HR: 0800h
AN: GC51D-1088    [Abstracts]
TI: Effects of Mean Annual Temperature and Vegetation Type on Soil Carbon Quality in Soils from North America.
AU: * Fissore, C
EM: cfissore@mtu.edu
AF: Michigan Technological University, 1400 Townsend Dr, Houghton, MI 49931 United States
AU: Giardina, C P
EM: cgiardina@fs.fed.us
AF: USDA Forest Service North Central Research Station, 410 McInnes Drive, Houghton, MI 49931 United States
AB: Temperature influences belowground carbon cycling, but many uncertainties remain regarding the effects of mean annual temperature (MAT) on soil carbon quality. In particular, it is unclear how temperature alters the physical and chemical protection of organic matter in the more stable soil carbon fraction. The potential of stable carbon to act as a long-term reservoir of carbon is important, but whether storage is sensitive to management or climate is poorly quantified. Here we review data on acid insoluble carbon (AIC), separated from other soil carbon fractions using the established method of acid hydrolysis, and found a negative but non-significant correlation between AIC (soil content or percent of total soil carbon) and MAT (AIC = -MAT x 0.38 + 43; R2 = 0.01; p= 0.59). From the analyses of mean residence time (MRT) of the recalcitrant fraction, we observed that, across the gradient, there is no significant relationship between AIC turnover time and MAT (R2 = 0.08; p = 0.25), although AIC was found to be older at the warmest sites. We explored these relationships more precisely by examining AIC in soils of paired hardwood and Pinus dominated sites across an MAT gradient from Georgia to Colorado, and in parallel samples examining soil C quality through incubation. In this study, MAT across Pinus and hardwood stands ranges between -2 degree C and 20 degree C. Clay content across Pinus stands varied from 1% and 12.3%, with no relationship to MAT, while across hardwood clay content ranged between 2% and 16%, again with no relationship to temperature. Our results will provide information for understanding the relationship between MAT and soil carbon quality.
DE: 1699 General or miscellaneous
SC: Global Climate Change [GC]
MN: 2004 AGU Fall Meeting