Abstract:A large canopy simulation and nitrogen deposition field control experimental platform was established on southern slope of Tiger Mountain in Shimentai National Nature Reserve, Guangdong Province, China. To further understand the characteristics of vegetation composition at the platform, 18 plots covering a total area of 0.72 hm2 were set up. The results showed that there were 127 vascular species, belonging to 86 genera and 53 families. Furthermore, there were 2 465 individuals with diameter at breast height (DBH) ≥ 1.0 cm. The tree density was 0.34 ind./m2, and the tallest up to 25 m. The dominant species in the community was Castanopsis chinensis, Ardisia quinquegon, and Schima superba, which was a secondary evergreen broad-leaved forest consisting of phanerophytes, medium-and small-leaf, leathery, and unentire leaf as main species. The tropical-subtropical floristic elements were dominant in the community, with the characteristics of transition from the tropical to subtropical. Among 18 plots at tree layer, the Simpson index (0.851-0.936) and Shannon-Wiener index (3.504-4.494) were similar; the Pielou's evenness index was high (0.780-1.000); and the Gleason and Margalef richness indexes were rather variable (3.209-7.738 and 16.760-40.806, respectively). The plots shared 10-26 species with Sorensen similarity coefficient of 0.377-0.722. On the contrary, in shrub layers, the above indexes all varied greatly, and only 0-10 common species among plots with Sorensen similarity coefficient of 0-0.714. Therefore, the effect of shrub layer density and species difference on community structure should be considered.