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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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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.
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Showing 161 to 169 of 169 (0.595 seconds)Spelling suggestions: "subject:"other arcology anda evolutionary angiology"" "subject:"other arcology anda evolutionary asbiology""
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Spatiotemporal Dynamics in a Lower Montane Tropical RainforestLawton, Robert Michael 01 August 2010 (has links)
Disturbance in a forest’s canopy, whether caused by treefall, limbfall, landslide, or fire determines not only the distribution of well-lit patches at any given time, but also the ways in which the forest changes over time. In this dissertation, I use a 25 year record of treefall gap formation find a novel and highly patterned process of forest disturbance and regeneration, providing a local mechanism by examining the factors that influence the likelihood of treefall. I then develop a stochastic cellular automaton for disturbance and regeneration based on the analysis of this long term data set and illustrate the potential of this model for the prediction and detection of patterned forest dynamics in general. Finally, I investigate the spatial structure of a population of one of the most common gap colonist species in this forest, Didymopanax pittieri, and illustrate the effect of local aggregation of treefalls and on the population dynamics of D. pittieri in the process.
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USING STABLE ISOTOPES TO ASSESS LONGITUDINAL DIET PATTERNS OF BLACK BEARS (URSUS AMERICANUS) IN GREAT SMOKY MOUNTAINS NATIONAL PARKTeunissen Van Manen, Jennapher Lynn 01 May 2011 (has links)
Long-term diet patterns based on stable isotope analysis may be helpful to understand changes in food selection of black bears (Ursus americanus) over time and guide management programs to reduce human-bear conflicts. An enriched stable carbon isotope signature indicates an anthropogenic food source in the diet and an enriched nitrogen signature indicates a higher tropic level for a species. I examined longitudinal feeding patterns from 117 hair samples of black bears live captured in Great Smoky Mountains National Park during 1980–2001 using stable carbon and nitrogen isotope analysis from hair samples. I developed a set of a priori models to examine if sex, age class, year, weight class, total hard mast index, white oak index (Quercus spp.), red oak index (Quercus spp.), nuisance status and hog harvest (Sus scrofa) affected stable isotope signatures. I used model averaging and an estimator of the unconditional variance was used to account for model uncertainty. The δ[delta]13C signatures differed by weight class with above average weight, (ß[Beta] = 0.76‰; 95% CI = 0.28 to 1.23) and average weight (ß[Beta] = 0.42‰; CI = 0.06 to 0.78) showing enriched values compared to below average bears. Bears had enriched δ[delta]15N signatures in years with low white oak mast production (ß[beta] = -0.19, CI = -0.34 to -0.03) and depleted when white oak hard mast was abundant. Sub adult bears had enriched δ[delta]15N signatures compared to adult and older adult bears. Variation of nitrogen values was small during 1980–1991 ( = 2.57, SD = 0.28) but increased substantially during 1992–2000 ( = 2.29, SD = 0.71) when there was substantial variation in hard mast production. Bears in better physical condition appear more likely to access anthropogenic food sources. In years of low white oak acorn production, the larger bears and sub adult bears are more likely to turn to alternative food sources. The long term variation detected in this study is important in identifying which bears are potentially more likely to seek out the anthropogenic food sources when changes occur in availability of natural foods.
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Effects of Catastrophic Seagrass Loss and Predation Risk on the Ecological Structure and Resilience of a Model Seagrass EcosystemNowicki, Robert J. 07 November 2016 (has links)
As climate change continues, climactic extremes are predicted to become more frequent and intense, in some cases resulting in dramatic changes to ecosystems. The effects of climate change on ecosystems will be mediated, in part, by biotic interactions in those ecosystems. However, there is still considerable uncertainty about where and how such biotic interactions will be important in the context of ecosystem disturbance and climactic extremes.
Here, I review the role of consumers in seagrass ecosystems and investigate the ecological impacts of an extreme climactic event (marine heat wave) and subsequent widespread seagrass die-off in Shark Bay, Western Australia. Specifically, I compare seagrass cover, shark catch rates, and encounter rates of air breathing fauna in multiple habitat types before and after the seagrass die-off to describe post-disturbance dynamics of the seagrass community, shifts in consumer abundances, and changes in risk-sensitive habitat use patterns by a variety of mesoconsumers at risk of predation from tiger sharks (Galeocerdo cuvier). Finally, I conducted a 16 month field experiment to assess whether xi loss of top predators, and predicted shifts in dugong foraging, could destabilize remaining seagrass.
