Book Review
The American Chestnut: An Environmental History
(University of Georgia Press, 2021), by Donald Edward Davis, PhD
By Jonathan Sciarcon, Ph.D.
Although American Chestnut (Castanea dentata) is not native to Colorado, Donald Edward Davis’ recent book, The American Chestnut: An Environmental History, holds lessons for those of us who care about the role native keystone species play in Front Range ecosystems. Davis is an independent scholar who has previously published works on the environmental histories of the Southern United States and the Southern Appalachians. In The American Chestnut, Davis demonstrates a remarkable depth of knowledge in natural history, deep history, Native American history, colonial American history, eighteenth, nineteenth, and twentieth century United States social and scientific history, and United States horticultural history, to explain the rapid decline of the American Chestnut and its economic, social, and ecological impacts over the course of the early to mid-twentieth century. Davis also discusses attempts to re-establish the American Chestnut in eastern, midwestern, and southern forests from the middle of the twentieth century through the 2010s.
While I would recommend the entire book to anyone interested in environmental history, chapters 1, 2, 5, 8, 9, and 11 might be of particular interest to Wild Ones Front Range members. Chapter 1 traces the evolutionary history of the Castanea species. Davis shows that over the past 50,000 years, ranges of Castanea species in North America shifted significantly, and sometimes abruptly, as a result of periodic changes to the climate. Chapter 2 discusses both how Native Americans interacted with the American Chestnut and how the latter continued to spread northward in eastern North America right up to the period of European contact. Taken together, Chapters 1 and 2 highlight the dynamic nature of plant migration in response to both climatic and anthropogenic pressures. Two interesting takeaways, at least for me, are that native keystone plants may be able to continue to serve as keystone species when introduced into nearby, though not necessarily adjoining, regions, assuming similar climate conditions, and that we may not be able to adequately classify plants as native to a particular area without conducting extensive historical pollen studies. These points are relevant for urban and suburban Front Range gardeners interested in, for example, introducing plants native to New Mexico in order to respond to a warming climate or adding regionally native trees like Bur Oak (Quercus macrocarpa) or Buckley Oak (Quercus buckleyi) to our landscapes in order to add biodiversity to our neighborhoods and local ecosystems.
Chapters 5 and 8 cover the arrival of diseases that either harmed or devastated American Chestnut populations in the nineteenth and early to mid-twentieth century. The first disease, Phytophthora, also called ink disease, likely entered the United States in the late eighteenth century through East Coast ports. A slow-moving pathogen, Phytophthora was not able to reach all populations of American Chestnuts. Thus, at the beginning of the twentieth century, while some local populations had been significantly reduced by disease, American Chestnut populations, in general, were still intact. This changed abruptly over the next quarter century as another pathogen, now classified as Cryphonectria parasitica (commonly referred to as Chestnut Blight), was introduced by northeastern nurseries that imported Japanese Chestnut trees (Castanea crenata) infected with the fungal pathogen. Forest managers took a slash and burn approach to containing the new disease, destroying healthy populations before they could become infected. As a result of both infection and pre-emptive removal, by the mid-twentieth century, American Chestnuts had largely disappeared from both landscapes and the forests of the eastern United States. As both a gardener and someone who values our Front Range ecosystems, my key takeaway from these chapters is that we need to tread carefully when introducing plants from other continents.
Finally, Chapters 9 and 11 highlight efforts, from the mid-twentieth century through the 2010s, to re-establish American Chestnut populations in eastern forests. Notably, Davis discusses three competing efforts to breed blight resistant American Chestnut populations. The first involves crossing American Chestnuts with Chinese Chestnuts (Castanea mollissima), which have blight resistance. The second attempts to collect seeds from surviving American Chestnuts found in the wild, which, theoretically, may have some level of blight resistance. The third relies on genetic engineering. Davis, in my estimation, skillfully highlights the perils and promises of each approach and concludes that we should be skeptical of all of them. To conclude, Davis’ book is well-researched yet accessible for a general reader and, even though it covers a plant that is not native to our ecoregion or geographical area, has much to offer to practitioners of native plant gardening along the Front Range.
Jonathan Sciarcon is Associate Professor, Department of History at the University of Denver