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Soil Carbon under the Snowpack in a Continuous Coniferous Forest
Daniel P. BradleyFebruary 19th, 2011
Winter Ecology
Mountain Research Station,University of Colorado, Boulder
EBIO 4100, Sec 570
Life in the Winter SoilsSoil microbes in snow covered soils are respiring every
minute, consuming available nutrients, and off-gassing them as CO2 (King 08).
Our class experiment: 18.536 g (0.653 oz) of carbon could be converted into CO2 in 186 days (Oct 25 – May 1), in ~100 cm2 (Winter Eco 11).
Winter soil: An ideal environment for microbial life.
Pro’s and Con’s of Winter Microbial LifePro’s Con’sHighly protected
Predatory, UVHighly stable
TemperatureWater supply
via the snowpack, varying (Brooks 96)
A specialized niche
Food SupplyHigh, but non-replenishing
TemperatureNot ideal for metabolic
processes
The Food SupplyThe food supply in a finite amountWe can assume that the amount of food is
equal throughout the forest.
QuestionIf food is limited by the cover of the snowpack, does the
depth of the snowpack affect the amount of carbon (food) in the soil?
HA : There is a difference in soil carbon between sites of varying snowpack.
HO : There is not a difference in soil carbon
MethodsA deep and shallow site were found on Feb 5th Five samples for each site were taken, with 2 sub sites for
each site, from the top 5cm of the soil. The soils were refrigerated maintain metabolic processesThe soils were then sieved, weighed into 5 gram samplesThe samples were dried, combusted and weighed.Percent differences and averages were derived.
The Sites
CU Mountain Research Station - Google Earth
ResultsThe data show that there was a significant difference (p-
value ≤ 0.05) in soil carbon between the sites
The Datap-value = 0.0165 (paired t-test)
Mean percent difference: deep=0.1057, shallow=0.3322
The Datap-value = 0.0113(paired t-test)
Mean difference, in grams: deep=0.0056, shallow=0.0182
DiscussionThe shallow snowpack had more carbon underneath it,
why? Carbon is limiting for microbes, lower carbon indicates
higher microbe populations/activity (Nemergut 11). Temperature swings.
What is affecting snowpack?Wind, Precipitation
What is affecting the amount of carbon (litter) under the snowpack?Beetle kill?
SummarySnowpack does have an affect on the microbial
population of the soil, via carbon.More snowpack, more respiration, more carbon
consumed.
Literature Cited Brooks, Paul D., Mark W. Williams, and Steven Schmidt. "Microbial
Activity under Alpine Snowpacks, Niwot Ridge, Colorado " Biogeochemistry 32.2 (1996). 93-113. Mark Williams. Web. 25 Jan. 2011.
King , A. J., A. F. Meyer, and S. K. Schmidt. "High Levels of Microbial Biomass and Activity in Unvegetated Tropical and Temperate Alpine Soils." Soil Biology and Biochemistry 40.10 (2008): 2605-610. ScienceDirect. Web. 25 Jan. 2011.
Nemergut, Diana, CU-Boulder, INSTAAR. Personal interview. 16 Feb. 2011.
Winter Ecology 2011, and T. Kittle. TS. CU-Boulder, Mountain Research Station.