Mycorrhizae-associated belowground economics mediate microbial life history strategy in temperate forests

The co-evolution of plant roots, mycorrhizal fungi, and soil saprotrophic microorganisms shapes underground resource acquisition strategies of plants. However, the knowledge of how mycorrhizal associations affect plant belowground economics strategy and rhizosphere microbial community is not well established. Here we sampled leaves, roots and rhizosphere soils from five arbuscular mycorrhizal (AM) and seven ectomycorrhizal (EcM) tree species in a mixed temperate forest to explore the impacts of mycorrhizal associations on plant above- and belowground functional traits and rhizosphere microbial community composition. Mycorrhizal associations regulate soil fungal community composition, root functional traits, and economics space, but do not impact leaf traits. AM trees adopt a more aggressive strategy for nutrient acquirement with higher specific root length and root nitrogen concentration and support greater abundance of fungal community with nutrient acquirement strategy compared to EcM trees. The mycorrhizal-associated belowground economics spectrum, which ranges from conservative to aggressive nutrient acquisition strategies, was positively correlated with the relative abundance of the aggressive-strategy saprotrophic fungi (Ascomycota), while the conservative-strategy fungi (Rozellomycota) were associated with the opposite end of the spectrum. Our study highlights the importance of the mycorrhizal-associated belowground economics spectrum in mediating microbial functional groups and ecological strategies. Integrating mycorrhizal-mediated interactions into root economics framework could improve predictions of nutrient cycling and ecosystem functioning in temperate forests.