Study On Structure Characteristics Of Major Commercial Timbers In Nicaragua

Paper researched 28 species of main commercial wood from Nicaragua, observing the three sections with stereoscopic microscope, briefly introducing the macroscopic features such as colour, heartwood and sapwood distinction and vessel types. Meanwhile making permanent slices and observing the microscopic structure features. Some vestured pits have been observed under SEM and classified according style. Paper studied their material property, color and fluoresces of water extract and its ethanol extract of all 28 species, explored new methods of wood identification and provided a theoretical basis for the identification of main commercial wood from Nicaragua. Conclusions are below:(1)Research studied on how to distinguish 28 species of main commercial wood from Nicaragua which belong to Aceraceae, Bignoniaceae, Boraginaceae, Burseraceae, Leguminosae, Combretaceae, Meliaceae, Guttiferae and so on. These woods have these features below: Wood diameter class being high, annual ring mostly being not obvious, mostly diffuse-porous wood, mostly simple perforation plates, nonstoried wood ray, tylosis and gum being rich in vessel, and most of them have septate fibres and vestured pits. Paper’s research provides important reference value for wood identification, wood trade and wood using.(2)Paper shows that the shape of the vestured pits do not actually change after the treatment. For the reason above, we could classify these vestured pits without chemical treatment.(3)Paper scanned pits of 11 species by SEM and classified them. It shows that they can divide into two groups. The first group is unbranched vestured(8 species), concluding Dialium guianse(spherical), Hymenaea courbaril(spherical), Dalbergia retusa(spherical), Dalbergia tucurensis(papillae), Myroxylon(irregular), Ormosia sp.(spherical), Enterolobium cyclocarpum(spherical), Pithecellobium arboretum(spherical、irregular). The second group is branched vestured,concluding Terminalla Amazonia(dendritic), Pterocarpus officinalis(forked-shaped), Vochysia hondurensis(dendritic).(4)Paper analyze Sloanea sp.,the result shows that no vestured pit is found during the study.(5)Different species’ crystallinity are different. The range of 28 species of main commercial wood from Nicaragua relative crystallinity is 34.04%~62.14%.These tropical hardwoods have crystallinity around 47%.(6)Generously, among one species, the ethanol extract fluoresces while its water extract does not. But among these woods, some species’ water extract have fluoresces while its ethanol does not. Strong fluoresces on water extract occurs on Fabaceae for an instance Platymiscium sp., it shows strong blue fluoresce. Strong fluoresces on ethanol extract occurs on Fabaceae and Caesalpiniaceae for instances Hymenaea courbaril shows strong green-yellow fluoresce, Dalbergia tucurensis shows strong green fluoresce. For the reason, the fluoresce is an important feature to identify a wood, which is quite easier than the way based on wood anatomy.(7)Water extract basically colourless to brown or shades of brown is the most common of the water extract feature colours. In this paper, water extract colours variation of parameter L*,a*,b*,V,C and H of 27 species are 20~28,1~4,0~5,1~2,0~3,4R~8YR. Most of them are in the zone of(YR), low lightness scope, entirely black and orange. ethanol extract colours variation of parameter L*,a*,b*,V,C and H of 27 species are 19~28,1~3,1~4,1~2,0~2,4R~4Y. Most of them are in the zone of(YR), too. Low lightness scope, entirely black and shades of red. Through cluster analysis showed that the color of the 27 kinds of the water extract, is divided into six classes; ethanol extract color, divided into five classes.