15. Effects Evaluation and Risk Assessment of Air Pollutants Deposition at European Monitoring Sites of the ICP Forests

The study presents modelled critical deposition load exceedances for over 4,700 representatively selected forest plots in 21 European countries. It is based on measured soil data, different deposition scenarios and an application of the Simple Mass Balance (SMB) model. Effects of climate change on critical loads and exceedances are presented for 108 intensive monitoring plots in 17 countries. Results suggest hardly any more exceedances of critical loads for acidity in the near future. In contrast, even a maximum feasible emission reduction scenario which will leave 10 % of the forest sites unprotected against nitrogen effects by the year 2020. Full implementation of existing clean air legislation will result in 20 % of unprotected forest sites. Forests are less sensitive compared to other ecosystems as for these areas with exceedances are up to 58 %. Under a climate change scenario, decreasing critical loads suggest increasing sensitivity towards nutrient nitrogen inputs. When comparing critical load exceedances over the period 2020–2100, the share of ‘safe’ sites is assumed to decrease from 60 % (constant climate) to 50 % (climate change).