HR: 14:55h
AN: B52D-05    [PDF]
TI: Pulse Effects of Soil Respiration After Rain Events in California
AU: * Tang, J
EM: jtang@nature.berkeley.edu
AF: University of California at Berkeley, 151 Hilgard Hall, Dept of Environmental Science, Policy and Management, Berkeley, CA 94720 United States
AU: Baldocchi, D D
EM: biomet@nature.berkeley.edu
AF: University of California at Berkeley, 151 Hilgard Hall, Dept of Environmental Science, Policy and Management, Berkeley, CA 94720 United States
AU: Goldstein, A
EM: ahg@nature.berkeley.edu
AF: University of California at Berkeley, 151 Hilgard Hall, Dept of Environmental Science, Policy and Management, Berkeley, CA 94720 United States
AU: Xu, L
EM: lkxu@nature.berkeley.edu
AF: University of California at Berkeley, 151 Hilgard Hall, Dept of Environmental Science, Policy and Management, Berkeley, CA 94720 United States
AB: We observed pulse effects of soil respiration following the first rain and second rain after the dry season in California savanna and forest ecosystems in 2002 and 2003. Soil respiration was measured by three different methods: soil CO2 profile measurements using solid-state CO2 sensors buried in several depths of soils, under-story eddy covariance measurements, and chamber measurements. In addition, we conducted laboratory soil incubation experiments and in situ watering experiments to simulate rain events to observe the pulse effects of soil respiration. The results indicated that soil microbes immediately responded to the rain events. The time lag is less than an hour. The pulse CO2 efflux was about 5-10 times larger than the efflux before the rain. Spatially, soil respiration under trees has smaller pulse than that in the open area. Surface soils provide more CO2 sources and more contribution to the pulse than deep soils. The pulse after the first rain was more significant than that after the second rain, probably due to the decrease in the labile carbon content. The pulse effects also influence the seasonal pattern of soil respiration. It is suggested that soil respiration models may need to consider these pulse effects of soil respiration.
DE: 0315 Biosphere/atmosphere interactions
DE: 0400 Biogeosciences
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting