Sustaining forest resources requires a better understanding of forest ecosystem processes, and how management decisions and climate change may affect these processes in the future. While plot and inventory data provide our most detailed information on forest carbon, energy, and water cycling, applying this understanding to broader spatial and temporal...
Disturbance events strongly affect the composition, structure, and function of forest ecosystems; however, existing US land management inventories were not designed to monitor disturbance. To begin addressing this gap, the North American Forest Dynamics (NAFD) project has examined a geographic sample of 50 Landsat satellite image time series to assess...
Free and open access to satellite imagery and value-added data products have revolutionized the role of remote sensing in Earth system science. Nonetheless, rapid changes in the global environment pose challenges to the science community that are increasingly difficult to address using data from single satellite sensors or platforms due...
The history of forest change processes is written into forest age and distribution and affects earth systems at many scales. No one data set has been able to capture the full forest disturbance and land use record through time, so in this study, we combined multiple lines of evidence to...
Because it is an important regulator of terrestrial carbon cycling in North America, extensive research on natural and human disturbances has been carried out as part of the North American Carbon Program and the CarboNA project. A synthesis of various components of this research was carried out, and the results...
Evidence of shifting dominance among major forest disturbance agent classes regionally to globally has been emerging in the literature. For example, climate-related stress and secondary stressors on forests (e.g., insect and disease, fire) have dramatically increased since the turn of the century globally, while harvest rates in the western US...
Samples of benthic organisms off the coast of Oregon, taken
from depths varying from 50 to 2900 meters, have been analyzed in
terms of diversity at a given station, and similarity and ecological
distance to other stations. Estimates of epifauna abundance were
also made. In the analysis an important distinction...
Endophytes, foliage inhabiting fungi, are an unexplored source of fungal biodiversity and a potential resource for the production of bioactive natural products. In this research, leaf tissues from the species Arbutus menziesii, Rhododendron macrophyllum and the genus, Ilex and Salix were collected for the isolation of endophytic fungi. Fungal extracts...
Organophosphate insecticides may produce sublethal, adverse effects on salmonid
growth, reproduction, maturation, swimming, and feeding. Chlorpyrifos, an
organophosphate insecticide, was detected by the Oregon Department of Environmental
Quality in the Hood River and tributaries during March 1999 at levels exceeding state
water quality standards in the range of 0.011-0.482 μg/L....
The effect of physical factors such as soil structure, bulk density, parent material, and topographic variables on soil C and N dynamics and ectomycorrhizal inocululu
potential in forests of southwest Oregon were investigated In the high-elevation white fir (Abies concolor (Gord. & Glend.) Lindl.) zone, two old poorly-vegetated clearcuts with...
Renibacterium salmoninarum is the causative agent of bacterial kidney disease in both
wild and farmed salmonid species worldwide. The genome of this pathogen has
significant synteny to the ubiquitous, soil-dwelling Arthrobacter spp. though it is 1.9 Mb
smaller, suggesting that reductive evolution has occurred. Recently, our group finished
sequencing and...
During the 1980s the sales and use of all-terrain vehicles (ATVs) was on the rise. Many people used them for recreation, while others started using them on their ranch or farm for work-related purposes. As a result, morbidity and mortality rates also began to climb. It became apparent that the...
The purpose of this research was to measure the copper-binding behavior of Dissolved Organic Matter (DOM) contained in Pulp and Paper (P&P) wastewater effluent and evaluate the Biotic Ligand Model’s (BLM) ability to quantify copper speciation in P&P influenced waters. A copper ion selective electrode was used to measure copper...
Heavy metals, such as copper, zinc, and cadmium, are ubiquitous in stormwater and potentially toxic to aquatic organisms at low concentrations. Removal of heavy metals contamination by conventional treatment is expensive and does not always reduce metals concentrations low enough to ensure safety of all aquatic species. This research seeks...
While the heartwood of many wood species exhibits excellent resistance to fungal and insect attack, this resistance is sometimes diminished in second-growth material of the same species. The reasons for the reduced durability are unclear, but they may reflect a combination of both higher proportions of sapwood as well as...
