The state of climate and air pollution in the Silesian Beskid

The region of Moravian-Silesian Beskids has been in recent years affected by expressive yellowing of Norway spruce stands, which leads to a gradual drying and dieback of individual trees. The analysis of stress factors in the region of Silesian Beskids demonstrated a persisting occurrence of predisposition factors whose synergic action has a potential to provoke gradual decline, degradation and dieback of forest stands. The damaging of forest stands is apparently very complex. In the situation when chemical stress adds to climatic stress, the climatic stress assumes the role of predisposition factor. Damages to forest stands occur particularly in locations with exceeded limits of acid deposition critical load. It also follows out from the analysis that climatic stress induced by insufficient precipitation in years 1992, 1993 and 2003 in the studied locality of Silesian Beskids can be considered one of main predisposition factors of health condition worsening and damage to Norway spruce stands with a flat and often disturbed root system e.g. by increased soil acidification, established in upper soil horizons. The analysis of the occurrence of temperature reversals showed that frost shock is one of potential stress factors affecting the health condition of Norway spruce stands in the spring and in the autumn. The process of disturbance manifested by yellowing with the symptoms of chlorosis and necrosis of the youngest needle years is further entered by the synergic action of the ground ozone concentrations and the increasing intensity of UV-A and UV-B radiation. Trigger factors for local defoliation can be for example one-time extreme air temperature fluctuations in early spring or recurrent spells of drought and damage to assimilatory organs of the tree species due to ozone, UV radiation or direct and indirect synergic effect of acidic depositions of hydrogen ions in the soil environment.