The analysis of marsh cores from the tidal zones of the Siuslaw, Umpqua, and Coos River systems on the south-central Oregon coast provides supporting evidence of coseismic subsidence resulting from megathrust earthquakes and reveals the landward extent of the zero-isobase. The analysis is based on lithostratigraphy, paleotidal indicators, microfossil paleotidal indicators, and radiocarbon age. Coseismic activity is further supported by the presence of anomalous thin sand layers present in certain cores. The analysis of diatom assemblages provides evidence of relative sea-level displacement on the order of 1 to 2 m. The historic quiescence of local synclinal structures in the Coos Bay area together with the evidence of prehistoric episodic burial of wetland sequences suggests that the activity of these structures is linked to megathrust releases. The distribution of cores containing non-episodically buried marshes and cores that show episodically buried wetlands within this area suggests that the landward extent of the zero-isobase is between 100 km and 120 km from the trench. The zero-isobase has a minimum width of 10 to 15 km. Radiocarbon dating of selected buried peat sequences yields an estimated recurrence interval on the order of 400 years. The apparent overlapping of the landward margin of both the upperplate deformation zone (fold and/or thrust fault belt) and the landward extent of the zero-isobase is interpreted to represent the landward limit of the locked zone. The earthquake magnitude is estimated to be 8.5 based on an arbitrary rupture length of 200 km and a locked zone width of 105 km. The identification of the zero-isobase on the southcentral Oregon coast is crucial to the prediction of regional coseismic subsidence and tsunami hazards, the testing of megathrust dislocation models, and the estimation of megathrust rupture areas and corresponding earthquake magnitudes in the Cascadia Margin.

For over 25 years organized groups of low-income families in Oregon have been gathering food that would otherwise go to waste and distributing this food among organization members. The purpose of this research study is to explore the potential for these organizations (gleaning groups) to contribute not only to food distribution, but also to the reduction of poverty through the development of human capital (acquiring knowledge and skills) and social capital (building relationships of trust and support) among participants in these organizations. Data was collected through participant observation at a regional food distribution agency and seven gleaning group sites, as well as interviews with 13 key informants working with gleaning organizations, and 19 volunteer members of gleaning organizations. The results of this study indicate that gleaning groups are contributing to the development of human and social capital by providing individuals with opportunities such as working closely with other gleaners, carrying out the administrative tasks of a non-profit organization and distributing food to shut-in or disabled "adoptee" members of these groups. In addition, this study shows that there are significant hindrances to human and social capital development within gleaning organizations including lack of control over the amount of food groups receive through the national food-banking network, deficiencies in volunteer participation and an emphasis on efficiency in carrying out group tasks. The author suggests incorporating social and human capital development into the stated purposes of gleaning organizations in an effort to stated purposes of gleaning organizations in an effort to intentionally remove barriers to, as well as encourage further investments in these forms of capital. / Graduation date: 2004

Carbon and energy fluxes were measured with the eddy covariance technique above two semi-arid ecosystems, ponderosa pine and juniper/sagebrush, located in central Oregon. The two ecosystems have low LAI and a very open canopy structure. The energy closure was ~70-80% at both ecosystems, equivalent to an imbalance of 150-250 W m⁻² on cloudless summer days, when net radiation (R[subscript n]) was ~600-700 W m⁻². The lack of closure cannot be explained by the uncertainty of an estimate of available energy due to a single R[subscript n] sensor location. At the more open juniper/sagebrush ecosystem, a numerical model showed that spatial variation in R[subscript n], even for large differences in surface radiation temperature and reflection coefficient between ecosystem components (soil and vegetation), is less than 10% of measured R[subscript n]. The uncertainty in R[subscript n] at the two-layered ponderosa pine ecosystem with patches of young and old-growth trees is expected to be smaller than at the juniper ecosystem. Net carbon exchange (NEE) at the pine site strongly depends on environmental factors effecting carbon assimilation (A[subscript c]) and ecosystem respiration (R[subscript e]). A more detailed analysis of the carbon budget showed a strong negative response of carbon uptake to large vapor pressure deficits (VPD), whereas water vapor exchange (LE) was less affected. At large VPD the vegetation maintains a sustainable water flow through the soil-plant system by stomatal control of transpiration. The stomatal closure leads to limitation in A[subscript c], but LE is subject to a positive feedback from higher evaporative demand. Annual NEE of the ponderosa pine forest (200-300 gC m⁻²) was in the mid-range of reported NEE of temperate forest ecosystems, though, unusually, much of the annual carbon gain occurred during the fall through spring, because the relatively mild winters allowed carbon assimilation to occur and R[subscript e] rates were low. The information gathered at our ponderosa pine site during two years with contrasting climate suggests that the carbon uptake of the ponderosa pine ecosystem will be more sensitive to global climate change than the water vapor exchange. / Graduation date: 2000

