Large woody debris recruitment to streams from adjacent riparian forests influences stream
channel morphology, sediment routing, and fish habitat. A mathematical model was developed
to 1) determine whether the trees in a stand adjacent to a stream, upon falling, would provide
large woody debris of a specified size to the...
CONIFER simulates water, carbon, and energy dynamics of a coniferous forest. The model consists of 29 nonlinear difference equations. Measured driving variables include air temperature, dew point temperature, precipitation, solar radiation, and wind speed. Water and energy variables are updated
daily; carbon variables are updated weekly. This report contains a...
CONIFER simulates water, carbon, and energy dynamics of a coniferous forest. The model consists of 29 nonlinear difference equations. Driving variables include air temperature, dew point temperature, precipitation, solar radiation, and wind speed. Water and energy variables are updated daily; carbon variables are updated weekly. This report contains a detailed...
Many studies have shown that net primary production in old-growth Douglas-fir/western hemlock forests is lower than in younger forests in similar sites, although the cause is still not clear. One possibility is that overall carbon assimilation, or GPP, is lower in older forests. However, it is difficult to measure GPP...
The natural fall of trees in riparian areas is an important source of coarse woody debris for mountain streams, improving fish habitat and influencing stream morphology. Existing models consider the probability of coarse woody debris entering a stream channel based upon trees having a random direction of fall without consideration...
"We have developed graphical and logical models for explaining the production of a consumer on the basis of the capacity of an ecosystem to produce that consumer (the productivity of the system for that consumer), on the basis of the biomass of the consumer, and on the basis of the...
The simulation model described below is based on the assumption that the periphyton community can be treated as a unit, without a quantitative concern for the dynamics of
its many constituent populations. The function statements and parameter
estimates incorporated into the model are based on experimental work with laboratory streams...
The aquatic modeling group, consisting of Davis, Donaldson, Hall, Higley, Lyford, McIntire, Mullooly, Overton, Strand, Waring, and Warren, met in four 2-hour sessions from July 7 to July 26. The charge to the group was: 1. Define an appropriate internal structure for the aquatic subsystem; 2. Define significant couplings between...
This paper presents a framework for analyzing efficient spatial allocation of forest
management efforts - fuel treatment and harvest - under the risk of fire. The framework
integrates a fire behavior model and a spatially-explicit stochastic dynamic optimization
model. I investigate the effects of spatial interaction across plots during forest...
The problem of determining an optimal sequence of decisions in
even-aged stand management is analyzed and solved with an alternative to
the traditional dynamic programming network. The new method is derived
independently from two different approaches to the problem: Network
optimization and generalized LaGrange multipliers. Both derivations are
presented. It...
A complex and sometimes serious problem facing modern day forest
managers is that of estimating and analyzing potential on-site impacts
which result from forest activities. A major type of adverse impact
is man-Initiated forest erosion. This consequence can be substantially
magnified when forest harvest and road activities are implemented in...
An hierarchically structured resource flow competition model
for two species is developed. The model is shown to be
intrinsically neutrally stable with a dynamical behavior
derived from perturbation responses. The model properties
are contrasted with those of a conventionally interpreted
Lotka-Volterra competition model.
A simulation developed from the model is...
There has been an increased interest in the
quantification of pattern in ecological systems over the past
years. This interest is motivated by the desire to construct
valid models which extend across many scales. Spatial methods
must quantify pattern, discriminate types of pattern, and
relate hierarchical phenomena across scales. Wavelet...
Calow (1983) realized that differences between parasites and their free-living
relatives can be explained by the differences in nutrient richness. I
propose a model that is based on Calow's idea which identifies the relative
position of different trophic strategies (e.g. predation, grazing, parasitism and
others) based on (1) the differences...
The relationships between inorganic nutrient supply and the first two trophic levels have long been understood in a very approximate manner but the dynamics of such a system cannot be explored adequately by simple
arithmetic when nonlinear relationships exist. An exploration of such a
system was accomplished by the use...
