Restoration thinning and a more focused burn 

regime was applied in a site specific manner on the landscape in 2008 through present. 

Woodland-grassland and forest-shrub obligate songbirds, white-tailed deer, and Rocky 

Mountain elk have responded favorably.
70 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

INTRODUCTION

Fire suppression along with attendant forest 

densification has had a pervasive, deleterious influence 

on numerous ecosystems across eastern North 

America (Nowacki and Abrams 2008). In particular, 

the interior Highlands of Oklahoma, Arkansas, and 

parts of Missouri have over the last century and more 

succeeded from a landscape matrix composed of 

prairie elements, oak and pine savanna (see Appendix 

for list of common and scientific names), and oak 

or pine woodland-grassland complexes to a dense 

homogeneous hardwood or oak-pine dominated land 

cover (Beilmann and Brenner 1951; Foti and Glenn 

1991; Masters and others 1995, 2007). Historically 

associated wildlife species included bison, elk, 

white-tailed-deer, many other mammals, and birds in 

abundance (Featherstonhaugh 1844, Smith and Neal 

1991). 

This forest densification and homogenization has 

led to declines in species richness and abundance of 

flora (Gilliam and others 2006, Sparks and others 

1998) and fauna. Declines in wildlife species included 

extirpation of bison, elk, some meso-mammals (Smith 

and Neal 1991), and near-loss of some small mammals 

and woodland-grassland obligate songbird species, 

particularly those associated with pine-grasslands 

(Masters and others 1998, 2002; Wilson and others 

1995). 

As forest density and canopy cover increases, 

understory herbage production declines and understory 

structure changes (Fenwood and others 1984; Masters 

and others 1993a, 1996). This has a profound influence 

on many species of wildlife in several respects. In 

closed canopy forests of the Ozark and Ouachita 

Mountain regions similar to other Interior Highlands 

in the eastern United States, the understory forage 

base for white-tailed deer and elk is often inadequate 

to meet nutritional requirements to sustain healthy 

populations year round. This problem is compounded 

in winter because of little or no suitable evergreen 

winter browse (Masters and others 1993a, 1997; 

Segelquist and Pennington 1968; Segelquist and others 

1969, 1972). In addition to herbage declines, structural 

complexity changes with densification and canopy 

closure, thus precipitating major impacts on songbird 

and small mammal communities (Engstrom and others 

1984; Masters and others 1998, 2002; Wilson and 

others 1995).

Oak mast provides a valuable food resource for 

numerous wildlife species (McShea and Healy 2002). 

Oak mast failures in this region have been linked to 

winter mortality of deer, decreased productivity, and 

summer fawn mortality (Logan 1972; Segelquist and 

others 1969, 1972). During late fall and winter, deer 

preferentially select hard mast and only turn to browse 

and herbage in appreciable amounts when acorns are 

unavailable (Harlow and others 1975, Segelquist and 

Green 1968).

Establishment of food plots has been the traditional 

approach to provide additional forage as a contingency 

for mast failure (Masters and others 1993a, 

1997). Some value has been shown for providing 

supplemental forage in the limited productivity forests 

of the Interior Highlands (Segelquist 1974, Thompson 

and others 1991). Deer mortality is less in years of 

mast failure in areas of contiguous closed canopy 

forest where comparatively large forage clearings 

have been developed (Segelquist and Rogers 1974). 

However, adequate nutrition for deer in years of mast 

shortfall can only be provided in unique situations 

because oak mast is substantially higher in nutritional 

quality than typically available winter forage (Harlow 

and others 1975). 

Pine-grassland restoration efforts via thinning and use 

of frequent fire have resulted in favorable population 

responses of pine-grassland obligate songbirds, small 

mammals, and in successful restoration of understory 

herbaceous communities and improved food resource 

availability for deer (Masters and others 1996, 1998; 

Sparks and others 1998; Wilson and others 1995). 

However, little research attention has been given to 

comparative efforts using thinning and frequent fire 

for restoration of oak savannas or mixed oak-pine 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 71

woodlands on the effects on wildlife occurrence or on 

the long-term effects of varying fire frequency on oak 

survival and development.

In the late 1960s and early 1970s, the Pushmataha 

Wildlife Management Area (PWMA) in southeast 

Oklahoma experienced a precipitous decline of the 

deer population and of a recently established elk 

population. Because of the importance of oak mast 

for deer and the need for improving the forage base 

for these two focal species, the Oklahoma Department 

of Wildlife Conservation began long-term research 

on thinning and frequent fire strategies that retained 

selected oaks at lower stand densities on a series 

of small plots designated as the Pushmataha Forest 

Habitat Research Area (FHRA) (Masters 1991a, 

1991b; Masters and others 1993a). The goal was to 

critically examine then current strategies to develop 

early succession openings (ESOs) for forage and to 

improve mast production by releasing selected oaks 

from competition. 

The forest management strategy at that time employed 

commercial thinning of mixed oak-pine stands to 

create ESOs. These were created by harvesting 

merchantable pine and thinning remaining hardwoods 

to a target basal area (BA) of about 9 m2

/ha, 

approximating presettlement stand density in parts 

of the Ouachita Mountains (Foti and Glenn 1991, 

Masters and others 2007). The fire frequency needed 

to perpetuate early succession openings was unknown 

as was the effects of frequent fire on oak survival 

and general health. Conventional wisdom at that 

time suggested frequent fire was deleterious to oaks. 

Following mid-term results, management strategies 

were to be developed and applied on the landscape of 

PWMA.

To that end we examined post oak and blackjack 

oak response in untreated control, thinned only, 

and thinned and burned stands at 4, 3, 2, and 1 year 

burning cycles on the FHRA beginning in 1983. Our 

goal was to evaluate the validity of a current forest 

management strategy for determination of leave 

trees in timber harvest units. As an objective, we 

wanted to determine the effects of fire frequency on 

survival, diameter growth, crown development, and 

acorn production. Further, we wanted to determine 

if fire had an influence on nutrient content of acorns. 

Following thinning we predicted that selected trees 

would experience increased radial and crown growth 

and increased acorn production as a result of decreased 

canopy, water, and nutrient competition. We expected 

a cumulative increase in oak mortality within a 10-year 

study horizon, commensurate with crossing some fireinterval threshold encompassed within our increasing 

fire frequency treatments. Further, we expected that 

longer interval repeated burning would have positive 

cumulative effects on growth and survival over time 

as selected trees were freed from canopy and moisture 

competition. 

Results from the small plot study would then be 

used to develop a restoration strategy for treatment 

application to the PWMA landscape. A critical part of 

that strategy included monitoring and evaluating deer, 

elk, and songbird response to landscape application of 

restoration treatments.

STUDY AREA

The study area was 29.1 ha in size and located 

within the FHRA (34°32’N, 95°21’W) on the 7,395 

ha PWMA near Clayton, Oklahoma. The PWMA is 

located in the Kiamichi Mountains along the western 

edge of the Ouachita Highland Province. The study 

area is on thin, drought prone Hector-Pottsville soils 

developed from cherty shales and resistant sandstones. 

They belong to the Carnasaw-Pirum-Clebit association 

with a high proportion of surface rock and areas of 

rock outcrop (Bain and Watterson 1979). Soil nutrient 

levels and their response to our periodic prescribed 

fire and thinning treatments have been described by 

Masters and others (1993b). Available P, K, Ca, and 

Mg increased and nutrient cycling was enhanced when 

thinning and burning were applied together.
72 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

The climate is semi-humid to humid with hot summers 

and mild winters (Bain and Watterson 1979). Rainfall 

is somewhat unequally distributed throughout the 

year with August being drought prone and the driest 

month (x = 6.0 cm) and May the wettest (x = 14.7 

cm) (Masters 1991b). From 1978-2010 average 

annual precipitation on or in the study area vicinity 

was 124.4 cm (unpublished data from Department 

of Natural Resource Ecology and Management, 

Oklahoma State University and Oklahoma Department 

of Agriculture, Forestry Services). From 1984 to 

1996 annual precipitation was 146.5 cm (SD = 26.1), 

well above the 34 year average, and from 1997-2010 

annual precipitation was 113.5 cm (SD = 27.6), 

which was significantly lower (P > T =0.004) than 

the previous period. We obtained Palmer Drought 

Severity Index (PDSI) data during our study period for 

Oklahoma and Arkansas from the National Oceanic 

and Atmospheric Administration (2011). We used an 

October-September water-year for rainfall and drought 

indices data summarization (Fig. 1). In spring 1987, 

a late freeze affected acorn production and ice storms 

followed by high winds and crown damage to trees on 

FHRA occurred in December 1996, December 1997, 

December 2000, and January 2007. 

Prior to acquisition from 1946-54, PWMA was grazed, 

selectively harvested, and frequently burned. The 

Forest Habitat Research Area was protected from 

further logging, grazing, and fire until 1984. The 

FHRA has been excluded from fire at least since 1969.

Figure 1.—Annual and long-term average (LT AVE) annual 

rainfall (cm) based on an October-September water-year 

for Pushmataha Forest Habitat Research Area 1978-2010, 

Pushmataha Wildlife Management Area, OK. Rainfall for the 

period 1983-1996 was higher (P=0.004) than for the period 

1996-2010.

Prior to treatment and on unharvested sites (control 

and rough reduction burn), post oak, shortleaf pine, 

mockernut hickory and blackjack oak were respective 

dominates in the overstory. The BA of unharvested 

treatments ranged from 24-30 m2

/ha. Common 

understory species included: tree sparkleberry, poison 

ivy, Virginia creeper, greenbriar, and muscadine grape. 

Although sparsely occurring, the most prevalent 

understory herbaceous plants were little bluestem, 

panicums, and sedges (Masters 1991a, b).

Post-treatment harvested and thinned openings were 

dominated by tall grasses and woody sprouts of 

varying density, depending on fire frequency and 

time since burned for a given site. Grasses included 

big bluestem, little bluestem, and to a lesser extent, 

Indiangrass, and in drainages switchgrass. Post oak, 

blackjack oak, winged sumac, and blackberry were 

dominant understory woody species. The thinned 

overstory was comprised of sparse (~9 m2

/ha BA 

stems >5 cm at 1.4-m height) post oak and blackjack 

oak (Masters 1991a,b; Masters and others 1993a). The 

clearcut treatment was planted with loblolly pine in 

1986. Masters (1991a,b), Masters and Engle (1994), 

Masters and others (1993a,b, 1997), and Crandall 

(2003) have described the study area, management, 

and vegetation of these stands. The deer population 

on the entire PWMA was estimated at 7.3 deer/km2

 

± 3.8 (x ± SE) in 1984 based on spotlight counts. At 

that time the total elk population was six animals 

(Masters 1991b).

METHODS

Experimental Design

Beginning in summer 1984 through present, 10 

treatments with 1-4 replications were applied to 36, 

units (0.2-1.6 ha in size) in a completely randomized 

experimental design (Masters and others 1997). For 

the purposes of this paper, only the eight treatments 

that retained and involved monitoring of selected oaks 

were utilized (Table 1). The HT treatment included one 

replication until 1989 when a spot-over burned part of 

the unit. Because the monitored trees were not in the 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 73

burned area, the trees on this unit were retained for the 

purposes of this study. Three additional replications of 

the treatment were included at that time that had not 

previously been monitored. 

During summer 1984, merchantable pine trees were 

harvested in assigned treatments, and hardwoods were 

selectively thinned by single stem injection using 

2,4-D to approximately 9 m2

/ha basal area. Prescribed 

strip-head fires were applied on appropriate treatment 

units in mid-March and early April 1985 and in 

succeeding years at 1-, 2-, 3-, and 4-year intervals. 

Fireline intensity of March 1988 burns ranged from 

628-903 kW/m (Masters and Engle 1994). 

On each treatment unit, 10 permanent plots were 

established at 20 m intervals on two randomly located 

lines perpendicular to the contour. No sampling was 

conducted within 20 m of any edge to prevent bias 

from adjacent treatment units (Mueller-Dombois and 

Ellenberg 1974, Oosting 1956). Basal area of overstory 

vegetation was quantified each year using the variable 

radius plot method (Avery 1967). Basal areas of stems 

≥5 cm diameter at breast height (d.b.h.) were measured 

with a 10-factor wedge prism at each permanent plot 

location. Baseline sampling before cultural treatment 

application was conducted in 1983. Overstory canopy 

Table 1.—Study treatment acronyms, descriptions, and number of replications (N) for the Pushmataha 

Forest Habitat Research Area, Pushmataha Wildlife Management Area, Oklahoma, for 1983-present

Treatment Description N

Control Control, no thinning, no burning 3

RRB Rough reduction, late-winter prescribed burn, 4-year interval 3

HNTI Harvest pine timber only, late-winter prescribed burn, 1-year interval; Oak savanna, except 1995 3

HT Harvest pine timber, thin hardwoods, no burn (natural regeneration to a mixed stand) 

(initially 1 replication was monitored, then an additional 3 were monitored after 1989)

4

HT4 Harvest pine timber, thin hardwoods, late-winter prescribed burn, 4-year interval 3

HT3 Harvest pine timber, thin hardwoods, late-winter prescribed burn, 3-year interval 2

HT2 Harvest pine timber, thin hardwoods, late-winter prescribed burn, 2-year interval, except 1995 3

HT1 Harvest pine timber, thin hardwoods, late-winter prescribed burn, 1-year interval, except 1995 3

cover was determined from mid-September to midOctober prior to leaf abscission. Estimates were made 

with a 9-point grid in a sighting tube with vertical and 

horizontal levels at plot center and cardinal points at 

2 m and 4 m from each permanent plot location in 

most years from 1985 to 2010 (Mueller-Dombois and 

Ellenberg 1974). 

Mast Tree Sampling

We selected three post oaks and three blackjack oaks, 

where available, as study trees from each treatment 

unit, following commercial pine harvest in 1984. 

Initially we sought to include black oaks as well, but 

given the paucity of this species on the study area and 

unequal distribution, only a few were available and 

chosen for monitoring. Black oaks did not occur in all 

units or treatments. 

On each unit, all oak trees were systematically 

examined before selection. Those selected must not 

have been damaged by commercial timber harvest, in 

terms of canopy breakage or bark damage from felled 

trees or skidders. Further, trees were evaluated based 

on canopy development, height, and d.b.h. Oaks in 

the dominant or codominant position in the canopy 

were selected over intermediate or suppressed trees. 

However, some of the selected blackjack oaks were 
74 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

in intermediate canopy position as these were all that 

were available. The best formed and most vigorous 

appearing trees were selected from all candidate trees 

because acorn production is strongly related to tree 

diameter, crown area, and condition (Goodrum and 

others 1971). Trees on harvested units had complete 

crown release from competition and were generally 

farther than 20 m from the nearest residual tree. All 

competing residual trees greater than 5 cm in diameter 

that had touching or overlapping crowns were single 

stem injected as described earlier. We chose to select 

trees based on specified criteria rather than at random 

because we were evaluating validity of the current 

forest management strategy for determination of leave 

trees in timber harvest units. 

Variables included for measurement included age, 

species, d.b.h., total height, crown area, and since 

2000 crown density. Measurements were taken every 

year until 1989 and at least every 2 years thereafter. 

Mortality was tracked each year. In the first years of 

the study we did not measure crown area and height of 

trees on the annually burned treatments.

We measured d.b.h. annually to the nearest 0.1 cm 

using a standard diameter-tape. We used a clinometer 

to estimate total tree height to the nearest 0.5 m at 20 

m distance until 2000. In following years a calibrated 

hypsometer was used to estimate height to the nearest 

0.1 meter height. 

To estimate crown area, we measured live crown 

diameter at two perpendicular axis and then calculated 

area based on the formula for the area of an ellipse 

whose semiaxes are a and b, A = Πab. To assess crown 

density and health, from 1994 to 2010 we estimated 

canopy density beneath each sample tree from midSeptember to early October prior to leaf abscission at 

cardinal points half the distance from the tree bole to 

canopy edge.

Postburn measurements after the initial thinning 

and first prescribed burn included bark-char height 

and height of limb scorching. Residual bark char 

prevented remeasurement in succeeding years. During 

early burns, fire behavior was estimated and fireline 

intensity was calculated after Masters and Engle 

(1994) and later modeled with BEHAVE or based on 

flame length estimates.

Acorn Sampling

We evaluated acorn production and viability from 

1984-1989 and 1998 in Control, HT, HT4, HT3 and 

HT2 treatments. We used 18.93 liter buckets with an 

opening diameter of 28.96 cm for an effective trap 

area of 658.52 cm2

. Mast traps were fitted with wire 

screen covers to prevent wildlife depredation and 

placed at four quadrants under each tree; trap center 

was half the distance from the bole of the tree to the 

edge of the crown. We checked acorn traps at 1 week 

intervals beginning in early September until acorn 

drop was completed, generally late November during 

each sampling year. Acorns were counted, bagged, and 

the green weight recorded to the nearest 0.1 g. We also 

recorded the percent of acorns that were sound based 

on a viability rating of the percentage of sound acorns 

in the trap (Christisen and Kearby 1984, Goodrum and 

others 1971). We extrapolated total acorn production 

of viable acorns for each tree based on the crown area 

and percent of crown sampled.

In 1988, acorns from all post oaks on selected 

experimental units were collected for nutrient analysis 

by tree. Nutrient analysis of samples was conducted 

by Servi-Tech, Inc. (Dodge City, KS) and included 

moisture content, dry matter content, ash, crude 

protein, acid detergent fiber (ADF), total digestible 

nutrients (TDN), calcium, phosphorous, magnesium, 

and potassium. 

Landscape Treatment and Wildlife 

Response

We selected stands to apply landscape thinning and 

burning treatments based on topographic position, site 

characteristics, and species composition. Historical 

references and settlement period tree density, basal 

area, and fire regime were also used to determine 

thinning levels and fire regime on targeted sites (Foti 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 75

and Glenn 1991; Johnson 1986; Kreiter 1994; Masters 

and others 1995, 2007). Restoration thinning and 

burning began in 1999. Target stand types and target 

basal areas were oak-savanna and oak-pine savanna 

(7 m2

/ha), and oak-pine woodland and pine-bluestem 

woodland (14 m2

/ha). Riparian corridors and upland 

drainages were not thinned but were included in the 

adjacent administrative unit fire regime. More detail on 

proportion and juxtaposition of restoration treatments 

may be found in (Masters and Waymire 2012).

During August and September each year, spotlight 

counts were conducted for a minimum of 10 nights 

on a 16.1 km route using standardized Oklahoma 

Department of Wildlife Conservation protocols to 

index deer population status. In February of each year, 

total elk counts are made by driving the same route 

in late afternoon with the high count of the survey 

used as the population index. We used Breeding 

Bird Survey (BBS) data for Pushmataha County 

to derive trend data of target species of interest 

for PWMA (Sauer and others 2011). We chose 20 

species to examine based on published accounts of 

habitat association and response to habitat change 

and whether or not they were species of special 

management concern (Cox and Widener 2008, Masters 

and others 2002, Wilson and others 1995). A total of 

37 of the 50 stops in Pushmataha County were located 

on the PWMA. Individual stop data for each year 

from 1994-2009 were obtained for these 37 stops. 

Data Analysis

Means were tested for homogeneity of variance 

among treatments using Levene’s test (Snedecor 

and Cochran 1980). When variances were unequal 

we used the Kruskal-Wallis nonparametric test to 

determine treatment differences in acorn production, 

average annual diameter growth, tree height, and 

crown diameter (Steel and others 1997). Unit × year 

× treatment type III mean square was the error term 

(SAS Institute 1985). We used multiple comparisons 

between mean ranks with the Least Significant 

Difference (LSD) test with P = 0.050 (Steel and 

others 1997). We used rank transformations to 

analyze percentage data. Correlation analysis was 

used to examine relationships between weather, fire 

characteristics, and tree mortality and regression to 

examine linear trends in BBS data.

RESULTS

Stand Response

Pretreatment stands were characterized by closed 

canopy overstory and dense pine-hardwood midstory 

with extensive leaf-litter cover in the understory. Pine, 

hardwood, and total basal area (x ± SE; 25.3 m2

/ha 

± 0.5) were similar (P>0.05) across all experimental 

units in 1983 but different (P<0.05) in 1984 after 

thinning and in following years (Table 2). Stand 

Table 2.—Pine, hardwood, and total basal area 

(BA) (m2/ha) change by treatment on Pushmataha 

Forest Habitat Research Area, Pushmataha Wildlife 

Management Area, OK. Data in 1984 were postthinning and in 2010 following fire frequency 

directed tree succession. Means with same letter 

were not different (P > F <0.004). See Table 1 for 

treatment descriptions. Most burns were in late 

February through mid-March. 

Pine BA (m2/ha)

1984 2010

Treatment Mean SE Mean SE

CONT 12.6 a 2.5 14.3 ab 2.0

RRB 13.9 a 1.7 15.5 ab 1.3

HNT1 0.3 b 0.2 0.9 d 0.3

HT 0.9 ab - 21.1 a 6.2

HT4 1.1 ab 0.7 9.9 abc 3.7

HT3 0.6 b 0.3 2.0 cd 0.4

HT2 2.2 ab 0.7 2.6 bcd 0.5

HT1 0.5 b 0.2 1.1 d 0.6

Hardwood BA (m2/ha)

1984 2010

Treatment Mean SE Mean SE

CONT 13.9 a 0.8 12.9 a 1.8

RRB 11.7 a 1.2 9.9 a 1.2

HNT1 9.6 ab 1.7 6.2 bc 1.1

HT 8.3 ab - 10.0 ab 2.2

HT4 7.8 ab 0.9 3.9 cd 0.4

HT3 4.8 b 0.5 3.1 cd 0.1

HT2 6.3 ab 1.7 3.0 cd 0.3

HT1 6.8 ab 0.2 2.1 d 0.3

(Table 2 continued on next page)
76 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

understory immediately following thinning was 

characterized by a clumped and patchy ground cover 

of slash and sparse cover of hardwood sprout shrubs, 

vines, grasses, and forbs (Fig. 2). After the first burn 

and following subsequent burns, grass and forb cover 

Table 2 (continued).—Pine, hardwood, and total 

basal area (BA) (m2/ha) change by treatment 

on Pushmataha Forest Habitat Research Area, 

Pushmataha Wildlife Management Area, OK. Data 

in 1984 were post-thinning and in 2010 following 

fire frequency directed tree succession. Means 

with same letter were not different (P > F <0.004). 

See Table 1 for treatment descriptions. Most burns 

were in late February through mid-March. 

Total BA (m2/ha)

1984 2010

Treatment Mean SE Mean SE

CONT 26.5 a 1.7 27.4 a 0.7

RRB 25.6 a 1.0 25.2 a 0.5

HNT1 9.9 ab 1.8 7.2 bc 1.3

HT 9.2 ab - 31.7 a 4.3

HT4 9.0 ab 1.5 13.8 ab 4.0

HT3 5.4 b 0.1 5.1 bc 0.5

HT2 8.5 ab 2.3 5.6 bc 0.7

HT1 7.3 ab 0.2 3.2 c 0.7

predominated on thinned and burned treatment stands 

and had 21 times greater standing crop than control. 

Herbaceous standing crop on unthinned but burned 

RRB was three times that of control stands (Masters 

and others 1993a) (Figs. 3 and 4). Over time tree 

structure developed along a fire frequency gradient 

with unburned stands developing into dense closed 

canopy stands. For frequently burned stands, as 

fire frequency increased tree density and basal area 

decreased (Table 2 and Figs. 3 and 4).

Mortality

By 2010 total mortality was 38 of the 131 selected 

trees for 29.1 percent (Fig. 5). Percent mortality of just 

blackjack oak was over double that of post oak (44.4 

percent versus 18.1 percent). Fire related mortality for 

all trees was 16.8 percent, and hypoxylon mortality 

was 10.7 percent. A total of 12 blackjack oak trees 

and 1 black oak succumbed to hypoxylon canker. A 

higher proportion of total blackjack oak mortality was 

from disease rather than fire. Except for one tree, all 

blackjack oak mortality from hypoxylon canker was 

on unthinned treatments. Lightning mortality of two 

post oaks was 1.5 percent (Fig. 5).

Figure 2.—Example of stand conditions post pine harvest and hardwood thinning (HT) before the first burn. All HT units were 

similar in residual hardwood basal area before burning on the Pushmataha Forest Habitat Research Area, Pushmataha 

Wildlife Management Area, OK.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 77

Figure 4.—Photos of different treatments after 21 

years of treatment application in early October 

2006. All treatments in this figure were similar to the 

control (top left, Fig. 3) in 1983. Pine harvest and 

thinning was accomplished in early summer 1984 

(see Fig. 2) and burning initiated in late winter 1985. 

Top left to right: HT4, harvest pine, thin hardwoods 

to approximately 1⁄2 of original basal area, latewinter burn at 4-year interval; HT3, harvest pine, 

thin hardwoods to approximately 1⁄2 of original basal 

area, late-winter burn at 3-year interval. Bottom 

left to right: HT2, harvest pine, thin hardwoods 

to approximately 1⁄2 of original basal area, latewinter burn at 2-year interval; HT1, harvest pine, 

thin hardwoods to approximately 1⁄2 of original 

basal area, late-winter burn at 1-year interval 

on Pushmataha Forest Habitat Research Area, 

Pushmataha Wildlife Management Area, OK. 

Figure 3.—Photos of different treatments after 21 

years of treatment application in early October 

2006. All treatments in this and in Fig. 4 were 

similar to the control (top left) in 1983. Pine harvest 

and thinning was accomplished in early summer 

1984 (see Fig. 2) and burning initiated in late winter 

1985. Top left to right: Control, no treatment; 

RRB, no harvest or thinning, late winter burn on a 

4-year interval. Bottom left to right: HNT1, harvest 

pine, no hardwood thinning, annual late winter 

burn; HT, harvest pine, no thinning and no burning 

on Pushmataha Forest Habitat Research Area, 

Pushmataha Wildlife Management Area, OK.

Figure 5.—Cause-specific mortality of selected post, blackjack, and black oaks on the Forest Habitat Research Area, 

Pushmataha Wildlife Management Area, OK from 1983-2010. 
78 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Blackjack and post oak mortality was 9.2 percent in 

the first growing season postburn and totaled 10.7 

percent by the second year following introduction 

of fire on ESO treatments. This pulse of fire-caused 

mortality affected blackjack oak more severely than 

post oaks (Fig. 6). Smaller trees (lower diameter, 

height, and crown area) tended to succumb to fire in 

this initial pulse. Blackjack oak mortality leveled out 

following the first 2 years postfire reintroduction. The 

first canker-related mortality to blackjack oak occurred 

in 1994, and since 2002 subsequent mortality has been 

entirely from hypoxylon canker on control units and 

RRB treatments (Figs. 5 and 6). Of those trees dying 

from hypoxylon, 92.3 percent were during the period 

of below average rainfall and mortality was associated 

with the 2 previous years PDSI (r=0.327, P<0.05). 

The last fire-caused mortality of blackjack oak was in 

2002. Control units experienced 87.5 percent mortality 

to blackjack oaks from hypoxylon canker (Fig. 7). 

Blackjack oak mortality on HT4, HT2, and HT1 

treatments resulted from initial prescribed fires applied 

in the same week, and thus was not a fire frequency 

effect (Figs. 5 and 7). 

Post oak attrition has been slight annually but 

steady until 2002 with 58 of the original 72 trees 

(81.9 percent) surviving thereafter through 2010 

(Fig. 6). Post oak mortality was related largely to a 

fire frequency gradient on ESO treatments but also 

influenced by lightning mortality (Fig. 6 and 8). The 

HNT1 or post oak savanna treatment had the least 

post oak mortality of any of the thinned and burned 

treatments (P=0.004). Fuel loading tended to be 

lower on this treatment, particularly around the bole 

of selected trees, than on the other annually burned 

treatment, thus resulting in lower fire line intensity.

Crown Area, Height, 

and Diameter Response

Following commercial pine harvest and thinning of 

hardwoods in 1984, selected mast trees were similar in 

conformation (P<0.05) across all treatments. Average 

crown area, height, and d.b.h. of blackjack oak was 

Figure 6.—Annual survival (%) of selected post and 

blackjack oaks from the Forest Habitat Research Area, 

Pushmataha Wildlife Management Area, OK from 1983-

2010.

Figure 8.—Percent mortality of selected post oaks by 

treatment on the Forest Habitat Research Area, Pushmataha 

Wildlife Management Area, OK from 1983-2010. See Table 

1 for treatment descriptions. Percent mortality by treatment 

with the same letters was not different (P=0.004). 

Figure 7.—Percent mortality of selected blackjack oaks by 

treatment on the Forest Habitat Research Area, Pushmataha 

Wildlife Management Area, OK from 1983-2010. See Table 

1 for treatment descriptions. Mortality on the CONT, RRB 

and HT treatments was from hypoxylon canker. Mortality on 

the thinned and burned treatments was fire related. Percent 

mortality by treatment with the same letter was not different 

(P=0.014).
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 79

respectively 25.1 m2 ± 3.3, 11.0 m ± 0.4, 35.6 cm ± 

1.2. Average crown area, height, and d.b.h. of post 

oak was 68.5 m2

 ± 4.3, 15.7 m ± 0.4, 23.6 cm ± 1.4, 

respectively. 

It took 6 years for differences to be expressed in 

terms of blackjack oak physical characteristics 

following initial treatment. In subsequent years and 

during the period of above average rainfall, we found 

differences (P<0.050) in height in 3 years, d.b.h. in 

4 years, and in crown area in 2 years for blackjack 

oak. When differences became apparent, the height 

was greater on HT2, RRB, and HT treatments than 

on Control treatments. However as the HT stand 

densified, height-growth slowed, and heights became 

similar to the Control by 1991 (P=0.36) but less than 

HT2 and RRB. Crown area and d.b.h. exhibited a 

similar pattern. After 1997 and throughout the period 

of below average rainfall, we found no differences 

in any of these variables between treatments for 

blackjack oak. Because of declining sample size and 

loss of some replications from both fire and disease 

mortality, the ability to detect meaningful differences 

was compromised somewhat as illustrated by average 

annual growth of blackjack oak across 28 years 

(Fig. 9).

We observed no treatment differences in average d.b.h. 

or crown area in any years in post oaks. However, we 

observed differences in average height by treatment 

5 years following the ice storms. Post oaks from the 

HT treatment averaged greater heights than did the 

harvested and burned treatments. The treatments 

that were burned were much more open throughout 

the study, and crowns were more exposed to ice 

damage. The crowns of post oaks in the HT treatment 

were somewhat protected from the ice storms until 

2007. Following that ice storm, post oaks in the HT 

treatment experienced severe crown damage and were 

near the lowest in height and were supplanted by the 

Control and RRB with highest average height. In 

contrast to height, average annual diameter growth was 

lowest for the HT treatment and highest for the HT4 

(Fig. 10). Following ice storms and during the below 

average rainfall period, thinned and burned treatments 

had lower (P>0.050) heights because of top breakage 

in 4 years. Following the damaging storm in 2007 

which affected trees across the board, we found no 

difference in height or crown area.

In 2010, average crown area, height, and d.b.h. of all 

blackjack oak across treatments was not different and 

was respectively 29.0 m2

 ± 4.8, 11.2 m ± 0.5, 

31.4 cm ± 2.4. The same was true for post oak with 

average crown area, height, and d.b.h. of 78.1 m2

 

± 3.6, 15.5 m ± 0.3, 43.6 cm ± 0.9, respectively.

Acorn Production and Nutrient Content

In the first fall (1984) of the 7 years that we monitored 

post oak acorn production, we observed no differences 

among units treated alike because commercial harvest 

was accomplished by mid-summer and hardwood 

Figure 10.—Mean (± SE) post oak average annual diameter 

growth from 1984-2010 by treatment on the Forest Habitat 

Research Area, Pushmataha Wildlife Management Area, OK. 

See Table 1 for treatment descriptions. Treatment means 

with the same letter were not different (P=0.031). 

Figure 9.—Mean (± SE) blackjack oak average annual 

diameter growth from 1984-2010 by treatment on the Forest 

Habitat Research Area, Pushmataha Wildlife Management 

Area, OK. See Table 1 for treatment descriptions. Treatment 

means were not different (P=0.126). 
80 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

thinning shortly thereafter. That year was a bumper 

acorn production year with an average of 105.2 kg 

± 17.7 per tree across all units and the highest during 

the study years. Only in 1 year (1988) did post oak 

acorn production differ (P=0.0099) between treatments 

(Fig. 11). Here the thinned but unburned treatment 

(HT) had the highest production. The previous year 

showed a strong similar tendency in acorn production 

by treatment (P=0.071) with the HT treatment again 

being highest. Post oak acorn production varied widely 

by year exhibiting a strong year effect (P<0.0001) 

with 2 years of the 7 producing an average of <1 kg of 

acorns per tree across all treatments. Another year had 

very low production, and 2 years exhibited moderate 

production, one of which was 1988 (Fig. 9). We 

observed no year by treatment interaction (P=0.381) 

but did observe a tendency (P=0.115) for the HT 

treatment to have higher post oak acorn production 

when analyzed across all years, with the burned 

treatments similar in production to the control. 

We found no differences in acorn production by 

blackjack oaks in any year as a response to thinning 

and burning. However this may have been a result 

of high fire-caused mortality following the first burn 

and mortality from canker on unburned controls, 

thus lowering sample tree number and number of 

replications for some treatments. When analyzed 

across all years that acorn production was monitored, 

we observed a strong tendency (P=0.052) for a 

treatment effect wherein the thinned (burned or 

unburned) treatments ranked higher in production 

than the control. Some blackjack acorn production, 

although somewhat limited at times, occurred in every 

year (F-test for year effect; P=0.086). 

Nutrient content of sampled acorns generally varied 

more by tree within treatment units than between 

treatments (P>0.05) (Table 3). The only exception 

was moisture content which was different (P=0.030) 

depending on the time since burned and number of 

times burned (Table 3). Acorns from the unburned 

control and the burned unit three-growing seasons 

Figure 11.—Mean (± SE) post oak acorn production in 

1988 by treatment on the Forest Habitat Research Area, 

Pushmataha Wildlife Management Area, OK. See Table 1 

for treatment descriptions. Treatment means with the same 

letter were not different (P=0.0099).

postburn had higher moisture content than the more 

frequently burned treatments. Crude protein was 

elevated slightly (P=0.120) in more frequently burned 

treatments.

Landscape Treatment 

and Wildlife Response

When initial thinning efforts were applied on a 

landscape level on PWMA beginning in 1978, fire 

frequency was >4-year intervals and inadequate for 

maintenance of savanna and woodland structure. 

Based on small plot study results, we began landscape 

application of frequent fire on a 1-3 year cycle in 1997, 

increased thinning in 1999-2001, then restoration 

thinning on the landscape in 2008 through present 

(Masters and Waymire 2012). By 2010, appropriate 

thinning regimes had been applied on 3,704 ha or 

47.5 percent of the area. Since 1999 we have averaged 

2,460 ha of prescribed burning annually. Both deer 

and elk populations have responded dramatically 

to landscape level application of thinning to 

presettlement basal areas and application of frequent 

fire across the area. Deer populations have increased 

from 7.3 deer/km2

 ± 3.8 in 1984 to 35.8 deer/km2 

± 9.6 in 2010. However we note that since 1999 the 

average number of deer observations during spot-light 

counts has increased dramatically, partially a result of 

day-lighting of roads (complete tree removal 20-40 m 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 81

 Number Months

of Burns Since Burns Mean SD Max Min

Percent Moisture

CONT 0 >200 48.1 a 4.6 55.3 39.4

HT1 gs 2 7 40.6 b 1.9 42.1 38.5

HT2 gs 2 20 32.3 c 9.7 40.2 21.5

HT3 gs 1 42 46.8 a 7.3 55.0 40.9

Crude Protein

CONT 0 >200 5.0 0.75 5.9 3.6

HT1 gs 2 7 6.0 0.90 6.6 5.0

HT2 gs 2 20 6.0 0.70 6.7 5.3

HT3 gs 1 42 4.8 0.89 5.5 3.8

ADF 27.9 5.5 38.0 19.5

Ash 2.7 0.3 3.4 2.2

TDN 70.5 5.0 78.1 61.2

Ca 0.44 0.13 0.86 0.29

P 0.09 0.01 0.12 0.07

M 0.10 0.03 0.20 0.08

K 0.77 0.17 1.23 0.55

Table 3.—Mean nutrient content (% dry matter) of post oak acorns from control and thinned and burned 

units (1, 2 and 3 growing seasons postburn) from the Forest Habitat Research Area, Pushmataha Wildlife 

Management Area, OK in 1988. See Table 1 for general treatment descriptions, except that numbers 

represent number of growing seasons (gs) post-burn. Differences were not significant other than for 

percent moisture content. Means with the same letter or no letters were not different (P > 0.050).

either side of the road), thus inflating estimates to 

some extent. Never-the-less the trend is clear. Elk 

index numbers have increased from 6 in 1984 to 50 in 

2010 (Masters and Waymire 2012).

On the PWMA portion of the BBS route from 1994-

2009, a total of 70 different songbird species were 

reported. Average species richness per year was 39 

± 3. Of the 20 target species we selected, 8 were 

considered woodland-grassland associates, 6 were 

considered forest-shrub (edge) associated species, 

and 6 were considered forest interior species. All 

songbirds from the woodland-grassland species group 

except the pine warbler showed an increasing trend 

(Table 4). The trend was level throughout the study 

period. Of particular note was the strong increase for 

Bachman’s sparrow, a species of special management 

concern across the southeastern United States, and 

in Oklahoma and Arkansas in particular (Cox and 

Widener 2008). The yellow-billed cuckoo was the 

only forest-shrub associated species to demonstrate a 

downward trend following landscape treatments. In 

this group, notable increases over the 16 year timespan for blue grosbeak and common yellowthroat were 

observed. For the forest interior group the summer 

tanager showed an increasing trend while the tufted 

titmouse, downy woodpecker and red-eyed vireo were 

level and showed no influence from the application of 

restoration treatments. On the other hand, we observed 

declining trends for only black & white warbler and 

chuck-will’s-widow (Table 4). 
82 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Table 4.—Breeding bird trends of selected species 

from Pushmataha Wildlife Management Area, OK, 

1994-2009 following landscape level application 

of restoration treatments. Trends are derived from 

only the Breeding Bird Survey Route data for 

Pushmataha County that occur on the Pushmataha 

Wildlife Management Area. A total of 37 stops out 

of the 50 for the county occur on the area. Key to 

trend symbol: + = increasing trend, – = decreasing 

trend, o = no or level trend.

Species Group/Species r2 Trend

Woodland-grassland

 Bachman’s Sparrowa 0.61 +

 Chipping Sparrow 0.12 +

 Eastern Wood Peweea 0.64 +

 Indigo Bunting 0.52 +

 Northern Bobwhitea 0.14 +

 Pine Warbler 0.00 o

 Prairie Warblera 0.39 +

 Red-headed Woodpeckera 0.12 +

Forest-shrub

 Blue Grosbeak 0.77 +

 Blue-gray Gnatcatcher 0.40 +

 Common Yellowthroat 0.81 +

 Mourning Dove 0.37 +

 Yellow-billed Cuckoo 0.22 –

 Yellow-breasted Chat 0.26 +

Forest interior

 Black & White Warbler 0.62 –

 Tufted Titmouse 0.00 o

 Downy Woodpecker 0.10 o

 Red-eyed Vireo 0.04 o

 Summer Tanager 0.43 +

 Chuck-will’s-widow 0.46 –

a

 Species of special management concern in southeast U.S.

DISCUSSION

Presettlement forests in the Ouachita Highlands 

of eastern Oklahoma and western Arkansas were 

characterized by low-density and low basal area stands 

from open woodland to savanna-like conditions. They 

included a variety of forest cover types that expressed 

dominance according to topographic position and 

site conditions including shortleaf pine-bluestem, 

mixed oak-pine woodlands, and post-oak dominated 

savannas or oak woodlands (Foti and Glenn 1991, 

Masters and others 2007). Fire was a common factor 

that influenced density and likely a given stand’s 

composition (Masters and others 1995, 2007). 

Forest thinning and periodic fire is useful for returning 

natural stands to structural characteristics similar 

to presettlement times and managing for the full 

complement of native wildlife species (Masters 

and others 1996, 2002; Wilson and others 1995). 

However, following thinning the reintroduction of 

fire into a stand long-excluded from fire should be 

undertaken with some degree of understanding. 

Otherwise extensive mortality of the residual trees 

may result. Wade and Johansen (1986) concluded 

that reintroduction of fire into stands long excluded 

from fire may cause delayed mortality from stem 

girdling because low intensity fires may smolder in the 

accumulation of sloughed bark and litter around the 

immediate bole of the tree. Tree mortality was related 

to bark thickness, moisture content of the tree (Martin 

1963), tree diameter, fire intensity, and residence time 

(Wade and Johansen 1986). Large-stemmed oaks are 

very resistant to fire induced mortality (Garren 1943, 

Komarek 1981, Kucera and others 1963, White 1986). 

This is due to the fact that the time for the cambium of 

trees to reach lethal temperatures increases with bark 

thickness (Hare 1965), and bark thickness increases 

with age (Davis 1953). Fire intensity is a causative 

factor in tree mortality, and mortality is determined 

largely by the extent of bark char and crown damage 

(Cain 1984) and is a function of fire type (backfire 

vs. headfire) (Fahnestock and Hare 1964) and season 

of burn (Waldrop and Van Lear 1984). The height of 

crown scorch on residual trees is a geometric function 

of fire intensity (Van Wagner 1973). 

We observed a mortality pulse following introduction 

of fire into our experimental stands. This pulse of 

mortality affected blackjack oaks more severely 

than post oaks (Fig. 6) and was likely related to 

high amounts of residual logging slash, related fire 

behavior, and perhaps the shock of fire introduction 

after a long absence (Wade and Johansen 1986). 

However, throughout the study a higher proportion of 

total blackjack oak mortality was from disease rather 

than fire compared to post oak. Canker mortality was 

found in unthinned stands except for one tree in the 

harvested and thinned but unburned treatment (HT). 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 83

This treatment had increased in basal area 3-fold over 

the 25 years post-thinning. It is of note that mortality 

in the unthinned RRB treatment (4-year interval) was 

reduced compared to the control. In this treatment, 

some reduction of midstory hardwoods has occurred 

over the course of our study as a result of repeated 

burning. As our weather and mortality data suggested, 

mortality in all disease cases was likely a result of 

competition and late summer drought stress (Conway 

and Olson 2004). Our evidence suggests that thinning 

and burning together alleviated competition and 

drought stress on blackjack oak.

Aside from the high mortality rate from canker, the 

100 percent blackjack mortality on the HT1 treatment 

but none on the HNT1 treatment also was unexpected. 

Because of the greater canopy cover on the HNT1 

treatment versus other thinned and burned treatments, 

there was substantially less fuel and thus lower fireline 

intensity for burns on this treatment. Lower fuel loads 

particularly adjacent to tree stems prevented stem 

girdling. Post oak also exhibited similar differential 

mortality with annual burned treatments, but otherwise 

mortality was increased with increasing fire frequency.

Based on mortality alone, our thinned treatments with 

less frequent fire intervals (3- and 4-year or no fire) 

would appear to be recommended alternatives for 

oak-savanna restoration. However, given that over 28 

years of the study, unburned treatments (HT) and the 

HT4 treatment had developed into immature forest 

stands (Table 2, Figs. 3 and 4) and were not judged 

viable alternatives for oak savanna restoration. Burn 

conditions during the first burns were lower than 40 

percent relative humidity at 1400 hrs and considerable 

crown scorch resulted in approximately 11 percent 

mortality that occurred over the ensuing 3 years and 

beyond. If burns were conducted under higher relative 

humidity and firing patterns used generated less 

intensity than strip head fires, likely mortality could 

have been reduced substantially. 

Conventional wisdom suggests that even mature oaks 

may respond with increased diameter, height, crown 

growth, and acorn production in response to full crown 

release (e.g., Cypert 1951, Drake 1991) although few 

studies have demonstrated this empirically and none 

other than this one that we are aware of with post oak 

or blackjack oak in the western part of its range on 

xeric sites. 

Weather conditions such as periodic ice storms and 

drought is a stronger determinant of individual tree 

growth and development and associated characteristics 

of diameter, height, and crown area increment than 

credited in the literature, especially on xeric sites. 

We measured increases, due to thinning and thinning 

and burning to some extent, in crown expansion, 

diameter, and height of blackjack oak during a 

period of above average rainfall. These increases 

disappeared following a period of years with shortinterval ice storms and during a period of significant 

below average rainfall. On an individual tree basis, 

those blackjack oak surviving our first burns grew 

vigorously on the thinned and burned treatments 

with 2- and 3-year intervals; however, with the loss 

of sample size and replication we cannot state this 

unequivocally. Greater development in open areas 

would not be surprising, however, as DeSantis 

and others (2010) suggested that blackjack oaks 

needed a growing environment with high light and 

further were more susceptible to drought and fire. 

Our data suggested that surviving blackjack oaks 

responded favorably in diameter growth in a high light 

environment, but also under drought and frequent fire 

conditions.

Post oaks were not as responsive to full crown release 

as blackjack oaks in terms of height growth and crown 

development. Our results were somewhat confounded 

by a series of ice storms that severely damaged some 

crowns. Blackjack oak was apparently more resistant 

to crown damage from ice than post oaks because of 

the stout and short nature of their limbs and compact 

nature of their crowns. We did find clear indications of 

higher average annual growth over 28 years on thinned 

and burned treatments. 
84 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Acorns are an important food item in the diet of many 

species of wildlife. As such any change in production 

and nutrient content as a result of management 

treatments may directly affect a given wildlife species 

nutritional status, especially during winter. We noted 

decreases in post oak acorn production with thinning 

and frequent fire but no difference from controls with 

either thinning or thinning and 4-year fire intervals 

(HT4). We only measured acorn production during the 

first half of the study period. Our trees were notably 

slow to respond on these xeric sites. Goodrum and 

others (1971) found that total mast failure never 

occurred during their 20-year study. We observed 

near complete mast failure in 2 of 7 years and low to 

moderate production in 4 years and 1 exceptional year. 

These xeric and nutrient poor oak-pine habitats in 

mountainous terrain such as in the Ouachita Highlands 

may not have the capacity for acorn production, 

especially in drought years, as in their study. Mast 

shortfalls have also been documented in the Ozark 

Plateau region of Arkansas (Segelquist 1974). The 

variability of individual trees in terms of acorn 

production and growth is well noted in the literature 

(Downs and McQuilken 1944, Drake 1991, Goodrum 

and others 1971) and our findings were no different. 

However, with increased diameter growth from 

thinning and burning, perhaps mast production should 

be revisited in a later study.

All nutrient parameters for sampled post oak acorns 

fell close to mean values and within the range of 

values reported in the literature (Short 1976, Halls 

1977). However, moisture content for our samples 

was different according to time since burned. Samples 

three growing seasons postburn were similar to 

samples from unburned control units, and those one 

and two-growing season postburn were lower in 

moisture content. Lower moisture content may have 

some additional nutritional benefit to wildlife as crops 

with lower moisture content have been shown to 

have lower storage loss (from rot) and higher starch 

(carbohydrate) content through time compared to 

items with higher moisture content (Hornick 1992). 

If the same holds true for acorns then acorns should 

remain sound longer and have higher carbohydrate 

content during the late winter period of nutritional 

stress. Whether this is nutritionally significant 

remains to be seen. Acorns are generally very high in 

carbohydrates and are highly digestible, particularly 

those in the white oak group, and thus are an excellent 

energy source in winter (Kirkpatrick and Pekins 2002). 

Energy appears to be more important than protein or 

other nutrients at least for bobwhites (Giuliano and 

others 1996) in winter. Although a slight increase 

(1 percent) in crude protein was noted in acorns for the 

first two growing seasons postburn, that small increase 

may not be of biological significance given that crude 

protein of acorns is generally low compared to other 

foods (Kirkpatrick and Pekins 2002). 

Implications of our fire and thinning treatments 

for landscape implementation of oak savanna and 

woodland restoration suggested fire regimes longer 

than every year because of higher cumulative oak 

mortality from annual burning in low density stands 

(<10 m2

/ha BA). However periodic annual fire may be 

a suitable application in stands above 10 m2

/ha BA for 

maintenance of oak savanna conditions. We found that 

a 3- or 4-year frequency allows for oak regeneration 

to develop into small trees, but the longer interval also 

allows forest development as also reported by Burton 

and others (2010). Therefore a rigid 4-year frequency 

is likely unsuitable for savanna maintenance.

Because oak recruitment was virtually non-existent 

in the annually burned treatments (R. Masters, 

unpublished data), 2-year and 3-year intervals are 

recommended to maintain open woodland or savanna 

conditions. The fire return intervals reported for the 

nearby McCurtain County Wilderness Area across a 

variety of sites ranged from 2.1-5.6 years with a range 

of 1-12 years (Masters and others 1995). Because the 

fire regime was historically variable, we implemented 

a fire regime across the landscape restoration units 

encompassing 1-4 years recognizing that north 

slope hardwoods, riparian corridors, and upland 

drainages associated with ephemeral streams will 

have effectively longer intervals as the understory will 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 85

burn completely only in very dry conditions. With fire 

intervals longer than 4 years, mesic tree species begin 

to invade and change the character of the stands, and 

thus the potential for recurrent surface fire (Burton and 

others 2010).

Forest health issues have been raised particularly 

about densification of oak woodlands and savannas 

and oak decline, aside from the loss of herbaceous 

plants and associated animal species habitats. Oak 

decline is ascribed to various insect and disease agents 

associated with approaching physiological maturity 

(Hyink and Zedaker 1987). Relatively little attention, 

however, is paid to increased tree density through 

time, and thus increasing competition for moisture 

and nutrients, as an untoward influence on disease 

incidence and ecosystem health of fire suppression 

efforts (e.g., Hyink and Zedaker 1987, Oak and others 

1986). 

Fire is an integral process in oak or mixed oak-pine 

systems. Beneficial effects on ecosystem health 

include thinning of trees to reduce moisture and 

nutrient competition, thus increasing drought tolerance 

and lowering incidence of disease in a given stand, and 

for maintaining historic structure and function (Burton 

and others 2010, DeSantis and others 2010). Oak 

savanna and woodland restoration efforts as applied 

on a landscape level on PWMA are similar in site 

location, tree density, and composition to presettlement 

conditions. The essential test to determine the 

success of restoration efforts is the effects on wildlife 

populations. This view of restoration success is too 

often overlooked.

The dramatic response of deer and elk was not 

surprising given that a sporadic source of nutrition 

from acorns was supplemented with a much greater 

and more consistent amount of nutritious forage. 

However, at this point it is not clear if acorn 

production was enhanced, as we had postulated, to the 

point that it offsets that lost from thinning.

Songbirds provide rapid feedback on the effects 

of forest management and re-introduction of fire. 

Because they are closely associated with a particular 

arrangement of habitat structure, they respond 

in relatively short periods of time, and some are 

associated with narrow successional windows created 

by postfire succession in the understory in addition to 

forest canopy cover change (Cox and Widener 2008, 

Masters and others 2002, Wilson and others 1995). 

Woodland-grassland and forest-shrub birds have 

declined precipitously across the southeast United 

States because of fire exclusion and densification of 

forests (Cox and Widener 2008, Wilson and others 

1995). The frequent fire connection is essential for 

woodland grassland birds in order to maintain suitable 

habitat structure (Cox and Widener 2008).

Not withstanding the needs of these groups of birds, 

we were also interested in any deleterious influence 

on forest-shrub and forest interior birds that were 

species of high interest although not species of special 

management concern. It is significant that only three 

species, yellow-billed cuckoo, black & white warbler, 

and chuck-will’s-widow, showed declines over the 16 

years following staged implementation of landscape 

level restoration. Regional trends have a strong 

influence on local populations of birds. Therefore, 

interpretation of results on a given route must be 

interpreted in light of regional trends. Yellow-billed 

cuckoo and chuck-will’s-widow experienced strong 

regional declines from 2004-2007 (Sauer and others 

2011). However, the black & white warbler exhibited 

a stable regional trend during this time period (Sauer 

and others 2011).

Our study has shown that small plot research can 

inform landscape level restoration and management 

through confirmation of the utility of restoration 

targeted thinning and confirmation of fire intervals 

used by land management as compared to 

presettlement landscape structure and fire regime. 

Studies of presettlement landscape characteristics 

such as structure, form, function, and fire chronology 

provide essential data for guiding restoration of 

oak woodlands and savannas as well as for other 

ecosystems. Researchers and land managers would do 

well to explore and learn from this diverse literature.
86 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

ACKNOWLEDGMENTS

Financial support to establish the study area came from 

the Oklahoma Department of Wildlife Conservation, 

Federal Aid in Wildlife Restoration Project W80R-140. 

Later support has come from Oklahoma Department 

of Wildlife Conservation, Oklahoma Department 

of Agriculture, Horticulture and Forestry Services, 

Oklahoma State University, Oklahoma Agricultural 

Experiment Station McIntire-Stennis funds, and 

Tall Timbers Research Station, Wildlife Research 

Endowment. We thank R. Thackston and R. Robinson 

for assistance with establishing this study and with 

initial field data collection. We thank K. Gainey 

for assistance with manuscript preparation and two 

anonymous referees for reviewing the manuscript. 

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The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 91

APPENDIX

List of common and scientific names of plants, bird, and mammal species mentioned in the text and 

figures.

Common Name Scientific Name (authority)

Plants

Big bluestem Andropogon gerardii (Vitman)

Black oak Quercus velutina (Lam.)

Blackberry Rubus spp. 

Blackjack oak Quercus marilandica (Muenchh.)

Bluestem grass Schizachyrium spp., Andropogon spp.

Greenbriar Smilax bona-nox (L.)

Hypoxylon cancer Hypoxylon atropunctatum (Schwein.) Cooke

Indiangrass Sorghastrum nutans (L.) Nash

Little bluestem Schizachyrium scoparium (Michx.) Nash

Loblolly pine Pinus taeda (L.)

Mockernut hickory Carya alba (L.) Nutt.

Muscadine grape Vitus rotundifolia (Michx.)

Panicums Panicum spp., Dicanthelium spp. 

Poison ivy Toxicodendron radicans (L.)

Post oak Quercus stellata (Wangenh.)

Sedges Carex spp., Scleria spp.

Shortleaf pine Pinus echinata (Mill.)

Switchgrass Panicum virgatum (L.)

Tree sparkleberry Vaccinium arboretum (Marshall)

Virginia creeper Parthenocissus quinquefolia (L.) Planch.

Winged sumac Rhus copallinum (L.)

Birds

Bachman’s Sparrow Aimophila aestivalis (Lichtenstein)

Black and White Warbler Mniotilta varia (Linnaeus) 

Blue Grosbeak Guiraca caerulea (Linnaeus) 

Blue-gray Gnatcatcher Polioptila caerulea (Linnaeus)

Chipping Sparrow Spizella passerina (Bechstein)

Chuck-will’s-widow Caprimulgus carolinensis (Gmelin)

Common Yellowthroat Geothlypis trichas (Linnaeus)

Downy Woodpecker Picoides pubescens (Linnaeus)

Eastern Wood Pewee Contopus virens (Linnaeus)

Indigo Bunting Passerina cyanea (Linnaeus)

Mourning Dove Zenaida macroura (Linnaeus)

Northern Bobwhite Colinus virginianus (Linnaeus) 

Pine Warbler Dendroica pinus (Wilson)

Prairie Warbler Dendroica discolor (Vieillot)

Red-cockaded woodpecker Picoides borealis (Vieillot)

Red-eyed Vireo Vireo olivaceus (Linnaeus)

Red-headed Woodpecker Melanerpes erythrocephalus (Linnaeus)

Summer Tanager Piranga rubra (Linnaeus)

Tufted Titmouse Baeolophus bicolor (Linnaeus)

Yellow-billed Cuckoo Coccyzus americanus (Linnaeus)

Yellow-breasted Chat Icteria virens (Linnaeus)

Mammals

Bison Bison bison (Linnaeus)

Rocky Mountain elk Cervus elaphus (Linnaeus)

White-tailed deer Odocoileus virginianus (Zimmermann)
92 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

FIRE-ADAPTED NATURAL COMMUNITIES OF THE OZARK HIGHLANDS 

AT THE TIME OF EUROPEAN SETTLEMENT AND NOW

Paul W. Nelson

Forest Ecologist, Mark Twain National Forest, Supervisors Office, 401 Fairgrounds Road, 

Rolla, Missouri 65401. To contact call 573-341-7433 or email at pwnelson@fs.fed.us.

Abstract.—The Ozark Highlands Plateau of southern Missouri and northern Arkansas 

is home to more than 2,000 vascular plant species and at least 15,000 species of various 

animals of which over 150 are endemic. The Nation’s most significant karst region occurs 

here, boasting the most springs of any state and more than 6,000 caves. Missouri’s Ozark 

biota is sorted into 65 distinctive mappable natural communities. Misconstrued as “oakhickory forest”, analysis of Missouri’s historic vegetation, fire history studies, plant 

adaptations, and responses to fire management reveal that the Ozark’s was a landscape 

dominated by a complex mosaic of fire and topography-mediated grass and forb-rich 

savannas, woodlands, glades, forests, and fens. Much of today’s native Ozark vegetation 

is deceptively out of character for its structure, composition, species richness and former 

landscape patterns due to having suffered the consequences of destructive post-European 

settlement overgrazing, poor farming, fire cessation, and soil loss. Fallacies abound that 

“resilient” Ozark ecosystems will recover, succeed, and migrate in the face of climate 

change and homogenizing vegetation transformation. Monitoring of remnant high quality 

natural communities reveals their susceptibility to irreversible conservative species loss 

and simplification. Managers must understand and distinguish between the achievement 

of true ecological restoration outcomes of high quality habitats over personal/professional 

biases including grazing woodlands, timber production, and singular species emphasis.

BACKGROUND

This paper primarily employs the ecological 

classification and ecosystem restoration approaches 

used by the Missouri Natural Areas Committee. The 

committee is made up of six state and federal agencies 

that have cosigned a Memorandum of Understanding 

to administer a system of natural areas. Natural areas 

by definition are areas of the landscape that protect 

high quality aquatic and terrestrial assemblages of 

plants and animals as they may have existed prior to 

European settlement (Nelson 2010). It is this time 

period that sets the stage for defining and describing 

natural communities and the sequence of European 

settlement factors that have altered and damaged 

Missouri’s historical fire-adapted natural communities. 

The objectives of this paper are:

1. To describe the primary fire-adapted natural 

communities that occurred prior to European 

settlement

2. To list the modern day disturbances that have 

altered their historic patterns 

3. To introduce some misconceptions about 

ecosystem restoration

Nelson (2010) describes natural communities as 

distinct assemblages of native plants, animals, and 

microorganisms that occur in repeatable (mappable) 

patterns across the landscape and through time. These 

assemblages of biota occupy definable physical 

environments, which in turn influence the structure and 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 93

composition of natural communities. In Missouri, 85 

natural communities are described with approximately 

65 occurring in the Ozarks. These natural communities 

fall into broad types including forest, woodland, 

savanna, glade, prairie, wetland, stream bank, cliff, 

and cave. High quality natural communities are 

generally rich in native plant and animal species 

including a host of “conservative species” that are 

sensitive to modern disturbances. Conservative species 

decrease or disappear in ecosystems degraded by 

clearing, plowing, overgrazing, over browsing, and 

fire cessation resulting in a loss of biodiversity. As 

many as 300 to 400 vascular plant species may occur 

in one natural community type. A second attribute of 

high quality natural communities is the abundance 

of flowers, seeds, and biomass cover produced by 

the rich groundcover plant species. In turn, a great 

variety of host specific and other invertebrates inhabit 

this ground layer, interacting as plant pollinators and 

providing food for predators higher in the food chain. 

High integrity natural communities are characterized 

by woody vegetation of variable ages and patterns 

as determined and shaped by the presumed historical 

disturbance regime and climate. This includes 

differences in gap size, blow down, old growth 

character, spacing between trees, and the presence or 

absence of large dead or decaying wood. Ozark natural 

communities were further characterized by variable 

but connected landscape patterns differentiated by the 

distinctive features of a given ecological subsection. 

Those features included topographic expressions, 

bedrock type, drainage patterns, and disturbance 

processes. 

Each natural community type is classified according 

to dominant or characteristic vegetation types, canopy 

height and openness, vegetation layers, rock type, 

age class variation, and disturbance processes. The 

author (and the Missouri Natural Areas Committee) 

recognizes the temporal nature of natural communities 

and the changes brought about by variations in climate 

and other disturbance processes. For the purposes of 

this paper, the Missouri Natural Areas Committee uses 

the pre-European time period as a reference point to 

differentiate the contemporary altered landscape from 

high quality ecosystems prior to their severe, modern 

day disruption (Nelson 2010). 

THE OZARK LANDSCAPE SETTING

The Ozarks ecoregion encompasses nearly 34 million 

acres across the southern one half of Missouri, 

northern Arkansas, and small portions of Oklahoma 

and Illinois. This distinctive biogeographic region of 

southern Missouri and much of northern Arkansas is a 

low structural dome of variably aged rock strata with 

the dome center consisting of the oldest (1.5 billion 

years) igneous rock in the St. Francois Mountains 

(Nigh and Schroeder 2002). This elevated region of 

the central United States along with the Ouachita 

Mountains to the south is the highest elevated region 

of mid-continental North America. A quarter billion 

years of exceptional geologic erosion, wind transport, 

and subterranean karst dissolution has created a 

diversity of landforms that vary in degree of relief, 

dissection, and geologic parent materials. Ozark biota 

are characterized by an unusually high level of species 

disjuncts and endemism with more than 160 species 

endemic to the area. Among the diversity of plants 

and animals, 159 species are endemic, 77 are modal 

(meaning their primary population density exists 

there), 81 are globally rare, and 58 are disjunct. Of this 

number, 32 species are in decline with perhaps a dozen 

extirpated (Ozarks Ecoregional Assessment Team 

2003). 

