[Pollution Legacy Effect Alters the Response of Soil Ecological Functions to Water Limitation]

Long-term environmental pollution may have legacy effects on soil microbial communities and ecosystem functions they sustain. The contaminated areas may simultaneously experience other environmental stressors （e.g.， water limitation） in the context of global change. Although several studies have reported the effect of water limitation on microbial communities and their multiple functions， how the legacy effects of long-term pollution influence the response of soil microbial and ecological functions to water limitation remains unclear. A moisture gradient incubation experiment was conducted using agricultural soil with over 600-year contaminated history， and then several functional metrics were measured after incubation. The results showed that microbial respiration， carbon use efficiency， and multifunctionality of polluted soil significantly declined under water limitation compared to that in control soil. There was a significantly positive correlation between multifunctionality and soil moisture in polluted soil， and the overall functional stability of polluted soil was higher than that of control soil. Further hierarchical partitioning analysis showed that the multifunctionality of contaminated soil was mainly affected by soil moisture， microbial biomass carbon， and microbial biomass phosphorus， which were significantly correlated with multifunctionality. Furthermore， pollution legacy effects weakened the resistance of bacterial diversity to water limitation and altered microbial community structure. In conclusion， the pollution legacy effects weakened the resistance of bacterial community and soil functions （e.g.， microbial respiration， carbon use efficiency， and multifunctionality） to water limitation， but the overall functional stability of polluted soil was higher. These findings are significant for assessing potential responses of soil ecological functions in contaminated areas to future water limitation.