Seminar: Guang Zhao

Increasing investigations highlight the role of microbial carbon use efficiency (CUE) in determining soil organic carbon (SOC) storage and persistence. However, the intrinsic link between CUE and SOC persistence remains unclear. Here, we analyzed soil organic matter (SOM) physicochemical composition and microbial traits in surface soils along an environmental gradient in conjunction with global-scale data. As aridity declines along this transect, SOC increases but its persistence based on radiocarbon age and SOM physicochemical composition declines. Soil microbial biomass, its CUE and turnover rate positively correlate with SOC, but did not lead to enhanced preservation of microbially-derived carbon in soils, suggesting decoupling of microbial necromass production from stabilization. We argue that microbial CUE may not effectively capture the SOC accumulation and loss due to the decoupled nature of microbial-derived carbon production from stabilization. Such process understanding will considerably enhance predictions of soil carbon feedbacks to climate change.