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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.
1

Developing adaptation strategies for forest management under uncertain future climate

Mbogga, Michael Ssekaayi 11 1900 (has links)
Bioclimate envelope models are widely used to project potential species habitat under changing climate. Conceptually, these models are also well suited to match natural resource management practices to new climatic realities, for example by guiding species choice in reforestation programs. Nevertheless, uncertainty due to a variety of causes has so far limited the practical application of bioclimate envelope models. The goal of this thesis is to examine sources of uncertainty, to reduce uncertainty if possible, and to develop methodology to systematically deal with the remaining variability in model projections. Secondly, this thesis develops practical climate change adaptation strategies for the forestry sector in western Canada. This requires answering what species should be used for reforestation for a particular site, and subsequently selecting planting stock of the species that is best adapted to current and anticipated environments. Using a novel approach to partition variance in results from multiple model runs, climate data were identified as arguably the most important source of uncertainty. Variation was primarily caused by different general circulation models, followed by different emission scenarios. Also, the method used to interpolate current weather station data was an important contributor to uncertainty at specific locations. Other sources of uncertainty were the choice of predictor variables and different bioclimate envelope modeling methods, which primarily contributed to uncertainty through interaction effects. For example, different modeling methods provided similar habitat projections for western Canada on average, but under certain climate change scenarios their results differed markedly. Given the large uncertainties in model projections, it is important to remember that ultimately, climate change adaptation has to be guided by climate trends that actually materialize. A considerable portion of this thesis therefore analyzes climate trends in western Canada over the past century. In a case study for aspen, it is shown that the combined information from multiple bioclimate envelope model runs, climate trends that have already materialized, and observed climate change impacts can make a strong case for implementing adaptation strategies in central Alberta. Amendments to aspen reforestation practices are proposed, avoiding the use of the species in areas where it is likely to lose habitat in the future, and recommending movement of planting stock so that it is reasonably well adapted under a range of future climate scenarios. / Forest Biology and Management
2

Developing adaptation strategies for forest management under uncertain future climate

Mbogga, Michael Ssekaayi Unknown Date
No description available.
3

Assisted migration to address climate change: recommendations for reforestation in western Canada

Gray, Laura Unknown Date
No description available.
4

ASSISTED EVOLUTION AS A TOOL TO INCREASE CORAL THERMOTOLERANCE IN THE RED SEA

Barreto, Marcelle 12 1900 (has links)
The rise of atmospheric CO2 is a threat to many ecosystems, including coral reefs. Rising sea surface temperatures are known to interfere on coral health and cause extensive worldwide mortality. In the Red Sea, coral reefs are spread across 18 degrees of latitude, resulting in a temperature gradient with maximum monthly mean sea surface temperatures ranging from around 33 °C in the south to 27°C in the north. Such gradients can lead to adaptations to local conditions, with coral thermal performance expected to increase along temperature/latitude gradients. In this research, I used the corals Porites lobata and Platygyra daedalea collected in various locations in the Red Sea to resolve fine-scale populational differences in thermotolerance along the Red Sea, and assess if this variability can be explored for potential assisted gene flow projects (i.e. assisted migration and selective breeding) within the Red Sea region. In chapter two, a heat stress assay indicated that P. lobata colonies from the Southern Red Sea have a higher thermal bleaching threshold than conspecifics from Northern latitudes, highlighting their potential as source of temperature resilient colonies. In chapter three, a common garden experimental design showed that thermotolerance of southern P. lobata colonies is maintained when transplanted to a foreign environment. However, despite lack of bleaching in Southern colonies, mortality rates of approximately 20% suggested that other environmental constraints besides temperature might impact coral health and survival. In chapter four, purebred Arabian Gulf larvae generated by cross-breeding colonies of Platygyra daedalea collected along the Red Sea and the Arabian Gulf showed higher survival under heat stress. In addition, paternal survival index increased in crosses with fathers from warmer locations. These results combined indicate that assisted gene flow via translocation alone may have limited success due to a lack of local adaptations to environmental conditions other than temperature. Nonetheless, inter-populational breeding may overcome these limitations as they could generate offspring with both increased thermal tolerance and local adaptations.
5

