Posts Tagged ‘old growth forests’

Help the Hemlocks

Tuesday, March 10th, 2009

I first saw the hemlock wooly adelgid in action about 15 years ago. Its telltale wooly white egg masses appeared on a few branches of three hemlock trees in my next-door neighbor’s yard in Park Slope, Brooklyn. Within three years the trees were dead. Since then the insect, which arrived in North America from Asia in the 1920s, has become a major scourge of eastern forests from Maine to Georgia. It is spreading rapidly into the oldest and largest hemlock stands in the Southern Appalachians, where some of the trees are 800 years old and more than 175 feet tall.

In fact, new research suggests the hemlock woolly adelgid is killing hemlock trees even faster than expected in the Southern Appalachians and most of the region’s hemlocks could be dead within the next decade. The hemlock plays a fundamental role in the ecology and hydrology of mountain habitats. Its thick, evergreen canopies help cool mountain streams that are home to trout. Many birds find shelter and places to nest in the hemlock’s evergreen boughs. In one study, 96 percent of all wood thrush nests found by surveyors were in hemlocks. Some warblers only nest in hemlocks.

Few of the growing number of U.S. native trees beset by pestilence have a federal task force devoted to their survival. The hemlock does. Among other things, the Hemlock Wooly Adelgid Action Team coordinates control efforts and runs a public education and outreach campaign. While homeowners can treat individual trees with horticultural oils or chemical pesticides, this isn’t practical for entire forests of afflicted trees. The most promising backwoods treatments found so far are two tiny nonnative beetles that dine voraciously on adelgids (and, scientists say, only adelgids). Tests in Connecticut and Virginia show that these beetles can reduce hemlock wooly adelgid populations by 47 to 87 percent in five months. The beetles have been released in selected areas throughout the Southern Appalachians.

Still, the scale of the hemlock wooly adelgid epidemic is so huge that scientists and public land managers won’t be able to contain it without the public’s help. Details on how you can monitor and treat trees on your own property and get involved in efforts to protect hemlocks in the wild are on the Hemlock Wooly Adelgid Action Team’s website.