TY - JOUR
T1 - Warming-related increases in soil CO2 efflux are explained by increased below-ground carbon flux
AU - Giardina, Christian P.
AU - Litton, Creighton M.
AU - Crow, Susan E.
AU - Asner, Gregory P.
N1 - Funding Information:
We thank M. Long, J. Albano, M. Koontz, R. Mosley, J. Johansen, B. Hwang, K. Kinney and K. Kaneshiro for assistance with data collection, C. Fissore for assembling previously published radiocarbon data, T. Giambelluca for assistance with climate analyses, and D. Binkley, M. Busse, P. Selmants and D. Levinson for reviews of earlier versions of the manuscript. We thank the National Science Foundation (C.M.L. and C.P.G.), the College of Tropical Agriculture and Human Resources at the University of Hawaii at Manoa (C.M.L.), the Pacific Southwest Research Station, USDA Forest Service (C.P.G), and the Carnegie Institution for Science (G.P.A.) for funding to establish the study, collect flux data, and process and analyse soil samples. We thank C. Swanston and K. Heckman of the Northern Research Station, USDA Forest Service for funding, preparation and bulk SOC radiocarbon analyses at Lawrence Livermore National Laboratory; P. Reimer and the 14CHRONO Centre for Climate, the Environment, and Chronology, Queen’s University Belfast for radiocarbon analyses of SOC fractions; the USDA Forest Service, the State of Hawaii Department of Land and Natural Resources, Division of Forestry and Wildlife and the Parker Ranch for access to research plots in the Hawaii Experimental Tropical Forest; the US Fish and Wildlife Service for access to plots in Hakalau Forest National Wildlife Refuge. The Carnegie Airborne Observatory is made possible by the Andrew Mellon Foundation, John D. and Catherine T. MacArthur Foundation, Avatar Alliance Foundation, Grantham Foundation for the Protection of the Environment, Mary Anne Nyburg Baker and G. Leonard Baker Jr., and William R. Hearst III.
PY - 2014/9/11
Y1 - 2014/9/11
N2 - The universally observed exponential increase in soil-surface CO 2 efflux ('soil respiration'; F S) with increasing temperature has led to speculation that global warming will accelerate soil-organic-carbon (SOC) decomposition, reduce SOC storage, and drive a positive feedback to future warming. However, interpreting temperature-F S relationships, and so modelling terrestrial carbon balance in a warmer world, is complicated by the many sources of respired carbon that contribute to F S (ref.) and a poor understanding of how temperature influences SOC decomposition rates. Here we quantified F S, litterfall, bulk SOC and SOC fraction size and turnover, and total below-ground carbon flux (TBCF) across a highly constrained 5.2 °C mean annual temperature (MAT) gradient in tropical montane wet forest. From these, we determined that: increases in TBCF and litterfall explain >90% of the increase in F S with MAT; bulk SOC and SOC fraction size and turnover rate do not vary with MAT; and increases in TBCF and litterfall do not influence SOC storage or turnover on century to millennial timescales. This gradient study shows that for tropical montane wet forest, long-term and whole-ecosystem warming accelerates below-ground carbon processes with no apparent impact on SOC storage.
AB - The universally observed exponential increase in soil-surface CO 2 efflux ('soil respiration'; F S) with increasing temperature has led to speculation that global warming will accelerate soil-organic-carbon (SOC) decomposition, reduce SOC storage, and drive a positive feedback to future warming. However, interpreting temperature-F S relationships, and so modelling terrestrial carbon balance in a warmer world, is complicated by the many sources of respired carbon that contribute to F S (ref.) and a poor understanding of how temperature influences SOC decomposition rates. Here we quantified F S, litterfall, bulk SOC and SOC fraction size and turnover, and total below-ground carbon flux (TBCF) across a highly constrained 5.2 °C mean annual temperature (MAT) gradient in tropical montane wet forest. From these, we determined that: increases in TBCF and litterfall explain >90% of the increase in F S with MAT; bulk SOC and SOC fraction size and turnover rate do not vary with MAT; and increases in TBCF and litterfall do not influence SOC storage or turnover on century to millennial timescales. This gradient study shows that for tropical montane wet forest, long-term and whole-ecosystem warming accelerates below-ground carbon processes with no apparent impact on SOC storage.
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U2 - 10.1038/nclimate2322
DO - 10.1038/nclimate2322
M3 - Article
AN - SCOPUS:84906857229
SN - 1758-678X
VL - 4
SP - 822
EP - 827
JO - Nature Climate Change
JF - Nature Climate Change
IS - 9
ER -