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Data from: Shift in relative importance of complementarity and selection drives different effects of community evenness on richness-invasibility relationships

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Apr 11, 2025 version files 46.86 KB

Abstract

How biodiversity affects ecosystem functioning is context-dependent. Competition for different resources (e.g., light vs. soil water) may lead to differential effects of species richness and their relative abundance (evenness) on ecosystem functioning. We constructed experimental communities with different richness and evenness levels and let them be invaded by an exotic annual Conyza canadensis or not at both xeric and mesic sites. Community invasibility negatively correlated with species richness at both high and low evenness in the xeric site, but only at high evenness in the mesic site. In the xeric site, soil water competition determined community invasibility, and complementarity effects and changes in niche overlap between invader and native species were the main mechanism for diversity effect on invasibility. In contrast, in the mesic site, light competition determined community invasibility, and selection effects due to presence of competitively superior native species played key roles. Changing evenness altered height differences between competitively superior native species and invader, leading to the different richness-invasibility relationships. Therefore, aboveground vs. belowground resource competition drives different effects of community evenness on richness-invasibility relationships. Our study highlights the roles of resource competition and functional traits in regulating the effects of species diversity on community invasibility.