Graduation date: 1961

Relationships among the surface wind, horizontal synoptic-scale pressure gradient and topography are studied in the Willamette Valley in western Oregon. Terrain features alter the standard surface wind-pressure gradient relationship such that the angle between the surface wind and the surface geostrophic wind is most frequently 60°. In winter the surface flow is predominantly southerly and surface geostrophic flow varies from southerly to westerly. Little diurnal change occurs in the average surface wind, the average surface geostrophic wind and their relationship with each other because the air in the valley is generally stably stratified throughout the day. Partially in response to the northward extension of the subtropical anticyclone summertime surface winds and surface geostrophic winds are northerly, except during afternoon episodes of marine air invasion when surface winds are westerly. The pressure gradient is 88% less intense in summer but the ratio of the magnitudes of the surface wind and surface geostrophic wind, R, is 125% greater than in winter. However, a sharp summertime morning maximum in R of -0.67 is diminished by early afternoon as differential surface heating establishes a strong afternoon pressure gradient. When the surface geostrophic wind vector is cross-valley, the surface wind is still most frequently parallel to the valley and the surface geostrophic wind speed is largest and most variable. Because of the importance of terrain and meso-scale events, little correlation between the surface winds and synoptic-scale pressure gradient is found. / Graduation date: 1975

Graduation date: 1999

Rotating wheat with other crops is a common practice in the Willamette Valley of western Oregon. Depending upon previous crop and soil type, current N fertilizer recommendations for wheat in the Willamette Valley vary widely. Excessive fertilizer poses environmental risk, whereas lower N inputs than required by the crop represent economic losses to growers. Growers and their advisors face the challenge to minimize the environmental risk, and at the same time to maintain or increase economic returns. Questions are often raised concerning the efficient use of N fertilizer and accurately predicting the amount of N needed by wheat following different crops. The first study measured growth, N uptake and N use efficiency (NUE) of winter wheat grown after either a legume or oat for three years. In all three growing seasons, winter wheat showed higher biomass, N uptake and NUE when grown after a legume than after oat. The contribution of legume was evident before the wheat was fertilized in spring, indicating that legume N had mineralized in fall or winter. Contribution of soil N to wheat suggested that fertilizer N can be reduced by 44 kg N ha����� if a legume is grown previously. Nitrogen use efficiency estimated 50 to 70 days after N application by isotopic method (24 to 94%) was comparable with that estimated simply by difference (21 to 94%) at the same time. The second study predicted gross mineralization rates using analytical models. Comparable N mineralization was predicted by a model assuming remineralization and a model assuming no remineralization, suggesting that remineralization was negligible. In the spring, mineralization-immobilization turnover was at a lower pace than expected in both rotations. In two growing seasons, gross mineralization rates were higher where the previous crop was legume (0.37 to 0.74 kg����� ha����� day�����) as compared to where oat was grown previously (0.14 to 0.6 kg����� ha����� day). Negative net mineralization indicated that fertilizer N was immobilized in the oat-wheat rotation. The third study evaluated calibration and digestion techniques used to determine elemental concentration in grasses. Use of a dry ashed standard to calibrate the ICP spectrometer generated highly variable calibration curves and was not a viable calibration method. Good agreement was found between chemical and microwave digested standards. Dry ashing resulted in considerable S and Mn losses, whereas, perchloric acid digestion and microwave digestion showed similar results. Our study suggests that if routine analysis are to be performed for macro nutrients or involve trace level work, the best method is microwave digestion with chemical standard calibration of ICP spectrometer. / Graduation date: 1999

Graduation date: 1998

I monitored demography, movement, and reproductive behavior of gray-tailed voles, Microtus canicaudus, in experimental habitat patches with and without corridors. I tested the hypotheses that reproductive rate, juvenile recruitment, and population size and growth rate would be affected negatively by immigrants that were introduced to resident groups (+ male and + female treatments). I hypothesized that "strangers" would commit infanticide thus decreasing juvenile recruitment. Second, I determined if movement corridors facilitated dispersal among habitat patches, thus potentially increasing infanticide, but decreasing reproductive inhibition of opposite-sex relatives by allowing them to separate (corridor treatment). Experiments were conducted in 12 0.2 ha enclosures planted with alfalfa that was fragmented into four patches (each 156 m��) separated by 12.5 m of bare ground. Introduction of unfamiliar conspecifics did not adversely affect reproductive rate, juvenile recruitment, population size, density, or growth rate. Corridors facilitated dispersal movements with males moving more than did females; however, corridors did not result in an even distribution of animals in the four patches. Unconnected habitat patches resulted in female- rather than the typical male-biased dispersal and females dispersed at lower body mass than in controls. Males that did not disperse from their natal patch exhibited a slight delay in sexual maturation. I conclude that movement is deterred in patchy environments, enhanced with corridors, and differentially affects males and females. Behavioral factors that affect an individual's dispersal or reproductive pattern should be considered in landscape planning. / Graduation date: 1997

