Are we zoning out? Biases in the assessment of protected area zoning and a blueprint for a way forward

Protected areas (PAs) often use zoning schemes to balance biodiversity conservation and sustainable human use, typically dividing the PA into fully protected zones and others permitting varying levels of activity, in line with UNESCO and International Union for Conservation of Nature visions. However, the effectiveness of zoning in protecting biodiversity is rarely assessed. We reviewed the scientific literature, screening 3,783 articles and identifying only 60 that specifically evaluated zoning effects on biodiversity. We observed geographic, environmental, and taxonomic biases: there are few studies in regions where zoned PAs are widely implemented (e.g., Europe); 75% focused on marine environments, none in freshwater, and most targeted vertebrates, particularly fish. Biodiversity was mainly measured through species diversity and abundance, often from a fisheries management perspective. Critically, few studies assessed biodiversity adaptability to global change—a key 2050 Global Biodiversity Framework target. This lack of comprehensive assessment hinders informed conservation decisions. We propose a blueprint for multifaceted biodiversity monitoring to support holistic evaluations of zoning effectiveness.