American Chestnut

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The American Chestnut, Castanea dentata (Marsh.) Borkh., was once one of the most common trees in the eastern United States.  An important ecological and economic component of American forestry until the early 20th century, the American chestnut population began to rapidly decline due primarily to an introduced fungal pathogen, the Chestnut blight [Cryphonectria parasitica (Murrill) Barr].  It is believed that the fungal blight was introduced by the importation of Old World Chestnut varieties, such as the four Castanea species found in Asia: C. mollissima Bl., C. henryi (Skan) Rehder & Wilson, C. seguinii Dode. in China and C. crenata Sieb. & Zucc. in Japan.  Today, the American Chestnut survives in low densities and poor condition, mainly due to the repeated regrowth of sprouts from surviving root masses.  The sprouts are eventually re-infected and die back.  Restoration efforts are underway and consist of traditional approaches, such as inoculating infected individuals with fungicides, as well as an extensive genetic hybridization program lead by the US Forest Service aimed at producing a blight resistant American-Chinese chestnut species for reintroduction.  These breeding programs are dependent upon the collection of a diverse sample of American Chestnut gametes in order to maintain as much genetic diversity as possible in the restored population.  Therefore, determining the location of mature, breeding C. dentada individuals is necessary to the success of the genetic hybridization restoration efforts.  Additionally, more accurate information on the current distribution of the species would provide the opportunity for further analyses focused on plant-pathogen ecology, climate change adaptations of threatened tree species, and biological conservation.  With these goals in mind, we have complied information from The American Chestnut Foundation (ACF) and the Appalachian Trail MEGA transect project, which have coordinated the counting of individual American Chestnut trees along thousands of miles of the Appalachian Trail from Georgia (GA) to Maine (ME) since 2008.