Global warming and extreme weather events have impacted the ability of Earth’s forest ecosystems to sequester atmospheric carbon dioxide. The full effects of these events on forest productivity, vulnerability, and the carbon cycle have not yet been fully assessed. One potentially fruitful approach is to explore past climate and forest growth patterns through tree ring records. These records may be used to explore how past environmental events may have impacted tree growth and provide insight into the functioning of forest ecosystems in the future. The stable isotope ratios (e.g. 13C to 12C) of tree ring material also provide additional information about tree growth trajectories and environmental stressors that may not be recognized in radial growth. In this study, tree ring and stable isotope records were measured and constructed to explore the dynamics of growth over the lifespan of plantation pine stands in southern Ontario. Tree ring growth records were used to determine the effects of climate and other environmental changes on radial growth. These records were constructed from two white pine (Pinus strobus L.) plantations established in 1939 (TP39) and 1974 (TP74) and one red pine plantation established in 1931 (TP31). Air temperature, precipitation, and drought indices were analyzed at monthly combinations to determine controls on growth. Temperature was consistently negatively correlated to growth, while precipitation and Palmer Drought Severity Index (PDSI) were consistently positively correlated to growth. The effectiveness of each climate variable to control ring growth differed between sites which may be related to stand age, stand density, and management factors. In both white pine plantations, inter-annual eddy-flux quantifications of gross ecosystem productivity (GEP) was found to be significantly related to tree ring growth over the overlapping period from 2003 to 2017. These relationships enabled an inter-annual estimate of GEP to be constructed for both growth chronologies over the period 1942 to 2017 for TP39 and 1981 to 2017 for TP74). Additionally, growth rings from three specimens in two different-age (14- and 77-year old) white pine plantation forests were analyzed for stable carbon isotope ratios to identify both short- and long-term variations in the physiological response to changing environmental conditions. Variations in δ13C time series from whole wood samples provided a potential record of intrinsic water use efficiency (iWUE) for these three trees. These iWUE records were compared to climate records and inter-annual eddy-flux quantifications of GEP and evapotranspiration (ET). Long-term iWUE was found to increase by 50 μmol mol–1 yr–1, with nearly all of the increase occurring as the tree shifted into active homeostasis of stomatal control in the late 1960s. Changes in time series of internal and external concentration of CO2 (ratio) also displayed a significant shift from first increasing and then decreasing trend. In the three wood samples, air temperature, ET, and GEP were found to be significantly, but inconsistently related to iWUE. The work of this thesis shows that tree ring properties are strongly related to key environmental variables such as temperature and drought stress in pine plantation forests in southern Ontario, Canada. Results also suggest that dendrochronology and isotope tracers are useful tools to be used to evaluate historical environmental impacts on growth in these different-age plantation stands. The background knowledge of climate drivers acting on tree ring growth and ring isotopic compositions over the forests’ history may be used to make informed management decisions to promote tree productivity in a changing climate in Eastern North America. / Thesis / Doctor of Philosophy (PhD) / The full effect of water availability and environmental factors on forest productivity, vulnerability, and the carbon cycle has not been fully assessed. Tree ring chronologies offer one approach to explore past climate and forest growth patterns. These records may be used to identify past environmental events may have impacted tree growth and provide insight into the functioning of forest ecosystems in the future. Additionally, stable carbon isotope ratios (δ13C, or 13C to 12C) of tree ring material provide information about tree intrinsic water use efficiency (iWUE) which is not captured in radial width measurements. Lastly, inter-annual eddy-flux quantifications record stand-level dynamics of ecosystem productivity. In this study, tree ring, stable isotopes, and eddy-flux records were measured and constructed to explore the dynamics of growth over the lifespan of plantation pine stands in southern Ontario. In all three techniques, records were constructed from three white pine (Pinus strobus L.) plantations established in 1939 (TP39), 1974 (TP74) and 2002 (TP02). Air temperature, precipitation, and drought indices were analyzed at monthly resolution to determine controls on water use and productivity. Temperature was consistently negatively correlated to growth, while precipitation and PDSI were consistently positively correlated to growth. Variations in the δ13C time series from whole wood samples also provided a record of iWUE. Long-term iWUE was found to increase by 50 μmol mol–1 yr–1, with nearly all of the increase occurring as the tree shifted into active homeostasis of stomatal control in the late 1960s. In all three white pine plantations, inter-annual eddy-flux quantifications ecosystem productivity were found to be significantly related to tree ring growth over the overlapping period from 2003 to 2017. These relationships enabled an inter-annual estimate of tree ring-inferred fluxes to be constructed for all three growth chronologies. These results suggest that dendrochronology and isotope tracers are useful tools to be used to evaluate historical environmental impacts on growth in these different-age plantation stands. The interrelationships of tree ring growth, ring isotopic compositions, and eddy-flux quantifications found here serve as useful background knowledge on which to base additional studies of forest climate change impacts.

