Quantifying and modeling processes involved in the global carbon cycle is important to evaluate the temporal and spatial variability of these processes and understand the effect of this variability on future response to changing climate and land use patterns. Biomass accumulation and Net Primary Productivity (NPP) are large components of...
Soil respiration, or the combined CO₂ emissions from roots and soil microorganisms, constitutes one of the largest losses of carbon (C) from terrestrial ecosystems. The major drivers of soil respiration, which include soil moisture, temperature, and substrate quality, have been known for some time. Nevertheless,
correlations between these drivers and...
Ecosystems are highly heterogeneous systems subjected to important levels of environmental variability; however, it is common in terrestrial biogeochemical models to assume homogeneous properties of the elements of the system or constant environmental conditions. For some processes, heterogeneity in these models is treated very simplistically, but there is not much...
Effects of small-scale disturbances on fecundity and growth rates of Linnaea
borealis L., Tiarella trifoliata L. var. unifoliata, and Trillium ovatum Pursh. were studied in
old-growth forests in the Tsuga heterophylla Zone on the west slope of the Cascade
Mountain Range of Oregon. Performance of each species was compared in...
This study assessed the effects of thinning on arthropod communities on understory plants in the Central Oregon Coast Range. Arthropods were sampled from five understory plants in five pairs of thinned and unthinned, young (50-80 yrs), managed Douglas-fir stands, from late May to mid-July of 1998. Vine maple (Acer circinatum),...
A simple debris-slide model, employing a digital elevation model (DEM) and geological data, was used in a geographic information system (GIS) to map slope stability in the Andrews Experimental Forest, located in the western Cascade Range in Oregon, USA. To evaluate the contribution of error in elevation to the uncertainty...
The growth potential of Douglas-fir, grand fir and western hemlock advance regeneration in the forest understory of Douglas-fir-dominated forests was investigated to detennine the feasibility of selection cutting systems in northwest Oregon. This study compared the growth of Douglas-fir, grand fir and western hemlock advance regeneration along a light gradient...
Seasonal and annual patterns of N fluxes and concentrations in streamwater in six conifer-dominated watersheds at the H.J. Andrews Experimental Forest, OR, were studied to gain insight into the factors that influence N retention in this ecosystem. Processes affecting N flux in streamwater differed between organic (DON) and inorganic (DIN;...
A series of experiments were established to gain a better understanding of the extent to which Douglas-fir seeding root architecture may be manipulated and subsequent influences on seedling morphological and physiological development. The incorporation of amendments into nursery soils changed root architecture to some degree, but did not produce large...
Viability analysis of well-selected focal species can complement other types of conservation planning by revealing thresholds in habitat area and landscape connectivity that may not be evident from ecosystem-level evaluations. I used focal species analysis of five carnivores to suggest conservation planning guidelines for the Rocky Mountains and adjacent areas...
Maritime cyclonic windstorms cause widespread disturbance to forested ecosystems in southeast Alaska. The consequence of this disturbance process on the movement, storage, and quality of soil carbon, forest hydrology and streamwater chemistry was studied along a windthrow disturbance sequence. Soil profiles were described and the thickness of the major organic...
Estimates of potential carbon (C) storage can be used to constrain predictions of future carbon sequestration and to understand the degree to which disturbances, both natural aid anthropogenic, affect C storage. An upper bound on C storage in the Pacific Northwest (PNW) of the United States was estimated using field...
A series of studies, in three western Oregon Douglas-fir plantations, was conducted to understand the physiological impacts of Swiss needle cast on Douglas-fir physiology. Four aspects of the disease complex were investigated: fungal colonization and assessment, plant-water relations, carbon assimilation and interaction with climate. Several techniques were developed and used...
My objectives were to investigate the correlation of height and diameter growth in young Douglas-fir (Pseudotsuga menziesii) plantations with stand density, and to determine the effects of stand density on the canopy boundary layer conductance (g[subscript]ac) and microclimate characteristics of young Douglas-fir plantations. I measured annual height (h) and diameter...
