Index Catalog // ScholarsArchive@OSU

Dynamic seascapes : a quantitative framework for scaling pelagic ecology and biogeochemistry

Creator:: Kavanaugh, Maria T.
Abstract:: Understanding and modeling microbial responses and feedbacks to climate change is hampered by a lack of a framework in the pelagic environment by which to link local mechanism to large scale patterns. Where terrestrial ecology draws from landscape theory and practice to address issues of scale, the pelagic seascape concept...
Resource Type:: Dissertation
Full Text:: Abstract approved: _____________________________________ Ricardo M Letelier Understanding and

Marine Nitrogen Subsidies to Terrestrial Systems: Transport Through Wrack Deposition

Creator:: Traylor, Andrew
Abstract:: Fluctuations in one system affect adjacent systems; mechanistic understanding of linkages helps conservation efforts be more effective by focusing on influential species and areas that facilitate connections between ecosystems. This study explored marine-derived nutrient inputs to adjacent terrestrial communities. We quantified wrack (seaweed and other organic matter) deposition at sites...
Resource Type:: Honors College Thesis
Full Text:: : _______________________________________________________________ Ricardo Letelier Abstract body

A study on the effects of enhanced pCO2 on open ocean diazotrophic assemblages

Creator:: Gradoville, Mary Rose
Abstract:: Biological di-nitrogen (N₂) fixation is a key process in open-ocean ecosystems, where the new nitrogen (N) provided by marine diazotrophs can support a large fraction of primary productivity and carbon (C) drawdown. Recent laboratory studies have shown that elevated pCO₂ enhances the rate of N₂ fixation by select laboratory isolates...
Resource Type:: Masters Thesis
Full Text:: : _____________________________________________________________________ Ricardo M. Letelier Biological di-nitrogen (N2) fixation is a key process in open-ocean

Phosphorus physiology and environmental forcing of oceanic cyanobacteria, primarily Trichodesmium spp.

Creator:: White, Angelicque E.
Abstract:: The biological transformation of dinitrogen gas (N2) into combined forms(termed N2 fixation) by certain genera of oceanic cyanobacteria represents the largest incoming flux of nitrogen to the global ocean. As such, biological nitrogen fixation plays a significant role in the regulation of oceanic productivity and the export of carbon and...
Resource Type:: Dissertation
Full Text:: : _____________________________________________________________________ Ricardo M. Letelier Yvette H. Spitz The biological

Primary production dynamics in the North Pacific subtropical gyre

Creator:: Corno, Guido
Abstract:: The North Pacific subtropical gyre (NPSG), once considered to be a biological desert due to low primary production (PP) and its associated variability, has been found more productive and variable than previously thought. The environmental conditions controlling this relatively high PP variability are yet to be elucidated, despite important implications...
Resource Type:: Dissertation
Full Text:: : _____________________________________________________________________ Mark R. Abbott, Ricardo M. Letelier The North Pacific subtropical gyre (NPSG), once

Seconds to hour scale photosynthetic responses in marine microalgae

Creator:: Laney, Samuel R.
Abstract:: Our view of phytoplankton has historically revolved around their inability to control their location in space. The term phytoplankton itself underscores this particular difference between phytoplankton and their sessile terrestrial counterparts. Yet there are other differences between land plants and the phytoplankton that are perhaps equally important, beyond this sessile-planktonic...
Resource Type:: Dissertation
Full Text:: . CONTRIBUTION OF AUTHORS Contributions and advice by Ricardo M. Letelier and Mark R. Abbott were central

Phosphorus control of nitrogen fixation

Creator:: Watkins-Brandt, Katie S.
Abstract:: Under conditions of fixed N-limitation, as with most oligotrophic systems, the process of biological N₂ fixation (diazotrophy) is favored, provided the necessary trace elements and vitamins are sufficient. Despite the well understood contributions of N₂ fixation in oligotrophic regions, the nutritional and ecological controls of marine diazotrophs have not been...
Resource Type:: Masters Thesis
Full Text:: : Angelicque E. White Ricardo M. Letelier Yvette H. Spitz Under conditions of fixed N