Differences in landform, soils, and vegetation produce 

16 ecological subsections in the Ozark Highlands of 

Missouri (Nigh and Schroeder 2002). These ecological 

subsections and their geologic, biologic, topographic, 

and historical Native American interactions prior to 

European settlement created mosaics of diverse firemediated prairies, savannas, woodlands, glades, fens, 

and forests. 
94 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

OZARK VEGETATION SHAPED BY

HISTORIC FIRE

Native Americans played a role in shaping changes 

across the Ozarks for as long as 12,500 years (Ray and 

others1998). When Europeans first arrived in Missouri, 

high integrity ecosystems had evolved with adaptations 

to disturbance processes. Nelson (2010) provides an 

in-depth accounting of the effects of Native American 

habitation ranging from the landscape application of 

fire to agriculture and settlement. The environment 

was radically different during the period between 

8,500 and 4,500 years before present (YBP) when 

drought-adapted species expanded their range, and 

grasslands (among woodlands) dominated. Following 

4,500 YBP, essentially modern vegetation and faunal 

patterns appeared. Extensive evidence of past fires 

started by Native Americans abound. Guyette and Dey 

(2000) and Guyette and others (2006) provide accurate 

records in the modeling of historic fires across North 

America and the relationship between historic human 

habitation, topographic relief, and climate. Abrams and 

Nowacki (2008) concluded that Missouri’s subhumid 

Midwestern climate would not support prairie, 

savanna, and open woodland without the influence 

of Native Americans broadcasting fire over North 

America the past 5,000 years. Thus, the 65 distinct 

natural communities of the Missouri Ozarks were 

shaped by centuries of variable fire regimes. 

THE OZARKS VEGETATION-DIVERSE 

ASSEMBLAGES OF FIRE-ADAPTED 

NATURAL COMMUNITIES, NOT 

OAK-HICKORY FORESTS

The mindset of early natural resource management 

by state and federal agencies was shaped throughout 

the early 1900s by the notion that fire was detrimental 

for plants and wildlife. Dr. Julian Steyermark who 

wrote “Flora of Missouri” (1963) and “Vegetational 

History of the Ozark Forest” (1959) falsely shaped 

this mindset by furthering the theory that the Ozarks 

was primarily a forested landscape succeeding from 

an earlier open savanna-woodland vegetation type. He 

attributed the “unnatural succession” of former open 

grass-dominated Ozark woodlands and savannas to 

the eventual mesification effects of a warmer-wetter 

climate following the xerothermic period (a postglacial 

interval of a warmer, drier climate that occurred 

4,000-5,000 years ago). Dr. Steyermark never made 

the connection between the role of Native Americans 

in their broadcasting fire across all of North America 

and its profound effects in shaping fire-adapted natural 

communities. His reports to the Mark Twain National 

Forest and state foresters in the mid 1950s furthered 

the notion that post-European annual burning of the 

Ozarks was destructive to native flora. Later, natural 

features inventories conducted by the Missouri Natural 

Areas Committee (listed in Nelson 2010) would 

demonstrate that it was the combination of open-range 

overgrazing coupled with annual burning of the now 

logged over Ozarks that led to the widespread loss of 

the once rich grass-forb groundcover associated with 

ancient open woodlands, savannas, and glades. 

Many early explorers in Missouri chronicled numerous 

accounts of periodic fires and their influence in 

shaping the open, park-like character of the Ozarks. 

Schoolcraft (1819) observed, “The Ozarks...covered 

with a very uniform growth of black oaks and post 

oaks, in the summer season by a vigorous growth 

of wild grasses, flowers and vines.” Louis Houck 

(1908) states, “Open woods and a growth of wild 

prairie grasses and flowers filling the broad spaces 

between the trees. All the forests were free from 

undergrowth, and open and park like in appearance.” 

George Swallow (1859) writes, “This growth is not 

due to the poverty of the soil but to the fires which 

have annually overrun this country since the earliest 

dates of the Indian traditions...” Table 1 shows the 

transitional continuum and breaking points between 

the primary fire-adapted natural communities in the 

Ozark Highlands. 

Prairie

While over 13 million acres of prairie occurred across 

Missouri, its presence in the Ozarks is restricted 

primarily to the Central Plateau Subsection. Prairies 

were essentially treeless, primarily dominated by a 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 95

Table 1.—The Prairie, Savanna, Woodland to Forest Continuum for the Ozark Highlands

Attributes Mesic Forest

Dry-mesic 

Forest

Dry-mesic 

Woodland

Dry (open) 

Woodland and 

Flatwood Savanna

Prairie and 

Glade

Vegetation 

Layers

Multiple >4 Multiple >3 2 to 3 2 to 3 2 1

Age Classes Variable - 

uneven age

Variable - 

uneven and 

even

Uneven/even Multiple even 

age

Multiple even 

age

Not 

applicable

Tree Form/

Height

Narrow crowns, 

clean trunks 90+

Narrow 

crowns, clean 

trunks 70-90

Somewhat 

spreading 

crowns, clean 

trunks 60- 90

Spreading 

crowns and 

lower branches 

20-60

Wide-spreading 

crowns, 20-60

Not 

applicable

Canopy 

Closure

90-100 90-100 80+ 30-80 10-30 0-10

% Understory 

Cover

50-100 dense 50-100 dense 30-50 patchy 10-30 

scattered

5-10 sparse 0-10

Ground Layer 

Cover

Dense in spring, 

patchy to sparse 

by mid-summer

Dense to 

patchy in 

spring, patchy 

to sparse by 

mid-summer

Dense to patchy 

in spring, patchy 

to dense by midsummer

Patchy to 

dense all 

season

Dense all 

season

Dense all 

season

Ground Layer 

Plants

Rich diversity 

of spring 

ephemerals, 

and ferns; few 

summer/fall forbs

Moderate to 

low diversity 

of spring 

ephemerals, 

and ferns, few 

summer/fall 

forbs

Moderate to 

low diversity 

of spring 

ephemerals, and 

ferns; abundant 

C3 grasses, 

sedges, and 

summer/fall forbs

C3 and C4 

grasses, 

sedges, 

diversity of 

forbs all season

C4 grasses, 

sedges, 

diversity of 

forbs all season

C4 grasses, 

sedges, 

diversity 

of forbs all 

season

Topography 

and Landform

Protected 

valleys, ravines, 

bluff bases, 

lower slopes of 

northerly aspects, 

fire shadow areas

Mid and 

upper slopes 

of northerly 

aspects, 

ravines, fire 

shadow areas

Mid and 

upper slopes 

of southerly 

aspects, 

fire prone 

landscapes

Steep upper 

slopes of 

southerly 

aspects, 

narrow ridges, 

broad ridges, 

fire prone 

landscapes

Level to 

gently rolling 

topography, 

steep loess 

hills, broad 

ridges

Level to 

gently rolling 

plains, steep 

loess hills, 

broad ridges; 

steep sw 

slopes-glades

Soils Deep (>3’) loams, 

nutrient rich, high 

organic matter

Moderate 

depth (24-36”) 

silt loams, 

moderate 

organic matter

Moderate depth 

(20-36”) silt 

loams, moderate 

organic matter

Shallow 

depth (<20”), 

droughty, often 

rocky and or 

nutrient poor

Wide range 

of soil types 

from shallow to 

deep, variably 

rocky

Wide range 

of soil types 

from shallow 

to deep, 

variably rocky

Fire Regime Very infrequent 

(30+ years), 

and/or low 

intensity fires

Infrequent 

(20+ years), 

and/or low 

intensity fires

Low to moderate 

intensity fires 

every 3 to 15 

years

Low to 

moderate 

intensity fires 

every 3 to 5 

years

Moderate 

intensity fires 

every 1 to 3 

years

Moderate to 

high intensity 

fires every 1 

to 3 years

Dominant 

Trees

Red oak, sugar 

maple, ash, 

basswood, walnut

White, red, 

and black 

oaks, hickories

White, black, 

scarlet, 

chinkapin 

oaks, hickories, 

shortleaf pine

Post, blackjack, 

chinkapin, bur, 

white oak, pine

Bur, 

chinquapin, 

swamp oak, 

white oak

Shrubs

Basal Area 

# mature trees/

acre

70-80 

>30

70-80 

30

60-80 

20-30

30-60 

<10

<30 

<5

<10 

<2
96 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

mix of grasses, forbs, and low shrubs. The often level 

to gently undulating plateau was conducive to rapidly 

spreading, intense fires occurring as often as every 2-3

years, thus limiting tree growth. Only one occurrence 

of a remnant Ozark prairie exists today.

Savanna

Some 6.5 million acres of savanna occurred across 

the Ozarks, primarily on the Springfield Plateau and 

Central Plateau Subsections. Savannas were Serengetilike landscapes of widely spaced, orchard-like trees 

of variable age classes ranging from old growth trees 

to islands and scatterings of oak regeneration. Tall 

grass species and forbs dominated the groundcover. 

Principle tree species included post oak, white oak 

and bur oak (scientific names listed in Appendix). 

The greater undulation and fragmentation of plateaus 

and plains by streams and rivers decreased the 

effects of rapidly spreading fires, thus leading to the 

increase in tree species, particularly post and white 

oak. Unfortunately, very little savanna remains in 

the Ozarks, having succumbed to exotic cool season 

grasslands used for pasture. 

Woodland

By far the most diverse, 13 woodland types occur 

across the Ozark Highlands. This was the predominant 

natural community type with at least 11 million 

acres occurring. Fortunately, this is also the most 

recoverable, restorable natural community in the 

Ozarks with the potential of restoring 6 million 

acres (Spencer and others 1992). Woodland types 

often have a variable canopy openness ranging 

from 30 to 90 percent canopy cover depending on 

restoration objectives and fire effects. Important 

woodland types include post oak-black oak 

woodlands, mixed oak woodlands, shortleaf pinebluestem woodlands, chinquapin oak woodlands, and 

bottomland woodlands. Many examples of woodland 

restoration abound across the Ozark Highlands as 

agencies and conservation groups continue actively 

restoring landscapes. The Central Hardwoods Joint 

Venture considers woodlands, particularly their early 

seral, grass-dominated patterns, vital toward the 

recovery of early seral bird species including bluegray gnatcatcher, indigo bunting, prairie warbler, 

chipping sparrow, field sparrow, and bobwhite quail. 

Vaughn (personal communication) demonstrated 

the importance of the attainment of quality restored 

woodland vegetation structure and the recovery of 

diverse bird communities. 

Forests

In the general absence of fire, trees formed a closed 

canopy interspersed with multi-layered shade-tolerant 

subcanopy trees, shrubs, vines, and scattered herbs. 

Trees attained their greatest height, forced to grow 

high, often competing for light in forest gaps. Ground 

flora often consisted of a rich assemblage of fireintolerant spring ephemeral forbs, shade-tolerant 

sedges, grasses, and ferns. Much of Missouri’s 

woodland landscape was regarded as “forest” (Braun 

1950, Steyermark 1959) when in fact the presentday closed, dense canopy is an artifact of domestic 

livestock overgrazing and fire suppression (Pyne 

1982). In the Ozarks, forest is confined to the most 

rugged, deeply dissected hills and breaks of the 

Current River and Eleven Point River watersheds with 

lesser amounts in protected valley coves, large river 

floodplains, and the base of bluffs elsewhere (Nigh 

2002). 

Glades

Five glade natural communities occur in the Ozark 

Highlands. Glades are essentially treeless shallow 

bedrock openings in woodlands ranging in size from 

one-half acre to 1,500 acres. Despite shallow bedrock, 

as many as 400 vascular plant species inhabit glades, 

including several endemic and restricted species. The 

extremely dry, desert-like condition of glades attract 

animal species with a primary distribution in the more 

arid southwestern United States including the eastern 

collared lizard, flat-headed snake, southern coal 

skink, tarantula, and greater roadrunner. The Ozark 

Highlands contain the highest number and acreage 

of glades in Eastern North America (Nelson and 

Ladd 1983). Approximate glade acreages and types, 

according to Nelson and Ladd, include: 200 acres of 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 97

chert glades (Springfield Plateau only); 5,000 acres of 

limestone glades (Springfield Plateau); 12,000 acres 

igneous glades (St. Francois Mountains); and 200,000 

acres dolomite glades (located throughout the Ozark 

Highlands but greatest abundance in White River 

Hills, Osage River Hills, and Inner Ozark Border). 

Guyette (1982) estimated historical fire to occur every 

3-4 years on glades in southwest Missouri. 

NATURAL COMMUNITY PATTERNS 

ACROSS THE OZARK HIGHLANDS

Early interpretations of the falsely applied concept of 

“Oak Hickory Forest” portrayed the Ozarks as covered 

primarily in forest and dominated by mixtures of oak 

and hickory. Modern interpretations now cite several 

valuable sources. The Missouri Historic Vegetation 

Survey, Geographic Resources Center, University of 

Missouri, Columbia has attributed the characteristics 

of over 400,000 individual trees recorded by 

Government Land Office early land surveyors during 

the early to mid 1800s. The Geographic Resources 

Center has queried these data across a variety of 

stratified applications, including relative importance 

values for all tree species by ecological subsection, 

the relative openness of the tree canopy, and tree 

associations. Results reveal that the Ozark Highlands 

contained over 25 different tree associations, many of 

them attributed to the influences of fire, topography, 

and geology (Batek and others 1999). Oaks were 

important but so was shortleaf pine. Hickory was not 

an important (dominant) tree species. When modeling 

witness tree structure and openness (a measure of 

distance and diameter from section corners and section 

lines), much of the Ozarks was open in character, thus 

confirming the historical presence of savanna and open 

woodlands. Again, forest was confined to dissected 

river breaks. Table 2 shows the most important oakdominated natural communities, landforms, and 

estimated fire interval. Table 3 lists the oak species 

known to occur in the Ozark Highlands and their 

optimal natural community (Nelson 2010).

THE PRESENT-DAY OZARK

HIGHLANDS: OUT-OF-CHARACTER 

AND DEGRADED

Biotic homogenization (McKinney and Lockwood 

1999) happens when native localized ecosystems are 

assimilated by widespread exotic or weedy native 

species, thereby increasing their compositional 

similarity. Biotic distinctiveness gradually dissolves. 

An example might be the replacement of 300 native 

plant species associated with a high quality, preEuropean glade by 40 native species and dozens of 

exotics within the same landscape area. Present day 

homogenization processes include: 

• Importation of exotic plants for agriculture, 

wildlife plantings, and landscaping/gardening

• Globalized transport of exotic pets (legal and 

illegal) along with accidental insect/diseases

Communities Landform Fire Interval

Post oak bluestem flatwoods Gentle fragipan plains and ridges Fire 3-5 years

Post oak and bur oak savanna Gentle plains Fire 2-4 years

Chinquapin oak bluestem woodland Dolomite slopes and hills Fire 3-10 years

White, black, and blackjack oak woodlands Chert plains Fire 3-5 years

Blackjack oak xeric woodland Igneous rock outcrops Fire 5-15 years

Post and chinquapin oak-smoketree glades Dolomite bedrock of dissected hills Fire 3-4 years

White oak-pine woodlands Dissected hills and breaks Fire 10-50 years

Mixed bottomland oak forests Larger river floodplains Fire 25-50 years

White, northern red oak/sugar maple forest Deep coves and valleys Fire 15-30 years

Table 2.—Important oak-dominated natural communities of the Ozarks, their landform and presumed 

fire interval
98 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Open Closed Upland Bottomland

Oak species Savanna Woodland Woodland Flatwoods Forest Forest Glade

Blackjack oak x

Black oak x x

Bur oak x x

Cherrybark oak x x

Dwarf chestnut oak x

Chinquapin oak x x

Nuttall’s oak x

Overcup oak x

Pin oak x

Post oak x x x x

Red, northern oak x x

Red, southern oak x x

Scarlet oak x X X

Schneck’s oak x

Shingle oak x

Shumard oak x

Swamp white oak x

Table 3.—List of Missouri oak species and their optimal natural community type (Nelson 2010)

• Land fragmentation and parcelization

• Overhunting and wildlife persecution

• Agriculture

• Fire suppression

• Overgrazing (past and present)

• Modern developments; housing, reservoirs, 

roads, industry

• Variations in management philosophies

The consequences of these processes have impacted 

the Ozark Highlands in the following primary ways:

1. Overgrazing has decimated the once lush mantle 

of rich grass/forb groundcover and resulted in 

soil loss-erosion of gravel into Ozark streams 

(Smith 2003).

2. Soil erosion has exasperated watershed 

hydrology degradation with runoff increasing 

(even in dense, overstocked canopies) and 

subsequent landscape dehydration. 

 3. Loss of groundcover species has dramatically 

reduced or eliminated flower and seed 

production, thereby decreasing the abundance 

of insect populations important for foraging by 

birds and bats (Beilmann and Brenner 1951).

4. Fire suppression coupled with grazing and 

logging has led to dense overstocking of 

increasingly undesirable tree species (Ladd 

1991, McCarty 1998, Nigh 1992).

5. Loss of topsoil has changed soil chemistry and 

dehydrated the landscape causing increased 

runoff and decreased spring flows.

6. Black and scarlet oak (preferred species for 

timber markets) have increased, but so have oak 

decline, oak wilt, and oak borer diseases (Law 

and others 2002, USDA 2005). 

7. Exotic species are on the increase in especially 

vulnerable damaged woodlands. Of Missouri’s 

800 introduced nonnative plant species, 32 

are recognized as invasive on the Mark Twain 

National Forest (USDA 2012). Feral hogs are 

increasing across the Ozarks.

8. Certain native species populations are out of 

balance including invasive red cedar on glades 

and isolated occurrences of heavy white-tailed 

deer overbrowsing. Rooney (2004) attributed 

biotic simplification of 62 forests in Wisconsin 

to the keystone effects of too many deer. 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 99

9. There is an increase in the listing of species 

of conservation concern, particularly those 

once associated with fire-adapted natural 

communities.

Over 75 percent of Missouri’s 44 million acres of 

historic vegetation is completely transformed; most 

destroyed. The remaining 25 percent is fragmented, 

out-of-character, damaged, fire-suppressed, and 

subject to exotic species invasion. Of this percentage, 

the following acreages of various oak-dominated 

natural communities are estimated to be restorable 

to high quality natural community standards on the 

Mark Twain National Forest: 4,000 acres of post oak 

bluestem savanna; 15,000 acres post oak-chinquapin 

oak dolomite glade and woodland; 2,000 acres post 

oak igneous glade; and 150,000 acres of various oak 

and pine woodland types. The most threatened oak 

systems across the Ozark Highlands include mixed 

oak bottomland forests with few high quality examples 

occurring anywhere. 

MISCONCEPTIONS OF ECOSYSTEM 

SUCCESSION AND MIGRATION

The old botanical theories of plant succession, species 

migrations, and reaccrual of species-rich ecosystems 

on the move in the face of climate change are not 

going to operate effectively, at least in the Midwest. 

Rooney (2004) and others observed that in the face 

of changing vegetation structure and patterns, species 

richness declines and there’s no corresponding accrual 

of new species adapted to the different environment. 

We do not have any examples of an unmanaged 

savanna, woodland, or prairie that, when left to its 

own devices, has recovered or succeeded to an equally 

species rich ecosystem. Also a myth is the old concept 

that natural communities will migrate or succeed in 

response to shifts in climate (Steyermark 1959). 

CONSERVATION STRATEGIES

The Nature Conservancy’s Ozark Ecoregional 

Conservation Assessment (Ozarks Ecoregional 

Assessment Team 2003) has identified high priority 

portfolio areas within the Ozark Highlands to 

concentrate protection/management strategies. The 

Mark Twain National Forest used this assessment to 

design and delineate 19 management areas across 

distinctive ecological regions of the Mark Twain, 

emphasizing restoration of ecosystems. The 2005 

Forest Management Plan for the Mark Twain identified 

objectives to restoration more than 150,000 acres to 

desired conditions for healthy natural communities. 

The Mark Twain has also increased prescribed burning 

to 40,000 acres annually. At the 2009 Missouri Natural 

Resources Conference, a multi-agency workgroup 

concluded that the best conservation strategy in 

response to climate change was to make ecosystems 

more resilient by restoring their historical condition 

and maintaining or emulating critical disturbance 

processes, especially fire. 

CONCLUSIONS

In conclusion, much of the Ozark landscape was 

mantled in a park-like growth of mixed oak and pine 

interspersed with a nearly continuous ground cover 

of deep rooted perennial grasses and forbs. Most 

vegetation composition and structure directly reflected 

the effects of variable fire regimes, excepting the most 

deeply dissected river breaks. Open range overgrazing, 

soil erosion, poor farming, and fire suppression have 

obliterated the historic character of former firemediated woodlands, savannas, and glades resulting in 

population shifts for many plant and animal species. 

Hands-off management will result in declines in 

species richness for landscapes once dominated by 

fire-adapted ecosystems due to the homogenization 

process. Threats abound. To make matters worse, 

the preservation of biodiversity through ecosystem 

restoration is not a primary management goal of most 

land managing agencies. Managers differ in their 

land management aspirations, personal interests, 

philosophies, and management styles. 

We have the resources: people, money, time. We 

have strategies: state park resource stewardship plans 
100 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

and policies, Missouri Department of Conservation 

Comprehensive Wildlife Strategy, Mark Twain 

National Forest Plan ecosystem restoration objectives, 

and The Nature Conservancy’s Ozark Ecoregional 

Conservation Assessment. But the statewide scorecard 

for ecosystem restoration work accomplished is far 

from achieving its objectives. Resistance prevails in 

many forms: budget cuts, layoffs, other priorities, 

manager philosophies, changing leadership, and 

government agency decentralization. 

Perhaps toughest of all is our not accepting that 

sensitive plant and animal populations and quality 

ecosystems will in many places fall victim to the 

homogenization process. Protecting ecosystems is 

time consuming, expensive, and requires a constant 

dedicated commitment. This commitment requires that 

we institutionalize the idea of ecosystem restoration as 

a primary driver behind what land managing agencies 

and private nature organizations do. But changing 

politics, new leaders with their own aspirations, and 

the eventual “retirement” of those with passion and 

initiative to advocate make this extremely challenging. 

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The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
102 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Appendix

List of scientific plant names (Yatskievych and Turner 1990) for cited common plant names.

Common name Scientific name

Blackjack oak Quercus marilandica

Black oak Quercus velutina

Bluestem Andropogon species

Bur oak Quercus macrocarpa

Cherrybark oak Quercus pagoda

Dwarf chestnut oak Quercus prinoides

Chinquapin oak Quercus muehlenbergii

Nuttal oak Quercus texana

Overcup oak Quercus lyrata

Pin oak Quercus palustris

Common name Scientific name

Post oak Quercus stellata

Northern red oak Quercus rubra

Scarlet oak Quercus coccinea

Schneck’s oak Quercus schumardii var. schneckii

Schumard’s oak Quercus schumardii

Shingle oak Quercus imbricaria

Shortleaf pine Pinus echinata

Smoketree Cotinus obovatus

Sugar maple Acer saccharum 

Swamp white oak Quercus bicolor
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 103

Fire Chronology and Windstorm Effects on Persistence 

of a Disjunct Oak-Shortleaf Pine Community

Michael D. Jones and Marlin L. Bowles

Research Associate (MDJ), The Morton Arboretum, and Christopher B. Burke Engineering, Ltd.; 

Plant Conservation Biologist (MLB), The Morton Arboretum, 4100 Illinois Rt. 53, Lisle, IL 60532. 

MLB is corresponding author: to contact, call 630-719-2422 or e-mail at mbowles@mortonarb.org.

Abstract.—We investigated effects of a human-altered fire regime and wind storms on 

persistence of disjunct oak-shortleaf pine vegetation occurring along 5.5 km of xeric 

habitat on the east bluffs of the Mississippi River in Union County, IL. In 2009, we 

resampled vegetation transects established in seven stands in 1954 and obtained 26 cross 

sections containing fire scars from pines downed by windstorms in 2008 and 2009. These 

scars revealed 81 years with fires between 1767-1991. Only presettlement fire years 

corresponded with drought conditions indicated by the Palmer Drought Severity Index. 

After settlement, fire return intervals measured within stands increased significantly from 

4.55 years during the prelogging era (1825-1875) to 8.19 years during the postlogging 

era (after 1935). After 1975, only one wildfire and two of three management fires were 

detected. Pine recruitment and the percentage of scarred trees, a proxy for fire intensity, 

peaked during the prelogging era when both pine and oak recruitment were also 

positively correlated with fire frequency. Shortleaf pine (Pinus echinata Mill.), black oak 

(Quercus velutina Lam.), and post oak (Quercus stellate Wangenh.) were codominant 

in 1954, but by 2008, pine had become subdominant to black oak, and post oak had 

declined significantly. The 2008-2009 windstorms apparently compensated for recent fire 

exclusion by selective removal of black oak, allowing pine to regain codominance. At this 

site, longevity of shortleaf pine coupled with periodic canopy disturbance and favorable 

fire history appear to have been critical factors maintaining this species in optimum xeric 

habitat. However, unless fire processes are restored, post oak and other shade-intolerant 

species may disappear, and shade-tolerant woody species recently established in the 

understory may further influence future canopy composition. 

INTRODUCTION

Fire and windstorms were two of the most important 

disturbance processes affecting composition and 

structure of presettlement forests (e.g., Frelich and 

Lorimer 1991, Peterson and Pickett 1995, Schulte 

and Mladenoff 2005). Postsettlement fire suppression 

has significantly altered oak forests by reducing oak 

regeneration and allowing establishment of fireintolerant woody vegetation; however, this effect 

may be moderated on drier habitats (Abrams 1992). 

As a result, understanding how human-altered fire 

regimes and their interactions with other disturbances 

affect long-term vegetation change is critical for 

management of disturbance-dependent woody 

plant communities. To resolve this need, managers 

often seek information on fire history dynamics and 

reference stand conditions to develop management 

and restoration goals (Stambaugh and Guyette 

2006, Swetnam and others 1999). Fire chronologies 

determined from tree rings and fire scars can reveal 

historic fire regimes that have maintained firedependent woody plant communities and can help 

set management strategies to maintain this vegetation 

(Wolf 2004). For example, Midwest fire chronologies 
104 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

for oaks have revealed comparatively long fire return 

intervals associated with landscape-scale fires before 

and during early settlement, followed by a shift toward 

more localized fire occurrences and fire suppression 

(reviewed in McClain and others 2010). Likewise, in 

the Missouri Ozarks, shortleaf pine (see Appendix I for 

nomenclature and common names) fire scars indicate 

that presettlement fires occurred during years of 

extreme drought, while more frequent postsettlement 

fires, as well as fire protection, mask the influence of 

drought (Engbring and others 2008, Stambaugh and 

Guyette 2006). 

Severe windstorms alter stand structure by reducing 

basal area and increasing canopy openness (Hanson 

and Lorimer 2007). They range from narrow tornado 

paths or downbursts to wide-scale straight-line winds 

or derechos (Peterson 2000). Impacts correlate with 

wind speed and vulnerability due to topographic relief 

and range in scale from small gaps that are captured 

by advance regeneration of shade-tolerant species to 

stand-wide disturbances that may reset or advance 

successional stages, depending upon understory 

vegetation (Arevolo and others 2000, Canham and 

others 2000, Dunn and others 1993, Peterson 2000, 

Peterson and Pickett 1995, Van Couwenberghe and 

others 2010). Canopy disturbance return times may 

occur within the life span of a tree cohort in northern 

hardwood forests (Frelich and Lorimer 1991) as well 

as in the Missouri Ozark forests (Rebertus and Meier 

2001). Under such disturbance regimes, variability in 

canopy species susceptibility to windthrow, as well as 

storm season, can determine their relative abundance 

in stand composition (Arevalo and others 2000, 

Fumiko and others 2006, Peterson 2000). 

In this paper, we develop a fire chronology for disjunct 

oak-shortleaf pine vegetation in southwest Illinois. 

We correlate oak and pine recruitment with fire 

frequency and compare long-term vegetation change 

between 1954-2008 with short term change following 

windstorms in 2008 and in 2009. Our goal was to 

understand long-term vegetation change in relation 

to exogenous disturbance processes and to provide 

management recommendations to help sustain this 

vegetation. We asked the following research questions: 

1) What are the chronology and characteristics of 

fire, and have they changed during presettlement, 

prelogging (1825-1975), logging (1876-1935), and 

postlogging eras? 

2) How have pine and oak recruitment interacted 

with fire history over time? 

3) How have canopy and sub-canopy vegetation 

structure and composition changed since 1954? 

4) How did windstorms alter canopy structure and 

affect species persistence? 

Because of its fire-dependence, we expected that 

pine dominance and reproduction would decline with 

reduced fire frequency, but that this effect would be 

moderated by xeric habitat conditions.

Study Species and Study Area

Shortleaf pine is characteristic of the fire-adapted 

vegetation of the Missouri Ozark Plateau, which 

extends into Illinois along 5.5 km of southwest 

facing limestone bluffs of the Mississippi River at the 

LaRue-Pine Hills Forest Service Research Natural 

Area, Union County, IL (Fig. 1). We hereafter refer 

to the study area as Pine Hills. Shortleaf pine stands 

occupy cherty soils on convex slopes dissected by 

ravines; this xeric habitat averages 57 percent slope, 

with 21 percent canopy openness, 79 percent ground 

cover by litter, and 21 percent exposed mineral soil or 

moss (Jones and Bowles 2010). Shortleaf pines were 

recorded at Pine Hills by the U.S. Public Land Survey 

in 1810 and were sampled by Shake (1956), Suchecki 

(1987), and Jones (2003). In a dendrochronological 

analysis of shortleaf pine tree cores from Pine Hills, 

Jones (2003) indicated that most of the older trees 

established following major disturbance in 1811-12 

and attributed episodic releases in the 1900s to tree 

harvest, natural canopy disturbance, and favorable 

precipitation. Both Suchecki (1987) and Jones (2003) 

projected the shortleaf pine population to decline with 

continued fire-protection. Concern for shortleaf pine 

population viability prompted this investigation (Jones 

and Bowles 2010). 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 105

Figure 1.—Distribution of shortleaf pine in southeastern 

North America, indicated by shading. Source: (http://esp.

cr.usgs.gov/data/atlas/little/). Arrow indicates location 

(circled) of disjunct stands at Pine Hills. 

Variation in fire frequency is critical for maintenance 

of shortleaf pine. In Missouri, pine seedlings establish 

with 1-4 year fire return intervals but require 8-15 year 

fire-free intervals for survival (Stambaugh and Muzika 

2007). Adult pines are fire-resistant, but record fires 

by developing characteristic callus tissue over injured 

cambium, allowing development of fire chronologies 

(e.g., Stambaugh and Guyette 2006). Shortleaf pine 

occurs with black oak, post oak, and blackjack oak at 

Pine Hills, as well as in dry forests and savannas in the 

Missouri Ozarks (Kabrick and others 2004). Post oak, 

a member of the white oak group, is shade intolerant 

(Stransky 1990) and fire tolerant (Johnson and Risser 

1975). It occupies fire-maintained savanna and 

woodland in the Cross Timbers (Stambaugh and others 

2009) and appears to be declining in southern Illinois 

due to succession following fire protection (McClain 

at al. 2010). Blackjack oak, a member of the black 

oak group, also tends to be shade intolerant and may 

occupy an earlier-successional niche than post oak 

(DeSantis and others 2010, Fumiko and others 2006). 

European settlement began at Pine Hills during the 

1820s, followed by the initiation of a logging era in the 

mid 1870s, and acquisition as a Forest Service natural 

area between 1934-1937. The 1908 Union County plat 

book shows five saw mills within 1 mile of Pine Hills 

and six property owners of the seven shortleaf pine 

stands sampled for this study. The 1929 county plat 

indicates that ownership of these stands was halved 

within 21 years. Annual fall fires in the late 1800s and 

early 1900s reportedly did little damage to large trees 

at Pine Hills (Krause 1985). Nevertheless, concern for 

damage from frequent forest fires in this area lead to 

increasingly greater fire protection in southern Illinois 

(Miller 1920), thereby reducing the extent of fire 

coverage. For example, although an average of one fire 

per year was reported from the Pine Hills area between 

1936 and 1968, they occurred mostly along roads and 

railroads (Suchecki 1987). The Shawnee National 

Forest conducted prescribed burns in 1989, 1991, and 

1993. 

Seven shortleaf pine stands at Pine Hills sampled 

in 1954 by Shake (1956) established that canopy 

importance was shared by shortleaf pine, post oak, 

black oak, and blackjack oak, with Vaccinnium and 

Rhododendron species in the shrub layer. In 2009, we 

resampled transects mapped by Shake (1956). This 

sampling followed 2008 and 2009 windstorms that 

downed both pine and oak canopy trees. Most pines 

were uprooted, while oaks were broken off near their 

bases. The 2008 storm may have been 80-130 km/hr 

straight-line winds that were associated with the 5-6 

February Super Tuesday Tornado outbreak (CIMSS 

2008). The 2009 storm was a cyclonic derecho with 

peak 145-160 km/hr winds that crossed eastern 

Missouri and southern Illinois on 8 May (Brown 2009, 

CIMSS 2009). The 2009 storm had far greater impact 

on Pine Hills than did the 2008 storm (M. Jones, 

personal observation). 
106 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

METHODS

Data Collection and Processing

To develop a fire chronology, we used a chain saw 

to obtain 58 cross sections from the bases of pines 

downed by windstorms and from previously cut pine 

stumps. Downed pines were unavailable in one stand. 

We also extracted cores to pith from 71 standing 

shortleaf pine and 28 oaks representing 10 cm size 

classes in sampling plots. All samples were sanded 

with progressively finer grades of sandpaper (1200 

minimum grit) to reveal annual rings and fire scars. 

Twenty-six of the cross sections contained 113 fire 

scars and were used to develop a stand fire chronology. 

Following Stambaugh and Guyette (2006), a radius 

of each cross section with the least variability due to 

fire scarring was used for measurement, and plots of 

ring-width series were used for visual cross-dating 

of “signature years” and for locating missing or false 

rings. Once dating was completed, series accuracy was 

verified on the COFECHA program (Grissino-Mayer 

2001a) and combined into a master stand chronology 

represented by a standardized ring-width index using 

the ARSTAN program (http://www.ldeo.columbia.

edu/res/fac/trl/public/publicSoftware.html). FHX2 

software (Grissino-Meyer 2001b) was used to graph 

fire scars, and to calculate fire intervals for each series, 

the percentage of scarred trees for each year of a fire 

occurrence, and Jaccard and Yule similarity indices 

of fire synchroneity among stands. Linear distances 

among stand midpoints were measured at a horizontal 

scale on a 7.5’ USGS quadrangle map and ranged from 

0.25-5 km, averaging 1.93 km in a pair-wise matrix. 

Transect locations were mapped by Shake (1956) on 

the Wolf Lake, Illinois 7.5’ USGS quadrangle. These 

transects were digitized onto a digital elevation model 

of the Wolf Lake quadrangle, from which Global 

Positioning System (GPS) positions were retrieved 

for field locations. The initial small mapping scale 

prevented precise relocation of transects, and our data 

represent random samples of stands over time. We 

sampled trees using the original point-center-quarter 

(PCQ) method (N = 210 points), as well as 0.025 ha 

tree plots (N = 56) in which were nested 0.001 ha 

sapling and 1-m2

 juvenile plots. PCQ tree sampling 

included the identity and diameter of the nearest tree 

(>10 cm d.b.h.) in each quadrant, including both 

standing trees and those toppled by the 2008 and 

2009 windstorms. The nearest live saplings (2.54-10 

cm d.b.h.) were also recorded in each quadrant. Plot 

sampling included trees >10 cm d.b.h. in 0.025 ha 

plots, saplings >1 m high and > 2.54-10 cm d.b.h. in 

0.001 ha plots, and juvenile trees <1 m high in 1-m2

plots. All windthrown trees originating within sample 

plots were sampled to reconstruct pre-storm (2008) 

stand structures. Following Shake (1956), PCQ data 

were used to calculate relative density and relative 

basal area (BA) for 2.5-25.4 and >25.4 d.b.h. size 

classes. Pre- and post-storm plot samples were used 

to calculate basal area and dominance (relative basal 

area) for each stand. Average 2008-2009 density was 

also calculated for trees, saplings, and juvenile tree 

species.

Statistical Procedures

What are the chronology and characteristics of 

fire, and have they changed during presettlement, 

prelogging, logging, and postlogging eras? 

Superposed Epoch Analyses (SEA) was used on FHX2 

software (Grissino-Meyer 2001a) to test whether fire 

years were associated with years of extreme drought 

during the presettlement, prelogging, logging, and 

postlogging eras. Proxy climate data were Palmer 

Drought Severity Indices (PDSI) from Grid 112 for 

southeast Missouri (Cook and others 2004); data were 

bootstrapped for 1000 simulations to derive 99 percent 

and 95 percent confidence intervals for normal drought 

conditions and were compared for each of the 5 years 

proceeding and 4 years following the year assigned 

to a fire scar. We used regression analysis to test 

whether stand ring-width indices had significant linear 

relationships with local 1901-2009 precipitation and 

temperatures in years t and t-1 for fall, winter, spring, 

and summer months. Data were obtained for Anna, IL 

from the Illinois State Climatologist Office and Illinois 

State Water Survey (Illinois State Water Survey 2012).
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 107

A Kruskal-Wallis one-way analysis of variance 

(ANOVA) was used to test whether mean fire return 

intervals differed among eras. For this test, fire return 

intervals were measured within stands. Stands were 

not included in a factorial test because all stands were 

not represented by fire intervals within each era. A 

separate Kruskal-Wallis test was used to compare fire 

return intervals among stands. A Kruskal-Wallis oneway analysis of variance was also used to test whether 

the mean percentage of fire scarred trees (a proxy for 

fire intensity) differed among eras. Regression analysis 

was used to test whether significant linear relationships 

occurred between stand distance and fire synchroneity 

between stands, as measured by the Jaccard and Yule 

indices. This test was applied within eras.

How have pine and oak recruitment interacted with 

fire history over time? 

Regression analysis was used to test whether 

significant linear relationships occurred between both 

pine and oak recruitment numbers and decadal fire 

frequency calculated in a sliding 10-year window 

(following Stambaugh and Guyette 2006) within 

eras. For this test, we based recruitment on trees aged 

from cores taken from sample plots and lagged fire 

by one decade to accommodate growth to d.b.h. in 

xeric habitat. The sample size for oaks was limited 

by availability of cores to pith because heart-rot was 

common among black oaks. 

How have canopy and sub-canopy vegetation structure 

and composition changed since 1954? 

Shake (1956) provided relative basal area and relative 

density data for each stand, which required converting 

modern data to relative values in order to test for 

significant temporal changes in these categories. 

Repeated measures analysis of variance (RMANOVA) 

was used to test whether relative basal area and 

relative density of trees > 10 cm d.b.h. changed 

between 1954 and 2008 (pre-storm), using the 7 stands 

as replicates. These tests were applied at the species 

level to shortleaf pine, white oak, blackjack oak, post 

oak, black oak, and hickory, as well as a single group 

representing subordinate species that were poorly 

represented as canopy trees. For each stand, Shake 

also provided tallies of tree species stem numbers 

in 2.5-25.4 cm and in >25.4 cm size classes. We 

converted these data to stand point sample densities 

for each species by dividing species tallies by the 

number of plots in each stand. They were analyzed 

by RMANOVA to test whether species point density 

changed between 1954-2008 (pre-storm) within size 

classes. This provided a validation of changes in 

relative density. We also used linear regression to 

test whether 0.025 ha plot density of post oak, which 

declined significantly, was related to canopy openness 

(measured with a digital camera and hemispherical 

lens, Jones and Bowles 2010) and whether its basal 

area was inversely related to that of black oak, the 

dominant canopy species.

How did windstorms alter canopy structure and affect 

species persistence? 

To assess the 2008 and 2009 storm impacts on tree 

species density, we used RMANOVA to test whether 

significant temporal change occurred in basal area 

and relative basal area (dominance) of dominant tree 

species, as well as other subordinate species treated as 

a single group. 

RESULTS

Chronology of Fire and Tree Growth

Cross sections from 25 windthrown trees contained 

110 fire scars, while a single cross-dated stump cross 

section contained 3 scars, resulting in 113 scars 

dating between 1767 and 1993 on 26 trees (Fig. 2). 

Seasonality of presettlement fire scars was difficult 

to assess because of poor conditions of the cross 

sections. However, the majority of scars occurred 

during the dormant season, indicating most fires 

were between September-March. The total number 

of years during which fires were detected included 6 

years in the presettlement era (1767-1825), 22 years 

in the prelogging era (1826-1875), 31 in the logging 

era (1876-1935) years, and 22 in the postlogging 

era. After 1975, only one wildfire and two of three 

management fires were detected, and no fires were 
108 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Figure 2.—Fire chronology of shortleaf pine at Pine Hills. Vertical bars represent fire scars on cross sections from 

25 windthrown trees and a single cross-dated stump between 1767-1993. Vertical axis indicates stand and tree numbers.

recorded after 1993. At the landscape level, fires 

were recorded about every 2 years between 1820 and 

1975. Fire-return intervals measured within stands 

increased significantly over time, averaging 4.55 

(+1.1 se) years in the prelogging era, 6.57 (+1.2 se) 

years in the logging era and 8.19 (+1.5 se) years in the 

postlogging era (Fig. 3). These intervals also varied 

significantly (Chi-square = 13.06, P = 0.011) among 

stands, ranging from 3.7 (0.58 se) to 16.7 (8.69 se) 

years. The percentage of fire-scarred trees, indicating 

fire intensity, was greater during the prelogging era 

(Fig. 3). Within eras, there was no significant 

relationship between distance among stands and fire 

synchroneity. SEA indicated that fires during the 

presettlement era occurred during significant dry years, 

as indicated by the Palmer Drought Severity Index 

(Fig. 4). No significant relationships occurred between 

dry or wet years and fire during the postsettlement, 

logging, or postlogging eras. The standardized 

ring-width chronology was significantly positively 

correlated (r2

 = 0.145, P < 0.001) with summer 

precipitation and negatively correlated 

(r2

 = 0.259, P < 0.001) with summer temperature. 

There were no significant correlations with other 

seasonal precipitation or temperature variables, nor 

with any variables in the previous year.

Shortleaf pine and oak establishment based on plotsampled tree cores were recorded from 1810-1970 

(Fig. 5). The greatest percentage of pine recruitment 

occurred during the prelogging era when it was 

significantly positively correlated with decadal fire 

frequency (Fig. 6). Pine recruitment tended (P < 0.07) 

to be negatively correlated with fire frequency during 

the logging era and positively correlated during the 

postlogging era. Pine recruitment also underwent a 

moderate increase during the early decades of the 

postlogging era. Oak recruitment also was positively 

correlated with fire frequency during the prelogging 

era. However, a greater percentage of oak recruitment 

occurred during the last decade of the logging era and 

continued into the early postlogging era, when it was 

marginally (P < 0.07) correlated with fire frequency. 

Among oaks, white oak recruitment predominated 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 109

Figure 3.—Relationship between mean (+se) fire return interval and mean (+se) percentage of fire-scarred trees across eras at 

Pine Hills. Fire return interval: Chi-square = 6.15, P = 0.046. Sample size: Prelogging (N = 19), Logging (N = 30), Postlogging 

(N = 21). Percentage of fire-scarred trees: Chi-square = 31.56, P < 0.001. Sample size: Prelogging (N = 23), Logging (N = 30), 

Postlogging (N = 26).

Figure 4.—Superposed epoch analysis (SEA) during the presettlement era at Pine Hills. Horizontal axis represents lag in 

years from fire year (0). Bars represent deviation from normal drought conditions based on 1000 simulations. Solid and dashed 

lines are 95 and 99 percent confidence intervals, respectively.

during the prelogging era, black oak and blackjack oak 

predominated during the logging era, and white oak 

and black oak predominated during the postlogging 

eras (Fig. 5). Post oak recruitment was represented by 

single occurrences during the prelogging and logging 

eras.
110 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Figure 6.—Decadal relationship between running mean fires/decade and recruitment of shortleaf pine and oak at Pine Hills. 

Years represent end of decade. Fires are lagged 1-decade. Correlations: Prelogging (pine r = 0.869, P = 0.005; oak r = 0.832, 

P = 0.01); Logging (pine r = -0.83, P = 0.066; oak r = 0.211, P = 0.689); Postlogging (pine r = 0.788, P = 0.063); oak r = 0.788, 

P = 0.0625).

Figure 5.—Recruitment chronology and age-diameter relationships for shortleaf pine (r2

 = 0.293, P = < 0.001) and oak species 

(r2 = 0.610, P < 0.001) at Pine Hills. 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 111

Figure 7.—Temporal change in tree species mean (+se) relative basal area (BA) and relative density at Pine Hills. Relative 

BA: post oak (F = 23.61, P = 0.0028), other (F = 14.78, P = 0.0086). Relative density: post oak (F = 18.26, P = 0.0052), other 

(P = 15.84, P= 0.0073).

Structural and Compositional Change 

By 2008, there were significant declines in relative 

BA and relative density of post oak and an increase in 

these measures for the group of subordinate species, 

including elm, sassafras, service berry, tulip tree, 

red maple, flowering dogwood, ironwood, white ash 

and American beach (Fig. 7, Appendix I). The most 

abundant of these species were subdominant with 

white oak, black oak, and shortleaf pine in juvenile 

and sapling size classes (Appendix I). Post oak also 

declined significantly in density in the 2.5-25.4 cm 

and > 25.4 cm size classes (Fig. 8). This change was 

accompanied by significant increases in white oak 

and other subordinate species in the 2.5-25.4 cm 

size class. In 2009, post oak density had a significant 

positive linear relationship with canopy openness 

(r2

 = 0.5546, P = 0.0022), and its basal area had a 

significant negative relationship with that of black 

oak (r2

 = 0.2337, P = 0.0264). 

Figure 8.—Temporal change in species mean (+se) sample point density by size class at Pine Hills. 2.5-25.4 cm size class: 

white oak (F = 11.38, P = 0.0150), post oak (P = 11.90, P = 0.0016), other (F = 18.73, P = 0.0049); >25.4 size class: post oak 

(F = 29.32, P = 0.0016).
112 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Figure 9.—Species mean (+se) pre- and post-storm basal area, and post-storm change in relative basal area (dominance) at 

Pine Hills. BA: shortleaf pine (F = 6.10, P = 0.0485), black oak (F = 30.51, P = 0.0015). Dominance: hickory (F = 10.34, P = 

0.0183), shortleaf pine (P = 7.57, P = 0.0332), black oak (F = 13.7, P = 0.01).

Before the windstorms, black oak had become the 

single dominant tree with subdominance by shortleaf 

pine and white oak and minor representation by 

blackjack oak and post oak (Fig. 9). Windstorm 

damage caused significant declines in BA of black oak 

and, to a lesser degree, shortleaf pine (Fig. 9). Because 

of the greater reduction of black oak BA, the storm 

damage resulted in increased relative BA (dominance) 

of hickory and shortleaf pine (Fig. 9).

DISCUSSION

Chronology and Change 

in the Fire Regime

At Pine Hills, average stand level fire return intervals 

increased from 4.55 years during the prelogging 

era to 8.19 years during the postlogging era. These 

intervals fall within the ranges reported for other 

Midwest oak-dominated stands with human ignition 

sources (McClain and others 2010) and indicate a 

strong human influence on the Pine Hills fire regime. 

The low fire synchroneity and high variability in 

fire return intervals among stands is probably due 

to spatially independent ignitions, as well as the 

site’s dissected topography, which would reduce the 

landscape spread of fire. Indeed, the maximum number 

of stands with recorded wild fires during single years 

was three stands, which occurred only during 1860 

and 1935. Ignitions also may have been independent 

of ownership by the early 1930s, when the seven 

stands had only three landowners. Cultural conditions 

may strongly affect fire return intervals. Wolf (2004) 

and McClain (2010) report three-decade fire return 

intervals during the mid to late 1800s in southeastern 

Wisconsin and in southern Illinois, and indicate that 

they correspond to periods of accelerated settlement 

and fire protection in the forest-prairie transition 

region. Although the increasing fire return intervals 

at Pine Hills support these findings, the absence of 

extended periods without fire indicates either more 

frequent ignitions or more moderate levels of fire 

suppression. The continuation of burning until about 

1975 parallels results from the Ozark Wilderness of 

the Missouri Ozarks, where fires may have been set 

in protest against federal acquisition (Stambaugh and 

Guyette 2006). Similar actions could have taken place 

at Pine Hills after it was acquired as a Forest Service 

natural area.

Although our presettlement sample depth was 

limited to two trees, the lower fire frequency during 

this period is not inconsistent with other Midwest 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 113

studies (e.g., McClain and others 2010), which would 

suggest that less frequent fires characterized this 

period at Pine Hills. Our data also support findings 

of Stambaugh and Guyette (2006) that less frequent 

fires in the presettlement era corresponded to extreme 

drought conditions, while greater fire frequency 

during the postsettlement era masked the effects 

of drought on fire occurrence. Infrequent droughtdriven fires may have been comparatively intense 

due to fuel accumulation between fire years and 

greater flammability during drought conditions. The 

occurrence of a greater percentage of scarred trees, a 

proxy for greater fire intensity, during the prelogging 

(1825-1875) era also suggests that high intensity 

fires would have continued through this era. The 

composition, structure and fuel loads of forests during 

this period also would have been more similar to 

presettlement conditions than to those that developed 

during the logging period. Increasing fire suppression 

during the 1900s may have contributed to less frequent 

burning as well as lower percentages of scarred trees. 

Tree Recruitment and Interaction with Fire 

The greater recruitment of shortleaf pine during the 

prelogging era, its positive correlation with decadal 

fire frequency, and the greater percentage of scarred 

trees during that era suggest that fire has had a 

strong positive influence on population dynamics of 

shortleaf pine at Pine Hills. Shortleaf pine seedling 

establishment requires 1-4 year fire return intervals, 

and 8-15 fire return intervals for subsequent survival 

and development (Stambaugh and Muzika 2007). 

At Pine Hills, temporal variation in fire return 

intervals falls within that range, and interactions with 

spatially variable topography and fuel loads may 

have facilitated pine regeneration and population 

maintenance. Nevertheless, the lower percentage of 

scarred trees during the logging and postlogging eras 

may indicate that reduced pine recruitment during 

these eras resulted from lower fire intensity. Slash from 

logging is often attributed to causing greater fuel loads 

and greater fire intensity, but no data are available on 

the intensity of logging in pine stands and the levels 

of fuels that might have accumulated. Although oak 

recruitment also had a positive relationship with fire 

frequency during the prelogging era, it had greater 

recruitment during the late logging era, as well as 

the early postlogging era. This process could have 

been enhanced by sprouts from cut stumps following 

logging, as well as large canopy gaps that would have 

persisted for a decade or more following logging. The 

lower recruitment of both oak and pine in the latter 

part of the postlogging era appears to correspond to 

decreasing fire frequency during that era. 

Compositional Change and 

Compensatory Effects of Windthrow 

Xeric habitats have been suggested to be resistant 

to successional replacement of oaks (Abrams 

1992). However, long-term data have demonstrated 

successional change in western post oak-blackjack 

oak forests (DeSantis and others 2010). Likewise, 

our data suggest that reduced fire frequency and 

intensity has lead to replacement of post oak and 

shortleaf pine by black oak, with increased advance 

regeneration of shade-tolerant species. Canopy closure 

may be a strong causal factor in decline of post oak 

because of its shade intolerance (Stransky 1990), and 

has been suggested as a cause of post oak decline in 

southern Illinois (McClain at al. 2010). At Pine Hills, 

the positive relationship between post oak density 

and canopy openness and the negative relationship 

between post oak and black oak basal area suggest 

that post oak may be declining due to competition 

for canopy light caused by increasing canopy closure 

from black oak. The greater resilience of blackjack 

oak, white oak, and black oak may result from species 

specific adaptations to different habitat conditions. 

Blackjack oak may be adapted to more xeric or open 

early-successional habitat, which would allow it to 

persist in a comparatively narrow habitat range at 

Pine Hills where other species are less competitive. 

Black oak and white oak tend to have greater shade 

tolerance than blackjack oak (Dey 2003), and appear 

to tolerate a greater range of overlapping soil moisture 

conditions. This would promote their survivorship 

across a wider habitat range under more dynamic 

canopy conditions.
114 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

If fire protection continues, the increases in smaller 

size classes of shade-tolerant species may provide the 

basis for eventual successional replacement by many 

of these species, as they comprise well over 50 percent 

of the advance regeneration in oak-pine stands at Pine 

Hills. Similar successional change in other systems 

has been linked with fire protection. In Oklahoma, 

sapling densities of winged elm increased while 

densities of post oak and blackjack oak decreased 

(DeSantis and others 2010). Red maple is shade 

tolerant and fire sensitive and is currently expanding in 

eastern forests (Abrams 1998, Green and others 2010, 

McDonald and others 2002). Flowering dogwood and 

sassafras also colonize old fields in southwest Illinois 

but may not persist with succession (Ashby and 

Weaver 1970). Work is needed to understand whether 

restoring fire processes can prevent additional seedling 

establishment and canopy replacement by shadetolerant species and also prevent competition by these 

species from excluding both pine and oaks seedlings.

Interactions between fire and windstorms have 

probably been important historic factors maintaining 

shortleaf pine at Pine Hills (Jones 2003). Our data 

suggest that in the recent absence of fire, the 2008 

and 2009 windstorm effects have been compensatory, 

as they restored the former codominance of shortleaf 

pine with black oak (Shake 1956). Seasonality of 

windthrow was also critical, as the 2009 growing 

season storm selectively removed greater oak than pine 

basal area. This apparently resulted because broadleaf 

oak crowns are more vulnerable to windthrow 

than are needle-leaf pine crowns. Such stochastic 

exogenous disturbance processes may be important 

factors operating in combination with longevity of 

shortleaf pine and presence of optimum habitat in 

maintaining this disjunct pine population. The steep 

slopes and exposed soil at this site probably facilitated 

seedling germination during the presettlement fire 

regime and may have reduced local fuel loads and 

allowed seedling establishment during more frequent 

postsettlement fires. Although projection of increased 

storm damage is problematic (Peterson 2000), climate 

change models predict greater frequencies of severe 

storms (National Assessments Synthesis Team 2004) 

which could continue to favor shortleaf pine over 

hardwoods. However, as the windstorms had no direct 

effect on sapling or juvenile tree species, successional 

processes involving advance regeneration may 

determine future canopy composition (Peterson 2000). 

The size class distribution of shortleaf pine indicates 

that pine advance regeneration is present, and more 

work is needed to determine whether pine will access 

canopy openings created by windthrow. 

ACKNOWLEDGMENTS

This work was funded by the Illinois Endangered 

Species Protection Board and conducted with 

permission of the Shawnee National Forest and U.S. 

Forest Service. We are grateful to Joe Marschall and 

Mike Stambaugh, Missouri Tree Ring Laboratory, 

Department of Forestry, University of MissouriColumbia for invaluable training and assistance. We 

also thank Beth Shimp for information on Pine Hills 

management, Nancy Good for statistical analysis, and 

Nancy Faller for library assistance. We thank Tim Bell, 

Bob Fahey, Don Kurz, Jack White and two anonymous 

reviewers for invaluable comments on this manuscript, 

Michele Bast for assistance with salvaging cross 

sections, and Jenny McBride for GIS assistance. We 

also thank Roy Eugene Shake for sharing an original 

version of his thesis.

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The content of this paper reflects the views of the author(s), who are 

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118 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Appendix

Species nomenclature and stems/ha for tree species in juvenile (<1 m high), sapling (>1 m, 2.54-10 cm 

d.b.h), and tree (>10 cm d.b.h.) size classes at Larue-Pine Hills Natural Area, ranked by juvenile density. 

Densities represent averages of pre- and post- 2008-2009 storm data.

Scientific name Common name Juvenile Sapling Tree 

Ulmus sp. L. Elm 5826.19 553.23 12.36

Quercus alba L. White oak 2127.72 220.31 62.81

Sassafras albidum (Nutt.) Nees. Sassafras 2117.30 470.96 7.32

Quercus velutina Lam. Black oak 2036.37 307.38 141.20

Amelanchier arborea (Michx. f.) Fern. Service berry 1714.12 159.58 2.90

Liriodendron tulipifera L. Tulip tree 1654.14 0.00 0.41

Acer rubrum L. Red maple 1531.75 95.92 2.94

Pinus echinata Mill. Shortleaf pine 1475.31 228.56 120.31

Quercus marilandica Muenchh. Blackjack oak 1164.06 119.93 50.94

Cornus florida L. Flowering dogwood 931.96 354.52 8.17

Ulmus rubra Muhl. Red elm 864.66 14.29 0.00

Carya glabra (Mill.) Sweet. Pignut hickory 747.71 148.02 21.17

Diospyros virginiana L. Persimmon 294.97 24.85 7.33

Carya ovata (Mill.) K. Koch. Shagbark hickory 168.94 24.87 0.00

Ostrya virginiana (Mill.) K. Koch. Ironwood 144.23 43.65 0.00

Fraxinus Americana L. White ash 134.71 20.41 0.00

Fagus grandifolia Ehrh. American beech 112.44 37.70 0.00

Prunus serotina Ehrh. Black cherry 75.19 0.00 0.00

Quercus stellata Wangenh. Post oak 64.94 14.29 19.43

Carya sp Nutt. Hickory 59.52 0.00 0.00

Juniperus virginiana L. Red cedar 59.52 0.00 0.00

Quercus rubra L. Red oak 8.93 65.56 7.20

Carya texana Buckl. Black hickory 4.46 37.68 17.61

Carya ovalis (Wangenh.) Sarg. Sweet pignut hickory 0 0 8.51

Cercis canadensis L. Redbud 0.00 10.20 0.00
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 119

AN OVERVIEW OF PRESCRIBED FIRE IN ARKANSAS AND OKLAHOMA 

OVER THE LAST 40 YEARS

Roger D. Fryar

Fire Management Officer (retired), Ozark National Forest, U.S. Forest Service, 377 Sturgeon Circle, 

Russellville, AR 72802. To contact, call 479-880-9592 or email at rogerfryar@yahoo.com.

Abstract.—Over the last 40 years, prescribed fire programs on National Forest lands 

have grown from relatively insignificant to a major emphasis area of natural resource 

management. During this same period, social, economic, and cultural values have greatly 

changed. The public’s environmental awareness has likewise grown. How prescribed 

fire programs in Arkansas and Oklahoma have fared during this time is a subject of some 

interest. Scientific research in fire ecology and fire history has aided managers, enabling 

them to better explain the need for prescribed fire programs. 

INTRODUCTION

While prescribed fire objectives can vary, restoring, 

enhancing, or maintaining ecosystem health has been 

of primary importance over the last decade. Research 

in the use of fire by people prior to and after European 

settlement and scientific discussions regarding the 

regenerative and restorative ecological effects of 

fire have aided fire managers in obtaining public 

confidence and support for burning programs. Today, 

prescribed fire in Arkansas and Oklahoma represents 

a large part of prescribed fire operations in the 

southeastern United States. The objective of this paper 

is to explore the history of prescribed fire programs. 

This comparison can provide a context and perspective 

into how the public perception of prescribed fire 

has found relatively wide acceptance where other 

vegetation treatment practices, such as clearcutting and 

herbicide use, have not.

The link between timely, pertinent research providing 

key rationale for why wildland fire is needed and 

resultant positive public perception remains key to 

seeing prescribed fire programs continue to grow in 

the future.

The utilization of prescribed fire was a small part of 

ecological restoration and management in Arkansas 

and Oklahoma 40 years ago. However, the next four 

decades witnessed a dramatic increase in the practice. 

Publicity surrounding historic natural catastrophic 

events such as Mount St. Helens and the Yellowstone 

fires may have helped the public to better understand 

ecosystem disturbance dynamics, resiliency, and the 

role of fire in forests. These natural catastrophic events 

provided a contrast to the many man-made disasters 

that occurred during the same time frame (e.g., Threemile Island, Times Beach, Bhophal, Chernobyl, 

and Exxon Valdez). The man-made disasters were 

perceived by the public as “unnatural” and the result 

of mistakes in the imprudent use of science and 

technology. Natural catastrophic events were often 

perceived differently and lent themselves to use as 

“teachable moments” for scientists to better explain 

how the natural world works. Major fire seasons with 

wildfires affecting the urban interface, particularly in 

the West and in Florida, led scientists and politicians to 

address why wildfires seemed to be causing so much 

more damage than in previous decades. Ultimately, 

these assessments led to the National Fire Plan, and 
120 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

shortly afterward came the President’s Healthy Forest 

Initiative (USDOI and USDA 2011). After that, a 

bipartisan led Congress passed the Healthy Forest 

Restoration Act (United States 108th Congress 2003). 

This Act focused on treatments to vegetation designed 

to restore “reference” ecological conditions and lower 

the threat of catastrophic wildfires in fire-adapted 

ecosystems. Prescribed fire was recognized as a 

primary vegetation management tool to accomplish 

these goals. The Fire Regime Condition Class 

(FRAMES 2011) and LANDFIRE (USDA and USDOI 

2011) projects soon became available to help land 

managers identify and rank how degraded ecosystems 

had become, comparing reference conditions to current 

conditions.

HISTORY OF PRESCRIBED FIRE 

IN THE REGION

The Ouachita and Ozark-St. Francis National Forests 

in Arkansas and Oklahoma are within the Interior 

Highlands and are the focus for a significant amount of 

prescribed fire for ecological restoration, maintenance, 

and enhancement. Public land within this geographic 

area contains a high percentage of fire dependent 

plant communities. Shortleaf pine-bluestem and oak 

woodlands are two representative fire-dependent plant 

communities common in this area. Natural fire regimes 

for these communities are generally characterized by 

frequent, periodic fire of low to moderate severity. 

Current conditions are far removed from the reference 

condition with most lands in condition class three 

(the most highly departed). Federal agencies, (e.g., 

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

Department of Interior, National Park Service, and 

Fish and Wildlife Service) state agencies, and private 

land trusts (e.g., The Nature Conservancy [TNC]) have 

developed large prescribed fire and fuel management 

programs. TNC provides key leadership and a clear 

voice to the public on prescribed fire issues. Research 

is conducted by universities, the Forest Service, the 

Fish and Wildlife Service, and National Park Service. 

Technology and information transfer is accomplished 

through a variety of means including Joint Fire 

Science Projects, The Fire Learning Network, research 

publications, Fire Effects Information System, 

Smoke Management Portals (e.g., Forest Consortium 

for the Advanced Modeling of Meteorology and 

Smoke [FCAMMS]), and various ad hoc councils, 

committees and planning efforts. A summary of some 

of this work is documented in Spetich (2004). These 

findings provided rationale for decisions in Land 

Management Plans for the National Forests and help 

guide development of reference condition descriptions 

in both Fire Regime Condition Class (FRCC) and 

LANDFIRE efforts.

