The Allegheny Highlands forests stretch across the Allegheny Plateau of Pennsylvania and New York, a hilly landscape of deeply cut river valleys, waterfalls, and—in the glaciated New York portion—the Finger Lakes. Under a cold temperate climate, pre-settlement forests were dominated by hemlock-white pine-northern hardwoods, with eastern hemlock and beech most abundant alongside sugar maple, red maple, birch, white ash, and black cherry. Eastern hemlock, the ecoregion's flagship species, is now declining across much of the region due to the introduced hemlock woolly adelgid, while over-abundant white-tailed deer suppress forest regeneration.

At a glance

About the temperate broadleaf & mixed forests biome

Four-season forests of deciduous hardwoods — oak, maple, beech — often mixed with conifers, shaped by warm summers and cold winters. Trees leaf out in spring and color in autumn; the generally fertile soils have made these forests heavily settled and farmed.

National refinement sub-regions

Catalog plants suited to this ecoregion

Computed from each plant's stated USDA zone range against this ecoregion's USDA Plant Hardiness Zone Map 2023 (1991-2020 climatology) via ArcGIS FeatureServer published current zone range, with the CHELSA mid-century warming delta applied for the projection. Plants whose stated range falls outside both the current and projected zone end up dropped; the rest land in one of the three buckets below.

Collections for this ecoregion

Curated multi-plant collections whose members all fit this ecoregion's zone range — no won't-grow members smuggled in. Overall fit class shown per collection is the weakest link across its members.

Related ecoregions