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American beech is one of the seven major tree species that makes up Ontario's tolerant hardwood forest, but like so many other tree species, it is declining due to an invasive alien disease known as beech bark disease.
"Beech bark disease is actually caused by two pests," explains OFRI research pathologist John McLaughlin, who is studying the disease.
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| Beech bark disease, which is caused by a scale insect and a fungus, killed the bark on the right side of this American beech tree. |
"There's a scale insect that wounds mature trees by feeding on their bark. Then a fungus enters through the scale wounds, producing many circular or lemon-shaped cankers that can kill large areas of bark.”
He says the weakened trees produce fewer branches and less foliage, causing the tree to decline, and the stems can be so weakened that high winds can break them.
According to McLaughlin, the scale insect and canker fungus likely hopped the North Atlantic a century ago, but beech bark disease was not officially confirmed in Ontario until 1999.
"The disease has been steadily marching across the range of beech in Ontario for the last decade or so," he reports. "We believe that people moving firewood may be hastening its spread."
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| Remarkably, these two beech—one healthy and one diseased—were found standing side by side in a southern Ontario forest. Scientists hope that one day they may be able to use cuttings from healthy trees to produce disease-resistant seedlings and restore beech to its former glory in southern Ontario forests. |
So what's a forester to do to manage beech in the face of beechbark disease? McLaughlin recommends checking out the new Forest Research Note he wrote with his colleague Sylvia Greifenhagen, OFRI's pathology research forester.
"On a relative scale, beechbark disease has not been in Ontario for that long, so we don't know yet how it will affect stand composition and ecosystem function in tolerant hardwood forests," he concludes.
"Based on what's happened in other parts of North America, the effects will likely vary. But we can mitigate the effects of the disease by retaining trees that show resistance and selectively removing diseased trees."
To download a PDF of the Forest Research Note, entitled Beech Bark Disease in Ontario: A Primer and Management Recommendations, visit OFRI's Publications page.
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| Because of its smooth bark, American beech is a favoured target for people with a pocketknife and a yen to express themselves publicly. However, carving initials in trees is not recommended; any injury to a tree's bark is a beacon for insects and diseases. |
Did you know...? Facts about American beech
Beech trees, which can live up to 250 years in Ontario, are known for their full, beautiful crowns and their ultra-smooth grey bark.
If you see a tree with smooth bark that has initials carved into it, chances are excellent it is a beech tree (carving initials is not a good idea, no matter how romantic it seems, as it creates an entry point for insects and disease).
According to McLaughlin the decline of beech could have serious ecological consequences. The oily, high-calorie nuts of beech trees are an important food source for black bears, deer, wild turkeys and other birds, and various rodents.
What's more, American beech has been very useful to people throughout history:
- The strong, heavy wood of this tree is used for products such as flooring, furniture, railway ties, and paper pulp, and its high density makes it excellent firewood.
Because of its large crown and smooth, attractive bark, beech is popular for parks and golf courses. - In colonial times, beech leaves were used to stuff mattresses when feathers were not available.
- Hollowed stems have been used for culverts, the leaves and bark are a source of clothing dyes, and its wood has been used to make creosote and charcoal.
