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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Road networks, timber harvest, and the spread of Phytophthora root rot infestations of Port-Orford-­cedar in southwest Oregon

Clark, William C. 01 September 2011 (has links)
Phytophthora lateralis is the causal agent of cedar root rot, a fatal forest pathogen whose principal host is Chamaecyparis lawsoniana (Port-Orford-cedar), a predominantly riparian-restricted endemic tree species of ecological, economical, and cultural importance to coastal Oregon and California. Local scale distribution of P. lateralis is thought to be associated with timber harvest and road-building disturbances. However, knowledge of the landscape-scale factors that contribute to successful invasions of P. lateralis is also important for effective land management of Port-Orford-cedar. P. lateralis is able to infest in wet conditions via stream networks (zoospore) and dry conditions via road networks (resting spore). This study tested the hypothesis that vehicles spread P. lateralis by relating its distribution to traffic intensive, anthropogenic disturbances (i.e. a road network, timber harvest) over a 31-yr period in a 3,910-km² portion of the Rogue River-Siskiyou National Forest in the Siskiyou Mountains of Oregon. Indices of road disturbance (presence/absence, configuration, length, density, road-stream network connectivity) and timber harvest (presence/absence, area, density, frequency) were related to locations of infested cedar populations from a USFS survey dataset using a geographic information system (GIS). About 40% of 934 7th-field catchments were infested with the pathogen. Total road length of the study site was 5,070 km; maximum road density was 8.2 km/km2 and averaged 1.6 km/km² in roaded catchments (n = 766). Timber activities extracted 17,370 ha (2,338 cutting units) of forest across 509 catchments; 345 catchments were cut ≥ twice. Maximum harvest density was 0.92 km²/km² ([mean] = 0.04). Both road networks and timber harvest patchworks were significantly related to cedar root rot heterogeneity. Chi-squared contingency tables showed that infestation rates were 2.2 times higher in catchments with roads compared to roadless catchments and 1.4 times higher in catchments with road-stream intersections compared to those that were unconnected. Infestation was twice as likely in catchments with both harvest and road presence than road presence alone. Single-variable logistic regression showed that a one percent increase in harvest density increased infestation odds 25% and a one-unit (km/km²) increase in road density increased infestation odds 80%. Road and stream network configuration was also important to pathogen distribution: 1) uninfested catchments are most likely to be spatially removed from infested, roaded catchments, 2) only 11% of 287 roaded catchments downstream of infested, roaded catchments were uninfested, and 3) only 12% of 319 catchments downstream of infested catchments were uninfested. Road networks and timber harvest patchworks appear to reduce landscape heterogeneity by providing up-catchment and down-catchment access to host populations by linking pathogenic materials to the stream network. Timber harvest data suggest that while infestation risk to Port-Orford-cedar populations remains high, management policies may have curbed infestation risk in timber-harvested catchments; if this is a result of specific P. lateralis mitigation policies adopted in the late 1980's or broader, region-wide conservation policies (i.e. the Northwest Forest Plan) is yet unclear. / Graduation date: 2012
92

CE-QUAL-W2 Water Quality and Fish-bioenergetics Model of Chester Morse Lake and the Cedar River

Wells, Vanessa I. 01 January 2011 (has links)
Many communities are currently seeking to balance urban water needs with preservation of sensitive fish habitat. As part of that effort, CE-QUAL-W2, a hydrodynamic and temperature model, was developed for Chester Morse Lake and the lower Cedar River, WA. Chester Morse Lake is approximately 10 km long with a maximum depth at full pool of 40 m. The Cedar River model started immediately downstream of the Chester Morse dam and ended 21 km downstream at Landsburg, where drinking water is diverted for the City of Seattle. This water quality model was coupled with a fish habitat and bioenergetics model for bull trout and was calibrated to temperature data between 2005 and 2008. Bull trout fish bioenergetics parameters were provided by the USGS. The CE-QUAL-W2 model was found to be highly accurate in modeling temperature variation in the lake - at most locations having an average absolute mean error of between 0.5 and 0.8 oC. The Cedar River model had an average absolute mean error of 0.7oC. This tool is designed to allow managers and operators to estimate the impact to fish habitat and growth potential from various management decisions including extent of drawdown, timing/volume of flows, and various pumping operations. Future studies could include incorporating further water quality parameters such as nutrients, algae, and zooplankton as they relate to fish productivity.
93

