Landscape configurational heterogeneity by small-scale agriculture, not crop diversity, maintains pollinators and plant reproduction in western Europe

Abstract

Agricultural intensification is one of the main causes for the current biodiversity crisis. While reversing habitat loss on agricultural land is challenging, increasing the farmland configurational heterogeneity (higher field border density) and farmland compositional heterogeneity (higher crop diversity) has been proposed to counteract some habitat loss. Here, we tested whether increased farmland configurational and compositional heterogeneity promote wild pollinators and plant reproduction in 229 landscapes located in four major western European agricultural regions. High-field border density consistently increased wild bee abundance and seed set of radish (), probably through enhanced connectivity. In particular, we demonstrate the importance of crop-crop borders for pollinator movement as an additional experiment showed higher transfer of a pollen analogue along crop-crop borders than across fields or along semi-natural crop borders. By contrast, high crop diversity reduced bee abundance, probably due to an increase of crop types with particularly intensive management. This highlights the importance of crop identity when higher crop diversity is promoted. Our results show that small-scale agricultural systems can boost pollinators and plant reproduction. Agri-environmental policies should therefore aim to halt and reverse the current trend of increasing field sizes and to reduce the amount of crop types with particularly intensive management.

Does composition of tropical agricultural landscape affect parasitoid diversity and their host–parasitoid interactions?

“…single large or several small (SLOSS)] (Diamond ), there is not only the trade‐off between SLOSS of natural habitats, but also the trade‐off between SLOSS of croplands. Agricultural landscapes with several small natural habitats and several small croplands appear to be more effective with respect to preserving parasitoids, although this is not true for pollinators (Hass et al ).…”

“…Parasitoid wasps, which offer pest control services, are enhanced by landscape composition (i.e. landscapes with more extensive and diversified noncrop habitats) (Steckel et al ; Martin et al ; Balzan et al ), whereas insect pollinators, especially their movement and pollen transfer, are more affected by landscape configuration especially crop–crop borders (Hass et al ).…”

Configurational crop heterogeneity increases within‐field plant diversity

“…The few attempts to tease apart the effects of crop heterogeneity components on species diversity have found positive effects of compositional crop heterogeneity, that is, Shannon crop diversity and/or configurational crop heterogeneity, that is, edge density or mean field size, on predatory arthropods (Bertrand, Burel, & Baudry, ; Bosem Baillod, Tscharntke, Clough, & Batáry, ; Fahrig et al, ; Martin et al, ; Palmu, Ekroos, Hanson, Smith, & Hedlund, ), butterflies (Perović et al, ) and wild bees (Hass et al, ). Studies addressing this issue for the diversity of plants within agricultural fields are rarer (but see Fahrig et al, ).…”

Applying the Aboveground-Belowground Interaction Concept in Agriculture: Spatio-Temporal Scales Matter

“…For pollinators, both the composition and configuration of crop and non-crop habitats is important to maintain effective communities (Barrios et al, 2018;Hass et al, 2018). Practices that increase flower-rich habitats can enhance pollinator conservation at the farm and landscape level (Dicks et al, 2015;Holland et al, 2015;Kleijn et al, 2018b).…”