Predicting knottiness of Scots pine stems for quality bucking

Mäkinen, Harri; Korpunen, Heikki; Raatevaara, Antti; Heikkinen, Jere; Alatalo, Juha M.; Uusitalo, Jori

doi:10.1007/s00107-019-01476-x

Cited by 9 publications

(6 citation statements)

References 40 publications

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“…This may be influenced by the origin of the sawn timber from the core part of the butt logs with a high proportion of juvenile wood. In contrast, general studies on knots indicate that the correlation does exist and is connected with structural changes within and around the knots (Oh et al 2009;Mäkinen et al 2020). The present study is an introduction to broader studies on the verification of the properties of Polish pine wood.…”

Section: Discussionmentioning

confidence: 65%

Elastic moduli of butt-end logs and the variable knots distribution in Scots pine from Western Poland

Mirski

Wieruszewski

Trociński

et al. 2021

BioRes

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In studies on Polish pine wood, the parameters determining its usefulness for processing are highly variable. In contrast, international studies on the optimum utilization of coniferous sawn wood describes its visual features as those indicating the distribution of defects and their impact on the selected mechanical and physical properties of sawn wood. Knottiness is one of the qualitative properties of sawn wood that is essential for wood grading. The objective of this study was to determine a correlation between variable knots and their soundness on the one hand and their selected strength parameters on the other. One of the basic issues of this work includes structural timber optimization. For Polish sawn wood, these indicators are still relatively new. The study material involved edged butt-end log lumber from a 120-year-old forest stand. The results confirmed a correlation between knots frequency and modulus of elasticity. The correlation was strong, indicating that sound knots play a major role in the process of the strength assessments. The study did not demonstrate a significant share of rotten knots and their effect on strength.

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Section: Discussionmentioning

confidence: 65%

Elastic moduli of butt-end logs and the variable knots distribution in Scots pine from Western Poland

Mirski

Wieruszewski

Trociński

et al. 2021

BioRes

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“…Suitability of a log for structural timber could be further estimated by measuring the force needed for crosscutting the stem (Sandak et al 2017) which essentially reflects the density of a wood. In appearance grading, log end face image could be utilised to estimate other sawlog features, such as knottiness (Uusitalo and Isotalo 2005;Mäkinen et al 2019), that have traditionally been predicted based on external features, such as dead branch height (Uusitalo and Kivinen 1998). Overall, a combination of various sensors could provide valuable information throughout the supply chain for sawmills, and the plywood or veneer industries.…”

Section: Discussionmentioning

confidence: 99%

Log end face image and stem tapering indicate maximum bow height on Norway spruce bottom logs

et al. 2020

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In cut-to-length logging, the harvester operator adjusts the bucking in accordance with visible defects on processed stems. Some of the defects, such as a sweep on the bottom of the stem, decrease the yield and quality of sawn products and are difficult for the operator to notice. Detecting the defects with improved sensors would support the operator in his qualitative decision-making and increase value recovery of logging. Predicting the maximum bow height of the bottom log in Norway spruce (Picea abies (L.) Karst.) with log end face image and stem taper was investigated with two modelling approaches. A total of 101 stems were selected from five clear-cut stands in southern Finland. The stems were crosscut and taper measured, and the butt ends of the bottom logs were photographed. The stem diameter, out-of-roundness, and pith eccentricity were measured from the images while the max. bow height was measured by a 3D log scanner at a sawmill. The bottom logs with an eccentric pith had higher max. bow height. In addition, a highly conical bottom part of the stem was more common on the bottom logs with a large max. bow height. Applying both log end face image and stem taper measurements gave the best model fit and detection accuracy (76%) for bottom logs with a large max. bow height. The results indicate that the log end face image and stem taper measurements can be utilised to aid harvester operator in deciding an optimised length for logs according to the bow height.

