In a field study, seedlings of Arizona pine (Pinus arizonica Engeim.), Apache pine (P. engelmannii Cam), and Durango pine (P. durangensis Mart.) were planted in an one open area and in canopy gaps of four forested sites of a pine-oak forest in the Sierra Madre Occidental in the state of...
We tested a synthetic bacterio-opsin (bO) gene derived from Halobacterium halobium for its effect on disease resistance in transgenic poplar hybrids, and assessed a genetic system for controlling expression of this gene. In tobacco the bO gene caused necrotic lesions similar to an induced hypersensitive response (HR), increased levels of...
Physiology and genetics of drought hardiness were investigated in two-year-old coastal Douglas-fir seedlings from 39 full-sib families obtained from coastal British Columbia and grown at Oregon State University, Corvallis, Oregon. The seedlings were subjected to three drought treatments (control, moderate, and severe drought) in their second growing season (June through...
Post-fire Pezizales often fruit seasonally approximately six weeks after a fire in successional groups over the course of two years. Two methods, pure culture synthesis and PCR-based identification, were used to determine if some of these species were mycorrhizal. Eleven fungal isolates, Anthracobia melaloma, Gyromitra infula, Helvella compressa, Morchella sp.,...
Ten herbicides (atrazine, azafenidin, chlorsulfuron, clopyralid, hexazinone, imazapic, imazapyr, metsulfuron, pendimethalin, and sulfometuron) were evaluated for phytotoxicity in first-year seedlings of eight conifer species (Douglas-fir, grand fir, noble fir, redwood, Sitka spruce, western hemlock, western red cedar, and western white pine). Six of these herbicides (atrazine, clopyralid, hexazinone, imazapyr, metsulfuron,...
Two rectangular 10-ha plots (200 x 500 m) were established in each of the two main forest types of the Ituri Forest, Democratic Republic of Congo (formerly Zaire). The description of stand structure and species diversity, the comparison of the two forest types, and the evaluation of the effects of...
Most soil organic C is in a stable form, associated with clay minerals in the upper soil profile. Upon environmental and land-use changes, stable soil C is subject to losses, which influence the global C cycle and the productivity of terrestrial ecosystems. However, mechanisms controlling soil C destabilization are not...
Devil's club (Oplopanax horridum (J. E. Smith) Miq.) is an indigenous shrub of the Pacific Northwest, often found in the Tsuga heterophylla (western hemlock)/Devil' s club association in western Oregon. In the same family as ginseng, Devil's club is gaining attention for its medicinal properties. While traditional uses of Devil's...
Modified selection thinning has been utilized by some non-industrial foresters in Douglas-fir forests of Western Oregon and Washington for at least 35 years. This silvicultural strategy has not been tested, but has often been associated with reduced volume production and other undesirable effects. It continues to be used on many...
Analysis of the long-term spatial pattern and dynamics of hardwood patches in the Coast Range of Oregon provides numerous ecological insights. Natural and anthropogenic disturbances have contributed to the development of a patchy mosaic of vegetation types in the area. Some hardwood patches in the Coast Range may be the...
Knowledge about vegetation patterns and ecological processes in unmanaged, late-successional
watersheds is needed to provide a foundation for forest management strategies
aimed at conserving native biodiversity. I examined influences of environmental variability
and disturbance history on forest structure and composition in the Cummins Creek
Wilderness, located on the central Oregon...
Soil organic carbon (SOC, kg C m-2) is an important component in evaluating global C stores. The nitrogen (TN, kg N m"2) cycle is closely linked to C and understanding its role is also important. Contents and distributions of SOC and TN in soil profiles, to 1-meter depth, were estimated...
An experiment was established in 1992 in the central Sierra Nevada Mountains of California to assess the effects of high levels of surface organic residues, severely compacted soil, and shrub competition on the development of mixed conifer plantations. This study was conducted in 1997 to determine if selected combinations of...
This thesis examines forest history of a portion of the Douglas-fir Region: Soap Creek Valley, a 15,000 acre sub-basin of the Luckiamute River in northern Benton County, Oregon. The primary reasons for the research were to test oral history methodology, document sub-basin scale forest cover pattern changes, and determine basic...
