The Return of the American Chestnut
by Bill Chameides | April 21st, 2009
posted by Erica Rowell (Editor)
The American chestnut’s range stretched from Maine to Florida. A fungus, brought to the U.S. from Asia, spread rapidly and quickly wiped out this important native tree. Now scientists are trying to bring it back. (American Chestnut Foundation)
In honor of this week’s Arbor Day, here is the hopeful story of the American chestnut.
A Look Back
The American chestnut is a majestic, towering hardwood that once graced the landscape of the eastern United States. Growing to heights of 150 feet, the tree is noted for its long, serrated leaves; catkin flowers; and of course the chestnut itself — ever-roasting by an open fire thanks to the indelible image created by Mel Torme and Robert Wells in their 1946 tune first and famously recorded by Nat King Cole.
According to the American Chestnut Foundation:
“The American chestnut tree reigned over 200 million acres of eastern woodlands from Maine to Florida, and from the Piedmont west to the Ohio Valley. … An estimated 4 billion American chestnuts, 1/4 of the hardwood tree population, grew within this range.
The American chestnut tree was an essential component of the entire eastern U.S. ecosystem. A late-flowering, reliable, and productive tree, unaffected by seasonal frosts, it was the single most important food source for a wide variety of wildlife from bears to birds. Rural communities depended upon the annual nut harvest as a cash crop to feed livestock. The chestnut lumber industry was a major sector of rural economies. Chestnut wood is straight-grained and easily worked, lightweight and highly rot-resistant, making it ideal for fence posts, railroad ties, barn beams and home construction, as well as for fine furniture and musical instruments.”
All that changed at the dawn of the 20th century. A fungus — the Chestnut blight — was inadvertently imported into the United States on imported wood probably from China or Japan. The American chestnut had no resistance to this exotic disease and by the 1950s, its entire population had virtually disappeared.
Bringing It Back
The trick has been to go back to the place from where the chestnut blight first came: Asia. It turns out both the Chinese chestnut and the Japanese chestnut are resistant to the fungus — they can become infected but do not succumb to it (read more about this here and here). Maybe you’re thinking, then why not just plant the Chinese chestnut in place of the American chestnut? The thing is, it would hardly replace the America chestnut. For one, the Chinese chestnut lacks the stature of the American form — growing to a maximum height of about 60 feet instead of 150 feet. More critical is the American chestnut’s intricate, complex relationship to our ecosystem. For hundreds on hundreds of years, countless species of birds, mammals, insects and other organisms as well as soils and water have interacted with American chestnuts, tying them and their genetic properties to the land they inhabit. So instead, scientists have been busy creating a new chestnut hybrid that has the character of the American chestnut but with the blight-resistant properties of the Chinese tree.
Not being a botanist, I don’t know all the details of the hybridization process, but I gather that it involves painstaking experimentation with grafts of the trees until the desired properties are developed. A complication is that it does not suffice to develop a single tree whose seeds are used to propagate the hybrid throughout the region because that would produce a population of trees without any genetic diversity and would therefore be highly susceptible to other diseases. So scientists have been working to develop several variants of the disease-resistant American chestnut hybrid for propagation.
After many years of work, the American Chestnut Foundation believes it has developed a new strain of the American chestnut that will survive and has slowly begun planting seeds. If successful, the American chestnut may once again reign in the forests of the eastern United States.filed under: faculty
and: American chestnut tree, Arbor Day, botany, fungi, hybridization, tree blight