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

A model describing carbon, nitrogen and phosphorus dynamics and their inter actions in riverine wetlands was developed to: (1) investigate the nature o f the interactions between the C, N and P cycles; (2) study the role of pro cesses in the vegetation and in the soil; (3) study the way in which these processes and interactions are governed by major controlling variables (tem perature and wetness of the soil); (4) quantitatively assess nutrient-relat ed functions in river marginal wetlands; and (5) simulate the effects of ma nagement and other human influences in (or outside) the wetland on these fu nctions. The model distinguishes several plant and soil compartments and al lows for grazing by large herbivores. One of the main features of the model is a factor called 'mode', which influences most processes rates. This des cribes soil redox potential, water table and soil oxygen content. Sensitivi ty 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 miner alisation and immobilisation. The model was applied to a slope at Kismeldon Meadows, Devon, southwestern England, and showed a good fit to field data. (C) 1999 Elsevier Science B.V. All rights reserved.