Variation Analysis on Kernel Oil Content and Its Fatty Acid Composition in 31 Superior Amygdalus pedunculata Individuals from Mu Us Desert Diversity and spatial distribution of arbuscular mycorrhiza fungi of phalanx clonal plant in the Mu Us desert Phosphorus contents in the rhizosphere and bulk soil under Amorpha fruticosa established in different years Effect of different vegetation types on soil organic carbon in Mu Us desert