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Gulf Coast Flatwoods

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About the Gulf Coast Flatwoods

The Gulf Coast Flatwoods are a low, flat, forested region just inland from the coast, extending from eastern Louisiana through Mississippi, Alabama, and Florida's gulf coast ending north of Tampa.

This region ranges from nearly completely flat to gently rolling terrain; is is underlain by a mix of sand and shell fragments of coastal origin, silt and clay, muck and peat originating from decaying organic matter, and in some places, gravel. Soils tend to be acidic and low in nutrients, and range from well-drained and droughty to poorly-drained, but there are some more nutrient-rich soils. Lakes here tend to be dark-colored, acidic, and low in nutrients, except in a few places where sag ponds formed where limestone is near the surface.

The climate is towards the mild end of a humid subtropical climate, and moderated by the ocean. Rainfall and humidity are high year-round.

This region originally supported a mix of woodland and open savanna. Most common cover was slash pine (Pinus elliottii) forest or savanna, with understory of wiregrass. Drier, more fire-prone areas supported longleaf pine (Pinus palustris) savanna, or woodland with longleaf pine and saw palmetto (Serenoa repens). Wetter sites supported savanna slash pine and pond cypress (Taxodium ascendens).

The original forests have been mostly cleared here, but the region still has a large portion of forest cover; presently there are extensive pine plantations, but also mixed forest and forested wetlands. There are small amounts of pastureland and cropland on the better-drained sites, and there is also significant urbanization. This region contains numerous small cities, including most of the metro areas of Hammond, LA, Slidell, LA, D'Iberville-St. Martin, MS, Mobile, AL, Pensacola, FL, and Panama City, FL. Even between the cities, this region is populous, especially near the coast, with low-density suburban development extending into this region from more heavily-developed coastal areas. Drainage here has also been altered; some sites have been drained. This area also contains much of the Gulf Intracoastal Waterway (GIWW), an inland waterway consisting of a mix of natural bays and rivers and artificial canals. In some places, these canals have cut directly through this region.

This region is bordered to the south along the coast by the Gulf Barrier Islands and Coastal Marshes, except at its eastern end in Florida where it is bordered to the south by Big Bend Coastal Marsh. Along the floodplains of larger rivers, it is interrupted by the Floodplains and Low Terraces. At its eastern end, it is bordered to the east by the Central Florida Ridges and Uplands, to the south by the Southwestern Florida Flatwoods, and to the north by the Tallahasee Hills/Valdosta Limesink. Over most of its length it is bordered to the north by the higher, hillier Southern Pine Plains and Hills, except for two spots in Florida where it briefly borders the Tifton Upland to the north, and has a slightly larger border to the north with the Dougherty Plain. At its westernmost end, is is bordered to the west by the Baton Rouge Terrace, to the south along the coast by the Deltaic Coastal Marshes and Barrier Islands, and to the south farther inland by the Inland Swamps.

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.