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Wendy Gandy Resource Specialist Texas Forest Service. Fire Behavior and Land Management Recommendations. Objectives:. Identify Fire Behavior Identify Fuel Types Identify Mitigation Techniques. Fire Behavior .
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Objectives: • Identify Fire Behavior • Identify Fuel Types • Identify Mitigation Techniques
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 1 Fire spread is governed by the fine, very porous, and continuous herbaceous fuels that have cured or are nearly cured. Fires are surface fires that move rapidly through the cured grass and associated material.
Fuel Types - Southern Rough Fire Behavior Fuel Model 7 Fires 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 between 2 and 6 feet.
Fuel Arrangement • Vertical • Horizontal • Ladder • Continuous
Horizontal Fuels • Continuous grass fuel
Wildfire Mitigation Methods : • Mulching
Wildfire Mitigation Methods: • Bulldozing
Wildfire Mitigation Methods • Disking- 10-15 ft. wide line.
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.
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: • Should be between 100-300 feet wide. • Understory trees, underbrush and ladder fuel removed. • Mature trees lower limbs removed up to 10 ft. • 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 Fire Fuel 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 and La 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 Jefferson County. (409) 736-2551
Conclusion • Questions or Comments
