Cumulative data package of surface elevation table and marker horizon data collected by the National Park Service at twenty national parks along the Atlantic seaboard.

The National Park Service (NPS), in response to the growing evidence and awareness of the effects of climate change on federal lands, determined that monitoring wetland elevation change is a top priority in Atlantic coastal parks. As a result, several NPS Inventory and Monitoring Division (IMD) Networks, in collaboration with colleagues from the U.S. Geological Survey (USGS) and The National Oceanic and Atmospheric Administration (NOAA), have developed a protocol for monitoring wetland elevation change and other processes important for determining the viability of wetland communities. These data consist of measurements made using the Surface Elevation Table (SET) and Marker Horizon techniques at five NPS Inventory and Monitoring Networks across the Atlantic seaboard: the Northeast Temperate Network (NETN), the Northeast Coastal and Barrier Network (NCBN), the National Capital Region Network (NCRN), the Southeast Coast Network (SECN), and the South Florida/Caribbean Network (SFCN).

The mean elevation of salt marsh surfaces must increase to keep pace with the annual rise in sea level and subsidence of salt marsh organic substrates. If the sedimentation rates in a salt marsh do not equal or exceed the net loss in elevation due to the steady increase in sea level and salt marsh subsidence, it will “drown”. When a salt marsh “drowns”, the surface of the marsh becomes sub-tidal which can cause drastic habitat changes such as the conversion of vegetated salt marsh to unvegetated mud flat. Understanding changes in relative salt marsh elevation is important for interpreting changes in salt marsh vegetation communities. Salt marsh erosion and accretion are also important parameters for measuring the response of formerly impounded marshes to restoration of tidal influence and will be particularly critical if the rate of sea level rise accelerates as predicted. This project is also part of a worldwide effort to monitor sea level rise with sediment erosion tables (SETs) and cryogenic coring devices. These two techniques measure the amount of erosion and accretion on salt marsh surfaces. Monitoring Objectives: Determine long term trends in salt marsh elevation at selected sites in NPS park units and factors contributing to the observed changes (sediment deposition or erosion).