Evaluation of SO2 and NO2-related degradation of coniferous forest stands in Poland

Poland has been for many years under the strong influence of air pollutants (mainly SO2, NO2 and heavy metals) which have inflicted significant damage on Polish forests. A 3-year study on the degradation of coniferous stands assessment as opposed to the level of acidic air pollutants was carried out in various regions of Poland. Concentrations of SO2 and NO2 in the atmosphere showed significant seasonal variation (monthly range from 0 to 95 and 0.5 to 22 μg m-3 considerably for SO2 and NO2), reaching the highest levels in winter. Their concentrations varied between the sites. Sulphur and nitrogen concentrations in the needles of Norway spruce (Picea abies (L.) Karst) (666-2511 μg g-1) and Scots pine (Pinus sylvestris L.) (900-2438 μg g-1) were high and exceeded the levels considered normal from 100 to 400%. Levels of S and N varied seasonally, between the years and sites. All analysed needles from all stations were damaged identifying the beginning to more severe degradation of epicuticular wax structure. Stage of epicuticular wax structures showed a relationship with S content in the needles. Both levels of S and N concentration and erosion of the needle surface wax were in most cases connected to the concentrations of acidic gas in the air