Functional groups, traits, and the performance of species in restoration

Creator:: Roberts, Rachael E. (Rachael Elaine)
Abstract:: In ecological restoration, species that are sown to increase the native plant diversity range in establishment ability. Some species readily establish, while others rarely do. This study set out to investigate some of the potential processes influencing species establishment, as well as the traits that are associated with the success...
Resource Type:: Masters Thesis
Full Text:: members of my committee, Eric Seabloom and Ricardo Letelier also provided great suggestions and helped

The Impact of Surface Ocean Mixing on Phytoplankton Communities and Associated Carbon Pools

Creator:: VerWey, Brian J.
Abstract:: Deep mixing events in the ocean’s surface layer act as physical drivers of carbon export by detraining dissolved and particulate organic matter, including surface phytoplankton communities, to depth. Once removed from the sunlit surface ocean environment, phytoplankton accumulation rates are dependent on the relative contributions of loss processes, such as...
Resource Type:: Masters Thesis
Full Text:: those that have provided pivotal insights along the way, including Dr. Ricardo Letelier, for your

Nitrogen isotopes in a global ocean biogeochemical model : constraints on the coupling between denitrification and nitrogen fixation

Creator:: Somes, Christopher J.
Abstract:: We present a new nitrogen isotope model incorporated into the three-dimensional ocean component of a global Earth System Climate Model designed for millennial timescale simulations. The model includes prognostic tracers for the stable nitrogen isotopes, ¹⁴N and ¹⁵N, in the nitrate (NO₃ˉ), phytoplankton, zooplankton, and detritus variables of the marine...
Resource Type:: Masters Thesis
Full Text:: invaluable to my growth as a scientist. I would like to thank my committee members Alan Mix and Ricardo

The Role of Iron: How Natural and Human-Induced Iron Fertilization Could Change Ocean Productivity

Creator:: Adroli, Nurmalia
Abstract:: Iron (Fe) is an important limiting nutrient that can affect the rate of ocean primary production because it is required by phytoplankton as an enzymatic cofactor in photosynthesis, nitrogen fixation, and other essential metabolic functions. Most Fe reaches the surface of the open ocean via atmospheric dust deposition, which is...
Resource Type:: Masters Thesis
Full Text:: advising committee, Prof. Michael Harte and Prof. Ricardo Letelier: thank you very much for your

Jet stream intraseasonal oscillations drive dominant ecosystem variations in Oregon’s summertime coastal upwelling system

Creator:: Bane, John M., Spitz, Yvette H., Letelier, Ricardo M., and Peterson, William T.
Abstract:: Summertime wind stress along the coast of the northwestern United States typically exhibits intraseasonal oscillations (ISOs) with periods from ≈15 to 40 days, as well as fluctuations on the 2- to 6-day “weather-band” and 1-day diurnal time scales. Coastal upwelling of cool, nutrient-rich water is driven by extended periods of...
Resource Type:: Article
Full Text:: ‡, Ricardo M. Letelier‡, and William T. Peterson§ *Department of Marine Sciences, University of North

The ecology of ocean acidification : integrating the effects of pH variation among other environmental stressors on biogeography and organismal performance in rocky intertidal communities

Creator:: Rose, Jeremy M.
Abstract:: Ocean Acidification (OA) has emerged as a major threat to marine ecosystems, particularly regarding calcifying organisms. A growing body of literature describing laboratory investigations into pH stress indicates broadly deleterious effects for calcifiers, but responses vary greatly across taxa and can be influenced by variations in other environmental characteristics. Scaling...
Resource Type:: Dissertation
Full Text:: , Kirsten has been a great friend, confidante and scientific mentor. Ricardo Letelier has always expanded

Fungal Secondary Metabolism of Basidiobolus meristosporus: a Novel Natural Product Reservoir

Creator:: Trautman, Ian A.
Abstract:: Secondary metabolites (SMs) play an integral role in the life history of most fungal species. Fungal metabolomic studies provide insights into how fungi perform certain ecological functions, how they compete and interact with other organisms, and the breadth of fungal chemodiversity. Fungal SMs have also been utilized for a variety...
Resource Type:: Masters Thesis
Full Text:: goes out to my committee members Drs. Jessie Uehling and Ricardo Letelier as well, for the time and

Quantification of dry concentration factor for Cs-134 in marine diatom Thalassiosira Weissflogii

