Plio–Quaternary stepwise drying of Asia: Evidence from a 3-Ma pollen record from the Chinese Loess Plateau

A 3-Ma pollen record was obtained from a continuous red clay–loess–paleosol sequence at Chaona in the central Chinese Loess Plateau (CLP). The record shows a permanent change of a domination of typical Cupressaceae forest vegetation representative of an ecological environment with a relative warm and humid climate during 3.0–2.6 Ma to largely steppe vegetation under dry climate conditions after 2.6 Ma. The later is further manifested itself as steppe to forest or forest–steppe (spruce forest — mostly mesophilous herbs) between 2.6 Ma and 1.5 Ma, forest–steppe (pine–grass) between 1.5 Ma and 0.95 Ma, open forest–steppe (mesophilous and xeromorphic herbs–pine) between 0.95 Ma and 0.5 Ma, and steppe (xeromorphic herbs) after 0.5 Ma, suggesting a process of stepwise aridification in Central Asia at the late Pliocene and the Quaternary.