The first Annual Impact Report set out to test how biodiversity results could be measured and sustained over time.

The report reviewed long-term effects of biodiversity projects using two complementary methods: case studies of protected areas in East Africa and statistical analysis of deforestation trends in Costa Rica.

The evaluation applied a theory-based approach to three projects in Uganda, Kenya, and Tanzania, alongside time-series comparisons of deforestation in protected and unprotected areas in Costa Rica.

Findings show that two of the East African projects achieved measurable conservation impacts, including stable or growing populations of mountain gorillas and black rhinos, and sustained reductions in threats to habitats where institutional continuity was planned from the outset.

In contrast, the cross-border forest project lacked a strategy for sustainability, and benefits declined after project closure, while unresolved livelihood issues among the Batwa highlighted the need for stronger social safeguards. In Costa Rica, GEF-supported protected areas reduced deforestation more effectively than comparable sites supported by other actors, demonstrating the value of quasi-experimental analysis.

The report concludes that combining targeted case studies with opportunistic statistical methods provides the most cost-effective and realistic approach to impact evaluation, and recommends integrating institutional continuity requirements into GEF biodiversity tracking tools and future project design.