Aims Soil microbes are key to myriad processes in terrestrial ecosystems. Elevated CO 2 represents a dominant driver of global climate change; however, it remains unclear to what extent elevated CO 2 impacts soil microbial communities at ecosystem and global scales. Here, we sought to address the following questions: (a) Do the compositions of microbial communities shift from K ‐ to r ‐strategists under elevated CO 2 ? (b) Wha...