Sökning: "trophic level effect"

Visar resultat 1 - 5 av 25 avhandlingar innehållade orden trophic level effect.

  1. 1. Perspectives from a human-centred archaeology : Iron Age people and society on Öland

    Detta är en avhandling från Lund University

    Författare :Helene Wilhelmson; [2017-03-15]
    Nyckelord :HUMANIORA; HUMANITIES; Osteology; bioarchaeology; Iron Age; Scandinavia; 3D; digital; Image Based Modeling; GIS; isotopes; Oxygen; Strontium; Carbon; Nitrogen; trophic level effect; fractionation; chronology; network; Virtual Taphonomy; human-centred archaeology; mortographies; dietary shift; integration; immigration; diet; migration; violence; burial; Viking Age; Öland; island;

    Sammanfattning : The objective of this study was to develop, test and evaluate a specifically defined interdisciplinary approach—the human-centred approach—as applied to a case study, Iron Age Öland. Four themes were selected to highlight different aspects of particular interest in Öland: taphonomy, diet, migration, and social organization. LÄS MER

  2. 2. Food web dynamics in open and closed systems

    Detta är en avhandling från Lund University

    Författare :Johan Lövgren; Lennart Persson; Jonathan Chase; [2004]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; allochtonous input; cross habitat foraging; donor control; heterogeneity within trophic level; compensation; food web; littoral; Ekologi; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology; NATURVETENSKAP Biologi Terrestisk; limnisk och marin ekologi;

    Sammanfattning : This thesis is a summary of enclosure and microcosm experiments that aimed to study the impact of allochtonous subsidies on food web dynamics in a heterogeneous food web. In the enclosure studies, a three trophic level littoral food web was used. LÄS MER

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

    Detta är en avhandling från Stockholm : Institutionen för systemekologi

    Författare :Henrik Österblom; Sture Hansson; Robert W Furness; [2006]
    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; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology Marine ecology; NATURVETENSKAP Biologi Terrestisk; limnisk och marin ekologi 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

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

    Detta är en avhandling från Umeå : Ekologi, miljö och geovetenskap

    Författare :Jonas Dahlgren; Lauri Oksanen; Johan Olofsson; John Terborgh; [2006]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; gray-sided voles; tundra vegetation; trophic cascades; plant-herbivore interactions; bilberry; plant communities; herbivory; plant resistance; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology Terrestrial ecology; NATURVETENSKAP Biologi Terrestisk; limnisk och marin ekologi 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

  5. 5. Trophic effects on the maintenance of biodiversity in the Fucus zone

    Detta är en avhandling från Stockholm : Botaniska institutionen

    Författare :Sonja Råberg; Lena Kautsky; Christer Brönmark; [2007]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biodiversity; epiphytes; eutrophication; faunal assemblage; filamentous algae; Fucus radicans; Fucus vesiculosus; grazers; nutrient supply; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology Marine ecology; NATURVETENSKAP Biologi Terrestisk; limnisk och marin ekologi Marin ekologi; Plant Ecology; växtekologi;

    Sammanfattning : Ecologically important macroalgae with large thalli and complex structures are threatened worldwide due to anthropogenic activities such as pollution. In the northern Baltic Sea the salinity is very low; the only large algae producing complex structural habitats found there are the fucoid species Fucus radicans and F. vesiculosus. LÄS MER