## About

124

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Introduction

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Education

September 1973 - June 1978

July 1968 - June 1970

September 1964 - June 1968

## Publications

Publications (124)

Provides a review, analysis, and conclusions concerning the modeling of the maximum size-density line and its trajectory line for tree species. Includes the observations and opinions of the author.

This paper reviews the assumption of statistical regression analysis that all independent variables are nonstochastic variables and are measured without error with emphasis placed on examples found in the forestry literature. The review focuses on the consequences of violating the assumption, how to test for violation, and how to adjust or correct...

Measurement error (ME) is a component of any study involving the use of actual measurements, but is often not recognized or is ignored. The consequences of MEs on models can be severe, affecting estimates of tree and stand attributes and well as model parameters. Although correction methods do exist for countering the effects of MEs, the use of the...

Measurements on 200 Douglas-fir trees from 23 stands with diameters at breast height (DBH) ranging from 7.4 to 77.0 cm were used to determine the biomass, in kg, for the tree’s foliage, live branches, bark, sapwood, heartwood, total stem inside bark, total stem outside bark, and total living tree above ground. In addition dead branch biomass was me...

The Stand Management Cooperative (SMC) was established in 1985 to study the impact of planting density and subsequent silvicultural treatments upon stand and tree development, including growth, yield, and wood quality in plantations located throughout the Pacific Northwest of the US and Canada. The SMC Type I installations (Type I) were created to...

We examined the performance of several generalized linear fixed- and mixed-effects individual-tree mortality models for Douglas-fir stands in the Pacific Northwest. The mixed-effects models accounted for sampling and study design overdispersion. Inclusion of a random intercept term reduced model bias by 88% relative to the fixed-effects model; howe...

This study developed a system for determining growth modifiers that predict the effect of Swiss needle cast both diameter and height growth of individual trees. The modifiers were tested in the context of a specific growth model (ORGANON), but they should be applicable
to any individual-tree growth model that has similar growth expectations for man...

This study answered the following questions concerning respaced, thinned and/or fertilized plots from the Stand Management Type I Installations:
1. Is there a trend in plot level site index estimates across total age for the three levels of respacing (ISPA/1, ISPA/2, and ISPA/4, where ISPA is Initial Stems Per Acre) on plots that received no subse...

Forest Growth and Yield Modelingsynthesizes current scientific literature and provides insights in how models are constructed. Giving suggestions for future developments, and outlining keys for successful implementation of models the book provides a thorough and up-to-date, single source reference for students, researchers and practitioners requiri...

IntroductionTotal heightCrown lengthCrown width and profileStem volume and taperBiomassUse of static equations to predict missing valuesSummary

IntroductionTwo-sided competitionOne-sided competitionLimitationsSummary

IntroductionCollection of appropriate dataGeneration of appropriate dataTemporal scaleSpatial scaleComputer interfaceVisualizationOutputSummary

IntroductionWhole-stand modelsSize-class modelsSummary

IntroductionData requirementsModel formParameter estimationSummary

IntroductionTypes of hybrid modelsComparison to statistical modelsSummary

IntroductionLinked stand- and size-class modelsLinked stand- and tree-level modelsSummary

IntroductionSingle-tree distance-dependent modelsTree-list distance-independent modelsSummary

IntroductionModel criticismModel benchmarkingModel calibrationSummary

IntroductionStand-level mortalityIndividual-tree-level mortalityMechanistic models of mortalityDevelopment and application of mortality equationsSummary

IntroductionKey physiological processesExample modelsLimitationsSummary

Improving predictionsImproving input dataImproving softwareSummary

IntroductionGenetic improvementsEarly stand treatmentsThinningFertilizationCombined thinning and fertilizationHarvestingSummary

IntroductionPhytocentric measures of site qualityGeocentric measures of site productivitySummary

IntroductionSeedingRegenerationRecruitmentSummary

Tree-list models are developed and utilized in many regions because they are flexible, provide the highest resolution of predictions, and simulate a range of stand compositions and structures. Although they can be sensitive to error compounding, a properly specified tree-list model emulates many of the important stand-level principles. In addition,...

