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| 2. |
- Eklund, Leif, et al.
(författare)
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Enhanced growth and ethylene increases spiral grain formationin Picea abies and Abies balsamea trees
- 2003
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Ingår i: Trees. - : Springer. - 0931-1890 .- 1432-2285. ; 17:1, s. 81-86
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Tidskriftsartikel (refereegranskat)abstract
- Spiral grain angle in Norway spruce (Piceaabies) trees and balsam fir (Abies balsamea) seedlingswas investigated in relation to growth rate, endogenousand applied ethylene. Trees from stands of Norwayspruce, which were irrigated and fertilised in order to enhancegrowth, and trees having different growth rates innon-treated stands were studied. Stem growth rate at thestand level (m3 ha–1 year–1) was measured annually, orby means of microscopy on stem sections as the numberand size of tracheids produced. Enhanced growth increasedethylene evolution and maintained a high levelof left-handed spiral grain angle in comparison to slower-growing trees. An increased number of earlywoodtracheids in fast growing trees was correlated to a moreleft-handed spiral grain angle. Ethrel, applied to stems ofbalsam fir seedlings, increased the internal ethylene levelsin parallel with increased left-handed spiral grain angle.The results indicate that ethylene regulates the extentof spiral grain angle.
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| 3. |
- Eklund, Leif, et al.
(författare)
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Spiral grain from an environmental, genetic and economical point of view
- 2000
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Ingår i: The Tree.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Characteristic of wood is that its behavior is strongly orthotropic due to the internal structure of the material and dependent on moisture and temperature. In addition, the material is characterized by a strong variation of the properties in the radial direction. Another important property that affects the behavior of wood is spiral grain, causing the direction of the fibers to deviate from the longitudinal direction of the tree. It is hardly possible to assess spiral grain in the woods, no rejection of severe spiraled trees are done before the log arrives into the sawmill. If a method for on site rejection is available, and the severest spiraled trees, 2-10%, could be avoided in the shipment to the sawmill substantial money could be saved in the forest industry. The causes of spiral grain have been thoroughly discussed through the years and the debate about the environmental and genetic impact on the phenomenon is still not settled. We present evidence for a direct effect of wind on the degree of spiral grain. We also present evidence for a putative thinning effect on spiral grain that is probably connected to wind. Additionally we also present evidence for a strong genetic impact on the formation of spiral grain in conifer trees. In another study mechanical properties such as shape stability has been investigated for the same trees. In some of the logs it may therefore be possible to quantify the relation between spiral grain and distortion in sawn timber.
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| 4. |
- Eklund, Leif, et al.
(författare)
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The influence of wind on spiral grain formation in conifer trees
- 2000
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Ingår i: Trees. - : Springer. - 0931-1890 .- 1432-2285. ; 14, s. 324-328
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Tidskriftsartikel (refereegranskat)abstract
- The correlation between spiral grain formationand crown asymmetry was investigated in 18 Scots pine(Pinus sylvestris L.) and 17 Norway spruce [Picea abies(L.) Karst.] trees selected from clones of each speciesgrowing in the south of Sweden. The angle between thelongitudinal direction of the tracheids in the outermostyear ring compared to the longitudinal direction of thestem was measured by scribing lines which followed thedirection of the tracheids. The crown asymmetry wasmeasured by taking photographs of the trees followed bya simple picture analysis of the tree. Wind data for thegrowing seasons of 1997 and 1998 were obtained fromthe Swedish Meteorological and Hydrological Institute.The results showed a significant correlation between theangle of the tracheids compared to the stem longitudinaldirection going from a left-handed angle if the trees hada crown projected to the north towards a right-handedangle the more the crown projects to the south.
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| 5. |
- Gjerdrum, Peder, et al.
(författare)
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Spiral grain in Norway spruce : constant change in grain angle in Scandinavian sawlogs
- 2002
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Ingår i: Forestry (London). - : Oxford University Press. - 0015-752X .- 1464-3626. ; 75:2, s. 163-170
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Tidskriftsartikel (refereegranskat)abstract
- Any evident grain deviation will reduce strength and increase warp in sawn timber. To describe the magnitude and variance of grain angle in Norway spruce, specimens from 1046 Norwegian sawlogs and 380 logs from Sweden and Finland were examined. For individual specimens, grain angle outside the innermost zone closest to the pith might be expressed by a simple linear function of radial distance from the pith. The intercept and inclination of this function are close to bivariate normally distributed with mean values (SD) of 2.7° mm−1 (1.9) and −0.039° mm−1 (0.037), respectively. Inclination is less negative for wider annual rings (r = 0.3), and intercept and inclination are negatively correlated (r = −0.4). The constant rate of change indicates inherited property rather than influence of any dynamic, external stimulus. No predictor for grain angle pattern was found. The linear model leads to simplifications both when observing the grain angle in the forestry, and in calculations of strength properties and distortion in the timber industry.
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| 6. |
- Hallingbäck, Henrik, et al.
