Restoring the American Chestnut Tree with Dr. William Powell and Rex Mann
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In July 2022, we brought you one of our favorite episodes about the restoration of the American chestnut tree. This tree species, which had been so vital to the establishment and flourishing of the United States, had been long assumed to be extinct. But the work of one pioneer, Dr. William Powell, changed that story.

Through the efforts of Dr. Powell, his colleagues, and countless citizen volunteers, the American chestnut tree has a future. We are sad to share that Dr. Powell passed away from cancer at the age of 67, just a few weeks before Thanksgiving.

We want to acknowledge our respect and gratitude for this cutting-edge scientist, this gentleman who inspired generations of scientists and the Stories of Impact community. Today, we're replaying the American Chestnut episode. But before we do, Richard has a few words. On my journey of understanding science and technology,

Bill Powell is one of those extraordinary researchers who brings together a pure love of academic science, but also pure research that is aimed at helping the world. His mission was to understand the demise of one of the icons of American history, the American chestnut tree.

which was wiped out very early in the 20th century, and this amazing thought of, can we bring it back to life? And he dedicated decades of research and work to genetically engineering a new American chestnut tree that would be blight resistant. Now, we all admit there is controversy around genetic engineering.

But to Bill's point, which you will hear in the story that unfolds, this is a very specific use of genetic engineering to bring back an American icon and would not endanger the world in any way, would contribute to conservation, and would contribute to America's history. We've lost an enormous mind

Welcome to Stories of Impact. I'm writer-producer Tavia Gilbert, and every first and third Tuesday, journalist Richard Sergei and I bring you conversations about the art and science of human flourishing.

Today is the penultimate episode of our fifth season of Stories of Impact, an inspiring story about how bringing together vision, community, and cutting-edge science can make the impossible possible. It's a story about American history, climate, globalization, and hope. And it begins with Rex Mann.

Rex Mann retired from the U.S. Forest Service and started volunteering with the American Chestnut Foundation. The foundation's lead collaborating scientist, Dr. William A. Powell, professor at SUNY College of Environmental Science in Forestry, also joins us today.

Dr. Powell and a fleet of scientist supporters and citizen volunteers like Rex Mann have set out to do something never before done. To restore a tree that is virtually extinct by using genetic engineering to develop a blight-tolerant American chestnut tree.

Why is the American chestnut tree so important to all of the people working on this first-of-its-kind restoration project? Rex Mann shares the history of the amazing American chestnut. Particularly for those early settlers who lived in chestnut country, in some ways there were more hunter-gatherers than there were farmers. This was in the days before roads, and they went into brand-new country

And to a great degree, they raised a few crops for their own use, but they survived off the land. A lot of these early settlers probably wouldn't have made it had it not been for the bountiful wildlife that was there. Because of the benefits of the tree itself, I personally think the value of the tree probably had more impact on our history than say the Liberty Bell or the American Eagle, both of which I treasure.

But I think that tree really played an untold role in the development of this country. I've heard stories that in the fall of the year, everybody that lived in the mountains would gather sacks full of these chestnuts and take them down to the local store and barter it for things they had to have that they couldn't raise, like salt, coffee, or a new pair of shoes for the winter for the kids.

The storekeepers, they finally made their way to the railroad lines and there would be train loads of chestnuts in the fall heading to the major cities of the country where they would roast them and sell them on the streets.

So it was a big part. It was mostly the cash money that these people got because they lived off the land. Aside from the benefits of the tree for lumber and so forth, it was a basic part of how they lived. Before the blight that decimated the American chestnut tree arrived on American soil, the tree played a role in sustaining virtually every aspect of life in America.

Chestnut not only helped feed them, it fed their livestock. It was free-ranging livestock. And a big part of their diet was the wild game that was there in such abundance, and it was largely because the chestnut was there. The wood, it was a preferred species for building log cabins because it was so rot-resistant. The wood was easy to work with.

And it was the go-to species for anything that was going to be exposed to the weather. So it just played a huge part in their life. And even today, when you talk to the grandchildren of these folks who saw the death of the chestnut, even though they never saw a healthy chestnut in their life, they heard the stories and they still know what you're talking about. And there's still a deep passion to restore this tree.

Rex Mann says the chestnut tree is unlike any other tree species. It's special. Chestnut is an amazing species. Over that 50 million year history that it's been around, it has survived numerous ice ages, global warming events, moved back and forth across the landscape of North America.

It has the amazing ability. It's almost evolved for long distance transportation. The American chestnut is just about the size of an acorn. And what spread the tree was primarily squirrels and blue jays that harvest these nuts. They fly off and they bury each one of those nuts.

