Evaluating protected areas' coverage of threats to terrestrial biodiversity

Protected areas (PAs) are vital for biodiversity conservation and have expanded globally. However, increasing pressures on biodiversity make it difficult to achieve conservation goals. Using threat probability maps based on the International Union for Conservation of Nature Red List and the World Database of Protected Areas, we analyzed the relationship between PA coverage and the major threats to amphibians, birds, mammals, and reptiles-agriculture, hunting, logging, pollution, invasive species, and urbanization. We included data on 33,379 species and 255,848 protected sites. We analyzed the relationship between threat probabilities and PA coverage with generalized additive models. Then, we grouped grid cells into discrete threat-protection categories and examined global spatial patterns. We focused three types of areas: areas with a high probability of threat that coincided with inadequate PA coverage; areas that had simultaneous threats; and areas with a high concentration of threatened species. We found a potential disconnect between global PAs and threat coverage. Twenty-one percent of areas had a high probability of threat, of which 76% were insufficiently protected. Over half of amphibian and mammal habitat was highly threatened and was insufficiently covered by PAs. Amphibians were subject to the highest proportion of simultaneous threats. Underprotected areas harbored the largest proportion of threatened species across all taxonomic groups. Our results provide crucial insights into the spatial relationship between threats and PA coverage and can be used to inform conservation planning at large scales.