Engineering Nature under Climate Change – Implications of Assisted Migration on Sustainable Development in Mountain Ranges

Markcrow, Katelin January 2017 (has links)
The Planet has entered a new epoch - the Anthropocene; where human activities, such as mining for and burning of fossil fuels, land-use change, and industrialization are actively disrupting the planet’s state. The rate at which climate change is occurring as a result of human activity is unprecedented in recent millennia and poses many threats through drastic changes in rain fall patterns, rising sea level, retreating glaciers, and an increase in extreme weather events. Mountain ranges and the plant and animal species that thrive in specific ‘life zones’ on the mountain slope are particularly vulnerable to the threats posed by climate change. As temperatures increase, these ‘life zones’ will essentially shift upwards - and flora and fauna either adapt to warmer conditions, or migrate to avoid extinction. This begs the questions, where will species retreat to when there is nowhere further up the mountain to migrate? Assisted migration has been proposed as a potential solution for species unable to adapt to climate change or unable to migrate, and involves the deliberate interference of humans in relocating species to habitats, outside their historic range, in hopes of preventing the species from going extinct. I examined key patterns within assisted migration research from peer-reviewed literature, to highlight the current state of assisted migration research and debate. My aim is to identify whether research favored certain species or geographic locations, to highlight the ethical dilemmas associated with engineering nature, and the potential assisted migration has for sustainable development in mountain ranges. I conducted a literature review and content analysis of 68 journal articles. The results suggest that assisted migration research is heavily debated from scientific, ethical, political and economic perspectives; with a largely theoretical debate and with limited transfer into field experiments. Furthermore, there is an element of bias in research focusing on plant species of economic value as opposed to other species. Moreover, many ethical dilemmas in assisted migration research exist, but no consensus as to whether assisted migration is ethically justifiable. Lastly, I suggest there could be potential for assisted migration for sustainable development in mountain ranges, however there is a need for inter/transdisciplinary research to collaborate in implementing assisted migration.
6

Cultivating Place, Livelihood, and the Future: An Ethnography of Dwelling and Climate in Western Greenland

Hayashi, Naotaka Unknown Date
No description available.
7

THE ECOLOGY AND BEHAVIOR OF SPRING MIGRATING INDIANA BATS (<em>MYOTIS SODALIS</em>)

Roby, Piper Lee 01 January 2019 (has links)
Migration of animals has been studied for decades and has included everything from large terrestrial and pelagic mammals traveling thousands of kilometers to many types of birds flying through several countries to insects going through multiple life cycles in a single migration. The migration of bats has been studied in broad terms to gather coarse information such as distance traveled, connecting summer and winter habitat, and a general understanding of timing. However, only recently have researchers begun to understand the specifics of bat migration including physiology and fine resolution behavior. Using nine years of spring migration data collected on VHF radio-tagged federally endangered female Indiana bats (Myotis sodalis), I predicted behavior based on previous migration studies for bats that used various methods such as band recovery data, stable hydrogen isotopes, and automated telemetry. My project used aerial telemetry to collect location points while tracking individual bats throughout the migration. I describe distances traveled, how much time bats spent in migration, traveling and foraging behavior during migration, and how weather affects bat behavior. In addition, this project resulted in the location of 17 previously unknown maternity colonies for the species including the southernmost colony known to date. Next, I used temperature data collected from individual bats along with ambient temperature to determine how air temperature affects specific bat behavior. I calculated air temperature thresholds for use of torpor in Indiana bats and described how air temperature affects transition states between torpor and normothermy. Finally, I determined landscape preferences for migrating bats during travel and foraging. Indiana bats tend to migrate in a direct path from hibernaculum to summer grounds and use the habitat in the proportion that it is available. Although bats used forested cover when possible, they did travel in open areas (e.g., across agricultural fields) when necessary to continue along the intended trajectory. This data set is the first to track individual nocturnally migrating bats via aerial telemetry for the entirety of the spring migration journey. It provides specific information about how far Indiana bats travel and how long they are migrating across the landscape, illustrates a web of connections between summer and winter habitat, describes the effect of weather on bat behavior, and provides landscape use information that can be useful for land managers and developers.
8

