FSC forest certification effects on biodiversity: A global review and meta-analysis.

FSC is a worldwide recognized forest certification scheme, that aims to promote the environmentally responsible management and conservation of the world's forests. Despite its broad application, there is little evidence of its effect on biodiversity. To address this important knowledge gap, here we conducted a systematic review and a hierarchical meta-analysis of the effects of FSC on biodiversity worldwide. Our review yielded 57 studies spanning 2004-2022. Most studies were in the Americas and Europe (31 % and 28 %, respectively), and largely focused on vascular plants (41 %). Half (51 %) of the studies aimed to determine the effect of FSC certification on biodiversity. There were 15 studies with sufficient information for meta-analysis, resulting in 231 effect sizes for mammal, bird, and vascular plant abundance and 10 for vascular plant richness. Overall, there is a neutral effect of certification on taxa abundance, with only a positive effect on mammal assemblages. Responses varied considerably between mammals' traits. Threatened species, individuals with reduced body weight, and omnivorous species benefit from management under the FSC scheme. Vascular plant richness exhibited significantly higher values in FSC-certified areas. Moreover, the abundance of vascular plants also differs among traits, with shrubs and adult trees benefiting from FSC certification. Our systematic review and meta-analysis revealed strong variation in biodiversity responses to FSC, and major geographic and taxonomic knowledge gaps. The overall neutral effect and the divergent responses of taxa and species traits suggest that taxa/species-specific management and improvement of FSC criteria are required.