in

Root traits and mycorrhizal fungi mediate reactive N and warming impacts on soil organic carbon


Abstract

Plant roots and arbuscular mycorrhizal fungi (AMF) form a ubiquitous symbiosis in terrestrial ecosystems and critically affect soil organic carbon (SOC) dynamics. However, how roots and AMF mediate the impact of reactive nitrogen (Nr) and climate warming on SOC remains unclear. Using a multi-year Nr addition and simulated warming experiment in a semi-arid grassland, we show that Nr input and warming alter SOC by reshaping plant communities and inducing multidimensional tradeoffs among fine-root traits and AMF communities. Stable isotope (13C) tracing revealed that Nr- and warming-induced changes in roots and AMF reduced C input belowground, and mineral-associated organic C and microbial necromass in soil, while stimulating organic C decomposition. Nr input also increased soil N:P ratios and shifted AMF communities toward taxa with finer extraradical hyphae, weakening SOC protection. Together, these findings highlight root-AMF interactions as critical regulators and improve predictions of long-term SOC dynamics under future climate change.

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Data availability

The data that support the findings of this study are available at https://doi.org/10.6084/m9.figshare.23664696.

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Acknowledgements

We thank Jiuxin Guo, Fanglong Su, Fuwei Wang, Qilai Yang, Juanjuan Zhang, Yanan Wei, Shijie Li, Luyao Zhou, and Hui Guo for their assistance in field experimental maintenance. We also thank the Ningxia Yunwu Mountains Grassland Natural Reserve Administration for providing logistical support. This work was supported by the National Natural Science Foundation of China (32371626 (Y.Q.), 32001140 (Y.Q.) and 32171553 (Yi. Z.)), the Natural Science Foundation of Jiangsu Province (BK20240193 (Y.Q.)), and Fundamental Research Funds for the Central Universities (RENCAI2025013 (S.H.)).

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S.H., Y.Q., Yi. Z., and Y.W. conceived this work, established and maintained the Nr addition and temperature manipulation experiment. Y.Q. and S.H. designed the two independent 13C isotope tracing experiments. Y.Q., Yunfeng Z., B.W., Yexin Z., X.X., K.Z., T.H., K.Q., C.Y., Z.L., Liang G., X.C., and T.B. performed field and lab work. Y.Q., X.W., Lijin G., S.W., and H.C. conducted bioinformatic and statistical analyses. Y.Q. and S.H. wrote the original manuscript. C.G., R.T., A.W., K.G., W.Z., and L.L. reviewed and edited the final manuscript.

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Yi Zhang or Shuijin Hu.

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Qiu, Y., Zhao, Y., Wang, B. et al. Root traits and mycorrhizal fungi mediate reactive N and warming impacts on soil organic carbon.
Nat Commun (2026). https://doi.org/10.1038/s41467-026-69301-7

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