Fig. 1.

Mycorrhizal colonization (percentages; mean ± SD) of Rudbeckia laciniata and Solidago gigantea grown in the fallow and river valley soils. Mycorrhizal parameters: mycorrhizal frequency (F), relative mycorrhizal root length (M), and relative arbuscular richness (A) (see the “Materials and methods” section for a description of these parameters). Within each plant species, the lowercase letters above the bars indicate the statistically significant interaction between the fungus and soil effects; the capital letters show the significant main effect of the fungus; the different letters above the bars indicate statistically significant differences; the asterisks (*) indicate the significant main effect of the soil; for each P < 0.05 (see Table 2 for details on the main effects and interactions)