Liquid water absorption in uncoated Norway spruce (Picea abies) claddings as affected by origin and wood properties

Abstract

Uncoated Norway spruce specimens from different spatial positions within stems from two origins with different growth conditions were exposed to liquid water over a prolonged time, and apparent diffusion coefficients and rates of void filling were calculated from sorption curves. Both apparent diffusion and rate of void filling were significantly affected by origin and by the difference between inner and outer boards. The differences between inner and outer boards were explained by heartwood proportion and density, but some effects of origin remained when these properties were accounted for. The apparent diffusion coefficient was reduced by increasing density, and increased by increasing heartwood proportion. Void filling rate was reduced by both increasing density and increasing heartwood proportion. Since the effect of heartwood proportion was more pronounced in the material from the highly productive area, it may have been confounded with properties of juvenile wood.     

Micromechanical properties of common yew (Taxus baccata) and Norway spruce (Picea abies) transition wood fibers subjected to longitudinal tension

The longitudinal modulus of elasticity of common yew is astonishingly low in light of its high raw density. At least this was found for specimens examined at the solid wood level and at the tissue level. However, to reveal if this low axial stiffness is also present at the cellular level, tensile tests were performed on individual yew fibers and on spruce fibers for reference. The results revealed a low stiffness and a high strain to fracture for yew when compared with spruce. This compliant behavior was ascribed to a relatively high microfibril angle of yew measured by X-ray scattering. It can be concluded that the high compliance of yew observed at higher hierarchical levels is obviously controlled by a structural feature present at the cell wall level. In future studies, the biomechanical function of this compliant behavior for the living yew tree would be of particular interest.     

The variation of the basic density within the juvenile wood of Sitka spruce (Picea sitchensis)

The variation in the basic‐density level of 45 stems of Sitka spruce from two Danish sites has been examined. It is shown that the basic‐density level, i.e. the basic density as a function of ring width, within the juvenile wood decreases with (1) increasing distance from the pith and (2) increasing height in the stem (same ring number from pith provided). Furthermore, the basic‐density level seems to decrease with increasing stand quality, which may affect the pattern of variation in basic‐density level if the stand quality class varies with age. The basic density of the juvenile wood is markedly higher in Sitka spruce than in Norway spruce, whereby the risk of stem cracks probably is reduced.     

Crystallinity of wood and the size of cellulose crystallites in Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis>)

X-ray diffraction was used to study variations in the crystallinity of wood and the average thickness and length of the crystallites of cellulose as a function of the number of the year ring in Norway spruce [Picea abies (L.) Karst.]. The crystallinity increased from ring 4 to ring 10 from the pith and was constant after ring 10. The crystallinity of mature wood was about 30% ± 5%. The average thickness and average length of the crystallites were 3.2 ± 0.1nm and 28 ± 2nm, respectively; and no systematic variation of these values with the number of the year ring was observed. The mean microfibril angle decreased near the pith but was constant in the mature wood.     

Impacts of fructification on biomass production and correlated genetic effects in Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis> [L.] Karst.)

For the period 2003–2006, fructification of Norway spruce (Picea abies [L.] Karst.) was recorded at the Kranzberg forest site in Southern Germany by employing a crane with access to the canopy of more than 266 trees. For each tree, stem diameter and growth parameters were assessed annually as well as biomass of cones and seeds, number of seeds per cone, and proportions of empty seeds for a total of 371 trees with cone crop. Genotypes at 19 enzyme coding gene loci of 110 trees were included in the study of correlations between morphological and genetic traits. Re-scaling the observed values for a virtual pure Norway spruce stand of 1 ha, cone biomass including winged seeds (oven-dried at 38°C) varied between 706.8 kg/ha in 2006 (average value per tree was 3.6 kg) and values close to zero in 2005. Corresponding values for vegetative biomass increment of the coning trees in 2006 were 9,273.0 kg/ha and 10.8 kg/tree. A significant higher biomass investment was determined for dominant trees in terms of absolute cone mass as well as in terms of cone mass relative to vegetative biomass and fructification frequency. No trade-off effects in decreased vegetative biomass growth were found in the fructification year, compared to trees that did not grow cones. Although the dominant trees invested proportionally considerable biomass in cones, they showed no significant reduction in vegetative biomass growth. In the following year no decrease in vegetative growth was detected. Based on logistic regressions and homogeneity tests, respectively, significant genetic effect became evident with respect to the gene loci AAP-B and AAT-C concerning fructification probability in the year with maximum generative biomass investment. These and closely related loci also have been found to be indicative for growth and viability, respectively, in other species.     

Characterization of lignin-carbohydrate linkages in the residual lignins isolated from chemical pulps of spruce (<Emphasis Type="Italic">Picea abies</Emphasis>) and beech wood (<Emphasis Type="Italic">Fagus sylvatica</Emphasis>)

To investigate the linkage types between carbohydrates and lignin, residual lignins were isolated from three different unbleached pulps [kraft, alkaline sulfite anthraquinone methanol (ASAM), and soda with anthraquinone (AQ) and methanol] of spruce and beech wood and then characterized by oxidation with 2,3-Dichloro-5,6-dicyanobenzoquinone and followed by Prehm’s methylation. In residual lignins, sugar moieties were bound to lignins via benzyl ether bonds. In particular, galactose and mannose are predominantly linked to lignin fragments in residual lignins of spruce wood, while xylose and galactose are favored in the formation of LC bonds in the residual lignins of beech wood. In the case of hexoses, primary hydroxyl groups (C6 position) preferentially take part in benzyl ether linkages. Hydroxyl groups in the C2 and C3 positions of xylose participate in LC bonds and a small portion of arabinose was notably connected to lignin via the C5 position. Approximately seven or eight sugars were connected in soda/AQ/methanol residual lignin per 100 C9 lignin units, while the frequencies of LC bonds in kraft and ASAM residual lignins were distinctively less at one to three sugars per 100 C9 lignin units. The publication of this article was made possible by an Emachu Research Fund. The authors are grateful for the fund.