Physical and Environmental Geography Commons^™

Climatological Analysis Of Tropical Cyclone Occurrence Dates And Landfall Characteristics In The North Atlantic And Eastern North Pacific, Nicholas Sava Grondin

Doctoral Dissertations

Tropical cyclones (TCs) are significant hazards to coastal and inland regions across the globe, especially in North America. North America is affected by TCs from two basins, the North Atlantic (NATL) and eastern North Pacific (ENP), with the former being the predominate focus of past research. In this dissertation, I present three studies that directly compare TCs in the NATL and ENP by using the same methods for each basin in studying occurrence dates and intraseasonal variability, effects of environmental parameters on occurrence dates and seasonal forecasting, and the behavior of TCs during the final 36 hours before landfall in …

The Global Impact Of The Antarctic Ice Sheet In A Warming World: Using Numerical Modeling And Critical Physical Geography To Assess Climate Change, Sea Level Rise, And Climate Justice

Doctoral Dissertations

Anthropogenic climate change is causing disruptions in the Earth system with negative ramifications for life on our planet. Increasing atmospheric greenhouse gas concentrations lead to accumulated heat content and the cryosphere is one of the earliest places to show changes in response to rising temperatures. The melting of the Antarctic Ice Sheet will have myriad effects on global climate due to interconnections and feedbacks between the ice sheet, ocean, and atmosphere. In this dissertation I use numerical modeling and critical geography to assess future climate conditions that occur in response to changes in Antarctic Ice Sheet melt as well as …

Residents' Perspectives Of Young, Street-Facing Trees: Three Cases From Legacy Cities With Active Tree Planting Initiatives, Alicia Coleman

Doctoral Dissertations

Organized tree planting initiatives are underway in cities across the world in order to expand tree canopy cover, combat environmental threats, and create more livable places for urban residents. Trees along and near city streets provide a number of services for residents; however, evidence from environmental design and landscape preference research suggests that the perceptual effect of large-statured, mature trees may differ from small-statured, young trees. This dissertation explored these differences in three studies based in communities with active tree planting initiatives. Chapter 2 compares tree preferences from a hypothetical tree planting initiative to preferences for trees in other settings …

Perceptions Of Historical Climate Change And Park Policy: The Impact On The Fremont Cottonwood In Zion National Park, Kathleen Kavarra Corr

Doctoral Dissertations

Despite its “natural” appearance and the Organic Act 1916 mandate for preservation of the natural environment in National Parks, the Virgin River as it flows through Zion National Park’s Zion Canyon was transformed through massive flood control re-engineering projects in the 1930s. The armoring of the river has had significant impacts on riparian vegetation, particularly on the stands of native Fremont Cottonwood trees that once filled the narrow valley. What was the motivation for this massive flood control project carried out in an arid region with less than 15 inches of rain per year? This dissertation explores the motivations which …

Monitoring Mammals At Multiple Scales: Case Studies From Carnivore Communities, Kadambari Devarajan

Doctoral Dissertations

Carnivores are distributed widely and threatened by habitat loss, poaching, climate change, and disease. They are considered integral to ecosystem function through their direct and indirect interactions with species at different trophic levels. Given the importance of carnivores, it is of high conservation priority to understand the processes driving carnivore assemblages in different systems. It is thus essential to determine the abiotic and biotic drivers of carnivore community composition at different spatial scales and address the following questions: (i) What factors influence carnivore community composition and diversity? (ii) How do the factors influencing carnivore communities vary across spatial and temporal …

Landslide Mapping And Susceptibility Assessment Of Chittagong Hilly Areas, Bangladesh, Yasin Wahid Rabby

Doctoral Dissertations

Landslides are natural phenomena in mountainous areas that cause damage to properties and death to people around the world. In Bangladesh, landslides have caused enormous economic loss and casualty in Chittagong Hilly Areas (CHA). In this dissertation, a landslide inventory of CHA was prepared using Google Earth and field mapping. Google Earth-based mapping helped in recording landslides in inaccessible areas like forests. In contrast, field mapping helped in mapping landslides in accessible areas like areas near road networks. For absence data sampling of landslide susceptibility mapping, this research proposed the Mahalanobis distance (MD) based absence data sampling and compared it …

Hazardous Weather And Human Response In The Southeastern United States, Daniel Burow

Doctoral Dissertations

Effectively mitigating the human costs of future hazardous weather events requires examining meteorological threats, their long-term patterns, and human response to these events. The southeastern United States is a region that has both a high climatological risk and a high societal vulnerability to many different meteorological hazards. In this dissertation, I study hazardous weather and human response in the Southeast through three different lenses: identifying uniquely simultaneous hazards posed by tropical cyclones, assessing precipitation and synoptic weather patterns on hazardous weather days, and examining patterns in intended response to tornado watches. I find that simultaneous and collocated tornado and flash …

Modeling Fire Observations, Ignition Sources, And Novel Fuels To Understand Human Impacts On Fire Regimes Across The U.S., Emily Fusco

Doctoral Dissertations

Fire is a natural, and necessary, component of many ecosystems. However, people are changing the spatial and temporal distribution of wildfires in the U.S. at great economic and ecological costs. My dissertation addresses the impacts of humans on U.S. fires both through the introduction of ignition sources and flammable grasses. Further, I evaluate fire datasets that are widely used to investigate these phenomena over large spatial and temporal scales. Finally, I create an aboveground carbon map that can be used to estimate the potential carbon loss consequences in western U.S. ecosystems most at risk to fire. My work shows that …

Effects Of Switchgrass Related Land-Use Changes On Aquatic Macroinvertebrates, Latha Malar Baskaran

Doctoral Dissertations

This research examines if switchgrass-based land-management practices have the potential to influence aquatic macroinvertebrates through changes in stream flow and water quality. The number of taxa in Ephemeroptera, Plecoptera, and Trichoptera orders (EPT taxa richness/EPT-TR) is analyzed as an aquatic macroinvertebrate bioindicator in the context of regional environmental effects, and changes in stream flow and water quality. This dissertation is structured as three manuscripts that link together to address the overall research question.

