National Repository of Grey Literature 22 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Decisions in seed reproduction in plants
Mašková, Tereza ; Herben, Tomáš (advisor) ; Thompson, Ken (referee) ; Těšitel, Jakub (referee)
Seed reproduction is a key part of the life cycle of the most plant species. It allows for the dispersal of species in space and time and, thus, significantly affects dynamics of plant populations and communities. Seed formation, germination and seedling establishment are subjected to selection pressures from the environment and lead to optimization of maternal investments (maternal care), manifested by the number of seeds and amount and composition of nutrients stored in individual seeds. The thesis aims to answer two questions: (i) whether maternal investments in terms of seed mass and seed nutrient stoichiometry is optimized according to the environmental conditions in which seedling development is expected and (ii) how nutrient availability, considering nutrients both stored in the seed by the mother plant and those available in the substrate, affects seedling growth and development. To answer the first question, we focused on interspecific comparisons of seed nutrient stoichiometry linking it with data on seed mass and species niche along gradients of nu- trient availability. We used a phylogenetically informed comparative approach to explore the ratio between phosphorus, nitrogen and nonstructural carbon in seeds from 510 wild herbaceous species. We analyzed seed nutrient stoichiometry with...
Effects of wild ungulates on vegetation in an abandoned landscape
Horčičková, Eva ; Herben, Tomáš (advisor) ; Diekmann, Martin (referee) ; Tichý, Lubomír (referee)
Wild ungulates are considered one of the major drivers for shaping terrestrial ecosystems, which has been developing since the early Cenozoic. Understanding the effects of ungfulates on vegetation is necessary for qualified knowledge how European landscape looked prior to human habitation and how it would look like without human intervention. Further, such understanding is of practical importance as management information necessary for managing abandoned landscapes. While the present-day wild ungulate European fauna does not contain several large grazers like auroch (Bos primigenius) anymore, the landscape has long been affected by them. It thus possesses historical experience of response to large grazers, which has been further maintained by livestock grazing. Importantly, the European landscape is experiencing a steady increase of populations of deer (Cervidae) and wild boar (Sus scrofa) with major effects of vegetation and landscape structure. While the effects of these present-day dominants have been studied mainly in forest habitats, there is a growing evidence that they both promote species diversity of forest understory and, interestingly, preferably feed in open vegetation and thus can affect broader landscape heterogeneity. The main aim of this thesis is therefore to examine effects of...
Role of phenology in differentiation of plant niches: quantitative and comparative approach using a large set of species
Huang, Lin ; Herben, Tomáš (advisor) ; van Kleunen, Mark (referee) ; Dostál, Petr (referee)
Niche differentiation is the most recognized species coexistence mechanism, of which, the temporal differentiation of species, i.e. phenological differentiation has gained an increasing interest of ecologists. However, as an important dimension of phenology, the phenology of growth has drawn relatively few attentions due to the lack of sufficient phenological data. Therefore, the aim of this thesis is to examine potential role of temporal differentiation of plant growth patterns in plant coexistence. I first collected data on growth phenology of 381 perennial herbs in the Botanical Garden of Charles University in Prague within one growing season (in 2015). Using this database, I addressed the general patterns of growth phenology among perennial herbs. I distinguished two contrasting growth patterns: (1) species with early peak growth had high standardized growth rates in contrast to late species, reflecting the survival under forest canopy, where species are selected to grow early and fast before the development of tree canopy which restricts their size; (2) tall species showed later peak growth than short species, associating with (asymmetric) competition for light in open habitats, where the main selection factor is for tall stature, which cannot be attained early in the season. Then, by linking...
Study of plant dispersal in river corridors using molecular marker
Fér, Tomáš ; Herben, Tomáš (advisor) ; Chrtek, Jindřich (referee) ; Tribsch, Andreas (referee)
5 Summary The thesis presents how the use of molecular markers (AFLPs and microsatellites) can help when studying plant dispersal in river systems. Analysis and interpretation of the spatial pattern of genetic variation allowed to address and discuss following aspects of long-distance dispersal in these linearly structured systems: (1) the extent of long-distance dispersal, (2) the intensity of vegetative long-distance dispersal, (3) unidirectional transport along the streams, and (4) dispersal among rivers. The first part of the PhD. thesis presents several general aspects of plant dispersal, methodological approaches used to detect dispersal, and possibilities of analysis and interpretation of the molecular data. It also gives a short introduction to the methodology used in the particular studies, summarizes the results of all studies, and discusses how differences detected by molecular markers correspond to dispersal possibility (e.g., by water, by wind) of the selected species. The second part contains a set of four papers, each focusing on a detailed survey of dispersal possibilities of one of four plant species within the river system of the Cidlina, the Mrlina and partly also the Labe Rivers (Czech Republic). Above- mentioned aspects of dispersal in river systems are further discussed in the light...
