Precipitation as the Key Regulator of Acid Rain Inhibition on Forest Soil Organic Carbon Decomposition: A Global Meta-Analysis for Sustainable Ecosystem Management

Acid rain poses a significant threat to forest ecosystems globally, with substantial impacts on soil organic carbon decomposition. This study employs a meta-analysis of 361 datasets from 63 published studies to investigate the response of SOC decomposition in forest ecosystems to acid rain. Our analysis reveals that acid rain has a significant inhibitory effect on SOC decomposition. Precipitation emerges as a crucial large-scale environmental factor that differentially modulates this effect; it alleviates acid rain’s suppressive impact on litter decomposition by diluting H+ ions but intensifies the inhibition of soil decomposition due to the soil’s strong adsorption capacity. Furthermore, our results indicate that acid rain exerts a more pronounced inhibitory effect on soil organic carbon decomposition than on litter decomposition. Compared to small-scale factors, precipitation plays a more significant role in regulating the inhibitory effects of acid rain on organic carbon decomposition. These findings underscore the need to integrate precipitation into carbon-cycle models and tailor management strategies to specific climates for sustainable forest carbon management. It also provides a theoretical foundation for predicting the response of forest carbon decomposition to environmental change and for balancing ecological protection with sustainable development in acid rain-impacted regions.