Author Dan Williams discusses exotic tree pests in the Park and Smoky Mountain forests for US-Parks.com:

Man’s activities have brought about profound changes in the forests of Great Smoky Mountains National Park (GSMNP.) Beginning around the turn of the 20th century, a series of devastating exotic tree diseases accidentally entered North America. These diseases existed in ecological balance in their native lands where host trees they attacked had enough resistance to ensure recovery. North American forests provided tree types suitable as hosts to the diseases, but with little or no inbred resistance to their onslaught. Consequently, the exotic diseases virtually wiped out their North American host species creating irrevocable rents in the forest. Here is the story of the first and possibly most devastating of these exotic pests, the chestnut blight.

Read the full story at US-Parks.com.