Western Allegheny Plateau Ecoregion

Description & Physiography

Encompassing some 26 million acres across the plateau of the Allegheny Mountains in eastern Ohio, western Pennsylvania, northwestern West Virginia, and parts of Kentucky and New York, the Western Allegheny Plateau ecoregion is, like its neighbor the High Allegheny Plateau, divided into northern areas that were gouged and scraped over millennia by glaciers and those of the southern plateau that lay beyond the ebb and flow of these great land movers.

The glaciated Western Allegheny Plateau, characterized by rounded hills, ridges and broad valleys, is divided into two major drainage basins: one that gathers flow west into Lake Erie (and points north) and the other that feeds the Ohio River and points south to the Gulf of Mexico. Elevations range from 650 to 1000 feet. Streams in the Lake Erie drainage are especially underlain by deep coarse sand and gravel glacial outwash and the landscape itself features natural lakes, fens, bogs and marshes. The Southern unglaciated Allegheny Plateau is a maturely dissected plateau characterized by high hills, sharp ridges and narrow valleys. An exception is the broad Teays Valley which was created by a large, preglacial river. Elevations vary from 650 to 1300 feet and the bedrock consists of sandstone, siltstone, shale, some limestone and coal.


Glaciated: Precipitation averages 35 to 40 in (900 to 1,020 mm) fairly evenly distributed throughout the year, but slightly higher in spring and early summer and lowest in winter. Average annual temperature is about 50 oF (10 oC). The growing season averages about 160 days.
Unglaciated: Precipitation averages 35 to 45 in (900 to 1,150 mm); it occurs mainly during summer, winter, and spring. Rain on snow is common during winter and early spring. Summers are dry with low humidity. Temperature averages 52 F (11 C). The growing season lasts 120 to 180 days.

Plants & Animals

At the onset of Euro-American settlement, original land surveys indicate oak-dominated forests covering much of the unglaciated plateau. Today approximately 30-40% of this region is forested but does not have any surviving examples of the original beech-maple systems at the scale they once occurred. All large occurrences of wet hemlock forests have been significantly degraded or destroyed. The largest examples of wet hemlock forest occurred historically along the lake plain of Southern Lake Erie in Ashtabula, Ohio and in the area of what is now Pymatuning Lake along the Ohio-Pennsylvania border. One remnant example of this wet forest type still remains in western Ashtabula County and is called Morgan Swamp. The Burton Wetlands near Akron are another significant wetland system with large patch size white pine –hemlock forest system occurrences still remaining.

A network of streams and mainstem tributaries to the Ohio River run through the unglaciated plateau, which remains one of the top ten most diverse freshwater regions in North America. The forest systems of the Appalachian Plateau support rich mammalian, avifaunal, and herpetofaunal communities. Neotropical bird species, many of them forest interior mogrants, are an important group that depend on the forest. The heart of the breeding range for the Cerulean Warbler occurs in the Western Allegheny Plateau. Two globally imperiled mammal species also depend on these forests for habitat – the Indiana bat and the Allegheny woodrat. Other key forest dependent wildlife species include the broad-winged hawk, pileated woodpecker and ruffed grouse. Black bears are an important wide-ranging species whose numbers are on the increase with a newly documented population in the Ironton Unit of the Wayne National Forest, the only National Forest in this ecoregion.

Humans & History

For European settlers, the relative ease of access to the region opened the Western Allegheny Plateau to early exploitation for agriculture, charcoal, furnace smelters and timber. Mineral extraction in combination with erosion has caused a pronounced change in aspect from the original condition. Strip and deep-wall mining has impacted large areas of this landscape, some of which will not return to forest in the foreseeable future. However, this system is rebounding - in Appalachian Ohio, forest cover has increased from less than 12% in the early 1900's to approximately 40% currently.

The people of Appalachian Ohio have struggled with hardscrabble farming and lack of infrastructure since the Ohio River ceased being the sole source of easy transportation in the late 1800's. In the interior of the ecoregion, where the major economic drivers have been mining and timber, extractive uses have left visible scars on the landscape and degraded the streams, forests and the local community in many areas. Unemployment and the tradition of harvesting medicinal herbs from the forest's rich herbaceous layer has brought many once common plants such as ginseng, goldenseal and black cohosh to the brink of extinction.


Approximately 95% of Ohio’s woodlands are privately owned, though on average, most woodland owners control less than 50 acres. The number of non-industrial private forestland owners has increased over the past 20 years. Many of the largest industrially-owned forests (coal, paper and energy companies) are being broken up into smaller parcels, and will offer some of the best opportunities over the next decade to conserve large tracts of forestland. The increase in numbers of ownerships makes it difficult to communicate habitat management opportunities such as private landowner incentive programs. Reduction in tract size also makes forest management less commercially viable which contributes to the trend of forestland conversion.
Climate data source: http://www.fs.fed.us/land/pubs/ecoregions/ch16.html#221E

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