Forwarding of Whole Trees After Manual and Mechanized Felling Bunching in Pre-Commercial Thinnings

Abstract This paper examines the forwarding productivity of energy wood thinnings. The objectives of the study were to: compare the forwarding productivity following either manual or mechanized felling of whole trees and create productivity models for forwarding. The time consumption of the work phases in forwarding, following manual and mechanized cutting, was formulated by applying a regression analysis, in which the independent variables were cutting removal (m3/ha) and forwarding distance (m). The final calculation unit for time consumption in each of the work elements was second (s) per solid cubic meter (m3). Time studies were carried out using two Timberjack 810B forwarders. According to these results, forwarding productivity following mechanized energy wood cutting was significantly higher compared to productivity after manual cutting. Mechanized cutting by the harvester enables the felling and bunching of whole trees into large grapple loads close to the side of the strip road, which clearly improves the output of forwarding thereby helping to reduce costs. When the forwarding distance was 250 m, accumulation of energy wood was 60 m3/ha, and load size was 6 m3, the forwarding productivity following mechanized cutting was 11.9 m3/E0h and 7.1 m3/E0h after manual cutting.