Nearctic Salt Marsh - Code: Ne12C

Nearctic Salt Marshes are found in low and sheltered coastal areas that receive regular tidal inundation. Salt marshes are only found in areas protected from strong wave action are often grow around bays, estuaries, and on the leeward side of barrier islands. Calmer conditions and sediment from estuaries or tides allow for the accretion of soils on tidal flats. As the mudflats increase in height, the rate and duration of tidal inundation decreases – this allows plants to become established on the exposed surfaces. Once plants are established, the rate at which sediment is trapped increases and salt marshes can grow rapidly after the initial hurdle of establishment. These wetlands typically occur in temperate areas and are often found in conjunction with Nearctic Tidal Mudflats and less commonly with Nearctic Sandy Beach and Dune.
In the Nearctic, salt marshes are dominated by halophytic (salt-loving) grasses. Height of the vegetation typically varies with distance from the waterline, with grasses increasing in height from 0.5–1 ft. (15–30cm) tall far from water to 4 ft. (120cm) near the water’s edge. Communities vary between the low marsh (areas that receive daily tidal flooding) and the high marsh (areas the flood only rarely). In the Atlantic and Gulf Coast Salt Marsh, grasses tend to dominate and shrubs are rare or absent. The primary plants found in this subtype are Saltgrass (Distichlis spicata), Smooth Cordgrass (Sporobolus alterniflorus), Gulf Cordgrass (Spartina spartinae), Salt Hay (Sporobolus pumilus), Blackgrass (Juncus gerardii), and pickleweeds (Salicornia spp.). Pacific Coast Saltmarsh tends to be less grassy overall with a mix of graminoid and succulent plants in the low marsh including Beachwort (Batis maritima), Lyngbye’s Sedge (Carex lyngbyei), Saltgrass, and Marsh Spikerush (Eleocharis palustris). Common Glasswort (Salicornia depressa), Spear-leaved Orache (Atriplex prostrata), Iodine Bush (Allenrolfea occidentalis), and Alkali Heath (Frankenia salina) are small shrubs that are dominant in the high marsh. Smooth Cordgrass is an invasive species in Pacific salt marshes and in many areas has become the dominant vegetation.
Many salt marshes occur along estuaries and salinity decreases as you move upstream. In many cases, these marshes will blend into freshwater wetlands like NEARCTIC REEDBED MARSHES and NEARCTIC SEDGE AND GRASSLAND MARSHES.