Fire Ecology in the Southeastern United States

U.S. Department of the Interior

U.S. Geological Survey

USGS FS-018-00

June 2000

For more information, contact:

U.S. Geological Survey/National Wetlands Research Center,

700 Cajundome Blvd., Lafayette, LA 70506; 337-266-8500;

Fax: 337-266-8513; http://www.nwrc.usgs.gov

Fire, whether naturally occurring or prescribed, has a vital function in the ecosystem. Fires,

such as the one shown here at Kisatchie National Forest, eliminate dead or dying plant matter,

stimulate growth of native plants, and suppress the invasion of exotic species and the

succession to woody species in many natural plant communities.

habitats. It also reduces the invasion of

exotic species and the succession to woody

species in pitcher plant bogs, pine savannas, coastal prairies, marshes, and other

natural plant communities of the southeastern United States.

Today we use fire as a management tool

to maintain and restore the ecological

structure of natural plant and animal

communities. We study the effects of fire

on native species to better understand the

influence fire has on the structure of their

communities and ecosystems.

Historically, human influences have

dramatically altered fire effects on the

North American landscape. Native

Americans used fire to change vegetation

patterns prior to European colonization.

Following European settlement, fire

became viewed as a natural force that

should be controlled. Throughout much of

Historically, fires destructive force has been viewed

as an enemy of both humans and native species.

Fire has played an important role in the

structure of natural ecosystems throughout

North America. As a natural process, fire

helps clear away dead and dying plant

matter and increases the production of

native species that occur in fire prone
our Nations history, fire has been aggressively suppressed in wildland areas to

protect both public and private interests

and prevent what was viewed as the

destruction of grasslands, forests, and other

ecosystems.

Tremendous resources have been

expended in attempts to prevent and

control wildland fire. Yet despite these

massive suppression efforts, the potential

for catastrophic wildfire continues to

threaten millions of acres of Americas

wilderness.

The new Federal Wildland Fire Policy

recognizes that past practices of aggressive

fire suppression have led to conditions of

historically unprecedented fuel loads, or

on the role of fire on the southeastern

Coastal Plain.

Fire on the Coastal Plain. NWRC

scientists are comparing the effects of fire

in pine flatwoods and savannas by season

in northeastern Florida. While traditional

fire managers have used fall and winter

burns in the belief that less harm would

result while the trees were dormant, most

natural fires tend to occur in spring and

summer as the result of lightning strikes.

This study seeks to determine whether the

intensity or seasonality of fire is more

important for a healthy forest system.

Fire and Prairie Restoration. The coastal

prairie of Louisiana and Texas is one of the

Southeasts most endangered ecosystems,

with more than

99% of its

historical range

lost to human

activities.

Restoration and

conservation

efforts are now

being focused

on protecting

what is left in

order to

preserve this

ecosystems

diversity of

native plants

and wildlife, including two endangered

bird species.

Before the area became settled, fire was

a sustaining force on the coastal prairie.

Fires set by lightning fed on the dormant

grasses and kept trees in check, while the

roots and bulbs of the native prairie plants

remained unaffected by fire at the surface.

Fire suppression practices, grazing and

mowing, and fragmentation of the prairie

landscape through agriculture and urban

sprawl have all but eliminated wildfire as a

dominant factor in the modern coastal

prairie ecosystem, however.

Since wildfire historically played a

significant part in maintaining the prairie

ecosystem, one aspect of management of

the coastal prairie is concerned with

studying the effectiveness of prescribed

fire for controlling invading species and

restoring the natural biodiversity of this

highly endangered ecosystem by promoting growth of native plants, reducing fuel

for wildfires, and regulating prairie

productivity.

One of the most invasive exotic species

in the coastal prairie is Chinese tallow

(Sapium sebiferum). Chinese tallow resists

both flooding and drought and also, to

some degree, fire. Tallow does not burn

easily and, because they shade out native

grasses that do burn, tallow stands act as

natural fire suppressants. Because of this,

and also because they are highly invasive

and quickly dominate an area once they

have entered it, Chinese tallow trees are

USGS researcher assisting in a prescribed burn at the Kisatchie National Forest.

Prescribed fire is now a primary tool in land management and restoration efforts.

burnable plant materials, in many of our

Nations natural areas. This policy calls

for the reintroduction of fire on an ecologically significant scale as a one of the tools

for public land management. Reintroduction of prescribed fire as a land management tool is a proactive means of reducing

the threat posed by wildland fire to both

people and property.

