Map of critical loads (sulphur) for coniferous forest soils in Norway

Abstract

Maps of critical loads of acidity and exceedance (sulphur) for coniferous forest soils in Norway have been compiled using the dynamic MAGIC model based on the soil survey data of NIJOS and NISK, the atmospheric deposition data of NILU, the forest productivity data of NIJOS, and the surface water chemistry data base of NIVA. The criterion used was that the Ca/Al molar ratio in soil solution should not fall beneath 1.0 in the uppermost 50 cm of soil. Scenarios were run 50 years into the future under the assumptions that nitrogen deposition and nitrogen retention are unchanged relative to the present. The results show that the critical load for soils is higher than the critical load for water (i.e soils are less sensitive). Critical loads for soils are exceeded by present-day sulphur deposition in many squares in southernmost Norway. There are indications that crown density of spruce stands in these squares in also lower than in nearby squares in which the critical load is not exceeded.