Restoration Method Influences Spatial Patterns of Tree Seedling and Sapling Recruitment in the Second Decade of Tropical Forest Recovery

ABSTRACT Aims Fine‐scale floristic heterogeneity is a hallmark of mature tropical forests. Restoring such patterns in degraded habitats should produce more resilient and biodiverse systems, yet these end‐goals are rarely compared across multiple restoration scenarios. We analyzed fine‐scale spatial tree recruitment patterns in a long‐term tropical forest restoration experiment. Location Coto Brus County in southern Costa Rica, 1100–1430 m above sea level. Methods We censused seedlings and saplings in 26 experimental restoration plots (0.25 ha) after 16–18 years and six reference forests. Restoration treatments included the following: (1) plantation—four tree species planted in rows; (2) applied nucleation—six tree nuclei of varying sizes planted with the same four species; and (3) natural regeneration—no trees planted. In 2022, we censused all tree stems ≥ 20 cm and mapped each to 3 × 3 m grid cells. Results Mean local species density of seedlings (per 6 × 6 m quadrat) was significantly greater in plantation (10.9; 95% CI = 10.0–11.9) and applied nucleation (8.4; 95% CI = 7.7–9.3) than in natural regeneration subplots (5.0; 95% CI = 4.5–5.5), as the latter commonly had quadrats with no recruits. Within‐plot Bray–Curtis dissimilarity was highest in natural regeneration, intermediate in applied nucleation, and lowest in plantations. Differences arose primarily from variation in seedling abundance, rather than from species turnover, but did not differ in sapling communities. Recruits of large‐seeded, later‐successional species were significantly less clustered and established more frequently in plot interiors of planted treatments than of natural regeneration. Conclusions After nearly two decades, the extent of initially planted trees did not substantially influence the fine‐scale heterogeneity of recruit community composition beyond spatial variation in seedling density. However, both applied nucleation and plantation restoration approaches resulted in a more even spatial distribution of large‐seeded recruits, highlighting the importance of tree planting for facilitating the recovery of dispersal‐limited species.