I found that the previously dominant temperate seagrass Amphibolis antarctica is stable, but not increasing. Conversely, an early-successional tropical seagrass, Halodule uninervis, is expanding. Following the die-off, the densities of several consumer species (cormorants, green turtles, sea snakes, and dugongs) declined, while others (Indo-Pacific bottlenose dolphins, loggerhead sea turtles, tiger sharks) remained stable. Stable tiger shark abundances following the seagrass die-off suggest that the seascape of fear remains intact in this system. However, several consumers (dolphins, cormorants) began to use dangerous but profitable seagrass banks more often following seagrass decline, suggesting a relaxation of anti-predator behavior. Experimental results suggest that a loss of tiger sharks would result in a behaviorally mediated trophic cascade (BMTC) in degraded seagrass beds, further destabilizing them and potentially resulting in a phase shift. My work shows that climactic extremes can have strong but variable impacts on ecosystems mediated in part by species identity, and that maintenance of top predator populations may by important to ecological resilience in the face of climate change.
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Effects of Increased Nitrogen Deposition on the Dominance of Hedera helix in the Pacific NorthwestDolan, Bianca Christine 25 March 2013 (has links)
Increased nitrogen deposition has been shown to promote the dominance of invasive species, and nitrogen deposition rates have steadily increased in most of the Western United States in recent years due to population increases. The purpose of this study was to determine if increased rates of nitrogen deposition are contributing to the success of Hedera helix in the Pacific Northwest. Plots were established in Lesser Park in Portland, Oregon and received monthly treatments of ammonium nitrate for one year. Growth, measured as change in percent cover, was compared between treated and untreated plots for both H. helix and native species. Additionally, a greenhouse experiment was employed wherein H. helix was grown in shared pots with two native species, Fragaria vesca and Polystichum munitum, and three treatment levels were compared; none, low, and high nitrogen. Relative growth rate was compared between treatments for each species after twelve weeks of treatment. Results from the greenhouse experiment were highly variable and no general conclusions could be drawn about the effects of increased nitrogen deposition on competition between H. helix and native species. In the field, treatment did not have a significant effect on growth but species did have a significant effect, as H. helix had a greater increase in percent cover than native species regardless of treatment. However, a marginally significant interaction was found between species and treatment. Native species cover actually increased in plots that received nitrogen addition and decreased in control plots, while H. helix had a slightly higher increase in cover in control plots. Though the growth of H. helix was significantly higher than the growth of native species in control plots, nitrogen addition caused the growth rates to converge towards more similar means in treated plots. Results indicate that increased nitrogen deposition may actually have a positive effect on the growth of native species by reducing the invasive potential of H. helix.
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Evaluating non-invasive environmental methods for detecting tropical African pangolin species to inform conservation actionsIchu, Ichu Godwill 09 August 2022 (has links) (PDF)
Tropical African pangolin species are threatened throughout their range due to habitat loss and illegal take. Limited knowledge on distribution has rendered conservation efforts challenging. Methods commonly used for other wildlife species need to be tested for each pangolin species as each has variable ecologies requiring specific detection and monitoring techniques. This thesis evaluates the efficacy of two non-invasive environmental methods for detecting tropical African pangolin species, and consists of two complementary studies; a proof of concept study using soil sourced eDNA from a white-bellied pangolin enclosure in the Columbus Zoo, Ohio, to detect the species, and a field study in the Campo Ma’an National Park, Cameroon, to evaluate the efficacy of targeted camera traps (terrestrial and arboreal), and environmental DNA (soil sourced eDNA and water sourced eDNA) to detect each tropical African pangolin species. Study results contribute to future ecological monitoring efforts for each species to inform conservation actions.
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Effect of Alliaria petiolata management on post-eradication seed bank dynamicsThompson, Chloe 01 September 2023 (has links) (PDF)
ABSTRACT Alliaria petiolata (garlic mustard) is an aggressive non-native and invasive forb that negatively impacts native arbuscular mycorrhizal communities and inhibits or prevents the growth of native plant species. Invasive species mitigation and management strategies that use native revegetation vary in success. This study focuses on which species naturally regenerate in areas where A. petiolata has been mitigated to help inform restoration efforts. Seedling emergence of species within the seed bank of four plot types (uninvaded, invaded, chemically treated, and mechanically treated) were observed two years post restoration efforts to determine which native species are likely to persist to seedlings following management. Species abundance and percent cover of all plant species were recorded to evaluate the presence of species in addition to plant health and physiological differences. Native species abundance was significantly reduced within herbicide treated plots as compared to untreated and invaded plots (p=0.02). Plots treated with mechanical removal had the greatest percent cover of native plants as compared to all other plot types but were dominated by colonizing species which is typical of a disturbed habitat. Mechanical removal also resulted in a greater abundance and stability among functional groups of native species, than those treated with herbicide. Forb species dominated coverage of plots over other functional groups when treated with herbicide. Alliaria petiolata invasion and management methods significantly impacted forb and graminoid species, as they had significantly lower abundance in plots treated with herbicide. The results demonstrate that the method of removal as well as the presence of A. petiolata affects emergence of plant species from the seedbank. The additional disturbance of mechanical removal may alter successional trajectories following invasion. Herbicide treatment resulted in the most similar species abundance as the uninvaded reference plots, which had the lowest seedling emergence and percent cover.