Reconstructing environmental forcings on aeolian dune fields : results from modern, ancient, and numerically-simulated dunes

Eastwood, Erin Nancy. 08 September 2014 (has links)
This dissertation combines studies of aeolian bedforms and aeolian dune-field patterns to create a comprehensive set of tools that can be used in tandem (or separately) to extract information about climate change and landscape evolution, and to identify the controls on formation for specific modern dune fields or ancient aeolian sequences. The spatial distribution of surface processes, erosion/deposition rates, and lee face sorting on aeolian dunes are each a function of the incident angle. This correlation between stratification style and incidence angle can be used to develop a “toolbox” of methods based on measurements of key suites of parameters found in ancient aeolian deposits. Information obtained from the rock record can be used as input data for different kinds of numerical models. Regional-scale paleowind conditions can be used to validate paleoclimate and global circulation models. Understanding the natural variability in the Earth’s climate throughout its history can help predict future climate change. Reconstructed wind regimes and bedform morphologies can be used in numerical models of aeolian dune-field pattern evolution to simulate patterns analogous to those reconstructed from ancient aeolian systems. Much of the diversity of aeolian dune-field patterns seen in the real world is a function of the sediment supply and transport capacity, which in turn determine the sediment availability of the system. Knowledge of the sediment supply, availability, and transport capacity of aeolian systems can be used to predict the amount of sand in the system and where it might have migrated. This information can be extremely useful for development and production of oil and gas accumulations, where a discovery has been made but the spatial extent of the aeolian reservoir is unknown. / text
94

Le cèdre blanc (Thuja occidentalis)dans le paysage culturel en amont de Montréal au XIXe siècle. Une approche dendroarchéologique

Brien, Marie-Claude 12 1900 (has links)
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.
95

Le bois d'oeuvre et le port de Montréal, 1830-1870 : une approche dendroarchéologique

Poudret-Barré, Alexandre January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
96

Dendrocronologia, fenologia, atividade cambial e qualidade do lenho de árvores de Cedrela odorata L., Cedrela fissilis Vell. e Schizolobium parahyba var. amazonicum Hub. ex Ducke, no estado do Acre, Brasil / Dendrochronology, phenology and cambium activity and quality of the wood trees of Cedrela odorata L., Cedrela fissilis Vell. and Schizolobium parahyba var. amazonicum Hub. ex Ducke, in Acre state, Brazil

