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 55 for “"Grazing pressure"”.
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Effect of Grazing Pressure on Cattle Grazing Cool Season Annual Forages
… understanding of specific plants selected by grazing ruminants remains elusive. Many long- and short-term factors impact cattle grazing behavior. Ultimately, grazing behavior can affect forage available for grazing, nutrient density of forage, dry matter intake, and animal performance. A …
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Going through the motions : the impacts of frequent fires and grazing pressure on reproduction of Montane grassland birds
… 2001 I examined the effect of fire frequency and grazing intensity on the density, breeding biology and nesting success of several grassland bird species that breed in the high altitude grasslands of Wakkerstroom, South Africa. I established study plots in heavily grazed and annually burned, …
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Impact of black swan grazing and anthropogenic contaminants on New Zealand seagrass meadows
… New Zealand estuaries during the last century. Grazing by the black swan (Cygnus atratus) and anthropogenic contaminants resulting from catchment development are postulated to contribute to seagrass meadow loss in New Zealand and these factors have been assessed in this study. The aim of this …
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The effect of ocean acidification on plant-animal interactions in a <i>Posidonia oceanica</i> meadow
… community dynamics, and 3) macroherbivore grazing pressure. Results suggested that <i>P. oceanica</i> and its associated community should be robust to levels of acidification projected for the end of this century. Seagrass density, invertebrate abundance, and <i>P. oceanica</i> grazing …
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Pastoral mobility in a variable and spatially constrained South African environment
… type and condition in the distribution of grazing pressure and further discussed the implications of using variable stocking rates in a spatially constrained pastoral system.
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Developing Management Guidelines that Balance Cattle and Timber Production with Ecological Interests in the Black Hills of South Dakota
… livestock and timber production. Livestock grazing of forested lands has been widespread throughout the western US since the settlement era, and currently occurs on 51.4 million hectares (ha) representing 16% of all US grazing land and 22% of all US forested land (Nickerson et al. 2011). …
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Contributions to the Proterozoic and Cambrian Evolution of Eukaryotes
… either nutrient stress or the absence of animal grazing pressure. The Ediacaran increase in surface/volume ratio and morphological complexity may have been driven by decreasing pCO₂ levels and increasing animal grazing pressure. Chapter 2 presents a systematic re-examination of the carbonaceous …
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Long-term impacts of livestock grazing in the Succulent Karoo: A 20-year study of vegetation change under different grazing regimes in Namaqualand
Livestock grazing is a key form of land-use around the world. Sustained, heavy grazing pressure, however, changes the vegetation structure of arid and semi-arid regions, often resulting in the local extinction of perennial, palatable species. It also causes changes in species composition through …
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A functional analysis of the response of the Southern Kalahari dune vegetation to land-use intensity
Natural and anthropogenic environmental variables pressures exert fitness pressures on our flora and vegetation and necessitate an understanding of the mechanisms of plant responses to those pressures. Overgrazing and desertification are examples of the stressors that affect plant community …
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Prymnesium parvum effects on green algae, cladocerans and fish in field and laboratory studies.
… relationships among environmental conditions, grazing pressure, mixotrophy and toxin production.
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Computational analysis of the biophysical controls on Southern Ocean phytoplankton ecosystem dynamics
… light, nutrients), as well as the top-down (via grazing pressure). In Chapters 3 and 4, I employ a higher resolution, eddy resolving, integration to explicitly track and examine closed eddy structures and address how they modify biomass at the mesoscale.
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Patterns of resource use by livestock during and after drought in a communal rangeland in Namaqualand
… the worst effects of natural stress and disperse grazing pressure. In the past in South Africa, the indigenous Nama people occupied large areas of land and moved around extensively to exploit seasonal differences in the availability of forage and water. With the settlement of the Europeans in the …
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Substrate dependant survivorship of Ecklonia maxima, in southern African kelp communities
… may occur through episodic recruitment escaping grazing pressure. In areas with low grazing intensity, recovery from catastrophic storms may be limited by competition with understorey algae.
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Floating seaweed as ephemeral neustonic habitat
… turn significantly influenced by temperature and grazing pressure. In favourable conditions, seaweed rafts can potentially cover great distances, carrying with them rafting fauna that are able to survive a long journey in the neuston.
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Population Dynamics and Pattern Formation in an Info-chemical Mediated Tri-trophic Plankton Model
… extended, four-species model. In the latter, the grazing pressure of microzooplankton (M) on phytoplankton (P) is controlled through external infochemical (C) mediated predation by copepods (Z). We undertake a stability analysis of both the two species model and the four species model and compare …
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Human-Managed vs. Natural Grazing Systems: Exploring Effects of Livestock and Wildlife Grazing at Multiple Scales
<p>Grazing by large herbivores is the most prevalent land use on grassland ecosystems, which cover greater than 40% of the earth's land surface and provide critical ecological and economic benefits. As such, understanding how grazing impacts different aspects of the ecosystem is of especially great …
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Assessing Respiration Rates and Nutrient Dynamics of Aritifical Reef Biofilms and Bacterioplankton in the Mississippi Sound
… abundance was limited by some factor, such as grazing pressure. P04 and NH4 production were often observed in incubation experiments, and production rates were higher in the presence of biofilm, indicating that the benthic community supplements microbial water column nutrient regeneration. …
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Changes in benthic marine macrophyte community structure in the Strait of Georgia: long-term and grazing responses
… 2) At Bath Island, a period of intensive grazing by sea urchins, Strongy locentrotus droebachiensis, during 1973 altered the community structure and provided an opportunity for a comparative study of macrophyte community change and regeneration at the two sites. 3) Community structure at …
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