Sökning: "Ekologi"

Visar resultat 1 - 5 av 1129 avhandlingar innehållade ordet Ekologi.

  1. 1. Predator-prey interactions in freshwater systems: The importance of chemical communication

    Detta är en avhandling från Kajsa Åbjörnsson, Limnology, Ecology Building, S-223 62 Lund, Sweden

    Författare :Kajsa Åbjörnsson; Lunds universitet.; Lund University.; [2002]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; aquatic ecology; marine biology; limnology; Marinbiologi; limnologi; akvatisk ekologi; Ecology; Ekologi; Hydrobiology; trophic cascades; non-lethal effects; benefits; costs; heredity; predator experience; alarmsubstances; dietary cues; amphibian larvae; invertebrates; visibility; fish; behaviour; Predator-prey; chemical cues;

    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

  2. 2. Predators in low arctic tundra and their impact on community structure and dynamics

    Detta är en avhandling från Umeå : Ekologi och geovetenskap

    Författare :Maano Aunapuu; Umeå universitet.; [2004]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; arthropods; coexistence; community dynamics; competition; food webs; hypothesis of exploitation ecosystems; intraguild predation; small mustelids; trophic cascades; Ekologi; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology; NATURVETENSKAP Biologi Terrestisk; limnisk och marin ekologi; zooekologi; Animal Ecology;

    Sammanfattning : The abundance of predators and their impact on ecosystem dynamics is a vividly discussed topic in current ecology. In my studies, incorporating field observations, field experiments and theoretical modeling, I explored the importance of predators and predation in a low arctic tundra ecosystem in northern Norway. LÄS MER

  3. 3. Macroalgae in the Baltic Sea responses to low salinity and nutrient enrichment in Ceramium and Fucus

    Detta är en avhandling från Umeå : Ekologi och geovetenskap

    Författare :Lena Bergström; Umeå universitet.; [2005]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; adaptation; asexual reproduction; Baltic Sea; Gulf of Bothnia; salinity; macroalgae; nutrients; sexual reproduction; stress; Ekologi; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology; NATURVETENSKAP Biologi Terrestisk; limnisk och marin ekologi; ekologisk botanik; Ecological Botany;

    Sammanfattning : The brackish Baltic Sea is a marginal environment for both marine and freshwater species. The rate of ecological differentiation is presumably high due to strong selection pressure from a gradient of decreasing salinity that has been present in its current state for only about 3 000 years. LÄS MER

  4. 4. Vegetation patterns and processes in riparian landscapes

    Detta är en avhandling från Umeå : Ekologi och geovetenskap

    Författare :Birgitta Malm Renöfält; Umeå universitet.; [2004]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Ekologi; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology; NATURVETENSKAP Biologi Terrestisk; limnisk och marin ekologi;

    Sammanfattning : The objective of this study was to increase understanding of the processes structuring and controlling the species richness of riparian plant communities. In particular, I examined the unimodal relationship, found in many rivers, between plant species richness and location along the river corridor. LÄS MER

  5. 5. Plants go with the flow predicting spatial distribution of plant species in the boreal forest

    Detta är en avhandling från Umeå : Ekologi och geovetenskap

    Författare :Ursula Zinko; Umeå universitet.; [2004]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; boreal forest; vascular plant; species richness; wetness index; soil pH; bryophyte; lichen; substrate; stand age; plot size; Ekologi; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology; NATURVETENSKAP Biologi Terrestisk; limnisk och marin ekologi; ekologisk botanik; Ecological Botany;

    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