| Abstract: | Using the methods of PCA and TWINSPAN, floristic data of seventy-six mountain floras
in the Chinese subtropical region were quantitatively analyzed to reveal the compositional characteristics of its floristic elements, the relationships of its different floristics elements, and the correlation as well as the spatial differentiation of its floristic element composition. Moreover, a north-south transect between 108.5°∽111.5° E and an east-west transect between 29°∽31° N were set up to analyze the spatial gradients of several floristic elements. The results are summarized as follows: ① In the subtropical region, the 15 areal-types of genera of seed plants of China fall into 4 groups:
tropical, temperate, arid and eastern Asian, with the pantropic elements and the northern temperate
elements being of the highest percentage, the eastern Asian elements being of a very high percentage, and the endemism being of a very high degree, while the arid elements being of a very low percentage. ② As shown by the result of PCA, the northern, middle and southern parts of the Chinese
subtropical region are well differentiated in terms of their floristic composition, but the eastern and
the western parts are not clearly differentiated. ③ The transect analysis has clearly shown the gradient pattern of the ratio of tropical vs. temperate elements, the status of the region from eastern Sichuan to Western Hubei as a distribution center of the Chinese endemic genera, and the contrary
distribution pattern of the cosmopolitan elements and the Chinese endemic elements in the Chinesesubtropical region. |
