Daniel P. Bradley February 19 th, 2011 Winter Ecology Mountain Research Station, University of Colorado, Boulder EBIO 4100, Sec 570

Life in the Winter Soils Soil microbes in snow covered soils are respiring every minute, consuming available nutrients, and off-gassing them as CO 2 (King 08). Our class experiment: g (0.653 oz) of carbon could be converted into CO 2 in 186 days (Oct 25 – May 1), in ~100 cm 2 (Winter Eco 11). Winter soil: An ideal environment for microbial life.

Pro’s and Con’s of Winter Microbial Life Pro’s Con’s Highly protected Predatory, UV Highly stable Temperature Water supply via the snowpack, varying (Brooks 96) A specialized niche Food Supply High, but non-replenishing Temperature Not ideal for metabolic processes

The Food Supply The food supply in a finite amount We can assume that the amount of food is equal throughout the forest.

Question If food is limited by the cover of the snowpack, does the depth of the snowpack affect the amount of carbon (food) in the soil? H A : There is a difference in soil carbon between sites of varying snowpack. H O : There is not a difference in soil carbon

Methods A deep and shallow site were found on Feb 5 th 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 processes The soils were then sieved, weighed into 5 gram samples The samples were dried, combusted and weighed. Percent differences and averages were derived.

The Sites CU Mountain Research Station - Google Earth

Results The data show that there was a significant difference (p- value ≤ 0.05) in soil carbon between the sites

The Data p-value = (paired t-test) Mean percent difference: deep=0.1057, shallow=0.3322

The Data p-value = (paired t-test) Mean difference, in grams: deep=0.0056, shallow=0.0182

Discussion The 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?

Summary Snowpack 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) Mark Williams. Web. 25 Jan 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 (2008): ScienceDirect. Web. 25 Jan Nemergut, Diana, CU-Boulder, INSTAAR. Personal interview. 16 Feb Winter Ecology 2011, and T. Kittle. TS. CU-Boulder, Mountain Research Station.