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Articles by Heikki Korpunen

Category: Research article

article id 67, category Research article
Pentti Niemistö, Heikki Korpunen, Ari Laurén, Marika Salomäki, Jori Uusitalo. (2012). Impact and productivity of harvesting while retaining young understorey spruces in final cutting of downy birch (Betula pubescens). Silva Fennica vol. 46 no. 1 article id 67. https://doi.org/10.14214/sf.67
Quite often Norway spruce (Picea abies (L.) Karsten) forms an understorey in birch dominated stands in Finland. Advantageous growth conditions for both storeys are present especially in downy birch (Betula pubescens Ehrh.) stands on drained fertile peatland. The most common way of regenerating mature Downy birch forest is clear cutting and replanting with Norway spruce, even if vital spruce seedlings or saplings was already growing under the birch. The aim of this study is to investigate the impact of retaining young understorey spruces on the productivity of harvesting and on the quality of the remaining stands in downy birch dominated stands with modern cut-to-length (CTL) machinery. Retaining undergrowth spruces decreased productivity of cutting in managed stands (600 stems/ha) by 6–9 per cent and in unmanaged stands (1200 stems/ha) by 11–17 per cent compared with clear cutting, where the understorey is not considered. Compared with the case where no understorey was present, the decrease in productivity was 10–17 per cent and 21–30 per cent respectively. In forwarding, retaining the undergrowth decreased the productivity of loading phases by 7–14 per cent. Harvesting treatment where spruces were retained produced an adequate stand structure for the future growing stock. Using this method, 14–24 per cent of the original spruces were totally destroyed while 25–44 per cent of spruces were destroyed when they were not considered for harvesting. The spatial variation of the remaining spruces was much better in the treatment where spruces were retained. Our study results shows that in this kind of two storey birch–spruce forests, the harvesting treatment where spruces are retained while cutting is the most acceptable and profitable method. It allows for a vital spruce sapling to continue growing, and avoids regeneration and tending costs or other harmful effects of clear-cut areas such as the freezing of young spruce plants and an increase in the ground water table.
  • Niemistö, Finnish Forest Research Institute, Parkano & Joensuu, Finland ORCID ID:E-mail:
  • Korpunen, Finnish Forest Research Institute, Parkano & Joensuu, Finland ORCID ID:E-mail:
  • Laurén, Finnish Forest Research Institute, Parkano & Joensuu, Finland ORCID ID:E-mail:
  • Salomäki, Finnish Forest Research Institute, Parkano & Joensuu, Finland ORCID ID:E-mail:
  • Uusitalo, Finnish Forest Research Institute, Parkano & Joensuu, Finland ORCID ID:E-mail: jori.uusitalo@metla.fi (email)
article id 177, category Research article
Tuomo Nurminen, Heikki Korpunen, Jori Uusitalo. (2009). Applying the activity-based costing to cut-to-length timber harvesting and trucking. Silva Fennica vol. 43 no. 5 article id 177. https://doi.org/10.14214/sf.177
The supply chain of the forest industry has increasingly been adjusted to the customer’s needs for precision and quality. This has changed the operative environment both in the forest and on the roads. As the total removal of timber is increasingly divided into more log assortments, the lot size of each assortment decreases and the time consumed in sorting the logs increases. In this respect, the extra assortments have made harvesting work more difficult and affected the productivity of both cutting and forest transport; this has thus increased the harvesting costs. An activity-based cost (ABC) management system is introduced for timber harvesting and long-distance transport, based on the cut-to-length (CTL) method, in which the logistic costs are assigned to timber assortments and lots. Supplying timber is divided into three main processes: cutting, forest transport, and long-distance transportation. An ABC system was formulated separately for each of these main operations. Costs were traced to individual stands and to timber assortment lots from a stand. The cost object of the system is thus a lot of timber that makes up one assortment that has been cut, forwarded, and transported from the forest to the mill. Application of the ABC principle to timber harvesting and trucking was found to be relatively easy. The method developed gives estimates that are realistic to actual figures paid to contractors. The foremost use for this type of costing method should be as a tool to calculate the efficiency of an individual activity or of the whole logistic system.
  • Nurminen, Metsätoimisto Tuomo Nurminen, Joensuuntie 5 B 8, FI-41800 Korpilahti, Finland ORCID ID:E-mail:
  • Korpunen, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland ORCID ID:E-mail:
  • Uusitalo, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland ORCID ID:E-mail:
article id 346, category Research article
Tuomo Nurminen, Heikki Korpunen, Jori Uusitalo. (2006). Time consumption analysis of the mechanized cut-to-length harvesting system. Silva Fennica vol. 40 no. 2 article id 346. https://doi.org/10.14214/sf.346
The time consumption and productivity of harvesting are dependent on stand conditions, the operators’ skills, working techniques and the characteristics of the forestry machinery. Even if the basic methods and machine types of the cut-to-length harvesting system have not changed significantly in 10 to 15 years, improvements in the operators’ competence, technical solutions in forest machinery and changes in the working environment have undoubtedly taken place. In this study, the objective was to discover the special characteristics in the time consumption of mechanized cutting and forest haulage in Finnish conditions. The empirical time study was conducted with professional operators and medium-sized single-grip harvesters and forwarders in final fellings and thinnings in easy terrain in central Finland. The models for effective time consumption in the work phases and total productivity were formed. Stem size, tree species and bucking affected the cutting, whereas timber density on the strip road, the average driving distance, load capacity, wood assortment and the bunching result of the harvester operator had an effect on the forest haulage performance. The results may be used in simulations, cost calculations and education.
  • Nurminen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: tuomo.nurminen@joensuu.fi (email)
  • Korpunen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Uusitalo, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland ORCID ID:E-mail:

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