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.

土壤动物群落(soil fauna communities)是湖泊湿地生态系统(lake wetland ecosystems)与土壤食物网(soil food webs)的关键组成部分；然而，当前学界对湿地生态系统中植被类型转换后，土壤动物如何调控温室气体(Greenhouse Gas, GHG)排放的认知仍较为有限。
本研究选取中国洪泽湖湿地的不同植被类型，包括人工林、天然林以及湖滨滩地(lake shoal)。我们分析了土壤理化性质、CO₂、CH₄与N₂O的排放通量，以及土壤动物群落特征，包括丰度、多样性与功能物种(functional species)。本研究旨在探究由土壤动物调控的温室气体排放如何响应植被类型转换。
研究结果显示，人工杨树林与柳树林的CO₂排放量（分别为1440 mg·m⁻²·h⁻¹与1231 mg·m⁻²·h⁻¹）高于天然林与湖滨滩地（分别为596 mg·m⁻²·h⁻¹与965 mg·m⁻²·h⁻¹）。人工林与天然林内的土壤动物丰度与生物多样性均显著高于湖滨滩地（P < 0.05）。腐食性类群(saprophagous group)为人工林与天然林的优势功能类群，占土壤动物总群落的55.8%~81.8%。0~50 cm土层的土壤有机碳储量在人工林与天然林中显著高于湖滨滩地（P < 0.05）。
植被类型转换、土壤环境与土壤动物直接影响CO₂排放。此外，土壤环境与土壤碳氮比可通过土壤动物间接调控CO₂排放。
本研究结果深化了学界对土壤动物群落调控温室气体排放机制的整体认知，可为淡水湖泊生态系统的温室气体排放调控与管理提供全新视角。