Vegetation reclamation in oil-sands requires a consistent and adequate supply of seeds of native shrubs. However, annual seed production is erratic and seeds are usually short lived and insufficient for the reclamation projects. Seeds of six native shrub species including: Prunus virginiana, Prunus pensylvanica, Arctostaphylos uva-ursi, Shepherdia canadensis, Cornus sericea, and Viburnum edule were used to analyze physiological changes during storage and artificial aging processes. The shrub seeds were studied for one year during storage under eight different combinations of temperature (-20, 4, 22.5 °C), atmosphere (Air / N2) and relative humidity (RH; 7-8 % / 3-4 %). No significant differences were detected among the storage parameters after one year; however, sub-zero and N2 environments showed a potential in maintaining a higher seed vigour during storage. In the artificial aging experiment, seeds were subjected to 45 oC, 60 % RH for 5-25 d. For most shrub species, the seed viability decreased significantly after 10-15 d artificial aging and was down to 0 % after 20 d. The germination percentage declined already after 5 d; therefore, there was a delay in detecting viability loss using the tetrazolium test. Non-aged seeds and aged seeds of most collections showed significantly different seedling lengths, which indicated a negative effect of accelerated aging process on the seedling growth. The electrolyte conductivity, as well as seed dehydrin protein expression, is strongly correlated with the seed vigour, which can be used as seed quality assessment methods in seed longevity predicting. A loss of membrane integrity occurred during the accelerated seed aging processes, as indicated by an increased electrolyte conductivity that was negatively correlated with the seed viability and germination. During artificial aging process, heat stress of Prunus virginiana induced expression of dehydrins with a molecular mass of 27 kDa, which reached a detectable level after 5 d. The storage protocol developed in this study would benefit the adequate supply of viable shrub seeds for reclamation. With species-specific parameters taken into consideration, the artificial aging technique to predict seed longevity can be further expanded to other non-crop species used in reclamation of lands after oil extraction.

Biosecurity is one of the main mechanisms used to protect and mitigate the introduction of non-indigenous species. Effective biosecurity requires a knowledge and understanding of pathways and vectors along which invasion can occur. This study contributes to our knowledge and understanding of possible biosecurity risk factors in the Antarctic by identifying potential vectors for invasive species in the pathway between New Zealand and the Antarctic. The Antarctic has important indigenous terrestrial and marine, plant and animal species, all of which contribute to the food chain in Antarctica and the Southern Ocean. This study seeks to contribute some baseline data about pathways and vectors between the two regions and the implications for the biosecurity of both. An assessment of some of the risks associated with human activities within the Antarctic region, including the traffic of people and goods to and from the area, are the focus of this thesis. Current biosecurity practices with regard to personnel, shipping containers, and fresh produce are examined and where appropriate, recommendations to alleviate any detected risks are made. The results of the research indicate a significant volume of seed and plant material being unintentionally transported to Antarctica. The most striking finding was the presence of seeds in new clothes, which have previously been assumed not to be vectors. The presence of seeds in soil samples in Antarctica suggests that seeds have probably already been transported to Antarctica. Presently the climate in Scott Base seems to prevent non-indigenous species from becoming established. However, with the increases in temperature being experienced in Antarctica, this may not always be the case, therefore greater attention to biosecurity legislation and its implementation is required.

Thesis (M.S.)--Oregon State College, 1956. / Typescript. Includes bibliographical references (leaves 74-75). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, Dept. of the Geophysical Sciences, June 2000. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--Carleton University, 1992. / Also available in electronic format on the Internet.

Thesis (doctoral)--In Universitate Viadrina, 1848. / Vita. Includes bibliographical references.

Thesis (Ph.D.)--University of Missouri-Columbia, 2004. / (tm) after EM in title is for Trademark symbol. Typescript. Vita. Includes bibliographical references (leaves 120-142). Also available on the Internet.

Thesis (Ph.D.)--University of Missouri-Columbia, 2004. / (tm) after EM in title is for Trademark symbol. Typescript. Vita. Includes bibliographical references (leaves 120-142). Also available on the Internet.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.