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Mass Balance Of 13C To Reveal Carbon Budget Under Imitating Global Warming Treatment At Alpine Meadow Ecosystem

Xianfeng Yi, Yueqin Yang

Open-top chamber (OTCs) introduced by International Tundra Experiment(ITEX) were conducted to simulate and determine the possible effects of imitating global warming on 13C values of soil organic C and C flux at the Haibei Alpine Meadow Ecosystem Research Station of Chinese Academy of Sciences. The preliminary results indicated that 13C values increased with increasing soil depth, however, the contents of organic C decreased. 13C values of soil organic C tended to averagely decrease by about 0.99±0.62‰ under the open-top chamber treatments, total organic C was averagely lost by 11.78 mg/g compared with the control. Open-top chamber treatments, which increased air and soil temperatures in plots by about 4 0C and 10C respectively, enhanced decomposition rate of soil organic C (or rate of soil respiration) and primary productivity by 1.446 and 1.035 times respectively. Preliminary data also suggested that open-top chamber treatments would generate a positive feedback, i.e., higher level of CO2 emission of the alpine meadow to climate warming. The C flux at the alpine meadow ecosystem would remain a net source under the future global warming as revealed by stable carbon isotopic signatures. Stable carbon isotopic technology, which reflects a time-integrated pattern of C flux and neglects short-term variations in CO2 emission, can be used to evaluate C flux at the alpine meadow.