A anatomia influencia na resistência mecânica da madeira de quatro espécies de um sistema agroflorestal

Abstract

Mechanical strength is an important property for the use of wood and anatomical variables influence this characteristic. Thus, the present study aimed to evaluate the influence of anatomy on the mechanical resistance of Parapiptadenia rigida (Benth.) Brenan, Peltophorum dubium (Spreng.) Taub., Eucalyptus grandis x Eucalyptus urophylla and Schizolobium parahyba (Vell.) Blake from an agroforestry system. Three trees of each species were sampled, aged 9 years. The specimens for the evaluation of the anatomical properties were removed from the diameter region at chest height (DBH at 1.30 m from the ground), with dimensions of 1.5 x 1.5 x 2.0 cm, followed by the IAWA technical standard (1989). The mechanical properties were determined according to the technical standard ASTM D143-94 (ASTM, 2000). The specimens came from central planks removed from the base to the individuals' DBH and made with the dimensions of 5 x 5 x 15 cm for the longitudinal hardness test, transversal hardness and perpendicular compression, while for the static flexion the specimens had dimensions of 2.5 x 2.5 x 41.0 cm. The anatomical variables influence the mechanical properties of the wood of the studied species. The higher the fraction values of the fiber wall, the frequency of the vessels and the frequency of the rays, the higher the mechanical properties. On the other hand, the increase in the dimensions of the diameter of the fibers, the diameter of the flame of the fibers, the diameter of the vessels, the height and width of the spokes, smaller are the values of the mechanical properties of the wood.