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Jeffrey J.Morrell
While the heartwood of many wood species exhibits excellent resistance
Treating durable, second-growth or plantation-grown material with supplemental chemicals could improve durability while enhancing the uniformity of the products. To test this hypothesis, the effect of two candidate biocide treatments on the durability of teak, redwood, and western redcedar was assessed in a ground proximity field test established in Hawaii....
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Jeffrey J. Morrell
Natural durability is generally lower in wood coming from second-growth
Recent studies have discovered that salmon, specifically juvenile Coho Salmon, have their olfactory senses inhibited by the presence of low concentrations of copper concentrations at very low concentrations. Much of this copper is deposited on roadways by car brake pads during their use. The copper is carried with stormwater into...
Malaria is the world’s most important parasitic infectious disease, and is a major cause of mortality and morbidity in many developing countries. In this dissertation I study the interaction of malaria and economic development at both the macro- and micro-economic levels.
In the first essay I examine the economic impact...
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Jeffrey J. Reimer
Malaria is the world’s most important parasitic infectious disease, and
Due to its frequent use in agriculture and its frequent detection in surface water,
atrazine was chosen as a model compound to study the treatment capability of a surface flow wetland used to remediate irrigation runoff at a container nursery near Portland, Oregon. Further evaluation of treatment of atrazine was...
Cell motility and invasion are important for development, immunity, wound healing, and tumor cell metastasis. Cells on two dimensional substrates migrate in three steps: protrusion of the front end, translocation of the cell body, and retraction of the rear end. For cells to migrate efficiently, these steps need to be...
Reported here is an investigation to determine if azinphos-methyl (AZM), an
organophosphate insecticide, adducts to hemoglobin, and if so, whether the
hemoglobin adduct could be used as a quantitative marker of occupational AZM
exposure. We hypothesized that AZM, or a metabolite of AZM, binds to hemoglobin
in erythrocytes forming an...
In order to better predict the aggregation state of nanomaterials, the factors that influence aggregation must be understood. The combined effects of natural and engineered coatings have been shown to factor into nanoparticle aggregation behavior in preliminary research. In this study, aggregation behaviors of gold nanoparticles with two different engineered...
Stream discharge is a key water balance component and important factor in global change evaluations. Nevertheless, the mechanisms for streamflow generation are poorly understood. Near- stream surface saturation during precipitation events is one of the most iconic, visible indicators of rapid runoff production in upland humid catchments around the world....
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Jeffrey J. McDonnell
Stream discharge is a key water balance component and important factor in
Glioblastoma, which occurs in adults primarily between ages of 40 to 70 years and accounts for 15% of all brain tumors, is a devastating diagnosis with a median survival rate of less than a year. Invasiveness of glioblastoma cells significantly reduces the effectiveness of current treatments, highlighting the importance of...
The dominant controls on flow generation in steep, forested hillslopes are poorly understood. This dissertation examined the dominant flow processes operating at the hillslope scale, using a combined macroscale measurement and model development and analysis framework. Irrigation experiments at two steep forested hillslopes were conducted to isolate individual hillslope flow...
Relationships between myosin heavy chain (MHC) isoform content and
eccentric-induced damage were investigated in chemically skinned muscle fiber
segments. Fibers were subjected to an eccentric contraction standardized for strain
magnitude (0.25 fiber length) and velocity (0.50 maximal shortening velocity).
Fiber MHC isoform content was identified by SDS-PAGE. Pre- to post-eccentric...
The purpose of this study was to determine the effects of back and seat rest inclination on the
kinematics of manual hand-rim wheelchair propulsion in subjects with spastic type cerebral palsy.
Subjects ranged in age from nine to twenty-one and were classified as USCPAA Class III or IV functional
ability....
The production of the fullerene C60 and its emerging applications in consumer
products imply its ultimate release to the environment. Due to the molecule’s relative
novelty, the aqueous characteristics of C60 have not been fully assessed, though it may
potentially harm human or ecological health. C60 is highly insoluble in...
Throughout a large portion of our planet, malaria has been nearly eradicated or reduced to levels that are highly manageable, and many countries possess the means to effectively treat the disease. However, many areas of the world, such as Sub-Saharan Africa and Southeast Asia, are still heavily burdened by malaria....