Controls of substrate quality, temperature, and moisture on woody root decomposition in the Pacific Northwest were explored using chronosequences, time series, laboratory incubations, and simulation modeling approaches at three sites: Cascade Head
(CAH), H. J. Andrews (HJA), and Pringle Falls Experimental Forests (PRF). In the chronosequence study, a structural component-oriented...
Understory conifer regeneration needs to occur beneath conifer-dominated
canopies if two-storied or uneven-aged structures are to be considered for western
Oregon Coast Range stand management. To ensure adequate numbers of seedlings
to meet stocking or habitat structure objectives, planting may be a solution. We
undertook a multi-level study to determine...
The response to various levels of stand density by natural Douglas-fir regeneration, shrub and sprouting hardwood species was studied in the mixed-evergreen-forests of southwest Oregon. Partial-cut old growth (harvested 22-31 years prior) and thinned evenaged (harvested 9-17 years prior) stand types were used as surrogates for intentionally managed uneven-aged stand...
Forest roads constructed in steep mountain landscapes have been associated with a
number of effects on hydrologic and geomorphic processes. This research examined the
effects of forest roads on the flow of water and sediment in drainage basins in the Cascade
range of western Oregon. A study conducted at the...
The fire regimes of a 9,000 hectare study area on the east side of the Southern Oregon Cascades are described. Fire regime parameters included are frequency, extent, and predictability of fire return interval. Severity of two fires is mapped by type of evidence. Changes in fire regime due to fire...
I investigated the population dynamics of fireweed (Epilobium angustfolium), foxglove (Digitalis purpurea) , and woodland groundsel (Senecio sylvaticus) to understand
their colonization, persistence, and extirpation in Pacific Northwest Douglas-fir forests. Factors affecting the species' frequency and abundance in forest communities were evaluated. Their population dynamics were modeled and field experiments...
This study examined the effect of fire regime on coarse woody debris (CWD) mass using a combination of field data and modeling. The objectives were to use field sampling to determine how CWD differs between two areas that have had different fire regimes, and investigate how fire frequency and severity,...
As a key factor contributing to slope stability, in-stream habitat for aquatic species (e.g., salmonids), nutrient cycling, and corridors for upland species, riparian vegetation and its maintenance is of critical conservation importance. Subsequently, the chronic degradation of aquatic and riparian ecosystems in the semi-arid and arid landscapes of the western...
Fire history and fire regimes were reconstructed for a 450 km² area in the central
western Oregon Cascades, using tree-ring analysis of fire scars and tree origin years at
137 sampled clearcuts. I described temporal patterns of fire frequency, severity, and size,
and interpreted topographic influences on fire frequency and...
Management of habitat for bats requires sound information on their habitat requirements. I used radio telemetry to identify 80 roosts for 24 long-eared myotis (Myotis evotis); 74 roosts were identified for 21 females and 6 roosts for 3 males.
Females primarily used dead and defective conifer trees (n=22) and conifer...
One of the goals of ecosystem management is to integrate management of many species and processes across a range of temporal and spatial scales. I investigated the relationship between small mammals and amphibians at 3 spatial scales. My objective
was to identify, habitat associations of forest floor vertebrates at the...
The population genetic structure of ponderosa pine (Pinus ponderosa Dougi.) in the Willamette Valley of Oregon was investigated. Cones were collected from native stands of ponderosa pine from the Willamette Valley, eastern Oregon, southwest Oregon and the Puget Sound Basin of Washington. Seeds were subjected to isozyme analysis of 12...
Because of their small genomes, facile clonal propagation, fast growth, and
susceptibility to Agrobacterium transformation, poplars (genus Populus) are widely
considered model systems for the application of molecular genetics and biotechnology
in forestry. However, a major concern over commercial use of genetically engineered
trees is the release of transgenes into...
