National Repository of Grey Literature 120 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
The influence of climate on the radial growth of Scots pine in the northern Scandinavia
Tomeš, Miroslav ; Treml, Václav (advisor) ; Šefrna, Luděk (referee)
The presented master's thesis deals with the influence of climate on the radial growth of Scots pine in the northern Scandinavia. Trees growing at the polar treeline are sensitive to environmental changes, and therefore their wood is used to study growth responses to ongoing climate change. During the period of the 20th and the beginning of the 21st century, air temperatures and precipitation sums were correlated with tree rings and dendroanatomical data of Scots pine from northern Finland. It was found that the widths of the tree rings had a slightly increasing trend during the observed period. Within the framework of the correlation relations, the controlling influence of the air temperatures of the current July on annual increments was confirmed. Thanks to the higher temperatures of the summer season, wider tree rings were formed. In addition, May and summer precipitation have been shown to be important for the final width of the tree ring. The currently often discussed problem of decoupling the tree ring chronology curve from rising summer temperatures ("divergence problem") was not clearly observed in this work. In order to evaluate the dendroanatomical parameters, the tree rings of the studied individual were divided into four sectors with a similar number of cells in the radial file. During...
Scots pine climate-growth response in the topographically complex landscape of the Kokořínsko region
Fišer, Petr ; Treml, Václav (advisor) ; Šefrna, Luděk (referee)
The extensive Scots pine Pinus sylvestris forests in topographically complex landscape of the Kokořínsko region in the Czech Republic are a suitable area for investigating how trees react differently to climate factors depending on local site conditions. Individual habitats are characterized by specific conditions which can influence a wide range of growth factors. It is therefore important to understand these differences also from the point of view of ongoing climate change, which threats forest ecosystems in central Europe. The relatively dry environment of the highly permeable sandstone landscape is vulnerable to increasing drought, which will increase the stress of local Scots pine population. Samples from 20 sites divided into 4 categories of northern slopes, southern slopes, plateaus and valley bottoms are supposed to sufficiently represent variability of the local terrain. Correlation of tree-ring chronologies with climate variables as well as PCA analysis revealed that the greatest differences are between plateaus and valley bottoms. In case of highly exposed plateaus, drought seems to be the most important limiting factor, whereas at the valley bottoms temperatures at the turn of winter and spring are the main controlling factor. Signifficant differences between northern and southern...
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.
Influence of mountain farming termination on forest stands in the east part of the Krkonoše Mts.
Mach, Dominik ; Treml, Václav (advisor) ; Romportl, Dušan (referee)
This thesis focuses on the evaluation of the impact of abandonment of agricultural land on forest stands in the eastern part of the Krkonoše Mountains. The aim of this thesis is to reconstruct the evolution of the forest response to gradual termination of mountain farming. Specifically, I analysed the age structure of Norway spruce (Picea abies) and described the dynamics of secondary forest succession in meadow enclaves around huts. Three main research methods helped meeting the above-mentioned objectives of the thesis. The first is the analysis of old maps. The second is segmentation and supervised classification of aerial photographs. The last is dendrochronological research of the age structures of Norway spruce. Research showed the expansion of forest stands into treeless grassland enclaves. The main driving force behind this process of secondary succession has been the gradual decline of mountain farming. After the end of mountain farming in the middle of the 20th century,the dynamics of forest succession in meadow enclaves increased significantly, with the highest rate of succession in the following 20 years. Forest succession took place mainly along the edges of meadow enclaves. Inside the meadow enclaves, trees were mostly established along streams. The most significant factor that...
Importance of forest continuity and fragmentation according to beetles as an indicating taxonomic group
Loskotová, Tereza ; Romportl, Dušan (advisor) ; Treml, Václav (referee)
Importance of forest continuity and fragmentation according to beetles as an indicating taxonomic group Abstract Old-growth forests can provide suitable habitats for certain organisms which can't live in another type of environment. These organisms can be used as bioindicators of old-growth forests. Spatial organization of forests affects spatial distribution and population abundance of these organisms. Fragmentation process can negatively influence populations of forest organisms. In particular, the aim of this work was to locate areas with forest continuity within the area of interest and to characterize their spatial arrangement. Long-term continuity of forests was identified using historical maps. Spatial distribution of forests is not equal. In the northern and north-eastern part of the area, there is a large forest complex while in the southern and south-western part of the area, there is lot of forest fragments with surrounding of agriculture fields. Next target was to select beetle group with potential bioindicators of forest continuity. Many beetle species live in forests and the group fulfills requirements for indicating groups. Saproxylic beetles were chosen as a crucial group for a subsequent study. Keywords: continuity, fragmentation, indicator, landscape structure, beetles
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.
Comparation of frost hummocks in the Hrubý Jeseník Mts. and Iceland.
Vejrostová, Monika ; Křížek, Marek (advisor) ; Treml, Václav (referee)
This paper is focused on comparation of frost hummocks in the Hrubý Jeseník Mts. and in the Mosfellsheiði area in Iceland in terms of their external and internal characteristics as well as their thermal characteristics. Field work in Mosfellsheiði provided height, length, and width data of more than 120 frost hummocks which were analyzed and compared to frost hummocks in Keprník and Tabulové skály location in the Hrubý Jeseník Mts. Soil samples from frost hummocks were taken to determine frost susceptibility of soils. Based on ground temperature measurements at depth of 15 and 30 cm in the frost hummocks in Iceland and the Hrubý Jeseník Mts., freeze-thaw cycles were investigated. The results show that frost hummocks in the Hrubý Jeseník Mts. are larger but less domed-shaped than those in Mosfellsheiði. Further, soils in frost hummocks are frost susceptible. The highest numbers of freeze-thaw cycles were identified in Iceland. It was also found out that freeze-thaw processes occurred in the frost hummocks in Tabulové skály but in Keprník location were very few freeze-thaw cycles observed. Short term freeze-thaw cycles at the end of regelation seasons mostly show diurnial frequency. At the 30 cm depths only one or two regelations were observed during a single season. Powered by TCPDF (www.tcpdf.org)
Structure of non-active sorted patterned ground in the Giant Mts.
Uxa, Tomáš ; Křížek, Marek (advisor) ; Treml, Václav (referee)
Sorted patterned ground are a group of periglacial microforms which create more or less symmetrical forms due to frost action and especially repeated freeze-thaw cycles. The origin of sorted patterned ground in the Giant Mts. is presumed in late Pleistocene and they are suggested to be recently inactive (with the exception of sorted circles). Their occurrence is linked to the topmost localities with flat surfaces and intense wind action which causes low snow cover and allow deep soil freezing. The submitted diploma thesis deals with the influence of site characteristics (such as microclimatic extremity, terrain morphology and lithology) on morphology and sorting degree of sorted patterned ground. Field research was carried out along a transect tracing the microclimatic extremity gradient (represented by altitude and so-called relative snow height) in area of Mt. Luční hora in the eastern part of the Giant Mts. which in relatively homogeneous from the viewpoint of lithology and wind exposure. The transect was further extended across the Modré sedlo Saddle to the Mt. Studniční hora where there also occur various types of fossil sorted patterned ground or quasi- active sorted circles in the Modré sedlo Saddle, respectively. However, there is a variability of lithological as well as altitude...
Freeze-thaw processes, temperature and moisture trends in earth hummocks
Kodríková, Anna ; Křížek, Marek (advisor) ; Treml, Václav (referee)
Earth hummocks are nonsorted patterned ground types. This thesis is primary focused on the study of temperature regime particularly during freeze-thaw process and also on factors that affect its non-uniformity. Secondary, it refers to the relation between temperature and moisture regime, morphometric characteristics of earth hummocks and their geographical expansion in the world. The information from the literature search is applied to the results from temperature and moisture measurements of the earth hummocks in depths 5 - 40 cm in the Hrubý Jeseník Mountains - Keprník peak in 2005 - 2010. The results show that many factors affect the non-uniformity of temperature regime in different parts of earth hummocks. The most important of them are: the shape of the earth hummock, the aspect orientation, the distribution and the height of snow cover, the wind exposure and the presence of vegetation. There is an interaction between the soil moisture content and the temperature regime, and they are mutually affected. The obtained results from the Keprník study area are compared with the literature data about the earth hummocks in the world. Key words: patterned ground, earth hummock, temperature regime, moisture, regelation, Keprník peak, Hrubý Jeseník Mountains
Dendrochronological dating of catastrophic slope movements
Tumajer, Jan ; Treml, Václav (advisor) ; Burda, Jan (referee)
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....

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