Thesis (M.S.)--Northwest Missouri State University, 2008. / The full text of the thesis is included in the pdf file. Title from title screen of full text.pdf file (viewed on July 25, 2008) Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 1998. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.A.I.S.)--Oregon State University, 1996. / Typescript (photocopy). Includes bibliographical references (leaves 191-211). Also available via the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 1986. / Typescript (photocopy). Includes bibliographical references (leaves 159-167). Also available online.

On May 18, 1980, the town of Othello, Washington was covered with volcanic ash from the Mount St. Helens eruption. Disaster research suggested that a natural disaster acted on impacted populations as a major stressor and could result in such stress-related symtoms/problems as anxiety, depression, alcohol abuse, family problems, etc. It was hypothesized that there would be an increase in the incidence of such symptoms/problems following the ashfall. Most previous research has relied on subjective accounts of victims, but data for this study came from selected objective indices such as mental health caseloads, welfare assistance grants, hospital admissions, police records, etc. Data were compared for a 12-month pre-disaster baseline, and a 7-month post-disaster period. Of the 34 indices examined, five showed significant post-disaster decreases, and nine failed to meet the criterion for significance. Twenty indices showed significant increases and these seemed to clearly support the hypothesis. Two rival hypotheses were explored as possible causal factors: local unemployment rates, and economic factors affecting agriculture. The disaster hypothesis fit the observed data more precisely and seemed most logical as a probably causal agent.

Mosses are some of the first colonizers to disturbed sites, yet their roles in early plant community structuring are not well understood. The primary succession zones of volcanoes provide opportunities to conduct natural experiments into how mosses contribute to early plant community formation, as well as how the unique environments found in such zones affect plant traits, particularly those associated with stress tolerance. Though plant community changes have been well-documented since Mount St. Helens (MSH) volcano erupted in 1980, the volcano's moss assemblages, their influence on other plants, and their potential roles in chemical-mediated competition and biogeochemical cycling have garnered little attention. Using a natural stress gradient from primary to secondary succession zones on MSH, and in control and nutrient manipulated test plots, I sought to elucidate how populations of three dominant moss species, Polytrichum juniperinum, Ceratodon purpureus, and Racomitrium canescens, respond to abiotic stress, as well as to provide life history and interaction data on establishment stages of these stress tolerant taxa. I first analyzed possible tradeoffs in survival strategies of four moss communities in test plots along an abiotic stress gradient. In P. juniperinum, seta specific density (mg/mm) increased significantly in response to nitrogen (N) addition. Differences in both vegetative and sexual reproductive morphological measurements were dependent on site and did not correlate with abiotic stress. In C. purpureus, the percentage of total spores germinated increased with N addition. Site dependent responses in nutrient allocation to vegetative and reproductive structures may be a result of phenotypic plasticity alone or may be a result of local adaptation. In mosses adapted to environmental stress, the allocation of nitrogen must be balanced between growth and survival. Efficient nitrogen uptake confers a competitive advantage if allocated to the higher dispersal of quickly germinating spores. Second, my results show the moss R. canescens may be able to inhibit the germination rate of co-occurring moss spores when spores were germinated in moss gametophyte infusions. R. canescens may also inhibit the germination of the co-occurring vascular plant Lupinus lepidus when seeds are germinated within intact moss patches. By uncovering chemical-mediated interactions between mosses on the germination and initial growth of neighboring mosses and vascular plants we can gain a better understanding of the mechanisms stress tolerant plants may use to limit resource competition. Such advantages offer insight into how mosses effectively colonize and affect primary succession landscapes.

Active seismicity and volcanism north of Washington state’s Mount St. Helens provide key ingredients for hydrothermal circulation at depth. This broad zone of seismicity defines the St. Helens Seismic Zone, which extends well north of the volcanic edifice below where several faults and associated fractures in outcrop record repeated slip, dilation, and alteration indicative of localized fluid flow. Candidate reservoir rocks for a geothermal system include marine metasediments overlain by extrusive volcanics. The colocation of elements comprising a geothermal system at this location is tested here by analysis of the structures potentially hosting a reservoir, their relationship to the modern stress state, and temperature logs to a depth of 250 m. Outcrop mapping and borehole image log analysis down to 244 m document highly fractured volcaniclastic deposits and basalt flows. Intervening ash layers truncate the vertical extent of most structures. However, large strike slip faults with well-developed fault cores and associated high fracture density cross ash layers; vein filling and alternation of the adjacent host rock in these faults suggest they act as vertically extensive flow paths. These faults and associated fractures record repeated slip, dilation, and healing by various dolomite, quartz, and hematite, as well as clay alteration, indicative of long-lived, localized fluid flow. In addition, where these rocks are altered by igneous intrusion, they host high fracture density that facilitated heat transfer evidenced by associated hydrothermal alteration. Breakouts in image logs indicate the azimuth of SHmax in the shear zone is broadly consistent with both the GPS plate convergence velocity field as well as seismically active strike slip faults and strike-slip faults mapped in outcrop and borehole image logs. However, the local orientation of SHmax varies by position relative to the edifice and in some cases with depth along the borehole making a simple regional average SHmax azimuth misleading. Boreholes within the seismic zone display a wider variety of fracture attitudes than those outside the shear zone, potentially promoting permeability. Temperature profiles in these wells all indicate isothermal conditions at average groundwater temperatures, consistent with rapidly flowing water localized within fractures. Together, these results indicate that the area north of Mount Saint Helens generates and maintains porosity and permeability suggesting that conditions necessary for a geothermal system are present, although as yet no modern heat source or hydrothermal circulation was detected at shallow depth. / Geology

Phytoplankton communities in fifteen lakes in the Mt. St. Helens area were surveyed to assess the abundance and species present. Eleven of the lakes were inside the blast zone of the 1980 eruption and four were located outside the blast zone as a comparison. The hypothesis is that lakes will cluster together based on the algal species present and that some algae will be correlated with certain environmental conditions. A cluster analysis was performed to determine if the lakes would group together based on algal abundance. There did not appear to be any distinct clustering among the study lakes, but this analysis did help to sort out some similarities of algal species present between lakes. It demonstrated that the lakes outside the blast zone were not functional as control lakes because they were very different from the blast-zone lakes. They had different assemblages of algae and their origin was so different from the blast-zone lakes that there was little overlap between them. The factor analysis was applied to determine the relationships between environmental variables and phytoplankton. The hypothesis is that certain algae are associated with each other and with identifiable environmental factors. Factor analysis should detect these patterns. The factors represent some condition in the environment but the analysis would be virtually meaningless unless these conditions can be recognized and the factors named. From the factor analysis alone, I could not name the factors but returned to the task after the canonical correlation analysis was performed. The canonical correlation analysis gave some clues to identify the environmental conditions that exert control on these algae. The most useful statistical technique used in this study was the canonical correlation analysis. This analysis is a useful tool in community ecology studies where species-environment relationships can be inferred from community composition and environmental data. The environmental data used was nutrient and light attenuation present at the time the phytoplankton samples were taken. From this analysis I summarized a list of algae and with what environmental conditions that they are associated. Trophic state categories were assigned to the lakes from a trophic state index based on phytoplankton biovolume.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references. / Microfiche. / xx, 252 leaves, bound ill. (some col.) 29 cm

Thesis (PhD)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Todd Feeley. Includes bibliographical references.