Plant–pollinator networks in semi-natural grasslands are resistant to the loss of pollinators during blooming of mass-flowering crops

Mass-flowering crops lead to spatial redistributions of pollinators and to transient shortages within nearby semi-natural grasslands, but the impacts on plant–pollinator interactions remain largely unexplored. Here, we characterised which pollinator species are attracted by oilseed rape and how this affected the structure of plant–pollinator networks in nearby grasslands. We surveyed 177 networks from three countries (Germany, Sweden and United Kingdom) in 24 landscapes with high crop cover, and compared them to 24 landscapes with low or no oilseed rape during and after crop blooming. On average 55% of grassland pollinator species were found on the crop, which attracted 8–35% of individuals away from grasslands. However, networks in the grasslands were resistant to these reductions, since mainly abundant and highly mobile species were attracted. Nonetheless, simulations indicated that network structural changes could be triggered if > 50% of individuals were attracted to the crop (a value well-above that found in our study system), which could affect community stability and resilience to further disturbance.

This project was funded by the EU FP7 STEP project ‘Status and Trends of European Pollinators’ (244 090, < www.STEP‐project.net>) and Biodiversa‐FACCE project ‘Enhancing biodiversity‐based ecosystem services to crops through optimized densities of green infrastructure in agricultural landscapes’ (PCIN‐2014‐048, < www.cec.lu.se/research/ecodeal >). AM, MV, JG‐V and IB acknowledge funding from the Spanish Severo Ochoa Program (SEV‐2012‐0262). AM acknowledges funding from the Juan de la Cierva program. JBW, VJW and SGP acknowledge the support of Insect Pollinators Initiative research funded jointly by a grant from BBSRC, Defra, NERC, the Scottish Government and the Wellcome Trust, under the Living with Environmental Change Partnership. HGS acknowledges the support of the Formas project SAPES for landscape analyses. AH received funding from DFG‐Collaborative Research Center 1047, Insect Timing.