Statistical analysis methods
One-way analysis of variance (ANOVA) and multiple least significant difference comparisons were used to explore the differences in soil physical and chemical properties (Table 1) and soil temperature and humidity (Fig.3) between the four habitats, while 100-seed weight, seed size, number of seeds per plant, and seed yield per m2were compared between A. artemisiifolia andA. trifida (Fig. 5). ANOVA was also used to examine differences in densities, coverage, and plant heights of A.artemisiifolia ,A. trifida , and companion species between the four habitats (Fig. 4). ANOVA, multiple least significant difference comparisons, andt -tests were used to explore the differences in seed germination (Table 3), density and plant height (Fig. 6), and seed yield (Table 4) of A. artemisiifolia and A. trifida in different water gradients.IBM SPSS Statistics 20 was used for data analysis, and OriginPro 8.5 was employed for graphics.