Tracheid dimensions of Norway spruce in uneven-aged stands

Tracheid length and width patterns from pith to bark at a height of 0.6 m in uneven-aged Norway spruce (Picea abies L. (H.) Karst) trees were addressed. The identification of the main factors and a comparison with even-aged stands were also pursued. 96 trees were sampled from experimental stands in Southern Finland. The material encompassed the variation in tracheid properties from early years to silvicultural maturity, i.e. from corewood to outerwood up to a cambial age of 111 years. Data from 39 Norway spruce trees from even-aged stands we utilized for comparison. Models fitted to the data indicated that annual ring widths did not influence mean tracheid dimensions but the latewood proportion showed a significant influence on tracheid dimensions. Tracheids in uneven-aged stands were slightly wider and longer at the base of the stem with a similar tree diameter, cambial age, and annual ring number.Tracheid length and width patterns from pith to bark at a height of 0.6 m in uneven-aged Norway spruce (Picea abies (L.) Karst.) trees were studied. Identification of the main factors and a comparison with even-aged stands were also carried out. Ninety-six trees were sampled from experimental stands in southern Finland. The material encompassed the variation in tracheid properties from early years to silvicultural maturity, i.e., from corewood to outerwood up to a cambial age of 111 years. Data from 39 Norway spruce trees from even-aged stands were utilized for comparison. Models fitted to the data indicated that annual ring widths did not influence mean tracheid dimensions but that the latewood proportion had a significant influence on tracheid dimensions. Tracheids in uneven-aged stands were slightly wider and longer at the base of the stem in trees with a similar diameter, cambial age, and annual ring number.Peer reviewe

Divergent selection predating the Last Glacial Maximum mainly acted on macro-phenotypes in Norway spruce

The current distribution and population structure of many species were, to a large extent, shaped by cycles of isolation in glacial refugia and subsequent population expansions. Isolation in and postglacial expansion through heterogeneous environments led to either neutral or adaptive divergence. Norway spruce is no exception, and its current distribution is the consequence of a constant interplay between evolutionary and demographic processes. We investigated population differentiation and adaptation of Norway spruce for juvenile growth, diameter of the stem, wood density, and tracheid traits at breast height. Data from 4461 phenotyped and genotyped Norway spruce from 396 half-sib families in two progeny tests were used to test for divergent selection in the framework of Q(ST) vs. F-ST. We show that the macroscopic resultant trait (stem diameter), unlike its microscopic components (tracheid dimensions) and juvenile growth, was under divergent selection that predated the Last Glacial Maximum. Altogether, the current variation in these phenotypic traits in Norway spruce is better explained by local adaptation to ancestral environments than to current ones, where populations were partly preadapted, mainly through growth-related traits

Genetic control of tracheid properties in Norway spruce wood

Through the use of genome-wide association studies (GWAS) mapping it is possible to establish the genetic basis of phenotypic trait variation. Our GWAS study presents the first such effort in Norway spruce (Picea abies (L). Karst.) for the traits related to wood tracheid characteristics. The study employed an exome capture genotyping approach that generated 178 101 Single Nucleotide Polymorphisms (SNPs) from 40 018 probes within a population of 517 Norway spruce mother trees. We applied a least absolute shrinkage and selection operator (LASSO) based association mapping method using a functional multi-locus mapping approach, with a stability selection probability method as the hypothesis testing approach to determine significant Quantitative Trait Loci (QTLs). The analysis has provided 30 significant associations, the majority of which show specific expression in wood-forming tissues or high ubiquitous expression, potentially controlling tracheids dimensions, their cell wall thickness and microfibril angle. Among the most promising candidates based on our results and prior information for other species are: Picea abies BIG GRAIN 2 (PabBG2) with a predicted function in auxin transport and sensitivity, and MA_373300g0010 encoding a protein similar to wall-associated receptor kinases, which were both associated with cell wall thickness. The results demonstrate feasibility of GWAS to identify novel candidate genes controlling industrially-relevant tracheid traits in Norway spruce

Implications of accounting for marker-based population structure in the quantitative genetic evaluation of genetic parameters related to growth and wood properties in Norway spruce

Background Forest geneticists typically use provenances to account for population differences in their improvement schemes; however, the historical records of the imported materials might not be very precise or well-aligned with the genetic clusters derived from advanced molecular techniques. The main objective of this study was to assess the impact of marker-based population structure on genetic parameter estimates related to growth and wood properties and their trade-offs in Norway spruce, by either incorporating it as a fixed effect (model-B) or excluding it entirely from the analysis (model-A). Results Our results indicate that models incorporating population structure significantly reduce estimates of additive genetic variance, resulting in substantial reduction of narrow-sense heritability. However, these models considerably improve prediction accuracies. This was particularly significant for growth and solid-wood properties, which showed to have the highest population genetic differentiation (QST) among the studied traits. Additionally, although the pattern of correlations remained similar across the models, their magnitude was slightly lower for models that included population structure as a fixed effect. This suggests that selection, consistently performed within populations, might be less affected by unfavourable genetic correlations compared to mass selection conducted without pedigree restrictions. Conclusion We conclude that the results of models properly accounting for population structure are more accurate and less biased compared to those neglecting this effect. This might have practical implications for breeders and forest managers where, decisions based on imprecise selections can pose a high risk to economic efficiency

Genome-wide association study identified novel candidate loci affecting wood formation in Norway spruce

