Perspectives and pitfalls in preserving subterranean biodiversity through protected areas

Abstract

Subterranean ecosystems (comprising terrestrial, semi-aquatic, and aquatic components) are increasingly threatened by human activities; however, the current network of surface-protected areas is inadequate to safeguard subterranean biodiversity. Establishing protected areas for subterranean ecosystems is challenging. First, there are technical obstacles in mapping three-dimensional ecosystems with uncertain boundaries. Second, the rarity and endemism of subterranean organisms, combined with a scarcity of taxonomists, delays the accumulation of essential biodiversity knowledge. Third, establishing agreements to preserve subterranean ecosystems requires collaboration among multiple actors with often competing interests. This perspective addresses the challenges of preserving subterranean biodiversity through protected areas. Even in the face of uncertainties, we suggest it is both timely and critical to assess general criteria for subterranean biodiversity protection and implement them based on precautionary principles. To this end, we examine the current status of European protected areas and discuss solutions to improve their coverage of subterranean ecosystems.

Fig. 1. The breadth of subterranean habitats considered in this perspective.

The overarching classification (Subterranean [S], Subterranean–Freshwater [SF], Subterranean–Marine [SM]) is based on ref. . A Terrestrial caves in different substrates (e.g., karst, lava, ice, salt); B Artificial subterranean habitats (e.g., mines, bunkers, blockhouses, transport tunnels, tombs); C Shallow and deep fissured systems; D Aquifers and groundwaters (e.g., subterranean lakes, rivers, ponds); E, F Springs, wells, and other surface-subterranean ecotones (e.g., voids within vadose zone in karstic and fissured aquifers, interstitial habitats such as hyporheic zone); G Artificial aquatic subterranean habitats (e.g., tanks, aqueducts, water pipes); H Marine caves, hosting coastal pools and subterranean voids connected to marine waters; I, J Anchialine caves and pools contain tidally influenced water bodies where fresh, brackish, and salt waters mix through subterranean connections between the sea and the groundwater. Anchialine pools are also exposed to open air and sunlight. Photo credits: A, B, D, G–I uPIX Fotografia Ipogea; C, E, F Ilaria Vaccarelli; J David Brankovits.

Fig. 2. The extent of (indirect) subterranean ecosystems protection across the European Union.

The map shows the European Union surface covered by the Natura 2000 network of protected areas (orange) overlaid on areas that have subterranean habitats (blue). Methods and data sources to generate the map and associated analyses are available in Supplementary Text 1.