The American chestnut was a keystone species until the late 1800s, when a blight fungus was accidentally introduced that killed around three and a half billion trees.
Now, the trees are a rare sight. But at the Kingman Research Farm just outside of the University of New Hampshire campus, there’s an orchard, growing under the watchful eyes of researchers.
When the trees were planted in 2016 at the New Hampshire Agricultural Experiment Station, researchers thought they might hold the key to repopulating the East Coast with Chestnuts. They were bred with Chinese chestnut trees, which are naturally resistant to blight, according to Jeff Garnas, a professor of forest ecosystem health at UNH.
“The hope was that they retained enough of the resistance,” he said. “Unfortunately, they’re finding that it's a little more complicated.”
Garnas has been working with the American Chestnut Foundation to keep an eye on these trees. This summer, they measured each of the trees to see how they were doing, taking stock of their size and health.
Some are starting to show signs of blight. Garnas points to a tree starting to develop sunken spots, dotted with orange spores
“That will eventually work its way around the tree and just choke the tree,” he said. “It has a couple of years left maybe, but it's not going to become a big tree.”
Garnas says chestnut experts are going in a few different directions now, looking at a range of genes that could make the trees more successful.
But the 150 chestnuts at Kingman still have some enhanced immunity. And even though the comeback tree probably isn’t in this field, they could still help the effort. The variation in resistance across each tree could help researchers figure out which genes in the trees are contributing to it.
Garnas is also studying whether there are pollinator species that are particularly attracted to chestnut trees.
“Many times people will cite the decimation of a tree species as a massive knock to biodiversity,” he said. “There must have been native insects that depended on chestnuts and native wildlife that depended on chestnuts. But it’s actually really hard to show that.”
Garnas is planning to put traps around the chestnut site to see if those pollinators are still around.
For now, he says he will continue bringing students to look at the trees, as some grow, and others die.
