EXAMPLES OF LOCAL FIRE BEHAVIOR
Presented below are six types of vegetation common
to our region with computer generated estimates of how they would burn
under certain conditions. These predications assume a wind speed of 20
mph, typical moisture contents of living and dead vegetation for summertime,
and normal August weather for our area. (Conditions similer to the Oregon
Mountain and Lowden Fires).
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Annual grass occupies pastures, disturbed areas,
and areas that have rocky, clayey, excessively drained, wet, or
shallow soils.
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Manzanita, buckbrush, and/or deerbrush are the dominant
shrubs in this type. There may be grasses and wildflowers in the
understory. This type is found on old burns, harsh sites, shallow,
rocky, and/or excessively drained soils, and some timber harvest
areas. |
Ponderosa pine or Douglas-fir often dominate,
but generally two to five coniferous species are found in these forests. Conifer needles,
twigs, limbs, and occasionally logs cover the ground. Some seedling and sapling trees are
scattered throughout the forest. |
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This forest is like the Conifer Forest, but has
many seedling, sapling, and pole size trees( up to 11" in diameter)
that act as fuel ladders. These fuel ladders enable ground fires
to burn into the overstory tree canopy.
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Usually ponderosa pines and/or Douglas-fir are
interspersed equally with black, white, and/or live oaks and/or
madrone. Leaves, needles, twigs, limbs, and occasionally logs cover
the ground. Seedling and sapling trees are scattered throughout
the forest.
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This forest is usually dominated by black, white,
and/or live oaks and/or madrone, often with interspersed ponderosa
pines and/or Douglas-fir. Leaves, needles, twigs, limbs, and occasionally
logs cover the ground. Seedling and sapling trees are scattered
throughout the forest |
A lot of people assume that when a wildfire starts,
it will be quickly controlled and extinguished. This is an accurate assumption
97% of the time. For most wildfires, firefighters have the ability, equipment,
and technology for effective fire suppression. But 3% of the time wildfires
burn so intensely that there is little firefighters can do. Presented
at below are firefighter tactics as they relate to wildfire flame length.
Compare this to the flame lengths shown in the table above.
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THE
LIMITATIONS OF WILDLAND FIREFIGHTING |
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FLAME LENGTH |
EFFECTIVE FIRE SUPPRESSION
TACTICS* |
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Less than 4 feet |
Fireline constructed with hand tools, such as shovels and axes,
can be effective at the front of the fire. |
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4 to 8 feet |
Bulldozers and other heavy equipment will be needed to construct
an effective fireline.
Where bulldozers are not available, fire engines with hoses and water
will be required to “knock down” the flames before the
fire crews with hand tools can be effective, or crews must construct
a fireline at considerable distance from the fire. |
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8 to 11 feet |
Airtankers with fire suppressing retardant or helicopters with water
are required to reduce the fire's rate of spread before fireline construction
by crews or bulldozers can be effective. |
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More than 11 feet |
Direct fire suppression efforts will be ineffective. Retreat to
existing roads, streams and other barriers. Burn out fuels between
the fireline and the advancing fire front. |
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*Adapted from information provided
by John Swanson, USDA Forest Service. |
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