Chinese Torreya Agroforestry Alters the Rhizosphere Soil Bacterial Communities and Potential Functions

The agroforestry practice has been regarded as a practical land-use selection to improve the Torreya grandis cv. Merrillii plantation management benefits. However, the relative report about the variation of rhizosphere soil bacterial communities and the potential functions under T. grandis-based agroforestry systems is currently limited. In the present study, we investigated the variation of soil bacterial communities and potential functions under the T. grandis-based agroforestry systems (T. grandis intercropping with Polygonatum sibiricum, PT; T. grandis silvopasture with goose, GT), using the Illumina MiSeq platform conjoined with Functional Annotation of Prokaryotic Taxa (FAPROTAX) annotation. The findings indicated that both silvopasture and intercropping significantly increased soil pH, total nitrogen (TN), available nitrogen (NH4+-N and NO3?-N), and total potassium (K) in comparison to the monoculture. According to the relative abundances of bacterial communities in T. grandis rhizosphere, Proteobacteria, Actinobacteria, Acidobacteria, and Planctomycetes were the dominant phyla. The intercropping and silvopasture showed a significant increase in phyla Chloroflexi and Verrucomicrobia and a decrease in phyla Proteobacteria and Rokubacteria. Besides, the intercropping significantly increased Actinobacteria compared to the monoculture. The result indicated that the different agroforestry systems formed distinct bacterial community structures. The bacterial functional structures shifted from nitrogen-utilizing bacteria to carbon-utilizing bacteria under silvopasture and intercropping. The soil available N (NH4+-N and NO3--N), pH, and TN were the most critical variables that impact the bacterial community and functional structures. These findings demonstrate that the bacterial community and potential function structures shift significantly under the agroforestry systems, reflecting the shift in the soil ecosystems caused by the plant soil-microorganism interaction. Our findings provide valuable information for understanding the response of bacteria to land-use changes and emphasize the influence of T. grandis-based agroforestry systems on soil bacteria.