Ecological niche and interspecific associations between rare plants and dominant species on the southern slope of Shennongjia

In 2024, a forest dynamics plot (100 m×100 m) was established in the Songzi Garden of the Badong Golden Monkey National Nature Reserve in Hubei Province, China. This study examined niche breadth and interspecific associations of four rare and endangered tree species (Davidia involucrata Baill., Dipteronia sinensis Oliv., Cercidiphyllum japonicum Siebold & Zucc., and Tetracentron sinense Oliv.) alongside dominant taxa within the plot. The survey recorded 111 woody species, including 38 evergreen and 73 deciduous species. Among them, one species was listed as nationally protected ClassⅠand six as nationally protected ClassⅡ, comprising 238 individuals that represented 9.6% of the total. Diameter class structure exhibited an inverted “J”-shaped distribution, reflecting robust regeneration and healthy community dynamics. Twenty species with importance values exceeding 1% were selected for further analysis, including five ecological specialists, one ecological generalist, and 14 neutral species. High values of niche overlap and similarity indicated strong interspecific competition. Overlap was low between D. involucrata and the other three protected taxa, but higher between D. sinensis and C. japonicum (0.56) and T. sinense (0.51). Overall, woody plant assemblages showed significant negative associations (P<0.05). Both association coefficient (AC) and Spearman rank correlation analyses revealed that negative interspecific association predominated, indicating that interspecific competition was a major driver of community organization.