Flooding is a major concern for Canadian society as it is the costliest natural disaster type in Canada. Southern Ontario, which houses one-third of the Canadian population, is particularly affected by early spring floods following snowmelt. During the last three decades, there has been a shift in flooding events from March-April to earlier months due to earlier snowmelt coupled with extreme rain events. Hydrological models run with different scenarios of climate change suggest further enhancement of this shift in the future. These projections of streamflow are associated with a cascade of uncertainties due to the choice of Global Climate Models (GCM’s), climate change scenarios, downscaling methods or hydrological models. A large part of the uncertainty is also associated with internal variability of climate due to the chaotic nature of the climate system. Despite these uncertainties, little is known about the impact of atmospheric circulation on past streamflow in southern Ontario and how the internal variability of climate is expected to impact the overall uncertainties in the projections of the future hydrological processes. In this thesis, the Precipitation Runoff Modelling System (PRMS), a semi-distributed conceptual hydrological model, was established in four watersheds in southern Ontario to assess the impact of atmospheric circulation on the modulation of streamflow and number of high flows. Recurrent meteorological patterns (Or Weather regimes), based on 500hPa geopotential height (Z500), have been first identified in Northeastern North America using the k-means algorithm. The occurrences of these weather regimes patterns were used to create a regime-normalized hypothetical temperature and precipitation dataset that have been used as input in PRMS. Then, to investigate the future evolution of the hydrological processes, PRMS was forced with temperature and precipitation from the 50-members Canadian Regional Climate Model Large Ensemble (CRCM5-LE), a dynamically downscaled version of CanESM2-LE. The 50-members were classified into different classes of similar change in average temperature, precipitation and streamflow to identify the corresponding large-scale patterns. The specific focus of this analysis was on winter high flows, with the identification of a heavy rain and warm index, that can help to explain the generation of winter high flows in southern Ontario. The future evolution of these hydrometeorological extreme events, calculated for each member of CRCM5-LE, was analyzed with respect to the corresponding k-means weather regimes calculated for each member of CanESM2-LE. Finally, the uncertainties in the projections of the hydrometeorological extremes from the 50-members ensemble were compared to other sources of uncertainties using an analysis of variance applied to 504 simulations in the Big creek watershed. The high flows were projected using seven sets of PRMS parameters, 11 CMIP5 climate models forced with 2 scenarios of climate change and the 50 members of CRCM5-LE. The results, focusing on the winter season, showed that weather regimes High-Pressure (HP) and southerly winds (South) are associated with a higher average streamflow volume and high-flows frequency in the historical period. Regime HP is characterized by high geopotential height anomalies on top of the Great Lakes region together with higher temperature and precipitation amounts. Regime South is characterized by high Z500 anomalies in the Atlantic east coast and is associated with stronger southerly winds and higher precipitation amount in southern Ontario. The temporal increase in HP in the past contributed more than 40% of the increase in average streamflow in winter. In the future, all 50 members of CRCM5-LE ensemble produce an increase in January-February streamflow. 14% of the ensemble depict a larger streamflow increase due to increase in Z500 anomalies in the east coast. This pattern, well defined by the regimes South, is expected to become a major contributor in the generation of hydrometeorological extreme events in Southern Ontario in the future. Regime HP is expected to contribute less to the high-flows due to the disappearance of snow. Overall, the contribution of internal variability of climate to high flows will be stable through the 21st century, primarily due to an increase in rainfall as generators of high flow events. The results suggest that the regional representation of rainfall in the GCMs-RCMs chains will be a critical area to improve with great societal implications for floods. / Dissertation / Doctor of Science (PhD)

