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Bucking trees with decay

University of British Columbia

The problem bucking of trees into logs is solved using dynamic programming. The state of the model is described by the physical dimensions of the tree, such as length, diameters and sweep. This thesis incorporates decay as a description of the state. This thesis begins with a detailed analysis of decay morphology, obtaining the expected values and dispersion of key variables. The main goal of this thesis is to evaluate the decay information that could be gathered; this is done by incorporating different levels of information into the bucking algorithms. The first level assumes perfect information; in this case the algorithm is provided with the observed diameter of decay and its actual length. The second level uses an observed decay diameter and a length estimated based on the decay model. The third level also uses the observed decay diameter, but now the length is assumed to be a random variable, whose distribution parameters are based on the decay model. Furthermore, the models will be compared to the normal practices of forestry companies of British Columbia. A test of four hundred trees in four species, Spruce, Lodgepole Pine, Balsam Fir and Western Red Cedar was performed. Clear improvements were found when bucking with algorithms that consider decay. The value increased an average of 11.9%. One of the most relevant findings of this thesis is that this significant lift does not result from lower stumpage and transportation costs, but from higher recoveries. The stumpage and transportation costs are on average higher in the proposed algorithms as compared to the normal practices. This means that the use of bucking algorithms that incorporate decay translates into gains for the lumber companies as well as for the Provincial Government and the transportation industry.

Thesis/Dissertation

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2009-05-26

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http://hdl.handle.net/2429/8232

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University of British Columbia

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