23.240.418.12/98

FIRE REGIMES

A fi re regime is a description of fi re’s role in an 

ecosystem based on its frequency of occurrence, intensity, severity and size (Heinselman, 

1973). Fire regimes are sorted into broad categories ranging from frequent, non-lethal fi res 

to infrequent, stand-replacing fi res. More than 

one type of fi re may occur within a vegetation type. For example a lodgepole pine stand 

that experiences non-lethal surface fi res about 

every 30 years, may experience a high intensity, severe fi re approximately every 150 years. 

Listed below are general fi re regimes for local 

vegetation, based on studies done for common types in Utah. The numbers represent the 

average frequency for each type of fi re, nonlethal to stand-replacing, occurring in the vegetation type. The values are for fi res that historically occurred, before the advent of European 

settlement and fi re suppression. 

OAKBRUSH - 10-30 years, 

stand replacing

SAGE/GRASS - 15-30 years, 

short return interval crown/

severe surface fi res

PONDEROSA PINE - 6-20 

years, infrequent light surface fi res

DOUGLAS FIR - 15-150 years, 

mixed fi re regime, non-lethal to stand replacement

JUNIPER - 15-50 years, stand 

replacement

LODGEPOLE PINE - 30-150 years, mixed fi re 

regime, infrequent non-lethal fi res to stand 

replacement

ASPEN - 70-200 years, stand 

replacement

SPRUCE-FIR - 250-300 years, 

long return interval crown fi res 

and severe surface fi res

––––––––––––

Fire regime information based on – Heinselman, M.L. 1973. Fire in the virgin forests 

of the Boundary Waters Canoe Area, 

Minnesota. Quat. Res. 3:329-82.

Oak roots 

survived a 

stand-replacing fi re 

to sprout 

new growth 

just six 

weeks later.

Even a stand-replacing fi re leaves islands of unburned vegetation that 

creates a mosaic of age classes as the burned areas regenerate.

Prescription

for a Healthy 

Environment

F I R E T E R M S 

WILDLAND FIRE SUPPRESSION - An appropriate management response 

to wildland fi re that results in curtailment of fi re spread and eliminates all 

identifi ed threats from the particular fi re. All wildland fi re suppression activities 

provide for fi refi ghter and public safety as the highest consideration, but 

minimize loss of resource values, economic expenditures, and/or the use of 

critical fi refi ghting resources.

WILDLAND FIRE USE - The management of naturally ignited wildland fi res 

to accomplish specifi c prestated resource management objectives in 

predefi ned geographic areas outlines in FMP’s. 

WILDLAND FIRE MANAGEMENT PROGRAM - The full range of activities and 

functions necessary for planning, preparedness, emergency suppression 

operations, and emergency rehabilitation of wildland fi res, and prescribed 

fi re operations, including nonactivity fuels management to reduce risks to 

public safety and to restore and sustain ecosystem health.

PRESCRIPTION - Measurable criteria that defi ne conditions under which a 

prescribed fi re may be ignited, guide selection of appropriate management 

responses, and indicate other required actions. Prescription criteria may 

include safety, economic, public health, environmental, geographic, 

administrative, social, or legal considerations.

PRESCRIBED FIRE - Any fi re ignited by management actions to meet specifi c 

objectives. A written, approved prescribed fi re plan must exist, and NEPA 

requirements must be met, prior to ignition. This term replaces management 

ignited prescribed fi re.

APPROPRIATE MANAGEMENT RESPONSE - Specifi c actions taken in response 

to a wildland fi re to implement protection and fi re use objectives.

INITIAL ATTACK - An aggressive suppression action consistent with fi refi ghter 

and public safety and values to be protected.

WILDFIRE - An unwanted wildland fi re.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis 

of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital 

or family status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative 

means for communication of program information (braille, large print, audiotape, etc.) should contact USDA’s 

TARGET Center at 202-720-2600 (voice and TDD).

To fi le a complaint of discrimination, write USDA, Director, Offi ce of Civil Rights, Room 326-W, Whitten Building, 

14th and Independence Avenue, SW, Washington, DC 20250-9410 or call (202) 720-5964 (voice or TDD). USDA is 

an equal opportunity provider and employer.

United States Department of Agriculture

Forest Service

Intermountain Region

Uinta and Wasatch-Cache National Forests
Prescription for a

Healthy Environment

F

or thousands of years, natural fires have 

played a major role in grassland, brush 

and forest ecosystems for as long as 

they have existed. Many ecosystems have 

evolved with fire and depend on it for renewal. 

A burned area may seem devoid of life, but 

many species survive, giving rise to a new for-

est. Fire also creates openings in the forest. 

Sunlight penetrates these gaps, warming the 

soil and stimulating new growth from seeds 

and roots.

Over time, periodic fires create a vegetation 

mosaic of different ages and types. This pro-

vides a rich variety of habitats that supports 

many species of insects, mammals, and birds. 

This diversity indicates a thriving ecosystem.

The science of ecology tells us that natural fire 

is an essential part of nature. Humans have at-

tempted to exclude all types of fire, not distin-

guishing between natural and human-caused 

fire.

In many of our wildlands fire specialists have 

grappled with the issue of fire for over 100 

years. An for most of that time society has 

viewed fire as a destructive force.

The result of a century of extensive fire sup-

pression, coupled with the growth in urban 

wildland areas, has caused a fire environ-

ment prone to catastrophic fire. To deal with 

this issue, the Forest Service is restoring fire into 

ecosystems.

Lightningcaused 

fires are an 

important 

part of 

forest 

ecosystems. 

Without 

these 

periodic 

fires to 

recycle 

forest 

debris, and 

regenerate 

new growth, 

fuels build 

up and 

unnatural 

catastrophic 

fires may 

occur.

Can you tell how 

many years ago 

this aspen stand 

burned? Aspen 

are able to renew 

themselves after 

a fire by sprout-

ing from their 

unburned roots. 

This aspen forest 

is sprouting a new 

aspen forest just 

one year after it 

burned.

Wildlife may 

move into 

a burned 

area before 

the smoke 

clears. Burns 

provide a 

variety of 

habitat for 

wildlife by 

rejuvenated 

vegetation.

What is the best way to restore fire? In some 

areas of the forests we simply let nature take 

its course. In some predetermined areas, when 

lightning strikes and starts a fire, the fire would 

be monitored and trained specialists would de-

cide when, where, and under what limits a fire 

would be permitted to burn. Another solution 

is prescribed burning. Fire management, along 

with wildlife, timber and other resource special-

ists, plan, and ignite fires in areas when they are 

in prescription. Fire can play its role in the forests 

safely and provide for:

RECYCLING OF NUTRIENTS

 RESTORING AND REGULATING PLANT 

SUCCESSION AND WILDLIFE HABITAT

 MAINTAINING BIOLOGICAL 

 DIVERSITY

 REDUCING HAZARDOUS FUEL, THUS 

DECREASING FIRE DANGER

 CONTROLLING INSECTS AND DISEASE 

POPULATIONS

Some fire must always be extinguished that 

threaten people, property and rare natural 

resources. Careful planning, using fire as a 

management tool, and increasing education 

and awareness will provide an environment for 

healthy forests. For years, the accepted story 

about fire was that it destroyed the landscape. 

The reality is, fire is essential to forest health. Re-

search shows that many ecosystems depend on 

fire to renew the ecosystems by releasing nutri-

ents and stimulating new life. In time, fire creats 

a healthy diversity of plant and wildlife species, 

which benefits the public and the land.

Frequent understory burns historically 

cleansed ponderosa pine and Douglas fir 

forests of dead and down fuel, preventing 

catastrophic fires.