Abstract
Questions: Is it possible to predict the composition of local plant assemblages? Trait-based approaches have offered some promise, especially in cases where deterministic processes such as environmental filtering and niche differentiation shape communities. In this study, we asked how much intraspecific variation contributes to trait distributions within and among plant communities, and whether trait distributions resulting from environmental filtering and niche differentiation can predict accurately the relative species abundances of montane plant species in local communities. Location: West Elk Mountains, Colorado, USA. Methods: We collected functional trait, species composition and environmental data from 14 sites along a broad climate gradient in Colorado, USA, ranging in elevation from 2480 to 3560 m. We partitioned the variation within and among sites into intraspecific and interspecific components, and compared the results to values from a recent global meta-analysis, which examined intraspecific trait variability patterns. We also used these data to parameterize statistical models that have been shown to reproduce patterns associated with the processes of environmental filtering and niche differentiation. We fit two models to the data, one assuming that niche differentiation is invariant among sites, and another assuming that niche differentiation varies among sites. Results: We found that the trait-based models were worse at predicting species relative abundances in local communities than a null model assuming equal abundances of all species. One plausible explanation for the poor performance of the models is that intraspecific variation in functional traits, which in our system was higher than the global averages documented in the meta-analysis, swamped the effects of interspecific variation in functional traits along the climatic gradient. In particular, almost all variation in root traits was within rather than among species, even among sites. Conclusion: Our results suggest that a greater focus be placed on measuring intraspecific trait variability and determining its consequences for community assembly and ecosystem properties.
Original language | English (US) |
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Pages (from-to) | 1070-1081 |
Number of pages | 12 |
Journal | Journal of Vegetation Science |
Volume | 28 |
Issue number | 5 |
DOIs | |
State | Published - Sep 2017 |
Externally published | Yes |
Bibliographical note
Funding Information:The authors would like to acknowledge colleagues who gave feedback on this manuscript and the staff of Rocky Mountain Biological Laboratory (RMBL) for their hard work in facilitating all kinds of scientific work. This work was supported by graduate assistantships at the Department of Ecology and Evolutionary Biology, University of Tennessee (Q.D.R., J.A.H.), graduate fellowships from RMBL: the Dr. Jean Langenheim Fellowship (Q.D.R.), the Dr. Lee R. G. Snyder Memorial Fellowship (J.A.H.) and the Fran Hunter Fellowship (J.A.H.), and a Semper Ardens grant from the Carlsberg Foundation (N.J.S.). Q.D.R. and J.A.H. collected the data, Q.D.R. performed the analyses and wrote the manuscript, and all authors assisted in revising the manuscript.
Publisher Copyright:
© 2017 International Association for Vegetation Science
Keywords
- Community model
- Functional trait
- Meadow
- Montane
- Niche
- Plant
- Sub-alpine
- Traitspace