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 5.7 m 3 /scheduled machine hour (SMH) and $27.9/m 3 , 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.

Cable yarding technology remains the most effective operation in steep terrain harvesting systems; however, it has limitations and challenges. Using cable yarders (tractor-, truck-, and excavator-based) to extract tree lengths and whole trees has been common since the late 20th century in South Korea, and cable yarding operations were developed in the late 1800s in the United States and Europe. Machine potential and limitations must be understood to ensure the widespread use of technology, strong cooperation, and optimal selection of machinery size. We reviewed the literature on tower yarder performances from 1990–2021 to determine the alteration of yarders and its productivity pattern and obtained 23 papers; <2 publications per year discussed the determination of cable yarding productivity. We selected independent variables (e.g., silvicultural treatment, harvesting method, and cycle log volume) for cable yarding that would likely affect productivity. Data were analyzed to compare productivities under silvicultural treatment, the harvesting method, and yarding direction and identify the interaction mechanical power (i.e., lifting capacity and machine power), yarding distance, and slope. Cable yarder productivity rates generally depended on the silvicultural treatment, harvesting method, and yarding direction, particularly in clear-cut, tree-length, and uphill yarding operation activities. The lifting capacity, machine power, and slope had no significant correlation with yarders’ productivity, particularly in thinning operations, whereas, in clear-cut productivity, it was influenced by these variables. The results contribute to improving operation activities for cable yarding systems and towards future research directions.