burning effects on soil temperature in subalpine environments
DESCRIPTION
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) - PowerPoint PPT PresentationTRANSCRIPT
Burning Effects onSoil Temperature in Subalpine
EnvironmentsEthan Larson
MRS, University of Colorado-BoulderSpring 2013
IntroductionFire 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).
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/durationSoil 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).
The QuestionDo 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.
Methods1. Pick a random location2. Measure:
1. Snow depth (if applicable)2. Air Temperature3. Sunlight?4. Soil Temperature
3. N=10 (per site)4. Repeat at corresponding
location
Fourmile Canyon FireStarted September 6, 2010Lasted for 11 daysApproximately 10 square miles burned
Image of Fourmile Fire.
Courtesy of Nasa’s Aqua
Satellite
Where I Was in Fourmile
Mostly moderate burns; (severe=completely burnt soil, low=no burning at the base, moderate=partial burning at the base)
Fourmile ResultsSunshine Road Site:
Average Air Temp= 0.8°CAverage Healthy Forest
Snow Depth=3.5cmAverage Burned Forest
Snow Depth=2.5cmAverage Healthy Soil
Temp= 0.8°cAverage Burned Soil
Temp=0.2 °CP-value of unpaired, two-
tailed t-test=0.6774 Much greater than 0.05 Not significant Healthy Burned
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.90.8
0.2
Average Soil Tempera-tures in Sunshine Road
Location
Aver
age
Soil
Tem
pera
ture
s (°
C)
Fourmile Results Cont.Fourmile Road Site
Average Air Temp= 1.8°CAverage Healthy Forest
Snow Depth=3.6cmAverage Burned Forest
Snow Depth=3.7cmAverage Healthy Soil
Temp= 0.5°cAverage Burned Soil
Temp=0.6 °CP-value of unpaired, two-
tailed t-test=0.8569 Much greater than 0.05 Not significant Healthy Burned
0.44
0.46
0.48
0.5
0.52
0.54
0.56
0.58
0.6
0.62
Average Soil Temper-atures in Fourmile
Canyon Road Location
Aver
age
Soil
Tem
pera
ture
s (°
C)
Flagstaff FireStarted June 26, 2012Lasted 7 daysBurned approximately 300 acresCaused by lightning strike
Where I was on Flagstaff
Flagstaff ResultsAverage Air Temp= -3.3°CAverage Healthy Forest
Snow Depth=4.3cmAverage Burned Forest
Snow Depth=3.9cmAverage Healthy Soil
Temp= -2.9°cAverage Burned Soil
Temp=-2.2°CP-value of unpaired, two-
tailed t-test=0.2731 Much greater than 0.05 Not significant
Healthy Burned
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
Average Soil Tempera-tures in Flagstaff Burn
Area
Aver
age
Soil
Tem
pera
ture
s (°
C)
Overarching Results/ConclusionsThere 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.
But…Temperatures under
“deep” snow are more significantP-value of 0.0955
Not quite below 0.05 but much closer (more significant).
Could justify doing more research on snowier years.
Healthy Burned
-2.5
-2
-1.5
-1
-0.5
0
Average Soil Tempera-tures in "Deep" Snow on
Flagstaff
Aver
age
Soil
Tem
pera
ture
s
Questions?
ReferencesBaker, 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.