Abstract
Climate change challenges the local adaptation of tree populations. Here we combine tree ring analysis with analysis of variation in bud burst and autumn senescence to study levels of genetic differentiation in growth and phenology within and between populations of Pedunculate oak ( Quercus robur L.) from the northern part of the specie’s natural distribution area. We find moderate to high levels of additive genetic variation and heritability in phenology ( h 2 = 0.4–0.7) with late senescence score correlated with increased growth in years with warm autumns. We also find presence of genetic variation in how tree growth is influenced by water availability in the previous year. The study underscores a correlation between autumn phenology and growth in pedunculate oak populations, particularly in northern regions. Based on the findings, we discuss the importance of preserving standing genetic diversity to facilitate continued adaptation to changes in growing season lengths in the future.