Thesis (M.S.)--University of Oregon, 2001. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 89-94). Also available for download via the World Wide Web; free to UO users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p1405201.

<p> Bur oak (Quercus macrocarpa Michx.) savannas of the Great Plains have long been reported to be disappearing and/or progressing to other vegetative schemes. These losses are directly relatable to the arrival of European settlers and their subsequent suppression in natural prairie fires, along with the introduction of domestic livestock. A preliminary investigation of the floristic composition within remaining oak savannas of Custer County, Nebraska was conducted as a base means of documenting plant diversity within the remaining savannas of central Nebraska. The point-centered quarter method was used to determine species, density, relative density, frequency, relative frequency, dominance, relative dominance, and importance values (IV). The Swedish-increment boring method was applied to woody vegetation to document tree ages and compositional change in the savanna over time. Exclusion cages on oak seedlings, vegetative and soil sampling were also utilized. Results indicated a bleak future for the remaining savannas of Nebraska. Bur oak averaged an importance value of 159.10 out of 300.00, leaving a substantial portion of the importance values divided among several fire-sensitive species. The majority of bur oaks sampled were distributed among the higher size classes, indicating a low rate of recruitment. Age class distributions further support this conclusion with a minuscule number of oaks younger than 25 years of age and the majority of the species recorded over 100 years of age. Seedling survivability tests during summer months produced low survivorship (3.13%) due to drought and large/small mammal herbivory. Winter testing displayed similar results. Vegetation sampling indicated high percentages of exposed till and weedy plant species, indicating a long history of abuse. Soil tests resulted in significant differences in phosphorus and zinc concentrations. As oak recruitment failings continue on a near global scale, more research should be conducted to assist in the conservation and management of these vital ecosystems.</p>

Thèse (M.Env.)--Université de Sherbrooke (Canada), 2006. / Titre de l'écran-titre (visionné le 6 mai 2008). In ProQuest dissertations and theses. Publié aussi en version papier.

The topic of my diploma thesis is Bioproducts and their position in the present retailing. The thesis is divided in two parts, a theoretical one and a practical one. The theoretical part deals with the theory of bioproducts and their market position. It analyses ecology-agriculture tasks in Czech Republic as well as the legislation in the Czech Republic. The practical part describes bioproducts in Interspar and its own brand SPAR Natur*pur. In Interspar I did my research using questionnaires that were filled in by costumers of Interspar. These costumers answered questions about bioproducts and their market position in the Czech Republic. The results are presented in graphs and with a comment.

<p>The recent research focus on integrated multi-trophic aquaculture (IMTA) is redefining the aquaculture industry's approach to intensive aquaculture. More sustainable farm model systems that include multiple farm products with integrated trophic levels are being developed. While these systems may be economically and environmentally more sustainable, it is important to realize that integrating farm products also changes disease risk on farms. This is illustrated by examining how finfish disease risk can increase or decrease depending on the pathogen in a simple finfish / blue mussel (<i>Mytilus edulis</i>) IMTA system. Mussels bio-accumulate and repackage the opportunistic pathogen, <i>Vibrio anguillarum,</i> into infectious fecal particles increasing the potential risk of infection and creating new transmission pathways. In contrast, mussels appear to inactivate the viral pathogen, Infectious Salmon Anemia Virus (ISAV) and potentially serving a role in reducing the transmission of the virus onto and off of IMTA farms. </p><p> To understand disease risk on IMTA farms, it is no longer adequate to simply investigate how a given pathogen interacts with its host under a range of environmental conditions. Evaluating the disease risk in IMTA systems requires a better understanding of how pathogens may potentially interact with all of the components of the farm system, while recognizing new potential pathways that may be created or enhanced within and by the system its self. Through a more comprehensive understanding of these potential interactions farmers can apply a range of bio-security and best management practices to limit the risk of disease on IMTA farms. With good management IMTA farms should not increase the risk of disease, but may actually reduce the spread of pathogens in some situations. </p>

<p> This study assessed the occurrence and impacts of maternal metal transfer in live-bearing fish. The occurrence was investigated in two different species (<i>Gambusia affinis</i>and <i>Heterandria formosa</i>), while the impacts were studied only in <i>G. affinis.</i> Occurrence and impacts were addressed by exposing gravid females for 10 days to 0.15 &mu;M of copper or cadmium, transferring the fish to clean water, monitoring their reproduction and collecting newborn offspring for further analyses of their health and reproductive success. </p><p> Maternal transfer of copper and cadmium occured in both study species. Metal levels decreased in subsequent broods and in broods born later after a female's exposure. Metal exposure impacted the reproductive success of exposed-females; effects included smaller broods and more broods were aborted broods or contained dead offspring. Many effects remained for second broods developing well after the exposure. </p><p> The maternal metal exposure also impacted the offspring's health. Newborn offspring were smaller at birth, had reduced calcium levels, had a lowered metal tolerance, and had cellular membrane damage. When these offspring grew up, they had an increased rate of malformations, a smaller size at sexual maturity, increased gestation time and fewer broods. In spite of the impacts on life history parameters found in the laboratory, effects on population dynamics were very limited for greenhouse mesocosm populations established with the offspring of exposed females. </p><p> Effects for the essential metal (copper) and the nonessential metal (cadmium) were generally similar. A few effects, like those on body size, were evident for copper but not for cadmium. However, several of the more severe impacts, like the increase in malformations and reductions in the number of broods, were greatest for the offspring of the cadmium-exposed females. </p><p> This is the first report demonstrating negative impacts resulting from a short-term maternal metal exposure in live-bearing fishes. Effects were evident not just for reproduction of exposed-females but also for their offspring's health and reproduction. The latter continued beyond the offspring that were developing during exposure. This study demonstrated that the internal development in live-bearing fish may not spare the developing young from impacts caused by a metal-contaminated environment.</p>

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves [228]-244). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves [228]-244). Also available on the Internet.

Thesis (doctoral)--Universität, Zürich, 1998/99. / Includes bibliographical references.

The aim of this study is to evaluate the local climate in the selected area and assess its impact. Monitoring will be situated in South Bohemia in Nové Hrady on an organic farm called Farm Besednice Ltd. This company is mainly focused on agricultural activities. The main interest is cattle breeding and cultivation of permanent grassland, i.e. production of hay and silage for farm´s own breeding and hay for export. Beside that a cultivation of fruit trees is other interest of this farm. There are many aspects that affect the economy. Therefore we are finding what agricultural activity favors and what does not, both in terms of weather, as well as in the practical side of farm´s own experiences