Linking soil bacterial biodiversity and soil carbon stability

Linking soil bacterial biodiversity and soil carbon stability Soil carbon (C) can be lost in response to fresh C inputs, a phenomenon observed for decades yet still not understood. Using dual-stable isotope probing, we show that changes in the diversity and composition of two functional bacterial groups mediate this “priming” effect. A single substrate pulse suppressed soil C loss and reduced bacterial diversity, whereas repeated substrate pulses stimulated soil C loss and the diversity, and also altered the composition of the soil bacterial community. This increased diversity response after repeated labile C amendments contrasts with resource competition theory, which might be explained by increased predation as evidenced by a decrease in 16S rRNA gene abundance. Our results suggest that the biodiversity and composition of the soil microbial community changes in concert with its functioning, with consequences for soil C stability.