Surface Elevation Table (SET) Data Package

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).

本数据集为美国国家公园管理局（National Park Service, NPS）沿大西洋沿岸20处国家公园采集的地表高程表（Surface Elevation Table, SET）与标记层数据汇总包。
美国国家公园管理局（NPS）鉴于越来越多证据表明气候变化对联邦土地造成影响且公众对此认知不断加深，将湿地高程变化监测列为大西洋沿岸公园的首要工作任务。
为此，该局多个清查与监测分部（Inventory and Monitoring Division, IMD）网络联合美国地质调查局（U.S. Geological Survey, USGS）与美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）的合作团队，制定了湿地高程变化及其他影响湿地群落存续关键过程的监测规程。
本次采集的数据采用地表高程表（SET）与标记层技术完成，覆盖大西洋沿岸的5个NPS清查与监测分部网络：东北温带生态网络（Northeast Temperate Network, NETN）、东北海岸与屏障生态网络（Northeast Coastal and Barrier Network, NCBN）、国家首都区域网络（National Capital Region Network, NCRN）、东南海岸网络（Southeast Coast Network, SECN）以及南佛罗里达/加勒比海网络（South Florida/Caribbean Network, SFCN）。
盐沼地表的平均高程需持续抬升，以匹配海平面年上升速率与盐沼有机基质的沉降速率。
若盐沼的沉积速率无法抵消或超过因海平面持续上升与盐沼沉降导致的高程净损失，盐沼将发生“淹没”。
盐沼被淹没后，其地表将变为潮下带，进而引发栖息地的剧烈变化，例如将有植被覆盖的盐沼转变为无植被泥滩。
解析盐沼相对高程变化，是解读盐沼植被群落变化的关键依据。
盐沼侵蚀与淤积速率同样是评估此前被阻隔潮汐的沼泽恢复潮汐影响后响应情况的重要参数，在海平面上升速率如预测般加快的背景下，该指标将尤为关键。
本项目亦是全球范围内利用地表高程表（SET）与低温取芯设备监测海平面上升的工作的一部分。
这两种技术可量化盐沼地表的侵蚀与淤积量。
监测目标：明确NPS公园单元内选定样点的盐沼高程长期变化趋势，以及引发该变化的驱动因素（沉积物沉积或侵蚀）。