Effect of slope on productivity and cost of Eucalyptus pulpwood harvesting using single-grip purpose-built and excavator-based harvesters

ABSTRACT

With the emergence of excavator-based harvesters in cut-to-length CTL operations as a potential alternative to purpose-built harvesters, a debate has been opened as to which machine type is the most suitable in the forestry environment. A mechanized Eucalyptus pulpwood CTL operation, was observed to determine the effect of slope on harvester productivity and cost. A 2 × 2 factorial design with two treatments (machine type) against slope and individual tree volume as factors was developed. Two machine types were studied, an excavator-based harvester (Volvo EC210BF), and a purpose-built harvester (TimberPro TL725B), both fitted with Maskiner SP 591 LX harvester heads. A single operator with significant experience on both machines was used throughout the study. The machines worked on a range of slopes, from level to 50% in two separate corridors containing trees of similar volume and form. Continuous slope data was derived using large footprint light detection and ranging (LiDAR) data of the area. Calculations were carried out on each machine to determine which machine was more cost-effective. The productivity of the excavator based harvester decreased by 0.048 m³PMH⁻¹ for every 1% increase in slope, while the productivity of the purpose-built harvester was constant across slope. While the purpose-built harvester was found to have a higher mean productivity the excavator-based harvester was more economical. This suggests that, in terms of economics the excavator-based harvester was more suitable across the conditions encountered in this study.

KEYWORDS:

• Mechanized
• cut-to-length
• slope-volume interaction
• machine costing
• LiDAR

Acknowledgements

Thanks to Dr Dirk Laengin of Mondi Limited for providing the study site and the team from Iningi Contractors for the use of their machines in this study.

Disclosure statement

No potential conflict of interest was reported by the authors.