Changes in the composition of soil bacterial and fungal communities after revegetation with Caragana microphylla in a desertified semiarid grassland

Revegetation with native leguminous shrub Caragana microphylla in the Horqin Sandy Land, China, has been reported to increase plant coverage and diversity, and ameliorate abiotic soil property. However, comprehensive investigation of soil microbial-community composition after revegetation in this area has been rarely conducted. In this study, DNA of sand dunes restored for a period of 12 and 30 years, and an unrestored sand dune (control), was extracted and sequenced using Illumina Miseq. The results indicated that revegetation of C. microphylla significantly altered soil microbial communities as reflected by the significantly different bacterial and fungal composition and fungal diversity between the restored dunes and the control; however, there was no significant difference in soil microbial composition between the dunes restored for different years. Specifically, microbial consortia that involved in a wide range of ecological function, including recalcitrant organic carbon decomposition, plant-microbe symbiosis and nitrogen fixation, were enriched on restored dunes particularly on the 30-year restored dune. The changes in soil microbial communities were significantly correlated with the content of soil organic carbon (SOC) and the proportions of labile and recalcitrant organic carbon in SOC, which may indicate a mutual-regulated ecological improvement between soil abiotic and biotic processes along sand dune restoration.