Last 12,000 years vegetation history in and around the Furano Basin, central Hokkaido, Japan

富良野盆地東部の東鳥沼と山地の東大演習林上湿原について，年代測定と花粉分析学的研究を行なった。盆地における森林の主構成種は，Abies，Picea，Betula，Juglans（9～8 ky BP）～Quercus，Abies（8～5 ky BP）～Quercus，Alnus（5～4 ky BP）～Quercus，Abies，Picea（4 ky BP～現在）と変遷した。Quercusは温暖気候のもと8～4 ky BPで最も優勢であった。4 ky BPにAbies，Piceaが増加して現在に至る汎針広混交林が成立した。湿原は～9 ky BPから成立した。山地では，Picea，Larix，Pinus，Abiesからなる亜寒帯針葉樹林と草原が発達した（12～11ky BP）。11ky BP に湿原が誕生し，Picea，Betula，Abies が主構成種となったが，Larix は8 ky BPまで生き残った。8～4 ky BP は盆地と同じく，Quercusが優占し，Juglansは低地より遅れて山地に進出した。4～2 ky BP はPiceaとAbiesが増加するとともに，Quercusが激減し，2 ky BPにPiceaは現在規模に達した。Peat sediments obtained from Higashi Torinuma and upper moor areas in Todai Enshurin in and around the eastern Furano Basin, central Hokkaido were analyzed for pollen and carbon-14 datings. In the basin areas, the main forest components changed from Abies, Picea, Betula and Juglans (9 ～ 8 ky BP- thousand years before the present) to Quercus and Abies (8 ～ 5 ky BP) and then to Quercus and Alnus (5 ～ 4 ky BP) and finally to Quercus, Abies and Picea (4 ky BP ～ present). Quercus became dominant under the warm climate during the period from 8 to 4 ky BP. At 4 ky BP Abies and Picea increased in extent, and the present Pan-mixed forest was formed. Areas of moor have developed in the basin at least over the past 9,000 years. In the highland moor, subarctic forest composed of Picea, Larix, Pinus and Abies, and grassland developed on landslide sites between 12 and 11 ky BP. Moor occurred at 11 ky BP and the main forest components changed to Picea, Betula and Abies. Larix survived until 8 ky BP. Between 8 and 4 ky BP Quercus was the dominant tree at the same as it dominating the basin areas, though Juglans migrated to the highlands later than its maximum period in the basin. The increase in the area of Picea, Abies and the sudden demise of Quercus happened at 4 ky BP. Development of Picea reached to the present scale at 2 ky BP