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Willamette Valley River Towns and SteamboatsKeeler, Elizabeth Louise 03 1900 (has links)
335 pages / This thesis describes the river towns along the Willamette River in
Oregon. River conditions, adaptation of the boats to the river, and
steamboat routes shown at ten year intervals illustrate the degree of
accessibility of the various towns. Reasons for success or failure in
light of factors of site, situation, efforts of townsite promoters or
lack thereof are evaluated. Increase in population is used as a measure
of success. Orientation to the river was reflected in town plans and
location of land uses as sh own in early maps and views.
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The marine air penetration of the southern Willamette Valley and its effect upon agricultural field firesSielaff, Carl Ogden 28 May 1980 (has links)
This research consists of two related yet distinct
studies: an observational study of the surface character of
the penetration of marine air into the southern Willamette
Valley and a climatological study of the summertime air
masses of northwestern Oregon.
For the observational study, temperature and estimated
wind data were gathered by automobile. Mesoscale analysis
of several cases indicate that the Marine Air Penetration
(MAP) occurs regularly in approximately the same area and
is strongly controlled by the topography. Qualitative
observation and reasoning strongly suggests that the strong
winds and increased stability at the top of the marine layer
have an adverse effect upon agricultural field fires.
Results of the climatological study indicated that the
application of the partial collective method of analysis to
July maximum temperature data from the U.S. Climatological
Network yielded a meaningful air mass climatology for northwestern Oregon. To our knowledge, this is the first time that the partial collective method has been applied to a
region with mountainous areas west of the Rocky Mountains or
to the mesoscale. / Graduation date: 1981
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The effects of patch size and isolation on juvenile emigration in gray-tailed voles, Microtus canicaudusNelson, Natasha 24 May 1996 (has links)
Graduation date: 1997
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Over-winter demography of the gray-tailed vole (Microtus canicaudus) in fragmented and continuous habitatsBrunkal, Heidi L. 25 November 1996 (has links)
Large scale disruption of natural habitats worldwide has led to concern over the
effects of habitat fragmentation on wildlife populations. Small scale experiments may be
a useful tool for discovering effects of fragmentation over larger landscape scales. I
sought to explore the potential for using voles as an experimental model system, at a
small scale, to discover mechanisms that may affect other species at different spatial
scales. I compared over-winter demography of gray-tailed voles, Microtus canicaudus, in
two experimental landscapes, consisting of fragmented and continuous habitat, to assess
the effects of habitat fragmentation. I chose winter as the time frame of the experiment
because it poses harsh conditions for voles and because seasonal bottlenecks may affect
population persistence. Population size, population growth rates, reproduction,
recruitment, survival and movements, were monitored using mark-recapture methods in
8, 0.2-ha enclosures planted with alfalfa. The habitat within the enclosures was
manipulated into 2 configurations of equal area, 1 large continuous patch (625 m��), and a
mosaic of 25 small patches (each 25 m��), prior to the introduction of 12 pairs of
animals/enclosure. I hypothesized that population size and growth rates, reproduction,
recruitment, and survival would be greater for vole populations in continuous habitats
than for populations in fragmented habitats. Additionally, I hypothesized that movements would be more restricted within fragmented habitat because the voles would perceive the
area between habitat patches as a barrier.
I did not detect significant differences between vole populations in continuous and
fragmented treatments. However, populations residing in fragmented habitat showed
higher variability over the study period. Populations in both treatments decreased
throughout the winter period and all became extinct by the end of the study.
Reproduction occurred only during the fall period, and there were no significant
differences between treatments. Movements were not different between treatments, or
between male and female voles, but movements did increase over time. Survival appeared
to be higher for male voles in continuous habitat than in fragmented habitat, but female
vole survival was similar between treatments. Survival was influenced by weather
conditions, and predation. These results contrast with a previous experiment during the
summer season, and indicate that seasonal bottlenecks may be important to consider
when studying habitat fragmentation. Extinction of populations in both treatments
demonstrates that small populations are extremely vulnerable to both environmental and
demographic stochastic events. / Graduation date: 1997
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Producing fiber flax using modern machinery and field rettingKennedy, Ralph C. 13 December 1996 (has links)
Fiber flax (Linum usitatissimum L.) production in the Willamette Valley ended in
Oregon around 1957 before newly developed technology and fiber cultivars were
available. The purpose of this research was to explore the use of modern methods and
new cultivars.
Field studies were conducted to evaluate cultivars and optimum cultural practices that
would produce the highest yield and best fiber quality in the Willamette Valley on
Woodburn silty clay loam. A study was conducted to assess the winter hardiness of fifty
flax cultivars.
The effect of four different pull dates on straw and fiber yield and fiber quality were
investigated at two sites in 1995 and 1996. Pulling in stage 2, 3, or 4 resulted in an
increase in straw yield over pulling in stage 1 in 1996. No differences were detected in
fiber yield or caustic weight loss in response to pull date in either year. An acceptable
pulling window is stages 1-3 (range of 900 to 1300 growing degree days). Retting took
13 weeks in both years. Rainfall during the retting period was 10.7 cm in 1995 and 6.9
cm in 1996.
A field study was conducted in 1995 and 1996 to test the effect of three nitrogen (N)
levels (50, 75, and 100 kg ha�����) and three fiber flax cultivars (Ariane, Cascade, and
Viking) on straw yield. There was a significant increase in yield with increased N levels
in 1996. Higher levels of N increased yield in all three cultivars in both years. Lodging
of 'Cascade' increased with increased N levels in 1995.
The effect of three planting dates on yield and stand density of Ariane fiber flax were
investigated in 1995. The 31 March planting date produced the most retted straw (9704
kg ha�����).
A fall-planted winter cultivar experiment was conducted during 1994-95 and 1995-96. In 1994-95, four varieties (Ariane, Texala, Viking, and Hyslop Cascade) had greater
winter survival than Linore, the check variety. Only Linore withstood the second winter. / Graduation date: 1997
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Developmental biology and phenology of the walnut husk fly, Rhagoletis completa Cresson (Diptera: Tephritidae) in the Willamette Valley of OregonKasana, Abdulmajid 26 July 1993 (has links)
Graduation date: 1994
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Investigating Groundwater Arsenic Contamination using Aquifer Push-Pull TestsDaigle, Ashley R., 1986- 06 1900 (has links)
xiii, 67 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The bedrock aquifer of the Southern Willamerte Basin, Oregon, USA, is
contaminated with arsenic at concentrations as high as several ppm. Single-well
push-pull tests were conducted to investigate how microbial metabolisms control arsenic
occurrence and levels in the aquifer. Test solutions containing ethanol were injected into
the aquifer; dissolved gases, groundwater, and sediments were then sampled to monitor
the speciation of carbon, iron, sulfur, and arsenic. Ethanol amendment stimulated a series
of microbial metabolisms, including arsenate reduction, iron reduction, and sulfate
reduction. Arsenate reduction converts arsenate to arsenite; iron reduction produces
ferrous iron; sulfate reduction releases sulfide. Arsenite and ferrous iron then combine
with sulfide and form arsenic sulfide and iron sulfide minerals. Results of the
experiments demonstrate that the interactions among microbial metabolisms and mineral precipitation influenced arsenic contamination in the aquifer. These results shed new
light on potential bioremediation strategies in the area. / Committee in Charge:
Dr. Qusheng Jin, Chair;
Dr. Mark Reed;
Dr. Samantha Hopkins
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Influence of light on algal growth in the lower Willamette RiverWille, Stephen Arthur 01 January 1976 (has links)
During the summer of 1974 chemical conditions in the lower reaches of the Willamette River, Oregon were similar to those in other rivers currently experiencing nuisance algal growth problems. Temperature and chemical nutrients are not limiting. Relatively high populations of phytoplankton and productivity values for upstream periphyton beds and surface waters suggest moderately eutrophic conditions. However, with increased depth in the lower river, and a constant euphotic zone, the amount of photosynthetically available light is reduced. With sufficient depth and complete mixing the critical depth is exceeded. Primary productivity rates are subsequently limited by low light availability in the lower river.
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The effects of land use on mineral flat wetland hydrologic processes in lowland agricultural catchmentsMarshall, Sarah M. (Sarah Marie) 16 September 2011 (has links)
Hydrologic processes within mineral flat wetlands, along with their
connections to groundwater and downstream surface water in lowland agricultural
catchments are poorly understood, particularly under different land uses. In the three
field studies included in this thesis, we examined infiltration, wetland hydroperiod,
groundwater recharge dynamics, surface runoff generation, and water quality in
mineral flat wetlands using a combination of soil and hydrometric measurements,
stable isotope tracers, and water chemistry analysis. Our overarching objectives were
to examine, for mineral flat wetlands under native prairie, farmed grassland, and
restored prairie land cover: 1) how different land management influences infiltration
and wetland hydroperiod at the plot scale, 2) the effects of land use on seasonal
groundwater-surface water dynamics at the field scale, and 3) seasonal variation in
runoff sources and nutrient transport from native prairie and farmed wetlands at the
small catchment scale.
