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The correlation between spiral grain formation and 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 species growing in the south of Sweden. The angle between the longitudinal direction of the tracheids in the outermost year ring compared to the longitudinal direction of the stem was measured by scribing lines which followed the direction of the tracheids. The crown asymmetry was measured by taking photographs of the trees followed by a simple picture analysis of the tree. Wind data for the growing seasons of 1997 and 1998 were obtained from the Swedish Meteorological and Hydrological Institute. The results showed a significant correlation between the angle of the tracheids compared to the stem longitudinal direction going from a left-handed angle if the trees had a crown projected to the north towards a right-handed angle the more the crown projects to the south.

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. Résumé: Cette étude traite de la possibilité d'utiliser l'évaluation hâtive et non destructive de certains caractères sur le terrain pour l'amélioration génétique sélective des traits associés aux qualités structurelles importantes dans les sciages d'épicéa commun (Picea abies (L.) Karst.). Dans une plantation expérimentale d'épicéa commun âgée de 34 ans et située dans le sud de la Suède, 401 billes de pied ont été prélevées et sciées pour produire deux planches de 50 × 100 mm qui furent séchées jusqu'à un degré d'humidité de 18 %. Les traits associés aux qualités structurelles ont été évalués et leurs paramètres génétiques, incluant la variance génétique additive, l'héritabilité et les corrélations génétiques avec les caractères mesurés sur le terrain, ont été estimés. Le gauchissement, la densité et le module d'élasticité (MOE, rigidité) avaient une héritabilité (0,23-0,44) non néglige-able. Il y avait une étroite corrélation génétique (0,93) entre le gauchissement et l'angle du fil mesuré sous l'écorce sur le terrain. Il y avait aussi une étroite corrélation génétique entre le MOE (-0,75) et la densité (-0,91) des planches d'une part et les mesures d'enfoncement dans le bois prises sur le terrain à l'aide du pylodin d'autre part. Bien que ces observations aient été faites sur du matériel d'éclaircie constitué principalement de bois juvénile, elles indiquent néanmoins que l'angle du fil et l'enfoncement dans le bois mesuré à l'aide du pylodin sont des candidats prometteurs comme critères de sélection pour l'amélioration de l'épicéa commun. L'héritabilité des autres traits des sciages était plus faible et les corrélations génétiques entre ces trai...

Key message The Douglas fir provenance Three Valley was found most suitable for planting in mid-Sweden. Greenhouse tests can most likely predict how different Douglas fir provenances will perform in the field. Abstract The need for species that will grow well through ongoing climate change has increased the interest in Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] in Sweden. One of the most common problems seen in plantations of Douglas fir seedlings is damage caused by late spring frost, known to be highly correlated with the timing of bud burst. The objective of this study was to investigate spring-related bud development under Nordic conditions of seven Douglas fir provenances and to compare data with a local provenance of Norway spruce (Picea abies (L.) Karst). Results from a field trial and a greenhouse-based study were compared. The interior Douglas fir provenances exhibited an earlier bud burst than coastal provenances, both in the greenhouse and in the field trial. When comparing differences within the groups of interior and coastal Douglas fir provenances, no differences could be found. The local Norway spruce, only grown in the greenhouse, showed an intermediate bud development profile similar to the interior Douglas fir provenance Three Valley. We therefore suggest that Three Valley could be planted at the same locations as the investigated local provenance of Norway spruce in mid-Sweden. To avoid spring frost damage the Douglas fir seedlings need to be frozen stored and planted late in spring. Planting under shelterwood can also help protect the seedlings from spring frost damages. As similar results for bud development patterns of Douglas fir and Norway spruce provenances were obtained from the greenhouse and field trials, greenhouse tests could facilitate selection of provenances.

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