Assessing the recovery gap in forest restoration within the Brazilian Atlantic Forest

Abstract Biodiversity serves as a proxy for numerous ecosystem services that can be realized through forest restoration, benefitting both people and the environment. We investigated the magnitude of biodiversity recovery incompleteness (i.e. the recovery gap) in forest restoration within the Brazilian Atlantic Forest, hereafter referred to as the Atlantic Forest. We conducted a meta‐analysis to analyse how species richness and species abundance of soil microorganisms, invertebrates, and vascular plants, as well as the vegetation structure, recover across major gradients in environmental conditions and human‐caused disturbances. Our study shows that forest restoration in the Atlantic Forest faces a notable biodiversity gap in species richness across both passive and active restoration areas. However, the vegetation structure could potentially reach reference levels within 25–50 years. Forest type influenced the recovery of species abundance in active restoration areas, with dense forests displaying the largest gaps. Likewise, taxonomic group influenced species richness gaps in passive restoration areas, with invertebrates showing the largest gap. Reference forest age and past land use did not significantly affect biodiversity outcomes in either restoration approach. However, biodiversity levels were lower than those of the reference forest at various levels of the moderating factors analysed. Synthesis and applications : The study shows that after 25–50 years, restoration sites develop a vegetation structure similar to that of reference forests, regardless of the restoration approach. Species richness also tends to recover over time, but the rate and pattern of recovery differ between approaches. Passive restoration follows a gradual, long‐term decline in the recovery gap, while active restoration exhibits a less clear trajectory. Past land use is the strongest predictor of biodiversity recovery, particularly for vegetation structure. The restoration age, forest type, and taxonomic group play more moderate roles but explain significant variation within particular categories of each variable. These findings highlight the importance of targeted interventions to enhance restoration outcomes and the need to prioritize efforts based on specific restoration objectives. Our results emphasize the importance of setting realistic, taxon‐specific goals and provide metrics to guide resource allocation based on recovery gaps and timelines.