Evaluation of a novel prototype harvester head in early fuel-wood thinnings

The objectives of this study were to evaluate and compare the productivity and operating costs of two harvesting systems for fuel-wood production in dense early thinnings, from stand to road-side: a harvester fitted with a prototype MAMA (brand name) felling head featuring a feed-roller system for compression-processing paired with a standard forwarder; and a harvester with a conventional C16 felling head paired with a forwarder having a grapple-saw for bucking. Because the MAMA head was a prototype, an additional objective was to identify factors that influenced the effectiveness of the MAMA system. The time required for the felling, accumulation, compression-processing and bunching of whole tree-parts using the MAMA head was no greater than that for the felling and bunching of whole trees with the C16 head. The feed-roller system increased the efficiency of the bucking process and also increased the bulk density of the harvested bunches by 47–70%. However, it reduced the overall harvesting yield by 10–23%. Consequently, the harvester productivity with the MAMA head was 12–14% lower than with the C16 head. However, because the MAMA head also increased the forwarder’s load size by 17–24% through its compression-processing of the biomass, it increased the forwarder’s productivity by 12% for an extraction distance of 300 m (one way). Given typical stand conditions and an extraction distance of 300 m, the operating costs of the system with the MAMA head were 1% higher than for the C16 head. In addition, the operating costs of the MAMA system should decrease with the extraction distance. In conclusion, even though the MAMA head is an early prototype that has not been heavily optimized in terms of mass and functionality, its operating costs are already comparable to those of conventional alternatives. With further development, it could significantly reduce the operating costs of harvesting from stand to road-side.