Winch Harvesting on Flat and Steep Terrain Areas and Improvement of its Methodology

With the increase of importance of bioenergy, the whole tree harvesting system was reconsidered. As a simple way of a whole tree harvesting system, this study analyzed two winching procedures in terms of productivity and influence from terrain conditions. One of the winching procedures was observed on flat terrain, where the felled trees were scattered and then, one-by-one, attached to the winch rope. The other was observed on a steep terrain, where the felled trees were concentrated in a line and then attached, at one time, to the winch rope. A significant difference caused by slope conditions appeared only in the reeling velocity. When increasing the harvested volume in a cycle, the productivity increased. The difference in productivity between two sites was slight with the same harvested volume. By the one-by-one procedure, the full volume harvested in a cycle was only skidded from the nearest felling points, while the bundled procedure skidded the full volume from various points including the farthest point. The one-by-one procedure will save the winch rope tension and reduce engine acceleration. Fuel consumption, therefore, will be decreased by applying the one-by-one procedure instead of the bundled procedure. Additionally, reducing the weight of felled trees by natural drying in a forest is effective for reducing fuel consumption not only in transportation but also in winching operation, and for enhancing the calorific value of bioenergy.