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UBC Theses and Dissertations

A practical system for determining optimal tree bucking at the stump Waddell, David Andrew


The objective of this study is to develop a practical system for determining optimal bucking patterns at the stump. The log bucking system was developed for implementation on an IBM-PC micro-computer using data for western hemlock (Tsuga heterophylla (Raf.) Sarg.). The log bucking system is based on a two-phase optimization algorithm which utilizes dynamic programming-to determine the optimal bucking pattern with the objective of maximizing potential tree value. The first phase determines the ultimate bucking pattern within the tree such that potential gross value of derived products is maximized. This pattern reflects log lengths that would be cut if the tree were at the mill. The second phase determines which of the first phase optimal cuts should be made at the stump at the time of tree felling such that extraction costs are minimized. The solution to these two phases yields a bucking pattern that maximizes potential net value from the tree. The log bucking system incorporates assessment of log grade, assignment of value based on log grade and premium log lengths, consideration of standard product lengths, and consideration of extraction costs. The log bucking system includes an algorithm for evaluating unusual bucking situations when there are practical constraints imposed on saw cut locations. For a set of test data, the potential net value of logs bucked using the optimization algorithm within the log bucking system showed an increase of 4.2% over the potential net value of trees bucked using present industry bucking practices. A two way analysis of variance for paired observations determined that this increase was significant at a 0.05% level of significance.

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