Sökning: "trophic cascades"

Visar resultat 6 - 10 av 21 avhandlingar innehållade orden trophic cascades.

1. 6. 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. 7. Predators in low arctic tundra and their impact on community structure and dynamics

   Författare :Maano Aunapuu; Tarja Oksanen; Ola Atlegrim; Oswald J. Schmitz; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; arthropods; coexistence; community dynamics; competition; food webs; hypothesis of exploitation ecosystems; intraguild predation; small mustelids; trophic cascades; Ekologi; Terrestrial; freshwater and marine ecology; 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

4. 8. Anthropogenic Disturbances and Shifts in Tropical Seagrass Ecosystems

   Författare :Johan S. Eklöf; Nils Kautsky; Patrik Rönnbäck; Teresa Alcoverro; Stockholms universitet; []
   Nyckelord :Aquaculture; feedback mechanisms; Kenya; management; overgrazing; regime shift; resilience; seagrass; seaweed farming; sea urchins; Tanzania; trophic cascades; Zanzibar; NATURAL SCIENCES; NATURVETENSKAP; Marine Ecotoxicology; marin ekotoxikologi;

   Sammanfattning : Seagrasses constitute the basis for diverse and productive ecosystems worldwide. In East Africa, they provide important ecosystem services (e.g. fisheries) but are potentially threatened by increasing resource use and lack of enforced management regulations. LÄS MER

5. 9. Food Web Ecology -- individual life-histories and ecological processes shape complex communities

   Författare :Martin Hartvig; Evolutionär ekologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; food web; community ecology; community assembly; size-structure; life-history omnivory; ontogeny; trophic interactions; trait based model; topology; emergent organisation; size-spectrum;

   Sammanfattning : This thesis sets out a food web framework for size-structured populations. The framework enables an ecological approach to food web modelling as the individual life-history from birth, through maturation, and ultimately death is explicitly resolved with the use of bioenergetics based on individual body size. LÄS MER

7. 10. Complexity and Change in a Simple Food Web : Studies in the Baltic Sea (FAO Area 27.IIId)

   Författare :Henrik Österblom; Sture Hansson; Robert W Furness; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Avian cholera; Bottom-up; Bycatch; Clupea harengus; Ecosystem; Food web; Gadus morhua; Halichoerus grypus; Regime shift; Sprattus sprattus; Top-down; Trophic cascade; Uria aalge; Marine ecology; Marin ekologi;

   Sammanfattning : An influence at one trophic level can result in dynamic impacts also on other components of a food web. These dynamics are known as trophic cascades, and can be both top-down and bottom-up. After a near-collapse of the Baltic cod Gadus morhua stock in the 1980s, its main prey sprat Sprattus sprattus increased dramatically. LÄS MER