For the reintroduction of fire to be

ecologically effective, though, it must be

based on the best available science.

Researchers at the U.S. Geological

Surveys National Wetlands Research

Center are participating in the effort to

better understand the role fires play in

natural systems and the effects of fire and

fire exclusion on certain species. Fire

research at the NWRC focuses primarily

Prescribed fire on coastal prairie at the Brazoria National Wildlife Refuge. Before

the coastal prairie became settled, fire was a sustaining force in the ecosystem.

Low-intensity natural fire kept woody growth in check, yet the roots and bulbs

of the native grasses remained undamaged. Fire suppression practices allow

the accumulation of plant litter and other flammable materials and therefore

increase the likelihood of a destructive, high-intensity wildfire.

considered a

significant threat to

the coastal prairie

and elsewhere.

NWRC scientists

have been experimenting since 1996

with controlled

burns in both the

dormant season and

the growth season to

study the effects of

timing of burns on

Chinese tallow

stands. Evidence so

far indicates that

burns conducted

during the growth

season are more

effective in the long

term than traditional

dormant-season
specialized plants such as pitcher plants

and orchids.

Many of the plant species that make up

the wet pine savanna habitat for the cranes

are fire dependent, that is, they need fire to

continue to reproduce. Some savanna

grasses need fire before they will flower.

NWRC scientists are studying the effect of

prescribed burning on native species such

as pitcher plants and wiregrass. In

addition, NWRC scientists are studying the

impacts of prescribed fire on the reduction

burns, and that prescribed fire may indeed

be a key in holding Chinese tallow at bay.

The Role of Fire in the Restoration of Wet

Pine Savannas. NWRC ecologists are

working with the Mississippi Sandhill

Crane National Wildlife Refuge (NWR) to

use prescribed burning to restore habitat

used by the endangered Mississippi

sandhill crane. The Mississippi sandhill

crane (Grus canadensis pulla) is a

critically endangered subspecies found

nowhere else on earth in the wild but on

and adjacent to the Mississippi Sandhill

Crane NWR. Cranes use the open wet

pine savannas for loafing, nesting, and

roosting.

 Historically, fire was a naturally

occurring phenomenon in the wet pine

savannas, shaping the appearance of the

landscape by burning off grasses, shrubs,

and pine litter frequently. Fire suppression

has interfered with this natural process,

allowing woody plants such as trees and

shrubs to invade and shade out native sunloving herbs in these plant communities.

Wet pine savannas have been shown to

contain the highest diversity of plant

species per square meter than any other

plant community throughout the southeastern United States. Frequently burned wet

pine savannas are dominated by a variety

of grasses, herbs, and sedges. In addition,

wet pine savannas are host to more

of exotic species and the encroachment of

woody vegetation that is degrading

existing potential wet pine savanna habitat

to be used by cranes.

Response of overwintering birds to

prescribed burning in wet pine savannas of

the Mississippi Sandhill Crane NWR. The

NWRC recently supported a study

conducted by Georgia Southern University

and the Mississippi Sandhill Crane NWR

of the responses of overwintering birds to

prescribed burning. Evidence indicates

that prescribed burning during the growing

season may benefit native forbs and

grasses of pine savannas, which are

important habitat for overwintering

migratory grassland birds. Besides

Mississippi sandhill cranes, wading birds

visit the bayou in this refuge, and many

songbirds, including the eastern bluebird

(Sialia sialis) and Henslows sparrow

(Ammodramus henslowii), frequent the

savannas.

Fire detection and fire danger monitoring

with a satellite system. Direct assessment

of the effects of fire on a region often is

constrained by time, personnel, and cost.

To decrease reliance on direct assessment

methods and add to the little information

that currently exists regarding the effects

of fire on marsh ecosystems, the NWRC is

helping to develop remote sensing

techniques for detecting evidence of

wildland fires and for monitoring fire

extent and intensity and resource recovery

or change, with an emphasis on coastal

ecosystems. Researchers seek to determine which current and future remote

sensing tools address the needs of resource

managers dealing with fire management.

Studies at various sites

in Florida and Louisiana have assessed the

value of such remote

sensing tools as

satellites and polarized

radar in monitoring

marsh burn recovery.

