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).