Responses of greenhouse gas emissions to increased precipitation events in different ecosystems

Climate change is altering precipitation patterns, which can stimulate carbon (C) and nitrogen (N) cycling processes in terrestrial ecosystems, potentially leading to increased soil greenhouse gas (GHG) emissions. However, a systematic understanding of how soil GHG fluxes respond to both increased precipitation (IP) and extreme precipitation (EP) across diverse global ecosystems is still lacking. To address this knowledge gap, we conducted a global meta-analysis based on data extracted from 49 published studies. Our objectives were to quantify the effects of IP and EP on fluxes of CO₂, CH₄, and N₂O, and to explore the key driving factors behind these responses. The results revealed that: (1) IP significantly enhanced soil CO₂ emissions by 10.2% and N₂O emissions by 61.7%, but had no significant effect on CH₄ fluxes. In contrast, EP significantly increased emissions of N₂O (by 61.8%), CO₂ (by 13.3%), and CH₄ (by 3.2%). (2) Ecosystem type mediated the GHG response under IP treatment (P < 0.01). Among grasslands, forests, and farmlands, the forest ecosystem showed the highest response ratios for CO₂ (30.4%), N₂O (61.8%), and soil respiration (37.5%), while grasslands exhibited the lowest responses. (3) Variation in CO₂ flux was primarily associated with soil dissolved organic carbon and microbial biomass carbon (both P < 0.001), whereas changes in N₂O flux were most strongly linked to soil NH₄⁺-N content (P < 0.001). This study synthesizes global experimental data to clarify the distinct impacts of IP and EP on GHG emissions, highlighting the critical role of ecosystem-specific traits and soil biogeochemical properties. Our findings provide an integrated perspective for predicting soil-climate feedbacks under future precipitation regimes.