(författare)
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Optimal timing of early genetic selection for sawn timber traits in Picea abies
- 2018
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Ingår i: European Journal of Forest Research. - : Springer. - 1612-4669 .- 1612-4677. ; 137:4, s. 553-564
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Tidskriftsartikel (refereegranskat)abstract
- In breeding Norway spruce, selection for improved growth and survival is performed at age 10-15 years in order to optimize genetic gain per year. We investigated whether a selection based on wood traits such as density and grain angle, measured under bark in the field at the same age would be informative enough with respect to structural quality traits of sawn boards. To achieve this objective, a sawing study was conducted on the butt logs of 401 trees from a 34-year-old Norway spruce progeny trial situated in southern Sweden. Stem discs were excised from the top of the logs and radial profile data of grain angle, and wood density was recorded for specific annual rings. The sawn and dried boards were assessed for structural traits such as twist, board density, bending stiffness (static modulus of elasticity, sMoE) and bending strength (modulus of rupture, MoR). Additive genetic correlations (r (a)) between single annual ring density measurements and board density, sMoE and MoR were consistently strong (r (a)> 0.7) for annual rings 5-13. Genetic correlations of similar magnitude between grain angle and board twist were estimated for all investigated annual rings (from 2 to around 26 under bark). Consequently, it was found that indirect selection for wood density and grain angle at the tree age 10-16 years would result in more genetic gain per year than selection at later ages. This makes it feasible to perform simultaneous selection of progeny in the field for both growth and wood traits at similar ages.
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| 7. |
- Hannrup, Björn, et al.
(författare)
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Genetic parameters for spiral grain in Scots pine and Norway spruce
- 2003
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Ingår i: Silvae Genetica. - 0037-5349. ; 52:5-6, s. 215-220
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Tidskriftsartikel (refereegranskat)abstract
- Genetic parameters were estimated for grain angle, growth and exterior quality traits in two 18-year-old Scots pine (Pinus sylvestris L.) progeny trials and for grain angle and growth traits in two 12-year-old clonal trials of Norway spruce (Picea abies L. Karst.). Mean grain angles ranged 1.4 to 2.0 degrees and 2.1 to 2.6 degrees in the Scots pine and Norway spruce trials, respectively. Heritabilities for grain angle were high in Scots pine (h2>0.40) and moderate in Norway spruce (H2>0.30). The genetic standard deviations were around or slightly below one degree. In general, grain angle was genetically and phenotypically uncorrelated with the growth and exterior quality traits. All traits showed low amount of genotype by environment interaction and there was no tendency of grain angle being a more stable traits than the other traits studied. A newly developed measurement device for grain angle where the grain angle is revealed by a wedge that is pushed through the bark into the wood and follows the inclination of the tracheids was tested and found suitable for measurements in genetic tests.
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| 8. |
- Hu, Min, 1979-, et al.
(författare)
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Growth layer and fibre orientation around knots in Norway spruce : a laboratory investigation
- 2018
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Ingår i: Wood Science and Technology. - : Springer. - 0043-7719 .- 1432-5225. ; 52:1, s. 7-27
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Tidskriftsartikel (refereegranskat)abstract
- The strength of structural timber largely depends on the occurrence of knots and on the local material directions in the surroundings of such knots. There is, however, a lack of methods for establishing a full dataset of the local material directions. The present research aims at the development and application of a laboratory method to assess the geometry of growth layers and the orientation of fibres in a high-resolution 3D grid within wood specimens containing knots. The laboratory method was based on optical flatbed scanning and laser scanning, the former resulting in surface images and the latter, utilizing the tracheid effect, resulting in in-plane fibre angles determined in high-resolution grids on scanned surfaces. A rectangular solid wood specimen containing a single knot was cut from a tree in such a way that it could be assumed that a plane of symmetry existed in the specimen. By splitting the specimen through this plane through the centre line of the knot, two new specimens with assumed identical but mirrored properties were achieved. On one of the new specimens, the longitudinal-radial plane was subsequently scanned, and the longitudinal–tangential plane was scanned on the other. Then, by repeatedly planing off material on both specimens followed by scanning of the new surfaces that gradually appeared, 3D coordinate positions along different growth layers and 3D orientation of fibres in a 3D grid were obtained. Comparisons between detected fibre orientation and growth layer geometry were used for the assessment of the accuracy obtained regarding 3D fibre orientation. It was shown that the suggested method is well suited to capture growth layer surfaces and that it provides reliable information on 3D fibre orientation close to knots. Such knowledge is of great importance for understanding the properties of timber including knots. The quantitative data obtained are also useful for calibration of model parameters of general models on fibre orientation close to knots.
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| 9. |
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| 10. |
- Högberg, Karl-Anders, et al.
(författare)
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The potential for the genetic improvement of sawn timber traits in Picea abies
- 2014
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Ingår i: Canadian Journal of Forest Research. - : NRC Research Press. - 0045-5067 .- 1208-6037. ; 44:4, s. 273-280
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluated the potential for the selective genetic improvement of the structural quality traits important in sawn Norway spruce (Picea abies (L.) Karst.) timber based on early and nondestructively assessed field traits. From a 34-year-old Norway spruce trial situated in southern Sweden, 401 butt logs were sampled and sawn to produce two 50 × 100 mm boards that were dried to an 18% moisture content. Structural quality traits were assessed, and genetic parameters were estimated, including additive genetic variance, heritability, and their genetic correlations with field traits. Board twisting, density, and modulus of elasticity (MOE, stiffness) were found to have appreciable heritabilities (0.23–0.44). Board twist was found to have a strong genetic correlation with grain angle measured under bark in the field (0.93), and both board MOE and density exhibited strong genetic correlations with field-assessed pilodyn penetration (–0.75 and –0.91, respectively). Although these observations were made on a thinning material comprising mainly juvenile wood, they nonetheless suggest grain angle and pilodyn penetration to be promising candidates as selection criteria for Norway spruce breeding. Heritabilities of other sawn timber traits were lower and the genetic correlations between these traits and field traits were also lower, variable, and had large estimation errors.
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