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2191. [Article] Ecological effects of spring and fall prescribed burning on basin big sagebrush : Idaho fescue--bluebunch wheatgrass communities
The vegetation response of spring and fall prescribed fires in basin big sagebrush (Artemisia tridentata subsp. tridentata Nutt.)/Idaho fescue (Festuca idahoensis Elmer)--bluebunch wheatgrass (Agropyron ...Citation Citation
- Title:
- Ecological effects of spring and fall prescribed burning on basin big sagebrush : Idaho fescue--bluebunch wheatgrass communities
- Author:
- Sapsis, David B.
The vegetation response of spring and fall prescribed fires in basin big sagebrush (Artemisia tridentata subsp. tridentata Nutt.)/Idaho fescue (Festuca idahoensis Elmer)--bluebunch wheatgrass (Agropyron spicatum Pursh. (Scribn. & Smith)) communities was measured at the John Day Fossil Beds National Monument in eastern Oregon. Objectives of the study were to quantify fuel loads, environmental conditions, fire behavior and vegetation response corresponding to these two fire treatments. Pretreatment fuel loads in the experimental units ranged from 5 to 12 Mg/ha, with the fall treatment units averaging 10.5 Mg/ha, and the spring units averaging 6.2 Mg/ha. Both treatments contained large amounts (> 3 Mg/ha) of herbaceous fuels. Moisture content of grass and herb fuels were significantly greater in the spring burned units. This is believed to be largely responsible for the less severe fire behavior observed in the spring burn treatment. Flame lengths averaged 4.2 m in fall burns, compared to a mean of 1.7 m in the spring plots. Similarly, rate of spread was significantly greater in the fall units, averaging 1.6 m/s, compared to 0.2 m/s in the spring treatment. Fireline Intensity was seven times greater, and total energy release was twice was great in the fall burns. Neither burn treatment resulted in significant mortality of bluebunch wheatgrass, but fall burning did cause significant mortality of Idaho fescue, where 20% of the population was killed. Fall burning stimulated tillering of bluebunch wheatgrass, as the average basal area increased both one and two years following burning. Average basal area per plant of Idaho fescue was reduced by 23% the first year following fall burning; however plants recovered to 90% of their preburn size by the second post-fire year. Spring burning resulted in no significant change in basal area of either species. Fall burning significantly reduced the number of flowering culms on bluebunch wheatgrass plants the first post-fire year (from 36 to 12 per plant); however, by the second post-fire year, number of flowering culms was significantly greater than either pre-burn or control levels (59/plant). Similarly, fall burning of Idaho fescue averaged 60% more flowering culms per plant as adjacent controls (11 compared to 7/plant). Spring burning reduced flowering of both species the first year following burning. Both burn treatments reduced the frequency of annual grasses, while causing no change in frequency of perennial grasses. Annual forbs increased in abundance following both burn treatments. Fire resulted in replacement of exotic annual grasses with annual forb species. Dominant perennial forbs responded variably in both burn treatments, as well as control plots. Frequency of sagebrush increased significantly in both spring and control experimental units in 1989 (one year after spring burning), while fall burns (two years posttreatment) demonstrated no such increase. Apparently, factors relating to the greater fire severity (e.g. consumption, total energy) in the fall burns reduced the rate and degree of reinvasion by sagebrush in the fall burn plots. Densities of annual grasses and woody species were significantly reduced by both burn treatments. Cheatgrass (Bromus tectorum L.) density before burning averaged 446 and 552/m2 in fall and spring units, respectively, as compared to 10 and 85/m2, respectively, the first post-fire year. Big sagebrush was completely eliminated by the fall fire, while spring burning resulted in an 84% decrease in density. Density of western juniper (Juniperus occidentalls Hook.) was reduced 100% by both burn treatments. Species diversity, as measured by the Shannon-Weaver Index (H'), was reduced by fall burning from 2.69 before treatment to 2.53 the first year following burning , but increased to 2.81 second post-fire year. Control plots behaved similarly, although changes were not as great. Changes were most evident in terms of rare species, many of which were not present prior to burning. Spring burning resulted in an no change in species diversity the first year after burning, although, species richness increased from 34 to 41. Both burn treatments appeared effective at changing stand structure to that of a dominance by native perrenial grasses and forbs. The reduced competition from woody plants has, and presumably will continue to favor surviving herbaceous plants. Overall fire effects appear to fit into land management policy of the National Park Service in regard to maintaining wildlands in a pristine state. Specifically, both spring and fall burning reduced fuel hazard, and increased the relative abundance of native species, indicating that prescribed burning may be an effective land management tool for the National Park Service and others managing similar rangelands.