History is an invaluable source of information to understand and evaluate management influences on contemporary ecosystems and landscapes. The first two chapters (Chapters 2 and 3) explored the concept of historical range of variability (HRV) in landscape structure and stand structure using a stochastic fire simulation model to simulate presettlement...
The Humboldt marten, Martes americana humboldtensis, has undergone a dramatic decline throughout its historical distribution in coastal Northwestern California. There is currently only one known population occupying an area occurring in <5% of the historical distribution of the subspecies. Conservation and management efforts to benefit this population are hampered by...
Hybrid poplar plantations (Populus trichocarpa x Populus deltoides) are a relatively new feature on the landscape in the Pacific Northwest of the United States, and these plantations may soon include genetically engineered trees. Meanwhile, many wild poplar populations (Populus spp.) are highly degraded due in part to logging, dams, grazing,...
Every wood anatomist knows that the wood near the center of a tree (juvenile wood) differs from the wood laid down at some distance from the pith (mature wood), and that the wood produced during the spring (earlywood) differs from the wood produced during the summer (latewood). There is a...
By emulating natural disturbances such as wildfire, managers hope to maintain biodiversity in managed forests. Leaving residual (live) trees in harvested areas is key to this strategy. However, the effectiveness of this approach is unknown. I surveyed songbirds in 176 stands in the Rocky Mountains of southeastern British Columbia, Canada,...
This study examined debris flows occurring in a 125 km² study area in the Blue River watershed in the western Cascade Mountains of Oregon over a 50-year period. Debris flow occurrence was found to be concentrated in a distinct zone of high activity occupying approximately half of the study area,...
When biogeochemical models are applied to large regions, the values of key model parameters are often unknowable. Through field and modeling studies, I examined the potential impact of such uncertainty on estimates of carbon cycling in western Oregon. I found that variation in key leaf traits could be interpreted ecologically,...
The overall purpose of this study was to examine the root and shoot development of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings at two distinct time periods in seedling establishment (after I and 3 growing seasons) in response to fertilizer, stock size, vegetation control, and soil moisture treatments. Two separate experiments...
These studies are part of the Demonstration of Ecosystem Management Options (DEMO) study, a program researching the effects of different levels and patterns of green-tree retention on ecological, economic, and social phenomena. We restricted our studies to the 15% basal area, evenly dispersed retention treatment. Our objectives were, first, to...
A series of studies and replicated field sites were implemented in the Oregon Coast Range within Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) sapling plantations infected with varying levels of Swiss needle cast (SNC) caused by the fungus, Phaeocryptopus gaeumannii (Rhode) Petrak (PG). This research was conducted to understand the effects of...
Canopy structure has a significant impact on the canopy hydrology of
Douglas-fir forests in the Pacific Northwest (PNW). Whole canopy rainfall
interception was measured for young Douglas-fir forest and compared to an
old-growth Douglas-fir forest. The old-growth forest had significantly greater
canopy water storage capacity (5) and direct throughfall fraction...
Despite many studies of large wood in streams, few landscape scale studies have been conducted. Large-scale studies can reveal how the history of forest harvest and road building has influenced wood patterns in streams of the Pacific Northwest. This study examined the relationships between wood in streams, timber harvest, and...
Silviculture systems that involve commercial thinning may provide higher quality wildlife habitat than traditional clearcut systems, yet such systems have not been vigorously tested. This prospective study examined forest floor animal abundance and habitat relationships under three different silviculture conditions: clearcuts, commercial thins, and uncuts. Eighteen stands, six per treatment,...
The Chugach National Forest has been using prescribed fire as a wildlife habitat management tool since l977. Between 1977 and 1997 about 4,000 hectares have been burned on the Kenai Peninsula to promote regeneration of woody plant species used by moose (Alces alces). Browse species include paper birch (Betula papyrifera),...
We have a poor understanding of the biotic communities in zero-order basins, drainages extending from ridgelines to the initiation of first-order streams. This study describes baseline plant and amphibian composition in unmanaged zero-order basins in the Oregon Coast Range. Specifically, I studied: i) the spatial distribution and diversity of species,...
