Abstract
We reported the condition after 20 years installing treeshelters on Chamaecyparis obtusa seedlings in Tsushima Island. Of the 198 seedlings that installed treeshelters in 1999, 150 (75.8%) were alive in late 2018. Since 24 seedlings had fallen due to the movement of surface soils, which is considered as accident during the initial period, the survival rate of the seedlings was 82.2% when the denominator was 174 seedlings after deducting this. Regarding the durability of the treeshelter, 37 of the surviving individuals were dropped, 53 were break, and 53 remained in a normal state. However, since the most of the 53 C. obtusa with the normal state treeshelter did not reach the diameter of treeshelter, they would likely to fall off when the seedlings grow. The treeshelter used in this study is unlikely to occur problems such as deformation of planted trees and early break of treeshelter even if it is left until thinning.
