Checklist of national key protected wild plants on the Qinghai-Tibetan Plateau

Abstract Background Qinghai-Tibetan Plateau is a global biodiversity hotspot due to the unique geographical environment. However, there are few reports on the list of national key protected plants and the distribution pattern of their diversity in this area. Based on the flora and online database, this paper summarised the species diversity and distribution patterns of national key protected wild plants on the Qinghai-Tibet Plateau. New information The results showed that there were 350 species of national key protected wild plants on the Qinghai-Tibetan Plateau, belonging to 72 families and 130 genera. Amongst them, 22 species were under class I protection, 328 species were under class II protection and 168 species were endemic to China. Its endangered status involves EW 1 species, CR 17 species, EN 90 species, VU 90 species, NT 30 species, LC 60 species and DD 62 species. Species diversity declined gradually from the southeast to the northwest with hotspots located within Sanjiang Valley subregion (ⅢE14a). The list of national key protected wild plants and their diversity and distribution patterns in the Qinghai-Tibetan Plateau can provide basic data for the conservation of regional biodiversity and the formulation of conservation strategies.


Introduction
China is one of the most biodiverse countries in the world. There are approximately 483 families, 4,275 genera, 38,493 species and 7,507 subspecies of higher plants, of which approximately 18,000 species are endemic to China (Liu and Qin 2022). However, biodiversity in China is still under great pressure. On the one hand, species diversity is seriously affected by sharp population growth, rapid economic development and the degradation or even loss of natural ecosystems. On the other hand, excessive mining, alien species invasion and natural disasters severely damage the species diversity (Liu et al. 2020). The Chinese government attaches great importance to biodiversity conservation. Relevant laws and policies have been promulgated and the legal framework has been continuously improved. The State Council issued "the List of National Key Protected Wild Plants (First Batch)" in 1999, which includes 246 plant species (varieties) and eight plant categories (State Forestry Administration and the Ministry of Agriculture, P.R. China 1999). The protection of wild plants in China has undergone significant changes since the release of the list in 1999. Some endangered wild plants have been effectively protected and the degree of endangerment has reduced. However, significant changes have occurred in the protection of wild plant diversity in China over the past 20 years. Therefore, in September 2021, the National Forestry and Grassland Administration and the Ministry of Agriculture and Rural Affairs released "the List of National Key Protected Wild Plants (2021)" (hereinafter as List (2021)), which includes approximately 1,101 species (455 species and 40 categories) of wild plants, of which 54 species and four categories of wild plants are under first-class state protection and 401 species and 36 categories of wild plants under second-class state protection (State Forestry and Grassland Administration and the Ministry of Agriculture and Rural Affairs, P. R. China 2021). The 15 UN Biodiversity Conference (COP15), held in October 2021, discussed the Post-2020 Global Biodiversity Framework, with the main objective of responding to the continuing deterioration of biodiversity worldwide. Therefore, strengthening the protection of wild plants to reverse the decline of wild populations and extinction of species was one of the key topics. In this context, based on the List (2021), it is necessary to investigate and sort the species, family and genus composition, endemism, endangered status, geographical distribution and other characteristics of national key protected wild plants in specific areas, especially in ecologically fragile areas, to provide important references for in situ protection, ex situ protection and standardised use of species. th Known as the "roof of the world" and the "third pole", the Qinghai-Tibetan Plateau is the highest and youngest plateau in the world. With diverse vegetation types and complex floristic components, the Qinghai-Tibetan Plateau is the most biodiverse region on Earth. It is also a vulnerable area of ecosystem and is sensitive to climate change. This region contains three global biodiversity hotspots: the Himalayas, mountains of Southwest China and Indo-Burma (Myers et al. 2000). The unique natural environment and strong changes in the historical geological environment make the Qinghai-Tibetan Plateau possess many complex fragmented habitats and rich species. According to the second Qinghai-Tibet Scientific Survey data, there are 14,634 vascular plant species on the Qinghai-Tibetan Plateau, accounting for 45.8% of vascular plants in China (Fu et al. 2021). Amongst these, 3,764 species of seed plants endemic to the Qinghai-Tibetan Plateau were included .
With the intensification of global climate change and owing to the vulnerability and sensitivity of the Qinghai-Tibetan Plateau to climate change and increasing human activities, the biodiversity of this region is facing a severe threat ) and various wild plants are highly endangered. However, there are only a few reports on the diversity and distribution patterns of national key protected plants on the Qinghai-Tibetan Plateau. Therefore, based on the List (2021), this study preliminarily sorted out the species of national key protected wild plants in the Qinghai-Tibetan Plateau Region, analysed their diversity, endangered status and endemic status and explored their distribution patterns, hoping to provide a reference and basis for the study of national key protected wild plants on the Qinghai-Tibetan Plateau.

