Ephemeral gully erosion (EGE) is a major driver of cropland soil degradation, exerting substantial impacts on soil properties and crop growth. These changes, in turn, profoundly alter soil erosion resistance (SER). Although SER is critical for soil conservation, its spatial patterns and driving mechanisms in long, gently sloping (LGS) cropland under the influence of EGE remain insufficiently understood. The aims of this study were to quantify the spatial variation in SER and to identify the influencing factors on a representative LGS cropland in the Mollisol region of Northeast China. Based on in-situ field sampling and controlled flume tests, the spatial heterogeneity of SER under EGE conditions was quantified. The dominant influencing factors and their interactive mechanisms were identified, and a stepwise regression model was developed to estimate rill erodibility (Kr). Results showed that SER varied significantly across slope positions but did not differ markedly between gully positions. Kr linearly increased with decreasing gully position, while critical shear stress (τc) first decreased and then increased, with variation ranges of −2.36 % to 50.00 %. Both Kr and τc showed quadratic relationships with slope position, with Kr peaking at the middle slope and τc at the upper slope. Dominant factors affecting Kr included clay content, sand content, soil cohesion (Coh), mean weight diameter (MWD), root mass density (RMD), and straw mass density (SMD), which collectively explained 79 % of the spatial variability. Notably, SMD had a significant regulatory effect on Coh, RMD, and MWD, and indirectly reduced Kr via these pathways (standardized path coefficient = −0.263). The developed Kr estimation model (Kr = 0.212MWD−2.405RMD−0.502) exhibited good predictive performance (R² = 0.860; NSE = 0.863) but requires further validation under field conditions. The findings provide important theoretical support for site-specific erosion control strategies and contribute to the improvement of process-based soil erosion models at the hillslope scale in Mollisol regions of Northeast China.
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