Effects of bark thickness estimates on optimal log merchandising

Abstract

Bark plays a critical role in the life of a tree when it is standing. Once the tree is felled, however, bark has minimal value and may be a net financial loss to the forest industry. Because of bark's limited worth, logs are often bought and sold based on under bark measurements. Removing bark in the forest is generally very difficult, so over bark measurements are often made and converted to under bark using a bark thickness model. This study investigated the effect of six bark thickness models on the predicted volume and value recovery obtained during the log bucking process. The results indicate that the type of bark thickness model used is of lesser importance than obtaining the correct model coefficients. This study investigated the effect of using a bark thickness model developed for a different species or using data from the same species but a different site. Using the wrong species coefficients for the chosen model can result in 34 percent of the logs being out-of-specification, volume estimates being incorrect, and a loss of value to the forest owner of up to 11 percent. The results show that, for the stands in this study, 2 to 5 percent value gains could be achieved simply by using stand-specific bark thickness coefficients.