Diversity of wood colour in tropical timber species and its relationship with wood density and anatomical features

The wood colour variability of 98 tropical species from India (Goa), Mozambique and East Timor was described using CIELab colour parameters and related to wood density and anatomical features. Wood colours were mostly light and yellowish, ranging from 24.0–84.4 for wood lightness, 2.6–20.4 for redness, 1.8–36.6 for yellowness, 2.1–35.9 for chromaticity and 27.5–81.6 for hue angle. Among the colour parameters, the positive correlation between L* and b* was the most significant, followed by a negative correlation between L* and a*, while the positive correlation between a* and b* was non-significant. Positive correlations between L* and both h and C* were also highly significant. CIELab colour parameters were significantly correlated to wood density, the stronger negative correlation was found with L*, followed by the negative correlation with b*. Wood colour was not strongly correlated with the quantitative anatomical features studied showing only weak negative correlations between L* and the fibre wall thickness/fibre width ratio and between b* and fibre length. Wood density was correlated to almost all anatomical features showing the strongest correlations with fibre wall thickness/fibre width ratio and fibre width. The darker-coloured tropical woods showed high wood density, high fibre wall proportion, high vessel frequency and narrow vessels compared to the lighter coloured woods. Overall, wood colour diversity of tropical species could contribute to increase the international timber market by including lesser-known species, which would enhance local development and sustainability of endangered tropical species.