Analysis of Cyperaceae Flora in Gansu Province

To elucidate the species diversity and floristic characteristics of Cyperaceae flora in Gansu Province, this study catalogued all the Cyperaceae species found in the region through specimen collection, collation, and literature verification. Using these data, the genus and species composition, advantageous genera, endemic species, floristic characteristics and the relationship with the neighboring provinces were analyzed. In addition, ArcGIS technology was used to investigate the geographical distribution pattern of Cyperaceae. The findings are as follows: 1) There are 179 species belonging to 12 genera of Cyperaceae in Gansu Province, of which 130 species belonged to the dominant genus, Carex. There are 6 life forms, predominantly of the rhizome type. 2) Within the floristic elements of the genera and species, the temperate element is dominant, with genera primarily distributed in the North and South temperate disjuncted (Pan-temperate) regions. The areal-type species are mainly endemic to China and temperate Asian elements in Cyperaceae, with 43 species endemic to China, all of them belonging to Carex. 3) The horizontal distribution of Cyperaceae in Gansu is extremely uneven, with the highest observed in the West Qinling Mountains and Longnan Mountainous Region. The vertical distribution spans a wide range of altitudes, ranging from 500 to 4 100 m. Within this range, altitudes of 1 400～1 700 m has the highest number of species, with 58 species, accounting for 32.40% of the total species count. 4) There is a high similarity between Cyperaceae in Gansu and adjacent provinces, with the highest similarity observed with Cyperaceae in Shaanxi and Sichuan. These results indicate that Gansu had a rich diversity of sedge plants, with numerous Chinese endemic species, and the characteristics of the temperate properties are obvious. Given that Gansu confluences the Tibetan, Loess, and Mongolian Plateaus and other geographic units, it serves as a connecting area of several flora. This special geographical location results in the transitional characteristics of sedge flora in this area. The West Qinling Mountains and Longnan Mountainous Region in the southeast of Gansu are the distribution centers of Cyperaceae plants and the diversity centers of endemic species.