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Full-Text Articles in Forest Sciences
Urban Impacts To Forest Productivity, Soil Quality, And Canopy Structure In Forest Park, Portland, Oregon, Andrew David Addessi
Urban Impacts To Forest Productivity, Soil Quality, And Canopy Structure In Forest Park, Portland, Oregon, Andrew David Addessi
Dissertations and Theses
Land use practices and exposure to low impact disturbances associated with an urban environment can alter forest structure and function. Past and ongoing research in Forest Park, a large urban forest in Portland, Oregon, suggests that mature mixed Douglas-fir (Psuedotsuga meziesii)-hardwood stands in the more urban end of the park lack a shade-tolerant conifer understory composed of the late successional conifer tree species, such western hemlock (Tsuga heterophylla) and western red-cedar (Thuja plicata). 5-year plot remeasurement data that characterizes productivity and mortality patterns did not show a strong relationship to urban proximity. Plot productivity …
Changes In Populations Of Soil Acari During The First Year After Clearcutting, Sue Ellen Orlaske
Changes In Populations Of Soil Acari During The First Year After Clearcutting, Sue Ellen Orlaske
Dissertations and Theses
Soil samples taken from a clearcut and adjacent uncut site of a Douglas Fir and Western Hemlock old growth forest in the Cascade Range of southern Washington showed greatly reduced adult and juvenile population densities of macro-phytophagous, microphytophagous, and predatory soil acari in the clearcut. These effects appeared to be due to high lethal summer litter temperatures and reduced pore spaces due to scarification. Also, the number of species of acari in the clearcut was lower than in the control after clearcutting.
The Allelopathic Potential Of Rhododendron Macrophyllum In A Western Cascades Clearcut, Ivan W. Clark
The Allelopathic Potential Of Rhododendron Macrophyllum In A Western Cascades Clearcut, Ivan W. Clark
Dissertations and Theses
The purposes of this study were to determine if Rhododendron macrophyllum has the potential to inhibit the growth of other species through the production of water-soluble toxins which are leached out of its litter by rainfall, and to determine if this potential is realized in the field. The study was therefore composed of two part: 1) a series of bioassays to determine the presence an activity of water-soluble phytotoxins in R. macrophyllum leaf litter, and 2) a field study to describe vegetational patterns associated with R. macrophyllum in a western Cascades clearcut.
Mutual Exclusion Between Salmonberry And Douglas-Fir In The Coast Range Of Oregon, Kenneth Ray Still
Mutual Exclusion Between Salmonberry And Douglas-Fir In The Coast Range Of Oregon, Kenneth Ray Still
Dissertations and Theses
One serious problem faced by the forest industry in the Pacific Northwest is poor regeneration of commercial trees on land which is harvested and subsequently dominated by brush species. In Coastal Oregon, salmonberry is one of these brush species. Detailed investigations of field sites indicate that light intensity in the brush stands was low but sufficient for germination and early growth of Douglas-fir seedlings and soil moisture percentages and nutrient levels were high enough to support early Douglas-fir growth. Laboratory tests demonstrated the presence of leachable phytotoxins in the leaves of salmonberry. The hypothesis resulting from this study is that …