Dendroecological study of spruce growth in regions under long-term air pollution load

The purpose of this study was to analyse increment cores from spruce growing in the Ore Mountains, Jizerské Mountains, and Giant Mountains, to evaluate the relationship between tree growth, climatic factors, and air pollution load. The sites from which sample cores were extracted were localised along an altitudinal gradient. Analytical methods included single pointer year analysis and simple linear regression. An unambiguous relationship between negative pointer years and climatic extremes was detected for growth increments prior to 1977. After 1977, minimum increment values also reflected the gradient of air pollution levels. In the eastern part of the Ore Mountains, an increased sensitivity of spruce to low temperatures and temperature breaks was evident. The dominant role of temperature during the winter period was confirmed by the results of correlation analysis. From this, I have concluded (indirectly) a long-term deleterious impact of sulphur dioxide, resulting in lower frost resistance of the spruce trees. Recent increment development suggested that the stands in the Giant Mountains overcame the critical period at the end of the 1980's, and regenerated well. By contrast, the ecological stability of the Ore Mountain forests was disturbed due to chronic stress, and the existence of the stands is threatened.