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2192. [Article] Livestock, deer and logging interactions in the lodgepole pine/pumice region of central Oregon
The objectives of this study were to: 1) determine production of plant species and utilization by cattle, sheep and deer as related to plant communities and timber management practices and 2) evaluate the ...Citation Citation
- Title:
- Livestock, deer and logging interactions in the lodgepole pine/pumice region of central Oregon
- Author:
- Stuth, Jerry W.
The objectives of this study were to: 1) determine production of plant species and utilization by cattle, sheep and deer as related to plant communities and timber management practices and 2) evaluate the interaction of range use between cattle and deer and between sheep and deer as affected by site and timber management practices. Meadow communities and logged and non-logged areas of the Pinus contorta/Purshia tridentata /Stipa occidentalis habitat type were studied during the summer grazing season of a dry (1973) and wet (1974) year in Klamath County, Oregon. Six meadow habitat types were proposed. Meadow production varied from 879 to 2602 pounds per acre in 1973 (dry year) and varied from 2389 to 3295 pounds per acre in 1974 (wet year). Grasslike species in the meadows accounted for the greatest response in production to yearly moisture fluctuations. Forbs experienced little change in production on meadows with good soil and water conditions, whereas, a 93 to 160 percent increase occurred on the more shallow, dry meadows. Deer grazing on the meadows maintained a diet dominated by forbs both years, whereas, cattle and sheep grazed predominantly on grass and grasslike species while on the meadows. Meadow species which constituted the greatest potential overlap in the diets of livestock and deer included: Potentilla gracilis, Microseris nutans, idalcea oregana, Ranunculus alismaefolius, Achillea millefolium and Penstemon procerus. Deer experienced a transition from a forb dominated diet to a shrub dominated diet during July. Purshia tridentata was the only species utilized by deer in both logged and non-logged areas with utilization being minimal during July. After August 1 utilization accelerated in the logged areas but remained static in the non-logged areas. Approximately 7 to 10 times more Purshia tridentata was consumed by deer from logged areas. Only fringes of non-logged areas were used by cattle. Stipa occidentalis and Sitanion hystrix growing in logged areas dominated the diet of cattle in July. By mid-August Purshia tridentata dominated their diet and comprised 75 percent by the end of the grazing season. Purshia tridentata was dominant in the diet of sheep on the logged and non-logged areas throughout the grazing season. Approximately 2.5 times more Purshia tridentata was consumed by sheep in the logged areas as compared to the non-logged areas. At the end of the grazing season dual utilization values on Purshia tridentata in logged areas were 25 and 50 percent for cattle-deer and sheep-deer, respectively and in non-logged areas were 15 and 30 percent, respectively. Total herbaceous production was 58-126 and 12-18 pounds per acre for the logged and non-logged areas, respectively. Purshia tridentata production was 287-397 and 223-297 pounds per acre for the logged and non-logged areas, respectively. Purshia tridentata plants growing in non-logged areas had 55 percent of their current year's growth in the unutilized spurs. Developed leaders (terminal and lateral) accounted for 71 percent of the production of Purshia tridentata in logged areas. Average leader lengths were approximately 2.5 cm longer on plants in logged areas. Approximately 42 percent of the Purshia tridentata plants were lost during the logging operations. Sixty-four percent of the > 40 cm height plants were lost from logging while 16 percent of the 20-40 cm height plants were destroyed. Densities of germinated rodent caches of Purshia tridentata were much lower in logged areas. Percent canopy cover and density of Purshia contorta were highly correlated with cache densities in logged areas. Additional managerial considerations relative to timber harvest were mentioned.
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2193. [Article] A production function analysis of water resource productivity in Pacific Northwest agriculture
The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This ...Citation Citation
- Title:
- A production function analysis of water resource productivity in Pacific Northwest agriculture
- Author:
- Holloway, Milton L.
