Abstract: The broadleaved Korean pine forest is the zonal climax vegetation in the eastern mountainous region of Northeast China, and it has been subjected to intense human disturbance and largely replaced by extensive secon-dary forests and plantations since the last century. Investigating the spatial distribution patterns of dominant species and their interspecific associations in secondary forests is crucial for elucidating community assembly mechanisms and ecological processes. Based on data from a 25 hm² permanent secondary forest plot in the Xiaoxing’an Mountains, we analyzed population structures of dominant woody species with DBH≥1 cm, explored the ecological processes influencing their spatial distributions by different null models. A total of 70611 woody plants (DBH ≥1 cm) were recorded, belonging to 48 species, 39 genera, and 23 families. Acer pictum subsp. mono and Pinus koraiensis exhibited an inverted “J”-shaped diameter distribution, while Betula platyphylla, Tilia amurensis, and Betula costata displayed approximately normal distributions in diameter classes, and Corylus mandshurica displayed an “L”-shaped patttern. Under the complete spatial randomness model, C. mandshurica, P. koraiensis, and B. costata showed aggregated distributions across all scales (0-100 m), B. platyphylla, A. pictum subsp. mono, and T. amurensis showed aggregated distributions at scales of 0-81 m, 0-94 m, and 0-48 m, and random distributions at other scales. Under the Poisson cluster model, C. mandshurica, A. pictum subsp. mono, T. amurensis, and P. koraiensis showed aggregated distributions at the 0-5 m scale, B. platyphylla showed an aggregated distribution at the 0-2 m scale, B. costata showed random distributions across all scales. Under the heterogeneous Poisson model, the degree of aggregation decreased, tending toward random and uniform distributions. Interspecific associations among dominant species were primarily positive or negative. Evergreen and deciduous species mainly showed positive associations, while dominant tree species and shrubs predominantly exhibited negative associations. In conclusion, the secondary forest community showed good regeneration, with dispersal limitation and habitat heterogeneity driving the spatial patterns of dominant species. The associations among dominant species reflected a coexistence of competition and mutualism mechanisms.

Key words: natural secondary forest, point pattern, spatial distribution, interspecies association, Xiaoxing’an Mountains