Working Party 1.01.13
Ecology and silviculture of chestnut

The Working Party on ecology and silviculture of chestnut (Castanea) includes a team of researchers with expertise in forest management, ecology, and silviculture. The prerogative of the group is to INCLUDE researchers actively interested in PROPOSING, PARTICIPATING and SHARING common research ideas and themes. Goals of this group are to provide knowledge and promote research and management activities that:

1. improve production and sustainability of Castanea forests to serve economic, social, and ecological needs,
2. restore Castanea trees where they have been extirpated or largely reduced due to non-native pests or pathogens,
3. improve resilience of Castanea to impacts from climate change,
4. innovate in multifunctional management approaches of Castanea forests towards valuing of and payment for ecosystem services.

Given the wide range of products and functions provided by the Castanea forests, the research group will strive to interact with other units within Division 1 and across other Divisions

STATE OF KNOWLEDGE

Chestnut holds an important cultural significance for communities across much of the globe and were historically principal tree species in many temperate forests (Beccaro et al. 2019). In eastern North America, chestnut seeds created their own currency when they were bartered or sold for other goods and services (Lutts 2004). Chestnut wood was some of the most versatile of all hardwood species in North America, used to produce staves for whiskey production, rot-resistant timber, and tannic acid for leather production (Ziegler 1920). Loss of the American chestnut had untold consequences ecologically because the tree was vastly abundant and widespread; its loss impacted food webs and other important ecological functions like water and soil dynamics (Clark et al. 2019).

Due to decades of efforts from genetic and breeding programs, trees are being produced with varying levels of resistance to diseases such as chestnut blight and Phytophthora root rot. Restoration will require more than a pest-resistant tree however (Clark et al. 2020), and silvicultural strategies will need to be developed for reintroduction of the chestnut into forested environments. The complex interactions between chestnut, its associated pests, and the environment have yet to be fully tested and are not well understood (Griffin and Elkins 1986), particularly in the context of climate change. Additionally, concern exists among managers, landowners, and Indigenous groups that chestnut restoration could negatively impact economic or cultural values by displacing valuable trees species like oaks (Quercus) and by introducing a genetically engineered tree (Barnhill-Dilling and Delborne 2019).

In Europe, the most traditional chestnut coppices originate from the Roman approach: relatively short rotations, in order to produce small to medium-sized poles, firewood, and charcoal. After World War II, this type of management experienced a deep crisis with the changes of the socioeconomic structures in rural areas. Recently new silvicultural methods have been proposed (Manetti et al., 2006; Marcolin et al., 2020) with the aim to give multiple ecosystem services (e.g. protective function, environmental and biodiversity conservation, quality wood production, maintenance of the social component and the cultural heritage).

There are complex challenges to sustain and restore chestnut forests due to the historical management regimes related to cultivation and abandonment as well as disease pressure from chestnut blight and Phytophthora species (Manetti et al., 2018; Marcolin et al. 2020). As in eastern North America, the European chestnut has wide versatility in wood products, but revival of chestnut coppice stands is often perceived as uneconomical to landowners (Patrício et al. 2019) or not sustainable by environmental associations. New management approaches are required. Research on the efficacy of silvicultural treatments are needed to encourage participation in coppice and high-forest management, particularly on lands that are privately owned. The forest plantations of the Castanea sativa increased remarkably over the last two decades under the European Union. Support Frameworks with an estimated rate at 4500 ha year-1 of afforestation in Portugal, northern Spain and France (Alvarez-Alvarez 2004). The private owners have been the driving force behind this increase in sweet chestnut afforestation area introducing a growing trend toward high-quality wood production that, when combined with non-wood forest products and ecosystems services, can become a profitable investment for forest owners (Patrício and Nunes, 2017). The production of long-lived products is of great interest in mitigating GHG emissions.

Asian chestnuts are the most diverse, representing six of the thirteen chestnut species in the world. However, management of Asian species seems largely relegated to forest tree improvement for nut production. Ecological studies have shown that management could be used to improve chestnut regeneration (Seiwa et al. 2002). Silvicultural strategies to maintain or improve upon existing chestnut resources in Asia are largely unknown.

Climate change, social perceptions, economic markets, and the never-ending spread of non-native pests and pathogens are challenging sustainability and restoration of chestnut species and forests across the globe (Waring and O’Hara 2005, Stanturf et al. 2014). Across all chestnut species, knowledge gaps exist in understanding the ecological and cultural impacts of chestnut management or restoration on already novel forests. Silvicultural prescriptions to restore or maintain chestnut species have not been fully tested, particularly in the context of climate change or as part of an integrated pest management approach.

Attempts to compile and improve upon existing knowledge on the silviculture, management, and ecology of chestnut has been conducted on a species level (Jacobs et al. 2007, Wang et al. 2013, Clark et al. 2014), but never on a multi-species, multi-continent scale. Recent advancements in modelling, genetic and breeding programs, and refinement of silvicultural prescriptions calls for a multi-disciplinary, state-of-the-art, collaborative approach to improve and sustain chestnut resources while being mindful of cultural and economic ramifications. We consider IUFRO an optimal platform for these activities and, vice versa, chestnut represents a timely expansion of IUFRO’s activities. Developments in virtual platforms will provide opportunities to share knowledge and collaborate in non-traditional ways.