Exploration on the outstanding universal values of Hainan potential world natural heritage site

World natural heritage sites are some of the most important and valuable protected areas in the world, and their designation aims to give recognition to the uniqueness and protect the integrity of the sites, which are of global outstanding universal value. Understanding the global uniqueness and value of natural heritage will help to better manage and protect them, support the functioning of ecosystems, and promote sustainable development of humans and nature. A systematic review was conducted to determine the potential for the Hainan tropical rainforest to become a world natural heritage site. Based on a large number of literatures, we took the native plants, animals and vegetation communities of Hainan’s potential natural world heritage site (Hainan Tropical Rainforest National Park) as the research objects, and evaluated the global outstanding universal value of Hainan’s potential natural world heritage site from the aspects of biological ecological processes such as vegetation types, species diversity, fauna composition and endemic species. The results are as follows: (1) Hainan potential world natural heritage site has 3 653 vascular plant species. There are 540 species of terrestrial vertebrates, which account for 10%-30% of the wild animal species in the country. This indicates that biodiversity in this area is extremely high. (2) The flora found in the Hainan tropical rainforest is unique. Vegetation on Hainan Island can be categorized in the Indo-Malay rainforest group, and within the Malay region, and vegetation is tropical in nature and has a common origin with the South China mainland. This is indicative of the transition between the South China flora into the Asian rainforest. (3) The plant species specificity of flora is lower, there are only seven endemic genera in the flora, and about one out of every 10 species is endemic to the island. Lower specificity shows some characteristics of continental origin and the flora on the island are an irreplaceable element of biodiversity, and make up a valuable ecosystem. This study clarifies the outstanding universal values of the Hainan tropical rainforest and makes the case using empirical scientific evidence for nominating this area as a world natural heritage site.