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EAFES Symposium ES03-7

Effect of experimental warming and altered precipitation on carbon cycle in an alpine meadow

HE Jingsheng (Peking University, China)

Climate warming will probably have large impacts on carbon fluxes in high-altitude alpine grassland ecosystems. An infrared heater temperature enhancement system has been established since June 2006 in an alpine grassland ecosystem at the Haibei Alpine Grassland Ecosystem Research Station, Chinese Academy of Sciences. We tested the hypothesis that experimental warming increase soil respiration because of the high temperature sensitivity at high altitude ecosystems. Soil respiration was measured once per hour using eight-channel automated soil CO2 flux system (Li-8150, Li-Cor, Inc, Lincoln, Nebraska, USA) since 1st June 2008. The results showed that total growing season (June to September) soil respiration was 434 and 498 g C m-2 in control plots for 2008 and 2009, respectively. Experimental warming for about 2 degrees in 5 cm soil depth did not significantly affect total soil respiration in 2007 and 2008, but slightly decreased soil respiration in 2009. Across 2007 and 2008, with continuous monitoring of soil moisture, we found experimental warming significantly decreased soil volume water content. Thus, contrary to our hypothesis, experimental warming does not increase soil respiration at high altitude ecosystems on the Tibetan Plateau, probably because of the balance of the positive effect of temperature and the negative effect of warming-induced water deficit.