1. Ethan Larson MRS, University of Colorado-Boulder Spring 2013

2. Introduction Fire effects on soil Changes the soil chemistry More C in soil (Knicker, 2007) Increases in inorganic N Soil retains less water (Iverson, 2002) In the same experiment, soil temperatures in burned areas were on average, higher than that of unburned soils during summer months (may be different for winter).

3. Why? Subnivean Residents Soil temperature can affect the animals that live under the snow (Coulson et. al, 1995). Insects usually use soil for insulation so change in soil temperatures can lead to high mortalities (Mail, 1930). Soil temperature can also affect the rate of decomposition that occurs under the snowpack (Schmidt & Lipson, 2003). Snow accumulation/duration Soil temperatures can affect the accumulation of snow, and snowpack can, in return, affect soil temperatures. Snow pack features, such as depth hoars, can only occur when the soil is at a certain temperature (there is a certain temperature gradient).

4. The Question Do recent burns have an effect on how well the soil retains heat? Hypothesis: Burned soils will be less efficient at retaining heat than healthy (unburned) soils.

5. Methods 1. Pick a random location 2. Measure: 1. Snow depth (if applicable) 2. Air Temperature 3. Sunlight? 4. Soil Temperature 3. N=10 (per site) 4. Repeat at corresponding location

6. Fourmile Canyon Fire Started September 6, 2010 Lasted for 11 days Approximately 10 square miles burned Image of Fourmile Fire. Courtesy of Nasa’s Aqua Satellite

7. Where I Was in Fourmile Mostly moderate burns; (severe=completely burnt soil, low=no burning at the base, moderate=partial burning at the base)

9. Fourmile Results Sunshine Road Site: Average Air Temp= 0.8°C Average Healthy Forest Snow Depth=3.5cm Average Burned Forest Snow Depth=2.5cm Average Healthy Soil Temp= 0.8°c Average Burned Soil Temp=0.2 °C P-value of unpaired, two- tailed t-test=0.6774 Much greater than 0.05 Not significant

10. Fourmile Results Cont. Fourmile Road Site Average Air Temp= 1.8°C Average Healthy Forest Snow Depth=3.6cm Average Burned Forest Snow Depth=3.7cm Average Healthy Soil Temp= 0.5°c Average Burned Soil Temp=0.6 °C P-value of unpaired, two- tailed t-test=0.8569 Much greater than 0.05 Not significant

11. Flagstaff Fire Started June 26, 2012 Lasted 7 days Burned approximately 300 acres Caused by lightning strike

12. Where I was on Flagstaff

14. Flagstaff Results Average Air Temp= -3.3°C Average Healthy Forest Snow Depth=4.3cm Average Burned Forest Snow Depth=3.9cm Average Healthy Soil Temp= -2.9°c Average Burned Soil Temp=-2.2°C P-value of unpaired, two- tailed t-test=0.2731 Much greater than 0.05 Not significant

15. Overarching Results/Conclusions There doesn’t appear to be any correlation between recent burning and winter soil temperatures. P-values were all really high, indicating no significance Accepting null hypothesis of no effect.

16. But… Temperatures under “deep” snow are more significant P-value of 0.0955 Not quite below 0.05 but much closer (more significant). Could justify doing more research on snowier years.

17. Questions?

18. References Baker, Malchus B. “Hydrologic and Water Quality Effects of Fire.” 31-42. Coulson, Hodkinson, Strathdee, Block, Webb, Bale and Worland. 1995. “Thermal Environments of Arctic Soil Organisms During the Winter.” Arctic and Alpine Research, 27, 364-370. Iverson, Louis R. 2002. “Soil Temperature and Moisture Fluctuations During and After Prescribed Fire in Mixed-Oak Forests, USA.” Natural Areas Journal, 22, 296-304. Knicker, Heike. 2007. “How does fire affect the nature and stability of soil organic nitrogen and carbon? A review.” Biogeochemistry, 85, 91-118. Mail, G. A. 1930. “Winter Soil Temperatures and their Relation to subterranean Insect Survival.” Journal of Agricultural Research, 41, 571-592. Schmidt, S. K. & D. A. Lipson. 2003. “Microbial growth under the snow: Implications for nutrient and allelochemical availability in temperate soils.” Plant and Soil, 259, 1- 7.