A silvicultural synthesis of sweet (Castanea sativa) and American (C. dentata) chestnuts

Abstract

Sweet chestnut (Castanea sativa) and American chestnut (C. dentata) have been explicitly linked to ancient, historical, and contemporary cultures while enhancing ecological services in forests in which they occur. Threats that currently face these chestnut species are unprecedented and additive, including global climate change, nonnative pest and pathogen species, land use changes, and lack of scientific knowledge and technologies. In this paper, we provide a synthesis of traditional and novel silvicultural systems for chestnut, focusing on these two important species. We frame the discussion within the context of the species’ cultural and ecological significances, scientific knowledge bases, and associated knowledge gaps. Sweet and American chestnuts require divergent strategies to sustain their conservation values due to differing cultural and ecological landscapes and biological stressors. Both species share the need to conduct active forest management to maintain or restore populations in native or naturalized habitats. Even-aged management is the preferred regeneration method for both species. Coppicing that is commonly implemented for sweet chestnut can provide a potential strategy for American chestnut once disease-resistant material becomes widely available. Blight caused by Cryphonectria parasitica may limit long rotation timber production of American chestnut, even for resistant material, making short-rotation systems a more attractive management option. Advanced artificial regeneration and breeding strategies have been developed for American chestnut but are largely underdeveloped for sweet chestnut. High forests of sweet chestnut can play an important role in new single or mixed species plantations, naturalized stands, or in naturally regenerated stands for production of medium-large dimension timber. American chestnut will likely be managed as a minor to moderate component of mixed species forests to achieve ecological restoration goals. A close-to-nature silvicultural approach has not been tested for either species and may be difficult to implement due to the threats from changing climate conditions and nonnative pathogens. Traditional and emerging markets of sweet chestnut, such as biomass or carbon markets, may help inform future opportunities around American chestnut for tribal and rural communities. Climate change and other threats call for synergistic partnerships and knowledge sharing to maintain or restore sweet and American chestnuts as part of the global ecosystem.