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Abstract To study the relationship between shrub roots and slope stability in loess area of northeast Qinghai— Tibetan plateau，four shrubs Caragana korshinskii，Atriplex canescens，Zygophyllum xanthoxylon and Nitraria tangutorum were planted on the slopes of the test area in Xining basin. The mechanical strength tests of root-soil composite systems were carried out and the increasing effect of slope stability of four two-year growth shrubs were simulated with two-dimensional finite element method. The results show that the horizontal and vertical displacements of four shrubs root-soil composite systems are obviously smaller than those of soil without roots. The order of four two-year growth period shrubs in the course of deformation in magnitude is Caragana korshinskii，Atriplex canescens，Zygophyllum xanthoxylon and Nitraria tangutorum. Lateral roots and main roots of shrubs play a part in reinforcement and anchorage in the soil，which increase the shear strength and the cohesion of the soil，thus the plastic area and the shearing stress concentration area can be reduced. The results of factors of safety of the slope in the testing area show that，compared with the safety factor of soil without roots，the increments of the safety factor of the related slope of the four shrubs root-soil composite systems of the four shrubs are 80.5%(Atriplex canescens)，48.7%(Caragana korshinskii)，22.1%(Zygophyllum xanthoxylon) and 8.0%(Nitraria tangutorum)，respectively. The achievements can be taken as criteria for choosing shrubs for protecting slope and preventing shallow landslide，collapsing and debris flow in loess area of northeast Qinghai—Tibetan plateau.
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Received: 08 February 2010
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2010, Vol. 29 
