北海道根釧台地東縁部から得られた最終氷期の花粉化石群

概要

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The tephra and peat beds distributed at Tokotan and Honbekkai in the eastern margin of the Konsen Plateau, Eastern Hokkaido, were investigated by tephra stratigraphy, pollen analysis, and 14C datings. The peat layers of Tokotan Loc. 1 were estimated to date from the late stage of the Last Glacial Age. Four pollen zones were discriminated there. The lowest zone, TK-I, about 36, 000y. B. P., is characterized by high pollen percentages of Picea coexisting with Larix and Abies. Zone TK-II is characterized by high Larix, Betula, Alnus, and herbs. Zone TK-III, a little older than 32, 000y. B. P. in age, is dominated by Picea. The uppermost zone, TK-IV, is estimated at about 32, 000y. B. P. based on the existence of Nl-a and Spfa-l, and it has high percentages of Larix, Picea and herbs. During the formation of these 4 zones, there could be subarctic forests (zones TK-I and TK-III) and subarctic open forests (zones TK-II and TK-IV) dominated by larch and/or spruce on bogs. Generally, the climatic conditions of zones TK-I-IV was colder and drier than at present, especially in zone TK-II, and less so in zone TK-III.