A model of carbon, nitrogen and phosphorus dynamics and their interactions in river marginal wetlands

A model describing carbon, nitrogen and phosphorus dynamics and their interactions in riverine wetlands was developed to: (1) investigate the nature of the interactions between the C, N and P cycles; (2) study the role of processes in the vegetation and in the soil; (3) study the way in which these processes and interactions are governed by major controlling variables (temperature and wetness of the soil); (4) quantitatively assess nutrient-related functions in river marginal wetlands; and (5) simulate the effects of management and other human influences in (or outside) the wetland on these functions. The model distinguishes several plant and soil compartments and allows for grazing by large herbivores. One of the main features of the model is a factor called ‘mode’, which influences most processes rates. This describes soil redox potential, water table and soil oxygen content. Sensitivity analysis showed that the most sensitive areas in the model coincide with the main interactions between C and other nutrient cycles. These are plant growth, as influenced by nutrient content of the plant, and decomposition of soil organic matter, which is coupled with nitrogen and phosphorus mineralisation and immobilisation. The model was applied to a slope at Kismeldon Meadows, Devon, southwestern England, and showed a good fit to field data.