Global patterns in mycorrhizal types
Over the whole dataset, AM plants accounted for 71.3% of all plant
species with an assigned mycorrhizal association, EcM plants accounted
for 7.0%, ErM for 4.2%, NM for 15.8% and Orchid Mycorrhizas (OM) for
0.1%. These numbers are similar to the proportions per mycorrhizal type
found by Soudzilovskaia et al., 2020 across the entire FungalRoot
database (AM: 70%, EcM: 8%, ErM: 2%, OM: 1%, NM: 17%). The
distribution of mycorrhizal types amongst native species in our data was
likewise broadly similar to that of the FungalRoot database (AM: 79.3%,
EcM: 6%, ErM: 3%, OM: 0.6%, NM: 10.3%). As expected, the majority of
non-native species were found to associate with AM or to be
non-mycorrhizal (AM: 85.6%, EcM: 0.3%, ErM: 0%, OM: 0%, NM: 14.1%).
Mycorrhizal type distribution also varied with region (Fig. 1): AM plant
species made up more than half of all vegetation in almost all regions
except for Norway, where ErM vegetation was dominant. In Argentina,
Armenia, Chile and India there was no or almost no EcM and ErM
vegetation, with all plants being either AM or NM.
Globally, our models showed that both EcM and ErM vegetation cover
decreased with increasing mean annual soil temperatures, while AM and NM
vegetation cover increased (Table 1). This effect of temperature on EcM
and ErM vegetation remained mostly consistent across regions while there
was a high variability of responses for AM and NM vegetation (Table 2).