Production and Costs of motor-manual tree felling in Hyrcanian forest

Tree felling includes all activities undertaken to fell standing trees and prepare them for extraction. This study was conducted in Gorazbon district in the Hyrcanian forest. The objectives of the study were to discover the special characteristics in the time consumption of manual tree felling, productivity and costs, and develop regression model of tree felling in selection conditions. The continuous time study was conducted with professional operators for chain-saw felling and the cycles were broken down into time elements. Different variables were measured such as time consumption, inter-tree distance, tree species, tree volume, and tree diameter. Rest and meal time of working crew was the most time-consuming element in felling, followed by under-cut and walk-to-tree times. The operational delay was the most time-consuming delay time. The results showed that time consumption for under-cut and backcut was increased with increasing diameter. Labor costs accounted for 44 % of the hourly cost while only 2 % was related to machine cost. A significant linear relationship was found between cycle time and diameter. Productivity of chainsaw felling was increased related to tree DBH as a power function. The cost of chainsaw felling with and without delay time were USD 3.03 and 2.7 per cubic meters, respectively. The cost of felling was increased as simple exponential function when DBH of harvested tree was decreased. However, the unit felling cost for chainsaw operation decreased as size of tree increased. Total felling cycle time without delay averaged 4.1 minutes and with delay time were averaged 4.65 minutes.