Aims <p>Soil erosion resistance, a critical indicator for regional erosion risk assessment and soil loss prediction, is essential for maintaining agricultural ecosystem sustainability in alpine regions. Vegetation restoration mitigates erosion, but the temporal dynamics of restoration and its driving mechanisms on erosion resistance remain poorly quantified.</p> Methods <p>We investigated soil physical properties, root morphological traits, and the Comprehensive Soil Erosion Resistance Index (CSERI) in sown grasslands (<i>Poa pratensis</i>) across a chronosequence of stand ages (1, 2, 7, 8, and 12&#xa0;years).</p> Results <p>Our results revealed that root architectural traits and soil physical parameters exhibited nonlinear responses to stand age, with synergistic interactions enhancing erosion resistance and ecosystem resilience. Soil properties exerted stronger direct effects than root traits on CSERI which dominated by soil physical conditions rather than root architecture. Crucially, erosion resistance followed a stage-dependent trajectory, peaking at 7–8&#xa0;years due to optimal root-soil feedbacks.</p> Conclusions <p>A multilevel control structure emerged, with clay content as the dominant factor, bulk density as a mediator, and root traits exerting indirect effects. These findings provide mechanistic insights for optimizing erosion control strategies and timing adaptive management in alpine grasslands, supporting sustainable agroecosystem resilience in erosion-prone environments.</p>