The first manuscript focuses on identifying regional environmental variables that influence EPT-TR across ecoregions in Tennessee. The influences of temperature, precipitation, geology, soil, stream flow and velocity …

Reconstructing Late Holocene Fire, Agriculture, And Climate From Sediment Records In Costa Rica And The Dominican Republic, Erik Nicholas Johanson

Doctoral Dissertations

We use multiple proxies from sediment cores to identify periods of climate stress during the late Holocene across the circum-Caribbean region and to determine how fire activity and signals of Pre-Columbian agriculture coincide with these arid periods. We examine evidence of aridity from stable carbon isotope ratios and shifts in elemental composition, along with pollen and microscopic charcoal, at Bao Bog in the highlands of Hispaniola. We infer two major periods of aridity (3600–2300 and 1040–850 cal yr BP), with the later period associated with the late phase of the Terminal Classic Drought. A third, less marked interval of aridity …

Using Spatial Analysis To Evaluate Fire Activity In A Pine Rockland Ecosystem, Big Pine Key, Florida, Usa, Lauren Ashley Stachowiak

Doctoral Dissertations

Pine rocklands are fire-prone ecosystems with limited spatial extent, and have experienced reduced area in the previous decades through habitat conversion and urbanization. The purpose of this dissertation research was to evaluate the historical range of variability of fire activity and spatial patterns of fires in a pine rockland ecosystem in the National Key Deer Refuge (NKDR) on Big Pine Key in the Lower Florida Keys. To investigate the temporal and spatial patterns in fire activity, I (1) evaluated the temporal patterns for fires in my study area in the NKDR, (2) analyzed differences in standard fire history metrics since …

Linking Soil Moisture And Carbon-Cycle Processes In Two Understudied Terrestrial Ecosystems: Ecuadorian Páramo Grasslands And Constructed Agricultural Wetlands, Julie Yvette Mcknight

Doctoral Dissertations

A better understanding of soil-water interactions and associated feedbacks in carbon-cycle processes is necessary for addressing knowledge gaps in the global carbon budget. This doctoral dissertation research investigated soil carbon-cycle processes in two ecosystems, Ecuadorian páramos and constructed agricultural wetlands, which are understudied in terrestrial carbon research. These sites represent ecosystems where land-use induced changes in soil moisture were expected to play an important role in soil carbon processes.

Soil carbon dioxide (CO₂) flux and extracellular enzyme (EE) activities were measured to assess changes in soil carbon processes in soil from four types of land use in Ecuadorian …

Geographic And Socioeconomic Risk Factors For Sporadic Cryptosdporidiosis And E. Coli Infection In East Tennessee, Ingrid Elizabeth Luffman

Doctoral Dissertations

This research examines risk factors for sporadic cryptosporidiosis and Escherichia coli (E. coli) O157 infection in East Tennessee, using case-control and retrospective ecological approaches. Multiple models and approaches are used to identify risk factors for the two diseases, and to examine the effect of scale on risk for disease in the individual and in the population. Risk factors examined are animal density, land use, geology, surface water impairment, poverty rate and availability of private water supply. The research objectives are, first, to identify risk factors for E. coli O157 and cryptosporidiosis in East Tennessee by relating disease data …

Fire And Forest History From Soil Charcoal In Yellow Pine And Mixed Hardwood-Pine Forests In The Southern Appalachian Mountains, U.S.A., Christopher Aaron Underwood

Doctoral Dissertations

The Holocene history and ecological role of fire in forested ecosystems in the southern Appalachians is incompletely known. Determining how often and when fire has affected forest communities requires us to think about fire over time scales that extend beyond those of written fire records. This research is the first to specifically address the spatio-temporal patterns of forest fires in southern Appalachian xeric forests using radiocarbon dating of taxonomically identified soil charcoal as the primary proxy. Forty-eight soil cores were recovered in eight sites established for a companion study of dendrochronological evidence of fire history. The eight sites were located …

Fire Regimes Of Lower-Elevation Forests In Great Smoky Mountains National Park, Tennessee, U.S.A., Lisa Battaile Laforest

Doctoral Dissertations

Disturbance is a natural part of any forest ecosystem. When disturbance regimes are altered, the forest stands will reflect those changes. Southern Appalachian xeric pine-oak woodlands are one forest type that has experienced such change, primarily in the form of fire suppression. The western side of Great Smoky Mountains National Park contains stands of large trees that escaped earlier intensive logging, show evidence of past fire, and provide an ideal setting for reconstructing stand histories. For three lower-elevation (ca. 500 m ASL) study sites, I used crossdated yellow pine tree-ring chronologies and records from cross-sections taken from living and dead …

Spatial Variation In Organic Carbon And Stable Isotope Composition Of Lake Sediments At Laguna Zoncho, Costa Rica, Zachary P Taylor

Doctoral Dissertations

Lake sediments are valuable paleoenvironmental archives that provide information on past climate and land-use change. Most lake sediment studies rely on a single core, usually recovered from the center of a lake, and do not consider spatial variability in the lake basin. My dissertation presents a spatially-explicit record of prehistoric agriculture from Laguna Zoncho, Costa Rica and evaluates spatial variability in lake sediment proxies based on a network of five sediment cores. Results extend earlier proxy analyses of a single core collected near the center of the lake, which documented prehistoric agriculture and forest clearance from 3000 to about 500 …