The experiment was conducted in 34 outdoor mesocosms (numbered from 1 through 34), 568 L Rubbermaid® tubs with a surface planting area of 1.15 m2 by 0.64 m deep, which sat aboveground in Ahn Wetland Mesocosm Research Compound on George Mason University's Fairfax campus (Fig. 1). Mesocosms were bottom-filled with 20 cm layers of locally-quarried rock and sand, and topped with 30 cm of locally-produced garden-quality topsoil known to have been used in the creation of Virginia wetland mitigation wetlands. Water levels were determined by precipitation events but were periodically supplemented with de-chlorinated tap water to maintain a minimum depth of 5 cm.