Abstract:Seven native xeromorphic shrub species inhabiting in the Alashan desert, including Nitraria tangutorum, Zygophyllum xanthoxylum, Reaumuria soongorica, Ammopiptanthus mongolicus, Atraphaxis bractata, Haloxylon ammodendron and Ceratoides lateens, are used to investigate and compare differences in contents of total P, available P, and P fractions between bulk and rhizosphere soils. It is found that there is a higher available P concentration in the rhizosphere soil than in the bulk soil for all seven shrubs, but concentrations of total P, DHCl-Pi and HHCl-Pi are lower in the rhizosphere soil than in the bulk soil in all shrubs except A. bracteata. Our results also showed that the H2O-P concentration is lower in the rhizosphere soil than in the bulk soil in all shrubs except H．ammodendron, whereas concentrations of NaHCO3-Pi、DHCl-Pi and HHCl-Pi are lower in the rhizosphere soil than in the bulk soil in C．lateens and that the NaOH-Po concentration is lower in the rhizosphere soil than in the bulk soil in all shrubs except A．mongolicus, as well as the HHCl-Po concentration is lower in the rhizosphere soil than in the bulk soil in all shrubs. Regression analyses indicated a significant relationship between available P concentration and pH, but no significant relationships are found between total P concentration and pH in both the rhizosphere and bulk soils.