Methane (CH₄) emission and environmental controls of CH₄-cycling microorganisms are unclear in inland floodplains. Here, we examined soil CH₄ emissions and the community composition of CH₄-cycling microorganisms under three vegetation types—mudflat (MF, no vegetation cover), Carex meadow (CM, mainly Carex brevicuspis), and reed land (RL, mainly Miscanthus sacchariflorus)—from water-adjacent areas to higher-elevation land in the Dongting Lake floodplain, China. The results showed that CH₄ emission is the highest in CM, while significant absorption was observed in the RL site. The abundance ratio of methanogen/methanotroph was the highest in CM, intermediate in MF, and lowest in RL. The Methanosarcinaceae family represented the dominant methanogens in the three sampling sites (41.32–75.25%). The genus Methylocystis (60.85%, type II methanotrophs) was dominant in CM, while Methylobacter and Methylosarcina (type I methanotrophs) were the dominant genera in MF (51.00%) and RL (50.24%), respectively. Structural equation model analysis showed that methanogen and methanotroph abundance were affected by water table depth, soil water content, and pH indirectly through soil organic content, total nitrogen, microbial biomass carbon, and microbial biomass nitrogen. These results indicated that the Dongting Lake floodplain may change from a CH₄ source to a CH₄ sink with vegetation succession with an increase in elevation, and the methanogen/methanotroph ratio can be used as a proxy for CH₄ emission in wetland soils. The continuous increase in reed area combined with the decrease in Carex meadow may mitigate CH₄ emission and enhance the CH₄ sink function during the non-flood season in the Dongting Lake floodplain.

Identifying ecosystem service trade-offs/synergies and their influencing factors are prerequisites for formulating scientific ecosystem management strategies. We selected Dongting Lake Area as the study area, quantified four key ESs dynamics, including food production (FP), soil conservation (SC), habitat quality (HQ) and ecological leisure (EL), identified relationships between paired ecosystem services using Spearman correlation coefficients, and analyzed how various drivers impact trade-offs and synergies by leveraging spatial panel data models; we also implemented ecosystem management zoning by superposition analysis on ecosystem services, the relationships between these services, and key drivers. The results showed that FC and SC displayed synergy before a trade-off over the period 2000–2022. The FP–HQ and HQ–EL initially displayed synergy, then trade-off, and then synergy again. Spatially, the spatial trade-off ratios of FP–HQ, SC–HQ, and HQ–EL exceeded the synergy ratios, and trade-off areas of FP–HQ, SC–HQ, and HQ–EL existed around Dongting Lake. The direct or indirect effects of DEM, slope, precipitation, and population density have the greatest effect on ecosystem service pairs. Furthermore, the DTLA was divided into ecological unbalance, soil conservation, habitat quality synergy, and ecological leisure areas. These finding may provide critical scientific insights into how to balance ecological conservation and socio-economic progress in the Dongting Lake Area.