Karin Vestlund, Tomas Nordfjell, Lars Eliasson, Anders Karlsson. (2006). A decision support system for selective cleaning. Silva Fennica vol. 40 no. 2 article id 343. https://doi.org/10.14214/sf.343

Keywords: forestry; pre-commercial thinning; automation; practical cleaning

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Cleaning (pre-commercial thinning) costs have increased relative to logging and regeneration costs, creating a desire for rationalisation. Cleaning with robots may be a solution, but automating stem selections requires a decision support system (DSS) capable of rendering acceptable results. The aims were to develop a DSS for automation of individual stem selections in practical cleaning, and to test, using simulations, if it renders acceptable results. Data on 17 young forest stands were used to develop a DSS that selects stems by species, position (including distance and density parameters), diameter, and damage. Six simulations were run, following the DSS, with different target settings for density, percentage of deciduous stems and minimum distance between stems. The results depend on the initial state of the stands, but generally met the requested targets in an acceptable way. On average, the density results deviated by –20% to +6% from the target values, the amount of deciduous stems shifted towards the target values, and the proportion of stems with defined damaged decreased from initially 14–90% to 4–13%. The mean diameter at breast height increased and the minimum allowed distance between stems was never violated. The simulation results indicate that the DSS is operational. However, for implementation in robotics a crucial problem is to automatically perceive the selected attributes, so additional simulations with erroneous data were run. Correct measurements of diameters are less crucial than to find the majority of the trees and the majority of trees with damages.

Vestlund, Swedish University of Agricultural Sciences, Department of Silviculture, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: karin.vestlund@ssko.slu.se
Nordfjell, Swedish University of Agricultural Sciences, Department of Forest Resource Management and Geomatics, SE-901 83 Umeå, Sweden E-mail: tn@nn.se
Eliasson, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: le@nn.se
Karlsson, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: ak@nn.se

article id 683, category Research article

Anders Karlsson, Arne Albrektson, Anders Forsgren, Lennart Svensson. (1998). An analysis of successful natural regeneration of downy and silver birch on abandoned farmland in Sweden. Silva Fennica vol. 32 no. 3 article id 683. https://doi.org/10.14214/sf.683

Keywords: Betula pendula; site preparation; Betula pubescens; afforestation; arable land; site conditions

Abstract | View details | Full text in PDF | Author Info

To improve our understanding of factors influencing the success of natural regeneration with downy birch (Betula pubescens Ehrh.) and silver birch (Betula pendula Roth) on abandoned farmlands, a survey was conducted to analyse the effects of site conditions and site preparation characteristics. The study was based on a sample plot inventory conducted in one northern and one southern district of Sweden, in which 29 successfully established, naturally regenerated stands, about to be cleaned or thinned, were assessed. Radical site preparation increased stand density and uniformity of established regeneration, and gave faster initial development, than establishment without site preparation on former leys or meadows. Large proportions of the total sample area were classified as moist, and soils consisting of sand–fine sand or peat were frequent. The frequency of birch stems was highest in mesic sites, and on soils consisting of sand, sand–fine sand or peat. Distances to seed-trees were generally shorter than 80 m, and downy birch was the dominant species in most stands.

Karlsson, Swedish University of Agricultural Sciences, Department of Silviculture, S-901 83 Umeå, Sweden E-mail: anders.karlsson@ssko.slu.se
Albrektson, Swedish University of Agricultural Sciences, Department of Silviculture, S-901 83 Umeå, Sweden E-mail: aa@nn.se
Forsgren, Swedish University of Agricultural Sciences, Department of Silviculture, S-901 83 Umeå, Sweden E-mail: af@nn.se
Svensson, Swedish University of Agricultural Sciences, Department of Silviculture, S-901 83 Umeå, Sweden E-mail: ls@nn.se

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