Distribution of arbuscular mycorrhizal fungi and soil enzyme activities in the rhizosphere of Artemisia ordosica in desert
荒漠油蒿（Artemisia ordosica）根围AM真菌分布与土壤酶活性

Soil samples in the rhizosphere of Artemisia ordosica distributed in west and northwest China desert were collected in October 2007 to isolate arbuscular mycorrhizal(AM) fungi, and to determine the soil enzyme activity in 0-10, 10-20, 20-30, 30-40 and 40-50 cm soil layers. The results showed that AM fungi had a relatively high hyphal colonization rate on the roots of A. ordosica, and the hyphal colonization rate was significantly and positively correlated with vesicular colonization rate. However, the colonization of hyphae, vesicles and arbuscules was not correlated to spore density and soil enzyme activities, while spore density was different among sites and soil depths, and was significantly and positively correlated with available P, N, and organic matter contents, urease and acid phosphatase activites. The correlation between the spore density and alkaline phosphatase activity was affected by pH. The maximal value of spore density occurred at the 0-10cm layer, and then gradually decreased with soil depth.The soil enzyme activities showed the same trend as the spore distribution. There was an obviously positive correlation between the activity of the three soil enzymes and soil fertility. This suggests that A. ordosica could establish well symbiosis with AM fungi, which was the main reason for maintaining integrity and stability of the desert ecosystem.