The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This rivalry and the long run prospects for water shortages have increased the demand for research concerning the productivity of this resource in alternative uses. This demand exists because the distribution and use of water resources require investment which typically comes from both public and private sources. Private and public planning groups seek answers to questions regarding future water resource development alternatives. Agriculture has historically been a major user of water in the Pacific Northwest. A substantial portion of total investment in water resource development has also been, in agriculture. As a result water use planners and decision making bodies are necessarily interested in water use in agriculture. The success of water resource planning requires answers to questions regarding the value of the productivity of water in all its major uses, including various aspects of water use in agriculture. Different aspects of water use in agriculture which are important to decision makers include (1) the value productivity of various kinds or types of water resource investments, (2) the value productivity of water in various kinds of agricultural production in different geographical areas, and (3) the returns to private and public investment in agricultural water resources. This study was directed to providing answers to these questions. Pacific Northwest agriculture was studied from this viewpoint. Agricultural water resources were classified as irrigation, drainage, and water related Agricultural Conservation Program (ACP) practices. These are the major classifications of water resources in which investments are made in the Pacific Northwest. Production function analysis was selected as a method of investigation. Production functions were estimated for five areas or subregions in the Pacific Northwest. These areas are composed of counties with similar patterns of production. The Agricultural Census was the primary data surce, supplemented by related U.S. Department of Agriculture publications, and various state publications, Ordinary least-squares regression (OLS) techniques were employed to derive the initial estimates of the parameters of the production function models. Tests for detecting interdependence within the independent variable set of the models revealed a considerable degree of instability in the OLS parameter estimates. This condition makes the OLS solutions (and various derivations) particularly vulnerable to change from measurement error, poor model specification, and equation form. A prior information model was selected to explicitly include available prior knowledge in the estimation process. The model selected allows (1) tests of comparability of the two information sources (prior and sample), (2) over-all contribution of prior information to the new solution set, and (3) derivation of percentage contribution of the two information sources to individual parameter estimates. The results of the study indicate that no reliable estimates of value of production from drainage and ACP were possible from the sample information. Returns to irrigation were considered lower than expected in two of the farming areas and higher than expected in another. Estimated returns were high in the area which produces primarily field crops (about nine dollars per acre foot). The area has a small level of current irrigation development. Indications are that irrigation development is probably beyond the optimum level in the area where most large, projects have been developed in the past (less than four dollars per acre foot). Future development would be most profitable (assuming equal development cost) in the dryland field crop area. Estimated returns to other factor inputs indicate (1) low returns to labor in two areas, (2) generally high returns to current operating expenditures, and (3) low returns to machinery capital. Returns to cropland were about as expected in two areas (five to seven percent) but low in two other areas (about two percent). Indications are that labor mobility should be increased in the area and that future land development should be in the livestock-field crop and the field crop areas rather than the coastal area or the west-central valley areas (primarily the Willamette Valley).
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This study was designed (1) to examine credit usages as they relate to financial problems of young married couples, (2) to investigate the similarities of financial practices of two populations, (3) to ...
Citation Citation
- Title:
- An investigation of credit usage among young married couples in western Oregon
- Author:
- Preisz, Lois Heesacker
This study was designed (1) to examine credit usages as they relate to financial problems of young married couples, (2) to investigate the similarities of financial practices of two populations, (3) to determine the sources of educational financial assistance and guidance used by young couples, and (4) to compare demographic characteristics of one sample known to have had financial difficulties and one group whose financial position was unknown at the time of the interview. The sample consisted of 30 young married couples who were being professionally counseled because of financial problems (group one) and 30 couples selected from a mailing list supplied by the Marion County Extension Service (group two). The total sample was drawn from the Salem, Oregon area. The couples were married at least one year and not more than five years, 11 months and the husbands were no more than 30 years of age. Data for the study were obtained through personal interviews. Hollingshead's Two Factor Index of Social Position, based on education and occupation of the head of household was used to classify the subjects into five social positions, by groups. The distributions for both groups were skewed heavily toward the lower social levels on the scale. The four null hypotheses that were set forth to assist in the organization of data were rejected. H₁ Young married couples in group one wit; show no differences in financial practices from those in group two. H₂ Married couples in group one will possess records with detail no greater than that in records possessed by group two. H₃ Formal educational training will not vary between group one and group two. H₄ Financial counseling sought by young couples will not differ between group one and group two. Analysis of the data indicated that couples in the uncounseled group kept records in a more readily accessable manner; they kept them in ledger or check stub form; and a larger percentage of group two kept track of how they spent their money. A higher number of husbands in group one took complete charge of financial management than the husbands in group two. There were inconsistencies in the responses of the wives in group one. Eighty-seven per cent of the respondents stated that they and their husbands combined their money. However, responses by 40 per cent of the wives in group one indicated that their husbands paid the bills and handled the finances. Couples in both groups used a variety of credit sources. Couples in group one held more credit cards, had a larger number of open charge accounts, more loans from banks and consumer finance companies, as well as a larger number of hospital, doctor and dentists bills than did the couples in group two. Department store and oil company credit cards were the two categories most frequently listed when respondents were asked about credit cards held. Both banks and consumer finance companies loaned to couples in group one, however, the consumer finance company had a higher incidence of repeat loans issued to these young couples than did banks. Ninety per cent of the young couples in the counseled group responded that they were being counseled and looked to the professional counselor for guidance in personal finance. The uncounseled group turned to parents most frequently as sources of information and guidance. Wives in group one perceived themselves as poorer users of credit or just equal when comparing themselves to their peers. It was apparent from this study that young couples feel inadquately prepared for the responsibilities faced in money management during the early years of marriage. With an affluent credit society predicted by many for the future, young people will need to use their total resources of time, energy and income in order to maintain financial solvency. Educators, both adult and secondary along with parents and all others interested in the welfare of families will need to be innovative in communicating sound personal finance principles.
