How landscape complexity impacts the multiple ecosystem service benefits of wildflower margins

A better understanding of how the surrounding landscape affects multiple ecosystem service outcomes of conservation practices would help identify opportunities where implementation can make the greatest impact. We used ecosystem services models to characterize the effect of adding perennial wildflower strips along crop field margins, assessing the role of natural land cover and landscape complexity (landscape composition, connectivity, fragmentation, and heterogeneity) on the magnitude of ecosystem service improvements. We compared baseline ecosystem service values to a scenario adding wildflower strips along all crop field margins on pollinator abundance, groundwater recharge, sediment runoff, and nutrient runoff in 437 subwatersheds in the northeast and upper midwest US. Planting perennial strips improved all four ecosystem services, but in distinct ways. Pollinator abundance improvement peaked between 20-50% natural land cover. Nutrient runoff decreased with increasing natural land cover and edge density. Though natural land cover was important for supporting pollinator abundance and reducing nutrient runoff, this metric did not fully capture the landscape processes that drove these ecosystem services. Cohesion and edge density of annual agriculture were positively but nonlinearly associated with groundwater recharge and sediment runoff, respectively. Annual agriculture edge density was also important, highlighting the importance of creating ecotones to support not only biodiversity-based ecosystem services such as pollination, but also for its potential to reduce sediment runoff. Our approach can be extended to consider tradeoffs and tipping points in intermediate scenarios, which can inform more realistic interventions based on optimizing partial landscape conversions.