The dominant plant species Solidago canadensis structures multiple trophic levels in an old‐field ecosystem

Dominant plant species are locally abundant and have large impacts on ecological communities via a variety of mechanisms. However, few studies have evaluated the influence of a dominant plant species both within and among trophic levels and on key ecosystem functions such as productivity. In this study, we evaluated the effect of the dominant plant species Solidago canadensis on plant and arthropod communities in an old‐field ecosystem in southeastern Michigan. We found that S. canadensis negatively correlated with the richness and combined biomass of all other plant species in the community, likely by reducing light availability. In turn, less biomass of all other plant species led to lower arthropod abundance. Specifically, detritivore and predator arthropod abundance was lower with less biomass of all plant species excluding S. canadensis, but herbivore and omnivore abundance was unaffected. Our results highlight the significant role of dominant plants in determining plant diversity and ecosystem function, and further suggest that the effect of a dominant plant species on a community is observed at higher trophic levels.