The earliest compiled local flora for the tropical areas of China was made for Hainan Island, but there is a need for a panoramic work to fully understand the biodiversity of the tropical flora of China, especially for conservation efforts.
Prof. ZHU Hua of Xishuangbanna Tropical Botanical Garden (XTBG) checked and synonymized native seed plants from tropical areas(southeastern Xizang (Tibet), southwestern to southeastern Yunnan, southwestern Guangxi, southern Guangdon, southern Taiwan, and Hainan) in China.
Based on present floristic records and data from these tropical areas of China, 12,844 species of seed plants included in 2,181 genera and 227 families are recognized. The families are mainly distributed in tropical areas and extend into temperate zones and contribute to the majority of the flora of southern China.
In geographical elements, the genera with tropical Asian distributions comprise the highest proportion among the various distribution types, supporting a tropical Asian or Indo-Malaysia affinity of the tropical flora of China. Additionally, the tropical flora of China shows conspicuous variations in floristic composition and geographical elements from region to region due to different geological history and ecological environments.
Prof. ZHU Hua found that there are more similar dominant families and genera, and also higher similarities at these levels between southeastern Xizang (Tibet) and southeastern Yunnan. The floras of southern and southeastern Yunnan have higher portions of the tropical Asian elements compared with other tropical floras in China, although they have the highest similarity at the specific level.
The dominant families and genera have noticeable differences between them; specifically, the flora of Hainan has the highest ratio of tropical elements, of which the pantropic element has the highest portion.
Evidently, the differences in characteristics and evolution of these regional tropical floras could very well be influenced by geohistorical events associated with the uplift of the Himalayas.