Recent studies have found that equatorial Atlantic sea surface temperature (SST) variability may be influencing tropical Indian Ocean climate (Kucharski 2009, Wang 2009). Due to the economic and social impact of tropical cyclones, it is important to investigate how an Atlantic-Indian Ocean connection may be affecting tropical cyclone behavior in...
The elasticity of excess demand held by foreign buyers of United States agricultural products is critical for understanding the impacts of changes in farm policy and is a parameter that is much debated. The objective of my study is to estimate this parameter for major U.S. export crops, including wheat,...
Untreated wood is inherently hygroscopic and moisture content variations can have substantial effects on dimensional stability leading to the development of deep surface checks that further enhance moisture uptake and ultimately encourage deterioration. The horizontal exposure of wood crossties makes water repellency and dimensional stability particularly important in railroad applications....
Fungi are the primary biological agents of wood deterioration and cause major economic losses of wood products globally. Wood in outdoor applications tends to remain wet for extended time periods, making it susceptible to fungal attack. Understanding the factors involved in fungal colonization of wood is important for developing improved...
This dissertation integrates a process-based hydrological investigation with an
ongoing paired-catchment study to better understand how forest harvest impacts
catchment function at multiple scales. We do this by addressing fundamental questions
related to the stocks, flows and transit times of water. Isotope tracers are used within a
top-down catchment intercomparison...
Despite the belief that fuels management, a form of prescribed fire that reduces accumulated fuels in commercially thinned forests, is necessary to restore forest 'health' in the Pacific Northwest, its effects on wildlife has received little attention in the scientific literature. Because fuels management is supported, funded, and implemented nationwide...
Diatoms are a ubiquitous group of plankton responsible for 20-40% of oceanic
primary production, and a higher fraction of organic matter export to the ocean
interior. Diatoms actively transport dissolved inorganic silicon into their cells, and
through the process of silicification (i.e. biogenic silica production) they build tough
and intricate...
Contamination of stormwater with Cu⁺², Pb⁺², and Zn⁺² has become an important issue with recognition of the neurotoxic effects of these metal ions on aquatic life. Low levels of aqueous Cu⁺² disrupt olfactory functioning in endangered Pacific Northwest salmon, decreasing their ability to avoid predation. One common solution is stormwater...
The purpose of this work was to determine if environmentally-relevant concentrations of chlorpyrifos and copper, two commonly detected chemicals in Western surface waters, can negatively impact the biological health of salmonids. Both compounds are highly neurotoxic to fish, but each with distinct biological target sites and mechanisms of action. We...
Chlorpyrifos (CPF) is a widely used broad-spectrum organophosphate insecticide. Following exposures, CPF and its more toxic oxon metabolite (CPFO) elicit neurotoxic effects by inhibiting the activity of the acetylcholinesterase enzyme (AChE), resulting in altered fitness and death at high doses. Following exposure, organisms bioactivate CPF to CPFO through the Cytochrome...
Supercritical fluid (SCF) impregnation is a promising preservative treatment method, however, the development of SCF processes has been slowed by a limited understanding of the process. Developing a better understanding of the effects of various process parameters on treatment results would allow for a more rational development of SCF impregnation....
Muscle weakness and fatigue are debilitating symptoms of multiple sclerosis (MS). Approximately 50% of muscle weakness and fatigue have been attributed to deficits within the peripheral nervous system, specifically mechanisms residing in the muscle. The goals of this study were to identify the cellular mechanisms of contraction within the muscle...
This research examined the potential for using peanut husk as a fiber alternative to wood in the production of melamine-formaldehyde (MF) particleboard. MF resin was used to produce panels with one, three, six, nine or 12 percent resin contents. Modulus of Rupture (MOR), Modulus of Elasticity (MOE), Internal Bond (IB)...
Pseudomonas syringae are plant pathogenic bacteria that cause disease by rapidly multiplying within the aboveground tissues of host plants. Growth of P. syringae within plant host tissues requires the disarmament of host immune defenses that limit microbial growth. To combat host defenses, P. syringae deploys a type III secretion system...
Small size wood assays were utilized to study the
effect of added nutrients to the wood on the interactions
of Trichoderma harzianum Rifai and two wood decay fungi,
Trametes versicolor (white rot) and Gloeophyllum trabeum
(brown rot). Weight losses related to time of exposure
were monitored as a measure of...
