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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Rekonstrukce a model postglaciálního šíření olší podrodu Alnus v Evropě / Reconstruction and model of postglacial spread of subgenus Alnus in Europe

Jelenová, Hana January 2017 (has links)
Many paradoxes exist about postglacial tree migration and they dont solve for many European trees. One example is wetland trees subgenus Alnus, which spread across Europe during the last glacial very quickly according to fossil records. The aim of this thesis is detection their migration potential, with the help of empirical evaluation of interpolated pollen data (interpolation method IDW) and a simulation model based on environmental characteristics of the species. The results of interpolated maps are similar to the rate previously estimated speed and the results of simulation model achieve these speeds only by A. incana but with specific extreme environmental conditions. The mason of this may be adapting its seeds to anemochorii because the simulation model confirmed their good potential to spread by the wind. Results of model for A. glutinosa don´t confirm the ability to rapidly spread by the wind and the observed rate must have another explanation. Maybe rivers can explain the empirical spread rate. This suggests visualization of migration lines and river networks. The model has also been disclosure of environmental properties that are related to migration potential. Within the parameterization of the model is demonstrated, that R0 of A. glutinosa is significantly better than A. incana. But main parameters of anemochory model are terminal velocity and generation time, which is shorter by the A. incana, and therefore is probably able to spread faster than A. glutinosa.
2

Komparace relativního stáří morén ve vybraných karech Vysokých Tater. / Relative age dating of moraines in selected High Tatras valleys

Procházková, Barbora January 2015 (has links)
The submitted diploma thesis deals with relative dating of the youngest glacigenic sediments (moraines) in the upper parts of some selected valleys in the High Tatra Mountains. These moraines were stabilized after the last cold events of the last glaciation cycle. The Schmidt hammer (SH) test was used for the assessment of their relative age. This method is based on the assumption that there is a mutual relation between the degree of weathering of a tested surface and the duration of its exposure. Information about the degree of weathering is expressed by the Rebound (R) value. The measurements were taken on fifteen moraines in four valleys in the High Tatra Mountains (Mengusovská, Velká Studená, Malá Studená and Litvorova valley). A large statistical population of measurements obtained from moraine surfaces were used to analyse the variability of R values means in the same lithology. The moraines were divided on the base of SH measurements into two groups of different age. R value means and standard deviation for these groups (SK_1: R=53,5±1,2 a SK_2: R=58,6±1,5) are significantly statistically different. The results of the weathering indexes were used for the reconstruction of the pattern of deglaciation in selected upper parts of valleys (cirques). Key words: relative dating, the Schmidt Hammer,...
3

Katalog obratlovčí fauny z pleistocénních lokalit na území Prahy / The catalogue of the mammalian fauna of pleistocenne localities in Prague area

Havlová, Tereza January 2014 (has links)
More than a hundred sites were in Prague in the past, where skeletal remains of Pleistocene mammals had been found. Most of these sites were brickyards or sand pits. These pits were in operation during the second half of the 19th century and first half of the 20th century. Many awards were found during construction works as well. Most of researchers attended only several most famous sites at the time of the findings. The catalog summarizes the basic known information about majority of Prague localities and includes a list of taxa wich were found there. Key words: Prague, locality, mammals, Pleistocene, brickyards, sand pits
4

Divergence zpěvu filipínských bulbulů (Pycnonotidae) na ostrovech / Song divergence of Philippine bulbuls (Pycnonotidae) on islands

Rulfová, Alena January 2014 (has links)
Bulbuls (Pycnonotidae) are a biologically diverse group of songbirds that produce a variety of vocalisations. Their songs are very audible, yet the vocal behaviour of the majority of bulbul species has not been formally described or subject to bioacoustical study. The Philippine bulbul (Ixos philippinus) is a sedentary and endemic species of the Philippine archipelago. This thesis presents the first detailed descriptions of its song. The songs were recorded on five islands locations that covered eight different habitats. Nine song features of these species were compared, in order to understand song variations between different islands. In searching for correlations, habitat types and geographical distances between the islands were also measured. The songs of the species found on five islands were readily split up into three groups based on end frequency, syllable number and song duration. The correlations possibly relate to a late Pleistocene connection between the islands and colonization routes of the species. It was found that song frequency parameters in bulbul species is primarily affected by habitat, whilst the effect of current distances between islands was shown to be weak.
5

Rekonstrukce paleoenviromentálních změn v pozdním pleistocénu pomocí multiproxy záznamu ze sprašové série Bůhzdař / Multiproxy evidence of Late Pleistocene environmental changes in the loess/paleosol sequence of Bůhzdař

Flašarová, Kristýna January 2016 (has links)
Loess-paleosol sequences preserve information that can be used to reconstruct paleoenvironement, specifically the climatic conditions and the vegetation present at the time of their formation. A dense network of reliably analyzed sequences from different geographic locations is crucial for representation of ecological and climatic trends during the Pleistocene (Frechen, 2011). The aim of this thesis is to fill the gap in the geographical distribution of well described loess-paleosol sequences in Central Europe. Therefore, it focuses on a loess- paleosol sequence in Bůhzdař, situated 9 km NW of Prague, Czech Republic. This profile was last studied in 1952 by naturalist Vojen Ložek. This thesis uses a number of analyses in order to get a multi-proxy record of local paleoenvironmental changes archived in a sequence of alternating loess sediments and paleosols in Bůhzdař. Geochemical approaches are combined with grain size distribution to define climatic conditions at the time of formation of the strata. Key words: loess/paleosol sequences, Bůhzdař, Czech Republic, particle size distribution, total organic carbon, XRF, XRD, stable isotopes 13 C and 18 O
6

