Hello my fellow curious critters! This week I have a real treat for you, a guest writer! Keeping on par with my ability to hurt myself doing the stupidest things, I somehow managed to dislocate my shoulder last week in my sleep, which has greatly hindered my ability to type. Thankfully, one of my best friends in the entire world, Jacob Pease, did me a huge favor by writing a fabulous post about his beloved American Chestnut for us. Just when I thought he couldn't teach me anything else about that tree, he surprises me with even more fabulous information. I thoroughly enjoyed his article and I know you will too. So sit back, relax, and learn all about the amazing American Chestnut!
- Alyssa
Welcome back to another shot of knowledge, Curious Critters! Alyssa was kind enough to offer me the opportunity to write this week’s post on something very near and dear to my heart: the American chestnut (Castanea dentata). It is my hope that with this piece, I will help you understand why I consider the American chestnut to be our country’s greatest tree. Mighty sequoias, sky-piercing redwoods, conquistador-stopping manchineel, or the clonal quaking aspen, cannot hold a candle to the American chestnut: the redwoods of the east.
The American chestnut’s rise to prominence, in modern times, begins as the last major glaciation event wanes. Because of the low temperatures created by the glaciers, many species were “squeezed” toward the equator. This squeeze affected oaks, hickories, maples, and many other groups of trees we know and love today – including chestnuts. It is likely that while mankind was traversing Beringia (the ice bridge between northeast Siberia and western Alaska) onto the North American continent, chestnuts were holding steady along the coast of the Gulf of Mexico. At the point when glaciers began to wane, chestnuts and their contemporaries could disperse north again and access ecological vacuums that had been unavailable for tens of thousands of years. Pollen core data suggests that the chestnut slowly crept north – much slower than other tree groups, but became incredibly numerous throughout the historical range starting 2000 years ago.
The American chestnut is the greatest tree in America for many reasons, but I will focus on three in this post. First, the chestnut was incredibly ecologically important; second, the tree was incredibly economically and culturally important; and third, the tree stands to be the greatest bastion of hope for modern forests.
To the first point, the chestnut was incredibly ecologically important. Chestnuts grow on dry, well-drained ridges and slopes throughout Appalachia. If xeric is bone dry and mesic means moderate moisture, then chestnuts excelled in areas between these two conditions – known as sub-xeric. These areas often have poor, acidic soils and are dominated by few species of oaks, hickories, sassafras, sourwood, and black tupelo, among others. Because conditions are so unfavorable for vegetation, it is necessary to have an advantage. The chestnut’s advantage was incredible growth even on the poor, sandy, acidic, Appalachian ridgeline soils. These trees once helped comprise an entire forest type known as oak-hickory-chestnut forests and would drop incredible numbers of nuts every fall. The chestnut was more resistant to late spring frosts than oaks and many other fruit-producers. Chestnuts flower in June or July across their range whereas oaks often flower much earlier in spring and can experience significant mast failures due to frost (mast = fruit). Chestnuts also played a crucial role in nutrient cycling, carbon:nitrogen ratios (link below), and other critical ecological infrastructure.
Economically, one could argue that it is impossible to put a solid dollar value on the American chestnut. Nuts were harvested every autumn and bartered for things that mountain folk either couldn’t make themselves or would be difficult to make. Shoes, salt, steel, books, livestock, and anything else necessary for life that wasn’t readily supplied by the forest were fair game. Chestnuts fed hogs, which became a staple of the Appalachian economy and way of life. Chestnut leaves were boiled to create a cough syrup. Chestnut lumber was comparable to locust, cypress, or cedar in rot resistance and was renowned for its straight and tall growth pattern. The tannic acid in the bark of the American chestnut fueled the American economy that began booming with the expansion of fur trading and tanning industries. The chestnut, for many Americans, became a symbol of Christmas. “Chestnuts roasting on an open fire” rings throughout the halls of American homes to this day. The chestnut was known as the cradle to the grave tree because it could provide the wood for cradles and caskets, nuts to survive winter, fruit for livestock, and livelihoods for the time between the cradle and grave. Think back to the small town roads or the shopping centers, parks, schools, and neighborhoods named after chestnut. Yet, to no fault of their own, many folks don’t give chestnuts a second thought. That wasn’t the case for Appalachians.