There are a number of private citizen groups with 

a variety of views regarding prescribed fire. Some 

groups such as Audubon, Quail Unlimited, and The 

National Wild Turkey Federation serve as strong 

advocates for burning. Others such as Sierra Club and 

Wilderness Society vary in views, with some local 

chapters advocating the prudent use of fire while 

others are resistant to burning.

During the 1970s, most burning objectives for the 

National Forests in the southeast were tied directly to 

range or game habitat improvement, with programs 

averaging a few hundred acres to a few thousand acres 

annually. Management of habitat for the federally 

endangered red-cockaded woodpecker (RCW) led 

to an increase in prescribed fire and an affirmation 

by scientists (and the courts) that RCW was a fire 

dependent species whose optimal habitat required 

frequent burning. While normally dynamic enough 

to sustain themselves in the face of natural biotic and 

abiotic events, forest insect and disease outbreaks in 

Arkansas and Missouri have lent credence to the idea 

that disturbance driven forest ecosystems could not be 

sustained as host tree density rapidly increased. The 

resulting epidemics may have created ecologically 

unsustainable conditions along with both biological 

and economic loss. To much of the public, prudent 

but active management (rather than a “hands-off” 

approach) may have become more popular. 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 121

Few prescribed fires were occurring on federal lands 

in the 1970s and into the early 1980s. The hiring of 

wildlife biologists to work at the district level on 

the National Forests in the late 1970s resulted in a 

significant growth in prescribed fire programs. Some 

of the first landscape-scale burns were conducted in 

the late 1970s.

On private land, timber companies managed land 

primarily for timber production in the 1970s but began 

leasing lands for hunting in the late 1970s (Arkansas). 

Some of these leases were burned specifically to 

improve habitat for deer and upland birds. The burning 

had positive effects in maintaining fire-adapted plant 

and animal species. Prescribed fire by industry began 

diminishing as liability concerns (escapes and smoke) 

caused companies to rethink vegetation management 

alternatives. Consequently, herbicide use increased on 

many industrial forested lands.

In the 1980s, burning for RCW began in earnest. “New 

Perspectives” initiatives merging research efforts at 

landscape-scale projects took root in the late 1980s 

and 1990. Arkansas occupies a unique and important 

place in the history of new perspectives and ecosystem 

management. A historic visit to the Ouachita National 

Forest by Senator David Pryor (D-Arkansas) in August 

1990, thereafter called the walk in the woods, served 

as an opportunity to shift the Ouachita’s style of 

management in a manner that has served as a model 

for other national forests in the Nation (Guldin 2004). 

Eventually “new perspectives” was replaced with 

ecosystem management as the byword for how U.S. 

Forest Service lands were to be managed.

The 1990s saw significant growth in prescribed fire 

programs on all Federal lands as the National Fire 

Plan emerged and additional funding was made 

available. The size of programs along with increases in 

prescribed fire incidents led to more agency oversight 

and policies, and state regulation of prescribed fire. In 

1999 the Ozark-Ouachita Highlands Assessment was 

done as a prelude to forest planning efforts. Findings 

regarding the role of fire in that assessment mirrored 

historical references by early explorers that described 

vegetation. They concluded that both pine and oak 

woodlands benefited from fire (USDA FS 1999).

The year 2000 marked the third year of drought in 

Arkansas thought to have contributed to a historic 

outbreak of red oak borer that affected thousands of 

acres in the national forests of Arkansas, Oklahoma, 

and Missouri. The prevailing low-disturbance fire 

suppression regime was cited as likely leading to oak 

forests being replaced by shade tolerant hardwood 

trees (Starkey 2004).

The Land and Resource Management Plans for both 

the Ouachita and Ozark-St. Francis National Forests 

were approved in 2005 (USDA FS 2005a, 2005b). 

Both plans called for an increase in prescribed fire as 

compared to former plans, with burning recommended 

for managing, restoring, and sustaining old-growth 

shortleaf pine, enhancing federally endangered RCW 

habitat and Indiana bat habitat, and responding to other 

ecological and social issues.

The surprising growth in prescribed fire (Table 1) 

can be largely attributed to how the practice has 

been perceived as a land management tool. Timely 

and pertinent research findings coupled with the 

relative absence of significant mishaps (escaped 

burns or smoke-related incidents) have also helped. 

Key research documenting mean fire return intervals 

generated through tree ring chronologies and General 

Land Office descriptions of pre-European settlement 

vegetation have greatly aided managers.

Symposia such as this and others provided a forum for 

the presentation of such research findings (Dickinson 

2005, Powers 2007, Spetich 2004). Reference 

condition descriptions and modeling generated by 

Fire Regime Condition Class (FRAMES 2011) and 

LANDFIRE (USDA and USDOI 2011) programs 

further provided a scientific basis for rationale 

supporting the role of fire in ecological communities 

found throughout the Ouachita, Boston, and Ozark 

Mountains.
122 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Table 1.—Prescribed Burning on the Ouachita and Ozark-St. Francis National Forests 1986-2010

 Year Acres burned

1986 27,754

1987 33,278

1988 49,785

1989 28,885

1990 30,561

1991 33,202

1992 31,726

1993 44,928

1994 37,643

1995 43,732

1996 59,139

1997 107,552

1998 155,181

 Year Acres burned

1999 135,041

2000 132,859

2001 79,653

2002 120,854

2003 180,644

2004 202,490

2005 134,957

2006 116,118

2007 215,483

2008 187,895

2009 183,163

2010 197,259

The ability of fire managers to clearly articulate to 

the public the need to burn and to demonstrate the 

effectiveness of burning have greatly assisted in 

program acceptance by the public and subsequent 

growth. The Forest Service Land and Resource 

Management Plans of 2005 used a “best-science” 

approach to describe the role of fire in the 

ecosystem and need to do prescribed fire in an 

effort to accomplish specific ecological restoration. 

Catastrophic events of national significance captured 

both the public and political interest in the need to 

better reduce the risk of catastrophic wildfire and 

understand the role of fire in fire-adapted ecosystems. 

The National Fire Plan and Healthy Forest Initiative 

(USDOI and USDA 2011) and Healthy Forest 

Restoration Act (United States 108th Congress 2003) 

have further provided impetus to the need to burn.

THE FUTURE OF PRESCRIBED 

BURNING IN THE REGION

The future for increased burning in the Ozark/Ouachita 

Highlands may well depend on the ability of managers 

to conduct burns without incident (nuisance smoke, 

escapes and/or negative press from other adverse 

impacts). Political oversight and the public will 

continue to need added and ongoing evidence that 

burning programs are lowering the risk of catastrophic 

fire, resulting in the restoration of ecosystems and 

their fire dependent species. Such evidence could 

be depicted in updates in LANDFIRE mapping 

(LANDFIRE 2011) or other assessments. Partnerships 

among federal, state, and nongovernmental 

organizations (NGOs) will be critical for the continued 

and perhaps increased use of fire for ecological 

restoration. Today, annual burning represents a 

relatively small percentage of federal ownership (less 

than 10 percent) but is an important program area for 

federal agencies and is a major source of funding. 

Public acceptance and/or support for prescribed 

fire are important to any program’s growth. Strong 

partnerships between research, state and federal 

agencies, and conservation groups will undoubtedly 

help burners to accomplish program goals.

The future growth in burning programs is likely to be 

less in this decade than in the past two decades. More 

stringent prescribed fire parameters, smoke issues, 

liability risks from escapes, and potential regulation 

of emissions could cloud the future for any significant 

program growth. Nevertheless, more pertinent research 

showing the continuing need for prescribed fire along 

with focused technology transfer and key partnerships 

could help alleviate many of the potential roadblocks.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 123

LITERATURE CITED

Dickinson, M.B., ed. 2005. Fire in eastern oak 

forests: delivering science to land managers.

Gen. Tech. Rep. NRS-P-1. Newtown Square, PA: 

U.S. Department of Agriculture, Forest Service, 

Northern Research Station. 303 p.

FRAMES. 2011. Fire research and management 

exchange system. Available at http://www.frames.

gov. [Date accessed unknown].

Guldin, J.M., tech. comp. 2004. Ouachita and Ozark 

Mountains symposium: ecosystem management 

research. Gen. Tech. Rep. SRS-74. Asheville, NC: 

U.S. Department of Agriculture, Forest Service, 

Southern Research Station. 321 p.

Powers, R.F., tech. ed. 2007. Restoring fire-adapted 

ecosystems: proceedings of the 2005 national 

silviculture workshop. Gen. Tech. Rep. PSWGTR-203. Albany, CA: U.S. Department of 

Agriculture, Forest Service, Pacific Southwest 

Research Station. 306 p.

Spetich, M.A., ed. 2004. Upland oak ecology 

symposium: history, current conditions, 

and sustainability. Gen. Tech. Rep. SRS-73. 

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

Forest Service, Southern Research Station. 311 p.

Starkey, D.A.; Oliveria, F.; Mangini, A.; Mielke, M. 

2004. Oak decline and red oak borer in the 

Interior Highlands of Arkansas and Missouri: 

natural phenomena, severe occurrences.

Gen. Tech. Rep. SRS-73. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, 

Southern Research Station: 217-222.

United States 108th Congress. 2003. Healthy forests 

restoration act of 2003. H.R. 1904. Washington 

D.C: Government Printing Office. Available at 

http://frwebgate.access.gpo.gov/cgi-bin/getdoc.

cgi?dbname=108_cong_bills&docid=f:h1904enr.

txt.pdf.

There is a compelling logic to nature. Form really does 

follow function. Technology transfer from scientist 

to resource manager is partially dependent on the 

individual researcher’s ability to publish. There are 

opportunities to leverage discoveries and findings 

among researchers delving into similar projects. There 

must be ways for managers to provide feedback to 

researchers to ensure there is a focus to what is being 

studied, i.e., that some of the questions scientists are 

studying have direct applicability to help program 

managers accomplish resource goals and objectives. 

There are opportunities to use natural events as a 

means to examine, explain, or demonstrate ecological 

processes to the public. There are new and/or emerging 

technologies that can greatly enhance technology 

transfer. The public has shown an amazing interest 

for several decades to better understand how things 

work in an ecological sense. Better public knowledge 

of ecosystem function promotes the potential “buyin” to projects and programs that otherwise might be 

so controversial as to be impossible to implement. 

Consequently, a key message and challenge to 

researchers is to help managers better describe to the 

public why burning is important and how prescribed 

fire can be used to restore, enhance, or maintain fireadapted ecosystems. Engaging the public by seeking 

input on both programmatic and site-specific projects 

can have a very positive effect. Using forums like the 

Fire Learning Network, Prescribed Fire Councils, and 

symposia like these can foster partnerships and meld 

diverse groups to a common goal.

ACKNOWLEDGMENTS

A number of professional land managers (currently 

working and retired) helped in providing overview 

information and timeline construction information.
124 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

U.S. Department of Agriculture, Forest Service. 

1999. Ozark-Ouachita highlands assessment: 

terrestrial vegetation and wildlife. Gen. Tech. 

Rep. SRS-35. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research 

Station. 201 p.

U.S. Department of Agriculture, Forest Service. 2005a. 

Revised Land and Resource Management 

Plan, Ouachita National Forest, Arkansas and 

Oklahoma. Manage. Bull. R8-MB 124A. Atlanta, 

GA: U.S. Department of Agriculture, Forest 

Service. 175 p.

U.S. Department of Agriculture, Forest Service. 2005b. 

Revised Land and Resource Management Plan, 

Ozark-St. Francis National Forests. Manage. 

Bull. R8-MB 125A. Atlanta, GA: U.S. Department 

of Agriculture, Forest Service. 296 p.

U.S. Department of Agriculture and U.S. Department 

of the Interior. 2011. LANDFIRE. Landscape 

fire and resource management planning tools.

Available at http://www.landfire.gov. [Date 

accessed unknown].

U.S. Department of the Interior and U.S. Department 

of Agriculture. 2011. Forests and range-lands. 

Previous wildland fire management initiatives.

http://www.forestsandrangelands.gov/resources/

overview/index.shtml. [Date accessed unknown].

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
From the Field: 

Fire Management In 

Oak Forest Ecosystems
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Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 127

RESTORING FIRE SUPPRESSED TEXAS OAK WOODLANDS 

TO HISTORIC CONDITIONS USING PRESCRIBED FIRE

Jeff C. Sparks, Michael C. Stambaugh, and Eric L. Keith

Wildland Fire Program Manager (JCS), Texas Parks and Wildlife Dept., 12016 FM 848, 

Tyler, TX 75707; Research Assistant Professor (MCS), University of Missouri-Columbia; 

Project Manager (ELK), Raven Environmental. JCS is corresponding author: 

to contact call 903-566-0535 ext. 237 or email at Jeff.Sparks@tpwd.state.tx.us. 

Abstract.—Comparable to many oak ecosystems across the eastern United States, oak 

woodlands in Texas display characteristics of changing composition and structure due 

to altered fire regimes. Information describing historic fire regimes suggests woodlands 

underwent relatively frequent and repeated burning prior to major Euro-American 

influence in the early 19th century. Oak woodland management is a central goal of 

the Texas Parks and Wildlife Department natural community management; however 

many questions and challenges exist related to habitat loss and fragmentation, human 

populations, and prescribed fire implementation. In this paper we: 1) review information 

describing the historic fire regimes and community structures of Texas oak woodlands; 

and 2) detail fire prescriptions and challenges related to restoring long unburned sites.

Introduction

A goal of many land management agencies is to 

restore existing vegetation communities to resemble 

the vegetation composition and structure prior to 

industrialization or Euro-American settlement. The 

timing of major landscape and fire regime changes 

varied spatially but generally occurred in Texas 

during the mid-19th century or earlier. Restoring 

oak woodlands that have undergone decades of fire 

exclusion and become invaded by a dense understory 

and midstory can require intensive management and 

high cost inputs. 

Using prescribed fire with standard published 

prescription parameters in these invaded oak 

woodlands often results in intermediate fire spread 

and relatively low intensity fires, thus not meeting 

objectives of reducing the stature of the invading 

understory and increasing the coverage of herbaceous 

species. It is often recommended that a combination 

of higher cost management tools such as mechanical 

and chemical treatments be used initially followed 

by prescribed fire as a maintenance tool. These more 

intensive management efforts greatly increase the cost 

for restoring these invaded woodlands, thus limiting 

the area that can potentially be restored. Based on 

13 years of experience, we have begun to develop 

prescriptions for effectively restoring these vegetation 

communities to historic conditions by using fire as the 

primary management tool.

CONDITIONS OF HISTORIC TEXAS 

OAK WOODS AND PRAIRIES

Composition and Structure

Aside from anthropogenic features (roads, towns, 

agricultural lands), the major difference between the 

pre-Euro-American settlement vegetation and the 

current vegetation in Texas Oak Woods and Prairies 

(Fig. 1) is the increase in woody species biomass and 

resulting reduction in herbaceous species biomass 

(Diggs and others 2006). In the absence of fire (natural 
128 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Figure 1.—Map of Texas ecoregions within the Oak Woods and Prairies region. Place names relate to the descriptions given 

for historic descriptions of vegetation and fire history.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 129

and controlled), woody species have encroached into 

post oak (Quercus stellata) dominated communities 

that were historically open and park-like (Diggs and 

others 2006). The terms savanna and woodland do 

not accurately portray the region’s current forest 

community structures, but according to early settler 

and explorer reports, they were accurate descriptors of 

pre-Euro-American settlement conditions (Diggs and 

others 2006). 

Olmsted (1857) described an area most likely near the 

Houston County–Leon County line: 

“We came today upon the first prairie of any 

extent, and shortly after crossed the Trinity 

River. After having been shut in during so many 

days by dreary winter forests, we were quite 

exhilarated at coming out upon an open country 

and a distant view. During the whole day’s ride 

the soil improved, and the country grew more 

attractive. Small prairies alternated agreeably 

with post-oak woods. The post-oak...forms a 

very prominent feature in Texas scenery and 

impressions. It is a somewhat small broadleaved oak of symmetrical shape, and appears 

wherever the soil is light and sandy, in a very 

regular open forest growth. It stands in islands in 

the large prairies or frequently borders an open 

prairie through a large tract.” 

More densely forested areas would have occurred in 

association with natural fire breaks or in areas with 

lessened fire severities such as in rough terrain or low 

productivity sites. Roemer (1849) provides evidence 

for this vegetation patterning in his descriptions of an 

area between Gonzales and La Grange as “a sandy, 

hilly country, covered almost entirely with post oak 

forests.” 

Captain Domingo Ramón in 1716 described forests in 

what is probably present-day Burleson County as so 

dense that “there were not enough hatchets and knives 

to open a passage” (Foster 1995).

Olmstead (1857) described multiple community types 

and structures including the presence of fires in this 

description of Leon County: 

“During the first part of the day we went over 

small, level, wet prairies, irregularly skirted by 

heavy timber, with occasional isolated clumps 

and scattered bushes. Most of the prairies have 

been burned over. Both yesterday and to-day 

we have been surrounded by the glare of fires at 

night. After a few miles began post-oak, which 

changed to blackjack, and for the remainder 

of the day the country was as forbidding as a 

moor.” 

Approximately 100 km to the south (Colorado 

County), Roemer (1849) described the structure of 

post oak forests: 

“These forests ...have a remarkable resemblance 

in winter to the cultivated German oak forests.... 

In other forests of North America many varieties 

of trees are usually found, but in the post-oak 

forests all are excluded with the exception of a 

few walnuts. Underbrush is also lacking. The 

soil upon which the post-oaks grow is usually 

of average fertility, but also often sterile and 

unproductive.... [There] is a wide zone where 

deposits of gravel and sand are found, and where 

farming cannot be carried on successfully. Here 

the land is covered with post-oaks.”

In summary, the Texas Oak Woods and Prairies region 

was likely a complex mosaic varying from prairies and 

open savannas to forests with closed canopies (Diggs 

and others 2006; Keith 2008, 2009d, 2010a, 2010b; 

Keith and Leavitt 2008). 

Fire Regimes

Since Euro-American settlement, fire regimes in Texas 

and throughout North America have been highly 

altered. Although fire is regarded as a principal historic 

disturbance to most of Texas’ ecoregions (McNab and 

Avers 1994), relatively little work has been done to 
130 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

describe how fire regimes of Texas Oak Woods and 

Prairies varied spatially and temporally (Courtwright 

2007, Diamond and others 1995). Here we describe 

fire regimes relevant to Texas Oak Woods and Prairies 

(Fig. 1).

Oak Woodlands

Very little information is available describing the 

historic fire regime in the Oak Woodlands (Fig. 1). 

Many of the relict oak woodlands have experienced 

infill of woody vegetation suggesting that the 

disturbance regime (fire and/or grazing) has been 

altered. A recent fire scar history study developed in a 

relict sand post oak (Quercus margaretta) woodland 

in Van Zandt County provides one example of what 

the fire regime may have been (Stambaugh and others 

2011). Here, the mean fire return interval for the 325 

years from 1681-2005 was 6.9 years. Prior to 1850 

(approx. timing of major Euro-American influence), 

fire intervals ranged from 2 to 16 years, with a mean 

fire interval of 5.9 years. Based on the presence 

and recruitment of trees, there was no evidence of 

stand replacing fire events, however two relatively 

severe fires occurred prior to 1850. During the Civil 

War era, fire frequency decreased and coincided 

with establishment of an oak cohort. Nearly all fires 

recorded at the site occurred when oaks were dormant. 

Eastern and Western Cross Timbers

Fire is considered an important disturbance agent to 

maintaining the Cross Timbers ecosystem (Engle and 

others 1996) which extends from southeastern Kansas 

to central Texas (Francaviglia 2000). Dyksterhuis 

(1948) related that early settlers of the Jacksboro 

vicinity recalled no shrubby undergrowth in the 

western Cross Timbers, but instead remember a 

grassy understory which commonly burned during 

dry periods. They also stated that when the first 

white settlers arrived in the western Cross Timbers 

fringe, the Indians were known to regularly burn 

off the grass and had done so for years. Dyksterhuis 

(1948) described the uncertainty as to the pre-EuroAmerican settlement fire regime of the Cross Timbers, 

but several accounts by early travelers mention the 

incursion of adjacent prairie fires into the Cross 

Timbers as the mechanism for grassy understories and 

branch formations of the trees. A survey conducted in 

the Trinity River watershed by the U.S. Department 

of Agriculture in 1942 used fire scars to show that 

periodic fires were still occurring through the mid-20th 

century (Dyksterhuis 1948). 

Recently, several fire scar history studies in more 

northerly Cross Timbers have contributed to 

characterizing the fire regime (Allen and Palmer 2011, 

Clark and others 2007, DeSantis and others 2010, 

Stambaugh and others 2009). Common among these 

studies are pre-Euro-American settlement period 

mean fire intervals of 3 to 6 years, a preponderance 

of dormant season fire events, and evidence for 

anthropogenic burning. These studies have had little to 

bear on the range of fire severity, however all sites had 

trees >200 years in age, suggesting no stand replacing 

events had occurred during at least the previous two 

centuries. Based on observations of fire scar heights 

in Cross Timbers post oaks, many of these sites likely 

experienced low- to moderate-severity fires. However, 

fires have the potential to be very high severity (e.g., 

stand-replacing) and widespread (>100,000 acres), 

particularly during drought conditions. In April 2011, 

wildfires burning through the western Cross Timbers 

in Palo Pinto County were stand replacing crown fires.

Blackland Prairie and Grand Prairies

As the southernmost extension of the “true prairie” 

(i.e., tallgrass prairie), the Blackland Prairie probably 

had a similar fire regime to other tallgrass prairie 

regions. The Blackland Prairie experiences higher 

temperatures and a longer growing season than the rest 

of the tallgrass prairie ecosystem, and its fire regime 

may have reflected these environmental differences 

(Smeins 1972). Smeins (2004) cites two reports from 

the 1840s (Gregg 1844, Kendall 1845) that assert 

that frequent fires and large grazing animals were the 

primary influences on vegetation in the Grand Prairie 

and Cross Timbers regions in pre-Euro-American 

settlement times. Considering the Blackland and Grand 

Prairie’s positions between the oak-dominated Cross 

Timbers and Oak Woodlands, it is likely that their fire 

regimes are strongly related. Like the Cross Timbers 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 131

and Oak Woodlands, it is likely that these large prairie 

subregions burned at least every 3 to 4 years. With a 

dominance of grass surface fuels, the potential burning 

window of the prairies was likely larger, leading to an 

increased fire frequency compared to areas dominated 

by litter and woody fuels.

Current Structure

Post oak savanna habitats that historically burned 

regularly and have continued to burn to present day 

are very open and dominated by native grasses and 

forbs in the understory (Keith 2008, 2010b; Keith and 

Leavitt 2008). Examples of this habitat type are now 

extremely rare. Pre-Euro-American settlement upland 

habitat types can be characterized most prominently 

by the Post Oak (Quercus stellata)-Blackjack Oak 

(Quercus marilandica) Series and the Post Oak 

(including sand post oak [Quercus margaretta])-

Black Hickory (Carya texana) Series (Diamond and 

others 1987). In addition, the Loblolly Pine (Pinus 

taeda)-Oak Series, Shortleaf Pine (Pinus echinata)-

Oak Series, and Bluejack Oak (Quercus incana)-Pine 

Series can be found in uplands on the eastern edge 

of the Oak Woods and Prairies Ecoregion and in the 

Bastrop Lost Pines Subregion (Griffith and others 

2007). Bluejack oak woodlands occur on xeric sandy 

soils in this region. In the western portion of the 

region, habitats in the Plateau Live Oak (Quercus

fusiformis) Series, Plateau Live Oak-Midgrass Series, 

and Ashe Juniper (Juniperus ashei)-Oak Series 

also occur as part of the ecotone with the Edwards 

Plateau Ecoregion. The Coastal Live Oak (Quercus

virginiana)-Post Oak Series occurs in the southern 

portion of the ecoregion. A complete list of common 

plant associations found throughout the region is found 

in Table 1 (Nature Serve 2011). Plant associations 

describe the most narrowly defined habitat types. 

Post Oak-Blackjack Oak Series Eastern Redcedar Forest TL3

Coastal Live Oak-Post Oak Series Live Oak-Post Oak-Cedar Elm-Water Oak Forest TL6, TU2, TU3

Loblolly Pine-Oak Series Loblolly Pine-Post Oak-Blackjack Oak Forest (Vernia or 

Jedd Rocky Upland)

TL6, TL8

Loblolly Pine-Oak Series Loblolly Pine-Post Oak-Eastern Redcedar-Blackjack 

Oak-Black Hickory Forest

TL8

Loblolly Pine-Oak Series Loblolly Pine-Sand Post Oak-Post Oak-Blackjack Oak 

Forest

TU2

Loblolly Pine-Oak Series Loblolly Pine-Yaupon Ravine Forest TL9

Plateau Live Oak-Midgrass Series Plateau Live Oak / Little Bluestem Woodland GR4

Ashe Juniper-Oak Series Post Oak-Ashe Juniper-Purpletop-Virginia Wild Rye 

Woodland

TL6, TU3

Post Oak-Black Hickory Series Post Oak-Black Hickory-Yaupon-Woodoats-(Little 

Bluestem)-Woodland

TL6, TU2, TU4

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak / Little Bluestem Woodland GR2, GR6, GS3, GS4, TU3

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak Cross Timbers Woodland TU3

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak Woodland TU3

Table 1.—Common plant associations including series and usual fuel model for habitats in the Post Oak 

Savanna and Cross Timbers and Prairies Ecoregions. See Table 2 for descriptions of fuel models. 

Series Association Fuel Model

(Table 1 continued on next page)
132 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Table 1 (continued).—Common plant associations including series and usual fuel model for habitats 

in the Post Oak Savanna and Cross Timbers and Prairies Ecoregions. See Table 2 for descriptions of 

fuel models. 

Series Association Fuel Model

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak-American Ash-Winged ElmWoodoats ForestTU2, TU3

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak-Black Hickory-Farkleberry 

Forest

TL6, TL9, TU2, TU3

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak-Cedar Elm Forest TL6

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak-Cedar Elm-Little BluestemCoralberry WoodlandTU2, TU3

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak-Eastern Redcedar Forest TU2

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak-Eastern Redcedar-Little 

Bluestem Woodland

GS3, TU2, TU3

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak-Red Oak-Yaupon-Woodoats 

Forest

TL6

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak-Rusty Blackhaw-Roughleaf 

Dogwood-Purpletop Forest

TL6, TU2, TU3

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak-Winged Elm-Roughleaf 

Dogwood-Silver Bluestem-Little Bluestem Woodland

GS4, TU3

Post Oak-Blackjack Oak Series Post Oak-Blackjack Oak-Yaupon Forest TU2

Post Oak-Blackjack Oak Series Post Oak-Cedar Elm Forest TL6, TU2

Post Oak-Blackjack Oak Series Post Oak-Cedar Elm-Blackjack Oak-Little Bluestem 

Woodland

GS3, GS4, TU3

Post Oak-Blackjack Oak Series Post Oak-Cedar Elm-Blackjack Oak-Purpletop-Virginia 

Wild Rye Woodland

TU2, TU3

Coastal Live Oak-Post Oak Series Post Oak-Cedar Elm-Cherokee Sedge-Purple Top 

Forest

TU2, TU3

Post Oak-Black Hickory Series Post Oak-Cedar Elm-Coralberry-Caric Sedge Forest TL6

Post Oak-Blackjack Oak Series Post Oak-Gum Bumelia-Saw Greenbriar-Purpletop 

Woodland

GS3, TU3

Post Oak-Blackjack Oak Series Post Oak-Little Bluestem-Longspike Tridens-Bushy 

Bluestem-Rush Spp Woodland

GS3

Post Oak-Blackjack Oak Series Post Oak-Lovegrass-Silver Bluestem Woodland GR3

Post Oak-Blackjack Oak Series Post Oak-Mesquite Woodland GR4

Post Oak-Blackjack Oak Series Post Oak-Plains Love Grass-Longspike Tridens 

Claypan Savannah

GR3

Post Oak-Blackjack Oak Series Post Oak-Plateau Live Oak-Cedar Elm-Caric SedgeVirginia Wildrye ForestTU3

(Table 1 continued on next page)
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 133

Table 1 (continued).—Common plant associations including series and usual fuel model for habitats 

in the Post Oak Savanna and Cross Timbers and Prairies Ecoregions. See Table 2 for descriptions of 

fuel models. 

Series Association Fuel Model

Post Oak-Black Hickory Series Post Oak-Sand Post Oak-Black Hickory-Blackjack OakSouthern Red Oak-Woodoats ForestTL6

Post Oak-Black Hickory Series Post Oak-Sand Post Oak-Black Hickory-Blackjack OakWhite Ash-Woodoats ForestTL6, TU2

Post Oak-Black Hickory Series Post Oak-Southern Red Oak-Black Hickory-White AshShortleaf Pine ForestTU2

Post Oak-Blackjack Oak Series Post Oak-Southern Red Oak-Blackjack Oak-Shortleaf 

Pine Forest

TL6, TU3

Post Oak-Blackjack Oak Series Post Oak-Southern Red Oak-Water Oak-Nutmeg 

Hickory-American Ash Forest

TU2

Post Oak-Blackjack Oak Series Post Oak-Texas Ash-Plateau Live Oak-Ashe Juniper 

Slope Forest

TL6, TU2, TU3

Post Oak-Blackjack Oak Series Post Oak-Water Oak-Cedar Elm-Sugarberry Forest TU2, SH9

Post Oak-Blackjack Oak Series Post Oak-Water Oak-Sand Post Oak-Winged Elm 

Forest

TL2

Post Oak-Blackjack Oak Series Post Oak-White Ash-Blackjack Oak-Woodoats Forest TL6

Post Oak-Blackjack Oak Series Post Oak-Winged Elm Forest TL6

Post Oak-Blackjack Oak Series Post Oak-Winged Elm-Water Oak-Blackjack Oak 

Forest

TU2, TU3

Post Oak-Blackjack Oak Series Post Oak-Winged Elm-White Ash-BeautyberryWoodoats-Nutrush ForestTL6, TU2

Post Oak-Black Hickory Series Sand Post Oak-Black Hickory-Loblolly Pine Forest TU2, TU3

Post Oak-Black Hickory Series Sand Post Oak-Black Hickory-Red Oak-Little Bluestem 

Woodland

TU3

Post Oak-Black Hickory Series Sand Post Oak-Black Hickory-Red Oak-YauponWoodoats ForestTL6

Post Oak-Black Hickory Series Sand Post Oak-Black Hickory-Southern Red Oak 

Forest

TU2

Coastal Live Oak-Post Oak Series Sand Post Oak-Live Oak-Black Hickory-Yaupon Forest TU2

Loblolly Pine-Oak Series Sand Post Oak-Loblolly Pine-Black Hickory-Eastern 

Redcedar-Yaupon Forest

TL6, TL9, TU2

Shortleaf Pine-Oak Series Shortleaf Pine-Southern Red Oak-Cherrybark OakLoblolly Pine-Post Oak-White Oak-White Ash ForestTL6, TU2, TU3

Post Oak-Black Hickory Series Southern Red Oak-Sand Post Oak-Post Oak-Eastern 

Redcedar-Water Oak Forest

TL6
134 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Most of the natural vegetation that has not been 

cleared for agriculture or urbanization is generally 

characterized by a mature overstory of post oak and 

a dense understory dominated by woody species. 

The most common woody species in these dense 

understories within its range is yaupon (Ilex vomitoria) 

(Keith 2009a, 2009b, 2009c, 2009d). In many areas, 

yaupon often creates a near monoculture in the 

understory, shading and virtually eliminating all 

native herbaceous vegetation. In the native yaupon 

range, post oak woodlands and forests are noticeably 

dense and difficult to restore to habitats with open 

herbaceous understories. Common community types 

or plant associations of this type (Nature Serve 2011) 

include the Loblolly Pine-Yaupon Ravine Forest, 

Post Oak-Black Hickory-Yaupon-Woodoats-(Little 

Bluestem)-Woodland, Post Oak-Blackjack Oak-Red 

Oak-Yaupon-Woodoats Forest, Post Oak-Blackjack 

Oak-Yaupon Forest, and Sand Post Oak-Black 

Hickory-Red Oak-Yaupon-Woodoats Forest (Table 1).

Outside the native yaupon range, woodlands are 

noticeably more open and easier to restore to habitats 

with herbaceous understories. Woody species 

that also encroach into upland habitats within and 

outside the native yaupon range include winged elm 

(Ulmus alata), American beautyberry (Callicarpa 

americana), eastern redcedar (Juniperus virginiana), 

saw greenbriar (Smilax bona-nox), Small’s greenbriar 

(Smilax smallii), roughleaf dogwood (Cornus 

drummondii) (on clay soils), upland privet (Forestiera 

ligustrina), Alabama supplejack (Berchemia 

scandens), coralberry (Symphoricarpos orbiculatus), 

Virginia creeper (Parthenocissus quinquefolia), and 

poison ivy (Toxicodendron radicans). The latter 

four species are often as effective as yaupon in outcompeting native herbaceous vegetation outside 

the dominant range of yaupon (Keith 2006, 2010b; 

Keith and Leavitt 2008). Common plant associations 

include Eastern Redcedar Forest, Post Oak-Blackjack 

Oak-Eastern Redcedar Forest, Post Oak-Winged 

Elm Forest, and Post Oak-Winged Elm-White AshBeautyberry-Woodoats-Nutrush Forest (Nature Serve 

2011) (Table 1). 

High quality savannas and woodlands consist of areas 

that have been frequently burned, and these areas are 

often dominated by post oak and a diverse herbaceous 

ground cover layer (Keith 2008). The dominant 

herbaceous species is most often little bluestem 

(Schizachyrium scoparium). Other common species 

include purpletop (Tridens flavus), Virginia wildrye 

(Elymus virginicus), silver bluestem (Bothriochloa 

laguroides), meadow dropseed (Sporobolus 

compositus), black needlegrass (Piptochaetium 

avenaceum), rosettegrasses (Dichanthelium spp.), 

Texas ironweed (Vernonia texana), hairy sunflower 

(Helianthus hirsutus), and Georgia rockrose 

(Helianthemum georgianum). Areas that receive 

less frequent fire have developed into habitats best 

described as close-canopied forests (Keith 2010c). 

These forests are also dominated by post oak (and 

sand post oak) in the overstory, vary from sparse 

to dense in the midstory, and generally possess a 

sparse herbaceous understory. The most common 

herbaceous vegetation in these forests is woodoats 

(Chasmanthium sessiliflorum), nutrush (Scleria 

oligantha), rosettegrasses (Dichanthelium spp.), caric 

sedges (Carex spp.), and black snakeroot (Sanicula 

canadensis). Common plant associations include the 

Post Oak-Blackjack Oak/Little Bluestem Woodland in 

the Post Oak Savanna Ecoregion and the Post OakBlackjack Oak Cross Timbers Woodland in the East 

and West Cross Timbers Ecoregions (Nature Serve 

2011) (Table 1). 

PRESCRIBED FIRE MANAGEMENT

There are few published prescriptions for effective 

oak woodlands and savanna burns in Texas. Available 

prescription parameters are more applicable to meeting 

objectives in grass-dominated fuels or open restored 

woodlands where there are sufficient herbaceous 

fuels to carry fire. As fire is excluded from an area, 

the ingrowth of understory and midstory vegetation 

shelters the surface fuels, preventing grasses and 

other herbaceous species from growing. The primary 

carriers of fire become leaf litter or a combination 

of leaf litter and shrubs versus a grass leaf-litter 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 135

combination. In these cases, fuel models change from 

a timber-understory (TU) to a timber litter (TL) fuel 

type (Scott and Burgan 2005). Fuel models in Texas 

fire suppressed oak woodlands, forests, and savannas 

can most commonly be categorized as either moderate 

load broadleaf litter (TL6) or moderate load, humid 

climate timber-shrub (TU2) (Tables 1 and 2) (Scott 

and Burgan 2005).

First entry burns in long unburned oak forest or 

savanna (Fuel Model TL6) can be difficult because 

the surface fuels are fully sheltered and have limited 

flammability. Under typical moderate prescriptions 

(RH >30, Winds <10 mph), we have observed only 

TL1 Forests with closed canopy juniper overstory and/or midstory. The 

understory is completely covered with juniper leaf litter and little or no 

woody or herbaceous fuels. Fire is carried predominantly by the juniper 

leaf litter.

No surface fire prescription

Requires high input management 

such as mechanical or herbicide

TL6 Upland forests with closed canopy hardwood (predominantly post oak 

and southern red oak) overstory and a relatively sparse midstory. The 

understory is sparse and covered with hardwood leaf litter. Very few 

herbaceous plants are present. Fire is carried predominantly by the 

hardwood leaf litter. 

Temperature: 40-90 °F

Relative humidity: 12-30%

Wind speed (mid flame): 6-18 mph

10-hour fuel moisure: ≤9%

TL8 Closed canopy forests dominated by pine. The midstory is sparse or 

composed of dense pine, and the understory is sparse and completely 

covered in a heavy layer of pine needles. Fire is carried predominantly 

by the pine needle litter.

Temperature: 40-75 °F

Relative humidity: 20-50%

Wind speed (mid flame): 4-12 mph

10-hour fuel moisure: 8-12%

TL9 Forests with a very close canopy overstory of hardwood or pine. The 

midstory is dense with woody species. This fuel type also describes 

midstory conditions with a dense pine needle drape primarily on 

yaupon. The understory is sparse with very dense hardwood litter 

or pine needles. Fire is carried by a combination of leaf litter and/or 

shrubs with heavy needle drape.

Temperature: 40-75 °F

Relative humidity: 28-65%

Wind speed (mid flame): 3-8 mph

10-hour fuel moisure: 9-15%

TU2 Closed canopy to moderately open canopy pine or hardwood forest 

overstories. The midstory is usually very dense with hardwood trees and/

or shrubs. The understory is dense and dominated by woody shrubs and 

saplings. Grass and other herbaceous plants are sparse. Fire is carried 

by a combination of leaf litter and understory shrubs.

Temperature: 40-80 °F

Relative humidity: 15-35%

Wind speed (mid flame): 4-12 mph

10-hour fuel moisure: <10%

TU3 Moderately open to very open canopy forests or woodland with pine or 

hardwood overstories. The midstory is sparse with few or no stems that 

don’t affect fire behavior. The understory is dominated by herbaceous 

species. Fire is carried by a combination of leaf litter and understory 

grass. This fuel model is often used to describe upland woodlands 

that are in a condition similar to those that existed prior to European 

settlement.

Temperature: 40-80 °F

Relative humidity: 20-60%

Wind speed (mid flame): 3-10 mph

10-hour fuel moisure: <12%

Table 2.—Fuel model descriptions relative to Texas oak communities. Prescription conditions are for 

initial burns with desired effects including topkill of understory woody vegetation.

Fuel Model Description Prescription

marginal, patchy burning with poor results for 

controlling woody invasive species in the understory 

and midstory. For restoration efforts to be effective, it 

is important to get a first entry burn intense enough to 

topkill the invading understory and midstory species. 

Research in other forested communities has 

determined a fire line intensity of 500 kW/m is needed 

to control (topkill) woody understory stems ≥1 m tall 

of the same genus (Sparks and others 1999). Using 

BEHAVE to estimate fire behavior of specific burns 

where management objectives were successfully 

achieved, we determined the fireline intensity of these 

burns was near or above the 500 kW/m threshold 
136 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

(Sparks, unpublished data). It is important to identify 

weather parameters needed to achieve a fireline 

intensity of 500 kW/m in the most common fuel 

models. In these invaded oak woodlands, it appears 

that this type of fireline intensity is only achievable 

under very extreme conditions (RH ≤25 percent; 

Winds >10 mph). 

Developing a Prescription for 

Long Unburned Oak Woodlands

We have spent the past 13 years attempting to use fire 

as the primary management tool for oak woodland/

savanna restoration. In addition, based on this 

experience we have attempted to develop prescriptions 

for restoring these vegetation communities with fire 

as the primary management tool. Through trial and 

error we have developed a prescription that is effective 

at pushing an intense fire through degraded, long 

unburned oak woodlands and topkilling the invasive 

mid- and understory woody species represented by 

fuel model TL6 (Tables 1 and 2). 

Early on we attempted fires with high winds (15-25 

mph) and moderate humidity (RH 25-40 percent) 

with the thought that wind would push fire through 

the oak leaf litter. We discovered that this worked 

some days and not others. We then conducted burns 

at lowered relative humidity (20-30 percent) and 

observed that high winds and low relative humidity 

often were effective, but not always. We then began 

to closely monitor fuel dryness, specifically 10-hour 

fuel moisture contents and time since a precipitation 

event. After several burns, we discovered 10-hour 

fuel moistures to be a critical component of the 

prescription. Even with moderate winds (6-12 mph), 

if 10-hour fuel moistures are less than 9 percent and 

relative humidity <30 percent, fires were generally 

intense enough to meet management objectives. 

However, the larger the unit, the higher the winds 

needed to be to ensure burn out within a given 

operational period.

Timing

We have determined that exact timing of the burn is 

not as critical as is achieving the other prescription 

parameters needed to produce a fireline intensity of 

500 kW/m. However, we have determined that we 

are more likely to meet prescription variables in late 

winter and early spring, when cold fronts drive down 

relative humidity, increase wind speeds and the longer 

days and warmer temperatures produce better drying 

conditions. Fall and early winter months can have 

days within prescription parameters, but leaf fall is 

often not until late November or early December, and 

days are short, reducing drying time between rain 

events. Longer days in early spring permit relative 

humidity to remain low and within prescription for 

several hours whereas in the winter it reaches its low 

in early afternoon hours after which it immediately 

begins to recover. In a typical year (during the last 10 

years or so), there are only a handful of days meeting 

all of these prescription parameters. During drier 

years, typically during a La Niña mode, the number 

of potential days increases dramatically. For example, 

during winter and spring of 2010, observed fuel 

moistures rarely were within prescribed parameters, 

but in 2011 observed fuel moistures were within the 

defined prescription parameters nearly weekly and 

often for multiple days at a time. Because of rapidly 

changing conditions it is important to be ready and not 

pass up a potential burn day.

Monitoring 10-Hour Fuel Moisture

We used 10-hour fuel moisture sticks comprised of 

four connected ponderosa pine dowels and the Forester 

Fuel Moisture Scale (Model 11552) to measure 10-

hour fuels (Davies and McMichael 2005). Through 

comparisons of our observed readings and those from 

Remote Area Weather Stations (RAWS) we have 

determined fuel moisture stick measurements to be 

less variable within a day, especially as fuel moistures 

are in the 6-15 percent range. Due to this variability, 

we recommend land managers utilize on site 10-hour 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 137

fuel moisture to guide their prescribed fire planning 

instead of data derived from RAWS stations. With 

respect to planning, it is recommended to begin 

looking for an acceptable burn window when the onsite fuel moisture reaches 12 percent for more than 2 

consecutive days. 

Fire Control

The above prescription has proven to be very effective; 

however it can produce extreme fire intensities and 

carries greater risk and costs than typical cool-season 

maintenance burns. This prescription should only be 

attempted by experienced fire crews with substantial 

preparation such as using well established fire breaks 

(bare mineral soil) and having a contingency plan and 

on-site contingency resources.

Burning under these prescription parameters will 

increase the likelihood of igniting snags and logs, thus 

increasing the time for mop-up and residual smoke. If 

maintaining snags and logs is a critical management 

objective, proper mitigation procedures should be 

established prior to ignition to protect them. The 

intensity of fires under these prescription variables will 

most likely generate new snags within the unit, and if 

the first entry fire is successful, subsequent fires can be 

conducted under less severe conditions, reducing risk 

of losing future snags and logs. Under these conditions 

embers generated by the fire can go unnoticed for 

hours or even days, increasing the chances for spotting 

well after an area has been burned. “Punky” downed 

logs or snags are more susceptible to glowing embers 

than surrounding oak leaf dominated fuels. Embers 

may smolder for up to 4 hours in these “punky” fuels 

before generating enough heat to start a fire and catch 

the surrounding area on fire. It is recommended that a 

crew remain on site to patrol for an extended period of 

time following one of these intense restoration burns.

Fuel Model Transition

Fuel models TL6 and TU2 (Table 2) best describe 

fire suppressed habitats with little to no herbaceous 

material in the understory that require severe 

conditions to produce a fire intense enough to meet 

management objectives during the first burn cycle 

or two. As the understory and midstory become 

suppressed by the initial fire treatments and light 

reaches the forest floor, grasses and forbs flourish, 

and the fuel model may transition into a TU3. The 

TU3 fuel model can be burned under more moderate 

conditions and still meet management objectives of 

woody control. 

Fire Effects on Vegetation

The inherent abilities of plants to respond to fire 

depend partially on the fire regime to which the plant 

community has adapted (NWCG 2001). Based on 

rapid regrowth and ability of understory plants to 

resprout, most of the plant species common in the 

Oak Woods and Prairies have adapted to frequent and 

often intense fires. In these long unburned habitats, the 

amount of dead woody fuel, depth of litter and duff 

layers, and amount of dead material within or around a 

living plant may be greater than would have typically 

occurred historically when fires occurred relatively 

frequently. In this situation, the effects of fire on 

vegetation are likely very different than it would have 

been under historic conditions because of the higher 

temperatures and longer durations of fires. 

Fire-related plant tissue mortality is dependent upon 

both the temperature reached and the duration of time 

the tissue is exposed to that temperature. The lowest 

temperature at which plant cells die is between about 

50 to 55 °C (122 to 131 °F) (NWCG 2001). Killing all 

belowground reproductive structures usually occurs 

only where there is a long duration surface heat source, 

such as beneath a large pile of woody debris that 

sustains almost complete combustion (NWCG 2001). 

The severity of burn relates to the depth of the litter 

layer beneath the vegetation and its moisture content 

when the fire occurs (NWCG 2001). These high 

severity conditions of initial burns typically results in 

consumption of all litter and organic matter beneath 

shrubs and killing of all buds and roots in or near the 

organic layer. This kind of fire favors shrubs with buds 

and roots buried deep enough that they escape lethal 

temperatures. Fires which occur where there are deep 
138 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

accumulations of litter beneath shrubs and isolated 

trees or significant amounts of dead lower branches 

that burn off and smolder beneath a shrub crown are 

more likely to lethally heat roots and reproductive 

structures than a fire that occurs where there is sparse 

litter and few dead branches. 

Tree mortality is often the result of injury to several 

different parts of the plant, such as crown damage 

coupled with a high percentage of cambial mortality. 

Mortality may not occur for several years following 

a fire. Death can occur from secondary infection by 

disease, fungus, or insects because the resistance of 

plants to these agents is often lowered by injury, and 

wound sites provide an entry point for pathogens 

(NWCG 2001). A tree weakened by drought, either 

before a fire or after wounding, is also more likely to 

die (Dickinson and Johnson 2001). A strong negative 

relationship exists between burn severity and postfire 

sprouting (based on personal observations). 

High severity fires occur when large dead fuels and 

organic layers are dry (<12 percent 10-hour fuel 

moisture). These fires typically consume all litter, 

twigs, and small branches, most or the entire duff 

layer, and some large diameter dead, down woody 

fuels, particularly rotten material. Significant soil 

heating occurs, especially near fuel concentrations. 

Post oak often possesses relatively thick bark that 

will protect it from moderately intense fires that could 

damage the cambium. However, overstory post oak 

trees can be killed in high severity fires, particularly in 

areas where burning of dense fuel concentrations at the 

base of individual trees leads to localized intensities 

that kill the cambium and/or canopy buds. 

Common woody species such as yaupon, American 

beautyberry, and saw greenbriar have thick, deep root 

caudices or tubers that aggressively resprout from the 

base of the plants following fire, including intense 

fires that occur in long unburned habitats. Other 

woody encroaching species such as winged elm and 

eastern redcedar rapidly colonize bare soil created 

by fire. Repeated and frequent fires (<2 years) are 

often necessary to kill the entire plants. Resprouting 

woody species after two or three fires continue to 

resprout but are often less vigorous and produce 

fewer stems. Reducing the total cover of these woody 

encroachers and creating open canopies under dead 

overstory trees then allows native perennial early 

successional herbaceous species such as broomsedge 

(Andropogon virginicus) and purpletop to begin to 

colonize. Herbaceous species adapted to these firesuppressed habitats such as woodoats and nutrush 

also readily resprout from root bases and are seldom 

completely killed by these intense fires. Woodoats 

often becomes very dense in these severely burned 

areas immediately following fire. Early successional 

herbaceous species such as rosettegrasses, fireweed 

(Erechtites hieracifolia), and American pokeberry 

(Phytolacca americana) also colonize the bare soil 

created by these intense fires and often temporarily 

become the dominant understory plants. These annual 

species rapidly disappear in successive years following 

these high severity fires. As native herbaceous species 

gradually become more common and the woody 

encroachers are reduced, fire climax species such 

as little bluestem can slowly begin to colonize and 

eventually become common in the understory.

ACKNOWLEDGMENTS

Funding was provided through Texas Parks and 

Wildlife Department, State Parks Division, and State 

Wildlife Grant T-33 from the U.S. Fish and Wildlife 

Service. We thank J. Cantrell and N. Shipman for data 

entry and analysis. G. Creacy, G. Gillman, C. Kinkead, 

and two anonymous reviewers provided helpful 

comments, and J. Estes assisted in creating maps and 

figures. We thank the State Park Wildland firefighters 

for field assistance and data collection. 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 139

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The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
142 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

FIRE MANAGEMENT AND WOODY INVASIVE PLANTS 

IN OAK ECOSYSTEMS

Joanne Rebbeck

Research Plant Physiologist, U.S. Forest Service, Northern Research Station, 359 Main Road, 

Delaware, OH 43015. To contact, call 740-368-0054 or email at jrebbeck@fs.fed.us.

Abstract.—The use of prescribed fire to sustain oak forests has increased rapidly in the 

last decade as the threat of poor regeneration and increased dominance of shade tolerant 

or fire sensitive tree species grows. While prescribed fire can favor oak regeneration, 

it may also increase the invasion and expansion of nonnative invasive plant species 

(NNIS). Little is known about the effects of fire on invasives in eastern U.S. oak forests. 

The majority of knowledge regarding the response of NNIS is anecdotal as managers 

have reported the expansion of invasives such as tree-of-heaven (Ailanthus altissima) 

and princess tree (Paulownia tomentosa) following prescribed fires. How can prescribed 

fire be used so that it does not facilitate the expansion of NNIS? Managers need to 

be proactive and integrate NNIS control strategies into prescribed fire and timber 

management programs at a landscape level. This paper presents a review of the current 

state of knowledge regarding woody NNIS and the use of prescribed fire in the Eastern 

United States. It includes a summary of the common traits of NNIS, potential responses 

of woody NNIS to fire, proactive approaches to managing for NNIS, and a list of 

recommended resources related to NNIS and forest management practices. In addition, 

an overview of the author’s current work on the effects of prescribed fire on Ailanthus in 

southeastern Ohio is presented. 

Introduction

Active fire suppression and the conversion of former 

agricultural lands over the last 80 plus years have 

produced dramatic changes in forest structure and 

composition within the eastern United States (Dibble 

and others 2008). Fire intolerant species such as red 

maple (Acer rubrum L.) often dominate the sapling 

and midstory layer creating dense shade conditions. 

In contrast, oaks (Quercus spp.) are disturbancedependent species (Abrams 1996). Forest managers 

often utilize some combination of harvesting, fire, 

and herbicide treatments which alter light levels to 

favor oak establishment (Brose and others 2008). 

Unfortunately, many nonnative invasive plants also 

have the potential to thrive in these same disturbed 

habitats or open conditions. Oaks have many 

disturbance-type adaptations that confer protection 

from fire, such as root-centered growth, thick bark, 

vigorous sprouting ability, and well-protected buds 

(Dey and Fan 2009). However, they do not compete 

well with faster growing native and nonnative plant 

species, especially on higher quality sites (Johnson 

and others 2009). It is likely that competition between 

oaks and nonnative invaders can also occur on dry, 

low fertility sites since some woody nonnative plants 

(e.g., Ailanthus, Paulownia) can thrive on poor sites. 

Nonnative plant species have become established 

at varying densities and distributions within forest 

edges and interiors. There are some NNIS species, 

such as the shade tolerant oriental bittersweet 

(Celastrus orbiculatus), which becomes established in 

undisturbed forest canopies. Once established, it and 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 143

many other NNIS can persist for extended periods in 

a suppressed condition until a disturbance occurs that 

increases light and other resources, allowing rapid 

growth and expansion. 

Reintroducing fire to oak ecosystems may increase 

susceptibility to nonnative plant invasion which may 

impede the restorative effects of burning. Recent 

work suggests fire alone does not increase light 

levels enough to favor the growth of regenerating oak 

(Hutchinson and others 2005). However, prescribed 

fire following a shelterwood harvest has been a 

successful prescription to promote oak recruitment and 

retention (Brose and Van Lear 1998). This treatment 

creates a higher level of disturbance than fire alone, 

and thus increases concerns of NNIS expansion. When 

invasive plants are present or nearby, forest managers 

have reported increases in their abundance following 

prescribed burns plus timber harvesting. 

Management recommendations to control NNIS 

within eastern forests have improved in the last 

decade (Evans and others 2006, Webster and others 

2006). Until recently there has been limited research 

addressing how NNIS respond to fire in the Eastern 

United States. Huebner (2006) evaluated 17 common 

invaders for their response to fire and their potential 

to alter fire regimes. She reported that 12 species were 

potentially controllable with repeated growing season 

burns while 5, including Ailanthus, had the potential to 

increase in abundance in response to fire. Kuppinger 

and others (2010) found that Paulownia quickly 

established across varying habitats immediately after 

fire but over time failed to persist except in resourcelimited habitats. The use of fire to control NNIS in 

the East has been tested with a few species such as 

Japanese stiltgrass (Microstegium vimineum) and 

Japanese barberry (Berberis thunbergii) with some 

success (Flory and Lewis 2009, Ward and others 

2009). However, using prescribed fire to control 

NNIS should proceed with caution given the sparse 

information currently available. In this paper, I focus 

on how biological and ecological traits of woody 

invasive species are intertwined in predicting the 

impact of fire and other management activities on their 

abundance and expansion. The use of prescribed fire to 

control NNIS will not be addressed. I give an overview 

of an ongoing study of the effects of fire on Ailanthus, 

as well as an efficient and cost-effective invasive plant 

mapping tool. A proactive NNIS management action 

list is also provided.

COMMON TRAITS 

OF INVASIVE SPECIES

Whether the management goal is to promote or to 

control a given species, it is important to understand 

its biology. Knowledge of an invasive plant’s life 

history is critical to predicting how it might respond to 

fire and other management treatments. Consideration 

must be given to its life form. Is it an annual, biennial, 

woody perennial tree, shrub, or vine? Is it dioecious, 

producing male and female plants such as Ailanthus, 

common buckthorn (Rhamnus cathartica), and 

autumn olive (Elaeagnus umbellate)? Monitoring 

the local seasonal patterns of a species’ growth to 

include time of leaf break and leaf drop, flowering, 

and onset of dormancy is invaluable in developing the 

most effective fire, mechanical, or chemical control 

treatments. If treatments occur during periods when 

energy reserves are at their lowest levels, they will be 

most effective in reducing sprouting compared with 

periods of higher reserves. 

Disturbance-dependent species are often shade 

intolerant and drought tolerant. They often have rootcentered growth with large carbohydrate stores which 

can be readily utilized when growth-limiting shade 

is removed. Some NNIS such as Ailanthus produce 

extensive root systems that share carbohydrate 

reserves that support multiple shoots growing across 

large areas in varying light environments. Conversely, 

shade intolerant species display shoot-centered growth, 

quickly occupying space and gaining competitive 

height over slower-growing species. 

Shade tolerant NNIS such as Amur honeysuckle 

(Lonicera maackii) typically are the first to leaf out in 
144 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

the spring and last to drop leaves in fall. The Oriental 

bittersweet vine can grow and persist in undisturbed 

forests until a canopy disturbance releases it to grow 

rapidly (Webster and others 2006). Linking the timing 

of fire and other methods of control to low energy 

reserves is essential to limit invasives. The challenge 

lies in trying to minimize harmful effects on native 

vegetation while at the same time controlling the 

NNIS.

There are a number of traits that are often associated 

with invasive nonnative plants. These may include but 

are not limited to: (1) ability to sprout, (2) prolific 

seed production, (3) seed dispersal by wind or birds, 

(4) rapid growth rate, (5) early age to seed production, 

(6) ability to form pure stands, and (7) presence in 

early successional plant communities.

Other important attributes of NNIS to consider 

include: (1) how long do seeds remain viable; (2) is 

the plant allelopathic (i.e., does it produce chemicals 

that inhibit native seed germination and seedling 

establishment); (3) is the species shade tolerant; and 

(4) can it persist suppressed in the understory for 

extended periods of time? These are all crucial in 

understanding how individual NNIS may respond 

to fire and other disturbances. Unfortunately, basic 

biological and ecological information is incomplete 

or lacking for a number of the common NNIS found 

in eastern U.S. oak forests, as demonstrated by the 

summary provided in Table 1.

POTENTIAL RESPONSES TO FIRE

It is expected that many woody NNIS will respond 

to prescribed fire in a similar manner to that of native 

vegetation. Common responses and postfire conditions 

that favor early successional invasives can include:

• Stem topkilling with resprouting. Depending 

on fire severity and timing of the fire, stems 

may be topkilled followed by the sprouting of 

dormant buds. Ailanthus is a prolific sprouter 

with an extensive shallow root system with 

many potential bud sources (Kowarik and 

Saumel 2007). Like oak, it appears to respond 

positively to fire with vigorous sprouting. But 

unlike oak, it can also expand by vigorous root 

suckering similar to aspen and sassafras (Burns 

and Honkala 1990).

• Increased understory light and available soil 

nutrients. Increases in resource availability 

often favor the growth and expansion of NNIS. 

• Consumption of litter layer and exposure 

of mineral soil. As with oak, these conditions 

often favor seed germination and seedling 

establishment, especially those that require light 

for germination such as Paulownia. 

• Soil disturbance. Site preparation such as fire 

breaks can create exposed bare soil.

• Spread by equipment. Movement of dozers, 

trucks, and other vehicles from one site to 

another can facilitate the spread of invasive 

plants across a landscape. Both seeds and small 

viable vegetative fragments can be transported. 

In addition, topographic effects on fire severity and 

intensity can create a variety of microsites within a 

burned landscape. If thinning treatments are combined 

with a prescribed fire or if a fire is severe enough to 

cause overstory mortality, patches of invasive plants 

can occur in the openings). This can promote NNIS 

movement towards forest interiors. Depending on site 

features and fire severity, postfire competition among 

new propagules (e.g., wind-blown or bird-dispersed 

seeds) or sprouts can be very high. Consideration 

must be given to the ability of a NNIS to successfully 

occupy a site after a burn as well as its ability to 

reproduce in that post-disturbance community. 

CURRENT STATE OF KNOWLEDGE

A comprehensive synthesis of available scientific 

and technical information regarding the interactions 

between fire and nonnative invasive plants is available 

through the U.S. Department of Agriculture Forest 

Service’s Fire Effects Information System (FEIS) 

(USDA FS 2012). Detailed information for each of 69 

invasive species includes: distribution and occurrence, 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 145

TreesAilanthus(tree-ofheaven),†

A. altimissa

moderate dioecious very high 

(>200,000 /female)

wind ~5 yrs 1-2 yrs? rapid 

(3-6 ft/yr)

vigorous high; forms dense 

thickets

early, but can persist 

Norway maple, Acer platanoides

very tolerant 

dioecious high wind ? 1 yr? moderate? limited suppression via 

dense shade

early, but persists

Paulownia(princess/empress tree), Paulownia tomentosa

intolerant perfect 

flowers

very high (>20 million/tree)

wind 3-5 yrs 2-3 yrs rapid 

seedling & sprout growth

very high transient, high 

as seedling; less with age

early, can persist

ShrubsAutumn olive, Elaeagnus umbellata

moderate primarily 

dioecious

very high (66,000 /mature shrub)

birds 3-5 yrs ? ? vigorous displaces natives, 

can form dense thickets

early

Bush honeysuckles, (Amur) Lonicera spp.

moderate to tolerant

perfect flowers, not-well studied

variable, up to 1 million/plant

birds 5-8 yrs ~2-3 yrs Rapid in high 

light

yes leaves first to 

expand & last to drop; rapid seedling height growth 

early, but can persist as large dense mature shrubs

Common buckthorn, Rhamnus cathartica

tolerant typically 

dioecious

heavy gravity and 

birds

5-6 yrs several yrs medium to 

fast

yes forms dense 

thickets

varies: early and mid-late

Japanese barberry, Berberis thunbergii

tolerant perfect 

flowers

varies with genotype

birds ? ~1 yr varies with 

light

yes form dense 

thickets

early, but persists

Multiflora rose, Rosa multiflora

tolerant ? 500,000/yr gravity & 

birds

? 10-20 yrs ? yes form dense 

impenetrable clumps

early

Privet (Chinese, European, & Japanese), Ligustrum spp.

moderate to tolerant

perfect flowers

hundreds/ mature shrub

birds ? none not reported yes form dense 

thickets

early, but can persist

Common and 

Latin 

Name

Shade 

Tolerance

Breeding 

System

Annual Rate 

of Seed 

Production

Seed 

Dispersal

Age to 

Produce 

Seed Seed Bank

Growth Rate

Sprouting 

Ability

Competitive 

Ability

Successional 

Status

Table 1.—Ecological and biological traits of common problem nonnative woody invasives in eastern U.S. oak forests*

(Table 1 continued on next page)
146 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference Vines Japanese honeysuckle, Lonicera japonica moderate to tolerant requires cross- fertilization prolific birds 3-5 yrs ? rapid once established yes aggressive colonizer, creates dense mats & thickets early, but persists Kudzu, Pueraria montana var. lobata shade intolerant

? infrequent infrequent 

seeder

3 yrs ? rapid (65-98 

ft/yr)

high aggressive 

asexual colonizer

early, but persists 

Oriental bittersweet, Celastrus orbiculatus

tolerant & intolerant

both dioecious & perfect 

abundant birds ? 1 yr rapid postdisturbance high overtops and girdles, can form 

thickets

early, but persists

Common and 

Latin 

Name

Shade 

Tolerance

Breeding 

System

Annual Rate 

of Seed 

Production

Seed 

Dispersal

Age to 

Produce 

Seed Seed Bank

Growth Rate

Sprouting 

Ability

Competitive 

Ability

Successional 

Status

Table 1 (continued).—Ecological and biological traits of common problem nonnative woody invasives in eastern U.S. oak forests*

*Primary reference source is the Fire Effects Information System Database (USDA FS 2012)†Demonstrated to be allelopathic

? Represents lacking or unknown information
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 147

botanical and ecological characteristics, fire effects, 

and management considerations. In 2011, the FEIS 

staff summarized the knowledge gaps of eastern 

U.S. invasive plants (Gucker and others 2011). They 

concluded that current information in the eastern 

United States is very limited and largely anecdotal. In 

addition, the transfer of research findings to managers 

needs improvement so they can make better informed 

decisions. They also recommend more experiments 

and observations of how NNIS respond to fire, 

including: (1) several years of data in a particular 

ecosystem, (2) various burning conditions, (3) season 

of burn, (4) varying fire severities, and (5) varying 

intervals between burns. It is noteworthy that these 

same research questions are also critical in developing 

better fire prescription guidelines for promoting oak 

restoration.