Historical aerial photos were used to examine the early phase of forest succession after stand replacement disturbance, covering the Coast Ranges Province (CRP) and the western Cascades Province (WCP) of western Oregon. The study consisted of two components: characterizing the pattern of forest succession in western Oregon; analyzing the influence...
Concentration of carbon dioxide (CO₂) in the atmosphere has increased over the past 150 years. Because CO₂ is one of a number of radiatively active gases, there is concern that global temperatures will rise and climatic conditions will change. Recent research indicates northern hemisphere forests may currently be accumulating carbon...
The main objectives of this study are to identify the nature of threats to protected areas and assess the effectiveness of protected area systems and management in Thailand, and to evaluate the use of conservation biology concepts in protected area management. The results from a survey of the heads of...
Many studies have shown that net primary production in old-growth Douglas-fir/western hemlock forests is lower than in younger forests in similar sites, although the cause is still not clear. One possibility is that overall carbon assimilation, or GPP, is lower in older forests. However, it is difficult to measure GPP...
Dead wood patterns and dynamics vary with biophysical factors, disturbance history, ownership, and management practices. Through field and modeling studies, I examined the current and potential future amounts of dead wood in two landscapes and region-wide in the Coastal Province of Oregon. The objectives of the first study were to...
Gene flow is a major evolutionary force and an important factor in the breeding and conservation of forest trees. I studied the applicability of SSR markers for measuring pollen-mediated gene flow (i.e., pollen flow) in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). I developed SSR markers, tested alternative approaches for measuring pollen...
In this study we use a combination of data from forest inventories,
intensive chronosequences, extensive sites, and remote sensing, to make estimates
of biomass and net primary production (NPP) for the forested region of Western
Oregon. Plot-level forest inventory data were provided by the USDA Forest
Service through their Forest...
Soil physical, chemical, and biological components as well as climate and physiographic characteristics can interact to have a great effect on forest regeneration and seedling growth response to different establishment activities. The objective of this project was to increase the understanding of the interactions between soil type, controlled-release fertilizers, and...
Longitudinal water surface profiles from high-gradient mountain streams provide useful indicators of the relative potential for hyporheic exchange flow in stream reaches with varying morphology. The spacing between slope breaks in step-pool and pool-riffle streams provides a geomorphic scaling metric that indicates how the length of average hyporheic flow paths...
The relationship between the level of Phaeocryptopus gaeumannii (Rohde) Petrak colonization and severity of Swiss needle cast (SNC) symptoms, the possibility of early testing of Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) for SNC tolerance, and geographic variation in coastal Oregon with respect to SNC tolerance were investigated. Comparisons between...
Beginning in the 1980s, large-scale commercial harvest of Tricholoma magnivelare created a need for management of forests to ensure sustainability, but little was known of the biology or ecology of this species to guide management decisions. Four of the five studies presented here explore the basic synecology of T. magnivelare...
Live western larch, Larix occidentalis Nutt., a tree species resistant to the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, produces the monoterpene 3-carene in higher concentrations compared to Douglas-fir, the preferred host of D. pseudotsugae (Reed et al. 1986). The inhibitory effects on attraction to aggregation pheromones and toxicity of 3-carene to...
This study investigated variation in xylem anatomy, hydraulic properties, and the relationship between anatomy and properties within Douglas-fir trees at multiple scales. The hierarchical scales in the study included fertilization treatments (fertilized and unfertilized), trees within the treatments, and positions within the trees. Tracheid diameter, tracheid length, percent latewood, number...
Water treatments were applied to young ponderosa pine trees in the Eastern Cascades, Oregon during the 2003 growing season, and shade treatments were applied during the 2003 and 2004 growing seasons to understand how photosynthesis and soil respiration, particularly the root/rhizosphere fraction (R[subscript rrh]), would respond to increased moisture availability...
