Clematis tientaiensis is a rare and endangered plant species endemic to Zhejiang Province, China, characterized by weak natural regeneration and a scarce extant population. To elucidate its endangerment mechanisms and formulate scientific conservation strategies, this study collected data from its natural community using the quadrat sampling method, with C. tientaiensis and its associated dominant species from the shrub layer (n = 19) and herb layer (n = 19) as the research subjects. By comprehensively applying niche analysis (niche breadth and overlap), interspecific association tests (overall association, \({\chi ^2}\) -test, association coefficient, Pearson and Spearman correlation analyses), and cluster analysis, we systematically revealed the resource utilization strategies and interaction patterns between the target species and its associated plants. The results showed that a total of 133 associated plant species were recorded in the C. tientaiensis community, belonging to 107 genera in 58 families. The proportion of liana species accounted for only 6.77%, and a shortage of seedlings was observed. C. tientaiensis belongs to the endemic Chinese distribution type, while 83.46% of the associated species or 70.00% of the dominant species belonged to the East Asian distribution type. In both the shrub and herb layers, C. tientaiensis exhibited the widest niche breadth (BL = 10.756 and BS = 2.508), but this ecological attribute did not enhance its population survival. The niche overlap among dominant associated species was generally low (mean value < 0.30), indicating weak interspecific resource competition. Furthermore, the overall associations among dominant species were not significantly negative. The ratios of positively associated species pairs to negatively associated species pairs were all below 1.00 in the \({\chi ^2}\) , AC, Pearson, and Spearman test results. According to the hierarchical clustering analysis results, C. tientaiensis was suitable for constructing a stable shrub community with associated plants such as Rubus idaeus, Lespedeza davidii, Mallotus apelta, and Oplismenus undulatifolius. In conclusion, the C. tientaiensis community is characterized by high species richness and a relatively complete structure, currently in the early unstable stage of positive succession with independent niche differentiation and loose interspecific associations. The majority of associated species, sharing similar resource requirements, created a niche monopoly effect that significantly inhibited resource acquisition by plants from other floristic regions. This may be a primary reason for the endangered status of C. tientaiensis. For the conservation and restoration of its native habitat, in situ protection of individuals should be implemented to enhance niche occupation, accompanied by appropriate replanting and optimization of associated species composition to improve community stability.
