Annual yields of multispecies grassland mesocosms outperformed monocultures across a drought gradient due to complementarity effects and rapid recovery

Abstract

More frequent and severe drought events due to climate change pose a major challenge for sustainable forage production in managed grasslands. This study investigated whether multispecies grassland communities can provide greater resistance to and/or recovery from drought compared to monoculture communities.Mesocosms of Lolium perenne L., Cichorium intybus L., Trifolium repens L. and Trifolium pratense L. were established as monocultures, and a four‐species mixture. A drought gradient with five levels of water supply ranging from a mild to a severe treatment was applied for 10 weeks, in each of 2 years. Shoot biomass was harvested to assess drought resistance, drought recovery and annual yields. Root mass density and specific root length were measured in Year 2.Across the drought gradient, four‐species communities had significantly larger annual yields than each of the four monocultures, indicating transgressive overyielding. This was despite relatively low drought resistance for four‐species communities compared with L. perenne and C. intybus monocultures. Recovery of yields following drought was high for all communities.Multispecies swards with complementary traits can provide a viable adaptation option across a wide range of drought severities. Application of a stress gradient methodology allowed a more detailed understanding of stress responses.