Abstract: To investigate the effects of different tree species composition configuration and nursery management on the species diversity of plant communities at various levels in the understory of Pinus Massoniana forests, four typical stand types, namely, nurtured P. massoniana + Cunninghamia lanceolata mixed forest （Ⅰ）, nurtured P. massoniana + Camellia oleifera mixed forest （Ⅱ）, unmanaged P. massoniana pure forest （Ⅲ） and unmanaged P. massoniana + C.lanceolata mixed forest （Ⅳ） were selected at Qinglinkou of Zigui County, to comparatively analyse the diversity of species in the shrub layer, herb layer and regeneration layer of P. massoniana forests of different types, as well as the relationship with stand factors. The results showed that, the number of species in the understorey of different types of P. massoniana forests was highest in the shrub layer, and the number of species in each layer of the understorey of the nurtured P. massoniana + Cunninghamia lanceolata mixed forest was the highest. The Margalef’s richness index （DM）, Shannon-Wiener’s diversity index （H）, Simpson’s dominance index （D） and Pielou’s evenness index （E） in the shrub layer of the nurtured P. massoniana + C. oleifera mixed forest were significantly lower than those of other stand types （P < 0.05）; the DM, H and D indices of the herbaceous layer of different types of P. massoniana forests were in the same order of change, with Ⅰ>Ⅳ>Ⅲ>Ⅱ. The DM and D indices of the nurtured P. massoniana + C. lanceolata mixed forest were significantly higher than those of other communities （P < 0.05）; and there was a significant difference in the E index of the regeneration layer among different types （P < 0.05）. Stand density was significantly negatively correlated with DM, H, D and E indices of the shrub layer （P<0.01）; average height below branches was significantly negatively correlated with DM, H, D and E indices of the regeneration layer（P<0.05）. Species composition, maintenance management, stand density and mean understory height all had significant effects on the species diversity of the understory community of Pinus massoniana. It is suggested that in the process of management of P. massoniana forest stands in the Three Gorges Reservoir Area, it was necessary to continuously optimise the structure of the forest stands, configure suitable mixed species, strengthen the nurturing management, and reasonably regulate the density of the forest stands, which was conducive to promoting the development of the positive succession of Pinus massoniana plantation forest stands.

Key words: Pinus massoniana forest, species composition allocation, nursery management, understory plant community, Three Gorges Reservoir Area