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What's news in nature
BY CHARLES GARRATT • STAFF WRITER
 | | The fluffy white spots on the bottom of these hemlock needles are hemlock wholly adelgids literally sucking the life out of the tree. The needles have white streaks caused by the feeding insects. The white to silver cast of dying hemlock trees has been a common site in the Highlands for a number of years. (Recorder photo by Charles Garratt) |
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FOREST LANDS - The next couple of years may be the last chance anyone will have to see eastern hemlock trees growing wild in the Highlands. The majestic trees are rapidly following the fate of the chestnut, which disappeared from these mountains almost 100 years ago.
A tiny, alien insect pest is responsible for the demise of the hemlock. Hordes of hemlock wholly adelgid, Adelges tsugae, suck the life out of eastern and Carolina hemlock trees by attaching at the base of the needles and feeding on the cells that transfer and store nutrients until the needles die.
The insects are tiny and hide on the underside of needles. They are spread by the wind, birds and mammals.
Heather Luczak, environmental coordinator in the U.S. Forest Service Warm Springs district office, said forest silvaculturists estimate 90 percent of the eastern hemlocks in the district are infected. So far, no effective control for the pest has been found.
Entomologists at Virginia Tech are studying a beetle from Japan that may be a natural predator of the wholly adelgid according to an article on the Bio-medicine Web site (www.bio-medicine.org). The beetle originates from the same part of Japan as the wholly adelgid species attacking hemlocks in the east.
The risk of extinction is real, according to Luczak and others. The forest service is working with the Camcore organization from N.C. State to preserve the genetic material of the Carolina and eastern hemlock. The Carolina hemlock is found as far north as southern Montgomery County.
Camcore personnel are collecting cones and seeds from the remaining healthy hemlocks in the Warm Springs district. But the job hasn't been easy, said Luczak. "We had a hard time finding any healthy trees producing cones."
Once healthy seeds are obtained, hemlock trees will be grown in areas not infested with the adelgid. This could include mountain locations in Central America and sites high in the Ozarks, said Luczak.
The process of saving species by relocating part of the population, storing the seeds or creating new populations is called ex situ conservation. Camcore began with Carolina hemlock in 2003 and expanded to eastern hemlock in 2005.
By establishing healthy populations outside the normal range of the hemlock, Camcore hopes to maintain the species until a control for the adelgid can be found. At that time, the species can be reintroduced to its natural range.
The loss of the hemlocks impacts more than just the tree species. The effect has been especially noticeable in stream corridors in the Highlands. Huge hemlock trees provided year around shading along many streams and rivers.
As the trees turn gray to white and die, the canopy opens allowing more sunlight to reach the stream and stream bank. Some species benefit from the additional light. But warmer waters can reduce trout habitat and additional sunlight can allow new species of plants and animals to crowd out other valuable species.
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