Sökning: "habitat fragmentation"
Visar resultat 16 - 20 av 70 avhandlingar innehållade orden habitat fragmentation.
16. Population biology and conservation of beetles and pseudoscorpions associated with hollow oaks
Sammanfattning : Many species associated with old trees are threatened, as this habitat has decreased severely in Europe during the last 200 years. In old oaks, hollows with wood mould often form in the trunks and these harbour a specialized fauna mainly consisting of beetles, flies and pseudoscorpions. LÄS MER
17. European Black Grouse : MHC Genetic Diversity and Population Structure
Sammanfattning : Black grouse Tetrao tetrix is a bird species composed of large, continuous as well as severely reduced and fragmented populations, making it an optimal species to investigate how genetic diversity is affected by habitat fragmentation. I have focused on genetic diversity in the Major Histocompatibility Complex (MHC) to measure the ability of the black grouse to respond to environmental changes. LÄS MER
18. Biodiversity in fragmented boreal forests : assessing the past, the present and the future
Sammanfattning : The aims of this thesis are to (1) analyze the predictability (indicators) of plant and fungal species diversity in old-growth forests, and (2) assess the history and biodiversity of woodland key habitats (WKHs) and their potential to maintain species diversity in fragmented boreal forest landscapes. Predictability was explored in Granlandet nature reserve, an unexploited landscape composed of discrete old-growth Picea forest patches of varying size isolated by wetland, reflecting conditions of insular biota at stochastic equilibrium. LÄS MER
19. Butterfly Diversity and Dispersal in Fragmented Grasslands
Sammanfattning : During the last decades, the distribution and abundance of many European species of birds, plants and insects in agricultural landscapes have declined due to agricultural intensification. To be able to mitigate these declines, it is essential to know the relative importance on local and regional ecological processes on population persistence and patterns of species richness. LÄS MER
20. Species extinctions in food webs : local and regional processes
Sammanfattning : Loss of biodiversity is one of the most severe threats to the ecosystems of the world. The major causes behind the high population and species extinction rates are anthropogenic activities such as overharvesting of natural populations, pollution, climate change and destruction and fragmentation of natural habitats. LÄS MER
