Sunny Crown Diameter as a Tree Selection Indicator for Thinning at a Mature Sugi Artificial Forest

Abstract

plantations that have been managed for over years have increased in number throughout Japan. However, there are no criteria or indicators for tree selection before thinning. Here, we attempted to expand the understanding of sunny crown management in Yoshino Forestry by analyzing a mature artificial Sugi stand at Sanbe Educational and Research Forest, Shimane University. We examined the correlation of sunny crown diameter and annual diameter at breast height DBH growth, and the accuracy of annual ring growth estimates. We found a correlation between sunny crown diameter and annual DBH growth; with accuracy, were able to estimate whether the annual ring width was mm using sunny crown diameter ranges. Therefore, although sunny crown and DBH size is associated with different numbers of thinning times, it is a useful indicator of tree selection for thinning in the Sanbe mature forest, and may also be a useful indicator in thick, mature Sugi plantation forests in Japan.