Abstract: As an important component of forest ecosystems, herbaceous plants are of great significance for vegetation restoration and the enhancement of biodiversity. Studying the niche, interspecific associations, and species co-occurrence networks of herbaceous plants in plantation forests helps to understand the community dynamics and resource utilization of Picea asperata plantation forests. In this study, we examined the niche breadth, niche overlap, overall association, interspecific associations, and species cooccurrence networks of 25 herbaceous plant species with an importance value (IV) greater than 1. The results showed that the relationship between importance values and niche breadths was uncertain. The average niche overlap index was 0.309, indicating a low overlap of herbaceous plants in the Picea asperata plantation. The understory herbaceous plants showed a highly significant overall positive association. With the Pearson correlation test and Spearman rank correlation test, the positive-to-negative association ratios were 0.65 and 0.66, and test significance rates were 19.67% and 42.33%, respectively. There was no significant association among most species. The species co-occurrence network analysis revealed a distinct modular structure (modularity=0.538 with 7 modules), with low overall connectivity (connectivity=0.1), where the keystone species (Veronica szechuanica and Circaeaster agrestis) served as critical hubs maintaining community connectivity. The Pearson correlation coefficient and Spearman rank correlation coefficient had significantly positive correlation with niche overlap index. Consequently, herbaceous plants in Picea asperata plantations exhibited low niche overlap indices, weak overall interspecific associations, with most species showing independent distribution patterns. The community had a distinct modular structure but low overall connectivity, implying that it was in the early stage of succession with unstable community structure. Therefore, priority in the management of Picea asperata plantation forests should be given to protecting keystone species and representative species of important functional groups to enhance community stability. Our results provide insights and theoretical references for the management of these plantations.

Key words: Picea asperata plantation forest, herbaceous plant, niche, species co-occurrence network