Predicting height for undamaged and damaged trees in southwest Oregon

Abstract

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 relationship were explored. Damage correction multipliers were estimated, then used to correct predicted height where damage was noted. Because the relationship between height and diameter changes with the competitive position of the tree in a stand, alternative equations are presented that include the average height and diameter of the 40 largest-diameter undamaged conifer trees per acre. Foresters can use these “height-diameter” equations to reduce the time-consuming task of measuring heights of every tree in an inventory, stand exam, or timber cruise. They can also use these equations to estimate the change in height as diameter changes. These equations will be incorporated into the new southwest Oregon version of ORGANON, which extends the model to older stands and stands with a heavier component of hardwood species