Citlivost letokruhových řad borovice kleče a smrku ztepilého ke klimatickým parametrům horní hranice lesa

Trees growing on the treeline can serve as a sensitive indicator of changes in climatic parameters associated with ongoing climate change. Understanding differences between trees and shrubs growing in this ecotone is a key for understanding the functioning of the treeline. Therefore, the submitted thesis deals with the study climate diameter-growth responseof Norway spruce and Dwarf pine. Samples from Norway spruce and Dwarf pine were collected at the localities at treeline in the National Nature Reserve Praděd in the Jeseníky PLA. Indexed chronologies were developed for Norway spruce and Dwarf pine using various detrending methods of raw tree ring series (Spline, Negative Exponential, Ar, Mean, Friedman). For subsequent dendroclimatological analysis, I used the chronology with their tree ring series were detrended using Spline. Subsequently, correlations of the indexed tree-rings width with monthly climatic variables (average temperature, precipitation total, PDSI – Palmer drough severity index) were calculated. These correlations were investigated both for the entire chronology period and separately for the sliding time sequences within the chronology. It was found that the radial growth of Norway spruce is influenced mainly by temperature in the growing season (May to July) and in November in the year preceding the creation of the tree-ring. In the case of monthly precipitation, their positive correlation with radial growth was recorded only in March and no significant correlations were noted for PDSI. The growth of Dwarf pine is influenced by the temperature at the beginning of the growing season (June) and in October in the year preceding the growth of the tree-ring. Monthly precipitation negatively affects radial growth in October in the year preceding the growth of the tree-ring and no significant correlations were noted for PDSI. The results correspond to the view that the most important factor for the growth of trees at the treeline is temperature, that is not so important for shrubs. The monthly precipitation sums and drought index are not limiting for woody plants of this ecotone