Restoration-driven positive and negative leakage in sub-Saharan Africa

Abstract Habitat restoration is a cornerstone of global climate and biodiversity policy, with over 350 million ha pledged for restoration by 2030, yet it remains unclear how restoration impacts ‘spill over’ beyond implementation areas. Restoration projects could lead to increased tree loss elsewhere (negative leakage; for example, when restoration replaces timber plantations and/or impacts landowner earnings) or reduced tree loss within project areas and surrounding landscapes (positive leakage; for example, if restoration meets timber or fuelwood resource needs or creates restoration-linked employment). Here we assembled a geospatial dataset of 129,982 restoration polygons (~6.8 million ha) across sub-Saharan Africa to evaluate changes in tree loss across space and time. Natural regeneration and active restoration reduced tree loss by up to 9.1 percentage points (pp) within restoration areas and 8.9 pp in 10 km buffers after 10 years, indicating positive leakage. By contrast, agroforestry increased tree loss by 7.9 pp within projects and 7.5 pp in surrounding landscapes. Leakage magnitude and direction varied across restoration approaches and countries (−7.8 pp to +7.1 pp), underscoring the need for context-specific strategies. Integrating leakage safeguards into restoration planning, carbon standards and incentive schemes is essential for securing landscape-scale climate and biodiversity-related benefits.