Seasonal phosphorus cycling in a riparian wetland, Grand Valley, Ontario

Abstract

Loss of riparian wetlands is linked to surface water phosphorus (P) pollution. Wetland riparian buffer zones (RBZ) can help to reduce P runoff. The seasonality of P cycling in wetland soils is poorly understood, especially P mobilization in early spring when freeze-thaw cycling (FTC) occurs. Here labile soil P and soil biology are investigated over the spring and in response to FTC. Soil was sampled from a wetland RBZ along the Grand River, Ontario. Soil temperature and conductivity, labile P, microbiome, and microbial biomass-P were quantified over the spring. In the lab, FTC experiments characterized the response of microbial respiration, microbial biomass P, and labile P. Results indicate labile P increased over the spring. In lab, soil labile P increased after 6 FTC compared to control treatments and fewer FTC. Results indicate relatively low risk for FTC to cause increased soil P mobilization in wetland RBZ.