Soil and geography are more important determinants of indigenous arbuscular mycorrhizal communities than management practices in Swiss agricultural soils

<jats:title>Abstract</jats:title><jats:p>Arbuscular mycorrhizal fungi (<jats:styled-content style="fixed-case">AMF</jats:styled-content>) are ubiquitous soil fungi, forming mutualistic symbiosis with a majority of terrestrial plant species. They are abundant in nearly all soils, less diverse than soil prokaryotes and other intensively studied soil organisms and thus are promising candidates for universal indicators of land management legacies and soil quality degradation. However, insufficient data on how the composition of indigenous <jats:styled-content style="fixed-case">AMF</jats:styled-content> varies along soil and landscape gradients have hampered the definition of baselines and effect thresholds to date. Here, indigenous <jats:styled-content style="fixed-case">AMF</jats:styled-content> communities in 154 agricultural soils collected across Switzerland were profiled by quantitative real‐time PCR with taxon‐specific markers for six widespread <jats:styled-content style="fixed-case">AMF</jats:styled-content> species. To identify the key determinants of <jats:styled-content style="fixed-case">AMF</jats:styled-content> community composition, the profiles were related to soil properties, land management and site geography. Our results indicate a number of well‐supported dependencies between abundances of certain <jats:styled-content style="fixed-case">AMF</jats:styled-content> taxa and soil properties such as <jats:styled-content style="fixed-case">pH</jats:styled-content>, soil fertility and texture, and a surprising lack of effect of available soil phosphorus on the <jats:styled-content style="fixed-case">AMF</jats:styled-content> community profiles. Site geography, especially the altitude and large geographical distance, strongly affected <jats:styled-content style="fixed-case">AMF</jats:styled-content> communities. Unexpected was the apparent lack of a strong land management effect on the <jats:styled-content style="fixed-case">AMF</jats:styled-content> communities as compared to the other predictors, which could be due to the rarity of highly intensive and unsustainable land management in Swiss agriculture. In spite of the extensive coverage of large geographical and soil gradients, we did not identify any taxon suitable as an indicator of land use among the six taxa we studied.</jats:p>