The Amazon Tropical Rain Forest is the largest tropical rain forest system, comprising approximately 65% of such forests on earth. Since the 1960's, human populations in the Brazilian Amazon have increased from two to over 20 million. Concomitant urbanization, forest conversion, and economic dependence on resource extraction have exerted severe...
Two research questions are posed: (1) How have ecosystem conditions changed through time in southwestern Oregon? (2) How have culture-driven and climate-driven processes contributed to ecosystem change in southwestern Oregon? A brief introduction to the Little River study area is followed by a cultural and ecological history of the watershed....
Commercial thinning operations can result in damage to residual stems. A literature review revealed that little was known about the effects of residual logging wounds with regard to rotation-age commercial conifers, particularly Douglas-fir. An experiment to examine fungal colonization of Douglas-fir following logging damage showed that while damage was significant...
This collection of three manuscripts serves to improve methods for collecting, interpreting, and utilizing autocorrelated data from headwater stream networks. Each stream network is comprised of linear segments. These segments lie within a unique branching structure that connects the segments via flowing water, and the connectivity provided by water varies...
In deciduous species, water exits stems mainly through leaf traces
attached to the outer growth ring and yet we know that water ascends
throughout the entire cross-section of the sapwood. There is an increasing
amount of information on sap flow and sapwood hydraulic properties from
separate studies, but little information...
Fire is a fundamental disturbance that drives terrestrial and atmospheric carbon dynamics. Previous studies have quantified fire effects on carbon cycling from local to global scales but have focused nearly exclusively on high-severity, stand-replacement fire. Since 2002, variable-severity wildfires have burned more than 65 000 ha across the east slope...
Fire exclusion has been associated with structural and compositional changes
in many upland forests of the western United States, but little is known about the
impacts on riparian forests, portions of the landscape protected for habitat and water
quality. For this study, I characterized the historic disturbance and tree recruitment...
The links between forests, streamflow, and climate are poorly understood. Despite hundreds of studies over the past 60 years, fundamental questions of forests' effects on the hydrologic cycle remain unanswered. The hydrological cycle involves mutually-dependent biological and physical processes that operate at multiple scales of time and space, and this...
Society uses massive quantities of wood fiber in production of paper, and demand for fiber is projected to increase further as production of biofuels from fermentation of plant cellulosic materials increases. Because these end uses generally require the costly step of removing of lignin, wood with reduced or more easily...
Two forest management objectives being debated in the context of federally managed landscapes in the US Pacific Northwest involve a perceived trade-off between fire restoration and C sequestration. The former strategy would reduce fuel (and therefore C) that has accumulated through a century of fire suppression and exclusion that has...
I examined factors regulating decomposition rates of red alder (Alnus rubra)) and Douglas-fir (Pseudotsuga menziesii) leaf litter in Coast Range riparian areas in western Oregon. Overall, this study was designed to examine the influence that leaf litter quality characteristics and decomposition site treatment have on decomposition rates, to provide a...
Accurate estimation of live and dead biomass in forested ecosystems is important for
studies of carbon dynamics, biodiversity, and wildfire behavior, and for forest management.
Lidar remote sensing has been used successfully to estimate live biomass, but studies focusing
on dead biomass are rare. We used lidar data, in conjunction...
The processes that lead to stable, low-growing plant communities and the characteristics of the species that form them are of great interest to rights-of-way (ROW) managers and others wishing to better understand plant community resistance to tree invasion on managed landscapes. The use of stable, low-growing plant communities as a...
We evaluated genes previously identified from a large scale functional genomics screen for their potential value to help enhance carbon sequestration in planted trees. We used poplar as a model tree species because of its abundant genetic variation, ease of gene transfer, and availability of large databases for genomic, anatomical,...
Litter nutrient dynamics contribute significantly to biogeochemical cycling in
forest ecosystems. These dynamics may be influenced by site attributes, litter nutrient concentrations, and soil nutrient availability either independently or synergistically. Litter nutrient dynamics were examined in two decomposition studies in temperate coniferous forests of Oregon. I used ¹⁵N-labelled litter of...
