Estimating Time Consumption and Productivity of Roundwood Skidding in Group Shelterwood System – a Case Study in a Broadleaved Mixed Stand Located in Reduced Accessibility Conditions

Abstract

In Romanian forestry, skidders represent the most used equipment for wood extraction, while the group shelterwood system is one of the most used silvicultural forest management strategies. Production rates are important indicators when trying to assess the efficiency of a process, since they can be used in different practical applications, starting with operational planning and ending with energetic analyses or LCA studies. The reduced accessibility of forest stands is one of the main problems of Romanian forestry, and therefore a lot of time and energy is usually spent in harvesting operations. In the present days, it has become very important to know the effects of these operational conditions. In order to evaluate the effects of very long skidding distances on the time inputs and productivity, a time study was conducted for a Romanian skidder that operated in a mixed hardwood stand located in Central Romania, where group shelterwood cuttings were applied. We found out that the time input of a winching work cycle was most affected by winching distance and the number of logs, and developed time consumption models for the main groups of operations. For the mean conditions (winching distance of 8.7 m, mean skidding distance of 1706.3 m, a load volume of 4.89 m and 6.48 logs per turn) the net and gross production rates were of 4.41 m3/h and 3.12 m3/h, respectively. The results of this study may be helpful in operational costing or harvesting planning when dealing with reduced accesibility conditions