Ch 12 Fire Part 2 Factors affecting intensity

Factors affecting intensity • • 1) Fuel features 2) Wind 3) Slope 4) Fire

Factors affecting intensity • 1) Fuel features – – – amount size (fine faster)

Factors affecting intensity • 2) Wind – Velocity – Direction: – A) Away from

Factors affecting intensity • 2) Wind – Which?

Factors affecting intensity • 3) Slope – Slows downslope, accelerates upslope

Factors affecting intensity • 4) Fire size – Firestorm creates wind

Fire frequency • How determine “natural” frequency?

Fire frequency • How determine “natural” frequency? • 1) historical records

Fire frequency • 2) fire scars on trees Old longleaf pine Pine Mtn, GA

Fire frequency • 3) sediment cores (lakes, oceans): charcoal

Fire Effects: Soil • Generally: – 1) Nutrient availability increases – Fire = decomposition

Fire Effects: Soil • Generally: – 2) CEC (ability soil hold nutrients) decreases –

Fire Effects: Soil • Generally: – – 3) Other properties p. H increases erosion

Fire Effects: Communities • Depends on frequency/intensity • Can affect succession – Some grasslands

Fire Effects: Communities • Some scrublands become grassland (fire frequent) • Ex, chaparral type

Fire Effects: Communities • Species composition • Resistance to fire affected by:

Fire Effects: Communities • Species composition • Resistance to fire affected by: – 1)

Fire Effects: Communities • Resistance to fire affected by: – – 1) bark: increased

Fire Effects: Communities • Resistance to fire affected by: – 2) bud placement: exposed

Slides: 22

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Ch. 12: Fire! Part 2

Factors affecting intensity • • 1) Fuel features 2) Wind 3) Slope 4) Fire size

Factors affecting intensity • 1) Fuel features – – – amount size (fine faster) moisture (dry better) chemistry (resins, etc. ) distribution (3 D): vertical good. patchy fuels decrease intensity

Factors affecting intensity • 2) Wind – Velocity – Direction: – A) Away from fuel: backfire. – B) Into fuel: headfire – C) Along fire: flank fire

Factors affecting intensity • 2) Wind – Which?

Factors affecting intensity • 3) Slope – Slows downslope, accelerates upslope

Factors affecting intensity • 4) Fire size – Firestorm creates wind

Fire frequency • How determine “natural” frequency?

Fire frequency • How determine “natural” frequency? • 1) historical records

Fire frequency • 2) fire scars on trees Old longleaf pine Pine Mtn, GA

• Ponderosa pine

Fire frequency • 3) sediment cores (lakes, oceans): charcoal

Fire frequency

Fire Effects: Soil • Generally: – 1) Nutrient availability increases – Fire = decomposition • BUT total N & S may decrease (Why? )

Fire Effects: Soil • Generally: – 2) CEC (ability soil hold nutrients) decreases – Why?

Fire Effects: Soil • Generally: – – 3) Other properties p. H increases erosion increases runoff (water leaving watershed) increases

Fire Effects: Communities • Depends on frequency/intensity • Can affect succession – Some grasslands become forest (no fire)

Fire Effects: Communities • Some scrublands become grassland (fire frequent) • Ex, chaparral type conversion: humans changing community

Fire Effects: Communities • Species composition • Resistance to fire affected by:

Fire Effects: Communities • Species composition • Resistance to fire affected by: – 1) bark: protects vascular cambium (vc) – death vc “girdles” tree

Fire Effects: Communities • Resistance to fire affected by: – – 1) bark: increased thickness increases resistance increased moisture content increases resistance decreased density (fibrous bark) increases resistance

Fire Effects: Communities • Resistance to fire affected by: – 2) bud placement: exposed damaged – 3) branch placement: low damaged – 4) root placement: shallow damaged