Plant body as a behavioural platform - an ecologist's insight
Weiser, Martin ; Herben, Tomáš (advisor) ; Šmilauer, Petr (referee) ; Novoplansky, Ariel (referee)
Conceptualisation of plant behaviour, or plant phenotypic plasticity, has been proven to be useful both on the ecosystem scale and on the level of individuals, as it allows to predict differentiation of species across ecosystems or results of interactions among individuals. Between these extremes is a vast array of processes that drive community assembly. These processes are difficult to predict, be it at the individual level or based on whether a whole species is plastic or non-plastic. These processes are traditionally investigated at the species level. In this thesis, however, I instead show how species-specific life histories delineate plant behaviour. I hope to convince the reader that it is the plant body, or at least its species-specific properties, not merely its non-specific, theoretical degree of plasticity, that should be used to explain actual cases where plant behaviour underpins species coexistence. As evidence for my case, I present four studies, each of them dealing with different part of the plant body that underlies different aspects of plant behaviour. In the first study, I show how species' life- history traits are coordinated with their responses to neighbour presence and resource shortage, both of these delivered in the form of changing light quantity and quality. Not only the...
Community ecology from the perspective of classic and bayesian statistics
Klimeš, Adam ; Keil, Petr (advisor) ; Herben, Tomáš (referee)
Community ecology from the perspective of classic and Bayesian statistics Ekologie společenstev z hlediska klasické a Bayesovské statistiky Řešitel: Adam Klimeš Vedoucí práce: Mgr. Petr Keil, Ph.D. Abstract Quantitative evaluation of evidence through statistics is a central part of present-day science. Bayesian approach represents an emerging but rapidly developing enrichment of statistical analysis. The approach differs in its foundations from the classic methods. These differences, such as the different interpretation of probability, are often seen as obstacles for acceptance of Bayesian approach. In this thesis I outline ways to deal with the assumptions of Bayesian approach, and I address the main objections against it. I present Bayesian approach as a new way to handle data to answer scientific questions. I do this from a standpoint of community ecology: I illustrate the novelty that Bayesian approach brings to data analysis of typical community ecology data, specifically, the analysis of multivariate datasets. I focus on principal component analysis, one of the typical and frequently used analytical techniques. I execute Bayesian analyses that are analogical to the classic principal components analysis, I report the advantages of the Bayesian version, such as the possibility of working with...
The role of biotic interactions in population biology of meadow plants
Janovský, Zdeněk ; Herben, Tomáš (advisor) ; Lepš, Jan (referee) ; Ehrlen, Johan (referee)
In present thesis, I treat the topic of impacts of plant-animal interactions, namely herbivory and pollination, on plant life cycle and lifetime fitness. First, I identify the components of the impact of plant-animal interactions: i) interaction frequency; ii) per-interaction effect; iii) sensitivity of the plant's life cycle to the changes in vital rate impacted by the animals. Furthermore, I also classify other causes changing the outcome of a plant-animal interaction into two categories: i) plant's traits; ii) plant's environment. A review of extant literature on the topic revealed that especially the role of plant's environment in changing the outcome of plant-animal interactions is largely understudied and I attempt to reduce this gap in knowledge in the five detailed studies encompassed in this thesis. The detailed studies focus on a model system of Central European wet grasslands and especially on three species typical to it: Succisa pratensis, Achillea millefolium and A. ptarmica. The first two studies examine the effects of environment on frequency of plant- animal interactions. The next two studies are more integrative, one focusing on the impacts of different herbivore groups on the complete life cycle and the other on interaction of herbivory and pollination on plant lifetime fitness....
Dynamical pollination models
Smyčka, Jan ; Herben, Tomáš (advisor) ; Těšitel, Jakub (referee)
Dynamical pollination models (abstract) Pollination is a complex biological phenomenon which may include many interacting plant and animal species. In such a case, and especially when we are interested in effects of spatial structure, it can be helpful to use some formal approach of study, as is dynamical modelling. This thesis describes common methods for pollination modelling in space. The pollination can be divided into two consequent processes - pollinator movement and pollen carryover. Simple method of pollination movement modelling is using some random particle movement patterns, e.g. Brownian motion. This approach is useful mostly for systems with one plant species, or at large scales. More accurate, but difficult, posibility is modelling pollinators" movement through some decision making process based on their behaviour. Pollen carryover models are the necessary "translation" of pollinator movement to variables important for plants. A part of this work is also an analysis of certain pollination models. Their assumptions, predictions and modifications for not yet tackled problems are discussed.
Horses and vegetation
Třeštíková, Tereza ; Herben, Tomáš (advisor) ; Mládek, Jan (referee)
Many studies show that large herbivores can have an important impact on the composition of vegetation. With the establishment of a year round, low density grazing regime, plant ecologists and nature managers expect that through selective grazing, herbivores will create a mosaic of different vegetation communities varying in structure and plant species composition. It is believed that such a mosaic in the end will guarantee a high degree of biodiversity. Grazing will, therefore, seem to be a suitable means to maintain grass. Also important is the ability of herbivores affect vegetation through endozoochory. In this thesis I have tried to find out what species of diet horses prefer regarding to plant species and what plant species they can spread through out endozoochory. I have compared this knowledge with the composition of pasture and meadow vegetation at the researched locality in Malenice and Hoslovice. With the purpose of finding out the preferences I established spots where I registered data on vegetation before pasture and the time intervals during the pasture. Afterwards, I researched the amount of sprouts and the composition of seedlings in excrements that I let germinate. I had to create phytocenologic shots from the pastures and meadows to compare the species of composition of grazed and...

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