Interspecific association among arbor species in two succession stages of spruce-fir conifer and broadleaved mixed forest in Changbai Mountains，northeastern China

Based on the use of variance ration (VR), 2×2 contingency table,χ2 test and interspecies association coefficient calculation, we examined interspecific association of dominant species both in polar-birch secondary forest and in spruce-fir forest. The results showed that mean variance of the 12 principal arbor species in poplar-birch secondary forests was 0.932, closes to 1, and had no significant correlation; but in spruce-fir mixed forest, it showed positive correlation, which indicated that the stage was relatively stable and adapted to the environmental conditions. The positive correlation of the whole community was strengthening along with the progression of succession. The end-result of competition would lead to the pioneer tree, Betula platyhylla and Populu. davidiana, which were declining species, be replaced by the zonal climax species spruce-fir forest in the future. The overall correlations among multi-species reflect the general trend among various species in community. The interspecific association further explains that the community we studied is in the transitional stage, ie from the polar-birch secondary forest to spruce-fir mixed forest.