Gulf Coast Loblolly Pine Flatwoods

This forested system occurs on broad upland flats in the East Gulf Coastal Plain of Alabama and Mississippi, as well as western parts of the lower terraces of the East Gulf Coastal Plain ("Florida Parishes"; EPA Ecoregion 74d) of Louisiana, and likely occurs in other parts of the region as well. Its status and extent in this intervening terrain is unknown. Known examples in the Alabama/Mississippi parts of the range include a mosaic of open forests dominated by Pinus taeda interspersed with patches of Quercus phellos and sometimes other tree species. The ground surface displays an evident microtopography of alternating mounds and swales occurring in a tight local mosaic. These mounds are most likely "gilgai" resulting from vertic or shrink-swell properties of the Luinn soil series. Known examples display a range of moisture conditions from dry to wet. The wettest examples trap significant moisture from local rainfall events. These areas have ponded water for a minimum of several days at an interval and potentially for long periods of the year, especially when evapotranspiration is lowest. The vegetation of this system supports relatively low vascular plant diversity and thus may appear floristically similar to other pine-hardwood vegetation of the region. The dry portion of this vegetational mosaic is dominated by grassy ground cover (Chasmanthium sessiliflorum) with scattered emergent greenbriars (Smilax spp.) underneath a nearly pure Pinus taeda overstory. The historical composition of this type is unknown, but it seems likely that Pinus taeda was a natural and even dominant component of this system, as it is in related systems in the West Gulf Coastal Plain. Wetter areas are dominated by an overstory of Quercus phellos with an abundance of Sabal minor in the understory. Although the specific role of fire in this system is unknown, low-intensity surface fires may have been ecologically important. Such fires could have originated in the surrounding East Gulf Coastal Plain Interior Shortleaf Pine-Oak Forest (CES203.506).

In the western parts of the lower terraces of the East Gulf Coastal Plain ("Florida Parishes") of Louisiana (EPA Ecoregion 74d and adjacent 75a), the flatwoods vegetation tends to be dominated primarily by hardwoods in the most western portion, and a mixture of Pinus glabra and Pinus taeda in the intermediate portion to the east of this (Smith 1996b). In this "Louisiana Florida Parishes Spruce Pine Flatwoods Forest" some characteristic species include Pinus glabra, Quercus laurifolia, Quercus michauxii, Quercus nigra, Quercus pagoda, Quercus virginiana, Pinus taeda, and Magnolia grandiflora. Some important understory trees and shrubs include Crataegus opaca, Sabal minor (which may often be very abundant or dominant), and Arundinaria tecta.

Known examples of this system in the Alabama/Mississippi parts of its range include a mosaic of open forests dominated by Pinus taeda interspersed with patches of Quercus phellos and sometimes other tree species. The vegetation of this system supports a relatively low vascular plant diversity and thus may appear floristically similar to other pine-hardwood vegetation of the region. The dry portion of this vegetational mosaic is dominated by grassy ground cover (e.g., Chasmanthium sessiliflorum) with scattered emergent greenbriars (Smilax spp.) underneath a nearly pure Pinus taeda overstory. The historical composition of this type is unknown, but it seems likely that Pinus taeda was a natural and even dominant component of this system, as it is in related systems in the West Gulf Coastal Plain (R. Evans pers. obs., T. Foti pers. comm.). Wetter areas are dominated by an overstory of Quercus phellos with an abundance of Sabal minor in the understory.

In the western parts of the lower terraces of the East Gulf Coastal Plain ("Florida Parishes") of Louisiana, the flatwoods vegetation tends to be dominated primarily by hardwoods in the most western portion, and a mixture of Pinus glabra and Pinus taeda in the intermediate portion to the east of this. In this "Louisiana Florida Parishes Spruce Pine Flatwoods Forest" stands contain Pinus glabra, Quercus laurifolia, Quercus phellos, Quercus michauxii, Quercus nigra, Quercus pagoda, Quercus virginiana, Pinus taeda, Nyssa biflora, Nyssa sylvatica, Magnolia grandiflora, Salix nigra, Liquidambar styraciflua, Carya glabra, Acer rubrum, and Fraxinus pennsylvanica. Understory trees and shrubs include Crataegus opaca and Sabal minor (which may often be very abundant or dominant), as well as Arundinaria tecta (= Arundinaria gigantea ssp. tecta), Cephalanthus occidentalis, Diospyros virginiana, Cornus foemina, Crataegus viridis, Ilex opaca var. opaca, Ilex decidua, Itea virginica, Morella cerifera (= Myrica cerifera), Sambucus nigra ssp. canadensis, Styrax americanus, and Viburnum dentatum (Smith 1996b).

In the Alabama/Mississippi parts of this system's range, the ground surface displays an evident microtopography of alternating mounds and swales occurring in a tight local mosaic. In Louisiana, the soils are described as Hydric, acidic silt loams (including the Encrow, Gilbert, and Springfield series). The setting is broad, low flats, in small to large depressions, and along small, ill-defined drainages locally known as "slashes" (Smith 1996b).

This forested system occurs on broad upland flats in the East Gulf Coastal Plain of Alabama and Mississippi, as well as western parts of the lower terraces of the East Gulf Coastal Plain ("Florida Parishes") in Louisiana. The complete and detailed range of this system is being developed and is not completely understood. It is not thought to extend into the Mississippi River Alluvial Plain of Louisiana (P. Faulkner pers. comm.).