Tokiko Hiraiwa

RADIAL VARIATION OF ANATOMICAL CHARACTERISTICS IN PARASERIANTHES FALCATARIA PLANTED IN INDONESIA

Radial variation in anatomical characteristics of five 13-year-old Paraserianthes falcataria (L.) Nielsen (syn. Albizia falcataria (L.) Fosberg), an important commercial tree species in Indonesia, were investigated in order to obtain basic information regarding breeding for wood quality. Both cell wall thickness in wood fibers and vessel percentage showed an almost constant value up to 10 cm from the pith and then increased toward the bark. In contrast, wood fiber percentage decreased from 10 cm toward the bark. The cell wall percentage was lower towards the pith and higher towards the bark. In the five sample trees, significant differences were found in the cell diameter of wood fibers, wood fiber percentage, axial parenchyma percentage, and cell wall percentage. Basic density was affected by the cell wall thickness of wood fibers, but not the vessel percentage and fiber percentage.

Radial variations of wood properties in Casuarina equisetifolia growing in Bangladesh

Radial variations of wood properties (basic density, fiber length, vessel element length, and compression strength) in plantation-grown Casuarina equisetifolia in Bangladesh were investigated for effective utilization of the wood. Samples disks at breast height were randomly collected from trees in a 10-year-old plantation in Cox’s Bazar Forest Division, Bangladesh. The basic density showed a near-constant value up to 30 mm from the pith and then rapidly increased up to 60 mm from the pith. The fiber length and vessel element length gradually increased from the pith to bark. When radial variation of wood properties was determined according to relative distance from the pith, similar radial patterns were observed among the sample trees, indicating that the wood properties in C. equisetifolia may be related to the growth rate. The compression strength parallel to the grain (CS) increased from the pith to bark. A significant positive correlation was found between the air-dried density and the CS. The results obtained indicated that wood around the pith has a relatively low density, and wood outside the pith area has a relatively high density, suggesting that it could be used as structural lumber.

Wood Anatomy of nine Japanese Hardwood species forming reaction wood without gelatinous fibers

The anatomy of reaction wood was studied in nine naturally growing Japanese hardwood species, all showing eccentric growth on the upper side of their leaning branches. The number of vessels decreased in the xylem of the upper side accompanying the formation of reaction wood. A typical G-layer was not detected in the reaction wood fibers, but an S3 layer was present in all nine species. The cellulose microfibril arrangement with an S helix was similar in the S3 layers of both reaction and opposite wood fibers. A decrease of lignin content occurred in the reaction wood fibers in all nine species. The coniferyl and sinapyl aldehyde units in the lignins were strongly reduced in the S2 layer of reaction wood fibers of four species, i.e., Euscaphis japonica, Rhododendron wadanum, Clerodendron trichotomum, and Daphne odora, and much less so in five other species, i.e., Viburnum dilatatum, Enkianthus subsessilis, Euonymus alatus, Ilex macropoda, and Ilex crenata. The syringyl content was lower in the S2 layer of reaction wood fibers than that in opposite wood of all nine species. On the other hand, chemical analysis of lignin using the acetyl bromide method showed that, among the nine species, lignin content was reduced most strongly in Clerodendron trichotomum. Tension wood-like characteristics are present on the upper side of leaning branches in all nine species, except that G-fibers are absent.

Variation in anatomical properties and correlations with wood density and compressive strength in Casuarina equisetifolia growing in Bangladesh

Summary Variation in anatomical properties and relationships with air-dry density and compressive strength were examined in wood of 10-y-old Casuarina equisetifolia. Average vessel diameter increased gradually between sample points 2.5 cm and 7.5 cm from the pith. Vessel frequency decreased between sample points 2.5 cm and 5 cm from the pith and then stabilised. Average fibre diameter decreased gradually from pith to bark, while fibre wall thickness displayed a reverse trend. The proportion of vessels decreased slightly between the 2.5 and 5 cm sample points and then increased again towards the bark. Fibre and cell wall proportions increased from the pith to bark. The proportion of rays was nearly constant along the radius, while the proportion of axial parenchyma decreased somewhat toward the bark. Vessel diameter, fibre wall thickness and the proportions of fibre and cell wall were positively correlated with air-dry density, whereas fibre diameter showed a negative correlation. A significant negative correlation was found between compressive strength and fibre diameter. Strong positive correlations suggest that variation in air-dry density and compressive strength is mainly determined by the proportion of cell wall in transverse sections.

