One hundred years ago, forests looked very different than they do today. Before 1900, “one in every four hardwood trees in the North America’s eastern forests was an American chestnut,” writes Ferris Jabr in an article published by Scientific American. Their flowers were so numerous in the spring that “from a distance, the hills appeared to be draped in quilts of snow.”
Today, that image is hard to even imagine. On an ill-fated day in 1876, the first Japanese chestnut trees was imported into the United States by S.B. Parsons. On these trees came Cryphonectria parasitica, a fungus “which chokes chestnut trees to death by wedging itself into their trunks and obstructing conduits for water and nutrients.” Within 50 years, four billion chestnut trees had died.
American chestnuts not only provided beautiful scenery, but critical habitat and food sources for a variety of other organisms. Their large crops of acorns fed the animals we know today in the forest, in addition to the passenger pigeon, one of America’s most famous extinct species. Though hunting undoubtedly played the largest role in the passenger pigeon’s extinction, they were also losing critical food supplies as chestnuts withered away.
As they died, chestnut trees created light-filled gaps that were quickly filled by “sun-loving saplings, blackberries and greenbriers. In addition, “Oaks, maples, and tulip trees became more numerous, claiming real estate that chestnut might have occupied.” As the fungus spread across the United States, it left changed ecosystems in its wake.
While a few saplings have managed to grow here and there, they are all that is left of the once great chestnut legacy. However, this tree tragedy may be slated for a positive plot twist. Scientists have spent decades “mating American chestnut with blight-resistant but much smaller Chinese chestnut,” and have also genetically engineered “transgenic trees that are almost 100 percent genetically identical to wild American chestnut yet immune to C. parasitica.” Researchers hope these trees could eventually spread over large areas of their historical habitat.
As we celebrate Arbor Day this Friday, it is important to remember that American chestnuts are not the only native species being decimated by an invasive species. In a previous “The Dirt” blog post, we described the ongoing hemlock destruction being wrought by the woolly adelgid. Ash trees are also being decimated by emerald ash borer larvae interfering with trees' water and nutrient flow. Though there is hope, it is important to support researchers as well as practice good wood practices, including avoiding the transport of firewood and reporting invasive species in your area!