Ecological relationships between D. coccinellae and its coccinellid hosts were examined in the Willamette Valley, Oregon, in 1982. The distribution and relative abundance of seven species of coccinellids from eight collecting sites were monitored to determine percent parasitism by D. coccinellae on a spatial and temporal basis. Host size and...
An outbreak of western spruce budworm Choristoneura
occidentalis in the Blue Mountains of eastern Oregon in
1983 was treated with helicopter applied carbaryl. Effects
of the spraying on forest ants were determined from pre- and
postspray samples taken from two carbaryl sprayed and
two unsprayed plots. In each 0.75-ha plot,...
This thesis presents our investigation of the problem of creating an intelligent tutor for solving algebra word problems that employs effective pedagogy. Among our major concerns are the problems of sufficient knowledge and proper knowledge organization. From student protocols and test papers, we derived sets of general purpose strategic rules...
Lack of stability of soil aggregates for water
movement is a major problem in arid soils due to low
organic matter and higher sodium contents. Soil
amendments for improving stability of structure and
increasing infiltration of water are essential to solve
water management problems in these areas.
Different rates of...
This study was conducted to determine the composition and size of prey consumed by northern fur seals (Callorhinus ursinus) in the eastern Bering Sea. Eighty three northern fur seals were collected in the summer and fall of 1981, 1982, and 1985 for examination of gastrointestinal contents. A total of 139...
A greenhouse bioassay was used to compare the effects
of soils collected at different distances from hardwood
species on the growth, mycorrhiza formation, and foliar
nutrient concentrations of Douglas-fir seedlings. Soil
nutrient concentrations and bulk densities were also
determined. Soils were collected from two southwestern
Oregon sites that had been...
This study characterizes the production of hypogeous sporocarps (broadly referred to as truffles) by ectomycorrhizal fungi within Douglas-fir dominated forests that are considered typical of those found on the west slopes of the central Cascade mountains in Oregon. Three aspects of sporocarp production are addressed: 1) the distribution of total...