Forest plant roots may restrain the occurrence of shallow landslides for forest land and pioneer tree species can alsoreduce runoff and soil erosion;thus they are useful practical ecological materials for landslide control and erosion control.Inthis study,two important pioneer plant species;Formosan Alder(Alnus formosana Makino) and Roxburgh Sumac(Rhuschinensis Mill.Var.roxburghi i(DC.) Rehd.) were selected at landslide areas under vegetation treatments for soil and waterconservation.In order to obtain the root strength model for the factors affecting pulling resistance and root tensile strength,experimental materials were tested and the data were analyzed using regression techniques.These models could be used toprovide the index of slope stability and to quantify the root-strength using non-destructive methods. Forest plant roots may restrain the occurrence of shallow landslides for forest land and pioneer tree species can alsoreduce runoff and soil erosion; thus they are useful practical ecological materials for landslide control and erosion control. Identity study, two important pioneer plant species; Formosan Alder ( Alnus formosana Makino) and Roxburgh Sumac (Rhuschinensis Mill. Var. Roxburghi i (DC.) Rehd.) Were selected at landslide areas under vegetation treatments for soil and waterconservation. Order to obtain the root strength model for the factors affecting pulling resistance and root tensile strength, experimental materials were tested and the data were analyzed using regression techniques. these models could be used toprovide the index of slope stability and to quantify the root-strength using non-destructive methods.