STRUCTURAL VARIATIONS IN ROOT AND STEM WOOD OF STYRAX (STYRACACEAE) FROM BRAZILIAN FOREST AND CERRADO

Abstract

The genus Styrax L. (Styracaceae) has a wide distribution in Brazil, occurring in diverse ecosystems. To get a better insight into the ecologieal adaptations ofwood strueture, we studied two speeies, S. camporum and S.jerrugineus from the cerrado, and three species, S. latifolium, S. martii and S. leprosus from the Atlantie forest. For each species, the wood of root and stern was analyzed separately and observations inc1uded qualitative as well as quantitative wood characteristics. The results show that there were significant anatomical differences between the forest and cerrado species as well as between the root and stern wood within single species. Quantitatively, the most informative features in the root wood that separated the forest from the cerrado species were diameter, length and number of vessels, length of fibres, and width and frequeney of rays. In the stern wood, length and frequency of vessels, length of fibres, and width and frequency of rays were the most informative features. In contrast to the forest species, which had larger vessel diameters in their stem wood, the cerrado species had larger vessel diameters in their root wood. The ca1culated vulnerability index indicates that all Styrax species have adaptations to mesic conditions. The cerrado species had the smallest index values, which could be related to the seasonally dry condition of this environment.