FIRE & THE FORESTForestry Revision TeamMay 2007

The Fire TriangleTo produce fire, three things must be present at the same time-

FUELHEATOXYGEN

The Fire TriangleThe fire triangle is like a three-legged stool. If you remove one leg, the fire goes out. fuelheatoxygen

How is the triangle broken?Some of the ways used to break the fire triangle are:fire rakefire flap or pine topbackpack water pumptractor with a fire plowbackfire torchairplane water bombprescribed burning

What is fire behavior?

When we talk about fire behavior, we are thinking in terms of the intensity of the fire itself, and the rate of spread or speed of the fire.

What determines fire behavior?Fire behavior is affected by a wide range of conditions.Three important factors:Time of occurrence of the fire seasonair movementstopography (slope of the land, presence of roads, fields, streams, etc.)

TERMSWildfirethe uncontrolled burning of fire

Incendiarythe unlawful & intentional setting of fire

Debris burningburning of trash

Preventionany action associated with stopping a wildfire before it is started

Pre-suppressionany action associated with being ready in case a wildfire occurs

Suppressionany action associated with stopping a wildfire

Prescribed burningthe controlled use of fire.

Originwhere a fire starts

Perimeterthe outmost area of the blaze including the head, flank & rear

Relative humiditythe amount of moisture in the air

Alidadean instrument used in locating fires

Buildup indexa rating of the cumulative effect of drying since a rain of 1/10 or more; indicative of the intensity with which a fire can burn. Scale 1-100

Spread indexa relative rating of the forward movement of a fire; rated on a scale of 1-100

Wind velocitythe speed of the wind measured in miles per hour

Psychrometeran instrument that measures temperature & relative humidity

Heavy fuelscontains a high percentage of thick material such as logs, large limb & tree tops

Medium fuelscontains light materials such as limbs & tree tops less than 4 in diameter

Light fuelsgrass, leaves, small limbs & twigs

Duffforest litter & other organic debris in various stages of decomposition on top of the mineral soil

Igniteto burn or burst into flames

Mortalitydeath or destruction of forests due to fires

Fire Seasonthe period of the year which fires are likely to occur

Mixing heightheight the smoke mixes with the wind, should be at least 1500 feet

Transport wind speedspeed of the wind at mixing height, should be at least 9 mph

Effects of WildfiresDestroy or reduce value of standing timber

Destroy young seedlings

3. Reduce the growth rate

4. Reduce the water holding capacity of watershed & cause erosion

Pollute local streams & ponds

Kill or injure wildlife as well as the habitat

Encourage insects & disease in the stand

Can effect local & state economy

Causes of Wildfires65% of fires caused by:40% escaped debris burning fires25% woods arson

Average size wildfire in the Southeast is 19 acres per fire

Ga. Average wildfire is 4.7 acres

Requirements for a FireFuel-wood or other plant material

Oxygen-air is the main supply

Heat Source-sparks, lightning, cigarettesA fire is like a 3-legged stool, remove one leg & the fire goes out

Types of Forest FiresGround Firefires that burn the organic materials beneath the surface litter of the forest floor

Surface Firefires that burn surface litter of loose debris on the forest floor & small vegetation

Crown Firesfires that burn from top to top of trees or shrubs

Georgia Forestry Fire LawsCriminal Damage to property in the first degreeKnowingly & without authority interferes with any property in a manner so as to endanger human lifePunishment of not less than 1 or more than 10 years

Criminal Damage to property in the second degreeIntentionally damages any property of another person without his consent & the damage exceeds $100

Punishment of imprisonment of not less than 1 or more than 5 years

Criminal TrespassIntentionally damaging property of another without his consent & damage is less than $100

Punishment is a misdemeanor

Use of fires & ignited objectsIt shall be unlawful:Start or cause a fire on any woodland not ones own or leased without owners permissionBurn without taking necessary precautions to prevent the escape of the fireCause a fire by discarding any burning objectDestroy or damage any material or device used in detection or suppression of wildfires

Notice of intention to burn LawCounty forestry unit must be notified of time & location before setting fire to any combustible materialsViolation is a misdemeanorMust obtain a permit before burning

Fire BehaviorFire is affected by a wide range of conditionsAir movement-both horizontal & vertical movement of air as well as wind speedFire season-for Georgia is fall & spring of the yearTopography-slope of an area affects the rate of a fire, generally the steeper the slope the faster the fire

Weather conditions that reduce the rate of spreadRain on the fire

Wind reversal

Increases in relative humidity

Types of fuelsThe two basic fuel types are:

Ground fuels-fuels found on the surface of the soil

Aerial fuels-fuels include all burnable materials located in the canopies above 6 feet from the ground

Fire ControlDivided into 3 main headingsPreventionthings done to prevent a fire from happeningPresuppressionthings done to be prepared when a fire does occurSuppressionthings done to stop a fire once it has begun

PreventionThe most effective & least expensive method of controlPrevention Measures include:Clear all fuel back several feet from trash, camp or warming firesNever leave fires unattendedHave suppression tools & methods availableKeep fires small

Avoid burning during dry spells, windy days or when RH is low

Maintain fire equipment in safe running condition

Extinguish all matches & smokes before discarding

Use prescribed fires to reduce or eliminate fuel

MethodsBe familiar with the property & the best way to get equipment to each area under all conditionsLocate firebreaks & keep them maintainedPre-suppression: Preparations made before a fire starts to more effectively control it.