Norway spruce is a boreal forest tree species of significant ecological and economic importance. Hence there is a strong imperative to dissect the genetics underlying important wood quality traits in the species. We performed a functional genome-wide association study (GWAS) of 17 wood traits in Norway spruce using 178 101 single nucleotide polymorphisms (SNPs) generated from exome genotyping of 517 mother trees. The wood traits were defined using functional modelling of wood properties across annual growth rings. We applied a Least Absolute Shrinkage and Selection Operator (LASSO-based) association mapping method using a functional multilocus mapping approach that utilizes latent traits, with a stability selection probability method as the hypothesis testing approach to determine a significant quantitative trait locus. The analysis provided 52 significant SNPs from 39 candidate genes, including genes previously implicated in wood formation and tree growth in spruce and other species. Our study represents a multilocus GWAS for complex wood traits in Norway spruce. The results advance our understanding of the genetics influencing wood traits and identifies candidate genes for future functional studies.Peer reviewe

Efficient wood and fiber characterization - A key factor in research and operation

During recent years, there have been a tremendous development in biotechnology. When entering the phase of industrial application, new possibilities have to be combined with a knowledge of the demands of the “users” concerning product quality, production efficiency, etc. It is also crucial to understand the natural variability of the wild-type plants and age-to-age relationships. Efficient measurement methods are key factors for progress in this field, in both research and operation. At STFI, the Swedish Pulp and Paper Research Institute, new tools and knowledge for improved wood and fiber utilization have been developed. Methods for the characterization of wood and fiber properties are emphasized. In this paper, measurement methods and variability in wood and fiber properties are illustrated. The methods used at STFI are useful not only for research on pulp and paper but may contribute also to projects in wood technology, forestry, tree improvement and biotechnology.La caractérisation rapide des propriétés du bois et des fibres. Une clé pour la recherche et les industries forestières. Ces dernières années ont connu un développement remarquable en matière de biotechnologie. Pour passer aux applications industrielles, ces nouvelles possibilités doivent être confrontées aux demandes des utilisateurs concernant la qualité des produits ou la productivité des procédés. Il est crucial aussi de bien maîtriser la variabilité des individus en peuplements naturels et les relations juvéniles/adultes au sein d'un même arbre. Pour répondre à ces objectifs, aussi bien au stade de la recherche que de la production, il est nécessaire de disposer de méthodes de mesures rapides. De nouveaux outils et savoirs pour une meilleure utilisation du bois et des fibres ont été développés à l'Institut suédois de recherche sur la pâte et le papier (STFI). Ces méthodes d'investigation et la variabilité des propriétés du bois et des fibres ainsi mesurées sont illustrées dans ce travail. Elles s'avèrent utiles non seulement pour la pâte et le papier mais peuvent aussi contribuer à des projets en matière de technologie du bois, de foresterie, d'amélioration des arbres et de biotechnologie

Juvenile wood characterization of Eucalyptus botryoides and E. maculata by using SilviScan

info:eu-repo/semantics/publishedVersio

Inter-and intra-annual wood property variation in juvenile wood between six Sitka spruce clones

Increased growth rates have reduced rotation lengths, increasing the proportion of juvenile wood relative to mature wood, which may negatively affect mechanical performance of sawn timber. However, there is limited information available on the potential impact of breeding for vigour on juvenile wood in Sitka spruce (Picea sitchensis (Bong.) CarriÚre). In this study, the relationship between vigour (based on total height) and wood properties was investigated in six-year-old Sitka spruce clones grown in two replicated field trials in Ireland. Six clones were evaluated, two clones from each of three vigour (high, intermediate and low) classes. Discs were cut from the base of one ramet per replication for each clone to assess wood quality attributes. Radial tracheid width was significantly and positively correlated with ring width and height, and was negatively correlated with density. The wood of the most vigorous clone had significantly larger ring width with thinner cell walls and wider tracheids than all clones in the two other vigour classes, resulting in lower mean wood density. Latewood properties for all wood attributes measured differed significantly between the two sites. Wood property differences resulted primarily from variation in the proportions of early- and latewood in each annual ring. Additionally, the width of early- and latewood bands in each ring was found to be a more important determinant of juvenile wood quality than the characteristics of the cells within each band. Wood properties differed greatly between clones, suggesting that there is potential to improve juvenile wood properties through selective breeding

Properties of materials from Birch – Variations and relationships : Part 2. Mechanical and physical properties

Birch regarded as Sweden’s third largest tree species. The two birch species, Silver- and Downy birch represents about 12% of total Swedish timber volume. For forestry, birch an important tree species which today mainly used for the manufacture of pulp and paper. The aim of this project was to describe mechanical and physical properties of birch. The properties that have been studied are stiffness, bending strength, shrinkage, spiral gran angle, density and microfibril angle in the cell wall and vessel cells, from different parts of the birch stems grown at different rates. The mapped properties have been compared also with those of other tree species, mainly spruce. The long term aim is to increase the knowledge of the birch wood properties to provide better predict their impact on products as well as provide a basis for better utilization of Swedish birch raw material and hopefully using birch as future structural timber. Three birch stands with different growth was chosen: Two stands where the birch growth has been different in a mixed forests stand of spruce and pine, and a fast growing stand with improved birch seedlings. Samples were taken from four different heights in the trees. The main thing that has been analyzed is the bending strength, modulus of elasticity, shrinkage coefficients in different directions and spiral grain. The mechanical tests are carried out on tines that are 20 x 20 x 300 mm and the fiber angle measurements were carried out on discs. These results have supplemented by the results of analyzes conducted with lnnventias SilviScan instruments that are able to recognize variations of year ring wood properties. Some of these are density, and microfibril angle, which is also included in this report. The results show that the wood from normal growth and fast growth improved birch receive equivalent wood properties. The results also show that birch wood properties are slightly better than that in Norway spruce. The material in this project was limited to only three stands and 11 sampled trees and therefore it can´t provide complete answers to the birch trees different wood properties. Limitations include genetic origin, growth rate, earlier silvicultural treatment and number of sample trees