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Pennsylvania Rare Communities

The Conservancy, since its inception in Pennsylvania, has protected globally rare communities like the serpentine barrens along the southeastern Pennsylvania/Maryland state line and the vernal pools of the Minsi Lake Corridor in Northampton County. Such sites host a disproportionately large share of Pennsylvania’s globally rare species.

But, threats to the rare communities are large, widespread, varied and growing. Barrens and vernal pools are declining steadily in the face of residential and commercial development. Even where protected, most barrens systems are being gradually replaced by more common forest communities because the fire disturbance they depend on has largely disappeared. Cave and karst systems are threatened by blockage of cave entrances, vandalism, and changes in hydrology.

The Conservancy has invested heavily in developing knowledge about the distribution and management needs of barrens and vernal pools, and will use that knowledge to expand protection and ecological management at the best remaining sites.

Barrens are naturally-occurring open habitats with unique plant communities that support many rare and threatened plant and animal species.

Pennsylvania has four major types of barrens:

  • Ridgetop acidic barrens on the highest, most exposed portions of some of our ridges. Moosic Mountain barrens in Lackawanna County is one of the largest barrens complexes in the state. Scotia barrens in Centre County lies in a region of unusual temperature ranges that can produce a month of subzero minimum temperatures per year and frost in mid-summer.
  • Mesic-till barrens, on the southern edge of the Pocono Plateau, with their shrub-savanna appearance, their overstory of pitch pine and their specialized component of wetland-indicator species.
  • Serpentine barrens, along the Pennsylvania-Maryland border in Lancaster and Chester counties, where serpentinite bedrock is exposed or is near enough to the surface to influence soil properties. At 2,100 acres, it’s the largest expanse of serpentine vegetation in eastern temperate North America.
  • And, shale barrens, on steep south-facing slopes, where the bedrock is composed of shale and the rocky, dark, shale soils can reach temperatures of 140 degrees Fahrenheit. Despite the dry living conditions, many species have become adapted to the habitat, including the Pennsylvania shale barrens evening primrose, cat’s paw ragwort, fence lizards and many rare moth species.

The Conservancy is working to acquire 10,000 acres to complete legal protection at the three largest northeast barrens complexes – Long Pond, Moosic Mountain and Arbutus Peak – and at Pennsylvania’s last remaining unprotected serpentine barrens.

In addition, the Conservancy is expanding partnerships to use prescribed fire and other options to prevent further loss of northeast and serpentine barrens on Conservancy lands, state forests and state game lands.

Vernal Pools

Vernal pools – also known as ephemeral, autumnal and forest pools – are temporary pools of water. No fish can survive in them, but they are a bustle of activity each spring, as salamanders, frogs and toads crowd into them to court and mate. The pools then serve as nurseries for the amphibians’ eggs and hatchlings.

The goal is protection of an additional 700 acres of Pennsylvania’s most important concentrations of vernal pools through the creation of new preserves at South Mountain, completion of the Minsi Lake Conservation Corridor at Totts Gap, and education of local government officials and landowners on conservation options for sites holding vernal pools.


For caves, the Conservancy will expand our knowledge about conservation needs and use that knowledge to protect at least a dozen large, ecologically significant systems, as well as major karst aquifers and springs, in the Central Appalachians.

In addition, the Conservancy plans to continue acquisition of priority parcels at Cherry Valley near Stroudsburg and promote the establishment of Cherry Valley National Wildlife Refuge.


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