Mann-Whitney test was used when there were only two categories in the environmental variable, while Kruskall-Wallis analysis was applied when three or more categories existed. Furthermore, Spearman rank correlation analysis was undertaken to study the correlation coefficient between two variables. Finally, ordination was applied to
produce a meaningful summary of the patterns underlying the multivariate data in this study, and investigate the relationships between environmental variables and data of species and earthworm ecological groups. Detrended Correspondence Analysis and Redundancy Analysis were used, and the outcomes were visualized by biplots. Further analysis was carried out by XY attribute plots with general linear modelling testing whether a significant relationship existed.