America's Giant Trees Are Coming Back

Look at this. These are giant American chestnut trees. They're the last of their kind, and there used to be four billion. But by the 1950s, a fungus had killed nearly every single one. Only a mere handful of them survived, making them functionally extinct. One of the greatest ecological disasters of all time. But now, scientists are on the verge of bringing them back. And the American chestnut isn't alone. A whopping 165 of trees native to the U.S. are at risk of extinction. Our trees are quietly dying. But when I started looking into what's really going on here, I realized this isn't just about logging or temperatures rising. It's about something humans accidentally did to forests everywhere. And the plan to bring them back is fascinating. And by the end of this, you'll probably never look at our forests the same again. Massive number of trees are dying. Tree faces two serious threats. Rapid population decline. Likely to decline or become extinct. So let's pretend we are scientists tasked with bringing them back and saving extinct American trees. Where do we begin? Let's go over the most popular methods. The first, breed the survivors. Those few remaining original chestnuts that outlasted the blight are remarkable to say the least. So remarkable, in fact, their locations are kind of kept secret to the public. Which makes you how on earth did these trees survive and why can't they just make more? Well, just like humans, trees need a mate to pollinate and make more tree seedlings. The problem is these remaining trees are probably hundreds of miles apart. Ironically, the same isolation that prevents them from breeding might have been the thing that saved them from the blight. If they were in somebody's front yard, for example, and not in a forest setting, then they may not have been exposed. Meaning they might not actually be blight resistant at all. Not to mention this survival breeding comes with other complications. For example, a tiny gene pool of only a few individuals. In other words, we don't want a bunch of inbred trees. Which brings us to the second method, breed hybrids. That's like a lion and a tiger mixed. Often called back cross breeding. This involves breeding the American chestnut with other relatives that are resistant to the blight. And it turns out there are some chestnut relatives that are naturally resistant. This is the Chinese chestnut. If we breed our beloved American chestnut with a disease-resistant Chinese chestnut, we get a tree that is a 50-50 hybrid. And that offspring is much more likely resistant. But there's a problem. That offspring is only half American chestnut, right? And this is where things get cool. Scientists intentionally expose these hybrids to the blight. This is a scar and it's exactly what scientists want to see. It's a sign that the tree has successfully fought and contained the blight exposure. These scarred trees have now been tested and will continue to be bred with more American chestnuts. Until a few generations later, we have a chestnut that is mostly American and is blight resistant. This is similar to selectively breeding other things, like dogs, minus intentionally exposing them to disease. And instead of selecting physical or personality traits, we are selecting for immunity traits. Now I'm generally on team save the trees, but scientists have spent a hundred years trying to save this one tree. They even tried exposing it to radiation in the 1950s to generate a disease-resistant mutation. But this begs the question, why? Is the American chestnut that special or is there something much bigger going on here? A quick note from me, I'm Chris, the founder of Green Belly Meals. We make a 650 calorie ready to eat meal that has been described as a rice crispy treat on steroids. We fueled over 50,000 customers on through hikes, expeditions in Antarctica, even nursing homes. Oh hell yeah. Oh, it's really good. It tastes like a rice crispy treat. It's fantastic. If you want to give our meals a try, check us out at greenbelly.com or the link in the description. Okay, we need to talk about this darn blight and what it took away because understanding it will catch us up to what's going on today with all of these trees dying. The American chestnut wasn't just a common tree. It was the tree in this part of the country. People called it clear day thunder because it was so loud and booming that billions of trees were dying around them. 150 years ago, if you were walking through the forests of Appalachia, one in four trees would have been American chestnuts. They towered and were so important to locals they were called a cradle to grave tree. Cradle to grave quite literally means you were likely born in an American chestnut crib, raised in a cabin made of it, and eventually buried in a coffin made of it. It was an American icon similar to the bald eagle. Chestnuts roasting on an open fire. But around 1904, a fungus from East Asia arrived on imported chestnut nursery stock. It attacks the cambium, the living tissue just under the bark, but it doesn't reach the roots. This is why, somewhat shockingly, there are an estimated 400 million American chestnut sprouts in the country. Meaning they sprout every year, but sometime before they can grow maybe 10 or 15 feet, the blight finds them. The American chestnut was considered functionally extinct because they would resprout. Those would survive for three to five years, but they'd never get old enough to reach reproductive age, which is about five to seven years. So we lost a culturally and ecologically significant American tree. That sucks. But let's get back to why this is bigger than just one tree. I found this study published in 2022. It's a comprehensive and the most up-to-date assessment of U.S. tree species threats. This is what determined that 165 of our native tree species are at risk. Let's look at some of these similar stories of tree populations being decimated and see if you can identify a pattern among them. The American elm. Dutch elm disease arrived in 1928, killed an estimated 77 million elms. Butternut, killed by a fungus called butternut canker, showed up in Wisconsin in 1967, up to 80% are now gone. Beech, beech leaf disease, showed up just in 2012, already spread to a dozen states. Young trees can die within a few years of infection. And if we expand more than just