Diversity and distribution of arbuscular mycorrhizal fungi along altitudinal gradients in Mount Taibai of the Qinling Mountains.

Elevational patterns of plant and animal diversity have been studied for centuries; however, the effects of land elevation on arbuscular mycorrhizal (AM) fungal diversity remains unclear. We examined AM fungal diversity and distribution along 19 elevation belts in Mount Taibai of the Qinling Mountains, with the aim to assess the altitudinal diversity patterns. In total, 63 AM fungal taxa belonging to 12 genera were discovered. Mycorrhizal colonization rates on roots; AM fungal spore density; and fungal species richness, evenness, and diversity had different patterns in terms of the changes of elevation. Root colonization followed a cubical parabolic pattern, with a peak and a foot at an elevation of about 2000 and 3000 m above sea level, respectively. Species richness decreased monotonically from the lowest to the highest elevations. Spore density and α-diversity exhibited a unimodal pattern and peaked at an elevation of 2107 and 1350 m, respectively. Species evenness increased monotonically at an elevation of between 1050 and 2250 m. β-Diversity also presented a basically incremental pattern along altitudinal gradients. Our findings suggest that elevation changes were the main factor governing the patterns of AM fungal diversity.