Abstract
Understanding how biotic interactions shape forest communities along environmental gradients remains a central challenge in ecology as the mechanisms regulating plant species richness and abundance are highly variable. Here, we examine how mycorrhizal composition and species dominance jointly shape species richness and abundance across the tree, shrub, and herb layers. Species richness peaks at intermediate levels of mycorrhizal dominance, especially in the tree layer, supporting the mycorrhizal mixture hypothesis. In contrast, strong species dominance generally reduces species richness but increases abundance across all vegetation layers, consistent with the relaxation of conspecific negative density dependence. Canopy mycorrhizal composition exerts cross-layer effects on shrubs and herbs, with arbuscular mycorrhizal dominated canopies facilitating higher understory richness but lower abundance than ectomycorrhizal dominated canopies. Environmental gradients primarily influence forest communities indirectly by regulating the prevalence of mycorrhizal strategies and species dominance. We provide an alternative mechanism involving mycorrhizal symbiosis and interspecific competition that reconciles the divergent patterns of species richness and abundance observed in temperate and boreal forests.
Acknowledgements
We are grateful to Jiaxing Zu, Pengyi Zhang, and Pengchao Zhang for their help in treatment of climatic data. We sincerely thank the three anonymous referees for their thorough reviews, constructive comments, and overall positive feedback.
Funding
This study was funded by the National Key Research and Development Program of China (2022YFD2201300), the National Natural Science Foundation of China (32471625, 32171562, 32371651, 32301379), Youth Innovation Promotion Association of Chinese Academy of Sciences (2022193), Natural Science Foundation of Liaoning Province (2024-MSBA-87), Liaoning Provincial Central Guidance Fund for Local Science and Technology Development (Free Exploration Program-Basic Research, Provincial Outstanding Young Scholars Program, 2026040011-JH6/1011), Shenyang Special Program for Cultivating Young and Middle-Aged Scientific and Technological Innovation Talent (RC240577).
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Liu, B., Liang, Y., Chen, X. et al. Mycorrhizal composition and species dominance mediate forest plant richness and abundance responses to environmental gradients.
Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03964-4
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DOI: https://doi.org/10.1038/s43247-026-03964-4
Source: Ecology - nature.com
