James A. Entry, William H. Emmingham 1
Riparian forests have been shown to filter nutrients from agricultural runoff and groundwater flow. We measured the storage and extractability of nitrogen and phosphorus in the organic layer and top 10 cm of mineral soil in riparian areas supporting coniferous, deciduous and grassland vegetation each season. In autumn and winter, the concentration of total N in the organic layer was higher in the deciduous forest and grassland than the coniferous forest. In autumn and winter, the concentration of total N in mineral soil was higher in coniferous and deciduous forests than grasslands. Coniferous and deciduous forests stored more kg N and P in the organic layer than grasslands. In autumn and winter, more NH4, NO3, and P was extracted from mineral soil in grasslands than from soils of coniferous or deciduous forests. Larger amounts of NH4 and NO3 were extracted from the organic layer of deciduous than coniferous forests. Our results indicate that coniferous and deciduous forests store more N and P in the organic layer than grassland vegetation. We did not find any significant differences in N and P storage between conifer and deciduous forests. Forest ecosystems may create riparian filterstrips capable of removing more N and P from agricultural runoff and subsurface flow than grassland ecosystems.
