The objective of this study was to compare the value recovery achieved by a sawmill optimized bucking system and the value recovery obtained with a harvester equipped with an optimized bucking software package. To achieve this objective, a practical bucking test was conducted with a harvester. Several bucking simulations were also performed with the Optitek optimization software and two bucking optimization software packages commonly installed on commercial harvesters.
Stem measurements using systems equipped with scanning heads and cameras are significantly more accurate than those obtained by the mechanical measuring systems installed on harvesters. The poor accuracy of diameter measurements and the absence of form parameters (sweep and crook) limit the bucking efficiency that can be achieved with a harvester bucking optimization software package.
Optimized bucking without any constraints holds the promise of a very attractive revenue potential. Unfortunately, the optimal potential is unachievable in the case of sawmill optimized bucking and harvester bucking optimization. At the sawmill, bucking constraints must be taken into account in order to produce logs with the requisite characteristics (diameter and length) to ensure sawmill production efficiency. The harvester operator must also take sawmill requirements into account in making bucking decisions. These decisions are slightly more difficult to arrive at given the lower accuracy of measuring data. Such bucking constraints significantly reduce the benefits that could be achieved through optimized bucking ($8/m³ of stems or $3.2 MM /yr from bucking without constraints at the sawmill).
In other respects, simulation results indicate that optimized bucking (with constraints) at the sawmill generates an income of $136.14/m³ of stems by comparison with $134.83 $/m³ for a harvester subject to the same constraints. The difference of $1.31$/m³ represents additional income of $525,000/yr from optimized bucking at the sawmill. However, this additional income would definitely not justify the installation of a sawmill optimized bucking system; such a system would require an investment of some $6 MM.
The practical sawmill bucking test indicated that the value recovery achieved by the harvester operator amounted to $133.43/m³ of stems. This represents $1.40/m³ less than the value recovery achieved using a bucking optimization software package installed on a harvester. This difference represents a loss of income of $560,000$/yr. It is therefore highly recommended that bucking decisions and their implementation be arrived at using optimization software. Operator decisions must be limited to the greatest extent in order to improve value recovery associated with bucking in the forest.