Peatlands represent a globally significant carbon stock and wildfire is the largest disturbance affecting these ecosystems. Climate change scenarios suggest that increases in evapotranspiration are likely to exceed increases in precipitation in northern latitudes, raising concern that peatlands will experience substantial drying. Drying may increase peat burn severity and, when coupled with expected increases in total wildfire area burned, may exceed peatland resilience to wildfire. While previous studies have examined both peatland vulnerability to wildfire and post-fire recovery, these studies have not examined the driest peatlands on the landscape that are likely to be the most susceptible to the combined effects of climate change and wildfire. For this reason, this thesis examined the hydrogeological and ecohydrological controls on burn severity and post-fire recovery in peatlands in the Boreal Plains of Alberta, where peatlands exist at the limit of their climate tolerance. High burn severity was prevalent at the margins of a small peatland isolated from groundwater flow, where average burn depths were five-fold greater than in the middle of the peatland. Deep burning was attributable to the effect of dynamic hydrological conditions on margin peat bulk density and moisture. Following wildfire, water availability was a key determinant of post-fire moss recovery. Both high and low burn severity can decrease post-fire water availability by altering peat hydrophysical properties. Post-fire recovery was also dependent on large-scale hydrological processes that influence peatland water tables, specifically, hydrogeological setting. Small peatlands isolated from groundwater flow systems had lower peatland moss recolonization rates at both their middles and margins due to drier conditions. This was important because the margins of these same peatlands were prone to deep burning. Therefore, deep burning is likely altering peatland margin ecohydrological function and may be facilitating a regime shift from peatland to mineral upland. / Thesis / Doctor of Philosophy (PhD)

<p> Plants can control water loss through their stomata in response to changing environmental conditions. Some research has been done on predicting stomatal resistance from climate variables such as solar radiation intensity, temperature, and vapour pressure deficit, but the factors involved are numerous and complex. Information on evapotranspiration from non-cultivated vegetation under field conditions is relatively scarce. This study was carried out in a subarctic coastal wetland on James Bay, an area for which little data exists. Leaf resistance measurements were collected in the field with a diffusion porometer as the 1988 growing season reached its peak. Meteorological data were also recorded. The main species examined was Carex aquatilis, a common sedge with a circumpolar distribution. As has been previously found, field resistances were lower than those reported for greenhouse-grown specimens. Attempts to derive a multivariate regression model to predict leaf resistances had a maximum explained variance under 40%. However, Principal Components Analysis suggested that cool, sunny, low-VPD conditions tend to accompany low leaf resistances. An increase in leaf resistance occurs when solar radiation intensities are low, or when the air is warm and dry. In addition, Carex aquatilis from drier areas showed less growth, and generally higher leaf resistances, than plants growing in saturated soils. Since climate models predict higher temperatures and lower soil moisture for the study area, due to carbon dioxide-induced warming, higher stomatal resistances could result. If these changes are severe enough, primary production could be reduced in the subarctic wetlands. Through the food chain, this could possibly affect species important to the economy and ecology of northern areas.</p> / Thesis / Candidate in Philosophy

Vernal pools are essential breeding habitat for amphibians - the vertebrates most at-risk across the globe. Unfortunately, due to their small sizes and temporary nature, vernal pools are prone to indiscriminate destruction. This is the case in southern Ontario as most vernal pools have already been destroyed by human development. As such there is an urgent need to map remaining vernal pools in relatively undeveloped forested regions, such as the District Municipality of Muskoka in South-Central Ontario. This thesis aims to head-start the creation of a community-based vernal pool mapping project using LiDAR in South-Central Ontario. This goal has been broken down into two chapters with their own sub-objectives. In one chapter, we implemented a pilot study for integrating community involvement in potential vernal pool mapping across the Muskoka River Watershed (i.e., the major watershed of the District of Muskoka). We built a protocol and survey based on past vernal pool projects and studies which effectively integrated citizen involvement and also implemented novel online components (e.g., a portal) for vernal pool field-work. Our efforts were successful with positive feedback for the online components and a majority of the potential vernal pools located by our volunteers were probable vernal pools. In the other chapter, we developed two potential vernal pool mapping protocols using LiDAR based on regional characteristics of pools across the District of Muskoka in the Muskoka River Watershed and Coastal Georgian Bay. We demonstrated that the best mapping protocol for each of the two regions were associated with the protocol that was based on their respective pool characteristics. Moreover, we determined that while LiDAR can increase the accuracy of vernal pool mapping efforts, this is not always the case, especially when mapping vernal pools that occur in expansive bedrock laden regions. / Thesis / Master of Science (MSc) / Vernal pools, small forested temporary wetlands, provide essential breeding habitat for amphibians - the most threatened vertebrate group across earth. Unfortunately, most vernal pools in southern Ontario have been destroyed by human development, and there is an urgent need to map remaining vernal pools in relatively undeveloped forested regions, such as the District Municipality of Muskoka in South-Central Ontario. We implemented a pilot study for integrating community involvement in potential vernal pool mapping and developed two potential vernal pool mapping protocols using LiDAR based on regional pool characteristics. With successful integration of volunteers and mapping accuracies above 80%, we hope our findings will aid future vernal pool conservation, especially by head-starting the creation of a community-based vernal pool mapping project using LiDAR in South-Central Ontario.

Rates of marsh wetland loss in the northern Gulf of Mexico are the highest observed in North America. Marsh terraces have been implemented over the last 30 years to address this loss. Marsh Terraces reduce fetch and resulting wave energy which, reduces rates erosion of sediments in coastal wetlands. This thesis evaluated marsh terraces by extensive data collection that will assess the spatiotemporal relationships between wind patterns, wave parameters, and sediment strength in water bodies modified with marsh terraces. Data collected during two four-month deployments captured the passage of 40 cold front storms and the passage of Hurricane Barry. Results indicated that the mean threshold for erosion for marsh platform and terraces (0.194 N/m2 and 0.500 N/m2) were often exceeded during the passage of cold front storms. Orientation to reduce the influence of these storms was determined to be 270/55 which is perpendicular to cold front associated winds.

Inception of the Clean Water Act in 1972 resulted in regulation of activities in wetlands through Section 404. Regulatory agencies like the Mississippi Department of Marine Resources (MDMR) have tried to find methods to rapidly evaluate wetlands. This study compares three rapid evaluation methods, Hydrogeomorphic Approach (HGM), Wetlands Rapid Assessment Procedure (WRAP), and Wetland Evaluation System (WES), based on their scoring of a group of reference and mitigation wetland sites. Repeatability was studied by scoring a group of sites twice. The non-parametric Spearman?s correlation was used to compare the three methods. In this study, HGM was most repeatable followed by WES and WRAP. Comparisons of overall scores using the Spearman correlation found the strongest correlation between HGM and WES, although all pairings were significantly correlated (p< 0.05). This study determined HGM was the optimum method for the MDMR because due to repeatability and producing results similar to the other two methods.

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