A spatially explicit population model written in C++ programming language is used in
this study examining the population dynamics of the Desert Tortoise (Gopherus
agassizii) in the California Mojave Desert. The model is constructed with hexagonal
divisions of space, and with one-year increments of time. Four thematic maps: vegetation,
soil...
This study examined the question of whether a big island can be divided into many smaller
islands with the same pattern of area-species curve as that of the complete island. To address
this question, this study used data on the number and distribution of amphibians and
reptiles on Puerto Rico...
Many diverse applications have begun to study processes and patterns at a global
scale. To aid in this research, discrete global grid systems (DGGSs) are data models
which enable environmental modeling, monitoring and sampling across the earth at a
variety of spatial scales. A DGGS can be evaluated on a...
This thesis explores the genesis of the ecoregion concept,
examines the conceptual development of ecoregion classification
systems, investigates applications of ecoregion classification
systems for a broad range of purposes, and discusses the prospects
for the further evolution of this concept. An ecoregion is an area
that exhibits patterns of homogeneity...
Understory vegetation in artificially created tree canopy gaps in the Pacific
Northwest was studied to determine 1) variation in understory vegetation cover
between gap edges and gap centers, as well as between control and treatment plots,
2) spatial patterns of biomass and difference in biomass patterns among plots, 3)
individual...
More efficient methods are needed for the in-situ evaluation of mass transfer parameters which describe the movement of solutes through aquifer material. The objective of this study was to develop a method for estimating diffusion rate and capacity coefficients using a single-well, "push-pull" tracer test. The method consists of the...
Satellite image interpretation, geologic mapping, and paleoseismic trenching are used to investigate the Trans-Yamuna active fault system in the northwestern Doon Valley of the Indian Himalayan foothills. This east-west fault system is subparallel to and crosses the Main Boundary thrust near the structural transition from the Nahan salient to the...
The accurate simulation of snowpack deposition and ablation beneath forested areas is confounded by the fact that the vegetation canopy strongly affects the snow surface energy balance. The canopy alters the radiation balance of the snowcover, and reduces the wind speed at the snow surface. Data collected as part of...
The basement of the Tonga intraoceanic forearc comprises Eocene arc volcanic crust formed during the earliest phases of subduction. Volcanic rocks recovered from the forearc include boninites and arc tholeiites, apparently erupted into and upon older mid-oceanic ridge tholeiites. Rock assemblages suggest that the forearc basement is a likely analog...
The Oregon Department of Fish and Wildlife's (ODFW) Ecological Analysis
Center (EAC) is in the process of creating, from Landsat Thematic Mapper (TM)
imagery, a vegetation map of Oregon that will meet the latest standards set by the
National Gap Analysis Program. Since field verification is often expensive and by...
Stratigraphic measurement of the 1,238-rn thick Cowlitz Formation in the
southwest Washington type section along Olequa and Stillwater creeks reveals complex
facies succession of wave- to tide-dominated deltaic sequences. The underlying, 625-rn
thick upper member of the McIntosh Formation (as mapped by Wells, 1981) is composed
of two units: a...
The Whittier fault forms the central part of a fault system extending
from the East Montebello fault at Whittier Narrows to the Elsinore fault,
which is traced as far as the Mexican border. The Whittier fault forms a
restraining bend in this fault system, resulting in uplift of the Puente...
Modern environmental monitoring and modeling requires a good global
grid system for survey sampling and accurate, spatially complete data
collection of relevant environmental phenomena. A prime requirement for the
global grid system is that the global sampling grids be regular and equal in area
and have minimal shape distortion. None...
Pre-flood (1995), and post-flood (1996) channel stability surveys were conducted on 22 reaches along Oak Creek, Benton County, Oregon in an effort to note if the flood of February 1996 altered the channel and if the channel stability survey that was being used accurately predicted the channels resistance to change...
This study addressed the effects of hilislope and fiuvial processes on spatial
patterns of stream bed particle size at the watershed, reach and within-reach scales.
The study was conducted in Lookout Creek watershed, a fifth-order, 64 km2 basin in
the Western Cascades mountains of Oregon. Stream bed particle size was...
The Queen Charlotte Fault system is a segment of the North America - Pacific
plate boundary. From 45 Ma - 5 Ma, plate motion has been primarily translational.
Since 5 Ma, transpression has been the dominant mode of interaction. The plate
boundary west of the Queen Charlotte Islands is characterized...
Although there has been extensive research on the geomorphic and ecologic role of
large woody debris (LWD) in streams, the dynamics of LWD in streams are poorly
known due to various measurement difficulties during floods. In this thesis I present the
results of two flume experiments on the dynamics of...
