Scientists Try to Save Hemlock Trees in WV Swamp

  • The hemlocks grow 60 to 100 feet tall, and if you look at the underside of their needles, you can identify them by the white lines you see there. Photo: Glynis Board/West Virginia Public Broadcasting

October 17, 2014
By Glynis Board

On the border of Maryland and West Virginia, in an ancient swamp left over from the last ice age, two state chapters of the Nature Conservancy, each state’s Divisions of Agriculture, the West Virginia’s Division of Natural Resources, and the Forest Service have all come together to see that whatever can be done is done to manage the hemlock woolly adelgid problem that has been identified there.

Hemlock trees are ‘keystone species,’ meaning they are fundamental players in the forest ecology where they grow, critical to the mountain water systems that they hug. In 1950, humans inadvertently introduced the tiny parasitic insects native to hemlock trees in Japan.  Since then, slowly but surely, tens of thousands of these evergreens across the east coast are already dead.

Graphic: Hemlock Woolly Adelgid Blight as of 2013. Credit: USDA Forest Service

“If you’re in Blackwater Canyon you can see hundreds or thousands of dead hemlock down in the canyon,” says Tim Tomon, forest entomologist with the West Virginia Dept. of Agriculture.

He says when super storms blew through the region in recent years, it became apparent that the infestation had infiltrated some of the more remote, pristine, and delicate areas of Appalachia.

Mike Powell, stewardship manager for the Nature Conservancy, explains that the Cranesville Swamp is kind of a natural relic left over from the last ice age some 15,000 years ago.

It’s preserved in what’s called a ‘frost pocket,’ where because of the elevation, the levels of precipitation, and climatic conditions, and other key factors, a very unique ecology exists. Today it’s home to rare snails, artesian wells, carnivorous plants, and many of hemlock trees.

“We’ve talked about these hemlock forests being filters for the water we drink and the air we breathe,” Powell says. He says taking away critical pieces of forest ecosystems like the hemlocks jeopardizes the functionality of that ecosystem which translates to long-term implications for the human populations that depend on a healthy environment, whether they realize it or not.

Remarkably, in the decades scientists have been dealing with the woolly adelgid problem, they still haven’t definitively figured out why or how they push the trees to death. All they can say for sure is that in 4 to 10 years, the trees succumb. Different techniques have been used to try to manage the problem, but Tomon says the chemical pesticide is the most effective method so far.

There are a couple ways to administer the pesticide. Tomon and Powell and their teams of tree doctors will either bury pellets around the bottoms of the hemlocks, or, if there’s a lot of water around, they'll use a more involved intervention which requires a tree IV. It’s an involved, time-consuming, and expensive undertaking, but Mike Powell from the Nature Conservancy says it’s worth it.

Graphic right: Cranesville Swamp is a boreal bog formed thousands of years ago when ponds filled with peat moss. Maryland DNR reports that while many bogs were mined to use their peat as a soil additive, those that survived provide a glimpse of what much of North America looked like during the ice ages. Credit: www.dnr.state.md.us / MD DNR