Lobão, Moisés Silveira 27 May 2011 (has links)
O estado do Acre possui uma vocação eminentemente florestal, devido a alta abundância natural de espécies madeireiras em um ecossistema caracterizado pela biodiversidade de espécies tropicais. Pesquisas em dendrocronologia nessa região tropical indicam que 35-50% das espécies arbóreas formam anéis de crescimento. Neste sentido, a dendrocronologia, método baseado na análise de anéis de crescimento anuais no lenho, torna-se importante ferramenta, fornecendo dados de longos períodos de crescimento e estimativas acuradas da idade das árvores, para o entendimento da dinâmica da floresta e desenvolvimento de sistemas de manejo florestal sustentados. Portanto, o objetivo dessa pesquisa foi o de estudar três espécies arbóreas de ocorrência natural no Acre, verificar a influência da quantidade total e distribuição sazonal de pluviosidade, temperatura e evapotranspiração, e os aspectos fenológicos apresentados por cada espécie, no seu crescimento em diâmetro e na qualidade do lenho produzido. O estudo foi realizado em três diferentes sítios, sendo que na Reserva Experimental Catuaba, havia três diferentes microsítios: floresta primária, borda de floresta e pastagem. Avaliou-se mensalmente o incremento em circunferência do tronco das árvores com dendrômetros e a fenologia com observações visuais das árvores das espécies selecionadas. Foram retiradas amostras de lenho no DAP do tronco para as avaliações dendrocronológicas, de densitometria de raios X e anatômicas do lenho. Verificou-se que a fenologia das árvores das espécies estudadas é regulada pela precipitação no mês corrente ou dos meses anteriores. Observou-se que a formação dos anéis de crescimento das árvores dessas espécies é regulada pela evapotranspiração, e pelas fenofases de queda e brotação de folhas nas diferentes estações sazonais do ano, indicando que possuem potencial para estudos paleoclimáticos. A análise da densitometria de raios X e anatômica do lenho mostrou ser possível separar seções de lenho juvenil e adulto no sentido radial do tronco das árvores. Houve diferença significativa no ritmo de crescimento do tronco das árvores entre as espécies, sítios e microsítios. Há grande potencial do uso da dendrocronologia aliada ao uso de parcelas de inventário permanente para a definição do ciclo de corte das árvores dessas espécies / The state of Acre has an eminently forest asset due the high natural timber species abundance in an ecosystem characterized by the biodiversity of tree tropical species. Researches in dendrochronology in this tropical region indicate that 35-50% of species form tree rings. Therefore, dendrochronology, a method based on tree ring analysis becomes important tool, providing data for long growth periods and accurate estimates of trees age, to understanding the forest dynamics and the development of sustainable forestry management. Thus, the objective of this research was to study some tree species of natural occurrence in Acre, verify influence of total amount and seasonal distribution of rainfall, temperature and evapotranspiration, and phenological aspects presented by each species in their growth in diameter and quality of timber produced. The study was conducted at three different sites, and in the Catuaba Experimental Reserve in three different microsites: primary forest, pasture and forest edge.The increase in the circumference the trunk was assessed monthly with a dendrometer and phenology was evaluated with visual observations in selected tree species. Samples were collected from wood in the DBH of the trunk for dendrochronological, X-ray densitometry and wood anatomy assessments. It was found that the phenology of the trees species is regulated by rainfall in the current month or previous months. It was observed that the formation of growth rings of trees of these species is regulated by evapotranspiration, and by phenophases of fall and sprouting new leaf during the year, indicating that these species have potential for paleoclimate studies. The analysis of Xray densitometry and anatomical of the wood allowed to separate portions of the juvenile and adult wood in radial section of the trunk. There were significant differences in the growth of the trunk of tress between species, sites and microsites. There is great potential for the use of dendrochronology combined with the use of permanent inventory plots to define cutting cycles for these species.
97

Advancing the application of analytical techniques in the biological chemistry of sporopollenin : towards novel plant physiological tracers in Quaternary palynology