Remote sensing technologies have proven useful and cost-efficient for quantifying various forest vegetation characteristics over multiple scales. However, significant limitations were encountered in each of two related experiments conducted to explore their potential to supplement or replace traditional, single-species biomass equations for estimation of ground vegetation and tree overstory on...
Western redcedar (Thuja plicata Donn.) is a valuable commercial species found in
the northwestern United States and southwestern Canada. This dissertation includes four
papers focused on wood and stem characteristics of second-growth western redcedar, and
how those characteristics vary within the stem or how they are influenced by cultural
practices....
Disturbances are a prevalent and important part of ecosystems. Many landscape patterns that we find today were created, maintained, and changed by natural disturbance regimes. This is especially true for fire, which has historically been a common, natural disturbance in the western U.S forests and grasslands and many other parts...
Many herbivores of the Pacific Northwest rely on forest understory shrub leaves for a source of nitrogen, energy, and moisture. I measured nitrogen, protein-binding capacity, and condensed tannin concentration as indicators of available nitrogen; cell wall constituents and lignin as indicators of available energy; and moisture concentration in young and...
The broadest goal of the research covered in this thesis was to contribute
to our limited knowledge of high elevation forest soil ecology. Based on the reeds
of funding agencies, specific objectives were to examine 1) how climate-induced
Abies lasiocarpa ([Hook.] Nutt.) forest expansion affects soil nutrient pools, 2) the...
Despite the critical ecological roles of structural features in forests, ecologically
relevant quantitative measures of structure that allow comparisons among forest stands
are still limited. A new index, the structural complexity index (SCI), was developed to
characterize and compare the structural complexity of different forests. Point patterns
of stem-mapped trees...
The effects of initial leaf litter chemistry of 16 common coniferous and deciduous hardwoods and shrubs on their annual decomposition patterns were studied on the H.J. Andrews Experimental Forest (Oregon). Leaf litters were characterized by their chemical qualities, which included measurement of elemental fractions (C, N, P, K, Ca, Mg),...
Tropical forests are of global importance with respect to their influence on
biogeochemical cycles, climatic patterns, and as large reservoirs of biodiversity. Yet, few studies have quantified their structure, biomass, and carbon pools; basic
information necessary to better understand the global function of tropical forests. The RADAMBRASIL project was conducted...
Forest spatial pattern is a primary interest of landscape ecology due to the relationships between spatial configuration of biotic components and ecological processes. The spatial pattern must be measured in meaningful ways so that relationships between forests and their environment can be analyzed. Aerial and satellite imageries provide ecologists a...
The survival, growth, foliar nutrient status, ectomycorrhiza (EM) colonization,
and associative N-fixation of ponderosa pine seedlings (Pinus ponderosa var. ponderosa
Doug!. ex Laws.) were studied under different gap sizes in forest canopy during the first growing season. Seedling performance variables were assessed relative to gap size of the forest canopy...
Plant succession is among the fundamental concepts in ecology. Studies addressing plant recruitment, successional mechanisms, and the role of root-colonizing fungi with focus on dark-septate endophytes (DSE) were
conducted in the laboratory and on the forefront of receding Lyman Glacier (North Cascade Range, Washington, U.S.A.). Primary successional studies primarily focus...
Patterns of western hemlock regeneration were studied in relation to forest structural development and environment in the Oregon Coast Range. Density of western
hemlock seedlings was examined across the climatic gradient from cool, moist coastal
areas to the seasonally hot and dry Willamette Valley Margin. Seedling densities were most strongly...
Most recent research on stream amphibians in the Pacific Northwest has focused on associations with reach-level or stand-level environmental features. Little is known about landscape-level distributions of these species or landscape-level aspects of their life-histories. I used a watershed-wide sample and logistic regression to develop models and maps of probability...
The Regional Vegetation Management Model (RVMM) predicts the effects of associated vegetation on the growth and yield of young Douglas-fir (age [less than or equal to] 20 years) in the Pacific Northwest, and is a 'front-end' growth model for existing rotation-age growth models. Objectives of this thesis are to: (a)...
The goal of this study was to determine whether annual growth ring variables of
young coastal Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco.)
growing in progeny tests are sensitive to availability of soil moisture during the growing season. If ring variables are found to respond to soil moisture deficit (SMD)...
