Influences of different pruning methods to growth of a zelkova tree（Zelkova serrata (Thunb.) Makino）

Abstract

This research was aimed at analyzing growth characteristics of zelkova trees（Zelkova serrata (Thunb.) Makino）pruned with 2 kinds of methods, "Kiritsume" and "Sukashi". "Kiritsume" is a pruning method to cut branches short. "Sukashi" is a pruning method to cut back branches at a diverging point, a traditional Japanese pruning technique. 15 trees approximately 350cm in height was used in this study to measure their growth for one year. 5 trees were pruned with "Kiritsume" and other 5 trees were pruned with "Sukashi", and the others were not pruned as control plots. The results showed that trees pruned with "Kiritsume" had a tendency to extend many branches from trunk. This result suggested that "Kiritsume" was a method to disturb tree form and to cause a crowd of branches and leaves inside a tree crown. The results also showed that pruning with "Kiritsume" weakened tree roots. Because trees pruned with “Kiritsume" was smaller in dry weight of current roots than control trees. These results suggested that "Sukashi” was a pruning technique not to disturb tree form and weaken tree roots, but to keep tree size and control tree vigor.