Structure and changes of broad-leaved-conifer-Korean pine mixed forest in Northeast China

The structure and species composition as well as their changes in a climax forest, dominated by Pinus koraiensis-Tilia amurensis and Fraxinus koraiensis, were ohserved with an interval of 10 years. The number of tree species was 16 in 1981, which was kept unchanged. Density was increased fr0m 510 to 535 stems/hm2, and basal area from 35.19 to 38.17 m2/hm2. Average stand DBH remained nearly unchanged. The total mortality of the stand was very low, 0.61% per year.Fraxinus and Pinus were declining in population size, the highest mortality rate for the former, and the largest death number for tlle latter. Tilia showed a rapid increasing of 14.9%, and the density of saplings (DBH 3-8 cm) was 71 stems/hm2, led the top among canopy-layer species. Acer niono, similar to Tilia, showed a type of continuous regenelation which was represented by the reverse J-shape of DBH distribution and compensation abilily to mortality. Sub-canopy species such as Acer pseudo-sieboldianum, Maackia amurensis etc. presented a stable status by self-maintenance. Based on the fact of the decreasing of dominant populations, it is predicted that the composition of the community was changing gradually, the rising of broad-leaved components versus the declining of coniferous species.