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RX-310 Introduction to Fire Effects
- Soil ecosystems
- Seed bank ecology
- Chemical, physical, and biological properties of soil
- Impact to soil biota
- Seasonal concerns (dormancy, vulnerability, response, etc.)
- Impact to soil chemistry
Unit 3B-1-RX-310-PPT
Fuel Reduction Practices
RX-310 Introduction to Fire Effects
GOALS • Review the objectives of fuel reduction
• Discuss a few soil issues
“Should the desire to reduce fuels take center stage while other affected resources fade into the
background to absorb the impacts?”
Reality or Myth?
Thinning leads to:
• Soil compaction
• Loss of site nutrients
• Masticated fuels lead to
increased bark beetle attacks
Reality or Myth?
Burning leads to:
• Excessive soil heating
• A flush of available nutrients
• Increased hydrophobicity
Super hot
1. Wood piles
0
100
200
300
400
500
600
700
0 6 12 18 24 30 36 42 48 54 60 66 72 78T
emper
ature
(oC
)
Time (hours)
Soil heating
0 cm
5 cm
10 cm
30 cm
Sort of hot
2. Slash piles
0
100
200
300
400
500
0 12 24 36 48 60 72T
emp
erat
ure
(oC
)
Time (hours)
Large diameter – 20 ft
0 cm
5 cm
10 cm
30 cm
Semi-hot
3. Masticated fuels
Heat duration (h)
0 2 4 6 8 10 12 14
Tem
pera
ture
(oC
)
0
100
200
300
4000
1
2
4
Soil depth (inches)
Not so hot
Heat pulse (minutes)
0 10 20 30 40 50 60 70
Tem
pera
ture
(oC
)
0
200
400
600
800
Duff-soil interface
2 cm mineral soil
5 cm mineral soil
4. Low to moderate severity underburning
• Low- to moderate-severity burning results in
nominal soil heating
• Encourage mixed-severity burn patterns
and uneven forest floor consumption to limit
changes in soil life
Are masticated fuels good or bad?
• More nutrient retention
• Less soil compaction
• Reduced ladder fuels
• Fire hazard remains
• Less biomass harvested
• More bark beetles
Burn severity Inorganic N gain (kg/ha)
Low 4 Hart et al. 2006
Medium 15 Covington Sacket 1986
High 34 Covington Sacket 1986
The hotter the burn, the greater the nutrient flush