Chapter 18: Fire Flashcards
This is an integral part of many ecosystems
Fire
Fire was once thought to be only this
Destructive
This has greatly changed many ecosystems
Fire suppression
This is the study of fire in ecosystems
Fire ecology
What are four focuses of fire ecology?
- Origin of natural fires; 2. Factors influencing spread and intensity of fire; 3. Relationship of fire and ecosystems; 4. Use of controlled fire for ecosystem health
What are the five concepts that form the basis for fire ecology?
- Fire dependence; 2. Fire history; 3. Fire regime; 4. Fire effects; 5. Fire adaptations
This describes the reliance of ecosystems on fire
Fire dependence
This describes the past association of regions with fire
Fire history
This describes the intensity and frequency of fire
Fire regime
This describes the impacts of fire on soil, vegetation and hydrology
Fire effects
This describes the evolution of fire-related species traits
Fire adaptations
What are the three types of systems related to fire?
- Fire-dependent systems; 2. Fire-sensitive systems; 3. Fire-independent systems
In these systems, fire plays an essential role and its exclusion leads to major changes in the ecosystem
Fire-dependent systems
Are many plants and animals in fire-dependent systems fire-adapted?
Yes
Is plant reproduction in fire-dependent systems often stimulated by fire?
Yes
Are fire-dependent systems less fire-prone and flammable?
No
Does plant architecture in fire-dependent systems hinder fire spread?
No
In these systems, fire effects are detrimental to the ecosystem
Fire-sensitive systems
In fire-sensitive systems, does frequent fire cause a shift to less or more fire-prone vegetation?
More fire-prone
Do fire-sensitive species have fire adaptations?
No
Does fire-sensitive ecosystem structure inhibit the spread of fire?
Yes
In these systems, fire plays little or no role
Fire-independent systems
What are three conditions that can make a system fire-independent?
Too cold, too dry, too wet
How many global ecosystems depend on fire?
More than half
What are five patterns of fire described by fire regimes?
Fire type, intensity, severity, frequency, and seasonality
What are three patterns of fire types?
Ground, surface, crown
This fire pattern describes the energy release of fire
Fire intensity
This fire pattern describes the impact of fire on an ecosystem
Fire severity
How is fire severity often measured?
As plant mortality
This fire pattern measures fire return interval
Fire frequency
This fire pattern describes the time of year when fire is most common
Fire seasonality
The frequency of fire varies with this
Geography
What three components are required for fire?
Fuel, ignition source, oxidizing agent
Forests provide a diversity of these for fire
Fuels
What are four types of fire fuel in forests?
Trees, woody debris, grasses, litter
What are the two different types of forest ignition sources?
Natural and human
What are two natural forest ignition sources?
Lightning and volcanoes
What are three human forest ignition sources?
Campfires, cigarettes, arson
The atmosphere provides sufficient amounts of this as an oxidizing agent
Oxygen gas
What are four factors that determine fire behavior?
- Forest fuel types; 2. Fuel moisture; 3. Topography; 4. Weather
What are four types of forest fuels?
Surface, ground, ladder and aerial fuels
What are four types of surface fuels in forests?
Woody debris, litter, grasses, small shrubs
This type of forest fuel is below the surface litter
Ground fuel
What are three types of ground fuels in forests?
Humus, peat, roots
What are three types of ladder fuels in forests?
Small trees, hanging branches, vines
This type of forest fuel is suspended in the forest canopy
Aerial fuel
What are the three types of wildfires?
Surface, ground, and crown fires
This type of wildfire burns surface fuels
Surface fire
Are surface fires hot and rapidly moving?
Yes
This soil layer is not completely consumed in a surface fire
O layer
What type of vegetation is killed by surface fires?
Smaller woody vegetation
This type of wildfire is fed by roots and buried organic matter
Ground fire
Are ground fires rapid-moving and high intensity?
No
Can ground fires smolder for long periods?
Yes
Are ground fires often highly destructive?
