Central Appalachians Ecoregion
The signature of Pennsylvania’s south-central heartland is its combination of abrupt ridges and rich open valleys, recognized as the Central Appalachian Ecoregion.
This region represents the headwaters of the West Branch of the Susquehanna River. Although some streams are degraded, largely by coal mining, several sub-watersheds are of high quality and currently are refuges for aquatic life.
Globally Important Ecological Systems
The defining folds of mountains for this ecoregion begin in the state’s northeastern counties, sweep diagonally southwest, and ultimately extend below central Pennsylvania through Maryland, West Virginia, Virginia and eastern Tennessee. This vast, rugged area includes a broad portfolio of globally important ecological systems, including rich deciduous forests, diverse watersheds and in some regions, mazes of underground habitats in the form of caves and subterranean streams.
The Appalachian Mountains
The Appalachian Mountains, some of the oldest on earth, contain ancient layers of diverse rocks chemically composed of various nutrients and existing at multiple levels of elevation. Nowhere else in Pennsylvania does the geological composition of the landscape so clearly dictate the expression of flora, fauna and the distinct habitats they depend upon. Habitats range from limestone glades and pitch-pine scrub oak barrens to cove hemlock forest and scattered vernal pools. However, all of that is everywhere dominated by the theme of long forested mountain ridges and open inter-mountain agricultural valleys.
The contributions and influence of this ecoregion to global aquatic biodiversity are significant. Many small cold, clear, headwater streams tumble down the mountainsides and gather in the pastoral and occasionally urbanized valleys as larger streams. The lower half of great Susquehanna River and its tributaries drain this region and, along with the Potomac River, contribute most of the water feeding the Chesapeake Bay, which is one of the world’s major estuaries.