Microbial communities and their genetic repertoire mediate the decomposition of soil organic carbon pools in revegetation shrublands in a desert in northern China

Revegetation using xerophytic plants in drylands can alter soil microbial community diversity and composition; however, information about the microbial communities and their genetic repertoires that are involved in soil organic carbon (SOC) processes in drylands remain unclear. This study aimed to characterize soil microbial genes and their potential to mediate SOC decomposition in three revegetation shrublands (Artemisia ordosica, Salix psammophila and Caragana microphylla) in the Mu Us Desert of northern China using an SOC mineralization experiment and shotgun metagenome sequencing. Among the three shrublands, the S. psammophila shrubland had the highest cumulative CO2 emissions and highest rates of mineralization of the slow SOC pool. The mineralization rate of the slow SOC pool and the microbial taxonomic and functional composition displayed a significant correlation. Most C‐degradation genes were assigned to three bacterial phyla, Actinobacteria, Proteobacteria and Acidobacteria. The relative abundance of microbial functional genes involved in degrading recalcitrant C‐complexes was significantly higher in the S. psammophila shrubland, resulting in the slow accumulation of recalcitrant SOC. These results suggest that the microbial functional genes that regulate the decomposition of the SOC pool in dryland shrubland soils may be influenced by shrub species selection. These findings highlight the importance of understanding how microbial catabolic potential mediates the potential for SOC sequestration in different revegetation shrublands in drylands. Highlights We studied SOC mineralization and soil microbial functional genes in three revegetation shrublands. S. psammophila shrubland had the highest CO2 emissions and highest mineralization rates of the slow C pool. Slow SOC pool mineralization rate was related to microbial taxonomic and functional composition. Different dryland shrubs may mediate soil microbial functional genes that regulate SOC pool decomposition.