Interspecific relationships among the dominants of wetland vegetation in Shanxi section of Yellow River

Based on the datasets from sampling plots, and by using Fisher’s exact test for 2×2 contingency table, Pearson correlation coefficient and Spearman rank correlation coefficient, the interspecific relationships between 24 dominants of wetland vegetation in Shanxi section of Yellow River were studied. The results indicated that there were positive associations for 33 pair-species and negative associations for 4 pair-species by Fisher exact test, positive correlations for 16 pair-species and no negative correlations for any pair-species by Pearson correlation coefficient, and positive correlations for 40 pair-species and negative correlations for 4 pair-species by Spearman rank correlation coefficient. The numerical changes between pair-species could not be reflected precisely by using Fisher exact test for 2×2 contingency table, where Pearson correlation coefficient and Spearman rank correlation coefficient should be introduced. According to the semi-matrix figure from Spearman rank correlation coefficients and the dominants’ ecological and biological characteristics, the 24 dominants were classified into xerophyte, mesophyte, hygrophyte and hydrophyte eco-species groups, with the same resource utilization ways and ecological requirements of the species in each group.