design: For each sample, total DNA from fresh soil (0.5 g) was extracted using an E.Z.N.A. Soil DNA kit (Omega, USA). The quantity and purity of DNA were determined using NanoDrop2000 microspectrophotometry (Thermo Fisher Scientific, USA). The V3-V4 region of bacterial 16S rRNA was amplified using the 341F (5- CCTAYGGGRBGCASCAG-3) and 806R (5- GGACTACNNGGGTATCTAAT-3) primers. The samples were sequenced on an Illumina MiSeq PE367 platform (Majorbio, China) in a paired-end manner.