Abstract: Wetland, as an important carbon pool, plays an important role in global carbon cycling. Variations in greenhouse gas fluxes from wetlands are of significant importance for understanding wetland carbon budget and assessing their climate change mitigation potential. In this study, taking Xixi wetland as the object, four land types (arbor land, arbor-shrub grassland, shrub grassland, and reed grassland) and three aquatic types (water course, pond, and shoal) were selected for in-situ monitoring of greenhouse gas fluxes via static chamber combined with gas chromatography for one year from June 2023 to May 2024. The results showed that greenhouse gas fluxes exhibited significant spatiotemporal variations. Among the four land types, the monthly average CO₂ fluxes were the highest in reed grasslands (557.71 mg·m^-2·h^-1), which was significantly higher than other types (P<0.05). The overall emission fluxes from aquatic types were lower than those from land types. N₂O flux showed a dual source-sink pattern. Reed grasslands acted as a strong emission source (54.34 μg·m^-2·h^-1), while arbor-shrub grassland and certain water bodies served as sinks. The CH₄ emission showed extreme variability, with aquatic types being significantly higher than that of land types (P<0.05), and the highest flux was observed in shoals, reaching 7720.23 μg·m^-2·h^-1. The greenhouse gas fluxes in land systems were positively correlated with environmental factors such as soil temperature and moisture content (P<0.05), while the aquatic systems exhibited a multi-factor nonlinear response pattern. This study systematically analyzed the microhabitat differentiation patterns of wetland greenhouse gas emissions, and revealed the key environmental driving mechanism, providing a scientific basis for accurately assessing the carbon sink function of subtropical urban wetlands.

Key words: wetland, greenhouse gas emission flux, land type, aquatic type