I conducted field studies to determine the effect of insect herbivory and
intraspecific plant competition on ragwort Senecio jacobaea. The objectives were to
determine the patterns and causes in the distribution of the ragwort flea beetle
Longitarsus jacobaeae foraging among varying densities of ragwort, to measure the
behavioral and numerical...
Sexual maturation and sex differentiation comprise facets of a
common theme: reproduction. The endocrine system regulates many
of the critical physiological processes necessary for reproduction and
offers a framework within which technologies can be developed for
controlling sexual maturation and sex differentiation. The studies
described in this thesis were undertaken...
A plant community classification was developed describing the comprehensive variation of oak vegetation currently occupying the Willamette Valley Ecoregion of western Oregon. Multivariate statistical analyses were used to classify field collected floristic and habitat data. Field sampling targeted minimally managed, homogenous vegetation stands with a significant oak component occupying at...
The cultural and ecological values of Pacific lamprey (Lampetra tridentata) have not been understood by Euro-Americans and thus their great decline has almost gone unnoticed except by Native Americans, who elevated the issue and initiated research to restore its populations, at least in the Columbia Basin. They regard Pacific lamprey...
Coastal cutthroat trout is one of three cutthroat subspecies found in Oregon. The coastal subspecies, which is closely related to steelhead/rainbow trout and Pacific salmon, displays the most diverse and flexible life history of any of the Oregon salmonids. Coastal cutthroat can be found in streams and rivers from the...
Chinook salmon are the largest of any of the salmon in Oregon. Mature fish range from less than 2 pounds to more than 70 pounds. In the late 1800s, chinook salmon were almost the only species taken for canning in the Columbia River, with production peaking at 43 million pounds...
Anglers and naturelovers prize steelhead trout for their mystique and power. Oregon has two subspecies of steelhead (so-called because of the metallic appearance of maturing adults) or rainbow trout: a coastal form and an inland form.
Twenty-two steelhead trout (Salmo gairdneri) containing coded wire tags (CWT's) were captured in gillnets fished by the Oshoro-Maru in the Gulf of Alaska and along 180 during 1982-85. These fish originated from North American streams and hatcheries in British Columbia, Idaho, and Washington. One fish was age 0.1, 16 were...
Bench scale column studies were used to examine the partitioning of microorganisms between groundwater
and a geologic medium and to examine the effect of hydrogeology (i.e., porous- versus fracture-flow) on
organism partitioning. Replicated columns were constructed with intact basalt core segments that contained
natural fractures and with the same basalt...