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2195. [Article] Effects of dispersion and parent population density on enclosed populations of Microtus montanus (Peale)
This field investigation was designed to further the understanding of the significant influence which parent population density, as well as dispersion, have on the dynamics of enclosed populations of the ...Citation Citation
- Title:
- Effects of dispersion and parent population density on enclosed populations of Microtus montanus (Peale)
- Author:
- Smith, Jerome Stafford
This field investigation was designed to further the understanding of the significant influence which parent population density, as well as dispersion, have on the dynamics of enclosed populations of the montane vole, Microtus montanus (Peale). The study was conducted in Klamath County, Oregon from June, 1963 to February, 1964. The objectives were to investigate possible effects of parent population density on such characteristics of the ensuing generations as density, reproduction, survival, and movement, and to determine the effects of dispersion on a population. Four one-quarter acre enclosures were used during this study. Two contained voles from a 1962 high parent population density (E 4 and E 6) and two contained voles from a 1962 low parent population density (E 5 and E 7). A means for mice to disperse was provided in two enclosures (E 5 and E 6), one enclosing mice from a low parent population, the other, mice from a high parent population. All population characteristics were determined by live trapping from three to five days at two to six week intervals. The enclosed populations had comparable peak densities during December, with the exception of E 4 which was significantly lower than E 7. The ratio of increase was greatest in E 4 and E 6. E 6 supported the largest number of mice and E 4 the smallest. Males were dominant in E 4 and E 7 through most of the study. Females were dominant in E 5 throughout the study and in E 6 until December. E 5 and E 6 supported a larger percentage of young animals than did E 4 or E 7. E 4 had the highest average percent of females perforate, pregnant, and with mammary glands large or lactating; E 6 had the next highest percentages and E 5 and E 7 the smallest. Reproduction stopped in all enclosures after the November trapping period. All enclosures had very good survival through December but poor survival through January. The poor January survival was probably due to the presence of tularemia within the enclosures. E 4 and E 6 had consistently better cohort survival throughout the study than did E 5 and E 7. Juveniles survived best in all enclosures until August, after which time the sub-adults and adults had the better survival rate. E 6 had statistically better mean survival through December than did E 4 or E 7, and through January than either E 5 or E 7. The dispersal ramps captured 2.73 times more animals from E 6 than from E 5. During the study juvenile and sub-adult females and sub-adult and adult males were the only age classes of mice captured in the ramps until November when adult females were first caught. Most sacrificed dispersal males were found to be in breeding condition while only a few of the females had bred. Captures per ramp day were generally density dependent. Some differences observed in the population characteristics of the four enclosures can be attributed to parent population density and /or dispersion. High parent population density did not adversely affect reproductive potential or the survival of a vole after it had become established in a population. Prenatal mortality and the amount of wounding, an indication of intraspecific strife, was greatest in the enclosure with mice from a high parent population density and where dispersion was not allowed. Where dispersion was allowed recruitment was high, survival was good, and the amount of wounding was low regardless of parent population density. It is suggested that animals from a high parent population are selected for aggressiveness which eventually causes a disruption of the social structure. Dispersal tends to maintain a stable social structure until populations become dense, at which time dispersion is a less effective regulatory mechanism.
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This thesis consists of three parts: 1) a field case study involving tree growth, moisture stress, and foliar nitrogen response to sheep-grazed pasture treatments; 2) a shadehouse (potted-plant) study ...
Citation Citation
- Title:
- Relationships of tree growth to nitrogen and water availability in a sheep-tree-pasture system in Douglas County, Oregon : field case study and shadehouse simulation
- Author:
- DeMeo, Thomas
This thesis consists of three parts: 1) a field case study involving tree growth, moisture stress, and foliar nitrogen response to sheep-grazed pasture treatments; 2) a shadehouse (potted-plant) study of simulated grazing effects on tree growth and moisture use; and 3) a summary, synthesizing results of the field and shadehouse studies and relating both to previous research. Part I. Field Case Study In a two-year-old agroforestry planting near Roseburg, Oregon, tree growth in grazed forb-dominated, grazed grass-dominated pasture, and bareground treatments was compared. Grazing by sheep was intensive. Trees were the KMX pine hybrid (Pinus attenuata X P. radiata) and Douglas-fir (Pseudotsuga menziesii). Significantly greater height and diameter growth of trees was found on the bareground treatment. KMX pine absolute growth was always superior to that of Douglas-fir. On a relative basis, however, both species were growing at about the same rate. Predawn tree xylem potential did not differ significantly among pasture treatments, but KMX pine values were significantly greater (less stress) than those of Douglas-fir during summer drought. Tree foliar nitrogen concentrations of both species were consistently high; species and treatment differences were generally insignificant. Soil total nitrogen likewise did not differ between treatments. Superior growth of KMX pine, compared with that of Douglas-fir, appeared related to lower summer xylem moisture stress. KMX pine produced superior growth, compared with Douglas-fir, due to lower xylem moisture stress during summer months. For the site and conditions investigated, moisture