Objective Teak (Tectona grandis) is one of the precious tree species in the tropics, it has a long growth cycle. Intercropping with medicinal plants is an effective way to achieve additional short-term benefits and to achieve the goal of “raising the short with the long.” Since soil microbial community plays an important role in soil health and quality, the purpose of this study was to investigate the effects of intercropping teak with medicinal plants on the structure and function of soil microbial community, and provide theoretical references for the scientific management and green development of teak plantations.

Method This study investigated the effects of intercropping Alpinia katsumadai with teak in a forest plantation. A non-intercropped teak forest was used as a control. Soil samples were collected from the rhizospheres of both treatments and analyzed for fungal community characteristics using high-throughput sequencing technology. The changes and differences in soil fungal communities under intercropping were analyzed based on diversity indices, community structure and composition, and co-occurrence networks.

Result The diversity of soil fungal communities in teak intercropped with A. katsumadai did not change significantly compared to non-intercropped forests. The diversity indices (Chao1, Shannon, Observed_species, and PD_whole_tree) did not differ significantly. However, the community structure was significantly different. Non-metric multidimensional scaling (NMDS) and principal component analysis (PCA) showed that the community composition of teak intercropped with A. katsumadai was clearly separated from that of non-intercropped forests. Linear discriminant analysis effect size (LEfSe) analysis showed that the most enriched taxa in the two treatments were also different. Soil fungal network structure in the intercropped treatment was more concentrated and complex (the number of network nodes and the proportion of positive edges increased, and the modularity index increased). Ascomycota and Basidiomycota were the central response taxa for soil fungal communities in intercropped and non-intercropped forests, respectively.

Conclusion Intercropping with A. katsumadai significantly influences the soil fungal community structure in teak plantations. Intercropping A. katsumadai enhances the network complexity and centrality of the rhizosphere fungal community in teak, forming a more compact soil microbial environment. The research results can provide theoretical guidance for teak plantation interplanting and improving productivity from the perspective of microorganisms.