Sökning: "environmental niche"
Visar resultat 1 - 5 av 68 avhandlingar innehållade orden environmental niche.
1. Miljörörelsens mångfald
Sammanfattning : In the thesis, the conditions, possibilities, and limitations for Swedish environmental organisations to influence other actors — state agencies, political organisations, enterprises and the Swedish public — are analysed. The focus is on their practice in the nineties, implying a context in which different actors, to a greater extent, have accepted the significance of environmental issues, demand knowledge of and solutions to environmental problems, and with new conflicts continously arising. LÄS MER
2. Species interactions in streams - effects of predation, competition and ecosystem properties
Sammanfattning : Stream ecosystems are dynamic and they have an inherent environmental variability. Organisms that live in streams are adapted to the continuously changing environment and the presence or absence of species are determined by their environmental requirements, while abundance is most often affected by interactions, such as competition and predation, with other species that are found in the same habitat. LÄS MER
3. Coping with environmental change : Lessons from isotope studies in a sentinel species
Sammanfattning : Adaptive evolution and phenotypic plasticity are two key mechanisms by which natural populations avoid extinction in the face of environmental change. Evolutionary young systems, such as the Baltic Sea with low species diversity and steep environmental gradients, are good models for studying how wild populations cope with environmental changes, such as climate-induced alterations in food supply and exposure to environmental contaminants. LÄS MER
4. Dynamics of omnivorous crayfish in freshwater ecosystems
Sammanfattning : In this thesis I examine the dynamics of crayfish in streams and lakes. I have studied the influence of abiotic and biotic factors on abundance, growth, trophic position, niche breadth, and recruitment of crayfish, by conducting field studies, an outdoor channel experiment and timeseries analysis. LÄS MER
5. The role of young-of-the-year fish in lake ecosystems
Sammanfattning : Food chain theory is based on consumption; that is, presupposing that the only important interaction between organisms is that they actually meet in an unstructured environment and that one of them is consumed. Recently, studies, including biomanipulation projects, have indicated that trophic interactions are more complex than predicted by food chain theory. LÄS MER
