Figure 1. Locations of the research area in Xishuangbanna, southern Yunnan, China, and compared regional ﬂoras (see Table 6). —1. Our research area. —2. Longgan, SW China. —3. Daqinshan Mountains, SW China. —4. Gulinqing, SW China. —5. Huapin, China. —6. Dongyang Mountains, China. —7. Cucphuong, N Vietnam. —8. Chiengdao, N Thailand. —9. The Malay Peninsula limestone. —10. Taiping, Malay Peninsula.
The forests on limestone in southern Yunnan, in tropical southwest China, were inventoried, and their ﬂoristic composition and biogeographical afﬁnities are discussed. These limestone forests were characterized by phanerophytes making up ca. 78% of the total species and those with mesophyllous leaves comprising 75%. Ecological species groups based on their habitat preferences were discerned from ﬁeld observations: the species exclusive to the limestone habitats make up 10% and the preferents make up ca. 12% of the total limestone ﬂora. From these limestone forests, 1394 vascular plant species belonging to 640 genera and 153 families were recorded. Based on their distributions, 12 biogeographic elements at the generic level and nine at the speciﬁc level were recognized. About 90% of the seed plant genera (over 90% of the species) were tropical; furthermore, 35% of the seed plant genera (65% of the species) have tropical Asian afﬁnities. In a comparison with other regional ﬂoras from southern China and tropical Asia, the limestone ﬂora of southern Yunnan revealed closer afﬁnity to tropical ﬂoras than to temperate elements of eastern Asian ﬂoras. This limestone ﬂora is thus tropical and part of the tropical Asian ﬂora at its northern margin.
Key words: biogeography, China, limestone forest, southern Yunnan.
Zhu, H., H. Wang, B. Li, P. Sirirugsa. 2003. Biogeography and floristic affinity of the limestone flora in southern Yunnan, China. Annals of the Missouri Botanical Garden. 90: 444-465.: