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TREELINE DYNAMIC IN THE MT. KRALICKÝ SNĚŽNÍK
Kolář, Václav ; Treml, Václav (advisor) ; Šenfelder, Martin (referee)
Treeline dynamic in the Mt. Kralický Sněžník Abstract Changes in treeline positions have been recorded both in the mountains of Central Europe and worldwide. The treeline upward shifts have been recently influenced particularly by rising temperature and reduced human impacts in the highest parts of the mountains. The goal of this thesis is to evaluate dynamics of treeline in the Mt. Kralický Sněžník and to determine influencing factors. Dendrochronological methods were employed to determine age structure of spruce across the ecotone and the analysis of aerial images was used to identify changes of spruce coverage between 1936 and 2014. I found that tree age is decreasing with increasing elevation - an evidence of advancing treeline. Treeline upward advance indicated by a gradual densification of spruce stands was also detected from aerial images. Seedling abundance is negatively affected by dense mats of blueberry in the upper part of ecotone. Mortality of spruce is rising with increasing elevation,which indicates the negative influence of extreme climatic conditions in the uppermost parts of ecotone. Age structures and aerial images show that the treeline advance in the Mt. Kralický Sněžník was caused by a combination of land abandonment at the end of 19th century supplemented by afforestation in the lower...
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Treeline rise as a consuquence of increasing temperature and land-use change
Kolář, Václav ; Treml, Václav (advisor) ; Chuman, Tomáš (referee)
Treeline advance to greater altitude is observed in the majority of European mountains. Many authors have attributed treeline advance to increasing temperatue, others to decrasing anthropogenic influence. The aim of the thesis was to describe dynamics of treeline and influencing factors. Based on newly created database of case studies I asked, whether the treeline agnace is controlled by increasing temperature or by land-use change. My treeline database documented, that treeline advance in Europe ranged from -0,2 to 1,6 m.y-1 . Treeline was advancing most quickly in the Austrian Central Alps, conversely treeline in Ukraine Carpathians revealed retreat. Furthermore, it was found that treeline rise coincides with increasing winter temperatures. While the advance of northern treelines without human impacts is attributed to increasing temperatures and precipitation, remaining areas showed treeline advance in consequence of temperature increase and decreasing anthropogenic influence.
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Dominant flow features of twin jets in crossflow
Kolář, Václav ; Savory, E.
A survey of the recent studies of "twin jets in crossflow" (TJICF) by the present authors is carried out and extended in terms of results of the velocity-field analysis based on decomposition techniques. Similarities and differences between the dominant mean-flow vortical features, vorticity and circulation associated with three basic ground arrangements (tandem, side-by-side and oblique arrangements) are examined, and the comparison with the single jet case is carried out as well.
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