The equations used in ORGANON for predicting the various elements of tree volume and taper were published in the 1980s: bark thickness equations (Larsen and Hann 1985), stump diameter at 1.0-feet above the ground equations (Walters et al. 1985), total stem cubic foot volume above breast height equations (Walters et al. 1985, Hann et al. 1987), merc...

This project used a comprehensive modeling data sets from red alder plantations in Western Oregon and Washington to develop the height-diameter; top-height/site-index; maximum crown width; largest crown width; crown profile; branch diameter; height-to-crown-base; annual diameter increment; annual height increment; annual crown recession; annual mor...

The volume increment of individual trees is often inferred from a volume or taper equation and predicted or observed diameter and height increments. Prediction errors can be compounded with this type of approach because of the array of equations used and differences in their accuracy. The consequences of several alternative approaches for indirectl...

Height growth equations for dominant trees are needed for growth and yield projections, to determine appropriate silvicultural regimes, and to estimate site index. Red alder [Alnus rubra Bong.] is a fast-growing hardwood species that is widely planted in the Pacific Northwest, USA. However, red alder dominant height growth equations used currently...

Subsampling and subsequent imputation of tree heights can improve the predictive performance of stand volume estimation but may also introduce biases. Using coastal Douglas-fir data from southwest Oregon, USA, the predictive performance of several height imputation strategies for estimating stand volume was evaluated. A subsample of 1-15 trees was...

Using an extensive Douglas-fir data set from southwest Oregon, we examined the (1) performance and suitability of selected prediction strategies, (2) contribution of relative position and stand-density measures in improving tree height (h) prediction values, and (3) effect of different subsampling designs to fill in missing h values in a new stand...

Selected tree height and diameter functions were evaluated for their predictive abilities for major tree species of southwest Oregon. Two sets of equations were evaluated. The first set included four base equations for estimating height as a function of individual tree diameter, and the remaining 16 equations enhanced the four base equations with a...

This study refit and updated the modifier equations used in ORGANON to characterize the impact of Swiss needle cast upon the diameter and height increment of Douglas-fir. The study also simulated the impacts of these tree-level modifiers upon stand-level development.

Using existing data from untreated research plots, we developed an equation for predicting 5-yr diameter-growth rate (ΔD5) for western hemlock [Tsuga heterophylla (Raf.) Sarg.] in the coastal region of the Pacific Northwest. This equation is a revision of the equation constructed in 1995–1997 for the Stand Management Cooperative’s (SMC) version of...

In a comparison of the responses predicted by six regional growth models to various treatments, Johnson (2005) reported that the SMC version of ORGANON (SMC-ORGANON) predicted the most conservative (smallest) response to fertilization of all the models.This finding led us to conduct an exhaustive review of the modeling techniques and assumptions us...

Using existing data from untreated research plots, we developed equations for predicting 5-yr diameter-growth rate (ΔD5), 5-yr height-growth rate (ΔH5), and 5-yr mortality rate (PM5) for Douglas-fir [Pseudotsuga
menziesii (Mirb.) Franco] in the coastal region of the Pacific Northwest. These equations are revisions of the equations constructed in 19...

An equation was developed for estimating a modifier (ranging from 0 to 1) that adjusts ORGANON diameter increment equations commensurate with initial Swiss needle cast severity.

A measurement error (ME) is a component of any study involving the use of actual measurements, but is often not recognized or is ignored. The consequences of ME on models can be severe, affecting estimates of tree and stand attributes and model parameters. Although correction methods do exist for countering the effects of ME, the use of these metho...

Two nonspatial approaches for modeling tree crown recession (ΔHCB) were evaluated by using 5341 observations from Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). The first approach applies a static height-to-crown-base (HCB) equation at the start and end of the growth period and uses the difference in these predictions as an estimate of ΔHCB. T...

Over the last decade, Oregon State University (OSU) College Forests has successfully implemented a plan for its 4600-ha forest in the Willamette Valley of Oregon that called for significant timber harvest under a range of silvicultural systems, including clear-cutting, while providing teaching, research and extension opportunities. Despite discover...

Crown profile equations were developed for stand-grown western hemlock (Tsuga heterophylla (Raf.) Sarg.) in northwest Oregon. The profile model uses a segmented approach, dividing the crown into an upper and lower portion at the point of the largest crown width (LCW). The model explains about 86% of the variation in crown width when LCW is known bu...

