<p> The pollen, charcoal and sediment stratigraphies of two cores from small lakes located northeast of Yellowknife, NWT are examined. The focus of this study is to reconstruct post-glacial vegetation changes in this climatically sensitive area. The resulting vegetation history is compared to similar reconstructions from across Canada. The pollen content of twenty-eight modern sediment samples, collected from the forest, the forest-tundra and the tundra zones were used to aid in the interpretation of the fossil record. Radiocarbon dates indicate that the fossil records from these lakes span ~7 500 years. The initial vegetation, shrub Betula tundra, was established at ~7 000 BP and persisted until ~6 000 BP. The presence of Ericaceae, Myrica, and Sphagnum distinguishes this zone from similar zones from western Canada and suggests the existance of large areas of bog environment. This zone is succeeded by a second shrub tundra zone, which is marked by a dramatic increase in Alnus crispa and Alnus incana. This zone spans from ~6 000 BP until ~5 000 BP. A synchronous increase in Alnus is noted from sites across Canada and is attributed to an increase in moisture. The third zone, spanning from ~5 000 BP to ~3 500 · BP, delimits the existance of forest vegetation defined by the northward expansion of Picea mariana. The delay of Picea mariana expansion into the area relative to its arrival in western Canada can be explained by one of the following: 1) geological differences; or 2) remnant glacial ice retarding climatic amelioration; or 3) the long-wave westerly disturbance, which causes cooler temperatures in the east when warmer temperatures persist in western Canada; or 4) some combination of the above. The decline of forest vegetation at ~3 500 BP marks the establishment of modern tundra vegetation at both sites. Climatic cooling coupled with fire caused the extinction of aboreal vegetation at the study sites.</p> / Thesis / Master of Science (MSc)

This research project used many disciplines to examine the impacts of industrialisation on the wooded landscape of the South Pennines. The woodlands of this upland region are characterised by their small size and steep topography. Nevertheless, they exhibit a rich archaeology of management from the medieval period onwards. Field survey of case study sites was combined with charcoal analysis from excavated burning platforms, palynology of soil cores, tree ring analysis and ecological survey. This was set within a historical context, particularly focusing on the regional industries of iron, leather and textiles, in order to understand the economic motivations for changes in woodland management. The woodlands examined showed a diverse range of histories. Some had a strong correlation with models of changing woodland management culture of neighbouring regions, particularly the evolution of systematic oak-dominated coppice in response to industrial demands. Woodland management in the South Pennines was more sensitive to industries which created dispersed demand from many actors than to bulk demand from centralised industries and responded to the changing economics of the fossil fuel era. The dominance of freehold tenure also contributed to many woodlands being managed in an unsystematic manner and the survival of private wood pasture alongside timber harvesting. / Arts and Humanities Research Council through the Heritage Consortium

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Smallholder households in Haiti face many natural resource management challenges. Agricultural production occurs on deforested hillsides prone to erosion. Charcoal is in an important source of income, and woodfuel stocks are often over-exploited. Donor-funded projects and non- governmental organizations have made large investments in programs that promote soil conservation practices and reforestation. Despite the magnitude of the problems and the amount invested, there are relatively few economic analyses of the long-term adoption of soil conservation practices and woodfuel management. This dissertation uses an economics approach to examine the adoption of conservation practices and the management of woodfuel resources in Central Haiti using cross-sectional data covering 600 households. The results show that plot and household characteristics have different effects on adoption across different classes of soil practices, particularly with regard to perceived soil quality, market access, and household health status. The results also provide evidence of the management of charcoal woodfuel stocks on private land. These findings inform the design and targeting of new programs related to soil conservation and reforestation in Haiti and other developing countries. / Ph. D.

