2021 Volume 103 Issue 1 Pages 48-52
This study examined the effects of weeding schedules on shrub quantity and operation time for improvement cutting in 13 year old sugi (Cryptomeria japonica) stands. We also assessed the total operation time, which included both weeding and improvement cutting, with different weeding schedules. Then, we confirmed the state of competition between planted sugi trees and shrubs. As a result, shrub density was affected by weeding frequency, and shrub basal area and mean height were affected a year after the previous weeding. The shortest operation time was annual weeding, which was implemented annually from the 1st to 6th year after planting (11.9-12.6 h/ha). Three-time weeding was implemented in the 1st, 2nd, and 3rd years after planting and required about twice as much time as annual weeding (24.5-32.3 h/ha). The total operation time was longest with annual weeding (155.1-181.3 h/ha). Most of the sugi trees in this study site were not in competition with shrubs. We concluded that the operation time of improvement cutting increased with decreasing weeding frequency. However, the total operation time decreased with reducing weeding frequency. Additionally, improvement cutting may be omitted because of competition, and it is more effective for reducing initial silviculture costs.
