Contains full text Manitoba-related theses dating from 1902 to the present. http://hdl.handle.net/1993/3098 2013-05-24T03:24:44Z 2013-05-24T03:24:44Z Li, Ru http://hdl.handle.net/1993/19948 2013-05-07T16:14:40Z 2012-12-19T00:00:00Z

Title: Exploring bacterial communities and their functions for soil health under different cropping systems Authors: Li, Ru Abstract: Rhizosphere and soil bacteria are important drivers in nearly all biochemical cycles in terrestrial ecosystems and participate in maintaining health and productivity of soil in agriculturally managed systems. However, the effect of agricultural management systems on bacterial communities is still poorly understood. In this study, cultural methods and advanced molecular methods (terminal restriction fragment length polymorphism (TRFLP) and 454- pyrosequencing) were used to identify shifts in soil and rhizosphere bacterial diversity, community composition, and functions under different cropping systems in Manitoba, Canada. This included monoculture vs. rotation, zero tillage vs. conventional tillage, and organic farming vs. conventional farming. Results showed that: (1) different cropping systems did not significantly influence the diversity of bacterial communities. However, a significant variation in relative abundances of bacterial communities at both the phylum and genus level was observed among different cropping systems. Compared to conventional farming systems, organic farming system had a higher percentage of the phylum Proteobacteria (many Plant Growth Promoting Rhizosbacteria) and a lower percentage of the phylum Actinobacteria. When canola monoculture was compared to wheat-oat-canola-pea rotation, a significantly higher percentage of Proteobacteria and a lower percentage of Actinobacteria were found in the rotational system. Wheat monoculture shared similar bacterial communities with wheat-oat-canola-pea rotation. Zero tillage did not change bacterial community profiles except for an increase in Firmicutes (many PGPR), compared to conventional tillage. At the genus level, significant differences were found for the dominant genera Pseudomonas, Rhizobium, Stenotrophomonas, Brevundimonas, Burkholderia, Marmoricola, Microlunatus, and Solirubrobacter. The bacterial distribution was strongly associated with soil pH. (2) The cropping systems also influenced the antibiotic-producing Pseudomonas populations determined through PCR-based screening for the detection of genes involved in the biosynthesis of antibiotics. It was found that pyrrolnitrin- and phenazine- producing Pseudomonas spp. were more prevalent in the soil under zero tillage and organic farming systems, while 2,4-DAPG and pyoluteorin-producing strains were not found in this study. This comprehensive study provided fundamental information on how different cropping systems affect soil and rhizosphere bacterial communities, which can be used to guide Manitoba farmers to choose proper farming systems to maintain soil health and increase PGPR populations in soil.

2012-12-19T00:00:00Z Bortoluzzi, Tara http://hdl.handle.net/1993/19686 2013-04-29T14:09:28Z 2013-04-29T00:00:00Z

Title: Spatial and temporal patterns in the hydrology, water chemistry and algal nutrient status of Delta Marsh, as influenced by the hydrology of adjoining Lake Manitoba. Authors: Bortoluzzi, Tara Abstract: Between 2002 and 2005, I examined spatial and temporal patterns in the hydrology, water chemistry, and algal nutrient-limitation status (N and/or P) in Delta Marsh, a 18,500-ha coastal lacustrine freshwater marsh on the south shore of Lake Manitoba, to determine the influence of surface water exchange with Lake Manitoba on these properties. Daily and annual marsh water level changes were found to be highly correlated with those of the lake, during some of the highest and lowest long-term water levels in recorded history. The average magnitude of water level changes in the marsh ranged from to a few centimeters to half a meter, which is significant in shallow coastal wetlands systems like Delta Marsh where the average depths are ≤ 1 m. In general, marsh sites located closest to the lake were influenced to the greatest degree by the flushing and dilution effect of the lake. Spatially, in connected sections of the marsh concentrations of dissolved inorganic and total N (DIN-N and TN), total reactive and total phosphorus (TRP-P and TP), dissolved organic carbon (DOC), chloride (Cl-), sulfate (SO4-), alkalinity and conductivity decreased with decreasing distance to Lake Manitoba. Regardless of east and west location and the distance of connected marsh sites from Lake Manitoba, annual variation in water level was the most significant predictor of differences in several water chemistry characteristics between sample sites including DIN-N, TN, TRP-P, TP, alkalinity, DOC, Cl-, SO4-, and conductivity. Annually, concentrations of DIN-N, TN, alkalinity, DOC, Cl-, SO4- and conductivity were negatively correlated with increasing water depth, and the spatial variation in the concentration of these water chemistry parameters also decreased with increasing water level. Results of nutrient diffusing substrata bioassay experiments indicated that periphyton biomass in the marsh was predominately limited by N. The predominance of N limitation in Delta Marsh was found to be significantly negatively correlated with water column N concentrations, but not correlated with P concentrations. Collectively, this study illustrates the important role of lake connection and hydrological influence on the structure and function of adjoining coastal freshwater wetlands.

