Stem Analysis of a Pollarded Wild Sugi (Cryptomeria japonica) Tree

Abstract

This study proposes a way to apply stem analysis to pollarded trees and to show the relationship between the growth of a pollarded tree and topping the main trunk. As an example, we examined a pollarded wild sugi (Cryptomeria japonica) tree. The study tree was in a sugi plantation with scattered wild sugi trees in Tsunagi hamlet, Aga Town, Niigata Prefecture, Japan. The main trunk was thought to have been broken by heavy snow. The part of a coppiced tree that differs most from a single-stemmed tree is the area that connects the remaining trunk and the pollard shoots. Examining disks taken by slicing through part of the tree allows the budding location and timing of the formation of the shoots to be determined from the distribution of annual rings. This study showed that losing the upper part of the trunk had a great effect on the secondary growth of the remaining trunk, suggesting that topping a main trunk also affects the secondary growth of the remaining trunk. Competition between the shoots was found, suggesting that in order to obtain large, high quality logs from the remaining trunks, shoots that are likely to die are pruned before they put on much growth.