Forest floor vertebrate species presence and abundance may be influenced by the volume and cover of coarse woody debris (CWD) in managed forests. I studied macro- and microhabitat associations of vertebrate species in 18 closed-canopy stands ranging in CWD volume from 14 to 859 m3/ha. Pitfall traps were used to...
Allochthonous litter inputs are a primary source of organic matter in low-order
forested streams. A major component of this litter moves through small streams as fine
particulate organic matter (FPOM). Litter decomposition has been well studied, but few
studies have examined benthic FPOM (FBOM) dynamics. The purpose of this study...
Stem defects, including sinuosity, large branches, and the occurrence of steep-angled
branches (e.g., forks and ramicorns) can occur with high frequency in young
plantations of Coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco).
The importance of including these stem defects as criteria in early selection depends, in
great part, on...
Coastal Douglas-fir (Psuedotsuga menziesii (Mirb.) Franco) 1 + 1 seedlings were fertilized with two types of fertilizers (NB4NO3+K2SO4 and (NH.4)2 SO4+KC1) at four rates (0, 80, 160, 320 kg N and K/ha) split over 3 application dates (September 19, October 13, November 1, 1996). By January 10, total Kjeldahl nitrogen...
Land-use change in forested regions of the tropics is currently one of the largest
anthropogenic perturbations on earth; it is a force capable of altering biogeochemical cycles at local, regional, and global scales. However, significant uncertainties exist concerning the impact of land-use change on biomass and elemental pools of tropical...
Hypogeous fungi are a critical component of forest ecosystems world wide. In Pacific Northwest forests, they are the base of the food chain of the threatened Northern
Spotted Owl. As part of The Forest Ecosystem Study (a interdisciplinary study designed to
increase development of suitable spotted owl habitat), diversity and...
Bioassays using red alder and snowbrush plants grown in soils collected
from a clearcut, a young Douglas-fir plantation, and an old-growth stand were
conducted. Sites are located at the Andrews Experimental Forest, Oregon. In
the first bioassays, more alder than snowbrush plants survived and nodulated.
Of the plants that survived,...
Infestations of the western pine shoot borer (Eucosma sonomana Kearfott) in young stands of ponderosa pine (Pinusponderosa Lawson), were surveyed on the Deschutes National Forest. Elevation, slope, aspect, tree height, tree diameter, number of shoots in the terminal whorl, stand density, stand age and plant association for each stand were...
Analysis of import trade since 1976 shows that forests of the Pacific Northwest provide
Japan with the largest share of pine mushrooms (Tricholoma spp.) outside of East Asia.
To determine whether North American pine mushrooms (Tricholoma magnivelare (Peck)
Redhead) merit more intensive management in the southern Cascade Range, a major...
From the 1920's through 1951 several severe fires occurred in the predominantly conifer forest ecosystems of the northern Oregon Coast Range. Of the 211,151 ha. of mapped area, 57 percent was burned. The effects of frequent fires with high severity on forest ecosystems over time at the landscape level is...
Xylem anatomy is a strong determinant of water transport efficiency and is therefore an important component of the overall hydraulic strategy of any woody plant.
However, in addition to its role in water transport, xylem also serves in mechanical
support, and these two functions may represent conflicting design requirements. To...
Soil effects from mountain beaver (Aplodontia rufa ) burrowing were
investigated in Oregon Coast Range soils formed from Tyee sandstone. The potential
for observed changes in soil to affect productivity was assessed. Soil horizons from
mountain beaver mound soil and adjacent unmounded profiles were collected with a
monolith-type quantitative sampler....
The objectives of this study were to determine the species composition and density of natural conifer regeneration following selective logging in southeast Alaska.
Therefore, we quantified the density and size of new cohort spruce and hemlock and current seedling bank in 17 selectively logged stands. All stands were in mixed...
