Harvesting alternatives and cost factors of delimbed energy wood.

The possibilities of harvesting small-diameter energy wood as delimbed instead of whole-trees was studied in the project ”Harvesting alternatives and cost factors of delimbed energy wood”. The study focused on comparing the productivity and costs of cutting whole-trees and delimbed trees. The cutting was carried out using the multi-tree-handling technique and only energy wood was recovered. The second aim was to study integrated harvesting of industrial round wood and delimbed energy wood using the conventional single-tree-handling technique. The regional availability, procurement costs and measuring of delimbed energy wood were also estimated in the study. The productivity of cutting delimbed energy wood was 10–40% lower compared to cutting whole-trees. This was due to the decreased stem volume. However, time consumption per tree was at the same level. The productivity of forwarding delimbed wood was 10–20% higher compared to forwarding whole-trees. Integrated harvesting of industrial wood and delimbed energy wood was found to be rather costly. The productivity of harvesting energy wood from tops of industrial wood stems was almost three times higher than productivity of harvesting energy wood from small stems not meeting the diameter requirements of pulp wood. Delimbing lowered the regional energy wood removals by 42–46% and increased the procurement costs by 17–25% compared to whole tree harvesting. Nevertheless, the study showed that the forest energy potential is increased and procurement costs are reduced, if delimbed energy wood is harvested from areas where whole tree harvesting is not acceptable due to nutrient loss or other ecological reasons. The measuring method of delimbed energy wood was based on estimating the frame volume and the solid volume percentage of the tree bunches by using the harvester’s measuring device. The estimation of both variables was rather inaccurate but the overall accuracy of the measuring method was rather good when the size of the harvested lot was larger than 10 m3. The project was funded by Tekes, Komatsu Forest Oy, Sampo-Rosenlew Oy and Waratah-OM Oy. The research was carried out by the Finnish Forest Research Institute and the TTS Institute.