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...
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...
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...
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...
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...
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...
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...
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...