One such project has

taken place over a 3-

year period at St. Marks

National Wildlife

Refuge (NWR) in

Florida in a black

needlerush (Juncus

Chinese tallow being burned by winter fire. At the Mississippi Sandhill Crane National Wildlife

Refuge, fire is mainly applied in the fall and in the

spring. Fall fire reduces overstocked planted slash

pine and enhances crane nesting areas, while spring

fire clears unwanted woody vegetation from

overgrown areas on the savannas.

This color infrared photograph of a burned black needlerush marsh at the

St. Marks National Wildlife Refuge shows a high contrast between the

burned (black area) and nonburned surrounding marsh.

roemerianus) coastal

saltmarsh. Black
needlerush is a

dominant vegetation in

most marshes on the

northeast gulf coast.

Canopy reflectance

spectra and canopy

light penetration

measurements, taken

with multipolarmetric

radar, were examined

as tools for monitoring

long-term burn

recovery at this site.

Another study used

various optical

instruments and

satellite data to detect

and monitor short-term

burn recovery in an

area of pine savanna in

Florida.

At another study

site, a freshwater

coastal marsh in

Louisiana, short-term

burn history maps were

generated using

Thematic Mapper

imagery. These maps

cover winter preburn,

eastern Coastal Plain. The research in the

NWRC project seeks to collect data that

can be used to modify the current fire

modeling system to more accurately

predict fire behavior related to the ecosystems of the Southeast.

Studies of the 1998 Florida Wildfires. In

the fall of 1998, an interagency research

team was formed under the leadership of

NWRC and U.S. Forest Service scientists

to evaluate the ecological effects and

economic ramifications of the 1998 Florida

wildfires. These fires, while catastrophic,

provided a rare opportunity to study

extreme fire behavior in natural and human

ecosystems in Florida.

The 1998 Florida wildfires were the

culmination of a combination of natural

though extreme conditions. Unseasonably

warm weather and copious rainfall during

the winter of 1997-98 resulted in more

plant growth than usual while limiting the

use of prescribed fire to reduce the hazard

of wildfires. Record-breaking rainfall

turned to recordbreaking drought

conditions in the spring

of 1998, again restricting the use of prescribed fire to reduce

potential hazards.

Lightning activity

picked up in May of

1998 but without the

usual attendant rains.

The end result of these

events was a series of

over 1,700 highintensity, very destructive wildfires that

ranked as one of

Floridas worst disasters.

 The interagency

team made up of

federal, state, private,

and academic institutions was formed with

support from the Joint

Fire Science Board to

study nine ecological

and economical impacts

of the wildfires. This

ate impacts of catastrophic wildfires.

NWRC scientists are assessing the status

and the post-fire response of known

populations of plant species of special

concern in areas burned by the wildfires.

NWRC scientists are also collecting

information on the extreme fire behavior

presented by the wildfires. The computer

model BEHAVE is being used to compare

actual and predicted behavior of the

wildfires to determine if models are

adequate under extreme conditions. In

addition, other agencies are studying insect

response, economic impacts, forest

structure changes, and assessing home

protection strategies following the wildfires. The results of this interagency

teams efforts will provide vital data to

land use and forest managers, home

owners, policy makers and other researchers towards future planning to protect

against such catastrophic wildfires in the

future.

project will create a

post-fire data base that

will provide information about the immedispring recovery, and

summer regrowth of

the marsh over a 1-year period.

Fire modeling for fire management.

Prescribed fire is a central element of the

new Federal Wildland Fire Policy, but for

it to be an ecologically useful management

tool, land managers need to know how fire

will react in specific ecosystems. Ecosystem modelers at the NWRC are working to

create improved fire behavior models that

will more accurately predict fire behavior

related to the vegetation and conditions of

the marshes, wet pine flatwoods and

savannas, and coastal prairie systems of

the Southeast. These models will be

extremely helpful tools in conducting

prescribed burns.

To conduct a prescribed burn, land

managers or researchers must first compare habitat conditions of the area to be

burned to the expected behavior of the fire

predicted with a fire modeling system. The

current fire modeling system, however,

often does not reflect the vegetation and

fire conditions encountered on the southAlthough catastrophic fires like the ones in Florida in 1998 may have devastating impacts on

timber resources, they may also prove to have ecological benefits. This photo shows

catastrophic fire where torching and crowning are common.