STRESS ON THE NORTHERN TYROLEAN LIMESTONE ALPS BY THE DEPOSITIONS OF POLLUTANTS

Anthropogenous stresses to the forest ecosystems of the Northern Tyrol ean Limestone Alps are caused by local emitters and long-range transpo rt. Apart from the gaseous pollutants SO2, NOX and ozone, the proton, nitrogen and heavy metal depositions are particularly harmful. Investi gation results from all over Austrian surveys (Austrian Bio-Indicator Grid, Austrian Forest Soil Monitoring System), air monitoring data fro m the Federal Province of the Tyrol, model calculations, and surveys f rom the Achenkirch area were used to describe the stress imposed by po llutants. The monitoring data were evaluated by using effect-related l imiting values and/or Critical Loads. The evaluation of air monitoring data from the Northern Tyrolean Limestone Alps showed that pollution patterns vary greatly depending on altitude. In valleys, the effect-re lated limiting values for SO2 and NO2 are exceeded in agglomerations; at higher locations, ozone is a potential risk factor, particularly fo r sensitive species. In the needles of Norway spruce, which has been u sed as a bioindicator species, sulphur depositions were proved up to a ltitudes of 1200 m. Attention should also be paid to the heavy metal d epositions caused by anthropogenous emitters. They accumulate in the u pper soil layers, increase with altitude and are important because the y can influence soil-biological processes. Whereas the acid inputs in the Northern Tyrolean Limestone Alps are usually well buffered by the soil, excessive nitrogen inputs may cause negative effects on forest e cosystems.