Spatial identification of areas suitable for other effective area-based conservation measures in the European Union.

Although significant biodiversity has been safeguarded by protected areas (PAs), biodiversity trends continue downward. Within the frameworks of the EU Biodiversity Strategy for 2030 and the new EU Restoration Regulation (2024), conserving critical biodiversity areas is essential. One promising approach is other effective area-based conservation measures (OECMs), which offer alternative pathways for in situ conservation. We identified sites across the EU that are not PAs but could contribute to conservation and be recognized as OECMs, and determined the potential contribution of these sites to biodiversity conservation. We partially applied the IUCN framework for OECM establishment across the entire EU with a focus on Greece and France. This framework is a three-step process (screening, consent, and full assessment), the full application of which requires data related to the governance and management regime of the area, long-term goals, and other site-specific information. Such data are typically available only at the site-based level. Hence, we based our analyses primarily on capturing biodiversity values within geographically defined areas based on freely available European data (e.g., landscape indices, habitats, and species statuses). We found that areas suitable for OECMs could cover up to 10% of European land and make substantial contributions to the EU's target of protecting 30% of its land by 2030. At the national level, we found that achieving biodiversity conservation outcomes with OECMs was uncertain. Accordingly, OECM confirmation must account for both the biodiversity value of proposed sites and the governance and management practices that support their effectiveness. Our approach highlights the potential of OECMs to enhance conservation efforts in support of a more resilient biodiversity landscape across Europe.