Results of Threshold Indicator Taxa Analysis (see Methods section for interpretation of the graph) for a nutrient-poor sites with P. serotina (n = 47 plots) b nutrient-rich sites with P. serotina (n = 48 plots) c nutrient-poor sites with R. pseudoacacia (n = 48 plots) d nutrient-rich sites with R. pseudoacacia (n = 48 plots). Grey/blue density estimators represent species responding negatively to invader biomass gradient (decliners) while red color – positively (increasers). We included here only responses for species that were both reliable (reliability ≥ 0.95) and pure (purity ≥ 0.95). For statistics of all species see Suppl. material 1: tables S5–S8.