The focus of this project is to examine the drought tolerance mechanisms of Douglas-fir, Norway spruce and European beech in mixed and pure stands. Mature trees of the named species will be compared with respect to important traits that determine hydraulic architecture, water consumption, drought tolerance and the isohydric/anisohydric water status regulation. The aim is to identify changes within these traits when tree stands are enriched with another species compared to when grown in monocultures. Moreover, cores will be taken to gain information about the climate over the last approximately 20 years.