The Senior Farmers' Market Nutrition Program (SFMNP), piloted in Oregon in 2001, provided $100 worth of vouchers (aka coupons) to low-income seniors to buy fresh local produce from farmers at farmers' markets and roadside stands. Presented in a political ecology framework, this research integrated the perspectives of beneficiaries and their communities into a program evaluation. Convenience interviews of participants at farmers' markets around Oregon revealed significant economic, social and nutritional benefits resulting from the program. Findings also revealed areas of contention for some seniors: produce prices, transportation barriers, and lack of awareness of local agriculture. Reimbursement delays, policing of coupon-users and lack of information caused frustrations for farmers. Generally, farmers were appreciative of seniors as customers, and of the program for enabling farmers and their market to perform a social good; strengthening the community-building role of the farmers' market, providing a social activity for seniors and their support network, creating new relationships between the community and farmers, and enabling seniors to participate in the market experience and farmers to provide fresh produce that enhanced seniors' nutritional intake. Overall, SFMNP achieved its objectives in supporting low-income seniors, farmers and farm-direct marketing, and was an appealing program for seniors and farmers. / Graduation date: 2004

Yellow starthistle (Centaurea solstitialis L.) is an introduced Asteraceae that has become established on 10 million acres in the Pacific Northwest and California. This weed functions as an annual or short-lived perennial and depends on seeds for reproduction. Strategies of control that reduce plant fitness or lower seed production or viability may help limit the rate of spread of yellow starthistle. Previous work has shown that grazing and mowing can influence seed production. This study tested the hypothesis that proper timing and frequency of defoliation can reduce the number and viability of seeds produced. The study was conducted in Umatilla County, Oregon using a randomized block design with 4 replications of each of 4 defoliation treatments: (1) single defoliation at the bolting stage; (2) single defoliation at the bud stage; (3) two defoliations, once at the bolting stage and again at the bud stage; (4) non-defoliated control. Each of 4 blocks consisted of a 12 x 12 m area, with 16 plots measuring 3 x 3 m. Plants were defoliated at ground level using a gas-powered string-type mower. Response measurements were collected at the end of the growing season (September) following potential regrowth and included: (1) number of seedheads per plant; (2) number of seeds per seedhead; (3) number of seeds per plant; (4) number of seeds m⁻², (5) seed viability (% germination rates). Supporting measurements included: seedhead diameter; plant height, number of branches per plant; pre-dawn xylem pressure; soil moisture; and documentation of 5 biological control insect species. A single defoliation at bolting resulted in fewer seeds per seedhead, and fewer seeds per plant than non-defoliated controls. A single defoliation at the floral bud stage or repeated defoliation (bolting and again at the bud stage) resulted in equally fewer seeds per plant and fewer seeds m⁻² compared to non-defoliated controls. There was no statistical difference in percent germination of seeds among treatments. Defoliation had no effect on the infestation rates of seedheads by biological control insects. A second study examined nutrient content of yellow starthistle during 6 phenological stages from sites in Union, Baker and Umatilla Counties, Oregon during each of 2 years. Acid detergent fiber, lignin, cellulose and neutral detergent fiber contents increased through phenological development. Crude protein ranged from 16.7 to 5.0%. In Vitro dry matter digestibility ranged from 84.8% to 57.0%. Mineral nutrients P, K, CA, Mg, Mn, Fe, Cu, Zn, and Na were analyzed and determined to be adequate for maintenance needs of ewes. / Graduation date: 2002

