N storage and cycling in vegetation of a forested wetland: Implications for watershed N processing

Pools and fluxes of N in wetland vegetation and soils were compared with an adjacent upland site to assess the relative importance of wetland versus upland landscapes in watershed N-retention in the Adirondack Mountains of New York (U.S.A.). The majority of N storage occurred in forest soils and wetland peat deposits (96 and 99% of total N in upland forests and wetlands, respectively). Annual N-uptake (49 kg N ha(-1) yr(-1)) was greater for wetland vegetation than that of upland vegetation (30 kg N ha(-1) yr(-1)). In the wetland the supply of N from mineralization (36 kg N ha(-1) yr(-1)) was less than N-uptake; in contrast, upland N mineralization (76 kg N ha(-1) yr(-1)) exceeded N vegetation uptake. Annual N-storage in peat was small due to low peat accretion rates. Wetlands acted as a sink for N and stored a disproportionally high fraction (15%) of catchment N in relation to their relatively small surface area (similar to4%) within the catchment.