Response of ecosystem respiration to experimental warming and clipping in Tibetan alpine meadow at three elevations

Abstract. This study aims to understand the response of ecosystem respiration (R_eco) to warming and clipping in the alpine meadow of Tibet. A field warming experiment using open top chambers was conducted in three alpine meadow sites at elevation 4313 m, 4513 m and 4693 m on the Tibetan Plateau since July 2008. Clipping was conducted three times a year since 2009. R_eco was measured from June to September in 2010–2012. For most cases, the seasonal variation of R_eco was mainly affected by soil water content rather than soil and air temperature, especially under warmer environment. Experimental warming tended to decrease seasonal average R_eco by 21.6% and 10.9% at elevation 4313 m and 4513 m, respectively, but significantly increased seasonal average R_eco by 11.3% at elevation 4693 m. The different responses of R_eco to experimental warming could be mainly dependent on temperature and water availability condition. Clipping decreased seasonal average R_eco by 6.9%, 36.9% and 31.6% at elevation 4313 m, 4513 m and 4693 m. The consistent declines caused by clipping may be mainly attributed to clipping-induced decline in aboveground biomass. Our findings suggested that the response of R_eco to warming differed among the alpine meadow and was regulated by soil water content on the Tibetan Plateau.