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G180 Schizachyrium scoparium - Packera paupercula - Packera plattensis Appalachian Mafic Glade Group
Type Concept Sentence: These are grasslands of Schizachyrium scoparium with scattered, stunted trees of Cercis canadensis, Fraxinus americana, Juniperus virginiana var. virginiana, Pinus rigida, Pinus virginiana, Quercus alba, Quercus marilandica, Quercus stellata, and Ulmus alata; Packera paupercula and Packera plattensis are characteristic forbs which occur on these shallow soils and outcrops of mafic and ultramafic bedrock substrates in the Piedmont and Blue Ridge.
Common (Translated Scientific) Name: Little Bluestem - Balsam Groundsel - Prairie Groundsel Appalachian Mafic Glade Group
Colloquial Name: Appalachian Mafic Barrens
Hierarchy Level: Group
Type Concept: This group consists of vegetation associated with shallow soils over predominantly mafic and ultramafic bedrock substrates in the Piedmont and Blue Ridge, usually with significant areas of rock outcrop. Bedrock includes a variety of igneous and metamorphic rock types such as greenstone, shale, diabase, serpentine, and amphibolite. These areas on gentle to moderate slopes support a patchy mosaic of open woodland and grassy herbaceous vegetation sometimes with a predominant woody short-shrub community present. Shallow soils impede tree growth and help to distinguish this group from forests. The vegetation is structurally intermediate between other rock outcrop groups and forests. The unusual and extreme soil chemistry determines the special flora of the type. Most examples are open woodlands with Pinus rigida, Pinus virginiana, Juniperus virginiana var. virginiana, and/or Quercus alba, Quercus marilandica, and Quercus stellata in the often stunted canopy. Trees can include Fraxinus americana, Ulmus alata, and Cercis canadensis on basic soil examples. Shrubs may be dense, with species determined by soil chemistry. The herb layer is usually fairly dense and may be dominated by grasses or by a mix of grasses and forbs, both in treeless areas and beneath open canopies. The forbs include species characteristic of other rock outcrops and grassland species, with a smaller number of forest species present. Plant species richness may be fairly high. Extreme edaphic conditions lead to locally xerophytic growing conditions that contribute to relatively open canopies and a ground cover dominated by prairie grasses and a variety of forbs. Disjunct species from drier regions and some endemic plant taxa are often present.
Diagnostic Characteristics: Occurrences of this group are on mafic and ultramafic substrates. The bedrock includes a variety of igneous and metamorphic rock types such as greenstone, shale, diabase, serpentine, and amphibolite. Schizachyrium scoparium is a common dominant grass in occurrences with open canopies. It is found in a wide variety of other woodlands and grasslands, however. Packera paupercula and Packera plattensis are characteristic forbs of the special mafic and ultramafic habitat of this group.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: These glades are found mainly in the Southern and Central Appalachians and the Piedmont and are on thin soils and outcrops of igneous or metamorphic rock, which is predominantly mafic and ultramafic. They are different from the alkaline or circumneutral glades on sedimentary or meta-sedimentary rock, such as occur in the Ridge and Valley or Interior Low Plateau. Can we just call these "serpentine glades" or "mafic glades"? [Perhaps note similarity of these to other calcareous and acidic glades. Certain similarities, despite underlying bedrock differences. List them under "Similar types."]
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: The vegetation is a fine mosaic of different physiognomies, with open woodland and grassy herbaceous vegetation or short shrubs predominating. Bare rock outcrops are usually present in a minority of the area.
Floristics: Most examples in the Appalachians are open woodlands with Pinus rigida, Pinus virginiana, Juniperus virginiana var. virginiana, and/or Quercus alba, Quercus marilandica, and Quercus stellata in the often stunted canopy. Canopy species in the Piedmont are tolerant of dry, shallow soils, most commonly Juniperus virginiana var. virginiana and various oaks and pines, but also including Fraxinus americana, Ulmus alata, and Cercis canadensis on basic soil examples. Shrubs may be dense, with species determined by soil chemistry. The herb layer is usually fairly dense and may be dominated by grasses or by a mix of grasses and forbs, both in treeless areas and beneath open canopies. The forbs include species characteristic of other rock outcrops and grassland species, with a smaller number of forest species present. Plant species richness may be fairly high in communities of this group.
