© 2014, Springer Science+Business Media Dordrecht. Nothing is published about the arbuscular mycorrhizal fungi (AMF) of the Azores archipelago, either with regard to individual species, or at the community level. This study, based on identification through spore morphological characteristics, compares the AMF community structure of semi-natural and intensively managed pastures. Thirty-nine glomeromycotan fungal spore types were detected in soil, with species in the genera Acaulospora, Ambispora, Archaeospora, Claroideoglomus, Entrophospora, Gigaspora, Paraglomus, Sclerocystis, Scutellospora sensu Morton and Msiska (Mycorrhiza 20 483–496, 2010) and Rhizophagus. The two most representative groupings were the glomoid spore types and Acaulospora with 13 and 10 species respectively, followed by Scutellospora with 3. The glomeromycotan fungal richness was similar for both intensive and semi-natural pastures, with 28 spore types in the former and 23 in the latter but their composition differed. Semi-natural pastures were dominated by species from Acaulospora and Scutellospora, particularly S. calospora and A. cf. myriocarpa, while for intensively farmed pastures, species with glomoid spores, and members of the two genera Claroideoglomus and Paraglomus were found most frequently and abundantly. Spore densities of the most commonly found groupings — Acaulospora, Claroideoglomus, Scutellospora and the glomoid spores were correlated with soil chemical properties, suggesting that soil characteristics influence the AMF communities. These results indicate that intensity of pasture management may not influence AMF richness but is probably an important factor influencing their composition and abundance.