Speaker
Description
In Sweden, half of the forest area is owned by approximately 300 000 non-industrial private forest (NIPF) owners. While most harvested timber is produced by companies using harvesters and forwarders, NIPF owners still contribute a substantial share of the total time spent on forest work. A large part of this work concerns logging, where tractor-based equipment, using chainsaws, tractor-mounted processors, and grapple loader trailers, represent a low-investment alternative for small-scale logging operations. Additionally, this equipment may be economically feasible for low-removal harvesting. However, studies on tractor-mounted processors’ work performance have been limited in recent decades, resulting in a lack of updated data on time consumption and cost estimates. Additionally, to the authors’ knowledge, no previous study has evaluated the combined tractor-based system during low-removal harvesting.
To address this knowledge gap, time studies were conducted in Southern Sweden during a low-removal harvest operation with a removal intensity of 10%. The studied system consisted of a Husqvarna 550 XP G chainsaw, a Hypro 450 XL processor, and a 101 4WD FTG Moheda grapple loader trailer, where the processor and grapple loader trailer were attached to a Valtra A105 tractor. The same operator executed all work in the study. Based on the time study data, regression models were developed that explained time consumption for work elements, and machine costs were estimated using the COST model.
In total, the studied logging operation comprised 36.2 productive machine hours excluding delays (PMH₀). Data was collected for 157 trees for chainsaw work and 161 trees for processor work, where the discrepancy was caused by equipment errors. Mean diameter at breast height (DBH) was 23.4 cm. For forwarding, 12 loads were recorded with a mean forwarding distance of 1 260 m and a mean load volume of 6.6 m³ob. Observed productivities for the chainsaw, processor, and grapple loader trailer work were 8.7, 4.3, and 6.3 m³ob PMH₀⁻¹, respectively. Costs, when excluding wages, were 0.26, 11.61, and 6.88 € m³ob⁻¹ for the chainsaw, processor, and grapple loader trailer work.
For chainsaw work, inter-tree distance, DBH, manual bucking, and tree species had a significant effect on time consumption. For processor work, distance between tractor stops, winching distance, DBH, manual bucking, and tree species were significant predictors. For the grapple loader trailer, forwarding distance and load volume significantly affected time consumption. Overall, the resulting models showed clear and strong relationships between predictors and time consumption and provide updated data for evaluating tractor-based harvesting systems. However, caution is warranted as the study was based on the observations of a single operator.
| Keywords | felling; processing; harvesting; forwarding |
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