Diversity and distribution of higher plants in Yunnan, China

Yunnan Province is a biodiversity hotspot in China that has global significance. In order to further recognize and protect the biodiversity of Yunnan, we examined the basic distributional pattern of its plant diversity based on Flora Yunnanica. According to our analysis, Northwest Yunnan had the highest plant diversity, with Yulong County the most diverse, containing 4,358 species of higher plants, followed by Gongshan County and Xianggelila County, which had 3,981 and 3,874 higher plants respectively. The tropical edge region of southern Yunnan, represented by Xishuangbanna, had the second highest level of diversity, with Mengla County and Jinghong County containing more than 3,000 higher plant species. In contrast, the plant diversity of Eastern and Central Yunnan, comprising mainly the Yunnan Plateau, was deemed relatively poor, possibly reflecting lower attention and field surveys by botanists. Both the distribution patterns of endemic and narrow-ranging species were similar to that for all plants. Yunnan contains 4,008 endemic and 4,509 narrow-ranging species with Gongshan County being most diverse, having more than 500 narrow-ranging species. Most species (64.1%) were distributed in less than five counties in Yunnan, and 46.0% could only be found in one. Our analysis reveals that previous field surveys of Yunnan’s plant diversity did not fully reflect the natural zonal regularity and consequently further investigation is warranted. Some narrow-ranging species will be endangered without protection.