Non-monotonic and distinct temperature responses of soil microbial functional groups of different origins and in different soils

Abstract

The fate of soil carbon (C) under climatic warming predominantly depends on temperature sensitivity of soil microbial functioning, but it is poorly understood. Using temporal measurements of soil respiration in an incubation experiment with cross-inoculation of microbial communities to contrasting soils, we constrained a microbial-explicit C model to infer temperature responses of two general microbial functional groups: fast-growing r- vs slow-growing K-strategists. We found that the two groups exhibit distinct, non-monotonic temperature responses. Both historical environment, under which the microbial communities were originated, and current environment, under which the microbial communities are colonized/adapted, significantly shape the temperature responses of the two groups. Our findings highlight the importance of combined effects of historical and current environment on microbial decomposition for regulating soil C dynamics under warming. We suggest that distinct, non-monotonic temperature responses of microbial functional groups may cause pronounced feedbacks between soil C dynamics and warming depending on climate-soil-microbe interactions.