Exponential stronggrowthstrong of ‘‘snow molds’’ at sub-zero temperatures.pdfVIP

Biogeochemistry (2009) 95:13–21 DOI 10.1007/s10533-008-9247-y Exponential growth of ‘‘snow molds’’ at sub-zero temperatures: an explanation for high beneath-snow respiration rates and Q10 values S. K. Schmidt Æ K. L. Wilson Æ R. K. Monson Æ D. A. Lipson Received: 13 May 2008 / Accepted: 4 September 2008 / Published online: 26 September 2008 Springer Science+Business Media B.V. 2008 Abstract Numerous studies have demonstrated and metabolism to small changes in beneath-snow exceptionally high temperature sensitivity of the soil temperature, create a double exponential in the beneath-snow respiratory flux in cold-winter ecosys- Q10 function that may explain the extremely high tems. The most common, but still untested, explanation ( *1 9 106) Q10 values observed in past studies. Our for this high sensitivity is a physical one based on biological explanation for high Q10 levels is supported the observation that water availability in soils increases by several independent studies that have demonstrated exponentially as soils warm from -3 to 0C. Here, build up of microbial biomass under the snow as we present evidence for a biological hypothesis to temperatures warm from -2 to 0C. explain exponential kinetics and high Q10 values as beneath-snow soils warm from -3 to 0C during the Keywords Sub-nivian biogeochemistry early spring in a high-elevation subalpine forest. First, Arrhenius function Michaelis–Menten kinetics we show that some of the dominant organisms of the Soil respiration Psychrophiles beneath-snow microbial community, ‘‘snow molds’’, exhibit robust exponential growth at temperatures from -3 to -0.3C. Second, Q10 values based on growth rates across the temperature range of -2 to Introduction -0.3C for th