Effects of intercropping systems of Phyllostachys edulis and Bletilla striata on soil bacterial community composition and function

Intercropping can result in changes in vegetation and soil properties, which could affect soil bacterial communities and functions that play critically important roles in the biogeochemical cycles in terrestrial ecosystems. Within the moso bamboo (Phyllostachys edulis)-based agroforestry systems, the bamboo-medicine model has received more and more attention regarding cultivation and ecology. The bamboo-medicine intercropping system is conducive to improving the utilization of bamboo forest land and space resources. However, the response mechanism of soil bacteria to changes in soil properties under the moso bamboo-rhizoma bletillae system is still unclear. In this experiment, a comparative study was conducted in three models including 4-year-old rhizoma bletillae (Bletilla striata) monoculture system (B4), 3- and 4-year moso bamboo-rhizoma bletillae intercropping systems (MB3 and MB4). The MB intercropping systems significantly reduced soil NO3−-N contents, and significantly altered soil microbial community structure with significant decrease of the relative abundance of Actinobacteria (the copiotrophic taxa) and increase of Chloroflexi (the oligotrophic taxa). The FAPROTAX database reflected that the functional group associated with C-cycling dominance decreased and N-cycling dominance increased during the transition from monoculture to intercropping system. The effect of intercropping on the soil microbial community structure was mainly due to the changes in soil moisture and NO3−-N. Our finding suggests that improvement of soil water and nitrogen regime can be effective measures for sustainable management of the bamboo-rhizoma bletillae intercropping system.