Variation of candidate genes related to climate change in European beech (Fagus sylvatica L.) European beech (Fagus sylvatica) is an ecologically and economically important tree species in Central Europe. Although beech is a highly competitive species it does not colonize all habitats in its area of distribution e.g. very dry habitats. Climate change scenarios predict higher annual mean temperatures and a decrease of precipitation in the summer months. This may increase the drought stress risk in summer and the late frost risk in spring. A candidate gene approach and the analysis of variation within these candidate genes were used in this study to investigate the genetic background of drought stress and bud phenology. Populations along a precipitation gradient in Northern Germany were studied. Additionally a controlled drought stress experiment was conducted. The neutral genetic diversity analysed with nine microsatellite markers was found to be high for all locations and is comparable to other beech populations. Partial sequences of ten candidate genes were identified at the genomic level and SNPs (Single Nucleotide Polymorphisms) were analysed. The nucleotide diversity range is comparable to other tree species whereas the mean nucleotide diversity is comparatively low. All populations were found to be significantly different with respect to genetic differentiation ...