PLEISTOCENE ENVIRONMENTAL MEGAEVOLUTION AS INDICATED BY THE SPOROPOLLEN FLORAS IN CHINA

By an analysis of the sporopllen time sequences from samples of 38 sections, a discussion of the vegetational and environmental megaevolution in China during the time of 1 6MaBP~0.8MaBP was made,with the result that we have 2 zones of the sporopollen assemblages and 2 palynoclimate events. It is pointed out that it was the period of the worst environment in the pleistocene,during which vegetation was very sparse,with dominantly forest steppe and steppe in northern China,desert or desert steppe in northwestern China and forest and shrub steppe in southern China. It has been shown that the climate was then cold and dry,with a of 15~17℃ temperature drop and decrease En precipitation of 300~500mm. As a result no reappearance of subtropical plant has since occurrred in North China and further north,but an initial form of the present vegetation cover. There after there was a more frequent and larger flora fluctuation. The change of spruce pollen in Qaidam Basin shows that the Qinghai Tibetan Plateau had then been uplifted to a height that could cause a transformation of the vegetation.