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Seasonal patterns in soil surface CO2 flux under snow cover in 50 and 300 year old subalpine forests


Hubbard, Robert M.; Ryan, Michael G.; Elder, Kelly; Rhoades, Charles C. 2005. Seasonal patterns in soil surface CO2 flux under snow cover in 50 and 300 year old subalpine forests. Biogeochemistry. 73(1): 93-107.

Soil CO2 þux can contribute as much as 60­80% of total ecosystem respiration in forests. Although considerable research has focused on quantifying this þux during the growing season, comparatively little effort has focused on non-growing season þuxes. We measured soil CO2 efflux through snow in 50 and 300 year old subalpine forest stands near Fraser CO. Our objectives were to quantify seasonal patterns in wintertime soil CO2 þux; determine if differences in soil CO2 þux between the two forest ages during the growing season persist during winter; and to quantify the sample size necessary to discern treatment differences. Soil CO2 þux during the 2002­2003 and 2003­2004 snow season averaged 0.31 and 0.35 ?mols m -2 s -1 for the young and old forests respectively; similar to the relative difference observed during summer. There was a signiÞcant seasonal pattern of soil CO2 þux during the winter with þuxes averaging 0.22 ?mols m -2 s -1 in December and January and increasing to an average of 0.61 ?mols m -2 s -1 in May. Within-plot variability for measurements used in calculating þux was low. The coefficients of variation (CV) for CO2 concentration, snowpack density, and snow depth were 17, 8 and 14%, respectively, yielding a CV for þux measurements within-plot of 29%. A within plot CV of 29% requires 8 sub-samples per plot to estimate the mean þux with a standard error of ±10% of the mean. Variability in CO2 þux estimates among plots (size = 400 m2) was similar to that within plot and was also low (CV = 28%). With a CV of 28% among plots, ten plots per treatment would have a 50% probability of detecting a 25% difference in treatment means for ? = 0.05.

Keywords: carbon budget, forest age, soil respiration, soil surface CO2 efflux, subalpine ecosystems


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Title: RMRS Other Publications: Seasonal patterns in soil surface CO2 flux under snow cover in 50 and 300 year old subalpine forests
Electronic Publish Date: August 16, 2007
Last Update:
August 16, 2007

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