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...
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...
Characterization of canopy structure, the horizontal and vertical distribution of the tree crowns in a forest, is important for the management of forests in the Pacific Northwest. The canopy is an important habitat element for many wildlife species, canopy structure affects understory development, and influences various natural processes, such as...
The objective of my study was to examine differences in riparian tree and shrub composition associated with adult aquatic emergence and implications for terrestrial spiders in these sites. Seasonal abundance and biomass of adult emergent aquatic insects, riparian arthropod abundances and spider densities were compared between conifer- and hardwood-dominated sites...
In response to concerns about excessive stand densities and high-severity wildfires, land managers in the western United States are carrying out extensive programs of fuel reduction thinning. How will these sudden reductions in canopy cover and associated changes in habitat affect native and exotic herbaceous vegetation and canopy species regeneration?...
We evaluated the regeneration behavior and early growth rates of 10 non-pioneer canopy tree species in medium-height, semi-evergreen dry tropical forest in Quintana Roo, Mexico. These species provide timber and non-timber forest products for local communities and include evergreen and deciduous species with varied dispersal mechanisms. The species were Coccoloba...
We use qualitative and quantitative methods to explore social and spatial relationships between land ownership and forest cover in the Oregon Coast Range. Using a Geographic Information System (GIS) and regression analysis, we tested for spatial relationships between the structure of land ownership and forest cover across 66 watersheds in...
This thesis examines factors limiting understory herb presence and flowering in young second-growth Douglas-fir (Pseudotsuga menziesii) forests on the west side of the Cascade Mountains, Oregon, USA. I studied the belowground effects of canopy trees on understory herbs and shrubs in old-growth forests using trenched plots from which tree roots...
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...
Interception of precipitation by forest canopies has been found previously to reduce rainfall intensity, but this effect is poorly understood. The goal of this research is to quantify the attenuation of rainfall intensity by forest canopy interception, with the specific objective of estimating the contribution of this attenuation to hillslope...
