Abstract Agricultural intensification has led to the conversion of natural habitats into agricultural fields, increased field sizes and simplified crop rotations. The resulting homogenisation of the landscape has led to a decline in bees, which provide an essential ecosystem service to agriculture. It has been suggested that an increase in landscape crop diversity supports higher biodiversity by providing more diverse and continuous resources without taking land out of agricultural production. We selected 14 faba bean (Vicia faba minor L.) fields in southern Sweden along uncorrelated gradients of landscape crop diversity and proportion of semi-natural habitat within 1.5 km radii surrounding focal fields. Pollinator surveys and pollinator exclusion experiments were conducted to assess whether landscape crop diversity affected pollinator densities, pollinator foraging behaviour (i.e. legitimate flower visitation, nectar robbing or extra-floral nectary visitation), pollination and yield formation. Landscape crop diversity enhanced bumble bee densities. Insect-pollinated faba bean plants produced, on average, 27 % higher bean weight per plant than bagged plants and the insect pollination benefit decreased with increasing semi-natural habitat cover. Bumble bee and honey bee densities, the proportion of nectar robbing bees as well as faba bean yield increased with increasing proportion of semi-natural habitat. Pollinator densities were not the driver of high yields associated with higher proportions of semi-natural habitat because the observed yield increase was unrelated to pollinator densities and driven by bagged plants that were excluded from pollinator visits. Insect pollination, however, clearly decreased the yield gap associated with low proportions of semi-natural habitat in the landscape. Our results highlight that agri-environmental policies should promote the retention of existing semi-natural habitats and encourage landscape crop diversity to provide pollinators with sufficient food and nesting resources.

中文翻译：

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景观作物多样性和半自然栖息地影响作物授粉媒介、授粉效益和产量

摘要 农业集约化导致自然栖息地转变为农田，增加了田地面积并简化了轮作。由此产生的景观同质化导致蜜蜂数量减少，蜜蜂为农业提供必不可少的生态系统服务。有人提出，景观作物多样性的增加通过提供更多样化和连续的资源而不占用农业生产的土地来支持更高的生物多样性。我们选择了瑞典南部的 14 个蚕豆（Vicia faba minor L.）田地，沿着焦点田周围 1.5 公里半径内景观作物多样性和半自然栖息地比例的不相关梯度。进行传粉媒介调查和传粉媒介排除实验以评估景观作物多样性是否影响传粉媒介密度，传粉者觅食行为（即合法的花访问、花蜜抢夺或花外蜜腺访问）、授粉和产量形成。景观作物多样性提高了熊蜂的密度。与袋装植物相比，昆虫授粉的蚕豆植物平均每株植物产生的豆重高 27%，并且昆虫授粉效益随着半自然栖息地覆盖率的增加而降低。随着半自然栖息地比例的增加，大黄蜂和蜜蜂的密度、采蜜蜂的比例以及蚕豆的产量都在增加。传粉媒介密度不是与较高比例的半自然栖息地相关的高产量的驱动因素，因为观察到的产量增加与传粉媒介密度无关，并且由被排除在传粉媒介访问之外的袋装植物驱动。然而，昆虫授粉，明显减少了与景观中半自然栖息地比例低相关的产量差距。我们的研究结果强调，农业环境政策应促进保留现有的半自然栖息地，并鼓励景观作物多样性，为传粉者提供足够的食物和筑巢资源。