We hypothesized that calpain activity is elevated in response to muscle damage. To test this hypothesis, we examined the degradation of α-fodrin into its 150 and 145 kDa fragments following either 20 eccentric or isometric contractions. In addition, experiments were performed in the presence or absence of E-64-d, a calpain...
Moisture intrusion in residential structures can lead to substantial fungal decay and this damage costs billions in repair/replacement costs. The extent of damage and the rate at which it occurs are primarily dependent on the wood moisture content and temperature in the structure. Determining the risk of decay for various...
Whitebark pine (Pinus albicaulis) is an iconic North American high-elevation tree species currently threatened by climate change, mountain pine beetle, and white pine blister rust (WPBR), a lethal disease caused by the non-native fungal pathogen Cronartium ribicola. In collaboration with the USDA Forest Service Dorena Genetic Resource Center, germplasm was...
Low concentrations of dissolved copper have proven to be harmful to a number of aquatic organisms, with recent research highlighting detrimental effects to endangered salmonid species. Stormwater runoff can represent a significant source of copper to surface waters, necessitating cost-effective alternatives to current stormwater best management practices (BMPs). This study...
Biomechanical models have been used in designing human work environments to evaluate potential risks to workers before a work environment is constructed. In order for work environments to be modeled correctly, most biomechanical models require as input, an accurate body posture of the worker. This information can be obtained by,...
The purpose of this study was to examine the evidence of construct validity for self-report with assistance from a secondary source as a measure of physical activity (PA) in adults with intellectual disabilities (ID) in free-living environments. Thirty-seven participants (21 females, 16 males) with mild to moderate ID aged 19-74...
The fungi that cause mold and stain of freshly sawn lumber result in millions of dollars in losses to the forest products industry. Stain and mold are typically prevented by either kiln drying or by application of a topical fungicide. While these treatments are effective, kiln drying is costly and...
Small manufacturing firms often serve a domestic market but would like to expand their sales overseas. It is difficult for a small firm to develop overseas contracts and relationships, however, in part because of their small size, and because the advantages of their products may not always be obvious. The...
It has been previously suggested that the walking pattern of individuals with Down syndrome is inefficient. This is thought to result from increased instability, particularly in the medio-lateral direction, due to the characteristic joint laxity and muscle hypotonia of individuals with DS. Therefore, this work was an attempt to gain...
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Jeffrey A. McCubbin
It has been previously suggested that the walking pattern of
Current best management practices (BMPs) for stormwater treatment are not able to adequately remove heavy metals to levels which do not adversely affect aquatic life. Copper is commonly found in highway stormwater runoff, with the primary source being brake pad wear. Copper is of particular concern due to inhibitory effects...
Copper and zinc are heavy metals commonly present in highway stormwater runoff. Discharge of these metals to surface waters inhabited by sensitive aquatic species including threatened and endangered salmonids has necessitated the need for improved treatment techniques. Although copper is of the greater toxicological concern, zinc is often present at...
The etiology and transmission of bacterial diarrheal pathogens is complex, making evaluating the association between extreme climate and diarrheal illnesses in North America challenging. Changes in climate may impact the survival, reproduction, and distribution of pathogens that cause diarrheal illness. Evidence supports the hypothesis that reproduction, survival, and transmission ability...
Heteroaggregation of nanoparticles with naturally occurring colloids has been shown to be an important process in nanoparticle fate and transport in the aquatic environment. The advent of a functional assay to measure heteroaggregation attachment efficiencies has opened the door for further mechanistic studies. It is well known that natural organic...
Metal oxide nanoparticles (MONPs) are manufactured at the greatest rate of any class of nanomaterial due to their wide variety of industrial, commercial, and environmental applications. The sustainable use of MONPs requires a balance of careful consideration of their potential negative environmental impacts with the effective exploitation of their unique...
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Jeffrey A. Nason
Metal oxide nanoparticles (MONPs) are manufactured at the greatest rate of
The focus of this research was to gain an understanding of physical activity in elementary school-aged children with mental retardation (MR). The primary purpose of the first study was to investigate physical activity levels of children with and without MR in both school and out of school environments. The secondary...
