Net Ecosystem Carbon Dioxide Exchange in Alpine Meadow of Nagchu Region over Qinghai-Xizang Plateau
ZHU Zhikun
,
HU Zeyong
,
MA Yaoming
,
LI Maoshan
,
SUN Fanglin
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Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China;2. Key Laboratory of Tibetan Environment Change and Land Surface Process, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China;3. University of Chinese Academy of Sciences, Beijing 100049, China
Eddy covariance method was used to measure the net ecosystem CO2 exchange (NEE) between an alpine meadow and the atmosphere at Nagchu station on the central of the Qinghai-Xizang Plateau.The results showed that during the growing season,the maximum CO2 uptake and release rate were 5.3 and 1.7 μmolCO2·m-2·s-1,respectively.Daily integrated NEE reached its peak magnitude of -8.5 gCO2·m-2·d-1 in the mid of July.Annual integrated NEE was -151.5 gCO2·m-2 (-41.3 gC·m-2),indicating this ecosystem was a carbon sink.However,the net carbon sequestration potential was weak compared to the grassland on the eastern plateau.During the pear growing period,the apparent quantum yield α was -0.0255±0.0105 μmolCO2·μmol-1 photons,which was similar to reported results of most C3 grassland under appropriate soil water content.Total daily NEE tended to be higher when day/night temperature difference was greater.The rain pulse occurred during the non-growing season stimulated the ecosystem respiration and had an important influence to the ecosystem carbon balance.