Concentrations of air pollutants measured by passive samplers, atmospheric deposition to forest ecosystems, soil water chemistry, nutrient content in the soil and foliage were all measured within a study of the causes of forest decline in Nýdek Forest Range, Jablunkov Forest District (Silesian Beskids). Declining Norway spruce stands are situated in a region of historically high air pollution load, mainly from the Třinec and Ostrava agglomeration. Air pollution significantly decreased in the second half of the 1990s. Forest soils showing the insufficiency of main nutrients remain today as the main factor affecting the forest vitality. The situation in the soil is subsequently reflected in the nutrition level of the assimilation tissues. Simultaneous effects of other stressors (e.g. biotic, meteorological ones) can support a sudden worsening of the stand health and cause serious damage.

ABSTRACT:The article focuses on changes in soil chemistry observed on plots limed in 2000 in the western Ore Mts. (Krušné hory) on the basis of chemical analyses done before liming and repeated in 2002, 2005 and 2010. In the deeper mineral soil (down to 30 cm), only the increase in pH and exchangeable magnesium was significant. The increase in exchangeable calcium in upper soil layers was significant in 2002 and 2005 only; ten years after liming the effect was negligible, although the number of Ca deficient samples was lower than in 2000. The exchangeable Mg content increased above the deficiency limit in all samples of upper soil, and an increase was also found in the deeper mineral soil. These changes were reflected in increasing base saturation and lower base cations/aluminium ratio in the organic and organomineral soil layer. Despite these positive shifts, calcium and magnesium deficiency and very low base saturation (< 10%) still prevail in the deeper mineral soil (2-30 cm) and are common even in the upper mineral soil. The increased total nitrogen level observed two and five years after liming indicated enhanced decomposition of the humus layer. On the other hand, N content in the upper organic (FH) horizon as well as in deeper mineral soil did not change significantly.

Microbial biomass-C [MBC] (1) arable Cambisols (100%), (2) cut and grazed grasslands (547%), (3) forest mineral horizon A H : 0-50 mm (783%) and (4) Norway spruce forest floor (2421%). The ratio EC-Ca/EC-K reached on average 62% and ranged from 48% to 74%. Correlation between EC-K and EC-Ca values is connected with soil organic ma�er status; the correlation was very close for Cambisols (r 2 = 0.925), a medium correlation was found for forest floor (r 2 = 0.380) and a weak correlation was observed for Podzols (r 2 = 0.042). The correlation between MBC-K and MBC-Ca was very close in all cases: Cambisols (r 2 = 0.811), Podzols (r 2 = 0.904) and forest floor (r 2 = 0.496). The ratio between organic carbon and organic nitrogen in 0.01 mol/l CaCl 2 extracts [EC-Ca/N org ] could be declared as a new indicator for soil microbial association status.