Red spruce and balsam fir (the keystone species in this ecosystem) are limited to the Allegheny Mountains and the Northern Ridge and Valley sections, and models project suitable habitat and growth potential to decline dramatically for both species under both climate scenarios. Balsam fir has the lowest adaptive capacity of all the species in this ecosystem, largely due to its fire- and drought-intolerance and susceptibility to balsam woolly adelgid and other insect pests. Models also project suitable habitat, growth potential, and trees per acre to decline for eastern hemlock and eastern white pine, but only under high climate scenarios. Results are mixed for red maple, tulip tree, black cherry, and white ash, which are projected to lose suitable habitat but maintain potential growth and volume. Although the amount of suitable habitat may contract, models agree that remaining suitable habitat may allow regeneration of these species in the absence of other stressors. Red maple and tulip tree could potentially fill the niche vacated by spruce and fir. Other common species were modeled only by the Tree Atlas: cucumber-tree, yellow birch, and sweet birch are also projected to lose suitable habitat in the sections occupied by this ecosystem.