Climate change is expected to have serious effects on forest ecosystems. Our ability to predict the impact of climate change (CC) on forest ecosystems remain however limited. This is because of an incomplete understanding of the processes through which CC will impact forests composition, structure and dynamics. A key limitation is that we are so far not able to link (i) the ecophysiological impacts of climate change, (ii) tree demography and (iii) tree competition within the community. These three themes however need to be connected to predict the CC impact at the community level. In this project we propose that plant functional traits can be pivotal to connect these themes.The fellow recently developed modern statistical methods to estimate how tree demography is affected by climatic variables and competition using the French National Forest Inventory data. The key advance proposed in this project is to link these methods with tree functional traits (FT). The fellow will spend two years in the world-leading group in FT of Prof. Westoby (Macquarie University, Sydney), to learn new skill in tree functional traits. He will first work in collaboration Westoby’s group to identify a list of key FT linked to drought, temperature and competitive interaction and develop a data base for European mountain tree species. Then the goals of this project are: (i) improve our understanding of the link between functional traits and response of demographic rates to climatic constraints, (ii) improve our understanding of the link between functional traits and response of demographic rates to competition, (iii) dissecting multiple trade-offs in the demographic space and analyse their relations with a nexus of interrelated functional traits and (iii) use these results to develop a new forest dynamics models for mountain forests based on tree functional traits (and not the species level) to forecast the effect climate change.