Community structure and species composition of primary evergreen broad-leaved forest: based on a 1-hm² forest dynamics plot in Badong Golden Monkey National Nature Reserve, Hubei Province, China

Evergreen broad-leaved forest (EBLF) represents the zonal vegetation type of subtropical China, yet primary stands have become rare due to long-term anthropogenic disturbance. A remnant Castanopsis fargesii Franch. evergreen broad-leaved forest was identified in Badong Golden Monkey National Nature Reserve on the southern slope of Shennongjia, marking the northernmost distribution of this forest type. Following the protocols of the Forest Global Earth Observatory (ForestGEO) and the Chinese Forest Biodiversity Monitoring Network (CForBio), a 1-hm² forest dynamics plot (FDP) was established to investigate species composition and community structure. All woody plants with a diameter at breast height (DBH)≥1 cm were surveyed. The FDP contained 4 184 individuals, comprising 115 species, 79 genera, and 45 families. Of these, 61 species were evergreen and 54 were deciduous. Fagaceae, Lauraceae, and Symplocaceae were the dominant families, with Quercus and Castanopsis (Fagaceae) and Litsea (Lauraceae) serving as constructive species. The flora included 49 common, 46 occasional, and 20 rare species. Evergreen and deciduous broad-leaved species accounted for 87.12% and 12.88% of individuals. Family- and genus-level classification revealed a slight predominance of tropical over temperate elements. Size-class distributions of dominant species exhibited reverse ‘J’, near-reverse ‘J’, or skewed curves, reflecting stable population regeneration. Habitat preference and aggregated distribution patterns of dominant taxa suggested that habitat heterogeneity exerted a strong influence on the spatial organization of species in this subtropical evergreen broad-leaved forest.