Pojetí druhu u medvědovitých (Ursidae): praktická, historická a teoretická perspektiva / Concept of species in bears (Ursidae): practical, historical, and theoretical viewpoint

Wagner, Jan January 2012 (has links)
The present thesis surveys topic of taxonomic diversity and phylogeny of bears (Mammalia, Ursidae) and aspects of its contextual setting under effects of changing conceptual and methodological viewpoints. This problem is studied from several perspectives. The historical perspective is represented by a critical overview of the history of specific and infraspecific classification of bears with special respect to mutual influences of this classification and theoretical concepts of species accepted in particular periods. The perspective of material approach is exemplified by a material-based study of taxonomical and phyletic status of selected Pliocene to Middle Pleistocene ursine taxa. Along with deconstruction of some traditional hypotheses this produced a model explaining species diversification in ursine bears and its discussion in terms of factual relevance of included background concepts. In the pre-evolutionary period the bear species were usually understood broadly, as incipient immanent entities, yet exhibiting obvious certain infraspecific variability. This was established using definitions of varieties (mostly not identifiable with present subspecies or infraspecific taxa) considered as unstable modes of particular species. Although, in the post-Darwinian period, the concept and taxonomic...
7

Kontinentální zalednění severovýchodní části Frýdlantského výběžku / Continental glaciation of the northeastern part of the Frýdlant Spur

Lehejček, Jiří January 2012 (has links)
North-eastern part of Frýdlantský Spur is situated at the northern foothills of the Jizera Mountains. It represents an area, which was at least twice covered by North-European ice sheet during the Middle Pleistocene. At the same time, it is the region whose hills have the summits around the expected altitudinal limit of the maximum ice sheet extent. Therefore, it is a suitable area to study glacial trimline altitude. Schmidt hammer testing was applied to determine different state of rock surface weathering. Obtained R-values were taken as the most relevant data for glacial trimline determination. Nevertheless, other approaches (GIS analysis, outcrops, block fields and erratics mapping) were also incorporated. Interpretation of these approaches gave the altitudinal limit of ice sheets in the north-eastern part of the Frýdlantský Spur at 500 m a. s. l. ± 20 m.
8

Paleogeografický vývoj kenozoických říčních systémů ve středních a severních Čechách a jejich vztah ke klimatickým změnám a neotektonice / Paleogeographic development of the Cenozoic river systems in the central and northern Bohemia and its link to climatic changes and neotectonics

Štor, Tomáš January 2018 (has links)
The main aim of this thesis is to provide greater details on the timing of the fluvial river systems formation in the middle and the northern Bohemia. We focused on the Ploučnice River and Vltava River evolution. The river systems are very complex therefore we have used multiple approaches of the research with the disciplines range from geology, sedimentology, geomorphology, geochemistry, over different dating methods such as 10Be and 26Al isochron burial dating, optically stimulated luminescence dating and radiocarbon dating methods. Our results suggests that the terraces are significantly older than previously proposed. The fluvial style of the Ploučnice River system changes from high-energy braided to long-bend meandered river in the upper terrace levels (36 to 29 m above the modern river) and from high- to medium-energy braided river in the middle terrace levels (22-14 m). In the lower terrace levels (13 to 5 m) high-energy braided to long-bend meandered river environments were identified. Terraces were dating at 34 m, 29 m and 14 m above the modern floodplain with cosmogenic radionuclides while the 19 m, 12 m and 6 m above the modern floodplain terraces were dating with OSL. The time span represented by the river terraces remains unclear and varies from Eburonian to Eemian (1.68 to 0.056 Ma)....
9

Environmentální dynamika svrchního pleistocénu ve střední Evropě: multidisciplinární výzkum spraší, paleopůd a jezerních sedimentů / Upper Pleistocene environmental dynamics in central Europe: multidisciplinary research of loess/paleosols sequences and lacustrine sediments

Hošek, Jan January 2017 (has links)
The principal goal of this thesis was to provide relevant information on the spatiotemporal dynamics of erosion-sedimentation and weathering processes in the last climatic cycle and to interpret the obtained data in the context of European paleoenvironmental development. Representative sequences of loess, paleosols and lacustrine sediments from the area of the Bohemian Massif, the Carpathian Foredeep, the the Vienna Basin and the northern edge of the Panno-nian Basin were investigated using a wide range of instru-mental tools and paleontological methods. A uniform analytical approach applied to these sedimentary facies has provided ample new information about the paleoclimatolog-ical and paleoenvironmental development of East-Central Europe - an important region in the transition zone from oceanic to continental macro-climatic settings. The individu-al studies included in this PhD thesis cover the complete period of the Upper Pleistocene (MIS 5-2; ~130-12.7 ky BP) and are presented as separate chapters in the order of the superposition of strata. Chapters III/1-3 deal with the results of research into six loess/paleosol sequences (LPSs) situated in the Central Bohemian Massif, throughout the Moravian Valleys, and at the northwest and north edge of the Pannonian Basin. A detailed paleoenvironmental...

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