It’s hard to imagine what the forests of North America looked like before they were impacted by colonial expansion, logging, and agriculture. No one alive today remembers the towering giants known as the eastern redwood for its size, or to many Indigenous nations east of the Mississippi, from southern Ontario to Florida—”Grandfather of the forest.”
I’m talking about the American chestnut that once accounted for one out of every four trees in its native region.
A chestnut’s trunk could span 10 feet across, and the tops of the canopy were 100 feet off the ground. Old photos of settler families gathered around a chestnut tree look photoshopped. While the chestnut is no longer a fixture of the forest, its story continues...
AMERICAN CHESTNUT: DEVASTATION TO HOPE
The plight of the American Chestnut (Castanea dentata) is surely one of the most devastating tragedies to hit our North American ecosystem.
In just 40 years 3-4 billion trees were felled by a blight that ripped through the eastern United States and southern Ontario. It’s believed that an infected Asian chestnut was imported in the late 1800s and the fungus spread from there. The first infection was spotted on a tree at the Bronx Zoo in 1904.
Chestnuts once made up a quarter of all hardwood forests in the region. Prior to European colonization, Indigenous North Americans used the nuts for sustenance and made medicines, tools, and building materials out of other parts of the tree. Native people actively managed forests to encourage the growth and health of chestnut trees. The carbohydrate-rich nuts were a staple crop for European colonists as well, and the mammoth trunks were milled into lumber for floorboards, furniture, fence posts, and anything else made from wood. Thousands of years and then gone in a single generation.
Nowadays, stewards of our forests including researchers, nut growers associations and conservation authorities have been working to save the species. There are all kinds of cool science-y things happening. In Europe, introducing a virus that attacks the chestnut blight has led to the recovery of Castanea sativa. The virus doesn’t seem to want to spread as readily in North America, unfortunately.
Over on this side of the pond researchers at the State University of New York College of Environmental Science and Forestry (S.U.N.Y.–ESF) are working on genetically modified American chestnuts that are entirely immune to the blight. They’ve taken a single gene from species that have blight immunity, including grapes, wheat, and peppers, and added it to the original 38,000 chestnut genes. The new gene allows the chestnut to break down the deadly oxalic acid present in the blight’s chemical makeup, instead of being killed by it. From the lab, the trees are grown in a greenhouse, and eventually transplanted into the field. So far the results have been positive and testing is still underway. There is hope!
PLEADING THE CASE FOR THE AMERICAN CHESTNUT
Okay so you might be asking yourself, “why would I plant an American chestnut if it’s just going to die?” Not so fast! Many of us live north of the original territory of the American chestnut and therefore the blight is not so much a factor. It takes about 10km of distance between an infected tree and a healthy tree to keep the fungus at bay. Northern nurseries that grow cold hardy plants have had success with the American chestnut.
Alternately, while transgenic species aren’t available yet, breeding programs have developed varieties that are at least blight-resistant by crossing American chestnuts with Asian and European varieties.
Chestnuts grow quickly and can produce 10-20 lbs of nuts after just 10 years, and between 50-100 lbs once they reach maturity after 15-20 years. Need I say more?