Determination of plant list
With reference to the Qinghai-Tibetan Plateau boundary data (Zhang 2019), plants in the List (2021), distributed only in the Qinghai-Tibetan Plateau Region, were collected. First, based on the Flora of China (Wu et al. 1994), specimen information was obtained from the National Specimen Information Infrastructure (NSII, http://www.nsii.org.cn/2017) and the Chinese Virtual Herbarium (CVH, https://www. cvh.ac.cn/index.php). Combined with field scientific survey records collected in recent years, the family and species lists, as well as county-level distribution of key protected wild plants on the Qinghai-Tibet Plateau were, sorted out. Threatened status and endemism of species were confirmed from the IUCN Red List of Threatened Species 2021 (IUCN Red List of Threatened Species), China Red List of Biodiversity (Higher Plants Volume) (Ministry of Environmental Protection of the People's Republic of China and Chinese Academy of Sciences 2018). Based on cataloguing, diversity characteristics of national key protected wild plants on the Qinghai-Tibetan Plateau were analysed and summarised, including family and genus composition characteristics, protection level, endemism, endangered status and geographical distribution characteristics. Floristic division scales of Qinghai-Tibetan Plateau were according to the Floristics of seed plants from China  respectively. However, the genus with only one species included 77 genera, accounting for 59.23% of all the genera (Fig. 2).

Endemic and endangered status of taxa
According to statistics, there are 14,939 species of endemic seed plants in China and 3,764 species of endemic seed plants in the Qinghai-Tibetan Plateau . The national key protected wild plants distributed on the Qinghai-Tibetan Plateau included 168 species endemic to China, including 16 species of Lycopodiophyta, three species of Pteridophyta, 14 species of Gymnospermae and 135 species of Angiospermae. The species of seed plants (Gymnospermae and Angiospermae) endemic to China (149 species) accounted for 1.00% of the total species endemic to China. There were 57 species endemic to the Qinghai-Tibetan Plateau, including eight species of Lycopodiophyta, three species of Gymnospermae and 46 species of Angiospermae. The species of seed plants (Gymnospermae and Angiospermae) endemic to the Qinghai-Tibet Plateau (49 species) accounted for 1.30% of the total seed plants endemic to the Plateau.
In terms of protection level, there were 22 species of Class-I protected plants, including two species of Lycopodiophyta, one species of Pteridophyta, nine species of Gymnospermae, nine species of Angiospermae and one species of Cyanophyta. There were 328 species of Class II protected plants, including five species of Bryophytes, 24 species of Lycopodiophyta, 10 species of Pteridophyta, 16 species of Gymnospermae and 273 species of Angiospermae.
In terms of endangered status, one species, Cystopteris chinensis, was extinct in the wild (EW), 17 species were critically endangered (CR), such as Calanthe dulongensis, 91 species were endangered (EN), such as Cephalotaxus lanceolata, 90 species were vulnerable (VU), such as Cypripedium henryi and 30 species were near threatened (NT), such as Paris polyphylla var. yunnanensis, 60 species were of least concern (LC), such as Huperzia selago and 62 species had data deficiency.

