Abstract: In April, July, and October 2007, soil samples (0-10, 10-20, 20-30, 30-40, and 40-50 cm layers) were collected from the rhizosphere of Artemisia sphaerocephala in Shapotou area, the southeastern edge of Tenger desert, aimed to investigate the spatiotemporal variation and diversity of arbuscular mycorrhizal (AM) fungi in the rhizosphere. The hyphal colonization rate of AM fungi in the rhizosphere was 90.5%, with the spore density averaged by 5.4 ind·g^-1soil. There was an obvious spatiotemporal variation in the colonization among seasons, which was significantly correlated with soil microenvironment. A total of 21 AM fungi taxa belonging to 5 genera were isolated and identified, and the dominant species was Acaulospora laevis. Most species were found in July. The spore density was significantly positively correlated with soil organic matter content, and the species richness was significantly negatively correlated with soil available P content but positively correlated with soil temperature, spore density, and hyphal colonization rate. A. sphaerocephala could establish well symbiosis with AM fungi under natural conditions, which was the main reason for the
enhancement of the endurance capability of A. sphaerocephala in rigorous circumstance and for the maintenance of the integrity and stability of desert ecosystem.

Key words: Canopy gap, Radiation, Tropical seasonal rain forest