Abstract: Aims The rhizosphere microbial network characteristics profoundly influence various ecological processes including soil carbon turnover, nutrient cycling and plant growth. Mycorrhizal types and root traits are crucial factors that affect plant growth and below-ground nutrient acquisition strategies. However, it is currently unclear how the root characteristics of different mycorrhizal tree species affect the topological structure of the rhizosphere microbial network. Methods This study focused on the secondary forest and investigated the root traits and rhizosphere soil microorganisms of five arbuscular mycorrhizal(AM) tree species and seven ectomycorrhizal(EcM) tree species to explore the impact and mechanisms of mycorrhizal types on root traits and rhizosphere microbial network characteristics. Important findings (1) Specific root length, root nitrogen, and root phosphorus content of AM tree species were all higher than those of EcM tree species, while root tissue density, root diameter and root nitrogen-to-phosphorus ratio showed no significant differences between the two mycorrhizal types. (2) The relative abundance of Rozellomycota in the rhizosphere of AM tree species is significantly higher than that of EcM tree species, while the relative abundance of Bacteroidota is significantly lower in AM tree species compared to EcM tree species. There is no significant difference in the diversity of rhizosphere microbial communities between different mycorrhizal type tree species. (3) The rhizosphere microbial network of EcM tree species is more complex, and the negative bacterial cohesion of EcM tree species are significantly stronger than AM tree species. (4) The specific root length of AM tree species and the root diameter and root nitrogen-to-phosphorus ratio of EcM tree species are identified as crucial factors predicting rhizosphere microbial communities. These findings suggest that the mycorrhizal type of tree species significantly influences root traits such as specific root length and nutrient content to regulate the relationship between root traits and rhizosphere microbial communities and network complexity.

Key words: mycorrhizal association types, root traits, stoichiometry, microbial co-occurrence network