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Data from: Native plant traits and invasibility of restored communities: Importance of environmental context and trait hierarchies

Kimball, Sarah1; Nguyen, Monica2; Funk, Jennifer3; Vose, Greg1; Huxman, Travis1

Published Jul 11, 2024 on Dryad. https://doi.org/10.5061/dryad.gb5mkkwxn

Data files

Jul 11, 2024 version files 306.01 KB

Abstract

During community assembly, theory predicts trait convergence among species due to environmental filtering, and trait divergence due to biotic filtering. Learning how traits of non-native species enable them to overcome these filters informs the process of invasion. We manipulated mixtures of native plants in a large restoration project in Southern California that was initially dominated by non-native annual grasses and forbs but was restored to a mixture of native shrubs, grasses, and forbs.  We measured subsequent establishment and performance by three non-native species (Brassica nigra, Salsola tragus, and Sonchus oleraceus) on N- and S-facing slopes to investigate relationships between the abiotic environment, native community composition, and invasibility in the context of trait-driven ecological filters. We then evaluated which community metrics influenced invader performance and tested whether relationships between invader performance and community-weighted traits varied depending on slope aspect. Plots with slow-growing native shrubs contained less of the fast-growing invasive, Brassica nigra. Invasibility was greatest in native communities restored with native grass and on N-facing slopes. Traits of individual species indicated relatively greater biotic as compared to environmental filtering. For example, abundance of Phacelia cicutaria, a native annual with traits most like invasive Brassica nigra, was negatively correlated with abundance of that invasive. Several community-weighted trait metrics were also significantly related to invasibility, but the direction of the relationship varied depending on the specific functional trait, community-weighted trait measure (mean or dispersion), invader, and slope aspect. The native functional group that was more likely to prevent invasion by non-native annual species (native shrubs) was different from the single species that most prevented invasion (a native forb). In restoration planning, functional groups and trait values of individual species may point to different mixtures of native species that prevent invasion by specific non-natives, depending on priority effects. Understanding the priority effects and trait hierarchies that underly biotic filtering appears critical to interpreting community-weighted traits and their complexity of responses to environmental variation in space and time.