Geographical distribution pattern
On the Qinghai-Tibetan Plateau, the diversity distribution pattern of national key protected wild plants showed a decreasing trend from the southeast to northwest. There were 169 species and 13 varieties in the Yunnan Province, with 13 Class-I and 156 Class-II species. In Sichuan Province, 169 species, 12 varieties and one subspecies were distributed, including nine Class-I species and 173 Class-II species. In the Tibet Autonomous Region, 155 species and five varieties were distributed, including nine Class-I species and 151 Class-II species. In Gansu Province, 75 species, five varieties and one subspecies were distributed, including six Class-I species and 75 Class-II species. In Qinghai Province, 46 species were distributed, which were all Class-II species. Eighteen species were distributed in the Xinjiang Uygur Autonomous Region, including 18 Class-II species.
From the distribution at the county-level (Fig. 3), the distribution of nationally protected wild plants on the Qinghai-Tibetan Plateau was the highest in Gongshan and Yulong counties in Yunnan and Motuo County in Tibet, with at least 80 species. Species distribution in Deqin, Weixi and Fugong counties of Yunnan; Chayu County of Tibet; and Kangding, Luding and Tianquan counties of Sichuan was concentrated, with 51-80 species. The species distribution in most areas from southeast to northwest Tibet was very low, with fewer than 10 species.
From the floristic distribution (Fig. 4), the species distributed in the Sanjiang Valley subregion (IIIE14a) and the South Hengduan Mountain subregion (IIIE14b) were the most dense, with more than 160 species, followed by species distributed in Southeast Asia of Tibet (IIIE15b) and Taohe-Minshan subregion (IIIE14d). Only less than 10 species were found in the Qaidam Basin subregion (IIC6b) and Pamir-Kashi Kunlun subregion (IIF17c).

Discussion
The Qinghai-Tibetan Plateau is not only a gene pool for plateau species and a hotspot for global biodiversity protection, but also an important ecological security barrier for China and Asia, which is one of the key areas of ecological civilisation construction in China. Due to the fragility and irreversibility of the alpine ecosystem, their environmental sensitivity and the increasing impact of climate warming and human disturbance, their biodiversity is facing serious challenges. Therefore, the protection of biodiversity and ecological security is the core task of ecological protection in the Qinghai-Tibetan Plateau. To date, 196 naturally-protected areas, including national parks, nature reserves, wetland parks, national forest parks and national geoparks, have been designated on the Qinghai-Tibetan Plateau (Hu 2020). These natural protected areas play an irreplaceable role in the protection of biodiversity resources on the Tibetan Plateau, especially in the protection of endangered and critical species on the Plateau (Fu et al. 2021). However, in the literature review, it was found that the population status of national key protected wild plants in this area, including the distribution of wild species, population size and genetic background information, is not yet clear and there are still blind areas of species distribution. Therefore, it was necessary to conduct a comprehensive investigation and assessment of the current status of these protected plants in the field.
Plant diversity patterns play an important role in maintaining the ecological balance of the Qinghai-Tibetan Plateau. Historical orogeny and related climatic changes are the main driving forces behind the formation of plant diversity patterns in the Qinghai-Tibetan Plateau (Muellner-Riehl 2019). On the one hand, the uplift of the Qinghai-Tibetan Plateau has greatly changed the surface pattern of the region and the geographical barriers such as mountains, canyons and "sky island" formed have restricted the gene flow amongst plant populations and promoted species differentiation , Khan et al. 2018). On the other hand, the uplift of the Qinghai-Tibetan Plateau also leads to the Indian and East Asian monsoons (Tada et al. 2016) and the change in the monsoon climate may be another important driving force for plant evolution in this region (Liu et al. 2013, Wen et al. 2014, Sun et al. 2015. In addition, the alternation of Ice Ages experienced in this region since the Pleistocene has led to habitat fragmentation of many originally continuously distributed species, which retreat to isolated Ice-Age sanctuaries, resulting in the lineage differentiation and the generation of many new species through allogeneic speciation (Wang et al. 2010, Ren et al. 2017. Under the influence of these special natural geographical conditions and speciation mechanisms, most of the national key protected plants on the Qinghai-Tibetan Plateau have a narrow distribution and small population size, which highlights the importance and urgency of sorting, investigating, collecting and protecting these germplasm resources.
In this study, the species distribution information was mainly sorted based on flora, virtual specimens and part of the field investigation data; thus, errors in the data are inevitable. Subsequent research on physical specimens and field investigation data can further clarify the distribution status of national key protected plants on the Qinghai-Tibetan Plateau.