Effects of chicken farming on soil properties and root-associated bacterial communities in a bamboo (Phyllostachys praecox) ecosystem

Abstract

Bamboo-chicken farming (BCF), in which chickens are farmed in bamboo forests, is a common land-use type in China. However, little is known regarding the responses of soil bacterial communities to the introduction of BCF. In this study, we investigated and compared the bacterial communities in chicken gut, bulk soil, the rhizosphere, and roots, along with relevant soil properties, in a BCF area and a control area (a pure lei bamboo (Phyllostachys praecox) forest: PBF). The results showed that BCF significantly increased (p < 0.05) soil pH, organic carbon (SOC), total N, total P, alkali-hydrolysable N (AN), available K (AK), and available phosphorus (AP) and significantly decreased (p < 0.05) the soil C:N and C:P stoichiometry. BCF significantly altered the bacterial communities in soil and bamboo root systems. Bacterial composition changes associated with BCF were mostly related to C and N cycling, plant growth, and abiotic stress adaptation, such as an increase of Bacteroidetes, Flavobacterium, and Sphingomonas in bulk soil; Mizugakiibacter and Sphingomonas in rhizosphere soil; and Flavobacterium, Rhizobium, and Rhodomicrobium in root endophytes. A redundancy analysis (RDA) showed that all bacterial communities were significantly correlated with soil AN, AP, and TP, suggesting that N and P were the driving factors for bacterial composition and C cycle changes. The shared operational taxonomic units in the chicken gut–soil–bamboo root continuum indicated the microbial linkage among these components. Our results suggest that the microbial community and soil stoichiometry changes induced by chicken farming would alter bamboo ecosystem functions; the decreased overall stoichiometry and reduced bacterial richness (Chao 1 index) may indicate a high risk of nutrient and biodiversity loss.