Despite the importance of rain and snowmelt in causing peakflows in the Pacific
Northwest, the interactive effects of a snowpack and watershed physiography on
streamflow are largely undocumented. This study investigated the influence of soil and
snowpack moisture on peakflow hydrograph shape in three small (< 60 ha) control sub-watersheds...
This study was conducted to investigate why root disease centers east of the
Cascade crest tend to be larger in diameter and more abundant than their counterparts to
the west, within subalpine forest stands of central Oregon. The trend in a 290 km² study
area appeared opposite of what was...
There is limited information on how to manage young forests of the Pacific
Northwest to benefit wildlife populations. Commercial thinning is becoming more important in young forests both as a tool for timber management and to hasten the
development of old-forest characteristics. There is some evidence that many species of...
Trees that survive disturbances can form a prominent legacy which may influence
post-disturbance successional pathways. The effects of biological legacies on community
dynamics is a critical question in ecology. In the present study, I examined two mapped
stands in which old-growth remnant trees, survivors of partial fires, emerge above a...
Southwest Oregon presents an environment of hot dry summers, cool moist winters, and rocky, shallow soils. The establishment of conifer plantations in this region presents challenging problems for initial seedling survival and subsequent growth. Three areas of concern include early conifer growth after seedling establishment, growth of competing hardwoods within...
Improved accessibility in remote noble fir (Abies procera Rehd.) stands and the
realization of the value of noble fir wood have led to increased pressure to enter and
actively manage noble fir stands in Oregon and Washington. This study examined the
incidence of infection and decay caused by Heterobasidion annosum...
In order to better understand the evolutionary patterns revealed by molecular
markers, we studied genetic diversity and differentiation of populations and races of
Douglas-fir using randomly amplified polymorphic DNA (RAPD) markers of nuclear and
mitochondrial origin. We conducted a range-wide survey of RAPD diversity and
differentiation, and compared RAPDs and...
I analyzed the relationship between avian abundance and landscape structure at five spatial resolutions for 30 subbasins in the central Oregon Coast Range using remotely sensed data and a geographic information system (GIS). I developed maps of forest successional stages from Landsat Thematic Mapper (TM) data at a spatial resolution...
I studied selection of winter den sites by northern flying squirrels (Glaucomys sabrinus) in forests of the Oregon Cascades. Fifty-six squirrels were radio-collared in three managed, 80- to 1 30-year-old Douglas-fir stands on the Umpqua Nationa Forest during the winters of 1994-95 and 1995-96. Squirrels were located at their den...
Associations between occupancy patterns of a montane anuran species, Rana cascadae, and habitat structure at multiple scales were examined to investigate how population structure may influence persistence in spatially and temporally heterogeneous environments. Predictions were based on population dynamics suggested by source-sink and metapopulation models. Potential sites in three basins...
Riparian areas that can be used as reference sites on which to base goals of vegetation restoration have not been documented in the Oregon Coast Range. I examined the composition and distribution of unmanaged riparian overstories in the central Oregon Coast Range along nine streams which have experienced minimal disturbance...
The goal of this thesis was to determine the physiological mechanisms that link adverse preplanting treatments of Douglas-fir, such as exposure and root pruning, to the phenomenon of transplanting shock. The objective of experiments 1 and 2 was to measure the effect of exposure and pruning on the physiology and...
The detection and mapping of large scale changes to forested landscapes is increasingly important in ecology and management. I used Landsat TM and MSS imagery to map forest cover in 1992 for a 4.2 million ha area of the interior of British Columbia with an overall classification accuracy of 79%....
Red alder (Alnus rubra Bong.) is recognized as an important source of nitrogen to
ecosystems that it inhabits. I examined N dynamics within alder trees, alder leaf litter, and the soil beneath alder leaf litter. ¹⁵Nitrogen, a stable isotope of N, was used as a tracer to follow the movement...
This research examined thinning effects on stand structure and species composition in
50- to 120-year-old Douglas-fir forests. Thirty-two paired stands (thinned and unthinned)
were measured throughout western Oregon, as were 20 old-growth stands for comparison. Thinnings occurred 10 to 24 years previously and ranged in intensity from 8 to 60%...