The blue jay is the only bird I know of that stores food for the winter. And they're able to recover most of these thousands of chestnuts or acorns that they move. But they miss a few. And these germinate and they grow. They have the amazing ability to survive in deep shade. They can sit there with almost no growth for decades, patiently waiting for a disturbance to create an opening in the canopy.

and then they can outgrow almost every species that grows in the woods, and they reach that opening. They normally grew head and shoulders above the rest of the competing trees, and once there, they were there for centuries. They could live to be several centuries old, and became this foundation species and exerted a powerful influence on the forest and everything that lived in the forest.

So it really wasn't just another tree. It was an extraordinary tree. And here's Dr. William A. Powell. Most people think of chestnut as the nuts being the most important thing of the tree, but actually the whole tree is important.

And the leaves that fall off the tree and form the leaf litter on the ground is also extremely important. So one of the things that this leaf litter can do, it could fall into little ponds or vernal pools, and this is where frogs replicate, you know. So we want to make sure that the tadpoles of these frogs, if they were eating our genetically engineered trees, would do the same as they would if they ate the wild type.

And that's what we found. There's really no difference between our genetically engineered leaves or the wild type leaves. In fact, it's kind of interesting because in the study we found something out that we weren't really expecting because we were also feeding the frogs things like maple leaves, beech leaves,

And when we looked at the development of the frogs, they actually did better on the American chestnut than, let's say, maple or beech. You know, chestnut wasn't just another tree. Ecologists today recognize it as what they call a foundation species. There are a few trees that have such a powerful influence on that forest system.

They can control, make up what other species are growing in that forest. They have a huge impact on productivity of the forest. And to a great degree, that foundation tree, this American chestnut, controlled wildlife numbers and the health of the wildlife. When the foundation collapsed, the system collapsed. And it's recovered, the oak trees and other species,

took over the growing space that the chestnut was in, but it's a far different forest system than what was there a century ago.

The blight that arrived in the early 1900s devastated the chestnut, killing billions of trees. Loss of the chestnut was without a doubt the greatest environmental disaster ever to strike this country. I know of no other environmental disaster that had such far-reaching effects as the chestnut blight. Because the thing grew on 200 million acres at the time of the blight. Almost everywhere where people lived

alongside the chestnut. It played a big part in their life. How do Rex and Dr. Powell explain the blight? It was an imported blight, first seen in Brooklyn, New York City. A lot of valiant efforts to try to stop the blight, but none of them worked.

Eventually it killed almost all of them. They were abundant all along the Appalachian Mountains. In some areas, you know, they represented up to 25% of the canopy.

And we lost all that because we started importing Asian species of chestnuts for horticulture and agricultural purposes. And what people didn't realize is when you bring over those trees, you're not just bringing a tree, you're bringing over all the microbes on those trees. And it turns out there was a fungus. You only cause minor damage on the Asian species, but on American chestnut, which was naive to it, caused very serious damage.

That jumped off those trees onto the American chestnut and within 50 years killed over 3 billion of some of the largest trees in our eastern force. What was the impact of the blight and the death of billions of trees? There was a collapse of wildlife. There were certain species of insect that went extinct when the chestnut was no longer around. Almost every species of wildlife that lived in the forest fed on chestnuts.

And populations collapsed and it took decades for these species to recover to some degree. But it probably had a greater impact on the people. This disaster occurred kind of simultaneously with the Great Depression.

And at that time, the mountain people heavily depended on their livestock, particularly pigs. And a common practice was to fatten those hogs on chestnut. It was a very nutritious way of raising their stock. When the chestnut died down, these people were so dependent on their livestock, they had no money to go to the store and buy feed. Thousands of them left the mountains.

They had no other way to make a living. They went to the big cities looking for any kind of work that they could. So not only did it have an impact on the wildlife and the rest of the forest, but it had a tremendous impact on the people who lived there. Despite the blight and the loss of the vast majority of the tree population, the American chestnut tree had astonishing resilience. The chestnut tree is so special, in fact, that it's primed to be brought back to life.

So the great thing about chestnut is that it can actually survive at the roots. So the blight can kill it down to the ground, but the soil actually protects the roots from the blight. And therefore, the roots still survive and the tree has the ability to sprout from the root collar.

And that will send up new shoots. It can grow for a while. It'll get the blight again, get killed back down, kind of goes through that cycle. Eventually the roots run out of energy and it dies. But there's still probably several million root sprouts out there. And that leaves us with a bunch of hope because once we develop the resistant tree, which we have done actually, you can then outcross that tree to the wild trees and build up a nice diverse population for restoration.

So the chestnut tree can be brought back from functional extinction, but why should it be restored? The chestnut was important to America in the past, but why is it important today? You know, a forest is not just a collection of trees that just happen to randomly be growing together. You know, it's a system. It is a system that includes everything that lives in that forest.

