The Tionesta Scenic and Research Natural Areas in northwestern Pennsylvania protect adjoining tracts of the Allegheny National Forest that preserve about 4,000 acres of old-growth woodland within a 4,131-acre landscape. As one of the region’s most important surviving remnants of the forest that once covered millions of acres of the Allegheny Plateau, the area contains 300- to 400-year-old American beech and eastern hemlock, along with other native trees. Purchased by the federal government in 1936, the land was set aside for both scenic value and scientific study, and in 1973 it was recognized as a National Natural Landmark. Its secluded plateau terrain also supports notable wildlife and trails.