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Introduction to Fire Ecology
5/25/07
What is Fire?
Rapid oxidation reaction in which heat and light are produced.
Exothermic Three ingredients
– Fuel– Oxygen– Heat
Fire Factoids
Of known planets, only Earth has ingredients essential for fire, oxygen, plant (for fuel), and lightening to ignite the two into flames
90% of wildland fires started by humans, most accidental.
10% by lightning, lava, heat of decomposition
~ 4.7 million acres burn annually United States
Estimates suggest 100 million acres burned annually before Europeans arrived
Fire Ecology Branch of ecology Focus on origins,
cycles, and effects of wildland fire on ecosystems
Wildland fire: any fire burning in a natural environment
Fire ecologist tires to understand relationships between fire, living organisms and their habitat.
Fire Ecology Concepts
Three main concepts that provide basis for fire ecology– Fire history– Fire regime– Fire dependence/
Adaptation
Fire History
How often fire occurs in a geographic area
Trees and soil provide evidence of past fires
Fire scars seen in core samples from trees provide evidence of past fires
Ash layers in soil can show fire patterns
Intense fires can also leave soil hydrophobic
Fire Regime
Patterns and cycles of fire/ time
Includes– Severity: ecological
impact– Intensity: fire behavior
Ex. High intensity- high burn scars, crown fire, but low severity- no soil damage, undergrowth
Fire Dependence/ Adaptation
Concept applies to plants and animals that rely on fire or are adapted to survive in fire prone environments
Plant adaptations– Serotinous cones, fire
resistant bark, heat resistant foliage, rapid growth
Animal adaptations– Generally fleeing or
burrowing
Communities Adapted to Fire
Six different vegetative communities
– Tall Prarie (Midwest)– Ponderosa Pine (Interior
west)– Douglas-Fir (Pacific
Northwest)– Loblolly and Shortleaf
Pine (The Southeast)– Jack Pine (Great Lake
States)– Chaparral (California
and Southwest)
Tallgrass Prarie
Cover parts of Nebraska, Illinois, Iowa, and Kansas Primarily grasses, forbs, shrubs, and trees Fire helps maintain ecosystem stability and diversity Benefits include elimination of invasive species
Ponderosa Pine
Location Eastern Oregon and Washington, West Idaho, Extends into Interior West
Residing among Ponderosa pines include grasses forbs, and shrubs
Generally receives less than 25 inches of rain a year Fire serves to replace older plants with younger ones
of same species Fire cycle of 5 to 25 years
Douglas-Fir
Pacific Northwest, Oregon, Washington, B.C.
Mixed forest with climates that provide over 50 inches of rain
Douglas-Fir regenerate rapidly on site prepared by fire
Benefits of fire include removal of fuel and consequent reduction of severe crown fires
Loblolly and Shortleaf Pine
Southeast, Maryland, Virginia
Not highly adapted to fire as in other species
Benefits of fire include creation of favorable environment for seedlings and hindrance of invasive competing species
Jack Pine Great Lakes States,
Michigan, Minnesota, etc. Found among a variety of
trees, brush, forbs, and grass Jack Pine do not drop all
their seeds Thick cone protects seeds on
trees during fire Seeds released where fire
removed existing vegetation Reduce competition
Chaparral
California and Southwest
General term that applies to various types of brushland
Many species are adapted to and even promote fire
Fire releases nutrients locked up in plants
Reduces competition by eliminating invasive species