Creator:: Krzyaniak, Nathan Anthony
Abstract:: The Fukushima Daiichi nuclear disaster of 2011 made it apparent that releases of fission products to marine environments is a very real possibility. Additional data on the movement of material through marine environments can be used by radioecology personnel to assist with both ecosystem protection as well as environmental cleanup...
Resource Type:: Masters Thesis
Full Text:: , Ocean, and Atmospheric Sciences. These members include, but are not limited to, Dr. Ricardo Letelier

Photosynthetic Energy Allocation Strategies of Thalassiosira pseudonana During Light Limited Growth

Creator:: Fisher, Nerissa L.
Abstract:: Photosynthetic energy allocation strategies were investigated in the marine diatom, Thalassiosira pseudonana, grown under a wide range of light limitation. Steady-state, continuous cultures were established at three light-limited growth rates. Simultaneous measurements of photosynthetic activity were made that targeted different points in photosynthetic energy flow from gross to net photosynthesis....
Resource Type:: Masters Thesis
Full Text:: µmol photons m-2 s-1 that is a measure of light energy and intensity. A more complicated example

Production and partitioning of organic matter during simulated phytoplankton blooms

Creator:: Wetz, Michael S.
Abstract:: Few studies have examined the partitioning of organic matter in upwelling systems, despite the fact that these systems play a key role in carbon and nitrogen budgets in the ocean. We examined the production and partitioning of phytoplankton-derived organic matter in deck incubations off Oregon during the upwelling season. During...
Resource Type:: Masters Thesis
Full Text:: also thank my committee members, Ricardo Letelier, Evelyn Sherr, and Fred Prahl, for their willingness

Parameterizing the natural fluorescence kinetics of Thalassiosira weissflogii

Creator:: Laney, Samuel R., Letelier, Ricardo M., and Abbott, Mark R.
Abstract:: We examined variability in the natural fluorescence yield of a neritic diatom, Thalassiosira weissflogii, in continuous cultures. In this species, kinetics in natural fluorescence yield over time scales less than a photoperiod were characterized by sharp decreases, occurring at irradiance intensities that presumably coincide with the onset of nonphotochemical fluorescence...
Resource Type:: Article
Full Text:: Laney, S. R., R. M. Letelier, and M. R. Abbott. Parameterizing the

GradovilleMaryCEOASPhysiologicalResponseCrocosphaera.pdf

Creator:: Gradoville, Mary R., White, Angelicque E., and Letelier, Ricardo M.
Abstract:: We investigated the effects of elevated pCO₂ on cultures of the unicellular N₂-fixing cyanobacterium Crocosphaera watsonii WH8501. Using CO₂-enriched air, cultures grown in batch mode under high light intensity were exposed to initial conditions approximating current atmospheric CO₂ concentrations (~400 ppm) as well as CO₂ levels corresponding to low- and...
Full Text:: *, Angelicque E. White, Ricardo M. Letelier Oregon State University, College of Earth, Ocean, and Atmospheric

GradovilleMaryCEOASPhysiologicalResponseCrocosphaera_TableS1.pdf

Creator:: Gradoville, Mary R., White, Angelicque E., and Letelier, Ricardo M.
Abstract:: We investigated the effects of elevated pCO₂ on cultures of the unicellular N₂-fixing cyanobacterium Crocosphaera watsonii WH8501. Using CO₂-enriched air, cultures grown in batch mode under high light intensity were exposed to initial conditions approximating current atmospheric CO₂ concentrations (~400 ppm) as well as CO₂ levels corresponding to low- and...

Physiological Response of Crocosphaera watsonii to Enhanced and Fluctuating Carbon Dioxide Conditions

Creator:: Gradoville, Mary R., White, Angelicque E., and Letelier, Ricardo M.
Abstract:: We investigated the effects of elevated pCO₂ on cultures of the unicellular N₂-fixing cyanobacterium Crocosphaera watsonii WH8501. Using CO₂-enriched air, cultures grown in batch mode under high light intensity were exposed to initial conditions approximating current atmospheric CO₂ concentrations (~400 ppm) as well as CO₂ levels corresponding to low- and...
Resource Type:: Article

Electrolyte Design: Improving Capacity and Structural Stability of Electrodes

Creator:: Xu, Yunkai
Abstract:: The grand plan of carbon neutralization and COP26 in Glasgow require a quick shift of energy sources from conventional fossil fuel to a more renewable substitute such as wind, or solar energy. However, the intermittency of those renewable energy sources does not meet the demand of the energy, which requires...
Resource Type:: Dissertation
Full Text:: thank my committee members Dr. Zhenxing Feng, Dr. Ricardo M Letelier, and Dr. Chong Fang for devoting

