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Articles containing the keyword 'energy'.

Category: Research article

article id 10379, category Research article
Juha Laitila, Kari Väätäinen. (2020). Productivity of harvesting and clearing of brushwood alongside forest roads. Silva Fennica vol. 54 no. 5 article id 10379. https://doi.org/10.14214/sf.10379
Highlights: The results can be used as a basis to determine in what kinds of cases brushwood biomass should be recovered and where it should be left to decay; The average volume of harvested brushwood and forwarding distance are the key elements to harvesting productivity with a harwarder; Stump diameter has a strong impact on clearing productivity of brushwood.

Expertise in the cost-efficient utilization and treatment of brushwood on forest roadside sites is limited. In the present study, the productivity of brushwood clearing and harvesting on forest roadside sites was defined by creating time-consumption models or parameters for the aforementioned working methods. Compiled time consumption models and parameters for the brushwood clearing and harvesting can be used as a basis for evaluating alternative management practices and to determine when brushwood biomass should be harvested and when it should be left to decay. The harvesting of brushwood was based on the harwarder system and the clearing of brushwood was done with a spiral cutter, which is a novel accessory for cutting roadside vegetation. Based on the study results, the average volume of harvested brushwood and forwarding distance are the key elements that have an effect on harvesting productivity with harwarders. Correspondingly, stump diameter has a strong impact on the clearing productivity of brushwood. The plot-wise productivity of the spiral cutter in brushwood clearings varied in the range of 0.19–0.61 ha per PMh. An increase in stump diameter slowed down the clearing productivity of the spiral cutter and there was a clear step downward in clearing productivity as the average diameter increased from 30 mm to 40 mm. The machinery under study operated well and there were no interruptions due to machine breakdowns.

  • Laitila, Natural Resources Institute Finland (Luke), Production systems, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: juha.laitila@luke.fi (email)
  • Väätäinen, Natural Resources Institute Finland (Luke), Production systems, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: kari.vaatainen@luke.fi
article id 10147, category Research article
Mika Aalto, Olli-Jussi Korpinen, Tapio Ranta. (2019). Feedstock availability and moisture content data processing for multi-year simulation of forest biomass supply in energy production. Silva Fennica vol. 53 no. 4 article id 10147. https://doi.org/10.14214/sf.10147
Highlights: A method for allocating forest biomass availability for a multi-year simulation model was developed; The possibility to take the quality change of feedstock into account by moisture estimations was studied; A method to estimate weather data for moisture estimation equations with fewer parameters was presented.

Simulation and modeling have become more common in forest biomass studies. Dynamic simulation has been used to study the supply chain of forest biomass with numerous different models. A robust predictive multi-year model requires biomass availability data, where annual variation is included spatially and temporally. This can be done by using data from enterprises, but in some cases relevant data is not accessible. Another option is to use forest inventory data to estimate biomass availability, but this data must be processed in the correct form to be utilized in the model. This study developed a method for preparing forest inventory data for a multi-year simulation supply model using the theoretical availability of feedstock. Methods for estimating quality changes during roadside storage are also presented, including a possible parameter estimation to decrease the amount of data needed. The methods were tested case by case using the inventory database “Biomass Atlas” and weather data from a weather station in Mikkeli, Finland. The data processing method for biomass allocation produced a reasonable quantity of stands and feedstock, having a realistic annual supply with variation for the demand point. The results of the study indicate that it is possible to estimate moisture content changes using weather data. The estimations decreased the accuracy of the model and, therefore, estimations should be kept minimal. The presented data preparation method can generate a supply of forest biomass for the simulation model, but the validity of the data must be ensured for correct model behavior.

  • Aalto, Lappeenranta-Lahti University of Technology LUT, School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland ORCID ID: https://orcid.org/0000-0002-7768-1145 E-mail: mika.aalto@lut.fi (email)
  • Korpinen, Lappeenranta-Lahti University of Technology LUT, School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland ORCID ID:E-mail: olli-jussi.korpinen@lut.fi
  • Ranta, Lappeenranta-Lahti University of Technology LUT, School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland ORCID ID: https://orcid.org/0000-0001-5464-5136 E-mail: tapio.ranta@lut.fi
article id 9902, category Research article
Perttu Anttila, Vesa Nivala, Olli Salminen, Markus Hurskainen, Janne Kärki, Tomi J. Lindroos, Antti Asikainen. (2018). Regional balance of forest chip supply and demand in Finland in 2030. Silva Fennica vol. 52 no. 2 article id 9902. https://doi.org/10.14214/sf.9902
Highlights: The impact of increasing forest chip demand in 2030 was analyzed in Finland; Demand of small trees may exceed potential at the national level; Surplus potential will remain in logging residues and stumps; Hot spots of demand call for efficient logistical solutions.

According to the National Energy and Climate Strategy of Finland in 2016, the demand for forest chips, that is, wood chips made of forest biomass directly for energy use, could even double by 2030 compared to the present situation. A spatially explicit impact analysis of regional supply and demand balances for forest chips was carried out. The balances were calculated as the difference between technical harvesting potentials and demand. First, the technical potentials were estimated based on the national forest inventory data. Secondly, three demand scenarios were defined for 2030 and subsequently deducted from the potentials. The results suggested that there would be increasing competition for feedstock in southern and western Finland, whereas in eastern and northern Finland there would still be surplus potential. Moreover, due to the remarkable deficit of small trees in southern Finland, there might be pressure towards using more pulpwood-sized and/or imported wood in energy production. The results also showed that, in particular, large new plants consuming substantial amounts of forest chips could have a significant effect on the regional availability of forest chips. Moreover, with increasing transport distances, new logistical solutions will be needed.

  • Anttila, Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID: http://orcid.org/0000-0002-6131-392X E-mail: perttu.anttila@luke.fi (email)
  • Nivala, Natural Resources Institute Finland (Luke), Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: vesa.nivala@luke.fi
  • Salminen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID:E-mail: olli.salminen@luke.fi
  • Hurskainen, VTT Technical Research Centre of Finland Ltd, Koivurannantie 1, FI-40400 Jyväskylä, Finland ORCID ID:E-mail: markus.hurskainen@vtt.fi
  • Kärki, VTT Technical Research Centre of Finland Ltd, Koivurannantie 1, FI-40400 Jyväskylä, Finland ORCID ID:E-mail: janne.karki@vtt.fi
  • Lindroos, VTT Technical Research Centre of Finland Ltd, Vuorimiehentie 3 (Espoo), P.O. Box 1000, FI-02044 VTT, Finland ORCID ID:E-mail: tomi.j.lindroos@vtt.fi
  • Asikainen, Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: antti.asikainen@luke.fi
article id 9902, category Research article
Perttu Anttila, Vesa Nivala, Olli Salminen, Markus Hurskainen, Janne Kärki, Tomi J. Lindroos, Antti Asikainen. (2018). Regional balance of forest chip supply and demand in Finland in 2030. Silva Fennica vol. 52 no. 2 article id 9902. https://doi.org/10.14214/sf.9902
Highlights: The impact of increasing forest chip demand in 2030 was analyzed in Finland; Demand of small trees may exceed potential at the national level; Surplus potential will remain in logging residues and stumps; Hot spots of demand call for efficient logistical solutions.

According to the National Energy and Climate Strategy of Finland in 2016, the demand for forest chips, that is, wood chips made of forest biomass directly for energy use, could even double by 2030 compared to the present situation. A spatially explicit impact analysis of regional supply and demand balances for forest chips was carried out. The balances were calculated as the difference between technical harvesting potentials and demand. First, the technical potentials were estimated based on the national forest inventory data. Secondly, three demand scenarios were defined for 2030 and subsequently deducted from the potentials. The results suggested that there would be increasing competition for feedstock in southern and western Finland, whereas in eastern and northern Finland there would still be surplus potential. Moreover, due to the remarkable deficit of small trees in southern Finland, there might be pressure towards using more pulpwood-sized and/or imported wood in energy production. The results also showed that, in particular, large new plants consuming substantial amounts of forest chips could have a significant effect on the regional availability of forest chips. Moreover, with increasing transport distances, new logistical solutions will be needed.

  • Anttila, Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID: http://orcid.org/0000-0002-6131-392X E-mail: perttu.anttila@luke.fi (email)
  • Nivala, Natural Resources Institute Finland (Luke), Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: vesa.nivala@luke.fi
  • Salminen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID:E-mail: olli.salminen@luke.fi
  • Hurskainen, VTT Technical Research Centre of Finland Ltd, Koivurannantie 1, FI-40400 Jyväskylä, Finland ORCID ID:E-mail: markus.hurskainen@vtt.fi
  • Kärki, VTT Technical Research Centre of Finland Ltd, Koivurannantie 1, FI-40400 Jyväskylä, Finland ORCID ID:E-mail: janne.karki@vtt.fi
  • Lindroos, VTT Technical Research Centre of Finland Ltd, Vuorimiehentie 3 (Espoo), P.O. Box 1000, FI-02044 VTT, Finland ORCID ID:E-mail: tomi.j.lindroos@vtt.fi
  • Asikainen, Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: antti.asikainen@luke.fi
article id 7830, category Research article
Jari Lindblad, Johanna Routa, Johanna Ruotsalainen, Marja Kolström, Ari Isokangas, Lauri Sikanen. (2018). Weather based moisture content modelling of harvesting residues in the stand. Silva Fennica vol. 52 no. 2 article id 7830. https://doi.org/10.14214/sf.7830
Highlights: Weather data used for estimating the moisture content of energy wood; The validation of the weather based models performed based on the field data.

Harvesting residues collected from the final cuttings of boreal forests are an important source of solid biofuel for energy production in Finland and Sweden. In the Finnish supply chain, the measurement of residues is performed by scales integrated in forwarders. The mass of residues is converted to volume by conversion factors. In this study, weather based models for defining the moisture content of residues were developed and validated. Models were also compared with the currently used fixed tables of conversion factors. The change of the moisture content of residues is complex, and an exact estimation was challenging. However, the model predicting moisture change for three hour periods was found to be the most accurate. The main improvement compared to fixed tables was the lack of a systematic error. It can be assumed that weather based models will give more reliable estimates for the moisture in varying climate conditions and the further development of models should be focused on obtaining more appropriate data from varying drying conditions in different geographical and microclimatological locations.

  • Lindblad, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: jari.lindblad@luke.fi (email)
  • Routa, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: johanna.routa@luke.fi
  • Ruotsalainen, Finnish Meteorological Institute, Aviation and Military Weather Services, P.O. Box 1627, FI-70211 Kuopio, Finland ORCID ID:E-mail: johanna.ruotsalainen@fmi.fi
  • Kolström, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: marja.kolstrom@uef.fi
  • Isokangas, University of Oulu, Control Engineering, P.O. Box 8000, FI-90014 University of Oulu, Finland ORCID ID:E-mail: ari.isokangas@oulu.fi
  • Sikanen, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: lauri.sikanen@luke.fi
article id 2017, category Research article
Pentti Niemistö, Soili Kojola, Anssi Ahtikoski, Raija Laiho. (2017). From useless thickets to valuable resource? – Financial performance of downy birch management on drained peatlands. Silva Fennica vol. 51 no. 3 article id 2017. https://doi.org/10.14214/sf.2017
Highlights: The most profitable management regimes for pulpwood and energy wood production in dense downy birch stands on drained peatlands include no thinnings, but final cutting at the stand age of 40–45 years as whole-tree harvesting, or as integrated harvesting of pulpwood and delimbed energy wood stems about 10 years later depending on applicable harvesting method; A competitive management regime is early precommercial thinning at 4 m dominant height to a density of 2500 stems per hectare and production of pulpwood with a rotation of 55–65 years. Equal profitability is achieved with or without traditional first thinning, which can thus be included for other reasons, for example to improve regeneration of spruce.

Downy birch (Betula pubescens Ehrh.) stands on drained peatlands are often considered useless because they typically do not yield good-quality sawn timber. However, covering an area of ca. 0.5 million hectares and with total yields of up to 250 m3 ha–1, downy birch stands on peatlands in Finland have a potential for pulpwood and/or energy wood production. We examined the financial performance of alternative management regimes (with or without thinnings, different thinning intensities, several rotation lengths) combined with alternative harvesting methods (pulpwood, energy wood, or integrated, energy wood being delimbed stems or whole trees). We used data from 19 experimental stands, monitored for 20–30 years. For harvesting removals we considered both actual thinning removals and final-cutting removals with alternative timings that were based on the monitoring data. We assessed the profitability as a combination of the net present value of the birch generation and the bare land value of future generations of Norway spruce (Picea abies (L.) Karst.). The most profitable management was growing without thinnings until whole-tree final cutting at the stand age of 40–45 years with an advanced multi-tree harvesting method. In contrast, the standard method in whole-tree final cutting resulted in the lowest profitability, and an integrated method with the energy wood as delimbed stems was the best of the standard methods. Thinnings were unprofitable especially when aiming to produce energy wood, whereas aiming for pulpwood, light precommercial thinning was competitive. Commercial thinning at the traditional “pulpwood stage” had little effect on profitability. The best stand age for final cutting was 40–65 years – earlier for very dense stands and whole-tree energy wood harvesting with advanced method, later for precommercially thinned stands and pulpwood harvesting.

  • Niemistö, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Kampusranta 9 C, 60320 Seinäjoki, Finland ORCID ID:E-mail: pentti.niemisto@luke.fi (email)
  • Kojola, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Latokartanonkaari 9, 00790 Helsinki, Finland ORCID ID:E-mail: soili.kojola@luke.fi
  • Ahtikoski, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Paavo Havaksentie 3, 90014 University of Oulu, Finland ORCID ID:E-mail: anssi.ahtikoski@luke.fi
  • Laiho, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Latokartanonkaari 9, 00790 Helsinki, Finland ORCID ID:E-mail: raija.laiho@luke.fi
article id 1521, category Research article
Kalle Karttunen, Juha Laitila, Tapio Ranta. (2016). First-thinning harvesting alternatives for industrial or energy purposes based on regional Scots pine stand simulations in Finland. Silva Fennica vol. 50 no. 2 article id 1521. https://doi.org/10.14214/sf.1521
Highlights: Small-diameter delimbed wood from Scots pine stands delivered directly for energy use was the most cost-efficient option in terms of the total supply-chain cost in comparison with corresponding industrial use or a whole-tree supply chain for energy use; Forest-management and harvesting decisions influenced the removal of forest biomass and stumpage price as well as the total supply-chain costs for forest biomass; The greatest cost-reduction potential (10.0%, 4.00 € m–3) was achieved for the delimbed energy wood’s supply chain in the regional case of South Savo in eastern Finland.

Combining research into forest management stand conditions and wood supply chain processes has been missing from earlier forestry studies. There is a clear need to develop more cost-efficient small-diameter wood production, harvesting and transportation methods from first thinning, which could be used for either industrial or energy wood purposes. This study considers the total cost for small-diameter wood originating from young Scots pine (Pinus sylvestris L.) dominated stands. Pine pulpwood is the most harvested and most used roundwood assortment, use of which is expected to rise following new pulp-mill investments in Finland. In addition, utilisation of small-diameter trees directly for energy purposes has been increasing steadily in recent years. The aim of the study was to determine the cost-reduction potential of alternative forest management options and supply chains for small diameter-wood in the regional case of South Savo in eastern Finland. The total costs of three distinct scenarios were studied on the basis of forest management, first-thinning harvesting methods, and transportation: 1) industrial wood, 2) delimbed energy wood, and 3) whole trees for energy purposes. The cost-reduction potential for energy-wood supply chains from first thinning was compared to the industrial supply chain. Small-diameter delimbed wood delivered straight for energy purposes was found to be the most cost-efficient as far as the total cost of the supply chain is concerned. More cost-efficient small-diameter wood processes can be found by linking forest stand simulations with supply chain analysis.

  • Karttunen, Lappeenranta University of Technology, LUT School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland ORCID ID:E-mail: kalle.karttunen@lut.fi
  • Laitila, Natural Resources Institute Finland (Luke), Bio-based business and industry, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: juha.laitila@luke.fi
  • Ranta, Lappeenranta University of Technology, LUT School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland ORCID ID:E-mail: tapio.ranta@lut.fi (email)
article id 1428, category Research article
Gernot Erber, Franz Holzleitner, Maximilian Kastner, Karl Stampfer. (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. https://doi.org/10.14214/sf.1428
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.

Early 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.

  • Erber, Addresses University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, Institute of Forest Engineering, Peter-Jordan Straße 82/3, A-1190 Vienna, Austria ORCID ID:E-mail: gernot.erber@boku.ac.at (email)
  • Holzleitner, Addresses University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, Institute of Forest Engineering, Peter-Jordan Straße 82/3, A-1190 Vienna, Austria ORCID ID:E-mail: franz.holzleitner@boku.ac.at
  • Kastner, Addresses University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, Institute of Forest Engineering, Peter-Jordan Straße 82/3, A-1190 Vienna, Austria ORCID ID:E-mail: maximilian.kastner@boku.ac.at
  • Stampfer, Addresses University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, Institute of Forest Engineering, Peter-Jordan Straße 82/3, A-1190 Vienna, Austria ORCID ID:E-mail: karl.stampfer@boku.ac.at
article id 1377, category Research article
Raul Fernandez-Lacruz, Fulvio Di Fulvio, Dimitris Athanassiadis, Dan Bergström, Tomas Nordfjell. (2015). Distribution, characteristics and potential of biomass-dense thinning forests in Sweden. Silva Fennica vol. 49 no. 5 article id 1377. https://doi.org/10.14214/sf.1377
Highlights: Biomass-dense thinning forests (BDTF) cover 2.1–9.8 M ha in Sweden, which represents 9–44% of the country’s productive forest land area, depending on the constraints applied; 65% of BDTF area is found in northern Sweden; Analyses revealed a yearly harvesting potential of at least 4.3 M OD t of undelimbed whole trees (3.0 M OD t of delimbed stemwood including tops).

Understanding the characteristics of unutilized biomass resources, such as small-diameter trees from biomass-dense thinning forests (BDTF) (non-commercially-thinned forests), can provide important information for developing a bio-based economy. The aim of this study was to describe the areal distribution, characteristics (biomass of growing stock, tree height, etc.) and harvesting potential of BDTF in Sweden. A national forest inventory plot dataset was imported into a geographical information system and plots containing BDTF were selected by applying increasingly stringent constraints. Results show that, depending on the constraints applied, BDTF covers 9–44% (2.1–9.8 M ha) of the productive forest land area, and contains 7–34% of the total growing stock (119–564 M OD t), with an average biomass density of 57 OD t ha–1. Of the total BDTF area, 65% is located in northern Sweden and 2% corresponds to set-aside farmlands. Comparisons with a study from 2008 indicate that BDTF area has increased by at least 4% (about 102 000 ha), in line with general trends for Sweden and Europe. Analyses revealed that the technical harvesting potential of delimbed stemwood (over bark, including tops) from BDTF ranges from 3.0 to 6.1 M OD t yr–1 (7.5 to 15.1 M m3 yr–1), while the potential of whole-tree harvesting ranges from 4.3 to 8.7 M OD t yr–1 (10.2 to 20.6 M m3 yr–1) depending on the scenario considered. However, further technological developments of the harvest and supply systems are needed to utilize the full potential of BDTF.

  • Fernandez-Lacruz, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID: http://orcid.org/0000-0001-9284-8911 E-mail: raul.fernandez@slu.se (email)
  • Di Fulvio, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden; International Institute for Applied Systems Analysis (IIASA), Ecosystems Services and Management Program (ESM), Schlossplatz 1, A-2361 Laxenburg, Austria ORCID ID:E-mail: Fulvio.di.Fulvio@slu.se
  • Athanassiadis, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID:E-mail: Dimitris.Athanassiadis@slu.se
  • Bergström, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID:E-mail: Dan.Bergstrom@slu.se
  • Nordfjell, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID:E-mail: Tomas.Nordfjell@slu.se
article id 1347, category Research article
Paulo Borges, Even Bergseng, Tron Eid, Terje Gobakken. (2015). Impact of maximum opening area constraints on profitability and biomass availability in forestry – a large, real world case. Silva Fennica vol. 49 no. 5 article id 1347. https://doi.org/10.14214/sf.1347
Highlights: We solved a large and real world near city forestry problem; The inclusion of maximum open area constraints caused 7.0% loss in NPV; Solution value at maximum deviated 0.01% from the true optimum value; The annual energy supply of 20–30 GWh estimated from harvest residues could provide a small, but stable supply of energy to the municipality.

The nature areas surrounding the capital of Norway (Oslomarka), comprising 1 700 km2 of forest land, are the recreational home turf for a population of 1.2 mill. people. These areas are highly valuable, not only for recreational purposes and biodiversity, but also for commercial activities. To assess the impacts of the challenges that Oslo municipality forest face in their management, we developed four optimization problems with different levels of management constraints. The constraints consider control of harvest level, guarantee of minimum old-growth forest area and maximum open area after final harvest. For the latter, to date, no appropriate analyses quantifying the impact of such a constraint on economy and biomass production have been carried out in Norway. The problem solved is large due to both the number of stands and number of treatment schedules. However, the model applied demonstrated its relevance for solving large problems involving maximum opening areas. The inclusion of maximum open area constraints caused 7.0% loss in NPV compared to the business as usual case with controlled harvest volume and minimum old-growth area. The estimated supply of 20-30 GWh annual energy from harvest residues could provide a small, but stable supply of energy to the municipality.

  • Borges, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Aas, Norway ORCID ID:E-mail: paulo.borges@nmbu.no (email)
  • Bergseng, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Aas, Norway ORCID ID:E-mail: even.bergseng@nmbu.no
  • Eid, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Aas, Norway ORCID ID:E-mail: tron.eid@nmbu.no
  • Gobakken, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Aas, Norway ORCID ID:E-mail: terje.gobakken@nmbu.no
article id 1124, category Research article
Āris Jansons, Mārtiņš Zeps, Juris Rieksts-Riekstiņš, Roberts Matisons, Oskars Krišāns. (2014). Height increment of hybrid aspen Populus tremuloides x P. tremula as a function of weather conditions in central part of Latvia. Silva Fennica vol. 48 no. 5 article id 1124. https://doi.org/10.14214/sf.1124
Highlights: Intra-annual height growth of hybrid aspen was monitored; Clones with early leaf flushing dates showed faster height growth; Height growth was generally controlled by temperature; Fast-growing hybrids were more robust to weather conditions than slow-growing ones; Potential evapotranspiration (moisture regime) negatively affected height growth of clones with delayed phenology.
Height growth of young hybrid aspen (Populus tremula L. × P. tremuloides Michx.) was studied in relation to weather conditions. Height of clones with different leaf flushing phenology (early, intermediate and late) was monitored during the growing periods of 2010 and 2011 in a plantation established on former agricultural land. Mean daily height increment (HI) was calculated. Multiple linear regression was used to determine which weather factors (variables) had significant effect on HI. Mean seasonal height growth (mean seasonal HI) between clones (groups) was compared by ANOVA. In both years, HI was significantly higher for clones with early and intermediate leaf flushing compared to clones with late leaf flushing. The effect of weather factors also differed between clones according to their leaf flushing phenology; it was the weakest for HI of clones with early leaf flushing compared to clones with intermediate and late leaf flushing. Mean temperature was the main factor, which positively affected HI of all clones, suggesting that warmer climate might be beneficial for height growth of young hybrid aspen in Latvia. Nevertheless, significant negative relationship between HI and potential evapotranspiration (PET) was observed for clones with delayed leaf flushing, suggesting negative effect of increasing variability of precipitation on growth. Thus, the differences in height growth intensity might be related to growth sensitivity to weather conditions. On the other hand, such differences in height growth between clones might be caused by competition (i.e. with herbs), as trees with early leaf flushing might conquer more resources and become more robust against the environmental fluctuation.
  • Jansons, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: aris.jansons@silava.lv
  • Zeps, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: martins.zeps@silava.lv
  • Rieksts-Riekstiņš, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: Juris.Riekstins@silava.lv
  • Matisons, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: robism@inbox.lv (email)
  • Krišāns, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: oskars.krisans@silava.lv
article id 962, category Research article
Paul A. Klockow, Anthony W. D'Amato, John B. Bradford, Shawn Fraver. (2014). Nutrient concentrations in coarse and fine woody debris of Populus tremuloides Michx.-dominated forests, northern Minnesota, USA. Silva Fennica vol. 48 no. 1 article id 962. https://doi.org/10.14214/sf.962
Highlights: We examine effects of size, species, and decay on woody debris nutrient concentrations; Results indicate wide variation in nutrient concentrations across the factors examined; Fine woody debris nutrient concentrations were greater than in coarse woody debris; Coarse woody debris nutrient concentrations generally increased as decay progressed; Results suggest high fine woody debris stocks can represent an important nutrient source.
Contemporary forest harvesting practices, specifically harvesting woody biomass as a source of bioenergy feedstock, may remove more woody debris from a site than conventional harvesting. Woody debris, particularly smaller diameter woody debris, plays a key role in maintaining ecosystem nutrient stores following disturbance. Understanding nutrient concentrations within woody debris is necessary for assessing the long-term nutrient balance consequences of altered woody debris retention, particularly in forests slated for use as bioenergy feedstocks. Nutrient concentrations in downed woody debris of various sizes, decay classes, and species were characterized within one such forest type, Populus tremuloides Michx.-dominated forests of northern Minnesota, USA. Nutrient concentrations differed significantly between size and decay classes and generally increased as decay progressed. Fine woody debris (≤ 7.5 cm diameter) had higher nutrient concentrations than coarse woody debris (> 7.5 cm diameter) for all nutrients examined except Na and Mn, and nutrient concentrations varied among species. Concentrations of N, Mn, Al, Fe, and Zn in coarse woody debris increased between one and three orders of magnitude, while K decreased by an order of magnitude with progressing decay. The variations in nutrient concentrations observed here underscore the complexity of woody debris nutrient stores in forested ecosystems and suggest that retaining fine woody debris at harvest may provide a potentially important source of nutrients following intensive removals of bioenergy feedstocks.
  • Klockow, Department of Forest Resources, University of Minnesota, St. Paul, MN 55108, USA ORCID ID:E-mail: klock039@umn.edu (email)
  • D'Amato, Department of Forest Resources, University of Minnesota, St. Paul, MN 55108, USA ORCID ID:E-mail: damato@umn.edu
  • Bradford, US Geological Survey, Southwest Biological Science Center, Flagstaff, AZ 86001, USA ORCID ID:E-mail: jbradford@usgs.gov
  • Fraver, School of Forest Resources, University of Maine, Orono, ME 04469, USA ORCID ID:E-mail: shawn.fraver@maine.edu
article id 937, category Research article
Rene Zamora-Cristales, Kevin Boston, John Sessions, Glen Murphy. (2013). Stochastic simulation and optimization of mobile chipping economics in processing and transport of forest biomass from residues. Silva Fennica vol. 47 no. 5 article id 937. https://doi.org/10.14214/sf.937
Highlights: A stochastic simulation model is proposed to analyze forest biomass operations; The cost of chipper and truck waiting times was estimated in forest biomass recovery operations; The economic effect of truck-machine interactions under uncertainty was analyzed; Road characteristics and processing location have an economic impact in truck and chipper waiting times
We analyzed the economics of mobile chipping and transport of biomass from forest residues for energy purposes under uncertainty. A discrete-event simulation model was developed and utilized to quantify the impacts of controllable and environmental variables on productivity in order to determine the most cost effective transportation options under steep terrain conditions. Truck-chipper interactions were analyzed to show their effect on truck and chipper standing time. A costing model was developed to account for operating and standing time cost (for the chipper and trucks). The model used information from time studies of each activity in the productive cycle and spatial-temporal information obtained from geographic information system (GIS) devices, and tracking analysis of machine and truck movements. The model was validated in field operations, and proved to be accurate in providing the expected productivity. A cost distribution was elaborated to support operational decisions of forest managers, landowners and risk-averse contractors. Different scenarios were developed to illustrate the economic effects due to changes in road characteristics such as in-highway transport distance, in-forest internal road distance and pile to trailer chipper traveling distances.
  • Zamora-Cristales, Department of Forest Engineering, Resources, and Management, College of Forestry, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA ORCID ID:E-mail: rene.zamora@oregonstate.edu (email)
  • Boston, Department of Forest Engineering, Resources, and Management, College of Forestry, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA ORCID ID:E-mail: kevin.boston@oregonstate.edu
  • Sessions, Department of Forest Engineering, Resources, and Management, College of Forestry, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA ORCID ID:E-mail: john.sessions@oregonstate.edu
  • Murphy, Waiariki Institute of Technology, Rotorua, New Zealand ORCID ID:E-mail: glen.murphy@waiariki.ac.nz
article id 1022, category Research article
Eero Muinonen, Perttu Anttila, Jaakko Heinonen, Jukka Mustonen. (2013). Estimating the bioenergy potential of forest chips from final fellings in Central Finland based on biomass maps and spatially explicit constraints. Silva Fennica vol. 47 no. 4 article id 1022. https://doi.org/10.14214/sf.1022
The technical potential of forest chips from final fellings in Central Finland was estimated using a method based on biomass maps derived from a multi-source forest inventory technique. Image segmentation techniques were applied to a satellite image mosaic to detect stand boundaries. The technical potential of forest chips was computed based on primary forestry residues, i.e. logging residues and stumps from final fellings. Harvesting level definitions for final fellings were established using realized statistics for roundwood at the municipality level as well as larger area statistics. The sensitivity of the potential to ecological and technical constraints in the model was also examined. The technical recovery rate of stump harvesting according to biomass harvesting guidelines was evaluated separately. The critical prerequisites for using the advanced, spatially explicit approach to analysing forest energy potentials may lie in the existence of spatially explicit forest inventory data and the biometric models for tree biomass assortments. The method applied was capable of taking into account the constraints that rely upon map data, such the actual forwarding distance or steepness of the slope in the terrain. The calculation results can be used for strategic decision making in the field of forest bioenergy production.
  • Muinonen, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: eero.muinonen@metla.fi (email)
  • Anttila, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: perttu.anttila@metla.fi
  • Heinonen, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: jaakko.heinonen@metla.fi
  • Mustonen, Stora Enso, Talvikkitie 40 C, FI-01300 Vantaa, Finland ORCID ID:E-mail: jukka.mustonen@storaenso.com
article id 1002, category Research article
Pentti Niemistö. (2013). Effect of growing density on biomass and stem volume growth of downy birch stands on peatland in Western and Northern Finland. Silva Fennica vol. 47 no. 4 article id 1002. https://doi.org/10.14214/sf.1002
Highlights: The thinning response in young downy birch stands was low and the mortality of merchantable stems was tolerable even in dense unthinned thickets during the rotation of 50 years; The production of above-ground woody biomass and stem volume or even the production of pulpwood increased with stand density, with these values being greatest for unthinned or very lightly thinned plots.
The objective of the study was to ascertain the relationship of thinning intensity of downy birch (Betula pubescens Ehrh.) stands with height, crown, and diameter development as well as pulpwood, stem volume, and biomass increment using long-term (20−30 years) field experiments. Diameter growth of birches increased with thinning intensity during the first 15 years from thinning in all development phases, though after that it did so only for the youngest stands. The thinning response was low. Thinning intensity had no influence on increase in height. In terms of stem volume with bark, the mortality in unthinned stands during the study period was 30–45 m3 ha-1. The mean stem number in unthinned birch thickets fell from 25 000 ha-1 at a dominant height of 7 m to 3000 ha-1 at 18 m. The stem volume increment over the first 15 years was highest (5–6 m3 ha-1 a-1) on the very lightly thinned or unthinned plots, but later there was no significant difference between initial thinning intensities. The maximum above-ground leafless biomass (over 100 Mg ha-1) was achieved on very lightly thinned plots. Also, the total production (including thinning removal) of biomass or stem volume or even the production of pulpwood increased with stand density, with these values being greatest for very lightly thinned or unthinned plots. During 50-year rotation, the highest leafless above-ground biomass production was 2.5 Mg ha-1 a-1 as a mean value from the experiments. The highest mean annual production of pulpwood (d > 6.5 cm) was 3.2 m3 ha-1 a-1, and, in practice, no saw timber or veneer timber was produced, because of the small size and low quality of the stems. A thinning in downy birch stands increased slightly the size of stems to be removed in future cuttings, but with exception for very light thinning it decreased the production of biomass and merchantable wood.
  • Niemistö, Finnish Forest Research Institute, Parkano Unit, FI-39700 Parkano, Finland ORCID ID:E-mail: pentti.niemisto@metla.fi (email)
article id 930, category Research article
Raffaele Spinelli, Eugenio Cavallo, Lars Eliasson, Alessio Facello. (2013). Comparing the efficiency of drum and disc chippers. Silva Fennica vol. 47 no. 2 article id 930. https://doi.org/10.14214/sf.930
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, CNR IVALSA, Via Madonna del Piano 10, Sesto Fiorentino (FI), Italy ORCID ID:E-mail: spinelli@ivalsa.cnr.it (email)
  • Cavallo, CNR IVALSA, Via Madonna del Piano 10, Sesto Fiorentino (FI), Italy ORCID ID:E-mail: e.cavallo@imamoter.cnr.it
  • Eliasson, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail: lars.eliasson@skogforsk.se
  • Facello, CNR IVALSA, Via Madonna del Piano 10, Sesto Fiorentino (FI), Italy ORCID ID:E-mail: a.facello@ima.to.cnr.it
article id 86, category Research article
Mats Jonsell, Jesper Hansson. (2011). Logs and stumps in clearcuts support similar saproxylic beetle diversity: implications for bioenergy harvest. Silva Fennica vol. 45 no. 5 article id 86. https://doi.org/10.14214/sf.86
Stumps from clear cuts are increasingly used for bioenergy. Extracting this wood will reduce the habitat available for saproxylic (wood-living) organisms. As little is known about the species assemblages that will be affected, we investigated the diversity of saproxylic beetles in stumps on clear-felled sites and as a reference, we compared it with the diversity in downed logs. Stumps and logs of aspen (Populus tremula L.), birch (Betula pubescens Ehrh. and B. verrucosa Ehrh.[syn. B. pendula Roth]), spruce (Picea abies (L.) Karst.) and pine (Pinus sylvestris L.) were examined in clear cuts of two different ages: one summer old and 4–5 years old. The beetles were sampled by sieving bark (0.25 m2) peeled from the wood. The samples were taken in pairs of one log and one stump situated close together and of the same tree species, age since death and diameter. In total 3348 saproxylic beetles belonging to 124 species were found in 176 samples. The stumps had a similar number of species to the logs both as measured per sample and as an accumulated number. Exceptions were 4–5 years old wood of birch and pine where the number was significantly higher in the stumps. The number of red-listed species was also similar between stumps and logs. Species composition was more different between the stumps and logs of conifers than of deciduous trees. We conclude that clear-felled stumps have a diverse saproxylic insect fauna. This has to be taken into account if large scale extraction of logging stumps is implemented.
  • Jonsell, Swedish University of Agrarian Sciences, Dept of Ecology, Uppsala, Sweden ORCID ID:E-mail: mats.jonsell@ekol.slu.se (email)
  • Hansson, Swedish University of Agrarian Sciences, Dept of Ecology, Uppsala, Sweden ORCID ID:E-mail:
article id 135, category Research article
Ola Lindroos, Marina Henningsson, Dimitris Athanassiadis, Tomas Nordfjell. (2010). Forces required to vertically uproot tree stumps. Silva Fennica vol. 44 no. 4 article id 135. https://doi.org/10.14214/sf.135
Stumpwood attracts renewed interest due to increased use of forest biomass for bioenergy. In Nordic countries stumps are generally uprooted with crawler excavators, which have strong cranes (ca. 400 kNm gross lift torque), but are not designed for moving in forest terrain. Their use is based on practical experience with available and tested machine types rather than thorough examinations of requirements, partly due to limited knowledge of force requirements for uprooting of stumps. Therefore, in this work mean and maximum forces required to vertically uproot stumps of Norway spruce (Picea abies) and birch (Betula spp.) were quantified together with the effects of various soil types and uprooting methods. The used excavator’s crane-mounted uprooting device enabled comparisons between usage of solely crane force, and a method in which preparatory loosening forces were applied prior to crane force. Uprooting stumps in single pieces proved difficult; 61% split unintentionally. Force requirements were similar across tree species, increasing curve-linearly with stump diameter, and stumps uprooted in a single piece required more force than split stumps. Preparatory loosening reduced crane force requirements and, surprisingly, less force was required to uproot stumps from a mesic, till soil than from a moist, finer-textured soil. No stump required more than 60 kN crane force and functions for maximum force requirements indicate that powerful harvesters and forwarders (gross crane lifting capacity of 273 and 155 kNm, respectively) should be able to uproot all stumps with ≤ 61 cm and ≤ 32 cm diameter, respectively, in one piece. Larger stumps could be managed if it is acceptable that stumps are split before uprooting.
  • Lindroos, Department of Forest Resource Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden ORCID ID:E-mail: ola.lindroos@srh.slu.se (email)
  • Henningsson, Komatsu Forest AB, Box 7124, SE-907 04 Umeå, Sweden ORCID ID:E-mail:
  • Athanassiadis, Department of Forest Resource Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Nordfjell, Department of Forest Resource Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
article id 134, category Research article
Dan Bergström, Urban Bergsten, Tomas Nordfjell. (2010). Comparison of boom-corridor thinning and thinning from below harvesting methods in young dense Scots pine stands. Silva Fennica vol. 44 no. 4 article id 134. https://doi.org/10.14214/sf.134
At present, only a small proportion of the potential extractable bioenergy from young dense forests in Sweden is utilized. The conventional mechanized first thinning systems used in such stands suffer from low productivity, so the operation is only profitable in stands with bigger trees and high standing volumes. Conventional harvesters are used for this operation equipped with accumulating felling heads designed for handling several trees during each crane cycle. In thinning from below the felling and bunching work requires many time-consuming non-linear crane movements to avoid felling or damaging of future crop trees. However, higher productivity can be achieved when trees between strip roads are harvested in about 1 m-wide corridors with a length corresponding to the reach of the crane. We refer to this operation as boom-corridor thinning. The objective of this study was to compare felling and bunching productivity in young dense stands when employing thinning from below or boom-corridor thinning. Experiments were performed using a randomized block design involving between 4400 and 18 600 trees x ha-1 with a corresponding average tree size of 7.2 and 3.2 cm dbh, respectively. Based on the average tree being removed at a dbh of 5.7 cm, the productivity (ODt x PW-hour-1) was significant (almost 16%) higher for the boom-corridor thinning than for thinning from below treatment. At the same time, the time taken for the work element “Crane in-between” (the period between the loaded crane starting to move towards a tree and the felling head rapidly slowing down for positioning) was significantly reduced, by almost 17%. The positive results were achieved even though the operator was new to the method. To achieve a significantly higher efficiency during the felling and bunching operation, development of new harvesting equipment and operating techniques seems crucial.
  • Bergström, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden ORCID ID:E-mail: dan.bergstrom@srh.slu.se (email)
  • Bergsten, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden ORCID ID:E-mail:
  • Nordfjell, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden ORCID ID:E-mail:
article id 134, category Research article
Dan Bergström, Urban Bergsten, Tomas Nordfjell. (2010). Comparison of boom-corridor thinning and thinning from below harvesting methods in young dense Scots pine stands. Silva Fennica vol. 44 no. 4 article id 134. https://doi.org/10.14214/sf.134
At present, only a small proportion of the potential extractable bioenergy from young dense forests in Sweden is utilized. The conventional mechanized first thinning systems used in such stands suffer from low productivity, so the operation is only profitable in stands with bigger trees and high standing volumes. Conventional harvesters are used for this operation equipped with accumulating felling heads designed for handling several trees during each crane cycle. In thinning from below the felling and bunching work requires many time-consuming non-linear crane movements to avoid felling or damaging of future crop trees. However, higher productivity can be achieved when trees between strip roads are harvested in about 1 m-wide corridors with a length corresponding to the reach of the crane. We refer to this operation as boom-corridor thinning. The objective of this study was to compare felling and bunching productivity in young dense stands when employing thinning from below or boom-corridor thinning. Experiments were performed using a randomized block design involving between 4400 and 18 600 trees x ha-1 with a corresponding average tree size of 7.2 and 3.2 cm dbh, respectively. Based on the average tree being removed at a dbh of 5.7 cm, the productivity (ODt x PW-hour-1) was significant (almost 16%) higher for the boom-corridor thinning than for thinning from below treatment. At the same time, the time taken for the work element “Crane in-between” (the period between the loaded crane starting to move towards a tree and the felling head rapidly slowing down for positioning) was significantly reduced, by almost 17%. The positive results were achieved even though the operator was new to the method. To achieve a significantly higher efficiency during the felling and bunching operation, development of new harvesting equipment and operating techniques seems crucial.
  • Bergström, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden ORCID ID:E-mail: dan.bergstrom@srh.slu.se (email)
  • Bergsten, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden ORCID ID:E-mail:
  • Nordfjell, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden ORCID ID:E-mail:
article id 144, category Research article
Markku Oikari, Kalle Kärhä, Teijo Palander, Heikki Pajuoja, Heikki Ovaskainen. (2010). Analyzing the views of wood harvesting professionals related to the approaches for increasing the cost-efficiency of wood harvesting from young stands. Silva Fennica vol. 44 no. 3 article id 144. https://doi.org/10.14214/sf.144
A lot of viable guidelines are currently available for more cost-effective harvesting of energy wood and industrial roundwood (i.e. pulpwood) from young stands. The study ranked the proposed potential approaches for increasing the cost-efficiency of small-diameter (d1.3 < 10 cm) energy wood and industrial roundwood harvesting from early thinnings. Research data, based on a total of 40 personal interviews, was collected in early 2008. The interviewees were divided into four wood harvesting professional groups: 1) Managers in wood procurement organizations, 2) Forest machine contractors, 3) Forest machine manufacturers and vendors, and 4) Wood harvesting researchers. In the opinion of the respondents, there is great potential to increase the cost-efficiency of wood harvesting through improving harvesting conditions (i.e. effective tending of seedling stands, delaying harvesting operations, and pre-clearance of dense undergrowth). The interviewees also underlined that harvesting methods can be rationalized, e.g. multiple-tree handling in industrial roundwood cuttings, crane scale measurement, integrated wood harvesting, and careful selection of stands for harvesting. The strong message given by the interviewees was that the education of forest machine operators must be made more effective in the future. There would be significant possibilities for cost savings in young stands, if methods and techniques with the most potential were utilized completely in wood harvesting.
  • Oikari, Karelwood, Kontiolahti, Finland ORCID ID:E-mail: markku.oikari@karelwood.com (email)
  • Kärhä, Metsäteho Oy, Helsinki, Finland ORCID ID:E-mail:
  • Palander, University of Eastern Finland, Faculty of Science and Forestry, Joensuu, Finland ORCID ID:E-mail:
  • Pajuoja, Metsäteho Oy, Helsinki, Finland ORCID ID:E-mail:
  • Ovaskainen, University of Eastern Finland, Faculty of Science and Forestry, Joensuu, Finland ORCID ID:E-mail:
article id 141, category Research article
Per Kristian Rørstad, Erik Trømborg, Even Bergseng, Birger Solberg. (2010). Combining GIS and forest modelling in estimating regional supply of harvest residues in Norway. Silva Fennica vol. 44 no. 3 article id 141. https://doi.org/10.14214/sf.141
New and ambitious targets for renewable energy production put attention to increased supply of biomass. Harvest residues are only to a limited extent demanded by the traditional forest industries and represent an unutilized resource for increased production of renewable energy in Norway. The overall objective of this paper is to study how GIS and forest modelling can be combined to improve estimates of the supply of harvest residues, taking different environmental and economic constraints into consideration. The analyses are based on a case study of a forest area of more than 40 000 ha in Southern Norway divided into about 500 private forest properties. The study was carried out by computations of timber harvest using the forestry scenario model SGIS based on extensive forest inventory data at stand level. In the studied area energy utilization of harvest residues is not profitable below an energy price of about EUR 3.2/GJ (NOK 0.10 /kWh) when the distance from roadside to industry is 20 km. Above this level supply increases rapidly over a rather narrow price range and is nearly inelastic above EUR 4.1/GJ (NOK 0.12/kWh). We did not find significant negative shifts in the residues supply caused by changes in location of roundwood harvest over time. Exclusion of collection from stands with a site index (H40) below 14 reduced the potential supply of residues by 16–27%. The optimisation method combined selection of exogenous variables in order to map observed harvesting level and is probably the best approach to map future harvest.
  • Rørstad, Norwegian University of Life Sciences, Dept of Ecology and Natural Resource Management, Ås, Norway ORCID ID:E-mail: per.kristian.rorstad@umb.no (email)
  • Trømborg, Norwegian University of Life Sciences, Dept of Ecology and Natural Resource Management, Ås, Norway ORCID ID:E-mail:
  • Bergseng, Norwegian University of Life Sciences, Dept of Ecology and Natural Resource Management, Ås, Norway ORCID ID:E-mail:
  • Solberg, Norwegian University of Life Sciences, Dept of Ecology and Natural Resource Management, Ås, Norway ORCID ID:E-mail:
article id 140, category Research article
Jussi Laurila, Risto Lauhanen. (2010). Moisture content of Norway spruce stump wood at clear cutting areas and roadside storage sites. Silva Fennica vol. 44 no. 3 article id 140. https://doi.org/10.14214/sf.140
Norway spruce (Picea abies (L.) Karst.) stump wood is a potential source of bioenergy in Finland. The heating value of stump wood depends on, among other things, the moisture, carbon and ash content of the wood. In this study the moisture content of Norway spruce stump wood was examined immediately after harvesting at the clear cutting area and after different drying times at the roadside storage sites. Immediately after stump harvesting the average moisture content (wet basis) was 53%. The stump wood dried fairly fast during spring and summer. One month after stump harvesting, the average moisture content was about 31%. If the stump wood had dried well once, water absorption became very weak and the moisture content increased only slightly in the late autumn. Each spring and summer the moisture content of the stumps was lower than during the previous year. Annually the lowest moisture content was observed at the beginning of July and the highest at both the beginning and the end of the year. The moisture content of stump wood followed an upwards opening parabola over a one year period and was repeated each year. Three years after harvesting the heating value of the stump wood was still 5.241 MWh/ton. Overall, when harvesting took place in the spring or early summer, the stump wood was combustible after a one month drying period immediately after harvesting.
  • Laurila, Seinäjoki University of Applied Sciences, School of Agriculture and Forestry, FI-63700 Ähtäri, Finland ORCID ID:E-mail: jussi.laurila@seamk.fi (email)
  • Lauhanen, Seinäjoki University of Applied Sciences, School of Agriculture and Forestry, FI-63700 Ähtäri, Finland ORCID ID:E-mail:
article id 166, category Research article
Kim Pingoud, Johanna Pohjola, Lauri Valsta. (2010). Assessing the integrated climatic impacts of forestry and wood products. Silva Fennica vol. 44 no. 1 article id 166. https://doi.org/10.14214/sf.166
Managed forests serve as a store of carbon (C) and a renewable source of energy and materials. By using forest products as substitutes for fossil fuels or non-renewable materials, emissions from fossil C sources can be displaced. The efficiency of emissions displacement depends on the product, its lifecycle and the fossil-fuel based reference system that is substituted. Forest management practices have an impact on C stocks in biomass and on the annual supply of products and their mix. There are trade-offs between sequestering C stocks in forests and the climatic benefits obtained by sustainable forest harvesting and using wood products to displace fossil C emissions. This article presents an integrated, steady-state analysis comparing various equilibrium states of managed forests and wood product pools that represent sustainable long-term forestry and wood-use strategies. Two climatic indicators are used: the combined C stock in forests and wood products and the fossil C emissions displaced annually by harvested wood products. The study indicates that long-term strategies could be available that are better according to both indicators than forestry practices based on the existing silvicultural guidelines in Finland. These strategies would involve increasing the basal area and prolonging rotations to produce more sawlogs. Further, the climate benefits appear to be highest in case the sawlog supply is directed to production of long-lived materials substituting for fossil-emission and energy intensive materials and recycled after their useful life to bioenergy.
  • Pingoud, VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland ORCID ID:E-mail: kim.pingoud@vtt.fi (email)
  • Pohjola, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Valsta, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
article id 163, category Research article
Blas Mola-Yudego. (2010). Regional potential yields of short rotation willow plantations on agricultural land in Northern Europe. Silva Fennica vol. 44 no. 1 article id 163. https://doi.org/10.14214/sf.163
The development of short rotation forestry for bioenergy requires accurate and reliable yield estimates. This paper analyses the current, expected and potential regional productivity of short rotation willow plantations for six countries in Northern Europe. The estimations for present productivity are based on empirical models, using data regarding management, and local productivity based on the regional cereal yields. The estimates of expected yield rely on the current trends of yield increase from commercial willow plantations in the region. The estimates for potential yield are based on climatic restrictions. The results show potential average yields of 9.5, 6.8, 7.9, 9.0, 9.3, and 8.0 odt ha–1 yr–1 for Denmark, Finland, Estonia, Latvia, Lithuania and Sweden, respectively. The results of the study also show that there is a wide regional variation between the different countries. In Denmark, Finland and Sweden there is a convergence between the future forecasts and the climatic potential yields in the areas of high productivity. The Baltic countries seem to present lower estimates of present productivity, reflecting possible socio-economic restrictions, although they show a high biomass potential. The methods presented in this study can be further developed in other areas where willow cultivation is considered, and can serve as a basis for future economic considerations.
  • Mola-Yudego, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: blas.mola@uef.fi (email)
article id 162, category Research article
Ruut Rabinowitsch-Jokinen, Ilkka Vanha-Majamaa. (2010). Immediate effects of logging, mounding and removal of logging residues and stumps on coarse woody debris in managed boreal Norway spruce stands. Silva Fennica vol. 44 no. 1 article id 162. https://doi.org/10.14214/sf.162
Wood fuel production has increased remarkably, but its environmental effects within the forest ecosystem have not yet been studied much. We investigated the immediate effects of two series of forest management treatments, which produce timber and forest chips, on the volume and decay classes of coarse woody debris (CWD). One of the treatment series included logging and residue harvesting (LRH) and mounding (M), while the other series included LRH and mounding combined with stump harvesting (MSH). We hypothesized that, i) LRH reduces CWD, excluding stumps; ii) the more intense the soil preparation treatment is, M vs. MSH, the more CWD is destroyed; iii) both LRH and soil preparation treatments (M and MSH) reduce the occurence of snags, highly decayed CWD and deciduous CWD in particular. Ten sample plots in mature managed Norway spruce (Picea abies (L.) H. Karst.) dominated forests were located in Southern Finland. The total volume of CWD on the sample plots was measured three times: before and after LRH, and after M or MSH. LRH significantly decreased the volume of snags and the combined volume of snags and logs. MSH significantly decreased the total volume of CWD, while M had no significant effect on the volume of CWD. The middle and highly decayed CWD were destroyed most easily in the treatments.
  • Rabinowitsch-Jokinen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301, Vantaa, Finland ORCID ID:E-mail:
  • Vanha-Majamaa, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301, Vantaa, Finland ORCID ID:E-mail: ilkka.vanha-majamaa@metla.fi (email)
article id 464, category Research article
Christian Kanzian, Franz Holzleitner, Karl Stampfer, Sarah Ashton. (2009). Regional energy wood logistics – optimizing local fuel supply. Silva Fennica vol. 43 no. 1 article id 464. https://doi.org/10.14214/sf.464
The promotion of electric energy production from solid biomass by the Austrian government has lead to a boom in the construction of new combined heat and power plants. The current total demand for wood chips in the research area for energy purposes is 70 400 m3 of loose volume chips per year. The expected increase in demand due to these new plants is more than 4 times greater than current demand: up to 302 700 m3 of loose volume per year. Even if the energy wood feedstock potential is satisfactory, the design of the supply chain is still unresolved. The aim of this study is to give decision-makers a base for further development. To accomplish this, we designed and tested four different supply scenarios: one for 9 plants and one for 16 plants. The scenarios were developed using a combination of geographic information systems (GIS) and linear programming methods. The results indicate that direct transport of solid fuel wood as round wood and chipping at the plant is the cheapest supply system with a resulting cost of 5.6–6.6 EUR/m3 loose. Using harvesting residues can only be recommended for large plants because of poor fuel quality. In this case, residues would be chipped at or near the landing, piled and transported via self-loading trucks at a cost between 8.4 and 9.1 EUR/m3 loose. In order to meet increasing demand and to ensure a continuous supply, especially during the winter and spring seasons it is necessary to optimize the supply chain by including storage terminals. However, using terminals and increased demand both lead to higher logistical costs. For example, if the total volume is handled via terminals, the average supply costs including storage will increase by 26%. Higher demand increases the costs by 24%.
  • Kanzian, University of Applied Life Sciences Vienna, Institute of Forest Engineering, Peter Jordan Strasse 82, A-1190 Vienna, Austria ORCID ID:E-mail: christian.kanzian@boku.ac.at (email)
  • Holzleitner, University of Applied Life Sciences Vienna, Institute of Forest Engineering, Peter Jordan Strasse 82, A-1190 Vienna, Austria ORCID ID:E-mail:
  • Stampfer, University of Applied Life Sciences Vienna, Institute of Forest Engineering, Peter Jordan Strasse 82, A-1190 Vienna, Austria ORCID ID:E-mail:
  • Ashton, Southern Regional Extension Forestry, Forestry Bldg. 4-420, University of Georgia, Athens, GA 30602, USA ORCID ID:E-mail:
article id 220, category Research article
Jani Heikkilä, Matti Sirén, Anssi Ahtikoski, Jari Hynynen, Tiina Sauvula, Mika Lehtonen. (2009). Energy wood thinning as a part of stand management of Scots pine and Norway spruce. Silva Fennica vol. 43 no. 1 article id 220. https://doi.org/10.14214/sf.220
The effects of combined production of industrial and energy wood on yield and harvesting incomes, as well as the feasibility of energy wood procurement, were studied. Data for 22 Scots pine (Pinus sylvestris L.) and 21 Norway spruce (Picea abies (L.) Karst.) juvenile stands in Central and Southern Finland were used to compare six combined production regimes to conventional industrial wood production. The study was based on simulations made by the MOTTI stand simulator, which produces growth predictions for alternative management regimes under various site and climatic conditions. The combined production regimes included precommercial thinning at 4–8 m dominant height to a density of 3000–4000 stems ha–1 and energy wood harvesting at 8, 10 or 12 m dominant height. Combined production did not decrease the total yield of industrial wood during the rotation period. Differences in the mean annual increment (MAI) were small, and the rotation periods varied only slightly between the alternatives. Combined production regime can be feasible for a forest owner if the price of energy wood is 3–5 EUR m–3 in pine stands, and 8–9 EUR m–3 in spruce stands. Energy wood procurement was not economically viable at the current energy price (12 EUR MWh–1) without state subsidies. Without subsidies a 15 EUR MWh–1 energy price would be needed. Our results imply that the combined production of industrial and energy wood could be a feasible stand management alternative.
  • Heikkilä, L&T Biowatti Oy, P.O. Box 738, FI-60101 Seinäjoki, Finland ORCID ID:E-mail: jani.heikkila@biowatti.fi (email)
  • Sirén, Finnish Forest Research Institute, Vantaa Research Unit, P.O.Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
  • Ahtikoski, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O.Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Hynynen, Finnish Forest Research Institute, Vantaa Research Unit, P.O.Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
  • Sauvula, Seinäjoki University of Applied Sciences, School of Agriculture and Forestry, Tuomarniementie 55, FI-63700 Ähtäri, Finland ORCID ID:E-mail:
  • Lehtonen, Finnish Forest Research Institute, Vantaa Research Unit, P.O.Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
article id 256, category Research article
Juha Laitila. (2008). Harvesting technology and the cost of fuel chips from early thinnings. Silva Fennica vol. 42 no. 2 article id 256. https://doi.org/10.14214/sf.256
This study compared and analyzed the procurement cost of whole tree chips when using supply chains based on comminution at the roadside landing or at the terminal. It also identified the bottlenecks of the most common logging systems used in Finland. The study was done by using existing and published productivity parameters and models. The procurement cost calculations were made for a stand where the forwarding distance was 200 metres, removal of whole trees was 60 m per hectare and the area of the stand was 2.0 hectares. The average size of the removed whole trees was 30 litres. The direct transport distance from the stand to the terminal or to the end use facility was 40 km while the secondary distance from the terminal to the end use facility was 10 km. A stumpage price for the harvested raw material was not included in this study. According to the study the cost of whole trees chips were 31.9–41.6 euros/m at the plant, or 14.9–19.4 euros/MWh when the moisture content of chips was estimated to be 40%. The two-machine system was found to be the most cost competitive logging system in pre-commercial thinnings thanks to both efficient cutting and, especially, forwarding work. In the manual worker based logging, the costs of felling bunching were the same as the mechanised system, whereas in forwarding the costs were almost double. Using the harwarder system the logging costs were found to be the highest, but in the larger tree volumes and removals the costs were almost equal to the manual worker based logging. The supply chain based on chipping at the roadside landing was more cost efficient compared to the chipping at the terminal system. The lower comminution cost at the terminal was not enough to cover the higher transportation cost of unprocessed material to the terminal, handling cost of chips at the terminal or the delivery cost to the end use facility.
  • Laitila, Finnish Forest Research Institute, Joensuu Research Unit, Joensuu, Finland ORCID ID:E-mail: juha.laitila@metla.fi (email)
article id 309, category Research article
Sandhya Samarasinghe, Don Kulasiri, Tristan Jamieson. (2007). Neural networks for predicting fracture toughness of individual wood samples. Silva Fennica vol. 41 no. 1 article id 309. https://doi.org/10.14214/sf.309
Strain energy release rate (GIc) of Pinus radiata in the TL opening mode was determined using the compliance crack length relationship. A total of 123 specimens consisting of four sizes of specimen with each size having four different crack lengths were tested. For each specimen, grain and ring angles, density and moisture content were measured. Video imaging, was used to measure crack length during propagation. Since cracks extended in stages, full compliance-crack length relationship was developed for each specimen based on their initial and subsequent crack lengths. No significant differences in GIc, between initial and subsequent crack lengths were found for the smaller specimens by paired sample t-tests, but differences were significant for the largest specimen size. The Average fracture toughness was calculated from GIc and it was 215 kPa.m0.5. Three artificial neural networks were developed to predict the: 1) force required to propagate a crack, 2) crack extension, and 3) fracture toughness of an individual specimen. Each was successful, producing respective R2 of 0.870, 0.865, and 0.621 on validation data. A sensitivity analysis of the networks revealed that the crack length was the most influential with 21% contribution followed by grain angle with 14% contribution for predicting the applied force. This was followed by volume and physical properties. For predicting the crack extension, density had the greatest contribution (20%) followed by previous crack length and force contributing 16% equally. Fracture toughness was dominated by the dimensional parameters of the specimen contributing (42%) followed by anisotropy and physical properties.
  • Samarasinghe, Centre for Advanced Computational Solutions (C-fACS), Lincoln University, New Zealand ORCID ID:E-mail:
  • Kulasiri, Centre for Advanced Computational Solutions (C-fACS), Lincoln University, New Zealand ORCID ID:E-mail:
  • Jamieson, Centre for Advanced Computational Solutions (C-fACS), Lincoln University, New Zealand ORCID ID:E-mail:

Category: Research note

article id 60, category Research note
Dominik Röser, Blas Mola-Yudego, Robert Prinz, Beatrice Emer, Lauri Sikanen. (2012). Chipping operations and efficiency in different operational environments. Silva Fennica vol. 46 no. 2 article id 60. https://doi.org/10.14214/sf.60
This research analyses the productivity of energy wood chipping operations at several sites in Austria and Finland. The aim of the work is to examine the differences in productivity and the effects of the operational environment for the chipping of bioenergy at the roadside. Furthermore, the study quantifies the effects of different variables such as forest energy assortments, tree species, sieve size and machines on the overall productivity of chipping. The results revealed that there are significant differences in the chipping productivity in Austria and Finland which are largely based on the use of different sieve sizes. Furthermore, the different operational environments in both countries, as well as the characteristics of the raw material also seem to have an effect on productivity. In order to improve the chipping productivity, particularly in Central European conditions, all relevant stakeholders need to work jointly to find solutions that will allow a greater variation of chip size. Furthermore, in the future more consideration has to be given to the close interlinkage between the chipper, crane and grapple. As a result, investments costs can be optimized and operational costs and stress on the machines reduced.
  • Röser, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: dominik.roser@metla.fi (email)
  • Mola-Yudego, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
  • Prinz, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Emer, University of Padova, Department of Land, Agriculture and Forest Systems, Legnaro (PD), Italy ORCID ID:E-mail:
  • Sikanen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
article id 148, category Research note
Ola Lindroos, Magnus Matisons, Petter Johansson, Tomas Nordfjell. (2010). Productivity of a prototype truck-mounted logging residue bundler and a road-side bundling system. Silva Fennica vol. 44 no. 3 article id 148. https://doi.org/10.14214/sf.148
When recovering logging residues (LR) for bioenergy its density should be increased before road transport, otherwise a low proportion of the trucks’ load capacity will be used. One way this can be currently done is to compress LR into bundles that are forwarded to roadside landing. A less well-developed alternative is to forward loose LR and bundle it at landing. In the presented study, a prototype specifically developed for road-side bundling was found to produce larger, heavier bundles than bundling machinery intended for in-field use (mean length, diameter and raw bulk density 4.7 m, 0.8 m and 285 kg m–3, respectively, with 299–445 kg oven dry matter per bundle). The machine was also at least 30% more productive than previously described in-field bundling systems, producing 14–19 bundles per productive work hour (PWh), equivalent to 5.2–7.8 oven-dry tonnes PWh–1. Bundles were estimated to use 67–86% of an LR truck’s 30 tonnes load capacity, similar to proportions used when transporting loose LR. However, a continuous feeding and compressing process would probably almost double productivity, while longer bundles would enable full use of truck load capacity. With such improvements bundling at road-side could provide a viable alternative to current LR-recovering systems.
  • Lindroos, Department of Forest Resource Management, Swedish University of Agricultural Sciences, Umeå, Sweden ORCID ID:E-mail: ola.lindroos@srh.slu.se (email)
  • Matisons, Department of Forest Resource Management, Swedish University of Agricultural Sciences, Umeå, Sweden ORCID ID:E-mail:
  • Johansson, Sveaskog Förvaltnings AB, Vindeln, Sweden ORCID ID:E-mail:
  • Nordfjell, Department of Forest Resource Management, Swedish University of Agricultural Sciences, Umeå, Sweden ORCID ID:E-mail:
article id 470, category Research note
Paula Jylhä, Juha Laitila. (2007). Energy wood and pulpwood harvesting from young stands using a prototype whole-tree bundler. Silva Fennica vol. 41 no. 4 article id 470. https://doi.org/10.14214/sf.470
The productivity of cutting and bundling whole trees using the first prototype of a bundle-harvester comprised of a harwarder as the base machine, an accumulating felling head, and a compacting device was studied in three young stands in order to facilitate the further development of the concept. In addition, the removal and its composition were studied as a means of laying the foundations for developing methods for work rating and measurement on delivery. Bundling enables in-depth integration of pulpwood and energy wood procurement. Both energy wood (crown biomass) and pulpwood can be incorporated into the same bundles, and the subsequent separation of these fractions takes place at the debarking phase at the pulpmill. Bundle-harvesting productivities were relatively low (2.8–3.7 m3/E0-h) when compared to current harvesting technology. Improving working techniques, machine structure, and components showed great potential for increasing the efficiency of the concept. The bundles were dimensionally uniform. Their solid volume varied between 0.350 m3 and 0.513 m3, depending on the bundle assortment and stand properties. Integrating energy wood harvesting with pulpwood harvesting increased removal even by 59 per cent.
  • Jylhä, Finnish Forest Research Institute, Kannus Research Unit, P.O. Box 44, FI-69101 Kannus, Finland ORCID ID:E-mail: paula.jylha@metla.fi (email)
  • Laitila, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
article id 311, category Research note
Dan Bergström, Urban Bergsten, Tomas Nordfjell, Tomas Lundmark. (2007). Simulation of geometric thinning systems and their time requirements for young forests. Silva Fennica vol. 41 no. 1 article id 311. https://doi.org/10.14214/sf.311
In Fennoscandia, large areas that have not been subjected to pre-commercial thinning (PCT), and thus support dense stands, are becoming suitable for harvesting biomass. However, efficient systems for harvesting biomass from young stands have not yet been developed. In order to optimise biomass harvesting it is here hypothesized that the handling unit should not be a single tree but a corridor area, i.e., all trees in a specific area should be harvested in the same crane movement cycle. Three types of corridor harvesting approaches (using accumulating felling heads for geometric harvesting in two different patterns) were compared in terms of time required to fell a corridor of standardised size. Corridors are defined as strips of harvested areas between conventional strip-roads. Harvests were simulated in two types of stands, first thinning (FT) and delayed PCT stands, in which the spatial positions of the trees had been mapped. The differences in simulated time consumption per corridor were minor when the only variable changed was the corridor pattern. However, there were ca. 2-fold and 3-fold differences in simulated time consumption per corridor between the harvesting approaches for the FT stand and the PCT-stand, respectively. Furthermore, area handling (felling head accumulating all trees corridor-wise, with no restrictions on the accumulated number of trees except for a certain load limit) was found to give up to 2.4-fold increases in productivity compared to a single-tree (reference) approach for the FT stand. In conclusion, the simulation results clearly show the benefits of applying area-harvesting systems in young, dense stands.
  • Bergström, SLU, Dept. of Forest Resource Management, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Bergsten, SLU, Dept. of Forest Ecology and Management, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Nordfjell, SLU, Dept. of Forest Resource Management, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Lundmark, SLU, Vindeln Experimental Forests, Svartberget Field Station, SE-922 91 Vindeln, Sweden ORCID ID:E-mail:

Category: Article

article id 5314, category Article
M. Saarilahti, E. Bakena, G. Mboya, T. Minja, T. Ngerageze, J. Ntahompagaze. (1987). Studies on Tanzanian forest work. Silva Fennica vol. 21 no. 2 article id 5314. https://doi.org/10.14214/sf.a15471

Four teams of two workers were time-studied in clearcutting of a cypress plantation and three teams in sulky skidding. The heart rate was recorded every 30 s. The average heartrate in timber cutting was 117.5 ± 13.4 P/min, and it was mainly dependent on worker’s working capacity. Average work load index was 41 ± 3% when working at 97% performance. The production rate was then 2.5 m3/h (crew). In sulky skidding the heart rate was lower, 106 ± 1.1 P/min, as well as the work load (WLI 30 ± 1%) and performance rating (87%). The low production rate (1.1 m3/h) (crew)) over 45 m distance is mainly due to under-dimensioned load size. The energy expenditure in timber cutting was 21.4 kJ/min and in sulky skidding 16.3 kJ/min. Daily energy expenditure was 15.0 MJ/d, and most of the timber cutters belonged to the class ”exceptionally active”.

The PDF includes an abstract in Finnish.

  • Saarilahti, ORCID ID:E-mail:
  • Bakena, ORCID ID:E-mail:
  • Mboya, ORCID ID:E-mail:
  • Minja, ORCID ID:E-mail:
  • Ngerageze, ORCID ID:E-mail:
  • Ntahompagaze, ORCID ID:E-mail:
article id 5145, category Article
Torleif Bramryd. (1981). Environmental effects of heavy metals distributed from power plants. Silva Fennica vol. 15 no. 4 article id 5145. https://doi.org/10.14214/sf.a15372

Increased prices on oil have resulted in the search for alternative energy sources, e.g. coal, peat, biomass, different types of waste. Combustion especially of waste, coal and peat emits large quantities of air pollutants such as heavy metals but also harmful organic substances. Heavy metals are not easily separated from the smoke, and the concentrations are often high in the emissions even with advanced fly-ash separators.

Ecological investigations carried out around a coal burning power plant in Finland using mosses and pine needles as parameters are presented in the paper. Increased concentrations of Pb, Cd, Cr, Ni, Cu and V have been found near the plant. Often a clear gradient was found with increased concentrations at decreased distance from the power plant.

  • Bramryd, ORCID ID:E-mail:
article id 5057, category Article
Rainer Rauramaa, Kaj Husman, Katriina Kukkonen, Erkki Voutilainen. (1980). Metsurien ravinto ja seerumin lipoproteiinit - esitutkimus. Silva Fennica vol. 14 no. 1 article id 5057. https://doi.org/10.14214/sf.a14998
English title: Preliminary observations about diet, serum lipids and lipoproteins among lumberjacks.

Energy intake of ten lumberjacks in Eastern Finland was estimated by using 24-hour recall. In addition, serum cholesterol and triglycerides were analysed in different lipoprotein fractions. Average energy intake was according to present recommendations in Finland, although there was great individual variation. Serum triglycerides were in the normal range. Five lumberjacks’ total cholesterol concentration was somewhat increased. Average HDL concentration was clearly greater than in men of the same age.

The PDF includes a summary in English.

  • Rauramaa, ORCID ID:E-mail:
  • Husman, ORCID ID:E-mail:
  • Kukkonen, ORCID ID:E-mail:
  • Voutilainen, ORCID ID:E-mail:
article id 5000, category Article
Hannu Mannerkoski. (1978). Säteilymittarin m/Frankfurt soveltuvuus energiatasemittauksiin. Silva Fennica vol. 12 no. 3 article id 5000. https://doi.org/10.14214/sf.a14854
English title: Use of chemical totalizer of radiation in energy balance measurements.

The investigation is concerned with testing chemical totalizer of radiation (Frankfurt radiometer) for use in measuring the components of a simple energy balance (latent heat = net radiation – sensible heat) so as to gain an estimate for evaporation. The meter is based on the temperature dependence of the inversion rate of sugar solution. The relationship is exponential. It was found that radiation sums for 2–6-day periods can be reliably determined with this meter when global radiation is below 20 MJ·m-2d-1. Determining sensible heat is noticeably inaccurate, and hence the calculation of evaporation values, too. In comparing evaporation from different types of ground and plant cover one thus has to be content with drawing conclusions on the basis of net radiation values. The totalizer is therefore only suited to describing radiation conditions.

The PDF includes a summary in Finnish.

  • Mannerkoski, ORCID ID:E-mail:

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