At the plot scale, our results suggest that edaphic factors, particularly those
related to soil structure, are strongly associated with wetland infiltration and overall
hydroperiod across least-altered prairie, farmed, and restored prairie mineral flat
wetlands. The hydroperiod metrics we examined were generally more sensitive to
level of site disturbance than land use alone. At the field scale, our results indicate
that, in spite of land use differences and slight variations in soil stratigraphy, many
similarities exist in overall wetland hydroperiod, water sources and evaporation rates
for mineral flat wetlands in the Willamette Valley lowlands. Isotopic evidence
suggests that the greatest degree of groundwater-surface water mixing occurs in the
upper 0.5 m of the saturated soil profile across sites under all land uses. Finally, at the
small catchment scale, farmed wetland runoff was isotopically similar to field surface
water for most of the wet season, indicating that saturation excess was an important
runoff generation process. Prairie wetland runoff was isotopically similar to upstream
water throughout the winter, and briefly similar to shallow groundwater and surface
water within the wetland in mid-spring. Throughout the wet season, elevated nitrate,
sulfate, and chloride concentrations were observed in groundwater and surface water
at the farm site, and deeper groundwater at the prairie site. Upstream-downstream
runoff chemistry remained similar throughout the wet season at the prairie site. Farm
site runoff chemistry reflected the dominant water source within the farm field
throughout the wet season. Our findings suggest that, while surface water pathways
dominate runoff from wetland flats under farm land use, large wetland flat fields have
a high potential to absorb, store, and process nutrients and agrochemicals from on-site
and nearby off-site chemical inputs.
Mineral flats that maintain wetland hydrology in spite of farm use represent a
unique balance between agricultural production and preservation of some of the water
storage and delay, and water quality-related ecosystem services once provided at a
much larger scale in the Willamette Valley lowlands. We anticipate that results of this
work will lead to better understanding of key site-scale edaphic and hydrologic factors
to consider when prioritizing and managing sites for restoration, and how site
disturbance under a variety of land uses may impact different hydrologic processes
and components of the wetland hydroperiod. Additionally, our results provide a
better understanding of how land use affects seasonal runoff generation processes in
mineral flat wetlands, and the water quality implications of modifying groundwater
and surface water connectivity between mineral flats and surrounding surface drainage
networks. / Graduation date: 2012
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Enhancing the predatory potential of hoverflies on aphids in Oregon broccoli fields with floral resourcesAmbrosino, Mario D. 13 March 2006 (has links)
Four key aspects of the relationship between predatory hoverflies and the aphid
pest Brevicoryne brassicae L. on broccoli were investigated in the Willamette Valley,
Oregon USA: 1) the relationship between aphid density and hoverfly oviposition, 2) the
larval voracity of key hoverfly species, 3) the preferences of hoverflies and broccoli pests
for candidate insectary plant species, and 4) the role of insectary plantings in enhancing
hoverfly oviposition in aphid colonies in broccoli fields.
Hoverfly oviposition at two commercial broccoli field sites increased at aphid
densities greater than 50 aphids per plant, but did not peak at the highest aphid densities.
A logistic regression model, selected with Akaike's Information Criterion, of the odds of
oviposition in relation to aphid density included effects for sampling date and aphid
species (B. brassicae and Myzus persicae (Suizer)). The magnitude of the response was
similar for B. brassicae and M persicae. The oviposition response was greater in the
upper part of the plant canopy, and different on individual leaves from that seen on whole
plants.
The voracity and development rate of Scaeva pyrastri (L.) were greater than those
of Eupeodes fumipennis (Thomson), and both exceeded Syrphus opinator Osten Saken
and Sphaerophoria suiphuripes (Thomson). Both E. fumipennis and S. opinator reduced
aphid populations to low levels on plants over two weeks, but E. fumipennis spent much
of the time foraging away form the caged plants.
Alyssum (Lobularia maritima (L.) Desv.), coriander (Coriandrum sativa L.),
buckwheat (Fagropyrum esculentum Moench), and phacelia (Phacelia tanacetifolia
Benth.) were screened for arthropod visitation frequency. The three pest species Pieris
rapae (L.), Diabrotica undecimpunctata undecimpunctata Mannerheim, and Lygus
hesperus Knight visited phacelia the most frequently, while the hoverfly species visited
mostly coriander, which was possibly influenced by competition from other foragers.
Hoverfly oviposition was increased near within-field blocks of alyssum in
broccoli fields at the end of the season however, hoverflies arriving at the field had pollen
in their guts and were oviparous four to five weeks before their eggs were detected in
aphid colonies. This late oviposition may have occurred because threshold densities for
oviposition were not reached until this stage. / Graduation date: 2006
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