In the Appalachian mountain region, the loss of the American chestnut, along with the visible scars of coal-related surface mining, have had a doubly devastating effect. However, it is in viewing these two ecological disasters together that the possibility of a solution emerges.
King of the Forest
The forests of eastern North America were once home to the American chestnut, a hardwood species so large that it came to be known as the “redwood of the east.” These giants averaged several feet in diameter and could attain heights greater than 100 feet tall, and some were much larger. The largest reported chestnut was found in Francis Cove, North Carolina, and measured 17 feet in diameter. So dominant was this tree that it grew in pure stands up to 100 acres, numbered in the billions, and accounted for nearly one out of every four trees throughout its range. The American chestnut was a superb timber producer. It grew straight and fast, and often produced three or four 16-foot logs before the first branch was reached. Chestnut timber was prized due to its straightness, beauty, workability, and resistance to rot. These characteristics made it useful for fence posts, railroad ties, telegraph poles, and building construction, as well as furniture and musical instruments. So numerous were its uses that it has been referred to as a “cradle to the grave” species, because one’s crib and casket might both have been constructed from chestnut wood.
As a nut producer, chestnut was unrivalled. Unlike other nut-producing trees such as beech and oak, which flower early, chestnuts flower in late spring and early summer, when the blooms are in no danger from frost, so every year the trees produced a nut crop that could be relied upon by humans and wildlife alike. Each fall, the trees bore an abundant crop of small, sweet nuts that were consumed by rodents, raccoons, bears, turkey, grouse, deer, livestock, and people. Railroad cars were loaded with bushels of chestnuts that were shipped to cities so that pedestrians could purchase freshly roasted chestnuts from street vendors. Farmers turned their hogs loose in the hills so that they could fatten up on the chestnut crop, which not only added to their weight but also lent the pork a sweeter flavor. Virtually everyone in Appalachia, the heart of the chestnut’s range, has a story about this once-mighty tree. The American chestnut was so universally known and loved that more than 900 places in its natural range were named after it (e.g., Chestnut Ridge, Chestnut Run, and Chestnut Church), not to mention the numerous Chestnut Streets found throughout the United States.
In 1904, a forester at the New York Zoological Park noticed that some of the chestnuts on the grounds were dying from an unknown disease. The chestnut blight, or Cryphonectria parasitica, as the disease eventually came to be known, was of Asian import, likely coming to America on infected Chinese or Japanese chestnuts. It was spread through the forests by wind, insects, and animals, including humans. Traveling about 50 miles each year, the blight left decimated forests in its wake. By the 1950s, the entire range of the chestnut had been affected and approximately 4 billion trees had perished. Through this blight we lost an important wildlife and timber tree and nearly one-quarter of the canopy cover of our forests. Many consider the loss of the American chestnut to be the greatest ecological disaster of the twentieth century.
The blight fungus infects the American chestnut through wounds and deep crevices in its bark. The pathogen then grows in the bark and attacks the vascular tissues of the tree, creating a canker that effectively cuts off circulation to the branches above the canker while leaving the root system alive. It is fortunate that the disease does not attack the roots, for young chestnuts with healthy root systems have the capacity to produce stump sprouts. The ability to sprout has retained the American chestnut’s presence in eastern forests, but what was once a dominant overstory tree has been reduced to an occasional understory shrub.
Since 1983, employees and members of The American Chestnut Foundation (TACF) have taken on the task of restoring this once-dominant tree throughout its native range. By crossing the few surviving American chestnuts that reach the flowering stage with blight-resistant Asiatic chestnuts, TACF is creating a tree that will fill the void in our forests created by the loss of the American chestnut.
By conducting controlled pollinations through a series of crosses, backcrosses, and intercrosses, TACF is producing backcross chestnuts that incorporate the Asiatic chestnut's blight resistance while retaining the desirable timber and nut-producing characteristics of the American chestnut. Essentially, TACF would like to breed all Asian chestnut characteristics, with the exception of blight resistance, out of its backcross trees. Each family line within a generation is selected for blight resistance by inoculating the trees with strains of the blight and using only those that show high levels of resistance during successive stages of crossing. In this manner, TACF is currently producing trees that are approximately fifteen-sixteenths American chestnut and one-sixteenth Chinese chestnut. For further information on TACF’s breeding program, see www.acf.org.