Previous studies have indicated that roots from five tree species (Picea sitchensis, Tsuga heterophylla, Pseudotsuga menziesii, Pinus ponderosa, and Pinus contorta) decompose at different rates across an environmental gradient in Oregon. Measurements of wood chemistry from each tree species as well as moisture and
temperature from each location do not...
In the interest of meeting multiple forest management goals that include maintenance of wildlife, particularly cavity-nesting birds, uneven-aged silvicultural treatments are used increasingly in the Pacific Northwest. However, questions remain regarding the responses of cavity-nesting birds and residual green trees to different harvest intensities and patterns. To study these issues,...
Soils are the largest terrestrial pool of carbon, therefore it is critical to understand
what controls soil carbon efflux to the atmosphere in light of current climate uncertainty.
The primary efflux of carbon from soil is soil respiration which is typically categorized
into autotrophic and heterotrophic respiration. These two components...
Gymnomyces is an ectomycorrhizal basidiomycete genus in the family Russulaceae estimated to contain less than 50 species worldwide, with 23 species known to occur in the Pacific Northwest. Gymnomyces species are common in Pacific Northwest forests that include Pseudotsuga, Abies, Tsuga, and Quercus. They produce sequestrate (truffle-like) sporocarps with ornamented...
Field studies were conducted from 1996 to 1998 in three villages in a Highland watershed in Mae Hong Son Province, northern Thailand. The objectives of the study were to classify and define the fruit-based agroforestry cropping system and investigate
management activities used by villagers. In the first part of the...
I studied riparian forests of four western Oregon watersheds (dry south to wet north) to determine the multiscale controls on woody riparian vegetation. I conducted separate analyses of controls on plant distribution, diversity, and tree regeneration using vegetation and environmental data collected in two related field studies: (1) a multiscale...
Downed wood and antelope bitterbrush (Purshia tridentata) are often managed on federal ponderosa pine (Pinus ponderosa) forests in central Oregon to prevent catastrophic wildfires and provide wildlife habitat. However, although much is known regarding the roles of downed wood and bitterbrush in wildfire behavior, little is known regarding the relationships...
Effects of partial understory removal on belowground and aboveground ecosystem properties were investigated in 5 and 15 yr old Douglas-fir (Pseudotsuga menziesll (Mirb.) Franco) experimental plantations in western Oregon. Seedling survival was not affected by understory removal at age 5 yr.
But through age 15 yr, understory removal increased seedling...
The process of silvicultural thinning has become very controversial recently with regards to fire protection and management for old-growth conditions and biodiversity. Therefore, an unthinned control stand and 3 different thinning intensities were examined for their effects on the abundance, species richness, and diversity of arthropods in thinning treatments of...
Coarse woody debris (CWD) decomposition in the Russian boreal forests of the southern taiga zone was studied at four sites located near St. Petersburg in Northwestern Russia, Krasnoyarsk in Eastern Siberia, lrkutsk in the Baikal region, and Khabarovsk in the Russian Far East. This study was part of a broader...
Dissolved organic matter (DOM) plays an important role in transport of C and essential nutrients such as N, P and S. DOM is also critical for the formation of soil organic matter (SOM), which is the largest terrestrial C pool. Nonetheless, we lack a basic understanding of what controls immobilization...
Application of N fertilizer is a common forest management practice in the Pacific
Northwest, yet the long-term influence of fertilization on forest soil properties is not well known. Although elevated N often increases mineralization of C and N from labile organic matter, negative effects have been documented in recalcitrant organic...
Western juniper (Juniperus occidentalis) poses both a challenge and an opportunity for natural resource management in the rangelands of the northern Great Basin. The continued expansion of western juniper on the rangelands of the interior Northwest will likely continue as there are currently no practical options for returning this area...
Craterellus tubaeformis is a small to medium-sized forest mushroom that is fairly common in the Douglas-fir/western hemlock forests of the Pacific Northwestern United States and is most often associated with decayed coarse woody debris. In this study, the mycorrhizae of Craterellus tubaeformis in western Oregon is identified by DNA analysis...
