Abstract: Aims Understanding the characteristics of methane fluxes in temperate wetland ecosystems and elucidating the regulatory mechanisms of environmental factors on CH4 flux are crucial for improving our comprehension of wetland methane emissions and providing a scientific basis for predicting and managing wetland greenhouse gas emissions under the context of global climate change. Methods This study was conducted in 2024 in the Hanshiqiao Wetland ecosystem, located in Shunyi District, Beijing. Using the eddy covariance (EC) method, in situ continuous monitoring of methane fluxes in the wetland was carried out. Simultaneously, environmental factors such as air temperature (Ta), vapor pressure deficit (VPD), photosynthetically active radiation (PAR), and normalized difference vegetation index (NDVI) were monitored. Path analysis and multiple regression methods were employed to investigate the seasonal variation characteristics of methane fluxes and their influencing factors. Important findings In 2024, the cumulative CH4 emission from the Hanshiqiao wetland was 28.32 g·m-2. The daily variation showed an inverted "U" shape, with daytime emissions higher than nighttime, peaking at noon. The methane emissions exhibited distinct seasonal variation, presenting an inverted "U" shape, with methane emissions during the growing season (April-October) amounting to 27.04 g·m-2, accounting for 95% of the annual total. Path analysis revealed that Ta was the dominant factor influencing CH4 flux during the growing season (direct path coefficient 0.697), while PAR and NDVI also had direct positive effects (both 0.197). Additionally, both factors enhanced CH4 flux indirectly through separate pathways (indirect path coefficients of 0.301 and 0.374, respectively). VPD significantly influenced the seasonal variation of CH4 flux through indirect effects (indirect path coefficient 0.495). During the non-growing season, PAR had the most prominent impact on CH4 flux (direct path coefficient 0.146), while the effects of other environmental factors were relatively weaker. The seasonal fluctuations in CH4 flux of the Hanshiqiao wetland ecosystem are primarily controlled by the synergistic effects of Ta, PAR, and NDVI. Among these, Ta exhibits the strongest correlation with CH4 flux during the growing season, serving as an effective predictive variable for emissions in this period. In contrast, environmental factors have a weaker influence during the non-growing season. The results of this study provide scientific insights for understanding the carbon cycling process in temperate wetlands and their environmental impact mechanisms, and they have important implications for regional wetland management and greenhouse gas reduction policies.

Key words: wetland, methane flux, environmental factors, path analysis