In the Coniferous Forest Biome, many of the understory as well as
dominant plants are evergreen and thus water uptake is a year around
process. The flow of water from the soil through plants to the atmosphere
affects the entire forest ecosystem. As water is evaporated, it absorbs
heat and...
There is considerable uncertainty associated with stand
establishment in coastal Oregon. Several species can gain
control of the site depending on stand conditions as well as
management practices. In this study, three cover type
transition models were developed using data from the Siuslaw
National Forest to predict stand establishment patterns...
Quantitative habitat models of wildlife-habitat relationships are developed to
formalize our current understanding about an ecological system. A habitat
association model is one of these models that is useful for answering questions
about how the habitat is occupied, how much growth habitat is required by the
animal, or how the...
Low-temperature hydrothermal activity in Iceland is
apparently mostly controlled by dikes and fractures.
Conventional methods of production data analysis are not
readily applicable in cases of heterogeneous/anisotropic
fracture dominated hydrothermal systems. Moreover, the
dikes and fractures may control the heat uptake mechanism
of low-temperature activity.
The free-surface response functions of...
This thesis is a collection of four submitted manuscripts that present
methods to assist forest ecosystem service managers wanting to develop
operational sampling, monitoring, and production plans for a set of
specific quantifiable ecosystem services, which are formulated as a
series of general multi-objective optimization problems. The problems
are solved...
The study presents two main parts: first, a review
of tropical silviculture and forest management systems
and, second, the investigation of a growth and yield
model which has some potential for application in the
tropical region. The presentation of tropical
silviculture includes: (1) an overview of the biological
characteristics of...
This work describes the modeling framework and initial results for CLAWS (Coupled
Landscape And Water System), a physically-based, spatially-distributed hydrologicgeomorphic model that has been coupled with a vegetation dynamics simulation. Spatial variability of topography, soil, vegetation, and climate drive a hydrology module that calculates the water budget at given time...
Quantifying and modeling processes involved in the global carbon cycle is important to evaluate the temporal and spatial variability of these processes and understand the effect of this variability on future response to changing climate and land use patterns. Biomass accumulation and Net Primary Productivity (NPP) are large components of...
An analytical algorithm to formulate a sparser set of adjacency constraints than the conventional algorithm is proposed. Utilizing matrix algebra applied to an adjacency matrix, constraints are systematically and efficiently derived by the proposed algorithm. The proposed algorithm is proved to provide a true set of adjacency constraints in the...
As part of the effort to evaluate TRIM (Timber Resource Inventory
Model) for the next RPA National Assessment, a study was conducted
using natural pine stands in North Carolina. TRIM has been used for
regional timber supply studies in both the Pacific Northwest and the
South (Southern Timber Supply Study)....
Salmon survival and eventual recruitment success have long been thought to be determined within the first summer following ocean migration. Juvenile growth during this period is largely influenced by ocean conditions such as temperature, prey availability, abundance, and quality. Shifts in these conditions due to climatic perturbations are particularly prevalent...
We present a new nitrogen isotope model incorporated into the three-dimensional ocean component of a global Earth System Climate Model designed for millennial timescale simulations. The model includes prognostic tracers for the stable nitrogen isotopes, ¹⁴N and ¹⁵N, in the nitrate (NO₃ˉ), phytoplankton, zooplankton, and detritus variables of the marine...
The effects of harvesting Pacific hake (Merluccius productus)
were examined with a multi-species numerical model composed of
seven logistic growth equations coupled by a food web. The
food web was composed of: California sea lions (Zalophus
californianus), hake, sablefish (Anaplopoma fimbria), spiny
dogfish (Squalus acanthias), a generic rockfish species
(Sebastes...
The issue of global climate change and an increasing interest in the reduction of fossil fuel carbon dioxide emissions by using forest biomass for energy production has increased the importance of quantifying forest biomass in recent years. The official U.S. forest carbon reporting is based on the forest biomass estimates...
