In intensively managed forest plantations in the northern Oregon Coast Range, herbicides are often applied during site preparation and early stand regeneration to reduce competition for resources for planted conifer seedlings. In addition to reducing competition for crop trees, herbicide applications may affect soil processes including decomposition and nutrient cycling,...
It is difficult to treat the heartwood of many wood species with liquid preservatives using conventional liquid processes. Supercritical fluids (SCF) used as carriers of preservatives to impregnate refractory wood species may be an attractive alternative to conventional liquid carriers. While SCF impregnation has many potential advantages, some wood species...
Five different test methods to determine the parallel-to-grain shear
strength of Douglas-fir structural lumber were compared. Four methods
assessed the shear strength of lumber sections having a full nominal two by
four inch cross-section. These were: three-point bending, four-point bending,
five-point bending, and torsion. The fifth method was the ASTM...
Metham sodium or NaMDC is one of the four major soil
fumigants that are currently registered for controlling
internal decay of wood products in use. Fumigants are used
primarily in utility poles but are also applied to piling,
timbers and other large wood members.
NaMDC must decompose to fungitoxic compounds...
The goal of this research is to develop automatic techniques for
identifying defects in Douglas-fir veneer. To achieve this goal,
computer vision techniques, in particular image-processing, will be
applied. Several pre-processing steps may be required to enhance
images in making further analysis easier, faster, and more reliable.
Pre-processing is often...
Many higher plants have mycorrhizae associated with their roots. These structures are often essential for survival and growth (Harley & Smith 1983). Mycorrhizae are known for the abilities to enhance nutrient absorption. While nitrogen-fixing organisms are found as components of the mycorrhizosphere, mycorrhizal fungi are not presently known to fix...
The two-parameter Weibull function was used to predict forest stand diameter distributions and growth. Diameter distribution models were developed for even-aged Douglas-fir stands, 20 to 40 years old, in Oregon and Washington. In order to test if the two-parameter Weibull function can adequately describe the diameter distributions of such stands,...
Douglas-fir and western hemlock growth and stocking were examined on two neighboring clear-cut watersheds in the Western Cascades of Oregon and related to the intensity of burning and logging disturbance, habitat type, soil type, aspect and the influence of percent cover of both invading Ceanothus species and residual Acer circinatum....
Bigleaf maple (Acer iaacrophyllunt) is a deciduous, persistent, sprouting species that frequently accounts for as much as 20% of the basal area in Douglas-fir forests. Because of the lack of knowledge of the role of bigleaf maple in Douglas-fir forest ecosystems and the problems that it poses as a vigorous...
Nitrogen, phosphorus and sulfur concentrations were measured in the soil, foliage and litter of Douglas-fir growing in pure Douglas-fir and mixed conifer stands. On four sites of contrasting fertility and climatic conditions, plots had been modified by the introduction of alder, thinning, or by a single application of nitrogen fertilizer...
The purpose of this study was to determine if thinning, fertilization or a combination of thinning and fertilization had an effect on overall average specific gravity, modulus of elasticity, modulus of rupture, fiber length and intra-ring characteristics. Material for this experiment consisted of 7 trees randomly selected from each of...
This paper describes a study done on swinging and processing whole tree, tree length and log length pieces in a smallwood Douglas-fir thinning. Two machines were evaluated, a 70 horsepower rubber tired skidder and a hydraulic loader mounted on a 6 x 4 live tandem truck.
The study took place...
An energy balance analysis was performed on each of four
transplanted Douglas-fir [Pseudotsuga menziesii (Mirb.) Francol
seedlings growing on two cutover sites in southwestern Oregon. The
two sites were a clearcut and a partial-cut (shelterwood) side by
side, with a pair of seedlings used on each site. One seedling of...
A rapid and efficient procedure that required no partitioning was developed for the purification of abscisic acid (AbA) from the needles of Douglas-fir seedlings. Extracted needle pigments were removed by a
PVP column and the eluted AbA was concentrated on a DEAE column. The AbA was eluted from the DEAE...
Field and greenhouse bioassays were used to compare the mycorrhizal associations of Douglas-fir seedlings from undisturbed forests, and nonburned and burned portions of clearcuts on three Sites in the west-central Cascades of Oregon. Field soil transfers and greenhouse soil pasteurization and reinoculation were used to investigate soil biology and inoculum...
This study compared three nursery handling processes from the time just before lifting to the time seedlings are placed in cold storage after grading, sorting, and packing at the nursery. The seedlings handled in these different ways were compared first in terms of the temperature and plant moisture stresses they...
The purpose of this study was to determine if amount and kind of thinning had an effect on wood specific gravity, modulus of rupture, modulus of elasticity, growth rate, or pulp yield and kappa number. The study involved 24 1/5-acre plots, three plots in each of eight thinning treatments. The...
Three methods--radial compression strength, color indicators of decay and micro-toughness, an examination of tracheid fracture patterns, were evaluated for detection of early decay and for application to field use. Three-eighth-inch diameter plugs 3/4-inch long, cut from the sapwood and heartwood of a Douglas-fir pole free of decay, were decayed by...