Propriedades físico-mecânicas da madeira de um povoamento de Pinus taeda L. atacado pelo macaco-prego

Abstract

Planted forests in Brazil take the lead in world productivity, with a production average of 40 m³ ha-1 yr-1, representing a great wealth for the country's industrial sector supplying a variety of products and by-products such as charcoal, paper, cellulose, wood-panels and laminate flooring. Pinus taeda L. composes this scenario of planted forests, the most cultivated species in southern Brazil, but today the plantations of the species are suffering attack by black capuchin monkeys. These primates remove the bark on the tree upper third to feed on the sap. In view of this fact, the objective of the study was to evaluate the physical and mechanical properties of Pinus taeda attacked by black capuchin monkey. The material used in the research was collected from trees at the 19 years old. 15 trees attacked by monkeys and 15 free from attack trees were harvested, and removed the first two logs with 1.20 m each. The logs were sawn in plank of eight centimeters thick, which remained outdoors for four months to dry the material. After this period, specimens were made for the static bending tests, parallel compression and shear. We evaluated the properties of wood attacked by capuchin monkeys and not attacked wood, on three classes of DBH tree (20.00 to 27.99 cm, 28.00 to 35.99 cm and 36.00 to 43.99 cm). The specimens were used to determine the apparent density, latewood percentage, average length of growth rings, strength and stiffness in static bending and in parallel compression, and shear strength. The results showed that for the static bending and shear strength test there was no difference between the attacked and the non-attacked wood, but for the parallel compression test, a difference occurred resulting in higher strength and rigidity for the wood in the attacked condition. The latewood percentage was higher for the wood attacked in the specimens of the three mechanical tests. Also, a significant correlation was observed between the characteristics of the growth rings measured (latewood percentage and average length of growth rings), with the physical-mechanical performance of the specimens.