Functional chemical, physical, and mechanical traits of Amazonian forest species from different ecological groups using NIR spectroscopy

The variation in xylem properties may reflect the ecological functional strategies of each species. In this study, we evaluated the anatomical characteristics and quantified the chemical, physical, and mechanical traits of the wood of Simarouba amara (marupá), Scleronema micranthum (cardeiro), and Manilkara huberi (maçaranduba), species belonging to different ecological groups, using near-infrared (NIR) spectroscopy. The samples were collected from a terra-firme forest in Amazonas/Brazil, and 10 cm thick discs were extracted from the tree trunks at breast height. The samples were prepared to obtain transverse, radial, and tangential NIR spectra. The wood of Simarouba amara (low density) presented an anatomical profile with vessels measuring 253 ± 23 µm in diameter, a frequency of 3.65 ± 1.22 vessels/mm 2 , a low extractive content (1.98 ± 0.55%), and a low modulus of elasticity. In contrast, M. huberi (high density) exhibited the opposite profile, characterized by a high vessel frequency (13.32 ± 0.34 vessels/mm 2 ), relatively small vessel diameters (99 ± 2 µm), high extractive content, and high modulus of elasticity and modulus rupture. The wood of Scleronema micranthum was notable for its higher content of polyphenols (11.83 ± 2.51%), holocellulose (59.12 ± 2.69%), and a medium density (0.65 ± 0.04 g/cm 3 ). The results of the wood characteristics assessed in this study reinforce the reliability of NIR spectroscopy as a robust tool for estimating the traits of different ecological groups of tropical species.