The Formation of Interlocked Grain in African Mahogany (Khaya spp.) Analyzed by X-Ray Computed Microtomography

Interlocked grain occurs when the orientation of xylem fibers oscillates, alternating between left- and right-handed spirals in successive wood layers. The cellular mechanisms giving rise to interlocked grain, thought to involve the slow rotation of fusiform initials within the vascular cambium, remain unclear. We suggest that observations of wood structure at the cellular level, but over large areas, might reveal these mechanisms. We assayed timber from several commercially-important tropical angiosperms from the genus Khaya (African mahogany) that exhibit interlocked grain using X-ray computed microtomography followed by orthogonal slicing and image processing in ImageJ. Reconstructed tangential longitudinal sections were processed with the ImageJ DIRECTIONALITY plug-in to directly measure fiber orientation, and showed grain deviations of more than 10o from vertical in both left- and right-handed directions. Grain changed at locally constant rates, separated by locations where the direction of grain change sharply reversed. Image thresholding and segmentation conducted on reconstructed cross sections allowed the identification of vessels and measurement of their location, with vessel orientations then calculated in Matlab and, independently, in recalculated tangential longitudinal sections with the DIRECTIONALITY plug-in. Vessel orientations varied more than fiber orientations, and on average deviated further from vertical than fibers at the locations where the direction of grain change reversed. Moreover, the reversal location for vessels was shifted ~ 400 μm towards the pith compared to the fibers, despite both cell types arising from the same fusiform initials within the vascular cambium. We propose a simple model to explain these distinct grain patterns. Were an auxin signal to control both the reorientation of cambial initials, as well as coordinating the end-on-end differentiation and linkage of xylem vessel elements, then it would be possible for fibers and vessels to run at subtly different angles, and to show different grain reversal locations.

Effect of growth stress and interlocked grain on splitting of seven different hybrid clones of Eucalyptus grandis×Eucalyptus urophylla wood

Trees with high levels of growth stress begin to show log end splits (LES) immediately after harvesting, usually reaching its maximum end split in a week, and these tensions also create splits during lumber manufacturing. Interlocked grain is another characteristic that impacts the properties of eucalyptus wood. The aim of this study was to evaluate the effect of growth stress and interlocked grain patterns on log end splitting of seven different hybrid clones of Eucalyptus grandis × Eucalyptus urophylla planted in Brazil. The growth stress indicator (GSI) was measured in standing trees before harvesting. Splits were measured on logs in three different stages, and interlocked grain from wood blocks was obtained across the center of the cross-section. The results showed that LES occurred as soon as the trees were harvested; however, for better selection of clones, LES should be evaluated after a week of harvesting. There were statistically significant correlations for GSI with LES. Clones that presented higher values of interlocked grain tended to develop lower values of GSI and LES. Using GSI and interlocked grain measurements, it was possible to select the most indicated eucalyptus clones for lumber production.

Sifat Dasar Kayu Ganitri (Elaeocarpus sphaericus (Gaertn.) K. Schum.) dari Sukabumi dan Potensi Penggunaannya

