Ce mémoire porte sur le cèdre blanc (Thuja occidentalis) dans les contextes de colonisation et d’exploitation forestière de l’arrière-pays montréalais au XIXe siècle. Il vise, d’une part, à documenter les stratégies d’exploitation locale du cèdre blanc au XIXe siècle et l’évolution du paysage culturel domestique d’un établissement colonial depuis sa concession initiale. D’autre part, ce mémoire cherche à identifier les réseaux d’échanges du cèdre blanc acheminé à Montréal au XIXe siècle pour la construction des bâtiments et des infrastructures portuaires. En raison de la quasi-absence de documents historiques sur le sujet, il devient évident que seule l’application de la dendrochronologie et de la dendroprovenance permet d’atteindre ces objectifs. Nous vous présentons ici l’analyse détaillée de six sites ruraux situés dans les vallées de l’Outaouais et du haut Saint-Laurent. Les analyses dendrochronologiques effectuées permettent d’aborder l’établissement colonial d’une façon originale. La deuxième partie de ce mémoire se consacre aux analyses de dendroprovenance de sept sites montréalais préalablement étudiés par Poudret-Barré (2007) et le Groupe de recherche en dendrochronologie historique (GRDH). Pour ce faire, les sites ruraux discutés précédemment servent de point d’ancrage géographique afin de déterminer l’origine des pièces de cèdre blanc retrouvées à Montréal. L’étude du cèdre blanc et les résultats des analyses de dendrochronologie et de dendroprovenance réalisées dans le cadre de cette étude permettent d’aborder le patrimoine architectural et archéologique sous un angle nouveau. Venant compléter les données historiques disponibles, il ouvre la voie à de nouvelles recherches de ce genre. / This master’s thesis is about the colonization context and forestry exploitation of eastern white cedar (Thuya occidentalis) in the Montreal hinterland of the 19th century. On the one hand, it aims to document the local exploitation strategies of eastern white cedar and the evolution of the domestic cultural landscape of colonial landholdings since their initial concession. On the other hand, this thesis seeks to identify the exchange networks of the cedar timber that was shipped to Montreal for the construction of the city’s buildings and port facilities. With the near absence of historical documentation on the subject, only the application of the dendrochronology and the dendroprovenancing allows us to attain our objectives. We present a detailed analysis of six rural sites in the Ottawa and the Upper Saint Lawrence Valleys. Dendrochronology analysis of these areas enables us to tackle colonial establishment in an original way. The second part of this thesis is dedicated to the dendroprovenancing analysis of seven Montreal sites, all studied beforehand by Poudret-Barré (2007) and the Groupe de recherches en dendrochronologie historique (GRDH). To do so, the previously designated sites will serve as a geographic anchor point to help us determine the origin of the pieces of eastern white cedar found in Montreal. Our study of eastern white cedar along with the results of the dendrochronology and dendroprovenancing analysis allows us to tackle the architectural and archeological heritage from a new angle. Completing the available history data, it also opens the way to new research of the same kind.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Ce mémoire porte sur le cèdre blanc (Thuja occidentalis) dans les contextes de colonisation et d’exploitation forestière de l’arrière-pays montréalais au XIXe siècle. Il vise, d’une part, à documenter les stratégies d’exploitation locale du cèdre blanc au XIXe siècle et l’évolution du paysage culturel domestique d’un établissement colonial depuis sa concession initiale. D’autre part, ce mémoire cherche à identifier les réseaux d’échanges du cèdre blanc acheminé à Montréal au XIXe siècle pour la construction des bâtiments et des infrastructures portuaires. En raison de la quasi-absence de documents historiques sur le sujet, il devient évident que seule l’application de la dendrochronologie et de la dendroprovenance permet d’atteindre ces objectifs. Nous vous présentons ici l’analyse détaillée de six sites ruraux situés dans les vallées de l’Outaouais et du haut Saint-Laurent. Les analyses dendrochronologiques effectuées permettent d’aborder l’établissement colonial d’une façon originale. La deuxième partie de ce mémoire se consacre aux analyses de dendroprovenance de sept sites montréalais préalablement étudiés par Poudret-Barré (2007) et le Groupe de recherche en dendrochronologie historique (GRDH). Pour ce faire, les sites ruraux discutés précédemment servent de point d’ancrage géographique afin de déterminer l’origine des pièces de cèdre blanc retrouvées à Montréal. L’étude du cèdre blanc et les résultats des analyses de dendrochronologie et de dendroprovenance réalisées dans le cadre de cette étude permettent d’aborder le patrimoine architectural et archéologique sous un angle nouveau. Venant compléter les données historiques disponibles, il ouvre la voie à de nouvelles recherches de ce genre. / This master’s thesis is about the colonization context and forestry exploitation of eastern white cedar (Thuya occidentalis) in the Montreal hinterland of the 19th century. On the one hand, it aims to document the local exploitation strategies of eastern white cedar and the evolution of the domestic cultural landscape of colonial landholdings since their initial concession. On the other hand, this thesis seeks to identify the exchange networks of the cedar timber that was shipped to Montreal for the construction of the city’s buildings and port facilities. With the near absence of historical documentation on the subject, only the application of the dendrochronology and the dendroprovenancing allows us to attain our objectives. We present a detailed analysis of six rural sites in the Ottawa and the Upper Saint Lawrence Valleys. Dendrochronology analysis of these areas enables us to tackle colonial establishment in an original way. The second part of this thesis is dedicated to the dendroprovenancing analysis of seven Montreal sites, all studied beforehand by Poudret-Barré (2007) and the Groupe de recherches en dendrochronologie historique (GRDH). To do so, the previously designated sites will serve as a geographic anchor point to help us determine the origin of the pieces of eastern white cedar found in Montreal. Our study of eastern white cedar along with the results of the dendrochronology and dendroprovenancing analysis allows us to tackle the architectural and archeological heritage from a new angle. Completing the available history data, it also opens the way to new research of the same kind.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

