Succession and topography jointly influence the diversity of plant sexual systems in the Baishanzu forest community

Aim: This study aims to investigate forest community patterns in the 25-ha forest dynamics plot of subtropical forest in Baishanzu, Zhejiang Province, and their relationship with environmental factors affecting woody plant sexual systems. The broader theoretical goal is to explore the impact of plant sexual system diversity on forest community assembly. Method: This study conducted a comprehensive survey of all woody plants with a stem diameter at breast height (DBH) ≥ 1 cm in the 25-ha forest dynamics plot of the Baishanzu (BSZ) forest in Qingyuan County, Zhejiang Province. We analyzed the abundance of different plant sexual systems, the DBH of species within each sexual system, the importance of each sexual system within the community, and the diversity of sexual systems within the plot. Additionally, redundancy analysis (RDA) was employed to quantitatively examine the influence of topography, soil physicochemical properties, and succession on the characteristics of different plant sexual systems. Results: (1) Among the 163 species of woody plants in the 25-ha plot, 95 were hermaphrodite, 43 were dioecy, and 25 were monoecy. Hermaphrodite exhibited dominance in quantitative characteristics at the family, genus, species, and individual levels. The average DBH of monoecy was significantly greater than that of hermaphrodite and dioecy. (2) At the quadrat level, hermaphrodite remained dominant, followed by dioecy and monoecy. The north-facing slope at higher elevation exhibited lower sexual system diversity, while the south-facing slope at lower elevation exhibited higher sexual system diversity. (3) The impact of topography on plant sexual systems surpassed that of soil physicochemical properties. Additionally, the succession stage significantly influenced the quantitative characteristics of plant sexual systems, with early successional areas exhibiting higher occurrences of dioecy and consequently greater sexual system diversity. Conclusion: The sexual systems of plants play an important role in forest community assembly in the BSZ 25-ha plot. Topography, soil physicochemical properties, and succession jointly shape the diversity of plant sexual systems in the forest community.