The hump-shaped relationship that predicts highest species richness (species/unit area) at intermediate levels of productivity was examined for woody plants across the Pacific and Inland Northwest of the U.S. Many studies have examined this relationship at regional scales, but commonly use species range maps and surrogate measures of productivity (e.g....
Managing forest ecosystems for sustainable, multiple use requires forest resource managers to understand how species composition and distribution vary across environmental gradients and respond to landscape scale disturbance. A number of statistical modeling tools are available to construct predictive models and maps from response data, a set of predictor variables,...
An increment core-based, laboratory method was used to measure tissue-level respiration under controlled temperature (termed respiratory potential) of eleven tree species from three age classes. Respiratory potential was calculated on a basis of core dry-mass, volume, carbon, or nitrogen content and live bole volume. Methods tests suggested that core carbon...
Thinning has the potential to increase structural diversity of managed forests for wildlife. During 1994-1996, I conducted experimental and observational studies using pitfall trapping to assess short-term and potential long-term effects of thinning on abundance and reproduction of forest-floor vertebrates in Douglas-fir (Pseudotsuga menzeisii) forests of the Oregon Coast Range....
Adaptive ecosystem management is a new paradigm for managing federal forests which requires regular monitoring of ecosystem function and diversity to measure the effects of management. Managers need new strategies and tools to help them assess their progress in maintaining healthy, productive and biologically diverse forests. Biomonitoring of select forest...
Invasive plants threaten ecosystems and economies worldwide. Classical biological control, introduction of specialist herbivores on invasive plants, is one of the tools employed to reduce the impact of invasive plants. Gorse, Ulex europaeus L. (Fabaceae), an invasive leguminous shrub, is the target of a biological control program in Oregon. The...
Agroforestry is a traditional farming practice in American Samoa that has helped to sustain the livelihood of the native population for centuries. These once self-sufficient islands have become economically dependent on U.S monies and other external resources during the past century. Dependency has caused a shift in the carrying capacity...
During the last century, fire suppression, grazing, and climate change have caused sagebrush grasslands to be altered in both function and form; juniper and sagebrush dominate the landscape at the expense of herbaceous plants. Management efforts to reduce juniper and sagebrush overstory in order to enhance herbaceous components of the...
To effectively manage for biodiversity at broad, ecosystem scales, the influences of habitat structure at multiple spatial scales on vertebrate species must be understood. There are few studies on the broad-scale habitat requirements of stream amphibians despite their importance in streams in forest ecosystems in the Pacific Northwest (PNW) as...
Two experiments were conducted on the invasive plant species Potentilla recta in northeastern Oregon to investigate both biological and ecological characteristics of the species. Growth analysis was conducted on the plant at three sites over a period of two years (2002 and 2003). Relative growth rate (RGR) was calculated for...
The tree species and size structure of 9l old-growth forests dominated by Douglas-fir
in central western Oregon was characterized using complete inventories of all trees larger than 20cm dbh over a mean area of 17.1ha at each site. Douglas-fir accounted
for over 75% of the total average basal area (39.1...
Without the natural occurrence of fire in ponderosa pine forests of the western US, lodgepole pine has started to dominate regeneration in many forest stands and may be gradually replacing ponderosa pine over time. This development, however, conflicts with recent efforts in this region to restore old-aged, open ponderosa pine...
The goal of this dissertation was to improve our understanding of age-related constraints on aboveground production of forest trees. Previous research suggesting that carbon uptake of old trees is hydraulically constrained by tree size was used as the
springboard for this research. Three specific working hypotheses were investigated: 1) compensation...
To study the combined effects of seedling quality and fertilization at the time of planting, three experiments were established in western Oregon during the winter of 2000. The first experiment investigated the effect of preplanting rootvolume and fertilization rate on the field performance of 1+1 Douglas-fir seedlings during two growing...
