Arbuscular mycorrhizas in a hot and arid ecosystem in southwest China

The colonization by arbuscular mycorrhizal fungi, arbuscular mycorrhizal fungal spore abundance and community were investigated in a valley-type semi-savanna vegetation of Yuan River in southwest China. Of the 62 plants representing 33 families surveyed, 59 plant species (about 95%) were arbuscular mycorrhizal and 3 species (5%) were possibly arbuscular mycorrhizal. Rhizosphere soils harbored abundant arbuscular mycorrhizal fungal spores in a range of 240-6430 per 100 g soil with an average of 2096, and most spores were small with diameter less than 70 μm (about 78%). The fungi most frequently found were members of the genera Acaulospora and Glomus. Acaulospora spinosa, A. denticulata, A. tuberculata, Glomus sinuosa, G. clarum, G. intraradices and G. microaggregatum were the most common species. These results revealed that arbuscular mycorrhizas are a common and important component in this semi-savanna vegetation; the high spore density and colonization were presumably a selective adaptation toward the hot and arid ecosystem.