Air permeability in longitudinal and radial directions of compression wood of Picea abies L. and tension wood of Fagus sylvatica L.

Holzforschung ◽  
2009 ◽  
Vol 63 (3) ◽  
Author(s):  
Asghar Tarmian ◽  
Patrick Perré
Keyword(s):  
Picea Abies ◽  
Fagus Sylvatica ◽  
Tension Wood ◽  
Compression Wood ◽  
Air Permeability ◽  
Normal Wood ◽  
Reaction Wood ◽  
Anatomical Point ◽  
Bordered Pits ◽  
The Difference

Abstract The air permeability in longitudinal and radial directions of compression wood in spruce (Picea abies) and tension wood in beech (Fagus sylvatica) was compared with that of the corresponding normal wood. The primary aim of the present study was to explain why the reaction woods dry more slowly than the normal woods in the domain of free water. A number of boards conventionally dried to an average final moisture content of 12% were chosen to perform the measurements. Bordered pits on the radial walls of longitudinal tracheids in the compression and normal wood and intervessel or intervascular pits in the tension and normal wood were also examined. The reaction wood of both species is less permeable than the normal wood, both in longitudinal and radial directions. The difference in permeability was more pronounced between compression and normal wood of spruce, especially in longitudinal direction. From an anatomical point of view, this is likely related to some differences in anatomical characteristics affecting the airflow paths, such as the pit features. Such results can explain the difference in drying kinetics of the reaction and normal woods in the capillary regime of drying.

Reaction wood drying kinetics: tension wood in Fagus sylvatica and compression wood in Picea abies

2008 ◽  
Vol 43 (1-2) ◽  
pp. 113-130 ◽  
Author(s):  
A. Tarmian ◽  
R. Remond ◽  
M. Faezipour ◽  
A. Karimi ◽  
P. Perré
Keyword(s):  
Picea Abies ◽  
Fagus Sylvatica ◽  
Tension Wood ◽  
Compression Wood ◽  
Drying Kinetics ◽  
Reaction Wood ◽  
Wood Drying

scholarly journals Inter-Tracheid and Cross-Field Pitting in Compression Wood and Opposite Wood of Norway Spruce (Picea abies L.)

2011 ◽  
Vol 3 (2) ◽  
pp. 145-151 ◽  
Author(s):  
Asghar TARMIAN ◽  
Mohammad AZADFALLAH ◽  
Hadi GHOLAMIYAN ◽  
Mahdi SHAHVERDI
Keyword(s):  
Picea Abies ◽  
Norway Spruce ◽  
Compression Wood ◽  
Microfibril Angle ◽  
Air Permeability ◽  
Sem Images ◽  
Aperture Diameter ◽  
Opposite Wood ◽  
Bordered Pits ◽  
S2 Layer

Inter-tracheid and cross-filed pit specifications in compression wood and opposite wood of Norway spruce (Picea abies) were determined. Fewer pits of a smaller size and a smaller aperture diameter were observed in compression wood. In contrast to the uniseriate arrangement of bordered pit pairs in compression wood, both uniseriate and biseriate pits were observed in opposite wood. In contrast to the circular view of the pit aperture in opposite wood, a slit-like pit aperture was often observed in compression wood. SEM images showed a number of helical fissures on the tracheid walls and bordered pits of compression wood along the microfibril angle in the S2 layer. The cross-field pits in compression wood were dominantly piceoid but sometimes cupressoid and occasionally taxodioid, whereas they were mostly piceoid and occasionally cupressoid in opposite wood. Overall, some significant differences in the inter-tracheid and cross-field pitting between the compression wood and opposite wood can give some explanations for their different air permeability and drying kinetics found in the previous studies.

