Host plant and environment influence community assembly of High Arctic root-associated fungal communities

We investigated the assembly of root-associated fungal communities on six plant hosts on a glacial chronosequence in the Canadian High Arctic characterized by a non-replacement succession pattern. The plant species were Papaver lapponicum, Luzula confusa, Salix arctica, Saxifraga oppositifolia, Dryas integrifolia and Cassiope tetragona: the first two were dominated by endophytic fungi and the latter four by ectomycorrhizas, or a combination of ecto- and ericoid mycorrhizas (C. tetragona). The fungal communities on the six hosts were quite distinct and exhibited varying degrees of host specificity, but only the L. confusa community differed significantly across the chronosequence. When S. arctica was compared across additional sites with very different soil characteristics, the environment was nearly as important as the host plant in the proportion of variance explained in ordinations. The most important factors correlated with fungal community structure were pH, C:N ratio and available phosphorus.

► In a glacial chronosequence in High Arctic tundra, host plants are retained during succession and occur under a wide range of environmental conditions. ► Root-associated fungal communities were distinct on different hosts and changed from endophyte-dominated to ectomycorrhiza-dominated over the chronosequence. ► Environmental factors were also important in structuring fungal communities, with pH, C:N ratio and available P correlating most strongly with community differences.