rather than nitrogen appear to be limiting growth. On sites similar to the one investigated, it was concluded nitrogen recycled in animal waste is unlikely to induce a tree foliar N response in the establishment phase (0-3 years) of tree plantations. Part II. Shadehouse Grazing Simulation Effects of simulated grazing of interplanted forage plants on growth and water use of three tree species were evaluated in a semicontrolled environment (open shadehouses). Varied proportions of perennial ryegrass (Lolium perenne) and subterranean clover (Trifolium subterraneum) were planted in pots with individual KMX pine, Douglas-fir, and Eucalyptus glaucescens. A tree-only treatment was also included. Forage in pots was clipped monthly for one growing season (May until October 1986). To simulate animal waste nitrogen return, 80 percent of nitrogen removed was returned as urea after each clipping. A second set of forage treatments was clipped but received no urea. KMX pine showed significantly (p=O.O5) greater diameter growth and total biomass than eucalyptus or Douglas-fir. Eucalyptus had the greatest height growth of the three species. Generally, trees with clover only or with no competing vegetation showed greater (p=O.1O) growth than trees with grass or mixed clover-grass competition. High grass competition had a depressing effect on tree growth. Eucalyptus appeared most affected by forage treatments, followed by Douglas-fir. KMX pine was least affected. Fertilization had no effect on tree growth, although it significantly (p=O.O5) increased eucalyptus shoot/root ratio. Moisture stress experiments indicated trees with no competing vegetation lost the most water over time. Because of a watering regime predisposing trees to stress, soil moisture content could not be correlated with tree predawn xylem potentials. A comparison of tree foliar nitrogen (N) in October 1985 (forage establishment) and October 1986 (harvest) showed no significant difference between forage/fertilization treatments at either time. Total soil nitrogen likewise did not change during the study period. Ryegrass biomass production consistently exceeded that of subterranean clover in grass-clover mixtures. Ryegrass dominated clover when ryegrass proportion was 20 percent or greater (unfertilized) and 10 percent or greater (fertilized). Fertilization approximately doubled ryegrass biomass yield but had no effect on clover yield. Forage growth in association with KMX pine markedly decreased. Douglas-fir had no effect on forage growth. Eucalyptus was intermediate. I conclude that tree growth in the simulation was limited by moisture. Added urea nitrogen benefited ryegrass growth. Trees with the least amount of vegetative biomass competition produced the greatest growth. Clover was neutral in effect on tree growth. Results suggest young tree plantations in grazed western Oregon pastures are unlikely to benefit from animal waste nitrogen return. On dry sites, summer moisture stress will limit tree growth and inhibit uptake of animal waste nutrient return.
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2197. [Article] Influence of range improvement practices on composition, production, and utilization of Artemisia deer winter range in central Oregon
Recent emphasis on range improvement of sagebrush-bunch-grass types in Oregon has underscored the need for better understanding of their importance to deer winter range management. The objectives of this ...Citation Citation
- Title:
- Influence of range improvement practices on composition, production, and utilization of Artemisia deer winter range in central Oregon
- Author:
- Urness, Philip J.
Recent emphasis on range improvement of sagebrush-bunch-grass types in Oregon has underscored the need for better understanding of their importance to deer winter range management. The objectives of this study were to evaluate the impact of various sagebrush control practices on the composition, production, and utilization of deer forage plants during the critical winter period. Field studies continued from June, 1963, to August, 1965, at various locations throughout the Fort Rock and Silver Lake deer winter range units in northern Lake County. Range improvement effort has been directed primarily toward poor condition communities dominated by big sagebrush (Artemisia tridentata). Consequently, sampling was practically restricted to these communities although other types were recognized to be of equal or greater value to deer. Two basic approaches were followed. The first consisted of establishing three experimental treatment blocks in stands representative of extensive big sagebrush communities. Quantitative plant ecological data were taken prior to treatment as a basis for interpreting later successional changes. Four commonly-accepted range improvement methods--spraying, spray-seeding, rotobeating, and plow-seeding--were initiated on two-acre strips in each block with an additional untreated strip forming a control. Half of each block was fenced to determine differences resulting from livestock exclusion. Periodic resurveys over five to seven years are scheduled. The second approach entailed a paired-macroplot study of selected existing projects where spraying, rotobeating, burning, and seeding treatments had been used. Similarity of soils and other physical site factors formed the basis for pairing plots and inferring similarity of pretreatment vegetation. Floristic differences among paired plots were quantified by data on shrub coverage, density, and height; basal area of herbaceous species; and frequency of all species. All treatments reduced shrub cover sharply but rotobeating resulted in the greatest shrub survival. Herbaceous species response was variable but only seeded stands of crested wheatgrass showed marked increases in basal area of desirable forages. Production data indicated wide fluctuations in shrub herbage available for winter use. Estimated big sagebrush herbage production on untreated stands in oven-dry pounds per acre ranged from 23 to 449 and averaged 234. Winter-active grass herbage was most abundant on crested wheatgrass seedings, particularly those grazed heavily by livestock in the preceding growing season. Estimated production ranged from 37 to 126 and averaged 75 pounds per acre of oven-dry material. Green growth of native grasses was important