Sökning: "habitat fragmentation"

Visar resultat 1 - 5 av 70 avhandlingar innehållade orden habitat fragmentation.

  1. 1. Semi-natural grasslands: landscape, history and plant species diversity

    Författare :Lotten Jönsson; Institutionen för naturgeografi och ekosystemvetenskap; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; aerial photographs; Land-use history; cadastral maps; habitat continuity; fragmentation; landscape context; habitat connectivity;

    Sammanfattning : This thesis explores the impact of past and present landscape and habitat structure on present levels of vascular plant species diversity within fragmented semi-natural grasslands. Within the Jordtorp-area, a mosaic agricultural landscape on the island of Öland (Sweden), historical land-use changes and the development of semi-natural grasslands was characterized, over a time-period of almost 300 years, using historical maps, aerial photographs and a high-resolution imagery. LÄS MER

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

    Författare :Jonas Hedin; Biologiska institutionen; []
    Nyckelord :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

  4. 3. Habitat composition and restocking for conservation of the white-backed woodpecker in Sweden

    Författare :Kristoffer Stighäll; Per-Erik Olsson; Grzegorz Mikusinski; Örebro universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; White-backed woodpecker; Dendrocopos leucotos; Sweden; deciduous forest; suitable habitat; fragmentation; saproxylic insects; captive breeding; restocking; Biology; Biologi;

    Sammanfattning : In Sweden, intense human land use, especially forestry, has led to profound changes in the landscape over time, especially within the forest ecosystems. A consequence of this is that several specialist species have become endangered. One group of specialists is the woodpeckers. LÄS MER

  5. 4. 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 :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

  7. 5. Plant species diversity in semi-natural grasslands. Effects of scale, landscape structure and habitat history

    Författare :Triin Reitalu; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; habitat fragmentation; landscape diversity; habitat connectivity; historical maps; continuity; land-use history;

    Sammanfattning : The thesis examines the impact of present and past landscape structure, habitat history and management on different aspects of present-day plant species diversity in fragmented semi-natural grasslands in Sweden and in Estonia. Species diversity was significantly associated with present and/or past grassland connectivity in the majority of the studies in the thesis. LÄS MER