The type and intensity of land use are important drivers of local aboveground biodiversity. The same holds for arbuscular mycorrhizal (AM) fungi, but most research effort has been put into natural or, on the other hand, intensively managed habitat types. In this recent study, PhD student Siim-Kaarel Sepp and co-authors investigated the diversity patterns of AM fungi in a range of six common Estonian habitat types that also included semi-natural land use such as alvar grasslands or wooded meadows.

Surprisingly, mean AM fungal richness per sample did not differ among habitat types, but the AM fungal community composition clearly shifted with land use intensification (forest vs forest clear-cut). Meanwhile, abandonment and concurrent overgrowing of alvar grasslands only resulted in a marginal shift in AM fungal composition.

Furthermore, the study found that when comparing AM fungal communities in soil and in roots of a single host plant species, the AM fungi in roots are more similar among different habitat types. This could indicate that although little host specialization is expected in arbuscular mycorrhizal symbiosis (ca 300 AM fungal taxa interact with ca 80% of terrestrial plants), the host plant still may act as an additional filter in AM fungal community assembly by effectively selecting a suitable subset of AM fungi from the general soil species pool.

Citation: Sepp, S. K., Jairus, T., Vasar, M., Zobel, M., & Öpik, M. (2018). Effects of land use on arbuscular mycorrhizal fungal communities in Estonia. Mycorrhiza, DOI: 10.1007/s00572-018-0822-3. (link to full text)

Restored alvar grassland in Saaremaa, western Estonia (pic from here)

Abstract:

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.