Effect of multi-tree handling and tree-size on harvester performance in small-diameter hardwood thinnings Erber G., Holzleitner F., Kastner M., Stampfer K. (2016). Effect of multi-tree handling and tree-size on harvester performance in small-diameter hardwood thinnings. Silva Fennica vol. 50 no. 1 article id 1428. 17p. Highlights• Harvesting with the accumulating energy wood head EF28 was studied under small tree dimension (8 dm³) in hardwood thinnings.• Reasonable productivity was achieved.• Maximum achieved cutting diameter in hornbeam stand was 23 cm and 15% lower than in softwood stands.• Head has potential under such conditions. AbstractEarly thinnings are laborious and costly. Thus forest companies are searching for cost and time efficient ways to carry out this task. The study's purpose was to determine the productivity of the EF28 accumulating energy wood harvesting head in harvesting small-diameter hornbeam (Carpinus betulus L.) undergrowth trees and evaluate the effect of its multi-tree handling (MTH) capacity on time consumption. The harvester was a wheeled, three-axle Komatsu 911. A time study of 7.1 hours on 19 plots, with a total area of 0.76 ha was conducted. On average, the harvested tree volume was 8 dm³ and the stand density was 2666 trees/ha. The productivity was modelled with MTH conduction, mean diameter at breast height and the number of trees handled per cycle as independent variables. On average, MTH took 27% longer per cycle, increased extracted volume per cycle by 33% and consequently increased productivity with 5.0%. In 71.9% of the cycles more than one tree was handled and if so, dimensions were smaller than in single-tree handling (5.8 cm vs. 12.0 cm). Maximum felling diameter of 23 cm was about 15% smaller than in softwood (according to the manufacturer's specifications) and the driver didn't exploit the EF28's theoretical potential in terms of trees handled per cycle. It can be concluded that the head could significantly improve productivity in small-diameter wood procurement.

Abstract:The objective of this case study was to develop and test a specific survey protocol for monitoring tensile forces for winch-assisted harvesters and forwarders with a mounted or integrated constant-pull capstan winch technology. Based on the designed survey protocol, the interactions between work phases, machine inclination, and tensile forces in typical work conditions were analysed. The established workflow, including equipment and the developed analysis routines, worked appropriately and smoothly. The working load on the cable during the study did not exceed 50% of the maximum breaking strength. A maximum tensile force peak at 56 kN was observed during delays for the forwarder, and a peak of 75.5 kN was observed for the harvester, both of which are still within the safe working load when considering a safety factor of two.

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Digital transformation of the timber supply chain is more relevant at present than ever before. Timber tracking is one example of digital transformation, and can be performed in various locations, from the forest to the mill, or even beyond, to the final timber product. The integration of new technologies in the forestry and timber industries should contribute to enhancing supply chain efficiency and safety. For this purpose, a new timber tracking and processing system was tested by integrating RFID (Radio Frequency IDentification) technology with digital survey tools and intelligent machines, into a smart timber supply chain. A case study on this process was carried out in a mountain forest in Austria. The tags were used to link information to single items (trees and logs) and transfer relevant data (species, diameter, length, volume, defects, density, stiffness, branchiness, etc.), throughout the whole supply chain. The performance of the technology was analyzed by means of process flow, bottleneck, and risk analyses. Fourteen spruce trees went through the supply chain process from the forest stand to the log yard, monitored by the new timber tracking and processing system. The results revealed that the new system is useful for transferring information through the timber supply chain, and the system costs remained at a normal market level. The weakest point in the supply chain was the processing of the trees by the intelligent prototype processor. A high error rate and low durability lead to higher idling time and harvesting cost, but the findings of this study can be used to further improve this system. All other processes worked well and were at a marketable level.

Abstract:In Central Europe, full-tree (FT) harvesting is an increasingly common harvesting method in steep terrain harvesting due to the increased use of highly economical processor tower yarders. In conventional FT harvesting, nutrient removal from harvest sites is substantially higher than in cut-to-length (CTL) harvesting due to the extraction of nutrient-rich branches and foliage. One strategy to reduce the adverse impact of FT harvesting is to cut off the tops of felled trees prior to extraction (topping). The purpose of this study was to assess the effect of implementing topping treatments in FT harvesting on biomass and nutrient removal. The effect of conventional FT harvesting on the amount of logging residues left on the site was assessed in three different Norway spruce (Picea abies)-dominated stands following cable yarding operations by collecting logging residues from the forest floor. The additional effect of topping trees on the amount of logging residues was assessed by using biomass models. These models were created based on the data of 25 sample trees, which were felled and sampled destructively within the stands. The results show that conventional FT harvesting considerably increases nutrient removal in comparison to CTL, but still do not remove all nutrients from the sites. After conventional FT harvesting, 5-18% of the nutrients remained on the sites. Topping trees at a diameter of 8 cm substantially increased the amount of remaining nutrients to 30-34%.