Study

Types of Fire

 

Subsurface fires, burning in the duff, partially decayed leaves and woody material do not pose a great safety hazard to fire fighters. Be careful not to step into burnt out root or stump holes. A hazardous condition may exist where large quantities of dead or dried material have accumulated. If fire extends into this material the fire may spread quickly and entrap the fire fighter.

Surface fires, burning in the ground vegetation, slash, windfalls, young trees and the lower branches of standing trees pose a greater hazard to fire fighters. Be careful of radiant heat generated by the fire, flare ups, smoky conditions, poor visibility, sudden shifts of the wind and possible entrapment. Heavy accumulations of ladder fuels can permit the fire to rapidly extend into the crowns of the trees. Crew safety procedures should be re-evaluated if there is a high amount of ladder fuel present.

Crown fires burning in the tops of trees and jumping from tree to tree, create extremely dangerous conditions to work in. The fire fighter should not attempt to attack a fire once it has started to burn in the crown. Leave the area and retreat to the nearest safe area by way of pre-established escape routes. If a single tree burns to the top, firefighters should back away and reassess the situation because this candling effect can initiate a running grown fire.


Fuel Types

 

Caution should be exercised in proportion to the type, quantity and moisture content of the forest fuels. Wet fuels (high moisture content) will not generate the same heat intensity as dried fuels.

Areas of heavy fuel accumulations will be more hazardous than areas with less fuel loading. Areas where the fuels are large will produce more heat and will sustain the heat longer than areas with small fuels such as grass, brush and hardwood trees, also known as deciduous trees.

Hardwood (deciduous) trees will burn with less intensity and at a slower rate than softwood (evergreen) trees.