Thesis (M.S.)--Oregon State University, 1983. / Typescript (photocopy). Includes bibliographical references (leaves 41-44). Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 1972. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1984. / Typescript (photocopy). Includes bibliographical references (leaves 89-94). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1984. / Typescript (photocopy). Includes bibliographical references (leaves 56-59). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1984. / Typescript (photocopy). Includes bibliographical references (leaves 66-71). Also available on the World Wide Web.

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Delphis F. Levia, Dept. of Geography. Includes bibliographical references.

Episodes of stream acidification are suspected to be the primary cause of the extirpation of native southern brook trout (Salvelinus fontinalis) from six headwater streams in the Great Smoky Mountains National Park (GRSM). During periods of increased flow from storm events, stream pH can drop below 5.0 (minimum of 4.0) for 2-days or longer. To provide evidence that native brook trout are impacted by stream acidification, in situ bioassay experiments were conducted. Changes in stream water chemistry and brook trout physiology were determined during a 36-hour acidic episode at three remote headwater stream sites in the Middle Prong of the Little Pigeon River watershed. Conductivity, pH, turbidity, stage height and temperature were monitored continuously; and water samples were collected for laboratory analyses (metals, cations, anions, ANC). Native brook trout were put in cages at the three sites and fish were sampled before and after the acid storm event. Physiological stress in brook trout was assessed by measuring whole-body sodium in individual fish sampled before and after the stormflow, and evaluating whole-body sodium loss as a response to acid conditions. The pH decreased at all three sites during the acidic episode. Stream pH dropped to approximately 5.0 at two sites and 4.66 at the third site. Prior to the storm, there was no difference in the whole-body sodium concentrations in trout between the three sites. Following the storm event, in trout from the site that experienced the lowest pH, whole-body sodium levels were reduced significantly relative to a) the pre-storm condition and b) trout from the other sites. Results demonstrate that stream acidification can negatively affect native southern brook trout physiology in the GRSM under actual field conditions. Trout lose the ability to regulate critical blood ions, as exemplified by a loss of whole-body sodium, when stream pH was less than 5.0 for 20 hours. Loss of sodium is an important indication of physiological stress in fish exposed to acid waters. This observation supports the hypothesis that episodic acidification of streams could be limiting native brook trout from occupying headwater streams in the GRSM.

Microstegium vimineum is a non-native invasive plant species classified as an annual, shade-tolerant C4 grass. There is limited research regarding variables affecting the spread of M. vimineum. Two studies were conducted to investigate the spread of M. vimineum. A field study was undertaken in 2009 to determine how M. vimineum spreads in relation to litter disturbance. In 2010, a greenhouse study was conducted to determine the impact light has on M. vimineum aboveground biomass, height growth, and photosynthetic efficiency. The field study consisted of three treatments, Undisturbed (Control), Stirring, and Removal of leaf litter, employed along the boundary of existing M. vimineum populations in ½-meter by 2-meter plots. Distance of spread from the existing population and percent cover were documented for one growing season. Plants were counted at the end of the study. Neither stirring nor removal of leaf litter had a significant impact on spread rate, percent cover, or the number of plants in a given treatment suggesting pre-growing season leaf litter disturbance does not influence M. vimineum spread, percent cover, or number of plants. The greenhouse study consisted of growing M. vimineum under four light treatments: 100, 70, 45, and 20 percent of full light. Heights were measured weekly while minimum, maximum, and variable fluorescence emission, non-photochemical and photochemical quenching, and maximum quantum yield of Photosystem II photochemistry (QYmax) were measured every 10 days. Aboveground biomass accumulation was calculated at the end of the study. Results indicate that M. viminuem aboveground biomass accumulation is highest in 70 percent to 100 percent light while photosynthetic efficiency is highest between 45 percent and 70 percent light. This research indicates that M. vimineum does not spread appreciably at low light levels (closed canopies) in areas with litter disturbances that do not change the light regime. M. vimineum has greater aboveground biomass and photosynthetic efficiencies at higher levels of light. Thus, forest disturbances that result in more light reaching the ground may influence the spread of M. vimineum by creating a more favorable environment.

Thesis (M.S.)--Oregon State University, 1981. / Typescript (photocopy). Includes bibliographical references (leaves 125-132). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1981. / Typescript (photocopy). Includes bibliographical references (leaves 26-29). Also available on the World Wide Web.