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Competitive Interactions Between Appalachian Hardwoods And Different Groundcovers On Reclaimed Mine Sites, Adam David Klobucar

Masters Theses

Coal mining is a significant industry in Appalachia. Herbaceous groundcovers are commonly planted to reduce soil erosion and protect water quality during mine reclamation, but many groundcovers may be too competitive to be compatible with trees. The objectives of this research were to investigate the performance of trees planted within different groundcovers and to measure how different groundcovers influence resource availability, specifically soil moisture and light

Two studies were performed; one in a greenhouse and the other on 3 mine sites in east Tennessee where seedlings were planted and grown in competition with different groundcovers. Growth, biomass, leaf area, and …

Steps Toward Butternut (Juglans Cinerea L.) Restoration, Sunshine L. Brosi

Doctoral Dissertations

Butternut (Juglans cinerea L.), a lesser-known relative of black walnut (Juglans nigra L.), is a native tree species beneficial for wildlife, valuable for timber, and part of the great diversity of species in the eastern forests of North America. Populations of butternut are being devastated by butternut canker disease, caused by the fungus Sirococcus clavigignenti-juglandacearum (V.M.G. Nair, Kostichka, & Kuntz), which is thought to be introduced to North America. The disease causes multiple branch and stem cankers that eventually girdle trees. Small population sizes, lack of sprouting, and shade intolerance exacerbates the disease and results in permanent losses of butternut …

Conservation Genetics And The Ctenosaura Palearis Clade, Stesha Ann Pasachnik

Doctoral Dissertations

We are now in the midst of a mass extinction crisis. The top threats to biodiversity include habitat destruction, pollution, over-harvesting, and invasive species. The field of conservation genetics seeks to understand these threats and devise management to preserve taxa with the ability to cope with environmental change. Preserving genetic variation and the processes in which variation is created and maintained is vital to long-term conservation goals. Limited conservation resources are cause for the prioritization of taxa and areas. Nine basic methods of prioritization have been developed. Though there are differences in these methods, and thus in the resulting target …

Spatiotemporal Dynamics In A Lower Montane Tropical Rainforest, Robert Michael Lawton

Doctoral Dissertations

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 …

Linking Community Ecology And Biogeography: The Role Of Biotic Interactions And Abiotic Gradients In Shaping The Structure Of Ant Communities., Jean-Philippe Lessard

Doctoral Dissertations

Understanding what drives variation in species diversity in space and time and limits coexistence in local communities is a main focus of community ecology and biogeography. My doctoral work aims to document patterns of ant diversity and explore the possible ecological mechanisms leading to these patterns. Elucidating the processes by which communities assemble and species coexist might help explain spatial variation in species diversity. Using a combination of manipulative experiments, broad-scale surveys, behavioral assays and phylogenetic analyses, I examine which ecological processes account for the number of species coexisting in ant communities. Ants are found in most terrestrial habitats, where …

Optimal Control Of Species Augmentation Conservation Strategies, Erin Nicole Bodine

Doctoral Dissertations

Species augmentation is a method of reducing species loss via augmenting declining or threatened populations with individuals from captive-bred or stable, wild populations. In this dissertation, species augmentation is analyzed in an optimal control setting to determine the optimal augmentation strategies given various constraints and settings. In each setting, we consider the effects on both the target/endangered population and a reserve population from which the individuals translocated in the augmentation are harvested. Four different optimal control formulations are explored. The first two optimal control formulations model the underlying population dynamics with a system of ordinary differential equations. Each of these …

Soil Nitrogen Amendments And Insect Herbivory Alter Above-And Belowground Plant Biomass In An Old-Field Ecosystem, Jarrod Dwayne Blue

Masters Theses

Nutrient availability and herbivory can regulate primary production in ecosystems, but little is known about how, or whether, they may interact with one another. Here I investigate how nitrogen availability and insect herbivory interact to alter above- and belowground plant community biomass in an old-field ecosystem. In 2004, 36 experimental plots were established in which soil nitrogen (N) availability (at three levels) was manipulated and insect abundance (at two levels) in a completely randomized plot design. In 2009, after six years of treatment, I measured aboveground biomass and assessed root production at peak growth. Overall, I found a significant effect …

Population Abundance And Genetic Structure Of Black Bears In Coastal South Carolina, John Michael Drewry

Masters Theses

Because of increasing frequency of bear sightings, vehicle collisions, and nuisance incidents in coastal South Carolina, the South Carolina Department of Natural Resources is developing a comprehensive black bear management plan. However, no reliable estimates of population abundance or density are available. I used genotypes of black bears determined from hair samples collected in Lewis Ocean Bay and Carvers Bay to estimate population abundance and density. I obtained hair samples from snares during 8 weekly sampling periods in 2008 and 2009. I used Huggins closed population models to estimate abundance and spatially explicit capture- recapture models to estimate density. Based …

