Elevated carbon dioxide accelerates the spatial turnover of soil microbial communities

Although elevated CO₂ (eCO₂) significantly affects the α-diversity, composition, function, interaction and dynamics of soil microbial communities at the local scale, little is known about eCO₂ impacts on the geographic distribution of micro-organisms regionally or globally. Here, we examined the β-diversity of 110 soil microbial communities across six free air CO₂ enrichment (FACE) experimental sites using a high-throughput functional gene array. The β-diversity of soil microbial communities was significantly (P < 0.05) correlated with geographic distance under both CO₂ conditions, but declined significantly (P < 0.05) faster at eCO₂ with a slope of -0.0250 than at ambient CO₂ (aCO₂) with a slope of -0.0231 although it varied within each individual site, indicating that the spatial turnover rate of soil microbial communities was accelerated under eCO₂ at a larger geographic scale (e.g. regionally). Both distance and soil properties significantly (P < 0.05) contributed to the observed microbial β-diversity. This study provides new hypotheses for further understanding their assembly mechanisms that may be especially important as global CO₂ continues to increase.