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Alpine treelines in the High Asia and their relation to temperatures
Yakubouskaya, Alina ; Treml, Václav (advisor) ; Romportl, Dušan (referee)
Treeline is a gradual transition from closed forest to treeless areas at a certain elevation above the sea. According to its forms, we distinguish diffuse, abrupt, island treelines and krummholz. Depending on the form we can assume the main factors affecting its occurrence and possible response to climatical changes. Generally, the position of the treeline in various latitudes relates to the thermal characteristics, mainly to the temperatures of the growing season, limiting tree growth, the availability of necessary nutrients and seedling survival. Limitation by an insufficient carbon balance as a cause of the ecotone, is not considered as a major or decisive factor by many authors. In most cases they proved a sufficient carbon balance at the treelines and fixed an incresing amount of non-structural carbohydrates, needed for trees to activate their growth after a period of dormancy. This work was focused primarily on identifying the positions of the treeline in the mountains of High Asia, and determining the basic thermal characteristics relating to these sites. The best indicator, connected to the position of the treeline in this region was founded. The results were compared with global research. Key words: treeline; diffuse, abrupt and island treelines, krummholz, sink limitation hypothesis,...
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Alpine treelines in the High Asia and their relation to temperatures
Yakubouskaya, Alina ; Treml, Václav (advisor) ; Romportl, Dušan (referee)
Treeline is a gradual transition from closed forest to treeless areas at a certain elevation above the sea. According to its forms, we distinguish diffuse, abrupt, island treelines and krummholz. Depending on the form we can assume the main factors affecting its occurrence and possible response to climatical changes. Generally, the position of the treeline in various latitudes relates to the thermal characteristics, mainly to the temperatures of the growing season, limiting tree growth, the availability of necessary nutrients and seedling survival. Limitation by an insufficient carbon balance as a cause of the ecotone, is not considered as a major or decisive factor by many authors. In most cases they proved a sufficient carbon balance at the treelines and fixed an incresing amount of non-structural carbohydrates, needed for trees to activate their growth after a period of dormancy. This work was focused primarily on identifying the positions of the treeline in the mountains of High Asia, and determining the basic thermal characteristics relating to these sites. The best indicator, connected to the position of the treeline in this region was founded. The results were compared with global research. Key words: treeline; diffuse, abrupt and island treelines, krummholz, sink limitation hypothesis,...
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Změny obsahu nestrukturálních sacharidů v asimilačních orgánech při odumírání stromu
Bradáčová, Alžběta
Non-structural carbohydrates (NSC) are one of the most important organic compounds in the plant growth. Concentration of NSC was studied in the mature Scots pine trees (Pinus sylvestris L.) with artificially disrupted phloem connection between the crown and the roots by stem girdling and in the controls within the vegetation seasons 2013 -- 2014. The highest concentrations of NSC in the needles were at the beginning of the vegetation season, before the needle flush and beginning of radial growth of the stem. While the concentration of the soluble saccharides was not different between the girdled and control trees, the concentration of starch was significantly higher in girdled trees at the beginning of a season. In contrast to the needles, the highest concentrations of NSC in the wood were found in the summer and lowest in the June. The starch content in the wood o girdled trees was significantly higher at the end of the season. The concentration of soluble saccharides was similar in all variants of experiment for the entire season. The NSC may provide and information about the physiological vitality of the tree, however their use as a simple indicator is complicated by the normal seasonal dynamics. The results provide an important contribution to understanding of underlying physiological processes necessary for the correct prediction of the tree survival time.
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Vliv různého typu poškození stromu na obsah nestrukturálních sacharidů u smrku ztepilého
Holasová, Veronika
The aim of the thesis was to investigate concentrations of nonstructural carbohydrates (soluble saccharides and starch) in various organs of damaged Norway spruce (Picea abies (L.) Karst.) trees. The damages of trees were girdling, xylem disruption, cutting off the roots and inoculation by Armillaria sp. The samples of the roots, xylem, bark with phloem and needles were collected in September 2013 and 2014. There were statistically significant differences in starch concentration in needles collected in September 2013; high starch concentrations were detected in girdled trees, while the lowest values achieved trees with xylem disruption. Another significant divergence was found in the concentration of soluble carbohydrates in needles collected in September 2014; the concentration of soluble carbohydrates in the control trees was significantly higher than in trees with cut roots. Other differences in the concentrations of nonstructural carbohydrates variously damaged trees and control trees were not statistically significant. Given the number of factors affecting the concentration of nonstructural carbohydrates -- especially financial and time factors -- they are not suitable as a simple and reliable indicator of tree vitality. However the data provide a deeper insight into the tree functioning after the damage. Inclusion of this information into the process based models will help to more accurate predictions of tree mortality.
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