Effects of nitrogen input on global warming potential of natural wetlands and paddy fields

Purpose Nitrogen (N) addition significantly impacts greenhouse gas emissions, yet differential response mechanisms between natural wetlands and paddy ecosystems remain poorly understood. This study elucidates these ecosystem-specific variations and their underlying driving factors. Methods A 28-day laboratory incubation was conducted using soils from Shengjin Lake natural wetlands and adjacent paddy fields across four N levels: 0.00, 3.90, 7.80, and 15.60 g·m − 2 ·yr − 1 . Cumulative methane (CH 4 ), carbon dioxide (CO 2 ), and nitrous oxide (N 2 O) emissions were measured, and Structural Equation Modeling was used to identify regulatory pathways for comprehensive global warming potential (CGWP). Results Paddy soils exhibited higher cumulative CH 4 and CGWP than natural wetlands. N addition suppressed CO 2 emissions in wetlands but induced a priming effect in paddies. N 2 O emissions increased linearly in wetlands but showed significant temporal lags in paddies. SEM indicated that wetland CGWP was primarily regulated by nitrate nitrogen via pH and urease. In contrast, paddy CGWP was driven by a multifactorial network characterized by intensive nitrogen transformations involving pH dynamic fluctuations, soil organic matter and nitrate nitrogen, while cellulase activity showed a significant negative correlation with CGWP. Conclusion Paddy ecosystems exhibit higher sensitivity to N input and greater climate feedback risks. These findings support differentiated N management and precision agriculture to mitigate climate pressure while preserving the ecological resilience of natural wetlands. Graphical