Knowledge of old-growth Juniperus occidentalis woodlands, which occur in central and eastern Oregon, is limited. Wise management of these woodlands necessitates a better understanding of the community ecology. The community structure of woodlands at seven sites in three areas of central Oregon was studied. Measurements taken at nine plots per site included tree density, canopy cover, heights, diameters, and canopy areas; cover of each understory species and other ground covers; density of shrubs by species and condition; density of woody debris as downed pieces and standing dead trees; and topographic and soil parameters. Tree cores were taken for aging, although heartwood rot is pervasive in older trees. Factors of interest included cover and richness in all vegetative layers, variability within and between sites, and comparison of J. occidentalis woodlands to other old-growth communities. J. occidentalis woodlands were found to have a minimum of 80 trees over 200 years old per hectare, canopy cover of 10-35%, and understory cover of less than 20%. Woody detritus was primarily retained aloft and decomposed by weathering. Tree morphology was highly variable, but decadence was common. Outward physical attributes did not appear to be reliable predictors of tree age. Shrub cover was strongly correlated (r��=0.66) with the combination of elevation, ground cover by rock, and clay content of the soil. Perennial grass cover increased with elevation and the sand-sized soil fraction (r��=0.46). Understory cover, dominated by perennial grass, showed a weaker correlation with the same parameters (r��=0.20). Other significant findings included correlation of juniper cover with elevation, sand. and heat load (r��=0.38). Tree cover was found to increase by almost 1% for each 1% increase in sand content of the soil and by almost 8% for each 100m increase in elevation, while heat load, based on aspect. had a smaller effect. Plots grouped strongly by area. suggesting that there is a stronger influence of area than site on community composition for most of the sites and that differences between areas overwhelm the differences within areas. / Graduation date: 1999

Graduation date: 1994

A trial was conducted May 1 to September 4, 1989 at the Eastern Oregon Agricultural Research Center (EOARC) Burns, OR to examine the effects of strip or continuous grazing management on the diet and performance of steers grazing native flood meadows. The objective was to determine if strip grazing would be a more efficient means of grazing management than continuous grazing. The experiment was designed to test diet quality, botanical composition of the diet, daily dry matter (DM) intake and performance of yearling steers. Eighty yearling steers weighing 253±17 kg were selected from cattle at the Squaw Butte Experiment Station. The experimental design was a randomized complete block, with blocking based on past forage production. Treatments were continuous or strip grazing. A representative meadow of approximately 22.4 ha was divided into four equal pastures. Continuous grazing steers had access to 5.6 ha pastures for the duration of the study. Animals on strip grazing were confined to an area that was estimated to provide 5-7 days of forage using New Zealand portable electric fencing. Strip sizes were predetermined based on standing forage crop. Steers were not allowed to graze more than 7 days in any one strip. Diet quality was estimated from bi-weekly esophageal samples. Extrusa was collected from 4 esophageal fistulated steers per treatment on two consecutive days. Collections were timed to coincide with the mid point of the strip being currently grazed. Samples were pooled by collection dates and analyzed for CP and IVOMD. Dietary OM intake was estimated from biweekly, 24 hr total fecal collections starting the day following esophageal collections. Total DM fecal output from 6 fecal collection steers per treatment was corrected with the %IVOMD to predict actual DM intake. Diet botanical composition was estimated by microhistological examination of fecal sub-samples. Animal weight gains were recorded bi-weekly. Experimental animals grazed together at all times during the trial. Initial stocking densities were 2.0 AU/ha in each treatment pasture. Steers were counted as .56 AU with 20 steers grazing 5.6 ha pastures. The average strip size over the trial was .46 ha; and depending upon standing crop of forage, ranged from .23-1.15 ha. Record moisture from snowmelt and rainfall resulted in greater than expected standing crop of forage. This growth resulted in under stocking of both treatment pastures. A 1.08 ha block was removed as hay from the higher forage producing strip treatment block to adjust for over abundant forage. This resulted in a total mean strip grazed area of 4.37 ha or 22% less than continuous grazing. Actual grazing density means over the summer were 2.6 AU/ha for continuous and 3.15 AU/ha for the strip treatment. Available forage was determined from clipped plots on a DM basis and expressed as herbage allowance at a given point in time. Herbage allowance for steers in continuous grazed pastures ranged from 405-1153 kg/AU when measured at bi-weekly intervals and 68-186 kg/AU for strip grazed steers when estimated at the beginning of each strip. Grazing pressure was higher for strip grazed steers (.10 AU/kg) compared to continuous (.02 AU/kg). Diet quality declined significantly over the summer (P<.01). Analysis for CP in steer diets provided values of 13.9 vs 10.9% for continuous and strip treatments, respectively. However, this difference was not significant (P=.14). Digestibility analysis suggested that forage in continuous diets tended (P=.07) to have higher IVOMD than strip diets (64.6 vs 60.7%), respectively. Daily herbage intake was similar (P=.42) for both treatments when expressed as a percentage of body weight. Diet botanical composition was positively affected by the type of management system. The amount of the major grass species, meadow foxtail (Alopecurus pratensjs), was increased (P=.05) 39% in the diet of strip grazing steers. Differences were noted in the amounts of other, less frequently occurring grass species. The total amount of grass tended (P=.06) to be higher in strip diets (49% vs 35% for continuous). Rushes (Juncus spp.) and sedges (Carex spp.) contributed a similar percentage to the diets of both treatments. Forbs comprised less than .5% of the overall diet of both strip and continuous steers. Individual animal performance tended (P=.09) to be higher under continuous grazing management. The ADG was 1.16 and .77 kg for steers in continuous and strip grazing, respectively. However, total animal production per hectare grazed area (26.14 vs 22.13 kg/hd) was not considered different (P=.17). / Graduation date: 1991