Not only the vegetation and the trees, but the wildlife, the people. We're part of that system. The forest that existed when our ancestors first came here was very, very resilient. Like I say, it had gone through ice ages and global warming events, but when you begin to lose species, you really diminish that resilience that the forest has. Yes, it'll recover.

There'll be a forest, there'll be a green forest out there of some sort, but it's much different from the forest that was there. Most of the medicines we use today, they first arrived on from plants or animals.

Who knows what's out there? So it's very foolish on my opinion to allow something to disappear if we have the capability to bring it back. And I believe for the first time in history we're approaching that point. Our knowledge is really increasing. It's almost breathtaking how rapidly science is advancing. If we don't have those answers, we will soon. So I think for the first time ever,

We're entering a doorway where we can bring these species back, and I believe we should. We have almost a moral obligation, I believe, to do that. And we're getting close. We're making tremendous progress, and I believe it'll happen. I really do. What would the benefit be of restoring the American chestnut tree? The benefits of bringing that tree back. We love our woods, and we love to take our kids and grandkids

I think without a doubt that you would see an increase in most of the wildlife species. They would have to be in healthier condition because winter is the tough time for wildlife and this bountiful chestnut crop came about just before winter came. So they entered the winter in much better shape than they generally are today.

Healthier wildlife has more offspring and healthier offspring than hungry wildlife. So I think you would see a dramatic increase in the productivity of the forest, the impacts on our people. Why is this project so personal for RACS? When I was a senior, many half a century ago, in forestry school,

at North Carolina State. I remember a seminar in my senior year when somebody who worked for the outfit I gave my life to, the U.S. Forest Service, came in and I remember them saying, "Chestnut is gone. It's gone forever. Forget about it." And at the time, I accepted that. So when I heard the story of the American Chestnut Foundation,

which was utilizing the best science we had at the time. Hey man, we can restore that tree. It was like a door opening. I grew up in the southern Appalachians in North Carolina from a very poor background. My dad witnessed the entire chestnut story from the time of the healthy chestnut forest. In his midlife, he saw the blight begin to take effect.

and he saw the forest without the chestnut. So I grew up hearing these stories all my life and had a powerful influence on me. As I finally realized it wasn't just another tree. This was the foundation of a culture that's not here anymore. So I was always fascinated by the story. I became a forester for 42 years and early in my career

I could still see the gray ghosts, the trunks of the old dead chestnuts, still standing, almost gazing down at me as I worked in the woods. And I understood why my dad felt so sad about the passing of the tree. After a career with the American Forest Service, Rex has a unique perspective on forest health and the role of this particular special tree. Very few people understand

have a glimpse at the big picture, what's happening to our forests. I was really saddened by the other losses that are occurring in our forests right now. We have lost American elm. We're currently losing millions of eastern hemlocks. We're losing probably billions of ash trees.

A new disease is setting up in Tennessee that has the capability of killing all of our black walnut. Most of our butternut or white walnut is now gone. And there is a disease that is quarantined in Northern California, the sudden oak death. But if that thing ever makes it to the East Coast, it has the capability of taking out all of our oak trees.

So when I think of chestnut, I think of it in that context. Most of these losses are somehow tied to world trade. World trade has made us the greatest, richest, most powerful nation in the world. We're not about to stop world trade, but I think that if we're not able to restore the chestnut

People just become hardened to these losses, you know, and say, "Oh well, lost another tree." And all the while, when we're losing these trees, our forests get poorer and poorer from a diversity standpoint. They're not nearly as productive. We're changing everything. And I don't think you can do that. I think it has far-reaching implications. Again, I believe that's the real significance of what we're doing.

is laying a foundation, a model, so that we can awaken our people and we can bring back these other species. Species restoration requires collective action and creative collaboration. You can't do this without partnering up with the true scientists, the ones who figure out exactly what causes this blight. How can we defeat it? So it is a partnership. So

When I heard about the American Chestnut Foundation coming along, I joined up. After my retirement, I'm working full time, whatever I can do to try to bring this tree back. I think of myself in my old age as a chestnut evangelist, if you will. You know, I'm very optimistic that I won't live to see it, but we're going to restore that tree.

But the encouraging thing, particularly with the young people that I meet, is once they hear the story, they're on board. They want to help do something about it. So I'm very hopeful that we can do something that has never been done in human history. We're going to bring a tree back. So, hey man, I'm on board. And we'll be until I'm too old to do anything about it. Rex isn't alone in his passion for the chestnut and the restoration project.