Graduation date: 1996

This thesis documents a period of ecological and cultural change on a Willamette Valley, Oregon landscape. In particular, this study examines the Peavy Arboretum area and the cultural changes that accompanied the transformation of the landscape from an oak savannah in the mid-nineteenth century to a dense Douglas-fir forest in the early twentieth century. Culturally, the inhabitants of this period included late-prehistoric native people, Euro-American based fur industry personnel, and Euro-American settlers. As a student of history and archaeology, I have used a combination of methods and sources for this study including surface surveys for cultural materials and features, archaeological excavations and analysis, and documented materials. Knowledge gained as a result of surveys and excavations are studied within the context of other Willamette Valley archaeology, and likewise, documented materials concerning this landscape and its historic features and people are compared against larger patterns in the history of the American West. Geographically, the study area was in a fortunate position to witness cultural events. Located along the edge of the foothills of the Willamette Valley, its many desirable features attracted both native people and the first white settlers. The study area was also located along a main route of travel that was used by natives, fur company personnel, travelers, and Euro-American settlers. The section of trail has been a part of regional travel routes known at different times as the Hudson's Bay Company Trail, the California Trail, the Southern Route (Scott-Applegate Trail), and the Territorial Road. The objective of this thesis was to see what kind of information could be retrieved for a given landscape using a variety of methods practiced in history and archaeology. I believe such a multi-disciplinary approach allowed me to be more flexible and open to all pertinent sources of information. This type of investigation also provided an example of the type of work that could be done professionally when determining the cultural significance of a property. My fascination with the study of landscapes and their cultural features was also influential in my selection of a thesis topic. / Graduation date: 1999

'Golden Delicious' winter squash (GDWS), Cucurbita maxima Duchesne, provides significant amounts of pollen (24 mg) and nectar (236 μl), but with a low reward of 14% nectar sugar. The quantity of nectar produced per GDWS flower differed between sites and floral sex. The GDWS male flowers had 25% higher sugar concentration than female flowers. There was no statistical difference in the percent of nectar sugars per flower between sites, but the interaction between site and floral sex was statistically significant for the amount of nectar and percent of nectar sugars. Pollen production per flower differed significantly between sites with the most productive site producing 27% more, and 45% more than the other sites. Pollination efficiency of honeybees and bumble bees was assessed with field cages (1.8x1.8x1.8 m). No significant differences were found except for the interaction between the bee treatment and year on number of fruit per cage. This significant difference reflects the increase in fruit number produced by honey bees in 1997. The effect of distance from honey bee hives on fruit and seed quality was tested, and found significant only for B- and C-seeds weight, which were both less in the plots farthest from the nearest group of honey bee hives. Placement of honey bee hives in fields of ≤120 ha appears not to be critical for adequate pollination of GDWS. Other pollinators (excluding honey bees) were frequent visitors to the squash flowers studied here - for example, Bombus spp., Megachilids, Halictids, etc. These other pollinators, mostly bumble bees, accounted for 3.55% of all bee visits. Honey bees visited proportionately more female flowers in the morning, and progressively switched to the more abundant male flowers in the afternoon. This bias differed by site and year. Bumble bees visited proportionally slightly more male GDWS flowers than did female flowers and did it in a similar rate throughout the day. From 15 minute observations each hour of individual female GDWS flower, we calculated that they received approximately 80 honey bee visits per day. / Graduation date: 2001

Volcanic tuffs and tuffaceous sediments are frequently associated with elevated As groundwater concentrations even though their bulk As contents (~ 5 mg kg-1; Savoie, 2013) are only marginally greater than the average crustal abundance of 4.8 mg g-1 (Rudnick & Gao, 2003). Thus, As mobilization must be facilitated by conditions particular to these rocks. Alkaline desorption, anionic competition, reactive glass dissolution, and reductive dissolution of iron oxides are proposed processes of As release from volcanic rocks. Geogenic As contamination of groundwater in the southern Willamette Valley in western Oregon has been well-documented since the early 1960s, and previous studies have identified the Little Butte Volcanics Series and Fisher and Eugene Formations as the source of As contamination. This study examines 19 samples from 10 units of ash flow tuffs and tuffaceous sediments within the Fisher Formation and Little Butte Volcanics Series, representing a range of weathering and devitrification, to determine conditions of mobilization and mineralogical constraints that control As release into solution. Leachate studies were conducted over a range of pH from 7 to 11, phosphate concentrations from 10 μM to 100 mM, and in time series from 4 to 196 hours. Results demonstrate that silicic volcanic tuffs are capable of mobilizing As in concentrations above regulatory limits at pH conditions produced naturally by the tuffs (pH 8-9) or with moderate concentrations of P (10-100 μM). Alteration products, e.g. zeolites and clays, appear to be the primary host phases for mobile As. Samples that do not contain these alteration products tend to produce concentrations of As well below regulatory limits and often below the instrument detection limits of this study. The type of alteration may influence As mobilization: tuffs containing more clays tend to mobilize As through surficial desorption, and tuffs containing more zeolites tend to mobilize As by dissolution or formation of colloids. Additionally, one volcaniclastic sample demonstrates that extremely elevated concentrations of As, up to 1000 μg/L are possible as a result of oxidative dissolution of As-bearing sulfide phases.