Canopy gap formation is a major factor contributing to maintenance of overstory species diversity and stand structure in forests and may be integral to development of understory shrub and herb layers as well. Acknowledgement of gap formation as a fundamental feature of natural forests has led to consideration of gaps...
This report presents results of an investigation of water and streambed-sediment quality in selected tributaries of the South Umpqua River. Concentrations of inorganic constituents in water (major and minor ions, nutrients, and trace elements) and streambed sediment (primarily trace elements), along with standard field parameters, are tabulated for samples collected...
Logging planning and layout costs were examined for commercial thinning of 40- to 50-yr-old stands of Douglas-fir on the Willamette National Forest in the Cascade Mountains of Oregon. The study consisted of four replications of three silvicultural treatments. Thinning involved three types of logging systems: mechanized cut-to-length (a combination of...
Young Douglas-fir stands were commercially thinned to achieve vegetation- and wildlife-related objectives. Harvesting and forwarding production and costs were compared among three mechanized thinning treatments: light thin [(115 residual trees per acre (tpa)], light thin with 0.5-ac openings (92 residual tpa), and heavy thin (53 residual tpa). The sites were...
Harvesting productivity rates and costs were determined for three
silvicultural treatments used in commercial ground-based thinning of
young stands to achieve timber management objectives and enhance
wildlife habitat. Treatment definitions were based on residual trees
per acre (tpa) after thinning. The treatments were light thin (115
residual tpa), light thin...
Regression models of height growth and survival were fitted to aggregate data for trees, protected and not protected from animal damage, that had been surveyed on Douglas-fir and ponderosa pine plantations in Oregon and Washington. Animal damage significantly affected both height and survival. Dynamic programming analysis-using both soil expectation (Se)...
A 20-year-old Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] stand in the Oregon Coast Range was thinned from about 1,700 to about 350 trees/ac. Subsequent thinnings, under eight different regimes, occurred at ages 23, 27, 30, and 32. Average net periodic cubic-volume growth was strongly influenced by thinning regime, varying from about...