The nature of reaction wood. IV. Variations in cell wall organization of tension wood fibres

1955 ◽  
Vol 3 (2) ◽  
pp. 177 ◽  
Author(s):  
AB Wardrop ◽  
HE Dadswell
Keyword(s):  
Cell Wall ◽  
Tension Wood ◽  
Secondary Wall ◽  
Degree Of Crystallinity ◽  
Tropical Species ◽  
Normal Wood ◽  
Reaction Wood ◽  
Gelatinous Layer ◽  
Wood Fibres ◽  
Cell Wall Organization

The cell wall organization, the cell wall texture, and the degree of lignification of tension wood fibres have been investigated in a wide variety of temperate and tropical species. Following earlier work describing the cell wall structure of tension wood fibres, two additional types of cell wall organization have been observed. In one of these, the inner thick "gelatinous" layer which is typical of tension wood fibres exists in addition to the normal three-layered structure of the secondary wall; in the other only the outer layer of the secondary wall and the thick gelatinous layer are present. In all the tension wood examined the micellar orientation in the inner gelatinous layer has been shown to be nearly axial and the cellulose of this layer found to be in a highly crystalline state. A general argument is presented as to the meaning of differences in the degree, of crystallinity of cellulose. The high degree of crystallinity of cellulose in tension wood as compared with normal wood is attributed to a greater degree of lateral order in the crystalline regions of tension wood, whereas the paracrystalline phase is similar in both cases. The degree of lignification in tension wood fibres has been shown to be extremely variable. However, where the degree of tension wood development is marked as revealed by the thickness of the gelatinous layer the lack of lignification is also most marked. Severity of tension wood formation and lack of lignification have also been correlated with the incidence of irreversible collapse in tension wood. Such collapse can occur even when no whole fibres are present, e.g. in thin cross sections. Microscopic examination of collapsed samples of tension wood has led to the conclusion that the appearance of collapse in specimens containing tendon wood can often be attributed in part to excessive shrinkage associated with the development of fissures between cells, although true collapse does also occur. Possible explanations of the irreversible shrinkage and collapse of tension wood fibres are advanced.

scholarly journals Variability of spruce (Picea abies [L.] Karst.) compression strength with present reaction wood

2009 ◽  
Vol 55 (No. 9) ◽  
pp. 415-422 ◽  
Author(s):  
V. Gryc ◽  
H. Vavrčík
Keyword(s):  
Picea Abies ◽  
Compression Strength ◽  
Compression Wood ◽  
3D Models ◽  
Reaction Wood ◽  
Stem Height ◽  
Direction Parallel ◽  
Strength Limit ◽  
Wood Compression ◽  
Wood Strength

The aim of research was to find out the variability of spruce (<I>Picea abies</I> [L.]) Karst.) wood compression strength limits in the direction parallel to grain. The wood strength was examined using samples from a tree with present reaction (compression) wood. The strength was found out for individual stem zones (CW, OW, SWL and SWR). The zone with present compression wood (CW) demonstrated slightly higher values of wood strength limits. The differences in the limits of compression strength parallel to grain in individual zones were not statistically significant. All the data acquired by measuring were used to create 3D models for each zone. The models describe the strength along the radius and along the stem height. The change of strength along the stem radius was statistically highly significant. There was an obvious tendency towards an increase in the strength limit in the first 40 years. With the increased stem height, there is a slight decrease in wood strength.

Strength and stiffness of the reaction wood in five Eucalyptus species

Holzforschung ◽  
2019 ◽  
Vol 73 (2) ◽  
pp. 219-222
Author(s):  
Bruno Charles Dias Soares ◽  
José Tarcísio Lima ◽  
Selma Lopes Goulart ◽  
Claudineia Olímpia de Assis
Keyword(s):  
Mechanical Behavior ◽  
Tension Wood ◽  
Compression Wood ◽  
Vertical Position ◽  
Eucalyptus Species ◽  
Reaction Wood ◽  
Opposite Wood ◽  
Average Slope ◽  
Strength And Stiffness

AbstractTree stems deviating from the vertical position react by the formation of tension wood (TW) or compression wood (CW), which are called in general as reaction wood (RW), in which the cells are modified chemically and anatomically. The focus of the present work is the mechanical behavior of TW in five 37-year-oldEucalyptusspecies, which were grown on a planting area with an average slope of 28% leading to decentralized pith in the trees, which is an unequivocal indication of the presence of RW. TW and opposite wood (OW) samples were isolated and subjected to a compression-parallel-to-grain test. It was observed that TW is less resistant and less stiff than the OW.

