Breeding ecology and behavior were investigated in a field study of three sympatric anuran amphibians in the Oregon Cascade Mountains: the western toad (Bufo
boreas), the Cascades frog (Rana cascadae) and the Pacific treefrog (Hyla regilla). A comprehensive study of the western toad mating system was conducted at three populations...
Since their range expansion into the Pacific Northwest, anecdotal evidence suggests that northern barred owls (Strix varia varia) may be displacing northern spotted owls (Strix occidentalis caurina). My objectives were to characterize barred owl distribution and population increase in Oregon, investigate spotted owl territory performance before and after barred owl...
Disaggregative and individual-tree/distance-independent modeling methods are
compared and contrasted. Differences between the two are related to differences in functional
and apparent resolution and may be illustrated using aggregation theory. When considering
models of different levels of resolution describing a given phenomenon, invariance with respect
to the aggregation implied (symmetry) may...
Most reserves fail to capture the habitat heterogeneity necessary to maintain viable populations of wide-ranging species. Methods to determine defensible dimensions of reserves and reserve networks are needed. The primary goal of this study was to develop such methods for lowland tropical forests by examining habitat- and spatial-use patterns of...
As concern over global warming intensifies, sequestration and storage of atmospheric CO2 has become an important scientific and policy issue. Confusion persists, however, over interpretation of forest carbon (C) source-sink dynamics, in part because conclusions drawn depend on temporal and spatial scales of analysis (e.g. day-week
scale vs. successional-scale), type...
Seven species of water-dependent birds (northern phalarope,
Phalaropus lobatus; American avocet, Recurvirostra americana; Wilson's
phalarope, P. tricolor; eared grebe, Podiceps nigricollis;
ring-billed gull Larus delawarensis; California gull, L.
californicus; and northern shoveler, Anas clypeata) were studied
during the fall migrations of 1982 and 1983 to determine the diets and
foraging...
The Tillamook and Kilchis subbasins of the Tillamook Bay watershed (Oregon Coast Range) have differences in geology and land use history and, therefore, varied environmental conditions that could affect fish assemblages. Fifty-two randomly selected wadeable stream reaches in these two subbasins were surveyed for stream habitat and fish assemblage composition...
The United States invests tens of billions of dollars in higher
education each year. This had led many researchers to estimate the
marginal and average rates of return to these expenditures. Past
works, however, have been partial in scope. That is, they have
counted only the benefits of higher education...