Shallow, rapid soil mass movements are common events and primary sources
of sediment in steep terrain of the Pacific Northwest.
Poorly vegetated debris deposits and scars resulting from landslides
remove land from the productive timber base, and are subject to
continuing erosion. To examine the impact of these events on...
The volcanic (~45-10 Ma) and plutonic rocks (~37-12 Ma) comprising the Western Cascades extend from northernmost California to southern British Columbia and are ancestral to modern arc magmatism. The ancestral arc hosts a series of small plutons that are locally associated with porphyry (Cu-Mo) and epithermal (Au) ore deposits. Three...
Pseudotsuga menziesii dominates the forests of the Pacific Northwest.
But though it is dominat, Tsuaa heteroohylla or Abies amabilis
is usually climax. Many researchers have studied Pseudotsuga on the
widespread mesic sites where it is seral, but few have examined the
relatively rare ecosystems in which Pseudotsuga or its associate...
Despite the recognized role of soil arthropod fauna on nutrient cycling
and decomposition processes, many aspects of the effects of sylvicultural
methods in forest ecosystems upon their biology remain poorly understood.
The long term effects of prescribed fires on soil arthropods in forest
ecosystems in the Pacific Northwest have never...
In the Oregon Cascade Range, conifer encroachment has reduced the extent of mountain meadows by as much as 50% since the mid-1940s. Although encroachment results in a general decline of meadow species abundance and diversity, species differ in their sensitivities to encroachment: some show rapid declines whereas others persist in...
As a result of a warming climate, subsequent declining snowpack, and a century of fire suppression, forest fires are increasing across the western United States. However, we still do not fully understand how forest fire effects snowpack energy balance, nor the volume and availability of snow melt and associated water...
Rainfall interception is a primary control over the moisture input to a forested ecosystem through the partitioning of precipitation into throughfall, stemflow, and an evaporated component (i.e. the interception loss). Rainfall interception is a spatially and temporally varying process at multiple scales, but heterogeneity in interception processes are poorly understood...
Knowledge of stand structure, stand dynamics, and production ecology of species mixtures lags well behind that of single-species, even-aged stands. Two mixed-species spacing trials in central Oregon allowed investigation of mixed-species dynamics in a controlled experimental setting. The first site, Pringle Butte, is a mixture of ponderosa pine (Pinus ponderosa...
Montane forest vegetation as it occurs on the east flank of the
central Oregon Cascades has provided excellent conditions for a
"natural experiment" in the use of various methodologies in studying
vegetational distribution. This "experiment" has reflected on some
theory and practice for the discipline of plant synecology. Detailed
descriptions,...
The morphology and ecological importance of habitats associated with the margin of third-order stream channels in the Oregon Cascades were studied in streams in three different riparian types: 450-year-old conifers, 40-year-old alder, and an open, herbaceous-dominated clearcut. Margins, backwaters, and side channels in streams create important habitat for fry of...
National Forest management in the Pacific Northwest is shifting
from a focus on commodity production to ecosystem management, in which
the health of the entire forest ecosystem is considered, rather than that
of a few key species. Ecosystem management includes retention of some
live trees following timber harvest (green-tree retention)...
Despite the importance of rain and snowmelt in causing peakflows in the Pacific
Northwest, the interactive effects of a snowpack and watershed physiography on
streamflow are largely undocumented. This study investigated the influence of soil and
snowpack moisture on peakflow hydrograph shape in three small (< 60 ha) control sub-watersheds...
Study objectives were to survey and compare physical and chemical characteristics of soils within two thirdorder montane riparian ecosystems: a 500-year old Douglas fir (Pseudotsuga menzlesii) forest at Mack Creek, and a mature red alder (Alnus rubra) forest occupying a 35-year old clearcut at Quartz Creek, both near Blue River,...
Experimental prescriptions compare agroforestry systems designed to increase financial returns from high-elevation stands in the southern Oregon Cascade Range. The prescriptions emphasize alternative approaches for joint production of North American matsutake mushrooms (also known as North American pine mushrooms; Tricholoma magnivelare) and high-quality timber. Other agroforestry byproducts from the system...
Twenty sites of uniform topography and soil were select ed in the
montane forest found on the East flank of the Central Oregon Cascades.
These sites were located along a vegetational gradient composed of
five plant communities: Abies/Pachistima, Pinus/Ceanothus, Pinus
Arctostaphylos-Purshia, Pinus/Purshia/Festuca, and Juniperus
Festuca. An attempt was made to...
Soils representative of several landscape units in the H. J.
Andrews Experimental Forest, Western Cascade Range, were sampled,
analyzed, and tentatively classified. Genetic inferences were
drawn relating soils to landscape position and other factors of soil
formation. Descriptive information and nutrient capital data were
provided to support ecosystem modelling efforts...
This thesis includes four separate studies. The first two studies assessed edge effects in a
700-year-old forest. After 20 years of exposure, epiphyte assemblages on the clearcut edge
were similar to those of the forest interior, but there were some differences in vertical
distribution patterns. Several species restricted to the...
Measuring habitat selection by bats is complicated by their intricate life cycle. Scaling habitat measurements to reflect a hierarchal habitat selection process can help to define habitat associations of bats. I assessed day roost habitat of female long-legged myotis at four scales: the roost structure, micro-habitat surrounding the roost, the...
Distribution and juvenile habitat use of bull trout (Salvelinus
confluentus) were surveyed in selected areas of the Upper Willamette,
Deschutes, upper Yakima, and upper Cedar River basins in Oregon and
Washington from 1989 to 1991, using day snorkeling, night snorkeling,
and electrofishing. These methods were selected after a preliminary
diel...
