The American chestnut once reigned supreme
Tracking down a specific tree in Nova Scotia is like hunting for a particular grain of sand on Prince Edward Island or a cob of corn in southern Ontario, but I found it all the same, on an undisclosed dirt road in Nova Scotia’s Hants County. Its species once accounted for a full quarter of all the trees in the mixed deciduous forests of eastern North America, conquering habitats from southern New England to the Appalachian Mountains and northward into Ontario. In front of me was the “king of the forest,” as it was known, long since deposed—the American chestnut, Castanea dentata. This is not to be confused with the common horse-chestnut, Aesculus hippocastanum, an introduced tree from Europe that is very popular as a landscape or ‘street tree’ throughout the region.
The American chestnut, capable of growing 35 metres tall with a trunk 1.5 metres thick, was a keystone species in its time, producing so many nuts that countless wildlife—squirrels, bears, raccoons, deer and birds of every description—came to depend on its regular bounties. So did we, in fact. It’s been said that a single American chestnut tree can provide enough straight-grain, rot-resistant lumber to build a barn and a good-sized house, both of which would outlive you several times over. We came to praise this marvellous and mighty plant, as industries and ecosystems both flourished in its shadow.
Nova Scotia is well outside the comfort zone of the American chestnut—its seeds can’t weather the cold—but this tree’s fame carried it farther than evolution ever dared. The individual I discovered in Hants County is called the Ashdale tree, delivered to Nova Scotia from New York in 1905 by a migrant worker who planted it in his father’s front yard, where it stands to this day.
Its arrival was fortunate for the Ashdale tree, allowing it to narrowly avoid the collapse of its species. At the time, the prevailing trend across New York and New Jersey was the importation of chestnut species from Japan, China and Europe, bringing with them a ferocious blight never before encountered by the region’s native American trees.
This blight first manifested itself in 1904, in the Bronx Zoo, New York, likely carried by a Japanese sapling planted within its walls, and from there it spread. Upwards of five billion American chestnuts across a significant swath of North America were struck down in a mere half-century, pushing this once-proud plant to the brink of extinction. The only true survivors, by virtue of their isolation alone, were those planted outside their natural range, like the Ashdale tree.
It was raining slightly when I came across this refugee, its leaves somewhat darker and more robust than those of the surrounding trees. But it was the flowers that really gave it away—creamy-white catkins (like those of a willow) dangling from its branches. I stepped under its canopy to escape the rain and found I had to crane my neck in order to appreciate its true size, in width as well as height.
In fact the Ashdale tree is believed to be the largest American chestnut left in Canada—perhaps even in all of North America—its branches twisting across one another to give the distinct impression of majesty. Its bark looked hardy, and it would have taken three people to reach around its massive trunk. On the ground were dozens of empty burrs, discarded from countless failed attempts at reproduction. Without a fellow chestnut within 200 metres, the burrs of this tree could only bear empty shells. But I knew better in the case of the Ashdale tree; I knew that at least once, decades before I was born, this tree had given seed.
Les Corkum is a retired forester living in Falmouth, NS, tending to a backyard arboretum thick with oak, walnut, ash, poplar, hickory, pine and an assortment of American chestnuts all his own. I’d already fallen in love with this species by the time I met Les, and he found this amusing.
“It’s a bad one to fall in love with,” he told me, speaking, I suspect, from experience.
Shortly after the species collapsed in its native range, Les was active in preserving the American chestnuts left within our provincial borders, as yet out of the blight’s reach. He told me the first one discovered in Nova Scotia was in Bridgewater, heralded by some as the last of its kind, considering the thoroughness of the blight. This tree might have been 300 years old—and to this day no one knows where it came from—but the American chestnut cannot self-pollinate and so it produced no offspring. That is, until the Ashdale tree was found around 1948, Les estimates.
With the diligence of honeybees, conservation workers carried pollen back and forth between these two chestnuts, hoping that at least one would produce seed and allow for the establishment of a Nova Scotian population where the species would be safe—at least for the time being. But the trees were stubborn. Finally, one of them bore fruit in 1965—20 seeds in all—from which 15 saplings were successfully raised.
Two of these saplings were planted in the Halifax Public Gardens in 1967 and another three at the Kentville Research Station that same year, but to Les’s ongoing frustration, no one seems to know what happened to the other 10.
It wasn’t until August 1 (Natal Day) that I found myself able to visit the saplings in Halifax, but of course they weren’t saplings anymore but almost twice my age and very tall. I found these young ’uns fascinating, among the first American chestnuts conceived, born and raised in Nova Scotia—the products of two far-flung immigrants brought together by people and pollen.
The Bridgewater tree died in the 1970s or thereabouts, leaving behind its Ashdale mate and scattered progeny, but, as we now know, there were at least four others in our province at the time—two in the community of Hantsport, perhaps as old as the Ashdale tree, and another two at the Uniacke Estate Museum Park, planted sometime before 1815. For better or worse—likely worse—these refugees were soon joined by hundreds more.
