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Phragmites australis (Cav.) Trin. ex Steud., the invasive common reed, is a perennial grass with a cosmopolitan distribution. Unlike the native subspecies (Phragmites australis subsp. americanus) in North America, this invasive haplotype is an aggressive competitor and has firmly established itself throughout the Great Lakes basin by dominating wetlands and wet habitat, forcing out native plants and creating monocultures of little use to native fauna. Growing clonally and from seed, invasive Phragmites can quickly dominate wet areas throughout North America. It has also become a prominent feature in roadside habitats, where native plants are subject to increased disturbance under which invasive Phragmites will thrive competitively. In order to effectively manage this aggressive invader, we must be able to accurately map its distribution at multiple spatial scales, understand its invasion ecology, and determine efficacy of current removal efforts. In this thesis, I evaluated multiple remote sensing methods to determine the extent of invasive Phragmites. The basin-wide wetland mapping project based on satellite image data was a collaborative effort between U.S. and Canadian scientists to document the current and potential distribution of invasive Phragmites throughout 10-km of the shoreline of the Great Lakes, including all coastal marshes. To elucidate its distribution through road networks, I used provincial orthophotography databases to map changes in the distribution of Phragmites in road corridors between 2006 and 2010. Based on these data, I created a conceptual model to show the relationships among the main factors that govern the establishment of invasive Phragmites in roadsides within Ontario. These factors included habitat quality, habitat availability, and propagule dispersal. I also showed how unmanned aerial vehicles can be used with very high accuracy to map the distribution of very small stands of Phragmites at the beginning of an invasion, and to determine short-term changes in habitat availability in smaller wetlands. Using various remote sensing approaches, I was able to determine the efficacy of treatment programs implemented by provincial agencies on roadway corridors at the scale of the entire southwestern, southcentral and central regions of Ontario. This is the first quantitative evidence of invasive Phragmites removal along roads and one of the largest spatial and temporal time scales used to evaluate these processes. Finally, I synthesized the capabilities and limitations of these remote sensing methods to create an evaluative framework that outlines how to best map invasive Phragmites across varying landscapes. This research integrates geography and biology to create novel mapping techniques for invasive Phragmites and has furthered our understanding of this aggressive plant and how its invasion can be controlled. / Thesis / Doctor of Philosophy (PhD) / Invasive common reed, Phragmites australis subsp. australis, is one of the most aggressive and problematic invasive species in North America. This species rapidly expanded in the late 1900s and now occupies large patches of our critical wetland habitats as monocultures, especially in the northeastern states and the Great Lakes basin. My thesis presents new methods to identify where invasive common reed is present at a landscape level so that it can be targeted for large-scale control and removal. With colleagues in Michigan we created the first basin-wide map of invasive common reed for the Great Lakes region using satellite image data. Within Ontario, I used imagery from satellites and planes to determine the extent of invasive common reed along our road networks. At a site-specific scale, I used drones or unmanned aerial vehicles to map a protected wetland with high precision and accuracy. I used many of these approaches in combination to determine how effective current invasive common reed removal efforts are along roadway corridors. I compare all of these mapping processes and techniques to showcase the strengths and weaknesses of each approach and to help managers decide which approach is most suitable for their unique case. With all of these data, I have created new mapping techniques that can show the rapid spread of invasive common reed and how effective current management plans have been in combatting this aggressive invader.

The eastern massasauga rattlesnake, or massasauga, is threatened in Ontario. Massasaugas overwinter in habitat that is sufficiently moist, above the water table, and below the zero-degree isotherm in a physical space conceptualized as a resilience zone. A development project in the Eastern Georgian Bay subpopulation of massasaugas overwintering habitat necessitated restoration. The Toronto Zoo hibernacula design was deemed inappropriate for use in this bedrock dominated landscape, as the limited deep groundwater percolation would result in flooding of the habitat from the fall to spring. Massasaugas in EGB, overwinter above the water table in Sphagnum peat hummocks. The ecohydrological factors of these hummocks in confirmed massasauga habitat were evaluated in a mixed effect linear model. It was found that taller hummocks, taller shrubs, and less WT variability were the best predictor of suitable conditions. This information was combined into a restoration method that moves surficial peat material from a soon to be impacted wetlands to an adjacent depression with mean depths of 40-80 cm, with mean bottom substrates 15-30 cm, and varying proportions of open water and floating peat with different vegetation communities. This design limits water table variability and allows for the growth of tall shrubs. Unforeseen circumstances meant that peat to be used in the project had to be stockpiled, which increased peat bulk density and limited photosynthesis. Despite this, restored habitat had similar mean lengths of unsuitable conditions compared to confirmed massasauga wetland habitat. The physical size of available overwintering habitat, as well as the total duration of unsuitable conditions, was not significantly different between restored wetlands, unconfirmed wetlands, and confirmed wetlands. Amendments to increase the cover of live Sphagnum moss will likely increase the duration and size of suitable conditions in the restored wetlands. Based on this success with degraded materials this new method of restoration design shows great promise in this region. / Thesis / Master of Science (MSc)

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In order to improve our understanding of present and future coastal environmental change, we look into the past using sediment that accumulates in coastal environments. We have done this for two disparate systems: a back-barrier lagoon in southwestern Japan, and freshwater tidal marshes along the Hudson River, New York, USA. In Japan, we used a 2,500-year sediment record to investigate coastal flood risk from tsunamis and typhoons. This is a critical area of study to better understand the spatial and temporal variability of these hazards in Japan. In the Hudson River we looked at modern (since 1800) deposition of sediment in anthropogenically constructed embayments that have formed tidal wetlands in the last few centuries. A better understanding of the factors that have attributed to these successful tidal marsh systems in the past can help inform future management decisions in the face of future sea level rise. Studying the history of coastal systems using the sediment record is a valuable tool for assessing hazard risk and habitat loss in the present and future.

