Progress developing the concept of other effective area-based conservation measures

In 2010, the introduction of other effective area-based conservation measures (OECMs) into international policy caused a paradigm shift in area-based conservation, which included consideration of areas outside formal protected areas and places where biodiversity conservation may not be a management objective for the site. Despite the importance of this shift for global conservation, conservation science and policy have been slow to engage with the concept of OECMs. As the world moves toward protecting 30% of the Earth by 2030, it is imperative to develop evidence-based guidance for how to identify effective conservation measures, especially tools to help evaluate and monitor the biodiversity outcomes associated with potential OECMs. To understand the current progress in developing the concept of OECMs, I evaluated the peer-reviewed literature to consolidate and synthesize current knowledge. I conducted a thematic analysis of papers to identify the types of challenges and opportunities being discussed and lessons from studies evaluating the effectiveness of OECMs. Only 105 studies mentioned OECMs, and those that did rarely move beyond superficial mention of OECMs as part of area-based conservation. Around one-half of studies listed potential risks or benefits of OECMs but none provided evidence these issues have materialized. Twenty-three studies attempted to identify potential OECMs, although specific case studies were rare. The 7 studies that evaluated existing OECMs were highly critical of how they had been implemented to date. Studies that evaluated conservation outcomes were extremely rare, and suggested effectiveness must be judged on a case-by-case basis. The current literature not only leaves many gaps in the science required to operationalize the concept of OECMs, but also often raises additional questions that need to be addressed. If these gaps are not filled by robust science, the promised benefits for biodiversity from OECMs may never be realized.