Authors: Boetzl, Fabian; Douhan Sundahl, Anna;Friberg, Hanna;Viketoft, Maria;Bergkvist, Göran;Lundin, Ola;

Conserving biodiversity and biodiversity mediated ecosystem services commonly clashes with maintaining productivity levels in agriculture. Increasing within field vegetation diversity by intercropping with legumes seems promising but the effects on biodiversity and ecosystem services are so far not sufficiently understood. Using 26 semi-field plots in a paired design, we studied the effects of intercropping oats with a mixture of three annual undersown clovers on pollinators, arable weed control and natural pest control. We found beneficial effects on pollinators and arable weed suppression but no effects on most natural enemies and a slightly negative effect on spiders. Neither pest damages nor natural pest control or crop yields were affected by intercropping. The biomass of undersown clovers was positively correlated with flower cover, pollinator densities and arable weed suppression. We demonstrate that undersowing annual clovers is a simple and comparably cheap method to suppress arable weeds (and thereby reduce herbicide inputs) and support pollinators without sacrificing cereal crop yields or taking land out of arable production. Intercropped plant mixtures should, however, be optimised to support a wider spectrum of pollinators and benefit natural enemies and natural pest control in order to support a higher level of overall cropping system biodiversity and multi-functionality.