Search for dissertations about: "species richness"
Showing result 21 - 25 of 169 swedish dissertations containing the words species richness.
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21. Butterfly Diversity and Dispersal in Fragmented Grasslands
Abstract : 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. READ MORE
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22. Diversity Underfoot : Systematics and Biogeography of the Dictyostelid Social Amoebae
Abstract : 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. READ MORE
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23. Biodiversity in Agricultural Landscapes: Landscape and Scale-Dependent Effects of Organic Farming
Abstract : 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. READ MORE
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24. Biological Diversity of Fish and Bacteria in Space and Time
Abstract : 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. READ MORE
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25. Semi-natural meadows in southern Sweden - changes over time and the relationship between nitrogen supply and management
Abstract : 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. READ MORE