Sunday, February 28, 2021

Blight wiped out the extremely useful chestnut trees in Appalachia, but there's an effort to engineer a hardier species

Long article by Kate Morgan for the Sierra Club:

Between 1904 and 1940, some 3.5 billion American chestnut trees, the giants of the Appalachian hardwood forest, succumbed to a fungal blight called Cryphonectria parasitica.

The loss was stunning—not just for sprawling ecosystems across much of the eastern United States, where the tree was a keystone species, but also for the Appalachian way of life.


By almost any metric, the American chestnut was a perfect tree. Massive, fast-growing, and rot-resistant, it was easy to mill into cabin logs, furniture, fence posts, and railroad ties. After being harvested, it resprouted; in 20 years, it was ready for the sawyer again. Wide limbs spanned the canopy, filtering sunlight and creating a diverse, layered forest below. Sweet, acorn-size nuts fed squirrels, deer, raccoons, and bears. Cooper's hawks nested in the high branches, wild turkeys in the lower forks. Insects thrived in the craggy bark, which was naturally tannic and a good choice for preserving hides. Cherokee people made dough from the crushed nuts, treated heart troubles with the leaves, and dressed wounds with astringent brewed from the sprouts. And in the fall, when the chestnuts piled up in carpets half a foot thick, white settler families collected and sold them by the bushel. 


The American chestnut does have one defense mechanism against the blight: While the tree aboveground dies, often what's beneath the soil remains viable. Chestnut roots in Appalachian forests are constantly shooting up new sprouts. They resemble shrubs more than trees—live stems clustered around a dry, dead one, with serrated oval leaves that pop, golden yellow, against the underbrush. There are an estimated 430 million wild American chestnuts still growing in their native range, and while the majority of them are less than an inch in diameter, they're easy to find if you know what you're looking for. But even these persistent saplings are doomed. Most survive only five or 10 years before the blight gets them too.