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; however, model discrimination...
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...
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...
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...
In their recent Canadian Journal of Forest Research Comment 368 article, Wilson and Oliver (2000) developed an equation for predicting the average ratio of height to diameter at breast height for the largest 250 trees/ha (H/DL250) in unthinned stands as a function of initial density and dominant height of the...
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 preference over diameter-based...
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 addition, models were...
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...
The purpose of this study was to determine if infection levels of dwarf mistletoe on ponderosa pine could be detected with color aerial photography. The photography was taken in early September using Kodak Ektachrome Infrared Aero and Ektachrome Aero films at scales of 1/4000, 1/2000, and 1/1000. Ground truth consisted...
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....
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 tree height, crown competition factor in trees...
Equations for predicting tree height as a function of diameter
outside bark at breast height are presented for 16 tree species
from the central western Willamette Valley of Oregon. Foresters
can use these "height-diameter" equations to avoid the time consuming
task of measuring heights of all individual trees in an...
Equations are presented for predicting height to crown base (or bole ratio) for fourteen species of trees common to the mixed-conifer zone of southwest Oregon. Nonlinear regression was used to fit a weighted logistic function for each species. The independent variables include height, crown competition factor in larger trees, stand...
Equations for predicting total height as a function of diameter at breast height are presented for 17 tree species from southwest Oregon. Because basal area and site index often influence tree height, additional equations are presented which may include either or both of these as independent variables. Equation coefficients were...
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,...
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...
Equations and tables predicting gross total stem volumes in cubic feet are presented for Douglas-fir, grand fir, white fir, ponderosa pine, sugar pine, and incense-cedar. The data were gathered in second-growth, mixed-conifer stands of southwest Oregon. The basic equations use diameter outside bark at breast height and total tree height...
Tables are presented that summarize 108 published articles on forest growth and yield in the Pacific Northwest. Each table describes the form of the information presented, the species to which the information is applicable, the data sources used to develop the information, the data needed to predict growth and yield,...
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 1995–1997
for...
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...
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...
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 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...
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...
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...
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,...
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...
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...
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 of curves/equations,...
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...
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...