Wood composition analysis of Caesalpinia echinata Lam. (Brazilwood): subsidies to understanding its structure and xilophagous organisms

Author(s)

Claudia Alves da Silva

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2007-02-26

Examining board members

Marcia Regina Brochetto Braga; Andre Luiz Ferraz; Angelo Luiz Cortelazzo; Marilia de Moraes Castro; Dacio Roberto Matheus

• Advisor: Marcia Regina Brochetto Braga

Abstract

In the present work, the wood of Caesalpinia echinata Lam. (Brazilwood) from the Biological Preserve and Experimental Station of Moji-Guaçu (SP) was analyzed in respect to the content and composition of extractives, lignin, cell wall polysaccharides and resistance to xylophagous organisms, and compared with woods of Anadenathera macrocarpa (Benth.) Brenae (angico-preto), Eucalyptus grandis Hill ex Maiden (eucalipto) and Pinus elliottii (Warm.) Engelm (pinus). The extraction of wood extractives using ethanol showed that heartwood of C. echinata presents high content of extractives when compared to the other woods. Extractives from the sapwood of C. echinata and heartwoods of E. Grandis and A. macrocarpa presented the highest contents of cyclitols, with the predominance of pinitol in C. echinata and A. macrocarpa. Decay assays revealed that the heartwood of C. echinata was less attacked by termites, leading to the highest insect mortality, possibly due the toxic activity of its extractives. In the fungal assays, the heartwood of C. echinata presented weight loss values lower than 3%, confirming its high natural durability; weight loss was similar that of A. macrocarpa, which is well known for presenting high resistance to fungal attack. The degradation profile indicated the preferential decrease of xylose in angiosperm woods and mannose in P. elliottii. No differences in the lignin content were observed in the sapwood and heartwood of C. echinata, and the heartwood of E. grandis. After Maüle reaction, similar lignin staining was observed in C. Echinata and A. macrocarpa, with predominance of syringil-type lignin in the fiber walls and guayacil-type lignin in the secondary wall of the vessel elements. Cell wall analysis showed that the wood of C. echinata differs from other woods in pectin composition and hemiceluloses content, although the composition of the latter fraction was similar to that of E. gradis and A. macrocarpa. In conclusion, the results showed that the wood of C. echinata, analyzed under different aspects and compared with commercial woods, has similarities with the wood of high resistance, and may be considered of high natural durability. However, its resistance can not be attributed to one single feature, but certainly it is a consequence of the interaction of several wood components. Considering that brazilwood was included in the IBAMA list of plant species in risk of extinction, the use of its wood for multiple purposes has to be carefully evaluated. (AU)