diseases, let's look at the iconic hemlock, killed by an insect from Japan. Today it's wiped out up 80% of hemlocks and parts of the southern Appalachians. And ash trees, killed by a beetle from China that arrived in 2002. Over 100 million trees died in just 20 years. Nearly half of America's native ash species are now threatened with extinction. So what the heck is going on here? Why are all of these diseases attacking our trees at historical rates? When the Spanish arrived in the Americas, came war and conflict, yes, but even more deadly was disease. Smallpox, measles, and influenza. The natives had no natural immunity. Over the next 100 years an estimated 80 to 90% of the indigenous populations of the Americas were gone. Historically, natural barriers, mountains, oceans, deserts, and perhaps pure distance alone, meant diseases and hosts evolved together, often much more slowly. And then we started moving things around with all sorts of timber and lumber and trade. Diseases and invasive species started being exposed to foreign hosts that had zero immunity. Chinese chestnuts co-evolved with chestnut blight for millions to billions of years. And this was a new pathogen. They had no resistance to it. Now, before we start getting all s*** on those foreign trees, this is not a one-way street. You might be surprised to hear we have diseases and species that have caused serious destruction to other populations. As far back as the 1870s, an American fungus called the downy mildew arrived in European vineyards. It nearly destroyed the French wine industry. The American pine wilt nematode arrived in Japan in the 1970s. It has now killed billions of pine trees across East Asia and Japan, Korea, and China. This is a huge ecological problem that has been happening across the globe. And you might've heard how pet Burmese pythons were released into the Florida Everglades have now reduced native species like raccoons and bobcats and rabbits, in some cases up to 99%. Those snakes are not native to the sunshine state and are wreaking havoc on the Everglades ecosystem. Or how just 24 individual European rabbits were released into Australia. Within 50 years, there were hundreds of millions, devastating native habitat. Stories like this are endless. And our trees are suffering from this same spread of invasive species and diseases. So what do we do about it? Is this just the way it is? Disease is inevitable and fingers crossed it doesn't destroy too much. Or are we able to bring them back? If we humans directly or indirectly facilitated the spread of these, we might be able to save them as well. And this to me is the real importance of our friend, the American chestnut. Because this is one of the most significant tree restoration projects happening in the world right now. I'm seeing that now right before my eyes how the emerald ash borer is killing our native ash trees. And I'm wondering how the work that we're doing could possibly help. And the success or failure of the American chestnut and really anything learned could determine the future and at least a playbook for reviving dying tree species across the globe. What we're doing now could be a roadmap for other species. And if we can figure it out through all of this trial and error, maybe it can work for other species as well. We are on our way to the American chestnut foundation in Meadowview, Virginia to check out their research. The ACF is the most prominent research facility on the American chestnut and potentially for any tree reintroduction effort in the world. It turns out their breeding methods have had a big breakthrough. They are able to now take a hybrid leaf sample, send it off to a lab and the lab predicts how blight resistant the tree is going to be in the wild. Gene testing used to be around $1,100 for one sample. Now it's about $20 to sample each tree. So instead of waiting years for their hybrid species to grow large enough to test them against the blight, they now use affordable genetic testing to quickly predict how blight resistant their hybrid seedlings are going to be. We are already starting to do some forest reintroduction trials just to see how things go, find the correct sites and find good partners to work with. Today, thousands of these American chestnuts have been planted across the East Coast with hopes of them eventually growing up and reestablishing their historic range along the Appalachians. Long term, we want these trees to be able to live on the landscape without any human assistance. Now this approach at the foundation is the most popular approach, but it turns out there are actually some other methods and ideas about how to bring back nearly extinct trees. In the early 2000s, a different lab in New York tried genetic modification. They engineered a chestnut tree with a gene that would help it fight blight. For a few years, this was the most promising development in the field. People thought these sort of GMO chestnuts could be in wild forests within a decade. Then in late 2023, it fell apart. The trees didn't perform as expected. Their genetic resistance acted like an overactive immune system and ended up killing the trees from within. And there's a third camp entirely that thinks we shouldn't be engineering trees at all. In Maine, a biologist planted a few American chestnut seedlings back in 1980. He didn't do anything special. Today, there are thousands of wild, younger generations of American chestnuts on his land. None of them have blight, all reproducing on their own. The science isn't clear why. Maine's cold climate might slow the blight down. But either way, his trees have sort of become the poster child for this all natural method. So we have the most popular breeders, the semi-failed GMO engineers, and the more contrarian leave it alone crowd. Seeing which approach succeeds and more importantly, exactly how will be incredibly valuable and will be part of a multi-generational, multi-country effort to help determine how to bring back millions of dying trees across hundreds of species across the globe. We can make this a blueprint for other endangered species as well and other species going through something really similar. Hope you enjoyed this deep dive into bringing back our native trees and forests. If you did, I would love a subscribe. I'll link up to the ACF below if you want to support them as well. Be good. Peace.