Nanoparticles are becoming increasingly important in numerous technological fields but evidence shows that they can be toxic to many organisms. To predict their fate and transport in the environment, nanoparticle attachment to naturally occurring colloids must be examined. This study investigated citrate-capped gold nanoparticle (Cit-AuNP) heteroaggregation with two model colloids...
Understanding how the interactions and feedbacks between plant function, climate, and soils ultimately affects the terrestrial water balance and subsurface flow processes is major challenge in scientific hydrology. This dissertation summarizes the findings of a manipulative climate warming experiment, an observational field study that utilized stable-isotope tracers, and associated modeling...
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Jeffrey J. McDonnell
Understanding how the interactions and feedbacks between plant
Coagulation and flocculation are commonly used in drinking water treatment
as a means of destabilizing and aggregating particles and promoting adsorption of
dissolved organic carbon (DOC). In practice, jar tests are used to determine optimal
conditions for the removal of turbidity and DOC. However, beyond the inferences
that can be...
Birdsfoot trefoil (Lotus corniculatus L.) is a popular perennial, non-bloating forage legume used for pasture, hay and silage throughout the temperate regions of Europe, Asia Minor, North Africa and North and South America. It is regarded as the most morphologically and biochemically variable species in the genus. Research investigating the...
Engineered nanomaterials (ENMs) are small anthropogenic colloids with at least one length dimension <100 nanometers. Due to the nature of their use, ENMs are being increasingly released to the environment. Yet the environmental risks posed by ENMs are unknown due to a variety challenges, including limitations with detecting and quantifying...
The objective of this thesis is to develop and
computationally test a new algorithm for the class of
network models with generalized upper bound (GUB) side
constraints. Various algorithms have been developed to
solve the network with arbitrary side constraints problem;
however, no algorithm that exploits the special structure
of...
Understanding the aggregation behavior of engineered nanomaterials (ENMs) in aqueous environments is essential to understanding their fate, transport, and toxicity. Because naturally occurring colloids will likely be present at much higher concentrations than ENMs in environmental systems, heteroaggregation and attachment with these natural colloids could significantly influence ENM fate and...
The relative role of cospeciation and host switching in the phylogenetic history of
ascomycete foliar symbionts is addressed in the orders Leotiales and Rhytismatales, fungi
associated predominantly with Pinaceae (Coniferales). Emphasis is placed on comparing
the evolution of the sister genera Pseudotsuga and Larix (Pinaceae) with that of the
pathogenic...
Postmenopausat women on hormone replacement therapy (HRT) have been reported to be stronger when compared to women who are not using HRT. The first goal of this study was to investigate whether muscle morphology was altered in women who use HRT when compared to women who do not use HAT....
A common perspective promoted by health care professionals is that exercise may help reduce symptoms and improve activities of daily living among persons with multiple sclerosis (MS). Yet, the effects of resistance exercise on power, functional mobility, and fatigue are largely unknown. The purpose of this study was to examine...
Glioblastoma is the most malignant primary brain tumor with the average
patients surviving only one year after diagnosis, even with aggressive therapy. The
formation of numerous micro-tumors dispersed into the brain due to rapid invasion of
tumor cells, presents the primary challenge to the surgical removal of tumors and
limits...
Defensive chemical and nutritive quality of young leaves were measured for 72 individual trees of Chrysolepis [Castanopsis] chrysophylla in conjunction with light intensities of two different stand types and population numbers of Habrodais grunus herri in the Cascade mountains of Oregon. Leaves were collected in the spring and leaf characteristics...
The goals of this research were to a) characterize the protein-function relationships of skeletal muscle single fibers from the mouse hindlimb b) examine mouse-strain related differences in myosin heavy chain composition (MHC) and single fiber contractile function, and c) quantify changes in fiber size and contractile function in response to...
Both red (Trifolium pratense L.) and white (Trifolium repens L.) clover
seed yields can be highly variable and low in western Oregon. The objectives of
this study were to: i) determine crop water requirements and supplemental
irrigation timing, and ii) quantify the effects of soil and water status on
inflorescence...
Microplastics (MPs) are plastic particles less than 5 mm in diameter. These contaminants are increasingly found in the environment due to increased plastic production, use, and improper disposal. Detecting and measuring these contaminants in the environment has proven difficult, requiring the use of fate and transport models to assess MP...
