Basic examination on the harvesting of small-diameter trees as unutilized forest biomass in Japan

In order to secure the supply source as well as promote the further utilization of “Untapped wood” following the completion of the Feed-in Tariff Scheme for Renewable Energy (FIT), small-diameter trees such as not only cleanings from young planted forests but also broad-leaved trees from coppice forests can be expected to be prospective in Japan. In order to discuss the effective method of harvesting such small-diameter trees as unutilized forest biomass appropriate for Japan, a basic model forest was assumed in this study, while the harvesting of small-diameter trees was experimented with a truck-mounted multi-tree felling head and time-studied. As a result, the machine used in the experiment could fell the maximum six trees inward a row from a forest road, but the harvesting (felling, accumulating, and chipping) cost was the cheapest when the machine felled five trees inward a row. The results of the sensitivity analysis suggested what kind of improvement should be necessary for the felling machine used in the experiment.