Salt marsh vegetation recovery at salt hay farm wetland restoration sites on Delaware Bay

Public Service Enterprise Group's (PSEG) Estuary Enhancement Program (EEP) restored normal daily tidal inundation and drainage to three previously diked farm sites totaling 1780 ha during the period 1996-1998 along the shoreline of the Delaware Estuary in New Jersey, USA. Normal tidal exchange was either prevented or altered by the construction of dikes and water control structures that were used to promote the growth of high marsh “salt hay” species, such as salt meadow cordgrass (Spartina patens) and salt grass (Distichlis spicata) at elevations below mean high tide. These elevations would normally support low marsh species, such as smooth cordgrass (Spartina alterniflora). Prior to restoration these sites were either un-vegetated due to excessive ponding associated with poor drainage or vegetated with “salt hay” species as well as common reed (Phragmites australis). Extensive S. alterniflora marshes occur in the vicinity of each site at similar elevations and these marshes were relied on as the source of seed for the re-establishment of S. alterniflora on the restoration sites; thus, no other planting or seeding was implemented to initiate re-vegetation. Vegetation coverage at the restoration sites as well as a naturally restored reference marsh was determined during 1996-2003 utilizing geo-referenced remote sensing data and geographic information system (GIS) analyses. Coverage by S. alterniflora or other desirable low marsh vegetation exceeded that required by New Jersey authorities to meet the restoration goal at two sites 8 years ahead of the anticipated 12-year period and re-vegetation of the third site is expected to meet its goal within the established 12-year period. Annual vegetation coverage data have been integral components of an adaptive management program utilized by PSEG to manage the restoration process at each of the sites.