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Evolutionary history resolves global organization of root functional traits

Nature volume 555, pages 9497 (01 March 2018) | Download Citation

  • An Erratum to this article was published on 04 April 2018

This article has been updated

Abstract

Plant roots have greatly diversified in form and function since the emergence of the first land plants1,2, but the global organization of functional traits in roots remains poorly understood3,4. Here we analyse a global dataset of 10 functionally important root traits in metabolically active first-order roots, collected from 369 species distributed across the natural plant communities of 7 biomes. Our results identify a high degree of organization of root traits across species and biomes, and reveal a pattern that differs from expectations based on previous studies5,6 of leaf traits. Root diameter exerts the strongest influence on root trait variation across plant species, growth forms and biomes. Our analysis suggests that plants have evolved thinner roots since they first emerged in land ecosystems, which has enabled them to markedly improve their efficiency of soil exploration per unit of carbon invested and to reduce their dependence on symbiotic mycorrhizal fungi. We also found that diversity in root morphological traits is greatest in the tropics, where plant diversity is highest and many ancestral phylogenetic groups are preserved. Diversity in root morphology declines sharply across the sequence of tropical, temperate and desert biomes, presumably owing to changes in resource supply caused by seasonally inhospitable abiotic conditions. Our results suggest that root traits have evolved along a spectrum bounded by two contrasting strategies of root life: an ancestral ‘conservative’ strategy in which plants with thick roots depend on symbiosis with mycorrhizal fungi for soil resources and a more-derived ‘opportunistic’ strategy in which thin roots enable plants to more efficiently leverage photosynthetic carbon for soil exploration. These findings imply that innovations of belowground traits have had an important role in preparing plants to colonize new habitats, and in generating biodiversity within and across biomes.

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Change history

  • 04 April 2018

    Please see accompanying Erratum (http://doi.org/10.1038/nature26163). Both authors D.G. and L.O.H. should have been listed as corresponding authors. This has been corrected online.

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Acknowledgements

We thank C. Ma, L. Li, Y. Yue, M. Liu, F. Ma, H. Li, D. Kong, B. Liu and K. Sun for collecting data; X. Liu and X. Deng for their assistance in field sampling; and all members of field research stations of the Chinese Academy of Sciences for their support. This study was funded by the Natural Science Foundation of China (NSFC Grants 31325006, 31530011, and 41571130041).

Author information

Author notes

    • Zeqing Ma
    • , Dali Guo
    •  & Lars O. Hedin

    These authors contributed equally to this work.

    • Dali Guo

    Deceased.

Affiliations

  1. Center for Forest Ecosystem Studies and Qianyanzhou Ecological Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China

    • Zeqing Ma
    • , Dali Guo
    • , Xingliang Xu
    •  & M. Luke McCormack
  2. Department of Ecology and Evolutionary Biology, Princeton University, New Jersey 08544, USA

    • Mingzhen Lu
    •  & Lars O. Hedin
  3. School of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PT, UK

    • Richard D. Bardgett
  4. Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, Pennsylvania 16802, USA

    • David M. Eissenstat
  5. Department of Plant and Microbial Biology, University of Minnesota, St Paul, Minnesota 55108, USA

    • M. Luke McCormack

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Contributions

Z.M., D.G. and L.O.H. developed the overall conceptual approach and analysis. Z.M. compiled and analysed the data, and X.X. provided nitrogen-uptake-rate data. R.D.B., D.M.E. and M.L.M. contributed to the formulation of research questions and interpretations. Z.M., D.G., M.L. and L.O.H. wrote the paper and all authors contributed to revisions.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Dali Guo or Lars O. Hedin.

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