I examined the abundance and habitat associations of terrestrial amphibian species and the species richness of terrestrial amphibian communities in riparian buffer strips, clearcuts, and unmanaged riparian forests. The study was conducted in the western hemlock (Tsuga heteropliylla) vegetation zone of the northern and central Oregon Coast Range. Data were...
The overall objective of this study was to evaluate biomass production and soil ameliorative potential of alley farming in sub-humid India. Effect of the cutting height (40, 80, 120, 160 cm) of Leucaena hedges and root barriers on biomass yield of Leucaena and maize and wheat crops were examined. Trees...
Concerns over the possibility of exotic pest
introductions from eastern Russia to the West Coast of the United States due to proposed log imports raises the question of the effectiveness of possible mitigation measures. Toxicity of methyl bromide to representative pathogenic fungi was tested by exposing Armillaria ostoyae, Heterobasidion annosum,...
In order to restore conifers in hardwood dominated riparian forests 25% of the
experimental reach forests alongside four streams in western Oregon was clearcut.
Clearcutting removed 400 m without residual buffers from a 1600-m streamside forest
reach in patchcuts spanning 100 and 200 meters. To assess the cumulative and direct...
In an agrisilviculture system, trees and crops compete for above and below ground resources. This study aimed at quantifying the effect of shoot pruning and root barriers around pollarded trees on the production of crop and tree components with and without application of fertilizer to the crop. Sorghum (1991 &...
Knowledge of how stream habitats change over time in natural and human-influenced ecosystems at large, regional scales is currently limited. A historical stream survey
(1934-1945) was compared to current surveys to assess changes in poo1 habitats in the Columbia River basin. Streams from across the basin, representing a wide range...
Knowledge of regional-scale patterns of plant community structure and controlling factors is largely qualitative and based on numerous local studies. Data from a subsample of 10,000 field plots were used to quantify and map compositional gradients of woody plant communities across Oregon forests. Canonical correspondence analyses explained 9-14% of the...
A field study was established to explore stand structure and development patterns of
mature, mixed-species forests in the Interior Cedar-Hemlock (ICH) zone: moist cold
subzone of northwestern British Columbia. The species of interest in the study area
were: western hemlock (Tsuga heterophylla (Raf.) Sarg.), western redcedar (Thuja
plicata Donn), lodgepole...
The overall goal of this study was to investigate influences of ectomycorrhizae (EM) and
interspecific carbon transfer on seedling performance in species mixtures. The objectives were to:
(I) determine the potential for EM to link paper birch and Douglas-fir, (ii) quantify gross and net
interspecific carbon transfer, and (iii) evaluate...
Information about forest substrate respiration, nitrogenase activity and
mineralizable nitrogen may be incorporated into carbon and nitrogen budgets that comprise an important element of forest management planning. In this study, substrate respiration, nitrogenase activity and mineralizable nitrogen were measured in two western Oregon Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] stands within...
Riparian ecosystems play numerous and essential roles related to the quality and
flow of water, and food/habitat for fish, and varieties of wildlife. Due to lateral and linear linkages throughout the landscape, these zones influence the integrity of the terrestrial as well as the entire aquatic-riverine ecosystem. Since Euro-American settlement...
Evaluation of meta-sedimentary bedrock as a source of stored water available
to plants in a mediterranean climate is presented based on: root length distribution
(RLD), root morphology, rock water holding capacity and seasonal pattern of water
depletion. Studies were performed in southwestern Oregon under young stands of
whiteleaf manzanita, ponderosa...
This study examined the relationships between the frequency of occurrence and severity of Douglas-fir dwarf mistletoe (Arceuthobium douglasii Engelmann), environmental and stand conditions, and plant communities in the Southern Oregon Cascade Mountain Province. Data for the study was collected from the same ecology plots that were previously used to define...
The influence of shading intensity on performance, chlorophyll fluorescence emissions, the slope of the fluorescence induction curve, chlorophyll contents, and stomatal conductance of four Pacific Northwest conifer species [ponderosa pine (Pinus ponderosa Laws.), Douglas-fir
(Pseudotsuga menziesii (Mirb.) Franco), western redcedar (Thujaplicata Donn.), and western hemlock (Tsuga heterophylla (Raf.) Sarg.)] was...
