Response of the rhizosphere microbial community to fine root and soil parameters following Robinia pseudoacacia L. afforestation

Rhizosphere microbial community structure and composition are affected by tree species, soil properties and fine root parameters. In this study, we investigated the changes in rhizosphere soil properties, fine root parameters and rhizosphere microbial community composition following Robinia pseudoacacia afforestation. Rhizosphere microorganisms were analyzed by high-throughput sequencing of the 16S rRNA gene and the internal transcribed spacer (ITS). Soil available phosphorus (AP) and fine root total phosphorus (RTP) were lower at the 25- and 35-Y sites than at the 5- and 15-Y sites, and fine root parameters could be inferred by soil AP, nitrate nitrogen (NO3-) and nitrogen: phosphorus (N:P). Rhizosphere microbial community composition clustered into the 5- and 15-Y group and the 25- and 35-Y group at the operational taxonomic unit (OTU) level. At genus level, 28.57% of the major bacterial genera (relative genera abundances >= 0.1%) and 18.33% of the major fungal genera exhibited significant differences. Rhizosphere soil and fine root properties explained 89.42% and 65.04% of the total variation in the major bacterial genera group, and 84.17% and 62.13% of the total variation in the major fungal genera group at the genus level, respectively. Soil AP and fine root TP are crucial for regulating rhizosphere soil microbial communities. Our results suggest that fine root and soil properties cooperatively affect rhizosphere microbial community composition in the root-soil system following Robinia afforestation.