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Trinexapac-ethyl and open-field burning in creeping red fescue (Festuca rubra L.) seed production in the Willamette ValleyZapiola, Maria Luz 22 October 2004 (has links)
Open-field burning has been an effective, economical, and widespread
method of post-harvest residue management in creeping red fescue seed
production in the Willamette Valley since the late 1940s. However, the use of field
burning has been legislatively restricted due to air quality and safety issues. The
foliar-applied plant growth regulator trinexapac-ethyl (TE), commercialized in the
USA as Palisade, has been accepted by producers as a yield enhancing agent
and is considered here as an alternative to open-field burning over a four-year
period.
The effects of open-field burning versus mechanical removal (flailing) of
post-harvest residue, and spring versus fall applications of TE on seed yield, dry
matter partitioning, and seed yield components were evaluated in a split-plot
design. The response to the different treatment combinations differed across
years. The young stand responded with a seed yield increase to spring TE
applications, regardless of residue management treatment. However, as the stand
aged, field burning became critical for maintaining high yields and, in 2003 and
2004, only spring TE applications resulted in seed yield increases in burned plots.
The higher potential seed yield achieved in burned plots over flailed plots,
as a result of a higher number of panicles per unit area and spikelets per panicle,
was critical for maintaining high seed yields as the stand aged. Spring
applications of TE, further increased seed yield over the untreated check by
increasing the number of florets per spikelet, reducing fertile tiller height and
lodging and consequently, favoring pollination and fertilization of the florets. Late
spring TE applications also increased 1000-seed weight in 2003 and 2004.
Although spring applications of TE were a promising alternative to open-field
burning early during the life of the stand, as the stand aged they did not
increase seed yield on flailed plots. Fall TE applications did not have a consistent
effect on seed yield, dry matter partitioning or seed yield components, and were
found not to be a viable management practice. / Graduation date: 2005
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Effects of fire on seedling establishment in upland prairies in the Willamette Valley, OregonMaret, Mary P. 17 December 1996 (has links)
Prior to European settlement, native prairie dominated the landscape of the
Willamette Valley. Today, due to urbanization, agriculture, and the cessation of
burning, only isolated remnants of these grasslands still exist. In response to
conservation concerns, there has been a move to restore the remaining prairies in the
Willamette Valley, and prescribed burning and sowing native seed are often top
candidates for grassland restoration. However, the effects of burning on native seedling
establishment and the spread of weedy exotics are largely unknown.
In this study, I investigated how prescribed burning affects native and exotic
species seedling establishment on three upland prairie vegetation types in the Willamette
Valley. The general approach was to sow a known number of seeds from several native
and exotic grassland species into experimentally manipulated plots, designed to separate
the effects of litter removal from the other effects of burning, and to monitor seedling
densities. Germinability and dormancy characteristics of the sowed seeds were also
addressed. An additional study focused on the fire temperatures at soil surface in three
grassland vegetation types and two burn sizes.
Burning increased the establishment of most or all of the sown native species in
the two low quality, exotic grass sites. Exotic seedling establishment also tended to
increase, but did not differ significantly from unburned plots for most species tested. On
the higher quality, native bunchgrass site, burning did not significantly improve native species establishment, but did significantly increase the establishment of short-lived exotic species over those in unburned plots.
The germination and dormancy characteristics of the native and exotic species tested indicate that grasses, both native and exotic, are more likely than forbs to be non-dormant in the autumn following dispersal. Forbs, especially native forbs tend to require cold-stratification for maximum germinability.
During grassland fire, temperatures at soil surface were relatively cool. Fire temperature intensity was highest in the higher quality native bunchgrass vegetation. These burns reached higher temperatures significantly closer to the soil surface than the plot burns in lower quality sites dominated by annual or perennial exotic grasses. Average temperatures in a two hectare broadcast burn and in replicated 2m x 2.5m plot bums in an annual exotic grassland were very similar.
Prescribed burning can be an excellent tool for the restoration of low-quality upland prairies when combined with sowing native seeds in the fall. However, on high-quality prairie, prescribed burning may be a poor restoration choice for promoting native seedlings, as burning promoted weedy species without enhancing native seedling establishment. / Graduation date: 1997
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Effects of ryegrass residue management on Dayton soil organic carbon content, distribution and related propertiesChapin, Michele F. 13 March 1992 (has links)
Total organic carbon, total nitrogen, microbial respiration and enzyme
activity (β-glucosidase) were measured on several horizons of a Dayton silt loam
(fine, montmorillonitic, mesic, Typic Albaqualf) soil cropped to annual ryegrass
under two straw residue management systems. The study evaluated the effects
of annual burning of straw residues or annual incorporation of straw residues on
the content, distribution and bioavailability of soil organic carbon.
Four fields were selected to represent the burn management system which
have been annually burned for a minimum of 40 years. Four fields were selected
to represent the straw incorportated system (mold board plow) which had been
annually burned for approximately 30 years, followed by incorporation of straw
residues into soil for a minimum of 10 years. One native site was selected to
represent non-cultivation conditions.
Straw management system strongly influenced both the total organic C and
N and microbial activity the surface soil horizon. Soil organic C and N content
were significantly greater (p < 0.05) in the Ap horizons of soils under the plowed
management system than soils under the burned management system. The
collective evidence suggests, however, that the significant differences observed
between the two residue management systems are not due to greater losses of
soil organic C and N as a result of burning but rather that organic C levels have
increased as a result of a change in management. Soil C:N ratios are slightly
higher in the Ap horizons of soils as a result of straw residue incorporation in
comparison to burning of straw residues.
When expressed on a mass soil basis, both C0₂ evolution from microbial
respiration, during a 32 day incubation period, and enzyme activity were
significantly greater (p < 0.10) for the Ap horizon of soils where straw residue had
been incorporated than in soils where residues had been annually burned. When
expressed on a per gram C basis, neither C0₂ evolution from microbial respiration
or enzyme activity were significantly different between the two management
systems. These results indicate that long-term annual burning of straw residues
has not decreased the bioavailability of soil organic C. / Graduation date: 1992
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The effect of nitrogen, irrigation, and cultivation on Pinot noir juice and wine composition from the Willamette Valley, OregonWall, Katherine Elizabeth 05 November 2003 (has links)
Graduation date: 2004
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Drivers of arbuscular mycorrhizal fungal community composition in roots : hosts, neighbors, and environmentPhillips, Wendy S. 06 September 2012 (has links)
The vast majority of terrestrial plant species live in symbiosis with arbuscular mycorrhizal fungi (AMF). AMF and plants live in complex networks, with roots of individual plants hosting multiple AMF, and single AMF colonizing multiple plants concurrently. Through the exchange of resources, the two partners of this symbiosis can have great effects on each other, effects which can ripple through both communities. What determines the patterns of associations between the partners is still largely unknown. In this dissertation, I examine a variety of factors, and in particular host identity, that could drive the community composition of AMF in roots.
I began by surveying the diversity of AMF in roots of 12 plant species at a remnant bunchgrass prairie in Oregon, U.S.A. (Chapter 2). To do that, I first designed new primers for use in polymerase chain reaction (PCR) to specifically amplify DNA from all Glomeromycota species. Using those primers, I found 36 distinct AMF phylogenetic groups, or operational taxonomic units (OTUs) in the roots from the
prairie. The proportion of OTUs in the basal order Archaeosporales was greater than in many other environmental surveys. I also conducted an in silico analysis to predict how effectively previously published primers would detect the whole diversity of OTUs I detected.
I then assayed AMF community composition in the roots of 50 plants from nine plant species (Chapter 3). To do that, I designed primers specific to 18 of the OTUs detected in the initial field survey and used them to test for the presence of each OTU in the roots individual plants. I used that data to test if AMF community composition in individual roots correlated with host identity, spatial distribution, or soil characteristics. I found host identity was associated with both the richness and the structure of root AMF communities, while spatial distribution and soil characteristics were not.
Finally, I performed an experimental test of the effect of host identity and community context on AMF community assembly (Chapter 4). I grew plants from four native perennial plant species, including two common and two federally endangered plants, either individually or in a community of four plants (with one plant of each species). I analyzed the AMF community composition in the roots of all plants after 12 weeks of growth with exposure to a uniform mix of field soil as inoculum. I found that host species identity affected root AMF richness and community composition, and community context affected AMF richness. Only one of the endangered species was highly colonized by AMF, and I did not detect unique AMF communities associated with it.
This dissertation provides information on the diversity of AMF at a remnant bunchgrass prairie, an ecosystem which has been the subject of very few studies of AMF. Although a complex mix of factors interact to determine AMF community composition in roots, this work provides strong evidence that host identity plays a major role in that process. / Graduation date: 2013
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The role of body size in the foraging strategies and management of avian herbivores : a comparison of dusky Canada geese (Branta canadensis occidentalis) and cackling geese (B. hutchinsii minima) wintering in the Willamette Valley of OregonMini, Anne E. 11 October 2012 (has links)
Body size explains much of the interspecific variation in the physiology, behavior, and morphology of birds, such as metabolic rate, diet selection, intake rate, gut size, and bill size. Based on mass-specific metabolic requirements and relative energetic costs of activities, being a certain body size has both advantages and disadvantages. In particular, avian herbivores such as geese possess a relatively simple digestive system, consume foods with low digestibility and poor nutrient content, and have increased energetic demands compared to other bird taxa; therefore, any effects of body size on foraging strategies should be readily apparent in this foraging guild. The influence of body size on the behavior and management of Canada Geese (Branta canadensis) and Cackling Geese (B. hutchinsii) as avian herbivores has not been well studied.