Ganitri (Elaeocarpus sphaericus (Gaertn.) K. Schum.) adalah pohon cepat tumbuh yang banyak ditemukan di Sukabumi. Kayu ini tumbuh di hampir semua wilayah Indonesia. Tulisan ini menyajikan hasil pengujian sifat dasar (struktur anatomi, kimia, sifat fisis dan mekanis) kayu ganitri yang diambil dari hutan rakyat di daerah Sukabumi. Tujuan penelitian adalah untuk mengetahui potensi penggunan kayu ganitri berdasarkan sifat dasar dan penggunaan kayu oleh masyarakat sekitar. Hasil penelitian menunjukkan bahwa kayu ganitri memiliki kayu teras berwarna kuning dan kayu gubal berwarna putih. Corak kayu polos dan tekstur halus. Arah serat lurus sampai berpadu, kayu lunak, tidak mengkilap, dan tidak berbau. Berdasarkan nilai dimensi serat dan nilai turunannya, kayu ganitri termasuk ke dalam Kelas Mutu II. Kayu ganitri memiliki kadar holoselulosa dan selulosa yang tinggi (70,70% dan 54,58%), kadar sedang untuk lignin 21,60%, ekstraktif alkohol-benzena 3,47%, dan kadar abu 0,81%. Dengan berat jenis (BJ) kering udara 0,35 kayu ganitri termasuk ke dalam Kelas Kuat IV. Kayu tersebut disarankan untuk digunakan sebagai bahan bangunan konstruksi ringan, perkakas, furnitur, kayu lapis, papan sambung dan produk panel. Basic Properties of Ganitri Wood (Elaeocarpus sphaericus (Gaertn.) K. Schum from Sukabumi and Its Potential UsesAbsractGanitri (Elaeocarpus sphaericus (Gaertn.) K. Schum.) is a fastgrowing tree that is widely found in Sukabumi, West Java. It grows in all part of Indonesia. A research was carried out to investigate basic properties (anatomical, physical, mechanical, and chemical) of ganitri wood from the community forest of Sukabumi. The purpose of this study was to determine the potential use of ganitri wood based on its basic properties and local utilization. The results showed that the color of ganitri sapwood was white , and it was not clearly demarcated from the yellow, with fewer figure patterns. The texture was fine with straight to interlocked grain. The wood was soft, not lustrous, and no special odor. Based on the fibre dimensions and derivative values, the quality of ganitri wood fell in Class II as a raw material for pulp and paper. Ganitri had high holocellulose and cellulose levels (70.70% and 54.58%), moderate level in lignin (21.60%), and it contained 3.47% extractive soluble in alcohol-benzene, and 0.81% ash. Based on its air dry specific gravity (0,35), ganitri wood could be classified into wood Strength Class IV. The potential uses of ganitri are for lightweight construction material, tools, furniture, plywood, connecting boards, and other panel products.

Population and vegetation structure of ramin (Gonystylus bancanus) in secondary forests of Ketapang District, West Kalimantan, Indonesia

Muin A, Astiani D. 2018. Population and vegetation structure of ramin (Gonystylus bancanus) in secondary forests of Ketapang District, West Kalimantan, Indonesia. Biodiversitas 19: 478-484. In the tropical peatland, ramin (Gonystylus bancanus Miq. Kurz) was one of many prominent species that present in peatland forest. The species distribution is mostly in Southeast Asia peatland. The beautiful wood color, pale yellow sometimes grayish with no differentiated sapwood and heartwood with straight interlocked grain, made it become the most wanted tree species from tropical peatland.The exploitation of Ramin wood since the 1970s caused the decrease of its population in the peatland forest, led to this species being listed as an endangered species. This study aimed to search information on the Ramin population and vegetation structure left in its habitat in secondary peatland forest of Pematang Gadung and Sungai Sirih villages area of Ketapang District. The study employed a survey method, and data collection was carried out using line plots system. Data assessed were natural regeneration condition-seedling, sapling and pole growth levels-, and tree growth levels. A 20 m x 20 m size plots were continually established to form a line with the length of 550-680 m. Results showed that relatively a few Ramin was found in the forests in Sungai Sirih with a mean seedling density of only 9.9 tree ha-1, height ranges of 131 cm to 150 cm, and counted sapling level of 183 trees ha-1 with diameter ranges from 0.38 to 6.37 cm. At Pematang Gadung village, more Ramin was found, especially with a bigger diameter. Tree level (diameter >20cm) was recorded at 74.1 tree ha-1 with a contradictory far less seedling (2.8 tree ha-1), sapling level (only 1 tree ha-1) and pole level (7.4 tree ha-1) established. Based on the tree population condition and the variation of their growth level, the vegetation structure of Ramin did not describe a normal curve form in the natural forest both in the villages of Pematang Gadung and Sungai Sirih.

