公告日期 : 2014-07-09
Productivity and Cost of a Small-scale Timber Forwarding System Using Farm Tractors in the Hyrcanian Forest, Northern Iran
Key words：small-scale timber extraction, farm tractor, pulpwood, fuelwood, time study.
Tractor-based systems are the most common type of small-scale forestry equipment. In the Hyrcanian Forest of northern Iran, farm tractors equipped with a 2-wheel trailer are mostly used to perform forwarding operations of pulpwood and fuelwood for with small-scale timber harvesting. A continuous time study was conducted on pulpwood and fuelwood forwarding using farm tractors in the Hyrcanian Forest, to assess farm tractor productivity and costs and develop time regression models and estimate forwarding costs. The analysis indicated that two of the most important factor affecting forwarding productivity are the skidding distance and number of logs per turn. The average hourly productivity values of forwarding with farm tractors were estimated to be 2.66 and 3.83 m3 for pulpwood and fuelwood, respectively. When the skidding distance increased, the total time of a cycle increased. The productivity of farm tractors logarithmically decreased with extraction distance. The cost of the farm tractor forwarding system was US$50.85 per productive machine hour. Hourly costs of using farm tractors for pulpwood and fuelwood forwarding were US$13.3 and 19.1 m-3. The cost of farm tractor forwarding increased by a simple power equation as the extraction distance increased. The loading phase required the largest time per trip, because of manual loading and physical handling of logs that was a labor-intensive operation. In conclusion, a forwarding operation has advantages such as larger payloads, and transporting logs off the ground that are good alternatives in order to extract pulpwood and fuelwood from gentle slopes of the Hycanian Forest.