Chapter 5 Fire Environment : Topography & Continued Flashcards
Topography is the most ___ of the three major components of the fire environment.
constant
The most important factor under topography is ____, since changes in slope have very direct and profound effects on fire behavior.
steepness of slope
The position of a slope is important because this ____ and their availability.
influences the types and loading of fuels
____ and ___ facing slopes typically have the greatest number of fires.
South / west
The fuels on south and west facing slopes cure out earlier in the year, they are typically ____, and the average relative humidity is ____.
smaller and drier / lowest on these slopes
These slopes have the ___ fire season and have more light, flashy fuels in which to carry fire on sunny days, south and west facing slopes receive the _____ because of exposure to the sun.
longest / longest heat period
North slopes, on the other hand, typically have the ____, highest fuel moisture, lowest average temperature, _____..
heaviest fuels / lowest rate of spread of fires and lowest fire starts
The third component of the fire environment is the ____. Fuels are the part of the environment that actually ____. The other two components, weather and topography, determine_____.
fuels / carry the fire / how the fuels will burn
Grasses and weeds are
(Light Fuels)
Coastal sage scrub are
(Moderate Fuels)
Mixed chaparral are
(Heavy Fuels)
The moisture content of dead fuels varies from around _____ depending on weather conditions.
2% to about 30%,
Dead branches and twigs frequently make up _____ volume in chaparral stands more than 30 years old.
one-third to one-half of the fuel
As a rule of thumb, chaparral stands accumulate about ___ dead material for each year since the brush canopy closed following the last major fire or other clearing.
1%
____ is generally considered the most important influence on flammability of fuels.
Moisture content
The moisture content is highest (_____) in late Winter and early Spring when the vegetation is in its active growing cycle.
200% or more
Moisture content in living, native vegetation is lowest (_____) in the Fall and early Winter. This is also the time of year when the Santa Ana winds are most prevalent.
50-60%
_____ compose a high percentage of the fuels in the City of Los Angeles.
Grasses and weeds
Grasses and weeds are light fuels and compose what we call _____.
“flash fuels.”
Coastal sage scrub is a plant community made up of _____. Common species include California Sagebrush, Buckwheat, Black Sage, Chamise, Elderberry and Honeysuckle.
mainly non-woody brush species
______ in the City of Los Angeles occur in this type of fuel complex. This is due to the high ratio of dead material build-up, and the high concentration of volatile chemicals and resins in coastal sage scrub.
Most of the brush fires
Although coastal sage scrub only grows about ____ in height, fires burn with great intensity, and high rates of spread of fires can be expected.
four feet
Mixed chaparral makes up the taller (_____) brush found mostly on ____ slopes. Common species include Toyon, Walnut, Scrub Oak, Ceanothus, Manzanita and Catalina Cherry.
up to 20 feet / north facing
The majority of these 20 inputs are gathered from _____ and from the Riverside National Weather Service.
Fire Station 108’s weather station
This a 10 hour fuel moisture reading which is acquired from Fire Station 108’s weather station. The weather station has the capability to detect this reading from the weighing of ______.
standard array of 1/2” Ponderosa Pines fuel sticks.
Our number rating is (2) which calculates to a ___ slope class.
26%-40%
BRUSH BURNING behavior INDEX is
BBI
1 Hour Timelag Fuel Moisture : Fuels consisting of dead herbaceous plants and roundwood less than ____ in diameter. Also included is the uppermost layer of litter on the forest floor.
one-fourth inch
10 Hour Timelag Fuel Moisture :
Fuels consisting of dead twigs, branches and roundwood ____ in diameter, and litter from surface level to _____ on the forest floor.
one-fourth to one inch / three-quarters of an inch deep
100 Hour Timelag Fuel Moisture :
Dead fuels consisting of roundwood in the size range of _____ in diameter
1 to 3 inches
1000 Hour Timelag Fuel Moisture :
Dead fuels consisting of roundwood ____ in diameter or the layer of the forest floor from ____ below the surface.
3 to 8 inches / three-fourths inch to 4 inches
X 1000 Hour Timelag Fuel Moisture :
Dead fuels consisting of roundwood greater than ____ in diameter.
8 inches
Red Flag :
wind speed 25+ and Relative humidity 15% or lower