Using existing permanent research plot data, we developed equations for predicting height-to-crown-base (HCB), 5-yr diameter growth rate (DG), 5-yr height-growth rate (HG), 5-yr mortality rate (PM), and the maximum size-density trajectory for Douglas-fir and western hemlock in the coastal region of the Pacific Northwest. With the exception of the H...

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 model for pr...

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 m...

Mixed conifer and hardwood stands in southwestern Oregon were studied to explore the hypothesis that competition effects on individual-tree growth and survival will differ according to the species comprising the competition measure. Likewise, it was hypothesized that competition measures should extrapolate best if crown-based surrogates are given p...

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 procedures. These equat...

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 correc...

Equations for predicting tree height as a function of diameter outside bark at breast height are presented for various tree species common to southwest Oregon. Data for damaged and undamaged trees were analyzed with weighted nonlinear regression techniques. The effects of specific damaging agents and their severity on the height-diameter relationsh...

Three equations for predicting tree height as a function of diameter (outside bark) at breast height are presented for six species found in coastal regions of the Pacific Northwest. Foresters can use these “height–diameter” equations to avoid the time-consuming task of measuring heights of all individual trees in an inventory, a stand exam, or a ti...

This study developed a method for predicting the crown profile of stand-grown trees that can be adjusted to other populations of the same species by using either measurements or predictions of the largest crown width (LCW) for trees in the alternative population. The method should be of particular interest for tree species such as Douglas-fir that...

Hann and Scrivani (1987) developed dominant height growth equations for Douglas-fir in southwest Oregon using stem analysis data sets with an upper age of approximately 125 years at breast height. The objective of this study was to determine whether these equations could be extrapolated for ages of 250 years or more. Data for the evaluation came fr...

Reconstruction of the spatial pattern of trees is important for the accurate visual display of unmapped stands. The proposed process for generating the spatial pattern is a nonsimple sequential inhibition process, with the inhibition zone proportionate to the scaled maximum crown width of an open- grown tree of the same species and same diameter at...

Largest crown width (LCW) equations for stand-grown trees were developed for 14 tree species found in western Oregon. The equations are used in the growth-and-yield model ORGANON and in the stand-visualization program VIZ4ST. They were constructed such that LCW equals the maximum crown width of open-grown trees when the crown ratio is equal to one....

Growth and yield simulators may be characterized with regard to the aggregation structure employed. Individual-tree simulators are an example of a passive aggregation approach. Whole-stand models represent an active aggregation structure. Of particular interest is the disaggregative modeling approach, which employs elements of both individual-tree...

Growth and yield simulators may be characterized with regard to the aggregation structure employed. Individual-tree simulators are an example of a passive aggregation approach. Whole-stand models represent an active aggregation structure. Of particular interest is the disaggregative modeling approach, which employs elements of both individual-tree...

The efficiency of six disaggregative methods and two individual-tree methods was evaluated in terms of their ability to predict 5-year basal area increment for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in western Oregon. Models were developed for predicting gross stand basal-area increment and individual-tree diameter increment. In...

Canopy architectures of five structurally complex forest stands and three structurally simple forest stands in southwest Oregon and the Willamette Valley, Oregon, were evaluated and quantified through crown area profiles. Mixed conifer and mixed conifer-hardwood stands across a range of sites were sampled for crown widths and heights. Crown width a...

Just minutes from the campus of Oregon State University, the McDonald-Dunn Research Forest is important for education and research at the College of Forestry and other academic units. Proximity to Corvallis also makes this 11 648-acre forest an important recreational asset to the community. To enhance the property's educational and research functio...

The efficiency of six disaggregative methods and two individual-tree methods was evaluated in terms of their ability to predict 5-year basal area increment for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in western Oregon. Models were developed for predicting gross stand basal-area increment and individual-tree diameter increment. In...

Summaries from 49 published articles on site-index and dominant-height-growth curves and equations are presented for 20 tree species or species groups found in California, Oregon, Washington, British Columbia, southeastern Alaska, Idaho, and western Montana. The summaries are organized by species. Each summary describes the modeling approach, type...

