VEGETATION CHANGE DURING THE EARLY LAST GLACIAL IN HABORO AND TOMAMAE, NORTHWESTERN HOKKAIDO, JAPAN

Early last Glacial sediments are exposed at several points on the clif fs of marine terraces in the Haboro and Tomamae area. The sediments ca n be correlated by their facies and three widespread tephra layers, Kc -Hb, Toya and Aso-4. Six stages of vegetation change can be recognized from the pollen spectra of three sites: (1) Picea forest spread aroun d the time of the Kc-Hb ash fall; (2) Larix forest spread between the K-Hb and Toya ash falls; (3) towards the Toya fall Lysichiton and Alnu s increased abruptly and after that Betula became dominant around the Toya; (4) between the Toya and Aso-4, temperate deciduous broad-leaved trees such as Quercus, Ulmus, Fraximus grew with Picea and Betula; (5 ) Larix forest spread again around the time of the Aso-4 fall; (6) fin ally, Betula forest spread again, accompanied by temperate deciduous b road-leaved trees such as Ulmus, Quercus, Fraxinus. The Picea-dominant stage and following Larix-rich stage might correspond to oxgen isotop e substage 5d while the subsequent Larix-rich stage around Aso-4 might represent substage 5d.