Facteurs écologiques régissant la régénération du chêne rouge (Quercus rubra L.) à la limite nordique de son aire de répartition au Québec

Lebel Desrosiers, Simon 04 1900 (has links)
Nous avons étudié deux chênaies à la limite de l’aire de répartition de l’espèce que Québec afin de reconstruire son historique de régénération et évaluer quels facteurs gouvernent la régénération juvénile. Dans cette optique, nous avons mené une étude dendrochronologique exhaustive des chênaies et une étude sur le terrain et en serre portant sur la germination, la survie et la croissance de quatre provenances de chêne rouge (gradient nord-sud), avec ou sans herbivorie, et selon plusieurs niveaux de nutriments du sol suivant une fertilisation. Les chênaies présentent des structures d’âge similaire qui coïncident avec les dernières perturbations de feu majeures dans la région autour des années 1920. Toutefois, les chênaies diffèrent quant à la densité et la composition en espèces d’arbres, ce qui suggère des différences de régime de feu ou de statut de succession écologique antérieure au feu. Le site a eu la plus grande influence sur la régénération du chêne rouge. Les semis du site présentant la densité d’arbres, l’indice de surface foliaire (LAI) et la disponibilité en eau les plus élevés ont montré un taux de survie supérieur de 29 %. La protection contre la grande herbivorie a également affecté la performance des semis, résultant en au taux de survie supérieur de 16 % et une plus grande taille des feuilles pour trois des quatre provenances étudiées. La provenance a aussi significativement influencé la performance des semis. La provenance locale (la plus nordique) a montré la plus faible performance, avec des taux de germination, de survie et de croissance inférieures de 28 à 42 % dans les deux expériences, alors que les provenances du sud ont montré une meilleure germination et survie en serre et une meilleure survie sur le terrain. L’augmentation de la fertilité du sol s’est avérée bénéfique dans l’expérience en serre mais n’a provoqué qu’un effet marginal sur la croissance et la survie sur le terrain, suggérant que ce facteur importe moins que les autres (ex. la disponibilité en eau et en lumière) pour les stades initiaux de régénération du chêne rouge. Nos résultats suggèrent que les efforts en sylviculture visant à favoriser le chêne rouge devraient se concentrer sur la sélection rigoureuse de sites et de provenances, et que la disponibilité de l’eau peut être une condition limitante pour le succès de la régénération du chêne rouge aux stades de gland et de semis juvénile (semis de l’année) à la limite nordique de son aire de répartition. / We studied two red oak stands at the northern distribution limit of the species in Quebec as a means to reconstruct regeneration history and assess which factors govern early regeneration. To do so, we conducted a thorough dendrochronological study of the stands as well as germination and seedling growth experiments, both in the field and in the greenhouse, of four red oak provenances (south-north gradient), with and without large herbivory, and along various soil nutrient levels following fertilization. Stands have similar age structures with red oak establishment coinciding with the last major fire disturbance in the area in the early 1920s. However, stands differ in regard to tree species composition and density, suggesting differences in fire disturbance regime or ecological succession status prior to fire. Site had the largest influence on red oak regeneration. Seedlings at the site with the highest tree density, LAI and soil water availability exhibited a 29 % higher survival rate. Protection against large herbivory also significantly impacted red oak seedling performance, leading to a 16 % higher survival rate as well as greater leaf size for three of the four provenances studied. Germination, survival and growth also significantly differed between provenances. The local (northernmost) provenance exhibited the poorest overall performance with 28 to 42 % lower germination, survival and growth rates in the two experiments, while the two southernmost provenances exhibited superior germination and sprout survival in the greenhouse and higher survival in the field. An increase in soil nutrient availability was beneficial to red oak in the greenhouse, but only marginally benefited survival and growth in the field, suggesting that this factor is of less importance than other factors (e.g. water and light availability) for red oak early regeneration. Our findings suggest that silvicultural efforts to favor red oak should focus on site and provenance selection, and that water availability is currently limiting red oak regeneration success at acorn and early seedling life stages (i.e. yearlings) near its northern distribution limit.

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