New Survey: Northern Hardwoods Dying in WV, PA


The northern hardwood forests of the Allegheny and Monongahela National Forests and surrounding private lands are dying in record numbers, according to a recent air survey of the region.

The survey, conducted by two environmental groups, show that tens of thousands of acres of sugar maples, yellow birch, beech, black cherry, red oaks and several other species are all dying at once over the higher elevations of the mountains of eastern West Virginia and northwest Pennsylvania.

The scope of the decline also extends to the lower elevations of the Appalachian region into the oak-hickory and mixed-mesophytic forests so prominent in southern
West Virginia and south, said survey director Dr. Harvard Ayers, a professor at Appalachian State University in Boone, NC.

Northern hardwood forests span the length of the Appalachian Mountains from New England to the Great Smoky Mountains of Tennessee and North Carolina. The ten or so species that comprise these mountain hardwoods occupy the life zone just under the boreal forests that are dominated by the red spruce and the Fraser and balsam firs.

Together, these dozen or so mountain tree species are bearing the brunt of air pollution impacts from coal-fired power plants and (to a lesser degree) cars and trucks, which have made the central and southern Appalachians the most polluted skies in the country. Leaf-killing ozone in these mountains is frequently twice what it is in the surrounding lowlands.

Heavy amounts of annual precipitation, once a blessing, are now a curse since air pollution has acidified the rain, snow and fog to the extent that the soils are poisoned and the once healthy forests are greatly weakened, Ayers said. Weather extremes, disease and pests that once were benign have become deadly to trees weakened by air pollutants.

PA’s Alleghenies

The plateaus of northwest PA and adjacent New York are the highest elevations of that immediate region. Northern hardwood forests dominated by sugar maple and American beech cover the uplands above about 1,800 feet elevation across thousands of square miles.

The entire area of the survey in the Allegheny National Forest did not receive the fertilizing effects of glaciers that made for better growing conditions in the surrounding region. This fact made these forests especially susceptible to acid precipitation, which destroys forest nutrients and poisons mountain soils.

Beginning in the summer of 2000, Appalachian Voices, with the help of the Allegheny Defense Project, began an aerial survey of the northern hardwoods of the 500,000-acre Allegheny National Forest. The higher elevations of the northeast corner of this national forest and surrounding private lands were the focus, as this area had the largest concentration of elevations of 1,800 feet and above, where the sugar maple and beech forests dominate.

The survey was done from single engine airplanes piloted by the Civil Air Patrol and SouthWings, an environmental aviation group. The air mapping was greatly complicated in the Allegheny by the practice in the region of “salvaging” dying and dead trees as soon as they appear sick. Determining the severity of the forest decline is heavily dependent on the “body count” of obviously declining trees. The salvage logging, combined with miles and miles of logging roads and roads servicing gas and oil wells on public land, severely fragmented the forest cover.

“It was so chopped up that it made it extremely difficult for us to determine which areas had experienced decline,” Dr. Ayers said. “Because of these confusing elements, we decided to concentrate on areas where the forest was not subject to logging, or else to areas where for some reason the chain saws had not yet arrived. Such a location was the Tionesta Scenic and Natural area just west of Kane, Pennsylvania. This area has not been subject to logging for the decades that have witnessed the decline.”

Aerial mapping disclosed that the northern hardwoods of virtually the entire plateau area of the Tionesta and surrounding forest above 1,800 feet were in “severe decline,” Ayers said.

Even in August, the remaining live beech and maple trees were already turning yellow and red, even though fall colors were normally not evident until well into September. Many trees of both species were standing leafless.

Over 4,000 acres of the Tionesta and immediately surrounding northern hardwoods were declining. The forests to the north and northeast of the Tionesta also were also declining over thousands of acres. An additional 22,000 acres of declining northern hardwood forests were mapped, especially a large area just south of Warren, PA. Many of the maples and beech in this area were standing dead.

Another concentration of decline was from about 10-30 miles north of Kane, where the declining maple forests took on a ruddy red appearance from the air. The AppVoices/ADF survey was limited to PA, but serious decline was noted extending well into adjacent southern NY.

Eastern WV Mountains

A separate survey by AppVoices in the mountains of West Virginia’s Monongahela National Forest found forests much more intact than the Allegheny area of Pennsylvania, Ayers reported.

“From our SouthWings Cessna, we did not see vast areas of salvaged northern hardwood forests or large networks of dirt roads,” he said. “Consequently, we were able to more adequately map the extent of the forest decline.”

Flying from north to south along the valley between Shaver’s Mountain and Cheat Mountain for a distance of about 70 miles, AppVoices mapped about 75,000 acres of declining northern hardwood forests. “Roughly a third of the area above 3,500 feet, and half of the area above 4,000 feet that we looked at were in decline,” said Dr. Ayers.

Based on a brief ground inspection of an area on Shaver’s Mountain near the John’s Camp shelter, AppVoices researchers determined that the West Virginia forest was more diverse in tree species than the Allegheny area.

“We inspected northern hardwood trees over a 400-foot by 50-foot wide area,” Ayers said. “The tree species included black cherry, yellow birch, sugar maple, American beech, and an occasional red spruce, many of these trees being of substantial size. A number were standing dead, others were recently blown over with roots intact, while others had snapped off well above the ground.

“Others had thinning leaves or no leaves at all at their tops. We found not a single healthy tree with a full complement of foliage over this area of about one acre. The forest in the area surrounding our acre survey appeared to be in a similar state of ill-health.”

What’s Next?

In the summer of 2002, AppVoices plans to complete its preliminary survey of the declining northern hardwood forests from the Great Smoky Mountains of Tennessee and North Carolina to the Allegheny National Forest of Pennsylvania.

“We expect to find considerably more decline in the Pennsylvania and West Virginia mountains in areas we have not yet mapped, as well as to confirm earlier decline observations in the southern Appalachians,” Ayers said.

The group will also conduct more extensive ground surveys of all these areas to allow them to better understand the nature of the northern hardwood demise. Ayers said he hopes the survey, once completed, will spur the U.S. Forest Service and regional universities to conduct the more detailed and expensive research necessary to fully understand this tragedy.

“We also sincerely hope that decision-makers will recognize that the evidence of air pollution’s heavy hand on our forests, as well as on our health, is already enough to take action now to clear our skies and our lungs,” Ayers said.


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  1. Deborah R on May 12, 2023 at 6:11 pm

    It’s both pollution AND foreign invasive insects!! 😢

  2. Ron Metz on May 6, 2022 at 8:40 am

    What’s the solution ?

  3. Doug norris on March 25, 2018 at 3:39 pm

    Pollution?? It’s the insects….

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