Rye cover crops limit alliaria petiolata growth and promote prairie restoration

Abstract

Alliaria petiolata (garlic mustard) is a non-native invasive species that invades intact, high-quality native ecosystems, outcompeting and extirpating native plants. Important questions in ecology and applied restoration are (1) How does A. petiolata affect plant species richness? and (2) How can A. petiolata be suppressed when attempting to restore native vegetation to a degraded site? We investigated the relationships between A. petiolata and plant species richness and tested the efficacy of two different cover crops, annual rye (Lolium multiflorum) and perennial rye (Lolium perenne), in inhibiting A. petiolata along an area of the Stokke Trail in Menomonie, Wisconsin. We hypothesized that A. petiolata would suppress plant species richness and that rye cover crops would be effective in suppressing A. petiolata. The percent cover of A. petiolata positively correlated with the species richness, possibly due to favorable conditions such as availability of nutrients, moisture, or sunlight. L. multiflorum did negatively affect the growth of first year A. petiolata; however, L. perenne did not. This suggests that competitive allelopathic annuals such as L. multiflorum could be used to suppress invasive species in other areas. Future research should investigate using aggressive annuals to outcompete invasive species.