2007 Volume 24 Issue 2 Pages 153-170
Ecogeography of Japanese beech (Fagus japonica Maxim.) near the northern distributional limit, in Miyagi and Iwate prefectures on the Pacific side of eastern Japan, was studied on the basis of a distributional database comprising 112 literature records, 105 observation records, 14 specimen records and 47 other records from the Unified Information Database on Natural Environment of Iwate Prefecture. It was clarified that Japanese beech showed geographically a patchy distribution with intermittent distributional gaps in the area. In terms of climatic factors, its distribution is limited to the area where the Warmth Index (WI) is between 60℃・month and 95℃・month, and where the maximum snow depth in winter is less than 120cm. The upper limit of altitudinal distribution is ca. 200m higher in Kitakami Mts. than Ohwu Mts., because of the less snowy conditions of the former. In terms of geological and topographical factors, the distribution of Japanese beech is mostly limited to the area where the bedrocks are relatively hard, sedimentary or igneous rocks, and where steep slope prevails. Historical factors that might affect the present distribution of Japanese beech, such as locations of refugium in the Last Glacial Period and human disturbance histories, were also discussed.
