Figure depicting the main data sources, analyses and hypotheses of Work Package (WP) 2. A: The site at which the Main Experiment of the Jena Experiment is located. B: Photo of the DrY Experiment. Illustration of the hypotheses (C) that plant diversity effects on the magnitude and stability of soil microbial properties increase with increasing levels of stress and (D) that the stabilising effects of plant diversity increase with increasing drought intensity, until a certain threshold is reached.