Abstract: Based on the data of 95 plots obtained from investigation, by using χ₂-test for 2×2 contingency table, Pearson coefficient and Spearman rank coefficient, the interspecific association and correlation among 300 species-pairs of 25 dominant plant species of Amaranthus retroflexus L. community in Shanxi were analyzed. The results indicated that: 1)The plant community was negative association, the structure of the community was scattered, few species pairs showed significant or highly significant association. 2)Only combine χ₂-test with correlation index can reflect the interspecific relationship more accurately. 3)Spearman rank correlation coefficient was more sensitive. Compared with χ₂-test and Pearson correlation coefficient, the result of the Spearman rank correlation coefficient was more reasonable. 4)According to the adaptability to the environment and the relationships between plants and environment, 25 species were divided into four ecological species groups, with the same resource utilization ways and ecological requirements of the species in each group.

Key words: invasive species, Amaranthus retroflexus L., interspecific association, ecological species groups