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All organisms, including plants, experience variability in the environment which puts pressure on organisms to evolve flexible responses. The study of these responses by organisms falls into the discipline of behavioural ecology. In this thesis, I am interested in the foraging behaviour of plant roots and I have two goals. First, I will use foraging theory from the animal literature to determine whether plants forage in ways that are similar to animals. Second, I will show how the adoption of foraging theory for plants can lead to a better theoretical understanding of coexistence of plants. I begin with a discussion of the major differences between plants and animals in their foraging behaviour and how this can be incorporated in to a more general predictive framework of plant foraging behaviour. I follow this discussion with two empirical tests of classic foraging models. First, I test a patch use model from the animal literature to determine if it can predict plant foraging behaviour. My results show that plants foraged for patches using the same strategies used by animals. Second, I test a resource choice model from the animal literature. These data indicated that plants select different types of nitrogen using the same resource choice strategies as foraging animals. These two studies reveal some basic foraging abilities of plants, however the experiments were performed in the absence of resource competition, a condition seldom experienced by plants in nature. To overcome difficulties in studying plant roots grown with neighbours I developed a molecular method for the identification of visually indistinguishable plant roots from competition experiments. Finally, I apply the molecular method to examine whether resource patchiness in soil can increase the intensity of competition experienced by foraging plants, and that the presence of neighbours influences the foraging strategies of plants. Together the results presented in this thesis show that plants use the same basic foraging strategies as animals, and that foraging behaviour can be linked to competition and coexistence of plant species. / Ecology

This thesis is focused on the analysis of eurasian beavers foraging behaviour and their strategy of getting food in the long-term perspective. First part (theoretical) of the thesis contains an explanation of the theory of the central place foraging, animal selective behaviour when food is selected and central place foraging influence on trees fertility. In this part is also mentioned the predation risk or how does the beaver perceives competitive pressure from other animals, and factors that can cause the change in population density of beaver colonies. The objective of this work is to determine the effect of long-term beaver populating on the volume of comsumed biomass and expanse of the territory, and a comparison of these results with one another in terms of different times of occupated territories. The second part describes the methodical procedure of the field survey. Data I collected from the areas of Šumava, Český les and South Moravia. I tried to find out, how the beaver´s foraging behaviour is induced depending on time inhabiting the territory and on increasing distance from the shore. This research shows that the beaver trips for food increases with age of occupation in 7-10 years and then the distance of tree cuts declined again from the shore. The volume of consumed biomass in reliance of increasing time of beaver occupation also decline and the most favoured tree species was an oak tree for which beavers were willing to walk long distances. The results of the simple analysis are presented as a measurement for both the entire region and also for each territory.

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