Propriedades físico-mecânicas do lenho deteriorado por fungos apodrecedores de árvores de Tipuana tipu

Abstract

The tipuana was widely used in urban arborization. In general, inadequate management exposes the wood to the action of wood decaying fungi and insects, often associated with the fall of the trees. The aim of this study was to evaluate the physical and mechanical properties of sound and rotten tipuana wood from São Paulo City´s afforestation. Thirteen old trees with symptoms of wood deterioration were removed. From the basal region of the trunk were cut 1 m-length stem segments, to characterize the physical and mechanical properties of sound and decayed wood. The results indicated that through the radial wood density profile by X-ray densitometry were classified seven pattern of wood biodeterioration, named (EXS) with accumulation of extractives and sound, (ZR) with the reaction zone and sound, (NS) normal and sound, (PBINC; PBINT) incipient and intense white rot (PMINC; PMINT) incipient and intense soft rot, with apparent densities of 0.94, 0.92, 0.82, 0.66, 0.41, 0.67 and 0.44 g.cm-3, respectively. The mechanical tests showed that wood classified as (ZR) (EXS) presented the highest values of strength and stiffness of 84 and 80 MPa and 6461 MPa and 5826, respectively; the (NS) showed values of 62 and 4642 MPa, and the (PBINC) (PMINT) the significant and lowest values of strength and stiffness, enhancing (PBINT) with values of 5 and 571 MPa. The reduction of density, strength and stiffness of wood is related to the biodeterioration of wood cell walls of trees tipuana by decaying fungi.