CHARACTERISTICS AND DRIVING FACTORS OF UNDERSTORY HERBACEOUS COMMUNITIES IN DIFFERENT PLANTATIONS AT PLAIN AFFORESTATION IN BEIJING

This study examined understory herb diversity and soil drivers in six Beijing Plain plantations: Styphnolobium japonicum (Stj), Robinia pseudoacacia (Rop), Fraxinus chinensis (Frc), Acer truncatum (Act), Ulmus pumila 'Jinye' (Ulp), and Salix matsudana (Sam).Key findings: (1) 34 herb species were identified, predominantly the family Asteraceae (41.18%), with Cirsium setosum, Artemisia argyi, Digitaria sanguinalis, and Artemisia scoparia as dominant species.(2) Rop plantations showed significantly higher Margalef, Simpson, Shannon-Wiener, and Pielou indices than others.(3) Soil properties varied significantly among plantations, with available nitrogen (AN, 17.27%), soil organic carbon (SOC, 16.81%), bulk density (BD, 10.92%), soil water content (SWC, 8.51%), and non-capillary porosity (NCP, 8.19%) being key factors affecting herb importance values.(4) Structural equation modeling revealed stand structure (path coefficient = 0.550) as the primary driver of diversity indices, outweighing stand density and soil characteristics.The results highlight Rop plantations' ecological advantages and demonstrate how soil chemistry and forest structure jointly shape herb communities.This research provides critical baseline data for optimizing plantation management and ecological restoration strategies in northern China's urban forest ecosystems.