feed for deer primarily during the latter part of the winter period. Bitterbrush, the key browse plant for deer on the study area, sustained excessive levels of use at all locations studied. Recent changes in livestock grazing season have effectively minimized use of bitterbrush by this class of grazing animal. Bitterbrush mortality has been high and both vigor and stand regeneration are generally poor. It was concluded that effects of existing improvement programs were usually minor compared with the declining condition of the all-important bitterbrush stands resulting from excessive winter populations of deer. Species other than bitterbrush were utilized moderately to lightly. Green rabbitbrush showed a consistently higher percent of plants grazed and mean percent utilization than big sagebrush on untreated stands. Seedings and other range improvements tended to create a diversified plant cover and forage resource that appeared to enhance use of the untreated sagebrush. Green grass material was significantly higher in crude protein percentage than current annual growth of shrubs. Management emphasis should be directed toward positive programs of vegetational manipulation designed to increase forage values of big sagebrush types for deer as well as livestock.
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Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; ...
Citation Citation
- Title:
- Geology of the Buster Creek-Nehalem Valley area, Clatsop County, northwest Oregon
- Author:
- Olbinski, James Steven
Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; upper Eocene Vesper Church formation (informal); upper Eocene to Oligocene Pittsburg Bluff Formation; and middle Miocene Depoe Bay Basalt. The Tillamook Volcanics is composed of basaltic andesite subaerial flows (SiO2 54.19% to 55.67%) and volcanic debris flows. The platy jointed subaerial flows are generally porphyritic with a pilotaxitic groundmass; a few aphyric flows with well defined flow banding are present. Highly vesicular flow tops typically show alteration of ilmenite to leucoxene producing a diagnostic bleached white appearance. Debris flows are comprised of very poorly sorted, angular, volcanic and minor sedimentary rock clasts in a mud matrix. Commonly this lithology is intruded by porphyritic and vesicular dikes. Major oxides of the Tillamook basaltic andesites suggest that these volcanic rocks may have erupted in an oceanic island "spreading center" environment. The Cowlitz Formation unconformably overlies the Tillamook Volcanics in the study area. This formation is divided into five informal members: a basal basaltic andesite conglomerate; a unit of interbedded micaceous arkese, volcanic lithic arenite and mudstone; a thick structureless mudstone; rhythmically laminated turbidite sandstone and siltstone; and a thick upper arkosic sandstone. The basal conglomerate represents a fluvial braided stream to high energy marine shoreline environment. The finer grained middle members indicate a deepening up sequence. The upper sandstone member is a micaceous, well-sorted, hummocky bedded, porous, very friable sandstone deposited in a high energy storm-dominated shelf to nearshore environment. The upper sandstone member of the Cowlitz Formation ("Clark and Wilson sand" of the Mist gas field) is the current target of active drilling in adjacent areas by several petroleum companies. This upper sandstone and lower arkosic sandstones represent favorable targets in contact with organic-rich, but immature, source rocks in potential fault bounded structural highs and erosional pinchouts in the northern part of the study area. The Narizian to Refugian Keasey Formation is represented by the Jewell member (informal), in the study area. The Jewell member, a well-bedded to laminated, tuffaceous, indurated mudstone, unconformably overlies the more extensively faulted Cowlitz Formation. Upper slope water depths of 200-600 m are indicated by foraminiferal and molluscan assemblages. A lithologically distinct and mappable turbidite unit crops out in the study area and is informally named in this thesis the Vesper Church formation. The Vesper Church formation represents west- to northwest-trending turbidite-filled "sea gullies" deposited at bathyal depths (1,000-1,500 m) on the lower slope. Thin-bedded channelized turbidites with Bouma c, d and e sequences and local thick amalgamated sandstones characterize this unit. The upper Eocene (Refugian) Pittsburg Bluff Formation conformably overlies the Vesper Church formation. Molluscan assemblages from the basal part of this formation indicate water depths of 20-200 m; thus, a significant shallowing episode between the Vesper Church and Pittsburg Bluff formations is indicated. Thick, bioturbated, glauconitic to fine-grained tuffaceous sandstone and sandy mudstone suggest an inner to middle (possibly outer) continental shelf depositional environment for the Pittsburg Bluff strata. Following a period of high-angle northeast trending faulting, two middle Miocene Depoe Bay Basalt dikes intruded the sedimentary formations exposed in the area. The reversely polarized Northrup Creek dike can be traced over 8.5 km and has a paleomagnetic declination of 170° and a steep inclination of -74°, possibly a result of secular variation of the geomagnetic pole during cooling of the dike through its Cuire temperature (Nelson, 1983). These aphanitic to sparsely micro-porhyritic tholeiitic basalts are chemically identical to the Grande Ronde Basalt of the Columbia Plateau. A recent hypothesis by Beeson et al. (1979) suggests that all Miocene coastal basalts represent the distal ends of subaerial Columbia River basalts which reached the Miocene shoreline and intruded or "invaded" soft marine sediments. The reversed stratigraphic order of high and low MgO Depoe Bay (Grande Ronde) basaltic sills intruding Keasey and Cowlitz strata, as much as 1600 m below the surface in the petroleum exploration well Quintan_a Watzek 30-1 Watzek 30-1 in this study area, illustrates a complicating factor in the emplacement mechanism if these are "invasive" intrusions. In late middle Miocene the northern Oregon Coast Range anticline was formed, possibly in response to a period of underthrusting (Snavely et al., 1980b). Contemporaneously, a second set of left-lateral and right-lateral conjugate faults (N55°E and N55°W) cut the middle Miocene basalt dikes. This faulting may be related to north-south compression and clockwise rotation of western Oregon and southwest Washington associated with the oblique subduction of the Juan De Fuca Plate beneath the North American Plate as suggested by Magill et al. (1981) and Coe and Wells (1982).
