Sökning: "Ekologi"
Visar resultat 16 - 20 av 1552 avhandlingar innehållade ordet Ekologi.
16. Mechanisms structuring the pelagic microbial food web : Importance of resource and predation
Sammanfattning : Temporal and spatial variations of pelagic microorganisms in the northern Baltic Sea were studied, as well as factors influencing their abundance and growth rates. Three main questions were asked 1) How does increased productivity influence the structure of the microbial food web? 2) Does predation limitation vary between trophic levels? 3) What is the relative importance of resource and predation limitation at different trophic levels?A field study in the northern Baltic Sea showed that dominating protozoa, flagellates and ciliates, increased with increasing primary productivity from north to south. LÄS MER
17. Ecology and Evolution of Adaptive Morphological Variation in Fish Populations
Sammanfattning : The work in this thesis deals with the ecology and evolution of adaptive individual variation. Ecologists have long used niche theory to describe the ecology of a species as a whole, treating conspecific individuals as ecological equivalent. LÄS MER
18. Plants go with the flow : predicting spatial distribution of plant species in the boreal forest
Sammanfattning : The main objectives of this thesis are to study if a topographic wetness index (TWI) could be used as a tool for predicting the spatial distribution of vascular plant species richness in the boreal forest as well as to study congruence in species richness between vascular plants, liverworts, mosses and lichens. A wetness index ln(a/tanβ) based on topography was used to assign a specific TWI-value to every 20 x 20m grid in two 25 km2 boreal forest landscapes (differing in average soil pH) in northern Sweden. LÄS MER
19. Predator-prey interactions in freshwater systems: The importance of chemical communication
Sammanfattning : Predator released chemical cues provide a valuable source of information to prey organisms that can be used to alter their behaviour in order to reduce predation risk. In this thesis, I have examined under what circumstances chemical cues may be used by prey, and if prey discriminate between different cues. LÄS MER
20. Structural Growth in Mountain Birch, Betula pubescens ssp. czerepanovii
Sammanfattning : In this thesis, I have studied long shoot performance in the monoecious, deciduous tree Betula pubescens ssp. czerepanovii. LÄS MER