ANATOMY AND CHEMICAL COMPOSITION OF LIRIODENDRON TULIPIFERA STEMS INCLINED AT DIFFERENT ANGLES

The anatomical and chemical characteristics of reaction wood (RW) were investigated in Liriodendron tulipifera Linn. Stems of seedlings were artificially inclined at angles of 30 (RW-30), 50 (RW-50) and 70° (RW-70) from the vertical, and compared with normal wood (NW) from a vertical seedling stem. The smallest values for the wood fibre length and vessel number were observed in RW-50. The pit aperture angle was less than 10° in RW-30 and RW-50, in which reduced lignin content was observed in the S2 layer of the wood fibres. An increase in the glucose content and a decrease in the lignin and xylose content was observed in RW-50. The stem inclination angle affected the degree of RW development with regard to anatomical and chemical characteristics: the severest RW was observed in RW-50, followed by RW-30. RW-70 was similar in anatomical and chemical characteristics to NW, apparently because the inclination was too strong to enable recovery of its original position. In this case a vertical sprouting stem was formed to replace the inclined stem.

ANATOMY AND LIGNIN DISTRIBUTION OF “COMPRESSION-WOOD-LIKE REACTION WOOD” IN GARDENIA JASMINOIDES

Anatomical characteristics and lignin distribution of ‘compression-wood-like reaction wood’ in Gardenia jasminoides Ellis were investigated. Two coppiced stems of a tree were artificially inclined to form reaction wood (RW). One stem of the same tree was fixed straight as a control, and referred to as normal wood (NW). Excessive positive values of surface-released strain were measured on the underside of RW stems. Anatomical characteristics of xylem formed on the underside of RW and in NW stems were also observed. The xylem formed on the underside exhibited a lack of S3 layer in the secondary fibre walls, an increase of pit aperture angle in the S2 layer, and an increase in lignin content. Some of the anatomical characteristics observed in the underside xylem resembled compression wood in gymnosperms. These results suggest that the increase of microfibril angle in the secondary wall and an increase in lignin content in angiosperms might be common phenomena resembling compression wood of gymnosperms.

CHARACTERISTICS OF TROCHODENDRON ARALIOIDES TENSION WOOD FORMED AT DIFFERENT INCLINATION ANGLES

To assess the characteristics of tension wood (TW) in Trochodendron aralioides Sieb. et Zucc., seedling stems were artificially inclined at angles of 30° (TW- 30), 50° (TW-50), and 70° (TW-70) from the vertical. At all angles, the growth promotion was pronounced on the upper side of the inclined stems, where excessive tensile growth stress was observed. A gelatinous layer (G-layer) formed in the tracheids of TW. The cell wall structure of the tracheids in TW was S1 + G. The G-layer had a small pit aperture angle <10°. TW-50 showed larger tensile growth stress, a thicker G-layer area, and a smaller pit aperture angle of the Glayer than TW-30 and TW-70. Lower levels of Klason lignin and hemicellulose and higher levels of α-cellulose content were observed in TW-50. In addition, an increase in glucose content and a decrease in xylose content in holocellulose were observed in TW-50. Therefore, it can be concluded that the degree of TW varied with different inclination angles.

Radial Variation in Microfibril Angle and Compression Properties of Paraserianthes Falcataria Planted in Indonesia

Paraserianthes falcataria (L.) Nielsen is an important plantation species in Indonesia. The objective of this study was to understand the radial variation of microfibril angle in the S2 layer of the wood fiber wall (MFA) in P. falcataria, and its relationship to compression properties parallel to the grain, including modulus of elasticity (E) and compression strength (σ). MFA gradually decreased from pith to bark while both E and σ increased from pith to bark. Significant differences in MFA, E, and σ were found among the five sample trees. Single-regression analysis of wood and compression properties revealed that the compression properties of core wood were affected mainly by density, whereas those in outer wood were affected by both MFA and air-dry density (AD).

Radial variation of bending property in plantation grown Acacia auriculiformis in Bangladesh

Acacia auriculiformis is one of the major fast-growing plantation species in Bangladesh. Understanding the radial variation of bending property has importance in tree improvement and wood utilization. In this study, the radial variation of modulus of elasticity (MOE) and modulus of rupture (MOR) in static bending were examined in 11-year-old plantation-grown Acacia auriculiformis from Bangladesh. MOE and MOR increased up to about 6 and 8 cm radial distance from the pith, respectively, and then both properties were nearly stable toward the bark. MOE did not show significant correlation with air-dried density. Conversely, MOR showed significant correlation with air-dried density. Significant variation among the trees indicates that the air-dried density and MOR could be used in plus tree selection for wood quality improvement of this species through tree breeding.