Graduate Theses & Dissertations

Distribution of Cluster Fly Species (Pollenia, spp. Diptera
This thesis looks at the genus Pollenia: historically where they were first introduced into Canada and spatially, where they are found now. This project involved me identifying 2211 files, sorted from the 3 years of field specimens obtained in 2011, 2012, 2013. P. pediculata was the most abundant and widespread, yielding 1272 specimens out of 2211, and it was found in all provinces sampled. The previous understanding of all Pollenia specimens as being P. rudis appears to be incorrect both in terms of actual number of species – which is known – and how prevalent it is. P. rudis comprised only 20% of the entire collection. The least common was P. griseotomentosa, occurring as 45 of 2211, or 2%. I found new eight first provincial records: four species in Alberta (P. angustigena, P. labialis, P. rudis, P. vagabunda) , one species for Saskatchewan (P. pediculata), two for New Brunswick (P. griseotomentosa, P. labialis), and one for Nova Scotia (P. labialis). P. labialis was new to three provinces, the other species to one province each. Author Keywords: Calliphoridae, Canada, Cluster Fly, Distribution, Pollenia, Provincial Records
Dynamics and Mechanisms of Community Assembly in a Mined Carolinian Peatland
Theoretical work on community recovery, development, stability, and resistance to species invasions has outpaced experimental field research. There is also a need for better integration between ecological theory and the practice of ecological restoration. This thesis investigates the dynamics of community assembly following peat mining and subsequent restoration efforts at Canada's most southerly raised bog. It examines mechanisms underlying plant community changes and tests predictions arising from the Dynamic Environmental Filter Model (DEFM) and the Fluctuating Resource Hypothesis (FRH). Abiotic, biotic and dispersal filters were modified to test a conceptual model of assembly for Wainfleet Bog. Hydrology was manipulated at the plot scale across multiple nutrient gradients, and at the whole bog scale using peat dams. Trends in time series of hydrological variables were related to restoration actions and uncontrolled variables including precipitation, evapotranspiration and arrival of beaver. Impacts of a changing hydrology on the developing plant community were compared with those from cutting the invasive Betula pendula. Transplanting experiments were used to examine species interactions within primary and secondary successional communities. Seedlings of B. pendula and the native Betula papyrifera were planted together across a peat volumetric water content (VWC) gradient. Impacts of beaver dams were greater than those of peat dams and their relative importance was greatest during periods of drought. Cutting of B.pendula had little effect on the secondary successional plant community developing parallel to blocked drains. Phosphorus was the main limiting nutrient with optimum levels varying substantially between species. Primary colonisers formed a highly stable, novel plant community. Stability was due to direct and indirect facilitative interactions between all species. Reduction in frost heaving was the major mechanism behind this facilitation. Interactions within the secondary successional community were mostly competitive, driven by light and space availability. However, restricted dispersal rather than competition limited further species recruitment. Predictions based on the DEFM were partially correct. A splitting of this model's biotic filter into competition and facilitation components is proposed. There was little support for the FRH based on nutrient levels and VWC. B. pendula had higher germination and growth rates, tolerance to a wider range of peat VWCs and a greater resistance to deer browsing than native birch. Peat mining, combined with restoration actions and the arrival of beaver has moved much of the bog back to an earlier successional stage circa 350+ years BP. Evidence points to B. pendula being a "back-seat driver" in the ecosystem recovery process. Indirect facilitation of a native by an exotic congener, mediated through herbivory, has not been described previously. Shifts in relative contributions of facilitation, competition and dispersal limitations to community assembly may be useful process-oriented measures for gauging progress in restoration. Author Keywords: Betula pendula, community assembly, competition, facilitation, peatland, restoration
In this study, we attempt to enhance current knowledge of ecological responses to riverine alterations from waterpower by using a bottom-up food up approach. A series of extensive and intensive study components were performed across northern Ontario, Canada, where biological (nutrients, dissolved organic matter (DOM) and periphyton) and physical (water level and thermal regimes) ecological indicators were examined in regards to alterations from dams and waterpower facilities. Overall, we found that the water levels and thermal regimes deviated from their reference condition at sites below the dams, whereas the biological indicators were more resilient to river alterations. Our results suggest that the characteristics of the watershed were influential in controlling the variability of nutrients and DOM resources in rivers within the boreal watersheds of northern Ontario, as well as the for the downstream recovery patterns of the physical indicators. The recovery of the periphyton communities downstream of the dams were also predicted to be cumulatively related to the physical alterations, nutrient availability and the possible displacement of invertebrate communities. Therefore, our bottom-up food web approach was not effective for better understanding how ecological responses from waterpower cascade through aquatic food webs, and instead multiple indicators should be used for examining the ecological responses in these particular river systems. Author Keywords: dissolved organic matter, ecological indicators, river alteration, waterpower facilities
Factors Controlling Peat Chemistry and Vegetation Composition in Sudbury Peatlands after 30 Years of Emission Reductions
Peatlands are prevalent in the Sudbury, Ontario region. Compared with the well documented devastation to the terrestrial and aquatic ecosystems in this region, relatively little work has been conducted on the peatlands. The objective of this research was to assess factors controlling peat and plant chemistry, and vegetation composition in 18 peatlands in Sudbury after over 30 years of emission reductions. Peatland chemistry and the degree of humification varies considerably, but sites closer to the main smelter had more humified peat and the surface horizons were enriched in copper (Cu) and nickel (Ni). Copper and Ni concentrations in peat were significantly correlated with Cu and Ni in the plant tissue of leatherleaf, although the increased foliar metal content did not obviously impact secondary chemistry stress indicators. The pH and mineral content of peat were the strongest determining factors for species richness, diversity and community composition. The bryophyte communities appear to be acid and metal tolerant, although Sphagnum mosses are showing limited recovery. Author Keywords: anthropogenic emissions, bryophytes, community comspoition, heavy metals, peatlands, wetland vegetation
Investigation of Air Recirculation and Thermal Efficiency within a Climate Controlled Passage
Historically, entrances have been used for passage between two separate temperature environments, such as moving from inside to outside of a building. Energy loss through entrances is a cause for concern, as it has been known to increase energy consumption to replace the lost energy; and with the exchange of air masses and cold air entering the building, human discomfort may occur. In this research, thermal efficiency and air circulation within a Conventional Entrance (CE) and Climate Controlled Passage (CCP) are compared. A small scale model of the CE and CCP was constructed to examine forty-eight energy exchange conditions, emulating those found through an entrance between a temperature controlled lab and the model. Instruments such as a power meter, a flow explorer laser Doppler anemometer, and thermocouples were used to measure and compare the energy consumption, velocity vectors, and temperature energy within the entrance. Results indicate that the CCP did retain thermal energy compared to the CE. The CE developed sloped isotherm lines and air flow that enabled and maintained thermal exhaust. Conversely, the CCP developed horizontal isotherm lines and a two-layer density current to recirculate and retain thermal energy. The research demonstrates that it is possible to increase energy efficiency of entrances in many applications. Author Keywords: Air Recirculation, Building, Entrance, Oven, Thermal Energy Efficiency, Two-layer Density Current

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