Soil fauna modulates the response of soil greenhouse gas emissions to vegetation type conversion in a freshwater lake ecosystem

Soil fauna communities are a key component of lake wetland ecosystems and soil food webs; however, our understanding of how soil fauna modulates GHG emissions following vegetation type conversion in wetland ecosystems remains limited. In this study, we selected different vegetation types in the Hongze Lake Wetland (China), including artificial and natural forests, and lake shoal. We analyzed soil physicochemical properties, emission fluxes of CO2, CH4, and N2O, and soil fauna community attributes, including abundance, diversity, and functional species. The objective was to examine how GHG emissions, as regulated by soil fauna, respond to vegetation type conversion. Results showed that CO₂ emissions were higher in artificial polar and willow forests (1440 mg·m-2·h-1 and 1231 mg·m-2·h-1) than in natural forests and lake shoal (596 mg·m-2·h-1 and 965 mg·m-2·h-1). Soil fauna in artificial and natural forests exhibited relatively higher abundance and biodiversity compared to those in LS (P < 0.05). Saprophagous represented the dominant functional species across artificial and natural forests, accounting for 55.8%–81.8% of the total soil fauna communities. Soil organic carbon storage in the 0–50 cm soil depth was significantly greater in artificial and natural forests than in lake shoal (P < 0.05). Vegetation type conversion, soil environment, and soil fauna directly influenced CO₂ emissions. Furthermore, soil environment and soil carbon/nitrogen indirectly affected CO₂ emissions via soil fauna. Our findings enhance the broader understanding of the regulatory mechanisms through which soil fauna communities modulate GHG emissions. This study will provide novel insights for the regulation and management of GHG emissions in freshwater lake ecosystems.