Dominant species identity regulates invasibility of old‐field plant communities

Dominant species are known to exert strong influence over community dynamics, although little work has addressed how they affect invasibility. In this study, we examined whether dominant species identity and abundance affected invasibility of old‐field plant communities. To quantify invasibility, we added seeds of 19 plant species into plots dominated by one of four different herbaceous perennial species ( Andropogon virginicus , Bromus inermis , Centaurea maculosa , or Solidago canadensis ) . We found that, independent of species richness and abiotic variables, plots dominated by Andropogon were the least invasible, while Bromus and Centaurea plots had the highest invasibility. We examined several potential mechanisms by which these dominant species might influence invasibility, and found invasion to increase with decreasing litter biomass and increasing community species richness. The abundance of the dominant species was not a significant predictor of invasion. These results indicate that dominant species identity plays an important role in determining invasibility of plant communities, though exact mechanisms underlying these effects still need to be explored.