Temporal and spatial heterogeneity of semi-natural habitat, but not crop diversity, is correlated with landscape pollinator richness.
Enhancing the diversity of mass-flowering crops (i.e. crop diversity) in agricultural landscapes is often proposed as a measure to favour pollinators and pollination, but it is uncertain whether crop diversity enhances pollinator richness on the wide landscape level. Here, we surveyed pollinator communities in semi-natural habitats and mass-flowering crops throughout the whole growing season in 26 agricultural landscapes to examine how the temporal and spatial heterogeneity in semi-natural habitats and crop diversity support pollinator species richness. Crop diversity was unrelated to pollinator richness in the wider landscape, and temporal and spatial heterogeneity in semi-natural habitats were equally important in determining pollinator richness. Surprisingly, the crop pollinator species pool size was a fixed proportion of the landscape pollinator species pool along a 0%-72% semi-natural habitat cover gradient. Synthesis and applications. Our results suggest that increasing crop diversity alone does not contribute to maintaining diverse wild pollinator communities in agricultural landscapes and emphasize the key role of temporally stable habitats such as semi-natural habitats to maintain rich pollinator communities.