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Acetylation of softwoods has been largely investigated to increase the dimensional stability and biological resistance of wood. However, the knowledge of this technology has not been applied to tropical hardwood species up to date. The objective of this work was to study the effect of acetylation on nine tropical hardwood species, from forest plantations in Costa Rica, by applying acetic anhydride in three different treatment times (1 h, 2.5 h, 4 h), as well as to evaluate this by Fourier-Transform Infrared Spectroscopy (FTIR). Results showed that weight percentage gain (WPG) of wood varied from 2.2 to 16.8%, withVochysia ferrugineaspecies showing the highest WPG, andGmelina arboreaandTectona grandisspecies exhibiting the lowest WPGs. Tropical woods such asEnterolobium cyclocarpum,Hieronyma alchorneoidesandSamanea samanexhibited statistical differences among treatment times, whereas the rest of the species studied showed no significant differences. In general, the most effective acetylation time was 2.5 h for all the species. The ratio of intensity (RI) from the FTIR spectra was greater at the 1732 cm−1, 1372 cm−1and 1228 cm−1peaks for all tropical species, associated with lignin. A good correlation between the RI of those peaks and WPG was found; the same was also found between all RIs and each other. Meanwhile, RI associated to the hemicelluloses and lignin (1592 cm−1and 1034 cm−1peaks, respectively) showed no correlation with WPG, nor between each other or with the other RIs. Furthermore, it was suggested that RI at 1732 cm−1(associated to acetyl groups C=O) can be considered as a reliable indicator of the degree of acetylation for tropical hardwood species. Finally, it was observed that tropical hardwoods having more suitable anatomical features, like larger vessel diameter, higher ray width and frequency, and lesser deposits such as gums and tyloses in the vessels, resulted in significantly higher WPGs.

Tectona grandis (teak) is an important commercial tree species that is widely used in tropical dendrochronology due to the formation of climate-sensitive annual growth rings. However, young trees growing in plantation conditions exhibit poor ring visibility during the first years of growth, limiting the dendrochronology application. In the present study, we use x-ray densitometry to determine the wood density profile between and within annual rings and at the sapwood-heartwood boundary in trees from fast-growth plantations. The resulting wood density profiles (WDP) can be categorized as uniform, stable growth, unstable growth, and false. The annual ring boundaries were indistinct in trees less than 8 years old. In mature trees, the annual ring boundaries are more defined. In relation to the sapwood-heartwood boundary, the WDP showed a decrease in the wood density; however, this decrease is influenced by the annual ring boundary when the two boundaries coincide. The identification of annual rings in trees growing in fast-growth plantations should be combined with X-ray densitometry and visual identification if wood density data are necessary for deriving other analysis, as climate change, from annual ring.

To elucidate the development of heartwood, bark, sapwood, pith and specific gravity of wood in fast-growing teak (Tectona grandis) plantations in Costa Rica, we sampled three trees in each of 55 plantations and modelled each variable with age, site and different tree heights. Age and stand density of plantations were significant correlated with stem diameter at breast height and total height of the tree. Formation of heartwood was initiated at the age of 4-year-old and increased in direct proportion with age. The age of plantation had a significant relationship with stem diameter at breast height, heartwood percentage, sapwood thickness, sapwood percentage, percentage of bark, pith diameter and percentage, and specify gravity. The model for these tree parameters was model with these parameters as dependent variable and in relation to age as independent variable.

Tectona grandis is the second most important species for reforestation in Costa Rica, and any improvement in its industrialization process is important, especially the drying process. Lumber obtained from a plantation of 12-year-old T. grandis trees was used to evaluate three drying schedules that include integrated steaming processes to determine the combined effect of the steam-drying system on the dried lumber. The variations in the moisture content (MC) and drying rate (DR) with drying time (DT) both before and after the steaming process were modeled mathematically for boards that have a flat and quarter grain pattern. For both types of boards that were dried with and without steaming, a relationship between MC and DT was observed. There was inflexion at 40%, and two mathematical models were computed. Additionally, the relationship between DR and DT for boards with flat and quarter grain patterns was not affected by the steaming process, and an inflection point was observed at 30 h (40% MC for...

