Birkenbach Markus, Straub Florian, Kiesel Anna, Ayasse Manfred, Wilfert Lena, Kuppler Jonas
Institute of Evolutionary Ecology and Conservation Genomics Ulm University Ulm Germany.
Ecol Evol. 2024 Mar 7;14(3):e11061. doi: 10.1002/ece3.11061. eCollection 2024 Mar.
Land-use management is a key factor causing pollinator declines in agricultural grasslands. This decline can not only be directly driven by land-use (e.g., habitat loss) but also be indirectly mediated through a reduction in floral resource abundance and diversity, which might in turn affect pollinator health and foraging. We conducted surveys of the abundance of flowering plant species and behavioural observations of two common generalist pollinator species, namely the bumblebee and the syrphid fly , in managed grasslands of variable land-use intensity (LUI) to investigate whether land-use affects (1) resource availability of the pollinators, (2) their host plant selection and (3) pollinator foraging behaviour. We have found that the floral composition of plant species that were used as resource by the investigated pollinator species depends on land-use intensity and practices such as mowing or grazing. We have also found that bumblebees, but not syrphid flies, visit different plants depending on LUI or management type. Furthermore, LUI indirectly changed pollinator behaviour via a reduction in plot-level flower diversity and abundance. For example, bumblebees show longer flight durations with decreasing flower cover indicating higher energy expenditure when foraging on land-use intensive plots. Syrphid flies were generally less affected by local land use, showing how different pollinator groups can differently react to land-use change. Overall, we show that land-use can change resource composition, abundance and diversity for pollinators, which can in turn affect pollinator foraging behaviour and potentially contribute to pollinator decline in agricultural grasslands.
土地利用管理是导致农业草原传粉者数量下降的关键因素。这种下降不仅可能由土地利用直接驱动（例如栖息地丧失），还可能通过花卉资源丰富度和多样性的减少间接介导，而这反过来可能会影响传粉者的健康和觅食。我们对不同土地利用强度（LUI）的人工管理草原上开花植物物种的丰富度进行了调查，并对两种常见的泛化传粉者物种，即大黄蜂和食蚜蝇，进行了行为观察，以研究土地利用是否会影响：（1）传粉者的资源可用性；（2）它们对寄主植物的选择；（3）传粉者的觅食行为。我们发现，被调查传粉者物种用作资源的植物物种的花卉组成取决于土地利用强度以及割草或放牧等管理方式。我们还发现，大黄蜂会根据土地利用强度或管理类型访问不同的植物，但食蚜蝇不会。此外，土地利用强度通过降低样地水平的花卉多样性和丰富度间接改变了传粉者的行为。例如，随着花卉覆盖率的降低，大黄蜂的飞行持续时间会变长，这表明在土地利用强度高的样地觅食时能量消耗更高。食蚜蝇通常受当地土地利用的影响较小，这表明不同的传粉者群体对土地利用变化的反应可能不同。总体而言，我们表明土地利用可以改变传粉者的资源组成、丰富度和多样性，进而影响传粉者的觅食行为，并可能导致农业草原上传粉者数量的下降。
