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