In 2008, the federal interagency Joint Fire Science 

Program (JFSP) made a request for research proposals 

that specifically addressed the interaction of invasive 

plants and fire in the eastern United States. Two main 

questions were addressed. First, what are the effects 

of nonnative invasive plant species on fire behavior 

and fire regimes? Secondly, what are the effects of fire 

and fire management on the distribution of NNIS? The 

three funded studies are:

1. Fire and the invasive Japanese stiltgrass 

(Microstegium vimineum) in eastern deciduous 

forests. Principal investigators: S. Luke Flory 

and Keith Clay, Indiana University. 

2. To burn or not to burn Oriental bittersweet 

(Celastrus orbiculatus): a fire manager’s 

conundrum. Principal investigators: Noel 

B. Pavlovic and Stacey Leicht-Young, U.S. 

Geological Survey.

3. Prescribing fire in managed oak forest 

landscapes: interactions with the invasive tree 

Ailanthus altissima. Principal investigators: 

Joanne Rebbeck and Todd Hutchinson, U.S. 

Forest Service.

Research questions for each project are provided in 

Table 2. Since all are active at this writing, annual 

project reports and updated deliverables are available 

at the JFSP website http://www.firescience.gov/JFSP_

Search_Advanced.cfm. Future technical publications 

are planned with management recommendations. An 

overview of the Ailanthus project in Ohio follows.

Plant species Life form Study location Research questions

Japanese stiltgrass Annual grass Big Oaks National 

Wildlife Preserve, 

SE Indiana 

How do stiltgrass invasions affect fire behavior? 

How do prescribed fires and timing of fires affect invasions? 

Do invasions alter the effects of fire on native species 

 and habitats? 

Can fire be used as a tool to manage invasions?

Oriental bittersweet Perennial vine Indiana Dunes 

National Lakeshore, 

Lake Michigan

How does fire impact seed viability? 

How does fire influence the susceptibility of different habitats 

 to invasion? 

What are the effects of fire on established plants? 

Can bittersweet presence and abundance be predicted 

 in a fire landscape?

Ailanthus Tree Tar Hollow State 

Forest, SE Ohio

What is the influence of past harvesting and fire history 

 on the distribution and abundance of Ailanthus 

 in a forested landscape? 

What are the direct effects of fire on the demography 

 of Ailanthus populations?

Table 2.—Summary of research questions of Joint Fire Science Program funded projects investigating the 

interaction of fire and nonnative invasive plants in the eastern United States 
148 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

FIRE AND AILANTHUS 

IN SOUTHEASTERN OHIO: 

A CASE STUDY

Background

Ailanthus is a common NNIS in the eastern United 

States and can invade and expand dramatically when 

forests are disturbed. It is extremely fast-growing, 

reaching heights of 80-100 feet. It is dioecious and is a 

prolific seeder with up to 350,000 seeds produced per 

tree in a single growing season (Kowarik and Saumel 

2007). Seeds develop in the summer mature in early 

fall and can persist until March. Wind-dispersed seeds 

can travel in excess of 330 feet (Landenberger and 

others 2007). The longevity of seeds in soil is not fully 

known. It appears that seeds are short-lived, typically 

1-2 years, but germination rates are very high (80-100 

percent) in disturbed stands. In addition, Ailanthus

is capable of aggressive clonal spread, often creating 

dense thickets that can outcompete native trees. While 

considered shade intolerant, clonal sprouts attached to 

a parent tree can persist in a shaded forest understory 

for up to 20 years (Kowarik 1995). Vigorous sprouts 

can develop 50-90 feet from a parent tree (Illick and 

Brouse 1926). Although the long-term effects of 

Ailanthus on native tree regeneration are not known, 

it likely has a negative impact because of its highly 

competitive traits and production of the allelopathic 

compound ailanthone (Hiesey 1996).

Very little is known about the direct and immediate 

effects of fire on Ailanthus. Saplings are easily 

topkilled by fire, but resprouting is prolific (Lewis 

2007). Managers have reported observing increases in 

Ailanthus via seed germination immediately following 

fires. However, in landscapes with very small 

populations of Ailanthus, it does not invade burned 

sites (e.g., Hutchinson and others 2005). It remains 

unknown whether a postburn Ailanthus expansion 

will inevitably occur if the propagule pressure is high. 

It may be that fire, by reducing litter and increasing 

light, creates improved conditions for Ailanthus

establishment as other disturbances have been shown 

to do (Kota and others 2007). 

At Tar Hollow State Forest in southeastern Ohio, 

thinning and burning treatments were conducted as 

part of the national Fire and Fire Surrogate Study. 

The explosive expansion of Ailanthus from seed 

followed the combined thin plus burn treatment 

(Hutchinson and others 2004, Rebbeck and others 

2005). Ailanthus trees (≥4 in d.b.h.) were present but 

not abundant in this unit prior to treatment, and no 

seedlings were observed. Both treatments occurred in 

the same dormant season, and 2 years later, Ailanthus

seedlings were present in 96 percent of plots at a mean 

density of >5000 per acre. However, it appears that the 

combination of propagule pressure and disturbance 

may have been critical, because in the adjacent thin 

only and burn only units, there were few if any adult 

Ailanthus prior to treatment (low propagule pressure) 

and there was not a large increase in Ailanthus after 

those treatments. 

The Ohio Department of Natural Resources, Division 

of Forestry has an active prescribed fire program to 

sustain oak forests (Bowden 2009). Between 2001 

and 2008, a total of 14 prescribed fires have been 

applied to 2,100 acres within a 9,600 acre portion of 

the Tar Hollow State Forest. The goal of our research 

project is to gain a better understanding of how the 

distribution and abundance of Ailanthus is related 

to recent fires, past timber harvesting, seed sources, 

and other landscape and stand characteristics. The 

study area is located within the Southern Unglaciated 

Allegheny Plateau. The topography is highly dissected, 

consisting of sharp ridges, steep slopes, and narrow 

valleys. 

Research Approach

Geo-referenced digital aerial sketch mapping 

technology (DASM) (Schrader-Patton 2003) in a 

low-flying helicopter was employed to identify seedproducing female trees and patches of Ailanthus in 

winter 2008 when persistent seeds were highly visible 

(Fig. 1). During a 2 hour flight, 98 seed-bearing 

females and 42 patches, ranging in size from 0.44 

to 33 acres, were identified within a 9600 acre area 

(Rebbeck and others 2010). Aerially-identified females 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 149

were ground-truthed with 95.7 percent accuracy using 

hand-held Global Positioning System (GPS) units. The 

method appears to be an effective and efficient tool 

to map the distribution of Ailanthus seed sources in 

a landscape. Additional aerial mapping of more than 

164,000 acres is underway in cooperation with the 

Wayne National Forest and Ohio Division of Forestry. 

In the course of 6 days, 78,000 acres were surveyed 

on the Wayne National Forest at an estimated cost of 

$0.40 per acre.

A systematic grid of research plots was installed to 

quantify the abundance, size, and age distribution 

of Ailanthus, as well as other stand attributes (e.g., 

fire, harvesting, and stand structure). Past timber 

harvest records were digitized and incorporated into 

a Geographic Information System (GIS) database. 

Current data analysis includes GIS and statistical 

techniques such as classification and regression trees 

(CART) and Random Forests (Prasad and others 

2006) to determine the relationships of Ailanthus Figure 2.—Basal sprouting of topkilled Ailanthus tree 

10 weeks after early spring prescribed fire.

Figure 1.—Aerial view of female Ailanthus trees with seeds 

during a 2011 winter helicopter survey on the Marietta 

District of the Wayne National Forest. Photo is courtesy of 

Tom Shuman, ODNR Division of Forestry.

presence and abundance to distance and direction 

from seed-producing trees, fire, timber harvest, and 

other landscape attributes. Relationships are being 

tested to determine the extent to which burning and/or 

harvesting favors the spread of the Ailanthus and to 

determine possible mechanisms of its expansion in this 

landscape.

To gain a better understanding of how Ailanthus

responds to fire, replicated research plots were 

installed in 2009 to study the direct effects of 

prescribed fire and herbicide treatments on Ailanthus

demography and spread. Herbicide stem injections 

of Ailanthus (hack-n-squirt with imazapyr) were 

completed in autumn 2009, and prescribed burns were 

completed in April 2010. Treatment effectiveness and 

postburn survival, topkill, sprouting, and establishment 

of Ailanthus are being monitored for three postburn 

growing seasons (Figs. 2 and 3). If Ailanthus

successfully establishes and remains competitive, a 

second fire may be needed. A field tour and workshop 

as well as accompanying technical publications are 

planned to provide guidance on conducting prescribed 

fires in the presence of Ailanthus within managed oak 

forest landscapes.
150 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Figure 3.—Abundant Ailanthus regeneration on forest floor 

within gap created from an herbicide plus prescribed burn 

treatment.

RECOMMENDATIONS: PROACTIVE 

MEASURES FOR MANAGING

INVASIVES

Benjamin Franklin’s famous quote, “an ounce of 

prevention is worth a pound of cure” could be the 

centerpiece for adopting a proactive management 

approach of NNIS. It is much more efficient to 

eradicate a newly-introduced small NNIS population 

than control one that is large and well-established 

(Fig. 4). The U.S. Department of Agriculture (USDA) 

recommends utilizing early detection and rapid 

response management of invasive species and has a 

manager’s tool kit at the National Invasive Species 

Information Center (http://www.invasivespeciesinfo.

gov/toolkit/detection.shtml). 

These are my recommended guidelines in the 

development of a successful management plan. 

However, keep in mind that some of these suggested 

guidelines may be extremely challenging to 

implement.

• Actively monitor for invasives.

• Develop “invasive plant” awareness in field 

staff.

• Know what invasives are present and learn their 

life histories.

• Stay current on new emerging invasive plants.

• It is easier to control a small population than 

large one.

• Eliminate invasives before they start 

reproducing.

• Focus treatment efforts on seed-bearing trees to 

minimize dispersal.

• Eliminate populations well in advance of a 

silviculture treatment such as fire or harvest 

(time required will depend on longevity of seed).

• Careful monitoring and follow-up is essential. 

Don’t assume that the treatment was effective.

• Take a landscape approach to management. 

Observe adjoining stands and properties.

Engage surrounding property owners to control 

invasives. Partner with other groups and work 

within a local cooperative weed management 

area.

• Use the appropriate herbicide with the 

appropriate method at the appropriate time of 

the year for more effective chemical control. 

Only stem inject woody perennials in fall when 

resources are being translocated to roots.

• Adopt clean sanitation practices. Keep logging 

or other cutting equipment clean to minimize 

spread. Use clean gravel and native seed mixes.

• Follow a triage treatment approach to focus on 

the least infested areas first. If may be more 

practical and efficient to only remove seed 

sources from extremely infested areas and ban 

any other silvicultural treatments.

• Utilize or develop a decision support system to 

prioritize treatment areas.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 151

Figure 4.—Public awareness of invasive plants typically occurs after complete eradication is unlikely, increasing efforts and 

costs of control.

RECOMMENDED RESOURCES

1. Mistaken Identity? Invasive Plants and their 

Native Look-alikes: an Identification Guide for the 

Mid-Atlantic. A wonderful color photo guide with 

side by side comparisons of native and invasive plants 

that are difficult to distinguish. 

Sarver, M.; Treher, A.; Wilson, L. [and others]. 

2008. Dover, DE: Delaware Department of 

Agriculture. Mistaken identity? Invasive plants 

and their native look-alikes: an identification 

guide for the Mid-Atlantic. Available at 

http://weblogs.nal.usda.gov/invasivespecies/

archives/2009/02/mistaken_identi.shtml.

2. Fire Effects Information System (FEIS) Invasive 

Plants List. This is a great resource, a one stop 

information portal for distribution and occurrence, 

biological and ecological characteristics, and 

management. It synthesizes available fire effects 

research on given species (includes peer reviewed and 

nonpeer reviewed literature). It was updated in 2011 

to include 80 nonnative invasive plant species. Use 

caution when applying fire and management responses 

to other ecosystems and geographic regions. 
152 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

U.S. Department of Agriculture, Forest Service. 

2012. Fire Effects Information System, [Online]. 

Invasive plants list. U.S. Department of 

Agriculture, Forest Service, Rocky Mountain 

Research Station, Fire Sciences Laboratory. 

Visit the following to access FEIS: www.fs.fed.

us/database/feis/plants/weed/index.html.

3. Wildland Fire in Ecosystems: Fire and Nonnative 

Invasive Plants. An extensive review of information 

on NNIS and wildland fire. It covers a wide range 

of topics including management planning with an 

emphasis on the western United States. 

Zouhar, K.; Smith, J.K.; Sutherland, S.; Brooks, 

M. L. 2008. Wildland fire in ecosystems: fire 

and nonnative invasive plants. Gen. Tech. 

Rep. RMRS-GTR-42-vol. 6. Ogden, UT: U.S. 

Department of Agriculture, Forest Service, 

Rocky Mountain Research Station. 355 p. 

Available at http://www.treesearch.fs.fed.us/

pubs/30622.

4. Invasive Plant Responses to Silvicultural 

Practices in the South. A guide to assist foresters and 

managers in the southern United States in developing 

management plans to reduce invasive plants. It is a 

good overview of integrating vegetation management 

guidelines and control techniques with silvicultural 

practices for other eastern U.S. regions. 

Evans, C.W.; Moorhead, D.J.; Bargeron, C.T.; 

Douce, G.K. 2006. Invasive plant responses to 

silvicultural practices in the south. BW-2006-03. 

Tifton GA: The University of Georgia Bugwood 

Network. 52 p. View or download publication at 

http://www.invasive.org/silvicsforinvasives.pdf. 

5. A Field Guide for the Identification of Invasive 

Plants in Southern Forests. An update of the 2003

edition. The guide displays distinguishing plant 

features throughout the year for accurate identification 

of 56 problematic invasive plants. Many species are 

found throughout the eastern region. 

Miller, J.H.; Chambliss, E.B.; Loewenstein, 

N.J. 2010. A field guide for the identification of 

invasive plants in southern forests. Gen. Tech. 

Rep. SRS-119. Asheville, NC: U.S. Department 

of Agriculture, Forest Service, Southern 

Research Station. 126 p. View or download 

publication at http://www.treesearch.fs.fed.

us/pubs/35292.

6. A Management Guide for Invasive Plants in 

Southern Forests. A companion to the Southern 

Forests Field ID guide described above. It provides 

great information on current management strategies 

and procedures for 56 invasive plants in a variety of 

habitats. Good overview on organizing, planning, and 

enacting invasive plant management and prevention 

programs. 

Miller, J.H.; Manning, S.T.; Enloe, S.F. 2010. 

A management guide for invasive plants in 

southern forests. Gen. Tech. Rep. SRS-131. 

Asheville, NC: U.S. Department of Agriculture 

Forest Service, Southern Research Station. 120 

p. View or download publication at http://www.

treesearch.fs.fed.us/pubs/36915.

7. Invasive Plants Field and Reference Guide: An 

Ecological Perspective of Plant Invaders of Forests 

and Woodlands. A handy ringed laminated guide 

suitable for field work. Provides key information for 

the accurate identification of invasive species, and 

gives a scientific synthesis of what is known about the 

behavior of these species in managed, disturbed, and 

pristine forested systems. 

Huebner, C.; Olson, C.; Smith, H. 2005. Invasive 

plants field and reference guide: an ecological 

perspective of plant invaders of forests and 

woodlands. NA-TP-05-04. U.S. Forest Service, 

State and Private Forestry, Northeastern Area. 

View or download publication at http://www.

treesearch.fs.fed.us/pubs/19822.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 153

8. A Guide to Nonnative Invasive Plants 

Inventoried in the North by Forest Inventory and 

Analysis. The intent of this guide is to aid FIA field 

staff in identifying 44 invasive plant species in the 24-

state Northern Research Station region (Maine south to 

Delaware west to Kansas and north to North Dakota). 

However, this guide can be used by anyone interested 

in learning about these invasive plants. It contains 

distribution maps, short descriptions, space for notes, 

and numerous pictures of each plant.

Olson, C. 2009. A guide to nonnative invasive 

plants inventoried in the North by Forest 

Inventory and Analysis. Gen. Tech. Rep. NRS52. Newtown Square, PA; U.S. Department of 

Agriculture, Forest Service, Northern Research 

Station. 194 p. View or download publication at 

http://nrs.fs.fed.us/pubs/34183.

9. Join a Regional Invasive Plants Listserve.

Subscribe to a regional invasive plants listserv 

to receive emails and updates to stay informed 

of emerging problem species and current control 

methods. Two such groups include the Midwest 

Invasive Plant Network at www.MIPN.org or the MidAtlantic Exotic Pest Plant Council website at www.

ma-eppc.org. 

SYNOPSIS

Land managers and researchers have much to learn 

about the interaction between fire and invasive plants 

in eastern oak forests woodlands and savannas. The 

use of fire alone should not be considered as a viable 

control option for invasives. Instead, an integrated 

management approach with early detection, removal, 

and monitoring should be utilized to minimize their 

deleterious impacts on oak ecosystems.

ACKNOWLEDGMENTS

The author thanks the support and cooperation from 

Michael Bowden, Robert Boyles, Chad Sanders, Greg 

Guess, and Aaron Kloss of the Ohio Department of 

Natural Resources, Division of Forestry as well as 

Todd Hutchinson, Louis Iverson, and Daniel Yaussy 

of U.S. Forest Service, Northern Research Station. 

This research was supported by the Joint Fire Science 

Program, U.S. Forest Service Northern Research 

Station, and the Ohio Division of Forestry.

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The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
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Animal Populations 

and Fire-Maintained 

Oak Ecosystems
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Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 159

SONGBIRDS IN MANAGED AND NON-MANAGED SAVANNAS 

AND WOODLANDS IN THE CENTRAL HARDWOODS REGION

Frank R. Thompson III, Jennifer L. Reidy, Sarah W. Kendrick, and Jane A. Fitzgerald

Research Wildlife Biologist (FRT), U.S. Forest Service, Northern Research Station, 

202 Natural Resources, University of Missouri, Columbia, MO 65211; 

Research Specialist (JLR); Graduate Research Assistant (SWK); Joint Venture Coordinator (JAF). 

FRT is corresponding author: to contact call 573-875-5341 ext. 224 or email frthompson@fs.fed.us.

Abstract.—We know little about the response of birds to savanna and woodland 

restoration in the Ozarks or how important such habitats are to birds of conservation 

concern. Bird species such as red-headed woodpecker, prairie warbler, field sparrow, and 

blue-winged warbler are species of regional concern, and declines of these species may 

be due to historical declines in savannas and woodlands. Our objective was to compare 

abundance of focal bird species between sites managed to restore savanna or woodland 

conditions and forested sites with no restoration management in the Ozark Highlands 

of Missouri and Arkansas during the breeding season. We consulted with local resource 

managers to identify sites they considered good examples of savanna or woodland 

restoration (managed sites) and also selected nearby stands on similar landforms that had 

no recent management (non-managed sites) and had succeeded to closed-canopy forest. 

We conducted 9 to 15 point counts along randomly located transects within these sites 

in 2007 and 2008. For species with >50 detections, we estimated density using distance 

sampling surveys, and for species with fewer detections we report the mean number of 

detections/point as an index of abundance. We conducted 260 surveys at managed sites 

and 244 at non-managed sites. Blue-winged warbler, eastern towhee, eastern woodpewee, field sparrow, prairie warbler, and summer tanager were more abundant in 

managed sites whereas Acadian flycatcher, and worm-eating warbler were more abundant 

in non-managed sites. Abundance of blue-winged warbler, field sparrow, and prairie 

warbler decreased with canopy cover while Eastern towhee and summer tanager reached 

their greatest abundance in intermediate canopy cover. Eastern wood-pewee and prairie 

warbler were the most abundant breeding birds with 0.22 and 0.15 singing males/ha, 

respectively. Savannas and woodlands provide habitat for an interesting mix of grasslandshrub and canopy nesting birds that are of high conservation concern. 

BACKGROUND AND OBJECTIVES

Savanna and woodland habitats historically covered a 

large portion of the Midwest and were the dominant 

habitats in the Ozark Plateau in the early 1800s 

(Nelson 1997). Before European settlement, oak 

savanna covered 11 to13 million hectares in the 

Midwest from Texas to Michigan, but only 2,607 

hectares remained in1985 (Nuzzo 1986). Agricultural 

plowing, fire suppression, and forest succession 

eliminated most oak savannas (Peterson and Reich 

2001). An estimated 24,700 to 49,400 hectares of 

restorable oak savanna maintain enough floristic 

diversity to justify preservation in the state of Missouri 

(Currier 1993). 

There is not a clear distinction between savannas and 

woodlands. Savannas have been defined as 10-50 

percent canopy cover, scattered trees and shrubs, and a 
160 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

ground cover of grasses, sedges, and forbs (McPherson 

1997, Nelson 1985, Taft 1997), whereas woodlands 

have been defined as 30-80 percent canopy cover, 

open-grown trees, and ground cover of forbs, some 

woody plants, and grasses (Taft 1997). Fire historically 

maintained these open habitats by thinning the 

understory, reducing woody vegetation, and creating 

large openings in the canopy where sunlight reached 

the ground. This increased sunlight encourages 

floristic diversity with a dense ground flora consisting 

of grasses, sedges, and other composites that continue 

to grow throughout the summer as opposed to the 

herbaceous layer in a forest that peaks in the spring 

(Nelson 1985). Current efforts to restore savannas and 

woodlands use prescribed fire as the main management 

tool, although managers often use additional 

mechanical treatments consisting of selective tree 

removal to reduce tree density.

Savannas and woodlands are transitional habitats 

between the oak forests to the east and prairies to 

the west (McPherson 1997) and have been described 

as ecotones (Temple 1998). As ecotones, they have 

some biotic and environmental characteristics of 

adjacent systems (grassland and forest), as well 

as characteristics unique to the ecotone, enriching 

biodiversity of these habitats (Temple 1998). Current 

knowledge suggests these communities harbor 

few bird specialists (Grundel and Pavlovic 2007a). 

However, savannas and woodlands may represent 

important habitats for some species of birds, and bird 

species may have been eliminated or altered their 

habitat use when the availability of savannas and 

woodlands declined before researchers could gather 

baseline information (i.e., red-headed woodpecker 

[Melanerpes erythrocephalus]; Davis and others 

2000). As such, their importance in the landscape 

remains understudied and poorly understood. 

Savanna and woodland restoration could potentially 

provide additional habitat for declining species that 

use grasslands or closed-canopy forests. Based on 

Breeding Bird Survey data, approximately 70 percent 

of 21 species associated with open woodlands and 

savannas are in long-term decline or are currently 

declining in eastern North America (Hunter and others 

2001). In a study of breeding bird densities in central 

Minnesota, 9 of 20 species associated with savanna 

and woodland have been declining in abundance 

during the past 35 years (Davis and others 2000). 

The use of prescribed fire to restore savanna 

and woodland affects vegetation structure and 

composition, which potentially influences habitat 

selection by birds (Brawn and others 2001). Avian 

species richness and densities appear to increase 

with restoration burns in the Midwest. Species 

richness and total density were greater on burned 

sites than unburned savanna restoration sites in 

central Minnesota (Davis and others 2000). Bird 

communities along a habitat gradient ranging from 

prairie to woodland had the greatest species richness 

in dry oak savanna with 5-65 percent canopy cover 

(Au and others 2008). Species of concern, such as 

blue-winged warblers (Vermivora cyanoptera), goldenwinged warblers (Vermivora chrysoptera), and redheaded woodpeckers, were more abundant in savannas 

than prairies or woodlands (Au and others 2008). 

Frequent fires in savannas and woodlands in Indiana 

were positively correlated with species diversity and 

density of the most threatened species. Species with a 

preference for oak savanna habitat were at maximum 

density at an average fire frequency of once every 3

years (Davis and others 2000, Grundel and Pavlovic 

2007b). Bird community structure was most strongly 

related to the use or absence of fire when managing 

savanna in the Minnesota study (Davis and others 

2000). Savannas managed with cutting and no fire 

supported bird communities more similar to woodland 

than to other savanna sites managed with fire (Au and 

others 2008). While no specific cause was identified 

relating community structure to vegetation differences 

between the two habitats, the use of fire may shift a 

habitat enough to influence bird communities (Au and 

others 2008).

Our objective was to determine the response of focal 

bird species to savanna and woodland restoration in 

the Central Hardwood Region. We compared bird 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 161

abundance between savannas and woodlands that 

were maintained or restored by active management 

(managed) versus potential savannas or woodlands 

with no recent management (non-managed) that 

had succeeded to closed woodland or forest. We 

hypothesized early successional species such as 

blue-winged warbler, brown thrasher (Toxostoma 

rufum), eastern towhee (Pipilo erythrophthalmus), 

field sparrow (Spizella pusilla), and prairie warbler 

(Dendroica discolor) would be most abundant in 

managed sites with the most open canopies or lowest 

basal areas. We hypothesized that forest species 

such as Acadian flycatcher (Empidonax virescens), 

Louisiana waterthrush (Parkesia motacilla), and 

worm-eating warblers (Helmitheros vermivorum) 

would be most abundant in non-managed sites 

with high canopy cover, and Eastern wood-pewee 

(Contopus virens), and summer tanager (Piranga 

rubra) would be most abundant on managed sites with 

intermediate canopy cover or basal area. 

STUDY AREAS

We conducted our study in forests, woodlands, and 

savannas on public lands in Arkansas, Missouri, 

and Tennessee within the Central Hardwoods Bird 

Conservation Region (CHBCR) (Fig. 1). The CHBCR 

was comprised of >3 million ha of rolling hills covered 

Figure 1.—Location of study sites where bird abundance 

was surveyed on managed savanna and woodlands and 

non-managed forest in the Central Hardwood Region in 

2007-2008.

primarily with hardwood forests (oaks [Quercus

spp.] and hickories [Carya spp.]) interspersed 

with glades and woodlands and dissected by deep 

river valleys (Fitzgerald and others 2003). Other 

landforms within the region are steep-sided ridges 

and hills, karst terrain, gently rolling lowland plains, 

or bottomlands along major rivers with associated 

terraces and meander scars (McNab and Avers 1994). 

The Mississippi River floodplain bisected the CHBCR 

between Illinois and Missouri into two regions: the 

Ozark Highlands and Boston Mountains to the west, 

and the Interior Low Plateaus to the east (U.S. NABCI 

2000). 

METHODS

Site Selection

We identified managed woodlands and savannas by 

contacting state and federal agencies. Stands selected 

were on ecological land types that were historically 

savanna or woodlands with a history of management 

that included repeated prescribed fires and had 

largely achieved the desired structure for a woodland 

or savanna. All managed stands had a history 

of prescribed burns and some had been thinned. 

Prescribed burns were conducted in late winter and 

early spring. We located non-managed stands within 

10 km of each managed site; the non-managed stand 

consisted of forest on similar landforms and aspects 

as the managed stand but had no recent fire or tree 

harvest (>20 years). Stands ranged from 20 ha to >150 

ha, and all sites were imbedded in a matrix of forest. 

We refer to the paired managed and non-managed 

stands as sites. The dominant tree species at these sites 

were black oak (Q. velutina), post oak (Q. stellata), 

red oak (Q. rubra), scarlet oak (Q. coccinea), white 

oak (Q. alba), hickory (Carya spp.), and shortleaf pine 

(Pinus echinata).

Bird Surveys

We conducted counts at points spaced at 250-m 

intervals on a grid starting from a random location. 

We located 9-15 points in a stand and did not place 

points within 50 m of the edge of the stand. Most 
162 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

points were substantially more than 50 m from a stand 

edge, and all stands were in a matrix of forest so edge 

effects were limited. We conducted one 10-minute 

survey at each point from 23 May 2007 through 30 

June 2008. Counts were done from sunrise to 1000 

hr during periods of no or low wind, no or light 

precipitation, and temperatures >10 °C. We counted 

the number of singing males for 10 focal bird species 

(acadian flycatcher, blue-winged warbler, brown 

thrasher, eastern towhee, eastern wood-pewee, field 

sparrow, Louisiana waterthrush, prairie warbler, 

summer tanager, and worm-eating warbler). We 

limited surveys to 10 focal species to ensure we were 

able to accurately collect the distance data needed for 

density estimation. For each singing male detected, 

we recorded the time of initial detection and the 

distance and direction to the bird from the observer. 

We measured distances using a Bushnell Yardage Pro 

laser range-finder (Bushnell, Overland Park, KS), 

but some distances were estimated when topography 

or vegetation precluded use of the range-finder. All 

observers received training on distance measurements 

prior to the surveys. At the end of each count, we 

measured canopy cover at the point by averaging two 

measurements with a spherical densiometer taken 

back-to-back at the point, and we measured basal area 

with a ten-factor prism.

We used two approaches to estimate abundance from 

surveys. We treated counts of detections of singing 

males during a 10 minute survey as a measure of 

relative abundance and fit generalized linear models 

evaluating treatment. Because not all individuals 

present during a count are detected by the observer, 

this approach assumes that the number of birds 

detected is related to the true abundance, and that 

variation in detectability does not contribute to bias 

in the results. For species with >50 detections, we 

used distance modeling to estimate detectability and 

true densities (Buckland and others 2001). More 

sophisticated analyses that address detectability 

require greater numbers of bird detections than we had 

for most focal species. These two approaches represent 

the tradeoffs between the more sophisticated modeling 

of treatments possible when considering relative 

abundance and addressing detectability to estimate 

densities. 

Effects on Relative Abundance

For species with greater than 20 detections, we used 

a generalized linear model with a Poisson distribution 

to model the effects of treatment on bird relative 

abundance. The Poisson distribution is often used 

with count data and fit our data better than a negative 

binomial or normal distribution. While counts at 

individual points was the response variable in our 

models, we acknowledged the non-independence 

of points at sites by including a random effect for 

site in the model which treated sites as subjects and 

points as repeated measures. We hypothesized that 

treatment and canopy cover or basal area affected 

bird abundance. For our treatment effect we did 

not distinguish between savanna and woodland 

management because most stands had canopy cover in 

the range of woodlands. Rather, we simply considered 

stands managed or non-managed and included a 

continuous measure structure to capture additional 

variation. Because basal area and canopy cover are 

correlated, we determined which was more supported 

and included it in our models. The effect of canopy 

cover was supported more (n = 8) or equally (n = 1) 

compared to basal area, so we included canopy cover 

in models. We evaluated support for effects using an 

information theoretic approach to compare support for 

four a priori models based on Akaike’s Information 

Criteria (AICc

) adjusted for small sample sizes 

(Burnham and Anderson 2002). We included year as 

a fixed effect in all models to account for variability 

in abundance between the 2 years of the study. The 

null model consisted of an intercept and year effect. 

Additional models included the following fixed effects: 

Year + Treatment (managed or non-managed); Year + 

Canopy cover; and Year + Treatment + Canopy cover. 

We considered linear and quadratic forms of canopy 

cover and used the form most supported for each 

species. We interpreted relative support for models 

based on AICc

 to infer the importance of the factors 

considered and report model coefficients and predicted 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 163

abundances as a function of covariates model-averaged 

across the set of candidate models to address model 

selection uncertainty (Burnham and Anderson 2002). 

We estimated predicted abundances for each covariate 

over its observed range while holding values of other 

covariates at their mean. 

Density Modeling

For species with greater than 50 detections, we 

estimated density based on the distance to detected 

individuals at points, assuming detectability decreases 

with increasing distance between the observer and the 

detected individual. Analyses were carried out with 

Distance 6.0 (Thomas and others 2010) using three 

distance functions (a half-normal key function with 

cosine series expansion, a hazard-rate key function 

with simple polynomial series expansion, and a 

uniform function) and selected the most supported 

function based on Akaike’s Information Criteria 

(Buckland and others 2001). We deleted observations 

at distances >100 m, which roughly corresponded to 

truncating the greatest 10 percent of recorded distances 

as recommended by Buckland and others (2001). We 

did not consider other factors affecting detectability 

such as observer, habitat, or date because the number 

of detections across each level of these factors was 

too sparse. We post-stratified estimates by treatment to 

estimate density and 95 percent confidence intervals 

for managed and non-managed sites. 

RESULTS

We surveyed bird abundance at 244 points in nonmanaged stands and 260 points in managed stands 

located on 23 sites (Fig. 1). We surveyed 236 points 

in 2007 and 260 in 2008. We detected the following 

number of individuals for the focal species: eastern 

wood-pewees (257), summer tanagers (135), eastern 

towhees (106), prairie warblers (105), Acadian 

flycatchers (79), worm-eating warblers (61), field 

sparrows (44), blue-winged warblers (21), brown 

thrashers (7), and Louisiana waterthrushes (1). 

Because only one Louisiana waterthrush and seven 

brown thrashers were detected, we excluded them 

from further analyses. Median canopy cover was 82 

percent (95 percent CI = 8, 96) in managed sites and 

96 percent (95 percent CI = 80, 99) in non-managed 

sites (Fig. 2). Median tree basal area was 60 ft2

/acre 

(95 percent CI = 10, 150) in managed sites and 

100 ft2

/acre (95 percent CI = 40, 170) in non-managed 

sites. 

Figure 2.—Box plots indicating median, 25th and 75th, 10th and 90th, and 5th and 95th percentiles of canopy cover and basal 

area on managed savanna and woodlands and non-managed forests in the Central Hardwood Region in 2007-2008.
164 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Table 1.—Support for four models predicting bird abundance in managed savanna and woodlands and 

non-managed forest in the Central Hardwood Region in 2007-2008 based on treatment (managed and nonmanaged) and canopy cover. Δ AICc is the difference in Akaike’s information criteria adjusted for small 

sample size between the model and best model and ωi is the weight of evidence for the model.

 Null Canopy Treatment Treatment + canopy

Species Δ AICc ωi Δ AICc ωi Δ AICc ωi Δ AICc ωi

Acadian flycatcher 17.5 0.00 6.9 0.02 0.9 0.39 0.0 0.59

Blue-winged warbler 3.7 0.07 0.0 0.47 1.8 0.19 1.1 0.27

Eastern towhee 100.4 0.00 64.1 0.00 0.0 0.70 1.7 0.30

Eastern wood-pewee 40.8 0.00 34.5 0.00 0.0 0.73 2.0 0.27

Field sparrow 44.2 0.00 0.0 0.51 20.5 0.00 0.05 0.49

Prairie warbler 74.3 0.00 40.7 0.00 4.2 0.11 0.0 0.89

Summer tanager 9.7 0.00 0.0 0.53 3.0 0.12 0.9 0.34

Worm-eating warbler 17.9 0.00 4.2 0.09 2.5 0.20 0.0 0.71

Effects on Relative Abundance

Treatment effects, canopy cover effects or combined 

effects of both were detected for all species analyzed 

(Table 1). Abundance of Acadian flycatchers and 

worm-eating warblers differed between managed 

and non-managed stands as expected for species 

breeding in mature forests. The treatment + canopy 

model received the most support for both species 

(Table 1). Abundances were greater in non-managed 

than managed sites (Table 2, Fig. 3) and increased 

linearly with canopy cover (Fig. 4), but canopy cover 

effects were not as strong as treatment effects and the 

confidence intervals overlapped zero (Table 2).

Blue-winged warbler, eastern towhee, field sparrow, 

and prairie warbler generally showed patterns in 

abundance consistent with our expectations for birds 

breeding in early-successional forest and were more 

abundant in managed stands or stands with more open 

canopies. Blue-winged warbler and field sparrow 

 Year Treatment Canopy Canopy2

Intercept β 90% CI β 90% CI β 90% CI β 90% CI

Acadian flycatcher -2.31 -0.70 -1.30, -0.09 -1.02 -1.61, -0.43 0.01 -0.01, 0.03

Blue-winged warbler -2.98 -0.86 -2.33, 0.60 0.38 -0.55, 1.31 -0.01 -0.03, 0.00

Eastern towhee -6.16 -1.24 -3.25, 0.76 4.67 2.82, 6.52 0.00 -0.009, 0.014 0.000 0.000, 0.000

Eastern wood-pewee -1.37 -0.02 -0.32, 0.28 0.95 0.70, 1.20 0.00 -0.001, 0.001

Field sparrow -2.18 -0.02 -1.97, 1.94 0.48 -0.64, 1.60 -0.03 -0.043, -0.022

Prairie warbler -3.25 -0.06 -0.76, 0.65 2.64 1.81, 3.47 -0.01 -0.016, -0.001

Summer tanager -1.60 0.32 -0.05, 0.69 0.15 -0.21, 0.52 0.02 -0.006, 0.052 -0.000 -0.001, 0.000

Worm-eating warbler -3.76 0.30 -0.22, 0.77 -0.81 -1.50, -0.13 0.02 -0.005, 0.045

Table 2.—Model-averaged parameter estimates from generalized linear models with Poisson distributions 

used to predict bird abundance in managed savanna and woodlands and non-managed forests in the 

Central Hardwood Region in 2007-2008

were most affected by canopy cover, eastern towhee 

by treatment, and prairie warbler by canopy cover 

and treatment (Table 1). These four species were all 

substantially more abundant in managed stands (Fig. 

3). Abundance of blue-winged warblers and prairie 

warblers decreased linearly with canopy cover; a 

quadratic effect of canopy cover received some 

support for eastern towhee but after model-averaging 

there was no visible effect of canopy cover (Fig. 4). 

Eastern wood-pewee and summer tanager nest in 

mature trees and are often considered forest species, 

but both were most abundant in managed stands (Fig. 

3) Treatment had the strongest effect on eastern woodpewee, while canopy cover had the strongest effect 

on summer tanager (Table 1). A quadratic effect of 

canopy cover was supported for summer tanagers and 

they reached greatest abundance at approximately 40 

percent canopy cover (Fig. 4). 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 165

Figure 3.—Model-averaged predictions of relative abundance of birds (birds/count) predicted by generalized linear models on 

managed savanna and woodlands and non-managed forests in the Central Hardwood Region in 2007-2008.

Figure 4.—Model-averaged predictions of relative abundance of birds (birds/count) predicted by generalized linear models as 

a function of canopy cover on managed savanna and woodlands and non-managed forests in the Central Hardwood Region in 

2007-2008.
166 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Densities

We were able to fit Distance models and estimate 

densities for six species at managed and non-managed 

sites (Table 3). Densities on managed and nonmanaged sites for each species followed a similar 

pattern to that predicted by the relative abundance 

models (Fig. 2). Eastern wood-pewees and prairie 

warblers were the most abundant species on managed 

sites. Acadian flycatchers and worm-eating warblers 

were the most abundant species on non-managed sites. 

DISCUSSION

We found substantial differences in abundance of our 

focal species between managed and non-managed 

sites. Relationships to management and canopy cover 

generally followed our a priori expectations and 

reflect habitat needs of species from both ends of a 

successional gradient as well as some that seemed to 

prefer the intermediate conditions created by savannawoodland management. Early successional species 

(e.g., blue-winged warbler, eastern towhee, field 

sparrow, prairie warbler) had greater abundance in 

managed sites or sites with the most open canopies, 

and abundance declined linearly with canopy cover. 

Savannas are typically defined by a dominant 

herbaceous ground cover, which would be achieved 

with frequent fire (short intervals). Allowing a longer 

interval between fires would presumably increase the 

woody growth and should support higher abundance of 

shrub-nesting species. The degree to which savannas 

and woodlands provide habitat for grassland, earlysuccessional, and forest birds likely depends on 

micro-scale habitat features such as amount of ground 

cover that is herbaceous or woody and the structure 

of the canopy, as well as landscape features such as 

proximity to other suitable habitat patches, size of 

savanna or woodland stands, and composition of 

surrounding landscape. 

Acadian flycatchers and worm-eating warblers were 

both less common on managed sites. Both species are 

typically associated with mid- to late-successional 

forests with a well-developed understory. Acadian 

flycatchers nest in understory trees such as flowering 

dogwood (Cornus florida). Worm-eating warblers nest 

on the ground and are often associated with deep leaf 

litter and high densities of shade-tolerant understory 

shrubs and trees. An objective of savanna-woodland 

restoration is often to remove the understory with the 

use of fire, so it is not surprising that these species 

were less common on managed sites. Conversion 

of forests to woodlands or savannas would likely 

negatively affect other forest-dependent species by 

removing the subcanopy layers and leaf litter ground 

layer.

Two species, eastern wood-pewee and summer 

tanager, reached their highest abundance in the 

intermediate canopy cover or tree densities that were 

found in managed savannas and woodlands. Both 

species are aerial insectivores, so the open canopy 

provides ideal conditions for foraging. Additionally, 

both seem to prefer to nest far out on horizontal 

 Non-managed Managed

 GOF pd Density 95% CI Density 95% CI

Acadian flycatcher 0.87 0.41 0.165 0.115 - 0.237 0.034 0.024 - 0.049

Eastern towhee 0.49 0.68 0.002 0.001 - 0.003 0.113 0.076 - 0.169

Eastern wood pewee 0.49 0.69 0.081 0.062 - 0.107 0.220 0.167 - 0.289

Prairie warbler 0.95 0.48 0.006 0.004 - 0.008 0.144 0.106 - 0.195

Summer tanager 0.23 0.65 0.054 0.038 - 0.078 0.091 0.063 - 0.130

Worm-eating warbler 0.31 0.39 0.108 0.067 - 0.174 0.023 0.014 - 0.037

Table 3.—Estimated densities (singing males/ha) of birds in managed savanna and woodlands and nonmanaged forests in the Central Hardwood Region in 2007-2008. Density and probability of detection (pd) 

were estimated by distance modeling, p-values > 0.05 (GOF) indicate no lack of fit.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 167

branches when possible, so open canopies also provide 

ideal structure for nesting. This contrasts with the other 

focal species which were associated more with either 

the most open or dense stands. Brawn (2006) similarly 

found eastern wood-pewees, summer tanagers, and 

eastern towhees were more abundant in restored 

savanna than forest.

Previously reported densities for blue-winged warbler, 

field sparrow, and prairie warbler are 0.3-0.4, 0.3-0.5, 

and 0.5-0.9 birds/ha, respectively, in glades and 3 to 

5-year-old regenerating forest in the Missouri Ozarks 

(Fink and others 2006, Thompson and others 1992). 

Mean density of prairie warblers in managed sites in 

this study (0.11 birds/ha) was less than that reported in 

these earlier studies in the Ozarks, but this was likely 

because, on average, savanna and woodland stands had 

more canopy cover and less shrub cover than optimum 

for prairie warblers. Densities of Acadian flycatchers 

in non-managed sites (0.17 birds/ha) was not very 

different from densities previously reported in the 

Ozarks (0.2 birds/ha) (Thompson and others 1992).

Our results provide valuable information for 

conservation planners associated with the Central 

Hardwoods Joint Venture (CHJV), a public-private 

bird conservation partnership focused on the Central 

Hardwoods Bird Conservation Region. The CHJV 

staff and partners are charged with identifying habitat 

conditions and acreages needed to support desired 

population levels of priority species associated 

with both grass-shrubland and forest ecosystems 

as identified by Partners in Flight (Rich and others 

2004). Little information was previously available 

that allowed planners to quantify priority species 

abundances in savanna and woodland ecosystems 

or to assess tradeoffs among grass-shrubland and 

forest-affiliated species if and when overstocked and 

degraded savannas and woodlands were restored. We 

showed that grass-shrubland bird populations could be 

increased with more widespread restoration of these 

ecosystems and that a loss of some number of forestbreeding birds would need to be offset by conservation 

efforts in appropriate forest landtypes.

While tree basal area and canopy cover were lower 

on managed compared to non-managed stands (Fig. 

2), the average values for managed stands were in the 

upper end of that considered typical for woodlands. 

We believe this is because restoration of the sites 

we studied is still an ongoing process, and few sites 

had fully achieved the desired future condition. 

The high canopy cover and basal area may also be 

indicative of a need to more actively manage stands by 

thinning or that site conditions are more suitable for 

woodlands than savannas. Because managed savanna 

and woodland stands had greater canopy cover than 

typically described for these communities, these stands 

might have provided a slightly biased perspective 

of the bird communities expected in savannas and 

woodlands. 

Future research should include a larger number of 

bird species to identify additional birds that reach 

high abundance in intermediate canopy covers or 

at managed sites, and also a larger suite of habitat 

characteristics, such as shrub and herbaceous 

variables. We did not include cavity-nesting species 

in this study, but it is likely that they reach higher 

abundances in these habitats given the increased 

snag density associated with more frequent fires. 

Additionally, to fully understand the value of savannas 

and woodlands as breeding bird habitat, we need to 

evaluate additional demographic parameters such as 

productivity. Better knowledge of the effects of timing, 

frequency of fire, and tree stocking levels is needed 

to develop best management practices for sustaining 

savanna and woodland communities. 

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The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
170 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

A REVIEW OF FIRE EFFECTS ON BATS AND BAT HABITAT 

IN THE EASTERN OAK REGION

Roger W. Perry

Research Wildlife Biologist, U.S. Forest Service, Southern Research Station, P.O. Box 1270, 

Hot Springs, AR 71902. To contact call 501-623-1180, ext. 108 or email at rperry03@fs.fed.us.

Abstract.—Fire is increasingly being used in oak forests to promote oak regeneration, 

improve wildlife habitat, and reduce hazardous fuel loads. Although recent research 

has begun to shed light on the relationships among fire, bats, and bat habitat, these 

interactions are not yet fully understood. Fire may affect bats directly through heat and 

smoke during the burning process or indirectly through modifications in habitat. Studies 

suggest fire generally has beneficial effects on bat habitat by creating snags, reducing 

understory and midstory clutter, creating more open forests, and possibly increasing 

abundance of flying insects. Direct effects of fire on bats during the burning process 

are still largely unknown. These potential direct effects likely differ for each species or 

roosting guild of bats, and may also vary by season and reproductive condition. 

BACKGROUND

Fires ignited by lightning and Native Americans 

historically maintained a mosaic of forests, grasslands, 

savannas, and open woodlands throughout the eastern 

United States, including the eastern oak (Quercus

spp.) region (Abrams 1992, Lorimer 2001). Prior to 

European settlement, fire frequencies ranged from 

every 3 to 19 years within this region (Guyette and 

others 2006). European settlement, logging, and 

clearing for agriculture altered these landscapes 

during the 18th and 19th centuries. During the 20th 

century, fire suppression caused many forests that were 

previously open and park-like to succeed to dense 

closed-canopy forests where fire-adapted plant species 

were replaced by shade-tolerant and fire-sensitive 

vegetation (Lorimer 2001, Nowacki and Abrams 

2008, Van Lear and Harlow 2002). It is assumed 

that bats adapted to fire across these landscapes over 

thousands of years of frequent fire. However, changes 

in bat populations resulting from fire suppressioninduced changes in habitat over the past century are 

difficult to differentiate from other anthropogenic 

effects such as disturbance of cave roosts, pesticides, 

habitat destruction, fragmentation, urbanization, and 

indiscriminant killing of bats that also occurred during 

portions of this period.

Fire may affect bats directly through heat, smoke, and 

carbon monoxide, or indirectly through modifications 

in habitat and changes in their food base (Dickinson 

and others 2009). Although use of fire by land 

managers has increased substantially in recent years, 

researchers have just begun to study the effects of 

fire on bats and bat habitat. Recent reviews have 

summarized the state of knowledge on the relationship 

between bats and fire. Carter and others (2002) 

provided a general review on effects of fire on bats 

in the southeastern United States and Mid-Atlantic 

States, and Keyser and Ford (2006) reviewed effects 

of fire on mammals (including bats) in eastern oak 

forests. A comprehensive review of direct and indirect 

effects of fire on bats, with an emphasis on Indiana 

bats (see Table 1 for scientific names of species), 

was presented by Dickinson and others (2009). My 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 171

Eastern red bat 

(Lasiurus borealis)

Foliage, mostly hardwood canopies Foliage, trees, low shrubs, leaf litter

Seminole bat 

(L. seminolus)1

Foliage, mostly pine canopies Foliage, trees, low shrubs, leaf litter

Hoary bat 

(L. cinereus)

Foliage, pine and hardwood canopies Unknown

Tri-colored bat 

(Perimyotis subflavus)

Foliage, mostly dead leaves in hardwoods, 

structures2

, caves, mines

Caves, mines, structures

Big brown bat 

(Eptesicus fuscus) 

Tree cavities, under bark, structures, caves, 

mines

Caves, mines, structures

Rafinesque big-eared bat 

(Corynorhinus rafinesquii)

Tree cavities, under bark, structures, caves, 

mines

Caves, mines, structures, tree cavities

Southeastern bat 

(Myotis austroriparius)

Tree cavities, structures, caves, mines Caves, mines, structures, tree cavities

Evening bat 

(Nycticeius humeralis)

Tree cavities, under bark, structures Tree cavities, under bark, ground-level3

Silver-haired bat 

(Lasionycteris noctivagans)

Tree cavities, under bark Tree cavities, under bark, caves, mines, 

structures, ground-level

Northern long-eared bat 

(M. septentrionalis)

Tree cavities, under bark, structures Caves, mines

Little brown bat 

(M. lucifugus)

Tree cavities, under bark, structures Caves, mines

Indiana bat 

(M. sodalis)

Tree cavities, under bark, structures Caves, mines

Gray bat 

(M. grisescens) 

Caves, mines Caves, mines

Ozark big-eared bat 

(C. townsendii ingens)

Caves, mines Caves, mines

Virginia big-eared bat 

(C. t. virginianus)

Caves, mines Caves, mines

Eastern small-footed bat 

(M. leibii) 

Caves, mines, under bark, structures, 

rock crevices

Caves, mines

Brazilian free-tailed bat 

(Tadarida brasiliensis)4

Caves, mines, structures Caves, mines, structures

1 Associated primarily with southern pine forests, rare in most of eastern oak region. 

2 Structures include buildings, bridges, culverts, water tanks, wells, and other man-made structures. 

3 Ground-level includes small mammal burrows, rock crevices, under tree roots, and other cavities or crevices on the ground. 

4 Resides primarily south of the eastern oak region.

Table 1.—Summer and winter roosting locations for bats found in the eastern oak region 

Species Summer Roosting Winter Roosting
172 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

objectives here are to expand upon those reviews and 

update information provided by recent studies. In the 

life history of bats, roosts and food are the two most 

important resources known to affect bat distribution 

and abundance (Kunz and Lumsden 2003). Therefore, 

I focus primarily on how fire in forests potentially 

affects these two resources. This discussion focuses 

on understory burning typically used for management 

purposes (not stand-replacing wildfire) and the effects 

of fire intensities typically found during prescribed 

burns.

Similar to birds, many species of bats undertake short 

(<500 km) or long-range (>1000 km) migrations 

between summer and winter use areas. Consequently, 

range maps often depict a species occurring throughout 

a wide area, but a species may occur only in portions 

of their range during each season (e.g., Cryan and 

Veilleux 2007). Furthermore, the ecology of bats often 

differs substantially among seasons. Thus, fire affects 

different species in different ways during each season, 

and burns conducted during winter will likely affect 

various species in different ways from those conducted 

between spring and fall. 

ROOSTING AND FIRE

Bats may spend over half their lives in roosts, and 

roosts provide protection from predators and the 

weather (Kunz and Lumsden 2003). Therefore, 

adequate roost sites are critical to the survival of 

bats. Bats that occur in the eastern oak region use 

different types of roosts, and the type of roost used 

often differs between summer and winter (Table 1). 

The 17 bat species that occur or potentially occur in 

the region can be classified loosely into three guilds: 

foliage-roosting species; species that roost in cavities, 

crevices, or under bark of trees during all or part of the 

year (cavity- and bark-roosting species hereafter); and 

cave obligates. Many bats use different types of roosts 

between summer and winter. For example, red bats 

and tri-colored bats in forests roost mostly in foliage 

during summer; however, during winter, red bats 

continue to roost in forests whereas tri-colored bats 

retreat to caves or mines for hibernation. Therefore, 

differences in the natural history of each species 

determine how fire affects that species, and direct 

effects of fire on individual bats is likely dependent 

on season and intensity of fire, sex and age of bat, 

and reproductive condition of bat. Most tree-roosting 

bats switch roosts every 2-4 days (e.g., Lewis 1995); 

thus, an abundant supply of potential roost locations 

is needed to provide suitable roosting habitat within a 

forest stand. 

Growing Season Fires 

and Foliage-Roosting Bats

During late spring, summer, and early fall (summer 

hereafter), four species that occur in the region roost in 

foliage (leaves or needles of trees and shrubs) during 

the day, including red bats, hoary bats, Seminole 

bats, and tri-colored bats (Table 1). Lasiurine bats 

(red, hoary, and Seminole bats) typically roost 15-

19 m above the ground in the canopies of overstory 

trees (Hein and others 2008; Hutchinson and Lacki 

2000; Menzel and others 1998; Perry and Thill 2007a, 

2007b; Perry and others 2007a). Seminole bats roost 

primarily in the needles of pines, red bats roost mostly 

in deciduous foliage such as oaks, and hoary bats use 

both pines and hardwoods (Hein and others 2008; 

Hutchinson and Lacki 2000; Menzel and others 1998; 

Perry and Thill 2007a, 2007b; Perry and others 2007a; 

Willis and Brigham 2005). Tri-colored bats roost 

in a variety of locations during summer, including 

caves, mines, and buildings (Fujita and Kunz 1984). 

However, in forests lacking these substrates, they roost 

in foliage of trees (often oaks), and mostly in dead 

leaves or suspended clusters of dead pine-needles 

(Perry and Thill 2007d, Veilleux and others 2003).

Direct effects of growing-season burns on foliageroosting bats are largely unknown. Because they 

typically roost relatively high (15-19 m) in the 

canopies of overstory trees during the warm season, 

it is unlikely that burning during the growing season 

leads to direct mortality. Further, carbon monoxide 

levels at roosting heights are unlikely a concern when 

flame lengths (fire intensity) are less than 1.6 m, which 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 173

is typically the most intense fires observed during 

most prescribed burns (Dickinson and others 2010). 

Dickinson and others (2010) created models predicting 

potential burns to ears, wings, or other non-furred 

parts of bats based on roost heights, fire intensity 

(flame length), and wind speed. Winds may reduce the 

temperature and gas concentrations at roosting heights 

by distorting fire plumes. They suggest that bats 

roosting at heights above 12 m (wind speeds of 2 m/

sec [4.5 mph]) to 22 m (wind speeds of 0 m/sec) would 

not be injured during intense controlled burns (flame 

lengths approximately 1.6 m high). Furthermore, they 

suggest models used to predict foliage scorch during 

prescribed burns (Reinhardt 2003) may potentially be 

useful as surrogates for predicting injury to bats.

When temperatures associated with fires are below 

lethal thresholds, heat and smoke could potentially 

disturb foliage-roosting bats regardless of roost height, 

causing them to relocate to other trees. However, 

foliage is not a limited substrate in most forests, and 

a substantial supply of alternative roosts is likely 

available if bats are disturbed (Carter and others 

2002). Tri-colored bats, which tend to have great site 

fidelity to particular dead leaf clusters in hardwood 

forests (Perry and Thill 2007d, Veilleux and others 

2003), may have more difficulty locating alternative 

roosts that provide adequate cover from predators after 

disturbance. Furthermore, because male tri-colored 

bats occasionally roost in suspended dead leaves 

close to the ground (<5 m high), they may be more 

susceptible to direct effects of fire than many other 

bats during summer (Perry and Thill 2007d). 

Temperate, insectivorous bats undergo periods of 

torpor during which their metabolism is reduced 

and body temperatures may be similar to ambient 

air temperature. Bats control energy expenditure 

by regulating the frequency, depth, and duration of 

torpor (Speakman and Thomas 2003). Torpor lasting 

multiple days or weeks is considered hibernation. 

Because torpor can slow fetal development and reduce 

milk production (Racey 1973, Wilde and others 

1999), females during the gestation and lactation 

periods of summer may spend less time in torpor 

than nonreproductive females or males (Cryan and 

Wolf 2003, Hamilton and Barclay 1994, Kurta and 

Fujita 1988, Solick and Barclay 2006). Because 

females are less likely to be in torpor during the 

reproductive season, they are likely able to escape fire 

more readily than males or non-reproductive females. 

However, non-volant young may not have the ability 

to escape heat and smoke from intense fires during the 

reproductive season. Nevertheless, females of many 

species (including most bats in the region) often carry 

non-volent young when roost switching, especially 

when disturbed (Davis 1970), and likely have the 

ability to escape oncoming heat if given sufficient 

warning.

Low-intensity burns during the reproductive season 

would likely have few negative effects on bats 

roosting in relatively tall (19-25 m) overstory trees. 

Furthermore, active bats maintain body temperatures 

of approximately 32-38 °C (90-100 °F) and may 

remain active above temperatures of 30 °C (86 °F) 

(Barclay and others 1996, Herreid and SchmidtNeilsen 1966). Thus, bats may not be in torpor or may 

only be in shallow torpor during periods of relatively 

high ambient temperatures, which would allow for 

quick escape during fires. Dickinson and others (2010) 

suggested bats may arouse and escape fire in less than 

10 minutes when temperatures are 25 °C (77 °F). 

Dormant-Season Fires 

and Foliage-Roosting Bats

In southern portions of the eastern oak region, red bats 

and Seminole bats may be active during winter nights 

when temperatures are above freezing. During winter, 

red bats roost on the ground (under leaf litter) or 1-6 m 

above the ground in the lower branches of eastern red 

cedars or in persistent dead leaves of oaks or shrubs 

(Mormann and Robbins 2007). Red bats typically roost 

in trees when temperatures exceed 10 °C during winter 

(Mormann 2005). Seminole bats roost in the canopies 

of overstory pines and hardwoods, in understory 

vegetation, pine needle clusters suspended above 

the ground, or in pine litter on the forest floor during 
174 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

winter (Hein and others 2008). Evidence suggests 

hoary bats occur in the region during winter (Cryan 

2003), but little is known about their winter roosting 

habits. Furthermore, little is known about the winter 

roosting habits of tri-colored bats outside hibernacula 

(caves, mines, and man-made structures), and it is 

not known if they use tree roosts or are active during 

winter in southern portions of the region.

Potential effects of dormant-season burning on species 

that use forests during winter are likely affected by 

ambient air temperatures. During colder periods of 

winter, lasiurine bats and some cavity- and barkroosting species may retreat to roosts on or near the 

ground where temperatures are more stable (Boyles 

and others 2005, Flinn 2009, Hein and others 2008, 

Mormann and Robbins 2007, Perry and others 2010, 

Saugey and others 1998). For example, Mormann 

and Robbins (2007) found red bats switched from 

tree roosts to leaf litter roosts when temperatures 

approached freezing, and Flinn (2009) found most 

roosts of red bats in leaf litter when the maximum 

daytime temperature was <14 °C (57 °F). Hein and 

others (2008) found that Seminole bats roosted 

extensively on or near the forest floor when minimum 

nightly temperatures were below 4 °C (39 °F). Thus, 

on days when the previous night’s temperature is 

below approximately 5 °C (41 °F), these bats are 

expected to be located in roosts more vulnerable to 

fire. Studies suggest that during winter, red bats roost 

in litter mostly on south-facing slopes where radiant 

heating may provide greater temperatures than other 

areas across a landscape (Flinn 2009, Mormann and 

Robbins 2007), whereas one study suggested red 

bats may roost more on north slopes where lower 

temperatures allow deeper torpor (Saugey and others 

1989).

Many bats may take from 30 to 60 minutes to arouse 

from torpor when ambient temperature is 5 °C 

(Thomas and others 1990), and red bats roosting in 

leaf litter may take up to 30 minutes to arouse (Layne 

2009). Furthermore, lower ambient air temperatures 

correspond with longer arousal times. However, when 

temperatures fall to near or below freezing (<5 °C or 

<41°F), red bats increase their metabolisms or arouse 

to prevent freezing (Dunbar and Tomasi 2006). Thus, 

a bat may not have sufficient time to arouse and flee 

from approaching flames on cold days (>5 °C), but 

may be in a lesser state of torpor when temperatures 

are below freezing. Data on lightning strikes from the 

Interior Highlands suggest natural fire ignitions peak 

in July-September, with a smaller peak in March-April 

(USDA FS 1999). Historical accounts also suggest 

Native Americans ignited fires mostly in September 

and November (USDA FS 1999). This led Carter and 

others (2002) to suggest that bats using forests burned 

during winter may not be fully adapted to winter 

burning. 

Hein and others (2008) recommended caution 

when conducting prescribed burns on days when 

temperatures the previous nights are <4 °C. However, 

Layne (2009) suggested temperature from sunrise to 

the onset of the fire had a higher correlation value with 

red bat recovery times than night-before temperatures. 

Furthermore, Layne (2009) recommended conducting 

winter fires on days when temperatures are greater 

than 10 °C and starting the fire on north-facing slopes 

to give red bats a chance to passively rewarm and react 

to approaching fire. Nevertheless, if or how these bats 

escape injury during winter fire remains unclear, and 

it is unknown what temperatures these bats experience 

under the leaf litter.

Reports of red bats exiting leaf litter or located on 

the ground attempting to flee during dormant-season 

burns suggests they may arouse during winter fires 

(Moorman and others 1999, Saugey and others 1989). 

Furthermore, dormant-season burns are typically 

ignited in late morning or early afternoon when 

humidity is lower and temperatures are higher. For 

example, unpublished data on ignition times and 

temperatures of days when dormant-season burns 

were conducted (November-early March) in the 

Interior Highlands of Arkansas indicated average 

temperature 2 hours before ignition was 7.7 °C, and 

average temperature at time of ignition was 12.3 °C 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 175

(Table 2). Further, 36 percent of burns were conducted 

when temperatures 2 hours before ignition measured 

below 5 °C. Only 13 percent of burns were initially 

ignited when temperatures were below 5 °C, and 

many of these burns took hours to complete. Thus, in 

southern portions of the eastern oak region, dormantseason burns often take place at times when ambient 

temperatures allow for quicker arousal. 

