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CEGL006294 Fraxinus americana - Juniperus virginiana / Opuntia humifusa - Phemeranthus (teretifolius, piedmontanus) Outcrop Barrens
Type Concept Sentence: No Data Available
Common (Translated Scientific) Name: White Ash - Eastern Red-cedar / Eastern Prickly-pear - (Quill Fameflower, Piedmont Fameflower) Outcrop Barrens
Colloquial Name: Piedmont Mafic Barrens
Hierarchy Level: Association
Type Concept: This community is known only from scattered mafic outcrops in the northern Virginia Piedmont. It occupies exposed, xeric bedrock exposures and has a mixed physiognomy best characterized as herbaceous with scattered, stunted trees. Fraxinus americana and Juniperus virginiana are the most typical woody plants. Dominant and diagnostic lower-strata species include Opuntia humifusa, Phemeranthus teretifolius, Polygonum tenue, Krigia virginica, Carex pensylvanica, and Danthonia spicata.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: It is unclear whether similar vegetation occurring on Bald Knob, a mafic monadnock in the southern Virginia Piedmont, belongs to this type. Also closely related (at least in physical setting) are the Diabase Glades of North Carolina, but based on the available information, they appear to be floristically distinct. None of the characteristic herbaceous species are mentioned in the descriptions provided by North Carolina.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available
Floristics: This small-patch community exhibits mixed physiognomy, occurring as a patch-mosaic of lichen and moss mats, herbs, and shrubs or stunted trees. Wooded herbaceous is probably the best descriptor of the physiognomy. Trees are usually stunted and widely spaced, with Fraxinus americana and Juniperus virginiana usually the principal species. Minor trees and shrubs include Pinus virginiana, Carya glabra, Quercus montana (= Quercus prinus), Celtis occidentalis, Celtis tenuifolia, and Rhus aromatica. The herb layer consists of mixed forbs, grasses, and Opuntia humifusa rooted on thin-soiled shelves, moss mats, and crevices. Constant species include Carex pensylvanica (dominant), Danthonia spicata (dominant), Phemeranthus teretifolius (= Talinum teretifolium), Polygonum tenue, Krigia virginica, Triodanis perfoliata, and Schizachyrium scoparium. Less constant but nevertheless characteristic herbs include Bulbostylis capillaris, Cheilanthes lanosa, Cyperus lupulinus, Eragrostis capillaris, Fimbristylis annua, Trichostema brachiatum (= Isanthus brachiatus), Muhlenbergia capillaris, Panicum philadelphicum, Scutellaria parvula var. missouriensis (= Scutellaria leonardii), Trichostema setaceum, and Trifolium virginicum. Many other species occur at low cover and constancy. Lichens and mosses, including Xanthoparmelia sp., Grimmia laevigata, Polytrichum sp., and Dicranum sp., are abundant on exposed outcrop surfaces.
Dynamics: The massive outcrops supporting this community type effectively limit the normal establishment and development of trees. Although periodic drought stress limits some weeds, the shrub Symphoricarpos orbiculatus, introduced from the western U.S., has become invasive in one occurrence. Ruderal weeds such as Veronica arvensis, Barbarea vulgaris, and Verbascum thapsus can also become problematic, especially in wet years.
Environmental Description: This vegetation type is restricted to exposed outcrops of diabase, metabasalt, and perhaps other mafic rocks in the northern Virginia Piedmont. In the northern Virginia Culpeper Basin, outcrops of fine-grained Triassic diabase are usually exposed by stream incision. Metabasalt outcrops are located on western Piedmont foothills of the Blue Ridge and are represented by resistant ledges and cliffs. Outcrops supporting this community vary from steeply dipping to nearly level ("flatrocks"). On steeper terrain, habitats are typically south- to west-facing. Soil development is limited to depositional crevices and thin veneers of silt and gravel on ledges. Samples collected from three plots were strongly to moderately acidic, with moderately high Ca, Mg, and Mn levels. Most occurrences exhibit periods of ephemeral vernal seepage on outcrop surfaces and moss mats. A closely related community type in North Carolina (Diabase Glade) occurs on xeric, acidic to neutral, purple brown, Lithic Hapludalfs with exposed bedrock.
Geographic Range: This type is apparently restricted to the northern Piedmont of Virginia.
