Sökning: "Rare species"

Visar resultat 1 - 5 av 105 avhandlingar innehållade orden Rare species.

  1. 1. Disentangling Lecania

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Rikke Reese Næsborg; Uppsala universitet.; [2007]
    Nyckelord :Biology; Crustose lichens; Phylogeny; Taxonomy; Morphology; New species; Phylogenetic diversity; Rare species; ITS; mt-SSU; RPB2; IGS; Biologi; Lecania; Ramalinaceae;

    Sammanfattning : This thesis focuses on phylogenetic, taxonomic, ecological, and conservation aspects of the crustose lichen genus Lecania (Ramalinaceae, lichenized Ascomycota). Lecania has previously been defined on basis of relatively few morphological characters, and the genus had never been treated in molecular phylogenies. LÄS MER

  2. 2. Interaction strength and keystone species in model food webs

    Detta är en avhandling från Linköping : Linköpings universitet

    Författare :Maria Christianou; Linköpings universitet.; Linköpings universitet.; [2003]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; interaction strength; keystone species; keystone links; permanence; resilience; local stability; Lotka-Volterra models; species loss;

    Sammanfattning : Ecological communities are often exposed to different kind of disturbances of varied magnitude. The response to disturbances can be affected by, among other factors, the strength of interactions between species within the community. LÄS MER

  3. 3. Effects of climate change on boreal wetland and riparian vegetation

    Detta är en avhandling från Institutionen för ekologi, miljö och geovetenskap, Department of Ecology and Environmental Sciences

    Författare :Lotta Ström; Umeå universitet.; [2011]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; biomass; flooding; hydrologic niche; invasibility; riparian zone; riparian plant species; river margin; climate scenario; seed sowing experiment; species composition; species richness; transplant experiment; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology Terrestrial ecology; NATURVETENSKAP Biologi Terrestrisk; limnisk och marin ekologi Terrestrisk ekologi;

    Sammanfattning : Models of climate change predict that temperature will increase during the 21th century and the largest warming will take place at high northern latitudes. In addition to warming, predictions for northern Europe include increased annual precipitation and a higher proportion of the precipitation during winter falling as rain instead of snow. LÄS MER

  4. 4. VUV Emission and Energy Transfer Phenomena in Rare Gas Mixture Discharges

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Andrei Morozov; Uppsala universitet.; [2002]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; VUV spectra; excimers; energy transfer; rare gas discharges; Fysik; NATURAL SCIENCES Physics; NATURVETENSKAP Fysik; fysik; Physics;

    Sammanfattning : VUV emission spectra of Xe-X (X = He, Ne, Ar and Kr) and of Kr-Y (Y = He, Ne and Ar) mixtures with low concentrations of the heavier gases (0.1 - 1 %) and moderate total pressures (50 - 200 hPa) are recorded near each of the two resonance lines of Xe and Kr in DC glow capillary discharges. LÄS MER

  5. 5. Functional Extinctions of Species in Ecological Networks

    Detta är en avhandling från Linköping : Linköping University Electronic Press

    Författare :Torbjörn Säterberg; Linköpings universitet.; Linköpings universitet.; [2016]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Functional extinctions; Extinctions; Fisheries management; Ecologically Effective Population sizes;

    Sammanfattning : Current rates of extinctions are estimated to be around 1000 times higher than background rates that would occur without anthropogenic impacts. These extinction rates refer to the traditional view of extinctions, i.e. numerical extinctions. LÄS MER