Name:
Schizachyrium scoparium - Clinopodium arkansanum - Bigelowia nuttallii Southeastern Coastal Plain Barrens & Glade Group
Reference:
NatureServe Biotics 2019
Description:
This glade and barrens vegetation is found on various specialized substrates (igneous rock, clay, saline soil, limestone, sandstone) in the coastal plains of the southeastern United States from eastern Texas to northern Florida. It is currently documented from seven distinct areas and their particular substrates. They will each be described separately.<br /><br />On outcrops of marine sediment and glauconitic clays of the Weches Formation in central eastern Texas, a series of small-patch communities occur primarily in San Augustine, Nacogdoches, and Sabine counties, where they are endemic. These outcrops are exposed by natural erosion of hillside slopes. Soils are shallow, rocky and basic, factors which tend to inhibit growth of woody vegetation. Outcrops are seepy and saturated during winter and early spring but become hard and dry in the summer. Enormous seasonal variations in species dominance can occur. Characteristic species include <i>Sedum pulchellum, Clinopodium arkansanum</i>, and <i>Sporobolus vaginiflorus</i>. A scattered shrub layer, including <i>Cercis canadensis, Cornus drummondii, Juniperus virginiana</i>, and <i>Sideroxylon lanuginosum</i>, may be present on some sites. In addition, the narrowly endemic annuals <i>Lesquerella pallida</i> and <i>Leavenworthia aurea var. texana</i> may be present.<br /><br />Another series of associations is confined to the Catahoula geologic formation of eastern Texas and western Louisiana. These sites include a vegetational mosaic ranging from herbaceous-dominated areas on shallow soil and exposed sandstone to deeper soils with open woodland vegetation. Seasonal droughtiness, shallow soils, aluminum toxicity, and periodic fires are important factors that influence the composition and structure. The woodland component (which is treated in a separate group) exhibits a post oak-dominated overstory grading into longleaf pine-dominated areas.<br /><br />In Saline and Pulaski counties, Arkansas, there are glade communities restricted to distinctive, massive outcrops of igneous substrate ("nepheline syenite"). Zonal vegetation communities are present around the outcrops. Interior herbaceous-dominated zones can be mesic to wet as springs and small ephemeral streams flow across the rock outcrops and water pools in flat areas. Deeper, more heavily wooded vegetation develops along the flat or slightly sloping outcrop edges. It is possible that examples also occurred in the adjacent Ouachita Mountains of Arkansas, although extant examples are not known. These are also at least conceptually accommodated here, even though this extends the range off of the coastal plains.<br /><br />Altamaha Grit glade vegetation occurs on outcrops of indurated sandstone in the Tifton Upland of the Georgia Coastal Plain. Scattered trees and shrubs can be rooted in deeper soils or crevices, including <i>Pinus palustris, Quercus marilandica</i>, and <i>Vaccinium arboreum</i>. Typical herbaceous species include <i>Allium cuthbertii, Aristida beyrichiana, Bigelowia nuttallii, Coreopsis major, Croton michauxii, Liatris squarrosa, Manfreda virginica, Penstemon dissectus, Schizachyrium tenerum, Phemeranthus teretifolius</i>, and <i>Tephrosia virginiana</i>. A typical dwarf-shrub is <i>Hypericum lloydii</i>. Rare or highly restricted species typical of this community are <i>Cuscuta harperi, Evolvulus sericeus</i>, and <i>Penstemon dissectus</i>. Occurrences can be as large as 5 acres. This community typically occurs in a matrix of longleaf pine woodlands.<br /><br />Sandstone glades of Panhandle Florida are dominated by <i>Bigelowia nuttallii</i>. Other characteristic species include <i>Schizachyrium scoparium var. scoparium</i> and <i>Eurybia hemispherica</i>. Outstanding examples are found at TNC Rock Hill Preserve (Washington County, Florida).<br /><br />Small-patch limestone glade and outcrop communities are endemic to the Panhandle of Florida (primarily Gadsden and Jackson counties) and adjacent Decatur County, Georgia. This vegetation includes a range of open limestone outcrops on hillsides and hill crests where soils are either very shallow or absent. This grades into shaded, mesic lower slopes near the floodplain of the Chipola River, and some mesic herbaceous patches dominated by <i>Aquilegia canadensis</i> are also included here.<br /><br />In addition, there are distinctive communities that occur in portions of the coastal plain west of the Mississippi River on soils with high saline content, which in the most extreme examples are generally not conducive to woody plant growth. Thus, the vegetation forms a mosaic primarily consisting of open herbaceous or shrubby plant communities. This type is most common, and best documented in Arkansas and western Louisiana, but also occurs in eastern Texas. There are also related examples in the adjacent Ouachita Mountains of Arkansas; these are also accommodated here, even though this extends the range off of the coastal plains.
Accession Code:
urn:lsid:vegbank.org:commConcept:40250-{CF285668-5CEF-4BBF-A51D-93F0C4B45366}
Plot-observations of this Community Concept:
0
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