Interspecific association of dominant species of wetland vegetation in the middle and lower reaches of Fenhe River,Shanxi province of China

By using χ2-test,Pearson's correlation coefficient,and Spearman's rank correlation coefficient,a quantitative study was made on the interspecific association among the 561 species pairs of 34 dominant plant species of wetland vegetation in the middle and lower reaches of Fenhe River.The χ2-test showed that among the 561 species pairs,178 pairs were positively while 256 pairs were negatively correlated,and the correlation ratio was 0.70.Pearson's correlation coefficient test showed that 157 pairs were positively while 402 pairs were negatively correlated,and the correlation ratio was 0.39.Spearman's rank correlation coefficient test showed that 216 pairs were positively while 343 pairs were negatively correlated,and the correlation ratio was 0.63.As compared with χ2-test and Pearson's correlation coefficient,Spearman's rank correlation coefficient was more sensitive.Most of the total 561 species pairs did not show significant association.The results indicated that the wetland vegetation in the middle and lower reaches of Fenhe River was at the early stage of succession.According to the adaptation to the environment and the leading ecological factors,the 34 dominant species were divided into four ecological species groups.