Uppsala, Sweden
Uppsala, Sweden

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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 | Year: 2013

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.

Spinelli R.,CNR Tree and Timber Institute | Eliasson L.,Skogforsk | Magagnotti N.,CNR Tree and Timber Institute
Fuel Processing Technology | Year: 2016

Latest chipper models feature new in-feed and evacuation systems that can be adjusted on the fly to match variable work conditions. Proper adjustments of the two systems are expected to produce significant effects in terms of productivity, diesel fuel consumption and chip quality. The study verified such claims by testing one of these new machines in a controlled experiment, conducted under two alternative in-feed and evacuation system settings on two different feedstock types (2 × 2 × 2 = 8 treatment combinations). Each treatment was repeated 5 to 10 times, depending on feedstock availability. The study showed that feedstock type has a dominant effect on all the studied parameters, whereas in-feed mode has no effect on any of them. In contrast, blower setting has a significant effect and offers a strong potential for increased wood fuel processing efficiency. In particular, decreasing blower speed when full ejection power is not necessary allows reducing diesel fuel consumption between 6 and 16%, while increasing chip integrity by 20%. © 2016 Elsevier B.V. All rights reserved.

Edlund J.,Sveaskog AB | Bergsten U.,Swedish University of Agricultural Sciences | Lofgren B.,Skogforsk
Journal of Terramechanics | Year: 2012

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.

Jacobson S.,Skogforsk | Pettersson F.,Skogforsk
Silva Fennica | Year: 2010

In 1981-82 three field experiments were established with the aim of elucidating (i) the growth response of middle-aged coniferous stands at different fertilization intensities and, hence, the economic outcomes; and (ii) the need to add nutrients other than nitrogen (N). Nutrient additions were performed at intervals of two, four, six and eight years. The experiments were established on typical podzolized and N-limited mor-humus sites, two in Scots pine (Pinus sylvestris L.) stands and one in a Norway spruce (Picea abies (L.) Karst.) stand, at three different locations in Sweden. The ages of the stands were 65-70 years at the time of establishment. Growth responses were calculated after a 22-year study period. The growth responses were significant in all treatments. The addition of nutrients other than N did not affect stem growth at any of the sites. The growth response tended to increase with decreasing application interval. The results also revealed that the efficiency of fertilization is reduced as the interval between fertilizations is shortened. Accordingly, the growth effect per kg of added N was negatively correlated to fertilization intensity. The least intensive fertilization regime (an eight-year interval) resulted in an average net increase in C sequestration of 35 kg per kg N added. The profitability, in terms of internal rate of return, the present net value at different interest rates and the cost of production, i.e. the cost to produce one extra m3 under the different N regimes, are presented and discussed.

Oliva J.,Swedish University of Agricultural Sciences | Thor M.,Skogforsk | Stenlid J.,Swedish University of Agricultural Sciences
Canadian Journal of Forest Research | Year: 2010

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.

Launiainen S.,Finnish Forest Research Institute | Futter M.N.,Swedish University of Agricultural Sciences | Ellison D.,Hungarian Academy of Sciences | Clarke N.,Norwegian Forest And Landscape Institute | And 4 more authors.
Ambio | Year: 2014

The water footprint by the Water Footprint Network (WF) is an ambitious tool for measuring human appropriation and promoting sustainable use of fresh water. Using recent case studies and examples from water-abundant Fennoscandia, we consider whether it is an appropriate tool for evaluating the water use of forestry and forest-based products. We show that aggregating catchment level water consumption over a product life cycle does not consider fresh water as a renewable resource and is inconsistent with the principles of the hydrologic cycle. Currently, the WF assumes that all evapotranspiration (ET) from forests is a human appropriation of water although ET from managed forests in Fennoscandia is indistinguishable from that of unmanaged forests. We suggest that ET should not be included in the water footprint of rain-fed forestry and forestbased products. Tools for sustainable water management should always contextualize water use and water impacts with local water availability and environmental sensitivity. © Royal Swedish Academy of Sciences 2013.

Nati C.,CNR Tree and Timber Institute | Eliasson L.,Skogforsk | Spinelli R.,CNR Tree and Timber Institute
Croatian Journal of Forest Engineering | Year: 2014

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.

Futter M.N.,Swedish University of Agricultural Sciences | Ring E.,Skogforsk | Hogbom L.,Skogforsk | Entenmann S.,Albert Ludwigs University of Freiburg | Bishop K.H.,Swedish University of Agricultural Sciences
Environmental Pollution | Year: 2010

Short-term increases in soil solution nitrate (NO3 -) concentration are often observed after forest harvest, even in N-limited systems. We model NO3 - leaching below the rooting zone as a function of site productivity. Using national forest inventories and published estimates of N attenuation in rivers and the riparian zone, we estimate effects of stem-only harvesting on NO3 - leaching to groundwater, surface waters and the marine environment. Stem-only harvesting is a minor contributor to NO3 - pollution of Swedish waters. Effects in surface waters are rapidly diluted downstream, but can be locally important for shallow well-waters as well as for the total amount of N reaching the sea. Harvesting adds approximately 8 Gg NO3-N to soil waters in Sweden, with local concentrations up to 7 mg NO3-N l-1. Of that, ∼3.3 Gg reaches the marine environment. This is ∼3% of the overall Swedish N load to the Baltic. © 2010 Published by Elsevier Ltd. All rights reserved.

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 | Year: 2012

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.

Oliva J.,Swedish University of Agricultural Sciences | Thor M.,Skogforsk | Stenlid J.,Swedish University of Agricultural Sciences
Forest Ecology and Management | Year: 2010

Norway spruce (Picea abies) trees infected by Heterobasidion annosum s.l. decrease their periodic increment after a long period of time. Periodic increment decrease hypothetically relates to the formation of a reaction zone in order to prevent fungal colonisation. We studied 11 stands in Sweden, where we compared the periodic increment of healthy, rotten- and H. annosum-infected trees growing on plots thinned in winter, unthinned or thinned in summer, with and without urea or P. gigantea treatment of the stumps. Based on the rot incidence and the population structure of H. annosum of the plots, two phases of infection were considered: > 13 years and < 13 years. The presence of reaction zone and decay was observed on wood cores extracted with an increment borer. Rotten and H. annosum-infected trees with reaction zones exhibited a lower periodic increment than healthy trees (13.0% and 12.5% losses in terms of diameter, respectively), while no differences were observed between healthy trees and rotten and H. annosum-infected trees without reaction zone. Our results support the hypothesis of a periodic increment decrease in individual trees due to photosynthate re-allocation resulting from decay compartmentalization. Periodic increment decrease was only evident in trees that had been infected for more than 13 years. Trees in urea-treated plots registered a higher periodic increment, suggesting a possible response of trees to the nitrogen addition of the urea treatment of the stumps. © 2010 Elsevier B.V.

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