“Despite aggressive efforts to control hemlock woolly adelgid infestations, large numbers of hemlock trees in the Southern Appalachian region are dead or in poor health. This loss has important implications. In addition to providing year-round cover for wildlife, hemlock has a strong influence on streamside habitat conditions and stream health. The shade cast by these majestic trees cools the water where brook trout and other stream organisms live; hemlock needles and wood decompose slowly, providing unique habitat for important forest floor organisms such as salamanders.”
“Many of these changes may prove to be short-term or localized; more significant changes are expected in the coming decades as other species replace hemlock. In areas where the evergreen shrub rhododendron is absent, red maple, sweet birch, and yellow poplar will probably take the place of eastern hemlock. Where rhododendron is already present, the shrub will probably spread, and could limit recruitment of overstory tree species.”
http://www.srs.fs.usda.gov/compass/2013/01/22/managing-for-hemlock-woolly-adelgid/
Land Management Readings 