Nitrogen and phosphorus mineralization in three wetland types in Southeast Alaska, USA

To improve our ability to predict how different wetland soils cycle nutrients, it is necessary togain an understanding of N and P net mineralization rates. Since information on mineralization rates insoutheast Alaska is limited, this study will improve our ability to predict how different wetlands affectsoil nutrient processing. Net N and P mineralization rates were measured both in situ and via labincubations to evaluate both actual and potential mineralization rates in three wetland types: bogs;forested wetlands; and riparian wetlands. Soil pH was an important controlling variable for both net Nand P mineralization rates and soil phosphorus content significantly influenced net P mineralizationrates. In situ net mineralization rates ranged from 410–1,710 mg N kg soil21 day21 for N and from 2–27 mg P kg soil21 day21 for P after 56 days. Lab incubations revealed mineralization potentials were 2–3times greater than in situ rates. Net N and P mineralization potentials were greatest in the riparianwetlands and were significantly different from the bogs and forested wetlands. In contrast, the bogsmineralized a greater proportion of the total N and P soil pool (mg nutrient mineralized per gramnutrient) and indicates greater internal nutrient cycling within bogs. These results suggest that differentwetland types of southeast Alaska process N and P differently and these wetland types should beevaluated separately in future evaluations of wetland ecosystem function.