This study develops an interdisciplinary theoretical framework for understanding institutional change and resistance to change towards sustainability. The research rests on two leading theories of change within the social and ecological sciences: the New Institutionalism and Panarchy theory. A theoretical framework integrating insights from the two theories is applied in an analysis of the development of the Town of Caledon’s mineral resources policies. The research suggests that institutional change and inertia are interconnected and interdependent and, depending on the case and context, they may interact with each other across spatial and temporal scales. There may be overlap in the emergence of pressures for institutional inertia and change across temporal and spatial scales, and both institutional change and inertia may be present when opportunities arise for renegotiation of the “rules of the game”. Results show that the two theories share many concepts (e.g., thresholds or tipping points, fast and slow moving variables, etc.) to aid in understanding the dynamics of institutional and ecological realms. Moreover, the integrated theoretical framework can help to explain the dynamics of institutional systems in a way that overcomes the limitations in Panarchy and the New Institutionalism theories by themselves. Key concepts within Panarchy theory (e.g., regime shifts, etc.) complement the New Institutionalism’s ability to capture important contextual factors influencing institutional change and inertia, and help to overcome the current limitation in its capacity to explain the nonlinear, multi-scalar dynamics of institutional systems. In turn, key concepts within the New Institutionalism (e.g., uncertainty, etc.) complement and enrich Panarchy theory’s capacity to illustrate the social and economic dimensions of institutional dynamics. Results of the case analysis demonstrate that a range of overlapping, historic and immediate, local-to-provincial factors (e.g., socioeconomic costs, uncertainty, path dependent effects, etc.) and institutional elements (e.g., interests and values, power and resources, issues of fit, etc.) drove institutional change and inertia in the development of Caledon’s mineral resources policies. The slow moving institutional variables in Caledon’s case (core Town, industry and provincial government values and interests) were perhaps the greatest determinants of institutional change and resistance to change towards sustainability. The story of the development of Caledon’s mineral resources policies, then, is about the resilience and resistance efforts of a small Town committed to maintaining core community values under the constraints of a resilient and resistant, ecologically destructive and inequitable institutional system.

Since taking hold in the mid 1960s, the modern atrium has become prevalent in many designs and buildings within contemporary architecture. The modern day atrium has endured to find its place amidst our current technologies and design aspirations by continuing to offer a capacity for assisting in urban strategies, providing strong economic returns on investment, conserving or recycling existing buildings, and for its potential to reduce energy consumption. Today, as concerns for energy and the environment rise to prominence within contemporary opinion, the reliance on more integrated conservational design strategies such as what the atrium offers in the matter of material and energy conservation is more relevant than ever. Yet simply including an atrium space within a building does not guarantee its effectiveness in realizing the potential for sustainable design. By selecting to survey a collection of recently completed academic buildings in Southern Ontario, the thesis aimed to examine what current reality exists in our use of the atrium with regards to its conservational characteristics. By examining the atrium’s ability to integrate sustainable design strategies in three areas: the adaptation into existing buildings and flexible program space; the use of effective daylighting; and the provisions to manage passive air handling; the thesis identified what conservational attributes are present and how often these functions are accomplished within the atrium designs of the selected study group of buildings. Overall it was found that the current trends of conservationism in atria of the studied academic buildings are constant, that is, they do not exhibit growth proportional to the increasing awareness of ‘green’ and sustainable thinking seen in today’s culture. Furthermore, the thesis closes with a concluding critique, providing a discussion surrounding the belief that though the atrium is a possible material and energy conservational tool, much of its success can be attributed to the meticulous planning and holistic approach involved in the execution of successfully resolved atria designs.