The influence of climatic and site fertility conditions affect wood quality from fast growing trees. The change in tree diameter, thickness of sapwood, heartwood percentage and bark and pith tissue, physical and mechanical properties, resistance to termite attack and the presence of drying defects on lumber boards were evaluated. Four teak trees (Tectona grandis L.f.) from fast growing plantations in Costa Rica were selected for the study. Teak trees of 11 years old growing in two climatic conditions and two fertility types (high and low fertility) in Costa Rica were studied. The results showed that tree diameter, sapwood thickness, pith diameter and its percentage were higher in the climate with more rainfall and greater fertility. However, the percentage of heartwood and bark were higher at low fertility sites with less rainfall. It was also observed that only sites with low fertility produce modifications in specify gravity, fiber saturation point, initial moisture content, MOR in flexion in green and dry condition, MOE in bending and resistance to termite attack. Incidence and magnitude of defects increased with drying, and were mainly affected when wood comes from younger trees from high fertility sites and growing in tropical moist forest climate. © 2015, Indian Academy of Wood Science.

La présente étude vise à établir les variations du duramen (pourcentage, diamètre, rayon, volume) rapportées à la hauteur des arbres et à l’épaisseur de l’aubier, ainsi que l’âge de début de formation du duramen et sa hauteur maximale pour les arbres de l’essence Tectona grandis. Les résultats de l’échantillonnage de seize plantations réparties dans différentes zones du Costa Rica, âgées de 2 à 22 ans, montrent que l’aubier est plus épais entre 2 et 10 ans d’âge qu’entre 10 et 22 ans. La formation du duramen commence à la base des arbres âgés de 2 à 3 ans, mais il n’apparaît à hauteur de poitrine qu’à partir de 3 à 4 ans. Le duramen disparaît à une hauteur allant de 0 à 90 % de la hauteur totale selon l’âge de l’arbre. Enfin, des modèles statistiques prédictifs ont été développés pour l’épaisseur de l’aubier et pour le rayon, la hauteur maximale et le pourcentage du duramen, en se basant sur le modèle Y = K0 + K1*(épaisseur de l’aubier) + K2*(hauteur relative de l’échantillonnage) + K3*(diamètre à hauteur de poitrine) + K4*(âge de l’arbre). Ces modèles indiquent des coefficients de détermination de 70 %, 90 %, 95 %, 73 % et 31 %, respectivement.

International audience; Wood colour of Tectona grandis produced from fast-growth plantations is highly variable and the causes of this variation are relatively unknown.* With the purpose of understanding the colour variation, different fast-growth plantations were sampled with different growth rates, tree ages, and sites.* Wood colour was measured with a CIELab system, where three variables are estimated: coordinate L* for lightness, coordinate a* defines redness and coordinate b* defines yellowness.* Results showed only a negative correlation between L* and a*. L* and a* were negatively and positively respectively correlated with pith distance in heartwood, but not for b*. No correlations were found between L* and b* in sapwood and plantation characteristics, while a* was positively correlated with age and height of tree and growth rate. In heartwood, tree age and diameter at breast height were correlated with all colour parameters, but tree height and plantation density were correlated with a* and b*. Cluster site had correlation with L*. Multiple correlation analysis showed that the heartwood is increasing darker (L*) and redder (a*) when the trees are older and bigger. Correlation coefficient shown that sapwood and heartwood with lighter colour (L*) is less resistance to fungal attack, but redness colour (a*) increasing decay resistance.; Il y a une grande variabilité de la couleur du bois de Tectona grandis produit à partir de plantations à croissance rapide et les causes de ces variations sont relativement inconnues.* Pour comprendre l'origine des variations de couleur nous avons échantillonné dans des plantations à croissance rapide qui diffèrent entre elles en termes de vitesse de croissance, d'âge et de site.* La couleur du bois a été mesurée avec le système CIELab qui permet la mesure de trois variables colorimétriques: la luminance L* allant du noir au blanc, a* et b* allant respectivement du vert au rouge et du bleu au jaune.* Les résultats montrent une corrélation négative entre L* et a*. Dans le bois le cœur il y a une corrélation négative entre L* et la distance à la moelle et une corrélation positive entre a* et la distance à la moelle: aucune corrélation n'apparaît pour b*. Dans l'aubier, on ne trouve aucune corrélation entre L* et b* et les caractéristiques des plantations. Cependant a* est corrélé positivement avec l'âge, la hauteur et la vitesse de croissance des arbres. Dans le bois de cœur, l'âge et le diamètre à 1,3 m des arbres sont corrélés avec les trois coordonnées chromatiques mais la hauteur des arbres et la densité de plantation sont corrélées avec a* et b*. Il y a une corrélation entre le site et L*. On montre que le bois de cœur est d'autant plus sombre et rouge que les arbres sont plus vieux et plus gros. Les corrélations obtenues montrent que les bois d'aubier et de cœur qui sont les plus clairs résistent moins bien aux attaques fongiques et que les bois de tendance plus rougeâtre ont une meilleure résistance aux pourritures.

