Technical and economic performance of a feller buncher in eucalyptus forests with different yields in Southern Bahia, Brazil

The objective of this study was to assess the performance of a feller buncher as a function of forest yields. The feller buncher productivity and production costs were evaluated in a eucalyptus forest with different mean tree volume (MTV) classes. The technical analysis included time and motion study, productivity, mechanical availability, and operational efficiency. The economic analysis was based on fixed and variable costs, which resulted in the feller buncher's total operating cost. Production costs were calculated by the ratio of operating costs to wood volume harvested per working hour, which varied according to the forest yield levels (low, medium, and high) determined based on MTV classes. The results showed a total operating cost of US$157.76 h-1 for the feller buncher, 83.52% attributed to variable costs. The highest operational performance and, consequently, lower production cost were found for the highest MTV, with a tendency for productivity stabilization as the forest yield increases. The time and motion study of the feller buncher operating cycle for the three forest yield levels showed a statistically significant difference by Tukey’s test (5% significance). A significant difference was found in the tree felling and bunching phase among the three forest yield levels, as the feller buncher operating time in low-yield forests was 46.59% greater than that in high-yield forests.