The Geohistorical Succession of the Vegetation and the Climatic Change during the Würm Glacial Age in Japan (Preliminary Report)

Abstract

In the present paper, the geohistorical succession of the vegetation in Japan (chiefiy Honsyu) during the Würm Glacial Age is researched into from the plant fossil records (remains and pollen) and geochronological evidences. Moreover, some preliminary considerations on the climatic change during the above mentioned age are given based on the results of research in the geohistorical succession of the vegetation.
Some noticiable facts are as follows;
1) At the times of about 12, 500y. B.P. (in radiocarbon years), the vegetation indicating a somewhat warmer climatic condition appeared in some areas, such as Oomi in Kinki District and Niigata in Chubu District.
2) At the times of about 18, 000y. B. P. (in radiocarbon years), the typical vegetation now distributed in the subarctic or subalpine zone in Japan occupied the lowland of the northern part of Honsyu. It indicates that the coldest episode appeared at this term in Japan. This term may be referred to the Maximum Würm glacial.
3) During the term of the Würm Glacial Age older than 21, 000y. B.P. (in radiocarbon years), the vegetation was characterized by the forest, composed chiefly of the plants now distributed in the subalpine zone and intermingled with the plants now distributed in the montane zone. It indicates that the climate in this long term was affected more by the somewhat humid condition than the climatic condition in the subarctic or subalpine zone.
Especially, at the short term of about 25, 000y. B.P. (in radiocarbon years), the vegetation was composed chiefly of the plants now distributed in the temperate or montane zone in Japan. It indicates that the minor warm episodes appeared in the times of about 25, 000y. B.P. The appearance of the same episodes may be expected in the somewhat longer term of about 40, 000y. B.P. (in radiocarbon years).