Sökning: "habitat quality"

Visar resultat 1 - 5 av 81 avhandlingar innehållade orden habitat quality.

  1. 1. Metapopulation ecology of Osmoderma eremita - dispersal, habitat quality and habitat history

    Författare :Jonas Hedin; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; extinction debt; habitat history; habitat quality; pheromone; telemetry; capture-mark-recapture; metapopulation; dispersal; oak; Osmoderma eremita; beetle; Animal ecology; Djurekologi;

    Sammanfattning : This thesis starts with a review of different biodiversity assessment methods in forests and the rest deals with the metapopulation ecology of Osmoderma eremita, a threatened beetle living in hollow trees. I concentrate on the effect of dispersal, habitat quality and habitat history for the presence, population size and future survival of this species. LÄS MER

  2. 2. The long-term decline of the grey-sided vole (Clethrionomys rufocanus) in boreal Sweden: importance of focal forest patch and matrix

    Författare :Pernilla Christensen; Birger Hörnfeldt; Rolf A. Ims; Umeå universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; : Destructive sampling; high quality habitat; focal habitat; landscape; habitat fragmentation; threshold; clear-cut; patch size and quality; long-term time-series; Terrestrial ecology; Terrestisk ekologi;

    Sammanfattning : There has been a long-term decline in number of cyclic vole populations in boreal Sweden since the 1970s. Several hypotheses have been suggested to explain this decline. Commonly for C. glareolus, C. LÄS MER

  3. 3. Through the eyes of a woodpecker: Understanding habitat selection, territory quality and reproductive decisions from individual behaviour

    Författare :Ola Olsson; Biodiversitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; reproductive success; territory quality; habitat selection; giving-up density; Bayesian processes; foraging; Picidae; lesser spotted woodpecker; Dendrocopos minor; conservation; Animal ecology; Djurekologi;

    Sammanfattning : In this thesis I present some connections between foraging behaviour and reproductive success, time budget, tree species use, and habitat selection. The thesis is based upon both theoretical and empirical work. All empirical studies concern a south Swedish population of lesser spotted woodpeckers Dendrocopos minor, studied between 1990 and 1996. LÄS MER

  4. 4. Regional and local variation in plant species richness

    Författare :Cecilia Dupré; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Developmental biology; coastal meadows; deciduous forests; dry grasslands; grazing; habitat configuration; habitat quality; hump-shaped curve; life history traits; regional species pool; soil factors; Utvecklingsbiologi; Developmental biology; Utvecklingsbiologi; ekologisk botanik; Ecological Botany;

    Sammanfattning : In this thesis, I examine the variation in plant species richness along gradients of productivity and disturbance in grasslands and forest habitats in southern Sweden, and I compare the documented patterns with theoretical predictions. Moreover, I evaluate the relative importance of habitat quality and habitat configuration for the occurrence of field layer species in deciduous forests. LÄS MER

  5. 5. The function of seasonal habitat shifts in two congeneric mayflies in a boreal river

    Författare :Olle Söderström; Umeå universitet; []
    Nyckelord :AGRICULTURAL SCIENCES; LANTBRUKSVETENSKAPER; Habitat utilization; diel activity; orientation; predation; life-history; temperature; food quality; mayflies; Parameletus chelifer; Parameletus minor;

    Sammanfattning : Unregulated North Swedish rivers show large seasonal variations in their physical characteristics. During winter the whole littoral zone freezes solid, and in spring the water flow increases rapidly and the same areas become flooded. The two mayflies Parameletus chelifer and P. minor are common in the North Swedish river Vindelälven. LÄS MER