Response index (mean ± SE) of functional traits of Rhus typhina in monoculture (a) and mixture (b) and Ailanthus altissima in monoculture (b) and mixture (d) under three nitrogen addition levels. Differing lowercase letters indicated significant differences according to post-hoc Tukey’s HSD test. P values represented the result of one-way ANOVA of nitrogen deposition on invasive soil legacy index of invasive R. typhina and native A. altissima. CA: crown area; A: photosynthetic rate; E: transpiration rate; SLA: specific leaf area; Chl: total chlorophyll; LN: leaf nitrogen; and LP: leaf phosphorus. N0: no nitrogen addition; N8: moderate nitrogen addition (8 N m-2 year-1); and N20: high nitrogen addition (20 N m-2 year-1). The colours of the bars represent the nitrogen addition treatments of R. typhina and A. altissima.