The current speed of global change forces species to adapt to an unprecedented pace or to die off from their current distribution areas. This change is particularly pressing for long-lived sessile organisms such as trees, as they cannot migrate and their long generation times make them sensitive to very quick environmental changes. One possible avenue to speed up adaptation is the modification of epigenetic marks, such as DNA methylation. Here, we explore the role of DNA methylation in local adaptation between populations of sessile oaks (Quercus petraea). It is expected that the epigenetic component of variation will have a stronger effect than the genetic component in the early stages of local adaptation. We studied methylation patterns forapproximately 200 individuals from 23 different populations grown together in a common garden experiment. This allowed us to investigate the epigenetic differences between the various populations to gain an understanding of the possible impacts of the original population environment. Preliminary results seem to indicate that some populations have distinct methylation patterns in biosynthesis process genes that might be linked to environmentalvariables like summer humidity and annual temperature. This study will enable us to compare the epigenetic and genetic components of variation through the use of SNPs in the future. Which will provide insight into the differences between epigenetic and genetic adaptation in the various populations. Understanding the ways in which trees can exploit epigenetic changes for rapid local adaptation is vital to allowing us to safeguard our precious forest resources.< Réduire