There is tremendous desire on the part of the descendants of the early settlers and other people in the East to bring the tree back just because it was the foundation of the system that existed then. But the bigger story, I think, I think history would probably validate someday.

that the greatest accomplishments of the American Chestnut Foundation, Bill's work on helping restore that tree, is not just the restoration of that iconic tree, but it's laying a pathway

for how other species can be restored. There may be some that have disappeared so long ago that it would be much more difficult to bring them back. You want to make sure that it makes sense to bring something back. Chestnut, we know it does. How are they bringing back the chestnut? What's the science behind the restoration project? Kind of lucky we found a gene that can disarm the fungus.

Basically, it's a gene that a lot of plants have. It's used to detoxify an acid called oxalic acid. When we first thought about the oxalate oxidase gene, actually one of our postdocs returned from a meeting and she brought the book of abstracts. And I was leafing through it and came across this abstract where someone was using oxalate oxidase in tomatoes.

to enhance fungal resistance. And I read it and I saw how it worked. And I said, wow, this harkens back to when I was a graduate student. I know that the fungus that attacks chestnut produces oxalic acid to help kill the tree. And so we put two and two together and there you go, Eureka. We just needed to get this enzyme into the chestnut tree to give it resistance to this acid and therefore allow it to coexist with the blight.

And how is Dr. Powell's work progressing? We have been very successful as producing trees that are as resistant as the Asian species. And who knows, maybe even a little bit more than the Asian species. But we have a tree that now can coexist again with the blight. And therefore, you know, it's ready to be tested out in the field in a restoration program.

The project offers a vision for broader species restoration efforts. I like to see this as a model system, again, that we can possibly save other trees. I mean, our forests are really being challenged right now. There's something like...

I don't know, around 15 pests and pathogens that could possibly wipe out 40% of our forests in the near future that need to be addressed. And, you know, genetic engineering isn't the only tool. We use actually lots of different tools with genetic engineering. It's not the magic bullet, but it's definitely a powerful tool that we can use with it. So I'm hoping that

This chestnut project will be a model that we can then show how you can save other trees using these methods. It makes me feel very hopeful. It makes me feel absolutely sure we're going to do this job. We're going to restore this tree. I don't have a doubt in my mind, so I feel very good about this. Restoring the tree is physically demanding work, but it's work that matters deeply.

And the success of the project also offers a positive spiritual impact, as well as an ecological one. But the real job is putting that tree back into the woods. And as a forester, and knowing something about the cost and the trouble to physically go in there and plant these trees, it's almost overwhelming when you look at the huge range of that tree.

But again, I think that there will be cases where individuals decide, yeah, I'm going to do that, even if it's at great expense. But in many cases, the tree will make its way back probably the way it did after the last ice age. Yes, it will be people, squirrels and blue jays that eventually spread that tree into the territory it once occupied.

One of the oldest admonitions in human history is to be good stewards of the land. That means retaining what's there and let's keep it, not for ourselves, but for those that come after. And I think most people, most Chestnut champions are wired up that way. That's what they want to do. This is their way of leaving the land in better shape than it was when we came along. Many of them will be able to say, I helped make that happen.

We helped with that. We brought that tree back. I think that's appropriate. That's what we should do. And I think, again, that's the big benefit of what we're doing here is laying the groundwork and creating a model where we can start to work on these other species that we're losing. And if we don't do that, it's catastrophe. We'll never bring the culture back, but if we can restore the tree

that can fulfill the same role that it has fulfilled for 50 million years. It'll come out all right. It'll compete. It can make its way, I believe. Getting the people involved in doing something on this scope of bringing back a tree, in the long run will bring our people closer to the land. I think they'll have great pride in what they did.

That's the bigger story, I believe. That'll be the greatest accomplishment that we can make. Our battered human hearts desperately need stories like this and projects like this that combine vision, science, and collective effort. We need to know that we can work together to solve problems that seem insurmountable, to find solutions that will support health and well-being of our ecosystems and our communities.

I love this story. It gives me hope for a thriving future and a healthier planet. I hope it offers you the same. We'll be back in two weeks for our final episode of the season with a conversation with Dr. Andrew Sarazin, Executive Director of Templeton World Charity Foundation.

We'll review what we've learned this season, and we'll look to the future of Stories of Impact and the work of Templeton World Charity Foundation as it continues to support projects that develop the art and science of human flourishing. If you appreciate the Stories of Impact podcast, please follow us and rate and review us. You can find us on Twitter, Instagram, and Facebook, and at storiesofimpact.org.

This has been the Stories of Impact podcast with Richard Sergay and Tavia Gilbert. Written and produced by TalkBox Productions and Tavia Gilbert. Senior producer Katie Flood. Music by Alexander Filippiak. Mix and master by Kayla Elrod. Executive producer Michelle Cobb. The Stories of Impact podcast is generously supported by Templeton World Charity Foundation.