Model application to study the effects of emission reduction scenarios on a forested catchment in Finland

Abstract

SMART2, a revised version of the dynamic soil acidification model SMART, was tested at a forested catchment in Finland. A forest growth routine and a more detailed description of nitrogen processes in soil have been included in SMART2. The aim of the study was to calibrate the model with data set derived from the catchment and to study the model behavior. A prediction of long-term effect of atmospheric deposition, originated from anthropogenic sources, on soil and runoff water was done, giving different scenarios of future deposition of sulphur and nitrogen. The emphasis was put on studying the acidifying effects of the deposition. Another aim of the study was to investigate the representativity otthe catchment compared to a regional map, to which the critical loads of acidity have been calculated at European scale. The scenario runs showed a decline in soil base saturation and, surface water pH in response to the rapid increase of acidifying deposition due to increased emissions starting in 1960's. With the studied reduction strategies, environment deterioration can be stopped and the recovery will begin. The timing of the response depends on the stringency of the chosen abatement strategy. Comparisons of the regionally calculated critical loads of sulfur to the catchment value indicated that the catchment belongs to the most tolerant ecosystems of the grid cell.