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.