Ages, diameter growth, density, tree size, and species were studied in old-growth,
plantation, and young natural Douglas-fir stands in three areas in western
Oregon: the western and eastern Coast Range and the western Cascades. The
purpose was to compare the development of these three stand types and to
The Three Sisters region of the Oregon High Cascades has developed three compositionally
and petrogenetically distinct silicic (i.e., SiO₂ ≥ 58%) magma systems within the last 600 k.y. These
silicic systems evolved from the same High Cascade mafic magma system and developed in the same
20x30 km area of the...
Western juniper (Juniperus occidentalis) encroachment has been associated with
increased soil loss and reduced infiltration resulting in the loss of native herbaceous plant
communities and the bird and animal species that rely on them. Hydrologically,
however, change in water yield has been linked with the amount of annual precipitation a...
The Willamette Silt is a surficial geologic unit composed of successive Missoula Flood Deposits that underlies 3100 km2 (1200 mil) of arable land in the Willamette Valley of Oregon. The Willamette Silt protects the underlying regionally important Willamette
Aquifer from agricultural contamination while acting as a semi-confining unit and a...
Active habitat management plays a key role in the preservation of native ecosystems
and rare species, especially in the Willamette Valley of Oregon, where natural
succession to woodlands threatens the few wetland prairies remaining after 150 years
of agriculture and urbanization. Sidalcea nelsoniana, listed as threatened under the
A variety of soil properties have been proposed and tested as potential
indicators of soil quality. This study was conducted in an effort to produce a
standardized soil quality index for systems in Oregon. Soils in both forested and
agricultural systems were sampled in a wide variety of locations, climates,...
Barley Yellow Dwarf Virus (BYDV) is a major disease of wheat. Unfortunately, unlike barley where the Yd2 gene provides adequate levels of resistance, the situation in wheat is more complex. This study was designed to provide information regarding: 1) evaluation of methods of measuring resistance among selected cultivars; 2) identification...
The effects of burial by tephra (volcanic aerial ejecta) on
forest understory plants were examined northeast of Mount St. Helens,
Washington, in the area where the 18 May 1980 eruption deposited
tephra but did not destroy canopy trees. At six sites along a tephra
depth gradient from 2-15 cm, understory...
Conventional soil maps represent a valuable source of information about soil
characteristics, however they are subjective, very expensive, and time-consuming to
prepare. Also, they do not include explicit information about the conceptual mental
model used in developing them nor information about their accuracy, in addition to the
error associated with...