The amount and quality of competition among
individuals in developing plant communities is an important factor determining community structure, composition and development. In perennial plant communities, this competition is reflected by shifts in carbon allocation among plant parts and can result in long-term structural differences between neighboring individuals. This study...
In terms of production forestry, more often than not any species that is not the crop
species is considered a competitor as they are using finite growing resources that would
otherwise be available to the crop species. With specific regard to Douglas-fir
(Pseudotsuga menziesii (Mirb.) Franco) production in the Pacific...
The response of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) saplings to various levels of brush overtopping when growing on three north-facing sites in the Oregon Coast Range was investigated for two consecutive years. A fisheye (hemispherical) photographic technique combined with a digitizing computer system was used to determine the percentage of...
The objective of this research was to determine which
environmental resources, light, water, and nutrients,
control understory plant production and composition in a
Pinus ponderosa forest in northeastern Oregon. A split-plot
experimental design, with three blocks, four
treatments, and 44 plots, was established in the summer of
1985. Twenty plots...
The effect of nitrogen on influencing the competitive balance between a shrub, Artemisia tridentata ssp. wyolningensis (ARTRW) and a perennial grass Stipa
thurberiana (STTH) in a sagebrush steppe community was determined. Nitrogen levels were altered on 5x5 in plots by applying 4.5 gun2 of nitrogen in the form of ammonium...
This thesis examines the 8-year growth trend of
Douglas-fir (Pseudotsuga menziesii (mirb.)Franco), ponderosa
pine (Pinus ponderosa Dougl. ex laws.), and whiteleaf
manzanita (Arctostaphylos viscida Parry). Manzanita stands
ranging from 1700/ha to 27000/ha density were grown among
mixed conifers of the same age, which were planted in 1981
at 250x250 cm...
Southwest Oregon presents an environment of hot dry summers, cool moist winters, and rocky, shallow soils. The establishment of conifer plantations in this region presents challenging problems for initial seedling survival and subsequent growth. Three areas of concern include early conifer growth after seedling establishment, growth of competing hardwoods within...
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...
Weeping alkaligrass (Puccinellia distans) and Nuttall’s alkaligrass (Puccinellia
nuttalliana) infest Kentucky bluegrass seed fields of eastern Oregon. Weeping
alkaligrass is an introduced species from Eurasia, whereas Nuttall’s alkaligrass is
native to semi arid environments of western North America. These species are often
referred to collectively as ‘alkaligrass’; however, for farmers...
