Productivity, cost and impact to residual trees and soil of the all-terrain skyline yarding system in selectively logged second growth dipterocarp forest
1992
Hernandez, A.Z.
The main objectives of this study were to: 1) identify and define the working sequences of the Ganther-Koller all-terrain skyline yarding system developed by the RP-German Dipterocarp Forest Management Project; 2) analyze the factors that affect the productivity of the yarding system; 3) derive prediction equations for the needed yarding time of the yarding system; 4) determine the productivity and cost of yarding per unit of output in a given set of conditions; and 5) determine the damages incurred by the system to residual trees and soil. The results of the study showed that the Ganther-Koller all-terrain skyline yarding system has four major working sequences: transfer; rigging up; yarding; and rigging down. Its productive yarding time is a function of yarding distance along cableway, lateral yarding distance, terrain, bush, number of chokesmen and chasermen, number of logs per turn, turn volume, and adverse skyline slope. The analysis of the time studies indicates a productivity of 7.9 cubic meters per hour at a yarding cost of PHP 330.35 per cubic meters. However, the developed prediction equations, productivity rate and cost are only true for the conditions prevailing in the cableway logging set-up where the time studies were gathered and the assumptions used in the cost calculation. In addition, damages caused by the system to the remaining residual trees and soil was minimal
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