Soil bacteria, archaea, and enzymatic activity of natural and rewetted peatlands display varying patterns in response to water levels

Peatland restoration is an efficient approach to enhance soil carbon sequestration and mitigate climate change. However, successful restoration outcomes require an in-depth comprehension of the underlying soil ecological processes following restoration. To gain a processed perspective on the distinctions between natural and rewetted peatlands, this study compared the soil properties, enzymatic activities, and bacterial and archaeal community structures under uniform water level gradients. The results confirmed our hypothesis that the ecological processes between rewetted and natural peatlands vary significantly. Although the rewetted peatland exhibited different soil properties compared to the natural peatland, increasing water levels resulted in a shift in soil physicochemical properties and hydrolase activities toward those of the natural peatland. This highlights the importance of maintaining a high water level for successful peatland restoration. However, enzymatic activities in the rewetted and natural peatlands exhibited opposite trends with increased water levels, with the natural peatland exhibiting lower polyphenol oxidase activity (-56.7%), higher archaeal diversity (7.3%) and lower bacterial diversity (-2.1%). As the water level increased, ecological processes in the natural peatland shifted from bacteria-dominated faster processes to archaea-dominated slower processes, while no such trends were observed in the rewetted peatland. The study suggest that the lower pH and more restrictive nutrient conditions in the natural peatland, which were altered by rice cultivation with fertilization and vegetation deterioration in the rewetted peatland, may contribute to the biological differences between the two peatland types. These differ-ences may hinder the restoration process after rewetting. Therefore, to enhance the effectiveness of peatland restoration, particularly in the context of rich fens, it is necessary to consider measures that can promote the development of a nutrient-limited and acidic environment aside from rewetting.

Automated summary

Peatland restoration is important for soil carbon sequestration and climate change mitigation, but successful outcomes require understanding of the soil ecological processes. This study compared soil properties, enzyme activities, and bacterial and archaeal communities in rewetted and natural peatlands. Results showed significant differences between these two types of peatlands. Increasing water levels in rewetted peatlands shifted soil properties and enzymatic activities towards natural peatlands. However, enzymatic activities exhibited opposite trends with increased water levels in the two types of peatlands. Differences in pH and nutrient conditions may contribute to the biological differences between rewetted and natural peatlands, hindering restoration after rewetting. Therefore, it is important to consider measures that promote a nutrient-limited and acidic environment for effective peatland restoration.