Relationship of Soil Erodibility, Soil Physical Properties, and Root Biomass with the Age of caragana Korshinskii Kom. Plantations on the Hilly Loess Plateau, China

Changes in soil properties caused by artificial vegetation planting is of great interest to both scientists and policy-makers. However, a quantitative understanding of the effects of Caragana planting on soil erodibility is not available. This study selected five Caragana plantations aged 0 (control), 9, 21, 33 and 46 years to assess the erosion resistance of Caragana soils using spatio-temporal substitution method in Zhi Fanggou small watershed on the hilly Loess Plateau. Findings showed that Caragana planting significantly reduced soil loss compared with the control. Sediment loss over time was well described by a negative exponential function. On average, about 80% of the soil sediment was lost within the first 3 abrasion minutes. Compared with control, soil bulk density of surface (0-20cm) and middle soil layers (20-40cm) decreased by 8.9% and 18.0%, respectively, but minimal changes occurred in the lower soils (40-60cm). Soil aggregate content and shear strength increased significantly, whereas soil disintegration rate decreased significantly, with a maximal reduction of 357.1% in the middle soil layer. Soil erosion resistance increased 9.3, 4.1 and 4.2 fold in the surface, middle and lower soils, respectively. Linear regression equations could well fit the relationship between soil erosion resistance and soil physical properties, with root biomass. Soil aggregate content and root density were the key factors in the reinforcement of soil erosion resistance for Caragana plantations on the hilly Loess Plateau.