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

Abstract

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.