Maps of critical loads and exceedance for sulfur and nitrogen to forest soils in Norway

We use the dynamic MAGIC model to calculate critical loads of sulfur and nitrogen for forest soils in Norway. Inputs include the soil surveydata of NIJOS and NISK, the atmospheric deposition data of NILU, the forest productivity data of NIJOS, and the surface water chemistry of NIVA. Two scenarios for future sulfur deposition are used with two scenarios of nitrogen retention in catchments. The magnitude and patterns of calculated nitrogen critical loads and exceedance differ substantially depending on the scenario chosen for sulfur deposition and nitrogen retention. In worst case critical loads for N are low and exceed in southernmost Norway. In the best case critical loads for N are high and not exceeded. More information on the processes controlling N retention in forested ecosystems is of outmost importance for the specification of nitrogen critical loads