Abstract:

Disjunct distributional patterns and the formative mechanisms resulting in distinct flora has been an important focus in the field of phytogeography. In this study, we compared vascular plant checklists of the Chinese mainland and Taiwan, and analyzed the formation mechanisms of the discontinuous taxa between southwestern area and Taiwan area in China. We documented 198 total species (including infraspecies) in 129 genera and 56 families disjunctly distributed in southwestern area and Taiwan area in China, among which 22 genera in 15 families have species-pairs with a disjunct distribution between the two regions, including six genera of ferns, one of gymnosperm, seven dicotyledons, and eight monocotyledons. The disjunct taxa are mainly herbaceous, most of which are ferns and orchids. These disjunct taxa are mainly distributed in the center-northeastern Taiwan area, and three regions of the mainland China, including eastern Sichuan-western Hubei, western Sichuan-northwestern Yunnan-southeastern Xizang, and southeastern Yunnan-western Guangxi-southwestern Guizhou. These taxa are generally distributed along an altitudinal gradient ranging from 1,550 m to 2,350 m. We believe that these disjunct patterns may have been derived from three possible origins including a northern temperate origin, southwestern China origin, and/or tropical Asia origin.

Key words: Taiwan area, southwestern China, vascular plants, flora, biogeography, disjunct distribution