Plant community diversity supports soil microbial community complexity

Because plants and arbuscular mycorrhizal (AM) fungi form intimate associations, their diversity and functioning are thought to be inherently linked to plant-soil feedbacks. Yet we know very little about how AM fungi contribute to microbial interactions within the rhizosphere microbiome. In this study, we observed soil microbial community structure and coexistence network interactions across an experimental plant diversity gradient (low, medium, high) to understand the relationship between plant diversity and soil microbial taxa (in terms of its composition and coexistence networks). We found that plant diversity differed from soil microbial diversity based on soil microbial taxonomic group. Additionally, we noted that soil bacteria mirror plant diversity while AM fungal and non-AM fungal community diversities were independent from plant diversity. Our network analyses revealed that microbial communities associated with low plant diversity are dominated by bacteria and have more negative, or competitive interactions. However, coexistence networks show that interactions between non-AM fungi, AM fungi and bacteria increase in complexity with higher levels of plant diversity.