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.

Cross-field pitting characteristics of compression, lateral, and opposite wood in the stem wood of Ginkgo biloba and Pinus densiflora

IAWA Journal ◽  
2020 ◽  
Vol 41 (1) ◽  
pp. 48-60
Author(s):  
Byantara Darsan Purusatama ◽  
Nam Hun Kim
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Ginkgo Biloba ◽  
Compression Wood ◽  
Pinus Densiflora ◽  
Reaction Wood ◽  
Stem Wood ◽  
Opposite Wood ◽  
The Cross ◽  
Scanning Electron

Abstract The characteristics of cross-field pitting among compression wood, lateral wood, and opposite wood, in the stem woods of Ginkgo biloba and Pinus densiflora were investigated with optical and scanning electron microscopy. In Ginkgo biloba, compression wood exhibited piceoid pits, while lateral and opposite wood exhibited cupressoid pits. The compression wood of Pinus densiflora exhibited cupressoid pits and piceoid pits, while lateral wood and opposite wood exhibited pinoid and window-like pits in the cross-field. In both species, compression wood yielded the smallest pit number among each part, while opposite wood yielded the greatest pit number per cross-field. Cross-field pitting diameters of compression wood and opposite wood were significantly smaller than lateral wood in Ginkgo biloba, while the cross-field pitting of compression wood was the smallest in Pinus densiflora. Radial tracheid diameter of compression wood was slightly smaller than lateral and opposite wood in Ginkgo biloba and significantly smaller than lateral and opposite wood in Pinus densiflora. In conclusion, the cross-field pitting type, pit number, and cross-field pitting diameter could be used to identify reaction wood in the stem wood of Ginkgo biloba and Pinus densiflora.

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.

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.

scholarly journals Influência do lenho de tração nas propriedades físicas da madeira de Eucalyptus sp.

2010 ◽  
Vol 1 (1) ◽  
pp. 6-11
Author(s):  
Thiago Campos Monteiro ◽  
Renato da Silva Vieira ◽  
José Tarcísio Lima ◽  
Edy Eime Pereira Baraúna ◽  
Duam Matosinhos de Carvalho ◽  
...  
Keyword(s):  
Tension Wood ◽  
Basic Density ◽  
Eucalyptus Camaldulensis ◽  
Normal Wood ◽  
Reaction Wood ◽  
Opposite Wood ◽  
The Face ◽  
Eucalyptus Maculata ◽  
Shrinkage Coefficient

The reaction wood is formed in an attempt to remain upright tree in response to the action of forces such as winds, irregular crown or slope of the land that tend to incline it. In hardwoods, as in Eucalyptus, this type of wood is called tension wood and occurs in the region of the stem facing the face of force application. Indicative of the presence of this type of wood is the high shrinkage and basic density compared to normal wood. Once the basic density and shrinkage are parameters for determining the quality of the wood, this study aimed to evaluate the variation of basic density and shrinkage of opposite and tension wood along the radius in four species of Eucalyptus sp. Four tree species Eucalyptus camaldulensis, Eucalyptus maculata, Eucalyptus pilularis and Eucalyptus urophylla, with 32 years of age, were taken from an experimental planting of the Federal University of Lavras. Specimens were made to represent the diametrical variation of the opposite of tension wood in disks cut at the dbh. The results indicate that the properties of radial, tangential and volumetric shrinkage, coefficient of anisotropy and basic density did not differ statistically between the tensionand opposite wood.

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 Tension Wood and Opposite Wood in 21 Tropical Rain Forest Species

IAWA Journal ◽  
2006 ◽  
Vol 27 (3) ◽  
pp. 329-338 ◽  
Author(s):  
Bruno Clair ◽  
Julien Ruelle ◽  
Jacques Beauchêne ◽  
Marie Françoise Prévost ◽  
Meriem Fournier
Keyword(s):  
Rain Forest ◽  
Tropical Rain Forest ◽  
Tension Wood ◽  
Reaction Wood ◽  
Forest Species ◽  
Growth Stresses ◽  
Opposite Wood ◽  
Two Samples ◽  
Key Factor ◽  
French Guyana

Wood samples were taken from the upper and lower sides of 21 naturally tilted trees from 18 families of angiosperms in the tropical rain forest in French Guyana. The measurement of growth stresses ensured that the two samples were taken from wood tissues in a different mechanical state: highly tensile stressed wood on the upper side, called tension wood, and lower tensile stressed wood on the lower side, called opposite wood. Eight species had tension wood fibres with a distinct gelatinous layer (G-layer). The distribution of gelatinous fibres varied from species to species. One of the species, Casearia javitensis (Flacourtiaceae), showed a peculiar multilayered secondary wall in its reaction wood. Comparison between the stress level and the occurrence of the G-layer indicates that the G-layer is not a key factor in the production of high tensile stressed wood.