The western spruce budworm (Choristoneura occidentalis Freeman) is the most widespread and destructive defoliator of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests in British Columbia. Over the past two decades, western spruce budworm outbreaks have been sustained and widespread in the interior of British Columbia, leaving the forest industry and many forest-dependent communities increasingly vulnerable to the economic consequences of these outbreaks. While a great deal is known about the impact of western spruce budworm outbreaks on tree growth and form, substantial knowledge gaps remain as to the historic variability of western spruce budworm outbreaks and the consequences of defoliation on fundamental characteristics such as wood structure. This research focused on describing historic and contemporary western spruce budworm outbreaks across multiple spatial and temporal scales in south-central British Columbia using dendrochronology and wood anatomy techniques. Outbreak histories over the past 435 years were reconstructed using a network of tree-ring chronologies from central British Columbia, revealing that 12 western spruce budworm outbreaks have occurred since the early 1600s, with a mean return interval of 30 years. Further, the research illustrates that outbreaks observed over the last 40 years are not unprecedented, which does not support the perception that western spruce budworm is moving northward into central British Columbia. To evaluate the effects of a single western spruce budworm outbreak on the anatomical characteristics of Douglas-fir stemwood, tree ring data was collected from permanent sample plots that sustained both periodic and chronic western spruce budworm feeding. In mature even-aged stands of Douglas-fir, a documented outbreak occurred from 1976 to 1980 in the coastal transition zone of southern British Columbia. Based on microscopic wood anatomical measurements it was shown that the tree rings formed during this outbreak had significantly lower percentages of latewood, reduced mean cell wall thickness and smaller radial cell diameters relative to wood formed during periods without budworm feeding. Western spruce budworm defoliation temporarily modified cellular characteristics, which has implications for wood quality. In uneven-aged stands of mature Douglas-fir, located in the xeric southern interior of British Columbia, there has been a sustained western spruce budworm outbreak since 1997. Tree rings formed during this outbreak had progressively larger earlywood lumen area and radial cell diameter, reduced latewood cell wall thickness, latewood radial cell diameters, and lower percent latewood. Mixed-effects models revealed that climatic variables, defoliation severity, defoliation duration, and in limited cases canopy class were the best predictors of xylem features. The severity and duration of western spruce budworm defoliation, as well as site factors that influence moisture conditions effect the degree and direction of anatomical changes in the stemwood of Douglas-fir. This research fills a number of knowledge gaps by providing insights into the temporal and spatial dynamics of western spruce budworm outbreaks in central British Columbia over multiple centuries, and the plasticity of anatomical features in the stemwood of Douglas-fir during discrete western spruce budworm outbreaks. These research findings suggest that Douglas-fir forests are resilient to western spruce budworm outbreaks over space and time. / Graduate

