Resistência natural de madeiras de cinco espécies do bioma Caatinga em ensaio de campo

Abstract

The present study aimed to evaluate the natural wood resistance of five native species of the Caatinga in a field test and correlate with the physical-chemical characteristics. For this purpose, three trees were slaughtered by species and discs were removed at 0 (base), 25, 50, 75 and 100% of the commercial height of the stem to determine the physical properties (basic density, moisture content and porosity) and chemical properties (holocellulose, lignin, extractives and ash). In the biological analyses, a log of approximately 1,20 m was used obtained from the first section of each tree. As a standard of comparison, Eucalyptus sp. wood treated with CCA was used. To perform the test in field, 36 samples (six by species) with dimensions of 50 cm in length and 8 to 12 cm in diameter were made, in which they were distributed in a randomized blocks. The samples remained buried vertically in the soil up to half their length for one year, and were analyzed every two months. In test, the loss of mass, deterioration index (notes), and the susceptibility index to deterioration (DSI) were evaluated. The natural durability of Caatinga woods showed varied results under the factors of biodeterioration, in which as species Auxemma oncocalyx and Aspidosperma pyrifolium were the most susceptible to biotic and/or abiotic action deterioration over the 365 days of testing, while Mimosa tenuiflora, Mimosa ophthalmocentra and Mimosa caesalpiniifolia stood out as highly resistant, being less susceptible to deterioration. All woods were of good quality according to their natural and technological properties, and can thus be used for the production of stakes and posts.