Restoration fosters later‐successional seed rain, yet large seeds remain scarce after two decades

Seed dispersal patterns play a crucial role in tropical forest restoration, and especially for later‐successional species, which are vital for carbon storage and the structural integrity of old‐growth forests. While early‐successional species typically colonize quickly, the dispersal and establishment of later‐successional, large‐seeded species represents a consistent challenge to restoration efforts. We examined the seed deposition rate, species richness, and composition of seed rain from mid‐ and late‐successional (i.e. later‐successional) species across three restoration treatments (natural regeneration – no planting, applied nucleation – planting in patches, plantation – planting throughout) as well as in remnant reference forests in southern Costa Rica, nearly two decades after restoration began. Small‐seeded (< 5 mm) zoochorous tree species dominated seed assemblages, particularly Ficus spp., a keystone genus for frugivores. Reference forests exhibited the highest deposition rate, with values 8–11 times greater for small‐seeded, mid‐successional species and 6–11 times greater for small‐seeded late‐successional species compared to restoration plots. Large‐seeded (≥ 5 mm) species were significantly underrepresented across all restoration treatments, likely due to limited seed sources within and surrounding restoration plots. Compositional differences between restoration treatments and reference forests were minimal, suggesting convergence of the more abundant species over time. Mid‐successional species, such as Palicourea padifolia and Miconia spp., showed very high seed deposition rates in restoration treatments (up to 36 seeds m −2 year −1 in applied nucleation plots), possibly resulting from naturally recruited reproductive individuals generating successional feedbacks. Results emphasize the need for complementary restoration strategies, such as early planting of large‐seeded species and enhancing ecological interactions through landscape connectivity to promote dispersal and facilitate the establishment of later‐successional species.