Phosphatase Activity Along Soil C and P Gradients in a Reed-Dominated Wetland of North China

Previous studies in oligotrophic wetlands showed that phosphatase activity (PHA) was positively related to soil total phosphorus (TP) content, and that PHA can serve as a predictor of wetland degradation. However, phosphatase dynamics are poorly known for eutrophic wetlands, where anthropogenic nutrient inputs elevate soil P content. We reported variations in PHA along a nutrient content gradient in soils of the eutrophic Baiyangdian wetland in North China. Soil PHA mainly responded to the soil organic carbon (C) content, and microbial biomass carbon. A positive correlation existed between PHA and C but not between PHA and TP in the wetland soils. The Baiyangdian wetland has high soil P content, averaging 598 mg kg(-1). The high TP content caused the lower mass ratios between sediment C and TP (C:TP) that are lower than those reported in many wetlands. Results suggest that there may be a TP threshold above which PHA has no relationship with TP. A laboratory incubation study showed that PHA increased with added C, suggesting that the soil C content was a limiting factor for P mineralization in the Baiyangdian wetland. PHA, together with its limiting factors, could reflect the state of eutrophication of the wetland.