A dark side of conservation biology: Protected areas fail in representing subterranean biodiversity

Biodiversity conservation is a central imperative of the 21st century. Subterranean ecosystems deliver critical nature's contributions to people and harbour a broad diversity of poorly understood specialised organisms. However, the subterranean biome is still largely overlooked in global biodiversity targets. We assessed how well subterranean biodiversity is represented in protected areas (Natura 2000 and Emerald networks) in two global hotspots of subterranean biodiversity (the Pyrenees and the Alps). For this, we used two comprehensive databases of terrestrial subterranean taxa, that is, leiodids (beetles) from the Pyrenees and spiders from the Alps, and identified priority areas in each region using both species richness and geographic rarity patterns. Our results show the incapacity of surface-protected area networks to represent subterranean biodiversity, as more than 70% and 90% of the identified priority areas (and 40% and 22% of the species) are not effectively covered by protected areas in the Pyrenees and the Alps, respectively. These findings call for developing an urgent plan for subterranean biodiversity conservation within the European Biodiversity Strategy for 2030.