Nutrient and particulate matter balances were established for five ecosystems dominated by Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] in the western Cascades, Oregon. Carriers of N and P were particulate matter (dust in precipitation and sediment in streams) and dissolved matter in both precipitation and stream water. The input and outflow...
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...
We used radio-telemetry techniques to estimate home range size, movements, den sites, and habitat selection of 39 northern flying squirrels (Glaucomys sabrinus) in 2 old- and 2 second-growth stands in the central Oregon Cascades. Sampling periods were at night during summer and fall of 1991-92. Home ranges were smaller for...
Denitrification, the biological or chemical reduction of ionic nitrogen oxide or dinitrogen, has not been widely studied in forest ecosystems despite widespread interest in other facets of the forest nitrogen economy. This study had three main objectives: to determine whether potential for denitrification exists in forest riparian and hill slope...
Montane meadows comprise less than 5% of the landscape of the western Cascades of Oregon, but they provide habitat for diverse species of plants and pollinators. Little is known about plant-pollinator network structure at these sites. This study quantified plant-pollinator interactions over the summer of 2011, based on six observations...
Forest soils contain a substantial portion of global terrestrial carbon stores. Forest management can influence the soil carbon pool and how soil organic matter functions. The long-term productivity of forests is an ongoing goal where land managers utilize biomass and timber. A site-specific understanding of intensively managed forests can ensure...
This thesis examines factors limiting understory herb presence and flowering in young second-growth Douglas-fir (Pseudotsuga menziesii) forests on the west side of the Cascade Mountains, Oregon, USA. I studied the belowground effects of canopy trees on understory herbs and shrubs in old-growth forests using trenched plots from which tree roots...
Gravity measurements made during 1979 and 1980, combined with
existing gravity measurements, provide data for the interpretation
of upper crustal structures relevant to the assessment of the geothermal
potential of south-central Oregon.
West of Upper Klamath Lake, free-air gravity anomalies trend
north-south and average near 35 mgals. East of Upper...
Defensive chemical and nutritive quality of young leaves were measured for 72 individual trees of Chrysolepis [Castanopsis] chrysophylla in conjunction with light intensities of two different stand types and population numbers of Habrodais grunus herri in the Cascade mountains of Oregon. Leaves were collected in the spring and leaf characteristics...
Montane meadows comprise a small area of the predominantly forested landscape
of the Oregon Cascade Range. Tree encroachment in the last century in these areas has
threatened a loss of biodiversity and habitat. Climate change in the coming century may
accelerate tree encroachment into meadows, and exacerbate biodiversity loss. Multiple...
Analysis of import trade since 1976 shows that forests of the Pacific Northwest provide
Japan with the largest share of pine mushrooms (Tricholoma spp.) outside of East Asia.
To determine whether North American pine mushrooms (Tricholoma magnivelare (Peck)
Redhead) merit more intensive management in the southern Cascade Range, a major...
I compared transpiration among different types of forest stands in the western Cascades of Oregon. The three major questions were: 1) How does transpiration compare between a young and old stand and why? 2) Does diversity of overstory trees affect transpiration? and 3) How is transpiration related to stream flow?...
Reforestation-based restoration of severely burnt plantations is one of the primary management activities following wildfire on U.S. federal lands. Restoration effects on early-seral plant and cryptogam communities have not been documented. The objectives of this study were, in severely burnt plantations two to four years post-fire, to examine the: (1)...
The seasonal duration of snow cover is a primary factor influencing the patterns of vegetation in high subalpine and alpine environments, but little is known concerning the responses of plant reproduction and
seedling recruitment to gradients of snow-release. Vegetation patterns of a high subalpine site in the Oregon High Cascades...
This study evaluated the effect of soil compaction on the growth
of natural regeneration on volcanic ash-influenced soils in the
southern Washington Cascades. Growth of 9 to 18 year-old sapling-.
sized Ponderosa pine (Pinus ponderosa Laws.) was studied on sites
ranging from 915 to 1006 m elevation in an area...
The Central Western Cascades and southeast Zaire were selected to test the distance decay and deforestation models on forest environments. Distance gradients included away from cities, and away from highways/roads. Two forest definitions were used in each study site. The "extended-forest" definition included areas with at least 30 percent canopy...
I studied nest-site characteristics and habitat relationships for three species ofprimary cavity-nesting birds--hairy woodpecker (Picoides villosus), northern flicker (Colaptes auratus), and red-breasted sapsucker (Sphyrapicus ruber)-- over spatially heterogeneous landscapes in managed forests of the Southern Oregon Cascades during 1995 and 1996. The study was conducted on the Diamond Lake Ranger...
The objectives of this thesis were to examine the links between soil microbial community composition and function using the nitrogen (N) cycle as a model for these interactions and to assess the impact of environmental factors such as microclimate, vegetation type, and nutrient availability on microbial diversity and N transformations...
The abundance and spatial heterogeneity of coarse woody debris (CWD) on the forest floor is a prominent feature of Pacific Northwest (PNW) forest ecosystems. The effect of CWD on soil solution chemistry, nutrient cycling and availability, soil physical structure and formation of soil organic matter, however, remains unknown. Therefore, studies...
This study assessed how logging-access roads may have contributed to
observed historical increases in peak discharges associated with small and large
logged basins in the western Cascades of Oregon. The study was conducted on
the Lookout Creek (62km²) and the upper Blue River (118km²) basins. Potential
road effects on hydrology...
In this study, biological and chemical characteristics were determined for two high-elevation meadow-to-forest transitions located in the Central Oregon Cascades. The chloroform fumigation incubation method (CFIM) was used to determine microbial biomass C(MBC) and the N flush due to fumigation (NF), and meadow values were compared to forest values for...