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“…The tight interdependencies between primary and secondary growth are due to the wood formation responding to intrinsic (increasing size) and extrinsic (climate and competition) factors as described in the Introduction. With detailed inputs from TLS point clouds accompanied by wood property references, any of the above-mentioned models could be utilized in translating allometric growth responses into vertical and radial gradients of wood properties such as knottiness, wood density, or fiber properties (Duchateau et al 2013;Eberhardt et al 2019;Ikonen et al 2003;Mäkelä et al 2010;Mäkinen et al 2020;Moberg 2006;Osborne and Maguire 2016) (Figures 1 and 4).…”

Section: Applications In the Modeling Of Wood Properties And Wood Quamentioning

confidence: 99%

“…The wood quality indicators listed above can be used to estimate many key wood properties when used as descriptors of wood formation (Figure 1). Models for predicting wood properties from the characteristics of standing timber could be used to provide additional information not directly obtainable from log dimensions and to produce virtual sawlogs for more flexible definitions of grading rules and optimization of the bucking and sawing patterns (Mäkelä et al 2010;Mäkinen et al 2020). Their inclusion in future remote-sensing-aided forest management and wood procurement planning could improve the precision of forestry operations and forest use, with possibly positive implications for the sustainability of managed forests.…”

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confidence: 99%

Assessing wood properties in standing timber with laser scanning

Pyörälä¹

2020

Diss. For.

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Managed forests play crucial roles in ongoing climatic and environmental changes. Among other things, wood is capable of sinking and storing carbon in both standing timber and wood products. To promote these positive effects, more precise planning is required that will ensure sustainable forest management and maximal deposition of harvested wood for long-term applications. Information on wood properties plays a key role; i.e. the wood properties can impact the carbon stocks in forests and the suitability of wood for structural timber. With respect to the theoretical background of wood formation, stem, crown, and branching constitute potential inputs (i.e. wood quality indicators) to allometric wood property, tree biomass, and wood quality models. Due to the complex nature of wood formation, measurements of wood quality indicators that could predict wood properties along the relevant directions of variation have previously been elusive in forest inventories. However, developments in laser scanning from aerial and terrestrial platforms support more complex mapping and modeling regimes based on dense three-dimensional point clouds. The aim here was to determine how wood properties could be estimated in remotesensing-aided forest inventories. For this purpose, methods for characterizing select wood quality indicators in standing timber, using airborne and terrestrial laser scanning (ALS and TLS, respectively) were developed and evaluated in managed boreal Scots pine (Pinus sylvestris L.) forests. Firstly, the accuracies of wood quality indicators resolved from TLS point clouds were assessed. Secondly, the results were compared with x-ray tomographic references from sawmills. Thirdly, the accuracies of tree-specific crown features delineated from the ALS data in predictive modeling of the wood quality indicators were evaluated. The results showed that the quality and density of point clouds significantly impacted the accuracies of the extracted wood quality indicators. In the assessment of wood properties, TLS should be considered as a tool for retrieving as dense stem and branching data as possible from carefully selected sample trees. Accurately retrieved morphological data could be applied to allometric wood property models. The models should use tree traits predictable with aerial remote sensing (e.g. tree height, crown dimensions) to enable extrapolations. As an outlook, terrestrial and aerial remote sensing can play an important role in filling in the knowledge gaps regarding the behavior of wood properties over different spatial and temporal extents. Further interdisciplinary cooperation will be needed to fully facilitate the use of remote sensing and spatially transferable wood property models that could become useful in tackling the challenges associated with changing climate, silviculture, and demand for wood.

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Predicting knottiness of Scots pine stems for quality bucking

Cited by 9 publications

References 40 publications

Elastic moduli of butt-end logs and the variable knots distribution in Scots pine from Western Poland

Elastic moduli of butt-end logs and the variable knots distribution in Scots pine from Western Poland

Log end face image and stem tapering indicate maximum bow height on Norway spruce bottom logs

Assessing wood properties in standing timber with laser scanning

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