ESTIMATING AND VALIDATING HARVESTING SYSTEM PRODUCTION THROUGH COMPUTER-SIMULATION

A Ground Based Harvesting System Simulation model (GB-SIM) has been developed to estimate stump-to-truck production rates and multiproduct yields for conventional ground-based timber harvesting systems in Appalachian hardwood stands. Simulation results reflect inputs that define harvest site and timber stand attributes, wood utilization options, and key attributes of the harvesting operation. Statistical validation of GB-SIM was conducted with harvesting production data collected from 16 harvest units and 2 logging operations, including partial cuts and clear-cuts in Appalachian hardwood stands. The mean error in estimated production rates was 14.1 ft. 3/hour, or 2.6 percent of the observed rates. For 10 of the 16 units, this error was less than 10 percent of the observed production rate. Nonparametric tests conducted with five replications of each simulated harvest did not find a statistically significant difference between the distributions of actual and simulated production rates. These validation results indicate that GB-SIM can be used to estimate harvesting system production rates and product yields; information required to conduct economic analysis of wood utilization and forest management alternatives. Simulation results are also presented that contrast two different logging crews and compare production rates from eight unique wood utilization options.