Climate change drives hydrological decoupling of a central European beech forest

Climate change models suggest increasing rain variability for Europe in the next decades, with hypothesised cascading effects on ecosystems. We evaluate decadal-scale data of a measuring plot in a beech forest in central Germany to test these model-based suggestions and potential implications by empirical evidence. Based on 15 min resolution metrics of precipitation and subsequent water pathways towards and within the soil, we show medium-term trends in rainfall characteristics and their modulation by biota. Rain event durations and rain amounts per event tended to decrease over the observation period, while rain intensity increased, accommodating the effect of the two former parameters on annual precipitation. This change in precipitation patterns, together with canopy structure caused a systematic decrease in throughfall ratios and an exponentially enhanced throughfall variability. Our results suggest that changing rainfall and throughfall patterns will progressively decouple hydrological links in one of Europes most extensive ecosystem types. Based on the observed trends, we discuss effects of changing vegetation-modulated rain-input on ecosystem functioning and soil-hydrological trajectories to be anticipated in the near to mid-term future.