RESUMO
By measuring the surface shear strength of Nitraria tangutorun nebkhas at different succession stages in the fringe of Minqin oasis, and selecting several typical nebkhas at stabilizing stage to investigate its surface erosion rates before and after removing crust and vegetation, the surface erosion-resistance of N. tangutorun nebkhas and related affecting factors were studied. The results showed that the nebkhas had the highest surface shear strength (0.31-0.79 kg cm(-2)) at stabilizing stage, and the lowerest one (0.06-0.15 kg cm(-2)) at rudimental stage. The surface shear strength of nebkhas at stabilizing stage was significantly higher than that at other succession stages (P <0.01), and at the other succession stages except degradation stage, there was no significant difference in the surface shear strength in windward and leeward (P >0.05). After removing crust and vegetation, the surface shear strength of nebkhas at stabilizing stage was greatly reduced, with the difference before and after removing the crust and vegetation being significant (P <0.01). However, there was no obvious difference between different slope positions (P >0.05). Keeping both vegetation and crust, deposition occured on both slope positions of nebkhas; removing crust but keeping vegetation, the deposition reduced a little; removing vegetation but keeping crust, the deposition reduced greatly; while removing both vegetation and crust, nebkhas surface was severely eroded.