Competitiveness of the Exotic Silphium perfoliatum against the Native Urtica dioica: A Field Experiment

Figure 5

Plant projection area (a, b), plant height (c, d) of S. perfoliatum (a, c), and U. dioica (b, d) depending on the treatment: control without surrounding plants (white box), surrounded by S. perfoliatum (S around, yellow box), and surrounded by U. dioica (U around, green box). Precipitation is given as the sum of April to August of the respective year. n = 9 (except S. perfoliatum with U around n = 8). Different letters indicate significant differences in the respective year (Tukey’s post hoc test on LMs with nontransformed plant height or log-transformed projection area).