THE APPLICATION OF THE MODEL NAP TO THE SOLLING SPRUCE SITE

The NAP (Nutrient Availability and Productivity) model is an integrate d forest-soil model for analysing indirect effects of acidification on forest growth. The NAP model is applied here to the Selling spruce si te in Germany. The model was validated and tested for the years 1969-1 990. In addition, two scenarios, one with continuing deposition at the 1990 level and the other with a reduced deposition, were evaluated. T he simulations show that forest growth is strongly enhanced by anthrop ogenic N deposition. Unchanged deposition will lead to a Mg-limited fo rest growth. This growth will be higher than forest growth in an impro ved environment. However, forest growth in the no-reduction scenario i s accompanied by an unbalanced nutritional status, whereas in the impr oved environment the forest has a balanced nutrient status with lower growth and no risks for Mg limitation.