Georgia marble at the Minnesota State Capitol The Effects of Mineralogy and Climate on Durability

Based on visual observations and tests made of Georgia marble units that have been in service at the historic Minnesota State Capitol for 110 years, a fielddiscernible correlation exists between marble unit mineralogical composition and unit weathering performance. Field studies noted over the course of a five-year restoration project of the capitol exterior were used to categorize the original marble cladding into four perceptible types, which were evaluated by field testing that suggested a correlation between the textural and mineralogical differences within the marble and its long-term durability. To test this theory, field-issued repair assignments made during an exterior marble restoration project at the capitol were examined statistically. The nature and frequency of assigned repairs were compared to the type of marble from which they were originally fabricated to determine whether a correlation existed. The results of this comparison provided convincing statistical verification of the link between mineralogy and durability. This hypothesis was then verified through detailed petrographic analysis in a laboratory setting, which determined that marble consisting of a smaller, more interlocked grain configuration that was more dolomitic than calcitic in its basic chemistry consistently proved to be more durable in weathering performance over time. The paper describes the process followed by the authors to categorize and study the distinct varieties of Georgia marble present on the Minnesota State Capitol, and how this information was used to guide the restoration process with the intent of maximizing the anticipated service life of new marble replacements.

Method for the integral calculation of the fiber orientation and the fundamental material properties of softwood logs and lumber

An integral calculation method (ICM) is presented for fully estimating the fiber orientation and fundamental physical and mechanical properties of softwood (SW) logs and lumber. The proposed ICM reproduces with great detail the most important anatomical features of SW, including annual rings, seasonal variations, main growth patterns (straight, spiral, and interlocked grain), and especially fiber distortions due to knot clusters for each annual ring. The failure load of the lumber has been predicted with an absolute error of 10.2%. In addition, the ICM has shown very strong robustness and high calculation speed as most of the calculations are performed analytically, and only one final simplistic computation is conducted by finite element analysis (FEA). This article describes the proposed ICM in detail and shows the initial verification with experiments. The ICM should contribute not only to lumber research and grading but also to research and optimization of logging and sawing industrial processes.

Unidirectional splitting and uniting of rays in the cambium of Platanus accompanying the formation of interlocked grain in wood

Developmental changes in the cambium producing interlocked grain wood of <i>Platanus</i>, were determined by an analysis of successive late xylem layers (TLX) at the borders of the annual rings. Intensive splitting and uniting of rays were observed. These occured by intrusion of fusiform cells into the rays and by loss of the fusiform initials which formed the strands separating the rays, respectively. Uniting of rays was unidirectional within the large areas of cambium (domain), so was the splitting, too. There were domains of Z and S-type. Orientation of splitting and uniting of rays at a particular locality of the cambium was reversed at irregular time intervals. It appears that the reason for these reversals was slow movement of domain pattern. The occurrence of alternating Z and S domains brought about the alternation of the grain inclination from right to left and back again in the interlocked-grained wood.

Movement of the cambial domain pattern and mechanism of formation of interlocked grain in Platanus

The orientation of splitting and uniting of rays, which served as an indicator of the orientation of morphogenic events occurring in cambium, was determined on series of veneers covering large tangential faces of <i>Platanus</i> trunks. It has been shown that cambium consists of orientational domains of Z- and S-type. They are perpendicular to, or slightly inclined with respect to, the trunk axis. Axial dimensions of domains are 8-28 cm. They move upward along the trunk, at a rate 6,5—12 mm, per radial mm of xylem porduced. Migration domain patterns are responsible for the formation of the interlocked grain.

Mechanism of changes in grain inclination in wood produced by storeyed cambium

The changes in cell orientation in the cambium of <i>Entandrophragma</i> producing wood with interlocked type of grain, and in the cambium of <i>Tilia</i> in a spirally girdled stem are traced through serial tangential sections of wood. In <i>Entandrophragma</i> the changes result from the intrusive growth of a fusiform cell whih repeatedly produces a new pointed tip from one side of the existing tip which disappears. This causes a sort of creeping of cell ends of one storey past those of the adjoining storey. The oppositely directed ends of the cells belonging to one storey creep in opposite directions so that the position of the cell centres remains constant and only the angle between the cells and the stem axis changes. The stratification of short rays in <i>Entandrophragma</i> represents an adaptation to the changes in celi orientation involved in the formation of interlocked grain. The mechanism of changes in grain inclination in <i>Tilia</i> is intermediate between that based on the creeping of cell ends and that based on pseudotransverse division and intrusive elongation which is known in non-storeyed cambia.