Response of ecosystem respiration to experimental warming and clipping at daily time scale in an alpine meadow of tibet

The alpine meadow, as one of the typical vegetation types on the Tibetan Plateau, is one of the most sensitive terrestrial ecosystems to climate warming. However, how climate warming affects the carbon cycling of the alpine meadow on the Tibetan Plateau is not very clear. A field experiment under controlled experimental warming and clipping conditions was conducted in an alpine meadow on the Northern Tibetan Plateau since July 2008. Open top chambers (OTCs) were used to simulate climate warming. The main objective of this study was to examine the responses of ecosystem respiration (R (eco) ) and its temperature sensitivity to experimental warming and clipping at daily time scale. Therefore, we measured R (eco) once or twice a month from July to September in 2010, from June to September in 2011 and from August to September in 2012. Air temperature dominated daily variation of Reco whether or not experimental warming and clipping were present. Air temperature was exponentially correlated with R (eco) and it could significantly explain 58 similar to 96% variation of R (eco) at daily time scale. Experimental warming and clipping decreased daily mean R (eco) by 5.8 similar to 37.7% and -11.9 similar to 23.0%, respectively, although not all these changes were significant. Experimental warming tended to decrease the temperature sensitivity of R (eco) , whereas clipping tended to increase the temperature sensitivity of R (eco) at daily time scale. Our findings suggest that R (eco) was mainly controlled by air temperature and may acclimate to climate warming due to its lower temperature sensitivity under experimental warming at daily time scale.