SIMULATION OF SOIL RESPONSE TO ACIDIC DEPOSITION SCENARIOS IN EUROPE

The chemical response of European forest soils to three emission-deposition scenarios for the years 1960-2050, i.e. official energy pathways (OEP), current reduction plans (CRP) and maximum feasible reductions (MFR), was evaluated with the SMART model (Simulation Model for Acidification's Regional Trends). Calculations were made for coniferous and deciduous forests on 80 soil types occurring on the FAO soil map of Europe, using a gridnet of 1.0 degrees longitude x 0.5 degrees latitude. Results indicated that the area with nitrogen saturated soils, i.e. soils with elevated NO3 concentrations (> 0.02 mol(c) m(-3)) will increase in the future for all scenarios, even for the MFR scenario. The area with acidified soils, with a high Al concentration (> 0.2 mol(c) m(-3)) and Al/BC ratio (> 1 mol mol(-1)) and a low pH (< 4) and base saturation (< 5%), was predicted to increase for the OEP scenario and to decrease for the MFR scenario. The CRP scenario resulted in a continuous increase in the forested area with an Al/BC ratio above critical values. A small decrease was predicted in the area exceeding a critical Al concentration up to the year 2000 followed by a slight increase after 2000. Areas with very high NO3 and Al concentrations mainly occurred in western, central and eastern Europe. Uncertainties in the initial values of C/N ratios and base saturation, and in the description of N dynamics in the SMART model had the largest impact on the temporal development of forested areas exceeding critical parameter values. Despite uncertainties involved, predicted general trends are plausible and reliable.