HR: 0830h
AN: B31E-0351    [PDF]
TI: Variation in 13C abundance in Respiration Among Ecosystem Components: Implications for Flux Partitioning
AU: * Tu, K P
EM: ktu@socrates.berkeley.edu
AF: University of California at Berkeley, Center for Stable Isotope Biogeochemistry, Department of Integrative Biology, VLSB, Berkeley, CA 94720 United States
AU: Dawson, T E
EM: tdawson@socrates.Berkeley.edu
AF: University of California at Berkeley, Center for Stable Isotope Biogeochemistry, Department of Integrative Biology, VLSB, Berkeley, CA 94720 United States
AB: Contrary to the longstanding notion of isotopic equilibrium among ecosystem respiration components, we found significant variation in the carbon isotope ratio of CO2 respired from leaves, stems, roots and soil microorganisms in five contrasting ecosystems along a climate gradient in California (redwood forest, chaparral, grassland, oak savanna, ponderosa pine plantation). The largest differences were observed between leaf and microbial respiration (5.84 per mil +/- 1.58 per mil; mean +/- SD) with the signature of ecosystem respiration always lying between that of leaves and microbes (leaves $<$ ecosystem $<$ microbes). Based on these differences, we determined that ecosystem respiration comprised an average of 25% microbial and 75% plant respired CO2 (+/- 10%). Further study is underway to determine the underlying cause of these isotopic differences.
DE: 0315 Biosphere/atmosphere interactions
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting