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Resilience of sessile oak to climatic variations in Europe
INRA researchers working with the France’s national forestry bureau, or ONF, and European partners have shown that sessile oak (Quercus petraea) is very resistant to climatic variations (temperatures and precipitation). This overall resilience nevertheless belies differential responses between populations according to their origin. In response to future climate change, the survival and growth of southern populations will be significantly more affected than those native to northern Europe. The findings have recently been published in the journal Global Change Biology.
In order to study the responses of sessile oak to climatic variations, researchers at INRA, working in tandem with the ONF and European partners, analysed data pertaining to tree growth and survival in a network of experimental plantations created 30 years ago in several European countries, from England and Scandinavia to Turkey. Two- or three-year-old seedlings taken from 116 different geographical areas across Europe were transplanted into 23 field test sites. Among these population transfers, some reproduce spatially climatic variations analogous to those predicted by IPCC1. These plantations therefore provide important information about how sessile oak will respond to climate change in going forward.
Overall, the results show that the species is not very sensitive to variations in climate. The factor that had the greatest impact was lack of water. However, responses varied depending on geographical origins: populations from warmer climates showed slower growth than populations from colder climates, proving that the population’s climate of origin impacts its genetic make-up, now made manifest.
Oak trees in southern and eastern Europe threatened through to 2100
These phenomena would be exacerbated in the case of more severe climate change, with an average jump in temperatures of 3.7°C through to 2100.
An extraordinary experiment
The experiment is unlike any other in terms of scope and timeframe. It has allowed scientists to evaluate resistance to climate change by a forest species that is of major importance in economic, ecological and cultural terms. Sessile oak covers more than 1.5 million hectares in France.
The next step in the experiment will be to study other biological factors that come into play in the adaptation of species: the capacity to reproduce and the adjustment of growth cycles during vegetation seasons (phenology). This research is shedding new light on the issue of the possible assisted migration2 of oak trees, which has yet to be modelled in greater detail.
These studies were co-financed by three European research projects on the adaptation of forests to climate change: FORGER (www.fp7-forger.eu), TREEPEACE (www.treepeace.fr) and MOTIVE (motive-project.net).
Partnering with the ONF: betting on the sustainability of forest experiment sites
These findings, the result of the expert handling of an ambitiously wide-scale experiment, were made possible by the collaboration of European partners - through the financial support of the European Union - and cooperation of France’s national forestry bureau (ONF), who agreed to the installation of 4 comparative Sessile oak plantations in four State forests, ranging in size from 19 to 40 ha each: La Petite Charnie (Sarthe), Vierzon (Cher), Sillégny (Moselle) and Vincence (Nièvre). The experiments carried out in these national forests are a guarantee of sustainability for this type of study in the long term.
1The Intergovernmental Panel on Climate Change had defined four scenarios for the evolution of greenhouse gas concentrations in the atmosphere for the 21st century and beyond. For each scenario, climate experts deduce climate conditions and the associated impacts of climate change over time.
2Assisted migration entails transferring populations by plantation and managing them based on forecasts in climatic variations for the century to come.
Sáenz-Romero, C., Lamy, J.-B., Ducousso, A., Musch, B., Ehrenmann, F., Delzon, S., Cavers, S., Chałupka, W., Dağdaş, S., Hansen, J. K., Lee, S. J., Liesebach, M., Rau, H.-M., Psomas, A., Schneck, V., Steiner, W., Zimmermann, N. E. and Kremer, A. (2016), Adaptive and plastic responses of Quercus petraea populations to climate across Europe. Global Change Biology. doi:10.1111/gcb.13576