Seasonal variations in soil erosion resistance under tap and fibrous root systems grasslands on the Chinese Loess Plateau

• The rill erodibility decreased as a power function during one growing season. • Fibrous root systems reduced rill erodibility 65% more efficiently than tap root systems. • The rill erodibility could be effectively predicted from water-stable aggregate content and root surface area density. Vegetation growth can induce the seasonal variation in soil erosion resistance during a growing season, reflected by rill erodibility ( Kr ) and critical shear stress ( τ c ). However, few studies have been conducted to quantify the seasonal variations in erosion resistance under different root type grasslands. This study was conducted on the seasonal variations in soil erosion resistance under tap and fibrous root systems grasslands on the Chinese Loess Plateau, and quantified the potential influencing factors of soil erosion resistance. The undisturbed soil samples were collected over 30-day intervals from April to September 2021. Soil detachment capacity by concentrated flow was measured in a hydraulic flume with the fixed bed under six shear stresses to determine soil erosion resistance. The results showed that the Kr decreased over the growing season as a power function, and the Kr of annual herbaceous plants decreased faster than that of perennial herbaceous plants. Compared with the bare control soil, the Kr of grasslands decreased by 4.07–95.78 %, τ c increased by 141.26–176.35 %. Generally, the Kr of annual herbaceous plants was 11.58 times higher, and τ c was 15.48 % lower than perennial herbaceous plants. Differences in Kr were also observed between plants with tap and fibrous root systems. Plants with tap root systems had a higher Kr , which was 2.83 times that of plants with fibrous root systems. Plant root systems and soil were all affected in terms of Kr and τ c , root system and soil contributions were 41.0 and 3.4 % for Kr , and 9.1 % and 18.8 % for τ c , respectively. In addition, Kr decreased exponentially with increasing root mass, length, and surface area density, and also decreased with increasing bulk density, cohesion, and water-stable aggregate content. The τ c increased with increasing bulk density as a power function. Finally, Kr was effectively predicted from using water-stable aggregates content and root surface area density. The performance of the developed model is satisfactory ( NSE = 0.85).