Plant-soil biota interactions explain shifts in plant community composition under global change

1. Plant-soil biota interactions play a crucial role in the assembly of plant communities and the maintenance of plant species diversity. However, few studies have tested how the effect of soil biota on plant species and communities depends on environmental context and whether shifts in plant community composition caused by environmental change are associated with variation in plant-soil biota interactions. 2. We combined a field experiment in a Tibetan alpine meadow and a greenhouse experiment with factorial combinations of nitrogen (N) enrichment and warming to examine the role of plant-soil biota interactions in plant community dynamics. 3. The results showed that plant relative abundances were negatively correlated with the net effects of soil biota on plant growth but only under ambient field conditions. Warming and N enrichment alleviated the negative soil biota effects in the greenhouse, and changed plant community composition and reduced species diversity in the field. Importantly, changes in soil biota effects on plant growth were positively correlated with changes in plant relative abundances caused by warming and N enrichment in field. In a parallel field experiment, the diversity of mycorrhizal fungi increased while the diversity of fungal pathogens remained unchanged under warming and N enrichment, indicating that soil biodiversity may play a critical role in plant responses to environmental change. 4. This study empirically demonstrates that altered plant-soil biota interactions explain shifts in plant community composition under global change, providing new insights into the mechanisms of diversity loss in a changing world.