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Trends in tree-ring width of treeline trees along latitudinal gradient from subtropics to the Arctic.
Zborníková, Kateřina ; Treml, Václav (advisor) ; Mašek, Jiří (referee)
This bachelor thesis is interested in a tree ring of trees at the treeline from subtropics to the arctic and the main aim of this work is to find if there is a trend in the tree ring width at the treeline along the latidunial gradient. The work/thesis focuses on conifers. The data were obtained from International Tree-Ring Data Bank database, article searches and from the internal workplace database. A total of 9859 annual ring samples were obtained from 153 localities in Europe. Trees of the genus Pine (Pinus), Spruce (Picea) and Fir (Abies) were selected, which dominate the europeans ecotones of treeline. After removing the age trend, the regression of tree ring width and the latitude, were calculated. The results showed that in most cases the tree ring width decreases with higher latitude. However, a small number of tree ring samples from latitudes around 55ř north latitude adds to the uncertainty of this claim.
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SPATIAL PATTERN OF TREES WITHIN TREELINE ECOTONE
Zákravská, Šárka ; Treml, Václav (advisor) ; Demková, Katarína (referee)
The main part of my bachelor thesis is focused on treeline advance and on its spatial pattern especially. The theoretic part is consisted of a description of basic properties, hypothesis of treeline formation, current treeline movements in chosen European mountains and their potentional explanations. The aim of the practical part was to discover whether the type of spatial pattern affects treeline dynamics. Namely, the western part of the Giant Mountains was taken as a surveyed teritory. Ortorectified aerial photographes from years 1936 and 1964 were used when doing comparison. Spatial pattern was counted by "Ripley's K-function" and by the method of "Average Nearest Neighbour" on 110 defined squares (size 30 m) in the expanding part of the ecotone and on 110 defined squares in its stagnation part. Results don't indicate that some type of spatial pattern support treeline advance. The same spatial pattern was found both in major parts of stagnation and the expanding part of the ecotone.
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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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The effect of vegetation pattern on stand expansion on the example of dwarf pine
Růžičková, Veronika ; Treml, Václav (advisor) ; Lipský, Zdeněk (referee)
This bachelor thesis deals with the influence of the structure of the dwarf pine on its expansion in the highest parts of the Giant Mountains. The aim was to find out how this and other factors influence the expansion. For this purpose, in 68 squares, the kneeling vegetation was orchestrated on the basis of orthoctified aerial photographs from 1964 and 2015. Subsequently, a change in the growth of the dwarf pine, the length of the edges of the forest in 1964, the average slope and the altitude in each square were found. Using the correlation analysis, the effect of the variables on the change of the surface was determined. These variables were further used to build a multiple linear regression model. The results showed that the dwarf pine growth increased in the period under review. The greatest influence on expansion is the length of the edges in 1964, ie the breakthrough, the impact of which is positive. A similarly strong influence is the slope of the surface, which affects the expansion negatively. Similar results have been achieved by other authors
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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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Climatic settings of Carpathians' treelines
Klášterková, Hana ; Treml, Václav (advisor) ; Chuman, Tomáš (referee)
6 Climatic settings of Carpathians' treelines Abstract Alpine treeline ecotone is phenomenon widely studied around the world. Its shift to greater altitudes is connected mainly with climatic changes recently. However, many authors take into account changes in landuse as well. The aim of this thesis was to depict dynamics of treeline and factors influencing temperature metrics which delimitate advancing of the treeline to higher altitudes. For 6 sites within Carpathians were found the uppermost positions of treeline and several temperature metrics based on available meteorological data were calculated for these locations. Results of calculated thermal metrics revealed that treeline positions in most of the studied areas are situated at altitudes under their climatic limit. Varful Omu with TJUN-SEP = 7,1 řC was the only one location which meets the stated interval of minimal mean temperatures for growing season (Paulsen & Körner 2004) necessary for tree growth. This fact points out that treelines found within Carpathian Mts. are under pressure of other limiting factors than thermal ones. Persistent anthropogenic activities have a significant influence on treeline positions in some regions of Carpathian Mts. Altitudes of treeline stands are most negatively influenced by human activites in the Western and...
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Recent shifts of alpine treeline ecotone in temperate and boreal part of Northern Hemisphere
Kolařík, Petr ; Treml, Václav (advisor) ; Romportl, Dušan (referee)
Treeline advance is often cited as one of the effects of the global climate change, especially the rise of mean temperatures. However, treeline dynamics is a complex issue. This thesis aims to describe factors that determine the position and dynamics of the alpine treeline and create an overview of treeline dynamics in the temperate and boreal parts of the Northern Hemisphere outside of Europe. A further goal is to create a database of treeline advance at locations in this region and then analyze this database. Of the 20 studied locations, 65 % showed treeline advance while treeline receded at only two locations. The highest rate of advance was recorded in the Rocky Mountains of North Americe, up to 1.59 m/yr. The highest rate of recession was recorded in the San Francisco Peaks, also in North America, where a recession of 1.21 m/yr was recorded. A statistical analysys showed no significant correlation between temperature trends and treeline advance. Locations that had undrgone a change in land use showed both the highest rate of advance and recession. It appears that anthrpogenic activity is an importnant factor influencing the dynamics of alpine treelines.
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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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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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