The color of Tectona grandis wood is an attribute that favors its commercialization, however, wood color from fast-growth plantation trees is clear and lacks uniformity. The aim of this work is to characterize steamed teak wood by means of the Fourier transform infrared spectroscopy (FTIR) and [Formula: see text] color systems. Two moisture conditions (green and 50%) and two grain patterns (flat and quarter) of boards were analyzed through the application of different steaming times (0, 3, 6, 9, 12, 15 and 18[Formula: see text]h). The FTIR results showed that the bands at 1158, 1231, 1373 and 1419[Formula: see text]cm[Formula: see text] did not show any change with steaming, whereas the bands at 1053, 1108, 1453, 1506, 1536, 1558, 1595, 1652, 1683, 1700 and 1733[Formula: see text]cm[Formula: see text] presented a decrease in the intensity with the steaming time. The band at 1318[Formula: see text]cm[Formula: see text] was the only one that increased. Lightness ([Formula: see text]) was the most affected parameter, followed by yellowness ([Formula: see text]), while redness ([Formula: see text]) showed the smallest change. Surface color change ([Formula: see text]) presented the lowest value between 3[Formula: see text]h and 6[Formula: see text]h of steam-drying in the boards with flat grain, whereas for boards with quarter grain, the smallest [Formula: see text] value was obtained after 18[Formula: see text]h of steaming.

The objective of this study was to show the radial variation of some anatomic characteristics, wood density and natural durability of teak (Tectona grandis L.F.) growing in Costa Rica. Samples of trees 13 years old were obtained from two growing sites (high and low growing) of plantations established in a humid tropical climate (CHT) and dry tropical climate (CST). The variables measured of the fibers as well as for the rays were not affected by the climate or the type of growing site, except for the length of the fibers. The fibers of teak wood from the best growing site were significantly larger. Vessels were found with a greater frequency for the CST but mostly solitary in comparison with the CHAverage density, maximum density and the variation within the ring presented a light higher magnitude for the CSThe quality of the growing site did not affect these variables. The resistance of fungus attack was similar in the area of heartwood near the pith compared to the heartwood near the sapwood for all the conditions evaluated. Nevertheless, it was observed in some trees a similar resistance of fungus attack for areas of sapwood compared to similar areas of heartwood. Con el objetivo de mostrar la variación radial de las características anatómicas, de densidad normal y de durabilidad natural de la madera de Tectona grandis L.f. creciendo en Costa Rica, se muestrearon plantaciones de 13 años procedentes de dos regiones con clima diferente: clima húmedo tropical (CHT) y clima seco tropical (CST). En cada una de ellas se analizaron dos tipos de sitios con diferente fertilidad: bueno (SB) y malo (SM). Se encontró que las fibras y los radios no fueran afectados por el tipo de clima o calidad de sitio, a excepción de la longitud de la fibra que sí fue afectada. Se encontró que CST produce mayor frecuencia de vasos, pero en su mayoría solitarios en relación al CHT, la densidad normal promedio, máxima y su variación dentro del anillo, presentan magnitudes mayores en CST que CSH. La calidad de sitio no afectó estas variables. La resistencia al ataque de hongos fue similar en el duramen próximo a la médula y el duramen próximo a la albura para los dos tipos de clima y las calidades de sitio. No obstante, se observó que en algunos árboles la resistencia al ataque de los hongos del duramen fue similar a la albura.