With thousands of "cut and fill" slopes, more than 3,000 vista openings and more than 1,000 utility and roadway crossings, the Parkway contains an unusually large number of "disturbance" habitats for pioneer and often exotic plant species. In the Southern Appalachian highland forest landscape, exotic thickets and groves are aesthetic intrusions. They often obscure native flora and give visitors a false image of the area's natural vegetation. Furthermore, exotic plant invasion can lead to elimination of some species of local flora. Exotic vine species such as kudzu, honeysuckle and bittersweet prevent mature forests from developing by suppressing tree emergence and growth.
Control of an exotic plant species is a long-term commitment since non-natives are prolific seed producers and often become well established in an area within one or two years. Many of these species also have long-lived seed viability, further enhancing their establishment. Abandonment of a control area can actually result in enhancement of exotic populations. Consequently, Parkway staff must look for new exotic species that might establish themselves in these newly disturbed areas.
Several non-native animals can also pose problems to our native species. Eastern bluebird populations dropped significantly as the more aggressive European starlings took over available nesting cavities. Introduced brown and rainbow trout have displaced brook trout from many aquatic systems, forcing our only native trout to move further and further upstream. The list of nonnative species extends down to invertebrates, including earthworms and crayfish, and even fungi. The introduced chestnut blight fungus wiped out American chestnut trees throughout the Southern Appalachian forests, and the balsam woolly aphid has destroyed spruce forests at our highest elevations.