Format: ORAL

Tao Su1,2, Zhe-Kun Zhou2, Jia Liu1, Xin-Wen Zhang1, Jiang Huang2, Shu-Feng Li2

1 State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation & Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China 2 CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China

The modernization of plant diversity, which means the floristic assemblage in deep time being similar to nowadays, is a milestone for the evolution of global plant diversity; however, little is known about when did this process occur. Recent paleobotanical investigation on the Qinghai-Tibetan Plateau (QTP) sheds new lights on this topic. The late Paleocene Liuqu flora (~59 Ma) from southern QTP mainly consists of Annonaceae, Fabaceae, Moraceae and Palmae, suggesting a tropical forest. The middle Eocene Jianglang flora (~47 Ma) from central QTP is composed of Apocynaceae, Araceae, Menispermaceae, Sapindaceae and Simaroubaceae, there is no dominant species in this subtropic flora. The Dayu flora (~39 Ma) from central QTP consists of both woody plants and herbs, indicating the vegetation of open woodland. The floristic components of all these floras mentioned above are quite different from modern vegetations. It is not until the latest Eocene that the floristic components are similar to nowadays, which is evidenced by the Markam flora from eastern QTP with Fagaceae and Betulaceae as the most abundant taxa. This kind of evergreen deciduous broad-leaved mixed forest still survives in southeastern margin of the QTP nowadays. During the latest Eocene, the growth of the QTP and the associated climate change from dry to wet condition may contribute to the modernization of plant diversity on the QTP and regions nearby, and gradually shaped the rich plant diversity in this large area.