RESISTENCIA NATURAL DE LA MADERA DE CINCO ESPECIES DE ENCINOS DEL ESTADO DE PUEBLA

Abstract

Natural decay resistance in the sapwood of five oak species from Puebla state, Mexico, was tested by the soil-block method, according to the ASTM D 2017-81 standard. Twenty wood blocks were obtained from wood samples cut from logs of the following oak species: Quercus affinis, Q. crassifolia, Q. glabrescens, Q. laurina and Q. mexicana. Wood blocks were exposed in soil bottles for 16 weeks to the xilofagous fungus species Porya monticola and Lentinus lepideus, which causé the brown decay of wood. Samples from the same species were also exposed to Polyporus sanguineus, which is related to the white decay of wood. Evaluation of wood decay was done after the. exposure period, and the average percent loss in the dry weight of the blocks was calculated. Results showed that the natural decay resistance of the tested oak species was different. Q. glabrescens was classified as highly resistant, whereas Q. affinis, Q. crassifolia and Q. mexicana, were classified as resistant. In contrast, Q. laurina was found as non-resistant to wood decay. The high durability of Q. glabrescens may be related to the combination of wood tannins, the content of cell wall polymers, as well as the presence of tyloses in the vessel elements. Fungal attack, as showed by the percent weight loss values, was greater for P. sanguineus and lower for P. monticola.