CRITICAL LOADS OF ACIDITY AND NITROGEN, BASED ON MULTIPLE CRITERIA FOR DIFFERENT SWEDISH ECOSYSTEMS

The critical loads of acidity and nitrogen has been mapped for Swedish forest soils, using data from the Swedish Forest Inventory. The Swedi sh critical load map used in negotiations has been based on a number o f ecological receptors. For terrestrial ecosystems criteria based on n o adverse effect on growth, soil stability and groundwater quality was used. For surface waters, stream and lake biology was used as indicat ors for setting limits to acidification. A reduction of 75% of the aci dity deposition in relation to 1988 is required in order to protect 95 % of the forest resource in Sweden from effects of soil acidification. A reduction of 50% of the nitrogen deposition is required to avoid ex ceedance in more than 5% of the area. The mapping work was carried out by using the PROFILE model.