Ranchers and resource managers have become concerned about the role and spread of Cardaria draba (L.) Desv. (whitetop) in the sagebrush steppe of Northeastern Oregon. This area is an important natural resource for livestock production and big game winter range. An area near Keating, Oregon was selected to study the influence of environmental conditions on whitetop seed germination, mode of spread and species displacement by whitetop. Whitetop seeds were placed in the field at four different topographical positions (toe slope, mid-slope, north slope and south slope) and placed at three different locations in the soil profile (0, 1, and 3 cm). Seed placed on the toe slope position at 0 cm had the greatest germination. At the south aspect greater germination occurred at lower soil profile locations. Increases in whitetop populations were evaluated by establishing permanent transects in two locations in the study area. Whitetop shoot density increased during the three year study. Whitetop density increase was restricted to previously infested plots and was due to vegetative reproduction. In whitetop infested areas, crested wheatgrass density was less than in non-infested areas. Whitetop germination at different topographical positions was apparently related to moisture conditions. Once established, whitetop populations increase through vegetative reproduction. This phenomenon is reflected in a reduction of crested wheatgrass density and production as the level of whitetop infestation increases. / Graduation date: 1992

Research was conducted near the Starkey Experimental Forest and Range in northeastern Oregon. Effects of defoliating bluebunch wheatgrass (Agropyron spicatum (Pursh) Scribn. and Smith) to increase the quality of regrowth available on elk (Cervus elaphus nelsoni) winter range were studied from 1988 through 1990. Clipping treatments were implemented to condition the forage regrowth. Treatments were no defoliation, spring defoliation (7.6 cm stubble height) in June, and fall defoliation (7.6 cm stubble height) in September. Percent calcium, phosphorus, in vitro dry matter digestibility (IVDMD), and available forage (kg/ha DM) of regrowth present on control, spring defoliated, and fall defoliated plots were determined in November and April of both years. Conditioned forage that was again defoliated in the winter was also analyzed for nutrient quality and available forage. Spring conditioning did not affect (p > 0.05) the forage in percent calcium, phosphorus, or available forage, and only slightly increased the IVDMD, when compared to the control in November. In November, the control and spring conditioned forages were deficient in meeting elk requirements for phosphorus, and contained wide calcium to phosphorus ratios. The forages were below 50% IVDMD, and digestible energy levels were below animal requirements in year 1, indicating that spring conditioning did not have an effect on the quality of winter range forage. Defoliation in the vegetative phenology stage allowed the regrowth to complete the growing season similarly as undefoliated plants. Fall conditioning significantly increased the percent phosphorus and IVDMD, while decreasing the available forage compared to the control and spring conditioned forage in November. Fall conditioned forage exceeded elk requirements in both calcium and phosphorus. The calcium to phosphorus ratio was near the optimum absorption range. Digestibility was high, and digestible energy levels were above animal requirements for both years. Fall conditioning however, may create a severe deficit of forage if regrowth is not achieved. In April, there were no differences among treatments in percent calcium, phosphorus, or available forage. Forage from all treatments exceeded elk requirements in calcium and phosphorus, and the calcium to phosphorus ratio would allow optimum absorption of both minerals. Digestibility was high for forage from all treatments. This indicated that the previous years defoliation did not effect forage quality the following spring. Conditioned forage that was again defoliated in the winter was not different in percent calcium or phosphorus when compared to the control in April. Depending on the year and conditioning treatment, there were statistically significant differences in IVDMD and available forage between the control and the winter defoliated samples in April. Conditioned forage that was not defoliated in the winter (April (U)) and winter defoliated samples (April (W)) were comparable in forage quality and available forage in April, though statistical differences were calculated for the spring conditioned samples in year 1, and fall conditioned samples in year 2. / Graduation date: 1992

