Objective China National Botanical Garden as an institution that carries out ex situ conservation of plants at the national level and undertakes the important task of plant diversity conservation in China. Taking the first national botanical garden in China as an example, this research discusses the main approaches and methods for national botanical gardens to contribute to plant diversity conservation, for purpose of providing reference for the construction of a national botanical garden system in China.

Analysis This research introduces the concept of biodiversity, the general situation and existing problems of biodiversity in China and the significance of biodiversity conservation. China is one of the most biodiverse countries in the world. There are still some problems in China's biodiversity conservation, although a lot of efforts have been made. A national botanical garden of a country typically serves as a national base for plant diversity conservation in and a representation of the country. On December 28, 2021, the State Council approved the establishment of the national botanical garden in Beijing. On April 18, 2022, the national botanical garden was officially inaugurated in Beijing and named as China National Botanical Garden, marking a new chapter in the construction of national botanical garden system in China. There are four main approaches and methods for national botanical gardens to contribute to biodiversity conservation. First, effectively preserve valuable plant resources through species collection. By now, the China National Botanical Garden has collected and preserved about 17, 000 species of plants (including subspecies), including 786 endemic species in China, 354 species included in the List of National Key Protected Wild Plants (2021), 1, 412 species included in the Appendix to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), and 79 critically endangered (CR) species, 150 endangered (EN) species and 170 vulnerable (VU) species included in the Volume of Higher Plants in the China Biodiversity Red List, covering Orchidaceae, Gesneriaceae, Araceae, Cycideraceae, Serodiaceae, Cactus and other plant groups. It can be said that China National Botanical Garden has become a "Noah's Ark" for the protection of rare and endangered plants, and has provided rich plant materials for scientific research, science popularization, horticultural exhibition, etc. Second, provide scientific support for ex situ conservation through scientific research. China National Botanical Garden has organized and completed the preparation of both the Chinese and English versions of Flora of China, a national flora of China with great achievements in ex situ conservation of rare and endangered plants, such as Orchids, Metasequoia glyptostroboides, Welwitschia mirabilis, Amorphophallus titanum and Clematis acerifolia. Third, contribute to global biodiversity conservation through international cooperation. China National Botanical Garden is one of the most important members of the Botanical Gardens Conservation International (BGCI) and a member of the International Advisory Committee (IAC). It is also one of the founding members and East Asian representative of the Climate Change Alliance of Botanic Gardens (CCABG), and a base for international scientific and technological cooperation in Beijing that represents the image of Beijing and China as a whole. In addition, China National Botanical Garden has conducted international scientific and technological cooperation and exchanges successively with more than 70 international famous botanical gardens and professional organizations, such as the Royal Botanic Gardens, Kew, the Australia Royal Botanic Garden, and the Arnold Arboretum of Harvard University. Last but not the least, raise public awareness of biodiversity conservation through public education. The Public Education Center of China National Botanical Garden receives about 1 million visitors each year, and attracts more than 10 million of online and offline audiences through holding science popularization activities, publishing science popularization articles and videos, etc. In 2021, China National Botanical Garden was recognized as one of the first national science popularization education bases in China by China Association for Science and Technology on the ground that it plays an important role in improving people's awareness of biodiversity conservation and scientific literacy. On July 11, 2022, the South China National Botanical Garden was inaugurated, marking the beginning of the construction of China's national botanical garden system. Steady progress has been made in the buildng of the national botanical garden system following the goal of gradually covering the ex situ conservation of more than 85% of wild native plants and all key protected wild plant species in China.

Prospects Under the background of ecological civilization, the research envisions the future responsibility, mission and work direction of national botanical gardens in China. In the future, the national botanical gardens should intensify efforts on such tasks as biodiversity inventory, improvement of ex situ plant biology data, compilation and research of biodiversity annals, research on the causes of species endangerment and survival strategies, biodiversity monitoring, collaborative management of biodiversity conservation and climate change response, and the impact of invasive species. Meanwhile, national botanical gardens should work closely with the natural protection area system with in situ conservation as the main function, to improve China's biodiversity conservation security system, and provide a strong guarantee for the construction of ecological civilization and sustainable development in China.