Effects of Biological Soil Crusts Development on Soil Erosion Resistance on Loessial Soil

[Objective] The extensive development of biological soil crusts driven by the project of “Grain for Green” on the Loess Plateau can significantly inhibit soil erosion, but the characteristics of soil erosion resistance and the response mechanism with the growth and development of biological soil crusts are still unclear. [Methods] Algal crusts, moss crusts, and natural succession crusts were cultivated for 176 days to systematically study the effects of different developmental stages and types of biological soil crusts on loessial soil erosion resistance. [Results] (1)The coverage, thickness, biomass, chlorophyll and roughness of the biological soil crusts increased significantly with growth time, and the moss crusts were higher at the beginning of cultivation and the natural succession crusts were highest at the end of cultivation. (2) With the development of biological soil crusts, the cohesion increased as a power function, which increased by 39.8%~60.3% compared with the initial period; the mass loss rate decreased exponentially, which decreased by 45.6%~57.3% compared with the initial period; and the saturated hydraulic conductivity (Ks) was more complex, but the Ks was lowest at the end of cultivation (0.08~0.12 mm/min). (3) Soil cohesion increased as a power function with the increase of coverage, thickness, chlorophyll, biomass and roughness, and the mass loss rate decreased exponentially with the increase of coverage, thickness, chlorophyll, biomass and roughness. (4) The comprehensive index of soil erosion resistance (Cser) constructed based on soil properties can effectively show the effect of biological soil crusts development on soil erosion resistance. And the Cser can be expressed as a power function of coverage (Cov), thickness (T) and biomass (B) (Cser=0.279 Cov0.194T0.188B0.119, R2=0.73, p