ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Functional Plant Ecology
The Primacy of Species Turnover over Intraspecific Variation in the Environmental Filtering of Understory Ferns
Provisionally accepted
- 1Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
- 2Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai, China
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Quantifying community-level trait shifts, driven by species turnover and intraspecific trait variation (ITV), is essential for understanding environmental filtering and elucidating community assembly and species coexistence. While well-studied in seed plants, the relative roles of these processes in ferns—a key component of forest understories—remain poorly understood. Here, we evaluated how topographic, soil, and overstory biotic factors influence the functional traits of understory fern communities at a local scale in a subtropical forest. We measured six key functional traits across 45 fern species in 121 plots of 10 m × 10 m. We found that trait-environment models based on species turnover alone (CWMfixed) had consistently higher explanatory power than models that included ITV (CWMspecific) (mean pseudo-R² = 0.56 vs. 0.23). Variance partitioning revealed that trait-environment relationships were primarily driven by the unique effects of environmental factors rather than their shared variance, identifying soil properties and overstory biotic structure as distinct, independent drivers of community functional composition (explaining 23.0% and 17.7% of variance for plant growth and resource-use strategies, respectively). Our results highlight two key insights: (1) the understory fern community responds to environmental filters primarily through species turnover (compositional shifts) rather than widespread intraspecific trait variation; (2) soil phosphorus and forest structure act as critical filters that together shape community-level functional traits of ferns.
Keywords: Community functional composition, Community-weighted mean (CWM), Environmental filtering, Forest understory, Intraspecific trait variation (ITV), species turnover
Received: 02 Jan 2026; Accepted: 10 Feb 2026.
Copyright: © 2026 Zhou, Zhang, Liu, Jiang, Zheng, Shen, Wang and Yang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Qingsong Yang
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