"Repeating this analysis as new FIA data becomes available may show if we are beyond a tipping point and are now losing hemlock," Trotter said.
Even if there were continued increases in hemlock abundance in northern climates, where cold temperatures slow damages from hemlock woolly adelgid, the loss of trees in the south is a loss to the species, Trotter said. "Losing trees in the South results in less genetic variation for hemlock," he said.
"Non-native forest insects like the hemlock woolly adelgid are devastating on many levels because trees are so important to a region's culture and economy," said Michael T. Rains, Director of the U.S. Forest Service's Northern Research Station and the Forest Products Lab. "Forest Service research is working hard to more aggressively control non-native insects and make our forests healthier and more resistant to these disturbances."
Co-authors on the study included Randall Morin, a research forester with the Northern Research Station, Sonya Oswalt, a forester with the Forest Service's Southern Research Station, and research entomologist Andrew Liebhold with the Northern Research Station.
The study included data from 432 counties in 21 states: Alabama, Connecticut, Delaware, Georgia, Kentucky, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Vermont, Virginia, West Virginia, and Wisconsin.
|Contact: Jane Hodgins|
USDA Forest Service - Northern Research Station