Many once-dominant tree species no longer prevalent thanks to non-native species elisfkc2 / Flickr / CC BY-SA 2.0 Many once-dominant tree species no longer prevalent in WNC thanks to non-native species Forest experts say the health of the region’s trees is being put to the test. “We are learning more and more that when you make an impact to one tree, it’s felt around the forest,” said Jonathan Marchal, director of education at the North Carolina Arboretum. “If you would ask me that question 200 years ago, I would have had a different answer for you. This would have been a forest dominated by the American Chestnut,” said Marchal.