Abstract:Based on the observed data from 288 plots in tree layer, shrub layer and herbaceous layer in a Symplocos sumuntia secondary forest community in Bifengxia, we quantitatively analyzed the niche characteristics of main species in these three different layers in a S. sumuntia secondary forest community and similarity of community species using Levins and Hurlber niche breadth, Pianka niche overlapping indices, and Sφrensens similarity coefficient. By revealing the interference relationship of secondary forest community in Bifengxia, it demonstrated the main species in different layers can be changed in adapting the environment and relative status, which clarified the ecological adaptability of the species. It provided a theoretical basis for the stability of the ecosystem. The results suggested: (1) S. sumuntia with higher capability of adapting to environment and resources in the investigated habitat had wide niche breadth under different levels of anthropogenic disturbance, which was the major species of community composition. With the increasing of disturbances, the niche breadth of Theaceae increased in the tree layer, and the niche breadth of Cyclobalanopsis glauca increased first and then decreased. The niche breath of Cunninghamia lanceolata decreased but that of Phoebe neuranthoides increased in shrub layer under severe disturbance, and the niche breadth for most other species were the lowest under medium disturbance. In the herbaceous layer, the niche breath for Dryopteris erythrosora increased under severe disturbance with wider adaptive range. (2) Under severe disturbance, the overlap values for S. sumuntia and Ilex chinensis in tree layer increased. Under medium disturbance, the overlap values of Rubus lambertianus and Symplocos stellaris only appear in the shrub layer. With increasing disturbances, the overlap niche values of Vittaria flexuosa disappear, and the same values of D. erythrosora appear and become high. The overlap niche values of main populations in all layers became minimum under medium disturbance. (3) The Sφrensens similarity coefficient between tree layer and herbaceous layer is higher than 0.8; in shrub layer, the Sφrensens similarity coefficient of severemedium disturbance level, mediumslight disturbance level and severeslight disturbance level were 0.636, 0.746 and 0.608, respectively. In conclusion, under different levels of anthropogenic disturbance, the interspecies competition caused the utilization of resources is more intense in the S. sumuntia forest, the distributed pattern of species community and succession direction are affected and the species community of forest becomes unstable.