The coupling of carbon cycle and nitrogen cycle drives food web structure and biogeochemistry of an ecosystem. However, across precipitation gradients, we have found examples of consistent N pool sizes above- and belowground and a shift to a greater proportion of belowground N in drier sites. We suggest that precipitation gradients do potentially decouple the C and N pool, but the exact nature of the decoupling depends on the dominant species’ capacity for intraspecific variation.