On the Tree Line Composed of Beech (Fagus crenata) on Funakata Mountains, Miyagi Prefecture

Abstract

A boreal coniferous forest belt is underlain by a cool temperate summer green broad leaved forets belt in japanese mountains as usual. The latter, composed mainly of beech (Fagus crenate), however, has no overlying belt with arboric forest belt but has one with scrubs, herbaceous vegetations, Sasa communities and other treeless vegetations on mountains rising along the coast of the Sea of Japan. It is said that this results from heavy snow of the region. Such treeless vegetations are found also on summit areas of some mountains of backbone range in northeast Japan.In the above cases a tree line or an upper limit of arbors lies within an altitudinal range in which beech can survive. Across this line the growthform of beech shifts from arbor to sub-tree or shrub. Such an upper limit was studied in Funakata Mts. (Figs. 1 and 2) rising in a midst of the backbone range of noutheast Japan.The upper limit in this area runs higher in gullies and ravines than on spurs and ridges in elevation (Fig. 3 and Table 1). There is not so much differrence in the elevation of the limit between the east facing slope and the west facing. These tendencies are opposite to that observed on the mountains of the Sea of Japan side.This suggests that the zone of treeless vegetation of this area is not under the same condition as on the mountains of the Sea of Japan side. It is more probable that the treeless vegetations of Funakata Mts. result not from the heavy snow but from the strong wind. Heavily deformed Pinus parviflora var, pentaphylla scattered on the treeless vegetation belt of these mouttains supports this estimation, too.