I used greenhouse and field studies to investigate how intraspecific and
interspecific competition, soil disturbance, and fertilization affect the biomass and
reproductive output of Senecio sylvaticus and Epilobium paniculatum, common winter
annuals which invade and dominate western Cascades forests during the first two seasons
after clearcutting and slashburning.
Field work...
This thesis research examines the effects of film-forming antidesiccants applied to dormant pondexosa pine (Pinus ponderosa Dougl.) seedlings after being lifted and to actively growing seedlings. The basic proposition was that antidesiccants would have a positive effect on reducing water loss in ponderosa pine seedlings. In order to evaluate the...
Tree seedling establishment and growth were studied in experimental canopy gaps to determine the effect of structural and environmental heterogeneity on species dynamics within mature and old-growth Douglas-fir forests in the Cascades of central Oregon and southern Washington. Factors examined included forest age, gap size, within-gap position. substrate, year of...
The purpose of this study was to assess how growth of young to mature Douglas-fir
(Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sar.)
in mixed stands was influenced by the presence of residual trees. Fourteen paired plots with
and without residual trees were examined in a retrospective...
Stem growth, stem form development, and the dynamics of crown recession in young red alder (Alnus rubra Bong.) were studied by analyzing annual growth rings of stems and
knots, annual height increments, projected crown areas, and branch diameters. Forty-one
trees were sampled from three plantation spacing studies, representing ages 1...
Cold hardiness and phenology are important adaptive
traits for perennial plant species in temperate climates.
Timing of growth, dormancy, and associated cold acclimation
and deacclimation represents a delicate balance between
maximizing growth under favorable conditions and minimizing
frost damage under unfavorable conditions. Geographic
patterns of genetic variation in adaptive traits,...
I developed a conceptual model of Douglas-fir bark beetle dynamics and associated host mortality across spatial and temporal scales. I proposed that a hierarchy of factors influence host resistance to attack at different spatial scales. I then tested this model by measuring the association between the occurrence of beetle-kill and...
Endemic populations of pandora moths (Co/oradia pandora Blake), a defoliator of western pine forests, proliferated to epidemic levels in central Oregon in 1986 and increased dramatically through 1 994. Golden-mantled ground squirrels (Spermophilus lateralis Say) consume adult pandora moths, but reject nutritionally valuable eggs from gravid females. Feeding trials with...
Douglas-fir and grand fir seedling establishment and plant community regeneration were examined in a western Oregon forest following harvest in three
different silvicultural systems: clearcut, two-story and patchcut. The two-story system
consisted of removing all but 10 to 12 trees per acre. The patchcut system consisted of
harvesting 1/2 acre...
There is renewed interest in agroforestry as a management strategy for marginal agricultural lands in western Oregon. Silvopastoral systems combine tree and
forage production, which involve crops and practices familiar to the area. The objective of this study was to determine how
management influences the physiology and ecological interactions of...
Riparian forests in the central Oregon Coast Range vary along a coniferous-deciduous compositional continuum. Variations in structure and composition affect water quality, fish and wildlife, biodiversity, timber, and aesthetics. A retrospective approach was taken in this study in order to understand and compare the structure, pattern, and history of an...
The coniferous forests of the Pacific Northwest are
affected by a variety of endemic fungal root pathogens. Forest
disease surveys have noted the presence of two or more of
these root pathogens infecting the same stump or root, and it
has been suggested that these fungi may be interacting
synergistically....
The main objective of this study was to evaluate the interaction between
herbaceous competition, fertility, and seed source on Douglas-fir survival and
growth. A secondary objective was to evaluate the effect of these various factors
on the production of lammas shoots and the selectivity of deer browse. Finally,
the role...
Most of the methods currently used to measure root respiration introduce various disturbances which may lead to biased results, and require destruction of roots which does not permit repeated measurements of root growth and respiration. A root box method was developed for measurement of root respiration, as well as root...