Response of a Wetland Plant Community to Management of Phragmites Australis (Poaceae) in Southwestern Connecticut

Many conservation organizations remove invasive plants with herbicides; however, few quantify the outcomes of management on the invaded plant community (Martin and Blossey 2013). Phragmites australis (Cav.) Trin. ex Steud. is a perennial grass, native to Eurasia, that is now found throughout temperate regions of North America in fresh water, brackish, and salt marsh environments (Meyerson et al. 2009). Despite considerable interest in the effects of P. australis on native wetland ecosystems, relatively little information exists on the efficacy of different management strategies and the response of plant communities to the removal of P. australis, especially over multiple years (Hazelton et al. 2014; Martin and Blossey 2013). We examined the efficacy and effects of removing Phragmites australis from the perimeter of a 1-hectare pond at Highstead Preserve in southwestern Connecticut (41.327, –73.394) over a six-year period (2012–2017). Prior to the study, P. australis covered 30% of the shoreline around the pond and formed several small (, 100 m), dense patches and one relatively large patch (~1300 m). We used vegetation monitoring and three different herbicide (Rodeot [53.8% glyphosate]) application techniques to treat P. australis: (1) handwipe 25% solution (leaves and upper half of stem wiped via cotton work glove worn over 15 mil nitrile glove); (2) wand 25% solution (leaves and upper half of stem wiped with long-handled brush applicator); and (3) spray 2.3% solution (whole plant with backpack sprayer). Prior to herbicide treatment in 2012, we sampled the pondside vegetation by randomly placing 28 quadrats 1 m in patches invaded by P. australis. In each quadrat, we counted live stems of all vascular plant species with the exception of graminoids that grew in overlapping clumps (Farnsworth