Scaling Species Risk Assessment to Network-Level Structural Fragility: A Continental Analysis of European Food Webs

Biodiversity extinction-risk assessments have traditionally focused on the species level, using standardized criteria to evaluate their conservation status. These assessments provide essential information for conservation policy and legislation, for example by helping to identify priority areas for expanding protected area networks, in an effort to halt biodiversity loss across taxa, spatial scales, and political borders. However, scaling species-level extinction risk to the network level is a critical step toward a more comprehensive assessment of biodiversity loss, accounting for ecological interdependencies and the structural integrity of communities and ecosystems. Here, we provide a novel framework for estimating the fragility of ecological networks, based on species structural importance within the network and their sensitivity to different anthropogenic threats. We apply the framework into local food webs across Europe, and show that both direct exploitation of biological organisms (e.g., harvesting), and degradation of natural environments are associated with higher food web fragility across the continent. Our results suggest that the vulnerability of food webs is highly spatially heterogeneous, with hotspots of fragility in the Iberian Peninsula, and in Western- and Central-Europe regions.