The rapid change in the Earth’s climate is predicted to disrupt the conditions which determine the distribution of tree species, with the most dramatic impacts at species range edges. At the trailing-range edge, empirical knowledge of the structure and performance of populations is very limited despite its essential importance for accurate prediction of species distribution and conservation of species diversity. Here, I hypothesize that the trailing-range edge is partly comprised of a relict structure of populations that can stabilize the range-edge of tree species. Through trait-based ecology and combining field, experimental and molecular approaches I aim to disentangle (1) the habitat, functional, genetic and demographic structure of trailing-range edge populations; (2) the mechanisms of local adaptation in early life stages; and (3) the associations between functional traits, demographic performance, habitat conditions and the relict status of populations. PERS-RELICT-CLIM is the first project designed to gain a complete understanding of trailing-range edge structure and functioning and potential of populations for persistence under global climate change.