HR: 0800h
AN: B51C-0955    [Abstracts]
TI: CO2 Exchanges Between The Atmosphere And An Alpine Meadow Ecosystem On The Qinghai-Tibetan Plateau
AU: * Kato, T
EM: t\_kato\@jamstec.go.jp
AF: Ecosystem Change Research Program, Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, 236-0001 Japan
AU: Tang, Y
AF: National Institute for Environmental Studies, 16-3 Onogawa, Tsukuba, 305-8569 Japan
AU: Gu, S
AF: Northwest Plateau Institute of Biology, The Chinese Academy of Science , No.59 Xi-Guan Main Street, Xining, 81000 China
AU: Cui, X
AF: National Institute for Environmental Studies, 16-3 Onogawa, Tsukuba, 305-8569 Japan
AU: Hirota, M
AF: National Institute for Environmental Studies, 16-3 Onogawa, Tsukuba, 305-8569 Japan
AU: Du, M
AF: National Institute for Agro-Environmental Science, 3-1-3 Kannondai, Tsukuba, 305-8604 Japan
AU: Li, Y
AF: Northwest Plateau Institute of Biology, The Chinese Academy of Science , No.59 Xi-Guan Main Street, Xining, 81000 China
AU: Zhao, X
AF: Northwest Plateau Institute of Biology, The Chinese Academy of Science , No.59 Xi-Guan Main Street, Xining, 81000 China
AU: Oikawa, T
AF: Institute of Biological Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba, 305-8572 Japan
AB: We measured the net ecosystem CO2 exchange (NEE) in an alpine meadow ecosystem (lat $37\deg$29-45$^{'}$N, long $101\deg$12-$23$^{'}$E, 3250 m a.s.l.) on the Qinghai-Tibetan Plateau in China, in the 2001 and 2002 by the eddy covariance method to examine the carbon dynamics and budget on this unique plateau. The maximum CO$_{2}$ uptake and release rates derived from the diurnal course of CO$_{2}$ flux were -10.8 $\mu$ mol m$^{-2}$ s$^{-1}$ and 4.4 $\mu$ mol m$^{-2}$ s$^{-1}$, respectively, indicating a relatively high net carbon sequestration potential as compared to subalpine coniferous forest at similar elevation and latitude. The largest daily CO$_{2}$ uptake flux was 3.9 g C m$^{-2}$ d$^{-1}$ on 7 July 2002, which is almost half less than those reported for lowland grassland and forest at similar latitudes. The daytime CO$_{2}$ uptake flux was lineally correlated with the daily photosynthetic photon flux density in each month. The nighttime average CO$_{2}$ effluxes increased exponentially with the increment of soil temperature measured at the depth of 5cm with a Q$_{10}$ value of 3.7. The nighttime average CO$_{2}$ flux, however, showed a negative linear correlation with the soil water content. Diurnal changes in gross primary production (GPP) and ecosystem respiration (R$_{e}$), derived from the regression curves of the nighttime R$_{e}$ to the soil temperature, showed that an afternoon increase of NEE was highly associated with an increase of Re. Seasonal changes in GPP corresponded well to changes in the leaf area index and daily photosynthetic photon flux density. The alpine ecosystem exhibited lower GPP (575 g C m$^{-2}$ y$^{-1}$) than, but similar net ecosystem production (78.5 g C m$^{-2}$ y$^{-1}$) as, subalpine forest ecosystems. The results suggest that the alpine meadow behaved as a CO$_{2}$ sink during the 1-year measurement period, but apparently sequestered a rather small amount of C in comparison with similar alpine ecosystems.
DE: 4805 Biogeochemical cycles (1615)
DE: 1615 Biogeochemical processes (4805)
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
DE: 0330 Geochemical cycles
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting