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Silva Fennica vol. 48 no. 3 | 2014

Category : Research article

article id 1161, category Research article

Tiina Laine, Veli-Matti Saarinen. (2014). Comparative study of the Risutec Automatic Plant Container (APC) and Bracke planting devices. Silva Fennica vol. 48 no. 3 article id 1161. https://doi.org/10.14214/sf.1161

Keywords: productivity; regeneration; cost-efficiency; planting cost; mechanized tree planting

Highlights: As currently designed, the prototype Risutec APC fitted with an automatic feeding system offers no significant advantage over the Bracke planting device in terms of planting productivity or quality; Cost estimates suggest that an idealized automated feeding system could increase productivity and decrease unit costs.

Abstract | Full text in HTML | Full text in PDF | Author Info

The productivity of mechanized planting could be increased by minimizing the time spent manually reloading seedling cassettes. This study compared the work-time distribution, productivity and quality of the prototype Risutec APC fitted with an automatic feeding system and the commonly-used and manually-loaded Bracke P11.a. An approach of comparative time study was employed that compared performance of two operators using both machines in four sites where slash and stumps had been removed. Operating costs were estimated and compared for these two machines and an idealized machine with automatic feeding system (referred as AUT). AUT was assumed to be similar to the Bracke planting machine with the only difference being in automatic feeding. Productivity of the Risutec APC (196 seedlings per productive work hour [pl PWh₀^–1]) was lower than that of Bracke (244 pl PWh₀^–1), making the unit cost 35.7% higher. A large portion (17.6%) of the productive work time of Risutec APC was interrupted by malfunctions, so it cannot be considered robust and reliable yet. Quality of the planting work was reasonable for both machines. The results suggest that an idealized AUT could increase planting capacity (hectares per year [ha yr^–1]) by 15.4% and lower the unit cost (Euro per seedling [€ pl^–1]) by 4.7% compared to today’s machines. The importance of an automated feeding system increases with planting efficiency because relatively more time is spent reloading seedlings. Proper automatic feeding system could offer a cost-effective solution and could enhance productivity, but the Risutec APC has yet to meet the technical and economic standards required to be competitive.

Laine, Finnish Forest Research Institute (METLA), Suonenjoki Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: tiina.laine@metla.fi
Saarinen, Finnish Forest Research Institute (METLA), Suonenjoki Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: veli-matti.saarinen@metla.fi

article id 1153, category Research article

Anu Akujärvi, Ville Hallikainen, Mikko Hyppönen, Eero Mattila, Kari Mikkola, Pasi Rautio. (2014). Effects of reindeer grazing and forestry on ground lichens in Finnish Lapland. Silva Fennica vol. 48 no. 3 article id 1153. https://doi.org/10.14214/sf.1153

Keywords: forest management; timber harvesting; reindeer herding; pastures; lichen cover; lichen biomass

Highlights: Both reindeer grazing and forestry affect the cover and biomass of reindeer lichens; Reindeer grazing has bigger impact than forestry; The lichen cover was about five-fold and the biomass about fifteen-fold in the ungrazed (fenced) sites than in the grazed ones; The decrease of not only the biomass, but also the cover of lichens, is alarming.

Abstract | Full text in HTML | Full text in PDF | Author Info

Reindeer husbandry and forestry are practiced in the same areas in northern Fennoscandia. Reindeer pastures have largely deteriorated. We aimed to quantify the separate and combined effects of reindeer grazing and forestry on the amount of ground lichens. To do this, we mapped and inventoried all larger enclosures (49) in Finnish Lapland where forest management practices were similar in both sides of the fence. The average time since fencing was 43 years. We recorded the cover and estimated dry biomass of ground lichens, as well as parameters describing forest stand characteristics. The effect of reindeer grazing on both the cover and estimated dry biomass of lichens was clear: in the ungrazed (fenced) sites, the lichen cover (35.8%) was on average 5.3-fold and the dry biomass (1929 kg ha^–1) 14.8-fold compared with the corresponding estimates in the grazed sites (6.8% and 130 kg ha^–1). The effect of forestry on lichens was smaller. In the grazed stands the cover and biomass of lichens were higher in the mature stands compared to the younger stand development classes, whereas in the ungrazed stands there were no significant differences between the development classes. Both reindeer grazing and forestry affect the cover and biomass of ground lichens. The influence of reindeer grazing is, however, much heavier than that of forestry. The decrease of not only the biomass, but also the lichen cover, is alarming. The decrease of lichen cover may hinder the recovery of reindeer pastures, which in the long run endangers the sustainability of reindeer husbandry.

Akujärvi, Finnish Environment Institute, Helsinki, Finland E-mail: anu.akujarvi@ymparisto.fi
Hallikainen, Finnish Forest Research Institute, Northern Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: ville.hallikainen@metla.fi
Hyppönen, Finnish Forest Research Institute, Northern Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: mikko.hypponen@metla.fi
Mattila, Finnish Forest Research Institute, Northern Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: eero.mattila@metla.fi
Mikkola, Finnish Forest Research Institute, Northern Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: kari.mikkola@metla.fi
Rautio, Finnish Forest Research Institute, Northern Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: pasi.rautio@metla.fi

article id 1120, category Research article

Ilari Lehtonen, Petri Hoppula, Pentti Pirinen, Hilppa Gregow. (2014). Modelling crown snow loads in Finland: a comparison of two methods. Silva Fennica vol. 48 no. 3 article id 1120. https://doi.org/10.14214/sf.1120

Keywords: climate; forests; snow damage; rime; dry snow; wet snow; frozen snow

Highlights: A new method to model crown snow loads is presented and compared with a previously published simpler method; The heaviest crown snow loads in Finland are found to typically occur in the eastern parts of the country; The relative importance of different snow load types varies between different regions of Finland.

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The spatial occurrence of heavy crown snow loads in Finland between 1961 and 2010 is studied by using for the first time a model that classifies the snow load into four different types: rime, dry snow, wet snow and frozen snow. In producing this climatology, we used meteorological observations made at 29 locations across Finland. The model performance is evaluated against classified daily images of canopy snow cover and with the help of two short case studies. The results are further compared to those achieved with a simpler method used in previous studies. The heaviest crown snow loads are found to occur typically in eastern Finland. The new method reveals that this holds not only for the total snow loads but also for the different snow load types, although there are certain differences in their geographical occurrence. The greatest benefit achieved with the new method is the inclusion of rime accretion. The forests most prone to heavy riming are those located on tree-covered hills in northern Finland, but as the terrain elevation affects riming efficiency greatly, these small-scale variations in the snow load amounts could not be described in this study in great detail. Moreover, the results are more inaccurate in northern Finland where variations in the terrain elevation are greater than elsewhere. Otherwise, the largest uncertainties in this study are related to wind speed measurements and possibly partly because of that, we were not able to detect any significant trends in the crown snow-load amounts over the study period.

Lehtonen, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland E-mail: ilari.lehtonen@fmi.fi
Hoppula, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland E-mail: petri.hoppula@fmi.fi
Pirinen, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland E-mail: pentti.pirinen@fmi.fi
Gregow, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland E-mail: hilppa.gregow@fmi.fi

article id 1087, category Research article

Ilkka Korpela, Lauri Mehtätalo, Lauri Markelin, Anne Seppänen, Annika Kangas. (2014). Tree species identification in aerial image data using directional reflectance signatures. Silva Fennica vol. 48 no. 3 article id 1087. https://doi.org/10.14214/sf.1087

Keywords: forestry; reflectance calibration; BRDF; mixed-effects modeling; Monte-Carlo simulation

Highlights: Multispectral reflectance data showed a strong and spectrally correlated tree effect; There was no gain in species classification from using species-specific differences of directional reflectance in real data and only a marginal improvement in simulated data; The directional signatures extracted in multiple images are obscured by the intrinsic within-species variation, correlated observations and inherent reflectance calibration errors.

Abstract | Full text in HTML | Full text in PDF | Author Info

Tree species identification using optical remote sensing is challenging. Modern digital photogrammetric cameras enable radiometrically quantitative remote sensing and the estimation of reflectance images, in which the observations depend largely on the reflectance properties of targets. Previous research has shown that there are species-specific differences in how the brightness observed changes when the viewing direction in an aerial image is altered. We investigated if accounting for such directional signatures enhances species classification, using atmospherically corrected, real and simulated multispectral Leica ADS40 line-camera data. Canopy in direct and diffuse illumination were differentiated and species-specific variance-covariance structures were analyzed in real reflectance data, using mixed-effects modeling. Species classification simulations aimed at elucidating the level of accuracy that can be achieved by using images of different quality, number and view-illumination geometry. In real data, a substantial variance component was explained by tree effect, which demonstrates that observations from a tree correlate between observation geometries as well as spectrally. Near-infrared band showed the strongest tree effect, while the directionality was weak in that band. The gain from directional signatures was insignificant in real data, while simulations showed a potential gain of 1–3 percentage points in species classification accuracy. The quality of reflectance calibration was found to be important as well as the image acquisition geometry. We conclude that increasing the number of image observations cancels out random observation noise and reflectance calibration errors, but fails to eliminate the tree effect and systematic calibration inaccuracy. Directional reflectance constitutes a marginal improvement in tree species classification.

Korpela, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014, Finland E-mail: ilkka.korpela@helsinki.fi
Mehtätalo, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: lauri.mehtatalo@uef.fi
Markelin, Department of Remote Sensing and Photogrammetry, Finnish Geodetic Institute, P.O. Box 15, FI-02431 Masala, Finland E-mail: lauri.markelin@fgi.fi
Seppänen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: anne.seppanen@arbonaut.com
Kangas, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014, Finland E-mail: annika.kangas@helsinki.fi

article id 1054, category Research article

Karin Kolis, Juhana Hiironen, Esa Ärölä, Arvo Vitikainen. (2014). Effects of sale-specific factors on stumpage prices in Finland. Silva Fennica vol. 48 no. 3 article id 1054. https://doi.org/10.14214/sf.1054

Keywords: pulpwood; timber trade; standing timber sales; hedonic price; sawlogs; non-industrial forest owners

Highlights: Data on 4824 individual sales were used to estimate which factors affect stumpage prices; The time of sale, seasonal harvest restrictions, the location and the assortment affected prices; Larger total volumes and shorter forest haulage distances raised unit prices; A higher percentage of the assortment and percentage of sawlogs within the sale corresponded to higher prices.

Abstract | Full text in HTML | Full text in PDF | Author Info

Buyers of standing timber take not only the market situation but also the harvest costs into consideration when making purchase offers. In Finland, 85% of all timber is sold as standing timber, but there is little information for forest owners and third parties regarding how differences in harvest costs are reflected in the stumpage prices. This article analyses the relationship between sale-specific factors and stumpage prices in Finland. Data on 4824 standing timber sales between 2008 and 2012 were gathered from five local Forest Management Associations. Regression analyses were run on the stumpage prices (euros m^–3) paid for sawlogs and pulpwood. Seasonal harvest restrictions, the volume of the sale and the timber assortment influenced stumpage prices, as did the presence of forest damages. Prices also differed over time and between locations. Furthermore, the forest haulage distance was statistically significant for pulpwood. The results suggest that the size of the individual sales and the composition of assortments affect the income owners earn from their forest. The results can be used to estimate stumpage prices and the monetary impacts on forest owners of procedures such as forest road network planning and land consolidation, as well as for valuation of forests.

Kolis, Aalto University, Department of Real Estate, Planning and Geoinformatics, P.O. Box 12200, FI-00076 Aalto, Finland E-mail: karin.kolis@aalto.fi
Hiironen, Aalto University, Department of Real Estate, Planning and Geoinformatics, P.O. Box 12200, FI-00076 Aalto, Finland E-mail: juhana.hiironen@aalto.fi
Ärölä, National Land Survey of Finland, Production Support Services, P.O. Box 84, FI-00521 Helsinki, Finland E-mail: esa.arola@nls.fi
Vitikainen, Aalto University, Department of Real Estate, Planning and Geoinformatics, P.O. Box 12200, FI-00076 Aalto, Finland E-mail: arvo.vitikainen@aalto.fi

Category : Review article

article id 1095, category Review article

Jonas Fridman, Sören Holm, Mats Nilsson, Per Nilsson, Anna Hedström Ringvall, Göran Ståhl. (2014). Adapting National Forest Inventories to changing requirements – the case of the Swedish National Forest Inventory at the turn of the 20th century. Silva Fennica vol. 48 no. 3 article id 1095. https://doi.org/10.14214/sf.1095

Keywords: remote sensing; sampling; sample plot inventory; forest state; ENFIN; harmonization

Highlights: National Forest Inventories supply invaluable long term time series of forest state. Recent developments and international harmonization of modern NFIs widen the scope to even include ecosystem goods, e.g. biodiversity and carbon sequestration. The combination of NFI field data with remote sensing techniques can give good estimates for areas smaller than national and regional level.

Abstract | Full text in HTML | Full text in PDF | Author Info

National Forest Inventories (NFIs) are becoming increasingly important worldwide in order to provide information about the multiple functions of forests, e.g. their provision of raw materials to industry, biodiversity and their capacity to store carbon for mitigating climate change. In several countries the history of NFIs is very long. For these countries a specific challenge is to keep the inventories up-to-date without sacrificing the advantages associated with long time series. At the turn of the 20th century European NFIs faced some major challenges. In this article we describe the history and the recent developments of the Swedish NFI as an example from which general observations are made and discussed. The Swedish NFI started in 1923 and has evolved from an inventory with a narrow focus on wood resources to an inventory today which aims to provide information about all major forest ecosystem services. It can be concluded that the traditional approaches of most European NFIs, e.g. to collect data through sample plot field inventories, has proved to be applicable even for a wide range of new information requirements. Specifically, detailed data about land use, trees, vegetation, and soils has found new important uses in connection with biodiversity assessments and the estimation of greenhouse gas emissions. Though time-consuming and difficult, making NFI information comparable across countries through harmonization appears to be a useful approach. The European National Forest Inventory Network (ENFIN) was formed in 2003 and has been successful in pan-European NFI harmonization.

