Assisted natural regeneration in Brazil: a synthesis of the available evidence

Assisted natural regeneration (ANR) has emerged as a promising approach for scaling up ecological restoration, particularly in tropical countries such as Brazil, where large areas present high natural regeneration (NR) potential. However, the state of ANR research and its effectiveness relative to other restoration approaches remain poorly understood. We conducted a systematic review and meta-analysis to synthesize evidence on ANR in Brazil and compare its ecological outcomes with those of full-area planting (FP), NR, and reference forests. A total of 24 studies met the criteria for quantitative synthesis. Ecological responses were compared using the natural logarithm of the response ratio (lnRR) and analyzed with multilevel mixed-effects models. Our review showed that ANR research in Brazil is concentrated in the Atlantic Forest and Amazon biomes, primarily addresses early restoration stages, and rarely incorporates fauna-related indicators. Ecological outcomes under ANR showed high variability and overlapped with those observed under FP and NR. While no significant differences were detected among restoration strategies, ANR with enrichment exhibited ecological performance comparable to FP, whereas planting tended to outperform ANR without enrichment. Reference forests consistently exhibited higher ecological values than ANR areas. These findings indicate that ANR may provide ecological outcomes comparable to intensive restoration approaches under suitable conditions, particularly when combined with enrichment interventions. However, restoration outcomes are strongly context-dependent, and important knowledge gaps remain, including limited long-term evidence, restricted biome coverage, and lack of standardized monitoring approaches. Addressing these limitations will be essential to strengthen the evidence base and support ANR implementation in Brazil.