Potencial energético de espécies lenhosas da caatinga para uso de biomassa em plano de manejo florestal

Abstract

The knowledge of the physical and mechanical properties of the wood allows determining the best way to use the products exploited in the forests, also, generate subsidies so that the impacts caused by the harvesting activities minimized. In the Caatinga, typical vegetation of the Brazilian northeast, the woody species historically are used in the production of energy from its biomass, but without detailed studies as to its quality for this purpose. The objective of this work was to characterize the wood coming from six woody species native to the Caatinga regarding chemical properties and their energy potential. The study area located in the municipality of Floresta, Pernambuco, and samples of the wood were collected based on diametric classes defined in continuous forest inventories executed in the area. Each species had three individuals sampled in five classes of the circumference at 1.30 m of soil (CAP) and with an amplitude of 6 cm. From each a disk collected, in which the apparent density, the contents of carbon, hydrogen, and nitrogen, the contents of insoluble lignin and ash determined. A variance analysis performed considering a completely randomized factorial arrangement, taking as factors the species (six), the circumference classes (five), with three replicates, and for the comparison of means, the Tukey test considered. Pearson's correlation coefficient was applied, to measure the degree of relationship between the different variables. The developed analyses allowed to identify that Mimosa ophthalmocentra and M. tenuiflora obtained the best characteristics regarding the apparent density, hydrogen content, upper and lower calorific value and energy density of the wood, which places them as relevant for the selection of lignocellulosic elements for energy production. The diameter class 24.0 - 29.99 cm provided wood of low nitrogen contents and high values in upper and lower calorific power, providing better biomass products for the generation of energy. M. ophthalmocentra, M. tenuiflora, Anadenanthera colubrina and Poincianella bracteosa stand out for energy generation. M. ophthalmocentra and M. tenuiflora stood out for having more energy per unit volume. A. colubrina and P. bracteosa despite good energy quality can increase the environmental and maintenance costs of combustion equipment. Cnidoscolus quercifolius and Aspidosperma pyrifolium did not present good indicators of energy quality, indicating that they should not be subject to forest management for this purpose. The production of wood for energy purposes should prioritize according to the diameter class.