Sökning: "Lauri Oksanen"

Hittade 3 avhandlingar innehållade orden Lauri Oksanen.

  1. 1. Interactions between gray-sided voles (Clethrionomys rufocanus) and vegetation in the Fennoscandian tundra

    Författare :Jonas Dahlgren; Lauri Oksanen; Johan Olofsson; John Terborgh; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; gray-sided voles; tundra vegetation; trophic cascades; plant-herbivore interactions; bilberry; plant communities; herbivory; plant resistance; Terrestrial ecology; Terrestisk ekologi;

    Sammanfattning : I have, in this thesis, studied the interactions between gray-sided voles (Clethrionomys rufocanus) and tundra vegetation, on islands in, and mainland sites close to the lake Iešjávri, in northern Norway. As isolated islands are virtually free of predation, I have been able to compare plant-herbivore interactions in the presence and absence of predators. LÄS MER

  3. 2. Population dynamics of tundra-living grey-sided voles

    Författare :Per Ekerholm; Lauri Oksanen; Rolf Anker Ims; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Population dynamics; Tundra; Grey-sided vole; Cycles; Vole specialist predators; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; zooekologi; Animal Ecology;

    Sammanfattning : This thesis deals with the dynamics of tundra living voles with emphasis on the most common one, the grey-sided vole (Clethrionomys rufocanus). The tundra area chosen for the study was Finnmarksvidda, a vast flatland in northernmost Norway. LÄS MER

  4. 3. Top-down and bottom-up effects in a Fennoscandian tundra community

    Författare :Doris Grellmann; Lars Ericson; Lauri Oksanen; Richard Inouye; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; consumer-resource interactions; exclosures; food web dynamics; grey-sided voles; lemmings; NPK-fertilization; plant defences; reindeer; soil microbes; vertebrate grazing;

    Sammanfattning : The objective of this thesis was to investigate the effects of mammalian grazers, such as microtine rodents and reindeer, (top-down effects) and nutrient availability (bottom- up effects) on the plant community of a tundra heath.I conducted a large-scale fertilization experiment and studied the impact of grazers using exclosures. LÄS MER