Sur la base de constats globaux concernant l’importance d’appliquer des modes de gestion durable des zones forestières et le manque d’investigation concernant l’histoire passée des feux en Europe centrale, il a été entrepris de reconstruire l’histoire des événements de feux et de la dynamique forestière pour des sites d’étude en Allemagne. L’ensemble des données obtenues et analysées ont été utilisées pour l’évaluation du niveau de naturalité des sites étudiés, cette notion étant essentielle pour la mise en place d’une gestion durable, et/ou pour des projets de conservation et / ou de restauration des systèmes perturbés. Concernant les dynamiques des écosystèmes en Europe centrale, il a été souvent mis en évidence que l’homme joue un rôle essentiel depuis des millénaires. Par conséquent, l’approche historique des événements de feux et de la dynamique forestière à été réalisée sur de longues échelles temporelles. Neuf sites d’étude ont été sélectionnés incluant une large gamme de systèmes forestiers d’Europe centrale. Les sites d’études sont répartis dans deux zones générales d’étude : le nord de l’Allemagne (Schleswig-Holstein), qui comprend quatre sites d’étude, et le centre de l’Allemagne (le Harz), qui comprend cinq sites d’étude. Quatre disciplines ont été principalement utilisées. Pour définir l’état actuel des sites d’études ceux-ci ont été caractérisés, utilisant divers indicateurs dendrométriques concernant la structure et la composition des parcelles analysées. Pour obtenir des informations à propos de la dynamique forestière des peuplements forestiers en place des analyses dendroécologiques ont été utilisées. Pour analyser la dynamique forestière sur une longue échelle temporelle, à une échelle spatiale comparable, des analyses pédoanthracologiques ont été menées, combinées à des analyses de sols. De plus, des analyses anthracologiques de séquences de tourbes ont été réalisées, fournissant, combinées avec les données pedoanthracologiques, des enseignements à propos de l’histoire des incendies. L’état actuel et la dynamique forestière récente des sites étudiés indiquent divers niveaux de complexité des peuplements forestiers, correspondant souvent à divers niveaux postulés d’impact anthropique. Il a été obtenu huit chronologies moyennes, standardisées en haute et moyenne fréquences, âgées au maximum de 1744 et au minimum de 1923 ans. A partir de ces chronologies des changements dans les conditions de croissance de peuplements forestiers ont été mises en évidence. Basées sur un ensemble de 71 charbons de bois datés par radiocarbone, il a été mis en évidence, à l’échelle locale et globale, deux principales phases présentant plus d’événements de feux datés, une durant le Pléistocène supérieur/Holocène inférieur, une autre durant l’Holocène supérieur. Pour les deux phases identifiées des forçages climatique et anthropogénique ont été respectivement postulés comme déterminisme des occurrences de feux. Finalement, les différentes données collectées ont été utilisées de façon combinée pour reconstruire l’histoire des feux et des forêts des sites étudiés, afin de contribuer à l’évaluation de leur niveau de naturalité. / Considering two global observations in Central Europe of, firstly, the need for, and development of, sustainable and biological conservation practices for forest and/or woodland areas and, secondly, the lack of long-term fire history, an attempt has been made to reconstruct the fire and the forest history at several investigation sites in Germany. The overall data set gathered and analyzed has been used for on-site naturalness assessment. This latter notion is crucial for forest system conservation/restoration planning, considering the past human impact on forest dynamics. Also, in view of this past human impact on forest systems, which is well-documented for Central Europe, as occurring on a multi-millennium scale, an historical perspective perceptive that combined a long and short temporal scale of investigation was used.Nine investigation sites were selected, in order to include various and representative types of Central European forest. Therefore, the investigation sites were located in two main investigation areas. One is in Northern Germany (Schleswig-Holstein) and includes four investigation sites. The other is in Central Germany (Harz Mountains) and includes five investigation sites. Four main approaches were used. To assess the current state of the investigated site, forest stand characterization was undertaken (i.e. based on various forest attributes that concern stand structure and composition). Tree ring series were analyzed to provide insights about short-term forest tree population dynamics. Then, charcoal records from soil (combined with soil analysis) and peat sequences were qualitatively and quantitatively analyzed. These last two approaches also provide information about the past fire history. Forest current and short-term dynamics illustrated various levels of stand complexity, often corresponding to various levels of human impact that had been postulated. Eight mean site tree-ring chronologies, standardized in high and mid-frequency signal, spanning at a maximum of up to AD 1744 and at a minimum of up to AD 1923, were obtained. The insight, about the identification of events of growing changes and the correlated temporal and, if possible, spatial patterns, was discussed. Charcoal analysis provided a long-term insight about fire history. Based on 71 charcoal radiocarbon dates, it was shown on a macro-scale that there were two phases that had a greater frequency of fire - one during the transition from the late Pleistocene to the early Holocene, and one during the mid- and late Holocene. A strong human control during the most recent fire phase has been postulated. This is supported by on-site soil and peat charcoal record analysis, allowing one to point out the event of environmental changes (disturbances), at local scales. In the end, the on-site data from the various indicators were combined to assess the fire and forest history and the naturalness level of the investigated sites, based on past insights, thereby contributing to a better understanding of the present and helping to anticipate the future.

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La région du lac Mégantic est probablement la première zone à s'être déglacée au Québec, ce qui lui confère un intérêt particulier. L'analyse pollinique et anthracologique des sédiments des trois lacs situés à ses abords, soit les lacs Clinton, Dubuc et des Joncs ont permis de reconstituer l'histoire locale et régionale de la végétation et des feux. La présence d'un gradient altitudinal a entrainé des décalages surtout dans l'instauration des premières phases forestières. La région s'est déglacée vers 13 500 ans AA, et une toundra s'y est installée. Le début de l'afforestation est marqué par l'arrivée du sapin baumier et de l'épinette noire. Par la multiplication de leurs populations, la forêt s'est fermée vers 10 000 ans AA pour constituer une forêt boréale qui fût alors perturbée par plusieurs épisodes de feux. Vers 8000 ans AA, les nouvelles conditions climatiques favorisent les espèces feuillues et instaurent une érablière à bouleau jaune et une diminution de la fréquence des feux. Les résultats obtenus permettent d'enrichir les connaissances paléophytogéographiques et anthracologiques du Québec. / The Lac Mégantic area is probably the first deglaciated in Quebec (13,500 cal. BP) which gives it a special interest. The pollen and charcoal analysis in sediments of three lakes located in its vicinity, Clinton, Dubuc and des Joncs Lakes, helped to reconstruct postglacial vegetation and fire, locally and regionally. The presence of an altitudinal gradient resulted in some delays in the introduction of various forest stages especially at the beginning. At start, tundra established in the region. The start of the afforestation is marked by the arrival of the balsam fir and black spruce. By multiplying their populations, the forest closed around 10,000 years cal. BP to build a boreal forest and was also disturbed by multiple fires. By 8,000 years cal. BP, new conditions favored deciduous species and created a sugar maple and yellow birch forest associated with lower fire frequencies. This study offers new perspectives in fire and forest reconstitutions by using proximal sites.