Reforestation of Pacific Northwest forest-lands with western hemlock has been hindered by unexplained plantation failures.
The purpose of this thesis is to provide information that will help in determining the cause of seedling damage and mortality. The studies focused on the relationship between xylem water potential, xylem cavitation and the...
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....
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...
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...
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 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...
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,...
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...
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...
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 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...
Transplant shock was induced by applying a range of soil water contents to unstored and cold-stored two-yearold (2+0) bareroot Douglas-fir seedlings graded by root volume. Moisture stress had the greatest influence on
morphological characteristics commonly associated with transplant shock. Terminal growth, lateral growth, stem diameter growth, and needle length increased...
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,...
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...
In western Oregon, hardwood trees occupy 20% of the
timberland but account for less than 1% of the timber
harvest. Information about how to manage them effectively
is limited.
The objective of this study was to examine: 1)
effect of thinning on tree growth, plant moisture stress,
and crown cover...
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 goal of this study was to evaluate the ability of two seedling quality evaluation methods to predict the field survival of Douglas-fir (Pseudotsuga menziesii) seedlings. The starch reserves in seedlings have been suggested as a possible predictor of seedling quality. Starch reserves have been shown to decrease during cold...
The increased interest in red alder (Alnus rubra Bong.) management instigated research in growth and yield and stand development of red alder in pure and mixed red alder/Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands. This study had the goa1s of evaluating the accuracy of the currently existing growth and yield tools...
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...
This greenhouse study evaluates the influence of separately and
simultaneously imposed water stress, western spruce budworm (Choristorneura
occidentalis Freeman) defoliation, and inoculation with the root pathogen, Armillaria
ostoyae (Romagn.) Herink, on the growth and biochemical features of Abies .grandis
(Dougl.) Lindi. Seedling biomass, plant moisture status, bud phenology, and
allocation...