Bell, Benjamin January 2018 (has links)
Palynology, the study of organic microfossils, is an important tool for improving our understanding of past environments and landscapes. Palynology provides a wealth of information from which climatic and environmental conditions can be inferred. However, inferred climatic and environmental conditions are often open to interpretation. Assumptions made about past climate conditions from pollen assemblages often rely on qualitative understanding of modern-day vegetation distributions, rather than empirical relationships. Historic anthropogenic impact on the environment must also be inferred, and assessments made as to whether vegetation changes are a result of climate change or human impact. This study seeks to address some of the questions that arise through the interpretation of pollen assemblages, by establishing empirical relationships between the geochemistry of modern pollen and climate or environmental controls. It focuses on the pollen of the climatically sensitive montane conifer Cedrus atlantica, which is distributed across the mountains of Morocco and Algeria. The study investigates aspects of modern pollen geochemistry and morphology and finds a strong relationship between the stable carbon isotope composition of modern pollen and mean annual precipitation (r2 = 0.54, p <0.001) and summer precipitation (r2 = 0.63, p <0.0001). Furthermore, a stronger relationship exists with aridity measured using the self-calibrating Palmer Drought Severity Index (r2 = 0.86, p <0.0001), suggesting that the stable carbon isotope composition of Cedrus atlantica pollen is influenced by environmental moisture availability. The study also finds there is an increased abundance of ultraviolet absorbing compounds (UACs) in modern Cedrus atlantica pollen with increasing summer UV-B flux. This relationship was evident with samples growing in their native range (r2 = 0.84, p <0.0001), but not with samples from outside this range (r2 = 0.00, p = 0.99), suggesting a possible genetic influence. Lastly, the study finds that grain size of Cedrus atlantica pollen is highly variable within and between samples, and we rule out climatic control on pollen grain size. These results suggest that quantitative relationships can be established between the geochemistry of Cedrus atlantica pollen and environmental and climatic influences. Stable carbon isotope analysis of fossil pollen could be used as a proxy for reconstruction of summer moisture availability, while analysis of UACs in fossil pollen could be used as a proxy for the reconstruction of summer UV-B flux. These proxies will enhance our understanding of climatic and environmental change in Northwest Africa and will complement existing palynological techniques for environmental and climate reconstruction. Palynology, the study of organic microfossils, is an important tool for improving our understanding of past environments and landscapes. Palynology provides a wealth of information from which climatic and environmental conditions can be inferred. However, inferred climatic and environmental conditions are often open to interpretation. Assumptions made about past climate conditions from pollen assemblages often rely on qualitative understanding of modern-day vegetation distributions, rather than empirical relationships. Historic anthropogenic impact on the environment must also be inferred, and assessments made as to whether vegetation changes are a result of climate change or human impact. This study seeks to address some of the questions that arise through the interpretation of pollen assemblages, by establishing empirical relationships between the geochemistry of modern pollen and climate or environmental controls. It focuses on the pollen of the climatically sensitive montane conifer Cedrus atlantica, which is distributed across the mountains of Morocco and Algeria. The study investigates aspects of modern pollen geochemistry and morphology and finds a strong relationship between the stable carbon isotope composition of modern pollen and mean annual precipitation (r2 = 0.54, p <0.001) and summer precipitation (r2 = 0.63, p <0.0001). Furthermore, a stronger relationship exists with aridity measured using the self-calibrating Palmer Drought Severity Index (r2 = 0.86, p <0.0001), suggesting that the stable carbon isotope composition of Cedrus atlantica pollen is influenced by environmental moisture availability. The study also finds there is an increased abundance of ultraviolet absorbing compounds (UACs) in modern Cedrus atlantica pollen with increasing summer UV-B flux. This relationship was evident with samples growing in their native range (r2 = 0.84, p <0.0001), but not with samples from outside this range (r2 = 0.00, p = 0.99), suggesting a possible genetic influence. Lastly, the study finds that grain size of Cedrus atlantica pollen is highly variable within and between samples, and we rule out climatic control on pollen grain size. These results suggest that quantitative relationships can be established between the geochemistry of Cedrus atlantica pollen and environmental and climatic influences. Stable carbon isotope analysis of fossil pollen could be used as a proxy for reconstruction of summer moisture availability, while analysis of UACs in fossil pollen could be used as a proxy for the reconstruction of summer UV-B flux. These proxies will enhance our understanding of climatic and environmental change in Northwest Africa and will complement existing palynological techniques for environmental and climate reconstruction.
98

Trembling aspen site index in relation to environmental measures of site quality

Klinka, Karel January 2001 (has links)
Trembling aspen (Populus tremuloides Michx.) is one of the most common tree species in the boreal and temperate forests of North America. It grows on many different sites and associates with a variety of tree species. In BC, aspen is frequent throughout all submontane and montane continental forested zones. Relationships between environmental factors and forest productivity have been the subjects of many studies. Most of these studies, using various topographic, soil, physical and chemical properties as independent variables, had limited success in accounting for the variation in SI over a large geographic area. The objectives of this study were (1) to quantify relationships between aspen SI and environmental factors at two spatial scales, and (2) to develop predictive SI models from easily measurable environmental factors.
99

Le cèdre blanc (Thuja occidentalis)dans le paysage culturel en amont de Montréal au XIXe siècle. Une approche dendroarchéologique

Brien, Marie-Claude 12 1900 (has links)
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.
100

Le bois d'oeuvre et le port de Montréal, 1830-1870 : une approche dendroarchéologique

Poudret-Barré, Alexandre January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

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