Air pollution load and nutrient status of Norway spruce forest stands in the north-western part of Slovakia

The article summarizes the results of research of air pollution load, site conditions, and nutrition of spruce stands in the Kysuce and Orava regions (Beskydy Mts.). The region was intensively exposed to air pollution from emission sources in neighbouring countries mainly in the 1970s and 1980s. At present, this region is affected by a vast decline of spruce stands, which is thought, at least partly, to be related to air pollution. Long-term research during the last decade indicated: i/ decrease in SO2 and NOx concentrations, ii/ although the trend of sulphate concentration in precipitation is decreasing, the deposition of sulphur and especially nitrogen remain relatively high, iii/ in general, there is no evidence of continued forest soil acidification, and the share of the area with an exceedance of critical load of total acidity is decreasing, iv/ the nutrition status of spruce is relatively good, v/ ground-level ozone exceeds the concentration that could damage the trees.