A Tale of Two Pathogens
While the blight was decimating the chestnut in the north, a second, lesser-known disease had already been killing the chestnut in its southern range. The disease, a Phytophthora root rot known as “ink disease” or “ink stain disease” due to the black lesions on the roots and stems of infected trees, likely played a role in the rapid decline of the American chestnut and may influence future stands. Whereas chestnut blight is a canker disease that leaves the tree with a functioning root system, Phytophthora attacks the roots, killing the entire tree and rendering it unable to sprout. Phytophthora are categorized as water molds and favor poorly drained soils. Several experiments conducted to evaluate the success of backcross chestnuts planted in forested sites within Appalachia were unsuccessful due to high mortality from Phytophthora. While TACF has been aggressively breeding against the blight, breeding and screening TACF family lines for Phytophthora resistance is still in its early stages and represents the next hurdle for TACF's restoration efforts.
Surface Mines as a Springboard for Restoration
The use of surface mines for chestnut reestablishment is gaining acceptance as numerous successful reforestation projects, following the Forestry Reclamation Approach (FRA), have been demonstrated on mine lands across Appalachia (see www.arri.osmre.gov). Reasons abound for planting chestnuts on fresh mine spoils. First, loose mine spoils reclaimed using FRA techniques have shown good growth and high survival rates for other native Appalachian hardwood species and may also be suitable for chestnuts. Second, many surface mines exhibit light and soil chemical characteristics that are similar to higher elevation and ridgetop positions where chestnuts were dominant. Third, loose mine spoils are initially devoid of vegetative competition, a hindrance to many reforestation efforts. Fourth, fresh mine spoils may initially be devoid of pathogenic microbial communities such as Phytophthora, which have hindered TACF’s breeding and restoration efforts elsewhere. Moreover, loose mine spoils are well drained, which may hinder the establishment of Phytophthora. Lastly, the Appalachian coal region falls almost entirely within the natural distribution of the American chestnut. If loose mine spoils prove conducive to chestnut survival and growth, then the establishment and dispersal from founder populations of blight-resistant backcrosses throughout the range of the Appalachian coal region would aid TACF’s goal of restoring the chestnut throughout its historic range.
In anticipation of the widespread release of the blight-resistant backcross chestnuts, research efforts are underway to evaluate the suitability of mined sites for chestnut establishment, per the FRA, in the Appalachian coal region. Pure American chestnuts and TACF backcross seedlings have been planted on mine lands to serve as proxies for the true-breeding, blight-resistant backcrosses. We are examining differing types of spoil to determine which parent material fosters the best growth and survival for the American chestnut. In addition, studies aimed at determining the best way to establish Phytophthora-free plantings are underway. Most operationally planted reclamation projects use dormant, bareroot nursery stock; however, Phytophthora are present in the soil at many nurseries and may be transported to planting sites on the roots of seedlings. Chestnuts can be established from seed on the mine site to avoid Phytophthora contamination, but rodent predation of the seeds can be as detrimental to survival as Phytophthora. Different planting techniques are being evaluated (e.g., direct seeded versus bareroot stock, use of tree shelters versus no shelter, fertilized versus no fertilizer). Much has been learned from this research and many successful plantings have been established. Not only is survival high in many mined locations, but Phytophthora has only been detected in one sample from a spoil that contained residual soil material from the pre-mined site. Soil samples tested from unmined forests in the region yielded high (80 percent) Phytophthora detection rates.
The Path Forward
Appalachia is one of the most beautiful and culturally rich regions in America. The heritage of Appalachia has been rooted in the forest and coal industries for centuries. Appalachia has experienced many hardships related to environmental degradation from coal mining, but the loss of the American chestnut was particularly troublesome to its citizens. At one time, virtually all of the land mined in Appalachia was forested. Where once there were forests, we now have abandoned grasslands that will take Mother Nature centuries to restore. Recently, TACF and the Appalachian Regional Reforestation Initiative (ARRI) developed a program to both promote the reforestation of mine lands in Appalachia and restore the American chestnut. This program, referred to as “Operation Springboard,” has been embraced by the mining community, environmental groups, and Appalachian citizens alike. In 2009, 520 volunteers and nine separate nonprofit watershed groups held tree-planting events on 36 acres of surface mine land and planted 27,500 trees. In 2010, over 175 acres have been committed for volunteer planting events, and nearly 115,000 trees will be planted. American chestnuts were planted on each of these sites, and many times they provided the incentive for volunteers to join in the planting events. The act of planting the American chestnut within its native range is important, but using the chestnut to promote reforestation efforts (all forested species) on these mined lands may be more significant because it brings individuals with opposing views on mining together (miners with environmentalists; teachers with students; elders with children) to engage in conversations about conservation, sustainability, and the future well-being of the region. These conversations, and the outcomes produced from them, are the true measures of success and progress. Ultimately, we hope these efforts will lead to the restoration of the American chestnut and the forests it once inhabited.