Evaluating Ecological Restoration In Tennessee Hardwood Bottomland Forests, Elizabeth Anne Summers

Masters Theses

Hardwood bottomland ecosystems provide critical habitat for various wildlife among numerous ecosystem services. Since the 1800s, these forested wetlands have been logged and drained for agriculture. The federal government passed a series of legislative acts that protected wetlands and provided monetary support for restoration. The Wetlands Reserve Program (WRP) was established in 1990 with the goal of restoring ecological function in wetlands. Although several studies have measured plant and wildlife responses to WRP restorations, no standard protocol has been developed to monitor the state of ecological restoration at sites. Index of biotic integrity (IBI) models are commonly used to evaluate …

Evaluation Of Genetic Diversity Of Flowering Dogwood (Cornus Florida L.) In The Eastern United States Using Microsatellites., Denita Hadziabdic

Doctoral Dissertations

Flowering dogwood (Cornus florida L.) populations have experienced severe declines caused by dogwood anthracnose in the past three decades. Mortality has ranged from 48 to 98%, raising the concern that genetic diversity of this native tree has been reduced significantly. Microsatellite data were used to evaluate the level and distribution of genetic variation throughout much of the native range of the tree. In the first conducted study, we found that genetic variation in areas affected by anthracnose was as high as or higher than areas without die-offs. We found evidence of four widespread, spatially contiguous genetic clusters. However, there was …

Early Vessel Evolution And The Diversification Of Wood Function: Insights From The Malagasy Canellales, Patrick Joseph Hudson

Masters Theses

Xylem vessels have long been proposed as a key innovation for the ecological diversification of angiosperms by providing a breakthrough in hydraulic efficiency to support high rates of photosynthesis and growth. However, recent studies demonstrated that angiosperm woods with structurally ‘primitive’ vessels did not have greater whole stem hydraulic capacities as compared to vesselless angiosperms. As an alternative to the hydraulic superiority hypothesis, the heteroxylly hypothesis proposes that subtle hydraulic efficiencies of primitive vessels over tracheids enabled new directions of functional specialization in the wood. However, the functional properties of early heteroxyllous wood remain unknown. We selected the two species …

Molecular Analysis Of Guano From Bats In Bat Houses On Organic Pecan Orchards, Veronica Angelelli Brown

Masters Theses

Bats are generalist predators of night flying insects, including many crop pests. Pecan nut casebearer (Acrobasis nuxvorella), hickory shuckworm (Cydia caryana), and several stink bug species are some of the most damaging crop pests in pecan orchards. Attracting bats to agricultural areas using bats houses may reduce the numbers of these pests and, consequently, their economic impact. This study uses quantitative polymerase chain reaction (QPCR) of mitochondrial DNA found in the guano of bats living in bat houses on organic pecan orchards to document the consumption of pecan nut casebearer, hickory shuckworm, and corn earworm ( …

Plant Genotype And Environment Interact To Influence Soil Carbon And Nitrogen Dynamics, Clara Christina Pregitzer

Masters Theses

Abiotic and biotic variation has been shown to be important in regulating nutrient cycling and belowground communities in natural systems. However, genetic variation in dominant plants as a driver of rates of nutrient cycling is still poorly understood and few studies have looked at genotype interactions across multiple environments. Using Populus angustifolia and a common garden approach, we hypothesized that all three factors: tree genetic variation, environmental conditions and genetic by environment (G x E) interactions would affect soil carbon (C) storage and nitrogen (N) cycling. Replicated copies of five different reciprocally planted Populus genotypes were studied in three separate …

Seasonality, Variation In Species Prevalence, And Localized Disease For Ranavirus In Cades Cove (Great Smoky Mountains National Park) Amphibians, Megan Todd-Thompson

Masters Theses

World-wide amphibian declines sparked concern and encouraged investigation into potential causes beginning in the 1980’s. Infectious disease has been identified as one of the major potential contributors to amphibian declines. For example, Ranavirus has caused amphibian die-offs throughout the United States. Investigators isolated Ranavirus from dead or moribund amphibians during large-scale die-offs of amphibians in the Cades Cove area of Great Smoky Mountains National Park in 1999-2001. In 2009, after nearly a decade without follow-up monitoring, I undertook an investigation to determine if the virus persisted in the area, and if so, to assess spatial, temporal, and taxonomic patterns in …