Effects of land use on arbuscular mycorrhizal fungal communities in Estonia

Arbuscular mycorrhizal (AM) fungal communities vary across habitat types, as well as across different land use types. Most relevant research, however, has focused on agricultural or other severely human-impacted ecosystems. Here, we compared AM fungal communities across six habitat types: calcareous grassland, overgrown ungrazed calcareous grassland, wooded meadow, farmyard lawn, boreonemoral forest, and boreonemoral forest clear-cut, exhibiting contrasting modes of land use. AM fungi in the roots of a single host plant species, Prunella vulgaris, and in its rhizosphere soil were identified using 454-sequencing from a total of 103 samples from 12 sites in Estonia. Mean AM fungal taxon richness per sample did not differ among habitats. AM fungal community composition, however, was significantly different among habitat types. Both abandonment and land use intensification (clearcutting; trampling combined with frequent mowing) changed AM fungal community composition. The AM fungal communities in different habitat types were most similar in the roots of the single host plant species and most distinct in soil samples, suggesting a non-random pattern in host-fungal taxon interactions. The results show that AM fungal taxon composition is driven by habitat type and land use intensity, while the plant host may act as an additional filter between the available and realized AM fungal species pool.