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Avalanches are important natural processes which shape the character of large mountainous areas. The reconstruction of their history has been performed on avalanche tracks in the Důl Bílého Labe Valley, Krkonoše Mts. through application of dendrogeomorphological methods. In total 101 trees from the area of 5 avalanche tracks were cored or cross-sectioned, which helped to identify 1253 growth disturbances (abrupt growth suppressions or releases, increases in tree-ring eccentricity, traumatic resin ducts, reaction wood, callus or determination of the tree death). The analysis spanning period from the 1859 led to the identification of 40 avalanche events, which prolong and complement written evidences of avalanche falls (avalanche cadastre). However, because of limitations of dendrogeomorphology (especially impossibility of dating of small events), these results have character of only minimal number of events. Strong influence of monthly snow melting and snow accumulation on initiation of events was pointed out through the statistical analysis of snowpack changes in relation to the reconstructed avalanche activity. Two main possible natural reasons for avalanche activity initiation were identified - vast spring snow melting and loading with fresh snow. The analysis demonstrates the potential of...

Mass-movements are one example of natural processes that can pose a serious risk for human beings and their possessions. Dendrochronology, a method capable of their reconstruction, can provide parameters of former events, which can be used for planning protective measures. The possibilities for the application of dendrochronological methods have been tested by means of meta-analysis of electronic and printed scientific articles and a case study focused on former avalanche activity in Schustler's avalanche path (Labský důl, Krkonoše Mts.). The main conclusion of the first one is the clear spatial disproportion of the recent dendrogeomorphological research activities - e.g. the dating of avalanches is typical for mountains of Montana (USA); the Alpine region (mainly Switzerland), on the other hand, absolutely dominates in the research of debris-flows. In the case study, the analysis of material with well-chosen indicators led to high accuracy results comparable with the results of scientific articles focused on avalanches, and made the identification of 14 years (in the period 1953-2007) with potential avalanche acitvity possible. Although methods of dendrogeomorphology are usually neglected in the research of avalanches in the Czech republic, their great potential for future applications is shown....

This diploma thesis is focused on mountain Norway spruce (Picea abies) forests and their sensitivity to acid deposition, which culminated in Czechia during the 1980s. Acid deposition negativelly affects tree growth resulting in high mortality and poor health status of the entire forest stands. Mountain forests provide numerous important ecological services, which increses the need for understanding of the processes affecting their growth. The thesis examines the interaction between acid damage in the past and current growth trends and the resistance of mountain forests to current climate extremes (mainly to the effects of drought). The empirical part of the research is based on data on trends in tree-rings widths over the last two decades together with historical data of defoliation monitoring. Tree-ring width data were sampled using dendrochronological methods in the field. For this research, I selected plots along two altitudinal transects in the Krkonoše Mts. - Pec pod Sněžkou and Špindlerův Mlýn. Defoliation data were extracted from the long-term MONBASE database from the Institute of Forest Ecosystem Research (IFER). The statistical method of correlation analysis was used in order to determine the relationship between acid deposition and current tree growth. The most important correlated...