Snow Cover on Planted Land at the Heavy-snow Area

Abstract

The purpose of this investigation is to make clear the states of snow cover in the heavy-snow area of which Cryptomeria japonica-trees are damaged by snow pressure very often. Gomisawa Plantation, young stands of C. japonica is in the heavy- snow area of Niigata Prefecture. On the various topographic places of this plantation, maximum snow cover depth, snow pressures and the vertical section of snow cover were investigation in the snow seasons of the years 1965-1969. The results are as follows : 1) The course of snow cover depth during each winter at Gomisawa has a strong resemblance to that of Tokamachi Site.2) It seems that the heavy-snow year over 500 cm in maximum depth on the flat stand occurred five times within last twenty years.3) It is estimated that the duration of continuous snow cover range 160-190 days on the flat stand.4) The maximum snow cover depths are considerably changed with topography, wind direction and climatic condition in each winter. They range from 310 to 750 cm or more in the heavy-snow year, and from 290 to 470 cm in the year of small depth. In addition, always they are shallow on the windward slopes, and are deep on the leeward slopes. Therefore, the snow pressures on inclined stands show remarkably large values onthe leeward slopes. The settling pressures of snow on flat stands range from 2.4 to 3.0 times as great as those of Tokamachi Site.The states of snow cover mentioned above are closely related with the damage of the forests.