Background and aims -The niche theory has become one of the fundamental theories to explain species coexistence. In the present study, the relationships between competition/ facilitation and species niche, and between displacement /coexistence and species niche were further explored by studying the realized niche dynamics of species along a succession process. Materials and methods -By using space series to replace time courses, the niche dynamics of species involved in the plant community succession process in the Waterfront Wetland of Yangtze Rivers Lower Reach, China, were studied by using the formula described by Levins and Pianka. Key results -Results showed that every succession stage community was dominated by the species with the highest or/and second highest niche breadths, revealing that these species had broader environmental tolerances and were able to use a wider range of resources. In general, niche overlaps were greater among species with higher niche breadths. The total average niche overlaps of all paired species at different succession stages first increased, reached its maximum in the late-middle stage, and then finally decreased slightly in the late stage in the entire succession process. Conclusion -The dynamic characteristics of niche of species reflect the process of displacement of species along the community succession process. The higher niche overlaps reflect the instability and transition state of plant communities along the successional process. Facilitation, as well as competition, occurs in the different species with higher niche overlap.

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