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

Highlights: • Soil respiration components were studied in an alpine scrubland under warming. • Warming equally increased heterotrophic and rhizosphere respiration. • Enhanced rhizosphere respiration resulted from fine root respiration. • Warming did not significantly affect rhizomicrobial respiration. The responses of soil respiration (R_s) to warming are driven by its components, that is, heterotrophic respiration (R_h) and rhizosphere respiration (R_r, including fine root respiration [R_fr] and rhizomicrobial respiration [R_z]). However, the effects of warming on R_s and its components are rarely studied in alpine scrub ecosystems on the Qinghai-Tibet Plateau. Here, we conducted a warming experiment to examine how R_s and its components respond to experimental warming. We found that one–year experimental warming (increased by 1.3 °C) significantly stimulated the rates of R_s, R_h and R_r by 21.6, 23.8, and 21.1%, respectively. The annual cumulative C effluxes of R_s increased by 87.87 g m⁻² with nearly equal contributions from R_h (46.84 g m⁻²) and R_r (41.03 g m⁻²) under warming. Moreover, warming-induced increase in R_r mainly resulted from increased R_fr rather than R_z due to the significant increase in fine root biomass and R_fr rate. In addition, the Q₁₀ values for R_s, R_h and R_r were also increased by experimental warming, while the contribution of R_h to R_s 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 R_h and R_r in these alpine scrub ecosystems on the Qinghai-Tibet Plateau.