Number of BEF relationships (shown by open circles) tested for each category of ecosystem functions and each trophic level of investigated biodiversity (marked by different colours), and the proportions of positive, neutral and negative BEF relationships. Stacked bars and the numbers near each bar show the proportions and numbers of total BEF relationships investigated for each ecosystem function (right panel) and for each trophic level (upper panel). Filled circles show the number of cases where ecosystem functions and biodiversity were simultaneously investigated but no BEF tests were performed. The circle colours show the trophic level of the biodiversity investigated. For details on trophic groups, trophic levels and the categories of taxa for which biodiversity was investigated see Supplementary Table S4. For details on ecosystem functions investigated see Supplementary Table S6.