Abstract: Exploring the interspecific relationships, ecological niches of main plant species, and community stability in Pinus massoniana forest of canyon habitat is beneficial to creating a scientific foundation for forest resource management in the Guangdong Grand Canyon. The importance value (IV), niche breadths (B_L and B_S), niche overlaps (O_ik), OI and DI indices of dominant plant species were calculated based on survey data and the 2×2 contingency table of Pinus massoniana forest plot. The interspecific associations (AC) of dominant species were analyzed using the variance ratio (VR) method and the chi-square test. Community stability was evaluated using the Godron method. The results showed that: (1) As the constructive species, Pinus massoniana had the highest importance value (IV=40.11%) and ecological niche breadth (B_L=12.53, B_S=2.64), followed by Cunninghamia lanceolata, Rhododendron kwangtungense, Schima superba, Platycarya longipes, Myrica rubra, and Elaeocarpus glabripetalus. Those seven species dominated resource competition in the community, with substantial niche overlap with other species. (2) Among the 78 species pairs of the dominant species, the species pairs with negative associations (53.85%) outweighed that of positive associations (44.87%). The results of χ² test showed that the species pairs with significant associations accounted for 10.26% and those with non-significant associations accounted for 89.74%. The species pairs with OI and DI values less than 0.4 accounted for 69.23% and 73.08% of the total species pairs, respectively, indicating a high degree of negative inter-species association, strong relative independence and loose association of the species pairs. (3) Results of the Godron method demonstrated that the community was at an unstable state, with a negative interspecific association in the community (VR=0.62, W=18.44). We proposed that Rhododendron kwangtungense, Schima superba, Platycarya longipes, Myrica rubra, and Elaeocarpus glabripetalus should be selected as the constructive species to promote near-natural succession in the Pinus massoniana forest in Guangdong Grand Canyon.

Key words: Pinus massoniana, interspecific relationship, ecological niche, community stability