'America's Great Lost Tree Is Finally Returning,' a story of hope for the American Chestnut

Today's evergreen educational entry features Human Footprint on PBS Terra giving hope for the American Chestnut in America's Great Lost Tree Is Finally Returning.

We used to have BILLIONS of these extraordinary trees. Thanks to a tragic twist of fate, now… there are only 4.

Once towering over eastern U.S. forests, billions of American chestnut trees nourished ecosystems, built homes, and sustained Appalachian communities. But in the early 1900s, a foreign fungus arrived, and within decades, nearly all of them were gone.

However, the species never fully vanished. Its roots still survive underground, sending up sprouts that grow, die, and regrow in an endless cycle. These trees are biologically alive, but with most never reaching maturity, they remain functionally extinct.

In the forests of Pennsylvania, Shane Campbell-Staton joins Sara Fern Fitzsimmons from The American Chestnut Foundation to track this tree’s strange afterlife and learn the science behind its potential revival. With the help of rare surviving trees, selective breeding, and even gene editing, scientists and volunteers are working to breed blight-resistant trees.

The chestnut’s comeback will take time. But researchers are making steady progress towards developing American chestnut trees that survive and thrive in the native range they formerly dominated.

This is a story I tell my students about the importance of biodiversity; the more biodiversity, the more possible ways organisms will be able to meet human needs and wants. If a species becomes extinct, biologically, functionally, or economically, other species will be able to meet the need. We lost American Chestnuts, so we turned to other species. That's a very human-centered explanation, but it's incomplete, both because humans never replaced all the uses they had for American Chestnuts and because other organisms didn't fully replace the trees in their lives, either, as the video points out.

I also use this as an example of the limitations of evolution by natural selection. If a trait needed to meet a challenge doesn't already exist in a population, the population doesn't evolve the trait; it goes extinct. Evolution by natural selection is not like how humans imagine problem solving works; nature does not brainstorm solutions. Instead, it picks up existing solutions off the shelf. For what it's worth, that's mostly what humans do, too. mRNA vaccines started off as possible HIV vaccines before they were used for COVID-19, for example. That didn't prevent the researchers from earning a Nobel Prize.

Back to the video. This is a post-apocalyptic zombie story, at least as far as the trees are concerned, if they were able to have an opinion. With the discovery of apparently immune individuals, humans can help the species recover from its zombie apocalypse. That's a good tale of surviving collapse I can use as an inspiration for us humans.

That's a wrap for today's topic. Stay tuned for another evergreen educational entry tomorrow.