[Article] Reexamination of Age and Flora of the Egota Conifer Bed, Tokyo, Based on Dr. Shigeru Miki Collection

Plant macrofossil assemblage from Egota conifer bed that was found in Egota, Nakano, Tokyo by Dr. Nobuo Naora was described taxonomically and authorized as an assemblage under a cold climate in the latest Pleistocene by Dr. Shigeru Miki. This was the first finding in Japan among plant fossil assemblages in last glacial cold stage and this assemblage has been authorized as a standard showing last glacial environment. The conifer bed was dated between MIS 3 and late glacial stage in the later excavations in and around Egota and occasionally correlated with the Younger Dryas stage. To clarify age and species composition of the original plant macrofossil assemblage in the Egota conifer bed defined by Miki, we reinvestigated Miki’s collection stored in the Osaka Museum of Natural History and dated them. The calibrated ages of four pinaceous conifers and one Quercus serrata samples range between 25,000 and 20,000 cal BP, indicating the later stage of the last glacial maximum. Plant macrofossil collection assigned to those from the conifer bed were composed of 22 tree and 26 herbaceous taxa and include Larix and Picea sect. Picea with the largest number of samples. Among 25 taxa described in Miki’s papers Luzula cf. plumosa fruit and seed are misidentification of Persicaria thunbergii fruit and Viola seed. Undescribed taxa are newly found in the collection. Paleovegetation reconstructed from Miki’s collection is characterized by abundance of pinaceous conifers as similar as the other assemblages in the last glacial maximum from Kanto area but also by diverse deciduous broad-leaved tree taxa.