Interspecific relationship of dominant populations in the wetland vegetation of Sanggan River watershed,Shanxi

Interspecific relationships in wetland vegetation in Sanggan River were studied by using χ2-test, Pearson’s correlation coefficient and Spearman’s rank correlation coefficient. The results indicated that: 1) Positive association coefficients of 79 spe- cies-pairs for the χ2-test were either significant (P0.05) or high significant (P0.01) and negative association coefficients were significant or highly significant in the 16 other species-pairs. In addition, positive correlation coefficients of 51 and 61 species-pairs were significant or high significant using the Pearson’s correlation coefficient and Spearman’s rank correlation coefficient respec- tively while 34 and 14 species-pairs had significant or high significant negative correlation coefficients using these same tests. 2) Because χ2-test can not reflect numerically contrasting interspecific relationships, Pearson’s correlation coefficient and Spearman’s rank correlation coefficient were applied to test for correlation between species. Moreover, compared with Pearson’s correlation co- efficient, Spearman’s rank correlation coefficient test were more sensitive. 3) Positive association and correlation between species occur where the members of a species-pair have similar biological characteristics or traits that make them ecologically adaptive for similar habitats but have segregated niche. Negative association and correlation between species occur where species have different biological features that are differently adaptive for habitats or have overlapping niches.