The deterioration of merchantable trees over time is often assumed to be negligible in growth models and yield calculations. Although the annual probability of becoming unmerchantable is small, the cumulative probability over a cutting cycle is significant, and should be included in yield studies.
Logistic regression analyses of permanent sample plot data revealed that changing merchantability can be modelled using species, stand basal area, tree size and time since last logging. The equation developed for the rainforests of north Queensland indicates that up to ten percent of trees may become unmerchantable during a forty year cutting cycle.
The abstract and pdf of the published article reproduced in ePublications@SCU with the permission of Commonwealth Forestry Review