Feasibility of an Adapted Tree Section Method for Integrated Harvesting of Pulpwood and Energy Wood in Early Thinning of Scots Pine

摘要

This paper deals with the feasibility of adapted tree section method using a conceptual bundle harvester for the integrated production of pulpwood and energy wood in first commercial thinning of Scots pine (Pinus sylvestris L.). The harvester would operate on the site, and it would be comprised of a base machine, an accumulating felling head, and a compacting device. Separation of pulpwood and energy wood fractions would take place at a pulp mill. In this experiment, the trees were topped and the top sections were left at the site. The concept was evaluated from an ecological and economic point of view. Nutrient losses were significantly lower compared to whole-tree harvesting. The energy fraction increased by 150% compared to the cut-to-length method, in which stem bark represents the energy fraction. In bundle transportation, the load-bearing capacity of standard trucks can be highly utilized. For short distance hauling by conventional forwarders, an expansion of the load space is required in order to improve the utilization of the load-bearing capacity. Due to insufficient compaction capability when dealing with large trees, the bundling concept seems to be more appealing in harvesting energy wood from dense stands characterized by small stem size. In energy wood procurement, the bundling concept has several indirect advantages compared to the conventional forest chip production. Standard vehicles, with minor modifications, can be used for transportation. Machines involved in the operation can work independently, increasing the reliability of the system. Bundling with accurate real-time information about the daily production and inventories creates favourable conditions for efficient process control.