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FACTORS INFLUENCING THE ESTABLISHMENT AND SURVIVAL OF NATIVE HARDWOOD TREE SEEDLINGS OF THE KENTUCKY INNER BLUEGRASS BLUE ASH-OAK SAVANNA-WOODLANDShaffer, James D 01 January 2013 (has links)
Historically, the Kentucky Inner Bluegrass blue ash-oak savanna-woodland was the primary ecosystem of the Inner Bluegrass Region (IBR) of Kentucky. After European settlement, the majority (>99%) of Bluegrass savanna was converted to agricultural and urban land uses. Currently remnant savanna tree species are failing to recruit. Therefore, a long-term restoration ecology project researching competition and disturbance on seedling establishment, survival, and growth has been established at Griffith Woods (the largest remaining savanna in Kentucky) in Harrison Co., KY. Fourteen native hardwood tree species (a total of 6,168 seedlings) have been experimentally planted. Light, soil, surrounding vegetation, and herbivory, factors thought to influence seedling survival, have been initially assessed. Results show that soils differed spatially in P, Ca, Mg, Zn, pH, N percent and soil organic matter percent. Light was significantly reduced by diffusive filtering through vegetation. Vegetation biomass was influenced by pH and Mg. Initial seedling survival was high, but significantly differed by species type, location, and soil pH, Mg, and Zn. This research demonstrates that under a similar range of conditions, native hardwood tree seedling establishment is possible. Therefore, the potential exists to restore Bluegrass savanna-woodland in order to return proper ecological functioning into a degraded landscape.
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Reimagining Movements: Towards a Queer Ecology and Trans/Black FeminismBenavente, Gabriel 30 March 2017 (has links)
This thesis seeks to bridge feminist and environmental justice movements through the literature of black women writers. These writers create an archive that contribute towards the liberation of queer, black, and transgender peoples.
In the novel Parable of the Talents, Octavia Butler constructs a world that highlights the pervasive effects of climate change. As climate change expedites poverty, Americans begin to blame others, such as queer people, for the destruction of their country. Butler depicts the dangers of fundamentalism as a response to climate change, highlighting an imperative for a movement that does not romanticize the environment as heteronormative, but a space where queers can flourish.
Just as queer and environmental justice movements are codependent on one another, feminist movements cannot be separate from black and transgender liberation. This thesis will demonstrate how writers, such as Audre Lorde, Toni Morrison, Angela Davis, and Janet Mock, help establish a feminism that resists the erasure of black and transgender people.
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SPEED AND RESOLUTION IN THE AGE OF TECHNOLOGICAL REPRODUCIBILITYTAYLOR, SHAWN 01 January 2015 (has links)
The rate of acceleration of the biologic and synthetic world has for a while now, been in the process of exponentially speeding up, maxing out servers and landfills, merging with each other, destroying each other. The last prehistoric relics on Earth are absorbing the same oxygen, carbon dioxide and electronic waves in our biosphere as us. A degraded .jpeg enlarged to full screen on a Samsung 4K UHD HU8550 Series Smart TV - 85” Class (84.5” diag.). Within this composite ecology, the ancient limestone of the grand canyon competes with the iMax movie of itself, the production of Mac pros, a YouTube clip from Jurassic park, and the super bowl halftime show. A search engines assistance with biographic memory helps our bodies survive new atmospheres and weigh the gravities that exist around the versions of an objects materiality. Communication has moved from our vocal chords, to swipes and taps of our thumbs on a screen that predicts the weather, accesses the hidden, invisible, and withdrawn information from the objects around us, and still ducks up what we are trying to say. This txt was written on a tablet returned to stock settings and embedded with content to mine the experience in which mediated technology creates, communicates and obscures new forms of language. Life in a new event horizon — a dimensional dualism that finds us competing for genetic and mimetic survival — we are now functioning as different types of humans.
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