Phylogenetic diversity recovery along Atlantic Forest succession: The potential for conserving evolutionary history

Understanding the recovery of phylogenetic diversity during tropical forest succession is critical for informing ecosystem stability, conserving evolutionary history, and guiding restoration. To address these goals, we evaluated patterns of phylogenetic diversity, structure, and lineage turnover across 61 s-growth and 18 old-growth forest communities in three regions of the Brazilian Atlantic Forest. We asked whether second-growth forests recover the phylogenetic diversity found in old-growth forests over time, whether there is a consistent pattern of community assembly along succession, whether functional traits are phylogenetically conserved, and to what extent second-growth forests contribute to evolutionary history conservation at the landscape scale. Our results revealed that second-growth forests exhibit increasing species richness and phylogenetic diversity with forest age. However, standardized phylogenetic structure metrics (sesPD, sesMPD, sesMNTD) remained stable along succession and did not differ from old-growth forests, suggesting that successional time alone does not shape phylogenetic structure. Most functional traits showed low phylogenetic signal, indicating a decoupling between phylogenetic and functional recovery. Despite the absence of some rare and evolutionarily distinct lineages, particularly within Malpighiales, in second-growth forests, beta diversity analyses demonstrated that combining both forest types conserves a broader set of lineages than either type alone. This phylogenetic complementarity underscores the value of conserving both forest types as complementary components of regional biodiversity. Our findings emphasize the role of second-growth forests in preserving evolutionary history and support their inclusion in conservation and restoration strategies. By integrating broad-scale phylogenetic analyses with regional datasets, this study enhances our understanding of biodiversity recovery in one of the world's most threatened tropical biomes. • Second-growth forests recover phylogenetic diversity as they age • Phylogenetic structure remains stable across the successional gradient • Functional traits show weak phylogenetic signal in forest succession • Second-growth forests miss some rare, evolutionarily distinct lineages • Conserving both forest types maximizes evolutionary history across landscapes