Wendy GandyResource SpecialistTexas Forest Service

Fire Behavior and Land Management

Recommendations

• Identify Fire Behavior• Identify Fuel Types• Identify Mitigation Techniques

Objectives:

Fire Behavior

• Definition- The manner in which a fire reacts to the influences of fuel, weather, and topography.

Types of Fire Behavior

• Low Fire Behavior- Flame lengths < 4 ft. Fires can generally be attacked at the head or flanks by persons using machinery or hand tools. Control line should hold the fire.

Types of Fire Behavior• Moderate- Flame lengths of 4 – 8 ft. Equipment such as

dozers, pumpers, and retardant aircraft can be effective. Fires are potentially dangerous to personnel and equipment. Control lines may not contain the fire.

Types of Fire Behavior• High fire Behavior- Flame Lengths 8 – 11ft. Fires may present

serious control problems, i.e., torching, crowning, and spotting. Control efforts at the head will probably be ineffective.

Types of Fire Behavior• Extreme Fire Behavior- Flame lengths > 11 ft.

Crowning, spotting, and major fire runs are probable. Control efforts at head of fire are ineffective. A high rate of spread, prolific crowning and/or spotting, presence of fire whirls, strong convection column. Predictability is difficult because such fires often exercise some degree of influence on their environment and behave erratically.

Recognizing Problem Fire Behavior

• Wildfire is a greater threat during high temperature, low humidity days.Thresholds: RH < 30% Temps > 90*

• The greatest influencing factor on a wildfire is the wind.

Threshold: > 15 MPH

• Heavy fuel loads contribute to higher fire behavior.

Pine Plantations, Heavy Understory, Tall Cured Grasses.

Problem Fire Behavior

• Expect Rapid rates of spread when these thresholds are met.• Cured Grasses respond rapidly to changes in relative

humidity.• Pine Plantations can have tree torching or tree top crown

fires.

• Peak Fire Seasons: • Primary June through September with summer drying. • Secondary December through March with cured grasses

and wind events.

Fuel Types

• Grass• Shrub/ Brush• Pine Plantation• Mature Pine/Hardwood Mix• Slash/Cutover

Fuel Types - Grasses

FUEL MODELS DESCRIPTIONS

Fire Behavior Fuel Model 1Fire spread is governed by the fine, very porous, andcontinuous herbaceous fuels that have cured or arenearly cured.

Fires are surface fires that move rapidlythrough the cured grass and associated material.

Fuel Types - Grasses

Fuel Types - Pine Plantation

Fuel Types - Southern Rough

Fire Behavior Fuel Model 7Fires burn through the surface and shrub strata with equal ease and can occur at higher dead fuel moisture contents because of the flammability of live foliage and other live material. Stands of shrubs are generally between2 and 6 feet.

Fuel Arrangement

• Vertical• Horizontal• Ladder• Continuous

Vertical Fuels

Horizontal Fuels• Continuous grass fuel

Ladder Fuels

Wildfire Mitigation Methods :

• Mulching

Wildfire Mitigation Methods:

• Bulldozing

Wildfire Mitigation Methods

• Disking-10-15 ft. wideline.

Wildfire Mitigation MethodsMowing

• Mowing grasses adjacent to fuel or fire breaks to a height of 4 inches will enhance the effectiveness of breaks.

Wildfire MitigationFire Break Construction

• Fire lanes should be at least 10 ft. wide.• They should be

maintained and kept free of debris.• They should be

cleaned by disking or bulldozing.

Wildfire MitigationFire Break with Fuel Reduction

Shaded Fuel BreaksAlone they will not stop the fire.• These breaks are designed to break up the

continuity of the fuel. • The breaks will change the vertical, horizontal

and ladder fuels.• The break acts as a defensible landscape for firefighters.

Shaded Fuel Breaks

Guidelines:

1. Should be between 100-300 feet wide.2. Understory trees, underbrush and ladder fuel

removed.3. Mature trees lower limbs removed up to 10 ft.4. Crown Spacing between mature trees 10 ft. or

more.

Shaded Fuel Break

Before

After

Roads As Fuel Breaks

Roads can be used in conjunction with shaded fuel breaks. General recommendation is to clear undergrowth and thin smaller trees 150 ft. on each side.

Prescribed FireFuel Accumulation Burn• Prescribed fire is the most

practical way to reduce dangerous accumulations of combustible fuels under southern pine stands.

• Wildfires that burn into areas where fuels have been reduced by prescribed burning cause less damage and are much easier to control.

Jones Forest-Conroe, TX

Prescribed Fire• Texas Parks and Wildlife Department www.tpwd.state.tx.us• U.S.D.A. Natural Resources Conservation

Service www.tx.nrcs.usda.gov• The Nature Conservancy of Texas

http://nature.org/wherewework/northamerica/states/texas

• Texas Forest Service http://texasforestservice.tamu.edu

• U.S. Fish and Wildlife Service www.fws.gov/fire

• Texas Department of Agriculture www.agr.state.tx.us

(see Programs – Prescribed Burning Board)• Texas Commission on Environmental

Quality www.tceq.state.tx.us• For a list of prescribed burning

associations in Texas, visit the TPWD Web site at www.tpwd.state.tx.us/burnassociations

Prescribed Burn Associations

SOUTHTEXAS: Chaparral WMA in Dimmit andLa Salle counties. (830) 676-3413

CENTRAL TEXAS: Kerr WMA in Kerr County.(830) 238-4483

PANHANDLE: Matador WMA in Cottle County.(806) 492-3405

GULF COAST: J.D. Murphree WMA in JeffersonCounty. (409) 736-2551

Conclusion• Questions or Comments