島根大学三瓶演習林におけるブナとイヌブナの分布について

Japanese beech, Fagus crenata, is one of major constituents of climax cold temperate forest in Japan. Beech forests grown in Shimane Prefecture are westernmost points of their distribution in Honshu Island. Trees of F. crenata normally appear in forests at higher elevation（800m A.S.L. or higher）, having lower warmth index, in Shimane Prefecture. In Sambe region of Shimane Prefecture, we can observe Japanese beech trees just below the summit of Mt. O-Sambe-San（1126m A.S.L.）. At lower elevation, we see another beech species, F. japonica. Nevertheless, it is recognized that several trees both of F. crenata and F. japonica grow in Sambe Forest, which is located at 300-624m A.S.L. In order to determine the spatial distribution of two beech species at Sambe Forest, we mapped the positions of the two species and described sympatric tree species of theirs. As results, we recorded both of beech species at Sambe Forest. Their distribution was isolated in a small scale, i.e., trees of F. crenata were found at an elevation of 475 to 610m A.S.L. in southern part of the forest, and those of F. japonica at an elevation of 390 to 480m A.S.L. in northern part. Trees of F. crenata accompanied some F. crenata trees, whereas some plots of F. japonica had only one F. japonica tree. Most abundant accompanied tree species were Quercus serrata and Carpinus laxifolia for F. crenata, and Acer crataegifolium and Ilex pedunclosa for F. japonica. Both beech trees grew with tree species which preferred drier site.