Root-colonising fungi form species-rich assemblages with key functions in principal ecosystem processes, making them prospectively important players in conservation and applied ecology. Harnessing the processes and services they drive requires a better understanding of their patterns of diversity and community structure, and how these link to function. We aimed at finding possible adaptations to contrasting environmental and host conditions, indicative of participation in habitat-specific processes, by surveying heathland and grassland habitats across a latitudinal gradient in Western Europe. We sequenced fungal ITS amplicons from root and soil samples collected in the field, and from roots of model plants individually inoculated with soil from each sampling site and grown in the laboratory.