Asymmetric responses of soil bacterial community and soil respiration to precipitation changes: A global meta-analysis

Changes in the frequency and intensity of precipitation altered the hydrological features, thereafter greatly affecting carbon (C) cycling in terrestrial ecosystems. Soil bacteria are pivotal drivers of the global C cycle in terrestrial ecosystems; however, the responses of soil bacterial communities and the C-cycle they regulated to precipitation changes remain unclear. Here, we conducted a global meta-analysis using 98 paired observations from 58 studies to explore the responses of soil bacteria (abundance and diversity) and their C-related functions (soil respiration) to increased/decreased precipitation. We found that the response of soil bacterial abundance was linearly correlated with precipitation changes, while the response of soil respiration was negatively asymmetric (concave-down). The relationship among soil bacterial abundance, alpha diversity, and soil respiration was weakened by decreased precipitation, indicating that decreased precipitation exhibited a stronger effect on soil bacterial community and soil respiration. Our study extends the understanding of soil bacteria and their functions in response to precipitation change and facilitates the prediction of soil carbon cycle-related functions by using soil microorganisms in terrestrial ecosystem models under future precipitation scenarios.