Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 632 for “"grassland"”.
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Biogeography and phylogenetics of grassland auchenorrhyncha
Grasslands cover a significant portion of the Earth’s terrestrial surface, yet we know little about the historical biogeography of grassland-restricted lineages. Previous work on the biogeography of grassland taxa has largely focused on large mammals. While these studies have generated some general …
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Modeling grassland productivity through remote sensing products
Mixed grasslands in south Canada serve a variety of economic, environmental and ecological purposes. Numerical modeling has become a major method used to identify potential grassland ecosystem responses to environment changes and human activities. In recent years, the focus has been on process …
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Ants and spiders in grassland food webs
Eine Herauforderung ökologischer Forschung ist das Verständnis des Zusammenhangs von Nahrungsnetzinteraktionen und Ökosystemfunktionen. Aktuelle Studien weisen dem Fraßdruck durch invertebrate Räuber und den damit ausgelösten trophischen Kaskaden eine wichtige Rolle in terrestrischen Ökosystemen …
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South African grassland ecology and its restoration
… how human related disturbances affect mesic grasslands. I identified what was lost from the system after a disturbance and what biological constraints ecologists and managers will face when approaching their restoration. I then investigated biological limitations to grassland restoration by …
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On the assembly of a grassland plant community
… possible species combinations. The assembly of a grassland plant community from the local species pool was examined in a phylogenetically corrected trait-based study. Competition theory suggests coexisting species should be less similar than expected by chance, whilst environmental sorting theory …
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Upland grassland agri-environment impacts on invertebrate biodiversity
… to enhance invertebrate biodiversity in upland grasslands.<br/><br/>Upland grassland swards were floristically poor, and were dominated by perennial ryegrass.<br/><br/>Agri-environment scheme management increased ground-dwelling invertebrate abundance and richness. Soil microarthropod total …
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Development of grassland modelling techniques with weather forecasts
This thesis investigates different aspects of weather, grass growth and statistical modelling. First, the accuracy of weather forecasts is assessed and improved using bias correction methods at twenty-five Irish locations for weather variables that influence grass growth. For the first time, soil …
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Development of mechanistic energy balance models for grassland
Grasslands are responsible for a significant percentage of the world's food supplies and, due to their large geographical extent, have an important influence on global climate. Major determinants of grassland productivity include near-surface soil and air temperatures and plant water use. Therefore …
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Grassland bird associations in a managed agricultural matrix
<p>Continued declines of grassland bird populations in the U.S. are largely attributed to grassland loss from conversion to agriculture. Habitat establishment efforts by the U.S. Department of Agriculture (USDA) may stem these declines given adequate ecological insight to guide management …
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Landscape Fragmentation and Grassland Patch Size Effects on Non-game Grassland Birds in Xeric Mixed-grass Prairies of Western South Dakota
Grassland bird populations have been declining throughout North America since the 1960’s. These declines have been attributed to landscape fragmentation, loss of grassland habitats, and the size and isolation of remaining grasslands. The purpose of this study was to inventory non-game birds on …
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Pattern and process at a desert grassland-shrubland ecotone
… shrub encroachment has occurred in desert grasslands all over the American Southwest. In the Northern Chihuahuan desert, most encroachment was due to creosotebush (Larrea tridentata [Sessé & Moc. ex DC.] Coville) expanding into black grama (Bouteloua eriopoda [Torr.] Torr.) dominated …
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Ecological studies of isopoda and diplopoda in dune grassland
… in the processes of energy transfer in a dune grassland ecosystem. The-species worked on were Armadillidiun vulgare, Porcellio scaber, Philoscia muscorum (Isopoda) and Cylindroiulus latestriatus (Diplopoda). Population data were available for the species from 1968 to 1975. Preliminary …
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Measuring grassland response to management using optical remote sensing
Grassland ecosystems cover a large portion of the Earth surface and have similar economic and ecological values as croplands and forest ecosystems. To sustainably provide ecosystem services through grasslands, grassland management bridges the connection between the provision of grassland services …
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Nesting Ecology of Grassland Birds in an Agricultural Landscape
… is an appropriate landscape context for grassland reserves. I found agricultural edges do not influence nest predation, reserves in agricultural settings support successful nesting throughout breeding seasons, and cropland is an important foraging habitat for birds provisioning nestlings …
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The effects of different burning regimes on grassland phytodiversity
The southern African grassland biome has a diverse flora including many rare and endangered species deserving a high conservation priority. With less than two percent currently conserved, proper management of this biome is crucial to maintaining its diversity. Fire, in particular, is important and …
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