Scesny (2006) reported red bats aroused (22 minutes 

at 5 °C) when exposed to smoke and the sound of fire, 

suggesting fire provides cues that cause these bats 

to arouse. However, other studies suggest individual 

bats of other species may not arouse when exposed to 

nontactile stimuli such as sound and light (Speakman 

and others 1991), and bats in torpor may not be able 

to perceive sound when temperatures fall below 12 °C 

(Harrison 1965). Arousal from fire sounds and smoke 

may be a species-specific response of red bats adapted 

to roosting close to the ground in fire-prone areas, but 

additional study is warranted. Nevertheless, possible 

arousal from fire stimuli, along with the warmer 

temperatures just prior to many burns may enable red 

bats to arouse and escape oncoming flames during 

many dormant-season burns. Head fires typically move 

in the direction of the wind and may deliver smoke 

over the area to be burned for substantial periods prior 

to the arrival of fire. When head fires and slowermoving back fires are used simultaneously, smoke 

from the head fire may cover the area prior to arrival 

of the back fire. Thus, substantial smoke may inundate 

the area prior to arrival of fire, providing cues for bats 

to arouse. Further study is needed on the interactions 

of ambient temperature, torpor, arousal times, fire 

stimuli, and escape behaviors by bats. 

Growing Season Fires 

and Cavity- and Bark-Roosting Species

In forested areas lacking buildings or manmade 

structures, eight species roost primarily in cavities or 

crevices of trees during summer (Table 1). In forests, 

this guild roosts under exfoliating bark, in hollow 

trees, and in small cavities of damaged or diseased 

trees (Ford and others 2006; Lacki and Schwierjohann 

Table 2.—Ambient temperatures (°C) for days 

when 372 controlled burns were conducted during 

November-March in the Interior Highlands of 

Arkansas, 2007-2010. Ignition time was estimated 

at 11 am for all days based on consensus from fire 

management officers.

Parameter Min Max Average

Low temp previous night (6 am) -10.6 19.4 2.0±0.34

Temp 2 hours before ignition (9 am) -8.3 21.7 7.7±0.33

Temp at time of ignition (11 am) -6.1 25.0 12.3±0.34

2001; Perry and Thill 2007c, 2008). Individual species 

may roost mostly in snags or live trees, and some 

species may use cavities more than loose bark. For 

example, evening bats tend to roost more in cavities 

than under bark (Boyles and Robbins 2006, Menzel 

and others 2001a, Perry and Thill 2008), whereas 

Indiana bats tend to roost mostly under exfoliating 

bark of live trees or snags (Foster and Kurta 1999, 

Menzel and others 2001b). However, bats may exhibit 

regional preferences for tree species and roost types 

based on the composition of available tree species 

and previous forest disturbances such as disease 

outbreaks, ice storms, fires, and tornados that create 

abundant snags or defects in particular tree species. 

Within this guild, reproductive females typically roost 

in colonies during summer, whereas adult males and 

nonreproductive females usually roost alone.

Female maternity colonies in this guild are typically 

found in relatively tall trees with abundant solar 

exposure during summer (Brigham and Barclay 

1996) where warmer roost temperatures promote 

fetal and juvenile growth (Speakman and Thomas 

2003). Among this guild, roosts in trees for both 

sexes combined average around 5-10 m above the 

ground (Lacki and others 2009a, Menzel and others 

2002b, Perry and Thill 2008). However, males of 

some cavity- and bark-roosting species often roost 

in smaller snags or closer to the ground than females 

during summer (Broders and Forbes 2004, Kurta 

2005, Lacki and Schwierjohann 2001, Perry and 

Thill 2007c). For example, Perry and Thill (2007c) 
176 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

found 21 percent of roosts of male northern longeared bats were located in small (<10 cm diameter at 

breast height [d.b.h.]) midstory trees and snags during 

summer, whereas <2 percent of female roosts were 

in these trees. Consequently, for some cavity- and 

bark-roosting species, males may be more susceptible 

than females to direct effects of fires during summer 

because of their closer proximity to the ground and 

thinner insulation provided by small diameter trees. 

Males may also enter torpor more frequently than 

reproductive females (Speakman and Thomas 2003), 

which could make arousal and escape from fire more 

difficult for males during cooler periods of summer. 

Many of the factors associated with potential injury 

to foliage-roosting bat species during summer (e.g., 

height of roosts and fire intensity) may also affect 

cavity- and bark-roosting species. However, the types 

of roosts used by cavity- and bark-roosting species 

may affect vulnerability to injury from fire. Bats 

roosting under pieces of bark, which are typically 

closed at the top but open at the bottom, may be more 

affected by rising heat and smoke, whereas bats in 

cavities are likely more protected (Guelta and Balbach 

2005). Thus, bats roosting in well insulated cavities 

located relatively high in the trees are unlikely to be 

subjected to injury. It is unknown how smoke affects 

bats in these roosts or if different types of roosts 

reduce or enhance smoke exposure to roosting bats. 

Little is known of the direct effects of fire on this 

guild, and few studies have examined escape 

behaviors, direct mortality, or potential reductions 

in survival associated with effects of fire. Dickinson 

and others (2009) monitored two northern long-eared 

bats (one male and one female) in roosts during a 

controlled summer burn. Both bats exited their roosts 

within 10 minutes of ignition near their roosts and flew 

in areas where the fire was not occurring. Among four 

bats they tracked before and after burning, all switched 

roosts during the fire, but no mortality was observed. 

Likewise, Rodrigue and others (2001) reported 

flushing of a Myotis bat from an ignited snag during an 

April controlled burn in West Virginia. 

Dormant Season Fires 

and Cavity- and Bark-Roosting Species

Many cavity- and bark-roosting species hibernate for 

extended periods during winter in northern portions of 

the region, often in caves or abandoned mines. Thus, 

many of these species are not directly vulnerable to 

dormant-season burns, with the possible exception 

of smoke intrusions into hibernacula (see below). In 

southern areas, some species including big brown 

bats, southeastern bats, Rafinesque big-eared bats, 

and evening bats, may be active and forage during 

warmer days of winter or may roost in trees (Barbour 

and Davis 1969, Boyles and Robbins 2006, Humphrey 

and Gore 1992). Furthermore, silver-haired bats are 

long-range migrants that can be found throughout most 

of the region during winter (Cryan 2003) where they 

roost in trees in southern portions of the region (Perry 

and others 2010). 

Similar to the foliage-roosting species, some cavityand bark-roosting bats that remain active during winter 

may roost on or near the ground during colder periods 

(<5 °C) of winter. For example, evening bats may use 

small mammal burrows during colder winter days 

(Boyles and others 2005), and silver-haired bats may 

be under tree roots, in rock crevices, or in tree cavities 

at ground level during colder winter days (Perry and 

others 2010). Thus, these species may use roosts that 

are more protected from excessive heat associated with 

fires than the foliage-roosting species during winter. 

For bats roosting in the ground, soil temperatures may 

not exceed 44 °C (111 °F) during prescribed burns 

at soil depths below 5 cm (Raison and others 1986). 

However, soil temperatures may exceed 200 °C (392 

°F) at a depth of 9.5 cm under heavy fuel loads such 

as slash piles (Roberts 1965). Furthermore, smoke and 

CO2

 levels in ground cavities may be benign during 

controlled burns (O’Brien and others 2006).

Fire Effects on Cavity and Snag Dynamics

Members of the cavity- and bark-roosting guild rely 

heavily on hollow trees, senescent trees, or snags, 

and availability of snags or trees with cavities may be 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 177

directly affected by fire. Snag density and population 

dynamics are complex and dependent on multiple 

factors. Age structure of stands and tree species affect 

snag dynamics. Natural disturbances such as insects, 

disease, wind and ice storms, lightning, drought, and 

wildfire all affect creation and destruction of snags. 

Snag densities are also affected by management 

prescriptions such as partial harvest, thinning, 

herbicides, and burning. Because of this complexity, 

managers often use models to predict snag dynamics in 

forest stands (McComb and Ohmann 1996, Morrison 

and Raphael 1993), and snag dynamics is included in 

the Fires and Fuels Extension of the Forest Vegetation 

Simulator model (FFE-FVS) (Dixon 2002).

Fire can affect the availability of roosting substrate 

for cavity- and bark-roosting bats by creating or 

consuming snags. Although stand-replacing or intense 

wildfires may create large areas of snags, effects of 

multiple, low-intensity prescribed burning on snag 

dynamics may be difficult to predict, especially for 

forests consisting mostly of fire-adapted species such 

as oaks. Low-intensity controlled burns with small 

fuel loads usually kill few or no overstory trees, but 

typically top-kill small (<5 cm d.b.h.) trees in the 

understory (personal observation). Low-intensity, 

ground-level fire may injure larger hardwood trees, 

creating avenues for pathogens such as fungi to enter 

and eventually form hollow cavities in otherwise 

healthy trees (Smith and Sutherland 2006). Fire 

may scar the base of trees, promoting the growth of 

basal cavities or hollowing of the bole in hardwoods 

(Nelson and others 1933, Van Lear and Harlow 2002). 

Consequently, repeated burning could potentially 

create forest stands with abundant hollow trees. Trees 

located near down logs, snags, or slash may be more 

susceptible to damage or death, and aggregations of 

these fuels can create clusters of damaged trees or 

snags (Brose and Van Lear 1999, Smith and Sutherland 

2006). However, snags created by fire may not stand 

as long as snags created by other disturbances because 

these snags may be weakened at the base by fire 

(Morrison and Raphael 1993). 

In stands with no recent history of fire, prescribed 

burns may initially create abundant snags by killing 

small trees and species that are not fire tolerant. 

Species with thin bark such as beech (Fagus 

grandifolia) and red maple (Acer rubrum), may 

suffer substantial damage or death, whereas oaks 

and hickories (Carya spp.) with thicker bark may 

suffer little or no damage (Brose and Van Lear 

1999, Hare 1965). Furthermore, smaller-diameter 

trees are at greater risk from mortality due to fire 

(Hare 1965, McCarthy and Sims 1935). Although 

burning often creates substantial numbers of small 

(<15 cm d.b.h.) snags (Horton and Mannan 1988, 

Morrison and Raphael 1993, Stephens and Moghaddas 

2005), effects on larger trees depends greatly on 

fire intensity, species of trees that are present, fuel 

loads, and past fire history. In oak savannas, frequent 

burning may eventually eliminate tree species that 

are not fire tolerant such as red maple, black cherry 

(Prunus serotina), and serviceberry (Amelanchier sp.) 

(Peterson and Reich 2001). However, long-term fire 

suppression can allow many relatively fire-intolerant 

species to grow into size-classes that are resistant 

to fire (Harmon 1984). Regardless, bats often take 

advantage of fire-killed snags. For example, Boyles 

and Aubrey (2006) found that initial burning of forests 

after years of suppression created abundant snags, 

resulting in extensive use of these burned areas by 

evening bats for roosting. Similarly, Johnson and 

others (2010) found that after burning, male Indiana 

bats roosted primarily in fire-killed maples. 

Fire may consume some standing snags. For example, 

in forests of ponderosa pine (Pinus ponderosa), loss of 

larger snags (>20 cm d.b.h.) was 43 percent following 

introduction of fire and 21 percent following second 

fires, but net loss (including new snags created by 

fire) was only 12 and 3 percent, respectively (Bagne 

and others 2008). Furthermore, Holden and others 

(2006) found fewer large (>47.5 cm d.b.h.) snags in 

ponderosa forests burned twice compared to those 

burned only once, but found no difference between 

areas burned two or three times. Thus, initial burns 
178 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

may create abundant snags and second burns may 

consume some of these, but further burns may not 

eliminate substantial numbers of large snags. However, 

comparable studies from eastern oak forests are not 

available.

Season of burning and topography also affect potential 

damage or death of overstory trees in hardwood 

stands. Winter burns tend to cause the least overstory 

damage because of cooler ambient temperatures 

and the dormant state of trees (Brose and Van 

Lear 1999). Spring burns may cause the greatest 

damage to overstory trees because of higher ambient 

temperatures, sunlight on boles, and fully hydrated 

vascular tissues that may reach lethal temperatures 

when burned (Brose and Van Lear 1999). Summer 

burns tend to be less damaging than spring burns, 

likely because of bole shading and lower intensity of 

fires (Brose and Van Lear 1999). Dry, upland sites 

on ridge tops and steep slopes tend to burn more 

intensely, and trees in these locations may be more 

susceptible to damage during fires.

Fire and Forest Structure for Roosting

Aside from creating snags, periodic prescribed burning 

may reduce the number of woody shrubs, understory 

trees, and midstory trees (10-25 cm d.b.h.) in the 

short term (Blake and Schuette 2000, Hutchinson and 

others 2005). Longer-term applications of prescribed 

fire may reduce stand density (Hutchinson and others 

2005, Peterson and Reich 2001) and complexity 

(clutter). Repeated low-intensity fire reduces clutter 

in the midstory and understory and creates more open 

forests, which may provide more favorable roosting 

(and foraging) conditions for many bat species, 

especially females during the reproductive season. 

Studies often find roost trees (mostly female) further 

from other overstory trees (Betts 1998, Brigham and 

others 1997b) and less canopy cover at roost sites 

compared to random locations (Kalcounis-Rüppell 

and others 2005). Canopy gaps created by fire may 

provide favorable roosting sites with greater solar 

exposure during summer for maternity colonies of 

some cavity- and bark-roosting species (Johnson and 

others 2009). Furthermore, maternity roosts may be 

located in areas with few midstory trees or relatively 

lower tree densities, which may provide both greater 

solar exposure and more open areas immediately 

around and below roosts that would otherwise impede 

inexperienced juvenile flyers (Perry and Thill 2007c). 

Thus, burned areas may have lower tree densities, 

less structural clutter, more open canopy, and greater 

numbers of snags, which may provide favorable 

roosting areas for many species. 

Studies often find bats favor burned areas for roosting. 

For example, Perry and others (2007b) found five of 

six species, including red bats, Seminole bats, northern 

long-eared bats, big brown bats, and evening bats 

roosted disproportionally in stands that were thinned 

and burned 1-4 years prior but that still retained 

large overstory trees. Boyles and Aubrey (2006) 

found evening bats used burned forest exclusively 

for roosting. Furthermore, Johnson and others 

(2009) found that for northern long-eared bats, roostswitching frequency, duration at roosts, and distance 

between successive roosts were similar between 

burned and unburned forests. 

Caves and Mines

Bats of 13 species may use caves during all or part of 

the year. Three bats (gray bat, Ozark big-eared bat, and 

Virginia big-eared bat) are year-round cave obligates 

(Table 1). Little is known of the effects of fire on 

adjacent cave and mine habitats used by bats, but these 

effects may be especially important in karst areas of 

the eastern oak region. Fire could alter vegetation 

surrounding entrances, which could potentially 

modify airflow (Carter and others 2002, Richter 

and others 1993). Smoke and noxious gases could 

enter caves, depending on air-flow characteristics of 

individual caves or mines and weather conditions such 

as temperature (Carter and others 2002, Tuttle and 

Stevenson 1977). Fire may not cause levels of gases 

high enough to be toxic to bats in caves or mines, 

but gases could potentially cause arousals during 

hibernation (Dickinson and others 2009). Caviness 

(2003) noted smoke intrusion into hibernacula 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 179

during winter burning in Missouri, but no arousal of 

hibernating bats was observed. No quantitative studies 

have examined smoke intrusions into caves and mines 

or smoke effects on hibernating cave bats, but this is 

an area that needs to be studied. 

FORAGING AND FIRE

Fire and Forest Structure for Foraging

Various factors can affect bat use, activity, and 

foraging within forests stands. Although studies often 

find the greatest levels of bat activity in forested 

riparian areas (Carter 2006, Ford and others 2005, 

Grindal and others 1999, Zimmerman and Glanz 

2000), bat activity and foraging may be greatly 

influenced by forest clutter. Studies throughout North 

America suggest that most bats avoid highly cluttered 

areas and prefer to forage and travel in areas with 

less clutter (Brigham and others 1997a, Erickson 

and West 2003, Hayes and Loeb 2007, Humes and 

others 1999). Bats are often more active in earlyand late-seral stages which are usually less cluttered 

than in intermediate forest stages (e.g., Burford and 

Lacki 1995a, Erickson and West 2003, Humes and 

others 1999, Loeb and O’Keefe 2006, Menzel and 

others 2005). Thinning may reduce clutter and lead to 

increased bat activity (Erickson and West 2003, Lacki 

and others 2007), although some studies suggest no 

response by bats to thinning (Tibbels and Kurta 2003). 

Responses to clutter differ among bat species. 

Differences in bat size (mass), bat morphology, and 

the echolocation frequencies used among species 

are believed to make some species more adapted to 

foraging in cluttered habitats, whereas others are 

more adapted to foraging in open habitats (Aldridge 

and Rautenbach 1987, Norberg and Rayner 1987). 

Species such as big brown bats likely forage more in 

open forests (Ford and others 2005, Ford and others 

2006), whereas northern long-eared bats and Indiana 

bats may readily utilize cluttered forests (Broders 

and others 2004, Ford and others 2005, Owen and 

others 2003, Schirmacher and others 2007), and red 

bats may use both cluttered and uncluttered habitats 

(Carter and others 2004, Menzel and others 2005). 

However, associations between individual species 

and levels of tolerable clutter are not concrete, and 

further study on foraging-habitat associations is 

needed. Total bat activity may be greater above the 

forest canopy than below, and some species, such as 

hoary bats and big brown bats, may be more active 

above the forest canopy (Menzel and others 2005). 

Reproductive condition may also affect bat foraging; 

less-maneuverable pregnant females may be less able 

to forage in cluttered habitats than nonpregnant bats 

(Aldridge and Brigham 1988). 

In general, within forest stands, fire reduces clutter 

that theoretically would provide favorable foraging 

habitat for some species. Similar to thinning, fire 

may reduce tree densities and create more open forest 

canopies. However, thinning and midstory removal 

may reduce structural clutter substantially more than 

burning alone, and bats may respond to thinning more 

strongly than simply burning. For example, in the 

Piedmont of South Carolina, Loeb and Waldrop (2008) 

found overall bat activity greater in thinned stands 

than unthinned controls, whereas activity in thinned 

and burned stands was intermediate. Fire may also 

kill small groups of trees, creating small gaps in the 

forest canopy. Small openings, such as tree gaps and 

group openings, often have higher activity than the 

surrounding forest (Menzel and others 2002a, Tibbels 

and Kurta 2003). Quantitative studies have found 

bat activity response to burned forests is generally 

favorable or not discernable. For example, following 

spring burns, Lacki and others (2009b) found homerange sizes and core areas of northern long-eared 

bats during late spring to summer were unaffected by 

burn-induced changes in habitat, but bats foraged more 

in burned habitats than unburned areas. Alternatively, 

Loeb and Waldrop (2008) found no difference in bat 

activity levels in burned and unburned habitats. 

Fire and Insect Abundance

All species of bats found in the eastern oak region are 

voracious insectivores. An individual can consume 

from 40 to 100 percent of its body mass in insects 
180 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

nightly (Kunz and others 1995). Most bats in the 

region consume insects in flight, although some 

species such as big brown bats and northern longeared bats may glean insects off foliage (Faure and 

others 1993, Stamper and others 2008). Consequently, 

abundance of nocturnal flying (and to a lesser extent, 

foliar) insects may have a direct effect on fitness of 

individual bats, but short- and long-term effects of 

prescribed burning on abundance of nocturnal flying 

insects remain unclear. 

Arthropod communities consist of numerous orders, 

families, and species that vary in natural history 

and include detritivores, herbivores, and predators. 

Therefore, responses of the overall insect community 

to fire are complex. Among individual insect taxa, 

fire and fire frequency may affect species groups 

differently, with some families increasing in burned 

areas and other families decreasing in richness or 

abundance depending on season and intensity of burns. 

Insect communities may differ between burned and 

unburned areas (Swengel 2001). Some flying insects 

(at least 40 species, mostly beetles) are attracted to 

fires, and the subgenus Melanophila use infrared 

sensors to locate fires where they lay eggs on burnt 

woody debris immediately after cooling (Hart 1998). 

Although many studies have examined effects of 

burning on insects, these studies are often not directly 

applicable to the insects available to bats in eastern 

oak forests subjected to burning. Most previous studies 

in North America have focused on effects of burning 

on insect abundance and diversity in grasslands or 

agricultural lands. Previous studies often include 

taxa that are not readily available to bats or combine 

taxa such as ground-dwelling and flying species. 

Furthermore, sampling methods used to determine 

effects of burning may affect observed responses. For 

example, pitfalls and litter sampling techniques often 

sample ground-dwelling insects that are not part of 

the food base for bats. Also, many studies of volant 

insect abundances examined diurnal insect abundance, 

and it is unclear if patterns of abundance for nocturnal 

insects mirror those of diurnal insects. Relatively few 

studies have examined effects of burning in a way 

that would provide insight into the specific groups of 

insects that bats utilize as food (i.e., nocturnal flying 

insects). 

Aside from the limitations of previous studies stated 

above, richness and abundance of herbivorous flying 

and foliar insects has long been associated with plant 

species richness (Hartley and others 2007, Knopps 

and others 1999, Murdoch and others 1972) because 

many insect species forage on the foliage, pollen, or 

nectar of specific plant species. Fires may produce 

more lush plant growth, and postburn vegetation 

may be attractive to recolonizing insects (Swengel 

2001), although size and heterogeneity of burns 

likely affect the ability of flying insects to recolonize 

burned areas. In eastern oak forests, the herbaceous 

layer harbors the majority of plant species richness, 

and burning typically increases community diversity 

and abundance of herbaceous plants (Hutchinson 

2006). Consequently, one would expect short-term 

reductions in insects due to mortality from fire and a 

temporary reduction in understory foliage, followed 

by subsequent increases in flying and foliar insects 

from enhanced abundance and diversity of herbaceous 

plants later. 

Results of studies examining burning and abundance 

of flying insects often give conflicting results. In 

grasslands, studies that collected flying insects suggest 

that recently burned sites produce more flying insects 

than nonburned sites (Hansen 1986, Nagel 1973), 

although burning may reduce abundance of grounddwelling insects (Buffington 1967, Bulan and Barrett 

1971, Seastedt 1984, Warren and others 1987). Studies 

suggest that fires may cause a short-term decrease 

of 95 percent in soil macroarthropods immediately 

after fire (Paquin and Coderre 1997), which could 

ultimately affect volant species because many volant 

species have a larval or pupae stage that is resident 

in litter or soil. Nevertheless, studies in other regions 

suggest many flying insects are resilient to burning 

and recover quickly because of their mobility, whereas 

ground- and litter-dwelling insects have low resilience 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 181

to fire (Lamotte 1975, Moretti and others 2006). In 

California chaparral, insect abundance peaked the first 

year after fire, likely because of an influx of generalist 

species that took advantage of the lush vegetation in 

the postburn area, but abundance declined the second 

and third years after burning (Force 1981). 

In oak-dominated forests of the eastern United States, 

thinning or other reductions in basal area likely has 

more of an effect on herbaceous plant growth than 

burning alone. In eastern oak forests, combinations 

of thinning and burning along with mechanical 

understory shrub control may produce substantially 

more flying insects than forest stands that are burned 

but not thinned or in unburned stands (Campbell 

and others 2007). In oak savannas, abundance of 

flying insects may be low the year of fire but quickly 

rebounds in subsequent years after burning (Siemann 

and others 1997). However, Lacki and others (2009b) 

found a 34 percent increase in nocturnal insects used 

by bats in burned areas during the first year following 

spring burns in Kentucky. Thus, fire in eastern oak 

forests may or may not cause a short-term decrease 

in abundance of flying insects, but may ultimately 

increase overall abundance. 

Fires may also have indirect effects on insect 

production. For example, in riparian areas, fires may 

increase nutrient delivery into streams and reduce 

canopy cover, which may increase water temperatures, 

all leading to increased productivity (Minshall and 

others 1997, Spencer and Hauer 1991). Increases 

in emerging insects may result from this increased 

productivity (Malison and Baxter 2010, Minshall 

2003), providing more food resources for bats. 

Malison and Baxter (2010) found streams in high 

severity burned areas had substantially greater insect 

emergence than streams in low severity burns or 

unburned areas, and bat activity in severe burn areas 

was substantially greater.

Moths are one of the most important insect groups in 

the diets of many eastern bats, and some bats are moth 

specialists, including the big-eared bats (Corynorhinus

spp.) (Burford and Lacki 1995b, Hurst and Lacki 

1997, Leslie and Clark 2002). Although most larval 

caterpillars of moths feed on vegetation (many are 

agricultural pests), adults either use nectar sources 

such as herbaceous flowers or do not feed as adults. 

Consequently, abundant and diverse herbaceous 

vegetation likely produces more food sources for 

those adults that feed. Restored woodlands subjected 

to periodic burning may produce substantially more 

nectar sources than mature unmanaged forests 

(Rudolph and others 2006). In forests, caterpillars 

of most moth species feed on woody plants such as 

oaks (Summerville and Crist 2002). Furthermore, 

early seral clearcut stands may be dominated by moth 

species whose caterpillars feed on tree species such 

as Prunus spp. and herbaceous vegetation, whereas 

mature forests may be dominated by species whose 

caterpillars feed on oaks, hickories, acorns, fungi, 

and lichens (Summerville and Crist 2002). Therefore, 

abundance and diversity of woody plants may be more 

important to moths than abundance and diversity of 

herbaceous vegetation in the understory. 

Studies of moths in the eastern oak region have 

compared abundance and diversity of moths among 

forest age classes and pasture monocultures (Burford 

and others 1999, Dodd and others 2008, Summerville 

and Crist 2002), but relatively few studies have 

examined effects of burning on moth abundance. 

Lacki and others (2009b) found a 22 percent increase 

in moth abundance the first year after burning in 

Kentucky, although the difference was not significant. 

In frequently burned pine woodlands of Arkansas, 

Thill and others (2004) found moth abundance was 

generally greater in forests managed using frequent 

fire compared to unburned controls, except for the first 

couple of months immediately following the burn.
182 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

FOREST DIVERSITY AND BATS

During landscape-level burns, differences in forest 

density and topography often result in a mosaic of 

burned and unburned areas that provide different levels 

of clutter and density of snags. For example, riparian 

areas (greenbelts, streamside management zones, 

or riparian zones) are often not subject to harvest 

or thinning and often burn less intensely than the 

surrounding forest due to greater shading and moister 

litter conditions. These buffers often provide greater 

densities of trees, more cluttered habitats, and more 

small trees and small snags than the surrounding forest 

landscape. Individual bat species may use these areas 

more or less than then their availability. For example, 

Perry and others (2007b) found that within thinned 

and burned stands, less than 2 percent of Seminole bat 

roosts were in unthinned greenbelts, whereas most (90 

percent) roosts of tri-colored bats were in greenbelts. 

Furthermore, Loeb and Waldrop (2008) found activity 

of big brown bats greater in thinned stands than 

unthinned controls, whereas activity of tri-colored bats 

did not differ among treatments. Thus, heterogeneous 

habitats created by various levels of thinning and 

burning intensity may provide a range of roosting and 

foraging habitats for a varied bat community.

CONCLUSIONS

Fire is increasingly being used in oak forests to 

promote oak regeneration, improve wildlife habitat, 

and reduce hazardous fuel loads. Although recent 

research has begun to shed light on the relationships 

among fire, bats, and bat habitat, these interactions 

are not yet understood. These interactions offer 

substantial opportunities for expanded research. 

Studies suggest burning may have positive, negative, 

or no effect on various aspects of bat ecology, but 

effects may vary among bat species, time of the year, 

fire frequency, ambient temperatures, and intensity of 

burns. In general, burning appears to improve habitat 

by creating snags and opening up habitats for foraging 

and roosting. Fire may also help create heterogeneous 

landscapes that provide a variety of habitats for 

multiple species. Abundance of bat food (insects) may 

also respond positively to fire. Direct effects of fire on 

bats during the burning process are still uncertain but 

may vary considerably due to timing and intensity of 

burns and the species of bat considered. Nevertheless, 

bats likely adapted to this disturbance over the 

millennia in areas such as the eastern oak region where 

fire has played a central role in the formation and 

maintenance of these forests. 

ACKNOWLEDGMENTS

I thank W. Mark Ford (Virginia Cooperative Fish and 

Wildlife Research Unit), Matthew B. Dickinson (U.S. 

Department of Agriculture, Forest Service, Northern 

Research Station), Mike Lacki (Department of 

Forestry, University of Kentucky), Stacy Clark (U.S. 

Department of Agriculture, Forest Service, Southern 

Research Station), and two anonymous reviewers for 

review of the draft manuscript. 

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The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
192 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

RESPONSES OF TIMBER RATTLESNAKES TO FIRE: 

LESSONS FROM TWO PRESCRIBED BURNS

Steven J. Beaupre and Lara E. Douglas

Professor (SJB), University of Arkansas, Department of Biological Sciences, 

Fayetteville, AR, 72701; Natural Resource Specialist (LED), Bureau of Land Management. 

SJB is corresponding author: to contact, call 479-575-7561 or email at sbeaupre@uark.edu.

Abstract.—Timber rattlesnakes (Crotalus horridus) are excellent model organisms 

for understanding the effects of large scale habitat manipulations because of their lowenergy lifestyle, rapid response to changes in resource environment, uniform diet (small 

mammals), and simple behaviors. We present two case studies that illustrate interactions 

between timber rattlesnakes and fire in a single large population. Case 1 describes the 

decimation and subsequent 11 year recovery of a timber rattlesnake subpopulation 

associated with a fire during a particularly vulnerable time of year. In Case 2, four 

control plots, three cut (thinned) plots, three burned plots, and three plots that were both 

cut and burned were studied. Our primary goals were to monitor responses of the food 

chain to the above four treatments and to assess timber rattlesnake responses as potential 

indicators for the relative success of manipulations. Although plant communities did 

not initially differ among treatment plots, manipulated sites experienced increases in 

early-successional annual vegetation after thinning and burning. Biannual live-trapping 

sessions indicated an increase in abundance of principal prey species after manipulations, 

although this increase was not uniform among treatments. Timber rattlesnakes that 

utilized manipulated sites exhibited enhanced growth and body condition relative to 

snakes that foraged solely in control areas. Snake physiological responses were more 

rapid and well-defined than measurable small mammal population responses suggesting 

that these top predators may potentially serve a role as indicator species for restoration 

ecology. Our case studies illustrate both direct and indirect effects, as well as dramatically 

divergent outcomes resulting from minor changes in the timing of fire application. 

BACKGROUND

Although the practices of thinning and fire application 

have become important tools for forest habitat 

management, relatively little is known about the 

responses of large-bodied ground-dwelling reptiles 

to large-scale habitat manipulations (however see 

Reinert and others 2011b). Most studies of the 

effect of fire on reptiles in eastern oak-dominated 

ecosystems have found little to no effect on diversity, 

species composition, and abundance (Ford and others 

1999, Greenberg and Waldrop 2008, Renken 2006). 

Frequently, in some treatments (typically thinned 

and burned plots) some reptiles show increases in 

abundance (Kilpatrick and others 2004, Matthews and 

others 2010), suggesting beneficial effects of fire. The 

few studies that have examined seasonal burn timing 

(Keyser and others 2004, Renken 2006) suggest that 

reptile communities may be resilient to both dormant 

and growing season burns (for a counter-example, see 

Griffiths and Christian 1996). 

Most of the afore-mentioned studies use similar 

methods. Specifically, reptile populations are sampled 

using one or more methods, including drift fences 

with funnel traps or pitfall traps. Both funnel and 

pitfall traps are subject to sampling biases since not 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 193

all reptiles can be equally caught using these methods 

(Crosswhite and others 1999, Enge 2001, Greenberg 

and others 1994, Jenkins and others 2003). In eastern 

oak-dominated ecosystems, pitfall traps tend to capture 

small mobile species such as fence lizards (Sceloporus 

undulatus), members of the five-lined skink group 

(Plestiodon spp.), ground skinks (Scincella lateralis), 

Anoles (Anolis carolinensis), small snakes such as 

garter snakes (Thamnophis spp.), and fossorial species 

such as worm snakes (Carphophis sp.) and ringnecked snakes (Diadophis spp.). Indeed, members 

of this short list tend to be the primary species upon 

which assessments of the effects of fire are made (but 

see Steen and others 2010). Funnel or box traps seem 

more effective at sampling larger snakes (Burgdorf 

and others 2005, Crosswhite and others 1999, Enge 

2001, Greenberg and others 1994, Jenkins and others 

2003, Sutton and others 2010). We note that many 

larger reptiles (e.g., box turtles, larger snakes) or 

those that are less mobile (e.g., ambush foragers such 

as the timber rattlesnake; Beaupre and Montgomery 

2007) typically occur in low density and are relatively 

poorly sampled by funnel traps and pitfalls, and thus, 

their responses to fire may be under-represented in the 

literature. Whereas we acknowledge the importance 

of a variety of trapping methods for quantifying 

community dynamics, significant information 

regarding response to environmental perturbation can 

be obtained through radio telemetry in appropriate 

target species (Beaupre 2008, Durbian 2006, Reinert 

and others 2011b). 

Long-lived vertebrates with slow life-histories (e.g., 

long life spans, low growth rates, late age at maturity, 

infrequent reproduction with small litter size) such 

as the timber rattlesnake (Crotalus horridus) that 

forage by ambush in the leaf litter (Brown 1993), may 

be especially susceptible to fire, depending on their 

evolutionary interaction with fire. Timber rattlesnakes 

are of special conservation concern throughout much 

of their geographic range as documented by their 

legally protected status throughout the northeast 

(Brown 1993). Thus, knowledge of their response 

to logging and fire may be of great value to habitat 

managers. It has been suggested that the behavior 

and physiology of top predators may be effective 

monitoring tools for assessing the outcomes of habitat 

manipulations (Beaupre 2002, Beaupre and Douglas 

2009, DeAngelis and others 1991, Dunham and others 

1989). With training, rattlesnakes may be easy to find 

(depending on species and locality), easy to measure 

and manipulate, and may provide a time- and costeffective monitoring approach. Herein, we describe 

and discuss two case studies of the response of timber 

rattlesnakes to the application of fire in a habitat 

management context. Both cases illustrate potential 

benefits and costs associated with application of fire.

STUDY SITES

We conducted studies on the McIlroy Madison County 

Wildlife Management Area (MMCWMA) in Madison 

County, northwest Arkansas. The MMCWMA is a 

public holding with a primary function as a public 

hunting ground. The MMCWMA and adjacent lands 

including Bear Hollow Natural Area (BNHA) and 

Ozark Natural Science Center (ONSC) comprise over 

6,000 ha managed for multiple uses. Topography can 

be rugged with permanent and intermittent streams, 

steep rock walls along ridgelines, periodically 

maintained food plots, and artificial ponds for game 

management. We have been continuously engaged 

in studies of the ecology and physiology of timber 

rattlesnakes at these sites since the fall of 1995 (e.g., 

Beaupre 2002, 2005, 2008; Beaupre and Montgomery 

2007; Beaupre and Zaidan 2001; Browning and others 

2005; Wills and Beaupre 2000). 

In general, forests at the MMCWMA are typical 

of disturbed Ozark hardwood forests and could be 

described as closed-canopy, dense, even-aged stands 

of mixed hardwoods and pine resulting from longterm fire suppression (Spetich 2004). Aggressive 

tree harvesting in the late 19th century followed by 

roughly 100 years of fire suppression (Guyette and 

others 2006, Smith and others 2004, Stambaugh and 

Guyette 2006) dramatically altered species dynamics, 

causing an increase in recruitment of shade tolerant 

species (Burns and Honkala 1990) while oaks and 
194 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

hickories, which once dominated these forests, had 

low establishment rates (Spetich 2004). The system 

became an even-aged, closed-canopy forest with 

relatively little herbaceous understory growth (Spetich 

2004). Canopy closure and decreased herbaceous 

growth has reduced ground-level productivity resulting 

in mast-crop (primarily acorns) dependence of wildlife 

(Fralish 2004, Spetich 2004).

The timber rattlesnake is a low-energy adapted 

ambush forager that feeds on small mammals, 

primarily including squirrels, chipmunks, and deer 

mice (Clark 2002, Montgomery 2005, Reinert and 

others 2011a, Wittenberg 2009). Previous studies 

have suggested that annual variation in acorn mast 

crop affects small mammal densities, which in turn 

rapidly affect feeding rates, growth dynamics, and 

body condition of timber rattlesnakes (Beaupre 2008). 

The population dynamics of timber rattlesnakes at 

MMCWMA can be described as “boom and bust” with 

periods of extended starvation punctuated by bursts 

of growth and reproduction associated with resource 

availability (Beaupre 2008). Their simple and narrow 

diets leave little ambiguity regarding the structure of 

their food chain. Studies of timber rattlesnakes have 

been facilitated by highly developed radio telemetry 

techniques (Reinert 1992). Their relatively small home 

ranges (as compared with predatory mammals or 

birds) and their tolerance to close approach by humans 

allows them to be repeatedly tracked on foot and 

relocated with high precision (Beaupre 2008, Reinert 

1992). The extreme sensitivity and rapid physiological 

responses of timber rattlesnakes to variation in 

the food resource environment coupled with ease 

of measurement and estimation of body condition 

potentially make them excellent bioindicators for 

assessing changes in small mammal populations as 

a result of habitat management practices that affect 

ground level seed production. Similarly, timber 

rattlesnake populations are highly sensitive to the 

effects of short-term mortality events (Brown 1993, 

Sealy 2002) and disturbances that undermine their 

food chain (Beaupre 2008).

CASE 1: DECIMATION 

AND RECOVERY AT SITE K

Background

Site K is a timber rattlesnake den complex (defined 

as an association of several independent hibernacula 

located on the same rocky outcrop) centrally located 

in our study area. The complex consists of at least 

five unique cracks that are occupied by one or more 

hibernating snakes distributed north to south along 

a 450 m west-facing ridgeline. Timber rattlesnakes 

typically emerge from hibernation in early April and 

rapidly disperse from the immediate hibernation area 

to take shelter under transitional rocks, logs, or leaf 

litter. In the weeks that follow emergence the snakes 

usually remain concealed, using cover to insulate them 

from temperature extremes while physiologically 

acclimatizing to warmer temperatures outside the den 

crevice. Prior to emergence, while in the den, snakes 

are likely insulated from damage due to surface fires. 

During a posthibernation fire, however, snakes are 

directly exposed to heat, oxygen deprivation, and 

desiccation, as they are physically located in the 

flammable substrate. 

Since the inception of our studies in 1995, sections of 

the MMCWMA have been periodically burned either 

as part of a formal management plan, accidentally, 

or as a result of arson. Fire management plans at 

MMCWMA have historically been directed at fuel 

reduction, but more recently have been designed for 

wildlife habitat improvement (see Case 2). In spring of 

1999 (between April 6 and April 15), a managementrelated fire swept through Site K involving all known 

hibernacula and transitional habitats associated 

with snakes that used the site. The fire encompassed 

approximately 10 ha and was of sufficient intensity 

to completely consume ground cover (leaf litter) and 

structure (logs) in the immediate vicinity of Site K. 

The fire occurred after emergence and during the 

period when snakes had taken refuge in transitional 

habitat, but before snakes had moved to summer 

foraging ranges.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 195

Methods

Site K has been visually surveyed during spring 

emergence (March 20-April 20, depending on weather) 

in every year since spring 1996. Although some 

variation in search effort among years is unavoidable, 

the site has been consistently surveyed (two to four 

visits per year during peak emergence) by the primary 

author. All captured snakes were transported to the 

laboratory at the University of Arkansas where they 

were individually marked (by PIT tag), sexed (by 

caudal probe), weighed (±0.01 g), and measured 

(snout-vent length [SVL], head length [HL], head 

width [HW], and tail length [TL]) in a squeeze 

box (Beaupre 2008, Quinn and Jones 1974). After 

processing, all snakes were released at their point of 

capture. 

Results and Discussion

In 4 years of spring sampling (1996-1999) prior 

to the fire, 20 individual timber rattlesnakes were 

captured from Site K, processed, and released. The 

fire occurred between April 6 and April 15, 1999, 

immediately postemergence when most snakes had 

entered vulnerable transition sites. Two snakes had 

been captured at the site in 1999 on April 6 and were 

safe in the laboratory when the fire struck. These two 

snakes were released on Site K after the fire, but no 

additional snakes were captured in 1999 at the site 

after the fire. In the years immediately following the 

fire, no snakes were found in spring surveys (Fig. 1). 

Snakes were not captured again until 2002 (n=2) with 

relative abundance increasing in 2005-2011 (Fig. 1). 

In the 12 years since the fire, 16 individual timber 

rattlesnakes have been captured at the site. The fire had 

a pronounced effect on the body size distribution of 

snakes that resided at the site (Fig. 2). Prior to the fire, 

the SVL distribution was relatively evenly distributed 

with some snakes present in all size classes, including 

several very large adult males and a large number of 

reproductively mature females near 75 cm SVL (Fig. 

2). Furthermore, active reproduction was known to 

be ongoing, as we observed pregnant females there in 

1998. In the years after the fire, there was an apparent 

complete loss of snakes in the two largest size classes 

and a shift of the most frequent size class from 75 

cm to the bin centered on 55 cm SVL (Fig. 2). This 

size class is typical of snakes roughly 3 to 5 years 

old that have not yet reached the age and size of first 

reproduction. Because timber rattlesnakes exhibit high 

den site fidelity (Agugliaro 2011, Browning and others 

2005) and highly repeatable home ranges (Beaupre, 

per obs.), we interpret this result as a near total loss 

of snakes at the site due to the effects of fire. The site 

was then slowly repopulated by dispersing young 

(Cobb and others 2005) over the 12 postfire years from 

adjacent unaffected sites. 

Figure 1.—Timber rattlesnake capture frequencies at Site 

K before (pre-spring 1999) and after (post-spring 1999) a 

destructive fire swept through the den area in the days just 

after spring emergence. Note: the two snakes captured in 

1999 were captured prior to the fire. 

Figure 2.—Site K timber rattlesnake body size (snout-vent 

length: SVL in cm) distribution before fire (black bars) and 

after fire (gray bars). Each bin represents a 10 cm range 

centered on the tick label value.
196 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Capture records before and after burns and from 

adjacent sites have revealed that 2 of the 16 snakes 

captured in later years (one male, one female) were 

present at Site K prior to the fire. We interpret these 

individuals to be persistent survivors of the fire. 

No other individuals present prefire at Site K were 

captured there or elsewhere in the study site after the 

fire. Notably, one of the two recaptured individuals 

(the male) was safely in the lab during the fire. A third 

individual of the 16 was a known migrant, captured 

and marked as a neonate on September 12, 1999 at an 

adjacent site (ca. 1150 m distant) and next appeared 

on Site K on April 9, 2005 as a small (79.6 cm SVL, 

336.94 g) adult male. The remaining 13 snakes were 

marked as new captures on Site K. One of these new 

individuals was large enough to be considered an 

adult, the remaining 12 were sub-adults, all having 

SVL of less than 60 cm. These young snakes were 

unlikely to have been present at the site prior to 2009 

and were probably either born at Site K or migrated 

from one of roughly 40 nearby areas (Browning and 

others 2005) in the years following the fire. Radio 

telemetry observations on neonate timber rattlesnakes 

in Tennessee support the contention that at least some 

neonates disperse to nonmaternal hibernacula (Cobb 

and others 2005). The persistent postfire paucity of 

adult (SVL = 65 cm) reproductive females suggests 

that most if not all of these young snakes have 

dispersed to Site K from adjacent den areas. 

The preceding data led us to the following 

interpretation. A healthy population of rattlesnakes 

hibernating at Site K was decimated (only 2 of 20 

known snakes survived) by a fire that struck after 

spring emergence when the snakes were particularly 

vulnerable. In the 12 years postfire, the site has been 

repopulated mostly by juvenile migrants from adjacent 

areas of higher timber rattlesnake density. We note 

that the site continues to recover and predict that in 

the coming years as sub-adults mature, reproduction 

will resume and a more typical size distribution will 

be reestablished. However, due to the long intervals 

between reproductive events and late female age at 

maturity in this species (Brown 1993), full recovery 

may take many more years. With respect to timber 

rattlesnakes, the severity of this fire was due primarily 

to the posthibernation timing of its application. It 

is also fortunate that the size of the fire was small, 

leaving surrounding hibernacula relatively undisturbed 

to serve as source populations for juvenile migrants.

CASE 2: CAN FIRE ENHANCE 

TIMBER RATTLESNAKE HABITAT?

Background

In 2004, we were approached by the Arkansas Game 

and Fish Commission (AGFC) and were informed 

that sections of our study site would be selectively 

thinned of timber and/or burned in an effort to enhance 

habitat quality for wildlife. Subsequent planning led 

to establishment of a detailed experimental design 

(described below). The AGFC sought to enhance 

habitat for game species, of which white-tailed deer 

(Odocoileus virginianus) and turkey (Meleagris 

gallopavo) were of primary interest. Thinning and 

burning were applied with the ultimate goal of opening 

habitat to approximate the historically present oak 

savanna or shortleaf pine forest system (Dey and 

others 2004, Guyette and others 2006).

Like white-tailed deer and turkey, small mammal 

populations (e.g., squirrels, chipmunks, and other 

rodents) are also dependent on acorn mast crop. These 

small mammals comprise over 90 percent of the diet 

of timber rattlesnakes. We hypothesized that small 

mammals would respond to increases in ground level 

food production much as deer and turkey would, and 

that rattlesnakes would in turn respond to increasing 

prey availability. Because of the ease of capture 

and measurement of timber rattlesnakes, we also 

hypothesized that they might be effective organisms 

to monitor changes in food productivity at the ground 

level. Thus, we measured changes in vegetation 

structure associated with forest manipulations, changes 

in small mammal populations, and changes in growth 

and body condition (both indicative of changes in 

resource availability) of timber rattlesnakes. Herein, 

we review the major findings of our study. A more 

detailed account can be found in Douglas (2010), and 

forthcoming publications. 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 197

Methods

In 2005, areas on ridge tops intended for timber 

harvest were identified by AGFC managers, and trees 

slated for removal were marked. Six plots ranging 

in size from 4 to 26 ha were chosen for timber 

harvest. Low-impact logging occurred during the 

summer of 2007 and was accomplished by two to 

three individuals on foot with chainsaws. Logs were 

skidded to existing forest roads and removed without 

major habitat disruption. Fire was applied on March 

12, 2008, prior to rattlesnake spring emergence. 

The net result of these management activities was 

13 experimental plots, including 3 plots that were 

only harvested (cut-only), 3 plots that were both 

harvested and burned (cut-burn), 3 plots that were 

burned but not harvested (burn only), and 4 plots 

(control) that were not manipulated. Our experimental 

design approximated a BACI (before, after, control 

impact) design (Williams and others 2001). However, 

manipulated plots were located on ridge tops only 

and were chosen based on accessibility and suitability 

for harvest and the ability to control application of 

fire. Thus, plots were not chosen at random, a normal 

assumption of BACI design, weakening inferences 

about the effects of manipulations by potential 

interactions related to the geographic proximity of 

certain site types (Bennett and Adams 2004). All 

experimental and control plots were located within 

known home ranges of several timber rattlesnakes, and 

plots were sized and located such that several snakes 

could occupy a plot simultaneously, but all snakes 

could easily avoid all manipulated plots.

Vegetation

We monitored plant diversity and community 

composition at all sites beginning in summer 2005 

and continued throughout the study (Douglas 

2010). Circular quadrat surveys (Cox 1980, Lindsey 

and others 1958, Patterson and James 2009) were 

employed at three spatial scales (1 m2

, 15 m2, and 

0.04 ha) three times per year to examine herbaceous 

plants, understory saplings and shrubs, and mature 

trees. Species were identified on site using field guides 

(Hunter 2004, Little 1980). Problematic identifications 

were confirmed with the help of ONSC field staff, 

Professor Doug James at the University of Arkansas, 

or University of Arkansas Herbarium staff. Data 

were analyzed by a variety of techniques, including 

MANOVA and principal components analysis. 

Small Mammals

Small mammals at all 13 plots were sampled 

biannually (spring, late summer) from 2005 to 2009 

using Sherman live traps (3” x 3.5” x 10” LFAHD 

Folding Trap and 3310A Non Folding Trap, H.B. 

Sherman Traps, Tallahassee, FL), with populations 

assumed to be open between trapping periods. Each 

trapping session lasted five nights (after five nights 

of prebaiting), a brief period through which the 

population was treated as closed. Fifty traps were set 

per site per night, with 4 of the 13 sites sampled per 

night. Trapped animals were marked with a unique 

ear tag (Self Piercing Fish Tag, National Band and 

Tag Company, Newport, KY) and released, and marks 

were used to identify recaptured individuals. Trap 

data were analyzed by Lincoln-Peterson estimator and 

by trap success rates which can be adjusted for trap 

disturbance and, in this case, provided qualitatively 

similar results to more formal population density 

estimators (Douglas 2010).

Rattlesnake Physiological Responses

Snakes were captured between 2006 and 2009 

during routine den and gestation site surveys and 

incidentally during random walks through study areas. 

We surgically implanted radio transmitters (Holohil 

SI-2T, Holohil Systems, Ltd., Carp, Ontario) in the 

coelomic cavity of adult snakes (minimum 300 g) 

under anesthetic (Beaupre 2008, Reinert and Cundall 

1982, Wills and Beaupre 2000). Depending on year, 20 

to 30 snakes were tracked approximately three times 

weekly using portable receivers (Wildlife Materials 

TRX 1000s, Murphysboro, IL or Communication 

Specialists Inc. R1000 receiver, Orange, CA) and 

hand-held antennae (Yagi three-element directional 

antenna). Snake locations were recorded using a 

Garmin GPS III Plus (Olathe, KS). At least twice per 

active season, snakes were captured and brought to 

the lab for morphometric measurements (SVL, HL, 

HW, TL, and body mass) as described above (Case 
198 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

1). All measurements were made by the first author to 

minimize observer bias. Morphometric measurements 

were used to estimate growth rates in SVL (cm/year) 

and body condition (residuals from a nonlinear masslength regression; a measure of fatness relative to 

length) (Beaupre and Douglas 2009). Snakes that 

spent more than a week of the active season foraging 

in manipulated areas were classified as manipulated 

(man). Snakes that spent their entire active season 

away from manipulated areas were classified as 

controls (con). Thus, statistical comparisons (repeated 

measures analysis of variance) were possible 

among treatments both before and after the habitat 

manipulations (Douglas 2010). 

Results and Discussion

Major shifts in vegetation occurred from 2005 to 2009 

in association with both experimental manipulations 

and natural events that affected canopy density and 

dynamics. The most significant component of habitat 

change was associated with increases in sun grasses, 

early annuals, early perennials, shade perennials, 

sassafras, blackberry, and sedges. Most of these groups 

are associated with invasions of forest openings and 

are seed-producing. In addition to planned forest 

treatments, all sites including control sites were also 

affected by natural events between 2005 and 2009. In 

2005, all sites clustered closely to the grand mean of 

pre-manipulation sites, suggesting that sites were quite 

similar prior to manipulations. However, each plot 

type exhibited a different response to manipulation 

with burn and cut-burn sites exhibiting increases 

in seed-producing sun-tolerant species, and control 

and cut sites exhibiting increases in tree recruitment 

(Douglas 2010). Application of logging and fire 

caused significant shifts in vegetation communities 

observed at our 13 sites. Paradoxically, control sites 

exhibited large shifts in vegetation, although in a 

slightly different multivariate direction than burned 

sites. We attribute this shift in control sites to a severe 

ice storm in February of 2009 that caused a significant 

canopy opening event, subsequently changing incident 

sunlight on the ground and affecting vegetation 

assemblages. Thus, control sites responded in a 

similar multivariate direction as thinned (cut-only) 

sites, but to a lesser degree. Burn-only and cut-burn 

sites shifted significantly toward greater density of 

ground level seed producing annuals and perennials. 

All manipulated sites showed increases in ground 

level seed producing plants, thus cutting and burning 

did achieve, to some measure, intended management 

objectives at the MMCWMA.

Small mammal trapping data were collected for a 

total of 25,750 trap-nights, adjusted to 21,596 when 

disturbance by larger mammals (e.g., raccoons, 

skunks, opossums) was accounted for. During this 

time, there were 1016 total captures of 463 individuals. 

Capture rates varied from 0 to 45 captures per 100 

trap-nights, with a mean of 5.58 captures per 100 

trap-nights. Eight potential snake prey species were 

captured, although the vast majority of all mammals 

captured (92.7 percent) were either deer mice 

(Peromyscus maniculatus) or white-footed mice 

(Peromyscus leucopus). After adjusting for high trap 

disturbance rates and using different approaches to 

cope with departures from normality in trapping data, 

we are confident that there were significant changes 

in small mammal capture success over time and that 

the responses were dependent on treatment (Douglas 

2010). Our data suggest that small mammal trapping 

success increased in cut, cut-burn, and control sites, 

while staying relatively unchanged at burn-only 

sites. The degree of increase in trapping success was 

greatest at cut-burn sites. Together with vegetation 

data, these results are consistent with the hypothesis 

that manipulations improved food availability in 

manipulated plots, and a numerical response of small 

mammals resulted. Enigmatically, burn-only sites 

exhibited some shift in vegetation but did not result 

in increased small mammal abundance. One possible 

explanation is that continued presence of closed 

canopy and reduction of ground level complexity did 

not favor small mammals. Also, snakes foraged in 

burn-only sites, and the lack of structural complexity 

compared to cut and cut-burn sites may have enhanced 

their prey capture success by reducing obstructions 

to sensory reception and strike mechanics. There is 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 199

also evidence (Douglas 2010) that burn-only sites 

are thermally extreme (hotter than other treatments), 

which may adversely affect small mammals. 

Surprisingly, control sites also exhibited small but 

significant increases in small mammal abundance, 

which we attribute to increases in ground level seed 

production after a canopy-opening ice storm. In our 

more complete analyses (Douglas 2010), LincolnPeterson abundance estimates were highly correlated 

with capture success estimates, and both methods 

yield similar conclusions regarding increases in 

small mammals that serve as prey species for timber 

rattlesnakes. Thus, we concluded that snake prey 

abundance increased at cut-only and cut-burn sites 

relative to control and burn-only sites. 

Prior to habitat manipulations, the growth rates of 

snakes that used areas planned for manipulation 

were not statistically distinguishable from snakes 

using control areas (Douglas 2010). However, after 

application of thinning and fire, snakes that used 

manipulated sites exhibited statistically significant 

increases in growth rates (Douglas 2010). Body 

condition in snakes using control areas appeared to 

decrease from 2005 to 2009, whereas body condition 

for snakes using manipulated areas did not change and 

was maintained at healthy levels. Thus, control areas 

were poor sites for snake mass gain throughout the 

duration of the study, whereas the best plots were the 

manipulated sites. Furthermore, a regression of body 

condition on proportion of time spent in manipulated 

plots was significant suggesting increased foraging 

success in manipulated plots (Douglas 2010).

Growth rates and body conditions of timber 

rattlesnakes were improved for snakes that used 

manipulated areas after manipulations occurred. 

This was consistent with expectations from previous 

studies of the effects of elevated resource levels 

on rattlesnakes (Beaupre 2008, Taylor and others 

2005). Also, use of manipulated habitat for a greater 

proportion of a snake’s active season was associated 

with higher body condition index (Douglas 2010). 

Therefore, increased use of manipulated habitats 

appears to result in healthier snakes. In light of 

these data, we suggest that not only does habitat 

manipulation enhance habitat quality for timber 

rattlesnakes, but also that both body condition and 

growth rates of timber rattlesnakes may be viable 

indicators of the effectiveness of large-scale habitat 

manipulations. Timber rattlesnakes responded 

rapidly to changes in resource environment, and their 

physiological responses were more immediately 

and unambiguously measured than changes in small 

mammal abundance or capture success which is highly 

variable and requires very large allocation of resources 

and effort.

CONCLUSIONS

Our two case studies located in the same experimental 

system offer dramatically different lessons regarding 

the response of timber rattlesnakes to the application 

of fire in an Ozark oak ecosystem. We offer several 

caveats regarding our observations and the quality of 

our experimental data. Results obtained are clearly 

specific to our sites and our general approach. The 

effects of logging and fire application on reptiles in 

general are likely highly variable, and dependent on 

a number of relevant conditions. For example, as 

demonstrated by Case 1, the severity and timing of 

fire application will likely have a profound effect on 

outcomes for ground-dwelling reptiles. Application 

of fire immediately after emergence had a local 

but devastating effect on ground-dwelling, leaflitter hiding timber rattlesnakes. For Case 2, prior 

knowledge of the pending manipulation allowed us to 

negotiate with AGFC to apply fire to the system prior 

to spring emergence of most large-bodied reptiles 

present in our system. Foreknowledge and planning 

resulted in dramatically different outcomes than those 

seen at Site K. Thus, timing is critical, and at least for 

the preservation of timber rattlesnakes, fire is probably 

best applied during their natural dormant season.

The vulnerability of timber rattlesnakes and other 

large-bodied snakes to fire during the growing season 

is unknown. Aside from post-spring emergence, snakes 
200 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

in particular may also be vulnerable during ecdysis, 

when eyesight and other senses are impaired as old 

skin lifts and separates from new tissue in preparation 

for shedding (Means and Campbell 1981, Russell 

and others 1999). Clearly, the ability of a species to 

endure fire will depend upon its evolutionary history 

and the frequency and intensity of fires in its native 

habitat. Nevertheless, some accounts in the literature 

suggest that rattlesnakes can survive low intensity 

growing season fires in nature. For example, only 

2 of 68 marked eastern diamondback rattlesnakes 

(Crotalus adamanteus) succumbed to direct effects of 

prescribed fire in a Florida scrub ecosystem (Means 

and Campbell 1981). Likewise, low intensity fires 

in desert island systems can be survived by montane 

rattlesnake species (Smith and others 2001). However, 

in the French Alps, an autumn grassland burn (while 

snakes were still active) doubled the mortality rate of 

the highly endangered Orsini’s viper (Vipera ursinii), 

and surprisingly, the snakes showed no improvement 

in body condition in the postfire environment (Lyet 

and others 2009). It is also clear that intense growing 

season fires can be catastrophic for rattlesnakes in 

some systems. The first author witnessed such an event 

in the Sonoran Desert in July 1995 when a thriving 

population of western diamondback rattlesnakes 

(Crotalus atrox) was locally extirpated, mostly by 

indirect effects, in the aftermath of the Rio Verde fire 

which consumed over 20,000 acres (Beaupre 1995). 

In any event, growing season fires should be expected 

to produce some mortality and possibly high mortality 

under some conditions. For healthy populations of 

common species, this mortality may be tolerable. For 

small relict populations of sensitive or threatened 

species, dormant season burns or alternatives to fire 

should be considered. 

We also suggest that initial conditions of the 

manipulated forest will profoundly influence 

outcomes. Degraded forests are likely to benefit 

through increases in heterogeneity, and associated 

food production. Healthy climax forests would likely 

be adversely affected. Furthermore, maintenance of 

a healthy disturbance-dependent state requires not 

only the initial manipulation, but frequent return of 

fire to the system. However, optimal intervals of fire 

return for most vertebrates are unknown. In addition, 

climate-related weather events (e.g., ice storms, late 

freezes) have the capacity to impact experimental 

data, providing less than perfect confidence in all 

interpretations. 

Finally, we caution the reader by reminding of some 

shortcomings in our Case 2 experimental design. In 

violation of the assumptions of a formal BACI design 

(Williams and others 2001), our sites were not chosen 

at random but were restricted to ridge tops and areas 

with sufficient logging access to saleable timber. This 

is less an admission of flawed experimental design and 

more of an acknowledgment of reality and the need 

to seize opportunities to forward our understanding, 

however imperfect they may be. Furthermore, all of 

our postmanipulation observations were made under 

transient successional dynamics. A critical question 

is whether differences in vegetation, small mammal 

abundance, and indicators of rattlesnake health 

will persist as the system settles into a long-term 

disturbance-dependent state. 

ACKNOWLEDGMENTS

We thank the conference organizers for the invitation 

to participate and for the hard work of conference 

logistics. Kory Roberts (namesake of Site K), Joseph 

Agugliaro, and James Van Dyke made substantial 

contributions to field data collection on radiotagged snakes. We thank D. Steen and W. Sutton for 

comments on the manuscript. We are indebted to the 

Arkansas Game and Fish Commission, Arkansas 

Natural Heritage Commission, and Ozark Natural 

Science Center for allowing surveys and access to 

their property, and to Martin Blaney, Carrie McQueen, 

Ray Boutz, Ray Wiggs, and Bob Wilson for their 

assistance in coordinating forest manipulation efforts 

with this study. Doug Fletcher and the Arkansas 

Natural Heritage Commission supported several 

pre-manipulation small mammal surveys. We also 

thank the University of Arkansas Honors College-
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 201

ENDY Research Mentoring Experiences for Students 

program, which supported summer fellowships to hire 

field assistants. This research was supported by the 

National Science Foundation (#IBN-9728470, #IBN0130633, and #IBN-0641117 to S.J. Beaupre, and 

Graduate Research Fellowship to L.E. Douglas) and 

the Ozark Society (Neil Compton Scholarship to L.E. 

Douglas).

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conference. Gen. Tech. Rep. SRS-71. Asheville, 

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The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
An Emerging Fire Program
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Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 207

GENESIS OF AN OAK-FIRE SCIENCE CONSORTIUM

Keith W. Grabner, Michael C. Stambaugh, Richard P. Guyette, 

Daniel C. Dey, and Gary D. Willson

Ecologist (KWG), USDI Geological Survey, Columbia Environmental Research Center, 

4200 New Haven Rd, Columbia, MO 65201; Research Associate (MCS); Professor (RPG); 

Research Forester (DCD); Research Coordinator (GDW). KWG is corresponding author: 

to contact, call 573-441-2782 or email at kgrabner@usgs.gov.

