Remote sensing of variables necessary to estimate net primary
production of vegetation over large temporal and spatial scales has been a
goal of climate change research. This thesis consists of two studies that
address the reliability of satellite and airborne sensors to quantify a basic
component of all production models,...
The importance of pheromones in insect control relies both on
their ability to reduce pest populations and on their relatively benign
effects on nontarget organisms. This study was conducted to test the
effectiveness of a pheromone application for mating disruption of the
ponderosa pine tip moth, Rhyacionia zozana (Kearfott), and...
This research assessed the effect of western juniper (Junlperus
occldentalls) removal on understory plant production and cover and
ponderosa pine (Pinus ponderosa) growth and plant water status.
A complete randomized block design, with four blocks and four
treatments was established in the summer of 1984 near Prineville,
Oregon. The four...
The ability of northern goshawks (Accipiter gentilis) to persist in intensively
managed and selectively harvested forest habitats is largely unknown. To address the
concern that populations of northern goshawks in eastern Oregon may be declining in
response to habitat alteration, I studied occupancy rates and habitat relationships of
nesting goshawks...
Xylem conducting tissue or sapwood is an important storage organ
for water, carbohydrates, and nutrients, and this storage helps trees
accommodate environmental change. However, the living ray parenchyma
cells in sapwood, which store the carbohydrates and nutrients,
require energy for maintenance. I examined how sapwood maintenance
costs vary among species,...
Trees that survive disturbances can form a prominent legacy which may influence
post-disturbance successional pathways. The effects of biological legacies on community
dynamics is a critical question in ecology. In the present study, I examined two mapped
stands in which old-growth remnant trees, survivors of partial fires, emerge above a...
Improving vegetation management decisions in Pacific Northwest forests requires a better understanding of the interactions between
planted conifers and associated vegetation. A practical index of interspecific competition, and quantitative models predicting conifer performance from such an index are particularly needed. To meet this
need, neighborhood models of interspecific competition were...
The role of disturbance in seed germination and first-year survival of red alder (Alnus rubra) was studied over two growing seasons at four sites representing a climatic gradient within the central Coast Range of Oregon. Disturbance affected red alder seed
germination and seedling establishment by altering the temperature and moisture...
Seasonal trends in forage production and environmental parameters
for five plant community types within a northeastern Oregon riparian zone
were described and modeled using correlation and path analysis. Wet
meadows produced the greatest amount of herbage biomass, followed by moist
bluegrass meadows, gravel bars, forests and dry bluegrass meadows. Trends...
Tree growth and soil nutrient responses to prescribed underburning were determined for a period of up to 12 years at four sites in northcentral and central Oregon ponderosa pine stands (Pinus ponderosa Dougl. ex Laws).
Differences reported are significant at a = 0.10. During the first 4-growing-season-measurement period after
underburning,...