Effects of different cut-to-length harvesting structures on the economic value of a wood procurement planning problem
In this paper, we develop a mixed integer linear model for a practical multi-facility wood-procurement planning problem using a cut-to-length (CTL) bucking system. This forest management problem is difficult to solve since it integrates the forest bucking problem and the multi-facility supply planning problem. A priority-list approach was used to generate adequate bucking patterns in the Eastern Canadian context. The model provides decision support with respect to how to harvest the different cut-blocks according to the bucking priority list used, and in what quantities harvested logs should be transported to sawmills. It aims to minimize the nonlinear harvesting cost, the transportation cost, and the inventory cost and to maximize the product value (i.e., profit maximization). The harvesting cost considers the nonlinearity of the harvester productivity function, which is an important aspect of the decision-making process in forest management. The model was used to compare the current bucking scenario to two new possibilities. These scenarios allow us to investigate the gains and losses that arise from the use of different bucking aggregations. Specifically, we consider the impact on the number of different log types per block and thus on the associated harvesting cost. Moreover, we aim to better understand the cost/benefit trade-offs of a more complex decision structure in a Canadian wood-procurement context. The results of our scenario tests showed that forest bucking aggregation (the current practice) significantly reduces the companys profit. A simple bucking disaggregation that does not increase the operational cost can improve the outcome.
wood-procurement planning forest bucking problem cut-to-length harvesting system mixed integer programming