Historical aerial photos were used to examine the early phase of forest succession after stand replacement disturbance, covering the Coast Ranges Province (CRP) and the western Cascades Province (WCP) of western Oregon. The study consisted of two components: characterizing the pattern of forest succession in western Oregon; analyzing the influence...
Live western larch, Larix occidentalis Nutt., a tree species resistant to the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, produces the monoterpene 3-carene in higher concentrations compared to Douglas-fir, the preferred host of D. pseudotsugae (Reed et al. 1986). The inhibitory effects on attraction to aggregation pheromones and toxicity of 3-carene to...
When biogeochemical models are applied to large regions, the values of key model parameters are often unknowable. Through field and modeling studies, I examined the potential impact of such uncertainty on estimates of carbon cycling in western Oregon. I found that variation in key leaf traits could be interpreted ecologically,...
This study explored how selected input and redistribution processes affect the amount and arrangement of in-stream wood within the 64 km2 Lookout Creek watershed in the Andrews Forest, western Cascade Range, Oregon. A longitudinal inventory of in-stream wood was conducted over approximately 20 km of stream length in 2nd to...
In the Coast Range of western Oregon, some natural resource managers are converting red alder-dominated riparian areas to conifers to increase the future source of in-stream large wood for salmonid habitat. However, studies in Alaska have shown red alder-dominated riparian areas support greater invertebrate biomass compared to conifer-dominated areas. In...
The nomenclatural history of Gomphus sensu lato began with Persoon in
1797. Over 200 years species of Gomphus sensu lato have been variously classified
also under Cantharellus, Craterellus, Chloroneuron, Chlorophyllum,
Gloeocantharellus, Nevrophyllum, and Turbinellus.
Species of Gomphus sensu lato have been historically characterized as
having aboveground fruiting, fleshy basidiomata with...
Gene flow is a major evolutionary force and an important factor in the breeding and conservation of forest trees. I studied the applicability of SSR markers for measuring pollen-mediated gene flow (i.e., pollen flow) in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). I developed SSR markers, tested alternative approaches for measuring pollen...
Hemlock woolly adelgid, Adelges tsugae Annand, is a serious threat to eastern hemlock, Tsuga canadensis Carriere, in the eastern United States. Infestations of A. tsugae are spreading rapidly and tree mortality caused by the insect is increasing yearly. As part of an integrated management approach, a classical biological control program...
Invasive plants threaten ecosystems and economies worldwide. Classical biological control, introduction of specialist herbivores on invasive plants, is one of the tools employed to reduce the impact of invasive plants. Gorse, Ulex europaeus L. (Fabaceae), an invasive leguminous shrub, is the target of a biological control program in Oregon. The...
The processes that lead to stable, low-growing plant communities and the characteristics of the species that form them are of great interest to rights-of-way (ROW) managers and others wishing to better understand plant community resistance to tree invasion on managed landscapes. The use of stable, low-growing plant communities as a...
The Amazon Tropical Rain Forest is the largest tropical rain forest system, comprising approximately 65% of such forests on earth. Since the 1960's, human populations in the Brazilian Amazon have increased from two to over 20 million. Concomitant urbanization, forest conversion, and economic dependence on resource extraction have exerted severe...
Concentration of carbon dioxide (CO₂) in the atmosphere has increased over the past 150 years. Because CO₂ is one of a number of radiatively active gases, there is concern that global temperatures will rise and climatic conditions will change. Recent research indicates northern hemisphere forests may currently be accumulating carbon...
Agroforestry is a traditional farming practice in American Samoa that has helped to sustain the livelihood of the native population for centuries. These once self-sufficient islands have become economically dependent on U.S monies and other external resources during the past century. Dependency has caused a shift in the carrying capacity...
Two experiments were conducted on the invasive plant species Potentilla recta in northeastern Oregon to investigate both biological and ecological characteristics of the species. Growth analysis was conducted on the plant at three sites over a period of two years (2002 and 2003). Relative growth rate (RGR) was calculated for...
Weed control in Pacific Northwest forests has been criticized for its potential impact on biodiversity. Changes were evaluated in conifer growth, diversity of vegetation in situ and of recruiting plants through different regeneration mechanisms after applying temporally-varied weed control by herbicide treatments based on the critical period concept. Conifer size...
The MODIS NBAR (M0D43B4) data space is explored in terms of biophysical variables with the objective of formulating a MODIS transformation relevant to global vegetation studies. The basic ideas of transform formulation were borrowed from the development of the TM Tasseled Cap transformation, but with differences in sampling strategy and...
I studied riparian forests of four western Oregon watersheds (dry south to wet north) to determine the multiscale controls on woody riparian vegetation. I conducted separate analyses of controls on plant distribution, diversity, and tree regeneration using vegetation and environmental data collected in two related field studies: (1) a multiscale...
Across western Oregon, Washington, and British Columbia, forest management practices over the past century reduced the amount of late-successional forest while
simultaneously increasing the amount of young (less than 80 years old), managed
Douglas-fir (Pseudotsuga menziesii) dominated forests. Recently, concerns over loss of late-successional habitat pushed management objectives on public...
Canopy structure has a significant impact on the canopy hydrology of
Douglas-fir forests in the Pacific Northwest (PNW). Whole canopy rainfall
interception was measured for young Douglas-fir forest and compared to an
old-growth Douglas-fir forest. The old-growth forest had significantly greater
canopy water storage capacity (5) and direct throughfall fraction...
