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...
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...
Fire is a major disturbance process in many forests. Long-term studies of the biogeochemical effects of fires, especially on soils, are very rare.
Consequently, long-term effects of fire on soils are often hypothesized from
short-term effects. In a chronosequence study, I studied 24 western Cascades
(Oregon) forest stands thought to...
This study examines the long-term role of interference on stand development of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and red alder (Alnus rubra Bong.) planted mixtures in the Central Cascades of Oregon, USA. The two species are common associates in naturally regenerated and planted conifer stands in the Pacific Northwest. Due...
Population trends and patterns in species distributions are the major currencies used to examine responses by biodiversity to changing environments. Effective conservation recommendations require that models of both distribution dynamics and population trends accurately reflect reality. However, identification of the appropriate temporal and spatial scales of animal response, and then...
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...
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...
This thesis examines the competitive aspects of Douglas-fir trees growing with two commonly associated competitors--red alder and grass--at varying densities. Two Nelder plots in three different environments in the Oregon Coast Range were studied. The sites represented the warm, dry climate of the Willamette Valley; the warm, moist climate of...
Silvicultural canopy gaps are emerging as an alternative management tool to accelerate development of complex forest structure in young, even-aged forests of the Pacific Northwest. I investigated patterns of nitrogen (N) availability along transects through 0.1 and 0.4 ha silvicultural gaps in three 50-70 year old Douglas-fir forests of western...
Fire severity is hypothesized as an important driver of bird responses to wildfire. For those species that typically respond negatively to increasing severity, Accessibility of high-severity burned forest may be dependent on the proximity of unburned or low-severity burned forest to meet all of the needs of breeding bird species...
