Prediction of Growth and Mortality of Oregon White Oak in the Pacific Northwest

In this article, we describe new diameter growth and mortality equations for Oregon white oak that were incorporated recently into ORGANON (download at organon/downld.htm). Equations also were developed to predict total tree height (Ht; as a function of diameter), and height to live crown. We chose to develop new equations because the equations in the previous ORGANON model were based on very few observations and initial analyses of diameter growth data from Oregon and Washington indicated that they consistently underpredicted diameter growth. The new equations, which are based on a much larger data set, should improve estimates of Oregon white oak development across a range of stand conditions. In addition, the equations should provide greater insight into how factors such as initial diameter, site index (SI), crown ratio (CR), and stand basal area (BA) affect oak growth and mortality. The long-term development of oak woodland and a conifer-oak stand (with and without conifer removal to restore it to a low-density oak stand) were projected to illustrate two common conditions. Projections also were performed using the previous ORGANON model and FVS to compare the results of these models with those obtained with the new equations.