EFFECTS OF AIRBORNE SEA SALTS ON SOIL-WATER ACIDIFICATION AND LEACHING OF ALUMINUM IN DIFFERENT FOREST ECOSYSTEMS IN DENMARK

Studies on biogeochemical cycling of elements are performed in even ag ed forest ecosystems of Norway spruce, Sitka spruce and beech at sever al locations in Denmark. Episodes with high sea salt deposition and un usual low water surplus percolation caused extreme salt concentrations in the soil solutions. The changes were smallest beneath beech stands and most pronounced at the most salt-affected Sitka spruce stands. Co ntemporary, the pH drops and the Al3+ concentration increased above 20 mg L(-1) owing to cation exchange with Na+. The Cl- and Al3+ concentr ations reached levels reported as toxic for Norway spruce, but not for Sitka spruce and beech. The changes in the soil water chemistry must be considered as important factors for the reduced vitality in Norway spruce ecosystems in Denmark.