Soil nutrients are often heterogeneously distributed in space and time at scales relevant to individual plants, and plants can respond by selectively proliferating their roots within nutrient-rich patches. However, many environmental factors may increase or decrease the degree of root proliferation by plants. I explored how soil fertility, nitrogen (N) or phosphorus (P) limitation, and soil oxygen availability affected root system response to nutrient heterogeneity in forested wetland ecosystems of southeastern United States. Fine root biomass was not correlated with soil nutrient availability within wetland ecosystems, but was related to ecosystem-scale fertility. Root systems generally did not respond to P-rich patches in both floodplain (nutrient-rich) and depressional swamps (nutrient-poor) swamps, but results were inconclusive because the growth medium (sand) potentially hindered root growth. In floodplain forests, roots proliferated into N-rich patches but not P-rich patches, even though litterfall N:P ratios were > 15, which suggested that these ecosystems were P-limited. The combination of nutrient and oxygen heterogeneity affected root proliferation and biomass growth of three common floodplain forest species (Liquidambar styraciflua, Fraxinus pennsylvanica, and Nyssa aquatica) in a potted study, which was related to species' flood tolerance. My results suggest that the environmental context of plants can affect roots system response to nutrient heterogeneity in forested wetland ecosystems and highlights the need for field studies that investigate this phenomenon. Learning how environmental conditions affect plant response to nutrient heterogeneity at a fine-scale will provide better predictions of nutrient cycling, plant competition and succession, and forest productivity, which are important factors that determine carbon sequestration and timber production. / Ph. D.

Establishing wetland gains and losses, delineating wetland boundaries, and determining their vegetative composition are major challenges that can be improved through remote sensing studies. In this study, we used the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) to separate wetlands from uplands in a study of 870 locations on the Virginia Coastal Plain. We used the first five bands from each of two ASTER scenes (6 March 2005 and 16 October 2005), covering the visible to the short-wave infrared region (0.52-2.185υm). We included GIS data layers for soil survey, topography, and presence or absence of water in a logistic regression model that predicted the location of over 78% of the wetlands. While this was slightly less accurate (78% vs. 86%) than current National Wetland Inventory (NWI) aerial photo interpretation procedures of locating wetlands, satellite imagery analysis holds great promise for speeding wetland mapping, lowering costs, and improving update frequency. To estimate wetland vegetation composition classs of the study locations, we generated a Classification and Regression Tree (CART) model and a Multinomial Logistic Regression (logit) model, and compared their accuracy in separating woody wetlands, emergent wetlands and open water. The overall accuracy of the CART model was 73.3%, while the overall accuracy of the logit model was 76.7%. Although the CART producer's accuracy (correct category classification) of the emergent wetlands was higher than the accuracy from the multinomial logit (57.1% vs. 40.7%), we obtained the opposite result for the woody wetland category (68.7% vs. 52.6%). A McNemar test between the two models and NWI maps showed that their accuracies were not statistically different. We conducted a sub-pixel analysis of the ASTER images to establish canopy cover of forested wetlands. The canopy cover ranged from 0 to 225 m2. We used visble-near-infrared ASTER bands, Delta Normalized Difference Vegetation Index, and a Tasselled Cap transformation in an ordinary linear regression (OLS) model. The model achieved an adjusted-R2 of 0.69 and an RMSE of 2.73% when the canopy cover is less than 16%. For higher canopy cover values, the adjusted-R2 was 0.4 and the RMSE was19.79%. Taken together, these findings suggest that satellite remote sensing, in concert with other spatial data, has strong potential for mapping both wetland presence and type. / Ph. D.

Plans to construct a wetland to replace wetland losses has become a common feature of permit requests. The purpose of this project is to suggest a methodology for quantifying the effectiveness of palustrine forested wetland construction in Virginia. Wetlands constructed by ~ne Virginia Department of Transportation and the U.S. Army Corps of Engineers were surveyed and Wagner Road constructed wetland in Petersburg, Virginia was selected as the primary study site. Chapter One of the present study suggests a method for early assessment of revegetation success utilizing weighted averages of colonizing vegetation. An adjacent reference site was chosen that was in close proximity to the constructed site and was used for comparison. Results from the Wagner Road site and the reference wetland indicated that colonizing vegetation weighted averages provide a more sensitive measure of revegetation success than the methods described in the federal wetland delineation manual. / Ph. D.

In 1985, 24 bottom samples were collected in each of two slightly brackish,semi-permanent prairie wetlands (P1 and P4) with different hydroperiods. The main objective was to determine if hydroperiod affected seed pool characteristics. Additionally, 48 samples were collected in 1986 from wetland P1 to determine if seed bank composition changed annually without a change in mature vegetation. Seed bank composition was determined by placing soil samples in a greenhouse, then counting and identifying emerged seedlings. As a check against the seedling emergence method, seeds were separated and identified microscopically in one-third of the 1985 samples. Results indicated that the emergence method was an accurate technique for assessing seed pool composition. The wetlands did not differ in floristic composition (i.e., presence/absence) but did in species densities. The mean relative density of mudflat annuals in all seed pool samples was significantly greater in wetland P4 (82%) than in P1 (52%). A shorter hydroperiod in this wetland produces more frequent drawdowns and a greater input of mudflat annual seeds. Conversely, seeds of emergent species were more abundant in the seed bank of wetland Pl (48%) compared to P4 (17%). The former wetland has a longer hydroperiod and less frequent drawdowns, and thus, the primary seed input is from emergent plants. / Master of Science