Home » Regions » North America » Eastern Temperate Forests » Mississippi Alluvial & Southeast USA Coastal Plains » Southern Coastal Plain » Floodplains and Low Terraces

Floodplains and Low Terraces

Page contents

About the Floodplains and Low Terraces

The Floodplains and Low Terraces of the Southern Coastal Plain are a region of many discontinuous low-lying regions bordering major rivers in the southern U.S. It can be seen as a more southerly counterpart to the Southeastern Floodplains and Low Terraces. These regions occur starting from the southeasternmost border of South Carolina, through Georgia, and then also on the Gulf Coast, from the Florida panhandle, west through Alabama, Mississippi, and into eastern Louisiana.

This region includes floodplains and low terraces. Stream gradients here tend to be low, and streambottoms sandy and silty. There are also numerous oxbow lakes, ponds, and swamps. Soils here are formed on diverse substrates, variable by site, including sand, silt, clay, muck, peat, and in some areas, gravel. The mild climate and diverse soil types lead this area to be high in plant diversity.

This area was, and still is, mostly covered with southern floodplain forest. Swamps feature bald cypress (Taxodium distichum), pond cypress (Taxodium ascendens), water tupelo (Nyssa aquatica), and swamp tupelo (Nyssa biflora), and slightly better-drained sites support bottomland hardwood forest including bottomland oaks along with American sweetgum (Liquidambar styraciflua), American elm (Ulmus americana), red maple (Acer rubrum), green ash (Fraxinus pennsylvanica), and water hickory (Carya aquatica). Among the oaks, sites tending to flood only for shorter periods support swamp chestnut oak (Quercus michauxii), cherrybark oak (Quercus pagoda), and shumard's oak (Quercus shumardii), whereas ones experiencing more prolonged flooding support laurel oak (Quercus laurifolia), overcup oak (Quercus lyrata), and willow oak (Quercus phellos).

There is little human land use here, owing to its tendency to flood; there is only a small amount of agriculture on the drier areas at the margins of this region. Most of this region is left as wild forest or wetland.

The northeasternmost portion of this region borders the Carolina Flatwoods to the northeast, but most of the eastern portions of this region are surrounded by the Sea Island Flatwoods. Downstream, to the southeast, they are bordered by the Sea Islands/Coastal Marsh. Upstream, they are bordered by the Southeastern Floodplains and Low Terraces.

Along the Gulf Coast, this region is mostly surrounded by the Gulf Coast Flatwoods, although the sections in Mississippi, Alabama, and Western Florida also borders the Southern Pine Plains and Hills. Downstream, to the south, it is bordered by the Gulf Barrier Islands and Coastal Marshes, and upstream, by the same Southeastern Floodplains and Low Terraces as the regions to the northeast.

References

1. Griffith, G.E., Omernik, J.M., Comstock, J.A., Lawrence, S., Martin, G., Goddard, A., Hulcher, V.J., and Foster, T. "Ecoregions of Alabama and Georgia (color poster with map, descriptive text, summary tables, and photographs)", U.S. Geological Survey, Reston, VA (2001) Web.