Stem form development of trees in response to wind has been established in the literature to be a response to stem sway induced by the wind. The response is manifested in modifications to height and diameter growth which strengthen the stem against wind stresses. Experiments in the literature show that...
A silvopastoral system using a Douglas-fir
(Pseudotsuga menziesii) tree crop and subclover (Trifolium subterraneum) as a nitrogen-fixing forage crop was
investigated near Corvallis, Oregon, during 1983-1985.
Treatments included all possible combinations of three
planting patterns (no trees, trees planted 2.5 m apart in a
grid, and clusters of five trees...
Aphids are a widespread family of plant pests, whose abilities to suppress shoot
and root growth are well documented for many terrestrial plants. Only a few studies have
been conducted on conifer aphids of the genus Cinara. Cinara pseudotsugae are known
to attack Douglas-fir seedlings, an important crop in the...
Computer simulations and experiments were used to determine
the basis for skewness and inequality in size structures
(frequency distributions of Individual plant sizes) prior to
self-thinning mortality. In simulated stands, density-dependent
neighborhood heterogeneity caused variability in the growth rate
of individuals with the same size, and such variability caused
skewness...
This thesis examines the competitive aspects of Douglas-fir trees growing with two commonly associated competitors--red alder and grass--at varying densities. Two Nelder plots in three different environments in the Oregon Coast Range were studied. The sites represented the warm, dry climate of the Willamette Valley; the warm, moist climate of...
Allometric equations are useful tools for predicting tree biomass when direct measurements are impractical. Any factor affecting plant growth can be a significant variable in allometric equations. Density and species proportion are spatial variables that influence tree growth and should be considered when developing allometric equations. This consideration is especially...