The data contains aboveground dry matter yields from grassland field experiments conducted at two Swiss sites (Zürich and Tänikon). The experiments investigated drought impacts on monocultures and mixtures of two and four key forage species that differed in their functional traits. The species were Lolium perenne L., a shallow-rooted grass; Cichorium intybus L., a deep-rooted herb; Trifolium repens L., a shallow-rooted legume; and Trifolium pratense L., a deep-rooted legume. A nine-week summer drought was experimentally imposed with rainout shelters, and aboveground biomass yields were measured under drought conditions and rainfed controls over several harvests. The dataset includes harvest-level and plant species-level data collected annually.
