A Checklist and Its Geographical Distribution of Vascular Plants from Xizang

The Xizang Autonomous Region, the provincial administrative region with the second largest land area in China, is located on the vast Qinghai-Tibet Plateau, which, in addition to being the tallest and largest plateau in the world, is also an incredibly rich biodiversity hotspot, supporting a variety of ecosystem. Flora Xizangica (Vols. 1–5), which was completed from 1983 to 1987, contains 6398 vascular plants (including varieties and subspecies). It is of great significance in botanical research, resource development and utilization, ecological environment protection in Xizang, and is also the most basic reference book for people to understand plants, their resource distribution, and living environment in Xizang. Due to the limitations of the objective conditions at that time, such as inconvenient transportation, vast territory, large compilation workload and limited time, many problems still remain among Flora Xizangica. It mainly includes: (1) Flora Xizangica is the flora with the largest number of missing species in China. For example, Flora Xizangica recorded 193 species of orchids. Our latest statistics show that there are 838 species of orchids in Xizang, which is 4.3 times the number recorded in Flora Xizangica. (2) A large number of species in the southern Tibetan region have not been included. (3) "Tibet" usually refers to Tibetan areas (including Qinghai, Sichuan, Gansu, Yunnan, and Indian controlled Kashmir), which is larger than the Xizang Autonomous Region. Plants recorded as "Tibet" in type specimens are not necessarily plants of Xizang Autonomous Region. Currently, many types of such distribution errors need to be corrected. (4) Due to the border with India, Nepal, Bhutan, Myanmar and other countries, plants in Xizang need to be compared with those from surrounding countries in order to obtain reasonable classification and treatment. We had compiled information extracted from floras, periodical literature, dissertations, collected specimens from field surveys, and the Plant Photo Bank of China (PPBC) to provide an updated dataset of vascular plants in Xizang (Chen et al. 2023. A dataset on inventory and geographical distribution of vascular plants in Xizang, China. Biodiversity Science, 31(9): 23188). Based on this dataset, we provided a checklist of vascular plants in Xizang includes 11,817species (including varieties and subspecies), belonging to 2049 genera of 252 families, including 50 species of lycopsids belonging to 7 genera of 2 families, 696 species of pteridophytes belonging to 110 genera of 31 families, 83 species of gymnosperms belonging to 19 genera of 6 families, and 10,988 species of angiosperms belonging to 1913 genera of 213 families. Compared with the 6398 species in Flora Xizangica, the number of vascular plants included in this checklist increased by 5419, or about 85%; In addition, about 1700 species have not been found in literature, which may be new records in Xizang. From this checklist we identified the top 10 families possessing the highest number of species in this region (Asteraceae, Orchidaceae, Poaceae, Fabaceae, Rosaceae, Ericaceae, Ranunculaceae, Lamiaceae, Primulaceae, and Apiaceae). Finally, we also generated a checklist of vascular plants with excluded/dubious records in Xizang, which includes 920 species of 467 genera across 123 families. Flora Xizangica needs to be revised urgently, which is an urgent challenge for Chinese plant taxonomists. This study will provide an expanded basic background and central framework for the second edition of Flora Xizangica, as well as serve as an important reference for plant diversity conservation and monitoring throughout Xizang forward.