SEEDFOR

What will temperate forests be like in 100 years? And beyond? Can we or do we need to manage forest to adapt to climate change? These are pressing questions given that forests represent one of the most important ecosystems on Earth, being both a biodiversity hotspot and an important carbon sink of the Earth System. In France alone, forests cover around 31% of the surface and are under management pressure to satisfy environmental quality and wood demands. This is particularly true for European lowland temperate deciduous forest characterized by species such as Fagus sylvatica, Quercus robur or Quercus petraea. These species may attain high economic value constitute around 67% of the forest surface in France. Furthermore, LTF ecological importance is highly valued, as exemplified by a recent designation of the first national park in the lowland forests in France. The future persistence of these forests is, however, not granted within the next 100 years. Climate change is expected to drastically increase temperature thus intensifying droughts, and this will affect the survival of these important tree species. Bioclimatic model forecasts predict a substitution of LTF tree species by drier adapted species such as Q. pubescens and Q. ilex. Recent microclimate modeling suggests that canopy cover may buffer the increases in free air temperature, which could enhance the recruitment of LTF species under the canopy. In addition, the stress gradient hypothesis posits that under harsher conditions we may shift from plant competition with plant facilitation. These shifts are in contrast with current management strategies to enhance forest recruitment via increasing light availability and control of competition. Surprisingly, we have a lack of knowledge of the performance and plant-plant interactions of early life stages of trees along strong climatic gradient, which precludes the assessment of future forest regeneration and the stability of LTF forests. In SEEDFOR we combine seed experiments, microclimate sensors and advanced computational techniques to understand early life stages of LTF trees under climate-change dry conditions, and project the future of lowland temperate forests in France. First, we will plant several tree seeds in different climate conditions, using seeds from different provenances. We will then understand whether there are seeds and juveniles that may be more adapted to dryer conditions than others. Second, we will use a network of intense monitoring plots to compare the climatic potential for the establishment of a young tree versus the real establishment observed in forests. We will then identify whether climate is an actual constraint for new trees to recruit, or other factors (e.g. seed predation or herbivory) are the main constraint. Finally, we will build scenarios of forest management in a forest landscape simulation model. These will provide key information on harvest potential and whether to plant climate change adapted seeds. This information will help provide answers to our main challenge: Will we be able conserve temperate forest in a warmer world?