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Burning Effects on Soil Temperature in Subalpine Environments

Burning Effects on Soil Temperature in Subalpine Environments. Ethan Larson MRS, University of Colorado-Boulder Spring 2013. 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)

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Burning Effects on Soil Temperature in Subalpine Environments

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  1. Burning Effects onSoil Temperature in Subalpine Environments 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 • Pick a random location • Measure: • Snow depth (if applicable) • Air Temperature • Sunlight? • Soil Temperature • N=10 (per site) • 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)

  8. 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

  9. 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

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

  11. Where I was on Flagstaff

  12. 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

  13. 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.

  14. 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.

  15. Questions?

  16. 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.

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