Northampton County Honors the Morey's - NC Forest Service

Managing For Hemlock Woolly Adelgid16The nonnative invasive insect hemlock woolly adelgid is taking its toll on eastern hemlock trees inthe Southern Appalachian region of the United States, where the tree often serves as a foundation or keystonespecies along mountain streams. A new article by U.S. Forest Service researchers covers the latest incontrol strategies for hemlock woolly adelgid and the ecological impacts of the widespread death of easternhemlock.Authored by Forest Service Southern Research Station scientists Jim Vose, Dave Wear, Bud Mayfield,and Dana Nelson and published March 1 (available now online) in the journal Forest Ecology andManagement, the article includes a matrix that provides the range of decisions land managers in affectedareas will need to make in the coming years, each decision tied to outcomes and implications.Despite aggressive efforts to control hemlock woolly adelgid infestations, large numbers of hemlocktrees 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 habitatconditions and stream health. The shade cast by these majestic trees cools the water where brook troutand other stream organisms live; hemlock needles and wood decompose slowly, providing unique habitatfor important forest floor organisms such as salamanders.As hemlock trees die, many of these important functions are changing. Hemlock mortality is addinglarge quantities of litter to the forest floor and streams; even more will be added as standing dead treescontinue to decompose. Hemlock death is also changing basic ecological processes such as the cycling ofcarbon, nutrients and water. Some studies predict as much as 30 percent increase in streamflow during thewinter months in areas where hemlocks dominate.Many of these changes may prove to be short-term or localized; more significant changes are expectedin the coming decades as other species replace hemlock. In areas where the evergreen shrub rhododendronis 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 recruitmentof overstory tree species. These changes in species composition may alter habitats and ecological processesrequired by terrestrial and aquatic animal and plant species.The good news is that land managers can start implementing control and restoration activities nowto prevent undesirable long-term impacts.Controlling the spread and impacts of hemlock woolly adelgid involves the integrated use of multipleapproaches including chemical control, biological control, cultural treatments, host resistance, and hostgene conservation. Chemical control has been extremely effective at small scales, but biological control iscurrently the only viable option for controlling hemlock woolly adelgid across the landscape, though re-