Asymmetric patterns of global diversity among plants and mycorrhizal fungi.

Questions: Although the roles of mycorrhizal fungi in different vegetation types are widely acknowledged, it is still largely unknown how the diversity and frequency of different symbiotic partners vary among plant assemblages globally. We asked (1) how the global distribution of vascular plants correlates with the diversity (i.e. number of species) and frequency (i.e. relative abundance) of different plant mycorrhizal types (i.e. arbuscular mycorrhizal [AM], ectomycorrhizal [ECM], ericoid mycorrhizal [ERM], orchid mycorrhizal [ORM] and non‐mycorrhizal [NM]); and (2) how the diversities of the most dominant plant mycorrhizal types (AM and ECM) correlate with those of their respective mycorrhizal fungal partners. Location: Worldwide. Methods: We retrieved all vascular plant occurrences available in the Global Biodiversity Information Facility database from sites worldwide where AM and ECM fungal diversity has been examined. Plant mycorrhizal types were assigned to plant species using expert‐based imputation. Diversity and frequency indices were calculated using extrapolation and bootstrapping procedures in order to account for the heterogeneity and uncertainty of the datasets. Results: Each plant mycorrhizal type correlated differently with the global diversity pattern of vascular plants, with higher total plant diversity in AM‐dominated vegetation, compared with vegetation containing a larger share of ECM, ERM or NM plant species. The diversities of AM and ECM fungi were positively correlated with the frequency, but not diversity, of their respective plant mycorrhizal types; and weakly correlated with the frequency and diversity of other plant mycorrhizal types. Conclusions: At the global scale, vascular plant distribution correlates, among other factors, with the frequency, and to a lesser extent diversity, of different mycorrhizal types of plants and fungi. Recognizing these relationships may help to predict changes in the frequency of ECM and AM plant mycorrhizal types under the different ongoing global changes. [ABSTRACT FROM AUTHOR]