Effect of Water Table Restoration on Microbial Communities and Enzyme Activities in Drained Peatland

Hydrological conditions are critical for restoring drained peatlands, and peat microorganisms are highly sensitive to environmental changes. This study investigated the effects of water table (WT) restoration on peat microbial communities and enzyme activities in the Baijianghe peatland of the Changbai Mountains. Peat samples from 0 to 50 cm depths were collected from natural, drained, and rewetted areas to analyze physicochemical properties, phospholipid fatty acids (PLFAs), and enzyme activities (two oxidases and three hydrolases). Key findings revealed that microbial communities and enzyme activities varied significantly among the three areas and across different peat depths. Rewetting reduced oxidases, whereas it increased hydrolase activities in the oxic zone, while transitional and anoxic zones exhibited intermediate oxidases between drained and natural areas. WT restoration significantly increased microbial biomass and altered community structure, with higher total PLFAs, fungal, actinomycetes, and G⁻ bacterial PLFAs in the oxic zone of the rewetted area. Phenolics and WC were the primary regulators of peat organic carbon (OC) accumulation, controlling C limitations for microbial activities. Notably, rewetting increased peat OC and active OC contents, primarily due to changes in water content (WC) and microbial biomass. These findings provide critical insights into the mechanisms driving peatland restoration and underscore the potential of rewetting to enhance carbon sequestration and restore ecological functions.