Summaries from 49 published articles on tree volume and taper equations are presented for 39 tree species found in California, Oregon, Washington, British Columbia, southeast Alaska, Idaho, and western Montana. The summaries are organized by species and then by type of equation (volume or taper). Each summary describes the types of dependent variab...

Equations are presented that predict individual-tree 5-year diameter growth, outside bark, for Douglas-fir and grand fir in the western Willamette Valley of Oregon. The data used to develop the equations came from 10,121 trees sampled from 136 stands. These equations express diameter growth as a function of diameter at breast
height, crown ratio, s...

Size-density trajectories were developed for pure red alder (Alnus rubra Bong) and Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) stands with quadratic mean diameter of the stand as the tree-size variable. The resulting self-thinning or maximum size-density line for red alder had a steeper slope (-0.64) than that for Douglas-fir (-0.52). The as...

1. The monoculture self-thinning concept was expanded to polycultures by describing a self-thinning surface in a mixed-species size-density space. The size-density relationships of pure and mixed populations of Alnus rubra and Pseudotsuga menziesii in the Pacific Northwest, USA were investigated.
2. For polycultures of A. ruba and P. menziesii, the...

This study analyzed the effect on growth-model predictions of introducing differential design error to predictor variables that are influenced by the sampling-unit design, such as basal area per acre. Computer simulations of five forest stands were generated from random spatial distributions and field data coveting a range of stand conditions. Two...

Three major determinants of wood quality in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) were estimated from the dynamics of crown structure in ORGANON, an individual-tree, distance-independent growth model. Branch whorl locations were estimated directly from the height growth predictions assuming formation of one whorl per year. Mean maximum...

Equations are presented that predict individual-tree 5-year diameter growth, outside bark, for 14 tree species in southwest Oregon. The data used to develop the equations came from 19,245 trees sampled from 391 stands in the study area. These equations express diameter growth as a function of diameter at breast height, crown ratio, site index, tota...

Duration of branch radial growth and longevity were summarized for 2153 branches immediately below the current live crown of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) trees in southwestern Oregon. Branch longevity averaged 24 years with a range of 4 to 72 years. The number of years without perceptible (13 × hand lens) annual branch radial g...

Seven alternative sampling strategies for estimating past crown recession on temporary plots were compared using known 5-yr recession rates reconstructed on permanent plots. Actual past crown recession was established on 28 Douglas-fir trees by application of a branch mortality dating technique to all branches in 10-15 whorls below present crown ba...

Crown recession rates were estimated by branch mortality dating on 357 sectioned Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stems from temporary plots. Numerous nonlinear, logarithmic, and gamma-theory generalized linear models were developed for predicting 5-year crown recession across a range in tree, stand, and site conditions. Residual...

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. Parameters were est...

Models of stand growth and yield must include an estimate of mortality. For individual-tree/distance-independent growth-and-yield models, it is necessary (1) to predict the probability of death of individual trees and (2) to keep stand projections within reasonable biological limits (e.g., the maximum basal area that the stand can achieve).
In thi...

A segmented polynomial taper equation for southwestern Oregon Douglas-fir (Pseudotsuga menziesii) predicts double bark thickness (dbt) at any point above breast height. Below breast height predictions assume conformity to a neiloid frustrum. The equations facilitate estimation of inside bark diameter (dib) given outside bark (dob) measurements. Bar...

Crown dimensions and sapwood area near crown base were measured on 189 Douglas-fir trees in southwestern Oregon. Sapwood areas were interpolated or extrapolated to crown base with a sapwood taper function. Various transformations of crown length and crown radius (as well as crown base stem diameter as a surrogate for crown diameter) were assessed f...

This paper presents equations developed to predict the height to live crown base of six species in the central western Willamette Valley of Oregon. Weighted nonlinear regression was used to fit a separate logistic equation for each species. the predictor variables are total height, crown competition factor in trees with larger diameter at breast he...

Five model forms were evaluated for their ability to predict height growth rate of individual Douglas-firs (Pseudotsuga menziesii [Mirb.] Franco) growing in even or uneven-aged stands of southwest Oregon. Three models had been previously used for Douglas-fir; the fourth was a simple modification of one of these, and the fifth was developed in this...