Abstract: The magnitude of soil anti-scouribility depends on the physical condition of the soil. Plant roots can greatly enhance soil stability and anti-erodibility. A scouring experiment of undisturbed soil was conducted to investigate the effects of roots on soil anti-scouribility and its distribution in the soil profile. At the end of each erosion test, plant roots were collected from soil samples and root surface area was calculated by means of a computer image analysis system (CIAS). Root surface area density (RSAD), the surface area of the roots per unit of soil volume, was related to soil anti-scouribility. More than 83% of root surface area was concentrated in the 0 – 30 cm soil layer. Soil anti-scouribility increased with an increase in RSAD and the value of intensified soil anti-scouribility (rAS) can be expressed by exponential equations, depending on the plant species. These equations were rAS = 9.578 6 RSAD0.832 1 (R2 = 0.951) for afforested Pinus tabulaeformis Carr., rAS = 7.808 7 RSAD0.789 4 (R2 = 0.974) for afforested Robinia pseudoacacia L., and rAS = 9.256 6 RSAD0.870 7 (R2 = 0.899) for Bothriochloa ischemum L.

Key words: Loess Plateau, root surface area, root, soil anti-scouribility.