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2199. [Article] The effectiveness of the emergency rules of 1998, as implemented during the erosion event in Neskowin Oregon, 1999
Neskowin, Oregon is a small village tucked against the north side of Cascade Head in the southern end of the Nestucca littoral cell in Tillamook County. It is a quiet place of narrow streets lined with ...Citation Citation
- Title:
- The effectiveness of the emergency rules of 1998, as implemented during the erosion event in Neskowin Oregon, 1999
- Author:
- Windrope, Amy
Neskowin, Oregon is a small village tucked against the north side of Cascade Head in the southern end of the Nestucca littoral cell in Tillamook County. It is a quiet place of narrow streets lined with old beach shacks and new mansions. Proposal Rock divides the old and new: to the north is the old town and to the south is the newer section. In summer, the town is full of vacationing residents while in winter the town is virtually deserted. Therefore, few residents were present to view the 30+ foot swells that rolled across the beaches in February and March of 1999. Not many saw the creek overflow as the wave bores tumbled across the main bridge dumping huge stumps and other debris in the Neskowin State Wayside. Returning on Memorial Day 1999, summer residents were confronted with a changed beach. A flat beach backed by boulders brought in from quarries had replaced the rolling dunes. The changes occurred suddenly in the winter of 1999, between January 1 and March 30 when the last of the dunes disappeared and the waves threatened the ocean front homes. The storms took the sand and the contractors replaced it with rock. The events of winter 1999 in Neskowin are not new to the state of Oregon, though they were unusually severe. Oregon has policies and rules in place to address the inevitable threat to oceanfront property. However, not until 1998 did the state formally address coastal erosion emergencies. Before 1998, the state provided emergency authorization to protect homes from erosion but there existed no formal process. El Nino 1997-98 motivated the State to formulate policies that would formalize the emergency authorization processes thereby insuring protection of the State's interest in coastal development. The storms of February and March 1999 offered the first test of these procedures in an emergency. The Neskowin erosion event provides an opportunity to judge the effectiveness of the new emergency rules. Understanding the events of Neskowin in 1999 provide a forum for discussing the entire Oregon coast. Neskowin reflects the issues and problems repeated throughout the state. Oregon's coast is dynamic and has the potential for major erosion events. In order to preserve the beaches for summer residents and visitors, the State must actively manage shore protection structures. By working with residents in winter, the State protects the public trust and the interest of non-coastal property owners. Oregonians have a unique relationship to their beaches; they are part of the family and act as an open playground. Armoring the coast undermines the right to wander the beach, gather agates and camp. The armoring alters the ability of the beach to respond to storms, and to move and retreat as water levels change. However, homes built on dunes and bluffs need protection. Managing the coast is about balancing the public good with private rights while recognizing the inevitability of coastal hazards. Viewing the erosion event at Neskowin and the subsequent management response as a microcosm for Oregon allows a broader understanding into the state of the coast and is therefore immediately relevant and important Shore protection structures are a controversial subject on the Oregon coast. The dispute-over the structures is essentially about the conflict between private property rights and the public's right to an unobstructed beach. The private property owners feel that they have a legitimate interest in protecting against loss of property from wave attack and erosion. There is also a sense in the private property community that the beach fronting their homes is essentially owned by them. This is a misperception leading to conflict with public beach advocates. Those that oppose shore protection structures have, typically, three main arguments. The first argument is that the structures limit access to the beach from the upland as well as lateral access along the beach in periods of high tide. The second argument is that the public owns the beach and private property owners do not have the right to place hard structures on the beach limiting the aesthetic quality of the beach. A last argument involves the uncertainty of sea level rise. If the sea level were to rise, this may result in a complete loss of beach with waves at all tidal levels reaching the back of the beach fronted with structures. The State of Oregon has tried to reach a compromise with the two views through its coastal management program and more specifically with the emergency rules. The ability of the State to protect private property while still protecting the public trust on the shore is a delicate balancing act. The emergency situation at Neskowin is illustrative of the implementation problems associated with protecting the public's right to an unobstructed beach while still offering property owners the opportunity to protect their homes. The purpose of this research is two-fold: to evaluate the success of the new emergency procedures promulgated in 1998 and to characterize the erosion event that 6 precipitated the emergency during January, February and March 1999. These two purposes support each other and provide a holistic understanding of how emergencies arise and how effective state procedures are in meeting the challenges of extreme events. In order to facilitate understanding, an overview of Oregon's shore protection policies will proceed the analysis of the new emergency rules. Neskowin will act as a case study to see how well the emergency rules worked.