Descriptions of the fire regime in the Douglas-fir/western hemlock region of the Pacific Northwest traditionally have emphasized infrequent, predominantly stand-replacement fires and an associated linear pathway of stand development, where all stands proceed along a common pathway until reset by the next fire. Although such a description may apply in...
The following report Introduces a documentation scheme for flow
oriented ecosystem models and shows its application to a carbon-water
model developed within the coniferous biome. This documentation scheme
has remained operative through revision of this model and expansion of
It to include nutrient flows. This model and subsequent versions are...
Equations for predicting the probability of a tree's dying in the
next 5 years are presented for eight conifer and eight hardwood
tree species from southwest Oregon. A logistic equation form was
used to characterize the probability of mortality. The parameters
of the equation were estimated using weighted, maximum likelihood...
Although no formal project in mineral cycling was defined for 1972, three modeling efforts were begun: calcium cycling at Cedar River, litter decomposition, and miombo ecosystem. The calcium cycling model is a simple compartment model and was developed as a practice exercise. It demonstrates the inadequacy of linear-donor control formulation...
Seasonal trends in forage production and environmental parameters
for five plant community types within a northeastern Oregon riparian zone
were described and modeled using correlation and path analysis. Wet
meadows produced the greatest amount of herbage biomass, followed by moist
bluegrass meadows, gravel bars, forests and dry bluegrass meadows. Trends...
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 Timber Resource Analysis System (TRAS) was the
timber supply projection model used in conjunction with
the Timber Assessment Market Model (TAMM) to predict
future U.S. softwood timber harvests, inventories and
product prices in the 1980 RPA Timber Assessment conducted
by the USDA Forest Service. Several criticisms of the
TRAS...
Volume I: TREES (Timber Resource Economic Estimation System), a forest management and harvest scheduling model, is comprehensively described in the first of a four-volume series. Even- or uneven-aged forest inventories form basic resource units (BRUs), entered by age class or size and diameter classes; stocking level; and management intensity. Management...
A model is developed to simulate basal area growth and mortality for forest stands using individual trees as the basic units. Yearly diameter increment, probability of death, and height-diameter relationship are computed
from a competition measure which is based on crown overlap. This model is used to simulate the growth...
The conceptual framework of an erosion model has been designed to link processes of mass wasting, surface erosion, and channel storage and transport. A program to stimulate mass wasting will be based on a variation of the factor of safety approach which balances forces tending to drive mass movement against...
Equations for predicting diameter growth are an essential component of single-tree growth and yield models (Munro 1974). Diameter
growth predictions are used to characterize individual-tree development and to project the growth of stand basal area and volume. Both diameter growth and basal area growth have been used as the dependent...
Equations for predicting individual-tree height growth per 5-year period are presented for Douglas-fir, white fir, grand fir, ponderosa pine, sugar pine, and incense-cedar growing in the mixed-conifer zone of southwest Oregon. The data used to develop the equations came from 3,648 trees sampled from 391 stands in the study area....
Equations for predicting the 5-yr diameter-growth rate of a tree are presented for eight conifer and nine hardwood tree species from southwest Oregon. Equation parameters for undamaged and damaged trees combined were estimated by weighted nonlinear regression. The resulting equation for Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] explained more than 71%...
Equations for predicting height to crown base are presented for tree species from southwest Oregon. Equations for undamaged and damaged trees were estimated with weighted nonlinear regression techniques. The effects of specific damaging agents on the height to crown base were explored, and damage correction factors were estimated. The damage...
A steady-state model designed especially for analysis of gas exchange studies of terrestrial net photosynthesis is discussed. The model expresses net photosynthesis as a function of light, temperature, CO₂ concentration, stomatal resistance, and other factors. The parameters of the model are
estimated from data by nonlinear least-squares. The data set...
The main objective of this study was to offer an alternative methodology for
forest sector modeling in developing economies. To this effect, a policy preference
function was developed and estimated using data from the forest sector of the Cote
d'Ivoire.
The justification for this alternative framework for forest sector analysis...
A model was developed for analysis of the soil water balance of
individual reforestation sites in western Oregon. The numerical
procedure for this model was programmed in compiled BASIC language and
calculations for an entire season are made in about 180 seconds on an
IBM AT microcomputer.
