Characterizing How Community‐Level Plant Functional Traits Impact Soil Microbial Diversity

ABSTRACT Introduction Functional trait‐based approaches have been suggested for designing functionally diverse plant communities to influence soil microbial community structure and diversity. However, it remains unclear how species‐level plant functional traits (PFTs) and microbial associations translate to community‐level functional trait and soil microbiome composition. Methods Four plant mixtures comprising of three species each, were designed to exhibit contrasting (high vs. low) PFTs, or soil bacterial diversity based on species‐level PFTs and soil bacterial communities as reported in (Agarwal et al., 2025). The mixtures were grown in pots in a greenhouse for 10 weeks, at the end of which, the pots were destructively sampled to characterize community‐level above‐ and belowground PFTs and the associated soil bacterial and fungal communities. Results Our results showed that all mixtures varied in their overall PFT composition. Mixture designed for high PFT diversity had significantly higher above‐ and below‐ground biomass, root diameter, and tissue C and N concentrations than low PFT diversity treatment. While mixtures with the greatest divergence in overall PFTs composition harbored distinct soil microbial communities, mixtures specifically designed to differ in their associated soil bacterial communities did not. We also did not identify any specific PFT(s) measured in this study that significantly related to the differences in the soil microbiome. Conclusions Together, these findings demonstrate that species‐level trait data can be used to assemble plant mixtures with contrasting community‐level functional trait composition and distinct soil microbial communities. Overall community‐level PFT composition was more influential than individual traits in shaping soil microbiomes. This highlights the potential of PFT‐based approaches for designing functionally diverse plant mixtures, such as cover crops, that influence the soil microbial assembly in agroecosystems. Future research should evaluate if microbial shifts associated with contrasting PFT composition translate into measurable changes in soil health and ecosystem services under field conditions.