A study of the mechanical effects of shrub roots for slope protection in frigid and arid-semiarid loess area

The pull-resistance was determined by the in situ pull-out test for four twoyear-old brush species,including Caragana korshinskii,Antiplex canescens,Zygophyllum xanthoxylon,Nitraria tangutorum.The distribution characteristics of root system were studied and the slope protection effects of these brushes were analyzed.The results indicate that the main distribution type of root is straight root system,and the main branch roots distribute at a depth of 20～80cm below land surface.The order of the four brush species pull-resistance is Caragana korshinskii>Antiplex canescens>Nitraria tangutorum>Zygophyllum xanthoxylon.There exists a power relation between the pull-resistance and the diameter,a linear relation between the pull-resistance and the branch root quantity,and a exponential relation between the pull-resistance and the plant height.Pull-resistance increases with increasing biological indexes,and the increasing extent of Caragana korshinskii and Antiplex canescens are bigger than Nitraria tangutorum and Zygophyllum xanthoxylon.Considering the distribution characteristics of root system and the mechanical effects,Atriplex canescens and Caragana korshinskii can be taken as the good shrubs for slope protection in frigid and arid-semiarid loess area.