Natural Communities of Virginia - Terrestrial System - Low-Elevation Rock Outcrops and Barrens: Central Appalachian Shale Barrens

The Natural Communities of Virginia
Classification of Ecological Community Groups
SECOND APPROXIMATION (Version 2.2)

Central Appalachian Shale Barrens
This is a variable group of sparse woodlands, shrublands, and open herbaceous rock outcrops occurring on Ridge and Valley shales and Blue Ridge metashales of the central Appalachian Mountains. These small-patch communities are endemic to western Virginia, eastern West Virginia, west-central Maryland, and south-central Pennsylvania. In Virginia, they occur at elevations from 300 to 850 m (1,000 to 2,600 ft). Habitats generally occur on steep (~ 30 degree) slopes with south to west aspects. The steep, xeric slopes and friable nature of the shale create poorly vegetated hillsides of bare bedrock and loose channery visible from afar. Continual undercutting of thick but relatively weak shale strata by streams maintain most shale barrens. Less common, densely graminoid-dominated variants occurring on steep spur ridge crests and mountain summits are sometimes referred to as “shale ridge balds.”

Although stunted trees of several species — e.g ., chestnut oak (Quercus montana, = Quercus prinus), Virginia pine (Pinus virginiana) and pignut hickory (Carya glabra) — are common, shale barrens are strongly characterized by their open physiognomy and by a suite of uncommon and rare plants found almost exclusively in these habitats. Endemic or near-endemic shale barren species include shale-barren rock-cress (Arabis serotina), white-haired leatherflower (Clematis albicoma), Millboro leatherflower (Clematis viticaulis); also endemic to Virginia), shale-barren wild buckwheat (Eriogonum allenii), shale-barren evening-primrose (Oenothera argillicola), shale-barren ragwort (Packera antennariifolia, = Senecio antennariifolius), and Kate's Mountain clover (Trifolium virginicum). Other more or less widespread and characteristic herbaceous species of Virginia shale barrens include Pennsylvania sedge (Carex pensylvanica), little bluestem (Schizachyrium scoparium), poverty oat-grass (Danthonia spicata), wavy hairgrass (Deschampsia flexuosa var. flexuosa), moss phlox (Phlox subulata), mountain nailwort (Paronychia montana), rock spike-moss (Selaginella rupestris), shale-barren Pussytoes (Antennaria virginica), Canada cinquefoil (Potentilla canadensis), smooth sunflower (Helianthus laevigatus), false boneset (Brickellia eupatorioides var. eupatorioides), hairy woodmint (Blephilia ciliata), and western wallflower (Erysimum capitatum var. capitatum), Bath and Alleghany Counties).

Shale barrens are considered globally uncommon and host many locally rare species including the butterflies Appalachian grizzled skipper (Pyrgus wyandot) and Olympia marble (Euchloe olympia) and the federally listed plant shale-barren rock-cress. The primary threat to these communities is probably invasion by introduced weeds, but examples of these communities near roads are also threatened by quarrying.

References: Allard (1946), Braunschweig et al. (1999), Fleming and Coulling (2001), Fleming and Moorhead (2000), Keener (1983), Platt (1951), Rawinski et al . (1996).

Click on the images below to open a larger image in a separate window.

	A large shale barren rises steeply above bottomland fields along the Cowpasture River in Bath County. Photo © Gary P. Fleming.
	Classic shale barren habitat with abundant, low shale outcrops and loose channery produced by stream incision on a steep slope. Short Mountain near Copeland, Bath County (George Washington and Jefferson National Forests). Photo: Dean Walton.
	Shale ridge bald type of shale barren on crest of a steep spur of South Sister Knob, Shenandoah Mountain, Bath County (George Washington and Jefferson National Forests). Photo: Gary P. Fleming.
	Shale-barren wild buckwheat (Eriogonum allenii, in foreground) in a shale barren woodland of stunted Virginia Pine (Pinus virginiana) and chestnut oak (Quercus montana , = Q. prinus). Woodstock Gap, Massanutten Mountains, Shenandoah County (George Washington and Jefferson National Forests). Photo: Gary P. Fleming.

REPRESENTATIVE COMMUNITY TYPES:
Classification of three community types was based on analysis of 50 plot samples. A cooperative regional analysis of Virginia, Maryland, and West Virginia shale barren plot data by NatureServe confirmed the range-wide distinctiveness of the first two units listed below. The third Virginia unit appeared to represent a compositional subtype at the scale of the USNVC. Click on any highlighted CEGL code below to view the global USNVC description provided by NatureServe Explorer.

Pinus virginiana – Quercus montana – Carya glabra / Phlox subulata – Packera antennariifolia Woodland
Central Appalachian Shale Barren (Southern Type)
USNVC: = CEGL006562
Global/State Ranks: G3G4/S3
(Pinus virginiana , Juniperus virginiana) / Schizachyrium scoparium – Eriogonum allenii Wooded Herbaceous Vegetation
Central Appalachian Shale Barren (Shale Ridge Bald / Prairie Type)
USNVC: =CEGL008530
Global/State Ranks: G2/S2
Quercus montana – Pinus virginiana / Deschampsia flexuosa – Selaginella rupestris – Packera antennariifolia Woodland
Central Appalachian Shale Barren (Northern Type)
USNVC: ~ CEGL006288
Global/State Ranks: G3/S3

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The Natural Communities of Virginia Classification of Ecological Community Groups SECOND APPROXIMATION (Version 2.2)

The Natural Communities of Virginia
Classification of Ecological Community Groups
SECOND APPROXIMATION (Version 2.2)