Fig. 2

Time-decay relationships (TDRs) at various levels of microbial communities, including (a) the entire bacterial community, b the entire fungal community, c functional groups, and (d) selected genera. The significance (asterisk) of the ω-value is determined by bootstrapping 999 times. The significance of differences between treatments was then calculated by comparing the observed slope differences with those in permuted datasets. The letter “A” in diagram (c) indicates a significant difference (P < 0.05) between the native treatment and the invasion treatment. In diagram d, the rates are scaled between − 2 and 2 in the heatmap; the unscaled mean rates are represented by green bars for native plants, red bars for invasive A. artemisiifolia, and blue bars for invasive B. Pilosa; asterisks over red or blue bars indicate significantly different rates in the invasion treatment compared to the native treatment; the scatter plot refers to the mean rates in each plant. Abbreviations: A. + C. — intercropping of A. artemisiifolia and C. serotinum; A. + S. — intercropping of A. artemisiifolia and S. viridis; B. + C. — intercropping of B. pilosa and C. serotinum; B. + S. — intercropping of B. pilosa and S. viridis. *P < 0.05, **P < 0.01, ***P < 0.001