2022 Volume 64 Issue 1 Pages 13-21
We examined the effects of understory clearing at thinning operation on the long-term development of forest floor vegetation. We investigated responses of vegetation cover, species richness, and Shannon-Wiener diversity index (H ') of forest floor vegetation to four different experimental treatments, testing thinning (treatment T), weeding (including shrub clearing) (W), their combination (TW) and control (C) in a hinoki plantation. In the treatment TW, where both thinning and weeding were conducted as ordinary thinning, vegetation cover, species richness, and H' were highest among the four treatments. The treatment W also showed significant development of forest floor vegetation during the measurement period, showing significantly higher vegetation cover and species richness than those in the treatment T at 8th year after the treatments. In contrast, the treatment T where shrubs were retained showed no significant change in vegetation cover and H' during the measurement period. In addition, vegetation cover was not different between treatments T and C throughout the measurement period. These results suggested that thinning of canopy trees without clearing of dense shrub cannot successfully promote the development of forest floor vegetation, and that understory clearing at thinning operation is effective for the purpose of long-term development and diversification of forest floor vegetation.
