Abstract
Mycorrhizal fungi are essential to the establishment of the vast majority of plant species but are often conceptualized with contradictory roles in plant community assembly. On the one hand, host-specific mycorrhizal fungi may allow a plant to be competitively dominant by enhancing growth. On the other hand, host-specific mycorrhizal fungi with different functional capabilities may increase nutrient niche partitioning, allowing plant species to coexist. Here, to resolve the balance of these two contradictory forces, we used a controlled greenhouse study to manipulate the presence of two main types of mycorrhizal fungus, ectomycorrhizal fungi and arbuscular mycorrhizal fungi, and used a range of conspecific and heterospecific competitor densities to investigate the role of mycorrhizal fungi in plant competition and coexistence. We find that the presence of arbuscular mycorrhizal fungi equalizes fitness differences between plants and stabilizes competition to create conditions for host species coexistence. Our results show how below-ground mutualisms can shift outcomes of plant competition and that a holistic view of plant communities that incorporates their mycorrhizal partners is important in predicting plant community dynamics.
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Data availability
All data are available via the Dryad Digital Repository at https://doi.org/10.5061/dryad.rxwdbrvjb.
Code availability
All code for analysis is available via Github at https://github.com/ClaireWilling/MycorrhizaCoexist.git.
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Acknowledgements
We thank K. N. Chin and J. M. M. Ferré for their help in planting seedlings for this experiment. Additionally, we thank K. N. Chin for her help in creating art for this manuscript. We thank L. D. L Anderegg for his input on the study design and feedback on early versions of this manuscript. K.G.P. is a Canadian Institute for Advanced Research (CIFAR) Fellow in the programme Fungal Kingdom: Threats and Opportunities and is supported by a United States Department of Energy (DOE) Award DE-SC0023661. C.E.W., J.J.Y., A.M.C. and K.G.P were all supported by the United States National Science Foundation (NSF) Faculty Early Career (CAREER) Award 1845544 for this work, which was awarded to K.G.P.
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C.E.W. and K.G.P. planned and designed the research. C.E.W. and K.G.P. conducted field work. C.E.W., J.J.Y. and A.M.C. conducted the laboratory work. C.E.W. analysed and interpreted the data with critical contributions from J.W., J.J.Y., A.M.C. and K.G.P. The manuscript was written by C.E.W. and all co-authors provided important contributions and critical revisions. All authors approve of the final version of this manuscript.
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Willing, C.E., Wan, J., Yeam, J.J. et al. Arbuscular mycorrhizal fungi equalize differences in plant fitness and facilitate plant species coexistence through niche differentiation. Nat Ecol Evol (2024). https://doi.org/10.1038/s41559-024-02526-1
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DOI: https://doi.org/10.1038/s41559-024-02526-1