Acid deposition, land-use change and global change: MAGIC 7 model applied to Aber, UK (NITREX project) and Risdalsheia, Norway (RAIN and CLIMEX projects)

Nitrogen processes are now included in a new version of MAGIC (version 7), a process-oriented catchment-scale model for simulating runoff chemistry. N et retention of nitrogen (N) is assumed to be controlled by plant uptake an d the carbon/nitrogen (C/N) ratio of soil organic matter, the latter as evi denced by empirical data from forest stands in Europe. The ability of this version of MAGIC 7 to simulate and predict inorganic N concentrations in ru noff is evaluated by means of data from whole ecosystem manipulation experi ments at Aber, Wales, UK, (nitrogen addition as part of the NITREX project) and Risdalsheia, Norway (exclusion of acid deposition as part of the RAIN project and climate change as part of the CLIMEX project). MAGIC 7 simulate d the changes in N leaching satisfactorily as well as changes in base catio ns and acid neutralising capacity observed at these two sites. MAGIC 7 offe rs a potential tool for regional assessments and scenario studies of the co mbined effects of acid deposition, land-use and climate change.