Douglas-fir, Pseudotsuga menziesii and white alder,
Alnus rhombifolia, species that are prevalent in the
Pacific Northwest, were fed to larvae of the gypsy moth,
Lymantria dispar L. Gypsy moth larvae from different
familial lines (egg masses) from a single geographic
population were evaluated on these hosts. The larvae
were fed...
The specific objectives of this dissertation are to determine subsurface flow
behaviors across different antecedent wetness conditions from a top-down perspective
and to mechanistically assess the hydrological controls on DOC and N transport at the
hillslope and catchment scale. The study area is a small catchment where hillslopes
issue directly...
The widespread use of engineered nanoparticles (ENPs) in industrial applications and consumer products makes their release to the environment inevitable. Understanding the aggregation behavior of ENPs is crucial to understanding their fate, transport and toxicology in aquatic systems. This study investigated the comparability of experimentally-determined and model-estimated attachment efficiencies for...
Pacific Northwest and California freshwater resources are key elements in the life history and ecology of Pacific salmon and steelhead listed as threatened or endangered under the Endangered Species Act. Risk to listed Pacific salmonid species can be assessed by evaluating the spatial and temporal co-occurrence of salmonid species at...
Mariner 9 and Viking spacecraft observations during the 1970's have provided
evidence for planetary-scale wave-like disturbances in the Mars atmosphere. It has
been suggested that possible sources of the wave activity are dynamical instabilities
(e.g., barotropic and/or baroclinic instabilities). An other candidate source is forced,
quasi-stationary planetary waves. In connection...
The influence of natural enemies and plant apparency in
determining the abundance of the cabbage aphid Brevicoryne brassicae L.
and the imported cabbageworm Pieris rapae L. was examined on collards
grown in a collard monoculture and in a collard-alfalfa biculture.
This design was used to examine the factors affecting collardherbivore...
Fifteen species of Noctuidae (Lepidoptera) were collected in alfalfa and
peppermint in western Oregon. Seven of these species were hosts for the braconid
parasitoid Meteorus communis. The most frequently parasitized (percent) species were
Agrotis ipsilon (35.3), Dargida procincta (15.0), and Peridroma saucia (6.9). Other
species parasitized were Autographa californica (3.8)...
This study investigates the relationship between total and ionic copper in samples taken from the Tualatin River and wastewater treatment facilities (WWTFs) that discharge into the Tualatin River. Copper speciation was analyzed by determining conditional stability constants and densities of copper binding ligands on the dissolved organic matter (DOM) in...
Resistance training is widely prescribed for rehabilitation of injuries and as a method to improve athletic performance. It is accepted that resistance training increases the maximal force production of whole muscle and it has been suggested that the velocity of shortening can increase as well. However, little is known about...
This paper investigates the atmospheric circulation and transport characteristics
of the Martian atmosphere (as modeled by a Mars GCM) for three sets of
conditions. The conditions are based on a combination of season and dust loading
(as parameterized by the optical depth, τ). The first experiment is for the Northern...
Copper is an excellent biocide which has a long history of usage for protecting wood from deterioration, but some organisms have developed tolerance for this chemical. Copper tolerance among wood decay fungi is a poorly understood phenomenon that is gaining importance as cofactors such as arsenic and chromium are removed...
Bedrock groundwater dynamics in headwater catchments are poorly understood and
poorly characterized. Direct hydrometric measurements have been limited due to the
logistical challenges associated with drilling through hard rock in steep, remote and
often roadless terrain. Here we develop and use an inexpensive, portable bedrock
drilling system to explore bedrock...
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Jeffrey J. McDonnell
Bedrock groundwater dynamics in headwater catchments are poorly
The fungus Nothophaeocryptopus gaeumannii is the causative agent of Swiss needle cast (SNC), a foliar disease of Douglas-fir. Disease is characterized by premature loss of foliage and reduced growth resulting from the inhibition of photosynthesis due to the occlusion of stomata by the ascocarps of N. gaeumannii. Although the disease...
The low-level baroclinic eddy activity seen in the NASA Ames Mars General Circulation Model (MGCM) for simulations under three annual dust cycles are characterized. Simulations were conducted with both radiatively active and radiatively inert clouds (RAC and non-RAC, respectively) for 11 continuous annual cycles for each dust case. Model results...