Carbon finance initiatives can provide biodiversity benefits

Carbon finance initiatives such as Reducing Deforestation and Forest Degradation (REDD+), designed to mitigate climate change, offer an opportunity to also protect biodiversity. However, managing forests to store and sequester carbon does not necessarily conserve biodiversity. We evaluated the biodiversity co‐benefits of the Gola‐REDD+ initiative in the tropical forests of Sierra Leone, using bioacoustics and DNA metabarcoding under a quasi‐experimental study design. We used soundscape saturation (SS) as a measure of vocalizing diversity, and e‐DNA arthropod community as a complementary measure of biodiversity to examine whether a Gola‐REDD+ financed protected area (Treatment‐PA) conserved biodiversity more than (1) a multiuse community land (Control‐CL) and (2) a PA without REDD+ finance (Control‐PA). We found that REDD+ financing is associated with additional biodiversity co‐benefits in the Treatment‐PA compared to both control areas. Our study makes three key contributions. First, we provide concrete evidence on a carbon finance (REDD+) project's effectiveness in conserving faunal diversity while sequestering carbon. Second, we present a gold‐standard causal inference study design for evaluating biodiversity co‐benefits of conservation strategies. Third, we highlight the role of conservation technologies like bioacoustics and DNA metabarcoding in informing conservation policy.