The current biodiversity crisis underscores the need to understand how biodiversity loss affects ecosystem function in real-world ecosystems. At any one place and time, a few highly abundant species often provide the majority of function, suggesting that function could be maintained with relatively little biodiversity. However, biodiversity may be critical to ecosystem function at longer timescales if different species are needed to provide function at different times. Here we show that the number of wild bee species needed to maintain a threshold level of crop pollination increased steeply with the timescale examined: two to three times as many bee species were needed over a growing season compared to on a single day and twice as many species were needed over six years compared to during a single year. Our results demonstrate the importance of pollinator biodiversity to maintaining pollination services across time and thus to stable agricultural output.

当前的生物多样性危机强调需要了解生物多样性丧失如何影响现实世界生态系统中的生态系统功能。在任何地点和时间，少数高度丰富的物种往往提供大部分功能，这表明可以通过相对较少的生物多样性来维持功能。然而，如果需要不同的物种在不同的时间提供功能，生物多样性可能对较长时间尺度的生态系统功能至关重要。在这里，我们表明，维持作物授粉阈值水平所需的野生蜂种数量随着研究时间尺度的增加而急剧增加：与单日相比，一个生长季节所需的蜂种数量是单日的两到三倍，也是两倍与一年相比，六年内需要物种。我们的结果证明了授粉媒介生物多样性对于长期维持授粉服务以及稳定农业产量的重要性。