Key questions for understanding drivers of biodiversity-ecosystem service relationships across spatial scales

Context: Biodiversity loss is predicted to have significant impacts on ecosystem services based on previous ecological work at small spatial and temporal scales. However, scaling up understanding of biodiversity-ecosystem service (BES) relationships to broader scales is difficult since ecosystem services emerge from complex interactions between ecosystems, people, and technology. Objectives: In order to inform and direct future BES research, identify and categorise the ecological and social-ecological drivers operating at different spatial scales that could strengthen or weaken BES relationships. Methods: We developed a conceptual framework to understand the potential drivers across spatial scales that could affect BES relationships and then categorized these drivers to synthesize the current state of knowledge. Results: Our conceptual framework identifies ecological/supply-side and social-ecological/demand-side drivers, and cross-scale interactions that influence BES relationships at different scales. Different combinations of these drivers in different contexts will lead to a variety of strengths, shape, and directionality in BES relationships across spatial scales. Conclusions: We put forward four predictions about the spatial scales that the effects of biodiversity, ecosystem service management, ecosystem co-production, and abiotic linkages or effects will be most evident on BES relationships and use these to propose future directions to best advance BES research across scales.