HR: 0800h
AN: B51C-0961    [Abstracts]
TI: Effects Of Temperature On The CO2 Flux In An Alpine Meadow Ecosystem On The Qinghai-Tibetan Plateau
AU: * Gu, S
EM: gus@mail.nwipb.ac.cn
AF: Northwest Institute of Plateau Biology, Chinese Academy of Sciences , 59 Xiguan Street, Xining, 810001 China
AU: * Gu, S
EM: gus@mail.nwipb.ac.cn
AF: National Institutes for Environmental Studies, Onogawa 16-2, Tsukuba, 305-8506 Japan
AU: Zhao, X
AF: Northwest Institute of Plateau Biology, Chinese Academy of Sciences , 59 Xiguan Street, Xining, 810001 China
AU: Li, Y
AF: Northwest Institute of Plateau Biology, Chinese Academy of Sciences , 59 Xiguan Street, Xining, 810001 China
AU: Tang, Y
AF: National Institutes for Environmental Studies, Onogawa 16-2, Tsukuba, 305-8506 Japan
AU: Du, M
AF: National Institutes for Agro-Environmental Sciences, Kannondai 3-1-3, Tsukuba, 305-8604 Japan
AU: Kato, T
AF: Frontier Research System for Global Change, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, 236-0001 Japan
AU: Cui, X
AF: Graduate School of the Chinese Academy of Sciences, Yuquan Road 18, Beijing, 100039 China
AB: Alpine meadow ecosystem on the Qinghai-Tibetan Plateau, the highest ecosystem in the world, is characterized by strong solar radiation and low temperature. The ecosystem CO2 exchange (NEE) between the atmosphere and ecosystem is controlled by cool temperature, even in growing period. We hypothesized that low temperature may limit the NEE at the alpine ecosystem. We tested this hypothesis by using the CO2 flux data measured by eddy covariance method and other climate variables during the growing season at the alpine meadow ecosystem on the northern edge of the Plateau (lat 37­’36'N, long 101­’18'E, alt. 3250 m). The effect of temperature on the carbon budget of ecosystem was evaluated in the late growing periods for two years. The optimum temperature for the NEE under light saturation conditions was estimated to be around 15›ŚC. The annual NEE estimated from August 9, 2001 to December 31, 2003 was about 290 g CO2 m-2 year-1 despite of the low ecosystem temperature. We found that NEE from August 9 to September 10 in 2001 with low average temperature was greater than that in 2002 with high average temperature during the same period, but ecosystem gross primary production (GPP) was similar during the two periods. Further analysis showed that ecosystem respiration was significantly higher in 2002 than 2001 based on the estimation from the relationship between temperature and ecosystem respiration during nighttime. The ratio of ecosystem respiration (Re) to GPP (Re/GPP) was lower for 2001 than 2002, indicating a higher proportion of ecosystem respiration in GPP in 2002, which may be partly due to the high temperature in 2002 if we assume the temperature dependence of respiration was the same. The results suggest that low temperature controlled the NEE mainly through the influence of temperature on the ecosystem respiration. Keywords: Alpine meadow, Ecosystem CO2 exchange, Ecosystem respiration, Temperature, Qinghai-Tibetan Plateau
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