In 1984, the Nova Scotian forestry group Bowater Mersey undertook a public relations initiative that, in hindsight, was ecologically reckless. They purchased some 600 American chestnut saplings from the United States and began planting them, in pairs, on public lands across Nova Scotia, inviting an outbreak of chestnut blight in our otherwise healthy province. These new chestnut saplings were supposedly blight-free, and for a while that seemed to be the case; but eventually the unthinkable happened.
When Bowater Mersey finished planting their trees across Nova Scotia, they had some 60 left over, which they planted all together in the Annapolis Valley. At the time, Les thought this would make a good seed orchard, but while visiting the site some years later, he discovered the unthinkable.
“I didn’t think the blight would be there,” said Les. “Couldn’t be there, I thought, but when I looked at the trees carefully, it appeared it was.”
Some of the trees seemed to be holding the pathogen off, but most were beyond help, their swollen trunks soon to be their undoing. The entire orchard was destroyed to prevent the blight’s spread, leaving Les and others to wonder just how the disease had gotten here. Had it lain dormant in one of the trees from Bowater Mersey, or was it brought here by some other means? Whatever the cause, the blight hasn’t reappeared.
But Bowater Mersey’s mass planting had one more unintended consequence, brought to my attention by PEI resident Jocelyn Clarke, an active member of the Canadian Chestnut Council and keeper of the lists for our region. Over a thousand American chestnuts span the Maritime Provinces, and she accounts for each, monitoring the plant’s numbers and ongoing health. During her time scrutinizing the chestnuts brought over by Bowater Mersey, she discovered something disappointing: many of them aren’t American chestnuts at all.
In an effort to preserve the American chestnut from the ravages of chestnut blight, many organizations have begun crossbreeding our native trees with European, Japanese and Chinese chestnuts (those who brought the blight in the first place but now have a natural resistance to the pathogen). Many of the trees imported by Bowater Mersey can therefore trace their ancestry to other parts of the world, their uniquely American traits compromised.
I hesitate to use phrases like “genetically pure,” because life is valid in any form, but the differences between a genuine American chestnut—a wild and ecologically significant species—and a domesticated Chinese chestnut—small and bred for taste—are profound. In the case of Nova Scotia’s pure American chestnuts, Bowater Mersey’s PR stunt muddied the waters. Telling the purebreds from the hybrids would take a significant amount of genetic study, considering there are now 200 to 300 living specimens across Nova Scotia. Perhaps a dozen of them have been confirmed as true American chestnuts, Jocelyn told me, but based solely on appearance, several others are not.
I tracked down one of these imposters, hiding in plain sight on the campus of King’s College in Halifax. Its partner was removed from the grounds some time ago, during a parking lot expansion, and the tree itself is in rough shape. Its base has been damaged, likely from snow removal, and it’s competing for sunlight with a sprawling maple planted not five metres away. With the passage of time, students and faculty alike have forgotten the exceptional heritage of this lone straggler, likely part American and part European, but it does have at least one admirer left.
Pamela Hazel is the president’s assistant for King’s College and has taken a special interest in the chestnut outside her office window. In fact she’s become its personal guardian, and the irony of a “hazelnut defending a chestnut” has not been lost on her.
“As long as I’m sitting at this desk, that little tree is going to stay right there,” she told me during an afternoon visit to the campus.
In 2011, Pamela took her duties as guardian a step further, accepting chestnut seeds mailed to her by Jocelyn and raising them with the intention of planting them on the campus. In her letter to the Property Grounds and Safety Committee, asking permission to undertake the project, she wrote, “We thank you for your consideration and hope that, with your approval, we are setting the stage for College Christmas 2020, when we will be serving roasted chestnuts from the trees at King’s.”
The seeds grew into four saplings over winter and would have graced the soil of King’s College in the spring of 2012, but they all died inexplicably before being planted, dashing Pamela’s hopes of feeding students roasted chestnuts grown on the campus. Whether they would have been genuine American chestnuts is another matter entirely. Just how pure must a tree’s heritage be for us to consider it an American chestnut? What if it had one foreign ancestor out of four—or one out of 10?
The Canadian Chestnut Council, a national charity dedicated to the preservation of this species, has been crossbreeding the pure Americans with foreign chestnuts for some time now. The resulting hybrids are then bred back with pure American chestnuts for several generations in the hopes of creating as pure an American as possible but with the blight resistance of its foreign progenitor. They expect progress is being made, but there are decades of work ahead and even with absolute success, the final product might still carry more foreign traits than is desirable.
It might one day be possible to restore the American chestnut to its former glory, at least in part. But whatever form the species finally takes, it seems certain to me that it will no longer be its original self, its purity sacrificed for the sake of its survival, making way for a hybrid species that’s wholly new. I think this is a worthy goal and perhaps a necessary one, but it means the true American chestnuts of Nova Scotia are relics in their own right and worth seeing before their time is up. For better or worse, someday there will be none quite like them. Having stood beneath the Ashdale tree, the Uniacke trees, the Halifax trees and those youngsters in the backyard of Les Corkum, I can say with confidence that their loss would be a crying shame.
Zack Metcalfe is a freelance environmental journalist, author and writer of the “Endangered Perspective”article series. He operates out of Halifax.