Climate change is confronting forestry with new challenges as tree species with the ability to acclimate to exacerbated climate conditions have to be identified. The ideal future forest would consist of species coping well with increasing drought and concurrently provide timber of high economic value.
Economically valuable species are for instance European beech (Fagus sylvatica L.) or Douglas fir (Pseudotsuga menziesii (Mirb.) Franco). Beech is highly valued for its favourable wood-technological properties and its good processability and thus is one of the prime European timber species. Douglas fir is not native in Europe but was introduced from the Western United States in the 19th century. It is highly appreciated due to its high productivity and its undemanding nature and is the most important timer species worldwide and the main non-native timber species in Western and Central Europe. However, it remains unclear whether both species are able to cope with increasing water shortage and if they can maintain high productivity and wood quality remains unclear.
Planting adapted provenances can largely improve the performance of beech and Douglas fir and hence play a role in the future tree species portfolio in Central Europe. By choosing the optimal provenance, species range could be enlarged or species yield could be maximised under various site conditions. The establishment of large provenance trials with beech and Douglas fir in the context of the Cost Action E52 and IUFRO programs offers an unique opportunity to study provenance performance under various climate and site conditions throughout Europe.
In this study we aim to designating provenances of beech and Douglas fir that perform well under periodically dry climate and site conditions. Radial growth dynamics including variation in wood structure are used as indicators for tree performance. Well adapted provenances are expected to show persistently high growth rates under permanent dry site conditions and elastic responses to extreme drought years, i.e. a fast recovery following a short growth depression. Provenances performance is analysed under contrasting climate at different locations in Europe. We compare provenance growth in the Netherlands characterised by maritime climate, with the trials within the framework showing the lowest water availability estimates based on a drought index.
Analysed parameters are:
- tree-ring width to determine the limiting effect of drought on long term growth performance
- variation in wood anatomical variables, to evaluate (i) the limitation of wood formation by drought and (ii) the expected consequences for the metabolism of the tree
- wood-technological properties to assess the impact of drought on wood quality
- water flow and water content by using NMR imaging to better understand the extent of water transport restraint via caviation
The combination of tree-ring analyses, wood anatomy including wood technology and eco-physiology will help to understand past and present changes in forest ecosystems and to predict shifts as a consequence of future climate changes.
In the project we aim to answer the following research questions:
- How do provenances differ in their growth response to and the recovery after drought years?
- How do provenances differ in their physiological response to drought?
- What is the main mechanism limiting the performance of beech an Douglas fir under drought – the limitation of carbon availability (and therefore the limitation of growth) or extensive cavitation?
- Do some provenances of beech and Douglas fir have the capability to perform well in a drier future climate?
- Eilmann, B.; Rigling, A. (2012) Tree-growth analyses to estimate tree species’ drought tolerance. Tree Physiology 32(2): 178–187. doi:10.1093/treephys/tps004
- Reijerse, R. (2012). Can we increase the potential of beech to cope with drier future climate in Central Europe?
- Sauren, P. (2012). Does origin matter? Chances to mitigate drought stress on coastal Douglas-fir in Europe.