Marine non-native species threaten economic and environmental health, making it crucial to understand factors that make them successful. Research on these species, therefore, allows for greater preparedness and informed management of biological invasions and increases understanding of elements structuring biological communities. Among the marine non-native species, and particularly the fouling community, non-native ascidians are a taxon of particular concern because they can crowd out native benthic species and smother mariculture products. This thesis addresses management for ascidians and other fouling organisms and includes research on the invasiveness of this taxon in addition to the invasibility of recipient fouling communities. On the West Coast of the U.S., limited efforts have been made to coordinate biofouling management across states, despite the myriad vectors increasing propagule pressure over time along coastal states. Building on recent state and local efforts, I developed a Pacific Regional Biofouling Plan for the states of Oregon and Washington to help start a consensus-driven process by which these states could create a forum for more comprehensive coordination efforts, following California's lead. As states address authority gaps, the biofouling management framework I've written is meant to be used to guide the conversation between managers as various stages of coastal management are realized. To better inform the scope and efficacy of management and regulatory efforts, the study of invasions ecology asks and aims to answer questions regarding recipient community interactions and characteristics of the non-native species themselves. Studies that identify characteristics that make ascidians successful (invasiveness) and determine the influence native communities have on their success (invasibility) are important for assessing overall risk of establishment and spread from non-native ascidians. Therefore, I aimed to: 1) explore the hypothesis that fouling communities on suspended, artificial structures are more invasible than benthic habitats; and 2) identify characteristics influencing predation patterns on the native Distaplia occidentalis versus non-native ascidian species using mensurative and experimental studies in Charleston Marina, Oregon. I conducted a series of feeding assays, surveys, and a caloric content analysis. Feeding assays were conducted with a suite of predators. The flatworm predator (Eurylepta leoparda) was found to be highly selective on the native ascidian Distaplia occidentalis, and only preyed on whole colony samples. Feeding assay data suggest that test (tunic) structure or thickness may be an influential factor affecting nudibranch (Hermissenda crassicornis) predation rates on native versus non-native ascidians, with greater predation on the native ascidian species. Non-native ascidians may escape predation in floating but not benthic environments on the Oregon coast due to their palatability characteristics, likely tunic structure and low caloric content. In this case, this suite of predators may indirectly facilitate the invasion of docks but provide at least partial resistance to the invasion of natural benthic areas. The chapters herein address gaps in management and scientific knowledge regarding non-native species of the marine fouling community. Future work enhanced by my efforts could include the development of the coastal biofouling management plan, coordinated by the Western Regional Panel on Aquatic Invasive Species Coastal Committee, and broadening the geographic and taxonomic scope of my research with a more comprehensive study of predator-prey interactions involving non-native ascidians and a diverse suite of predators. These interactions may be an important factor in explaining the success of ascidians and other fouling organisms on floating structures and lack of success on nearby benthic substrata.

No description available.

There is concern that climate change may cause mismatches between timing of flowering and activity of pollinators (phenology). However, concluding that mismatches will occur, and have serious consequences for pollination services, requires assumptions that have not yet been tested. I begin by discussing a set of these assumptions, bringing past research into the context of mismatch. Briefly, the assumptions are that 1) dates of first-flowering or emergence (DFFE) correctly describe phenology (and therefore mismatch); 2) differences in DFFE represent the magnitude of mismatch; 3) advancement of DFFE will be the primary phenological change; 4) shifts will be random and independent for each species; 5) populations of plants and pollinators are “bottom-up” regulated by their mutualistic interactions; 6) all interactions are of similar strength and importance; 7) dispersal, and the spatial context of phenological mismatches can be ignored; and ecological processes including 8) phenotypic plasticity and adaptive evolution of phenology, 9) competition and facilitation, and 10) emergence of novel interactions, will not affect mismatches. I then describe novel experiments, which could help to account for some of these assumptions, clarifying the existence and impacts of mismatches. Next, I present an original field experiment on factors affecting seed set in an alpine meadow in the Coast Range of British Columbia, Canada. I found evidence contradicting the assumption that seed set is primarily limited by pollination. My data highlight the roles of phenology, temperature (degree-days above 15°C, and frost hours), and interactions with pollinators (mutualists) and seed-predators (floral antagonists) in driving patterns of seed set. Seed set of early and late-flowering species responded differently to a 400m elevation gradient, which might be explained by phenology of bumble bees. My data suggest that the consequences of mismatch may be smallest for plants that are fly-pollinated and self-fertile. Non-selfing, bee-pollinated species might be more prone to reproductive limitation through mismatch (affected by snowmelt and cumulative degree-days). Plants that are limited by seed-predators might be negatively affected by warming temperatures with fewer frost hours, and extreme events such as late-season frosts and hail storms can prevent plants from setting seed entirely. Overall, my work emphasizes the importance of complementing theory, data-driven simulations, and meta-analyses with experiments carried out in the field. / Graduate

No description available.