This study develops an interdisciplinary theoretical framework for understanding institutional change and resistance to change towards sustainability. The research rests on two leading theories of change within the social and ecological sciences: the New Institutionalism and Panarchy theory. A theoretical framework integrating insights from the two theories is applied in an analysis of the development of the Town of Caledon’s mineral resources policies. The research suggests that institutional change and inertia are interconnected and interdependent and, depending on the case and context, they may interact with each other across spatial and temporal scales. There may be overlap in the emergence of pressures for institutional inertia and change across temporal and spatial scales, and both institutional change and inertia may be present when opportunities arise for renegotiation of the “rules of the game”. Results show that the two theories share many concepts (e.g., thresholds or tipping points, fast and slow moving variables, etc.) to aid in understanding the dynamics of institutional and ecological realms. Moreover, the integrated theoretical framework can help to explain the dynamics of institutional systems in a way that overcomes the limitations in Panarchy and the New Institutionalism theories by themselves. Key concepts within Panarchy theory (e.g., regime shifts, etc.) complement the New Institutionalism’s ability to capture important contextual factors influencing institutional change and inertia, and help to overcome the current limitation in its capacity to explain the nonlinear, multi-scalar dynamics of institutional systems. In turn, key concepts within the New Institutionalism (e.g., uncertainty, etc.) complement and enrich Panarchy theory’s capacity to illustrate the social and economic dimensions of institutional dynamics. Results of the case analysis demonstrate that a range of overlapping, historic and immediate, local-to-provincial factors (e.g., socioeconomic costs, uncertainty, path dependent effects, etc.) and institutional elements (e.g., interests and values, power and resources, issues of fit, etc.) drove institutional change and inertia in the development of Caledon’s mineral resources policies. The slow moving institutional variables in Caledon’s case (core Town, industry and provincial government values and interests) were perhaps the greatest determinants of institutional change and resistance to change towards sustainability. The story of the development of Caledon’s mineral resources policies, then, is about the resilience and resistance efforts of a small Town committed to maintaining core community values under the constraints of a resilient and resistant, ecologically destructive and inequitable institutional system.

This thesis is an analysis of the rural ideal as it resonates through exhibition at local county museums in southern Ontario. This study brings attention to the potential for museums to perpetuate the rural ideal through the manner in which they frame artifacts and create historical displays. Through a combination of a through historiography which features public history, museums, and rural history, this thesis argues that museums work in a similar manner as text or images to identify with an ideology. Utilizing the Wellington County Museum and Archives as a case study, exhibits of the institution are deconstructed to demonstrate their association with the ideal and the potential influence this may possess on audiences.

Since taking hold in the mid 1960s, the modern atrium has become prevalent in many designs and buildings within contemporary architecture. The modern day atrium has endured to find its place amidst our current technologies and design aspirations by continuing to offer a capacity for assisting in urban strategies, providing strong economic returns on investment, conserving or recycling existing buildings, and for its potential to reduce energy consumption. Today, as concerns for energy and the environment rise to prominence within contemporary opinion, the reliance on more integrated conservational design strategies such as what the atrium offers in the matter of material and energy conservation is more relevant than ever. Yet simply including an atrium space within a building does not guarantee its effectiveness in realizing the potential for sustainable design. By selecting to survey a collection of recently completed academic buildings in Southern Ontario, the thesis aimed to examine what current reality exists in our use of the atrium with regards to its conservational characteristics. By examining the atrium’s ability to integrate sustainable design strategies in three areas: the adaptation into existing buildings and flexible program space; the use of effective daylighting; and the provisions to manage passive air handling; the thesis identified what conservational attributes are present and how often these functions are accomplished within the atrium designs of the selected study group of buildings. Overall it was found that the current trends of conservationism in atria of the studied academic buildings are constant, that is, they do not exhibit growth proportional to the increasing awareness of ‘green’ and sustainable thinking seen in today’s culture. Furthermore, the thesis closes with a concluding critique, providing a discussion surrounding the belief that though the atrium is a possible material and energy conservational tool, much of its success can be attributed to the meticulous planning and holistic approach involved in the execution of successfully resolved atria designs.

