Maximizing the economic benefit for cable yarding timber harvesting operations by spatially optimizing tree selection

Abstract

The efficiency of forest logging operations can be strongly affected by the layout of the harvesting pattern, which is usually based on silvicultural constraints and technical feasibility. Specifically, individual tree volume and the spatial distribution of trees significantly impact the overall harvesting performance. Spatial optimization of tree selection at the forest stand level may improve timber harvest efficiency by maximizing key performance indicators, such as the economic benefit, under given operational and silvicultural constraints. In this study, we applied two harvesting operation-optimization approaches based on integer programming for uphill cable yarding operations in mountain areas, including tree selection and load maximization. The first approach involves tree selection based on single tree harvest, while the second one performs tree selection based on tree clusters harvest per work cycle. As input elements a productivity model, derived by time-motion study with a Mounty MT50-2 and individual tree parameters extracted from high-resolution airborne laser scanning data, were prepared. Single tree information was further rated by financial value, and subsequently combined with the productivity model, allowing a detailed breakdown of operational costs. The results showed that optimizing the tree selection while respecting the allowable cut timber volume established in the harvesting plan can improve the efficiency of forest operations. The cluster approach was shown to be more efficient in terms of economic benefit compared to the actual selection, with an increase of 24.94%. However, the single tree approach resulted in a decrease of economic benefit compared to the actual selection, with a decrease of 22.85%.