Paleoclimate archives have revealed abrupt climate events that are superimposed on more gradual climate changes throughout the last glacial and deglacial periods. The underlying causes of such rapid climate changes are still poorly understood, but the strong expression of these events in northern hemisphere records likely points to climatic mechanisms...
The goals of this dissertation are centered on understanding changes in Earth surface and climate systems through the use of geologic proxies as records of past changes in these systems. Specifically, this dissertation (1) establishes a new chronology for retreat of the Ross Sea sector of the West Antarctic Ice...
Burial Lake sediments from the Noatak Basin in the northwest Brooks Range of Arctic Alaska (68.43°N, 159.17°W, 21.5 m water depth) provide the oldest continuous lacustrine record of paleo-environmental change and paleomagnetic secular variation (PSV) in eastern Beringia. A precise radiocarbon chronology, determined through accelerator mass spectrometry (AMS) allows us...
African-born population is one of the fastest growing group in the United States. Very little is known about their socio-demographic characteristics, health behavior practices and long-term health. The purpose of this study was to examine hypertension prevalence, health behavior practices and the impact socio-demographic factors have on these outcomes among...
This dissertation presents the results of statistical analyses of large climate datasets from two time intervals – the 20th century instrumental record and the proxy record of the last deglaciation – in order to understand the forcings and mechanisms of past climate variability.
A longstanding question in climate dynamics concerns...
Fire regimes across the western United States have been altered due to past land management and changing land use. Mitigating increased risks of wildfire occurrence in landscapes such as central Oregon requires landscape level management from both governmental and private organizations. Non-industrial private forest (NIPF) owners manage a relatively small...
Wildfire management policy over the past century, which attempts to exclude fire from fire-adapted ecosystems, has led to a build-up of fuels across the western United States. As a result, current wildfires contain larger areas of high severity, high intensity burns than seen prior to the policy implementation. There are...
Wildfire in dry, frequent-fire forests is a pressing issue for natural resource managers, communities and politicians in the western United States. Area affected by wildfire has climbed steadily over the last twenty years and is expected to increase in the future. Recognition of the importance of both social and biophysical...
I measured responses of free-ranging Rocky Mountain elk (Cervus elaphus) to recreational disturbance at Starkey Experimental Forest and Range, Oregon from April to October, 2003 and 2004. Resting, feeding, and travel activities of 13 cow elk were recorded at 5-minute intervals using Actiwatch™ motion sensors. Elk were subjected to four...
Forest management in the face of fire risk is a challenging problem because fire spreads across a landscape and because its occurrence is unpredictable. Additionally, management must be adjusted over time as unpredictable fire events are realized. Land managers have some control over the vegetation conditions that facilitate fire spread,...