My dissertation explores the role of body size in comparative foraging behavior, habitat selection, and winter conservation planning for two congeneric geese, the Dusky Canada Goose (B. c. occidentalis; hereafter Duskys) and the Cackling Goose (B. h. minima; hereafter Cacklers). These two taxa share the same over-winter foraging environment (grass seed fields) in the same restricted geographic area (the Willamette Valley) during winter. Duskys and Cacklers differ by more than a factor of two in body size and have different relative bill sizes and social organization. Because of smaller body size, Cacklers have greater relative energy demands and less fasting endurance compared to Duskys; however, Cacklers have comparatively low energetic costs for flight and transport. Duskys, however, have higher total energy requirements than Cacklers. Additionally, Cacklers form large, high-density flocks and have a total over-wintering population size in the study area of about 200,000. Duskys occur in relatively small family groups and have a total over-wintering population size of about 13,000.
My study demonstrated that interspecific differences in body size between Cacklers and Duskys was associated with differences in foraging behavior, movements, and habitat selection. Cacklers foraged a greater percentage of time (30%) in all habitats and across the entire winter compared to Duskys. Cacklers had higher peck rates (up to 100 pecks min⁻¹ greater) than Duskys in all foraging habitats expect pasture. The pecking rate of Cacklers was greatest in fields of young grass (200 pecks min⁻¹), which may indicate that Cacklers had relatively high intake rates in this foraging habitat. Based on differences in foraging behavior among habitats, Cacklers may have the foraging strategy of energy intake maximizers, whereas the foraging strategy of Duskys is more towards time-energy expenditure minimizers, at least for part of the winter. Cacklers moved across the landscape very differently from
Duskys, exhibiting less site fidelity and greater commuting distances to foraging areas. Cacklers showed a preference for young grass during all periods of the winter, reaffirming that Cacklers are specialized grazers on short green forage, whereas Duskys preferred young grass and pasture. Fields of young grass were the preferred foraging habitat of Cacklers, had less standing crop biomass, and may have enabled higher foraging efficiencies, which may have led to higher intake rates.
The ability of the landscape to support wintering geese changed across the winter because total available plant biomass fluctuated with the rate of grass regrowth. The estimated carrying capacity of the landscape for geese decline by almost one-half during mid-winter (mid-December to mid-February) compared to early winter or late winter periods. Although Cacklers have lower individual energy requirements compared to Duskys, due to a much larger target population size, Cacklers required 89% more foraging habitat than Duskys. Forage requirements encountered a bottleneck during mid-winter, when grass regrowth rates were low and day length was short. Commensurate with this pattern of forage availability, goose body condition declined during the mid-winter period. To support Pacific Flyway target populations for geese, approximately 18,000 ha of total grazing habitat in young and mature grass is needed in the Willamette Valley to support a total over-wintering population composed of 340,000 geese belonging to four subspecies.
The role of body size in influencing the foraging behavior and decisions of over-wintering geese has important implications for conservation planning of goose populations. Small-bodied Cacklers are selective in field choice, yet more likely to
redistribute across the landscape. Disturbances (e.g., hunting, hazing, or predation) will have a disproportionate effect on the movements of smaller-bodied geese compared to larger geese. These characteristics of Cacklers will make conservation planning to retain geese on public land more difficult. Coordinated management with private landowners and farming practices that maximize preferred goose foraging habitat on public lands may attract geese to utilize protected areas and minimize conflicts with agriculture in the Willamette Valley. Availability of resources during critical periods in winter is an important factor affecting the distribution of geese, but may affect small and large bodied geese differently. Management could be targeted during these critical time periods. By considering the role of body size in the context of life history characteristics, foraging behavior and habitat selection, appropriate management strategies can be developed and implemented to reduce the effects of agricultural depredation by geese, while promoting the future conservation of wintering geese in the Willamette Valley. / Graduation date: 2013
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Determinants of off-farm labor supply among farm households in the north Willamette ValleyDoyle, Douglas J., 1963- 10 August 1987 (has links)
Financial stress in agriculture has been a concern over the past
century. Agrarian values and "love of the land" seem to yield public
conclusions for the support of the industry. Much of this support is
in the interest of preserving a viable food producing sector in an
volatile world climate. High interest rates, declining land values
and highly competitive export markets have spurred renewed concern
for farm survival in the past ten years.
