Wind-Shaped Trees in the Subalpine Zone in Japan

The wind-shaped trees in the subalpine zone and the lower part of the alpine zone were classified into two types. First, deformations of the respective types were described and figures and photographs included. Second, their distributions were studied in Central Japan. Concerning the distribution, it was pointed out that the history of vegetation development, the microtopographical situation, and the exposure to the prevailing wind are the important factors. The wind-shaped needle trees deformed by the winds in winter appear mainly on the Japan Sea side and those deformed by the winds during the growing season are distributed on the Pacific side of the mountains. In Tôhoku District it can be concluded that the wind-shaped trees of both types develop similarly and their distribution range is mixed. The development of wind-shaped coniferous trees is poor on volcanoes because of the volcanic activity.The upper limit of the subalpine zone corresponds well with the conditions of wind speed. The west components of wind of free atmosphere at the level of the limit are 8 to 10 m sec-1 as a winter mean in Tôhoku District and Hokkaido. Finally, the results of observation on the state of “silver thaw” on Mt. Azuma, Central Japan, produced just after the strong winter monsoon conditions were described.