Abstract.—With respect to fire management and practices, one of the most overlooked 

regions lies in the middle of the country. In this region there is a critical need for both 

recognition of fire’s importance and sharing of fire information and expertise. Recently 

we proposed and were awarded funding by the Joint Fire Science Program to initiate 

the planning phase for a regional fire consortium. The purpose of the consortium will 

be to promote the dissemination of fire information across the interior United States and 

to identify fire information needs of oak-dominated communities such as woodlands, 

forests, savannas, and barrens. Geographically, the consortium region will cover: 1) the 

Interior Lowland Plateau Ecoregion in Illinois, Indiana, central Kentucky and Tennessee; 

2) the Missouri, Arkansas, and Oklahoma Ozarks; 3) the Ouachita Mountains of Arkansas 

and Oklahoma; and 4) the Cross Timbers Region in Texas, Oklahoma, and Kansas. 

This region coincides with the southwestern half of the Central Hardwoods Forest 

Region. The tasks of this consortium will be to disseminate fire information, connect 

fire professionals, and efficiently address fire issues within our region. If supported, the 

success and the future direction of the consortium will be driven by end-users, their input, 

and involvement.

Introduction

With respect to fire management and fire practices, 

one of the most overlooked regions lies in the middle 

of the country (Pyne 2009). In this region there is a 

critical need for both recognition of fire’s importance 

and sharing of fire information and expertise. Fire 

science delivery is severely limited with dissemination 

of research results relying primarily on scientific 

publications or presentations, if the research is 

disseminated at all. There is no formal fire science 

laboratory at any level (federal, state, or private) and 

fire information delivery is primarily through the 

Forest Service’s Northern Research Station. Smaller 

groups such as the Fire Learning Network (The 

Nature Conservancy) and Prescribed Fire Councils 

exist, however there is limited correspondence, 

collaborative activities, or advertisement by these 

groups, particularly at a large scale and encompassing 

regional fire regimes. Many prescribed fire programs 

and demonstration plots exist in the region that would 

benefit fire discussions between practitioners and 

scientists. Long-term research programs that provide 

cutting-edge fire information exist in the region (e.g., 

OK-FIRE [Carlson and others 2010], pyric herbivory 

[Fuhlendorf and others 2009], fire history) that would 

benefit fire managers outside the region; however their 

exposure has been limited. 

We are in the planning stages towards developing 

a fire information consortium that will promote 

the dissemination of fire information across the 

interior United States and that will focus on fire 
208 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

information needs of oak-dominated communities 

such as woodlands, forests, savannas, and barrens. 

A consortium is defined as a group of individuals or 

organizations formed to undertake an activity that is 

beyond the capabilities of the individual members. 

This consortium will connect fire professionals and 

will address fire issues within the region. Consortium 

activities will be determined by a needs assessment of 

end users, but are likely to include

• developing an information clearinghouse (e.g., 

website) to serve the consortium region;

• highlighting regional fire management and 

research;

• development/access to online fire bibliography;

• presentations via webinars regarding regional 

management or research activities;

• organization of fire management and fire 

science symposia at national, regional, and state 

conferences; and

• supporting and initiating field visits for 

fire professionals to meet and discuss their 

respective needs. 

FIRE CONSORTIUM REGION

The geographic region of this consortium consists 

primarily of the oak-hickory and western mesophytic 

forest regions (Braun 1950). The region is bordered 

by the tallgrass prairie of the Great Plains to the north, 

the Appalachian Mountains to the east, the Mississippi 

alluvial plain and the Upper West Gulf Coastal plain 

to the south, and the southern mixed and shortgrass 

prairie to the west (Fig. 1). The region covers nearly 

1 million hectares and touches 11 states. The unifying 

features of this region include: 1) historically (last 

1000+ yr) oaks were a dominant tree species and 

2) fire was an important disturbance affecting 

vegetation development and the corresponding 

habitat. Oaks remain an important component of this 

region despite fire disturbance being largely lost due 

to fire suppression, land use changes, agriculture, 

and urbanization. Within this region, agricultural 

commodities (e.g., livestock, crops, and wood 

products) are economically important and have had 

important influences on fire regimes.

Figure 1.—The approximate region of the planned oak-fire consortium.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 209

Largely due to historic repeated burning, many oak 

communities within this region were comprised of 

savannas and woodlands with open canopies capable 

of supporting diverse herbaceous plant assemblages. 

In addition to fire, grazing by native herbivores likely 

influenced this vegetation structure, however little is 

known to what extent and importance. Furthermore, 

prolonged drought, though potentially infrequent, 

was likely an important factor influencing vegetation 

and annual acres burned. Historically, fire frequency 

broadly varied along a latitudinal gradient that was a 

function of the region’s continental climate (Guyette 

and others 2006). Fire frequencies likely averaged 10 

years or less for these fire-maintained communities. 

Fire regime characteristics common to the region 

include: dominance of dormant season fire events, 

relatively low lightning ignition frequency, surface 

fires, low- to mixed-severity fires, and potential for 

broad extent fires in areas with low to moderate 

topographic relief. 

Today, prescribed fire is commonly used in the region 

for ecosystem management, but its acceptance ranges 

widely (McCarty 2005). Roughly half a million acres 

or more currently burn annually from prescribed 

and wildland fires. Fire research has historically and 

is currently being conducted within the region by 

scientists at federal and state agencies and universities. 

Key fire organizations include the U.S. Forest Service, 

Northern Research Station Units (Delaware, OH, 

Columbia, MO, and the Eastern Area Modeling 

Consortium), Oklahoma State University, Texas 

A&M University, Texas Tech University, University 

of Arkansas, University of Illinois, University of 

Kentucky, and University of Missouri. Fire science 

is generally communicated to end users via federal 

agency proceedings, scientific journals, university 

extension, and professional societal meetings. 

The region contains a diverse representation of 

federal public lands including: 5 national forests, 

11 national park service units, 11 wildlife refuges, 1 

Native American administered land, and numerous 

Department of Defense managed lands. Currently there 

is no formal group that organizes and disseminates fire 

science for agencies or organizations within the region. 

Many challenges of fire managers are specific to the 

region proposed. Key regional challenges related to 

fire include: controlling tree expansion into woodlands 

(juniper, oak, and pine), restoration of historic 

vegetation communities, oak regeneration, ecosystem 

management, invasive and exotic species control, 

managing small remnant grasslands, and assessing 

and managing fire risk in grassland and woodland 

ecosystems.

FIRE CONSORTIUM ORGANIZATION

Ultimately much of the planning and activities of the 

consortium will be determined from surveys and needs 

assessments of the end users. Although the consortium 

proposal was led by the authors we envision the 

consortium to be a user-driven consortium in that its 

goals and activities come from input of end-users. 

During proposal development fire professionals from 

throughout the region expressed their interest in the 

consortium formation. Consortia already developed 

in other regions of the United States have provided 

examples and guidance for how this consortium may 

be organized. We intend to provide a fire science 

delivery system for information that targets a wide 

range of end users and utilizes existing Web resources 

where available. We intend to design the consortium 

to be an inclusive organization that will provide 

information for fire science professionals to fire 

novices.

Based on the guidance of the Joint Fire Science 

Program, we expect the consortium to have a 

coordinator, governing board, and advisory board. 

Activities of the consortium will be directed by 

a governing board comprised of fire managers, 

practitioners, and scientists. The governing board 

will provide a long-term vision, guidance, and review 

of consortium effectiveness. These individuals will 

be geographically distributed across the consortium 

region, and represent a collaborative and multiinstitutional team.
210 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

The advisory board will guide the activities of the 

consortium. The role of the advisory board will be to 

ensure the consortium is addressing its overarching 

mission, meeting the goals of the Joint Fire Science 

Program’s Fire Science Delivery Network, and 

effectively administrating programs. The advisory 

board will evaluate the effectiveness of the consortium 

by interviewing end-users and evaluating the amount 

of participation in consortium supported conferences 

or workshops. The advisory board will consist of 

representatives from state and federal agencies, 

regional nongovernmental organizations (NGOs), 

private landowners, and private industry. Additionally 

the advisory board will include a mix of researchers, 

managers, and administrators. This mix will ensure 

that the consortium is addressing as wide range of fire 

issues pertinent to the region.

Intended Focus of the Consortium

The guiding principles of the consortium will mirror 

those of the Joint Fire Science Delivery Network: 

1. Be inclusive; make sure all partners have the 

opportunity to be involved.

2. Serve as a neutral science partner.

3. Be customer driven, both in structure and 

function.

4. Operate collaboratively by fostering joint 

management and science communication.

5. Be innovative; pursue new and creative ways to 

disseminate knowledge.

6. Facilitate the flow of fire science information, 

dialogue of new science findings, and needs of 

resource managers and policymakers.

FUTURE WORK

The consortium will collate fire science information 

and develop a method for sharing this information 

in an interactive format. The primary focus of the 

consortium will be to assist in the dissemination of 

fire science information relevant to the needs of fire 

practitioners and researchers. The consortium will 

work to address the objectives of the Joint Fire Science 

Programs fire science delivery network.

Dissemination of information and building 

relationships. Information will be disseminated by the 

consortium through many outlets. A website will act 

as a portal for regional fire information, events, and 

regional fire professional contacts. Research highlights 

and publications will be made available through 

the website. The consortium will utilize traditional 

web-based information sharing tools but will remain 

receptive to emerging methods for information 

distribution (e.g., mobile messaging). 

Listing and describing existing research and 

synthesis information/methods to assess the 

quality and applicability of research. One of the 

first goals of the consortium will be to identify fire 

science research that has occurred within the region 

and develop an online bibliography that will include 

peer reviewed literature, gray literature, and internal 

reports. While the bibliography is being developed, 

manuscripts will be reviewed and the information 

assessed for applicability across the region. In addition 

to developing a regional bibliography, a geodatabase 

of current fire research will be created, perhaps using 

existing resources (e.g., Conservation Registry).

Demonstrating research on the ground. The 

consortium will ensure that fire research and 

monitoring projects within the region are highlighted. 

Updates of ongoing fire research will be made 

available through the consortium using multiple 

methods. We will host field days where researchers 

and fire managers can meet and interact at fire research 

or management sites and receive tours of on-theground operations. Additionally, field projects will be 

highlighted through webinars. Webinars will permit 

information sharing with consortium members across 

the region without the time and expense of travel. 

Webinars will be archived and made available for 

future access.

Other methods for highlighting research occurring 

in the region will include consortium participation 

in regional natural resource conferences. Regional 

conferences include, but are not limited to, the Central 

Hardwoods Conference, the North American Prairie 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 211

Conference, the Midwest Savanna and Woodland 

Conference, and the Midwest Fish and Wildlife 

Conference. Although the consortium’s focus will be 

regional, we will also be represented at national fire 

meetings.

Adaptive management. The consortium has the 

potential to act as a catalyst for the development of 

adaptive management projects across the region. By 

enabling communication between researchers and 

fire managers throughout the region, the consortium 

can promote cooperation and collaboration in 

the development of studies utilizing an adaptive 

management framework.

New partnerships. The consortium will promote 

establishing new relationships between fire researchers 

and practitioners. Consortium led meetings such as 

field days, regional conferences, and teleconferences 

will enable managers to provide input into fire 

research direction and needs.

Needs assessment for end-user communities. 

A needs assessment will be conducted to identify 

end-users and their fire information needs. Needs 

assessments will be conducted using an online survey, 

phone interviews, and face-to-face interactions. We 

envision end-users will include private landowners, 

private, state, federal, and Native American land 

managers, fire professionals, and scientists. In 

addition, we expect that over 50 colleges and 

universities and numerous NGOs within the region 

will become active in the consortium.

CONCLUSION

A final proposal for this planned consortium will be 

considered in October 2011. If funded, consortium 

operations should be underway quickly based on the 

planning-phase work. Existing consortia across the 

United States have been funded with 2-year budgets 

with possible continuation. Additional support for 

consortia is leveraged from partners who benefit from 

its existence.

LITERATURE CITED

Braun, E.L. 1950. Deciduous forests of eastern 

North America. New York, NY: McGraw-Hill. 

596 p.

Carlson, J.D.; Bidwell, T.; Wolfinbarger; M.; 

Blackburn, S.; Jabrzemski, R. 2010. OK-FIRE: 

a weather-based decision support system for 

wildland fire managers in Oklahoma. Final 

report for Project Number 05-2-1-81 to the Joint 

Fire Science Program. 30 p. Available at www.

firescience.gov/projects/05-2-1-81/project/05-2-1-

81_jfsp_final_report_05-2-1-81_ok-fire.pdf. 

(Date accessed unknown).

Fuhlendorf, S.D.; Engle, D.M.; Kerby, J.; Hamilton, 

R. 2009. Pyric herbivory: rewilding landscapes 

through the recoupling of fire and grazing.

Conservation Biology. 23: 588-598.

Guyette, R.P.; Dey, D.C.; Stambaugh, M.C.; Muzika, 

R. 2006. Fire scars reveal variability and 

dynamics of eastern fire regimes. In: Dickinson, 

M.B., ed. Proceedings, Fire in eastern oak forests: 

delivering science to land managers; 2005 

November 15-17; Columbus, OH. Gen. Tech. Rep. 

NRS-P-1. Newtown Square, PA: U.S. Department 

of Agriculture, Forest Service, Northern Research 

Station: 20-39.

McCarty, K. 2005. Ecological management.

In: Nelson, P.W., ed. The terrestrial natural 

communities of Missouri. Missouri Natural 

Areas Committee. Jefferson City, MO: Missouri 

Department of Natural Resources. 550 p.

Pyne, S.P. 2009. People of the prairie, people of the 

fire. Tucson, AZ: Wildland Fire Lessons Learned 

Center. Available at http://www.wildfirelessons.

net/uploads/People_of_Prairie2.pdf. (Date 

accessed unknown).

The content of this paper reflects the views of the 

author(s), who are responsible for the facts and accuracy 

of the information presented herein.
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Extended Abstracts
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Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 215

GROWTH RESPONSE OF MATURE OAKS FOLLOWING TSI 

AND PRESCRIBED BURNING TREATMENTS

Margaret Anderson, Eric J. Holzmueller, Charles M. Ruffner, and John W. Groninger

Research Assistant (MA), Assistant Professor (EJH), Professor (CMR and JWG). Department of 

Forestry, 1205 Lincoln Drive – MC 4411, Southern Illinois University, Carbondale, IL 62901. 

EJH is corresponding author: to contact, call 618-453-3708 or email at eholzmue@siu.edu. 

Abstract

Oak dominated forests were historically maintained by periodic, low intensity fires in 

southern Illinois, but over the past century, fires have generally been suppressed, resulting 

in the increased abundance of fire intolerant species and decreased oak abundance 

(Ruffner and Groninger 2006). Recent research indicates that mechanical thinning 

(timber stand improvement, TSI) and prescribed fire increase the regeneration of oak 

species and suppress the development of fire intolerant species (Carril 2009). However, 

it is unclear how the residual oak trees respond to these treatments. The objective of this 

project was to assess how two forest management practices, TSI and prescribed fire, 

affect the growth of residual trees in oak dominated forests. 

Three sites were selected for this study. Each site was similar in terms of slope, aspect, 

elevation, and site index. Prior to treatment all sites had a two-aged structure and were 

dominated by oak and hickory species in the overstory and sugar maple, white ash, and 

American elm in the understory. Each site was divided and randomly assigned one of 

four treatments: 1) TSI, 2) prescribed burning, 3) TSI and prescribed burning, or 4) no 

treatment (control). TSI treatments removed all undesirable trees < 8 inches in 2002. 

Stumps were treated with herbicide (Garlon 4, Triclopyr - 16 percent a.i.) immediately 

following cutting. Prescribed burning treatments were applied in the spring of 2002 and 

2006. In 2010, we sampled 10 dominant or codominant oak trees from each treatment at 

each site to determine differences in growth among treatments. 

Results indicated that there was no difference in growth, either pretreatment or 

posttreatment, among the three sites (P > 0.12). Mean age of the sampled trees across 

all sites was 102, and posttreatment growth across all treatments was minimal, ranging 

from 0.07 to 0.08 inches/year. There did not appear to be any increased growth following 

the cutting and/or burning treatments when compared to pretreatment growth (P = 0.63), 

and these treatments did not differ when compared to the control (P = 0.58). Growth, 

however, did appear to be related to tree age (r2

 = 0.44, P = 0.01) indicating that, on 

average, younger trees grew slightly more than older trees. 

Although TSI and/or prescribed fire did not increase residual oak growth when compared 

to the control, these treatments can still be beneficial because of the associated increased 

oak regeneration (Carril 2009). Examination of the growth rates of the cored trees over 

time indicated these stands were mature and well beyond peak annual growth. Our results 

suggest that working with younger stands and/or additional management (e.g., heavier 

cutting) may be necessary to increase residual tree growth.
216 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

LITERATURE CITED

Carril, D.F. 2009. Effects of repeated prescribed fire and thinning from below on 

understory components of southern Illinois oak-hickory forests. Carbondale, IL: 

Southern Illinois University. 115 p. M.S. thesis.

Ruffner, C.M.; Groninger, J.W. 2006. Making the case for fire in southern Illinois 

forests. Journal of Forestry. 104: 78-83.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 217

USING REMOTELY-SENSED IMAGERY TO MONITOR 

POST-FIRE FOREST DYNAMICS IN UPLAND OAK FORESTS 

ON THE CUMBERLAND PLATEAU, KENTUCKY

Mary Arthur, Christine McMichael, and Gretchen Sovkoplas

Professor (MA and GS), Department of Forestry, University of Kentucky, 214 T.P. Cooper Building, 

Lexington, KY 40546-0073; Associate Professor (CM). MA is corresponding author: 

to contact, call 859-257-2852 or email at marthur@uky.edu.

abstract

Throughout the central hardwood and southern Appalachian regions, forest managers 

are increasingly using prescribed fire to achieve a suite of management objectives. When 

such management occurs on federal lands, monitoring is mandated to determine the 

efficacy of prescribed fire to achieve stated objectives, yet limited funding for such efforts 

restricts the number, size, and spatial array of monitoring plots. Monitoring is typically 

done with a small number of monitoring plots across very large landscapes, and therefore, 

is limited in its ability to reveal the true landscape-scale impact of forest management. 

Based on its use in other forested ecosystems, remote sensing data have the potential to 

provide accurate and relatively inexpensive information in support of landscape-scale 

management objectives in central hardwood and southern Appalachian forests. Here we 

describe our preliminary efforts to develop this approach.

We used Landsat 5 Thematic Mapper satellite imagery to: (1) calculate the Normalized 

Difference Vegetation Index (NDVI) as a function of the red and near-infrared reflected 

energy, such that greener vegetation has a higher NDVI; (2) examine changes in the 

NDVI with burn treatment; and (3) analyze the relationships between NDVI and canopy 

cover measured using hemispherical photography (Alexander and others 2008). Buffered 

polygons were created from aerial photos to encompass each of 93 forest plots arrayed 

across three study sites, each with three treatments: fire-excluded, frequent burn (spring 

2003, 2004, 2006, and 2008), and infrequent burn (spring 2003, 2009). The polygons 

were matched with plot-scale locations to capture a larger area of similar vegetation. We 

used Landsat 5 Thematic Mapper summer (typically June) images obtained for each year 

from 2002 to 2010 to calculate NDVI. Plots were located on differing landscape positions 

and were classified as sub-mesic, intermediate, or sub-xeric based on vegetation. Analysis 

of variance (ANOVA) was used to test the main effects of treatment (nested within site) 

and landscape position on NDVI in each year. Regression analysis was used to test the 

strength of the relationship between NDVI measured in one year relative to another year. 

Regression was also used to examine the relationship between NDVI and canopy cover. 

As expected, prior to burning there was a close relationship between the NDVI in 2001 

and 2002 (R2

 = 0.66, p < 0.0001). In summer 2003, after both sites were burned the 

previous spring, the NDVI was lower (less green) on burned compared to fire-excluded 

sites (p = 0.0004). Comparing NDVI in 2003 with 2002, the R2

 for the relationships 

varied from R2 = 0.53 for control, R2 = 0.21 for less frequent, and R2 = 0.17 for frequent 

sites (after one burn had been conducted on both treatments in 2003). Differences in 

NDVI were greatest the first year after burning, despite repeated burning in subsequent 

years. By 2006, NDVI on less frequent burn sites was similar to that on fire-excluded 
218 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

sites; both had higher NDVI compared to the frequent burn sites, which by 2006 had 

been burned three times, including the previous spring. A second burn in 2009 on the less 

frequent burn sites reduced NDVI below that of the frequent sites, but NDVI rebounded 

the following year. 

We also examined the relationships between NDVI and canopy cover on a subset of 

sites (N = 33) from 2002 through 2007. In 2002, there was little variability in canopy 

cover or NDVI across these sites; although the relationship was significant, canopy cover 

explained little of the variability in NDVI (R2

 = 0.11; p = 0.03). In subsequent years, 

after burning the relationship between NDVI and canopy cover was strongly positive. 

For example, the first growing season after the first burn (2003), canopy cover explained 

50 percent of the variability in NDVI (p < 0.0001). In 2007, after three burns in the 

frequent sites and one burn in the less frequent sites, there was still a strong positive 

relationship between canopy cover and NDVI (R2 = 0.38; p < 0.0001), but the slope of 

the relationship was lower than in 2003. 

The intent of the prescribed burning in our study was to remove midstory stems of firesensitive species with fairly small changes to the overstory. Nonetheless, immediately 

after the first fire, following which we found the greatest stem mortality (Arthur, 

unpublished data), there were highly significant differences in NDVI among treatments, 

and a strong relationship between NDVI and canopy cover. As overstory canopy cover 

was replaced by understory resprouting (Arthur, unpublished data; Blankenship and 

Arthur 2006; Chiang and others 2005), increasing leaf area led to increasing NDVI such 

that by 2010 there were small but significant differences between the control and frequent 

burn sites, with the less frequent sites having NDVI similar to the controls. 

Future work on this project will examine additional stand characteristics (crown health, 

stem density, basal area) in relationship to NDVI and other spectral vegetation indices 

(SVIs), explore differences among landscape positions in burning effects on SVIs, and 

determine whether combinations of SVIs can be used to distinguish between canopy 

cover and understory sprouting response to burning. Prescribed fire used to create a range 

of habitats with more open canopies, such as oak woodlands and savannas, may lead to 

forest canopies that are more easily detected using this approach. Thus, we plan to expand 

our analysis to a landscape recently burned by wildfire which created a greater range of 

impacts to the forest canopy, and thus may provide a further test of this approach.

LITERATURE CITED

Alexander, H.D.; Arthur, M.A.; Loftis, D.L.; Green, S.R. 2008. Survival and growth of 

upland oak and co-occurring competitor seedlings following single and repeated 

prescribed fires. Forest Ecology and Management. 256: 1021-1030.

Blankenship, B.A.; Arthur, M.A. 2006. Stand structure over nine years in burned and 

fire-excluded oak stands on the Cumberland Plateau, Kentucky. Forest Ecology 

and Management. 225: 134-145.

Chiang, J.; Arthur, M.A.; Blankenship, B.A. 2005. The effect of prescribed fire on 

gap fraction in an oak forest on the Cumberland Plateau. Journal of the Torrey 

Botanical Society. 132: 432-441.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 219

FireStemII – A 2-D HEAT TRANSFER MODEL FOR SIMULATION 

OF STEM DAMAGE IN PRESCRIBED FIRES

Efthalia K. Chatziefstratiou, Gil Bohrer, Anthony S. Bova, and Matthew B. Dickinson 

Graduate Research Associate (EKC) and Assistant Professor (GB), Department of Civil 

and Environmental Engineering and Geodetic Science, 416 Bolz Hall, The Ohio State University, 

Columbus, OH, 43210; Physical Scientist (ASB); Ecologist (MBD). EKC is corresponding author: 

to contact, call 614-292-9582 or email at chatziefstratiou.1@osu.edu.

Abstract.— In this work, we present FireStemII, a software tool that allows fire 

managers to predict tree mortality and stem injury resulting from a prescribed forest fire. 

FireStemII is a revision of FireStem (Jones and others 2004, 2006). When prescribing 

a fire, it is important to have a tool that predicts tree mortality and the extent of stem 

injury given the fuel conditions, fire behavior, and height aboveground along the 

stem. FireStemII is a physically-based thermodynamic 2-D model of tree stem injury 

as a function of external heat forcing. It provides increased capability for predicting 

fire-induced mortality and damage before a fire occurs. By directly simulating tissue 

temperatures, moisture loss, and charring, it determines the depth and circumferential 

extent of damage caused by incident heat flux around a stem at a given height. These 

data are further integrated to provide a depth of necrosis around the stem and an index of 

vascular cambium viability.

Introduction

FireStemII simulates the influence of fire as a dynamic 

and spatially heterogeneous heat flux boundary 

condition around the circumference of a virtual slice 

of a stem. Several other numerical models for heat 

transfer in tree stems subjected to fire conditions have 

used temperature boundary conditions (Costa and 

others 1991) and were typically 1-D models (Rego and 

Rigolot 1990), not accounting for differential heating 

rates and injury responses around stems. FireStem 

was the first, to our knowledge, to include a heat flux 

boundary condition (Jones and others 2004). The 

realism and dynamics of FireStemII will allow it to 

be linked to a coupled fluid dynamics and combustion 

(fire) model in future work. Time series of heat flux 

will be simulated around stems at different heights 

aboveground and at different locations throughout a 

burn area (Fig. 1). For example, as the fire-line passes 

a tree, turbulence on the lee side of the stem leads to 

Figure 1.—FireStemII as a 2-D model of tree stem 

injury takes into consideration the uneven heating in the 

circumferential direction in case of a fire.

increased heating and injury at the back, while the 

sides and front of the stem are less affected (Gutsell 

and Johnson 1996).
220 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Stem Heating Model

The model is based on a two-dimensional heat transfer 

formulation:





 





∂

∂

∂

∂  +



 





∂

∂

∂

∂ = ∂∂

θθ

ρ T

r

k

rr

T rk

rrt

i 1 1

where r is radius (cm), k is conductivity (W/(m•K)), 

ρ is wood density (g/cm3

), i is specific internal energy 

(J), T is temperature (K), and θ is angle (radians).

Stem Simulation

Stems are simulated as circular slices out of infinitely 

long cylinders (Jones and others 2004). The required 

inputs to the model include geometric information 

(stem diameter, outer and inner bark thickness), and 

physical properties (thermal conductivity, density, 

specific heat, and moisture content in inner bark, 

outer bark, and wood). Stems are divided into radial 

wedges (we used 16 wedges), and each wedge was 

divided into nodes in the radial direction. The distance 

between nodes is flexible and was set here to 1 mm. 

The new feature of FireStemII in comparison to 

Jones and others (2004) is that the stem is modeled 

as two dimensional. In addition, the numerical solver 

was improved with a more robust Crank-Nicholson 

approach, and two new routines for desiccation and 

bark charring were used.

Physical Phenomena

Desiccation

The change in water mass at each nodal point is 

calculated at each time step. The relation for water loss 

was taken from Morvan and Dupuy (2001):





 





−⋅⋅= ∂

∂

RT

E M

T

k W

t

w w w

m ρ exp

where Wm is a multiplier that allows the water loss rate 

to be adjusted, M is moisture (%), T is temperature 

(K), ρ is wood density (g/cm3

), the coefficient kw

(6.05E5 K0.5/s) and the exponential factor Ew/R(5956 

K) are taken from Morvan and Dupuy 2001.

Bark charring

Pyrolysis is modeled in a manner analogous to water 

loss with the exception that in each time step, charring 

can occur only one node away from a previously 

charred node. The rate equation is based on Ragland 

and Aerts (1991):

( ) 















−⋅−⋅⋅⋅= ∂

∂

RT

E

cAP

t

p p

pm f ρ exp1

where Pm is the pyrolysis multiplier, cf is the 

density fraction, the coefficient Ap

 (7E7 s-1) and the 

exponential factor Ep /R(15610 K) are also taken from 

Ragland and Aerts (1991). The combustion of charred 

material (glowing combustion) is not modeled.

Tissue injury

The thermally caused mortality in population of cells 

is described by a rate equation, where the rate of 

decline in tissue viability is proportional to current 

viability (Dickinson and Johnson 2001; Dickinson and 

others 2004):

tV )( dt

dV −= κ

where V is viability value between 1 (survival) and 0 

(cell death), t is time (s), and κ is a species-specific, 

temperature-dependent rate parameter. Cellular 

necrosis is assumed if V is reduced below 0.5. 

EXPERIMENTAL METHODS

Controlled laboratory stem heating experiments were 

conducted on eight regional species: red maple (Acer 

rubrum L.), sugar maple (Acer saccharum Marsh.), 

mockernut hickory (Carya tomentosa [Poir.] Nutt.), 

yellow-poplar (Liriodendron tulipifera L.), blackgum 

(Nyssa sylvatica Marsh.), eastern white pine (Pinus 

strobus L.), chestnut oak (Quercus prinus L.), and 

northern red oak (Quercus rubra L.) in order to 

validate FireStemII. The stem sections were fitted with 

three thermocouples to monitor temperatures at bark 

surface, beneath the bark surface, and at the cambium. 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 221

Total mass loss with heating was also determined by 

measuring pre- and posttreatment stem mass. Finally, 

depth of necrosis into the sapwood following stem 

heating was determined by staining stem sections with 

tetrazolium chloride (TTC). 

RESULTS AND DISCUSSION

The laboratory stem-heating experiments of 53 tree 

sections of tree species mentioned above were also 

simulated with FireStemII. The results from the 

physical experiments are compared with the results 

from FireStemII simulations of the same cases. 

(Figs. 2 and 3). 

AKNOWLEDGEMENTS

The authors thank Joshua Levi Jones and Ravishankar 

Subramanian for collaboration and developments 

of earlier versions of the model. The study was 

funded by NASA-NESSF-Earth Sciences Fellowship 

#NNX09AO26 to Anthony Bova and Gil Bohrer, and 

through the U.S. Forest Service, Northern Research 

Station Agreement 09-CR-11242302-033. Bret Butler, 

Dan Jimenez, and Joe O’Brien provided useful 

feedback on an earlier draft of the manuscript. 

LITERATURE CITED

Costa, J.J.; Oliveira, L.A.; Viegas, D.X.; Neto, L.P. 

1991. On the temperature distribution inside a 

tree under fire conditions. International Journal 

of Wildland Fire. 1: 87-96. 

Dickinson, M.B.; Johnson, E.A. 2001. Fire effects on 

trees. In: Johnson, E.A.; Miyanishi, K., eds. Forest 

fires: behavior and ecological effects. New York, 

NY: Academic Press: 477-525. 

Dickinson, M.B.; Jolliff, J.; Bova, A.S. 2004. 

Vascular cambium necrosis in forest fires: 

using hyperbolic temperature regimes to 

estimate parameters of a tissue-response model. 

Australian Journal of Botany. 52: 757-763. 

Figure 2.—Necrotic depth of 53 tree sections from eight 

different species. Heating experiments in the lab are 

compared with the necrotic depth estimated with FireStemII. 

Figure 3.—Temperature variation through time just beneath 

bark surface in a chestnut oak tree section (stem diameter 

= 12.7 cm) in one lab experiment and from FireStemII 

simulation of the same case.

Gutsell, S.L.; Johnson, E.A. 1996. How fire scars 

are formed: coupling a disturbance process to 

its ecological effect. Canadian Journal of Forest 

Research. 26: 166-174.

Jones, J.L.; Webb, B.W.; Butler, B.W.; Dickinson, 

M.D.; Jimenez, D.; Reardon, J.; Bova, A.S. 2006. 

Prediction and measurement of thermallyinduced cambial tissue necrosis in tree stems.

International Journal of Wildland Fire. 15: 3-17.

0

5

10

15

20

25

30

0 5 10 15 20 25

Firestem II Depth of Necrosis (mm)

Experimental depth of Necrosis (mm)

y = 1.089x

R2 = 0.8121
222 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Jones, J.L.; Webb, B.W.; Jimenez, D.; Reardon, J.; 

Butler, B. 2004 Development of an advanced 

one-dimensional stem heating model for 

application in surface fires. Canadian Journal of 

Forest Research. 34: 20-30. 

Morvan, D.; Dupuy; J.L. 2001. Modeling of fire 

spread through a forest fuel bed using a 

multiphase formulation. Combustion and Flame. 

127: 1981-1994. 

Ragland, K.W.; Aerts, D.J. 1991. Properties of wood 

for combustion analysis. Biresource Technology. 

37: 161-168.

Rego, F.; Rigolot, E. 1990. Heat transfer through 

bark - a simple predictive model. In: 

Goldammer, J.G.; Jenkins, M.J., eds. The Hague, 

Netherlands: SPB Academic Publishing: 157-162.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 223

EFFECTS OF TWO PRESCRIBED FIRES ON RED MAPLE REGENERATION

ACROSS FOUR LEVELS OF CANOPY COVER 

IN NORTHERN LOWER MICHIGAN

William W. DeBord, David S. Buckley, Terry L. Sharik, 

Jason P. Hartman, and Jason G. Henning

Graduate Research Assistant (WWD) and Associate Professor (DSB and JGH), 

Department of Forestry, Wildlife and Fisheries, 274 Ellington Plant Sciences Building, 

University of Tennessee, Knoxville, TN 37996-4563; Professor (TLS), 

Department of Wildland Resources, Utah State University; Unit Manager (JPH), 

Michigan Department of Natural Resources and Environment. 

DSB is corresponding author: to contact, call 865-974-7978 or email at dbuckley@utk.edu.

Introduction

Mixed oak forests persist as a predominant forest 

type in eastern U.S. forests, but very little oak 

recruitment into the overstory has occurred since 

the implementation of fire suppression in the early 

1900s (Abrams 1992). Advanced oak regeneration 

on high quality and some intermediate quality sites 

is being replaced in the midstory by more mesic, 

shade tolerant species (Abrams and Nowacki 1992). A 

large proportion of the total increase in the density of 

competitors can often be attributed to an influx of red 

maple (Acer rubrum L.) (Abrams 1998, 2005). Current 

thinking is that reintroduction of representative fire 

regimes into eastern oak systems may help promote 

oak recruitment and impede the development of red 

maple competition. It has been suggested that oak 

seedlings and saplings are better adapted to fire than 

those of red maple and other competitors due to 

greater allocation of resources to roots and several 

other adaptations (Brose and Van Lear 1998). As a 

result, it follows that multiple fires should place red 

maple and other competitors at an ever-increasing 

disadvantage relative to oak species. 

As a component of a larger, long-term oak 

regeneration project established in 1990, the objectives 

of this study were to determine the additive effects of 

two spring prescribed fires on red maple regeneration 

across four levels of canopy cover, and test the 

hypothesis that red maple densities in medium 

(25 cm tall – 2.54 cm diameter at breast height 

[d.b.h.]) and large (>2.54 cm d.b.h.) size classes would 

be reduced to a greater degree following the second 

fire than following the first.

METHODS

Second-growth natural oak stands on state forest 

land in northern Lower Michigan were selected as 

study sites. The sites are located within the Grayling 

Outwash Plain of the Highplains District of the 

northern Lower Peninsula (Albert 1995). All stands 

occurred on sandy, mixed, frigid, Alfic Haplorthods 

developed in pitted outwash. Soils in all stands had 

comparable physical and chemical properties (Kim 

and others 1996). All sites were moderately productive 

with slopes ≤5 percent. Site index for northern red oak 

(Quercus rubra L.) was 17.8 m at 50 years (Carmean 

1978). Based on counts of annual growth rings on 

stumps following overstory treatment implementation 

in 1991, the stands studied were 106-118 years old in 

2009. 

Each of three 1.74 ha replicate oak blocks was 

subdivided into four overstory plots measuring 

66 × 66 m (0.44 ha). Each overstory plot was 

randomly assigned one of four canopy cover 

treatments: clearcut (CC), 25 percent residual canopy 

cover (25 percent), 75 percent residual canopy cover 

(75 percent), or uncut control (UC). All stands were 
224 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

cut between fall 1990 and early spring 1991. Four 

understory treatment subplots measuring 15 × 15 

m (0.02 ha each) were arranged in a square at the 

center of each canopy treatment plot in 1991, and the 

understory treatments were maintained intermittently 

through 1996. 

All stands were burned on May 15, 2002 and burned 

again on May 16, 2008. The goal in both years was 

to achieve strip-head fires with 0.9 m flame lengths in 

order to top kill all hardwood seedlings on all sites. 

Maximum fire temperatures were documented with 

temperature indicating paints (B.J. Wolfe Enterprises 

Inc., Agoura Hills, CA) painted on the bottom surface 

of horizontally oriented ceramic tiles. One ceramic 

tile was mounted on a steel stake 0.6 m above the soil 

surface in the center of each of the four understory 

plots within each overstory treatment plot. 

Natural regeneration was measured in 2001, 2003, 

2006, and 2009 at four sampling points within each 

understory plot near the end of the growing season 

in late July/early August. Genets of woody stems 

were tallied by species into three size classes: 1) 

Small (stems <25 cm height); 2) Medium (stems 25 

cm height – 2.54 cm diameter); and 3) Large (stems 

2.54 cm diameter – 10 cm diameter). Small size class 

stems were measured within 1 m2

 quadrats. Medium 

and large size class stems were measured within 2 

and 4 m diameter circular plots, respectively. Smaller 

sampling plots were nested within larger plots, and all 

three plots were centered on each of the four sampling 

points within each of the understory plots. 

Paired t-tests were used to evaluate differences 

between the differences in pre- and postburn seedling 

densities associated with each fire using SAS/STAT®

software (version 9.2, SAS Institute Inc., Cary, NC). 

Hypothesis tests were performed with ∝ = .05.

RESULTS AND DISCUSSION

Maximum fire temperatures ranged from 40 to 

100 °C at 0.6 m above the soil surface. Temperatures 

were comparable in both years, and flame lengths 

were typically 0.3 m or less. In the case of medium 

and large red maple stems, in most of the overstory 

treatments there were differences between the 

differences in maple density before and after Fire 1 

and the differences in density before and after Fire 2 

(Table 1). Differences associated with the second fire 

were far smaller in most cases, however, than those 

associated with the first fire (Table 1). Consequently, 

the hypothesis that red maple stems in the two larger 

size classes would be reduced more by the second fire 

than by the first was not supported. 

Many of the larger surviving red maple stems were 

stump sprouts that emerged from thinned midstory 

saplings following implementation of canopy 

treatments in 1991. These sprouts were able to develop 

over 11 growing seasons prior to the first prescribed 

fire. Densities may have been reduced to a greater 

degree following the first fire due to high mortality 

among stressed, ill-formed, or diseased stems, leaving 

only the most robust, well-established stems which 

then had six growing seasons to recover before the 

second fire. Reducing these robust stems may require 

continued repeated burning.

Prescribed fires implemented more frequently than 

in this study may help to reduce the density of large 

red maple stems that are able to survive and recover 

over longer time periods between fires. More frequent 

burns, however, will also have effects on oak stems. 

Overall, the two prescribed fires had a cumulative 

effect, reducing red maple densities by 46-74 percent 

in the medium size class and by 53-87 percent in 

the large size class, which may improve the future 

competitive position of oak seedlings and saplings. 

ACKNOWLEDGMENTs

This research was funded by the University of 

Tennessee Department of Forestry, Wildlife and 

Fisheries, and the Michigan Department of Natural 

Resources (DNR). Special thanks to several Michigan 

DNR personnel and to Chris Miller, John Johnson, and 

Stephen Grayson for their help in the field.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 225

Medium Size Class

Canopy 2001 2003 Fire 1 2006 2009 Fire 2

Treatment1 Density Density Difference P-value2 Density Density Difference

Stems/ha Stems/ha Stems/ha Stems/ha Stems/ha Stems/ha

CC 9416.68 4244.14 –5172.54 0.0605 4111.51 2453.64 –1657.87

25% 23475.37 13262.92 –10212.45 0.0094 14920.79 10941.91 –3978.88

75% 22480.65 12599.78 –9880.88 0.0057 17772.32 12135.57 –636.74

UC 16114.45 6432.52 –9681.93 0.0063 8289.33 4708.34 –3580.99

Large Size Class

Canopy 2001 2003 Fire 1 2006 2009 Fire 2

Treatment Density Density Difference P-value Density Density Difference

Stems/ha Stems/ha Stems/ha Stems/ha Stems/ha Stems/ha

CC 2287.85 1177.08 –1110.77 0.0082 1110.77 1077.61 –33.16

25% 1823.65 629.99 –1193.66 0.0035 613.41 464.20 –149.21

75% 646.57 132.63 –513.94 0.0388 198.94 82.89 –116.05

UC 116.05 16.58 –99.47 0.3400 66.31 16.58 –49.74

1

CC = clearcut; 25 percent = 25 percent canopy cover; 75 percent = 75 percent canopy cover; and UC = uncut controls.

2

Bold P-values indicate statistically significant differences between differences in red maple density before and after Fire 1 and differences in 

red maple density before and after Fire 2 suggested by paired t-tests with alpha = 0.05. 

Table 1.—Red maple densities by size class, year, and canopy treatment, differences between pre- and 

postfire densities associated with each prescribed fire, and results for paired t-tests conducted within 

canopy treatments to compare differences in red maple density associated with each fire.

LITERATURE CITED

Abrams, M.D. 1992. Fire and the development of 

oak forests. BioScience. 42: 346-353.

Abrams, M.D. 1998. The red maple paradox. 

BioScience. 48: 355-364.

Abrams, M.D. 2005. Prescribing fire in eastern oak 

forests: Is time running out? Northern Journal of 

Applied Forestry. 22: 190-196. 

Abrams, M.D.; Nowacki, G.J. 1992. Historical 

variation in fire, oak recruitment, and postlogging accelerated succession in central 

Pennsylvania. Bulletin of the Torrey Botanical 

Club. 119: 19-28.

Albert, D.A. 1995. Regional landscape ecosystems 

of Michigan, Wisconsin, and Minnesota: a 

working map and classification. Gen. Tech. 

Rep. NC-178. St. Paul, MN: U.S. Department of 

Agriculture, Forest Service, North Central Forest 

Experimental Station. 250 p.

Brose, P.H.; Van Lear, D.H. 1998. Responses of 

hardwood advance regeneration to seasonal 

prescribed fires in oak-dominated shelterwood 

stands. Canadian Journal of Forest Research. 

28: 331-339.

Carmean, W.H. 1978. Site index curves for northern 

hardwoods in northern Wisconsin and Upper 

Michigan. Res. Pap. NC-160. St. Paul, MN: U.S. 

Department of Agriculture, Forest Service, North 

Central Forest Experimental Station. 16 p.

Kim, C.; Sharik, T.L.; Jurgensen, M.F.; Dickson, 

R.E.; Buckley, D.S. 1996. Effects of nitrogen 

availability on northern red oak seedling 

growth in oak and pine stands in northern 

lower Michigan. Canadian Journal of Forest 

Research. 26: 1103-1111.

The content of this paper reflects the views of the 

author(s), who are responsible for the facts and accuracy 

of the information presented herein.
226 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

TALL LARKSPUR BENEFITS FROM FIRE IN CHINKAPIN OAK WOODLANDS

Dan Drees

Fire Ecologist, National Park Service, Ozark National Scenic Riverways, Van Buren, MO 63965. 

To contact, call 573-323-8234 ext. 26 or email at daniel_drees@nps.gov.

ABSTRACT

Tall larkspur (Delphinium exaltatum) is 

a globally rare wildflower (NatureServe 

2010). In Missouri, tall larkspur is strongly 

associated with chinkapin oak (Quercus 

muehlenbergii Engelm.) dominated 

woodlands (85 percent of sites) (Mullarkey 

and others 2008). It is an important oak 

woodland indicator species that requires 

strong filtered sunlight to maintain viable 

populations. In the absence of fire, the 

woodlands that tall larkspur prefers are 

subject to succession towards forest. 

The subsequent increase in shade greatly 

reduces tall larkspur populations (Fig. 1). 

According to www.natureserve.org, “A 

primary threat to tall larkspur is loss of 

habitat due to succession of vegetation 

in the absence of a natural fire regime. 

Encroachment of trees and shrubs (e.g., eastern redcedar [Juniperus virginiana L.]) into 

occupied habitat has likely resulted in the loss of many individuals and populations over 

time.” Historically, fire kept woody plants from becoming too dense in tall larkspur’s 

preferred habitat. This attractive wildflower may persist naturally without fire for decades 

on some sunny, steep slopes and the sunny banks of small high-gradient streams. This is 

especially true if windstorms, ice storms, or selective timber harvesting have thinned the 

tree canopy. However, only fire will prevent leaf litter accumulation from suppressing tall 

larkspur seedling germination over most of its preferred habitat. 

Tall larkspur population inventories at Ozark National Scenic Riverways (ONSR) 

between 1984 and 2008 documented dramatic population declines at unburned sites. The 

largest population (650 plants) declined by 64 percent in total number and by 94 percent 

in number of reproductive plants. In 2009, the Ozark Highlands fire ecology crew of the 

National Park Service discovered a new population of 2,481 tall larkspur plants in a fire 

managed woodland at ONSR. It is the largest reported natural population of tall larkspur 

in a prescribed fire management unit anywhere. 

In 2010, ONSR embarked on an ongoing project with permanent plots to study the fire 

ecology of tall larkspur in the Current River watershed where 15 of 17 populations in 

Missouri are located. We would like to collaborate with managers of natural tall larkspur 

populations throughout the plant’s range. 

Figure 1.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 227

LITERATURE CITED

Flora of North America Editorial Committee. 1997. Flora of North America north of 

Mexico. Volume 3: Magnoliophyta: Magnoliidae and Hamamelidae. New York, 

NY: Oxford University Press. 616 p.

Mullarkey, A.; Farrington, S.; Drees, D. 2008. Habitat, population status and 

management of tall larkspur (Delphinium exaltatum) in Missouri. [Poster]. In: 

Missouri natural resources conference; 2008 Jan 30 - Feb 1; Camdenton, MO.

NatureServe. 2010. NatureServe explorer: an online encyclopedia of life. [Web 

application]. Version 7.1. NatureServe: Arlington, Virginia. Available at http://www.

natureserve.org/explorer. (Accessed 2011 May 12).

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
228 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

LOCAL COLLARED LIZARDS NEEDED LANDSCAPE-SCALE FIRE

Dan Drees

Fire Ecologist, National Park Service, Ozark National Scenic Riverways, Van Buren, MO 63965. 

To contact, call 573-323-8234 ext. 26 or email at daniel_drees@nps.gov.

ABSTRACT

Evolutionary biologist Dr. Alan Templeton used 15 years of field research on eastern 

collared lizards to advocate for landscaped-scale prescribed burn units beginning in 1994. 

Another 18 years of field research by Dr. Templeton and his colleagues demonstrated 

that landscape-scale burns are necessary for a variety of reasons. In addition to restoring 

glade habitat for collared lizards, the large burns were necessary to open surrounding 

woodlands as travel corridors (Templeton and others 2007). Burning the surrounding 

woodlands permitted additional glades to be colonized and facilitated genetic dispersal.

Dr. Templeton started in 1979 with a search of the Stegall Mountain vicinity (Current 

River watershed in Missouri) to determine if historic populations of the collared lizard 

still existed. No collared lizards were observed in the initial surveys. The areas numerous 

igneous and dolomite glades had become too overgrown in trees, especially eastern 

redcedar. The historic populations of collared lizards probably died out due to shading of 

their open glade habitat. 

In 1982, cedar removal and small prescribed fires were initiated to reopen the best 

remaining glades on nearby Stegall Mountain. In 1984, collared lizards were captured 

from several healthy populations 40 to 80 miles away and released on Stegall Mountain. 

After a few years, Dr. Templeton realized that collared lizards were not moving to nearby 

glades that were separated by thin bands of dense woody vegetation, some only 50 meters 

wide. 

Dr. Templeton, as part of a Biodiversity Task Force commissioned by the Missouri 

Department of Conservation, suggested burning several hundred acres of glades and 

woodlands at once. At the time, this was a radical concept in Missouri. In 1994, the 

first landscape-scale burn was completed on Stegall Mountain. The collared lizards 

immediately responded by colonizing several nearby glades. 

One of Dr. Templeton’s students found that grasshoppers were the primary food of local 

collared lizards (Östman and others 2007). Another student discovered that there was a 

650 percent increase in grasshoppers in the prescribed burn units (Jon Hallemeier and A. 

Templeton, unpublished results). Grasshoppers and other ground dwelling insects are also 

the primary food for turkey hatchlings and many species of grassland birds. 

Indeed, the National Wild Turkey Federation (NWTF) has recognized for a long time that 

glades and their surrounding woodlands should be properly managed with prescribed fire 

to create the optimal mix of nesting cover, brood rearing habitat, and acorn production. 

Locally, the NWTF has been an important ally in promoting the restoration of firedependent habitats that support a diversity of rare plants and animals in addition to 

important game species.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 229

Dr. Templeton’s dream was to see at least 2,000 contiguous acres in prescribed 

fire management. In 2009, the National Park Service, the Missouri Department of 

Conservation, and The Nature Conservancy joined forces to complete over 5,000 

contiguous acres of prescribed burns in the Stegall Mountain area in just one season. 

Collared lizards have now colonized all of the suitable glades within these adjoining burn 

units. Most importantly, the collared lizards are indicators that landscape-scale prescribed 

fire has restored, stabilized, or increased populations of many other fire-dependent 

conservative species.

LITERATURE CITED

Östman, O.; Griffin, N.W.; Strasburg, J.L.; Brisson, J.A.; Templeton, A.R.; Knight, T.M.; 

Chase, J.M. 2007. Habitat area affects arthropod communities directly and 

indirectly through top predators. Ecography. 30: 359-366.

Templeton, A.R.; Neuwald, J.L.; Brazeal, H.; Robertson, R.J. 2007. Restoring 

demographic processes in translocated populations: the case of collared lizards 

in the Missouri Ozarks using prescribed forest fires. Israel Journal of Ecology and 

Evolution. 53: 179-196.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
230 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

EFFECTS OF WILDFIRES AND LIMING OF PINE-OAK-HEATH 

COMMUNITIES IN THE LINVILLE GORGE WILDERNESS, 

WESTERN NORTH CAROLINA

Katherine J. Elliott, James M. Vose, Jennifer D. Knoepp, and William Jackson

Research Ecologist (KJE), Research Ecologist and Project Leader (JMV), 

and Research Soil Scientist (JDK), U.S. Forest Service, Southern Research Station, 

Coweeta Hydrologic Laboratory, Otto, NC 28763; Air Quality Specialist (WJ). 

KJE is corresponding author: to contact, call 828-524-2128 or email at kelliott@fs.fed.us.

Abstract

Linville Gorge Wilderness (LGW) is a Class I area in 

the southern Appalachian Mountains, western North 

Carolina. Over the last 150 years, LGW has been 

subject to several wildfires, varying in intensity and 

extent (Newell and Peet 1995). In November 2000, 

a wildfire burned 4000 ha in the wilderness; the fire 

ranged in severity across the northern portion of the 

wilderness from low severity in coves to high severity 

along ridges and bluffs (Reilly and others 2006). In 

May 2007, the Pinnacle wildfire burned ca. 2000 ha in 

the southern portion of the wilderness. A large portion 

of the Pinnacle fire overlapped the area previously 

burned in 2000, resulting in much of the central 

section of LGW being burned twice in less than 7 

years. In addition, dolomitic lime was aerially applied 

at a rate of 1120 kg ha-1 on the most severely burned 

area. We hypothesized that liming the most severely 

burned area would accelerate the restoration of 

acidic, nutrient depleted soils by adding basic cations, 

balancing soil pH, reducing soil and soil solution Al, 

and subsequently increase ecosystem productivity. 

We sampled vegetation (composition, biomass, and 

foliar nutrients) and soil nutrients in five treatment 

areas in LGW over a 2-year period following the most 

recent wildfire. The treatment areas were: severely 

burned twice (2000 and 2007) plus dolomitic lime 

application (2xSBL); moderately burned twice plus 

lime (2xMBL); severely burned twice, no lime (2xSB); 

moderately burned once (2000), no lime (1xMB); and 

an unburned and unlimed reference area (REF). 

All wildfire burned sites experienced overstory 

mortality (>300 stems ha-1). There were no live 

overstory trees on 2xSBL, and 2xSB had a larger 

number of dead trees than all other sites. The large 

number of dead pines on all sites, including the 

reference, was due in large part to a southern pine 

beetle (Dendroctonus frontalis Zimm.) outbreak in 

1999-2001. The three areas impacted by the recent 

wildfire had little to no live pine in the overstory. 

Overstory biomass was lower on the severely burned 

areas (2xSBL and 2xSB) than the other treatments, 

with no significant change between 2008 and 2009 

(Fig. 1). By 2009, understory density was higher 

on 2xSBL than the other treatments (Fig. 2a), with 

higher numbers of tree species (Fig. 2b). We found no 

differences in shrub density among burned treatments, 

and only 2xSB had higher shrub density than REF 

(Fig. 2c). As expected, ericaceous (heath) species 

sprouted after fire, and their density increased between 

2008 and 2009 for all recently burned treatments.

We found no differences in foliar nitrogen (N) 

concentration among treatments for either evergreen or 

deciduous species (Table 1). Evergreen foliar calcium 

(Ca) was greater on 2xMBL and REF than the severely 

burned sites (2xSBL and 2xSB); whereas deciduous 

foliar Ca and phosphorus (P) were greater on 2xMBL 

than 2xSBL, 1xMB and REF (Table 1). 

With few exceptions, we found significant date, 

treatment, date x treatment interaction effects for 

soil exchangeable cations for both shallow (0-10 cm 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 231

Figure 1.—Overstory (≥ 5.0 cm diameter at breast height [d.b.h.]) biomass with standard error bars of live and standing 

dead trees for the five treatment areas the first (2008) and second (2009) growing seasons after wildfire in Linville Gorge 

Wilderness, western North Carolina. The treatments were severely burned twice (2000 & 2007) plus dolomitic lime application 

(2xSBL); moderately burned twice with lime (2xMBL); severely burned twice, no lime (2xSB); moderately burned once (2002), 

no lime (1xMB); and an unburned and unlimed reference area (REF). Bars with different letters denote significant (α≤0.05) 

differences among treatments within a year.

depth) and deep (10-30 cm depth) soils (Table 2). Soil 

exchangeable Ca2+ had a significant treatment effect, 

but no date or date x treatment interaction effects 

(Table 2). Soil Ca2+ was greater on 2xMBL and 2xSBL 

than 2xSB, 1xMB, and REF for shallow soil, and 

greater on 2xMBL than 2xSBL for deep soil (Table 2). 

Soil extractable aluminum (Al3+

) was less on 2xSBL 

than 2xSB, 1xMB, and REF, which resulted in higher 

Ca/Al ratios on 2xSBL and 2xMBL than 2xSB, 1xMB, 

and REF. 

Wildfires are landscape-scale disturbances and have 

the potential to significantly impact biogeochemical 

processes by altering pools and fluxes of carbon and 

nutrients (Debano and others 1998, Knoepp and 

others 2005). The magnitude and duration of these 

responses depends on the interactions among preburn 

conditions, burn severity, postfire precipitation regime, 

topography, soil characteristics, and vegetative 

recovery rate (Robichaud 2005). We expected that the 

effects of the most recent wildfire and lime application 

would be observed over a 2-year period, possibly 

longer, as Ca and Mg leach into the soil where it can 

be taken up by the recovering vegetation (Elliott and 

others 2002, Knoepp and Swank 1997). In our study, 

the moderately burned site with lime application had 

the highest soil and foliar Ca suggesting that the lime 

application was subsequently taken up by vegetation. 
232 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

In contrast, the severely burned site with lime had 

greater soil Ca but lower foliar Ca than the moderately 

burned site even though both sites received lime 

application. Soil Al was lowest on 2xSBL, suggesting 

that the lime addition did improve the soil Ca/Al ratio 

since it was higher on this site than the others. Al3+

increased and Ca/Al ratio decreased over time for both 

the shallow and deep soil depths (Table 2). Thus, the 

lime addition did improve the soil Ca/Al ratio, but the 

response was transitory. Soil Ca/Al ratios remain well 

below the toxicity threshold <1.0 (Cronon and Grigal 

1995) on all treatment areas in LGW.

Figure 2.—Understory (shrubs and trees <5.0 cm d.b.h.) density with standard error bars: a) all woody species, b) trees only, 

and c )shrubs only for the five treatment areas the first (2008) and second (2009) growing seasons after wildfire in Linville 

Gorge Wilderness, western North Carolina. Treatment labels are the same as in Figure 1. Bars with different letters denote 

significant (α≤0.05) differences among treatments within a year. Asterisk denotes significant (α≤0.05) difference between years 

within a treatment. 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 233

2xSBL 2xMBL 2xSB 1xMB REF

N (percent)

Evergreen 0.779 (0.032) 0.961 (0.021) 0.877 (0.032) 0.961 (0.064) 0.923 (0.052)

Deciduous 1.696 (0.067) 1.775 (0.132) 1.553 (0.059) 1.639 (0.057) 1.712 (0.042)

Ca (μg g-1)

Evergreen 6687 b (373) 10214 a (1001) 7180 b (313) 8878 ab (646) 10163 a (506)

Deciduous 4927 b (470) 6697 a (158) 5503 ab (560) 5164 b (510) 5014 b (556)

P (μg g-1)

Evergreen 736 (33) 780 (18) 707 (28) 670 (48) 739 (68)

Deciduous 1506 ab (36) 1612 a (53) 1445 ab (42) 1249 c (29) 1357 bc (24)

Al (μg g-1)

Evergreen 52 (6) 59 (5) 47 (4) 169 (65) 193 (92)

Deciduous 91 b (30) 104 ab (21) 138 ab (9) 166 a (28) 84 b (11)

Notes: Values followed by different letters are significantly different (p < 0.05) among treatments (SAS 2002-2003). 

Table 1.—Nutrient concentrations (with standard errors in parenthesis) of evergreen and deciduous leaf 

tissue for the five treatment areas: severely burned twice (2002 and 2007) plus dolomitic lime application 

(2xSBL); moderately burned twice plus lime (2xMBL); severely burned twice, no lime (2xSB); moderately 

burned once (2002), no lime (1xMB); and an unburned and unlimed reference area (REF).

2xSBL 2xMBL 2xSB 1xMB REF

0-10 cm soil depth

Nitrogen 0.107 b (0.021) 0.164 a (0.011) 0.143 ab (0.012) 0.145 ab (0.005) 0.139 ab (0.005)

NO3

–N 0.0009 (0.0004) 0.0003 (0.0003) ND† ND ND

NH4+-N 0.118 (0.021) 0.105 (0.022) 0.070 (0.005) 0.104 (0.011) 0.072 (0.005)

HPO4

2- 0.236 ab (0.009) 0.250 a (0.015) 0.195 b (0.008) 0.241 ab (0.014) 0.251 a (0.010)

Ca2+ 7.322 ab (0.502) 9.616 a (1.662) 1.854 c (0.363) 4.009 b (0.630) 0.626 c (0.059)

Al3+ 76.36 c (6.234) 167.55 a (8.232) 124.00 b (6.404) 110.09 b (4.752) 109.40 b (7.700)

Ca/Al 0.102 a (0.006) 0.072 ab (0.017) 0.015 c (0.003) 0.037 bc (0.006) 0.006 c (0.001)

10-30 cm soil depth

Nitrogen 0.046 b (0.009) 0.070 a (0.004) 0.078 a (0.006) 0.062 ab (0.003) 0.060 ab (0.003)

NO3–N ND ND ND ND ND

NH4+-N 0.040 b (0.005) 0.044 b (0.003) 0.052 a (0.003) 0.053 a (0.003) 0.038 b (0.002)

HPO4

2- 0.111 b (0.013) 0.142 ab (0.005) 0.143ab (0.008) 0.136 ab (0.009) 0.162 a (0.014)

Ca2+ 0.956 b (0.038) 1.519 a (0.251) 0.574 bc (0.146) 0.606 bc (0.063) 0.218 c (0.015)

Al3+ 57.83 c (4.982) 116.57 a (4.868) 87.55 b (6.530) 76.42 bc (3.719) 81.11 b (2.747)

Ca/Al 0.018 a (0.001) 0.016 a (0.003) 0.006 bc (0.001) 0.009 b (0.001) 0.003 c (0.0002)

†

ND = samples below the detection limits of our methods. Values within a soil depth followed by different letters are significantly different (p < 

0.05) among sites (SAS 2002-2003). Values were averaged across time; and then, mean values and standard errors were based on the five 

plots per treatment area (n = 5). 

Table 2.—Mean soil chemistry (with standard errors in parenthesis) for the five treatment areas in the 

Linville Gorge Wilderness, western North Carolina, USA. Treatment labels are the same as in Table 1. 

All values are in cmolc kg-1 except for Ca/Al molar ratio.
234 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

LITERATURE CITED

Cronon, C.S.; Grigal, D.F. 1995. Use of calcium/

aluminum ratios as indicators of stress in forest 

ecosystems. Journal of Environmental Quality. 

24(2): 209-226.

DeBano, L.F.; Neary, D.G.; Folliott, P.F. 1998. Fire’s 

effects on ecosystems. New York: John Wiley & 

Sons, Inc. 333 p.

Elliott, K.J.; Boring, L.R.; Swank, W.T. 2002. 

Aboveground biomass and nutrient pools in 

a Southern Appalachian watershed 20 years 

after clearcutting. Canadian Journal of Forest 

Research. 32(4): 667-683. 

Knoepp, J.D.; Swank, W.T. 1997. Long-term effects 

of commercial sawlog harvest on soil cation 

concentrations. Forest Ecology and Management. 

93(1-2): 1-7.

Knoepp, J.D.; DeBano, L.F.; Neary, D.G. 2005. Soil 

chemistry. In: Neary, D.G.; Ryan, K.C.; DeBano, 

L.F., eds. Wildland fire in ecosystems: effects of 

fire on soil and water. Gen. Tech. Rep. RMRS-42. 

Fort Collins, CO: U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Research Station: 

53-71. 

Newell, C.L.; Peet, R.K. 1995. Vegetation of Linville 

Gorge Wilderness, North Carolina. Curriculum 

in Ecology and Department of Biology. Chapel 

Hill, NC: University of North Carolina. 

Reilly, M.J.; Wimberly, M.C.; Newell, C.L. 2006. 

Wildfire effects on plant species richness at 

multiple spatial scales in forest communities of 

the southern Appalachians. Journal of Ecology. 

94(1): 118-130.

Robichaud, P.R. 2005. Measurement of postfire hillslope erosion to evaluate and model 

rehabilitation treatment effectiveness and 

recovery. International Journal of Wildland Fire. 

14(4): 475-485. 

