Interspecific relationships of dominant species in Forsythia suspensa communities in Taiyue Mountain of Shanxi, China

Based on the 2 × 2 contingency table, and by adopting χ2-test, variance ratio (VR), Pearson’s correlation, and Spearman’s rank correlation, a quantitative study was conducted on the interspecific association among the 300 species pairs of 25 dominant species in Forsythia suspensa communities in Taiyue Mountain, Shanxi of China. The variance analysis showed that the overall interspecific association of the 25 dominant species was not significant, and the species distribution was relatively independent. The χ2 test showed that there were 138 species pairs in positive association, and 150 species pairs in negative association, with the association ratio being 0.92. The Pearson’s correlation coefficient test showed that 100 species pairs were in positive association, and 199 species pairs were in negative association, with the association ratio being 0.5. The Spearman’s rank correlation coefficient test showed that 121 species pairs were in positive association, and 179 species pairs were in negative association, with the association ratio being 0.67. Compared with χ2 test, Pearson’s correlation coefficient and Spearman’s rank correlation coefficient tests had higher sensitivity. According to the adaptation ways of the species to the environment and the leading ecological factors, in combination with principal components analysis, the 25 dominant species were divided into four ecological species groups.