HR: 08:45h
AN: B21C-04    [Abstracts]
TI: The Response of Soil Carbon Decomposition to Temperature
AU: Fissore, C
EM: cfissore@mtu.edu
AF: Michigan Technological University, 1400 Townsend St., Houghton, MI 49931, United States
AU: * Giardina, C
EM: cgiardina@fs.fed.us
AF: Institute of Pacific Islands Forestry, USDA Forest Service, 60 Nowelo Street, Hilo, HI 96720, United States
AU: Ryan, M
EM: mgryan@fs.fed.us
AF: Rocky Mountain Research Station, 240 West prospect St, Fort Collins, CO 80520, United States
AU: Swanston, C
EM: cswanston@fs.fed.us
AF: Northern Research Station, 410 MacInnes Drive, Houghton, MI 49931, United States
AU: Vucetich, J
EM: javuceti@mtu.edu
AF: Michigan Technological University, 1400 Townsend St., Houghton, MI 49931, United States
AB: Global warming may accelerate the decomposition rate for soil carbon (C), potentially converting this massive terrestrial C reservoir from a net sink of atmospheric CO2 to a net source. We used three independent methods to examine the sensitivity of non-labile soil C decomposition (more than 90 percent of total soil C) to temperature: laboratory incubations paired with chemical fractionation and radiocarbon analyses; incubations where substrate supply was artificially manipulated; and isotope-based estimates of in situ soil C decomposition across gradients in mean annual temperature. Across methodologies, we found that non-labile soil C decomposition responded to changes in temperature with a Q10 values between 1.0 and 1.4. We conclude that for non-labile carbon (that remaining after 100 days of incubation or isolated slow and recalcitrant fractions through chemical fractionation) decomposition responses to temperature were significantly lower than the response of labile carbon (less than 5 percent of total soil C). We show that our findings cannot be explained by masking of recalcitrant carbon loss by labile carbon, and that, in contrast to modeling evidence, such masking is not tenable when soil C mass loss is accurately represented.
DE: 0419 Biomineralization
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0486 Soils/pedology (1865)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting