Influence of regionally dominant mycorrhizal type
In spite of the wide variation in ecosystems, all 8 regions where EcM and ErM associations occurred (all except India, Argentina and Chile) showed the pattern of increased AM vegetation cover and decreased EcM and ErM vegetation cover in roadside plots (Table 2). Importantly, however, the difference in proportion of mycorrhizal-type associations between the vegetation of the roadside plots and that of the adjacent plots was larger in plots (and regions) where AM plant species had a lower representation in the native natural vegetation (Fig. 3). In general, the lower the percentage cover of AM-dominated species in the natural vegetation, the higher the increase in AM-dominated species in the roadside plot (Fig. 1, as indicated by a flatter line above the 1:1 in Fig. 3). This effect mirrored the pattern we described for soil temperature, in plots for which the natural vegetation was in the upper range of AM vegetation cover we did observe a reversal of the general pattern: AM vegetation cover was lower in the roadside when compared to the adjacent vegetation with the vegetation being more NM instead (Fig. 3, regression line crossing the 1:1-line).