Forest ecosystems are heavily influenced by extreme events, because the natural adaptation potential of trees against such irregular disturbances is relatively small. However, increased adaptation potential of forest stands is ultimately required under the auspices of increased frequencies of extreme events in a changing climate. In particular beech forests of Central Europe have been found to respond sensitively to extreme summer droughts. In BuTaKli, an interdisciplinary team of researchers conducting biogeochemical, ecophysiological and economical research is addressing the question how admixing of fir can increase the resilience of beech stands to extreme events such as drying-rewetting cycles. Research is taking place in the Upper Rhine region, where such drying-rewetting-cycles are typical for both present and projected future climates, and at the southern distribution limit of beech/fir forest in Croatia. KIT/IMK-IFU is leading a subproject addressing the questions how drying-wetting cycles and admixture of fir are affecting microbial release, turnover and competition of/for nutrients, the soil-atmosphere-exchange of greenhouse gases (CO2, CH4, N2O), and the soil carbon and nitrogen stocks.