USING SEDIMENT CORES TO INVESTIGATE THE HISTORY OF A PHRAGMITES-INVADED COASTAL WETLAND ON THE SHORE OF LONG ISLAND SOUND IN QUEENS, NY

Identifying the environmental history of a 6-acre parcel of invasive Phragmites australis-covered coastal land in Udalls Cove in Douglas Manor, Queens, NY is essential to planning the restoration of the site to a native species assemblage. Historical aerial photos show an open landscape for the site, but the exact nature of the vegetation and substrate are ambiguous. To determine what kind of environment existed on the parcel prior to invasion by Phragmites, transects were surveyed from the road bordering the site to the shoreline and six sediment cores were collected along the transects, along with salinity readings from the subsurface water. Elevation transects reveal a relatively level surface across the Phragmites-dominated area of the parcel, gently sloping down to a fringe of Spartina alterniflora marsh and estuarine mudflats. Preliminary analysis of the sediment cores reveals a 30 cm Phragmites rhizomal mat underlain by approximately 1.5 meters of grey clay interpenetrated with abundant plant material, overlying pebbly glacial outwash. Our preliminary conclusion is that the parcel supported a persistent coastal wetland prior to invasion by Phragmites, arising from a natural protective coastal barrier created by a migrating sandy spit. Ongoing analysis of the cores should allow us to determine the exact nature of the pre-Phragmites plant community, which will help inform the ecological restoration initiative undertaken by the Douglas Manor community.