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Biodiversity-productivity relationship in desmid communities
Škvorová, Marie ; Škaloud, Pavel (advisor) ; Nedbalová, Linda (referee)
This thesis deals with biodiversity-productivity relationship in desmid communities. Biodiversity is found to be changing globally. The biodiversity-productivity relationship is therefore an important research topic. Three aspects of biodiversity are thought to play an important role: species richness, functional diversity and phylogenetic diversity. It is known that in general, productivity is positively correlated with diversity. Interactions between different metrics of biodiversity are known less. Existing studies have shown that these interactions might be present. In general, biodiversity-productivity studies were mostly focused on plants. Less is known about other organisms, including algae. In this work I explore the relationship between overyielding and functional or phylogenetic diversity on a species richness gradient of desmid communities. I conducted an artificial biodiversity- ecosystem functioning experiment using combinations of two to 12 desmid species. Communities differed in the diversity aspects. I had measured the biomass growth. For the analysis, I have used the overyielding index, which is based on a comparison of a polyculture production with the production expected based on monoculture yields. The relationship of overyielding on functional diversity depended on species...
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How do bird species richness and abundance differ between military training areas and surrounding landscape? A case study from the Hradiště military area
Bušek, Ondřej
Since the beginning of the 20th century human land use changed drastically in Central Europe. These changes included: homogenization of the landscape mosaic, intensification of agriculture, urbanization and land abandonment. In turn, these changes affected bird species and perhaps most significantly manifested in population decline of open habitat birds. Therefore, it is important to investigate sites, which were not affected by the changes mentioned above, such as military training areas (MTAs) - places dedicated to training of armed forces. Previous studies have shown that MTAs seem to host remarkably high bird diversity and abundant populations of bird species of conservation concern. This may be caused by two major factors. First, closure of MTAs to all human activies besides military training spared them of the landscape changes mentioned above. Second, the military training itself produces a very heterogeneous habitat mosaic that allows coexistence of many species with different ecological requirements. To my knowledge, no study compared bird assemblages between MTAs and surrounding landscape directly. At the same time, such data are crucial to assess the value of MTAs for bird conservation reliably and, as a consequence, they enable to think more deeply about mechanism generating this value....
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Universality in biodiversity trends
Bohdalková, Eliška ; Storch, David (advisor) ; Keil, Petr (referee)
Biodiversity trends (such as the relationship between species richness and temperature or productivity) are always defined for a particular taxon at a specific area (the entire range of the taxon or often just a region arbitrarily chosen by researchers). The form of these trends varies between taxa and regions. The weak relationship between richness and temperature or productivity is sometimes interpreted as a counterevidence for the hypothesis explaining diversity patterns by these variables. However, the delimitation of taxa or region may play a crucial role for the form of the trends. The aim of this thesis is to determine whether some taxon properties (its size) or region properties (its area, range of explanatory variables, the temperature-productivity relationship or average temperature) affect the strength and slope of the richness-temperature and richness-productivity relationships. 46 data sets of species richness for a wide range of plants, invertebrates and ectothermic vertebrates within different regions of the world were used for the analysis. While the taxon size is likely to affect the strength and slope of the relationship when comparing individual (nested) subclades within larger clade, the comparison of different taxa in different regions of the world shows only the effect of the region...
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Drivers of avian diversity on an altitudinal gradient of Mount Cameroon
Djomo Nana, Eric ; Hořák, David (advisor) ; Šálek, Miroslav (referee) ; Waltert, Matthias (referee)
Altitudinal gradients constitute a powerful test system for understanding distribution of species around the globe. Tropical mountains are quite rich in species even after controlling for environmental productivity, and are ideally suited for studying patterns of species distributions because they have had sufficient time for species to produce a response to environmental changes that affect their life histories. In this thesis, I investigate basic ecological mechanisms potentially behind avian distribution patterns along an altitudinal gradient in West-Central Africa. I used data collected with four methodological approaches (point counts, mist netting, random walks and artificial nest experiments) along an altitudinal gradient on Mt. Cameroon from October 2011 to September 2013. This work is focused on two interrelated themes: selection pressures on life histories (Chapters 1, 2, 3 & 4), and avian assemblage structures (Chapters 5 & 6). In the General Introduction, I present an overview of the study area with conservation implications of the study and my study objectives. In Chapters 1, 2 & 3, I investigate how selection pressures, i.e., nest predation and parasitism by haematozoa, affect bird assemblages. I used artificial nest experiments to assess nest predation rates in Chapters 1 & 2, and my...
