Abstract: The species diversity of Dipentodon sinicus communities in Yushe National Forest Park of Guizhou province was studied based on the quadrate method. The results showed that Rosaceae, Ericaceae, Betulaceae, Fagaceae, Theaceae, Lauraceae, Caprifoliaceae, Cornaceae were the dominant families in D. sinicus communities of Yushe National Forest Park. In the 10 sample plots, there were 8 which were absolutely dominated with D. sinicus population, the importance value came up to 135.69 on average, and it was far higher than the others. For D. sinicus communities, the abundance index (2.847), Simpson index (0.601), Shannon-Wiener index (1.523), probability of inter-specific encounter (0.601) and species evenness (0.569) of the tree layer were lower than those of the shrub layer (5.580, 0.830, 2.377, 0.829, 0.672, respectively) on the whole. It markedly showed a species diversity characteristic of the mixed broadleaved evergreen and deciduous forest in middle subtropics. In the 10 sample plots, the species diversity level of Q₁ (the first sample plot) was the highest, followed by Q₃, Q₅ and Q₆ was the lowest. The species diversity indexes of the 10 communities decrease in the order of Q₁>Q₃>Q₉>Q₇>Q₂>Q₄>Q₁₀>Q₈>Q₅>Q₆.

Key words: Dipentodon sinicus, Yushe national forest park of Guizhou province, rare plant, community, species diversity