Responses of soil respiration and its components to experimental warming in an alpine scrub ecosystem on the eastern Qinghai-Tibet Plateau.

The responses of soil respiration (Rs) to warming are driven by its components, that is, heterotrophic respiration (Rh) and rhizosphere respiration (Rr, including fine root respiration [Rfr] and rhizomicrobial respiration [Rz]). However, the effects of warming on Rs and its components are rarely studied in alpine scrub ecosystems on the Qinghai-Tibet Plateau. Here, we conducted a warming experiment to examine how Rs and its components respond to experimental warming. We found that one-year experimental warming (increased by 1.3 °C) significantly stimulated the rates of Rs, Rh and Rr by 21.6, 23.8, and 21.1%, respectively. The annual cumulative C effluxes of Rs increased by 87.87 g m-2 with nearly equal contributions from Rh (46.84 g m-2) and Rr (41.03 g m-2) under warming. Moreover, warming-induced increase in Rr mainly resulted from increased Rfr rather than Rz due to the significant increase in fine root biomass and Rfr rate. In addition, the Q10 values for Rs, Rh and Rr were also increased by experimental warming, while the contribution of Rh to Rs was not altered by experimental warming. Collectively, our results suggest that future climatic warming will stimulate more C releases from soil to the atmosphere through an enhancement of both Rh and Rr in these alpine scrub ecosystems on the Qinghai-Tibet Plateau.