Diversity-triggered bottom-up trophic interactions impair key soil functions under lindane pollution stress

A growing amount of evidence suggests that microbial diversity loss may have negative effects on soil ecosystem function. However, less attention has been paid to the determinants of the relationship between community diversity and soil functioning under pollution stress. Here we manipulated microbial diversity to observe how biotic and abiotic factors influenced soil multi-functions (e.g. lindane degradation, soil respiration and nutrient cycling). Results showed that protist community was more sensitive to dilution, pollution stress, and sodium acetate addition than bacterial and fungal community. Acetate addition accelerated the lindane removal. Any declines in microbial diversity reduced the specialized soil processes (NO₃-N production, and N₂O flux), but increased soil respiration rate. Dilution led to a significant increase in consumers-bacterial and fungi-bacterial interaction as evidenced by co-occurrence network, which possibly played roles in maintaining microbiome stability and resilience. Interestingly, pollution stress and resource availability weaken the relationship between microbial diversity and soil functions through the bottom-up trophic interaction and environmental preference of soil microbiome. Overall, this work provides experimental evidence that loss in microbial diversity, accompanied with changes in trophic interactions mediated biotic and abiotic factors, could have important consequences for specialized soil functioning in farmland ecosystems.