Yes
Heat exposure from ground fires destroys these three forest components
O layer, soil biota, plants
This type of wildfire usually starts as a surface fire, then spreads up the canopy via ladder fuels
Crown fire
Can crown fires spread quickly from crown to crown?
Yes
Are crown fires highly destructive to plant biomass?
Yes
Are crown fires more common in hardwoods or conifers?
Conifers
Fuels with this moisture level are highly flammable
< 10%
Which burns better, dead vegetation or living vegetation?
Dead vegetation
Which burns better, green conifers or green broadleafs?
Green conifers
This topographical feature influences fire behavior
Slope
Fires do this to uphill fuels, making them ignite faster
Preheat uphill fuels
This debris can ignite more fuels on a slope
Rolling burning debris
Do northern or southern aspects burn hotter?
Northern
Why do northern aspects burn hotter?
More vegetation
Fires spread rapidly in these two types of topographical features
Canyons and valleys
What four weather factors act in concert to affect fire behavior?
Temperature, relative humidity, wind, precipitation
Weather affects these two aspects of a fire
Intensity and spread
Hot temperatures increase this aspect of fuels
Ignitability
What are five effects of wind on fire behavior?
- Dries fuel; 2. Carries oxygen; 3. Affects fire direction; 4. Starts spot fires; 5. Shapes burn area
At this relative humidity, fuels are more likely to ignite
< 30%
This relative humidity is a dangerous fire risk
< 20%
What are two affects of heavy precipitation on fires?
Wetting fuels and extinguishing burning fires
What are the three scales at which fires are influenced?
Flame, wildfire, fire regime
What are three abiotic effects of fire on soil?
- Soil temperature; 2. Soil water and hydrology; 3. Soil chemistry
How does fire affect soil temperature?
By removing O layer and opening soil
How does fire change soil temperatures by day and night?
Hotter day temperatures and cooler night temperatures
What are three things that fires reduce to increase the amount of water than gets to the soil?
By reducing litter, interception and transpiration
Fires open soils and increase this in soil water
Evaporation
Can fires create water-repellent soils?
Yes
Fires on slopes can increase this
Runoff/erosion
What are three ways fire causes nutrient loss?
Oxidation, volatilization, erosion
What counteracts some nutrient loss from fire?
Charcoal
Do soils become more basic or acidic with fire?
Basic
Fire can alter these two soil aspects by affecting clays
Texture and structure
These flora are typically destroyed by fire
Fire-intolerant flora
Some fire-intolerant flora produce these
Fire-activated seeds
These flora resist some fire damage and may resprout after fire
Fire-tolerant
These flora suffer little damage from fire
Fire-resistant
What animals are most vulnerable to fire?
Small animals with limited mobility
What causes most large animal mortality during a fire?
Smoke
The biggest effects on animals from fire are due to this
Habitat impact
These animals are vulnerable to fire when nesting
Birds
Birds profit from more of this after fire
Prey
These animals flee or take cover from fire
Mammals
These animals hide from fire in mud or water
Herps
These organisms vary in fire resistance
Microbes
These provide refuge from fire for microbes
Deeper soils
Microbes profit from these soil conditions after fire
Warm, wet soils
What are six purposes of prescribed fire?
- Hazard reduction; 2. Hardwood control; 3. Site preparation; 4. Forage improvement; 5. Disease control; 6. Accessibility/aesthetics
This purpose of prescribed fire reduces fire risk by reducing litter
Hazard reduction
This purpose of prescribed fire kills undesirable plant species
Hardwood control
This purpose of prescribed fire destroys debris and exposes bare soil
Site preparation
This purpose of prescribed fire promotes grass and forbs
Forage improvement
This purpose of prescribed fire controls some bacterial and fungal pests
Disease control
This purpose of prescribed fire opens stands
Accessibility/aesthetics
What are eight factors to be considered when planning a prescribed burn?
