Rotation regimes lead to significant differences in soil macrofaunal biodiversity and trophic structure with the changed soil properties in a rice-based double cropping system

Crop production has negative effect on the biodiversity in farmlands because of less crop varieties and intensive soil disturbance. Macrofauna are important components of the belowground biodiversity, and contribute to the soil ecosystem functions and soil processes. The response of soil macrofauna to cropping pattern is crucial for understanding the soil ecological dynamics and biodiversity conservation. Herein, we established an experiment of rice (Oryza sativa L.)-based double cropping system in Jiangsu Province, China since 2016 to evaluate the effects of rotation regimes on soil properties and soil macrofauna communities. The rice-based double cropping system included rice–wheat (Triticum aestivum L.), rice-oilseed rape (Brassica campestris L.), rice-tiny vetch (Vicia hirsuta L.), rice-broad bean (Vicia faba L.), and rice-fallow. After 3-year rotations, soil macrofaunal biodiversity and trophic structure varied significantly with soil properties. The higher biodiversity indices were found in the tiny vetch (used as green manure in situ) and fallow fields. In addition, soil organic carbon (SOC), the main factor for shaping the soil environment and regulating the soil macrofaunal communities, was improved. While soil water content and pH were selected to predict each trophic richness and density in most of the optimal regression models, changes in soil macrofaunal communities should also be considered as comprehensive responses to the soil environments (food resources, microhabitats etc.) co-varying rotation regimes. Crop rotation with lower intensity of land use increased the complexity of soil macrofaunal trophic structure. Green manure fields or fallow after rice plantation promoted soil macrofaunal biodiversity in the rice-based cropping system.