Toward development of silvical strategies for forest restoration of American chestnut (Castanea dentata) using blight-resistant hybrids

Backcross breeding has provided a viable means to restore American chestnut (Castanea dentata (Marsh.) Borkh.) to eastern North American forests, where the foundation species was essentially extirpated by an introduced pathogen. With the prospect of American chestnut reintroduction imminent, it is critical to formulate restoration strategies based on the ecology and silvics of the species, operational confines, social or policy limitations, and ecological implications. American chestnut was apparently adapted to a relatively wide range of site conditions, has evolved a capacity to survive for prolonged periods beneath forest canopies yet respond rapidly to disturbance, and demonstrates extraordinary growth and competitive ability. These characteristics are discussed in reference to operative planting techniques and potential for migration of regeneration from hybrid chestnut plantings into forests of the original American chestnut range. The use of hybrid trees for American chestnut reintroduction may generate social and policy ambiguities that require conciliation. Additionally, potential long-term ecological implications associated with reintroduction of American chestnut to the original species range, or introduction to areas outside its original range, must be realized and integrated into reintroduction strategies. Limitations in genetic fitness, potential for disease mutation, and threats from other exotic insects and pathogens may serve as continual challenges to American chestnut restoration. This paper helps establish preliminary guidelines for restoration plantings and creates awareness of imposing ecological issues and barriers that must be overcome to successfully restore American chestnut to its natural range, while simultaneously maintaining ecological integrity and ensuring conservation benefits to eastern North American forests.