SAS Institute Inc. 2002-2003. SAS/STAT Guide for 

personal computers. Version 9.1, Cary, NC.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 235

COMMUNITIES AND DENSITY ESTIMATES 

OF HISTORICAL AND CURRENT MISSOURI OZARKS FORESTS

Brice B. Hanberry, Hong S. He, Daniel C. Dey, John M. Kabrick, and Brian J. Palik

Research Associate (BBH) and Associate Professor (HSH), Department of Forestry, 

203 Natural Resource Building, University of Missouri, Columbia, MO, 65211; 

Research Forester (DCD, JMK, BJP). BBH is corresponding author: 

to contact, call 573-875-5341 ext. 230 or email at hanberryb@missouri.edu.

Introduction

Forests in Missouri changed after European settlement, due in part to timber harvest, 

fire suppression, grazing, and conversion to agricultural and urban land use. There are 

few current examples of fire-mediated composition and structure present in oak and pine 

savannas and woodlands. Reconstruction of historical landscapes can provide a reference 

for restoration efforts.

METHODS

The United States General Land Office (GLO) surveyed trees during 1815-1864 in the 

Missouri Ozarks. The U.S. Forest Service’s Forest Inventory and Analysis (FIA) program 

surveys current forests. Using data from 2004-2008, we selected live trees with a 

diameter at breast height (d.b.h) ≥ 12.7 cm. Our ecological unit was a subsection divided 

into land types (ECOMAP 1993).

For community assignment in an ecological unit, the number of trees had to be ≥200 per 

ecological unit, and percent composition of species had to be ≥10 per ecological unit to 

be a dominant species in the community. Community order was based on descending 

mean percent composition for all GLO trees.

For density estimation in an ecological unit, FIA plots had to be 100 percent forest 

land. For historical forests, we used the Morisita plotless density estimator and applied 

corrections for surveyor bias. For current forests, we calculated trees per acre using the 

expansion factor of 6.018046, based on one tree representing the inverse of the plot 

area in acres (i.e., 1/[4*0.04154172]). To predict densities continuously for 835,000 

Soil Survey Geographic (SSURGO) Database polygons (mean area of 10 ha), we used 

calculated plot density, 24 soil and topographic predictor variables, and random forests, 

an ensemble regression tree method.

RESULTS AND DISCUSSION

Across the Missouri Ozarks, there has been a decrease in oaks from 79 percent of 

species composition to 57 percent of species composition. This has resulted in changes 

in communities. Dominant oak species (as defined by ≥ 10 percent composition) have 

been reduced and replaced by a mixture of many species, of which only eastern redcedar 

and maples have become dominant. Current forest densities are approximately two times 

greater than historical densities. Current forests are about 300 to 400 trees/ha (d.b.h. ≥ 

12.7 cm), with little deviation. Historical forests had greater deviation and ranged from 

a mean of 75 to 320 trees per ha. The greatest density increases were in the drier western 

Ozarks close to the prairies, where historical densities were lower.
236 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Although climate change, insects, fungal pathogens, and deer herbivory probably 

all contribute to oak declines, fire appears to be the primary factor that determines 

community composition and structure. Regionally distinct, oak-dominated and firedependent communities have been replaced by denser, fire-intolerant species. Currently, 

many oak-dominated forests have understories of shade-tolerant species, and in 

the future, upland eastern forests may become duplicates of mesic forests without 

management. Oak restoration will become more difficult if the overstory is no longer oak. 

Oak forest management and research priorities include commitment to both prescribed 

burns and opening the canopy and subcanopy where there is an oak understory.

LITERATURE CITED

ECOMAP. 1993. National hierarchical framework of ecological units. Washington, 

DC: U.S. Department of Agriculture, Forest Service. 20 p.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 237

RESTORING OAK REGENERATION AFTER OVERGRAZING AND FIRE 

IN ZAGROS FORESTS

Azad Henareh Khalyani, Audrey L. Mayer, and Manouchehr Namiranian

Research Assistant (AHK) and Assistant Professor (ALM), School of Forest Resources 

and Environmental Science, Michigan Technological University, 1400 Townsend Dr., 

Houghton, MI, 49931; Professor (MN). AHK is corresponding author: 

to contact, call 906-231-1186 or email at ahenareh@mtu.edu.

Introduction

Zagros oak forests have a long history of use by 

local communities. Palynological research provides 

evidence of stock breeding, grazing, and agriculture 

at least since the beginning of the fifth millennium 

cal B.P. (Djamali and others 2009, Sumner 1990, 

Wright and others 1967). The traditional sustainable 

management was maintained by a homeorhetic 

regulation in pre-technological land use (Naveh 1988). 

This regulation was acquired by a balance between the 

anthropogenic utilization of the forests for livelihood 

necessities and stabilizing feedbacks from a lack of 

food, water, and social components, generating a 

resource protection mechanism. Resource utilization 

activities such as coppicing and cultivation were 

practiced by rotations (Ghazanfari and others 2004). 

Landscapes maintained a patchwork formed by the 

combined effects and interaction of fire, grazing, and 

coppicing. 

However, contemporary technological progress and 

maladaptive policies have eliminated the economical 

feedbacks from population control by providing 

food, water, and medicine for man and livestock 

regardless of water supply, even though the lack of 

economical development should provide economic 

incentives to reduce pressures on the forests. The 

social stabilizing feedback was eliminated by a 

transition to governmental ownership and new 

regulations. Forests were nationalized in 1963, and 

grazing and coppicing became illegal. The Iranian 

government has tried to protect the forest (and 

encourage regeneration) from livestock grazing 

through the use of various exclosures, but these have 

not been effective in prohibiting overutilization in all 

areas because of the economical needs of locals. In 

this situation, the landscapes are no longer formed by 

the combined effects and interaction of fire, grazing, 

and coppicing because these influential factors are 

separated from each other in the landscape and have 

led to the formation of the two extreme models in 

Zagros landscapes: with and without exclosures. In 

areas without government exclosures, there is no 

or very limited fire frequency because of the quick 

consumption of understory grasslands by livestock. 

But overgrazing by livestock (mainly goats) leads to 

the lack of regeneration with consequent soil erosion. 

The additional pressure from climate change-induced 

droughts further catalyzes the transition of the forest 

landscapes to deserts. In areas with government 

exclosures that restrict access of people and livestock, 

the forest cover is frequently affected by fires during 

the dry season. Forest stands cannot recover quickly 

from the wildfires which devastate the ecological 

condition because of the dry and hot conditions in 

summer. If the fires are too frequent, they also reduce 

fauna and flora and inhibit regeneration through 

topsoil destruction.

The social and economical feedbacks, therefore, need 

to be restored in order to reactivate the dynamic selfstabilization and maintain ecological sustainability 

in patchy landscapes formed by the interaction of 

anthropogenic uses and fire. Restoration projects 

thus need to be carefully targeted, socially accepted, 

and implemented by direct participation of local 
238 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

communities using their traditional ecological wisdom. 

In this study we implement an adaptive management 

approach to: (1) gradually eliminate the boundaries 

between the two extreme conditions by reintroducing 

livestock grazing to avoid frequent extreme wildfires; 

(2) establish seed based regeneration in the context 

of grazing and coppicing by local communities; (3) 

restore the social feedbacks by giving access and 

utilization rights to local communities and use their 

participation in the project; and (4) evaluate the 

potential of the sites for regeneration establishment 

and compare different technical approaches for the 

regeneration establishment in the area.

STUDY AREA

The study area was 15 ha of Armardeh forests (45°48’ 

N, 35°56’ E) in the northern Zagros region in Baneh 

city, Kurdistan province, Iran (Fig. 1). These xeric 

forests are dominated by Quercus spp. with other 

deciduous species occurring occasionally. Forest cover 

rarely exceeds 70 percent. The average elevation is 

1675 m a.s.l., and average annual precipitation is 615 

mm. The bedrock is mainly formed by quartzite. The 

soil type is mainly formed of inceptisols and in some 

areas is heavily destructed and forms entisols.

METHODS

Thirty 1000 m2 circular plots were randomly located 

in the study area. The height, diameter at breast height 

(d.b.h.), and crown diameter at two directions were 

measured for all trees in the circular plots (Fig. 1). 

One soil profile was dug in each plot, and soil 

physicochemical characteristics were analyzed. Four 

restoration techniques were established in each of 

Figure 1.—Location of study area in Iran, position of the 1000 m2 circular plots in the study area, and the five 1 m2 micro plots 

in each circular plot.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 239

the circle plots as study treatments in 1 m2 micro 

plots, along with a control micro plot at the center of 

the plots in autumn. The study was conducted in the 

framework of a randomized complete block design 

(RCBD). The restoration approaches (treatment micro 

plots) were:

1. Fencing outside the crown coverage

2. Fencing under the crown coverage

3. Direct seeding outside the crown coverage

4. Seeding using Jiffy technique (Skoupy and 

Hughes 1971) outside the crown coverage

The treatment micro plots were fenced, and the 

control micro plots were left unfenced under the 

crown coverage of each plot’s center tree (Fig. 1). The 

response variables were the proportion of established 

seedlings and the heights of the saplings in the spring. 

Analysis of Variance (ANOVA) and Tukey’s post hoc 

test were used to test the difference between treatments 

at 0.05 significance level.

RESULTS

The quantitative measurements showed that 74.1 

percent of the trees in the study area were Lebanon oak 

(Quercus libani Olivier). Gall oak (Quercus infectoria

Olivier), Mann oak (Quercus brantii L.), pistachio 

(Pistacia atlantica Desf.), and wild pear (Pyrus glabra

Boiss.) formed 24.8 percent, 0.6 percent, 0.3 percent, 

and 0.2 percent of the trees, respectively. Mean d.b.h., 

height of the trees, and canopy cover were 29 cm, 

6.6 m, and 1314 m2

/ha, respectively. Aspects did not 

show significant effects on tree characteristics and 

treatment effects. Physicochemical analysis of soil 

characteristics in two layers showed that in spite 

of being mechanically compacted and destructed, 

it had proper physicochemical characteristics for 

regeneration (Henareh 2005, Namiranian and others 

2007). There was a significant difference in restoration 

success between fenced and unfenced study plots (Fig. 

2). Areas in exclosures demonstrated regeneration 

while controls with no fencing did not. Planting with 

Jiffy pellets resulted in significantly taller saplings 

compared to other approaches (Fig. 3). Direct seeding 

treatments were significantly lower in height than 

planting Jiffy pellets but taller than other treatments.

DISCUSSION

Higher percentage of Lebanon oak indicates forest 

stands with better ecological conditions, since 

this species requires higher humidity and deeper 

soils compared to other oak species. Forest stand 

measurements and soil analysis indicated that the 

potential for natural regeneration still exists. Applying 

exclosures over large areas increases the understory 

Figure 2.—Mean proportion of established seedlings for the 

five treatments in early spring (error bars represent standard 

errors).

Figure 3.—Mean heights of saplings for the five treatments 

in summer (error bars represent standard errors). 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Seeding-Jiffy Direct seeding Fencing-under-CC Fencing-out-CC Control

Treatments

Proportions

0

2

4

6

8

10

12

14

16

Seeding-Jiffy Direct seeding Fencing-under-CC Fencing-out-CC Control

Treatments

Height (cm)
240 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

dry vegetation and risk of extreme wildfires as well 

as social problems by forcing local communities out 

of forests. However, the very small exclosures tested 

here do not suffer from either of these problems and 

demonstrated that regeneration in a context of grazing 

and coppicing is feasible. Fencing at a small scale 

(1 m2

), even outside of the crown coverage and 

without applying artificial restoration techniques, 

ensured the establishment of regeneration significantly 

higher than in unfenced areas, where no regeneration 

occurred. No significant difference was found between 

natural and artificial restoration methods regarding 

the proportion of established seedlings. This suggests 

that the simple treatment of building a small fence 

around small, scattered areas is a low-cost, practical 

management approach that local communities can 

use to help restore forest regeneration into these 

landscapes. However, a significant difference was 

found between artificial and natural methods regarding 

the heights of the resultant saplings in the summer; 

the artificial methods resulted in taller samplings. 

These artificial methods may be a necessary addition 

in areas that have lost a significant amount of topsoil 

and where natural regeneration might grow too slow 

relative to the need for the resource base that the 

forests represent.

The study demonstrated that conservation at small 

scales in a context of livestock grazing and coppicing 

by local communities can result in forest regeneration 

and fire avoidance, while simultaneously being 

acceptable to local communities. Applied across the 

region, this approach could eliminate the boundary 

between the two dominant extreme conditions of fire 

and grazing and maintain patchy landscapes formed 

by the interaction of all factors including fire, grazing, 

and coppicing.

LITERATURE CITED

Djamali, M.; De Beaulieu, J.L.; Miller, N.F.; AndrieuPonel, V.; Ponel, P.; Lak, R.; Sadeddin, N.; 

Akhani, H.; Fazeli, H. 2009. Vegetation history of 

the SE section of the Zagros Mountains during 

the last five millennia; a pollen record from the 

Maharlou Lake, Fars Province, Iran. Vegetation 

History and Archaeobotany. 18(2): 123-136.

Ghazanfari, H.; Namiranian, M.; Sobhani, H.; 

Marvi Mohajer, R. 2004. Traditional forest 

management and its application to encourage 

public participation for sustainable forest 

management in the northern Zagros Mountains 

of Kurdistan province, Iran. Scandinavian 

Journal of Forest Research. 19(4): 65-71.

Henareh, A. 2005. Investigation, monitoring 

and evaluation of forest sustainability using 

permanent plots and suggested applicable 

approaches in forest management in Zagros, 

case study in Armardeh. Tehran, Iran: University 

of Tehran. 73 p. M.S. thesis. In Persian.

Namiranian, M.; Henareh, A; Ghazanfari, H.; Zahedi, 

G. 2007. Investigation of various management 

approaches for restoration & regeneration 

settlement in northern Zagros. Forest and Poplar 

Research. 15 (4): 386-397. In Persian.

Naveh, Z. 1988. Biocybernetic perspectives of 

landscape ecology and management. In: Moss 

M.R., ed. Landscape ecology and management. 

Montreal: Polyscience: 23-24.

Skoupy, J.; Hughes, E.L. 1971. Reforestation using 

Jiffy 7 peat pellets. Tree Planters’ Notes. 22: 1-4.

Sumner, W.M. 1990. An archaeological estimate of 

population trends since 6000 B.C. in the Kur 

River Basin, Fars Province, Iran. In: South 

Asian archaeology. Rome, Italy: Istituto Italiano 

per il Medio ed Estremo Oriente: 1-16.

Wright, H.E.; McAndrews, J.H.; van Zeist, W. 1967. 

Modern pollen rain in western Iran, and its 

relation to plant geography and Quaternary 

vegetational history. Journal of Ecology. 

55: 415-443.

The content of this paper reflects the views of the 

author(s), who are responsible for the facts and accuracy 

of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 241

INITIATING RESTORATION OF WOODLAND COMMUNITIES: 

THE EFFECT OF THINNING AND PRESCRIBED FIRE 

ON STAND STRUCTURE IN THE OZARK HIGHLANDS

Carter O. Kinkead, John M. Kabrick, Michael C. Stambaugh, and Keith W. Grabner

Graduate Research Assistant (COK); Research Forester (JMK), U.S. Forest Service, 

Northern Research Station, 202 Natural Resources Building, Columbia, MO 65211; 

Research Associate (MCS); Ecologist (KWG). JMK is corresponding author: 

to contact, call 573-875-5341 ext. 229 or email at jkabrick@fs.fed.us.

Introduction

In the last two centuries, Missouri Ozark forests 

have undergone immense transformation as a result 

of timber harvests and fire suppression (Dey and 

Hartman 2005, Ladd 1991). As fuel accumulation and 

canopy closure have increased (Kolaks 2004), so has 

interest in restoring and maintaining the woodland 

and savanna ecosystems that once prevailed across 

the Ozark landscape (Johnson and others 2002, Ladd 

1991, Nuzzo 1986). Woodland communities are 

characterized by open understories and dense ground 

flora comprised of forbs, grasses, and sedges (Nelson 

2005, Nuzzo 1986, Taft 2009). They once were 

common in the western Central Hardwood Region and 

prairie-forest transition zone where low-intensity fires 

occurred frequently (Guyette and others 2002, Taft 

2009). With fire-based management making its way to 

the forefront of this effort, a number of science-based 

efforts are aimed at quantifying the response of natural 

systems to various fire or disturbance regimes. 

The purpose of this study was to gain insight as to the 

implications of various treatments, from prescribed 

burning to thinning harvests and the combination. Our 

objective was to examine changes in forest structure, 

such as diameter distribution, canopy cover, and 

species composition, as a function of fire, thinning, 

and aspect to better understand how to restore oak and 

oak-pine woodlands. 

The project area is located in the Missouri Ozarks 

at Logan Creek and Clearwater Creek Conservation 

Areas, both managed by the Missouri Department of 

Conservation. Each site lies within the Black River 

Oak/Pine Woodland/Forest Hills Ecological Landtype 

Association that is characterized by steep hillslopes 

with cherty, low-base soils (Nigh and Schroeder 2002). 

The fully stocked, second-growth forests on each site 

have had no known management or fire for over 40 

years.

METHODS

Four treatments (burn, harvest, harvest-burn, and 

control) were applied to three (north slope, ridge, 

and south slope) ecological landtypes (ELTs) across 

three replicated blocks. Treatments were paired with 

the ELT to create 12 experimental units per block. 

Timber harvests (overstory thinning) occurred during 

the summer and early fall 2002 prior to the first 

burn. Harvests reduced stocking to approximately 45 

ft2

/acre by thinning from below, leaving primarily the 

dominant trees with preference for retaining shortleaf 

pine (Pinus echinata Mill.) and white oak (Quercus 

alba L.). We use the term “thinning” because the goal 

was not to regenerate the stand but rather to enhance 

the growth of the residual stand including the forbs, 

legumes, and graminoids in the understory. Two 

prescribed fires have been conducted on burn and 
242 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

harvest-burn units in each of the three blocks. The first 

occurred in early April of 2003 and the second in April 

2005 for blocks one and two. Because of unsuitable 

weather conditions, block three was not burned until 

March 2006. Consequently it was excluded from 

analysis.

Pretreatment data were collected in the summer of 

2001, and posttreatment data were collected in the 

summer of 2003 and 2005. Permanent vegetation plots 

were installed along transects during the summer of 

2001. Overstory vegetation plots consisted of three 

1/3 acre circular plots randomly located within each 

treatment/aspect class. All live trees (diameter at 

breast height [d.b.h.] > 1.5 inch) were identified to 

species and d.b.h. was measured. Ground flora data 

were collected at a total of 1,080 quadrats (size = 10.8 

ft2

, 30 per experimental unit). Within each quadrat, 

all live herbaceous plants and shrubs were identified 

to species, and cover by species was estimated to the 

nearest percent. 

RESULTS and DISCUSSION

Average pretreatment stocking for all stands was 94.2 

percent, composed primarily of trees greater than 10.5 

inches d.b.h., even after treatments. Prescribed fire 

alone decreased overall stocking nearly 10 percent 

from pretreatment conditions, having significant 

reductions in all trees less than 10 inches. In fact, 

2-5 inch stems declined 22 percent after a single fire, 

and 52 percent after a second fire. However, due to 

the minimal impacts on larger diameter trees, the 

effects of prescribed fire to overall stocking were not 

significantly different from the control. No significant 

(P < 0.05) interaction between aspect and treatment on 

stocking or ground flora coverage was detected. 

The effects of harvest-burn treatments on stocking did 

not significantly differ from harvest only treatments 

(Fig. 1). These findings indicate that prescribed fire 

has the ability to decrease the abundance of small 

diameter stems without drastically altering stand 

structure. From a woodland restoration standpoint, it 

is desirable to decrease the abundance of understory 

woody plants to provide more growing space for the 

herbaceous plants. In the absence of fire, hardwood 

seedlings and seedling sprouts proliferate, which can 

shade herbaceous plants and reduce their coverage 

(Hutchinson and others 2005). This is especially the 

case in the presence of increased canopy openness, 

such as after a harvest. Although our results show a 

minor decrease in woody stems one year after harvestburn treatments, preliminary results from recently 

collected data (2011) suggests that without continued 

burning, small trees and shrubs begin to limit all other 

life forms in the understory.

Life forms documented in the quadrats include forbs, 

graminoids, legumes, shrubs, and vines. All of these 

physiognomic groups increased with both prescribed 

fire and the combination of burning and harvesting. 

Since many restoration efforts are aimed at increasing 

forb and graminoid communities, it is important to 

note that harvest-burn treatments more than doubled 

the percent coverage of these life forms compared 

Figure 1.—Gingrich (1967) diagram portraying changes 

in stocking for each treatment from 2001 to 2006. Actual 

stocking percentages are slightly misrepresented because 

the parameters used are based on “typical upland oakhickory” stands rather than calibrated to the quadratic mean 

diameter of our study site (Johnson and others 2002). 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 243

to burning alone and harvesting alone. Analyses of a 

class of woodland indicator species (i.e., a collective 

group of forbs, graminoids, legumes, and shrubs) 

(Table 1) showed this class increased 42 percent in 

relative cover on plots that were harvested and burned, 

a near three- to fourfold increase compared to burn 

only and harvest only treatments (Fig. 2). Woodland 

indicators within control plots increased 2 percent. 

Overall, the results of this study suggest that 

commercial overstory thinning followed by two 

prescribed fires has the potential to restore woodland 

structure and composition (Nelson 2005, Taft 2009). 

Our findings also demonstrate the relationships 

between stand structural metrics such as stocking to 

woodland ground flora and shrub cover in the presence 

or absence of prescribed fire. These relationships 

have seldom been quantified and documented in the 

woodland restoration literature. This sequence of 

management techniques most effectively resulted in 

stands characteristic of woodland conditions (i.e., 

basal area 30-50 ft2

/acre, abundant forb and grass 

populations, and minimal midstory tree density 

[Nelson 2005]). While mechanical removal of the 

midstory and overstory trees fulfills these restoration 

objectives, increased burning becomes necessary to 

manage the understory woody response to canopy 

openness. Prescribed fire alone may pose a sustainable 

option for woodland restoration where overstory 

stocking is decreased over time, thereby subtly 

achieving canopy openness and suppression of woody 

regeneration. 

LITERATURE CITED

Dey, D.C.; Hartman, G. 2005. Returning fire to 

Ozark Highland forest ecosystems: effects 

on advance reproduction. Forest Ecology and 

Management. 217: 37-53.

Gingrich, S.F. 1967. Measuring and evaluating 

stocking and stand density in upland hardwood 

forests in the Central States. Forest Science. 

13: 38-53.

Guyette, R.P.; Muzika, R.M.; Dey, D.C. 2002. 

Dynamics of an anthropogenic fire regime.

Andropogon gerardii Ecosystems. 5: 472-486.

Asclepias tuberosa

Aureolaria grandiflora

Babtisia bracteata

Blephilia ciliata

Ceanothus americanus

Comandra umbellata

Coreopsis palmata

Cunila origanoides

Dalea purpurea

Desmodium rotundifolium

Echinacea pallida

Eryngium yuccifolium

Euphorbia corollata

Gentiana alba

Gillenia stipulata

Helianthus hirsutus

Ionactis linariifolius

Lespedeza hirta

Lespedeza procumbens

Lespedeza violacea

Lespedeza virginica

Liatris aspera

Liatris squarrosa

Lithospermum canescens

Monarda bradburiana

Orbexilum pedunculatum

Parthenium integrifolium

Phlox pilosa

Pycnanthemum tenuifolium

Schizachyrium scoparium

Silene regia

Silene stellata

Silphium integrifolium

Silphium terebinthinaceum

Solidago hispida

Solidago petiolaris

Solidago radula

Solidago rigida

Solidago speciosa

Solidago ulmifolia

Sorghastrum nutans

Symphyotrichum anomalum

Symphyotrichum 

oolentangiense

Symphyotrichum patens

Symphyotrichum turbinellum

Taenidia integerrima

Tephrosia virginiana

Verbesina helianthoides

Violoa pedata

Table 1.—List of woodland indicator species used 

in understory vegetation sampling

Figure 2.—Changes in percent coverage of woodland 

indicator species (see Table 1) for all treatments. Significant 

differences (P < 0.05) among treatments are indicated with 

differing letters.
244 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Hutchinson, T.F.; Sutherland, E.K.; Yaussy, D.A. 

2005. Effects of repeated prescribed fires on 

the structure, composition, and regeneration of 

mixed oak forests in Ohio. Forest Ecology and 

Management. 218: 210-228.

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

ecology and silviculture of oaks. Wallingford, 

UK: CABI. 503 p.

Kolaks, J. 2004. Fuel loading and fire behavior in 

the Missouri Ozarks of the Central Hardwood 

Region. Columbia, MO: University of Missouri. 

115 p. M.S. thesis.

Ladd, D. 1991. Reexamination of the role of fire 

in Missouri oak woodlands. In: Burger, G.V.; 

Ebinger, J.E.; Wilhelm, G.S., eds. Proceedings 

of the oak woods management workshop; 1988 

October 21-22; Charleston, IL: 67-80.

Nigh, T.A.; Schroeder, W.A. 2002. Atlas of Missouri 

ecoregions. Jefferson City, MO: Missouri 

Department of Conservation. 212 p.

Nelson, P.W., 2005. The terrestrial natural 

communities of Missouri. Jefferson City, MO: 

Missouri Natural Areas Committee. 550 p.

Nuzzo, V.A. 1986. Extent and status of Midwest oak 

savanna: pre-settlement and 1985. Natural Areas 

Journal. 6: 6-36.

Taft, J.B. 2009. Effects of overstory stand density 

and fire on ground layer vegetation in oak 

woodland and savanna habitats. In: Hutchinson, 

T.F., ed. Proceedings of the 3rd fire in eastern oak 

forests conference; 2008 May 20-22; Carbondale, 

IL. Gen. Tech. Rep. NRS-P-46. Newtown Square, 

PA: U.S. Department of Agriculture, Forest 

Service, Northern Research Station: 21-39.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 245

EFFECTS OF MULTIPLE INTENSE DISTURBANCES AT MANLEY WOODS, 

WILSON’S CREEK NATIONAL BATTLEFIELD

Sherry A. Leis and Kevin James

Fire Ecologist (SAL), Biology Department, Missouri State University, 901 South National Avenue, 

Springfield, MO 65897; Plant Ecologist (KJ). SAL is corresponding author: 

to contact, call 417-836-8919 or email at sleis@partner.nps.gov.

abstract

Natural communities in southwest Missouri are often challenged by ecological 

disturbances of a catastrophic nature. Windthrow, wildfire, flooding, drought, and ice 

storm events all occur periodically and range in spatial extent from local to regional. 

Although in this region local disturbances are common in singularity, it is unusual for 

several disturbances to affect the same locality within a short time period. Since 2003, 

however, the Ozark Highlands region has seen widespread events including tornados, 

fires, floods, and ice storms, many occurring in succession on the same piece of land. 

Understanding the change in vegetation composition and recovery rates resulting from 

multiple severe disturbances is crucial to natural resource management planning.

In 2003, a tornado struck the Manley Woods area of Wilson’s Creek National Battlefield 

(WICR) affecting 60 ha. The affected area included long-term monitoring sites sampled 

both 3 years prior to and post-tornado. In the post-tornado years, three additional notable 

disturbances occurred, but each disturbance differentially affected each of the sites. 

Increased fuel loads resulting from the tornado damage caused concern for elevated 

wildfire risk, so park staff made plans to reduce fuel loads. In 2005, a contractor removed 

salvageable timber from Manley Woods, and the following year a prescribed fire was 

completed. In 2007 a January ice storm further affected communities in Manley Woods. 

The aim of this study was to determine the effectiveness of the fuels reduction activities, 

and to describe the composition of overstory and understory plant communities currently 

inhabiting Manley Woods. 

Fuel loads at Manley Woods were quite high post-tornado, especially at site four 

(Fig. 1). The fuels reduction process, log removal, and fire reduced mean fuel loads 

by approximately half, leaving an average of 18.5 tons/ha. Mean fuel loads were 

significantly reduced at site 4 that received the most damage and notable reductions were 

seen at site 5. 

Changes occurred in several aspects of the plant community. Overstory tree density was 

reduced by 4.31 m2 per ha, mainly by the tornado (Fig. 2). In 2006, trees in the larger 

size classes (35+ cm diameter at breast height [d.b.h.]) could only be found at the less 

disturbed sites in the woods, and canopy closure trended towards a savannah structure. 

Regeneration (seedlings and saplings) was reduced overall, including a significant 

decline in oak and hickory species. Diversity of the herbaceous understory plants 

dropped significantly during the period of heaviest disturbance (2003-2006). Understory 

plant community response lagged 1 year behind disturbance events (Fig. 3). Plant 
246 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

community composition shifted towards more early seral woodland species after 2004 

at all sites, but the greatest change occurred at the most heavily disturbed areas in the 

woods. Furthermore, 2007 composition appeared to be on a path back toward previous 

community composition. Plant guilds, particularly woody plants, pulsed after the tornado 

but returned to similar predisturbance conditions. Exotic species remained low and did 

not change significantly over time.

This analysis may aid park natural resource managers to plan to achieve the desired 

conditions in Manley Woods. Prior to the 2003 tornado, park managers used fire to work 

towards a savannah community type. The disturbances had a heterogeneous effect on the 

whole management unit, hastening the restoration process in parts of Manley Woods, but 

not greatly affecting others.

Figure 1.—(A) Mean fuel loading by time lag class for Manley Woods. Error bars represent one 

standard deviation for mean total fuel load (not time lag class), (B) mean fuel loading by sampling 

site for Manley Woods. Asterisk indicates loadings at site 4 were significantly different through time 

(P = 0.04, r2 = 0.92).
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 247

Figure 2.—Total basal area (m2/ha) of trees in each size class throughout monitoring history at 

Manley Woods, (diameter at breast height = d.b.h.).

Figure 3.—Mean diversity measures with standard error bars for the understory community in 

Manley Woods long-term monitoring plots. Measures were converted to effective number of 

species for comparison.
248 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

POTENTIAL EFFECTS OF FIRE AND TIMBER HARVEST ON TERRESTRIAL

SALAMANDER MICROHABITAT USE IN A MISSOURI OZARK FOREST

Katherine M. O’Donnell, Frank R. Thompson III, and Raymond D. Semlitsch

Graduate Student Researcher (KMO), Division of Biological Sciences, University of Missouri, 

105 Tucker Hall, Columbia, MO 65211-7400; Research Wildlife Biologist (FRT); 

Curators Professor (RDS). KMO is corresponding author: 

to contact, call 573-882-1421 or email at kmozrc@mail.missouri.edu. 

BACKGROUND

Prescribed fire and timber harvest are human-caused 

disturbances that can have substantial effects on forest 

ecosystems. It is generally accepted that some methods 

of timber harvest adversely affect forest-dependent 

wildlife, including amphibians (e.g., Petranka and 

others 1993, Semlitsch and others 2009). However, 

wildlife responses to fire are not as well understood; 

they vary considerably among species, and are affected 

by fire seasonality and severity (Lyon and others 

2000). As the use of prescribed fire becomes more 

common, it is essential to better understand the effects 

of controlled burns on forest-dependent wildlife. 

Fire and Amphibians

Fire effects on amphibians remain incompletely 

understood but likely vary among species, geographic 

regions, and habitat types (Pilliod and others 2003). 

Amphibians require wet or moist places for breeding, 

nesting, and respiration, and are very susceptible to 

heat and desiccation. Therefore, they often retreat 

under cover objects such as rocks and logs to retain 

moisture when the leaf litter is dry. Amphibians have 

limited movement capacity (Russell and others 1999), 

which likely forces them to stay and cope with habitat 

changes postfire. This unique suite of characteristics 

may make amphibians more vulnerable to fire than 

other wildlife taxa. 

Recent studies have found little evidence of 

amphibians being directly affected by prescribed 

fire (burns, mortality from fire) in the short-term 

(Pilliod and others 2003, Russell and others 1999). 

However, fire can indirectly affect wildlife by altering 

components of their habitat. These indirect effects are 

likely key for amphibians because of their sensitivity 

to changes in microhabitat, such as leaf litter and 

downed wood, and could be long-lasting (Pilliod and 

others 2003). 

Focal Species

We chose to focus our study on the southern redback 

salamander (Plethodon serratus) (Fig. 1). Redback 

salamanders and other species in the Plethodontidae 

family are fully terrestrial; they do not have an 

Figure 1.—Southern redback salamander (Plethodon 

serratus).
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 249

aquatic larval stage like many other amphibians. They 

undergo direct development resulting in hatchlings that 

resemble miniature adults. Plethodontid salamanders 

are also lungless and respire directly through their 

skin, and therefore, are very moisture-dependent. 

These salamanders typically have very small home 

ranges. Previous studies have shown that the southern 

redbacks are most surface-active in the spring and 

fall when temperatures are moderate (Herbeck and 

Semlitsch 2000). They spend most of the summer 

months in underground refugia to avoid desiccation 

and heat stress. They are also nocturnal and come to 

the surface at night to forage. During the day, they 

usually retreat underground or under cover objects. 

Importance

Terrestrial salamanders like the southern redback 

are the dominant vertebrate predators in many forest 

ecosystems and represent a large portion of the 

vertebrate biomass (Burton and Likens 1975), although 

they are often overlooked because of their fossorial 

nature. Several studies suggest that these types of 

salamanders may play an integral role in forest 

ecosystem dynamics, such as nutrient cycling, leaf 

litter decomposition, and even carbon sequestration 

(Burton and Likens 1975, Welsh and Droege 2001, 

Wyman 1998). Disturbance events such as timber 

harvest cause drying of the soil and leaf litter and 

make forests less capable of supporting amphibians 

(Semlitsch and others 2009, Welsh and Droege 2001). 

Because prescribed fires also affect leaf litter and 

cover objects, there may be negative consequences 

for amphibians. We are investigating the effects 

of prescribed fire and timber harvest on terrestrial 

salamanders. We are interested in how these forestry 

practices affect salamander abundance and behavior. 

This paper focuses on the predicted outcomes of the 

study, based on pretreatment data, on the distribution 

of salamanders among microhabitats. 

STUDY AREA AND METHODS

The study is taking place in the Sinkin Experimental 

Forest, located within the Mark Twain National 

Forest in the Ozark Highlands region of south-central 

Missouri. The site consists of mature, fully-stocked 

oak-hickory stands. Five 5-ha replicate experimental 

plots per treatment will be subjected to one of the 

following treatments: prescription burn, shelterwood 

harvest, or midstory herbicide. Five plots will serve 

as controls. We sampled two locations (upslope, 

downslope) within each of the 20 sampling plots in 

the spring and fall of 2010. We conducted 3 x 3 m 

area-constrained searches of natural cover objects 

and leaf litter, and measured snout-vent length (SVL) 

and recorded the capture location of all salamanders 

(southern redback salamander, western slimy 

salamander [Plethodon albagula], and dark-sided 

salamander [Eurycea longicauda melanopleura]).

RESULTS

We captured 1025 southern redback salamanders, 

18 western slimy salamanders, and 4 dark-sided 

salamanders. We found most salamanders (74 percent) 

within the leaf litter; the remaining 25 percent were 

found under natural cover objects such as logs and 

rocks (Fig. 2). We captured more salamanders during 

downslope surveys (566) than upslope surveys (481). 

Salamander density was strongly correlated with 

recent rainfall (Fig. 3). We also found no significant 

pretreatment differences between groups. 

Figure 2.—Location of salamander captures.
250 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Figure 3.—Relationship between number of salamander 

captures and recent rainfall. 

CONCLUSIONS AND PREDICTIONS

Our pretreatment results suggest that redback 

salamanders are more likely to be found in leaf litter 

than expected. Many studies on terrestrial salamanders 

focus on sampling natural cover objects and do not 

include leaf litter searches. We believe our sampling 

technique results in a more complete understanding 

of salamanders’ distribution among microhabitats, 

and it will allow us to detect changes in cover object 

use following prescribed fire and timber harvest. We 

predict that competition for cover objects will increase 

following fire and timber harvest due to decreases 

in leaf litter and drier surface conditions. We expect 

to reveal more about the role of leaf litter loss in 

salamander population persistence. 

It is important for managers to consider the unique 

characteristics of amphibians when implementing 

forest management plans. Because amphibians 

have different microhabitat requirements than other 

vertebrate taxa such as lizards or snakes, they are 

likely to have different responses to fire. Terrestrial 

salamanders, such as the southern redback, may be 

even more susceptible to fire than other amphibians. 

ACKNOWLEDGMENTS

This project is funded by a grant from the U.S. 

Department of Agriculture, Forest Service (#10-JV11242311-061). Many thanks to Dana Drake, Michael 

Osbourn, Grant Connette, and Katie LaJeunesse 

for assistance in the field. Photo provided by Bill 

Peterman.

LITERATURE CITED

Burton, T.M.; Likens, G.E. 1975. Salamander 

populations and biomass in the Hubbard Brook 

Experimental Forest, New Hampshire. Copeia. 

1975(3): 541-546.

Herbeck, L.A.; Semlitsch, R.D. 2000. Life history 

and ecology of the southern redback 

salamander, Plethodon serratus, in Missouri.

Journal of Herpetology. 34(3): 341-347. 

Lyon, L.J.; Telfer, E.S.; Schreiner, D.S. 2000. Direct 

effects of fire and animal responses. In: Smith, 

J.K., ed. Wildland fire in ecosystems: effects of 

fire on fauna. Gen. Tech. Rep. RMRS-42-vol. 

1. Ogden, UT: U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Research Station: 

17-23.

Petranka, J.W.; Eldridge, M.E.; Haley, K.E. 1993. 

Effects of timber harvesting on Southern 

Appalachian salamanders. Conservation 

Biology. 7(2): 363-370. 

Pilliod, D.S.; Bury, R.B.; Hyde, E.J.; Pearl, C.A.; 

Corn, P.S. 2003. Fire and amphibians in North 

America. Forest Ecology and Management. 

178: 163-181. 

Russell, K.R.; Van Lear, D.H.; Guynn, D.C. 1999. 

Prescribed fire effects on herpetofauna: review 

and management implications. Wildlife Society 

Bulletin. 27(2): 374-384. 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 251

Semlitsch, R.D.; Todd, B.D.; Blomquist, S.M.; 

Calhoun, A.J.K.; Gibbons, J.W.; Gibbs, J.P.; 

Graeter, G.J.; Harper, E.B.; Hocking, D.J.; 

Hunter, M.L.; Patrick, D.A.; Rittenhouse, T.A.G.; 

Rothermel, B.B. 2009. Effects of timber harvest 

on amphibian populations: understanding 

mechanisms from forest experiments.

BioScience. 59: 853-862. 

Welsh, H.H.; Droege, S. 2001. A case for using 

plethodontid salamanders for monitoring 

biodiversity and ecosystem integrity of North 

American forests. Conservation Biology. 15(3): 

558-569. 

Wyman, R.L. 1998. Experimental assessment of 

salamanders as predators of detrital food webs: 

effects on invertebrates, decomposition and the 

carbon cycle. Biodiversity and Conservation. 

7: 641-650. 

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
252 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

SOIL AND LITTER NUTRIENTS FOLLOWING 

REPEAT ED AND PERIODIC BURNING IN THE MISSOURI OZARKS

Felix Ponder, Jr.

For more information, contact Daniel C. Dey, Research Forester, Northern Research Station, 

202 ABNR Bldg., University of Missouri-Columbia, Columbia, MO 65211-7260. 

To contact, call 573-875-5341 or email ddey@fs.fed.us

Abstract

Extractable nutrients in the surface litter and soil of oak-hickory (Quercus spp. and 

Carya spp.) forest plots subjected to annual and periodic prescribed burning were 

studied on plots located in the Chilton Creek basin in southeast Missouri on land 

owned and managed by The Nature Conservancy (TNC). Soils are generally poor and 

excessively drained and have developed over dolomite and sandstone bedrock. The TNC 

has intensively monitored vegetation responses to the high frequency, low intensity 

fire regime at the site including such variables as frequency, timing, intensity, and fuel 

conditions since pretreatment in 1996 and posttreatment in 1998 (Table 1). Little work 

has been performed at the Chilton Creek Management Area to examine soil and litter 

nutrient changes that may result from fire activities on the highly weathered soils on 

the site.

In 2007, the crew monitoring vegetation was permitted to collect soil and litter samples 

on vegetation plots during the same visit. After processing samples, they were analyzed 

for various chemical properties including pH, total organic carbon (TOC), N, P, K, Ca, 

Mg, and S. 

Nitrogen and S in the upper 0 to 15 cm of soil were significantly lower (α = 0.05) for 

plots burned annually than in plots burned periodically (Table 2). Several nutrients (P, K, 

Ca, Mg, and S) in the surface litter also differed between burning treatments. Differences 

were not consistent among treatments, suggesting possible differences in plant species 

contributing to litter composition as a consequence of burning treatments. 

Differences in nutrients attributed to aspect showed litter N, P, and K and soil N, P, K, 

and S were lowest on north facing slopes and usually highest on south facing slopes 

(Table 3). Differences in site moisture and temperature between aspects are likely 

explanations for the response. Correlations for aspect were significant for soil P (r = 0.45, 

P = 0.016) and for litter S (r = 0.45, P = 0.034). Except for N and P, concentrations of 

nutrients in litter were not strongly related to the concentration of nutrients in the soil. 

Further, among nutrients, only the concentration of P in the soil and its corresponding 

level in the litter were significantly correlated (r = 0.49, P = 0.012). 

Overall, TOC, although somewhat lower in soil for the annual burn treatment, did not 

differ between burn treatments for soil or litter. Unfortunately, this study does not include 

a “control” or “no burn” treatment for comparison. However, considering the lack of a 

control treatment, based on soil nutrient concentrations and litter nutrition, these results 

suggest that annual and periodic burning has had minimal effects on soils within the 

Chilton Basin, and perhaps the most ecologically significant effect was the loss of soil 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 253

N and S associated with annual burning. While these data represent a one-time view 

after 9 years of annual and periodic prescribed burns, they do give insight on soil and 

litter nutrient changes associated with burning treatments within the Chilton Creek 

Management Area in the Missouri Ozarks.

ACKNOWLEDGMENTS

The author thanks the Nature Conservancy for permission to do this study.

 Treatment (Burn interval over 9 years) Return

Location Aspect Size (ac) 1 2 3 4 5 6 7 8 9 Sequence Interval

Kelly North 600 X X X X X X X X X Annual 1.00

Kelly South 410 X X X X 1.3.4.7 2.25

Chilton East 460 X X X X 1.5.6.9 2.25

Chilton North 465 X X X X 1.2.3.6 2.25

Table 1.—Burn schedule for fire units in the Chilton Preserve (Missouri Ozarks) 

Burn sequence 

Interval (Years burned over 9 years)

Annually 1.3.4.7 1.5.6.9 1.5.7 1.2.3.6

Property 1.00 2.25 2.25 3.00 2.25

Soil

pH 5.3(1.0) 5.8(0.9) 5.5(0.8) 4.9(0.4) 5.0(0.9)

EC 132.4(112) 117(66) 120.6(21) 83.4(14) 77(41)

Carbon (g kg-1) 1.5(0.5) 2.7(0.9) 1.8(1.5) 2.6(0.9) 2.3(0.7)

N (%) 0.08(0.03)b 0.17(0.08)a 0.11(0.03)ab 0.10(0.02)ab 0.12(0.02)ab

P (mg kg-1) 10.4(4.4) 17.8(4.1) 15.9(3.3) 12.2(3.5) 13.7(6.8)

K (mg kg-1) 0.6(10) 85.0(43) 85.7(14) 47.1(15) 61.0(46)

Ca (mg kg-1) 419(370) 833(621) 525(484) 184(129) 140(109)

Mg (mg kg-1) 106.5(74) 226.2(168) 69.9(55) 24.3(11) 36.1(18)

S (mg kg-1) 10.4(3.0)a 14.2(3.7)ab 15.1(4.5)ab 15.5(1.2)ab 17.4(4.6)b

Litter

Carbon (g kg-1) 44.1(5.1) 43.8(2.3) 46.0(1.2) 46.0(2.1) 44.1(5.3)

N (g kg-1) 0.91(0.2) 1.2(0.1) 1.1(0.2) 0.99((0.1) 1.22(0.3)

P (g kg-1) 0.05(0.01)c 0.08(0.00)a 0.06(0.02)abc 0.05(0.00)bc 0.07(0.01)ab

K (g kg-1) 0.14(0.04)b 0.13(0.02)b 0.16(0.02)b 0.16(0.01)b 0.25(0.06)a

Ca (g kg-1) 1.5(0.4)ab 2.1(0.3)a 1.6(0.3)ab 1.2(0.5)b 1.3(0.4)ab

Mg (g kg-1) 0.20(0.07)a 0.14(0.05)ab 0.16(0.03)ab 0.10(0.03)b 0.14(0.03)ab

S (g kg-1) 0.09(0.02)ab 0.12(0.01)a 0.11(0.01)ab 0.08(0.01)b 0.10(0.02)ab

Table 2.—Effect of fire sequence and interval on soil quality characteristics in 

the upper soil layer in the Chilton Creek Preserve located in the Missouri Ozarks. 

EC=electrical conductivity. Means plus standard errors in parentheses within a row 

followed by different letters are significantly different at α = 0.05 (Tukey’s HSD).
254 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Site aspect

Property North South East

Soil

pH 5.2(0.8) 5.4(0.6) 5.5(0.9)

Ec 116.1(85) 98.5(43) 120.6(59)

Carbon (g kg-1) 1.9(1.4) 2.5(1.3) 1.8(0.9)

N (%) 0.09(0.04)b 0.14(0.07)a 0.11(0.6)ab

P (mg kg-1) 10.9(4.0)b 15.9(6.4)a 15.9(7.5)a

K (mg kg-1) 42.8(12.2)b 73.0(9.8)a 85.7(47.6)a

Ca (mg kg-1) 341.1(262) 513.2(354) 526.4(432)

Mg (mg kg-1) 79.1(42.5) 138.4(185.5) 69.9(57.1)

S (mg kg-1) 11.1(2.3)b 15.7(4.2)a 15.1(4.9)a

Litter

Carbon (g kg-1) 44.7(3.2) 44.0(3.8) 46.0(1.2)

N (g kg-1) 0.93(0.12)b 1.21(0.017)a 1.12(0.16)ab

P (g kg-1) 0.05(0.01)b 0.07(0.01)a 0.06(0.02)a

K (g kg-1) 0.14(0.02)b 0.16(0.04)ab 0.20(0.02)a

Ca (g kg-1) 1.41(0.45) 1.63(0.33) 1.59(0.30)

Mg (g kg-1) 0.16(0.05) 0.14(0.04) 0.16(0.03)

S (g kg-1) 0.09(0.01) 0.10(0.01) 0.11(0.01)

Table 3.—Influence of site aspect on soil quality characteristics in the upper 

soil layer (0 to 15 cm) and surface litter following burnings in the Chilton 

Creek Preserve located in the Missouri Ozarks. Means plus standard errors in 

parentheses within a row followed by different letters are significantly different 

at α = 0.05 (Tukey’s HSD).

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 255

HERBACEOUS UNDERSTORY AND SEED BANK RESPONSE 

TO RESTORATION EFFORTS AT AN OAK-PINE BARRENS 

IN CENTRAL WISCONSIN

Jeffrey L. Ralston and James E. Cook

Master of Science candidate (JLR) and Professor of Forestry (JEC), College of Natural Resources, 

University of Wisconsin-Stevens Point, 800 Reserve St., Stevens Point, WI 54481. 

JLR is the corresponding author: to contact, call 920-810-6103 or email at jralston@new.rr.com.

Abstract

The Wisconsin Department of Natural Resources (WDNR) has designated barrens 

communities as high priority for restoration. These communities are globally imperiled 

and support many endangered and threatened species. Many barrens are in various 

stages of degradation or are unmanaged. Restoration of structure and fire may increase 

understory richness of true prairie species (Tester 1989). An intermediate term 

evaluation of management efforts at the Quincy Bluff and Wetlands Area (Quincy Bluff) 

demonstrated only small changes with harvesting and return of fire (Nielsen 2003). 

This discrepancy in results may reflect the length of fire suppression and the degree of 

degradation at Quincy Bluff. Prior to initiating management, fire had been absent from 

Quincy Bluff for approximately 70 years, while other restoration sites have reported fire 

suppression of approximately 30 years.

Quincy Bluff is located in Adams County, Wisconsin and consists of over 1500 ha of 

several community types, including considerable oak-pine barrens. The objectives of 

this study were to test the impact of prescribed fire, timber harvest, and the seed bank 

on understory plant diversity at Quincy Bluff. Thirty-nine permanent transects were 

established prior to initiation of restoration efforts in five of The Nature Conservancy 

(TNC) management units and in the unmanaged WDNR property. An additional 26 

newly established, independent transects and the 39 previously established transects were 

monitored in 2010. The following were determined: cover and presence of all living 

vegetation <1 m tall; shrub and small tree cover and density; and tree cover, density, and 

basal area. Soil samples were obtained for greenhouse analysis of the seed bank. Species 

richness and ground layer cover in 2010 were lowest in management units treated with 

prescribed fire alone and were 50 percent to 150 percent greater in units with substantial 

reduction in canopy cover and basal area. Structural changes resulted from timber harvest 

and/or a tornado that struck one management unit in 2004. After a literature review, 

we generated a list of species likely to be indicators of barrens vegetation (Bray 1960, 

Curtis 1959, Will-Wolf and Stearns 1999). In 2010, these barrens indicator species had 

the largest percent cover in the control unit, however, cover of barrens indicator species 

declined in all units. In units with reduced canopy cover and basal area, barrens indicator 

species richness increased by two to three species and declined or remained the same in 

the other units. Frequent fires eliminated shrubs and small trees. Greenhouse analysis of 

the seed bank demonstrated low species richness and produced few germinates of any 

restoration value.
256 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Barrens, if left unmanaged, degrade to closed canopy forests with low species richness 

and low ground layer cover. Frequent fires over 17 years were ineffective at reducing 

canopy cover or basal area, and understory species richness remained low. Manipulation 

of the tree structure through timber harvest and/or natural processes (i.e., tornado) 

increased understory species richness, however, species determined to indicate healthy 

barrens communities decreased in relative cover, and richness only increased marginally. 

These results confirm that the resiliency of this system may be exceeded by the long 

period without management and the seven decades of fire suppression.

LITERATURE CITED

Bray, J.R. 1960. The composition of savanna vegetation in Wisconsin. Ecology. 41: 

721-732.

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

Wisconsin Press. 657 p.

Nielsen, S.; Kirschbaum, C.; Haney, A. 2003. Restoration of midwest oak barrens: 

Structural manipulation or process-only? Conservation Ecology. 7: 10-24.

Tester, J.R. 1989. Effects of fire frequency on oak savanna in east-central Minnesota.

Bulletin of the Torrey Botanical Club. 116: 134-14.

Will-Wolf, S.; Stearns, F. 1999. Dry soil oak savanna in the Great Lakes Region. In: 

Anderson, R.C.; Fralish, J.S.; Baskin, J.M., eds. Savannas, barrens, and rock outcrop 

plant communities of North America. New York, NY: Cambridge University Press: 

135-154.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 257

PRESCRIBED FIRE AND THINNING IMPACTS ON FINE FUELS 

AT THE WILLIAM B. BANKHEAD NATIONAL FOREST, ALABAMA

Callie Jo Schweitzer and Stacy L. Clark

Research Forester (CJS), U.S. Forest Service, Southern Research Station, 

P.O. Box 1568, Normal, AL 35762; Research Forester (SLC). CJS is corresponding author: 

to contact call 256-372-4230 or email at cschweitzer@fs.fed.us. 

Introduction

Prescribed burning and thinning are intermediate stand treatments whose consequences 

when applied in mixed pine-hardwood stands are unknown. The William B. Bankhead 

National Forest in north Alabama has undertaken these two options to restore unmanaged 

loblolly pine (Pinus taeda L.) plantations to hardwood-dominated stands. Our objective 

was to evaluate differences in fine fuel and duff dynamics in a combination of thinning 

and fire regimes.

METHODS

We installed a randomized complete block design with a 3 x 2 factorial treatment 

arrangement and four replications of each treatment. Treatments were three residual basal 

areas (50 ft2

 ac-1, 75 ft2 ac-1, and an untreated control) with two burn frequencies (burns 

every 3 years and an unburned control). Two prescribed burns were implemented. We 

collected measurements before and after each treatment implementation. A 1 ft2

 wooden 

frame was used to collect samples, which were sorted into duff, leaves, 1-hour fuel (0.1-

0.25 inches), 10-hour fuel (0.26-1 inch), fruit, and bark categories. Samples were oven 

dried until no change in weight was detected and then weighed to the nearest 0.01 g. 

RESULTS

Main effect of thinning was significant for duff, 10-hour, 1-hour, and bark immediately 

after thinning. Compared to controls, thinning increased duff (+4.3 and +5.7 tons 

ac-1 for 50 ft2

 ac-1 and 75 ft2 ac-1, respectively), 1-hour (+0.2 tons ac-1 for both thinning 

treatments), 10-hour (+1.6 and +1.4 tons ac-1 for 50 ft2

 ac-1 and 75 ft2 ac-1, respectively), 

and bark loads (+0.4 and +0.3 tons ac-1 for 50 ft2 ac-1 and 75 ft2 ac-1, respectively). Three 

years following thinning, only leaf litter had significant differences with a reduction of 

-1.1 and -0.8 tons ac-1 in 50 ft2

 ac-1 and 75 ft2 ac-1 treatments, respectively. Burning and its 

interaction with thinning were not significant after the first burn. After the second burn, 

leaf litter decreased by 0.5 tons ac-1 compared to controls, and bark increased by 0.1 tons 

ac-1. Leaf litter decreased by 0.5 tons ac-1 after the second burn, and bark increased by 

0.1 tons ac-1. Duff, 1-hour, 10-hour, and fruit were not affected by the first or second burn. 
258 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

CONCLUSIONS

Burning alone and in conjunction with thinning as applied in this study had minimal 

effects on fine fuels and duff. Thinning produced more of a reduction in fine fuels than 

did burning, likely due to higher decomposition rates related to increased sunlight hitting 

the forest floor. Based on these results, we do not recommend using prescribed fire in 

these stands to reduce fine fuel and duff loads, but recognize fire has other benefits not 

measured in this study for vegetation diversity and wildlife habitat. 

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 259

SIMULATING TREATMENT EFFECTS IN PINE-OAK FORESTS 

OF THE OUACHITA MOUNTAINS

Ayn Shlisky, Kori Blankenship, and Shawn M. Cochran

Regional Analyst (AS), U.S. Forest Service, Pacific Northwest Region, 333 SW. First Ave., 

Portland, OR 97204; Fire Ecologist (KB), The Nature Conservancy; Wildlife Biologist (SMC), 

U.S. Forest Service, Ouachita National Forest. AS is corresponding author: 

to contact, call 503-808-2284 or email at ajshlisky@fs.fed.us.

ABSTRACT

Effective land management decisionmaking depends on scientifically sound analyses of 

management alternatives relative to desired future conditions and environmental effects. 

We used a state-and-transition model to evaluate likely future landscape conditions in a 

pine-oak forest on the Ouachita National Forest, Arkansas based on current and potential 

future alternative management actions. Our objectives were to: (1) demonstrate the use of 

state-and-transition models in project planning, and (2) create simple “what if” scenarios 

to supplement the project environmental impact assessment and facilitate more informed 

decisionmaking through relative comparisons. We used the model to simulate and 

compare the effects of several management alternatives:

A. Current Management 

B. Regeneration Harvest/Thinning 

C. Woodland Management 

D. Regeneration Harvest/Thinning + Climate Change 

E. Woodland Management + Climate Change 

The effects of these alternatives were also compared against modeled ecological 

reference conditions. 

At the time of the study, a national forest interdisciplinary team was completing a projectlevel environmental assessment of alternative management scenarios across the 16,700 

acre Lower Irons Fork/Johnson Creek watershed. The watershed is located within the 

Ouachita National Forest near the town of Mena in western Arkansas. It is comprised 

primarily of pine-oak forest and woodland and has a history of active fire management. 

The watershed is a drinking water source for the town of Mena, Arkansas, offers 

recreational opportunities including hunting and fishing, and is home to two federallyendangered species: the red-cockaded woodpecker (Picoides borealis) and the harperella 

plant (Ptilimnium nodosumis). 

We modified the LANDFIRE Ozark-Ouachita Shortleaf Pine-Oak Forest and Woodland 

model (USDA FS and USDI 2009) using stand exam and other forest data to represent 

current landscape structure and disturbance probabilities. Timber harvest volume per acre 

coefficients were estimated from a similar nearby project, and smoke production values 

for particulate matter (PM 10 and 2.5) were estimated from the First Order Fire Effects 

Model. Forest colleagues and U.S. Forest Service Southern Research Station scientists 

provided peer review. We used the Vegetation Dynamics Development Tool and the Path 

Landscape Model, a state-and-transition modeling framework and platform, to simulate 

the effects of the various alternatives after 10 years.
260 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Our results indicate that a woodland management emphasis generally yielded landscape 

structure and fire frequencies closer to the desired future condition specified in the 

2005 Ouachita National Forest Revised Forest Plan (USDA FS 2005) compared to a 

regeneration harvest/thinning emphasis (Figs. 1 and 2). When potential climate effects 

were considered, the woodland management emphasis also yielded greater smoke 

(Fig. 3) and woody biomass harvest outputs (Fig. 4) than the regeneration harvest/

thinning emphasis. 

These findings suggest that Forest Plan revisions should reevaluate the desired future 

conditions for pine-oak forest in light of the fact that it does not currently include a 

standard for mid-seral forest structure, and that the existing desired future condition 

standard for late seral open woodland is lower than LANDFIRE reference conditions. 

While the model outputs have proven to be useful, the process forced the team to test 

assumptions and document knowledge, two intangible but valuable outcomes.

LITERATURE CITED

U.S. Department of Agriculture, Forest Service; U.S. Department of Interior. 2009. 

LANDFIRE 1.1.0 Vegetation Dynamics Models [Database]. Available at 

http://www.landfire.gov. (Accessed 11 August 2009).

U.S. Department of Agriculture, Forest Service. 2005. Revised land and resource 

management plan: Ouachita National Forest-Arkansas and Oklahoma.

Management Bulletin R8-MB 124A. Washington, DC.

Figure 1.—Proportions of pine-oak forest and woodland structural stages resulting from modeled 

management alternatives, ecological reference conditions, and revised forest plan desired 

conditions after a 10-year simulation.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.

0

10

20

30

40

50

60

70

80

90

100

Forest Plan

Desired Future

Condition

LANDFIRE

Reference

Condition

No Action A: Current

Management

B: Regeneration

Harvest/Thinning

C:Woodland

Management

D: B + Climate

Change

E: C + Climate

Change

Mature Closed

Mature Open

Mid-SeralOpen

Mid-SeralClosed

Early Seral

Scenario

Percent of Pine -Oak Forest
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 261

Figure 2.—Comparative return intervals for fire, insects and disease, and wind/weather/stress 

disturbances resulting from modeled management alternatives and ecological reference conditions. 

Figure 3.—Comparative smoke emissions resulting from modeled management alternatives and 

ecological reference conditions.

Figure 4.—Comparative biomass harvest resulting from modeled management alternatives.

0

50

100

150

200

250

300

350

400

450

500

LANDFIRE

Reference

Condition

No Action A: Current

Management

B: Regeneration

Harvest/Thinning

C: Woodland

Management

D: B + Climate

Change

E: C + Climate

Change

All Fire Return Interval (years)

Insect& Disease Return Interval (years)

Wind,Weather & Stress Return Interval (years)

0

10

20

30

40

50

60

70

LANDFIRE

Reference

Condition

No Action A: Current

Management

B: Regeneration

Harvest/Thinning

C: Woodland

Management

D: B + Climate

Change

E: C + Climate

Change

PM 2.5 & 10 from Fire (tons/acre/year)

0

2

4

6

8

10

12

14

16

0

200

400

600

800

1000

1200

1400

LANDFIRE

Reference

Condition

No Action B: Regeneration

Harvest/Thinning

C: Woodland

Management

D: B + Climate

Change

E: C + Climate

Change

Pre Commercial Harvest (CCF/year)

Commercial Harvest (CCF/year)

Commercial Biomass

Pre Commercial Biomass Harvest
262 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

VEGETATION STRUCTURE AND SOIL WATER CONTENT AFTER 60 YEARS 

OF REPEATED PRESCRIBED BURNING IN THE MISSOURI OZARKS

Kirsten Stephan and Jason A. Hubbart

Assistant Professor of Biology (KS), Department of Life and Physical Sciences, 

Lincoln University of Missouri, 816 Chestnut St., Jefferson City, MO 65101; 

Assistant Professor of Forest Hydrology (JAH). KS is corresponding author: 

to contact, call 573-681-5116 or email at stephank@lincolnu.edu.

Introduction

Two important interrelated factors determining 

ecosystem structure and function are vegetation 

composition and soil moisture. Both are affected 

directly and indirectly by fire (Hart and others 

2005). Few studies have characterized the longterm effects of repeated spring prescribed burning 

on these ecosystem characteristics. As an exception, 

Lewis and Harshbarger (1976) found that 20 years 

of repeated prescribed burning had significant and 

consistent effects on shrubs and herbs. However, 

post-fire soil moisture has been shown to increase 

(Klock and Helvey 1976), decrease (Campbell and 

others 1977), or remain the same (Wells and others 

1979) after single fire events. This could be attributed 

to the timing of measurements, sampling design, 

and/or differential fire effects on the many factors that 

influence soil moisture, such as interception by plants 

or forest floor, evaporation from the canopy or the soil, 

transpiration, and infiltration rates. 

The objectives of this study were to quantify the 

effects of 60 years of repeated spring prescribed 

burning at annual and 4-year intervals on a) vegetation 

composition and structure, b) soil physical properties, 

and c) their effects on soil moisture in a Missouri oakhickory forest.

STUDY AREA

The research was conducted at University Forest 

Conservation Area located in the Ozark Mountains 

near Wappapello in southeast Missouri. Data were 

collected from a total of six 40 m by 40 m plots in two 

sites. Site 1 and site 2 are approximately 3.2 km apart 

and were established in 1949 and 1951, respectively. 

At each site, plots are separated by a 10 m buffer. 

At each site, one of the studied plots is burned every 

spring (annual burn treatment, A), every 4 years 

(periodic burn treatment, P), or never (control, C). The 

last periodic burns prior to data collection took place 

in 2007 (site 2) and 2009 (site 1).

