Effect of Fire on Soil ability to Sustain Plant Life Becca 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 More than 1,700 starts!

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 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

Burn Site Criterion No 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 6/12 unknown E. Andrieska 6/13 S.Zufall 6/9

30ft 50 ft N Field Method : Quadrants Tree Density: 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 4 th 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: Figure 1: (Note: measurements on the y-axis are meant to show a general trend, not specific values) 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

Field Results No Significant Difference

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? -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

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?

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