Caracterização físico-química e energética da madeira de duas espécies exóticas de ocorrência no semiárido Braisleiro.

Abstract

The use of wood from exotic species present in the Caatinga for energy purposes has become an alternative, contributing to the reduction of intensive exploitation in the native vegetation of this biome. Thus, this research aimed at evaluating the physical, chemical and energetic attributes of the wood from the exotic species Prosopis juliflora (Sw.) D.C.) and Leucaena leucocephala (Lam.) R. de Wit), so that they are better used. From each tree, 5 cm thick discs were removed at 0 (base), 25, 50, 75 and 100% of the commercial trunk height. Each disc was subdivided into four wedge-shaped parts, passing through the medulla. Two of them, diametrically opposite, were used to determine the basic density and the rest was reserved for chemical and energetic analyses. The species Prosopis juliflora showed higher values of dry mass (77.92 kg), basic density (779.31 kg.m-3) and heartwood/sapwood ratio (1.00) of wood, with significant differences between species. Leucaena leucocephala showed a higher content of insoluble lignin (28.17 %); in contrast, Prosopis juliflora showed higher levels of alcohol/toluene (A:T) extractives (9.75%) and wood ash (2.20%). The energy density of wood (3.73 Gcal.m-3) was higher for Prosopis juliflora, but there was no significant difference between species. Regarding the higher and lower calorific value and the contents of fixed carbon and volatile materials, the species showed similar values for wood and charcoal. Gravimetric yield (42.33%) and charcoal productivity (329.77 kg.m- 3) were higher for Prosopis juliflora, showing significant differences between species. Therefore, the woods of those species have characteristics that are favorable for energy consumption.