The present study aimed to evaluate the dendrometric and chemical characteristics and variation of basic density and moisture content (green) of the wood of five Caatinga forest species along the commercial longitudinal direction (base-top) of logs. The studied species were pau-branco (Auxemma oncocalyx (Fr. All.) Taub.), jurema preta (Mimosa tenuiflora (Willd.) Poir.), jurema-de-embira (Mimosa ophthalmocentra Mart. ex Benth.), pereiro (Aspidosperma pyrifolium Mart.) and sabiá (Mimosa caesalpiniifolia Benth.). Fifteen trees were harvested, three of each species. The trees had diameter at breast height of 8 to 12 cm. Five disks with thickness of 10 cm were removed from each tree at the positions 0 (base), 25, 50, 75 and 100% of the commercial height. The dendrometric characteristics showed that the choices of the trees contributed to a better analysis of the physicochemical properties of the wood. The five studied species could be described by the same model of longitudinal variation of basic density, decreasing from the base to top, while the moisture content (green) presented inverse behavior, with an increase in this same direction. All species had good quality for the production of sawn lumber, veneers, firewood and charcoal. In the chemical composition, the wood presented constituents that convey natural durability, as well as use for energy purposes.

RESUMO Dentre as espécies lenhosas da Caatinga, três podem ser destacadas devido a sua frequência e potencial de uso: Aroeira (Myracrodruon urundeuva Allemão), Pereiro (Aspidosperma pyrifolium Mart.) e Jurema de Embira (Mimosa ophthalmocentra Mart. ex Benth.). Diante disto, objetivou-se caracterizar e correlacionar as propriedades físicas destas madeiras provenientes de árvores de diferentes classes diamétricas. Nove indivíduos de cada espécie estudada foram coletados de acordo com seus diâmetros à altura do peito e suas amostras separadas em três categorias de classe diamétrica: de 5 a 7,5 cm; de 7,51 a 9,5 cm; e de 9,51 a 16 cm. Determinou-se a massa específica básica e os índices de contração volumétrico e lineares nos diferentes sentidos (tangencial, radial e longitudinal). As madeiras estudadas apresentaram propriedades físicas influenciadas tanto pela espécie quanto pela interação entre espécie e classe diamétrica, com exceção da contração tangencial, que foi influenciada apenas pela espécie. As classes diamétricas influenciaram somente as contrações radial e tangencial. As espécies apresentaram valores de coeficientes anisotrópicos que as classificam como de boa estabilidade, independentemente de suas classes diamétricas. Palavras-chaves: Myracrodruon urundeuva; Aspidosperma pyrifolium; Mimosa ophthalmocentra; massa específica básica; retratibilidade. Physical properties inter and intra species of Caatinga ABSTRACT A Among wood species of Caatinga, three can be pointed out due to their frequency and use potential: Aroeira (Myracrodruon urundeuva Allemão), Pereiro (Aspidosperma pyrifolium Mart.) and Jurema de Embira (Mimosa ophthalmocentra Mart. ex Benth.). Thus, this work aimed to characterize and correlate the physical properties of those wood species from trees of different diametric classes. Nine invidious from each studied species were collected according to their breast height diameter, and the specimens were separated into three category of diametric classes: from 5 to 7.5 cm; from 7.51 to 9.5 cm; and from 9.51 to 16 cm. Basic specific gravity and volumetric and linear (tangential, radial and longitudinal) shrinkage indexes were determined. The studied woods showed physical properties influenced by species and by the interaction between species and diametric classes, with exception of tangential shrinkage, that was influenced only by species. Only diametric classes difference was able to influence just radial and tangential shrinkage. The species showed an anisotropic coefficient value that can be classified as woods of good stability for all diametric classes.

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