It is generally assumed that when natural habitat is converted to human-dominated cover such area is “lost” to its native species. Extinctions will ensue. The literature generally assumes that species are extirpated as natural area is reduced, following the well-known species-area relationship (SAR). However, SARs have consistently over-estimated species losses resulting from conversion of natural habitat to human-dominated land covers. We hypothesize that the overestimation occurs because these area-based models assume that converted habitat is “lost”, eliminating all species. However, in the real world, conversion of natural land cover to human-dominated cover frequently produces new land covers, different from the original habitat, but not necessarily completely inhospitable to biodiversity. We evaluated the responses of total avian richness, forest bird richness and open habitat bird richness to remaining natural area within 991 quadrats, each 100 km2, across southern Ontario. Total bird species richness does not follow SAR predictions; rather, the number of bird species peaks at roughly 50% natural land cover. The richness of forest birds does follow the usual SAR power-law as a function of forested area. In contrast, richness of birds that prefer open-habitat does not increase monotonically with either natural- or human-dominated land cover. However, we can partition human-dominated land cover into an “available human-dominated” component and “lost” habitat. Richness of open-habitat species relates to the amount of available human-dominated cover. Distinguishing three habitat types (natural, available human-dominated, and lost) permits accurate predictions of species losses in response to natural habitat conversion.

It is generally assumed that when natural habitat is converted to human-dominated cover such area is “lost” to its native species. Extinctions will ensue. The literature generally assumes that species are extirpated as natural area is reduced, following the well-known species-area relationship (SAR). However, SARs have consistently over-estimated species losses resulting from conversion of natural habitat to human-dominated land covers. We hypothesize that the overestimation occurs because these area-based models assume that converted habitat is “lost”, eliminating all species. However, in the real world, conversion of natural land cover to human-dominated cover frequently produces new land covers, different from the original habitat, but not necessarily completely inhospitable to biodiversity. We evaluated the responses of total avian richness, forest bird richness and open habitat bird richness to remaining natural area within 991 quadrats, each 100 km2, across southern Ontario. Total bird species richness does not follow SAR predictions; rather, the number of bird species peaks at roughly 50% natural land cover. The richness of forest birds does follow the usual SAR power-law as a function of forested area. In contrast, richness of birds that prefer open-habitat does not increase monotonically with either natural- or human-dominated land cover. However, we can partition human-dominated land cover into an “available human-dominated” component and “lost” habitat. Richness of open-habitat species relates to the amount of available human-dominated cover. Distinguishing three habitat types (natural, available human-dominated, and lost) permits accurate predictions of species losses in response to natural habitat conversion.

Concern over recent declines in many wetland-dependent bird species has led to a need to monitor marsh bird populations in response to anthropogenic activities. I conducted point counts and vegetation surveys at 26 coastal wetlands in the Laurentian Great Lakes Region of Canada from 2006-2008 to determine 1) effective methods to monitor marsh birds, and 2) the impacts of land use surrounding coastal wetlands on marsh bird communities. The first part of this dissertation showed that call-broadcasts are effective tools for monitoring marsh birds and that point counts for marsh birds should be conducted from both the shoreline and from the interior of large marshes. Because of the species-area relationship for wetland birds in southern Ontario, sampling effort should increase proportionally with wetland area to attempt the detection of all species present. In the second part of this thesis, I showed that marsh obligate-nesters preferred wetlands in rural areas as opposed to urban areas, while generalist marsh-nesting species showed no apparent difference in use. The Index of Marsh Bird Community Integrity (IMBCI), a biological index used to indicate wetland health, was significantly higher in rural than in urban marshes. Marsh isolation was also an important factor in predicting the marsh bird community, with more isolated wetlands containing fewer obligate species and associated with a lower IMBCI value. Wetlands of Georgian Bay were found to have quite different bird and plant communities than wetlands of Lake Ontario. Even though wetlands of Lake Ontario were considerably more degraded than those in Georgian Bay (according to land use alteration and degree of water quality impairment), these two regions produced similar IMBCI scores, and this draws into question the applicability of some indicators on a basin-wide scale. The results of this thesis indicate how survey protocols in existing wetland bird monitoring programs should be modified and support current literature that urbanization negatively affects the marsh bird community. </p> / Thesis / Doctor of Philosophy (PhD)