The sudden oak death pathogen, Phytophthora ramorum, is present in southwestern Oregon, and while an eradication effort is underway, the potential impact of the polyphagous pathogen on surrounding vegetation is unknown. Plant communities in the area are substantially different from those affected in California, although tanoak (Lithocarpus densiflorus), evergreen huckleberry (Vaccinium ovatum) and Pacific rhododendron (Rhododendron macrophyllum) are hosts found in both areas. Other species are likely to be susceptible to the pathogen. Detached leaf and whole plant assays were used to test species commonly associated with tanoak, as well as three rare or endemic ericaceous species of the western Siskiyou Mountains and their associated taxa. Leaves and plants were challenged with zoospore suspensions that were capable of generating symptoms in the known hosts tanoak and evergreen huckleberry. Most (78%) of the previously unchallenged species developed necrotic lesions in detached leaf assays although severity (% leaf area necrotic) was variable. All three of the ericaceous species of conservation concern: Arctostaphylos hispidula, Kalmiopsis leachiana, and Leucothoe davisiae were susceptible in detached leaf assays. Factors important in determining whether or not these species will become infected in their native habitat are discussed. / Graduation date: 2004

Biology of Scaptomyza apicalis Hardy (Diptera: Drosophilidae) was studied in relation to its host, meadowfoam, Limnanthes alba, a recent oil seed crop grown in the Willamette Valley, Oregon. Populations of flies and larvae were monitored weekly over three consecutive crop-years beginning in 1996. Yellow sticky traps gave relative population estimates of adults. Absolute estimates of larval populations were derived using Berlese funnels to extract immatures from whole plant samples. Weather and crop phenology are key factors in population regulation. Meadowfoams, Limnanthes species, were the only observed hosts for S. apicalis in this study. This has four to five overlapping generations per year. Adults of a small founder population colonize commercial fields coincident with fall rains and seedling emergence. Females deposit eggs in or on plant tissue. Larvae mine leaves and stems. They also bore into crown tissue and flower buds later in the season. Second generation flies arising from the larvae of the founder population first appear in late winter. Successive generations peak during the rapid vegetative growth stage of meadowfoam (mid-April). A steady decline in adult and larval numbers occurs as daily temperatures rise and plants develop flower buds. Last flies are detected in early July when meadowfoam is harvested. Temperatures below 0�� Celsius during December were a key mortality factor for S. apicalis in 1998. Three often major weather components analyzed, accounted for up to 60 percent of the trap count variability. These components were temperature, solar radiation and relative humidity. S. apicalis larvae fed only on plants within the Limnanthes in feeding studies. They accepted nine native meadowfoams but with varying survival rates. The commercial meadowfoam cultivar, Floral, was the most suitable larval host. An increase in supplemental nitrogen fertilizer rates generally resulted in increased infestations of S. apicalis and decreased seed yields. / Graduation date: 2001

The diverse lichen flora of the Pacific Northwest is being impacted by population growth and by forest management practices. Accumulating information about our lichen flora will improve our conservation strategies. This dissertation first collects information to improve our understanding of how lichen communities vary among forests of differing structure, and across the western Oregon landscape. It then proposes a method to predict species occurrence in unsampled sites by utilizing the information on forest characters and environmental gradients at sampled sites. Macrolichen communities sampled in coniferous forests revealed that old-growth stands (>200 yrs old) harbored communities that differed from those in young forests (50-110 yrs old). Even more atypical communities occurred in macrolichen hotspots, which were primarily in riparian zones. Many macrolichen species were associated with these hotspots, including numerous nitrogen-fixing cyanolichens. Macrolichen species associated with old-growth forested plots included the nitrogen-fixing lichen Lobaria oregana and several forage-providing alectorioid lichens. The presence of remnant old trees apparently increased the occurrence of old-growth associates in young stands. The calicioids, a group of microlichens investigated only in the Cascades, had a strong association with old growth forest and remnant trees. Diversity of calicioids may also be increased by legacy structures such as old snags and wolf trees. These structures increase continuity between current and previous stands. Macrolichen communities varied between the Coast and Cascade Mountain Ranges, following climatic gradients, particularly annual precipitation. Successional patterns in macrolichen communities appeared to differ between the mountain ranges. The modeling method proposed for using habitat associations to predict occurrence has several advantages over common modeling methods, such as regression. The method is simple, avoids parametric assumptions, provides easy updating of models as additional sites are sampled, and automatically accounts for interactions among predictor variables. It can be linked with GIS data and software to map estimated probability of occurrence across landscapes. The data on calicioids from the Cascades, supplemented with additional stand inventories, were used to test and demonstrate the modeling method. / Graduation date: 2001