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2200. [Article] Passage, migration behavior, and autoecology of adult Pacific lamprey at Winchester Dam and within the North Umpqua River Basin, Oregon, USA
The extensive reduction in adult Pacific lamprey (Entosphenus tridentatus) counts at many hydroelectric dams in the northwestern USA signals a substantial decline in lamprey numbers across the entire region ...Citation Citation
- Title:
- Passage, migration behavior, and autoecology of adult Pacific lamprey at Winchester Dam and within the North Umpqua River Basin, Oregon, USA
- Author:
- Lampman, Ralph Tatsuo
The extensive reduction in adult Pacific lamprey (Entosphenus tridentatus) counts at many hydroelectric dams in the northwestern USA signals a substantial decline in lamprey numbers across the entire region in the past 40 to 50 years. Among the many potential causes of this decline, obstruction of migration routes has likely played a substantial role. Within the North Umpqua River basin in southwest Oregon, USA, I focused on the following three research goals: 1) to describe the passage efficiency and migration routes of adult Pacific lamprey at Winchester Dam; 2) to evaluate the seasonal movement patterns of adult Pacific lamprey and their use of holding habitat at Winchester Dam in relation to temperature conditions; and 3) to portray the diversity of upstream migratory behaviors of adult Pacific lamprey and the environmental factors that influence these behaviors. This radio telemetry study was conducted between March 2009 and August 2011 with a combination of fixed stations and manual tracking. Passage efficiency was low in both years (8% and 19%, respectively), and all tagged lamprey that successfully passed the dam used routes other than the fish ladder. Lamprey that migrated early within the run and those with relatively small tags had higher passage rates and traveled further than the other groups of lamprey. Lamprey released above of the dam or those that passed the dam on their own distributed themselves widely in the upstream environment, suggesting that the dam deterred their upstream migration. Using mark-recapture data for the two years, the adult Pacific lamprey population upstream of Winchester Dam was estimated at 960 (95% C.I. [188, 4760]) in 2009 and 556 (95% C.I. [110, 2798]) in 2010, which was considerably lower than historical counts at the dam (between 14,532-46,785 in 1965-1971). Most tagged lamprey that did not pass the dam remained at the base of the dam at the end of the summer migration (63% in 2009 and 67% in 2010). Types of habitat most frequently used by lamprey downstream from the dam included the dam surface (wooden structures with crevices), interface zones between fast and slow water, and highway bridge pilings. The lamprey movement changed considerably between August and September, and the frequency of movements decreased sharply during this period. Tagged lamprey were detected using thermal refuges immediately downstream of the dam that were 0.4 to 2.8 C° colder than the mean river temperature at the dam, and this temperature differential increased as the season progressed. Lamprey may be seeking overwintering habitat associated with hyporheic exchange flows at the dam towards the end of the summer season after their display of heightened activity early in the summer. Ninety-five percent of the overall upstream migration took place during the first spring/summer period, and only small-scale upstream movements were observed during the winter and second spring/summer (4% and 1%, respectively). The rate of upstream migration (median) was the fastest during the initial migration phase and was 1.9 km/day (ranging from 0.3 to 11.0 km/day) for tagged lamprey released above Winchester Dam. During winter, 71% of the lamprey remained in the same location where they initiated holding. Multiple regression analysis indicated that the total upstream distance traveled by individual lamprey was most strongly related to presence/absence of Winchester Dam, relative tag size, and water temperature and photoperiod conditions at release. The presence of Winchester Dam, large relative tag size, and high water temperature / short photoperiod conditions at release significantly reduced upstream migration distance.