Abstract: Hydrological condition is important for the restoration of drained peatland by affecting both plants and microorganisms. Soil enzymes released by microorganisms are strongly associated with the decomposition of soil organic matter. It is therefore important to understand the impacts of hydrological condition on soil enzyme activities. To reveal the variation patterns of soil enzymes during water table restoration and also the triggers of these variations, soil samples (0-50 cm) were collected from a natural, a drained, and two rewetted areas of the Baijianghe peatland in June 2020. We measured soil physical and chemical properties and the activities of two oxidases (peroxidase and polyphenol oxidase) and three hydrolases (β-1,4-glucosidase, β-1,4-N-acetylglucosaminidase and acid phosphatase). The results showed that the activities of both peroxidase and polyphenol oxidase in 0-50 cm soils from the rewetted areas were significantly lower than those from the drained area. In terms of hydrolases, the activities of both β-1,4-glucosidase and β-1,4-N-acetylglucosaminidase in 0-10 cm soils from the rewetted areas were significantly lower than those from the drained area. Soil enzyme activities in the natural area was mainly affected by soil water content, but mainly affected by soil pH and the contents of total nitrogen and phosphorus in the drained area. Both soil nutrients and water content affected soil enzymes in rewetted areas. Our results indicated that soil enzyme activities were controlled by different factors under different water tables and that the effect of water table on soil enzyme activities was largely dependent on soil depth.

Key words: peatland, drainage, water table restoration, hydrolase, oxidase.