Forecasts of the impacts of climate change have traditionally focused on individual species and their phenotypes, phenology, or distribution. However, shifts in species distributions and the resulting reorganization of community composition represent an important violation to the assumption of species acting in isolation. Whereas species may respond individualistically to climate...
Many of Earth’s terrestrial large carnivore species are threatened with extinction. As a result, some of the ecological effects associated with these species may be lost. With the goal of furthering large carnivore conservation research, I conduct three global scale analyses involving these species. First, I explore prey depletion as...
Expansion of Juniperus occidentalis into the sagebrush steppe has resulted in significant changes in understory composition. A consequence of increased J. occidentalis dominance may be a depletion of the seed bank. The potential for depletion is problematic because a reduction in the amount of species available from the seed bank...
Sequence data from nrITS and cpDNA have failed to fully resolve phylogenetic relationships among Pinus species. Four low‐copy nuclear genes, developed from the screening of 73 mapped conifer anchor loci, were sequenced from 12 species representing all subsections. Individual loci do not uniformly support either the nrITS or cpDNA hypotheses...
The goal of this dissertation is to examine the effectiveness of high intensity-short duration goat browsing for the control of Himalayan blackberry (Rubus armeniacus) and English ivy (Hedera helix), two widespread noxious weeds in the Pacific Northwest.
The effects of goat browsing on Himalayan blackberry vigor, as quantified by densities...
Crested wheatgrass (Agropyron cristatum (L.) Gaertn.) is a nonindigenous perennial grass that was introduced to North America to improve the condition of degraded rangelands. It has proven to be a successful revegetation species due to its superior ease of establishment, strong competitive ability, and ability to tolerate grazing. However, crested...
Thirteen different habitat parameters were measured either quantitatively or
qualitatively around seven different Salix (willow) species on a defined reach of stream
on the southwestern slope of Steens Mountain in southeastern Oregon in order to both
broaden the current information base of riparian ecology and inform future willow
plantings aimed...
Craterellus tubaeformis is a small to medium-sized forest mushroom that is fairly common in the Douglas-fir/western hemlock forests of the Pacific Northwestern United States and is most often associated with decayed coarse woody debris. In this study, the mycorrhizae of Craterellus tubaeformis in western Oregon is identified by DNA analysis...
Biology of Scaptomyza apicalis Hardy (Diptera: Drosophilidae) was studied in
relation to its host, meadowfoam, Limnanthes alba, a recent oil seed crop grown in the
Willamette Valley, Oregon. Populations of flies and larvae were monitored weekly over
three consecutive crop-years beginning in 1996. Yellow sticky traps gave relative
population estimates...
Prescribed fire can release herbaceous forages from woody plant competition thus promoting increased forage plant production, vigor, and accessibility. Prescribe fire also consumes standing litter thereby improving forage quality and palatability. Consequently, prescribed fire is commonly considered an effective tool for manipulating livestock distribution on rangelands. Efficacy of this tool...