Cross-stressor resilience of soil microbial growth and carbon metabolism under climate change.

The microbial ability to recover metabolism after perturbation events ensures ecosystem functional stability in a changing climate, where multiple climatic stressors increasingly occur in sequential and seasonally cyclic patterns. While prior exposure to a specific stress can enhance microbial resilience to that stress, whether this resilience extends to different stressors remains largely unexplored. Here, we investigated cross-stressor resilience of microbial communities by testing how prior exposure to one type of perturbation (frost or drought) affects microbial resilience to subsequent perturbations of either type in soil systems. We found that prior exposure to drought or frost enhanced the resilience of microbial growth to subsequent perturbations of either type and enabled the maintenance of higher microbial carbon use efficiency. It is likely that this cross-stressor resilience arose because frost and drought both can exert stress on microbes via effects on water potential. This suggests that induced microbial perturbation resilience can extend beyond the stressor they originally were exposed to, indicating that ecological memory transcends the original stressor. Repeated perturbation cycles did not confer additional resilience beyond a single event, indicating that a single perturbation could shape the microbial community's perturbation resilience. We also identified the lag phase as a critical period defining microbial perturbation resilience. Our findings demonstrate a broader adaptive capability within microbial communities under climate change so far overlooked, where winter frost could impact summer drought resilience and vice versa, creating a need to consider selective environmental drivers across seasons.