This ecoregion: West Allegheny Plateau (10K) is a temperate broadleaf and mixed forests biome, covering about 32,630 square miles (84,500 square kilometers) located in northern unglaciated portion of the Appalachian Plateau region.

The West Allegheny Plateau ecoregion is a mesophytic forests, (also called mixed-mesophytic) common in the the eastern side of the middle Appalachian Mountains. Mesophytic forests are highly bio-diverse, moisture-loving hardwoods ecosystems found in humid, sheltered areas with deep, nutrient-rich soils, found throughout the Appalachian Plateau ecosystems. The sheltered areas include: coves, lower mountainous slopes, river valleys, stream valley and ravines. The ecoregion is a heavily dissected plateau with rugged unglaciated hills and underlain by Carboniferous sedimentary rock, with significant coal and gas extraction alongside forestry and rural agriculture.

The mesophytic forests are know as one of the most bio-diverse temperate forest types in the world and contains a rich variety of tree species, herbs and vernal flora. The mature canopy of large tree flora has as many as 30 tree species in a singe site including many relics of the ancient forest that once covered North America more widely. Along with the forest canopy, there is a rich undergrowth of ferns, fungi, herbaceous plants, shrubs and smaller trees.

The tree canopy includes species like sugar maple, beech, tuliptree, basswood, norther red oak, American sycamores, cucumber-tree, bitternut hickory, pawpaw and black walnut. The drier areas include also white oak and American chestnut. Other trees typically include eastern hemlock, white ash, sweetgum, black tupelo, sweet birch, river birch and yellow buckeye.

The herb layer is very rich often with abundant spring ephemerals. Some of the more common spring ephemerals herbs include: yellow troute-lily, Dutchman′s-breeches, bloodroot, toothwart, spring-beauty, wild blue phlox. Woodland Herbs iclude: blue cohosh, black hohosh, mayapple, trilliums, foamflower, wild-ginger, ramps, and twinleaf. The list of ferns and sedges include: northern maidenhair fern, rattlesnake fern, Appalachian sedge, Pennsylvania sedge

The West Allegheny Plateau (10K) is located in northeastern Kentucky, southeastern Ohio, northwestern West Virgina, and western Pennsylvania.

Also, the adjacent ecoregion, known as the Interior Plateau (10N) is located in southwestern Ohio, south Indiana, Central Kentucky, east-central Tennessee, and northern Alabama.