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DCR - Virginia Department of Conservation and Recreation
NATURAL HERITAGE

The Natural Communities of Virginia
Classification of Ecological Community Groups
SECOND APPROXIMATION (Version 2.5)

Information current as of February, 2012

Low-Elevation Basic Outcrop Barrens
This group comprises very sparse woodlands, scrub, and herbaceous vegetation of exposed, base-rich outcrops in the Piedmont and mountain regions. The majority of documented occurrences are on mafic (e.g., diabase, amphibolite, gabbro) outcrops of the Piedmont and southern Blue Ridge, and metabasalt (greenstone) outcrops of the northern Piedmont and Blue Ridge. A few examples on granitic rocks and calcareous sandstone have also been documented. Habitats generally have high cover of exposed bedrock, but often have more extensive organic or soil mats, and thus more vascular plant cover, than do acidic outcrops. Soils usually consist of thin veneers and vary from moderately acidic to circumneutral, with moderately high base status.

Vegetation is usually a patchwork of severely stunted trees, shrub thickets, herbaceous mats, and lithophytic lichens. Typical woody species include white ash (Fraxinus americana), eastern red cedar (Juniperus virginiana var. virginiana), fringetree (Chionanthus virginicus), ninebark (Physocarpus opulifolius var. opulifolius), staghorn sumac (Rhus typhina), aromatic sumac (Rhus aromatica var. aromatica), and hoptree (Ptelea trifoliata var. trifoliata). Eastern prickly-pear (Opuntia humifusa var. humifusa) is present at most Piedmont sites. Typical herbs include nodding onion (Allium cernuum), roundleaf fameflower (Talinum teretifolium), slender knotweed (Polygonum tenue), woodland sunflower (Helianthus divaricatus), hairy lipfern (Cheilanthes lanosa), rusty woodsia (Woodsia ilvensis), little bluestem (Schizachyrium scoparium), Pennsylvania sedge (Carex pensylvanica), long-awn hairgrass (Muhlenbergia capillaris), whorled milkweed (Asclepias verticillata), Appalachian phacelia (Phacelia dubia var. dubia), hoary mountain-mint (Pycnanthemum incanum var. incanum), dwarf skullcap (Scutellaria parvula var. leonardii), blue waxweed (Cuphea viscosissima), a flatsedge (Cyperus lupulinus ssp. lupulinus), tiny lovegrass (Eragrostis capillaris), false pennyroyal (Isanthus brachiatus), dwarf-dandeolion (Krigia virginica), pink corydalis (Corydalis sempervirens), mountains and foothills only), and American alumroot (Heuchera americana). These small-patch communities are rare in Virginia and globally. Perhaps because of their more fertile substrates, basic outcrop barrens are more prone to invasion by non-native weeds than are acidic barrens.

References: Copenheaver et al. (2004), Fleming (2002a), Fleming et al. (2007), Fleming and Coulling (2001), Fleming and Patterson (2004), Rawinski and Wieboldt (1993).


Click on the images below to open a larger image in a separate window.
Eastern red cedar (Juniperus virginiana) and lithophytic herbs on exposed metabasalt (greenstone) barrens at Cedar Cliffs, western slope of the Blue Ridge in Augusta County (George Washington and Jefferson National Forests). Gary P. Fleming / © DCR Natural Heritage.
Metabasalt (greenstone) barrens on the western slope Dickey Ridge, a Blue Ridge spur in Warren County (Shenandoah National Park). Gary P. Fleming / © DCR Natural Heritage.
Low herbaceous barrens on a massive diabase "flatrock" in the northern Virginia Mesozoic Basin. Near Elklick Run, Fairfax County (Fairfax County Park Authority lands). Gary P. Fleming / © DCR Natural Heritage.
Xerophytic herbaceous vegetation, lichens, and bryophytes on a massive exposure of actinolite schist, a metabasaltic rock of the southern Piedmont. Bald Knob, Franklin County. Gary P. Fleming / © DCR Natural Heritage.
Precipitous metabasalt barrens on the north flank of Little Devils Stairs, Rappahannock County (Shenandoah National Park). Clumps of little bluestem (Schizachyrium scoparium) dominate the herbaceous flora. Gary P. Fleming / © DCR Natural Heritage.
REPRESENTATIVE COMMUNITY TYPES:
This group has been fairly intensively inventoried and 65 plots have been sampled (map). Six community types have been classified, five of them supported by an average of 13 plots. Only a single example of the Southern Blue Ridge Low-Elevation Granitic Barren is currently known. Few additional examples of vegetation in this group are likely to be found. Click on any highlighted CEGL code below to view the global USNVC description provided by NatureServe Explorer.
  • Fraxinus americana - Juniperus virginiana / Opuntia humifusa - Talinum teretifolium - Polygonum tenue Wooded Herbaceous Vegetation
    Northern Piedmont Mafic Barren
    USNVC: = CEGL006294
    Global/State Ranks: G1/S1

  • Juniperus virginiana / Chionanthus virginicus / Cheilanthes lanosa - Sedum glaucophyllum Woodland
    Southern Piedmont Mafic / Calcareous Barren
    USNVC: = CEGL004443
    Global/State Ranks: G2/S1

  • Fraxinus americana - Juniperus virginiana / (Rhus aromatica) / Schizachyrium scoparium - Carex pensylvanica - Cheilanthes lanosa Wooded Herbaceous Vegetation
    Central Appalachian Mafic / Calcareous Barren (Low-Elevation Type)
    USNVC: < CEGL006037
    Global/State Ranks: G2/S2

  • Fraxinus americana / Physocarpus opulifolius / Carex pensylvanica - Allium cernuum - (Phacelia dubia) Wooded Herbaceous Vegetation
    Central Appalachian Mafic / Calcareous Barren (Mid-Elevation Type)
    USNVC: = CEGL008529
    Global/State Ranks: G2/S2

  • Quercus stellata / Schizachyrium scoparium - Sorghastrum nutans - Pycnanthemum tenuifolium - Packera paupercula Wooded Herbaceous Vegetation
    Southern Blue Ridge Low-Elevation Mafic Barren
    USNVC: = CEGL006215
    Global/State Ranks: G1/S1

  • Minuartia glabra - Talinum teretifolium - Saxifraga michauxii - Dodecatheon meadia Herbaceous Vegetation
    Southern Blue Ridge Low-Elevation Granitic Barren
    USNVC: = CEGL004991
    Global/State Ranks: G2/S1
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Table of Contents

Introduction

Overview of VA Physiography & Vegetation

Glossary

Literature

Format of Descriptions

Terrestrial System: LOW-ELEVATION ROCK OUTCROPS AND BARRENS
   - Low-Elevation Acidic Outcrop Barrens
   - Low-Elevation Basic Outcrop Barrens
   - Limestone and Dolomite Barrens
   - Mountain / Piedmont Calcareous Cliffs
   - Mountain / Piedmont Acidic Cliffs
   - Central Appalachian Shale Barrens
   - Granitic Flatrocks
   - Piedmont Prairies
   - Ultramafic Woodlands and Barrens
   - Riverside Outcrop Barrens
   - Lichen / Bryophyte Nonvascular Boulderfields and Outcrops

Palustrine System

Riverine System

Estuarine System

Marine System