Abstract:

Tree mortality, usually resulting from interactions among multiple factors, is a crucial process in forest dynamics. Using two census datasets (2004 and 2009) from a 25 ha plot in the Changbai Mountains, we analyzed the composition, size class structure and spatial distribution of individual trees (DBH ≥ 1 cm) that died during the 5-year period. The number of species went from 52 in 2004 to 51 in 2009, with 3 species disappearing and 2 others appearing. The number of individuals changed from 36,908 to 34,926, with 4,030 dying and 2,048 being recruited. The number of dead individuals accounted for 10.9% of total individuals in 2004. Species with high mortality also tended to have high recruitment. Compared with tree species, shrub species had both higher mortality and recruitment rates. In addition, 44 species showed an increased mean DBH in 2009, while the mean DBH of 5 other species decreased. Mortality decreased as DBH increased. Size class distributions of dead dominant species in different vertical layers were similar in the two censuses. Spatial distributions of dead individuals were species-specific. Dead individuals from smaller size classes were spatially clumped at small scales and became randomly spaced at larger scales. However, dead individuals from larger size classes tended to show random distribution at various scales.

Key words: tree mortality, growth, recruitment, size class structure, spatial distribution, broad-leaved Korean pine (Pinus koraiensis) mixed forest, Changbai Mountains