Effect of Effect of FireFire on Soil on Soil ability to Sustain ability to Sustain PlantPlant

LifeLifeBecca Gentile and Erica

Garroutte

Figure 1—The wildfires of the Northern Rocky Mountains in 1910 burned over 3.1 million acres, destroying valuable timber resources

Figure 2—Over one-third of

Wallace, ID, burned during

the wildfires of 1910.

More than 1,700 starts!

19531944 1975

Forest Fires are a natural part of many habitats!

Why are fires good?

Clear out undergrowth

Fire-dependent seed germination

Increase soil nutrients

Increase diversity of forest composition and structure

June 8, 2002 – June 28, 2002

One start

138,000 acres in 20 days

Areas of severe burn

Wagle/Kitchen Study:

Soils in unburned sites are low in phosphorus and nitrogen

Available nitrogen and phosphorus levels increase with burn intensity

Water and nutrient availability in the soil both affect the germination and growth of plants

Debano/Conrad Study:

Organic plant material burned = nutrients returned to soil

Nutrients were burned off or leeched by runoff water and erosion

Temperature during fire = 340º - 370 º, which means accelerated evaporation

Loss of organic nutrients increases with burn severity

Question: How did the Hayman Fire affect the soil in areas of differing burn severity with regards to sustaining plant life? How does water availability play a role?

Hypothesis: Plants will grow most in soil from unburned areas with high water availability. Plants will grow least in soil from high burn areas with low water availability.

Site Description

Application rate: 2,000 lb per acre

1)Evidence of Aerial Mulching -Cereal Rye Grass (Lolium Multiflorium)

2)Parent Rock Material: Pikes Peak Granite

3)Elevation : 7,500-8,000ft

4) Same slope- West facing

K. Watenmaker http://www.uppersouthplatte.org/photos_fire/index.htm

Burn Site CriterionNo Burn Moderate Burn High Burn

- Rye Grass

-no black bark

-green branches

-West- facing

-12 trees in Quadrant

-scarce ground vegetation

-Lowest elevation

-slope: 24%

-Rye Grass

-partial black burned bark

-green branches at top

-West-facing

-13 trees in Quadrant

-scarce ground vegetation

-Highest elevation

-slope: 19%

- animal grazing

-Rye Grass

-completely black burned bark

-no green on trees

-West-facing

-25 trees in Quadrant

-Scarce ground vegetation

-Medium elevation

-Slope: 15%

-Animal grazing

http://www.uppersouthplatte.org/photos_fire/index.htm

6/12 unknown

http://www.uppersouthplatte.org/photos_fire/index.htm

E. Andrieska 6/13

http://www.uppersouthplatte.org/photos_fire/index.htm

S.Zufall 6/9

30ft

50 ft

N

Field Method : Quadrants

Tree Density:

11-25 trees

Slope: 15-24%

12 plants in each transect

Additional Measurements

-Moisture in soil - Dried all 3 soil types to determine grams of water present

-Animal evidence

--Potential disturbances

-Surrounding environment

Laboratory Method:Treatments

 

 

   

  High Burn Area

Moderate Burn Area

No Burn Area

High Water Content(1oz everyday)

high burn, high water

moderate burn, high water

no burn, high water

Low Water Content(1oz every 4th day)

high burn, low water

moderate burn, low water

no burn, low water

*Temperature : Day 75 F Night 70 F

Corn Oats

Repetition:

6 plants for each treatment

Total: 36 plants

Repetition:

12 seeds for each treatment

Total: 72 seeds

                                                    

                                                                                        

Expected Results:Growth of Oats/Corn in Burn Area Soils

0

2

4

6

8

10

12

No Burn Moderate Burn High Burn

Sh

oo

t/R

oo

t G

row

th (

cm)

High Water

Low Water

Figure 1: (Note: measurements on the y-axis are meant to show a general trend, not specific values)

Height of Rye Grass in Burn Area Soils

0

0.5

1

1.5

2

2.5

No Burn Moderate Burn High Burn

Hei

gh

t (f

t)

Figure 2: (Note: measurements on the y-axis are meant to show a general trend, not specific values)

 

Most Growth: No Burn

Least Growth: High Burn

-Water is Limiting Factor

Results: Water in Soils

Soil Moisture

0

5

10

15

20

25

No Burn Moderate Burn High Burn

So

il M

ois

ture

(%

)

Field Results

Field Measurements of Rye Grass Height

010203040506070

No Burn Moderate Burn High Burn

Hei

gh

t (cm

)

No Significant Difference

Shoot Growth of Oat Seeds

-5

0

5

10

15

20

25

No Burn Moderate Burn High Burn

Gro

wth

(cm

)

High Water

Low w ater

Results: Oat Seed Growth

-more difference in No burn ( allocation to roots)

-no sig difference in Mod and High burn

What factor is causing the Moderate and High burn to grow?

Root Growth of Oat Seeds

0

5

10

15

20

25

30

35

No Burn Moderate Burn High Burn

Gro

wth

(c

m)

Low Water

High Water

-amt of water in No burn-more difference in High burn-error bars show no sig difference

High Burn No Burn

Oat growth

No burn

Low water

Oat Root Growth

No burn

High water

Mod burn

Low water

Mod burn

High water

High burn

Low water

High Burn

Low water

Results: Corn

-most difference in no burn

-no overall sig difference

-all receiving same amount of light

Note: roots were broken in moderate burn during measurement

-more difference in Mod and high

-no overall sig difference

Root Growth of Corn

-6

-4

-2

0

2

4

6

8

10

12

No Burn Moderate Burn High Burn

Gro

wth

(cm

)

Low Water

High Water

Shoot Growth of Corn

-2

-1

0

1

2

3

4

No Burn Moderate Burn High Burn

Gro

wth

(cm

)

Low Water

High Water

Corn Growth

Corn Root Growth

No burn

Low water

No burn

High water

Mod burn

Low water

Mod burn

High water

High burn

Low water

High Burn

Low water

Factors affecting Results:-Animal grazing

-Site differences (light, soils, etc.)

-Tearing of roots in measurements

-Species of plants

-Small growth time

-Transplant shock

-Human error (measurement, etc.)

Does not support hypothesis:

There was no significant growth difference in No Burn , Moderate Burn, and High Burn sites

There was no significant growth difference in High Water and Low Water treatments

Discussion:

Why less water in Moderate and High Burn sites?

-Hydrophobic layer

- evaporation (Debano/Conrad study)

Why are plants in No Burn and High Burn sites growing at same rate with a significant difference soil moisture?

-Water limiting to some extent- then nutrients

-Water brings in nutrients

What are the effects of Rye grass?

-stop erosion

-competition

-bring in animals

-is it really sterile?

Improvements:

-More repetitions

-More variation in water treatments

- Use same species in lab and field

-Use more variety and less plastic plants

-Allow for longer growth time

Why does this study matter?

-Multiple Factors (nutrients + water)

-Water retained does not necessarily predict root/shoot growth

-More research is needed

-Could affect fire prevention and fire fighting policies

-When should humans get involved?

-Do humans really understand what is best for the environment?

Http://www.fs.fed.us/rm/hayman_fire/

Debano, L.F; Conrad, C.E. “The Effect of Fire on Nutrients in a Chapparal Ecosystem.”Ecology, Vol. 59, No. 3 (1978):489-497

Ricklefs, Robert E. The Economy of Nature. 5th ed. St. Louis: University of Missouri,2001

Wagle, R.F.; Kitchen, J.H. “Influence of Fire on Soil Nutrients in a Ponderosa Pine Type.”Ecology, Vol.53, No.1(Jan.,1972):118-

125

Works Cited