| The rapid proliferation of invasive Phragmites australis in New England has challenged resource managers to curb its expansion and reduce the loss of functional salt marsh. The interactive effects of sediment elevation, nutrient additions and community structure (plant competition and diversity) on the success and health of Phragmites were examined within a salt marsh in Hampton, NH. Along with four native halophytes, Phragmites was transplanted to vegetation plots (0.09 m2) comprising three community structure types (Phragmites alone, PA+1sp., PA+4spp.). Plots were arranged across elevation and nutrient enrichment gradients. Elevation and fertilization had no effect on Phragmites success, likely due to irregular tides and potential nutrient saturation, respectively. In contrast, interspecific competition significantly reduced Phragmites biomass, growth, density and survival, but not leaf fluorescence. High diversity plots (PA+4spp.) further reduced Phragmites success compared to PA+1sp. plots, indicating plant diversity enhanced resource competition, which should be considered in strategies to manage Phragmites. |