The processes that...
Remote sensing technologies have proven useful and cost-efficient for quantifying various forest vegetation characteristics over multiple scales. However, significant limitations were encountered in each of two related experiments conducted to explore their potential to supplement or replace traditional, single-species biomass equations for estimation of ground vegetation and tree overstory on...
This paper describes methods that can be used to
evaluate stand and tree growth response to a single
application of fertilization and/or thinning with data
collected from multiple installations. Two kinds of
methods were proposed: (1) structure analysis which
applies covariance analysis in a blocked design with and
without sampling...
The algorithm RLS-PLUS was developed to yield solutions to the
multivariate control problem of diameter and species optimization for mixed conifer
and hardwood stands. The problem is specified with twenty-five state variables
consisting of five species groups with four merchantable diameter classes and one
unmerchantable class. This gives twenty diameter...
This study aims to compare different methods of obtaining maximum growing season leaf area index (LAI) maps using remote sensing data, LAI and tree cover field data in a boreal forest near Thompson, Manitoba, Canada. The comparison includes aspatial methods such as traditional regression, inverse regression and reduced major axis,...
Equations for predicting the 5-yr height growth rate of a tree are presented for six conifer species from southwest Oregon. Equations for the combination of undamaged and damaged trees were estimated with weighted nonlinear regression techniques. These equations are being incorporated into the new southwest Oregon version of ORGANON, a...
Strip thinning is recognized as a way of commercial thinning
young-growth stands. strip thinning has been used worldwide. The
purpose of this study was to explicitly evaluate the costs and benefits
associated with skyline strip thinning in young Douglas-fir
(Pseudotuqo menzesii Franco) stands in the Pacific Northwest and to
compare...
Malheur County is located in the southeast corner of Oregon and consists of about 64 million acres of which 260,000 acres is irrigated. Groundwater contamination has been found in a 115,000 acre area in Northeastern Malheur County. The main source of the groundwater contamination is agricultural practices. The overall objective...
The focusing of public attention on the practices of forest managers has resulted
in the need for new tools to help explain the results of these practices. The traditional
tools of tables and graphs of numerical values require a significant investment in
learning the forestry profession. Once the investment is...
Harvest scheduling and stand level optimization have
generally been regarded as separable problems. Some
studies have attempted to jointly optimize a wide range of stand treatments and a forest wide harvest schedule using combinations of mathematical programming techniques. The mathematical programming forest level techniques presume perfect information on production, costs...
Using existing permanent research plot data, we developed equations for predicting height-to-crown-base (HCB), 5-yr diametergrowth rate (delta D), 5-yr height-growth rate (delta H), 5-yr mortality rate (PM), and the maximum size-density trajectory for Douglasfir and western hemlock in the coastal region of the Pacific Northwest. With the exception of the...
The Elliott State Forest, located in the Coast Range of Oregon, is currently revising their Habitat Conservation Plan (HCP). Many of the constraints in the HCP are spatial, requiring identification of specific parcels in order to limit activity along habitat reserves, limit harvest opening size, and to coordinate activities within...
Conclusion: The first part of this note deals with problems of propagation of error and the latter part with questions commonly identified as "model validation" questions. It is concluded that all validation questions can be resolved into two parts: (1) strategic aspects, involving logical and inferential structures and (2) tactical...
Equations for predicting height from diameter outside bark at breast height (DBH) were generated for 24 tree species in western Oregon. The equations were based on the asymptotic Chapman-Richards function. Because geographic location and site productivity may influence height-diameter relationships, height-diameter measures from 8727 plots were first grouped by site...
This dissertation is a collection of three manuscripts that serve to fill the knowledge gaps and advance methods of detecting the effects of contemporary forest harvesting in experimental catchment studies. While there is a preponderance of studies evaluating the environmental effects of forest harvesting in the western United States, few...
