Abstract
We evaluated a combination of mechanized operations with a high-density road network and forestry machines in order to develop a new thinning operation system that keeps costs low and reduces damage to lower-story trees in thinning from above in multi-story forest management. We constructed temporary spur roads of 342.3 m/ha in a 1.58-ha multi-storied forest composed of 100-year-old upper-story trees and 40-year-old lower-story trees, and then implemented yarding with a grapple loader or swing yarder, and hauling with a forwarder. According to time studies, drawing with wire in felling operations and limbing in log-making operations take considerable amounts of time. The labor productivity was 5.97 m3/man-day, and is more than twice the national average in single storied Hinoki forests. Logging cost was held down to 7,516 yen/m3 through the use of rented forestry machinery. The damage to lower-story trees amounted to 16%, and was higher for thinner trees.