scholarly journals Variability in density of spruce (Picea abies [L.] Karst.) wood with the presence of reaction wood

2008 ◽  
Vol 53 (No. 3) ◽  
pp. 129-137 ◽  
Author(s):  
V. Gryc ◽  
P. Horáček
Keyword(s):  
Picea Abies ◽  
Moisture Content ◽  
Wood Density ◽  
Compression Wood ◽  
Wood Properties ◽  
3D Models ◽  
Reaction Wood ◽  
Stem Height ◽  
Sample Tree

The study was aimed to assess the integral value that determines wood properties &minus; wood density at a moisture content of 0% and 12%. The wood density was researched in a sample tree with the presence of reaction compression wood. The density was determined for individual zones (CW, OW, SWL and SWR). The zone where compression wood (CW) is present has a higher density than the remaining zones. On the basis of the acquired data, 3D models were created for individual zones; they describe the variability of wood density along the stem radius and stem height. The influence of the radius seems to be a statistically highly significant factor. The wood density is significantly higher in samples with the presence of compression wood. When the proportion of compression wood in the sample was 80%, the wood density was 1.5 times higher compared to wood without compression wood.

scholarly journals The Nature of Reaction Wood III. Cell Division and Cell Wall Formation in Conifer Stems

1952 ◽  
Vol 5 (4) ◽  
pp. 385 ◽  
Author(s):  
ABW Ardrop ◽  
HE Dadswell
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Secondary Wall ◽  
Compression Wood ◽  
Normal Wood ◽  
Reaction Wood ◽  
Primary Wall ◽  
Wall Formation ◽  
Tracheid Length ◽  
Secondary Wall Formation

Cell division, the nature of extra-cambial readjustment, and the development of the secondary wall in the tracheids of conifer stems have been investigated in both compression wood and normal wood. It has been shown that the reduction in tracheid length, accompanying the development of compression wood and, in normal wood, increased radial growth after suppression, result from an increase in the number of anticlinal divisions in the cambium. From observations of bifurcated and otherwise distorted cell tips in mature tracheids, of small but distinct terminal canals connecting the lumen to the primary wall in the tips of mature tracheids, and of the presence of only primary wall at the tips of partly differentiated tracheids, and from the failure to observe remnants of the parent primary walls at the ends of differentiating tracheids, it has been concluded that extra-cambial readjustment of developing cells proceeds by tip or intrusive growth. It has been further concluded that the development of the secondary wall is progressive towards the cell tips, on the bases of direct observation of secondary wall formation in developing tracheids and of the increase found in the number of turns of the micellar helix per cell with increasing cell length. The significance of this in relation to the submicroscopic organization of the cell wall has been discussed. Results of X-ray examinations and of measurements of� tracheid length in successive narrow tangential zones from the cambium into the xylem have indicated that secondary wall formation begins before the dimensional changes of differentiation are complete.

scholarly journals Critical review on the mechanisms of maturation stress generation in trees

2016 ◽  
Vol 13 (122) ◽  
pp. 20160550 ◽  
Author(s):  
Tancrède Alméras ◽  
Bruno Clair
Keyword(s):  
Cell Wall ◽  
Tension Wood ◽  
Compression Wood ◽  
Current Knowledge ◽  
Stress Generation ◽  
Plant Science ◽  
Reaction Wood ◽  
Wood Structure ◽  
Structure State ◽  
Cell Organization

Trees control their posture by generating asymmetric mechanical stress around the periphery of the trunk or branches. This stress is produced in wood during the maturation of the cell wall. When the need for reaction is high, it is accompanied by strong changes in cell organization and composition called reaction wood, namely compression wood in gymnosperms and tension wood in angiosperms. The process by which stress is generated in the cell wall during its formation is not yet known, and various hypothetical mechanisms have been proposed in the literature. Here we aim at discriminating between these models. First, we summarize current knowledge about reaction wood structure, state and behaviour relevant to the understanding of maturation stress generation. Then, the mechanisms proposed in the literature are listed and discussed in order to identify which can be rejected based on their inconsistency with current knowledge at the frontier between plant science and mechanical engineering.

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