3. Know your neighbors & ask them to report you on any unusual smoke in your area

4. Keep your fire fighting equipment in a handy, known location

5. Know how to contact the County Forest Ranger;

Suppression: action necessary to extinguish a fire after it has started.Basic jobs of fire suppression:Rob the fire of fuel

Reduce the fires temperature

Cut off the oxygen from the fire.

Major parts of a FireHead: the portion of the fire toward which the air is moving; the fastest moving part of a fire

Rear: the portion of the fire which air is moving away; slowest part of a fire

Flank: the sides of the fire

Methods of attack in suppressing a fireDirect: fighting the fire at the head of the flames. Used when the flames are not too intense & moving slowly.

Indirect: Used where heat & rate of spread will not permit a direct attack

Additional control methodsMop-up: making sure that all fire & smoking material is out or safe inside the fire breaks.

Patrol: Periodic inspections made over the area until the fire is dead out

Beneficial Uses of FireHazard Reduction-Reducing the forest litter & undergrowth

Hardwood Control-Hardwoods under 2 dbh can be controlled with fire. Summer burns give the best results

Site Preparation-the most economical tool to provide conditions for re-establishment of forests. Reduces competition & provides suitable seedbed.

Wildlife Habitat-Reduces predator cover, exposes hidden seeds & produces fresh low browse for wildlife.

Disease control-Only practical method of controlling Brown Spot Needle Blight. Burns away infected needles without killing the well protected bud. Litter reduction seems to reduce the incidence of Annosus Root Rot. No know control for this disease once established.

Improved Accessibility-Improves accessibility & visibility for marking & cruising timber. Also helps for harvesting operations. Can improve recreational & aesthetic values.

Prescribed (Prescription) BurningThe controlled use of fire in the forest to accomplish specific purposes

Most economical tool used for cleaning operations in young pine stands

Can be used for less than $3 per acre.

Should only be done by persons trained in its use.

Conditions to consider prior to prescribed burningRelative humidity

Temperature

Wind, velocity & direction

Fuel moisture

Fuel ConditionsRefer to the amount & arrangement of the fuel, along with the desired intensity of the fire.

A continuous litter of needles or grass is usually needed

On well-stocked pine sites, fuels reach critical levels in about 5 years.

Low growing shrubs with pine straw can cause a level of aerial fuels which can create a great level of heat & should be considered when burning

Weather FactorsTemperature20 to 60 degrees is the ideal range for winter burning; Hardwood control or site prep is often best accomplished in the summer with temperatures of 80 degrees or above.

WindSteady at 2-10 mph northerly is best. Steady wind direction & speed are vital for good burning.

Relative Humidity30to 50% is the best range. A 20 degree rise in temperature can reduce the RH by half.

Rainfallone half to one inch, one week before burning is recommended. For most prescribed burns the upper litter layer should be dry to the touch.

Season of the YearWinter burnsoffer the advantage of less stand damage, more predictable weather & steady winds

Summer burnsoffer hotter fires to burn more of the rough for seed bed & site preparation

Time of DayDay time fires offer better weather conditions. Burns should start about 10 a.m. & stopped so to burn out by night.

Night fires have problems with light winds & higher humidity

Types of FiresHead fire

Backfire

Strip Head Fire

Flank Fire

Head FireFires moving in the same direction of the wind.

Generate the most heat & travel at the fastest rate.

Good fire for site prep fires

BackfireFire moving in the opposite direction to the wind. (Burning into the wind)

Steady 4-10 mph wind

Generally burn at 100 feet per hour

Well suited for sapling size stands & plantations 15 or more in height

Strip Head FireUsed in conjunction with backfires

Only 75-100 wide

Winds should be 2-5 mph

Used to burn large areas much faster

Flank FireA supplemental burning technique

A fire set into the wind that burns at right angles to the wind

Used to even up backfires & strip head fires

Burning IntervalThe amount of time between burns

Usually every 2-5 years

Dependent on available fuel

Planning a Prescribed BurnSelect areas to be burned

Select burning method to use

Locate & scout firebreaks

Determine smoke sensitive areas

Smoke Sensitive AreasAirportsHighwaysCommunitiesResorts or Recreation AreasSchoolsHospitalsFactoriesStockyard or holding pens

Conducting a Successful Prescribed BurnGet weather forecast & observe conditions prior to burningNotify adjoining landownersObtain a permit to burnStart with a small test fireSet backfires as close as possible to firebreaks

Fire only as many lines as you have manpower to watch

Watch for changing wind conditions

Watch for burning snags & stumps near firebreaks

Mop-up smoldering materials along firebreaks

Evaluating the BurnCheck for crown scorchif 1/3 or less of the crowns are discolored in a winter burn, there is little or no damage

Trunks should not be blackened over 3 high, if so, the fire was probably too hot

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