Fig. 2: Plant–fungal richness correlations (Spearman) at the global, biome, and ecoregion levels.

Correlations are shown for arbuscular mycorrhizal (AM) fungi (A–C) and ectomycorrhizal (ECM) fungi (D–F). A, D Show global-level relationships based on values from 10,000 randomly selected grid cells of the consensus plant and fungal richness maps (see ‘Methods’). Trend lines show linear fits. B, E Show the distribution of correlations re-calculated within biomes and ecoregions (from 10,000 randomly selected grid cells in each biome and 1000 cells in each ecoregion; boxes show median and interquartile range, whiskers show 1.5 times the interquartile range). Maps (C, F) show ecoregion polygons¹⁵ coloured by correlation strength. Negative correlations are shown in red and positive correlations in blue. Biome correlation outliers in (B, E) are labelled with biome names. Grey areas were excluded from the analyses due to high uncertainty in the original alpha diversity predictions or where predictions for each taxonomic group by the different studies strongly disagreed (mostly based on the coefficient of variation between bootstrap model replicates; see ‘Methods’). Maps showing non-linear relationships from GAMs between plant and fungal richness at the ecoregion scale, and a comparison between the Spearman correlation coefficients and deviance explained by the GAMs, are provided in Supporting Information Figs. S2 and S3.