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?”

“There’s more to life

than fuels and fire models…..

Discuss”

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

RX-310 Introduction to Fire Effects Unit 3B-8-RX-310-PPT

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

Reality or Myth?

Does fire sterilize soil?

• 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

Reality or Myth?

Does fire lead to a flush of available nutrients?

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

Is pile burning ok?

What about soil compaction?

Houston, do we have a

problem?

“reducing fuels while proactively managing

our soils can be complementary outcomes”