|
|
Factors determining the alpine treeline
Oľhava, Rastislav ; Sklenář, Petr (advisor) ; Treml, Václav (referee)
The alpine treeline is a global phenomenon which represents sudden change between two significantly different vegetation types: mountain forest and low-stature alpine vegetation. The primary climatic factor that determines its position seems to be the temperature. We summarize the results that describe the relation between temperature and the altitudinal position of the treeline and search for a general formula that would determine its position. There are two hypotheses which try to explain what is the main limiting factor above tre- eline: C-limitation and growth-limitation. The first one claims trees are limited by carbon shortage, while the latter one favours low-temperature limitation of tissue formation al- though the carbon income is sufficient. This thesis provides a summary of the arguments for each of them and describes the state of knowledge on this matter.
|
|
|
Klimatický signál v letokruhových chronologiích borovice kleče
Samusevich, Alina ; Treml, Václav (advisor) ; Vejpustková, Monika (referee)
Pinus mugo Turra (sensu lato) is a prostrate shrub growing above the alpine timberline in the mountain ranges of Southern, Central and Eastern Europe. It is well adapted to the harsh alpine environment creating different mechanisms for survival. The research was carried out in Krkonoše Mountains on base of Pinus mugo individuals compared with Picea abies trees. Samples from shrubs were gathered using serial sectioning from four sites in different elevations located on Sněžka Mountain and Smogornia Ridge. Further analysis of the sampled material was made with the help of different detrending methods to see which method will return the best growth response to climate parameters. RCS detrending and detrending via simple averaging reflected the best climate signal contained in dwarf pine chronologies. The advantage of these methods is based on their ability to reflect growth conditions of the particular site. Upper sites showed significant correlations with temperatures of the growing season, while on lower sites the signal was quite unclear. The amount of precipitation plays the significant role on shrub growth during the vegetation period (especially July month) and early spring when water is very important for growth initiation. Upper Pinus mugo sites showed high sensitivity to droughts, especially...
|
|
|
Assessment of the impact of landscape structure on the dispersion of lynx in Posumavi
Sladová, Michaela ; Romportl, Dušan (advisor) ; Treml, Václav (referee)
Assessment of the impact of landscape structure on the dispersion of lynx in Posumavi Abstract: The big predators are a traditional group of bioindicative species, whose presence shows the state of environment and landscape within a region. As these animals recolonize the cultural landscape of central Europe it's needed to understand their space requirements and habitat preferences. The lynx (Lynx lynx) has been one of the Sumava forest species since the 70's. After almost 40 years the population of lynx has spread from Sumava and Bavarian Forest to forested parts of Cesky Les, Smrcina and Novohradske hory and to both sides of state borders. However today's state of lynx population, stable number of animals or genetic variability is endangered by many factors. Long term viability of the lynx population is - besides poaching or illegal hunting − affected by the loss of suitable habitats and ongoing fragmentation of the landscape. One of the possible solutions of negative impacts is delineation and protection of landscape permeability of habitat corridors. They might have provide supply of new individuals to small, extinction prone population and at the same time they could reinforce overall fitness population. This thesis has three main objectives:1) evaluation of landscape fragmentation and connectivity in...
|
|
| |
|
|
Paleoclimatic proxies for the Upper Holocene in Central Europe
Heglasová, Veronika ; Treml, Václav (advisor) ; Nývlt, Daniel (referee)
This thesis summarizes findings of the Central European climate evolution during the Late Holocene and approaches to studying the paleoclimates. Indirect sources of evidence about a climatic variable, i.e. proxy data, are used to infer quantitative estimates of temperature or precipitation and can be subdivided into several categories: tree rings record both low- and high-frequency variability of climate with annual resolution; biological (and palynological) proxy data show evidence of longer-term climate changes which are deduced from changes of assemblages/taxa and their ecological preferences. Sedimentary chemistry, including stable isotopes 18 O a 13 C, maintains information on environmental conditions at the time of origin and deposition of sediment (thanks to fractionation and other processes); natural archives are complemented with documentary data which capture the fluctuations of climate up to monthly resolution and also extreme events. There is 44 quantitative paleoclimatic reconstructions in the Central Europe that employ the aforementioned proxy data, although the majority of research articles investigates only approximately the past one thousand years. The temperature and precipitation are reconstructed in the area of the Czech Republic for the past ~600 years. Decadal variability of...
|
|
|
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
|
|
|
Spatial distribution snow cover in alpine forest-free area, Krkonoše mts.
