Sökning: "Pär Byström"

Visar resultat 1 - 5 av 8 avhandlingar innehållade orden Pär Byström.

  1. 1. En broder, gäst och parasit : Uppfattningar och föreställningar om utlänningar, flyktingar och flyktingpolitik i svensk offentlig debatt 1942-1947

    Författare :Mikael Byström; Klas Åmark; Pär Frohnert; Lena Berggren; Stockholms universitet; []
    Nyckelord :HUMANIORA; HUMANITIES; Sweden; Second world war; foreigners; refugees; refugee policy; ethnicity; Nordic prerogative; History; Historia;

    Sammanfattning : Earlier studies have proposed that Swedish refugee policy started to change around 1942, when a restrictive refugee policy became more generous and humanitarian. From a quantitative point of view this statement is true: there were about ten thousand refugees in 1941, compared to almost two hundred thousand by the end of the war. LÄS MER

  3. 2. Effects of temperature and terrestrial carbon on primary production in lake ecosystems

    Författare :Mohammed Hamdan; Jan Karlsson; Pär Byström; Erin R. Hotchkiss; Lars-Anders Hansson; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; lakes; primary production; benthic; pelagic; carbon dioxide limitation; light limitation; nutrient limitation; browning; warming; allochthonous carbon; grazing; trophic cascades;

    Sammanfattning : Climate warming is predicted to affect northern lake food webs in two ways: (1)directly via changes in water temperature and ice conditions, and (2) indirectlyvia changes in catchment characteristics and processes that influence input ofallochthonous coloured dissolved organic matter (cDOM) and nutrients. Input ofcDOM increases carbon dioxide (CO2) availability, causes brownification andreduced light conditions, and may increase nutrient availability especially forpelagic primary producers. LÄS MER

  4. 3. Climate change impacts on production and dynamics of fish populations

    Författare :Per Hedström; Pär Byström; Jan Karlsson; Peter Eklöv; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Temperature; terrestrial dissolved organic carbon; light extinction; GPP; recruitment; winter mortality; metabolism; cohort competition; fish production; fish biomass;

    Sammanfattning : Ongoing climate change is predicted to increase water temperatures and export of terrestrial dissolved matter (TDOM) to aquatic ecosystems influencing ecosystem productivity, food web dynamics and production of top consumers. Ecosystem productivity is mainly determined by the rates of primary production (GPP) in turn controlled by nutrients, light availability and temperature, while temperature alone affect vital rates like consumption and metabolic rates and maintenance requirements of consumers. LÄS MER

  5. 4. Ontogenetic scaling and the development of within-cohort size structure

    Författare :Magnus Huss; Lennart Persson; Pär Byström; David Post; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; cannibalism; competition; density-dependence; resource feedbacks; hatching; growth; ontogenetic niche shifts; Perca fluviatilis; size variation; larval fish; Freshwater ecology; Limnisk ekologi; zooekologi; Animal Ecology;

    Sammanfattning : It is increasingly recognized that individuals of the same species differ from each other and influence and respond to their environment in unique ways. This thesis deals with size variation among individuals that not only are of the same species but also of similar age. LÄS MER

  7. 5. Climate change impacts on aquatic consumer communities

    Författare :Shuntaro Koizumi; Pär Byström; Ryan Sponseller; Jonathan Shurin; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Climate change; warming; browning; aquatic consumers; zooplankton; benthic insects; fish; ecosystem experiment; environmental science; miljövetenskap;

    Sammanfattning : Climate change represents a serious threat to aquatic ecosystems, with an increase in lake temperatures already observed that is expected to continue in the near future. Aside from the direct effects of warming, climate change is also partially responsible for the browning of lakes. LÄS MER