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Dan Bergström
Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden

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Journal article
Published: 01 January 2021 in Silva Fennica
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Young, dense forest in Finland and Sweden urgently need to receive first thinning. In such stands, conventional selective thinning methods make the harvester work time consuming and, thus, costly. To make small-sized trees economically competitive as raw material for bioenergy and biorefining, new harvesting technologies and/or thinning methods need to be developed. A potential solution is boom-corridor thinning (BCT), rendering effective cutting work. The aim of this study was to describe and compare the stand structure of two Scots pine stands ( L.) and one birch-dominated ( Roth with natural downy birch, Ehrh.) stand after BCT and selective thinning at the first thinning phase. Furthermore, simulations were conducted to predict the future stand development after the first thinning treatments. The density of the growing stock was 16–46% higher after BCT treatment than after selective thinning because BCT stands included more small and supressed trees with a dbh < 100 mm. However, the numbers of future crop trees with a dbh > 140 mm per hectare were at the same level in both treatments. The stem volume removal per hectare did not differ between treatments. However, simulation of stand development and intermediate thinning and clearcutting revealed that the total removal volume was 10–18% higher in BCT stands compared to selectively thinned ones. The saw log volumes harvested did, however, not differ between treatments. This study shows that BCT generates stands with higher biodiversity compared to conventional thinning as higher levels of biomass removal can be reached throughout stand rotations.Pinus sylvestris Betula pendula B. pubescens

ACS Style

Yrjö Nuutinen; Jari Miina; Timo Saksa; Dan Bergström; Johanna Routa. Comparing the characteristics of boom-corridor and selectively thinned stands of Scots pine and birch. Silva Fennica 2021, 55, 1 .

AMA Style

Yrjö Nuutinen, Jari Miina, Timo Saksa, Dan Bergström, Johanna Routa. Comparing the characteristics of boom-corridor and selectively thinned stands of Scots pine and birch. Silva Fennica. 2021; 55 (3):1.

Chicago/Turabian Style

Yrjö Nuutinen; Jari Miina; Timo Saksa; Dan Bergström; Johanna Routa. 2021. "Comparing the characteristics of boom-corridor and selectively thinned stands of Scots pine and birch." Silva Fennica 55, no. 3: 1.

Journal article
Published: 03 November 2020 in International Journal of Forest Engineering
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ACS Style

Raul Fernandez-Lacruz; Marita Edlund; Dan Bergström; Ola Lindroos. Productivity and profitability of harvesting overgrown roadside verges – a Swedish case study. International Journal of Forest Engineering 2020, 32, 19 -28.

AMA Style

Raul Fernandez-Lacruz, Marita Edlund, Dan Bergström, Ola Lindroos. Productivity and profitability of harvesting overgrown roadside verges – a Swedish case study. International Journal of Forest Engineering. 2020; 32 (1):19-28.

Chicago/Turabian Style

Raul Fernandez-Lacruz; Marita Edlund; Dan Bergström; Ola Lindroos. 2020. "Productivity and profitability of harvesting overgrown roadside verges – a Swedish case study." International Journal of Forest Engineering 32, no. 1: 19-28.

Journal article
Published: 30 October 2020 in Forests
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Family forest owners (FFOs) own 48% of Sweden’s productive forest land and are responsible for 59% of the annual gross felling. They are thus important suppliers of raw materials to the forest industry and the energy sector. Environmental goals on the national and international level promote an increased use of renewable resources in order to replace fossil-based fuels, but since the current supply of forest products is already fully utilized by the industry, there is a need to find new types of biomass assortment. One way to increase the biomass supply is to replace traditional pre-commercial thinning operations, where fallen stems are left in the forest to rot, with whole-tree harvesting of small-diameter trees using novel technologies and methods. This will however require willingness of the FFOs to shift their management practices. The objectives of this study were, therefore, to elucidate FFOs’ perceptions of management and thinning operations in young dense forests, identify if there are differences depending on their demographic backgrounds, and clarify which factors could potentially affect their willingness to implement whole-tree harvesting in young dense forests. Data were collected through a survey administered to a random sample of 842 FFOs, with a response rate of 53.4% (n = 450). The results show that FFOs in general are positive towards implementing whole-tree harvesting in young dense stands, and are often also willing to promote the development of suitable stands. Factors such as forest size, geographical location, distance from home to their forest, degree of self-employment and current need for cleaning were found to significantly affect their attitudes. The study highlights that the development of cost efficient harvesting techniques and working methods is important if the industry wants to increase the FFOs’ willingness to engage in whole-tree harvesting in young dense forest stands and thereby increase the supply of biomass.

ACS Style

Thomas Kronholm; David Bengtsson; Dan Bergström. Family Forest Owners’ Perception of Management and Thinning Operations in Young Dense Forests: A Survey from Sweden. Forests 2020, 11, 1151 .

AMA Style

Thomas Kronholm, David Bengtsson, Dan Bergström. Family Forest Owners’ Perception of Management and Thinning Operations in Young Dense Forests: A Survey from Sweden. Forests. 2020; 11 (11):1151.

Chicago/Turabian Style

Thomas Kronholm; David Bengtsson; Dan Bergström. 2020. "Family Forest Owners’ Perception of Management and Thinning Operations in Young Dense Forests: A Survey from Sweden." Forests 11, no. 11: 1151.

Journal article
Published: 17 October 2020 in International Journal of Forest Engineering
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ACS Style

Simon Berg; Dan Bergström. Quality variation in comminuted forest fuels delivered during the winter in north Sweden. International Journal of Forest Engineering 2020, 32, 11 -18.

AMA Style

Simon Berg, Dan Bergström. Quality variation in comminuted forest fuels delivered during the winter in north Sweden. International Journal of Forest Engineering. 2020; 32 (1):11-18.

Chicago/Turabian Style

Simon Berg; Dan Bergström. 2020. "Quality variation in comminuted forest fuels delivered during the winter in north Sweden." International Journal of Forest Engineering 32, no. 1: 11-18.

Journal article
Published: 16 May 2020 in Sustainability
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Bioenergy is expected to contribute to mitigating climate change. One major source for bioenergy is woody biomass from forests, including logging residues, stumps, and whole trees from young dense stands. However, at increased extraction rates of woody biomass, the forest ecosystem, its biodiversity, and its ability to contribute to fundamental ecosystem services will be affected. We used simulation and optimization techniques to assess the impact of different management strategies on the supply of bioenergy and the trade-offs between wood fuel harvesting, biodiversity, and three other ecosystem services—reindeer husbandry, carbon storage, and recreation. The projections covered 100 years and a forest area of 3 million ha in northern Sweden. We found that the development of novel and cost-effective management systems for biomass outtake from young dense stands may provide options for a significant supply of bioenergy to the emerging bioeconomy, while at the same time securing biodiversity and important ecosystem values in future stand developments. In addition, there is potential to increase the extraction of harvest residues and stumps while simultaneously improving conditions for biodiversity and the amount of carbon stored in forest ecosystems compared to current levels. However, the projected continuing trend of increased forest density (in terms of basal area) has a negative impact on the potential for reindeer husbandry and recreation, which calls for researching new management strategies on landscape levels.

ACS Style

Jeannette Eggers; Ylva Melin; Johanna Lundström; Dan Bergström; Karin Öhman. Management Strategies for Wood Fuel Harvesting—Trade-Offs with Biodiversity and Forest Ecosystem Services. Sustainability 2020, 12, 1 .

AMA Style

Jeannette Eggers, Ylva Melin, Johanna Lundström, Dan Bergström, Karin Öhman. Management Strategies for Wood Fuel Harvesting—Trade-Offs with Biodiversity and Forest Ecosystem Services. Sustainability. 2020; 12 (10):1.

Chicago/Turabian Style

Jeannette Eggers; Ylva Melin; Johanna Lundström; Dan Bergström; Karin Öhman. 2020. "Management Strategies for Wood Fuel Harvesting—Trade-Offs with Biodiversity and Forest Ecosystem Services." Sustainability 12, no. 10: 1.

Journal article
Published: 26 March 2020 in Forests
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The rising throughput of log-yards imposes new constraints on existing equipment and increases the complexity of delivering an optimal and uninterrupted supply of pulpwood to pulp mills. To find ways of addressing these problems by reducing log cycle times, this work uses a discrete-event mathematics model to simulate operations at a log-yard and study the impact of three different log-yard inventory strategies and two alternative machine systems for log transportation between main log-yard and buffer storage. The yard’s existing inventory strategy of last load in and first out limits access to older logs at the main storage site. By allocating space for 89,000 m3 and 99,000 m3 of pulpwood at the buffer storage it is possible to keep the log cycle time at the main storage to a maximum of 12 and 6 months. Additionally, the use of an alternative log transportation machine system comprising a material handler with a trailer increased the work time capacity utilization relative to the yard’s current machine system of two shuttle trucks and a material handler for transporting logs between the main and buffer storage areas. Compared to the currently-used last in first out inventory strategy and purposely emptying the main storage area once or twice per year did reduce the total work time of both machine systems by 14% and 30%. Consequently, the volume delivered from the buffer to the log-yard decreased on average by 17% and 37% when emptying the main storage area once and twice per year. Even with reduced work time when emptying the main storage area, both machine systems could fulfil given work load for transporting logs from the buffer storage to the main log-yard without interrupting operations of the log-yard.

ACS Style

Kalvis Kons; Pedro La Hera; Dan Bergström. Comparison of Alternative Pulpwood Inventory Strategies and Machine Systems at a Log-Yard Using Simulations. Forests 2020, 11, 373 .

AMA Style

Kalvis Kons, Pedro La Hera, Dan Bergström. Comparison of Alternative Pulpwood Inventory Strategies and Machine Systems at a Log-Yard Using Simulations. Forests. 2020; 11 (4):373.

Chicago/Turabian Style

Kalvis Kons; Pedro La Hera; Dan Bergström. 2020. "Comparison of Alternative Pulpwood Inventory Strategies and Machine Systems at a Log-Yard Using Simulations." Forests 11, no. 4: 373.

Journal article
Published: 14 February 2020 in Forests
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Background and Objectives: in Sweden during 2016, 71.6 million metric tonnes (t) of forest biomass (roundwood and forest fuels) were transported by truck, corresponding to approximately 15% of all national goods truck transport. To reduce the environmental impact of forest product transports and meet Swedish climate goals, the use of 90 t high-capacity transport (HCT) trucks on well-chosen routes has been identified as one potential measure. The objective was, therefore, to develop a method of finding the geographical occurrence of potential roundwood HCT corridors for 90 t trucks, as well as estimating their environmental and economic potential in comparison to the conventional 74 t-truck transport system for Swedish conditions. Materials and Methods: the study used data from actual roundwood transports during 2016 along with a digitalization of the Swedish road network (National Road Database, SNVDB) for corridor identification. In four steps we: 1) identified supportive networks, 2) identified flow supporting corridors on the technically supportive networks, 3) applied a calibrated route finder (CRF) to route relevant transports both directly from the landing to the receiver and via the corridor, gathering drive distance information and, for example, 4) analyzed transports fuel consumption and potential CO2 savings. Results: Results showed there was annual potential for 25 HCT corridors throughout Sweden to employ 20 90 t trucks to transport 2.5 Mt of roundwood, reducing up to 5500 t of CO2 and €3.1 M in fuel costs. Conclusions: the study reinforces previous studies’ findings concerning economic and environmental potential using HCT vehicles and identifies terminal establishment and management costs as a bottleneck in successful large-scale implementation of HCT corridors.

ACS Style

Christian Höök; Victor Asmoarp; Björn Edlund; Dan Bergström. A Method of Finding HCT Roundwood Corridors for Reduction of GHG Emissions and Fuel Costs in Sweden. Forests 2020, 11, 220 .

AMA Style

Christian Höök, Victor Asmoarp, Björn Edlund, Dan Bergström. A Method of Finding HCT Roundwood Corridors for Reduction of GHG Emissions and Fuel Costs in Sweden. Forests. 2020; 11 (2):220.

Chicago/Turabian Style

Christian Höök; Victor Asmoarp; Björn Edlund; Dan Bergström. 2020. "A Method of Finding HCT Roundwood Corridors for Reduction of GHG Emissions and Fuel Costs in Sweden." Forests 11, no. 2: 220.

Journal article
Published: 30 January 2020 in Forests
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This article deals with the topic of modelling the log-yard of one of our industry partners. To this end, our framework is based on discrete-events modelling (DEM), as consequence that many stages of the process run as a sequence of events. The sequence starts when trucks, trains or ships arrive loaded with logs to the log-yard. A machine unloads these logs and accumulates them in different storage areas. Consequently, a machine transports logs from these areas to the pulp mill, thus finishing the process. As using probability density functions is the core concept of DEM, the necessary process data to build these PDFs have been partly provided by the company. Other necessary data have been acquired through time studies, and by defining operational requirements. The company data tell when trucks, trains, or ships arrive to the log-yard, and the amount of volume they carry. The objective is to develop the necessary formulations, model calibration techniques, and software, such that computer simulations reproduce the quantities observed in these data. To this end, this work suggests two alternatives to analyse the data itself. These two alternatives lead to two different models: (1) The first being a hybrid model, in the sense that it involves the events in the process, and the logic decisions taken by machine operators for handling the incoming load, and (2) the second containing only the main mathematical essence of the process. After running 100 simulations, both mathematical models show that the simulated values for input and output, in terms of transport units and their volume, differ only by less than 3% compared to company data. The first model has also shown the ability to replicate the decision making that a machine operator undergoes for driving the logs to the storage areas, and from there to the mill. Therefore, the framework adopted provides the necessary mathematical tools and data analysis to model the log-yard and obtain highly reliable results via simulations.

ACS Style

Kalvis Kons; Pedro La Hera; Dan Bergström. Modelling Dynamics of a Log-Yard through Discrete-Event Mathematics. Forests 2020, 11, 155 .

AMA Style

Kalvis Kons, Pedro La Hera, Dan Bergström. Modelling Dynamics of a Log-Yard through Discrete-Event Mathematics. Forests. 2020; 11 (2):155.

Chicago/Turabian Style

Kalvis Kons; Pedro La Hera; Dan Bergström. 2020. "Modelling Dynamics of a Log-Yard through Discrete-Event Mathematics." Forests 11, no. 2: 155.

Journal article
Published: 18 December 2019 in Forests
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Research Highlights: The use of terminals can increase supply costs by 5–11% (when compared to direct supply), but terminals help secure supply during peak demand and cope with operational problems in the supply fleet in cases where direct supply chains would be unable to meet demand on time. Background and Objectives: This work analyses the supply cost of chipped logging residues and small-diameter trees, from chipping at roadside storages to delivery to the end-user. Factors considered include demand curves (based on the requirements of a theoretical combined heat and power plant or biorefinery); demand volume; and mode of supply (direct or combined via terminal). The impact of longer trucking distances from the sites, and supply integration between forest and other land (varying relocation distances) was also assessed. Materials and Methods: The operational environment and work of a theoretical chip supplier in northern Sweden were modelled and simulated in ExtendSim®. Results: The mean supply cost of chips was 9% higher on average for combined chains than for direct chains. Given a high demand, 8% of the annual demand could not be delivered on time without using a terminal. High supply integration of forest and other land reduced supply costs by 2%. Contractors’ annual workloads were evened out by direct supply to the biorefinery (which has a relatively steady demand) or supply via-terminal independently of the end-user. Keeping distinct chips from different sites (implying that trucks were not always fully loaded) instead of mixing chips from different sites until the trucks were fully loaded increased supply costs by 12%. Conclusions: Terminals increase supply costs, but can enable demand to be met on time when direct supply chains alone might fail. Integrated supply planning could reduce supply costs by increasing the utilization of residual biomass from other land.

ACS Style

Raul Fernandez-Lacruz; Anders Eriksson; Dan Bergström. Simulation-Based Cost Analysis of Industrial Supply of Chips from Logging Residues and Small-Diameter Trees. Forests 2019, 11, 1 .

AMA Style

Raul Fernandez-Lacruz, Anders Eriksson, Dan Bergström. Simulation-Based Cost Analysis of Industrial Supply of Chips from Logging Residues and Small-Diameter Trees. Forests. 2019; 11 (1):1.

Chicago/Turabian Style

Raul Fernandez-Lacruz; Anders Eriksson; Dan Bergström. 2019. "Simulation-Based Cost Analysis of Industrial Supply of Chips from Logging Residues and Small-Diameter Trees." Forests 11, no. 1: 1.

Review articles
Published: 20 March 2019 in Scandinavian Journal of Forest Research
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The review discusses the potential of mechanized thinning operations with variable corridor patterns as a method to secure multiple ecosystem services. The focus is on young and dense forests, which are increasingly abundant in Northern Europe and a potential source of renewable biomass for the needs of future bioeconomy. Conventional selective (motor-manual) pre-commercial thinning (PCT) without outtake of cut biomass is used as a benchmark to evaluate a new mechanized thinning method: boom corridor thinning (BCT). The paucity of specific studies on the environmental effects of BCT limits systematic and quantitative comparisons. However, information extrapolated from studies on selective or other corridor thinnings suggests that BCT potentiates early outtake of forest biomass for energy or biorefineries while simultaneously maintaining the stand structure’s vertical heterogeneity and thereby supporting biodiversity. More experimental evidence is urgently needed to elucidate the detailed environmental consequences of BCT, and especially its effects on biodiversity and carbon balance. The increasing need to evaluate the pros and cons of silvicultural operations against a broad range of ecosystem benefits necessitates a holistic approach and the development of new typologies and indices that better reflect the structural properties of forest stands.

ACS Style

Johanna Witzell; Dan Bergström; Urban Bergsten. Variable corridor thinning – a cost-effective key to provision of multiple ecosystem services from young boreal conifer forests? Scandinavian Journal of Forest Research 2019, 34, 497 -507.

AMA Style

Johanna Witzell, Dan Bergström, Urban Bergsten. Variable corridor thinning – a cost-effective key to provision of multiple ecosystem services from young boreal conifer forests? Scandinavian Journal of Forest Research. 2019; 34 (6):497-507.

Chicago/Turabian Style

Johanna Witzell; Dan Bergström; Urban Bergsten. 2019. "Variable corridor thinning – a cost-effective key to provision of multiple ecosystem services from young boreal conifer forests?" Scandinavian Journal of Forest Research 34, no. 6: 497-507.

Review
Published: 03 December 2018 in International Journal of Forest Engineering
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Knowledge about the generalized operational efficiency of comminution machines and systems is of great interest when tailoring solid biofuel supply systems. The objectives were therefore to collect and compare data from the literature to those from machinery manufacturers on the performances of various forest biomass comminution systems, with the aim of identifying areas for further research. Our meta-analysis was based on data from 55 scientific publications and specification sheets from 566 machine models collected from manufacturer’s websites. A majority, 56%, of studies were carried out at the roadside and 54% of studies examined comminuted logging residues, which thus reflects the most common materials and environments of the forest fuel supply system studied in the literature. We conclude that: (1) Chipping is more productive and requires less energy than grinding for machinery with nominal power up to 300 kW. (2) Chipping small trees or residues lowers productivities and increases energy demand compared to logs; the comminution productivity is dependent on the type of machine, the nominal power, and the material handled. (3) The energy demand is a function of the variable type of machinery (chipper, grinder), and maximum particle size produced. (4) Productivities in operational studies are clearly lower than the ones reported by the manufacturers in idealized conditions. Further investigations of equipment such as large chippers and grinders operated in terminals under controlled conditions are needed, in order to gain a better understanding of the different factors affecting the efficiencies of large equipment.

ACS Style

Dan Bergström; Fulvio Di Fulvio. Review of efficiencies in comminuting forest fuels. International Journal of Forest Engineering 2018, 30, 45 -55.

AMA Style

Dan Bergström, Fulvio Di Fulvio. Review of efficiencies in comminuting forest fuels. International Journal of Forest Engineering. 2018; 30 (1):45-55.

Chicago/Turabian Style

Dan Bergström; Fulvio Di Fulvio. 2018. "Review of efficiencies in comminuting forest fuels." International Journal of Forest Engineering 30, no. 1: 45-55.

Journal article
Published: 09 August 2018 in Journal of Cleaner Production
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The development of mobile systems for the decentralized pelletizing of forest-based residual biomass is currently underway. However, there is a lack of knowledge regarding the environmental impacts of such systems that needs to be developed for correct judgements on the most sustainable developing paths. The objective of this study was to quantify and compare the environmental impacts of a decentralized mobile production system for pelletizing logging residues in Northern Sweden operating at either the forest landing or forest terminal from a Life Cycle Assessment (LCA) perspective. The results showed that the landing- and terminal-based scenarios showed similar environmental profiles. The pelleting, transportation and drying stages of both scenarios were identified as environmental hotspots. These production stages accounted for 62%, 14% and 14% of the total greenhouse gas emissions, respectively. Key factors influencing the system were the use of electricity at terminals, the increase in pelletizer capacity, and long transportation distances. The use of a Swedish electricity mix instead of diesel based electricity in the terminal-based scenario reduced all of the environmental impacts by between 68% and 83%, with the exception of fresh water eutrophication potential, which increased by 26%. In conclusion, our findings indicate that an electrified mobile pellet production system with high operational efficiency and situated at a terminal close to the harvesting sites could, from an LCA point of view, be an interesting option for pelletizing Nordic logging residues, especially in regions with long transportation distances to industry.

ACS Style

Teresa de la Fuente; Dan Bergström; Sara González-García; Sylvia H. Larsson. Life cycle assessment of decentralized mobile production systems for pelletizing logging residues under Nordic conditions. Journal of Cleaner Production 2018, 201, 830 -841.

AMA Style

Teresa de la Fuente, Dan Bergström, Sara González-García, Sylvia H. Larsson. Life cycle assessment of decentralized mobile production systems for pelletizing logging residues under Nordic conditions. Journal of Cleaner Production. 2018; 201 ():830-841.

Chicago/Turabian Style

Teresa de la Fuente; Dan Bergström; Sara González-García; Sylvia H. Larsson. 2018. "Life cycle assessment of decentralized mobile production systems for pelletizing logging residues under Nordic conditions." Journal of Cleaner Production 201, no. : 830-841.

Journal article
Published: 01 January 2018 in Silva Fennica
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According to the Swedish Timber Measurement Act, measurements affecting payments for wood fuels to landowners must be accurate and precise. In this regard, moisture content is an important quality parameter for wood chips which influences the net calorific value as received and thus the economic value. As standard practice moisture content is determined with the oven-drying method, which is cumbersome to use for deliveries to facilities without drying-ovens, which in turn necessitates that samples are taken elsewhere for measurement. An alternative solution is to use a portable moisture meter. Our aim was to evaluate the precision of a handheld capacitance moisture meter. Accuracy and precision of a capacitance meter was determined in the lab and a calibration function was made. Thereafter, the calibrated moisture meter was compared with the standard method for moisture content determination of truckloads of chips. The capacitance meter showed a moderate accuracy by underestimating moisture content by 6.0 percentage points (pp), compared to the reference method, at a precision of ±3.8 pp (CI 95%). For chips with M > 50%, both accuracy and precision decreased. Calibration increased the accuracy in the follow up study by 3 pp for chips with M < 50% but could not be made for wetter chips. The oven-drying method and the capacitance meter can provide equally accurate estimates of mean moisture content for chips with M < 50% if a larger sample is taken with the latter. It should be possible to use capacitance meters to measure moisture content even when used to calculate payments depending of the needed accuracy. A calibration function for each assortment is needed.

ACS Style

Lars Fridh; Lars Eliasson; Dan Bergström. Precision and accuracy in moisture content determination of wood fuel chips using a handheld electric capacitance moisture meter. Silva Fennica 2018, 52, 1 .

AMA Style

Lars Fridh, Lars Eliasson, Dan Bergström. Precision and accuracy in moisture content determination of wood fuel chips using a handheld electric capacitance moisture meter. Silva Fennica. 2018; 52 (5):1.

Chicago/Turabian Style

Lars Fridh; Lars Eliasson; Dan Bergström. 2018. "Precision and accuracy in moisture content determination of wood fuel chips using a handheld electric capacitance moisture meter." Silva Fennica 52, no. 5: 1.

Journal article
Published: 21 June 2017 in International Journal of Forest Engineering
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ACS Style

Raul Fernandez-Lacruz; Dan Bergström. Windrowing and fuel-chip quality of residual forest biomasses in northern Sweden. International Journal of Forest Engineering 2017, 28, 186 -197.

AMA Style

Raul Fernandez-Lacruz, Dan Bergström. Windrowing and fuel-chip quality of residual forest biomasses in northern Sweden. International Journal of Forest Engineering. 2017; 28 (3):186-197.

Chicago/Turabian Style

Raul Fernandez-Lacruz; Dan Bergström. 2017. "Windrowing and fuel-chip quality of residual forest biomasses in northern Sweden." International Journal of Forest Engineering 28, no. 3: 186-197.

Journal article
Published: 01 January 2017 in Silva Fennica
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ACS Style

Kristina Ahnlund Ulvcrona; Dan Bergström; Urban Bergsten. Stand structure after thinning in 1–2 m wide corridors in young dense stands. Silva Fennica 2017, 51, 1 .

AMA Style

Kristina Ahnlund Ulvcrona, Dan Bergström, Urban Bergsten. Stand structure after thinning in 1–2 m wide corridors in young dense stands. Silva Fennica. 2017; 51 (3):1.

Chicago/Turabian Style

Kristina Ahnlund Ulvcrona; Dan Bergström; Urban Bergsten. 2017. "Stand structure after thinning in 1–2 m wide corridors in young dense stands." Silva Fennica 51, no. 3: 1.

Journal article
Published: 01 May 2016 in Biomass and Bioenergy
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Marginal lands could be utilized for increasing energy biomass production independent of industrial roundwood procurement. Dedicated energy biomass production systems on such sites would be based on low stand establishment cost, clear-cutting at an early stage, and coppice regeneration. Harvesters designed for the processing of industrial roundwood are inefficient or too costly to use in small-diameter and dense stands, while insufficient cutting capacity and uneven space distribution of trees limit the use of modified agricultural harvesters developed for short-rotation woody-crop plantations (e.g. willow). We constructed time consumption models for clear-cutting and forwarding of whole trees from un-thinned, small-diameter stands. The data originated from naturally afforested downy birch-dominated stands located in a cutaway peat production area in northern Finland. Stand age varied from 14 to 29 years and stand density was 5150–160,250 trees per hectare. In clear-cutting, a medium-sized forest harvester equipped with an accumulating felling head fitted with a circular saw disc was used, and subsequent forwarding was done using a modified medium-sized forwarder. Cutting productivity was 3–11oven-dry tons (ODt) per effective hour (E0-h), and was highly dependent on stand characteristics (e.g. mean whole-tree volume). At a distance of 300 m, for example, the productivity of forwarding in the time study plots was 6.7–10.4 ODt E0-h−1. Our study indicates that energy biomass can be harvested from young downy birch thickets efficiently by clear-cutting with appropriate machinery.

ACS Style

Paula Jylhä; Dan Bergström. Productivity of harvesting dense birch stands for bioenergy. Biomass and Bioenergy 2016, 88, 142 -151.

AMA Style

Paula Jylhä, Dan Bergström. Productivity of harvesting dense birch stands for bioenergy. Biomass and Bioenergy. 2016; 88 ():142-151.

Chicago/Turabian Style

Paula Jylhä; Dan Bergström. 2016. "Productivity of harvesting dense birch stands for bioenergy." Biomass and Bioenergy 88, no. : 142-151.

Research article
Published: 26 March 2015 in Scandinavian Journal of Forest Research
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The aim of this study was to investigate the profitability of management regimes including both early biomass thinning (leaving 4000 stems/ha and using systematic boom-corridor thinning) and conventional production of pulp and timber. Empirical data obtained from five dense (11,000–20,000 stems/ha) naturally regenerated Scots pine experimental plots in which pre-commercial thinning (PCT) to 2500 stems/ha and control treatments (no PCT) were originally applied were used to initiate simulations. Biomass thinning was simulated at mean heights 6–7 m (BIO1) and 8–9 m (BIO2) in control plots. Land expectation values (LEVs) were calculated (3% interest rate), after simulating stands development to final harvest. Given the targeted stand stem density, 36–67 oven dry tons/ha were harvested in the simulations. Compared with PCT, both BIO regimes resulted in a somewhat lower average tree size in all subsequent harvest operations but a higher LEV in four of the five stands, if thinning was integrated with bundling. Higher LEVs (on average 27%) were achieved when BIO2 was applied compared to BIO1. Consequently, high biomass removal from dense Scots pine stands early in rotation periods might provide substantial economic benefits for forest owners, but appropriate general decision tools are needed to maximize profit.

ACS Style

Lars Karlsson; Kenneth Nyström; Dan Bergström; Urban Bergsten. Development of Scots pine stands after first biomass thinning with implications on management profitability over rotation. Scandinavian Journal of Forest Research 2015, 1 -13.

AMA Style

Lars Karlsson, Kenneth Nyström, Dan Bergström, Urban Bergsten. Development of Scots pine stands after first biomass thinning with implications on management profitability over rotation. Scandinavian Journal of Forest Research. 2015; ():1-13.

Chicago/Turabian Style

Lars Karlsson; Kenneth Nyström; Dan Bergström; Urban Bergsten. 2015. "Development of Scots pine stands after first biomass thinning with implications on management profitability over rotation." Scandinavian Journal of Forest Research , no. : 1-13.

Journal article
Published: 01 January 2015 in Silva Fennica
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ACS Style

Raul Fernandez-Lacruz; Fulvio Di Fulvio; Dimitris Athanassiadis; Dan Bergström; Tomas Nordfjell. Characteristics of unthinned biomass-dense forests in Sweden and their location in relation to industry. Silva Fennica 2015, 49, 1 .

AMA Style

Raul Fernandez-Lacruz, Fulvio Di Fulvio, Dimitris Athanassiadis, Dan Bergström, Tomas Nordfjell. Characteristics of unthinned biomass-dense forests in Sweden and their location in relation to industry. Silva Fennica. 2015; 49 (5):1.

Chicago/Turabian Style

Raul Fernandez-Lacruz; Fulvio Di Fulvio; Dimitris Athanassiadis; Dan Bergström; Tomas Nordfjell. 2015. "Characteristics of unthinned biomass-dense forests in Sweden and their location in relation to industry." Silva Fennica 49, no. 5: 1.

Journal article
Published: 01 January 2015 in Silva Fennica
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ACS Style

Simon Berg; Tomas Nordfjell; Dan Bergström. Effect of stump size and timing of stump harvesting on ground disturbance and root breakage diameter. Silva Fennica 2015, 49, 1 .

AMA Style

Simon Berg, Tomas Nordfjell, Dan Bergström. Effect of stump size and timing of stump harvesting on ground disturbance and root breakage diameter. Silva Fennica. 2015; 49 (5):1.

Chicago/Turabian Style

Simon Berg; Tomas Nordfjell; Dan Bergström. 2015. "Effect of stump size and timing of stump harvesting on ground disturbance and root breakage diameter." Silva Fennica 49, no. 5: 1.

Research article
Published: 12 November 2014 in Scandinavian Journal of Forest Research
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The objective was to study the effect of future harvesting and handling technologies on the cost and energy efficiency of supply chains for young dense thinnings. The system costs and energy requirements were modeled using type of stands, products delivered, and transport distances as variables. In total, 14 systems were analyzed, of which five represented future systems. The effects of increasing the payloads of off-road and road transportation of whole tree (WT) parts by 10%, 20%, and 30% were also analyzed. If boom-corridor thinning technologies, optimized bundle-harvesters, and load-compression devices are developed, on average, costs are reduced by 12–27% and 11–30% less energy is required when compared with present systems. For example, at an average harvested tree size of 22 dm3, the supply of WT using future technologies would reduce the cost by up to 15% and the energy requirements by 21%. These effects increase with reduced tree sizes and increased transportation distances. The effects of future technologies are especially significant for tree sizes below 30 dm3, representing a significant part of the potential that could be harvested annually in Sweden. Thus, there should be increased research and development of boom-corridor felling technology, bundle-harvesters, and load-compression devices.

ACS Style

Dan Bergström; Fulvio Di Fulvio. Comparison of the cost and energy efficiencies of present and future biomass supply systems for young dense forests. Scandinavian Journal of Forest Research 2014, 29, 793 -812.

AMA Style

Dan Bergström, Fulvio Di Fulvio. Comparison of the cost and energy efficiencies of present and future biomass supply systems for young dense forests. Scandinavian Journal of Forest Research. 2014; 29 (8):793-812.

Chicago/Turabian Style

Dan Bergström; Fulvio Di Fulvio. 2014. "Comparison of the cost and energy efficiencies of present and future biomass supply systems for young dense forests." Scandinavian Journal of Forest Research 29, no. 8: 793-812.