The study investigates the relationship between fungal-bacterial diversity and microbiome complexity in soil ecosystems and their impact on ecosystem functioning. By manipulating soil microbiome diversity in experimental grassland ecosystems, the researchers found that higher diversity and more complex microbial networks positively influenced multiple ecosystem functions related to nutrient cycling, such as multifunctionality. Microcosms with poorly developed microbial networks and reduced microbial richness showed lower multifunctionality due to fewer taxa supporting the same function and reduced diversity of taxa supporting different functions. Different microbial taxa explained different ecosystem functions, highlighting the importance of functional diversity within microbial communities. The findings suggest that maintaining complex ecological associations belowground is crucial for enhancing ecosystem performance and that the extinction of these associations can impair ecosystem functioning. The study also emphasizes the significance of considering both fungal and bacterial communities to better understand the impact of microbial communities on ecosystem functions.The study investigates the relationship between fungal-bacterial diversity and microbiome complexity in soil ecosystems and their impact on ecosystem functioning. By manipulating soil microbiome diversity in experimental grassland ecosystems, the researchers found that higher diversity and more complex microbial networks positively influenced multiple ecosystem functions related to nutrient cycling, such as multifunctionality. Microcosms with poorly developed microbial networks and reduced microbial richness showed lower multifunctionality due to fewer taxa supporting the same function and reduced diversity of taxa supporting different functions. Different microbial taxa explained different ecosystem functions, highlighting the importance of functional diversity within microbial communities. The findings suggest that maintaining complex ecological associations belowground is crucial for enhancing ecosystem performance and that the extinction of these associations can impair ecosystem functioning. The study also emphasizes the significance of considering both fungal and bacterial communities to better understand the impact of microbial communities on ecosystem functions.