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Abstract

Islands in the Last Glacial Time Tadao KAMEI and RESEARCH GROUP for the BIOGEOGRAPHY from WURM GLACIAL This article deals with introducing some problems being debated by the members of the Research Group, relating to the fauna and flora of the Japanese Islands in the Last Glacial time. Though nowhere in Japan the precise chronostratigraphy of this age has been established yet, a tentative clasification based on litho-and biostratigraphy in central Japan by J. SAKAI and others is proposed with tephrochronology and radiometric dating. According to them, the Early stage began with the regression and advent of cold phase of ca. 65,000 yr.B.P., and further with the Middle stage chracterized by climatic ossilation, some peculiar warm phases were corporated. In the Late stage between 25,000yr.B.P. and 10,000yr.B.P. was intercalated the maximal cold phase of ca. 20,000yr. B.P.. Concerning the reconstruction of paleoenvironment, I. HIURA made biogeographical and ecological consideration by paying his attention to the species and subspecies distribution of non-dispersal plants and insects like as tribe ASAREAE and tribe CARABINI respectively. On the other hand, the vegetation of the Japanese Islands and its adjacent areas was investigated from the recent and Last Glacial plant geography by M.HOTTA and T. NASU respectively. They suggest significance of the distribution of plant communities to the seasonal structure of precipitation rather than to the temperature control. Summing up those results collectively, the environmental and vegetational studies on the Last Glacial seem to indicate the presence of more arid and extensive steppe-like environment which is absent in the present Japanese Islands. It is characteristic that some of the arctic mammals migrated into Honshu through northern land connection during the Last Glacial. Therefore, the mammalian fauna in that time was composed of arctic immigrants and temperate endemics, that is the mixed fauna. In this sence, that mixed fauna may resemble to the present of mammals in the Maritime Province (Siberia) and Manchuria of the continent. The immigration of those arctic mammals might be undertaken before the maximal phase of ca. 20,000yr.B.P. In connection with this, the sea level change of those days was discussed by M. HOSHINO and that the southern land connection did not happen at that time.