Tropical regions are discontinuously distributed in South and Southwest China, spanning a range of some 2 500 km from South Taiwan to South Yunnan, and covering an area of about 80 thousand km². Owing to the influences of monsoon climate, landform and distribution of land and sea, the north limits of tropical China are winding, convex to the north or concave to the south in different places. Consisting of islands, peninsulas and coastal and sea areas, the eastern part of tropical China is characterized by its extensively distributed platforms and hills, and its maritime features, while the western part, situated at the south edge of Yunnan Plateau, is chara-cterized by its high mountains, deep valleys and basins, and its more continental climate. Acco-rding to different natural and social conditions, tropical China can be divided into four regions:(L) South Taiwan; (2) Hainan Island and Leizhou Peninsula; (3) South Yunnan; (4) Nan-hai (South China Sea) Islands.