Academic-conservation partnership reveals trade-offs in treatment method and frequency needed to restore invaded floodplain

Invasive species disrupt native ecosystems by restructuring communities and altering ecosystem functions. To restore invaded plant communities, conservation practitioners eradicate invasive species, and re-establish natives, but a lack of empirical understanding about how restoration methods and herbicide application frequencies affect native and invasive species limits restoration effectiveness. We developed a partnership between scientists and practitioners to evaluate conservation practices used to remove invasive stiltgrass Microstegium vimineum in an ongoing restoration of a Piedmont floodplain forest in Georgia, U.S.A. We examined the effects of the practitioners' existing large-scale field application methods (herbicide, herbicide + native perennial seeding, herbicide + native perennial planting, and native perennial seeding) and frequencies (single, annual) using a smaller-scale, controlled experiment. Both herbicide and planting native perennial seedlings reduced the invasive stiltgrass, but the methods varied in their optimal application frequency. Specifically, herbicide required annual application to maintain its potency, but planting natives was most effective following a single herbicide application. Our work highlights the benefits of planting native perennials as an effective alternative to herbicide in restoration plans. Furthermore, unlike the broad-spectrum herbicide, native plantings did not reduce nearby non-target taxa density. Our study illustrates trade-offs in choosing restoration methods; although planting natives reduced the invasive species and provided associated benefits to the native community, this method took multiple growing seasons to establish and could require more up-front costs than herbicide alone.

Automated summary

The study found that planting native perennial plants is an effective restoration method that can replace herbicides without affecting the density of non-target species. It also showed that herbicide needs to be applied annually to maintain its efficacy, while planting native plants is most effective after a single herbicide application.