The spruce weevil (Pissodes strobi) is a serious pest of Sitka spruce in Oregon. Weevils cause damage by killing the leader of a tree, resulting in defects such as crooks and forks that can render the tree unmerchantable. In this study, spruce stands 16-25 years old were surveyed for weevil...
Thinning of young Douglas-fir forests has the potential to enhance structural diversity and improve habitat for wildlife. I examined the effects of thinning and thinning intensity on abundance and demographic characteristics of forest-floor small mammals in the Coast Range of Oregon 5 and 6 years after thinning had occurred. Thinning...
The use of high throughput molecular methods that allow for the study of bacterial communities in environmental samples is commonplace in microbial ecology. Until recently, fungal community ecology has
focused on isolation, collection of sporocarps, or collection of ectomycorrhizal roots. The techniques used to extract and amplify DNA from environmental...
The MODIS NBAR (M0D43B4) data space is explored in terms of biophysical variables with the objective of formulating a MODIS transformation relevant to global vegetation studies. The basic ideas of transform formulation were borrowed from the development of the TM Tasseled Cap transformation, but with differences in sampling strategy and...
The Demonstration for Ecosystem Management Options (DEMO) study originated out of the changing management priorities associated with federal forest lands in the Pacific Northwest which included an objective to maintain mature and old-growth forest characteristics in managed stands. The DEMO project examines the effects that different levels and patterns of...
A mechanistic simulation model of nitrogen fixation in dead wood was developed to help synthesize knowledge, develop hypotheses, and estimate rates of nitrogen fixation in the Pacific Northwest. In this model nitrogen fixation is directly controlled by log substrate, temperature, moisture, and oxygen content. Respiration and diffusion of
oxygen indirectly...
The Normalized Burn Ratio and Composite Burn Index were used to classify burn severity in three sites that experienced lightning-ignited wildfire in the year 2000. The effect of burn severity (unburned, low, moderate, and high severity classes) was investigated on vegetation and soil microbial community composition. Vegetation communities showed a...
The Demonstration of Ecosystem Management Options (DEMO) study is a large-scale, multi-year, interdisciplinary project examining the effects of various levels and patterns of green-tree retention on multiple forest features. Six retention levels and patterns were examined and replicated across six blocks of predominately Douglas-fir forested land in western Oregon and...
As concern over global warming intensifies, sequestration and storage of atmospheric CO2 has become an important scientific and policy issue. Confusion persists, however, over interpretation of forest carbon (C) source-sink dynamics, in part because conclusions drawn depend on temporal and spatial scales of analysis (e.g. day-week
scale vs. successional-scale), type...
When Douglas-fir and red alder grow in mixture, interactions between the two species can be competitive, facilitative, or a combination of both over time. A number of factors have recently led to increased interest in managing these two species together for commercial production, and ongoing investigations are yielding important information...
Arthropods are important food resources for birds. Forest management activities can influence shrub-dwelling arthropods by affecting the structure and composition of understory shrub communities. Changes in abundance and species composition of arthropod communities in turn may influence the distribution and abundance of insectivorous birds. I examined relationships among bird abundance,...
The nomenclatural history of Gomphus sensu lato began with Persoon in
1797. Over 200 years species of Gomphus sensu lato have been variously classified
also under Cantharellus, Craterellus, Chloroneuron, Chlorophyllum,
Gloeocantharellus, Nevrophyllum, and Turbinellus.
Species of Gomphus sensu lato have been historically characterized as
having aboveground fruiting, fleshy basidiomata with...
The role of insect herbivores in the nutrient cycling dynamics of forest ecosystems remains poorly understood. Although past research in herbivory has focused primarily on the deleterious effects that insects can have on tree growth and mortality, the overall effects of herbivory are more complex. Herbivores have the potential to...
This dissertation was undertaken to improve the understanding of the population dynamics of the Pacific Golden chanterelle, Cantharellus formosus. It addresses the longevity of individuals over a 12 year period and the limits of gene flow within the area of a 6,400 hectare watershed at the H.J. Andrews Long Term...