Yarding productivity of tree-length harvesting using a small cable-yarder in steep slope, South Korea

Abstract

Tree diameter, topography, and stand accessibility have been major issues to consider when selecting the optimal equipment to extract logs from steep slopes. With an increasing interest using cable logging systems from steep slopes in South Korea, the yarding productivity and cost were evaluated for a small scale cable yarder. A standard time and motions study method were applied for three clearcut units in larch (Larix kaempferi) stands located in Pyeongan, Gogil, and Ungyo in Eastern Gangwon of South Korea. The average yarding productivity and cost were calculated at 5.7m3/scheduled machine hour (SMH) and $27.9/m3, respectively. The regression analysis reveals that the mean diameter class was found to have greatly influenced yarding productivity. Among the factors determining the yarding cost, tree volume was found to have the greatest influence, followed by lateral distance and yarding distance. Other factors that may contribute to reducing delay and improving yarding productivity included operational planning (i.e. corridor layout considering topographic conditions), pre-inspection, and post-maintenance/management of the yarder system, and specialized technical training to enhance yarding productivity.