Simulation study of a single-grip harvester in thinning from below and thinning from above

The time consumption and productivity of a single-grip harvester were studi ed, using a simulation model, when thinning from below and above in eight r andomly selected stands. The model estimated the time required for each wor k element, given machine and tree positions, and tree size. A 2 x 5 factori al design was used with factors thinning type [from below (T-b) and above ( T-a)] and tree size. Trees were subjectively selected for harvest according to thinning type. Total basal area removal was 30% plot(-1). Approximately 50% more trees were harvested in T-b than in T-a. Time consumption tree(-1 ) was higher for T-a than T-b. Time consumption for machine and boom moveme nts decreased with increasing number of harvested trees, and time for felli ng and processing of trees increased with harvested mean stem volume. Harve ster productivity was 36% higher for T-a, since the increase in harvested m ean stem volume was higher than the increase in time consumption tree(-1).