Shale Barrens

An ecological community known as “shale barren” exists in the Central Appalachian Mountains in Pennsylvania, Virginia, West Virginia and Maryland in an area known as the “Ridge and Valley Province.” Shale barrens are normally associated with south to west facing slopes that average 30% or greater, contain loose shale bedrock, little to no soil, and an acidic nature. The southwestern aspect ensures that these areas are bathed in sunlight throughout most of the day, and the steep rocky slopes shed water quickly. The best word to describe this kind of droughty, hot, unstable growing conditions is ”hostile.”

Cowpasture River, Williamsville, Bath CountyCourtesy of Gary P. Fleming

Shale barrens often have very sporadic vegetation composed of plants that can tolerate this harsh environment. What makes these barrens special is that many of the plants found here are highly adapted “endemic” to these conditions, so they are found here and nowhere else. What trees grow here are stunted and found sporadically where there is enough soil to support a root system. Some of the trees that you may encounter on shale barren include Virginia and Table Mountain pine, eastern red cedar, chestnut, scarlet, and bear oak, pignut hickory, and black gum. Many of the herbaceous plants found here are endemic to these areas, with some locally or nationally rare. Plants such as Kate’s Mountain clover, shale barren rock cress, sword leaf phlox, shale barren primrose, shale barren goldenrod, Millboro leather flower, shale barren ragwort, white haired leather flower, yellow nailwort, and low false bindweed are plants that are associated with these unusual communities.

These hot dry areas are home to a number of lizards and snakes—animals that prefer arid conditions. Some unusual butterflies are also dependent on these communities, including Appalachian grizzled skipper and the Olympia marble. The main threat to these unusual communities is the influx of invasive plants, especially garlic mustard, spotted knapweed, and tree of heaven. Colonization of some of these areas by trees can also threaten some of the rare herbaceous vegetation. Some shale barrens are managed by introducing prescribed fire, or controlling the invasive plants or trees present to help maintain a natural community. Most shale barrens found in Maryland occur in Allegany County around Green Ridge State Forest.

Article and photo by FCFCDB member

Nature Note for 2/23/20