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 28 for “"SOIL FACTORS"”.
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Can soil factors of Namibian fairy circles explain the absence of vegetation from them?
… Reserve to investigate the hypothesis that their soils show differences to the soils of the surroundings which would lead to suppressed plant growth and the absence of vegetation from the circles. Characterisation, temperature profiling and a transplantation experiments were carried out in the …
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An investigation of the influence of drought and other soil factors on the structure of a calcareous grassland.
… been given to the interaction of drought with soil heterogeneity and mineral nutrient stress. Efforts have been made to differentiate between mechanisms of drought tolerance and drought avoidance, and this has allowed some assessment of the contribution of diversity in morphology, life history …
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Soil factors and competition as determinants of fynbos plant species distributions in the South-western Cape, South Africa
… However, very few quantitative studies of the factors controlling species turnover and community boundaries exist. I used an integrated approach of broad correlation techniques and detailed field experiments, to investigate this. The study site was a landscape on the southern slopes of the …
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ΦΥΤΟΚΟΙΝΩΝΙΟΛΟΓΙΚΗ ΜΕΛΕΤΗ ΕΠΙ ΤΗΣ ΒΛΑΣΤΗΣΕΩΣ ΤΟΥ ΔΕΛΤΑ ΤΟΥ ΠΟΤΑΜΟΥ ΕΒΡΟΥ (ΑΙΝΙΣΙΟ ΔΕΛΤΑ)
… (IN TABLES), 2) THEIR DISTRIBUTION, 3) THE SOIL FACTORS WHICH INFLUENCE EVERY ONE OF THEM AND 4) THE CHOROLOGICAL AND THE BIOTIC SPECTRA. IT WAS CONCLUDED THAT THE PLANT COMMUNITIES ARE STRONGLY CONNECTED WITH THE FOUR BASIC BIOTOPES OF THE AREA, WHICH ARE A) DRIFT LINE, B) SAND DUNES, C) …
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Marama bean (Tylosema esculentum), a non-nodulating high protein legume indigenous to the Kalahari sands : studies of its N nutrition
… perennial legume native to the nutrient-poor soils of the Kalahari Sands. In Botswana and Namibia, it is the staple food of the Khoisan people. Marama bean, however, still have not been cultivated or established as an agricultural crop in these countries. This study investigated soil factors …
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A hierarchical phytosociology of the Greater Zandvlei area
… CCA-ordination indicates that the abiotic soil factors sampled (texture composition, pH, carbon content and visible disturbance) explain very little of the variation between the communities (r²=0.002). This phytosociology is provided as a tool for future research in the area, and it is …
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Aspects relating to the spread and survival of Phellinus root rot
… be the result of differences in root contacts or soil factors. Hypovirulence caused by a dsRNA virus was also investigated as a possible cause for the inactivation of Phellinus root rot centers. A survey of several isolates of P. weirii from British Columbia and the United States failed to reveal …
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Evaluation of check dams for sediment control on disturbed land surfaces
… under a rainfall simulator. Many climactic and soil factors were measured, although the main focus was on runoff and sediment removal. The investigation revealed that all structures effectively reduced the amount of sediment lost; all except the compost sock reduced it by over 50%. Some …
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A study of the pH-dependent charge of a selection of highly weathered humic soils
Acid soils have long been associated with increased mobility of metals and the subsequent nutrient toxicity to plants, the cause of which is believed partly to be a reduction in cation exchange capacity (CEC). At the same time the reduction in CEC would result in a decline in the soil's ability to …
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Examining Land Use/Land Cover Change and Potential Causal Factors in the Context of Climate Change in Sagarmatha National Park, Nepal
… covered by ice, shrub and grass to rock and soil. Factors including political conflict due to a Maoist rebellion group, inactive park management, increasing tourist demand, and consequent natural resources exploitation helped to explain the change in the forested areas. This is supported by …
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Belowground Fungal Community Change Associated with Ecosystem Development
… and their relationships with the vegetation and soil factors, it is critical to provide insight into aboveground and belowground linkages to ultimately include this new information into ecosystem theory. I hypothesized that fungal communities would change with pedogenesis, that these changes …
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Irrigation of acacia and eucalyptus species with waters of different salinities in a semi-arid environment in Formentera, Balearic Islands
… quantities of highly saline irrigation water. Soil improvement and avoidance of detrimental long term effects was a prime objective. Two species, Eucalyptus gomphocephala D.C. and Acacia saligna (Labill.)H.Wendl. were tested with four irrigation treatments. Irrigation volume and frequency were …
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Modeling pre-harvest aflatoxin incidence in groundnut (arachis hypogaea l.) using selected soil properties and ambient temperature
… during crop growth is associated with adverse soil factors and weather conditions. Therefore, good agricultural practices are an important strategy to minimize the pre-harvest aflatoxin contamination risk in groundnut. The main objective of this study was to formulate regression models to …
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Modeling pre-harvest aflatoxin incidence in groundnut (arachis hypogaea l.) using selected soil properties and ambient temperature
… during crop growth is associated with adverse soil factors and weather conditions. Therefore, good agricultural practices are an important strategy to minimize the pre-harvest aflatoxin contamination risk in groundnut. The main objective of this study was to formulate regression models to …
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Effects of soil pH and soil water potential on arbuscular-mycorrhizal fungal colonization of soybean
… in the growth medium. The effect of extreme soil pH and moisture conditions on AM fungal development and plant-growth enhancement has been well documented independently. However, the soil factors that influence the survival and success of fungi may not act independently. We have conducted a …
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The ecology and nitrogen-fixing ability of selected Aspalathus spp. in fynbos ecosystems
… nutrients trapped in the vegetation back to the soil. However, nitrogen is lost via volatilisation during fires and as deposition of nitrogen in precipitation is low, symbiotic and non-symbiotic nitrogen-fixation may be of importance in replacing lost nitrogen. The influence of soil total …
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Influence of site factors and vascular conductivity on the development of procerum root disease
… associated with trees growing in poorly drained soils in low lying areas. Two studies were undertaken to explore the relationship of site factors and vascular conductivity of sapwood to the expression ofPRD symptoms in P. strobus. In the first study, plots were established in a variety of …
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Tolerance of selected crops to gypsiferous water originating in coal mines
… by the growth rate, temporal, environmental and soil factors. Sensitivity of crops and growth stages is therefore related to its sensitivity to the external osmotic potential, whereas tolerance both in the seedling and vegetative growth stages was found in crops primarily affected by the ionic …
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Effects of nutrient limitation on understory communities in a tropical forest
… peak in mid-elevation tropical forests. Soil nutrient limitation is an important factor influencing plant communities and yet little is known about the factors influencing fern floristic composition and functional traits in montane tropical forests. My dissertation compares composition …
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