Biodiversity (n). Biological diversity is the full range of all life in a given place, including the variety of native species, habitats and ecosystems (streams forests, etc). Biodiversity also refers to the genetic variety within a species, and the difference in genetic composition between species populations.

Upper Ohio River Basin

The Ohio River and its tributaries represent one of the most diverse freshwater ecosystems on earth. This is particularly demonstrated by a richness of fish and mollusk species. The Ohio and Allegheny rivers have been identified as important ecosystems for conservation from the basin source here in Pennsylvania as well as downstream across the Midwest. However, habitat and ecosystem qualities are not equal along the 981-mile course of the Ohio River, the 321-mile length of the Allegheny River, nor their tributaries.

North Central Forests & West Branch Susquehanna Basin

The largest and most contiguous stretches of forestlands are within the High Allegheny Plateau of north central Pennsylvania. Here, the highest elevations of the plateau typically rise above 2,000 feet. 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.

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.

Laurel Highlands

The Allegheny Mountains and the Youghiogheny River are an extension of the Central Appalachians ecoregion starting in West Virginia and Maryland. In Pennsylvania, the region encompasses portions of Fayette, Somerset, Westmoreland and Cambria counties. High gradient streams, sandstone outcrops, limestone caves, and large tracts of intact forestland define this rugged landscape.

Great Lakes

Pennsylvania’s portion of the Great Lakes ecoregion begins with its 45-mile stretch of shoreline along Lake Erie. Many streams drain from adjacent Erie and Crawford counties, the Central Lowlands Province, into the lake. Lake Erie moderates the area’s climate, which allows for the production of specialty agriculture such as vineyards, which are found nowhere else in our region. This area is located within the larger St. Lawrence River Basin.