Variation in soil erosion resistance of slips deposition zone with progressive vegetation succession on the Loess Plateau, China

Purpose Soil slips are widely distributed on the Loess Plateau. Most of them have experienced an ecological succession process, which has strong effects on the near-surface characteristics, and thereby influences soil detachment capacity by overland flow (D-c). This study quantified the effects of progressive succession of the deposition zone of soil slip on D-c and soil resistance to flowing water erosion reflected by rill erodibility (K-r) and critical shear stress (tau(c)) on the Loess Plateau. Materials and methods Soil samples (diameter 10 cm, height 5 cm) were taken from seven deposition zones of soil slips covered by typical plant communities with different succession stages restored for 1 to 31 years. A 37-year grassland where no slip occurred covered by climax community was selected as the control. A hydraulic flume (4.0 m in length, 0.35 m in width) with a slope ranging from 0 to 60% was applied to determine D-c. Biological crusts thickness, soil texture, bulk density, cohesion (CH), water stability ability (WSA), organic matter content, root mass density (RD), and plant litter density (LD) were measured for each site. Results and discussion The measured D-c decreased rapidly when the soils were restored for 1 to 21 years, and then gradually leveled off. D-c could be well estimated by flow shear stress, CH, WSA, RD, and LD (NSE = 0.95). K-r decreased rapidly with succession till attained a stable stage after 21 years of succession. K-r could be well simulated by CH, WSA, RD, and LD (NSE = 0.92). tau(c) increased generally with succession, although it fluctuated from 10 to 31 years. The temporal variation of tau(c) was dominantly controlled by the biological crusts thickness and the content of WSA. Conclusions Natural ecological succession is an effective approach to promote soil resistance to flowing water erosion for the deposition zone of soil slip. The near-surface characteristics, such as CH, WSA, RD, and LD, were the key factors to control soil erosion for the deposition zone of soil slip on the Loess Plateau.