Sökning: "species richness"

Visar resultat 21 - 25 av 172 avhandlingar innehållade orden species richness.

1. 21. Butterfly Diversity and Dispersal in Fragmented Grasslands

   Författare :Erik Öckinger; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Naturvetenskap; Djurekologi; Animal ecology; Ekologi; Ecology; Lepidoptera; Landscape ecology; Insects; Species richness; Fragmentation; Mobility; Natural science; Source-sink dynamics; Metapopulations;

   Sammanfattning : During the last decades, the distribution and abundance of many European species of birds, plants and insects in agricultural landscapes have declined due to agricultural intensification. To be able to mitigate these declines, it is essential to know the relative importance on local and regional ecological processes on population persistence and patterns of species richness. LÄS MER

3. 22. Diversity Underfoot : Systematics and Biogeography of the Dictyostelid Social Amoebae

   Författare :Allison L Perrigo; Sandra Baldauf; Maria Romeralo; David Bass; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Amoeba; biogeography; cryptic species; dictyostelid; latitudinal gradient; multicellularity; protist; social amoeba; phylogenetics; systematics; new species; Biology with specialization in Systematics; Biologi med inriktning mot systematik;

   Sammanfattning : Dictyostelids (Amoebozoa) are a group of social amoebae consisting of approximately 150 species, which are found in terrestrial habitats worldwide. They are divided into eight major clades based on molecular phylogeny, and within these clades are many species complexes. LÄS MER

4. 23. Biodiversity in Agricultural Landscapes: Landscape and Scale-Dependent Effects of Organic Farming

   Författare :Maj Rundlöf; Biodiversitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Djurekologi; Natural science; Naturvetenskap; Ekologi; Animal ecology; plants; spatial scales; species richness; Ecology; landscape ecology; agri-environment schemes; farming practice; conservation; butterflies; bumble bees;

   Sammanfattning : Declines in the distribution and abundance of many farmland species during recent decades have been attributed to agricultural intensification. Agri-environment schemes are commonly used in Europe to reduce this loss of farmland biodiversity, but their effectiveness may depend on several external factors. LÄS MER

5. 24. Biological Diversity of Fish and Bacteria in Space and Time

   Författare :Henrik Ragnarsson; Peter Eklöv; Kerstin Holmgren; Göran Englund; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; species richness; fish; lake; biogeography; glacial; colonization; metacommunity; speciation; perch; bacteria; diversity; Ekologi;

   Sammanfattning : Biological diversity is controlled by an array of factors and processes all active at different spatial and temporal scales. Regional factors control what species are available to occur locally, whereas the local factors determine what species are actually capable of colonizing the locality. LÄS MER

7. 25. Semi-natural meadows in southern Sweden - changes over time and the relationship between nitrogen supply and management

   Författare :Gudrun A I Berlin; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Plant community dynamic; Nitrogen; Mowing; Meadows; Management; Long-term study; Landscape changes; Field experiment; Community diversity; Fertilisation; Species changes; Species turnover; Plant ecology; Växtekologi;

   Sammanfattning : In this thesis, I have studied continuously managed semi-natural meadows in south-central Sweden. The purpose was 1) to make a survey of meadow vegetation in the region 2) to compare two investigations of the vegetation, one from 1963-1966 and one from 1990 3) to investigate experimentally in the field how increased nitrogen supply rate as well as changed management intensity effects the nitrogen economy and species richness in two meadow communities. LÄS MER