- Weather; 2. Fuel moisture timelag; 3. Season; 4. Burn method; 5. Ignition method. 6. Smoke management; 7. Burn plan; 8. Burn evaluation
Knowledge of this is key to burning and mandatory for proper smoke management
Weather
What are four weather elements to consider when planning a burn?
Temperature, humidity, precipitation, wind
What is the best temperature for burning in the winter?
20-60 degrees
What is the best temperature for burning in the summer?
> 80%
What is the best humidity for burning?
30-55%
What wind speed is best for burning?
3-5 mph within forest
What is the best rainfall for a burn?
0.5-1.0”, one week before burn
What is the best Keetch-Byram Drought Index for burning?
250-400
This is key to predicting fire behavior
Fuel moisture timelag
These fuels take 1 hour for 2/3 of the dead fuel to respond to atmospheric moisture
Flashy fuels
Fuels this size take 10 hours for 2/3 of the dead fuel to respond to atmospheric moisture
1/2 inch diameter
Fuels this size take 100 hours for 2/3 of the dead fuel to respond to atmospheric moisture
3 inch diameter
Fuels this size take 1000 hours for 2/3 of the dead fuel to respond to atmospheric moisture
8 inch diameter
What are the two prescribed fire seasons?
Cool and growing season
These prescribed burns are held late winter to early spring
Cool season burns
What is the purpose of cool season burns?
Reducing forest litter
These prescribed burns are held from early spring to late summer
Growing season burns
What is the purpose of growing season burns?
Killing vegetation
Which burns hotter, growing season or cool season burns?
Growing season burns
Which is most common for wildlife management, growing season or cool season burns?
Cool season burns
These are used to achieve specific burning goals
Different burn methods
Burn methods must correlate with these three factors
Weather, fuels, terrain
What are four burning methods?
Backfire, headfire, flankfire, spotfire
This burning method is started at a firebreak/road and headed directly into the wind
Backfire
This burning method is the least intense and most predictable
Backfire
This burn method has a narrow burning zone with short flame lengths
Backfire
This burning method has a slow rate of spread and burns deep
Backfire
This burning method has a low smoke output
Backfire
What are seven characteristics of the backfire burning method?
- Low intensity; 2. Predictable; 3. Narrow burning zone; 4. Short flame length; 5. Slow rate of spread; 6. Burns deep; 7. Low smoke output
Where is a fire started in the backfire burning method?
Firebreak or road
How does a backfire travel in relation to the wind?
Directly into wind
This burning method is the most intense and unpredictable
Headfire
This burning method has a wide burning zone with long flame lengths
Headfire
This burning method has a fast rate of spread and burns shallowly
Headfire
This burning method has a high smoke output
Headfire
What are seven characteristics of a headfire?
- High intensity; 2. Unpredictable; 3. Wide burning zone; 4. Long flame lengths; 5. Fast rate of spread; 6. Burns shallowly; 7. High smoke output
These two burning methods are intermediate intensity
Flankfire and spotfire
In this burning method, fire spreads at right angle to the wind
Flankfire
This burning method is limited to steady wind conditions
Flankfire
This burning method requires careful coordination
Flankfire
This burning method is used for securing flanks of back or head fires
Flankfire
This burning method is useful in shifting winds
Spotfire
In this burning method, spots merge to form a strip headfire
Spotfire
What device is used to produce spotfire?
Delayed Aerial Ignition Device
There are many ground and aerial methods for this
Ignition methods
Proper burning must manage this
Smoke
What are four examples of smoke sensitive areas?
Roads, schools, hospitals, nursing homes
Burners are liable for this
Smoke damages
This will lift smoke during a burn
Correct weather
All burns should have this
Written plan
What are three things that should be included in the written burn plan?
- Burn unit location/description; 2. Burning objectives/instructions; 3. Desired and actual weather conditions
Burn plans should have a detailed map of this
Burn unit
What are four things that should be included in a burn unit map?
Control lines, terrain, wind, landowners
What are two things to check for when evaluating a burn in spring?
New growth and bark beetles