Dynamics: The dynamics of this group are not well known. The occurrence of the group appears to be primarily determined by site physical and environmental properties, with physical and chemical properties determining the vegetation variation. Fire may be an important influence on vegetation, and may in the long run be important for keeping the vegetation structure open, though the patchy distribution of vegetation might limit fire intensity. It is possible that fire would have allowed glade structure and vegetation to extend onto slightly deeper soils and, therefore, allowed for more extensive glades. Periodic drought and wind storms may also be an important factor limiting canopy density and stature. The shallow soil would make these sites particularly prone to all three. These glades do not appear to be undergoing the kind of cyclic succession that has been described for granitic flatrocks, but some balance of soil accumulation and destruction may be occurring on a longer term or coarser scale.
Environmental Description: These glades are mainly in the Southern and Central Appalachians and the Piedmont and are on thin soils and outcrops of igneous or metamorphic rock. Climate: Humid warm temperate, humid cool temperate. Soil/substrate/hydrology: These are areas of gentle to moderate slopes with shallow soils over predominantly mafic and ultramafic bedrock substrates in the Piedmont and Blue Ridge, usually with significant areas of rock outcrop. Bedrock includes a variety of igneous and metamorphic rock types such as greenstone, shale, diabase, serpentine, and amphibolite. The chain of serpentine barrens found along the Pennsylvania-Maryland border is one of only three such occurrences in North America. Called the Baltimore Mafic Complex, the underlying serpentinite body formed in the Cambrian Period (about 490 million years ago) and was probably deformed and attached to the continent by the Taconic orogeny in the Ordovician Period (approximately 450 million years ago). The igneous precursor rocks to the serpentinites may have originated as part of an oceanic plate or perhaps as a magmatic intrusion into the crust of an island arc.
Geographic Range: This group is scattered throughout the Southern and Central Appalachians and Piedmont, from Pennsylvania to Georgia and Alabama.
Nations: US
States/Provinces: AL, GA, MD, NC, NY, PA, SC, TN, VA, WV
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.836005
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: > Diabase Glade (LeGrand 1988)
> serpentine barrens (Latham 1993)
> serpentine barrens (Harshberger 1903a)
> serpentine barrens (Latham 1993)
> serpentine barrens (Harshberger 1903a)
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- Barton, A. M., and M. D. Wallenstein. 1997. Effects of invasion of Pinus virginiana on soil properties in serpentine barrens in southeastern Pennsylvania. Journal of the Torrey Botanical Society 124:297-305.
- Brooks, R. R. 1987. Serpentine and its vegetation: A multidisciplinary approach. Volume 1. Dioscorides Press, Hong Kong. 454 pp.
- Faber-Langendoen, D., J. Drake, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
- Harshberger, J. W. 1903a. The flora of serpentine barrens of southeastern Pennsylvania. Bulletin of the Torrey Botanical Club 18:339-343.
- Latham, R. 1993. The serpentine barrens of temperate eastern North America: Critical issues in the management of rare species and communities. Bartonia (supplement) 57:61-74.
- LeGrand, H. E., Jr. 1988. Cedar glades on diabase outcrops: A newly described community type. Castanea 53:168-172.
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- Oakley, S. C., H. E. LeGrand, Jr., and M. P. Schafale. 1995. An inventory of mafic natural areas in the North Carolina Piedmont. North Carolina Department of Environment, Health, and Natural Resources, Division of Parks and Recreation, Natural Heritage Program, Raleigh. 252 pp.
- Pennell, F. W. 1910. Flora of the Conowingo Barrens of southeastern Pennsylvania. Academy of Natural Science Philadelphia 62:541-584.
- Pennell, F. W. 1912. Further notes on the flora of the Conowingo serpentine barrens of southeastern Pennsylvania. Proceedings of the Academy of Natural Science Philadelphia 64:520-539.
- Pennell, F. W. 1929. On some critical species of the serpentine barrens. Bartonia 12:1-23.
- Radford, A. E. 1948. The vascular flora of the olivine deposits of North Carolina and Georgia. Journal of the Elisha Mitchell Scientific Society 64:45-106.
- Slapcinsky, J. L. 1994. The vegetation and soils associated with diabase in Granville and Durham counties, North Carolina. M.S. thesis, North Carolina State University, Raleigh. 208 pp.
- Wherry, E. T. 1963. Some Pennsylvania barrens and their flora. I. Serpentine. Bartonia 33:7-11.