Soil function-microbial diversity relationship is impacted by plant functional groups under climate change

Understanding the interactions between plant and soil microbial diversity is crucial for predicting ecosystem responses to environmental changes. While the individual roles of plant and microbial diversity in driving ecosystem functions have been widely investigated, their interplay especially under stress conditions remains largely underexplored. This study investigated how interactions between plant and microbial diversity affect key soil functions during and after drought. We simultaneously manipulated soil microbial diversity and plant species richness, while also considering the influence of plant functional groups (PFGs), to investigate their interactions and effects on key soil functions. Our results revealed independent and interactive effects of plant and microbial diversity in shaping soil functions. Microbial diversity loss significantly altered microbial community structure and impacted microbially-driven soil N and P pools and processes such as N-mineralization. These effects were modulated by plant species richness and varied across different PFGs. The relative influence of plant and microbial diversity on soil functions was context-dependent. Microbial diversity showed stronger effects on specific functions, such as phosphatase activity, and under the drought condition. Plant diversity, particularly through PFGs (e.g. legumes), played an independent role in shaping the microbial-driven soil functions. These findings advance mechanistic insights and highlight the importance of considering both above- and belowground biodiversity, along with their interactions, in shaping soil functions and ecosystem resilience, particularly under environmental stress. Further, it emphasizes the need to explicitly consider PFGs, along with above- and belowground biodiversity, as a strategy for preserving essential belowground functions in the face of ongoing environmental changes.