Prokaryotes associated with marine crust

Creator:: Mason, Olivia Underwood
Abstract:: Oceanic crust covers nearly 70% of the Earth's surface, of which, the upper, sediment layer is estimated to harbor substantial microbial biomass. Marine crust; however, extends several kilometers beyond this surficial layer, and includes the basalt and gabbro layers. In particular, the basalt layer has high permeabilities which allows for...
Resource Type:: Dissertation
Full Text:: also like to thank my committee members, Drs. Michael S. Rappé, Ricardo M. Letelier, Mario E. Magana

Storage Battery Chemistries with Earth Abundant Charge Carriers

Creator:: Hong, Jessica Junghwa
Abstract:: The demand for the development of sustainable energy is an all time high as we burn through limited fossil fuel reserves and as environmental concerns rise every year. Renewable energy sources such as wind and solar power have limitations due to inconsistent power supply that cannot meet the regular needs...
Resource Type:: Dissertation
Full Text:: . Ricardo Letelier. They have always made time for the committee meetings and kept me on track with the

Phylogenetic Studies in Tenebrionidae (Coleoptera) and Related Families

Creator:: Kanda, Kojun
Abstract:: In this dissertation, I present the results from three studies: (1) a phylogeny of Tenebrionoidea (Coleoptera) inferred from a seven-gene dataset derived from PCR and Sanger sequencing; (2) a phylogeny of Tenebrionidae, the largest family in Tenebrionoidea, inferred from a four-gene dataset also derived from PCR and Sanger sequencing; (3)...
Resource Type:: Dissertation
Full Text:: . Stevan Arnold, Scott Baker, Ricardo Letelier, Aaron Liston, Dave Lytle

Experimental assessment of diazotroph responses to elevated seawater pCO₂ in the North Pacific Subtropical Gyre

Creator:: Böttjer, Daniela, Karl, David M., Letelier, Ricardo M., Viviani, Donn A., and Church, Matthew J.
Abstract:: We examined short-term (24–72 h) responses of naturally occurringmarine N2 fixing microorganisms (termed diazotrophs) to abrupt increases in the partial pressure of carbon dioxide (pCO2) in seawater during nine incubation experiments conducted between May 2010 and September 2012 at Station ALOHA (A Long-term Oligotrophic Habitat Assessment) (22°45′N, 158°W) in the...
Resource Type:: Article
Full Text:: elevated seawater pCO₂ in the North Pacific Subtropical Gyre Böttjer, D., D. M. Karl, R. M. Letelier, D

Relationships of in situ spectral absorption, pigment ratios and environmental parameters for phytoplankton assemblages in coastal waters

Creator:: Eisner, Lisa B.
Abstract:: In situ optical measurements of spectral absorption and beam attenuation provide information on the fine scale horizontal and vertical variations in phytoplankton pigments and other measures of phytoplankton photophysiology and ecology in coastal waters. Phytoplankton pigment ratios from discrete sample analyses with High Performance Liquid Chromatography were compared to in...
Resource Type:: Dissertation
Full Text:: examples to follow. I thank Pat Wheeler, Ricardo Letelier, Ron Zaneveld, Scott Pegau and Steve Giovannoni

Disease models and infectious phenotypes of Mycobacterium avium subspecies paratuberculosis

Creator:: Everman, Jamie L.
Abstract:: Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of Johne's disease, a chronic inflammatory bowel disease that affects ruminant populations worldwide. The characteristic stages of the disease make diagnosis difficult, resulting in silent transmission among animals in a herd for years before proper detection of the infection. The extensive...
Resource Type:: Dissertation
Full Text:: . Lia Danelishvili and Dr. Ricardo Letelier for their support and input to my projects. I would like

The role of herbivores and productivity on community structure of rocky shores of the Galapagos Islands, Ecuador

Creator:: Vinueza, Luis R.
Abstract:: Ecosystems are facing increasing threats from human related activities, such as overfishing, pollution, habitat destruction, species invasions, and diseases, among others. While oceanic islands provide natural laboratories to understand ecological and evolutionary process, they are also particularly vulnerable to these impacts, given their usual isolation from the mainland and the...
Resource Type:: Dissertation
Full Text:: and suggestions about how to improve my research, and Scott Heppell and Ricardo Letelier for