Winter wheat is commonly grown in dryland cropping systems in the Pacific Northwest region of semi-arid eastern Oregon. For agronomic, economic, and environmental reasons, it is important to understand the long-term sustainability of such dryland systems. The objective of this study was to evaluate the long-term effects of tillage, nitrogen (N), soil depth, and the influence of precipitation on wheat yields in dry land cropping systems of eastern Oregon. Data were taken from the Tillage/Fertility or "Balenger" experiment, which was established in 1940 by a Soil Conservation employee, and is one of the oldest replicated research experiments in the western United States. The experiment consisted of a winter wheat-summer fallow rotation arranged in a randomized block design with three replications. The main plot consisted of three primary tillage treatments (moldboard plow, offset disk, and subsurface sweep) and subplots consisted of six nitrogen treatments that changed over time and most recently ranged from 0 to 180 kg ha�����. Soil depth of individual plots ranged from 1.2- to 3.0-m. The study was divided into four main time periods (1940-1951, 1952-1961, 1962-1987, and 1988-1997) within which experimental treatments were consistently maintained. The moldboard plow tillage treatment significantly increased yields by more than 300 kg ha����� over the subsurface sweep tillage treatment in all four time periods. Yields with the moldboard plow system were significantly higher than with the offset disk system in time periods 3 and 4. The same trend was evident for mean yield in time periods 1 and 2, but differences were not statistically significant. In time periods 1, 2, and 3, mean yields were higher with the offset disk tillage treatment than the subsurface sweep tillage system, although the differences were not statistically significant. In time period 4, mean yield was higher for the subsurface sweep system than the offset disk treatment, but differences were not statistically significantly. The optimum amount of N for winter wheat differed from year to year, within, and between experiment periods. This was apparently in response to rainfall patterns and improved management factors, specifically more N responsive semi-dwarf varieties. For time period 1, the maximum fertilizer rate was 11.2 kg N ha�����, which tended to produce higher mean grain yields than an application rate of than 0 kg N ha�����, regardless of the quantity or distribution of precipitation. For time period 2, the maximum fertilizer rate was 33.7 kg N ha�����, which produced significantly higher grain yields than an application rate of than 0 kg N ha�����, regardless of the quantity or distribution of precipitation. For time period 3 (1962-1987), which had below-normal annual and growing season precipitation, yield increased with the addition of 45 kg N ha�����. For time period 4 (1988- 1997), which had above-normal annual and growing season precipitation, yield increased with the addition of 90 kg N ha�����. Yield increases at greater rates of N were insignificant. For time periods 3 and 4, maximum mean yield was obtained at an application rate of 135 kg N ha�����. The response of wheat yield to N during dry years was greater for deep (> 2.8 m) soils than for shallow soils. In addition to amount, rainfall distribution during the winter (October to March) and growing (April to June) season significantly affected yield. Results demonstrate the importance of rainfall and nitrogen to winter wheat production in eastern Oregon, and that the most environmentally sound tillage systems are not necessarily the most profitable from farmers' point of view. / Graduation date: 2000

This exploratory study examined whether temperament, home environment, and family stress impact the amount of prosocial behavior displayed by pre-school age low-income children and examined how much of an impact each factor has. Each factor was explored in depth along sub-scale dimensions including, (1) self-regulatory temperament, negative reactive temperament, and positive reactive temperament, (2) physical environment, emotional environment, and learning environment, and (3) family stress due to financial difficulties, interpersonal tension, and child problems. This study applied a combination microsystem, mesosystem, exosystem, and macrosystem person-process-context model to explore the role these factors played. Subjects were 35 low-income pre-school age children who were enrolled in the Oregon Head Start Pre-kindergarten Program at Oregon State University. The Children's Behavior Questionnaire: Short Form, the Early Childhood Home Inventory, the Family Events Checklist, and the Modified Prosocial Behavior Questionnaire were used to obtain information about the relationship between the factors and prosocial behavior. Results indicated that the physical aspects of the home environment tended to positively contribute to the production of prosocial behavior and that family stress due to financial difficulties tended to negatively contribute to the production of prosocial behavior by low-income pre-school age children. This study did not establish that temperament was significantly related to prosocial behavior. These results have implications for those who are responsible for shaping children's behavior, such as teachers, parents, and home visitors by providing specific areas of focus for impacting behavior. These findings also support programs such as the Oregon Head Start Pre-kindergarten Program because it provides a venue through which impacts can be made. / Graduation date: 2000