Soil microbial interactions modulate the effect of Artemisia ordosica on herbaceous species in a desert ecosystem, northern China

Soil microbes are essential for enhancing the performance (i.e., recruitment and growth) of individual plants, thereby influencing the structure and diversity of plant communities. However, how soil microbes drive the plant interspecific interactions remains largely unexplored, particularly in harsh desert ecosystems. To address this knowledge gap, we examined the community composition and species interaction networks of soil bacteria using high-throughput 16S rRNA gene sequencing along a successional gradient of an Artemisia ordosica community in the Mu Us Desert, northern China. We also explored how A. ordosica affects the soil bacteria, especially keystone species, and herbaceous plants with community succession. Our main goal is to determine how soil bacteria regulate the interactions of A. ordosica with herbaceous plants. The results showed that soil bacterial community composition and main taxonomic groups were primarily influenced by the presence of A. ordosica along the successional gradient. The phylogenetic molecular ecological network analysis identified nine keystone species, with five species categorised as module hubs and four species as connectors. We found that the effects of A. ordosica on module hubs were highly correlated with its effects on soil nitrogen content and biomass of specific herbaceous plants, resulting in an increase of soil fertility and herbaceous under the shrub. These results indicated that soil bacterial interactions might be a crucial driver affecting plant interspecific interactions. Although our results highlighted the importance of bidirectional interactions between plants and soil microbes from the perspective of biotic interactions, their contribution to plant community succession still needs further confirmation through more robust evidence from future studies. However, overall our findings advanced the current understanding of plant-soil interactions on the processes of ecological restoration and desertification reversion, especially in stressful desert ecosystems. [Display omitted] •How soil bacteria influence plant species interactions was assessed.•Artemisia ordosica influenced soil bacteria composition and taxonomic groups.•Keystone microbial species were more abundant under A. ordosica.•These keystone species strengthened soil bacteria interactions.•The strengthened soil bacteria interactions may regulate plant-plant interactions.