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Uppsala, Sweden

Edlund J.,Sveaskog AB | Bergsten U.,Swedish University of Agricultural Sciences | Lofgren B.,Skogforsk
Journal of Terramechanics

Impact of two different forwarders, with similar carrying capacities but different transmission drive and steering systems, on rut formation was compared. El-forest F15 with three individual steerable axles without bogies, large wheels (∅164 cm) and an electric hybrid transmission drive system, and a Valmet 860, with conventional transmission drive (∅131 cm wheels, two bogies) were compared. The ruts from the El-forest with or without a load were generally deeper than those produced by the tracked Valmet when driving in a straight line on soft arable land. On an S-shaped or circular course the El-forest and Valmet produced the same rut depths after the first pass, but with an increasing number of passes, the Valmet made deeper ruts. On the intermediate forest land, after driving in a straight line, the El-forest generally produced shallower ruts than the non-tracked Valmet (tracks not used at this site). When driving on a circular course, this difference was also apparent when machines carried a load. The mean rut width created by the El-forest was significantly narrower than from the Valmet at both sites. A transmission drive system with axles and wheels that can be individually steered seems advantageous to reduce rut formation, especially if the wheels have reduced ground pressure on soft soils. © 2012 ISTVS. Published by Elsevier Ltd. All rights reserved. Source

Oliva J.,Swedish University of Agricultural Sciences | Thor M.,Skogforsk | Stenlid J.,Swedish University of Agricultural Sciences
Canadian Journal of Forest Research

Airborne Heterobasidion annosum (Fr.) Bref. sensu lato infections can be controlled by winter thinning or by mechanically spreading urea or Phlebiopsis gigantea (Fr.) Julich spores on stump surfaces during summer thinning operations. The long-term outcomes of these control methods when applied as part of the conventional forest operations are unclear. We studied the rot incidence and population structure of H. annosum in plots of Picea abies (L.) Karst. thinned in winter or thinned in summer with and without treatment of the stumps. Plots were distributed among 11 stands in Sweden representing two different land use histories: forest and agricultural. After 13 years, the effect of stump treatment on rot incidence was only evident in stands on former agricultural land. In stands planted on former forest land with higher levels of preexisting rot than on former agricultural land, the expansion of preexisting genets of H. annosum might have masked the effects of stump protection. In former forest land, unprotected summer plots showed a greater diversity of H. annosum genotypes and a smaller number of trees infected by each genet than in protected plots, suggesting that protection treatments prevented the establishment of new genets, which may result in a reduced rot incidence in the future. Source

Spinelli R.,CNR Tree and Timber Institute | Cavallo E.,CNR Tree and Timber Institute | Eliasson L.,Skogforsk | Facello A.,CNR Tree and Timber Institute
Silva Fennica

The study compared the effect of chipper type on productivity, power demand, fuel consumption and product quality. Tests were conducted on two commercial chipper models, a disc and a drum chipper. Both chippers had the same diameter capacity, were applied to the same tractor and fed with the same feedstock types. Fifteen replications were conducted per machine and for each of four different feedstock types, reaching a total of 120 tests. The disc chipper had a higher energy efficiency and used 19% less fuel per unit product, possibly due to its simpler design, integrating comminuting and discharge system in one synergic device. In contrast, the drum chipper was 8% more productive, since it cut with the same energy all along the length of its knives. The drum chipper produced smaller chips, with a higher incidence of fines. Feedstock type had a strong effect on productivity, energy efficiency and product quality. The effect of feedstock type was mainly related to piece size, and may be stronger than the effect of chipper type. Further studies should determine the effect of blade wear on the relative performance of the two chipper types. Source

Nati C.,CNR Tree and Timber Institute | Eliasson L.,Skogforsk | Spinelli R.,CNR Tree and Timber Institute
Croatian Journal of Forest Engineering

The study determined the time consumption, fuel consumption and chip size obtained with two different industrial chippers, working with logging residues (tops and branches), thinning material and pulpwood. Specific time consumption per oven dry tons (odt) was 83% higher for the less powerful disc chipper, and chipping forest residues resulted in a 35% increase in specific time consumption compared to chipping thinning material. What is more, the interaction between the two factors pointed at a different suitability of the two machines to chip different materials, since the difference in specific time consumption between the drum and the disc chipper was larger when chipping forest residues rather than thinning. Specific time and fuel consumption of the more powerful drum chipper increased by 30% and 39%, respectively, when working with dull blades compared to working with sharp blades. The best product quality was obtained when applying the disc chipper to pulpwood material. However, the same machine produced more fines when fed with forest residues. Source

Paivinen R.,European forest Institute | Lindner M.,European forest Institute | Rosen K.,Skogforsk | Lexer M.J.,University of Natural Resources and Life Sciences, Vienna
European Journal of Forest Research

Due to the emerging importance of sustainable use of natural resources, and policies requiring actions towards sustainable development, there is a demand for methodologies and tools that are able to address these new challenges. In this paper, an approach to assess sustainability impacts of alternative production chains of the forest sector is presented. The approach, which is designed for both public and private decision-makers, describes the forest sector as a set of processes by which forest resources are used to (1) produce biomass which is routed through different value-adding production chains and converted to products and (2) provide other ecosystem services. It is suggested that each production process included in a production chain will be characterised by a set of indicators covering environmental, economic and social aspects of sustainable development. The approach is demonstrated by a numerical example, in which the indicator values are determined based on the volume of wood material flowing through the processes. Sustainability impacts of policy scenarios or technological changes result from changing from one production chain to another; the impacts accumulate along the production chains. Combined cost-benefit and multi-criteria analyses are proposed to evaluate overall impacts and to compare alternative chains. © 2010 Springer-Verlag. Source

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