Long-term productivity of helicopter logging in Sarawak

Management of natural forests in the tropics generally involves some type of single-tree selection system that has only a few trees removed per hectare. To reduce the impact of harvesting on the residual stands, logging operations are increasingly moving to low-impact harvesting systems that work with single-tree selection. One low-impact harvesting system is the use of helicopters. However, helicopters are significantly more expensive than ground-based systems, and understanding the factors that influence productivity is critical to profitability of operations. This paper provides an analysis of logging productivity in the tropics using data from four different timber licenses operated by WTK in Sarawak over an 18-year period and using Sikorsky 61F, 64E, and 64F and Kamov KA-32 helicopters. The results show that productivity, measured as average volume produced per hour, is a function of the number of turns per hour, the number of productive hours in a day, the proportion of choker turns, and the type of helicopter. The relatively even hourly production through balancing log size and use of chokers also shows the effect of proper planning in helicopter harvesting