METHODS

Vegetation cover and forest floor mass data were 

collected in 2010. Cover of herbaceous and woody 

understory vegetation (<0.5 m height) and woody 

midstory vegetation (0.5-2 m height) was assessed 

using 32 sampling quadrats (1 m by 1 m) per plot. 

Quadrats were placed every 5 m along transects 

spaced 10 m apart. Cover was estimated to the nearest 

percent. Cover of shrubs and trees in the midstory and 

overstory >1.4 m was assessed via the Leaf Area Index 

(LAI) using a ceptometer in nine locations per plot.

Forest floor mass was quantified by collecting material 

from eight circular areas (30 cm diameter) per plot. 

Forest floor material was air-dried; woody and 

nonwoody components were separated and weighed.

Soil physical properties were assessed in eight 

locations per plot in 2009. Infiltration capacity was 

measured via double-ring infiltrometers. Bulk density 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 263

was determined from soil cores (5 cm diameter, 5 

cm long). Soil volumetric water content (VWC) was 

continuously measured at 15 cm depth in one location 

per plot at 30 minute intervals from 2008 to 2010. 

RESULTS & DISCUSSION

Tree and shrub cover (>1.4 m) was highest in the 

controls (LAI: A 2.3, P 2.1, C 3.4). This was attributed 

to fire-related tree mortality at the beginning of the 

study in annual and periodic burns. We predicted that 

interception, canopy evaporation, and transpiration 

losses by midstory and overstory trees lowered soil 

moisture in the controls more strongly relative to other 

treatments.

Cover of understory plants was highest in annual 

burns (cover in percent: A 40.0, P 37.2, C 14.0); cover 

of understory and midstory (<2 m) plants together 

was highest in the periodic burns (cover in percent: 

A 40.0, P 64.5, C 31.0). This was due to lack of 

woody seedling survival in annual burns but abundant 

resprouting in periodic burns. We predicted that 

interception, canopy evaporation, and transpiration 

losses by these plants reduced soil moisture in the 

periodic burn more strongly than in other treatments.

Forest floor (mainly leaf litter) was least abundant in 

annual burns because of frequent combustion (forest 

floor content in t ha-1: A 4.7, P 8.5, C 15.4). The 

predicted effect on soil moisture was ambiguous. On 

one hand, low interception by and evaporation from 

a thin litter layer would facilitate precipitation to 

enter into the mineral soil. On the other hand, once in 

mineral soil, water is more likely to evaporate from a 

soil lacking litter insulation. 

Infiltration capacity was lowest in annual burns (A 

11, P 41, C 107 cm h-1). This was likely due to a 

compacted top layer of soils from raindrop impact 

on bare ground in annual burns (bulk density in g 

cm-3

: A 0.99, P 0.96, C 0.94). We predicted that lower 

infiltration capacity decreased soil moisture in annual 

burns relative to other treatments.

In all treatments, direct measurements of soil moisture 

showed the expected temporal pattern of decreased 

soil moisture during the growing seasons due to 

increased evapotranspiration. However, there was 

no consistent fire effect on soil moisture. While 

VWC in annual burns was intermediate to the other 

treatments at both sites, VWC of the control was 

highest in site 1 but lowest in site 2 for the majority of 

the measurement period. This indicates the existence 

of significant microsite differences between sensor 

locations, masking any potential fire effect. 

CONCLUSIONS

While burn treatments affected vegetation and soil 

physical characteristics in a similar way in both 

sites, there was no consistent treatment effect on soil 

volumetric water content between the two sites. We 

hypothesize that this is likely due to large microsite 

variability commonly observed in soils. Several VWC 

probes per plot would be required to capture plot-scale 

soil moisture levels. Despite the low intensity of spring 

prescribed burning, repeated burning over decades has 

dramatic effects on vegetation characteristics and soil 

physical properties. A mechanistic understanding of 

the effects of long-term prescribed burning will result 

in better informed forest management decisions in 

Ozark oak-hickory forest.

ACKNOWLEDGMENTS

We thank Staria Vanderpool (plant data collection 

and identification), Edward Bulliner, Graham 

Freeman and Thomas Stokely (LAI, soil sampling), 

Brittany Winston (forest floor processing), and Marie 

Obourn, UM Forest Manager. Financial support was 

provided by DOD (W911NF-05-2-0003), John Yang 

at LU Cooperative Research, USDA CSREES/NIFA 

McIntire-Stennis (Accession #:218480), and the 

University of Missouri. 
264 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

LITERATURE CITED

Campbell, R.; Baker, M., Jr.; Folliott, P.; Larson, F.; 

Avery, C. 1977. Wildfire effects on a ponderosa 

pine ecosystem: an Arizona case study. Res. 

Pap. RM-191. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain 

Forest and Range Experiment Station. 12 p.

Hart, S.C.; DeLuca, T.H.; Newman, G.S.; MacKenzie, 

M.D.; Boyle, S.I. 2005. Post-fire vegetative 

dynamics as drivers of microbial community 

structure and function in forest soils. Forest 

Ecology and Management. 220: 166-184.

Klock, G.; Helvey, J. 1976. Soil water trends 

following wildfire in the Entiat Experimental 

Forest. In: Komarek, E.V., ed. Proceedings, 15th 

Tall Timbers Fire Ecology Conference, Pacific 

Northwest; 1974 October 16-17; Portland, OR. 

Tallahassee, FL: Tall Timbers Research Station: 

193-200.

Lewis, C.; Harshbarger, T. 1976. Shrub and 

herbaceous vegetation after 20 years of 

prescribed burning in the South Carolina 

coastal plain. Journal of Range Management. 

29: 13-18.

Wells, C.; Campbell, R.; DeBano, L.F.; Lewis, 

C.; Fredericksen, R.; Froelich, R.; Dunn, P. 

1979. Effects of fire on soil: a state of the art 

knowledge review. Gen. Tech. Rep. WO-7. 

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

Forest Service. 34 p.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Abstracts
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Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 267

RESTORATION OF HIGH ELEVATION RED OAK WITH FIRE 

IN THE SOUTHERN BLUE RIDGE

Peter Bates, Dean Simon, Gary Kauffman, Margit Bucher, 

Jon Shaffer, and Rob Lamb

Associate Professor (PB), Department of Geosciences and Natural Resources, 

Western Carolina University, 331 Stillwell Building, Cullowhee, NC 28723; 

Wildlife Forester (DS), North Carolina Wildlife Resources Commission; Botanist (GK), 

U.S. Forest Service, National Forests of North Carolina; Assistant Director (MB), 

The Nature Conservancy; Associate Forester (JS) and Forester (RL), Forest Stewards, Inc. 

PB is corresponding author: to contact, call 828-227-3914 or email bates@email.wcu.edu.

ABSTRACT

Prescribed fire is most often used to restore fire-adapted plant communities on xeric and 

mesic sites since these are the areas where frequent, low-intensity fires are most common. 

In southern Appalachian forests, these sites are typically found on south- and west-facing 

slopes and on ridges that historically supported varying pine and oak communities. 

The Southern Blue Ridge Fire Learning Network (SBRFLN) was created with the goal 

of restoring historical fire regimes across the southern Blue Ridge. The SBRFLN has 

targeted four plant communities for restoration. Three of the four forest communities 

are typical of relatively xeric sites. These include Shortleaf Pine-Oak, Pine-Oak-Heath, 

and Dry-Mesic Oak-Hickory. However, the fourth, High Elevation Red Oak (HERO), 

is unique in that it occurs at high elevations that are generally more cool and moist. 

This poster will present information on the extent of the HERO type in the southern 

Blue Ridge as well as the current composition and structure of stands being targeted 

for restoration. We will compare current stand structure to HERO restoration models 

developed by SBRFLN and others. We will also present preliminary results from several 

prescribed burns that have been performed in these stands and discuss fuel load changes 

and burn performance.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
268 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

COMPARING THE IMPORTANCE VALUE OF OVERSTORY 

AND UNDERSTORY TREES IN OAK FORESTS

Chad Bladow

Fire Manager, The Nature Conservancy, Indiana Field Office, 

Efroymson Conservation Center, 620 East Ohio Street, Indianapolis, IN 46202. 

To contact, call 317-829-3807 or email at cbladow@tnc.org.

ABSTRACT

In 2007, The Nature Conservancy began a long-term project at a site within the Brown 

County Hills of Indiana to manage dry-mesic oak forests. The understory of the oak 

forest is currently dominated by more mesic forest tree species. In the event of a canopy 

disturbance, there is little chance for oak and hickory saplings to compete with mesic 

forest species for canopy dominance. By comparing the importance value [IV = (relative 

basal area + relative density)/2] of tree species in the forest canopy (≥ 8 inch diameter 

at breast height [d.b.h.]) with the forest understory (4.5 ft tall - 8 inch d.b.h.) we can 

get a better idea of the severity of this problem. This monitoring will help determine if 

management activities are improving the IV of oak trees within the forest understory. 

Baseline data were collected from fifty-three 0.1-acre monitoring plots in the summer of 

2007. Oak species had an IV of 0.88 in the forest canopy compared to less than 0.04 in 

the understory. Data collected the first year following thinning and burning treatments 

in the fall/winter 2007 showed no increase in oak species’ IV in the understory, but there 

was a 20.7 percent reduction in basal area and 6.25 percent reduction in canopy closure. 

The monitoring of the forest overstory vs. understory will repeat every 5 years plus 

1 year following any management treatment and/or natural disturbance to determine 

if, over time, the IV of oaks in the understory increases. The long-term goal is to show 

whether forest management techniques used in the project can shift the dry/mesic forest 

understory from beech/maple dominance to oak/hickory.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 269

THE EFFECTS OF SEASONALLY PRESCRIBED FIRE 

ON A DOLOMITE GLADE

Mary Ann Blinkhorn and D. Alexander Wait

Graduate Assistant (MAB) and Associate Professor (DAW), Missouri State University, 

24058 East Cedar Point Rd, Lebanon, MO 65536-7719. MAB is corresponding author: 

to contact, call 417-718-7247 or email at Blinkhorn777@live.missouristate.edu.

ABSTRACT

The diverse vegetation that dominates glade systems is dependent on fire for long-term 

sustainability; therefore, prescribed fires are an important management tool. However, fire 

management has focused on spring and dormant season burns, with spring burns favoring 

grasses and dormant season burns favoring forbs. Growing season fires are known to 

kill woody plants that are not fire adapted; however, the effects of growing season burns 

on species composition are not well documented. In an effort to determine optimum 

methods of glade management, we are studying the effects of prescribed fire during 

different seasons in a dolomite glade at Ha Ha Tonka State Park in Camden County, 

MO. Three sites have been established, each containing four treatments. Within each 

site, one treatment area is designated as an unburned control, and each of the remaining 

treatment areas will have fire applied during the spring, dormant, or growing season. 

Initial observations and application of fire were conducted from July to September of 

2010 with subsequent applications scheduled for February and April of 2011. Final data 

collection and analysis will extend through September of 2011. Data will be comprised of 

both pre- and posttreatment observations, as well as observations timed to coincide with 

spring/early summer and late summer flowering periods. Quantification of the effects of 

seasonal burns will be accomplished through population studies conducted within and 

among plots. The results of this study should enable land managers to schedule burns in 

order to achieve a desired vegetation response. Baseline floristic assessment and initial 

postburn results were presented at the 4th Fire in Eastern Oak Forest Conference. 

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
270 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

RESEARCHING EFFECTS OF PRESCRIBED FIRE 

IN HARDWOOD FORESTS

Stacy L. Clark, Kathleen E. Franzreb, Cathryn H. Greenberg, Tara Keyser, 

Susan C. Loeb, David L. Loftis, W. Henry McNab, Joy M. O’Keefe, 

Callie Jo Schweitzer, and Martin Spetich

Research Forester (SLC, TK, DLL, WHM, CJS), Research Wildlife Biologist (KEF, JMO), 

Research Ecologist (CHG, SCL), Research Forest Ecologist (MS), U.S. Forest Service, 

Southern Research Station, 200 W.T. Weaver Boulevard, Asheville, NC 28804. 

CHG is the corresponding author: to contact, call 828-667-5261 ext.118 

or email at kgreenberg@fs.fed.us.

ABSTRACT

The Upland Hardwood Ecology and Management Research Work Unit (RWU 4157) is a 

group of research teams located across the South, strategically placed to conduct research 

in physiographic sub-regions of the upland hardwood ecosystems including the southern 

Appalachian Mountains, the Cumberland Plateau, the Boston Mountains, and the 

Missouri Plateau. Our RWU is one of 16 maintained under the Southern Research Station 

by the U.S. Forest Service. 

Our mission is to develop and disseminate knowledge and strategies for restoring, 

managing, sustaining, and enhancing the vegetation and wildlife of southern upland 

hardwood forests. Through experimental studies and modeling, our research program 

focuses on learning and predicting how upland hardwood-dominated forests and wildlife 

are affected by natural disturbances or silvicultural activities, and how plant and animal 

responses differ across environmental gradients such as elevation, moisture, and fertility. 

One of our focal research areas is fire ecology and fire effects on hardwood forests and 

the wildlife communities they support. Understanding how fire affects upland hardwood 

forest communities will help land managers to develop scientifically-based methods to 

meet their management and restoration goals. Here we highlight some of our current 

studies on fire ecology. 

FIRE ECOLOGY STUDIES

Historical Fire Frequency

We are using tree cores and fire scars to assess the frequency of fire in upland hardwood 

ecosystems prior to fire suppression efforts starting in the 1930s. For instance, in the 

Boston Mountains of Arkansas, we found that widespread fire occurred more often 

during drought years in the 1700s with fires likely achieving sizes unprecedented during 

the last century. Early transitional (1810-1830) settlement by Cherokees at population 

densities under 0.26 humans/km2

 was highly correlated (r = 0.90) with the number of 

fires per decade in the interior region of the Boston Mountains. Multiple regression 

analyses further implicated humans as well as short- and long-term climate variability 

such as forced by the El Niño/Southern Oscillation (ENSO) and Atlantic Multidecadal 

Oscillation (AMO). Understanding presettlement fire frequencies will help land managers 

in ecosystem restoration efforts. 
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 271

Fire and Fire Surrogate Study (FFS)

Scientists with RWU 4157 are participating in the wildlife component of the national 

collaborative Fire and Fire Surrogate Study (FFS). This long-term study is assessing 

how ecological components or processes may be changed or lost if fire surrogates, such 

as cuttings and mechanical fuel treatments, are used instead of fire or in combination 

with fire. Virtually no comparative data exist on how these treatments mimic ecological 

functions of fire, or how bird, reptile, amphibian, or small mammal communities respond 

to prescribed fire or fire surrogate treatments. 

Regional Oak Study

Scientists within our RWU have partnered with the North Carolina Wildlife Resources 

Commission, the Stevenson Land Company, the Northern Research Station, and the 

Mark Twain National Forest in a regional study of how hardwood tree species respond to 

prescribed fire and other silvicultural treatments across a productivity gradient and across 

the Central Hardwood Region. We and our collaborators are also studying the response 

of herbaceous plants, seed banks, acorn viability, artificial northern red oak regeneration, 

fuels, bat, bird, reptile, amphibian, and small mammal communities to prescribed fire and 

other oak regeneration treatments. This regional oak study includes three independent, 

fully replicated study areas representing different physiographic areas of the Central 

Hardwood Region including the Southern Appalachian Mountains (NC), the Cumberland 

Plateau (TN), and the Ozark Highlands (MO). University collaborators with our regional 

oak study include the University of Tennessee, Alabama A&M University, North Carolina 

State University, and the University of Missouri. 

Indiana Bats and Prescribed Fire

Scientists in our RWU are looking at the compatibility of prescribed fire in the Southern 

Appalachians with the conservation of the federally endangered Indiana bat. In 

cooperation with the Nantahala National Forest, Cherokee National Forest, and Great 

Smoky Mountains National Park, we are examining the effects of prescribed fire on 

snag population dynamics, Indiana bat roost tree availability in relation to fire history, 

and Indiana bat roost tree selection in relation to fire history and stand and landscape 

characteristics. This study will provide land managers with the information they need to 

manage Indiana bats and restore pine-oak habitats throughout the southern Appalachians.

Using Prescribed Fire to Restore Oak-Dominated Upland Hardwood 

and Hardwood-Mixed Pine Systems

Scientists are studying the use of regeneration and intermediate silviculture prescriptions 

coupled with fire to manage and restore upland hardwood systems. We have implemented 

a large-scale silvicultural assessment designed to examine the efficacy of stand-level 

prescriptions in reducing the potential impacts of gypsy moth infestations and oak 

decline on upland hardwood forests on the Daniel Boone National Forest, Kentucky. 

Early assessments showed a slight increase in tree vigor as determined by crown cover 

and position of residual trees in shelterwood with reserves, thinning, and oak woodland 

treatments. In a process to move a mixed-pine hardwood forest towards hardwooddominated stands on the William B. Bankhead National Forest in Alabama, scientists 

found that following the initial thinning and burning treatments there was a 30 percent 

reduction in percent canopy cover, and light penetration through the canopies ranged 

from 5 to 25 percent pretreatment to 29 to 60 percent posttreatment. The cool, slowmoving burns had no discernable effect on the overstory trees. Avian and herpetofaunal 

population dynamics appear to be influenced more by the thinning than the fires. 
272 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Amphibians and Prescribed Fire in Longleaf Pine-Wiregrass 

Sandhills

Scientists are studying amphibian and reptile use of isolated sinkhole ponds in both 

regularly burned and long-unburned Florida longleaf pine-wiregrass sandhills. This study 

will help land managers assess how prescribed fire affects herpetofaunal populations in 

the long term.

Artificial Regeneration and Prescribed Fire

Scientists are studying how high quality seedlings of planted oak (Quercus spp.) and 

American chestnut (Castanea dentate [Marsh.] Borkh.) respond to prescribed burning. 

Preliminary results indicate that seedlings can withstand burning several years after 

planting if root collar diameters are relatively large when established. 

Fire and Oak Decline

Scientists used LANDIS to model oak decline in the Boston Mountains of Arkansas 

150 years into the future under two fire return intervals. The analysis delineated potential 

oak decline sites and established risk ratings for these areas. This is a further step toward 

precision management and planning.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 273

SMALL MAMMAL OCCURRENCE IN OAK WOODLANDS 

AND RESTORED SAVANNAS 

Valerie J. Clarkston and Patrick A. Zollner

Graduate Research Assistant (VJC) and Assistant Professor of Wildlife Ecology (PAZ), 

Department of Forestry and Natural Resources, Purdue University, 195 Martstellar Street, 

West Lafayette, IN 47907. VJC is corresponding author: to contact, call 765-969-4016 

or email at vclarkst@purdue.edu. 

ABSTRACT

Oak savannas are rare in the United States, and few quantitative data exist on how 

the small mammal community will respond to the restoration of this ecosystem. We 

present the baseline data for an ongoing savanna restoration research project at the 

Jasper-Pulaski State Fish and Wildlife Area in northwest Indiana. During the summer 

of 2009, we investigated the density, abundance, and microhabitat preferences of small 

mammal species in oak woodlands versus existing oak savannas to better predict if shifts 

in species composition would occur after the restoration process. We used one-way 

analysis of variance to compare abundance of each species to habitat type and multiple 

linear regressions to compare their abundance with microhabitat variables. Significant 

differences in species abundance were not observed between oak woodlands and oak 

savannas. White-footed mice were positively correlated with percent herbaceous cover 

and basal area of white oaks, but negatively correlated with percent cover of soft mast. 

Southern flying squirrels were trapped only in oak woodlands and were positively 

correlated with basal area of black oaks. Eastern chipmunks were positively correlated 

with percent herbaceous cover and negatively correlated with woody stem density. Red 

squirrels were only captured in oak woodlands and were positively correlated with soft 

mast and basal area of white and black oaks, but were negatively correlated with percent 

herbaceous cover. Our data suggest that oak woodlands converted to oak savannas will 

lose woodland obligate species, and microhabitat characteristics are better predictors of 

species occurrence than the macrohabitat. 

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
274 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

VECTOR ANALYSIS OF RESPONSE OF ADVANCE REPRODUCTION 

TO REPEAT ED PRESCRIBED BURNING

Zhaofei Fan and Daniel C. Dey

Assistant Professor (ZF), Department of Forestry, Mississippi State University, Box 9681, 

Mississippi State, MS 39762-9681; Research Forester (DCD), U.S. Forest Service, 

Northern Research Station. ZF is corresponding author: to contact, call 662-325-5809 

or email at zfan@cfr.msstate.edu.

ABSTRACT

Advance reproduction is important to restore and maintain oak dominance. Response of 

oaks (Quercus spp.) and associated species to prescribed fire depends on a wide array of 

factors including site condition, fuel characteristics, fire frequency and intensity, and size 

or age of advance reproduction. It will be useful to quantify species response to fire for 

prescribing burning treatments that promote oaks while curbing their competitors. We 

used the 10-year Chilton Creek prescribed burning experiment data and vector analysis 

to simultaneously compare oak and associated species growth and resprouting ability, 

two important traits to determine future oak status. The species and size groups/classes 

identified based on the vector analysis can be directly applied to future prescribed 

burning practices.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 275

WOODLAND RESTORATION IN THE OZARK HIGHLANDS OF ARKANSAS

Allison Fowler, Douglas Zollner, and John Andre

Field Ecologist (AF) and Director of Conservation Programs (DZ), The Nature Conservancy 

Arkansas Field Office, 601 North University Ave., Little Rock, AR 72205; Ecologist (retired) (JA), 

U.S. Forest Service. AF is corresponding author: to contact, call 501-614-5084 

or email at allison_fowler@tnc.org.

ABSTRACT

Fire is one of the most important ecosystem disturbance processes in the Ozark-Ouachita 

Highlands. Conversely, the exclusion of landscape-scale fires from these ecosystems for 

the past several decades has changed the structure and species composition of the forest. 

Fire exclusion has allowed an increase of shade-tolerant, fire-intolerant tree species. 

The ecosystem restoration project on the Big Piney and Pleasant Hill Ranger Districts 

of the Ozark-St. Francis National Forest encompasses eight project areas designed 

to reduce hazardous fuels and increase forest health. Current restoration activities 

being implemented by the Forest Service include prescribed fire and commercial 

and noncommercial thinning. In order to assess changes in forest health over time, 

we monitored plant community structure and composition within the 102,120 acre 

ecosystem restoration project areas using 127 randomly placed macroplots. Data were 

collected during the summers of 2003-2006 (baseline) and 2007-2009 (remeasure). 

Data were stratified based on topographic position. Tree densities (stems per acre) 

decreased significantly in the north slope, south slope, and ridgetop communities. 

Overall tree density decreased as well. The majority of the decrease in stems per acre 

was from the midstory tree layer. Species richness in the ground layer increased in all 

communities, with a significant increase in the ridgetop community. Current restoration 

activities appear to be adequately producing the desired changes in forest structure. The 

continuation of prescribed fire is crucial to improving forest health and bringing the 

forest closer to desired ecological condition. In addition, continued monitoring can track 

progress toward desired condition and help guide forest management planning.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
276 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

RESPONSE OF SEASONAL BIRD SPECIES DENSITIES TO HABITAT

STRUCTURE AND FIRE HISTORY ALONG AN OPEN–FOREST GRADIENT

Ralph Grundel and Noel B. Pavlovic

Research Ecologist (RG), U.S. Geological Survey, Great Lakes Science Center, 

1100 North Mineral Springs Road, Porter, IN 46304; Ecologist (NBP). 

RG is corresponding author: to contact, call 219-926-8336 ext. 428 

or email at rgrundel@usgs.gov.

ABSTRACT

Along an open-forest landscape gradient in northwest Indiana, we assessed associations 

of bird species with grasslands, savannas, woodlands, scrublands, and forests by relating 

fire frequency and vegetation characteristics to seasonal densities of 72 bird species 

distributed across the open–forest gradient. About one-third of the species did not 

exhibit statistically significant relationships with any combination of seven vegetation 

characteristics that included vegetation cover in five vertical strata (bare ground; 

vegetation 0.3-1 m height; vegetation 1-2 m height; living woody shrubs, sprouts, 

saplings, or small trees 2.5-10 cm diameter at breast height [d.b.h.]; and living trees >10 

cm d.b.h.), dead tree density, and tree height. For 40 percent of the remaining species, 

models best predicting species density incorporated tree density. Therefore, management 

based solely on manipulating tree density may not be an adequate strategy for managing 

bird populations along this open–forest gradient. When fire frequency, measured over 

15 years, was added to vegetation characteristics as a predictor of species density, it 

was incorporated into models for about one-quarter of species, suggesting that fire may 

modify habitat characteristics in ways that are important for birds but not captured by 

the structural habitat variables measured. Among those species, similar numbers had 

peaks in predicted density at low, intermediate, or high fire frequency. Given these avian 

compositional variations along the open-forest gradient, managers considering restoration 

of landscapes will face a fundamental challenge. What should the habitat composition of 

the restored landscape look like? We developed a model for evaluating the desirability 

for birds of different landscape habitat compositions by quantifying an important 

conservation tradeoff inherent in making restoration decisions, the tradeoff between 

the landscape’s ability to promote avian species diversity and the landscape’s use by 

threatened avian species. This quantification allowed us to evaluate the ability of different 

landscape compositions to achieve preferable tradeoff compromises, such as maximizing 

diversity for a given level of landscape use by threatened species. Managers can use such 

tradeoff results to evaluate which landscape compositions are associated with particular 

conservation and management priorities. 

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 277

THE TRACE OF FIRE IN EASTERN NATIVE AMERICA

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

Rose M. Muzika, and Joseph M. Marschall

Research Professor (RPG), Missouri Tree-Ring Laboratory, University of Missouri, 

203 ABNR Building, Columbia MO 65211; Research Associate (MCS); Research Forester (DCD), 

U.S. Forest Service, Northern Research Station; Associate Professor (RMM); 

Research Specialist (JMM). RPG is corresponding author: to contact, 

call 573-882-7741 or email at GuyetteR@missouri.edu.

ABSTRACT

Written in the rings of trees is a history of fire in Native America that tells of humans, 

drought, and their interactions. These fire histories in eastern Native America move 

through generations and territories from 1600 to 1850. These quantitative histories are 

based on thousands of fire scars found on oak and pine trees. Each fire scar has a date, 

location, and associated human population. Here we examine the connections between 

the occurrence of wildland fire in Native America and the people who lived there, the 

Algonquin, Cherokee, Chippewa, Osage, Menominee, and others. The documentation of 

fire history ranges from the ecosystems of Appalachia, the Great Lakes, the Southeast, 

and the Midwest. We found changes in fire frequency associated with Native American 

populations in Alabama, Arkansas, Kentucky, Michigan, Missouri, Tennessee, Oklahoma, 

Ontario, Pennsylvania, and Wisconsin. Many fire regimes in eastern Native America are 

found to have a temporal human “footprint”, that is, an abrupt or rapid change in fire 

frequency not related to climate. The interactions of drought and human migrations and 

ignition are detected in the fire scar record. During years with large fires, severe drought 

is the predisposing factor, and human ignitions represent the inciting factor associated 

with the occurrence of widespread fires.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
278 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

CLIMATE AND PHYSICAL CHEMISTRY IN EASTERN FIRE REGIMES

Richard P. Guyette, Michael C. Stambaugh, Rose M. Muzika, and Daniel C. Dey

Research Professor (RPG), Research Associate (MCS), and Professor (RMM), School of 

Natural Resources, University of Missouri, 103 Anheuser-Busch Natural Resources Building, 

Columbia, Mo 65211; Research Forester (DCD), U.S. Forest Service, Northern Research Station. 

RPG is corresponding author: to contact, call 573-882-7741 or email at GuyetteR@missouri.edu.

ABSTRACT

Knowledge of the temporal-spatial variability in fire intervals is needed for understanding 

the changing effects of climate on fire regimes. This work focused on translating the 

physical chemistry of ecosystem processes and climate into fire regimes. This was 

achieved by using empirical, process, and multiple regression modeling to translate the 

laws and units of physical chemistry into the processes of ecosystem fire regimes. The 

Physical Chemistry Fire Frequency Model (PC2FM) is based on the Arrhenius equation 

and was calibrated with fire scar data, charcoal studies, and expert interval estimation. 

The model predicts the climate forcing of mean fire intervals (MFIcf) from temperature, 

precipitation, their interactions, and the partial pressure of oxygen. We used fire interval 

data from 166 sites in North America and elsewhere to calibrate the PC2FM. The PC2FM 

was calibrated with data from pre-Euro-American periods to reduce the effects of climate 

change, land use, fire suppression, and other nonclimatic factors affecting fire regimes. 

Details of the model’s chemistry and statistics are presented. The model is applied to 

ecosystems at scales from 1 km2

 or larger, but can span multiple time periods and climate 

scenarios. Mean fire intervals are mapped for the historic period from approximately 

1600 to 1820 using the PC2FM at regional scales in the eastern United States, at a 

broader scale in the United Sates, and at continental scales. Since the model does not 

directly include vegetation, natural or human ignitions, management, or topography, it 

only predicts fire regime characteristics that are influenced by climate.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 279

INFLUENCES OF TOPOGRAPHY AND FIRE 

ON EASTERN RED CEDAR (JUNIPERUS VIRGINIANA) DISTRIBUTION 

IN A PRAIRIE-FOREST TRANSITION ZONE

Lyndia D. Hammer and Michael C. Stambaugh

Research Assistant (LDH) and Research Associate (MCS), Department of Forestry, 

University of Missouri, 203 ABNR Building, Columbia, MO, 65211. LDH is corresponding author: 

to contact call 573-882-8841 or email at ldhp54@missouri.edu.

ABSTRACT

Historic information indicates that eastern redcedar (Juniperus virginiana L.; ERC) was 

restricted to rocky bluffs and fire-protected areas throughout much of its range during the 

pre-Euro-American settlement period. As a consequence of settlement, dramatic changes 

occurred in land use, grazing, fire, and human populations, all of which coincided with 

a widespread increase in eastern redcedar’s distribution and density. To more closely 

identify the relative importance of these factors, we initiated a study addressing ERC 

demographics and growth in a relatively intact post oak (Quercus stellata Wangenh.) 

woodland complex within the Wichita Mountains National Wildlife Refuge (WMNWR) 

located in southwestern Oklahoma. Tree density, ages, and site information were 

measured in 353 plots distributed throughout a 14,000 hectare area comprised of plains, 

riparian zones, and rugged mountains. Preliminary analysis suggests a positive correlation 

exists between tree age and local topographic roughness and rocky soil substrate. Overall, 

younger trees (<100 years old) dominated the age distribution refuge wide. Expansion 

appeared to occur more widely in moderately rough terrain compared to the extremes 

found in grasslands (gentle) and peaks (very rough). In areas with more open forest 

canopy conditions (e.g., savannas, open woodlands), ERC appears to exhibit nurse tree 

characteristics, whereby younger ERC more commonly establish at the bases of older 

oak trees. Older ERC trees (200-500+ years old) occupy increasingly topographically 

rougher terrain. We hypothesize that topography was historically an important barrier 

with respect to limiting fire spread and that a topographic roughness index (in addition 

to other variables) could be used to delineate the historic spatial distribution of ERC that 

existed during the past few centuries when frequent burning was well documented in 

these woodlands. 

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
280 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

DENDROCHRONOLOGICAL DETERMINATON 

OF HISTORICAL FIRE OCCURENCE AND RECRUITMENT 

IN A SOUTHERN ILLINOIS OAK-HICKORY FOREST

J.M. Harris, Charles M. Ruffner, M. Therrell, and C.K. Nielsen

Graduate Student (JMS), Department of Forestry, Mailcode 4411, 

Southern Illinois University Carbondale, Carbondale, Illinois 62901; Associate Professor (CMR); 

Assistant Professor (MT); Assistant Professor (CKN). JMS is corresponding author: 

to contact, call 618-401-2295 or email at jeffrey.harris24@siu.edu.

ABSTRACT

Throughout the central hardwoods, fire return interval dramatically increased during 

the period of Euro-American settlement. Fire was used as a tool for clearing land and 

improving forage for grazing. The Shoal Creek study site is located in Jackson County, 

Illinois, 8 km southwest of Murphysboro. Shoal Creek is situated at the northern extent 

of the Illinois Ozark Hills, classified as a Subsection of the Ozark Highlands Section. 

The region is unglaciated, and loess caps are 10 m deep on the ridgetops and 1-3 m 

deep on side slopes. Preliminary results suggest the site was frequently burned during 

postsettlement, with a mean fire interval (MFI) of 2.95 years from 1887 to 1946. Fire 

waned from the site in the 1930s, and the last major fire occurred in 1946. By this 

time, Shawnee National Forest had become established in southern Illinois, and fire 

suppression was the preferred management technique. Thirty-three fire scarred cross 

sections were opportunistically sampled from trees on a southwest aspect of a QuercusCarya forest. Cross sections were sanded to 600 grit, and skeleton plots were used to 

determine signature years for cross-dating purposes. Year and seasonality of individual 

fire scars and approximate pith date were determined for each sample and were utilized 

in FHX2 fire history software. Recruitment history revealed that overstory QuercusCarya species established under favorable conditions in the early 20th century. Timber 

was harvested from the site around 1900, and intense fires followed for the next 30 

years. A small pulse of Acer-Fagus germinated as fire frequency decreased on-site 

during the 1930s, and a significant pulse established immediately after the last recorded 

fire in 1946. Superposed epoch analysis (SEA) determines the influence of immediate 

weather patterns and overall climate trends surrounding fire event years. SEA was run 

to compare fire event years at Shoal Creek with Palmer Drought Severity Index (PDSI) 

climate reconstructions. For the 95 percent confidence interval, there was not a significant 

association between fire and climate. In the central hardwoods, lightning is associated 

with rainstorms, and fires burn in both dry years and wet years, so the relationship 

between fire and climate is not strong. If rehabilitation of Quercus-Carya dominated 

forest stands is the management objective, the results of this study will aid in fire cycle 

planning of frequency and seasonality. Managers may consider the MFI for rehabilitation 

burns, and range of fire intervals for long-term maintenance burns. However, prescribed 

burns are not the only answer for managers. Fire must be used in accordance with 

silvicultural techniques that mimic natural disturbance regimes such as timber stand 

improvement (TSI) and shelterwood harvests which create large overstory gaps suitable 

for oak-hickory recruitment.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 281

OAK-GRASSLAND RESTORATION AT LAND BETWEEN THE LAKES 

NATIONAL RECREATION AREA: PRELIMINARY RESULTS

Jaime A. Hernandez and Elizabeth F. Danks

Forester (JAH), Land Between the Lakes National Recreation Area, U.S. Forest Service, 

100 Van Morgan Drive, Golden Pond, KY 42211; NEPA Editor/Wildlife Biologist (EFD). 

JAH is corresponding author: to contact, call 270-924-2073 or email at jahernandez@fs.fed.us.

ABSTRACT

Two areas totaling 8,630 acres within the Land Between the Lakes National Recreation 

Area (LBL) were designated as oak-grassland demonstration restoration areas in 2004. 

Dormant and growing season prescribed fires along with several thinning operations 

occurred between 2006 and 2010. Prescribed fire frequency ranged from one to three 

ignitions within this time period. We conducted a comparison between the changes in 

basal area, canopy cover, and the occurrence or composition of understory herbaceous 

cover within areas treated by one fire with areas burned more than once, and areas that 

were both burned and thinned. Burned and thinned areas were also compared by thinning 

regime: cut-and-leave versus commercial thinning. Over the last 4 years, we have already 

seen that the vegetation management programs at LBL have affected forest structure and 

composition. Prescribed burning has had an effect on understory composition, and to a 

lesser degree, midstory composition. However, any structural changes accomplished by 

just the use of prescribed burning were limited to the most xeric sites. The combination 

of prescribed burning and thinning treatments had an effect on both species and structural 

composition across all canopy levels, with all sites types with herbaceous development 

increasing as well. Oak-grassland structure has yet to be completely developed within 

the two sites; however, several of the areas have developed a woodland structure. In 

conjunction with further prescribed burns, this combination should provide the higher 

light levels that are key to sustaining an understory dominated by herbaceous species.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
282 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

THE EFFECTS OF PRESCRIBED BURNING ON THE BLACK KINGSNAKE: 

GOING BEYOND THE DEMOGRAPHIC DATA

Christopher A.F. Howey and Willem M. Roosenburg

Ph.D. Candidate (CAFH), Department of Ecology and Evolutionary Biology, Ohio University, 

Athens, OH 45701; Associate Professor (WMR). CAFH is corresponding author: 

to contact, call 609-413-5942 or email at chris.howey@gmail.com.

ABSTRACT

Species responses to habitat alteration are most frequently studied by estimating changes 

in population numbers. However, subtle changes in the habitat may cause indirect effects 

that go unnoticed in the short term yet can cause adverse population effects in the long 

term. Although demographics may be informative to reveal how snakes respond directly 

to habitat alterations, understanding how landscape changes may alter prey abundances, 

preferred microhabitat availability and use, predation intensity, and foraging strategy 

would assist biologists in knowing more of the collective effects caused by landscape 

alterations. The objective of this project was to determine how the black kingsnake 

(Lampropeltis getula nigra) is affected by changes to the landscape that are caused by 

prescribed burning. In the summer of 2010, I began this project at Land Between The 

Lakes National Recreational Area in southwestern Kentucky. I set up four study plots 

(each 800 m x 800 m; 64 ha) within the Franklin Creek Area burn unit (~960 ha in total 

size) and four study plots of equal size in an adjacent unburned habitat with similar 

topography. The Franklin Creek Area was burned in April 2007 and again in September 

2010. Drift fences with funnel and pitfall traps were erected in the center of each plot, 

and an array of coverboards were placed throughout each plot. During the summer of 

2010, a total of 848 reptiles, amphibians, and small mammals were captured, marked, and 

released. Reptile species richness and diversity indices (DI) were lower in burned plots 

(13 species, DI = 2.03) than in control plots (17 species, DI = 2.37). Biophysical copper 

models were deployed in each plot to measure the potential body temperatures a black 

kingsnake could achieve. Mean temperatures in burned plots were consistently warmer 

than in control plots and more frequently exceeded the critical thermal maximum of black 

kingsnakes (42 °C) suggesting that habitat in burned plots may become too warm for 

black kingsnakes, thus limiting the amount of time that they could be active (foraging 

for food or searching for a mate). Available habitat was measured within all plots prior to 

the second burn, and burn plots were characterized by fewer understory trees and higher 

ground temperatures. Burned plots also had higher air temperatures, a lower percentage 

of leaf litter, and shallower depths of leaf litter than control plots. The preferred body 

temperature (Tpref) was also measured for four captured kingsnakes in a thermal gradient 

arena, and mean Tpref was determined to be 28.2 ± 1.6 °C. Of these captured kingsnakes, 

one was large enough to have a radio-transmitter surgically implanted, and I am currently 

tracking this individual within a burned plot. This project is currently in the second of 

three field seasons.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 283

MULTIPLE BURNS PAVE THE WAY FOR IMPROVED OAK-HICKORY 

REGENERATION IN CANOPY GAPS IN SOUTHERN OHIO FORESTS

Todd F. Hutchinson, Elaine Kennedy Sutherland, Robert P. Long, 

Joanne Rebbeck, and Daniel A. Yaussy

Research Ecologist (TFH), Research Plant Physiologist (JR), and Research Forester (DAY), 

U.S. Forest Service, Northern Research Station, 359 Main Road, Delaware, OH 43015; 

Supervisory Research Biologist (EKS), U.S. Forest Service, Rocky Mountain Research Station; 

Research Plant Pathologist (RPL), U.S. Forest Service, Northern Research Station; 

TFH is corresponding author: to contact, call 740-368-0064 

or email at thutchinson@fs.fed.us.

ABSTRACT

In 1995, we began a study of prescribed fire as a tool to sustain mixed-oak forests. We 

hypothesized that repeated fires would reduce stand density “from below”, favoring the 

development of oak-hickory advance regeneration relative to the shade-tolerant species 

(e.g., red maple) that dominated the understory. Our study consisted of four 60 acre 

stands burned two to five times from 1996 to 2005, and two unburned stands, located in 

the Vinton Furnace Experimental Forest, OH. We collected overstory and regeneration 

data on a total of fifty-four 0.3 acre plots located across the full range of upland 

topographic moisture conditions in the six stands. Though fire reduced the density of 1-4” 

d.b.h. (diameter at breast height) saplings (-74 percent) and 4-10” d.b.h. midstory trees 

(-30 percent) on these permanent plots by 2008, canopy cover remained high (>85 

percent), and the relative abundance of oak-hickory advance regeneration was not 

significantly greater in burned vs. unburned plots. In 2003, canopy gaps formed in these 

same stands during a regional white oak decline. In 2008, we quantified understory 

structure and tree regeneration in 52 canopy gaps (separate from the permanent plots); 28 

gaps were in three stands burned three to five times and 24 gaps were in three unburned 

stands. Gaps were formed from the death of one to nine canopy trees (mean = 4). The 

understory structure of burned gaps was much more open than unburned gaps, which 

had a dense layer of saplings and midstory trees. Burned stands had significantly more 

oak-hickory advance regeneration in gaps (range 3,725 to 5,590 stems/ac) than did 

unburned stands (607 to 2,308 stems/ac); and oak-hickory dominated the larger advance 

regeneration layer (stems 1ft tall to 1 inch d.b.h.) in burned gaps. Sassafras advance 

regeneration was also more abundant in burned gaps while shade tolerant species and 

all other intolerant species were equally abundant in burned and unburned gaps. While 

fire alone did not clearly benefit oak-hickory regeneration in closed canopy forests, 

canopy gaps that formed after multiple burns became dominated by large oak-hickory 

regeneration. Our results suggest that, given enough time, repeated fires can increase the 

probability that oak and hickory will retain dominance after a canopy disturbance. 

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
284 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

ASSOCIATION OF FIRE SEASON, FIRE FRONT, 

AND FIRE TEMPERATURE ON THE MORTALITY OF 

EARLY SUCCESSIONAL PERSIMMON AND SWEETGUM TREES

Paul Killian, Joe Robb, and Darrin Rubino

Graduate Student (PK), Division of Biology, Kansas State University, 116 Ackert Hall, 

Manhattan, KS 66506; Refuge Manager (JR); Associate Professor (DR). 

PK is corresponding author: to contact, call 317-402-9904 or email at killianp@k-state.edu.

ABSTRACT

Land managers commonly treat grasslands with prescribed fire to decrease encroachment 

of woody vegetation and to maintain grassland biodiversity. The focus of our study was 

to assess the mortality of two early successional invaders, sweetgum and persimmon, 

in response to various fire regimes. We compared: (1) tree mortality between spring 

dormant-season (March-April) and fall growing-season (October) fires; and (2) the 

relationship between fire intensity and tree mortality. To examine these objectives, we 

sampled tree mortality from four burns between the fall of 2007 and the spring of 2009 at 

Big Oaks National Wildlife Refuge in southeastern Indiana. Our results suggested that the 

fire season, fire front, and fire temperature were all positively associated with mortality of 

these two early successional trees in a species-specific manner. 

High intensity fires associated with head fires, and spring dormant season fires had the 

greatest impact on the mortality of persimmon trees. However, fall growing season fires 

of either high intensity or long duration had the greatest impact on sweetgum trees. Full 

mortality of these trees was difficult to achieve due to prolific root and collar sprouting 

occurring shortly after the fires.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 285

POSTFIRE SUSCEPTIBILITY OF HABITATS TO INVASION BY SEED 

OF ORIENTAL BITTERSWEET

Stacey A. Leicht-Young, Noel B. Pavlovic, and Ralph Grundel

Botanist (SAL-Y), U.S. Geological Survey, Lake Michigan Ecological Research Station; 

Ecologist (NBP, RG), U.S. Geological Survey, Great Lakes Science Center, 

1100 North Mineral Springs Road, Porter, IN 46304. NBP is corresponding author: 

to contact, call 219-926-8336 ext. 428 or email at npavlovic@usgs.gov.

ABSTRACT

Prescribed fires are a common management tool in forested ecosystems. These fires help 

to maintain forest structure as well as species biodiversity. Fires also create disturbance 

which could allow for invasion of exotic species. Oriental bittersweet (Celastrus 

orbiculatus) is an exotic liana (woody vine) that is aggressively moving its way west 

from the eastern United States. This species is a major invader of forests and can 

disrupt natural succession. We set out to investigate if habitats that have been burned 

provide more conducive conditions for bittersweet germination than those that have 

not. We examined six different habitat types including sand prairie, moraine prairie, oak 

savanna, oak-hickory forest, beech-maple forest, and oak forest. In each habitat type 

we had replicated 6 x 6 m plots that were divided into four different treatments: high 

fire intensity, low fire intensity, litter removed, and a control. We burned these plots 

in either the spring (prairies and oak savannas) or fall (oak-hickory, beech-maple, and 

oak forest) dormant seasons. After the burns (April), we introduced 25 seeds of oriental 

bittersweet to each of the four treatments within the plot and monitored their germination 

and height monthly throughout the growing season (May-September). When examining 

the maximum number of seedlings per sampling period over the 2 years, the forested 

habitat plots (beech-maple and oak forest) had significantly greater percent germination 

than the open plots (prairie, savanna); however this comparison is confounded with 

year of sowing and differences in weather between years. Plots on moraine soils had 

greater overall percent germination than those on sandy soils. In the prairie and savanna 

habitats, the control had the highest percent germination, while the litter removed had the 

lowest. The high and low intensity fire treatments were not significantly different from 

the control nor the litter removed plot. In the oak and beech-maple forest habitats, the 

germination percentage in the control treatment was significantly lower than the low and 

high fire treatments. The litter removed treatment was not significantly different from the 

control or the two burn treatments. Thus, in some habitat types, fire could make the plant 

community more susceptible to invasion, while in others, it does not. This result is largely 

a function of how exposed the seeds become in the habitat in the absence of litter. In 

more open habitats (prairie and savanna) these seeds are exposed to more sun and do not 

germinate well, while in the forested plots, having less litter is conducive to germination 

since the canopy of the forest protects the seeds from excessive sun and heat. These 

results will assist land managers in making decisions when burning in forested areas with 

high amounts of oriental bittersweet.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
286 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

DETERMINING LUMBER VALUE CHANGES IN FIRE INJURED OAK TREES

Joseph M. Marschall, Richard P. Guyette, Michael C. Stambaugh, and John Dwyer

Research Specialist (JMM), Professor (RPG), Research Associate (MCS), 

Associate Professor (JD), Department of Forestry, University of Missouri-Columbia, 

203 ABNR Building, Columbia, Missouri 65211. JM is corresponding author: 

to contact, call 573-882-8841.

ABSTRACT

Prescribed fire is used for a variety of management tasks in woodlands with only limited 

information on how it affects lumber product values. We analyzed how fire related 

injuries affect lumber volume and grade in red oaks (Quercus coccinea and Q. velutina) 

harvested from two sites in southern Missouri. Trees (n=58) with varying degrees of 

external damage (scar size), time since fire, and log size were harvested and milled into 

dimensional lumber. Lumber grade and scale changes due to fire related injuries were 

tracked on individual boards (n=423; 4160 board feet). To estimate lumber product value 

losses, grade and scale changes were compared to an expected grade and scale as if no 

fire injuries were present. Preliminary analysis indicates tree size, scar size, and time 

since fire to be important predictors in decreased lumber product values, and minimal 

value loss occurs within the first 10 years after fire-caused injuries occur. Current field 

sampling has occurred on mid-quality woodland sites where lumber product quality is 

typically low. Future field sampling (approximately 30 additional trees) and analysis will 

target higher quality sites. 

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 287

ESTIMATING FUEL CONSUMPTION DURING PRESCRIBED FIRES 

IN ARKANSAS 

Virginia L. McDaniel, James M. Guldin, and Roger W. Perry

Forestry Technician (VLM), Supervisory Ecologist (JMG), and Research Wildlife Biologist (RWP), 

U.S. Forest Service, Southern Research Station, Hot Springs, AR 71901. 

VLM is corresponding author: to contact, call 501-623-1180 ext. 112 

or email at vmcdaniel@fs.fed.us.

Abstract

While prescribed fire is essential to maintaining numerous plant communities (especially 

those dominated by oak and pine), fine particles produced as smoke can impair human 

health and reduce visibility in scenic areas. As a result of these concerns, the Arkansas 

Voluntary Smoke Management Guidelines were established by the Arkansas Forestry 

Commission to mitigate the impact of smoke from prescribed fire on people’s health and 

to ensure adherence to air quality regulations. These guidelines use standard fire behavior 

and fuel models developed elsewhere in the United States. The accuracy of these models 

for determining fuel loading and consumption in Arkansas, however, is unknown. We 

established 120 modified Brown’s transects in 15 burn units and three community types 

on the Mena, Oden, and Poteau Ranger Districts of the Ouachita National Forest in 

Arkansas to determine fuel loads before and after prescribed fires. The three community 

types were pine-oak (Pinus echinata-Quercus spp.) forest, oak forest, and pine woodland. 

In addition to the ordinary Brown’s methodology of measuring litter and duff depth 

and tallying woody fuels, we also clipped attached vegetation and collected 1 and 10 

hour fuels in adjacent quadrats before and after the prescribed fires. This enabled us to 

estimate the live fuel component not sampled by Brown’s transects and test the accuracy 

of ordinary Brown’s transects in terms of woody fuel consumption. We used localized 

bulk density values to convert inches of litter and duff into tons per acre. We then used 

FFI (Fire Ecology Assessment Tool-Firemon Integrated) software to quantify fuel 

consumption on 7 of the 15 prescribed fires. Preliminary analyses showed that the fuel 

consumption occurring in the Ouachita Mountains was consistent with expected values 

based on standard fire behavior and fuel models (Table 1), and that fuel consumption in 

restored woodlands was significantly less than that in closed canopy forests (Fig. 1). 

Table 1.—Comparison of fuel consumption values predicted by standard fire 

behavior fuel models and Brown’s transect data collected on dormant season 

prescribed fires on the Ouachita National Forest in Arkansas, 2010 and 2011

Community Type Standard Fuel Model Actual Brown’s Transect Data*

tons/acre tons/acre

Pine-oak forest 3.0–4.4 3.0–5.4

Oak forest 0.8–2.5 2.0–3.8

Pine woodland 1.5–5.9 0–1.9

* Includes Brown’s transect data only (N = 32, 14, and 9 for pine-oak forest, oak forest, and pine woodland, 

respectively). 
288 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

Figure 1.—Overall fuel consumption in pine-oak forest, oak forest, and pine woodland using only 

Brown’s transect data on the Ouachita National Forest in Arkansas, 2010 and 2011. Different letters 

indicate a significant difference (p≤0.05, mean ±2se) among forest types.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.

0

1

2

3

4

5

6

Pine-Oak Forest Oak Forest Pine Woodland

a

a

b

Tons/acre
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 289

FIRE EFFECTS ON THE RESPROUTING AND TOTAL NONSTRUCTURAL

CARBOHYDRATES OF THE HIGHLY INVASIVE ORIENTAL BITTERSWEET

Noel B. Pavlovic, Stacey A. Leicht-Young, and Ralph Grundel

Ecologist (NBP), U.S. Geological Survey, Lake Michigan Ecological Research Station, 

1100 North Mineral Springs Rd., Porter, IN 46304; Botanist (SAL-Y); and Ecologist (RG). 

NBP is corresponding author: to contact, call 219-926-8336 ext. 428 

or email at npavlovic@usgs.gov.

ABSTRACT

An important evolutionary strategy for surviving fire is the ability to resprout. 

Resprouting ability is determined by resistance to burning, the location of meristems, 

and storage of special chemical reserves for regrowth. Total nonstructural carbohydrates 

(TNC) in the roots can be an important source of readily available reserves for rapid 

resprouting. Oriental bittersweet (Celastrus orbiculatus) is a highly invasive liana that 

is migrating westward across the central portion of North America. This aggressive 

liana can girdle trees, reach and cover forest canopies, increase tree susceptibility to 

ice damage, and alter successional trajectories. While it is known that this species can 

vigorously root sprout after a fire or from cutting, no quantitative study on this prolific 

resprouter has been done. We are conducting a replicated experiment on sand and 

moraine soil substrates to examine the effects of burning, cutting, and the combination 

of the two on resprouting and regrowth of Oriental bittersweet. We initiated eight 

experimental blocks with control, burn, cut, and cut and burn treatments in the spring and 

fall. Extreme weather prevented us from conducting growing season treatments (which 

were moved to the fall dormant season), so we added an additional cutting treatment in 

early July. Oriental bittersweet density and cover were measured in four 1 m2

 subplots 

in each treatment plot (10 × 10 m) with a pretreatment inventory done in July 2009 and 

a posttreatment remeasurement done in July 2010. Stems were classified into six size 

categories: seedlings; <2.5 mm in diameter; 2.5-5.0 mm; 5.1-10 mm; 10.1-15 mm; and 

>15 mm. We also collected three root segments of Oriental bittersweet from each plot in 

March, May, and July for TNC analysis. We used the differences in Oriental bittersweet 

cover, stem counts, and diameters as our response variables for the preliminary 

comparisons between 2009 and 2010. We found that burning and cutting plus burning 

reduced bittersweet cover more than just cutting and no treatment, but the reduction was 

less on the richer morainal soils than on sand. We found that the cut and burn treatment 

had significantly greater numbers of resprouts compared to the cut treatment (F2,1 = 2.1, 

P = 0.1). In addition, the number of resprouts increased with size class (F4,1 = 9.8, 

P < 0.001). When we examined the percentage of plants that were killed in each size 

class we found, as expected, that the largest size class had the most survival overall. 

The spring cut and burn had the most killed stems, but also had the highest number of 

resprouts. Seasonally, TNC declined from a peak in March to moderate levels in May and 

then increased by July. Cutting bittersweet in early July resulted in a 75 percent reduction 

in TNC compared to dormant TNC levels. Our results have important implications for 

developing effective strategies for controlling and eliminating Oriental bittersweet.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
290 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

CHANGES IN FOREST UNDERSTORY ASSOCIATED WITH REDCEDAR 

ENCROACHMENT IN FIRE SUPPRESSED QUERCUS STELLATA FORESTS

Paul van Els, Rodney E. Will, Michael W. Palmer, and Karen R. Hickman

Ph.D. student (PvE), University of Las Vegas; Associate Professor (REW), Department of Natural 

Resource Ecology and Management, Oklahoma State University, 008C Agricultural Hall, 

Stillwater, OK 74078; Professor (MWP, KRH), Oklahoma State University. 

REW is corresponding author: to contact, call 405-744-5444 or email at rodney.will@okstate.edu.

ABSTRACT

Fire suppression in oak woodlands of Oklahoma, Missouri, and Arkansas often leads 

to the establishment of a redcedar (Juniperus virginiana) midstory that alters species 

richness and understory productivity. In a Quercus stellata dominated forest in northern 

Oklahoma, we compared vegetation in forest gaps, forests without redcedar, at the inner 

and outer edge of redcedar canopies, and near trunks (200 plots total). Species richness 

(11 to 6 spp. m-2) and cover (53.3 to 12.7 percent) declined with proximity to redcedar 

trunks. Regression analysis indicated that richness (R2 = 0.08) and cover (R2 = 0.18) 

were best explained by redcedar litter mass. Partial canonical correspondence analysis 

revealed two strong canonical axes, one related to litter/light and the other to cover of 

Quercus spp. versus redcedar. Tree seedlings and woody vines dominated near redcedar. 

Forbs, graminoids, and Quercus spp. seedlings were more common in areas without 

redcedar. Our study indicates that litter is the main determinant of understory vegetation 

declines associated with midstory redcedar encroachment in these fire-suppressed forests. 

Decreases in herbaceous litter loads, which historically contributed to the accumulation 

of fuel beds, will have a positive feedback effect on midstory encroachment. Declines 

in recruitment of Quercus spp. that were related to increasing abundance of redcedar 

and consequent increases in litter loads eventually may lead to changes in overstory 

composition.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Proceedings of the 4th Fire in Eastern Oak Forests Conference GTR-NRS-P-102 291

FROM SPRING EPHEMERALS TO LIGHT TO FUNGI: PLANT DYNAMICS 

IN AN OZARK OAK/HICKORY-FOREST/WOODLAND COMMUNITY 

MANAGED FOR WILDLIFE THROUGH PRESCRIBED BURNS

D. Alexander Wait and Mary Ann Blinkhorn

Associate Professor (DAW), Missouri State University, Temple Hall 248, 901 South National Ave, 

Springfield, MO 65897; Graduate Assistant (MAB). DAW is corresponding author: 

to contact, call 417-836-5802 or email at alexanderwait@missouristate.edu.

ABSTRACT

This research examines the effects of prescribed fire on community structure and function 

in Ozark forests. The research aim is to inform decisions about future monitoring and 

management strategies for forests in southwest Missouri managed for wildlife, and more 

generally, to understand how heterogeneity in light through a canopy affects community 

and ecosystem function. Eighteen circular 0.1-ha plots have been established across three 

“treatments/habitats” at the Drury-Mincy Conservation Area (DMCA) in Taney County, 

MO. In addition, belt transects and 100 m2

 areas have been sampled in conjunction with 

circular plot sampling. Burning was prescribed on approximately 70 percent of closed 

forest at DMCA in 1999 with the goal of reestablishing open woodlands, with subsequent 

burns in 2001, 2003, 2008, and 2010. Prior to this, the closed forest areas had not burned 

in over 50 years. Small areas of DMCA have been burned since the early 1980s and are 

sampled as “reference sites”, while areas unburned for over 50 years are sampled as 

“control sites”. All prescribed burns have been conducted in March and April on the same 

forest areas. Fire is clearly opening the canopy and resulting in greater heterogeneity in 

photosynthetically active radiation reaching the forest floor. However, after 12 years, 

recently burned forests do not have significant oak regeneration, and plant community 

structure and function are still more typical of a closed forest than open woodland. 

We will present data on physiology of oak and hickory saplings, herbivory on oak 

saplings, soil respiration, leaf litter inputs, fungal abundance, overstory production, light 

penetration to understory, spring ephemeral diversity, and overall understory, midstory, 

and overstory plant species richness and cover. Finally, we will summarize interactions 

towards the goal of increasing our ability to predict plant and animal population dynamics 

and anticipate and minimize habitat degradation and pest species invasions in Ozark 

forests.

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
292 GTR-NRS-P-102 Proceedings of the 4th Fire in Eastern Oak Forests Conference

PRESCRIBED BURNING IN AN UPLAND OAK FOREST 

REDUCED LITTER N, SOIL ORGANIC C, AND GRAM NEGATIVE BACTERIA

Ryan J. Williams and Steve W. Hallgren

Graduate Research Assistant (RJW), Ecology, Evolution and Organismal Biology, 

Iowa State University, 3424 Oakland Street, Ames, IA 50014; Associate Professor (SWH), 

Oklahoma State University. RJW is corresponding author: to contact, call 515-450-6809 

or email at ryanw@iastate.edu.

ABSTRACT

Prescribed burning is a management technique used for reducing fuel loads, preventing 

exotic species invasion, and maintaining wildlife habitat. In upland oak (Quercus spp.) 

forests, prescribed burning prevents the process known as mesophication where the 

dominant canopy species shift from fire tolerant oaks to fire intolerant tree species. 

Recently, it has become increasingly important to manage forests from an ecosystem 

service perspective, especially for soil carbon storage. However, little data exists that 

explores the relationship between prescribed burning at different frequencies and forest 

soil properties. We assessed the effect of prescribed burning at 0, 2.5, and 5 fires per 

decade (FPD) on litter, soil, and the soil microbial community in an upland oak forest 

in central Oklahoma. Results indicated burn treatments had 26 percent lower litter total 

nitrogen, resulting in a higher C:N ratio (P = 0.0017 and P = 0.0039 respectively). The 

litter lignin:N ratio was lower under 0 FPD when compared to 2.5 FPD but was no 

different from 5 FPD (P = 0.019). Areas burned at 5 FPD had 2.5 times less soil organic 

matter (SOM) and 2.7 times less soil organic carbon (SOC) than other treatments 

(P = 0.0383). Carbon storage dropped from 36.0 Mg ha-1 at 0 FPD to 15.7 Mg ha-1 at 

5 FPD. Differences in SOM and SOC were associated with increased soil bulk density 

(P = 0.0039). Phospholipid fatty acid analysis (PLFA) indicated that gram-negative 

bacteria were significantly less abundant under 5 FPD (P = 0.0378). Differences in litter 

chemistry could cause heterogeneity in ecosystem functioning between forest areas with 

different fire histories, yet changes in litter chemistry did not reflect the differences that 

occurred in soil chemistry. Differences between the response of litter and soil to fire show 

an uncoupled nutrient cycling relationship between these two pools. Less litter N may 

limit the availability of N in soil pools after repeated burning over time as reflected by 

the C:N and lignin:N ratios. However, nitrogen limitation may not be as dramatic under 

5 FPD due to lower amounts of recalcitrant lignin in litter. The reduction in SOM and 

SOC could affect soil properties like cation exchange capacity and porosity, affecting the 

availability of nutrients and water in the soil. Shifts in the microbial community could 

occur because of the reduction of SOC or changes in other nutrients not measured in this 

study. Our sampling occurred long enough after burning (1.5 years) to indicate that shifts 

in the soil microbial community were due to the soil environment rather than the burning 

itself. It is unknown how this change in the soil microbial community will effect nutrient 

cycling, but it is evident that prescribed burning can alter the soil microbial community 

at a broad taxonomic level. The differences found in SOM, SOC, and gram-negative 

bacteria illustrate how burning at a high frequency may be destructive to SOM and SOC, 

while maintaining an intermediate burn frequency maintains a soil environment like that 

of an unburned forest. 

The content of this paper reflects the views of the author(s), who are 

responsible for the facts and accuracy of the information presented herein.
Printed on recycled paper

Dey, Daniel C.; Stambaugh, Michael C.; Clark, Stacy L.; Schweitzer, Callie J., eds. 

2012. Proceedings of the 4th fire in eastern oak forests conference; 2011 

May 17-19; Springfield, MO. Gen. Tech. Rep. NRS-P-102. Newtown Square, PA: 

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

292 p.

Contains 14 full-length papers and 40 abstracts of posters that were presented 

at the 4th Fire in Eastern Oak Forests conference, held in Springfield, MO, May 

17-19, 2011. The conference was attended by over 250 people from 65 different 

organizations and entities, representing 22 states and 1 Canadian province.

Key words: fire, eastern forests, forest management, oak 

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