Differential responses of ecosystem respiration components to experimental warming in a meadow grassland on the Tibetan Plateau

Global warming is anticipated to have profound effects on terrestrial carbon fluxes and thus feed backs to future climate change. Ecosystem respiration (R_eco) is one of the dominant components of biosphere CO₂ fluxes, but the effects of warming on R_eco are still unclear. A field warming experiment using open top chambers (OTCs) was conducted in a meadow grassland on the Tibetan Plateau to study the effects of warming on the components of R_eco. Warming significantly enhanced above-ground plant respiration (R_agb) and total autotrophic plant respiration (R_plant) by 28.7% and 19.9%, respectively, but reduced heterotrophic respiration (R_h) by 10.4%. These different responses resulted in the insensitive responses of R_eco and soil respiration (R_s) to the experimental warming. The warming treatment also increased R_plant/R_eco and R_agb/R_eco by 8.4% and 17.3%, respectively, while decreasing R_h/R_eco by 19.0%, suggesting that warming could eventually cause R_eco to be dominated by R_plant. Enhancements in R_plant and R_agb were related to the warming-induced increases in aboveground biomass (AGB) while reduced R_h was closely coupled with warming-induced decrease of microbial biomass carbon. Our results highlight that the differential responses of the components of R_eco to different environmental physics under warming scenarios should be taken into consideration to project the future carbon-climate feed backs.