Since 1979, over $114 million of natural gas has been produced at the Mist Gas Field, currently the only commercial gas field in the Pacific Northwest. In the Mist Gas Field, the sandstone-dominated Clark and Wilson member of the upper Eocene Cowlitz
Formation is the reservoir and the overlying upper...
River regulation imposes changes in the supply of sediment and the frequency of competent flows. As a result, impounded rivers often exhibit downstream changes in channel processes, particle size, and morphology. The magnitude of change in competent flow frequency and sediment load together can be used to predict the pattern...
Magnetic and gravity modelling was completed along two E-W transects offshore central Oregon. These models indicate that the backstop-forming western edge of the Siletz terrane has a seaward dip of approximately 40° to 49° at 44°48'N, shallowing to ~28° at 44°1 1 'N. This is a well-determined result, given available...
The John Day Reservoir, a large reservoir between the John Day and the McNary Dams on the Columbia River, must be lowered several feet below design level during salmon migration season in order to preserve anadromous fish habitat. This research assessed the north shore of the John Day Reservoir for...
This thesis presents elastic finite difference simulations of two dimensional wavefield propagation for line-9, recorded during the 1993 part of the multi-institutional, multi-year Mendocino Triple Junction (MTJ) Seismic Experiment. Line-9 is a high-resolution, large-aperture seismic profile oriented in north-south direction, extending from the subduction regime north of the MTJ to...
Surface-geology, oil-well, seismic-reflection, and magnetostratigraphic data are
integrated to evaluate structural style and shortening rate at the Himalayan front (Sub-Himalaya) of northwest India. The Sub-Himalaya, between the Main Boundary thrust
and the Himalayan Frontal fault, is the actively deforming front of the Himalaya. At
certain locations, the Himalayan Frontal fault...
Lower and Middle Devonian strata crop out on the former
stable carbonate platform that existed in the Quinn Canyon Range,
through the carbonate shelf edge in the Pancake Range, to the
carbonate slope and outer-shelf basin in the Reveille Range.
The strata of the Reveille Range record a transition from...
The northwest-trending Neogene Tualatin basin in northwestern Oregon is a pull-apart
basin with approximately 750 m of post-middle Miocene structural relief. Gently
tilted uplands capped by Columbia River Basalt Group surround the synclinal basin on all
sides. Integrated gravity, aeromagnetic, and seismic reflection data indicated that the
basin is underlain...
Models that assess the risk to biodiversity from landscape change can help
communities prioritize planning decisions. Accurate representation of the ecology and
life history traits of species is necessary. This study introduces the use of habitat
quality in a biodiversity risk model to determine the significance of habitat quality when...
The purpose of this study was to: (1) evaluate land
use and vegetation history of the Willamette Floodplain
Research Natural Area; (2) characterize present day
vegetation; (3) evaluate the relation of vegetation to
environment, and (4) establish a baseline dataset for future
trend analysis in order that response of different...
A change to a warmer, drier climate beginning as early as 1900 was responsible
for triggering a dramatic, rapid retreat of Collier Glacier, Oregon, between 1924 and
1940. Although there was a dramatic decrease in precipitation contemporaneous with this observed "step-function" response of mass loss, it is unclear if climate...
Three-dimensional gravity analysis is the process of removing the predictable
components from the free-air gravity anomalies and has proven to be useful for
interpreting the subsurface structures and active processes at mid-ocean ridges. The
three-dimensional effects of the seafloor and Moho topography, assuming a constant
crustal thickness and constant crust...
Sediment production and delivery in Pacific Northwest
coastal streams can have damaging effects on channel
morphology and anadromous fish habitat. The research in
Pistol River was designed to determine if a link exists
between sediment delivery processes and degradation of fish
habitat. Objectives of this basin-wide analysis were to:
1)...
Detailed subsurface structure contour maps and cross sections have shown the
northern Los Angeles basin to be underlain by a south facing monocline that is
complicated by secondary faults and folds. The monocline forms a structural shelf that
marks the northern boundary of the Los Angeles central trough. The monocline...
The northern Los Angeles basin is influenced by two structural styles: the west-trending compressional Transverse Ranges to the north, and the strike-slip Peninsular Ranges to the south. The interaction of these two structural styles has resulted in a complex fold fault belt at the northern margin of the Los Angeles...
The Juniper Ridge volcanic complex is located in the High Lava Plains Province of
southeastern Oregon, a wide zone of bimodal volcanism and faulting that marks the northern
limit of widespread Basin and Range-style faulting in the northern Great Basin Province. Rhyolite
dome complexes are progressively younger to the northwest...
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...
Geographic Information Systems (GIS) is a burgeoning
field with its roots in geography. It is increasingly
being used by a large variety of disciplines, including
land use planning, as a decision support tool to help solve
complex spatial problems. At Oregon State University,
researchers have developed an analog model which...