Interactive effects of grazing and global change factors on soil and ecosystem respiration in grassland ecosystems: A global synthesis

摘要

1. As the key carbon (C) fluxes between biosphere and atmosphere, soil respiration (R_s) and ecosystem respiration (R_e) play vital roles in regulating global C balance and climate-biosphere feedback in the Earth system. Despite the fact that numerous manipulative studies and a few meta-analyses have been conducted to examine the responses of R_s and its components (i.e. autotrophic [R_a] and heterotrophic respiration [R_h]) as well as R_e to grazing (G) or global change factors, the interactive effects between grazing and global change factors remain poorly understood. 2. Here, we performed a comprehensive meta-analysis of manipulative experiments with both grazing and global change factors to quantify their individual and interactive effects on R_s and its components as well as R_e. 3. Our results showed that grazing and drought significantly decreased R_s by 12.35% and 20.95%, respectively, whereas warming (W), nitrogen addition (N) and increased precipitation (P) stimulated it by 2.12%, 5.49% and 13.44%, respectively. Similarly, grazing, warming, nitrogen addition and increased precipitation increased R_e by 7.21%, 4.94%, 48.45% and 21.57%, respectively, while drought decreased it by 16.86%. However, the combinations of grazing with warming (GW), nitrogen addition (GN) and increased precipitation (GP) exhibited non-significant effects on R_s. More importantly, additive interactions between grazing and global change factors exhibited a substantial predominance on R_s, R_a, R_h and R_e rather than synergistic and antagonistic ones. 4. Synthesis and applications. Our findings highlight the crucial importance of the interactive effects between grazing and global change factors on soil respiration (R_s) and ecosystem respiration (R_e). Therefore, incorporating this key influence on ecosystem processes into Earth system models (ESMs) could better improve the prediction of climate-biosphere feedbacks and develop sustainable strategies for grassland management in the An