عنوان مقاله [English]
Evaluating the cost of different harvesting alternatives is necessary to develop an efficient forest operation plan. This requires estimation of harvesting production rates, equipment and labor costs. To do this, the harvest planner must understand the operating and cost characteristics of the available logging systems especially considering the tree size, skidding distance, and skidding direction. Productivity studies are still frequently used to describe, understand and improve forest operations. This study was carried out in Namkhaneh district in Kheyrud forest using Timberjack 450c wheeled cable skidder. The objectives of this study were to formulate time-consumption models for short-log and long -log methods and determine factors such as production, cost per hour and machine rate during the skidding phase. The study used continuous time studies based on empirical data for two logging methods. The regression model for short-log method included the following factors: skidding distance and number of log. However, the model for long-log method included: skidding distance and winching distance. Results indicated that the productivity of the short-log and the long-log with delay times was found to be 6.71 and 9.84 m3/h, respectively. The productivity of the short-log and the long-log without delay times was found to be 8.92 and 13.34 m3/h, respectively. The cost in short-log method with and without delay times were 98120 and 73810 Rials/m3, and the cost in long-log method with and without delay times were 66910 and 49350 Rials/m3, respectively. Productions in both short and long log methods were directly related to skidding distance. Also, productivity was more sensitive to skidding distance than number of log and winching distance. Finally, this paper analyzes the delay component of time-study data sets.