出雲平野－宍道湖地域における完新世の花粉化石群集変遷 : 宍道湖と神西湖の例

その他

The vegetation and climate history since the early Holocene in the eastern Shimane Prefecture were clarifi ed by pollen analysis performed on the two sediment cores drilled from Lake Shinji and Lake Jinzai. About 9500 cal.yrBP, the cool-temperate deciduous broad-leaved forest of Fagus and Quercus subgen. Lepidobalanus were dominated around Lake Shinji, the warm-temperate evergreen broad-leaved forests of Quercus subgen. Cyclobalanopsis and Castanopsis-Pasania were mixed with the cool-temperate forest around Lake Jinzai. Until about 7000 cal.yrBP, the warm-temperate forest predominated around this region because of warming. Until about 4300 cal.yrBP at Lake Shinji and about 3200 cal.yrBP at Lake Jinzai, the coastal forest of Pinus thunbergii grew on the sands appeared by regression, but the succession of warm-temperate forest progressed in spite of cooling. Then, Cryptomeria and Fagus were increased by the cooling. Until AD1635, secondary forests of Pinus densifolia were expanded by artifi cial effects.