Characterizing compression wood formed in radiata pine branches

IAWA Journal ◽  
2014 ◽  
Vol 35 (4) ◽  
pp. 385-394
Author(s):  
Xinguo Li ◽  
Robert Evans ◽  
Washington Gapare ◽  
Xiaohui Yang ◽  
Harry X. Wu
Keyword(s):  
Compression Wood ◽  
Microfibril Angle ◽  
Marked Change ◽  
Radiata Pine ◽  
Wood Formation ◽  
Reaction Wood ◽  
Opposite Wood ◽  
Cambial Age ◽  
Cellulose Microfibril Orientation ◽  
Secondary Wall Formation

The formation of reaction wood is an adaptive feature of trees in response to various mechanical forces. In gymnosperms, reaction wood consists of compression wood (CW) and opposite wood (OW) that are formed on the underside and upperside of bent trunks and branches. Although reaction wood formed in bent trunks has been extensively investigated, relatively little has been reported from conifer branches. In this study SilviScan® technology was used to characterize radiata pine branches at high resolution. Compared to OW formed in the branches, CW showed greater growth, darker colour, thicker tracheid walls, higher coarseness, larger microfibril angle (MFA), higher wood density, lower extensional stiffness and smaller internal specific surface area. However, tracheids of CW were similar to those of OW in their radial and tangential diameters. These results indicated that gravity influenced tracheid cell division and secondary wall formation but had limited impact on primary wall expansion. Furthermore, seasonal patterns of CW formation were not observed in the branches from cambial age 4 while earlywood and latewood were clearly separated in all rings of OW. The marked change of MFA during reaction wood formation suggested that branches could be ideal materials for further study of cellulose microfibril orientation.

scholarly journals Effects of the position in a stem on the variability of tracheids in spruce (Picea abies /L./ Karst.) with the occurrence of reaction wood

2010 ◽  
Vol 58 (2) ◽  
pp. 77-86
Author(s):  
Vladimír Gryc ◽  
Hanuš Vavrčík
Keyword(s):  
Compression Wood ◽  
Growing Season ◽  
3D Models ◽  
Reaction Wood ◽  
Annual Rings ◽  
Opposite Wood ◽  
Late Wood ◽  
Radial Dimension ◽  
Wood Tracheid ◽  
Stem Structure

The paper is aimed at the field of the microscopic structure of wood dealing with the description of the most important anatomic element in softwood – tracheids in a stem with the occurrence of reaction wood. Significant changes of tracheids were found along the height and radius of a stem. There were statistically significant differences between particular annual rings (variability along the stem radius). The height of a stem was also statistically significant. On the basis of the results obtained 3D models were created (for zones compression wood, opposite wood and site wood; models for radial dimension an early-wood tracheid and late-wood tracheid) depicting changes in transverse dimensions of the spruce tracheid in relation to its position in a stem. Structure of ring with compression wood was studied too. It was observed that the ring with occurrence of compression wood has a following structure: early wood tracheids at the beginning of the growing season, transitional tracheids, compression tracheids and at the end of an annual ring typical late wood tracheids. The rings with compression wood show more tracheids as compared with annual rings from the opposite side.

scholarly journals Viscoelastic properties of green wood across the grain measured by harmonic tests in the range 0–95°C: Hardwood vs. softwood and normal wood vs. reaction wood

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 548-557 ◽  
Author(s):  
Vincent Placet ◽  
Joëlle Passard ◽  
Patrick Perré
Keyword(s):  
Storage Modulus ◽  
Viscoelastic Properties ◽  
Tension Wood ◽  
Radial Direction ◽  
Lignin Content ◽  
Softening Temperature ◽  
Normal Wood ◽  
Reaction Wood ◽  
Opposite Wood ◽  
Wood Compression

Abstract The viscoelastic properties of wood have been investigated with a dynamic mechanical analyser specifically developed for wooden materials, the WAVET device. Measurements were carried out on four wood species in the temperature range 0–100°C at frequencies varying between 5 mHz and 10 Hz. Wood samples were tested under water-saturated conditions in the radial and tangential directions. As expected, the radial direction always revealed a higher storage modulus than the tangential direction. Great differences were also observed in the loss factor. The tanδ peak and internal friction were higher in the tangential than in the radial direction. This behaviour is attributed to the fact that anatomical elements act as a function of the direction. The viscoelastic behaviour of reaction wood differs from that of normal or opposite wood. Compression wood of spruce, which has a higher lignin content, is denser and stiffer in transverse directions than normal wood, and has a lower softening temperature (T g). In tension wood, the G-layer is weakly attached to the rest of the wall layers. This may explain why the storage modulus and softening temperature of tension wood are lower than those for opposite wood. We also demonstrate that the time-temperature equivalence fits only around the transition region, i.e., between T g and T g+30°C. Apart from these regions, the response of wood reflects the combined effects of all its constitutive polymers, so that the equivalence is no longer valid.

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.

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