Data from: Yield of temperate forage grassland species is either largely resistant or resilient to experimental summer drought

Due to climate change, an increasing frequency and severity of drought events are expected to impair grassland productivity, particularly of intensively managed temperate grasslands.
To assess drought impacts, a common field experiment to manipulate precipitation was set up at three sites (two Swiss and one Irish) using monocultures and mixtures with two and four key forage species. Species differed in their functional traits: a shallow-rooted non-legume (Lolium perenne L.), a deep-rooted non-legume (Cichorium intybus L.), a shallow-rooted legume (Trifolium repens L.) and a deep-rooted legume (Trifolium pratense L.). A nine-week summer drought was simulated and soil water status and above-ground biomass yield were compared to a rainfed control.
Based on soil water measurements, the drought induced severe stress at both Swiss sites and extreme stress at the Irish site. Under severe drought, the legumes were more drought-resistant and showed an average change in above-ground biomass (CAB, compared to rainfed control) of only -8% and -24% (for the two Swiss sites) while the non-legumes had an average CAB of -51% and -68%. However, under extreme drought, all species were substantially impaired, with an average CAB of -85%.
During a six-week post-drought period with adequate water supply (Swiss sites), formerly drought-stressed species were highly resilient and attained (legumes) or clearly outperformed (non-legumes) the yield level of the rainfed controls. As a result, aggregated over the drought and the post-drought periods, a negative drought impact was largely absent.
Significant overyielding by multi-species mixtures was evident under rainfed control (+38% predicted CAB across all sites, P < 0.05) and persisted under severe drought conditions (+50%, P < 0.05). This overyielding was so large that drought-stressed mixtures at least attained the same yield as the average of the rainfed monocultures.
Yields of selected species of intensively managed temperate grasslands are either resistant to a single severe drought or are highly resilient as soon as soil moisture levels recover after the drought event. Combining species in mixtures can compensate for yield reductions caused by severe drought and it offers a practical management tool to adapt forage production to climate change.

受气候变化影响，干旱事件的发生频率与严重程度持续攀升，将对草地生产力造成损害，其中集约化管理的温带草原受影响尤为显著。
为评估干旱的影响，研究人员在3个试验站点（2个位于瑞士，1个位于爱尔兰）搭建了常见的降水调控田间试验，设置了单播种植以及包含2种、4种关键饲用物种的混播种植处理。供试物种的功能性状存在显著差异：浅根非豆科植物（多年生黑麦草Lolium perenne L.）、深根非豆科植物（菊苣Cichorium intybus L.）、浅根豆科植物（白三叶Trifolium repens L.）以及深根豆科植物（红三叶Trifolium pratense L.）。试验模拟了为期9周的夏季干旱，并将土壤水分状况与地上生物量产量与雨养对照组进行对比。
基于土壤水分监测数据，干旱胁迫在瑞士的2个站点达到重度胁迫水平，在爱尔兰站点则达到极端胁迫水平。在重度干旱条件下，豆科植物的耐旱性更强，瑞士两个站点的地上生物量变化量（CAB，以雨养对照组为参照）平均仅为-8%与-24%；而非豆科植物的平均CAB则分别为-51%与-68%。但在极端干旱条件下，所有物种均受到显著损害，平均CAB降至-85%。
在瑞士站点开展的为期6周的旱后供水充足恢复期内，先前遭受干旱胁迫的物种展现出极强的恢复力：豆科植物的产量恢复至与雨养对照组持平的水平，非豆科植物的产量甚至显著超过对照组。综合干旱期与恢复期来看，干旱的负面影响基本消失。
在雨养对照组中，多物种混播的显著超产效应清晰可见（所有站点的平均地上生物量变化量提升38%，P < 0.05），该效应在重度干旱条件下依然存在（平均提升50%，P < 0.05）。该超产效应幅度可观，使得受干旱胁迫的混播群落产量至少达到了雨养单播群落的平均水平。
集约化管理温带草原的供试物种，要么能够抵御单次重度干旱，要么可在干旱结束后土壤水分恢复时快速恢复产量。通过物种混播组合，可以弥补重度干旱导致的产量损失，为饲草生产适应气候变化提供了切实可行的管理手段。