The semi-arid regions of the Pacific Northwest are characterized by a high degree of annual temperature and precipitation variation. As a result of this climatic variation, dryland nitrogen fertilizer trials on fallow- ,wheat rotations typically demonstrate a variable response. Wheat growers in the area must not only cope with this climatic variation and its sundry effects upon their livelihood, they must also make decisions regarding the future level of anticipated climatic variation. The specific objectives were to: 1) develop a climatically responsive yield potential prediction model for soft white winter wheat from historical data at the Sherman Branch Experiment Station (Moro, OR); 2) modify this model for use on commercial fields; 3) field simulate five fallow-crop precipitation patterns characteristic of the variation found in the Sherman county area of eastern Oregon in order to test the yield potential model: 4) examine the effects of precipitation variation on nitrogen fertilizer responses, moisture storage and depletion and nitrogen mineralization; and 5) establish a quantitative relationship between precipitation/ soil moisture and nitrate accumulation in both the fallow and crop seasons. Two interacting regression models were developed to estimate grain yield levels in the 250-350 mm precipitation zone of eastern Oregon. The first model estimates yield potential from monthly precipitation and temperature values. The second model estimates the percent grain reduction due to delayed crop emergence. The grain yield model was adapted to commercial fields using a Productivity Index factor (PI). The PI is a measure of the productivity of other locations in relation to the Sherman Branch Experiment Station, using water-use-efficiency (WUE) as the basis of comparison. The field simulation of five fallow-crop precipitation patterns demonstrated that the maximum grain yield response occurred at 40 kg N (soil + fertilizer)/metric ton. The grain yield model demonstrated a 15% level of accuracy on a commercial field basis in both field trials and a survey of past production levels (1972-1980). It was hypothesized that the distribution of precipitation in the fallow and crop periods had an effect on both the amount and distribution of stored soil moisture. The field simulation demonstrated that more soil moisture was stored at the 90-240 cm depths by the patterns with more fallow season precipitation when measured in March of the crop year. Soil moisture storage and storage efficiencies fluctuated throughout the fallow and crop periods. At the cessation of the winter precipitation season in both the fallow and crop periods (March), the storage efficiency was highest when low levels of precipitation occurred. At this point in time, the mean crop period storage efficiency was 10% below the mean fallow period storage efficiency (34 and 44%, respectively) in both simulation studies. Soil moisture, temperature and immobilization requirements of crop residues interact to affect the net amount of nitrogen mineralization. The mineralization model proposed by Stanford and Smith (1972) was tested under field conditions. When the nitrogen immobilization requirement of the crop residues was included, the actual and predicted values were in agreement at the close of the 1978 fallow period. A nitrogen deficit was predicted at the 0-30 cm depth at the close of the 1980 fallow; however, the actual levels indicated a net accumulation of nitrate-nitrogen. Crop season mineralization, inferred from Mitscherlick and a-value extrapolations, in 1979 demonstrated that there was a decreasing amount of net mineralization during the crop season with increasing amounts of both fallow and crop season precipitation. Crop season mineralization in 1980 indicated that there was no net accumulation of nitrogen, rather a tie-up of 14 kg N/ha. This result reflects both the unsatisfied immobilization requirement predicted for the 1979 fallow season and crop season denitrification. / Graduation date: 1981

Museums and tourism have had a long and interrelated history. In this paper this relationship is reviewed in general, and the contemporary issues common to them both in the 1990's are discussed. This relationship is also explored in the context of the Oregon Coastal Zone. Two projects set on the Oregon Coast, involving museums, tourism and other organizations, the Bandon Community Archaeology project and the Lincoln County Interpretation project, are presented as alternatives to existing tourism opportunities. Both projects provide an alternative type of tourist experience where education and interpretation are the primary vehicles for creating benefits not only to tourists, but to the host community as well. These benefits may reduce possible negative impacts from tourism. / Graduation date: 1991

Not available / text

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 56-62). Also available on the World Wide Web.

The West Tidewater earthflow, one of the largest in Oregon's history, occurred in December of 1994. The earthflow is located approximately 15 km north of Jewel, Oregon near the summit ofthe Northern Oregon Coast Range Mountains. The earthflow is 900 m long and 250 m wide, giving it a surface area of 9 ha, or 22 acres. Volume is 3.5 million m3. The earthflow occurred in low strength, well-bedded, tuffaceous, carbonaceous, micaceous, clay-rich mudstone, and very fine-grained, feldspathic, clay-rich siltstone of the lower Miocene age Northrup Creek Formation. The soil clay fractions contain up to 90% smectite with indications ofhalloysite. This earthflow is a reactivation ofa 650-year-old landslide (C-14 dating of uncovered buried trees). The failure mode is examined using a Janbu slope analysis and includes double wedge failure near the headscarp. High soil pore water pressure is one of the major causes of this slope failure. Rainfall levels for October, November, and December of 1994 were twice the previous five-year average. Present day groundwater level within the basin is less than one meter below ground surface. The earthflow is partially controlled by two faults of regional extent that dissect the basin near the headscarp in NW-SE and NE-SW directions. The Inceptisol soils in the basin remain moist below 20 cm year around. Soil in the basin may have been further weakened due to loss of root strength following timber harvest on the site in 1991. Soil liquid limits range from 42% to 95%, with PI values ranging from 2% to 77%. Soil clay content ranges between 18% and 30%. Direct shear tests on the mudstone and siltstone bedrock in both drained and undrained conditions produced internal friction angles of 14-18°, with cohesion values of 4 - 8 kPa. Back calculation of study area soil strength using the modified Bishop method results in a residual friction angle of 20.7°. The failure mode ofthe earthflow is from the headscarp downward and is modeled using Janbu methods. The study includes a detailed topographic map and a failure analysis of the earthflow basin.