An Invasive Plant Species Decreases Native Plant Reproductive Success

Abstract

Invasive plants may have negative, positive, or neutral effects on the reproductive success of native plant species. In this study, I investigated the impact of the rhizomatous invasive species Securigera varia (Fabaceae; crown vetch; synonym: Coronilla varia) on the reproductive success of the native prairie species Tradescantia ohiensis (Commelinaceae; Ohio spiderwort). In particular, I examined how T. ohiensis plant height, fruit set, seed set, and stigma pollen load differed inside or at the edge of crown vetch patches and within native prairie not invaded by crown vetch. A significant reduction in reproductive success and pollen deposition was detected among T. ohiensis plants in the interior of a crown vetch patch compared to those at the edge of a crown vetch patch. These, in turn, had lower reproductive success and pollen deposition than plants in the native prairie areas. Also, T. ohiensis plants were taller inside crown vetch patches. The results of this study suggest that rhizomatous invasive species such as Securigera varia can have direct and indirect impacts on the reproductive success of native species.