Comparative Metagenomic Investigations Link the Functional Capacity of the Gut Microbiome to Vertebrate Physiology

Creator:: Armour, Courtney R.
Abstract:: Microscopic organisms inhabit virtually every niche on this planet, where they perform functions vital to all life on earth. Accordingly, humans host a complex community of microorganisms (i.e. the gut microbiome) that inhabit the gastrointestinal tract and modulate host physiology. Insight into the specific mechanisms through which gut microbes influence...
Resource Type:: Dissertation

New Insights on the Southern Ocean Carbon Cycle from Biogeochemical Argo Floats

Creator:: Williams, Nancy L.
Abstract:: The Southern Ocean plays an important role in the ocean’s uptake of heat and carbon yet the processes controlling this uptake are not well understood. To date, more than 100 biogeochemical profiling floats that measure water column pH, oxygen, nitrate, fluorescence, and backscattering at 10-day intervals have been deployed throughout...
Resource Type:: Dissertation
Full Text:: other members of my committee: Richard Feely, Burke Hales, and Ricardo Letelier. You have challenged

Late Quaternary paleoceanography of the Northeast Pacific and Atlantic Oceans based on diatom transfer functions

Creator:: Lopes, Cristina Isabel Coelho Dias
Abstract:: Modern upwelling conditions and corresponding oceanographic properties are investigated and reconstructed for the Late Quaternary. The oceanographic conditions considered influence diatom ecology and the record of fossil diatom frustules in the sediments. Diatoms from modern sediments are evaluated as paleoceanographic proxies and transfer functions (TFs) are calibrated using the Imbrie...
Resource Type:: Dissertation
Full Text:: committee members Nicklas Pisias, Ricardo Letelier, Peter Clark and Stephen Giovannoni and to Jim McManus

Satellite observations of the inﬂuence of mesoscale ocean eddies on near-surface temperature, phytoplankton and surface stress

Creator:: Gaube, Peter
Abstract:: The influence of mesoscale ocean eddies on near-surface ocean temperature, surface stress and phytoplankton communities is investigated by collocating numerous satellite measurements along with vertical profiles of oceanic temperature and salinity to the interiors of eddies identified and tracked in altimetric sea surface height maps. The surface currents associated with...
Resource Type:: Dissertation
Full Text:: role model and a friend, for this I’m grateful. My committee, Michael Behrenfeld, Ricardo Letelier

Evolutionary Dynamics of Genomes and Endosymbionts in Plant-Parasitic Nematodes

Creator:: Wasala, Wasala Mudiyanselage Sulochana K.
Abstract:: Plant-parasitic nematodes cause more than US $100 billion in annual agriculture loss worldwide. Thorough knowledge of their genetic diversity, and interactions with endosymbionts and environment have the potential to provide valuable insights into the basic biology of these animals, and assist future efforts aimed at management of these plant parasites....
Resource Type:: Dissertation
Full Text:: and Ricardo Letelier for serving on my graduate committee and for their valuable input to make

Phytoplankton shading of marine benthic macrophytes: Implications for intertidal community structure

Creator:: Kavanaugh, Maria T.
Abstract:: Previous observations of light levels and phytoplankton abundances along the Oregon coast demonstrated that phytoplankton attenuated light sufficiently to potentially limit the growth of intertidal macrophytes and therefore structure local intertidal communities. Inspired by this observation, in spring 2004, I initiated a study to quantify the direct and indirect benthic...
Resource Type:: Masters Thesis
Full Text:: included Dr. Karina Nielsen, my minor professors- Dr. Ricardo Letelier (Oceanography) and Dr. Lisa Madsen

Dynamics of organic matter production and degradation during coastal diatom blooms

Creator:: Wetz, Michael S.
Abstract:: Experiments were designed to answer key questions about diatom-derived organic matter cycling (i.e., production and degradation) in coastal systems. Dissolved organic matter (DOM) production was examined in axenic batch cultures of five diatom species. Dissolved organic carbon (DOC) release rates varied between species, but were significantly higher for all species...
Resource Type:: Dissertation
Full Text:: ) Ricardo Letelier, who was one of the first faculty here other than Pat who I had significant

Ecology and Environmental Controls of Two Keystone Groups of Oceanic Microorganisms : Diazotrophs and Pathogenic Vibrio

