On the origin and development of steppe vegetation in China

An evaluation on the origin and evolution process of Chinese steppe vegetation is carried out based on the pollen data documented from the Tertiary of China. Original steppe of China dates back to the later stage of Paleogene in Northwest China, where pollen floras exhibit an arid tendency even in the earlier stage of Paleogene. The first occurrence of steppe also coincided with some major environmental changes around the Eocene/Oligocene boundary, such as the herald of Himalayan movement, the retreat of Tethys from the west part of the Chinese Continent, etc., while the development of the steppe was extensively confined by the afterward orogeny and climate fluctuations. Case studies from seven key areas are put forward to show some detailed changing procedure of the steppe vegetation in China.