Fungal and arbuscular mycorrhizal communities unique to old grasslands in a Swedish agricultural landscape

Fungal and arbuscular mycorrhizal communities in semi-natural grassland soils depend on management regime, but we lack knowledge about these communities in a north European agricultural landscape context. Several species inhabiting semi-natural grasslands are of a high conservational interest, but their presence in nearby short-term grasslands such as leys is unknown. We investigated fungi and arbuscular mycorrhizal fungi (AMF) using DNA metabarcoding and quantitative PCR in soils and roots in nine semi-natural grasslands and adjacent leys and assessed unique and overlapping community members and their guilds. We observed a generally higher abundance and alpha diversity of total fungi and AMF in grasslands than in leys, but only in the uppermost soil layer. At the landscape level, leys also had more similar fungal and AMF communities than grasslands. Both fungal and AMF community composition differed between grasslands and leys, with higher relative abundance of root-associated ascomycetes, saprotrophic basidiomycetes and AMF Glomeraceae in grasslands, and more pathogens and dung saprotrophs in leys. The fraction of species shared between soils and roots was higher in grasslands than in leys. We identified distinct fungal and AMF communities associated with semi-natural grasslands that could be of interest for conservation purposes. Assessing how these communities respond to management will be important for proposing conservational measures. The higher abundances of saprotrophic basidiomycetes and root-associated ascomycetes in grasslands than in leys, together with a greater overlap of species between soils and roots, suggests that processes in soils may be more interconnected with roots via fungi in semi-natural grasslands.