Abstract
We examined current trends in harvesting methods in Japan's aging plantation forests with respect to forest road networks and the limitations on extraction imposed by terrain. On moderate terrain there is potential for a transition from the use of conventional swing yarders towards recently developed European tower yarders, which are sufficiently powerful to enable the extraction of large trees over greater distances. We considered an example from the Kami area in the Kochi Prefecture and found that the adoption of such a system required a significant upgrading of the forest road network. An alternative approach, applicable to working on steeper terrain, is the use of a dense network of narrow forest roads, which demands the use of smaller machines with correspondingly limited extraction distance. We found numerous examples of this approach in western Japan and Shikoku Island. For both approaches discussed, finding the right balance between investment in harvesting system technologies and forest profitability is key. Our analysis suggests that a transition to the use of tower yarder systems can reduce total harvesting costs and that there are opportunities to make further efficiencies. These include the domestic production of tower yarders, intensification of forest management to increase production of high quality timber, and greater reliance on in-house rather than outsourced labor.