Creator:: Gradoville, Mary Rose
Abstract:: Marine bacteria play vital roles in every niche of the ocean, from small-scale symbioses to large-scale productivity and the regulation of Earth’s climate. Recent advances in molecular tools now allow us to probe the genetic potential of entire microbial communities. The next step is linking these diverse communities to the...
Resource Type:: Dissertation

Phenology of particle size distributions and primary productivity in the North Pacific subtropical gyre (Station ALOHA)

Creator:: White, Angelicque E., Letelier, Ricardo M., Whitmire, Amanda L., Barone, Benedetto, Bidigare, Robert R., Church, Matthew J., and Karl, David M.
Abstract:: The particle size distribution (PSD) is a critical aspect of the oceanic ecosystem. Local variability in the PSD can be indicative of shifts in microbial community structure and reveal patterns in cell growth and loss. The PSD also plays a central role in particle export by influencing settling speed. Satellite-based...
Resource Type:: Article
Full Text:: ., Letelier, R. M., Whitmire, A. L., Barone, B., Bidigare, R. R., Church, M. J., & Karl, D. M. (2015

Particle distributions and dynamics in the euphotic zone of the North Pacific Subtropical Gyre

Creator:: Barone, Benedetto, Bidigare, Robert R., Church, Matthew J., Karl, David M., Letelier, Ricardo M., and White, Angelicque E.
Abstract:: During the summer of 2012, we used laser diffractometry to investigate the temporal and vertical variability of the particle size spectrum (1.25–100 µm in equivalent diameter) in the euphotic zone of the North Pacific Subtropical Gyre. Particles measured with this optical method accounted for ∼40% of the particulate carbon stocks...
Resource Type:: Article
Full Text:: ., Letelier, R. M., & White, A. E. (2015). Particle distributions and dynamics in the euphotic zone of the

Role of late winter mesoscale events in the biogeochemical variability of the upper water column of the North Pacific Subtropical Gyre

Creator:: Letelier, Ricardo M., Karl, David M., Abbott, Mark R., Flament, P., Freilich, Michael H., Lukas, Roger, and Strub, P. Ted
Abstract:: Continuous records of upper water column (0–150 m) temperature profiles, spectral distribution of downwelling irradiance, and phytoplankton solar-induced fluorescence at 25 m depth were obtained during the inaugural deployment of the Hawaii Air-sea Logging Experiment, A Long-term Oligotrophic Habitat Assessment (HALE ALOHA) mooring, near the Hawaii Ocean Time-series (HOT) Station...
Resource Type:: Article

Physiological impacts of groundwater and surface water application on desert graminoids of different geographic origin

Creator:: Abdallah, Mohamed (Mohamed Ahmed B.)
Abstract:: Desert plant communities are among the most sensitive to changes in soil water conditions. In areas with shallow aquifers, it is important to understand both the effects of groundwater alterations on vegetation and how changes in surface-soil water affect plant water uptake. Studies in arid environments have evaluated the effect...
Resource Type:: Masters Thesis
Full Text:: : Ricardo Mata-Gonzalez Desert plant communities are among the most sensitive to changes in soil water

Geographic variation in distribution and cover of principle native and non-native plant species along gradients of topography, climate, and disturbance in protected-area sagebrush steppe communities of the Columbia Plateau

Creator:: Esposito, Daniel M.
Abstract:: The sagebrush steppe ecosystem of the Columbia Plateau has become degraded by a long history of alternative land use and associated perturbations. Protection of remnant stands of intact sagebrush steppe currently relies upon their preservation within the nation's network of parks and protected-areas. The John Day Fossil Beds National Monument,...
Resource Type:: Masters Thesis
Full Text:: AN ABSTRACT OF THE THESIS OF Daniel M. Esposito

Long-term Fire Effects on Plant Succession and Exotic Weeds in Protected Area Sagebrush Steppe, John Day Fossil Beds National Monument, Oregon

Creator:: Reed-Dustin, Claire Marie
Abstract:: The historical function of fire in sagebrush steppe has been altered by 19th century overgrazing, active fire suppression, annual grass invasion and encroachment of woody species. The significance of fire to these systems is known, but research on long-term fire effects are limited. The Sheep Rock management unit of the...
Resource Type:: Masters Thesis
Full Text:: , Oregon Abstract approved: ________________________________________________________ Ricardo Mata