Fridman, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden E-mail: jonas.fridman@slu.se
Holm, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden E-mail: soren.holm@slu.se
Nilsson, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden E-mail: mats.nilsson@slu.se
Nilsson, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden E-mail: per.nilsson@slu.se
Ringvall, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden E-mail: Anna.Ringvall@slu.se
Ståhl, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden E-mail: goran.stahl@slu.se

Category : Research note

article id 1136, category Research note

Håkan Lideskog, Back Tomas Ersson, Urban Bergsten, Magnus Karlberg. (2014). Determining boreal clearcut object properties and characteristics for identification purposes. Silva Fennica vol. 48 no. 3 article id 1136. https://doi.org/10.14214/sf.1136

Keywords: forestry; forest regeneration; clearcut obstacles; terrain description; terrain conditions; site properties

Highlights: We define the quantitative properties and qualitative characteristics of stumps, stones, slash, and roots, the most important objects interacting with machine activities after clearcutting; We develop a flowchart showing how a computer-aided system using clearcut object identification should be executed.

Abstract | Full text in HTML | Full text in PDF | Author Info

After clearcutting, machines traffic the clearcut conducting different silvicultural activities. Many objects on a forest clearcut (slash residues, stones, stumps and roots) may disturb e.g. site preparation and planting. This paper describes properties and characteristics of these objects. A flowchart was developed that describes a possible computer-aided system that identifies the objects, and ultimately, makes a machine avoid or target them. A system for obstacle identification creates conditions for further technical development and (semi)automation of e.g., site preparation, mechanized planting, and stump removal.

Lideskog, Division of Product and Production Development, Luleå University of Technology, SE-97187 Luleå, Sweden E-mail: hakan.lideskog@ltu.se
Ersson, Department of Forest Biomaterials and Technology, SLU, SE-90183 Umeå, Sweden E-mail: back.tomas.ersson@slu.se
Bergsten, Department of Forest Biomaterials and Technology, SLU, SE-90183 Umeå, Sweden E-mail: urban.bergsten@slu.se
Karlberg, Division of Product and Production Development, Luleå University of Technology, SE-97187 Luleå, Sweden E-mail: magnus.karlberg@ltu.se

article id 1126, category Research note

Rebecka Mc Carthy, Per Magnus Ekö, Lars Rytter. (2014). Reliability of stump sprouting as a regeneration method for poplars: clonal behavior in survival, sprout straightness and growth. Silva Fennica vol. 48 no. 3 article id 1126. https://doi.org/10.14214/sf.1126

Keywords: Populus spp.; coppice regeneration; vegetative regeneration; short-rotation forestry

Highlights: Clonal differences were found in stump sprout survival; Clonal differences occurred in sprout straightness; It is uncertain if the ability to produce a high number of stump sprouts is beneficial.

Abstract | Full text in HTML | Full text in PDF | Author Info

The interest in poplars (Populus spp.) has increased globally as a result of the current incentive to expand the use of biomass for energy. So far, knowledge about poplar stump sprouting is generally poor. The objective of this study was to investigate poplar stump sprouting as regeneration method in harvested plantations. A 19-year-old poplar clonal test, including 23 different clones, on former arable land was harvested in the winter. After one year, stumps were assessed for sprout survival, sprout straightness, number of sprouts, sprout height and basal diameter. Differences between clones were found for survival and sprout straightness. Clonal differences were also found in mean size of sprouts (basal diameter and height). However, no differences were found between clones when comparing size of the tallest sprout or number of sprouts produced on stumps. This study indicates that stump sprouts from various poplar clones differ in survival, sprout straightness and mean growth, which should be taken into account when planning for the next tree generation. The study needs to be complemented with other studies to better assess sprouting characteristics for different clones.

Mc Carthy, Forestry Research Institute of Sweden, Skogforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden & Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: rebecka.mccarthy@skogforsk.se
Ekö, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: Per.Magnus.Eko@slu.se
Rytter, Forestry Research Institute of Sweden, Skogforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden E-mail: lars.rytter@skogforsk.se

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