1. Ch. 12: Fire! Part 2

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

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

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

5. Factors affecting intensity
2) Wind
Which?

6. Factors affecting intensity
3) Slope
Slows downslope, accelerates upslope

7. Factors affecting intensity
4) Fire size
Firestorm creates wind

8. Fire frequency
How determine “natural” frequency?

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

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

11. Ponderosa pine

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

13. Fire frequency

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

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

16. Fire Effects: Soil Generally: 3) Other properties pH increases
erosion increases
runoff (water leaving watershed) increases

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

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

19. Fire Effects: Communities
Species composition
Resistance to fire affected by:

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

21. 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

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