Decreases in the robustness of regional food webs to sequential species extinctions following habitat loss

In the face of escalating global environmental changes, understanding the robustness of ecological networks against sustained species losses is paramount to devising effective biodiversity conservation strategies. To explore the impacts of habitat-specific species losses on large-scale food web robustness, we used a trophic metaweb of 8,846 vertebrate, invertebrate and plant species and 466,255 interactions across Switzerland. We inferred twelve regional multi-habitat food webs, two for each of the six biogeographic regions, further divided into two elevation groupings. We simulated non-random species extinction scenarios on these regional food webs, focusing on broad habitat types and regional species abundances, and computed measures of network robustness. Targeted removal of species associated with specific habitat types, particularly wetlands, resulted in a higher network fragmentation and accelerated network collapse compared to random species removals. The simulations also reveal that the initial loss of common species significantly destabilised the network more than the loss of rare species across all biogeographic regions and elevation groupings. These findings underscore the critical need for integrated conservation strategies that maintain a diverse mosaic of habitat in a landscape, given the complex interdependencies within and across habitat types, to mitigate the cascading effects of species loss.