NONDESTRUCTIVE EVALUATION OF HARDNESS IN TROPICAL WOOD

Various nondestructive techniques have been developed to evaluate wood quality. However, these studies were conducted mainly for temperate species. The Central Amazonian forests have more than 300 tree species per ha (> 10 cm diameter at breast height) and few studies using nondestructive techniques were conducted on these species. This study aimed to test a nondestructive technique, with application of stress waves, for the evaluation of hardness of timber species in the Central Amazon The study was conducted in Itacoatiara city, Brazil (43 degrees 2'-3 degrees 04' S and 58 degrees 31'-58 degrees 57' W). Three timber species, namely, Nectandra cuspidata, Mezilaurus itauba and Ocotea guianensis were evaluated for hardness using nondestructive and destructive methods. Models adjusted for valuation of properties based on the speed of propagation of stress waves (r(2)= 0.54-0.59) and wood density (r(2) = 0.73-0.78) allowed the prediction of hardness of the wood species. Thus, the tested nondestructive techniques showed sufficient performances to predict timber hardness and would improve efficiency of the process to evaluate timber quality.