Early Postfire Regeneration Determines Long‐Term Successional Trajectories in Temperate Pinus densiflora Forests of Korea

ABSTRACT Aims This study examines how burn severity and postfire initial regeneration shape long‐term forest recovery and successional trajectories in cool‐temperate Pinus densiflora forests of Korea. Location Samcheok‐si, Gangwon Province, Republic of Korea, affected by the large‐scale East Coast Fire of 2000. Methods Permanent plots were established in five stand types representing unburned (UB), light‐burn (LB), and severe‐burn (SB) conditions and, within SB stands, high (H), intermediate (I), and low (L) initial regeneration levels. Vegetation structure and species composition were monitored repeatedly over 20 years and analyzed using generalized additive mixed models and ordination techniques. Results Postfire vegetation developed along distinct successional trajectories that were established shortly after fire and persisted throughout the 20‐year monitoring period. Temporal changes in vegetation structure and species richness differed consistently according to burn severity and postfire initial regeneration pattern. Tree regeneration played a central role in vertical stratification and canopy development. SB stands with high initial regeneration rapidly developed early‐stage forest structure and showed increasing dominance of Quercus and associated deciduous species. In contrast, stands with low regeneration exhibited delayed canopy development and prolonged dominance of shrub and herbaceous layers. LB stands followed a distinct recovery pathway, retaining P. densiflora dominance through the persistence of surviving canopy trees. Variation in regeneration level among SB stands resulted in divergent trajectories, ranging from Quercus ‐dominated stands to mixed Quercus – P. densiflora forests, indicating a successional shift away from prefire pine dominance. Species richness exhibited hump‐shaped temporal dynamics following fire. Conclusions Postfire initial regeneration provides a strong and persistent signal of long‐term forest structure and successional trajectories. In particular, within SB stands, differences in early regeneration level further constrained recovery pathways for at least two decades. These findings highlight early postfire regeneration as a practical indicator for anticipating long‐term forest development and guiding postfire management strategies.