Klivanová, Lucie ; Treml, Václav (advisor) ; Jeníček, Michal (referee)
Snow is a an important factor in alpine forest-free area and character of snow accumulation and degradation affect soil water availability; snow's insulation, soil temperature variations and regelation. Snow can influence flora and fauna, evolution of soils and occurrence of periglacials forms. This thesis deals with the distribution of snow cover and influencing factors of spatial pattern of snow depth.. The research of snow cover distribution was based on periodic field measurements of snow depths in winters 2009/2010 and 2010/2011. For evaluation and interpretation of measurements, data were statistically processed in programs ArcMap and STATISTICA 10. Based on statistical analysis, series maps of snow cover distribution was produced. Altitude, curvature, heat-load index, the orientation of the locality relative to the east (folded aspect with 0ř towards the east) and percentage of graminoid vegetation were the most important variables explaining snow depth. Furthermore the results of terrain measurements confirmed distribution snow cover of previous works. Key words: snow cover distribution, depth of snow, physical-geographical factors, modelling and measurement of snow cover, regression analysis, alpine forest-free area, east Krkonoše mountains
|
|
|
Effect of altitude on intra-annual growth of trees in the treeline ecotone
Kašpar, Jakub ; Treml, Václav (advisor) ; Gryc, Vladimír (referee)
RESUMÉ Tato práce se zabývá vlivem teplotních poměrů na intra-anuální růst smrku ztepitélo (Picea Abies (L.) Karsten) na alpínské hranici lesa v Krkonoších ve vegetačních sezónách 2011 a 2012. Monitoring probíhal na dvou lokalitách na jižním svahu Luční hory. První lokalita se nacházela v nadmořské výšce 1310 m n. m., přibližně na horní hranici zapojeného lesa, druhá pak v nadmořské výšce 1450 m n. m., ve stromových skupinkách nad horní hranicí lesa. Mezi lokalitami byl pozorován poměrně vysoký vertikální teplotní gradient jak u teplot vzduchu (1,2 - 1,7 řC), tak u teplot půdy v hloubce 10 cm (0,8 - 1,2 řC). Teplotní rozdíl mezi lokalitami se pak projevil v nižším pozorovaném přírůstu na výše položené lokalitě. Pozorované počátky kambiální aktivity se pohybovaly od 26. 4. do 21. 5. Začátek kambiální aktivity je ovlivněn množstvím sněhové pokrývky akumulované na lokalitách v průběhu zimy a s tím souvisejícím datem jejího odtátí, teplotami půdy a teplotami v přízemní vrstvě atmosféry. Délka kambiální aktivity se pohybovala mezi 55 - 77 dny, přičemž její délka byla nižší na výše položené lokalitě. Diferenciace buněk nastala bezprostředně po počátku kambiální aktivity a trvala od 111 do 132 dní. V porovnání sledovaných růstových sezón vyšla lépe růstová sezóna 2012, ve které byl průměrný přírůst stromů vyšší na...
|
|
|
Dendrochronological dating of the past avalanche events in the Krkonose Mts.
Tumajer, Jan ; Treml, Václav (advisor) ; Kociánová, Milena (referee)
Avalanches are important natural processes which shape the character of large mountainous areas. The reconstruction of their history has been performed on avalanche tracks in the Důl Bílého Labe Valley, Krkonoše Mts. through application of dendrogeomorphological methods. In total 101 trees from the area of 5 avalanche tracks were cored or cross-sectioned, which helped to identify 1253 growth disturbances (abrupt growth suppressions or releases, increases in tree-ring eccentricity, traumatic resin ducts, reaction wood, callus or determination of the tree death). The analysis spanning period from the 1859 led to the identification of 40 avalanche events, which prolong and complement written evidences of avalanche falls (avalanche cadastre). However, because of limitations of dendrogeomorphology (especially impossibility of dating of small events), these results have character of only minimal number of events. Strong influence of monthly snow melting and snow accumulation on initiation of events was pointed out through the statistical analysis of snowpack changes in relation to the reconstructed avalanche activity. Two main possible natural reasons for avalanche activity initiation were identified - vast spring snow melting and loading with fresh snow. The analysis demonstrates the potential of...
|
|
|
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.
|
guest ::
