BeechDrought

Oriental beech for assisted migration? Assessing its drought tolerance in old plantations of France, Germany and Switzerland

In collaboration with:

• Dr Christoph Sperisen, Dr Peter Brang (WSL)

• Oliver Brendel and Didier Le-Thiec (INRAE Nancy)

• Prof Jürgen Bauhus, Dr Martin Kohler (University of Freiburg)

• Dr Fabio Rezzonico and Dr Theo Smits (ZHAW Zurich University of Applied Sciences)

• Dr Peter Zhelev (University of Forestry, Sofia)

Students involved:

• Mirjam Kurz (ZHAW & WSL)

• Bea Pablo Carmona (WSL)

• Adrian Kölz (University of Freiburg)

Summary:

The capacity of forest tree populations to respond to climate change will directly affect the persistence, biodiversity, and ecosystem services of many forests. Assisted migration (AM) has been suggested as an adaptive forest management tool to reduce some of the negative ecological consequences of the rapidly changing climate1. AM involves potential benefits and risks, opens ethical questions, and opposes to a traditional status quo conservation strategy. Currently, there is a burning need for comprehensive risk assessment of AM in European forests. Oriental beech (Fagus orientalis) is one of the key species proposed for AM in Europe, because it is likely more drought tolerant than European beech (Fagus sylvatica). The two species are closely related ‒ some authors treat them as two subspecies ‒ and hybridize in their zone of contact in the southern Balkans. Thus, they may also hybridize upon introduction of Oriental beech by AM, potentially leading to genetic swamping of local European beech. In a BAFU funded project, we have genotyped several hundreds of seedlings to establish their species identity and hybrid status. This data set will be used to evaluate the rate of hybridization between the two species. Currently we are extending the project with international partner. In particular, we plan to take advantage of existing old Oriental beech plantations in France, Germany and Switzerland to compare the drought response of the two species in seedlings using a common garden rain exclusion experiment, and in adults, using tree rings and wood density profiles.