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外观相似性，这给不同树种的可靠区分带来了阻碍。这一问题在热带地区尤为突出，因为该区域的物种多样性极高。为解决木材识别难题，相较于传统的解剖学鉴定标准，采用比色鉴定标准可实现更精准、更客观的分类。因此，本研究旨在分析不同切削平面（切向与径向）下木材颜色的变异性，并探究其与十种亚马逊树种木材基本密度的相关性。本次研究涉及的树种如下：Apuleia leiocarpa（俗称amarelão）、Hymenolobium modestum（俗称angelim-pedra）、Anadenanthera columbrina（俗称angico）、Dipteryx odorata（俗称cumaru）、Pouteria pachycarpa（俗称goiabão）、Mezilaurus itauba（俗称itaubá）、Hymenaea courbaril（俗称jatobá）、Simarouba amara（俗称marupá）、Astronium leicontei（俗称muiracatiara）以及Bowdichia nitida（俗称sucupira）。本研究采用CIEL*a*b*色空间系统测定比色参数（L*、a*、b*、C*及h*），相关参数通过便携式色差仪获取。研究将受试树种划分为六大颜色组别：浅黄、橄榄棕、黄橄榄、浅橄榄、灰白及红棕。仅在明度指标上观察到切削平面的统计学显著效应，径向切面的平均明度更高。颜色参数与木材基本密度的相关性分析结果显示，密度更高的木材颜色更深，且红色分量（a*）更高。具体而言，明度（L*）与木材基本密度呈显著负相关（r=-0.78），比色参数a*与基本密度呈显著正相关（r=0.80）。