One alternative to traditional price supports and tariffs for
farm household support is off-farm income. This may take many forms
including off-farm wages and salaries, rental income, interest and
dividend income and, retirement or pension funds. Central to the
analysis of nonfarm income generation is the allocation of time by
farm households. For farmers who place a high value on the farm
lifestyle, occupational choice is embedded in the time decision to
such an extent that the resource allocations based on economic efficiency
criteria may be altered.
Tobit techniques offer a new approach to the analysis of farm
household decisions on time allocation. The procedure allows the investigator
to estimate and evaluate parameters that may affect the
amount of off-farm work by farm household members. The Tobit
analysis is designed for censored data sets. The data in this study
were censored because there were missing observations on the quantity
of off-farm work for those individuals who did not work off-farm in
1986.
Results of Tobit analyses of off-farm work by farm operators and
spouses in three Oregon counties indicated that high levels of gross
farm income reduce the likelihood and extent of off-farm work.
Middle-aged operators worked off-farm more while the presence of
small children and elderly dependents in the farm household inhibited
off-farm work. The allocation decisions of the spouse and the
operator appeared to be independent; this supports a nonsimultaneous
Tobit specification like the one used in this research. / Graduation date: 1988
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The similarity of texted musical grammar to oral communication : exploring grammar, text and content with examples from fieldwork with Grupo KulturaHerrera, Tere Lynn 08 August 1997 (has links)
The goal of this study is to elucidate the similarities between the grammar of
oral folk music and oral language grammar through field examples from Grupo
Kultura, a group of neo-Latin American musicians in the mid-Willamette Valley area
of Oregon.
The linguistic analysis of oral folk music explores textual and contextual
issues which serve to highlight the need to include such forms of communication as
music in an expanded view of "language." It suggests both fluid and non-fluid
boundaries between spoken language and oral folk music. Of particular emphasis
are the potential ability of music to express deep emotional content in music and the
possible decoding of that content's musical meaning.
Data was collected through ethnographic interviews and participant
observation. / Graduation date: 1998
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Sweet corn decline syndrome in Oregon's Willamette ValleyHoinacki, Elisabeth V. 02 June 2003 (has links)
Graduation date: 2004
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Chronology and Ecology of Late Pleistocene Megafauna in the Northern Willamette Valley, OregonGilmour, Daniel McGowan 01 January 2011 (has links)
This study is an investigation of the timing of extinction of late Pleistocene, large bodied mammalian herbivores (megafauna) and of the environment in which they lived. The demise of the megafauna near the end of the Pleistocene remains unexplained. Owing to potential human involvement in the extinctions, archaeologists have been particularly concerned to understand the causes for faunal losses. Our current lack of understanding of the timing and the causes of the extinctions in North America may result from a deficiency in understanding the histories of each individual species of extinct animal on a local level. Detailed regional chronologies of fauna are necessary for comparison with paleoenvironmental and archaeological data to help sort out causes for extinction. The Willamette Valley of western Oregon has long been noted for finds of megafauna, though records have not been synthesized since the early 20th century and these materials have remained largely unstudied. In this thesis, I first create a catalog of extinct megafauna recovered from the Willamette Valley. Next, using material from the northern valley, I employ AMS radiocarbon dating, stable isotope δ¹³C and δ¹⁵N analyses, and gross inferences based on the dietary specializations and habitat preferences of taxa in order to reconstruct environments and to develop a local chronology of events that is then arrayed against archaeological and paleoenvironmental data. The results of this study indicate that megafaunal populations in the northern Willamette Valley were contemporaneous with the earliest known human populations of the Pacific Northwest, as well as later populations associated with the Clovis Paleoindian Horizon. Consistent with the overkill hypothesis, radiocarbon ages span the length of the Clovis window, but no ages are younger than Clovis. Moreover, all radiocarbon ages are older than or contemporaneous to the onset of the Younger Dryas Stadial. No age ranges fall exclusively within the Younger Dryas. Comparison of megafaunal ages and paleoenvironmental records support the view that climate change contributed to local animal population declines. Prior to ~13,000 cal BP, the Willamette Valley was an open environment; herbivores mainly consumed C₃ vegetation. The timing of the loss of megafauna coincides with increased forested conditions as indicated by regional paleoenvironmental reconstruction. As the timing of megafaunal decline correlates with Clovis, the onset of the Younger Dryas, and increased forested conditions, it is not possible with the data currently available to distinguish the cause of extinction in the Willamette Valley. The age ranges of the fauna coupled with taphonomic and geologic context indicate that the fauna are autochthonous to the Willamette Valley; they do not represent ice rafted carcasses or isolated skeletal elements transported from elsewhere during late Pleistocene glacial outburst floods.
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