Altitudinal distribution patterns of AM fungal assemblages in a Tibetan alpine grassland.

A better understanding of Glomeromycotan biogeography is essential for the conservation of arbuscular mycorrhizal (AM) fungal species and the ecosystem services that they provide worldwide. Here, we examine the spatial dynamics of AM fungi along two slopes (4149 m a.s.l. to the summit at 5033 m a.s.l.) of Mount Mila on the Tibetan Plateau. Our hypothesis was that AM fungal communities at higher elevation would show distinct assemblages with lower diversity in conditions of increasing environmental harshness. A total of 52 operational taxonomic units (OTUs) spanning all four orders were detected and some OTUs were habitat specific. Nearly 30% of the OTUs were new phylotypes, including two family-like clades. Distinct communities of AM fungi were found at the higher elevation, demonstrating potential niche differentiation along the elevation gradient. Elevation patterns of taxon richness/diversity differed between the two transects, decreasing with increasing elevation on the eastern slope and unimodal (or no pattern) on the western slope. Taken together, we provide evidence for significant spatial structure of AM fungi across the elevation gradient, and the distribution patterns are regulated simultaneously by the plant communities, soil properties and climatic conditions in this plateau montane ecosystem. [ABSTRACT FROM AUTHOR]