Large-Scale Chemical Control of Smooth Cordgrass (Spartina alterniflora) in Willapa Bay, WA: Towards Eradication and Ecological Restoration

The grass species Spartina alterniflora (smooth cordgrass) is an invasive ecosystem engineer with serious ecological consequences to intertidal mudflats and saltmarshes. The largest infestation in North America was in Willapa Bay, WA, where it occupied ∼3,600 solid ha, covering ∼27,000 ha of intertidal habitat. An extensive effort by land managers to eradicate S. alterniflora has been in place for over two decades. This article discusses (1) the success of the control and issues that will need to be resolved in order to achieve eradication; (2) post-control succession of affected tidelands to native marsh species, and (3) the impact that S. alterniflora removal has had on shorebird usage of affected tidelands. Nomenclature: Imazapyr; glyphosate; smooth cordgrass, Spartina alterniflora Loisel.