Abstract: By using Ripley’s K function, the spatial distribution patterns of tree species in a 5.2 hectares secondary forest plot in Changbai Mountain of Northeast China, as well as the spatial distribution and association of dominant tree species at their different growth stages, were analyzed. 34 tree species (27 common species and 7 rare species) were recorded, with a total of 15 688 individuals. Among the 27 common species, 23 species were mainly in aggregate distribution, and the other four had a random distribution. All the 7 rare species were distributed randomly. With the sequence of sapling → small tree → big tree, Acer barbinerve, Acer pseudosieboldianum, Fraxinus mandshurica, Abies nephrolepis, and Pinus koraiensis had a decreased aggregate distribution and tended to be distributed randomly, while other species showed no obvious change pattern in their spatial distribution. Among 45 pairs of 10 dominant tree species, 11 pairs had significant positive association, and 1 pair showed significant negative association.

Key words: Ecosystem health assessment, Korean pine and broad-leaved mixed forest, Health distance