Conclusions

Our meta-analysis provides comprehensive evidence that plant diversity increases have a positive effect on multiple carbon and nitrogen processes in grasslands. We show that the effects of plant diversity on carbon and nitrogen cycles are enhanced in field experiments relative to greenhouse studies, and that the effects increase with experimental duration. Prediction models based on the field experiments showed soil carbon and nitrogen release in grasslands following plant diversity loss was faster with time, which indicate that global warming and forage production shortage might be exacerbate with continuous plant diversity loss.