Evaluation of Alternative Cut-to-Length Harvesting Technology for Native Forest Thinning in Australia


  • Mauricio A. Acuna University of Tasmania
  • Loren D. Kellogg Oregon State University


This research quantified the equipment productivity relationships between piece size and terrain conditions for mechanized harvesting operations in native forest re-growth thinning. In addition, the economic gains or losses of adding a feller buncher to a cut-to-length (CTL) harvesting system were quantified. Study results indicate that although the use of a feller buncher working in combination with two processors is more productive than the use of a harvester-processor (single-grip harvester) working alone the high cost per tonne of this harvesting system means that its use is not recommended in areas with moderately steep terrain and small tree diameter. The differential in costs obtained between the two harvesting systems (feller buncher and two processors vs. one harvester-processor) on moderately steep and gentle terrain was approximately AUD$5/tonne and AUD$2/tonne, respectively, for an average tree diameter of 19 cm. Regression models developed from the study showed that diameter at breast height accounted for more than 85 percent of the variance in productivity of the machines and, therefore, represented the main driver of productivity and cost per tonne of the harvesting systems in all of the scenarios studied.