Species diversity pattern and its drivers of the understory herbaceous plants in a Chinese subtropical forest

Understory herbaceous plants are an important component of forest ecosystems, playing important roles in species diversity and forest dynamics in forests. However, the current understanding of the biodiversity of forest communities is mostly from woody plants, and knowledge of community structure and species diversity for understory herbaceous plants remains scarce. In a subtropical forest in China, we investigated understory vascular herbaceous diversity from 300 plots (5 × 5 m) in the main growing season. In this study, we analyzed the community structure and diversity pattern of the understory herbaceous community and linked the species diversity pattern to both abiotic and biotic environments. We found a rich diversity of understory herbaceous communities in this forest (81 species belonging to 55 genera), and floristic elements at the genus level were dominated by tropical elements, followed by temperate elements. The diversity pattern of the understory herbaceous showed a significant habitat preference, with the highest diversity in the lowland valleys and then followed by in middle slopes. In addition, herbaceous diversity was significantly affected by both abiotic factors (such as terrain convexity) and biotic factors (such as the diversity of surrounding woody plants). Our study indicated that species diversity of understory herbaceous showed a remarkable habitat preference, such as lowland valleys, and highlighted the importance of both abiotic and biotic environments in driving herbaceous diversity patterns in the subtropical forest understory.