Nations: US
States/Provinces: VA
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.689765
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: G1
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 2 Shrub & Herb Vegetation Class | C02 | 2 |
| Subclass | 2.B Temperate & Boreal Grassland & Shrubland Subclass | S18 | 2.B |
| Formation | 2.B.2 Temperate Grassland & Shrubland Formation | F012 | 2.B.2 |
| Division | 2.B.2.Nc Eastern North American Grassland & Shrubland Division | D024 | 2.B.2.Nc |
| Macrogroup | 2.B.2.Nc.1 Catawba Rosebay / Michaux''s Saxifrage - Flattened Oatgrass Felsic & Mafic Scrub & Grassland Macrogroup | M506 | 2.B.2.Nc.1 |
| Group | 2.B.2.Nc.1.c Little Bluestem - Balsam Groundsel - Prairie Groundsel Appalachian Mafic Glade Group | G180 | 2.B.2.Nc.1.c |
| Alliance | A2074 White Ash - Post Oak / Pennsylvania Sedge Appalachian Mafic-Circumneutral Scrub Alliance | A2074 | 2.B.2.Nc.1.c |
| Association | CEGL006294 White Ash - Eastern Red-cedar / Eastern Prickly-pear - (Quill Fameflower, Piedmont Fameflower) Outcrop Barrens | CEGL006294 | 2.B.2.Nc.1.c |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: ? Fraxinus americana - Juniperus virginiana / Talinum teretifolium - Polygonum tenue - Opuntia humifusa Wooded Herbaceous Vegetation (Fleming pers. comm.)
? Fraxinus americana / Opuntia humifusa var. humifusa - Carex pensylvanica - Talinum teretifolium - Polygonum tenue Sparse Shrubland (Fleming pers. comm.)
? Fraxinus americana / Opuntia humifusa var. humifusa - Carex pensylvanica - Talinum teretifolium - Polygonum tenue Sparse Shrubland (Fleming 2002b)
= Schizachyrium scoparium - Opuntia humifusa - Talinum mengesii - Minuartia glabra Herbaceous Vegetation (Fleming and Patterson 2003)
? Fraxinus americana / Opuntia humifusa var. humifusa - Carex pensylvanica - Talinum teretifolium - Polygonum tenue Sparse Shrubland (Fleming pers. comm.)
? Fraxinus americana / Opuntia humifusa var. humifusa - Carex pensylvanica - Talinum teretifolium - Polygonum tenue Sparse Shrubland (Fleming 2002b)
= Schizachyrium scoparium - Opuntia humifusa - Talinum mengesii - Minuartia glabra Herbaceous Vegetation (Fleming and Patterson 2003)
- Eastern Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Boston, MA.
- Fleming, G. P. 2002b. Preliminary classification of Piedmont & Inner Coastal Plain vegetation types in Virginia. Natural Heritage Technical Report 02-14. Virginia Department of Conservation and Recreation, Division of Natural Heritage, Richmond. 29 pp.
- Fleming, G. P., K. D. Patterson, and K. Taverna. 2017. The natural communities of Virginia: A classification of ecological community groups and community types. Third approximation. Version 3.0. Virginia Department of Conservation and Recreation, Division of Natural Heritage, Richmond, VA. [http://www.dcr.virginia.gov/natural-heritage/natural-communities/]
- Fleming, G. P., and K. D. Patterson. 2003. Preliminary vegetation classification for the National Capitol Region parks. Regional (VA-WVA-MD-DC) analysis prepared for NatureServe and USGS-NPS Vegetation Mapping Program, March 2003. Virginia Department of Conservation and Recreation, Division of Natural Heritage, Richmond.
- Fleming, G. P., and K. D. Patterson. 2009b. Classification of selected Virginia montane wetland groups. In-house analysis, December 2009. Virginia Department of Conservation and Recreation, Division of Natural Heritage, Richmond.
- Fleming, Gary P. Personal communication. Ecologist, Virginia Department of Conservation and Recreation, Division of Natural Heritage, Richmond, VA.
- Grossman, D. H., K. Lemon Goodin, and C. L. Reuss, editors. 1994. Rare plant communities of the conterminous United States: An initial survey. The Nature Conservancy. Arlington, VA. 620 pp.