The modul MERLIN applied to Nordmoen, Norway

Abstract

The process-oriented dynamic model, MERLIN, is been used to predict N leaching and risk of "N saturation" at the experimental field at Nordmoen, Norway. The model was calibrated to the period 1957 to 1987, and then compared to observed data from 4 years of experimental addition of N at 20 kg N ha2 yr1 (above ambient 11 kg N ha2 yr 1). The calibrated model was used to predicts future trends in N leaching. MERLIN gave acceptable simulation of the increased N leaching observed in the N addition experiment. The model predicts that with ambient deposition there will be no significant leaching of N within the next 60 years the forest is not at risk for N-saturation. With ambient N load the model precited the C:N ratio in forest floor to remain above 30. The enhanced deposition, on the other hand, is predicted to lead to significant increased NO3 in leachate and a drop in the C:N ratio to below 25 after about 30 years. The critical load for nitrogen for this ecosystem is thus predicted to lie between 11 and 31 kg N ha2 yr1.