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Mountains as islands
Kačabová, Petra ; Storch, David (advisor) ; Ferenc, Michal (referee)
In this paper I deal with island biogeography and its applicability to isolated mountaintops, as an ecological equivalent of true islands. I discuss both true and mountain islands regarding their origin and the influence of long-term climate evolution on Earth. I underline some features of mountain islands, resulting from their topography and the dissimilarities of both types of island barriers. I find that mountain and true island communities might or might not have a number of species in a state of equilibrium, caused by balance between species immigration on island and their extinction. If the number of species on island is not in equilibrium, species extinction is not balanced by species immigration. I consider patterns of island communities, mainly nestedness, which has been frequently studied on mountain, as well as true islands. I discuss distribution patterns concerning invertebrates. And finally, I concentrate on recent methods of moutain island research and discuss mountain island isolation issues in terms of global warming.
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More-individuals hypothesis
Bohdalková, Eliška ; Storch, David (advisor) ; Sedláček, Ondřej (referee)
Gradients in species richness are often explained by variation in energy availability. Positive relationship between energy and number of species may be caused by many mechanisms. One of them is the 'more individuals' hypothesis (MIH). According to it greater energy availability enable more individuals to coexist and more individuals can be divided into more species with viable populations. However, authors do vary in exact formulation of the MIH and so they vary in predictions that they test. Review of literature has also revealed that studies are fundamentally different in the approach to testing MIH. Some studies examine whether mechanism of MIH can operate in real assemblages and they often give a positive answer. Other studies ask whether MIH is able to explain spatial patterns of species richness. The answer is mostly negative. Number of species is often closely related to energy without the mediating effect of the number of individuals. There is also the question whether the number of individuals really determines number of species, and not vice versa. However, these two variables are certainly linked. Therefore, regardless of the causality, the relationship between the number of individuals and number of species is worth exploring.
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How do bird species richness and abundance differ between military training areas and surrounding landscape? A case study from the Hradiště military area
Bušek, Ondřej ; Reif, Jiří (advisor) ; Koleček, Jaroslav (referee)
Since the beginning of the 20th century human land use changed drastically in Central Europe. These changes included: homogenization of the landscape mosaic, intensification of agriculture, urbanization and land abandonment. In turn, these changes affected bird species and perhaps most significantly manifested in population decline of open habitat birds. Therefore, it is important to investigate sites, which were not affected by the changes mentioned above, such as military training areas (MTAs) - places dedicated to training of armed forces. Previous studies have shown that MTAs seem to host remarkably high bird diversity and abundant populations of bird species of conservation concern. This may be caused by two major factors. First, closure of MTAs to all human activies besides military training spared them of the landscape changes mentioned above. Second, the military training itself produces a very heterogeneous habitat mosaic that allows coexistence of many species with different ecological requirements. To my knowledge, no study compared bird assemblages between MTAs and surrounding landscape directly. At the same time, such data are crucial to assess the value of MTAs for bird conservation reliably and, as a consequence, they enable to think more deeply about mechanism generating this value....
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Methods used to study the effects of grazing on vegetation
Hyklová, Lucie ; Münzbergová, Zuzana (advisor) ; Šlechtová, Anna (referee)
Calcareous grasslands are one of the most diverse habitats of Northern and Central Europe. Most of the calcareous grasslands were created by human agricultural activities and therefore they need some kind of management for their long-lasting maintenance. These habitats have been vanishing during last few decades and that's why there were many experiments provided all around the world to examine possible ways of their restoration and preservation. Grazing of livestock has been a traditional management in many places and is often being investigated nowadays. The aim of this work is to search and compare methods that are used to experimentally study the effects of grazing on vegetation. These experiments use different methods although they usually have the same goal - high species richness. Most of these studies are from Great Britain, Germany and states of Northern Europe. Average length of the experiment is seven years. Key words: grassland, grazing, management, restoration, methods, species richness
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Military training areas as anthropogenic biodiversity refuges
Bušek, Ondřej ; Reif, Jiří (advisor) ; Marhoul, Pavel (referee)
Military training areas are used by armed forces as training territories. These areas are exposed to intensive anthropogenic disturbances. It may seem paradoxical that a number of studies had shown that on those particular areas is often present remarkably high biodiversity and numerous species of conservation concern. In this respect, military training areas are more valuable than most parts of surrounding landscape and thus form true biodiversity refuges. Particularly important are those areas for open habitats species. There are two main causes of uniqueness of military training areas. First, they are closed for any human activities not connected to military training. Because of this, these areas were not exposed to negative influences such as agricultural intensification or urbanization. Second, military activities create very heterogeneous habitat mosaic. This allows coexistence of many species with different ecological requirements. However, biota of military training areas is currently endangered due to abandonment by armed forces caused by downsizing national troops. The end of unique disturbance regime caused by military training leads to gradual homogenization of landscape mosaic and therefore to population decline of habitat specialists. Subsequent commercial development of these areas is another...
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