Abstract: Clarifying species composition and diversity is conducive to understanding the basic situation of the tropical natural forests in Jianfengling, which will provide data support for biodiversity conservation, the construction of tropical rainforest national parks, and subsequent research. We investigated woody plants with diameter at breast height (DBH) ≥1.0 cm in 106 kilometer-grid plots of tropical natural forest in Jianfengling, with reference to the Chinese forest inventory grid method and plot survey method. The species composition, species-area relationship, diameter-class structure, and relevant affecting factors were analyzed. The results showed that there were a total of 33170 woody plants in the plots, belonging to 71 families, 296 genera, and 345 species, including 74 rare species and 131 common species. There were 19 species with an importance value ≥1, and the cumulative importance value was 29.7. The average DBH in the plots was 5.88 cm, and the diameter-class structure showed an inverted "J" shape. The Shannon index was significantly positively correlated with species richness, Simpson index, and Pielou index, while the Simpson index was significantly positively correlated with the Pielou index. A total of 15 species of China’s national key protected wild plants were recorded, with a national first-level key protected wild plant (Hopea hainanensis) and 14 species such as Vatica mangachapoi being national second-level key protected wild plants. In conclusion, the plots were rich in plant species, with no obvious dominant species, and had good overall regeneration ability. The individual quantity and regeneration ability of national key protected wild plants were good, and some common species can be introduced and planted in areas with similar habitats.

Key words: Jianfengling, tropical natural forest, kilometer-grid plot, species composition, biodiversity, national key protected wild plants