High Reinvasion Potential of Phragmites australis in a Delaware River (USA) Tidal Freshwater Marsh Following Chemical Treatment: the Role of the Seedbank

摘要

Management of the invasive Phragmites australis haplotype has focused on controlling its abundance in wetlands where it reduces biodiversity. However, little information is available on establishment of native communities and reinvasion by seed following removal using herbicides. The potential for reinvasion and development of native vegetation were evaluated using a seedbank assay and a vegetation survey along gradients from the channel edge to the marsh interior (0, 5 and 20 m distance) in three tidal freshwater marsh sites - Natural, treatment 6 months prior (Treated), and untreated (Phragmites). Recolonization potential from the seedbank was high with 18,500 seedlings m(-2) in Treated samples. Richness and density of native species were low in the interior of Treated and Phragmites sites as compared to the Natural marsh. Few species were present in Treated site vegetation 11 months following treatment where P. australis litter comprised a large proportion of the cover. Results indicate that planting native vegetation to outcompete P. australis seedlings and total removal of P. australis to cut off the seed supply may be necessary for successful longer-term restoration and establishment of native species.