Silvicultural Approach to the Forestry at the Heavy-snow Area

Abstract

The effects of deep snow upon young trees are discussed based on the survey at the south western area of Niigate Prefecture. Snow lays as deep as 45 meters at this area where cold air mass mixes with moist air mass due to topographical feature. Twenty-eight plots of planted Sugi (Cryptomeria japonica) stands ranging 440 years old are surveyed and yearly change of snow damage is estimated. Estimation of damage is based on the classification of Dr. T. Shidei.
The percentage of severely damaged trees to planted trees ranges from 8 to 44%. Mortality increases with age up to certain age and comes to plateau. Much influence on damage is caused by topogaphy, that is, flat land, especially concave plot is worst to trees and slopes ranging inclination of 1530° are better than other slopes. Sedimenting pressure of drifted snow is demonstrated to be more important than creeping pressure except avalanch to the growing trees.