The study investigates the relationship between plant diversity and soil carbon storage, using data from the Jena Experiment, a long-term grassland biodiversity experiment. The results show that higher plant diversity increases rhizosphere carbon inputs into the microbial community, leading to increased microbial activity and carbon storage. The increased carbon storage is primarily due to the accumulation of recently fixed carbon in high-diversity plots, while the decomposition rate of existing carbon is less affected by plant diversity. The study suggests that elevated carbon storage at high plant diversity is directly linked to the soil microbial community, indicating that the increase in carbon storage is mainly limited by the integration of new carbon into soil rather than the decomposition of existing soil carbon. The findings highlight the importance of plant diversity and its effects on soil microorganisms for ecosystem carbon storage, challenging previous views that underestimated the influence of soil microorganisms on soil carbon storage.The study investigates the relationship between plant diversity and soil carbon storage, using data from the Jena Experiment, a long-term grassland biodiversity experiment. The results show that higher plant diversity increases rhizosphere carbon inputs into the microbial community, leading to increased microbial activity and carbon storage. The increased carbon storage is primarily due to the accumulation of recently fixed carbon in high-diversity plots, while the decomposition rate of existing carbon is less affected by plant diversity. The study suggests that elevated carbon storage at high plant diversity is directly linked to the soil microbial community, indicating that the increase in carbon storage is mainly limited by the integration of new carbon into soil rather than the decomposition of existing soil carbon. The findings highlight the importance of plant diversity and its effects on soil microorganisms for ecosystem carbon storage, challenging previous views that underestimated the influence of soil microorganisms on soil carbon storage.