The effect of competition on the brood survival of the Douglas fir
beetle Dendroctonus pseudotsugae Hopkins, in down or windthrown
Douglas-fir Pseudotsuga menziesii (Mirb.) Franco was studied in the
field and the laboratory. The investigation of the role of competition
in the population dynamics of the beetle had four objectives:...
The publication of Charles Darwin’s On the Origin of Species, truly a synthesized work of natural history, coincided with the emergence of specialized disciplines in the 19th century. This thesis aims to explore the relationship between the specialization of knowledge, in the form of disciplinization, and the reception of new...
Three species of true firs in the Pacific Northwest--Abies gran-dis, grand fir; A. amabilis, Pacific silver fir; and A. lasiocarpa,
subalpine fir--are severely damaged or killed by an imported insect
pest, the balsam woolly aphid (Chermes (Adelges) piceae Ratz.), Infestations of this insect cause abnormalities in the wood and, in...
A study was conducted over a two year period, 1973 through
1974, on perennial ryegrass-subclover pastures with stocking rates
of 7.4 (moderate), 9. 9 (heavy), and 12.4 (overstocked) ewes per
hectare to establish guidelines on stocking intensity for dryland
improved pastures in western Oregon. Climatic conditions varied
annually and caused...