WOOD COLORIMETRY FOR THE CHARACTERIZATION OF AMAZONIAN TREE SPECIES: A SUBSIDY FOR A MORE EFFICIENT CLASSIFICATION

ABSTRACT The wood of different species may present macroscopic similarities, which hinders a reliable differentiation between the specie. This can be a problem, especially in the tropics, given the high species diversity in this region. To overcome this problem of wood identification, colorimetric criteria can be applied, aiming at a better and more objective classification, as opposed to the traditional anatomic criteria. Therefore, the aim of this research was to analyze the variability of the wood color considering the cutting planes (tangential and radial) and to determine its correlation with the wood basic density of ten Amazonian tree species. The following species were studied: Apuleia leiocarpa (amarelão), Hymenolobium modestum (angelim-pedra), Anadenanthera columbrina (angico), Dipteryx odorata (cumaru), Pouteria pachycarpa (goiabão), Mezilaurus itauba (itaubá), Hymenaea courbaril (jatobá), Simarouba amara (marupá), Astronium leicontei (muiracatiara) and, Bowdichia nitida (sucupira). The CIEL*a*b* system was used to determine the colorimetric parameters (L*, a*, b*, C*, and h*), which were obtained through a portable colorimeter. The species were classified in six color specific groups: light yellow, olive brown, yellowish olive, olive light, grayish white and reddish brown. We observed statistical effect of the cut planes only for luminosity, with higher mean for radial face. The correlation analyses between color and basic density showed that the denser woods are darker and have more red pigment (a*). There is negative correlation between luminosity (L*) and wood basic density (-0.78). The colorimetric parameter a* presented positive correlation with the basic density (r = 0.80).摘要 不同树种的木材往往呈现宏观形态相似性，这给可靠的树种鉴别带来了极大阻碍。这一问题在热带地区尤为突出，因该区域树种多样性极高。相较于传统解剖学鉴定标准，采用比色判别准则可实现更精准、更客观的分类，从而解决木材鉴别的痛点。 因此，本研究旨在分析不同切面（弦切面与径切面）下木材颜色的变异性，并探究其与10种亚马逊树种木材基本密度的相关性。本研究涉及的树种包括：光叶阿普尔木（Apuleia leiocarpa，俗称amarelão）、谦逊膜荚豆（Hymenolobium modestum，俗称angelim-pedra）、阔荚相思（Anadenanthera columbrina，俗称angico）、香豆木（Dipteryx odorata，俗称cumaru）、厚果桃榄（Pouteria pachycarpa，俗称goiabão）、伊塔乌巴樟（Mezilaurus itauba，俗称itaubá）、孪叶豆（Hymenaea courbaril，俗称jatobá）、苦木（Simarouba amara，俗称marupá）、莱氏漆树（Astronium leicontei，俗称muiracatiara）及光亮鲍迪豆（Bowdichia nitida，俗称sucupira）。 本研究采用CIEL*a*b*颜色系统测定比色参数（L*、a*、b*、C*及h*），相关参数通过便携式色差仪获取。研究将供试木材划分为6个特定颜色组别：亮黄色、橄榄棕、黄橄榄色、浅橄榄色、灰白色及红棕色。统计分析显示，切面仅对木材明度存在显著影响，径切面的明度均值更高。 颜色与基本密度的相关性分析结果表明：木材密度越高，其颜色越深且红色调（a*值）越强。其中明度（L*）与木材基本密度呈显著负相关（相关系数为-0.78）；比色参数a*与基本密度呈显著正相关（相关系数r=0.80）。