You may have noticed by now that everything has been in the past tense so far. There is a reason. In 1904, a new fungal disease was found to be killing American chestnuts in the Bronx Zoo in New York. This disease was brought to the New World on an Asian species of chestnut tree - likely the Japanese/Korean chestnut (Castanea crenata). By the 1910s, the US Forest Service, still in its youth, knew this could become one of the greatest ecological disasters in American history. To read old official documents is like reading the most vivid horror novel or living the scariest dream in which you cannot outrun a pursuer. Efforts were put in place to cut and burn infected trees, quarantine areas, spray fungicides, and more. Vain attempts gave way to vain attempts to stop the loss of America’s greatest tree. The disease, known as chestnut blight, radiated from the Bronx outward at a rate of more than 20 miles per year and reached the Blue Ridge Mountains by the Great Depression. When all was said and done, over four billion trees were lost and millions of acres of forest were devastated. People wept for the loss of a tree that had allowed them and their families to subsist on the land for over a hundred years. To some, it was like losing a family member. To others, it was that and more. As the chestnut died, so too did much of the simple, beautiful, subsistence lifestyle that typified Appalachian mountain communities. This likely contributed significantly to a mass movement of people out of the mountains and into major cities - known today as the Appalachian out-migration.
To this day, chestnuts still exist. Most survive near the forest floor throughout their historic range and rarely make it to maturity. Much like Icarus who flew too close to the sun, the few chestnut stems that do manage to reach skyward are killed back by the blight. There is hope, however. Chestnut blight does not affect the roots of these trees. This allows nodules at the base of the tree to erupt when the main stem dies, and sends numerous small shoots upward around the tree’s base. These shoots are the key to the chestnut’s future, and likely the future of all American forests.
Chestnut blight was not the first forest disease to be introduced to America thanks to humans, and it has not been the last. Even today, our forest trees and ecosystems are threatened by various pests and pathogens. Emerald Ash Borer (EAB) has devastated ash trees. Hemlock Woolly Adelgid (HWA) is causing declines in hemlocks throughout Appalachia. Beech Bark Disease (BBD) has led to the decline of beech trees that are critical to the maple-beech forests of New England. Dutch Elm Disease (DED) has left boulevards and neighborhoods throughout America devoid of the beautifully-shaped shade tree - American elm. Dozens of other organisms threaten the very fabric of America’s wilderness by threatening America’s forest ecosystems.
Thanks to efforts by The American Chestnut Foundation (TACF), their partners, members, volunteers, and donors, however, we have learned a great deal about what it takes to bring a species back from the brink. Breeding programs, genetic research, and ecological studies have brought us to where we are now. In the fall of 2020, the USDA allowed the public to comment on the deregulation of Darling 58 chestnuts, which are genetically modified to resist the blight. This resistance is conferred through one gene, OxO, which is a very common, naturally occurring gene that is heavily utilized by members of the plant kingdom to survive fungal infections. The blight kills chestnuts by creating oxalic acid that causes cankers. Think of cankers as analogous to a sore on the human body. The cankers destroy the xylem and phloem of the tree, which pull water to the leaves and energy to the roots, respectively. However, that acid is rendered harmless when combined with the product of the OxO gene: oxalic oxidase.
It is likely that we are at least a few years away from breeding these Darling 58 trees. The pollen must be combined with regional trees in order to preserve genetic adaptations and then bred again and again to create trees that are well suited to environments from southern Appalachia to Maine. But, the restoration efforts that have been underway since the 1940s have taught us so much about bringing a species back. The chestnut will serve as a model for as long as humans exist on this planet and dedicate themselves to protecting the forests they love and rely on. It is for this reason that the American chestnut is America’s greatest tree. The American chestnut is the pinnacle of ecological, economic, cultural, and historical importance because of the impact we saw and felt when we lost it. Chestnut restoration will serve as the case study that will allow future generations to protect forests into perpetuity. All things considered, the chestnut is truly America’s greatest tree.
For more information:
Refugia – Li X, Dane F. 2012. Comparative chloroplast and nuclear DNA analysis of Castanea species in the southern region of the USA. DOI 10.1007/s11295-012-0538-z
C:N Ratio - https://www.nrcs.usda.gov/wps/PA_NRCSConsumption/download?cid=nrcs142p2_052823&ext=pdf#:~:text=Carbon%20to%20Nitrogen%20ratio%20(C,of%20nitrogen%20in%20the%20substance.
Chestnut Oral Histories - https://scholar.utc.edu/american-chestnut/
Rex Mann Chestnut TedTalk - https://youtu.be/zwvlY8Hll3c
The American Chestnut Foundation - https://acf.org
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