Abstract
Sugi (Cryptomeria japonica D. Don) forest plantations were damaged by snow that accreted on the tree crown in the eastern part of Shimane Prefecture, which is at 200 -400 m altitude, on January 9-10, 2009. This study investigated the status of the damaged forests and the sizes of the damaged trees. The damage occurred in forests of suitable tree density, too. Despite having same tree density, resistance to damage is controlled by land form or management histories. The least damaged trees exceeded breast height diameter of 32 cm and had a height-diameter ratio of less than 65. It is, therefore, necessary to grow planted trees to the above sizes as soon as possible to minimize the risk of snow damage. Trunks were observed to break either at the tree crown or at the top of the trunk. Because the damages in these parts of the tree do not have a serious effect on growth, the growth increments of trees were expected to be reduced only minimally. However, trees where the trunk split in the middle, with an average split length of 3.5 m, were likely to die and could not be used as construction material. In conclusion, the trees sustain damages that are more serious by trunk splitting than by breaking.
