LAUSR

The Ordos Plateau is one of the biodiversity hotspots in the arid and semi-arid areas of China. To extend our knowledge of the flora in this region, we integrated documented data and field survey data to present quantitative analyses on the taxonomy, life forms, endemism, and composition of geographical elements. In total, 790 species of seed plants belong to 346 genera in 87 families are recorded. The area is characterized by herbaceous plants with 606 species (77%), and there are 145 shrub species. The flora of the Ordos Plateau is complex in geographical elements and shows obvious transitional and ancient originated characteristics. At the species level, temperate elements are the most species-rich, accounting for 40.05%, followed by East Asian elements, desert elements, steppe elements, and ancient Mediterranean elements (24.61%, 18.85%, 9.42% and 5.24%, respectively). Compared with adjacent regional floras, the Ordos Plateau flora possesses fewer East Asian elements than the Junger loess hill-gully and fewer grassland element than the flora of Mongolian Plateau. However, the proportion of Desert elements in the Ordos Plateau flora is similar to that of the Alashan Desert. Additionally, the Ordos Plateau possesses the highest ratio of ancient Mediterranean elements than adjacent regional floras. Of the flora on the Ordos Plateau, nine genera are endemic to China, and 41 species are endemic to Alashan-Ordos. To evaluate the continuing status of this area as a biodiversity hotspot, we suggest that floristic diversity may serve as a criterion for measuring biodiversity and guiding its conservation.