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Tree-ring chronologies of Norway-spruce on west-east longitudinal gradient in the mountain ranges of central Europe
Ponocná, Tereza ; Treml, Václav (advisor) ; Kolář, Tomáš (referee) ; Vejpustková, Monika (referee)
The Earth's climate system has recently experienced substantial warming which likely impacts temperature-limited communities close to their distribution margins. The alpine treeline ecotone represents upper distributional limit of montane/subalpine forests. This biogeographic boundary relies mainly on decreasing temperature with increasing elevation. Surprisingly the response of treeline ecotone to ongoing warming has varied a lot and the reasons of this variability are poorly understood. The aim of this dissertation thesis is the assessment of growth trends and tree ring response of Norway spruce (Picea abies[L.] Karst.) to climatic oscillations at treelines and montane forests of East-Central Europe. This dissertation deals with both inter-regional and intra-regional (aspect, elevation) variability of tree growth. The presented results are based on an extensive data set of growth curves for almost 1400 trees. All study sites revealed close relationship between tree ring widths and growing season temperatures as well as the temperatures of October preceding to ring formation season. The main site-dependent differences in growth trends and temperature responses were attributed to elevation, the effect of aspect was relatively less significant. At treelines between the Krkonoše Mts. and Nízké Tatry...
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An analysis of exposure effect on treeline ecotone, Krkonoše Mts.
Ponocná, Tereza
The thesis deals with the influence of thermal conditions on the growth of the trees along the slopes with differing exposure to solar radiation in the alpine treeline ecotone in the Eastern Giant Mountains. Methodological approach was based on the measuring of the tree top and root zone temperatures, measurement of the dendrometric parameters (tree height, length increment) and radial increment of the Norway spruce (Picea abies). The results show only weak relation between significant temperature characteristics and exposure effect in the alpine treeline ecotone, which correspond to the growth rates of the sampled trees. Slightly higher temperatures were found on the south-facing slopes during the growing seasons in case of the closed canopy forest. Soil and air temperatures in tree groups were a bit higher on the north-facing slopes. In closed-canopy forest there was larger radial increment on south-facing slopes of Luční hora, on the slopes of Malý Šišák there were similar growth trend on both slope exposures. In tree groups there were found larger increments on north-facing slope of Luční hora, on the sampled sites of Malý Šišák there were found larger increment on south-facing slope during the 20th century, then in last decade larger increment was recorded on north- facing slope. Based on...
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Selected approaches of climate-growth relationship determination of trees
Pekař, Ondřej ; Treml, Václav (advisor) ; Ponocná, Tereza (referee)
Presented bachelor thesis describes the use of tree-ring widths in dendroclimatology and main approaches of climate variables reconstruction. It reviews the basics about climate influence on tree- ring fromation and extraction of climate signal from tree-rings. Main standartization methods were used to develop 26 standard and residual chronologies from adjusted and not adjusted tree-ring series coming from high-elevation Norway sporuce stands. Chronologies were compared in terms of correlation with summer temperatures. The best correlated temperature variable were the June-July temperatures both for standard and residual chronologies. Tree-ring width chronologies were scaled to observed June-July temperatures. Based on comparison of scaled and real June-July temperatures, negative exponential function and RCS method appear to be the most suitable to preserve both high and low frequency climate signal. Key words: Dendroclimatology, tree-rings chronology, standardization, climate reconstruction
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Effect of slope aspect on intra-annual growth of trees in the treeline
Zákravská, Šárka ; Treml, Václav (advisor) ; Ponocná, Tereza (referee)
This diploma thesis is focused on microclimatic differences at treelines on north-facing and south-facing slopes and their effect on tree growth. Thesis contains an overview of factors affecting development and timing of xylogenesis. The effects of slope orientation on treeline in relation to exposure effect are mentioned as well. The aim of the practical part of diploma thesis was to determine development, timing and the impact of temperature characteristics on xylogenesis of Norway spurce (Picea abies) on two localities with opposite slope aspect. Locations were situated in the Důl Bílého Labe valley, Krkonoše Mountains. Xylogenesis was studied using sections of micro-cores. Microcores were sampled every 10 days during the growing season. They were subsequently analyzed in dendrochronological laboratory. My results show that influence of air temperature recorded at the start of cambial cell division and the development of enlarging cells in the first part of the growing season. Climatic characteristics of both sites was similar, larger differences in temperatures were recorded at the beginning and at the end of the reference period.
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Long tree-ring records in Central Europe and their climatologic significance
Gregor, Tadeáš ; Treml, Václav (advisor) ; Ponocná, Tereza (referee)
Submitted bachelor thesis is considered with use of tree-ring dates for reconstruction of climatic conditions in the past. There is a review of some most important long tree-ring reconstructions worldwide and a review of long central-european tree-ring reconstructions in the tesis. Central European dendroclimatic reconstructions longer than 250 years were compared to each other in accordance with their length, statistical strenghtness and ability to preserve high- and/or low-frequency climatic signal. Resulting reconstructions were also compared in this bachelor thesis. Greater variability among temperature reconstructions is evident contrary to conformity of hydroclimatic reconstructions. Localisation of Central European chronologies, possible causes of differencies among reconstructions and comparisons with other proxy data were discussed. Keywords: tree-rings, dendrochronology, dendroclimatology, climate
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An analysis of exposure effect on treeline ecotone, Krkonoše Mts.
Ponocná, Tereza ; Chuman, Tomáš (referee) ; Treml, Václav (advisor)
The thesis deals with the influence of thermal conditions on the growth of the trees along the slopes with differing exposure to solar radiation in the alpine treeline ecotone in the Eastern Giant Mountains. Methodological approach was based on the measuring of the tree top and root zone temperatures, measurement of the dendrometric parameters (tree height, length increment) and radial increment of the Norway spruce (Picea abies). The results show only weak relation between significant temperature characteristics and exposure effect in the alpine treeline ecotone, which correspond to the growth rates of the sampled trees. Slightly higher temperatures were found on the south-facing slopes during the growing seasons in case of the closed canopy forest. Soil and air temperatures in tree groups were a bit higher on the north-facing slopes. In closed-canopy forest there was larger radial increment on south-facing slopes of Lu_ní hora, on the slopes of Malý Šišák there were similar growth trend on both slope exposures. In tree groups there were found larger increments on north-facing slope of Lu_ní hora, on the sampled sites of Malý Šišák there were found larger increment on south-facing slope during the 20th century, then in last decade larger increment was recorded on northfacing slope. Based on standard...
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