Maintaining the sustainability of the earth’s ecosystems has attracted much attention as these ecosystems are facing more and more pressure from human activities. Machine learning can play an important role in promoting sustainability as a large amount of data is being collected from ecosystems. There are at least three important...
Marine systems undergo changes in community composition over time as a result of a variety of environmental and anthropogenic factors. Understanding these community changes and the factors that drive them is critical for ecosystem management of marine resources. The Gulf of Alaska (GOA) is a large marine ecosystem that includes...
Forest growth models in the Pacific Northwest are predominantly empirical. Predictions of yield under alternative silvicultural regimes cannot rely completely on field trials; yet empirical growth models are often inadequate for extrapolating untested regimes and genotypes. The limitations of current models include (1) long time-steps (e.g. 5-10 years); (2) insufficient...
A litter decomposition model was developed as part of :a watershed modeling effort. This model simulates weekly dry weight changes In woody and nonwoody litter (01), incorporated litter layer (02), and soil organic matter. Processes simulated by the model include: litterfall by component, root turnover, respiration, decomposition, and organic matter...
Many miles of roads are built in the Pacific Northwest Forests to provide access for logging and fire protection. Logging roads often cross steep mountainous terrain. Logging roads and the associated cut and fill slopes represent a discontinuity in the natural stress state in the soil mantle. These conditions result...
The objectives of this study were to ascertain the relative precision and accuracy of certain estimators on several forest populations and to determine if relative performance could be predicted from knowledge of population characteristics. Performance was tested on three populations of trees drawn from stands in northern Ontario. The first...
This thesis investigated the contribution of the forest to neighboring property
prices and explored the possible impacts from different neighboring forest characteristics
with the hedonic property price model.
The quadratic Box-Cox model was applied to choose the proper functional form.
The square root model was chosen to be the interpretable...
A study of the phosphorus dynamics in castle Lake, California, is presented.
The approach is (1) to identify the important phosphorus parameters,
(2) to develop and apply methods measuring the parameters in the
field and (3) to develop a computer model of the phosphorus cycle. This
model will be used...
The objective of this study is to develop a mathematical model to relate the production of juvenile sockeye salmon in the Wood River
Lake system to parent stock size, primary and secondary production, population size of predators and competitors, and abiotic variables.
Data collected from the Fern Lake watershed between 1958 and 1971 include measurements of the rate of flow of water into the lake through a single inlet stream. The objective of the work presented here is to
develop a model of this flow using the climatological data available from the...
Disaggregative and individual-tree/distance-independent modeling methods are
compared and contrasted. Differences between the two are related to differences in functional
and apparent resolution and may be illustrated using aggregation theory. When considering
models of different levels of resolution describing a given phenomenon, invariance with respect
to the aggregation implied (symmetry) may...
Contract harvest operations have become the preferred approach to reducing the largest cost component of timber production through free market competition amongst logging contractors bidding or negotiating for work. The goal of this research was to investigate economic components of harvesting operations not previously studied for steep slope thinning harvests...
Like other species interactions in ecological systems, host-pathogen interactions are influenced by environmental factors, landscape characteristics and the broader community context. My thesis explores the potential influences of food-web interactions (Chapter 2), climate change (Chapter 3), landscape structure and host movement patterns (Chapter 4), and the combined influences of local...
Developing accurate predictive distribution models requires adequately representing relevant spatial and temporal scales, as these scales are ultimately reflective of the relationships between distributions and influential environmental conditions. In this research, we considered both spatial and temporal scale and the influence each has on predicting broad-scale distributions of two disparate...
To facilitate policy making and improve understanding of issues facing the New Zealand forest sector, a spatial equilibrium model was developed for log and lumber trade in the Pacific Rim. Regions included in the model were New Zealand, Chile, Australia, Japan, Eastern Canada, British Columbia: Coast and Interior, and the...
Accurate measurement of forest productivity is fundamental to understand the carbon balance of forested ecosystems. Recent changes in climate highlight the importance of developing methods to measure forest productivity so that sound economic and environmental decision can be made. Efforts to measure forest productivity across the landscape using remote sensing...