Recovery Plan

Proposed National Recovery Plan for American Chestnut

In 2000, a Proposed National Recovery Plan for American chestnut was developed through funding provided by the World Wildlife Fund to Drs. John Ambrose and Greg J. Boland. The front cover and summary of this plan are reproduced below.



Summary of Recovery Plan

American chestnut (Castanea dentata) was a dominant forest tree species in northeastern North America before populations were devastated by the introduction in 1904 of the fungal pathogen, Cryphonectria parasitica, which causes chestnut blight. By the 1950s, American chestnut had been devastated throughout its native range. In southwestern Ontario, populations of American chestnut were reduced to far less than one percent of the original 1.5-2.0 million trees estimated to have been present. In 1987, American chestnut was designated as a “threatened” species by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).

American chestnut still survives as remnant populations and individuals throughout its native range mainly by resprouting from surviving root collars. During 1994-97, American chestnut was identified at 135 sites in southwestern Ontario, and the number of individuals per site ranged from one to numerous (average of 3.1). Approximately 58% of the sites contained only one tree or regenerating clump. About one-half of the sites containing surviving chestnut were located in Elgin and Haldimand-Norfolk counties. In addition to chestnut blight, American chestnut may be adversely impacted by loss of habitat, potential hybridization with introduced chestnut species, and the possible introduction of a gall wasp from the USA.

The long-term goal of this recovery plan is to restore American chestnut to self-sustaining (i.e., demographically viable) populations throughout its native range in Canada.

The long-term strategy of this recovery plan is to identify and implement actions required to maintain or establish self-sustaining populations of American chestnut. Chestnut blight continues to have the greatest negative impact on populations of American chestnut, although other factors such as the loss of habitat and possible hybridization with other Castanea species are also of concern. Until chestnut blight is controlled, restoration of American chestnut to a more secure position in the Carolinian forest is not likely. Therefore, long term strategies to control chestnut blight are critical. Potential strategies include hypovirulence (a viral infection that weakens the blight fungus), natural resistance to disease, and breeding for disease resistance. Although hypovirulence has been successful in controlling blight in Europe, there has been less success using this strategy in North America. Renewed studies may identify factors that contribute to increased efficacy. Significant resistance to blight has not been observed in surviving populations of American chestnut but concerted attempts have been made to identify such resistance. Finally, breeding programs using resistance genes from Chinese chestnut are underway in the USA, and increased emphasis could be placed on incorporating this resistance into germplasm adapted to environmental conditions within the native range of

American chestnut in southwestern Ontario, although it is questioned whether this tree improvement technique is appropriate for a recovery strategy.

In the short-term, emphasis should continue on the conservation and management of genetic diversity of American chestnut adapted to the native range in southwestern Ontario. To accomplish both short- and long-term goals, the following recovery objectives are proposed: 1) identify and protect populations of American chestnut within its native range in Ontario and promote self-sustainability in at least 15 core populations, 2) develop and assess management strategies for chestnut blight, and 3) identify blight-free stands of American chestnut outside its native range and protect and maintain at least seven stands.

Initiation and/or completion of these recovery objectives will contribute to increased knowledge and conservation of remnant populations of American chestnut in Canada, assess short-term strategies for improved management of chestnut blight within selected populations of American chestnut , and initiate and/or assess long-term strategies for more stable management of chestnut blight throughout its native range. This plan will also serve as a template to address the needs of other disease-threatened tree species, such as butternut and white elm, and provide a framework for public awareness of these conservation issues.