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G179 Schizachyrium scoparium - Bouteloua curtipendula - Stenaria nigricans Central Glade & Barrens Group

Type Concept Sentence: On glade rock outcrops annual plants dominate, such as Leavenworthia spp., Sedum pulchellum, Sporobolus neglectus, Sporobolus vaginiflorus, and Phemeranthus calcaricus; barrens areas that have thin soils may have perennial grasses and forbs such as Bouteloua curtipendula, Carex crawei, Carex eburnea, Panicum capillare, Panicum flexile, Schizachyrium scoparium, Silphium spp., and Sorghastrum nutans. These vegetation mosaics are associated with sedimentary and meta-sedimentary dolomite and limestone in the Central Appalachians and in the Interior Highlands of the Ozark, Ouachita, and Interior Low Plateau regions.


Common (Translated Scientific) Name: Little Bluestem - Sideoats Grama - Diamond-flowers Central Glade & Barrens Group

Colloquial Name: Central Interior Alkaline Open Glade & Barrens

Hierarchy Level:  Group

Type Concept: This vegetation is found primarily in the Ridge and Valley region from southwestern Virginia southward; the Inner Nashville Basin of Tennessee; on Dolomite in Bibb County, Alabama, in the vicinity of the Little Cahaba River; at low to moderate elevations in the Central Appalachians; and in the Interior Highlands of the Ozark, Ouachita, and Interior Low Plateau regions. This alkaline and circumneutral glade group encompasses shrublands, annual and perennial herbaceous vegetation, and sparsely vegetated rock outcrops on sedimentary and meta-sedimentary dolomite and limestone. These substrates are alkaline or circumneutral, and the thin soils are derived from the underlying rock. The vegetation varies according to the depth of the soil, or absence of soil. In the outcrops, annual plants dominate, such as Sporobolus vaginiflorus, Sporobolus neglectus, Phemeranthus calcaricus, Sedum pulchellum, and Leavenworthia spp. The areas that have thin soils may have perennial grasses and forbs such as Schizachyrium scoparium, Sorghastrum nutans, Bouteloua curtipendula, Panicum flexile, Panicum capillare, Silphium spp., Carex eburnea, and Carex crawei. Forbs vary greatly across the range and variability of the group and may be diverse. The shrublands can be dominated by Hypericum spp., Rhus aromatica, Forestiera ligustrina, and Juniperus virginiana var. virginiana. Sometimes widely scattered trees occur within the shrubs or perennial grasslands and may include Juniperus virginiana var. virginiana, Quercus muehlenbergii, and Quercus stellata. Some examples have numerous regionally disjunct and near-endemic plants, and have very high conservation value because of this.

Diagnostic Characteristics: These are grasslands and open rocky glades on alkaline substrates mainly in the southeastern United States, but occurring in the Midwest in Wisconsin and Ohio. Schizachyrium scoparium is a common dominant perennial grass species, and Bouteloua curtipendula and Stenaria nigricans are characteristic of this group in the southeastern United States.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Included here are open rock outcrops and related thin-soil annual and perennial grasslands and shrublands, from southern Ohio to and southern New England, south to Arkansas and Georgia. While the Great Lakes alvars have similar substrates and floristic composition to the vegetation included here, they occur far away from these glades in special habitats associated with the Great Lakes and are treated separately.

Similar NVC Types: No Data Available
note: No Data Available

Physiognomy and Structure: This group includes sparsely vegetated rock outcrops, annual and perennial grasslands, shrublands, and grasslands with very widely scattered trees. Related and adjacent woodlands are placed in other related limestone woodland groups [e.g., ~Northeastern Chinkapin Oak - Red-cedar Forest & Woodland Group (G016)$$].

Floristics: Characteristic species, which typically dominate the ground layer in open examples, include Sporobolus vaginiflorus, Sporobolus neglectus, Phemeranthus calcaricus (= Talinum calcaricum), Sedum pulchellum, Leavenworthia spp., Schizachyrium scoparium, Sorghastrum nutans, Bouteloua curtipendula, Panicum flexile, Panicum capillare, Silphium spp., Carex eburnea, Carex crawei, and Hypericum spp. Some typical woody taxa include Rhus aromatica, Forestiera ligustrina, Viburnum rufidulum, Juniperus virginiana var. virginiana, Quercus muehlenbergii, and Quercus stellata. In central Tennessee examples, there are many plants that are endemic, including Echinacea tennesseensis, Astragalus bibullatus, Astragalus tennesseensis, Dalea gattingeri, and Pediomelum subacaule. Other plants there are disjunct from further west (Somers et al. 1986). Dominant or abundant Juniperus virginiana var. virginiana is probably related to a lack of fire. In central Tennessee, small-scale seepage areas and washes may contain Eleocharis compressa, Eleocharis bifida, Nothoscordum bivalve, Isoetes butleri, and Hypoxis hirsuta. Characteristic forbs in northern examples include Asclepias verticillata, Monarda fistulosa, Salvia lyrata, Symphyotrichum oblongifolium, and Brickellia eupatorioides (Braun 1950). In the Cahaba Glades of Bibb County, Alabama, eight endemic taxa were found and newly described in 2001: Castilleja kraliana, Coreopsis grandiflora var. inclinata, Dalea cahaba, Erigeron strigosus var. dolomiticola, Liatris oligocephala, Onosmodium decipiens, Silphium glutinosum, and Spigelia alabamensis (= Spigelia gentianoides var. alabamensis). Seven Alabama state records were discovered: Solanum pumilum (last collected in 1837 and presumed extinct), Astrolepis integerrima (disjunct from Texas), Paronychia virginica (bridging a gap between Arkansas and Virginia), Baptisia australis var. australis, Rhynchospora capillacea, Rhynchospora thornei, and Spiranthes lucida (Allison and Stephens 2001).

Dynamics:  Due to the effects of periodic drought and winter frost-heaving, the thin rocky soils generally do not support forest vegetation. The perennial grasslands may accumulate fuel from dried drought-killed trees and may be prone to wildfire. Fires may play an important role in keeping the structure of the vegetation open and perennial grass- or shrub-dominated. Grazing and the harvesting of Juniperus virginiana var. virginiana trees also have played a role in keeping sites open, rather than forested (DeSelm 1994). The cessation of disturbances, such as grazing, harvesting of trees, and burning these habitats, has enabled many of the perennial grasslands to become completely dominated by Juniperus virginiana var. virginiana and/or the invasive exotic shrub Ligustrum sinense.

Environmental Description:  Site conditions and environment are characterized by thin soils over rock, usually with rock outcrops, and typically with higher pH. These areas are subject to extremes of temperature, and short-term drought can have extreme effects on the plants. In addition, wetness in the winter and frost-heaving can be pronounced. Climate: Humid warm temperate, humid cool temperate. Soil/substrate/hydrology: The substrate includes outcrops and thin soils (i.e., <20 cm soil depth) of sedimentary or meta-sedimentary rocks, dolomite or limestone. These can be flat as on limestone in the Nashville Basin or on slopes as in the dolomites of the Interior Highlands of the Ozark and Ouachita mountains, the Western Valley of the Tennessee River, and the Ketona dolomite in central Alabama. Generally the hydrology is dry upland, but there can be small saturated wetland inclusions which may support rare plant species.

Geographic Range: This group is found in the Southern Ridge and Valley of Alabama, Georgia, Tennessee, and Virginia, Knobs region of Kentucky, into southern Ohio, northeast on the Allegheny Plateau into Pennsylvania, also into New Jersey and the marble valleys of Connecticut, and west to the Interior Highlands of the Ozark and Ouachita mountains in Arkansas and Missouri.

Nations: US

States/Provinces:  AL, AR, GA, IL, IN, KS, KY, LA, MO, NC, OH, OK, TN, VA




Confidence Level: Moderate

Confidence Level Comments: No Data Available

Grank: GNR

Greasons: No Data Available


Concept Lineage: G060 split into G178 & G179 (East workshop 2-09)

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available

Synonomy: No Data Available

Concept Author(s): E. Quarterman (1950a)

Author of Description: C.W. Nordman

Acknowledgements: No Data Available

Version Date: 10-08-13

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