2013-04-29T00:00:00Z Van Helden, Michael John http://hdl.handle.net/1993/19683 2013-04-25T19:39:29Z 2013-04-25T00:00:00Z

Title: Measurement and Modeling of Anisotropic Spatial Variability of Soils for Probabilistic Stability Analysis of Earth Slopes Authors: Van Helden, Michael John Abstract: Geotechnical engineering design has relied upon deterministic methods of analysis whereby values for analysis parameters and conditions are selected subjectively based on judgment with the intent of providing acceptable margins of safety. The objective of this research was to improve the use of probabilistic slope stability analysis in practice so that the design of slopes can be made on a consistent and probabilistic basis. The current research involved the development of a methodology for the measurement and modeling of the anisotropic autocorrelation distance of cohesive soils, which was demonstrated at Dyke 17 West of the McArthur Falls Generating Station. In-situ testing using the piezocone and laboratory testing was conducted to characterize the spatial variability of the effective-shear strength envelope. Vertical (down-hole) and horizontal (cross-hole) geostatistical analysis was conducted to assess the anisotropy of the semivariogram. The investigation identified that heterogeneous inclusions had significant impacts on the results, but that simplistic (visual) identification and filtering procedures were adequate. The effective-stress shear strength envelope was statistically characterized as a random field, which was simulated as a first-order Markov process using customized add-in functions in a limit-equilibrium slope stability analysis. The analysis accounts for the spatial variability of shear strength and is capable of simulating both isotropic and anisotropic autocorrelation functions. The study showed that the critical slip surface geometry and the probability of failure can be significantly different when the anisotropy of spatial correlation is accounted for. The study also showed that neglecting spatial correlation may over-estimate the probability of failure, however this finding was noted to be likely case-specific. The primary conclusion of the study was that appropriate representation of spatial correlation is essential to calculating the probability of failure. Finally, convergence of the probabilistic simulation was evaluated using bootstrapping of the simulated factor of safety distribution to assess the standard error in the mean factor of safety, standard deviation of factor of safety and the probability of failure. A convergence criterion based on the percentage standard error in the probability of failure was proposed and used to define the number of Monte-Carlo iterations required.

2013-04-25T00:00:00Z Boulanger, Josée http://hdl.handle.net/1993/19447 2013-04-23T13:53:58Z 2013-04-23T00:00:00Z

Title: Look, listen, learn: collaborative video storytelling by/with people who have been labelled with an intellectual disability Authors: Boulanger, Josée Abstract: In 2006, I began working collaboratively with People First members to use video as a means of telling experience-based stories. Although, I found little information that would help prepare me to work collaboratively with people who have been labeled with an intellectual disability. I was acquainted with participatory approaches to making video and with inclusive research methods with people with learning disabilities. After working for over two years and facing a variety of hurdles and barriers, The Freedom Tour documentary was released in DVD in 2008, and a year later, short video stories were published on the Internet as part of the Label Free Zone web-based project. After having worked intensely and with great urgency to “get these stories out,” I felt the need to pause. To reflect upon my experiences and to ask questions about the work I was doing, I chose to write stories adopting an auto-ethnographic approach. Experimenting with auto-ethnography as a method of inquiry and storytelling as a form of representation, gave me the opportunity to experience a process I had encouraged so many others to do: telling experience-based stories. I hope this study will increase our knowledge and understanding of collaborative video storytelling projects involving people who have been labelled. I also hope that by delving into and speaking from my experiences as filmmaker/facilitator, sibling and now auto-ethnographer I have contributed, if ever so slightly, to shifting our thinking about intellectual disability from a deficit perspective to an assumption of competence.

2013-04-23T00:00:00Z