An optimization model to allocate forestry incentives funds in teak plantations of the southern-coastal region of Guatemala

Creator:: Pavez, Ricardo
Abstract:: Guatemala is internationally recognized as a country suitable to invest in the forestry industry. The first Guatemalan Forest Incentive Program – PINFOR- was implemented in 1996 to foster local forestry through cost-sharing. However, it lacks both formal land use planning processes and mechanisms to assess economic potential of projects, so...
Resource Type:: Masters Thesis
Full Text:: Ricardo Pavez for the degree of Master of Science in Sustainable Forest Management presented on June 12th

Kinematics and Dynamics of a Model Eastern-boundary Poleward Undercurrent

Creator:: Duran, Rodrigo
Abstract:: A carefully calibrated primitive-equation model from 41°N to 48°N is used to study the poleward undercurrent off the US west coast. Chapter 2 describes poleward flow over the slope from Eulerian and Lagrangian perspectives. The model is robust, in the sense of several characteristics being qualitatively consistent with observational and...
Resource Type:: Dissertation
Full Text:: approved: Roger M. Samelson A carefully calibrated primitive-equation model from 41ıN to 48ıN is used to

The Social Interactions of Pseudomonas aeruginosa

Creator:: Smith, Parker
Abstract:: Pseudomonas aeruginosa is a ubiquitous environmental microbe, opportunistic pathogen, and a highly social organism. P. aeruginosa utilizes a wide array of cooperative behaviors to adapt to the environmental conditions around it. These behaviors include quorum sensing (QS), a form a cell-to-cell signaling that coordinates the expression of secreted products in...
Resource Type:: Dissertation
Full Text:: . Ricardo Letelier, who have generously given their time and expertise to better my work. Additional

Biomass production and water use of common plant species in Owens Valley, California, USA

Creator:: Evans, Tracie L.
Abstract:: This study evaluated biomass production, water-use efficiency (WUE), biomass allocation, and water use characteristics of common plant species in Owens Valley, California, USA. The species studied were the grasses Distichlis spicata, Leymus triticoides, and Sporobolus airoides, the forbs Glycyrrhiza lepidota, Juncus arcticus, and Salsola tragus (annual), the desert shrubs Artemisia...
Resource Type:: Masters Thesis
Full Text:: approved: _________________________________________________________________ Ricardo Mata-González

Mycorrhizal Fungi on the Sagebrush Steppe: Benefits for Restoring Keystone Rangeland Plant Species

Creator:: Prado-Tarango, David E.
Abstract:: Arbuscular mycorrhizal fungi (AMF) are plant symbionts that associate with the vast majority of terrestrial plants species. The AMF colonizes the plant roots by penetrating the root cortical cells, where the fungi exchanges mineral nutrients with the host plant for photosynthates. This association exists as a complex system in which...
Resource Type:: Dissertation
Full Text:: : ______________________________________________________ Ricardo Mata-González Arbuscular mycorrhizal fungi (AMF) are plant symbionts that

Ecosystem Processes in Treated and Untreated Western Juniper Systems in Semiarid Watersheds: A Paired Watershed Study in Central Oregon

Creator:: Abdallah, Mohamed AB.
Abstract:: Western juniper (Juniperus occidentalis) encroachment has been associated with negative ecological and hydrological consequences including reductions in herbaceous production and diversity, deterioration for wildlife habitat, and higher erosion and runoff potentials. As a result, western juniper removal is a common and accepted rangeland management practice. Although studies evaluating the ecological...
Resource Type:: Dissertation
Full Text:: . Abstract approved: Ricardo Mata-Gonzalez Western juniper (Juniperus occidentalis

Vegetation as Impacted by Soil Characteristics and Moisture in a Conservation Wetland, Willamette Valley, OR

Creator:: Aslan, Fevziye
Abstract:: Wetland degradation has negative influences on wetland functions and services. The understanding of wetland functions requires the intersection of two science disciplines, ecohydrology and plant physiology for a correct approach on wetland restoration and management. Although studies assessing ecohydrological relationships to protect wetlands are relatively common, studies evaluating both ecohydrological...
Resource Type:: Masters Thesis
Full Text:: Ricardo Mata-Gonzalez Wetland degradation has negative influences on wetland functions and

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