为揭示春季风害发生期不同退化等级农田防护林下的风沙运动规律，以科尔沁沙地南缘35 a生樟子松农田防护林带（健康、轻度退化、中度退化、重度退化）为研究对象，旷野为对照（CK），监测3—5月防护林带迎风和背风方向4倍树高防护距离（-4 H~4 H）内距地表1 m、2 m高度的风速参数，结合土壤粒径分析，评估防风效能与土壤抗蚀机制。结果表明：（1） 健康农田防护林在-4 H~4 H范围内显著降低近地表风速，平均达49.63%±14.14%，背风向细沙粒（50~250 μm）较旷野下降12.22%~32.37%，粗沙粒（250~1000 μm）增加18.57%~42.83%，形成“细粒截留-粗化固表”双重防护；（2） 退化农田防护林防风效能随林带退化等级提升而衰减，在-4 H~4 H范围内中/重度退化农田防护林无有效防护距离，且重度退化农田防护林距地表2 m高度的防风稳定性优于1 m高度（ΔE_{2 m-1 m}=1.12 %），林冠层结构破碎对于近地表（≤1 m）防风效能的削弱更显著。（3） 中/重度退化农田防护林背风向粗化指数（粗/细沙粒比）较旷野分别下降0.71~0.94、0.89~1.09，全域风蚀强度高达5000 t·km^-2（剧烈等级）。综上所述，健康农田防护林通过多层次耗能抑制风蚀动力，中/重度退化农田防护林无有效防护距离、丧失抗蚀功能并诱发加速侵蚀。因此，建议优先修复中度退化农田防护林（枯死木比例11%~39%或缺带比例为30%~49%、风蚀模数>5000 t·km^-2），通过增加灌木层等方式修复近地表（≤1 m）林带结构，提高湍流控制能力，抑制细沙粒（50~250 μm）选择性流失。本研究为半干旱区退化农田防护林修复时序划定及风蚀防控提供了理论与技术支撑。

This study elucidates the dynamics of wind-blown sand movement across degradation gradients in farmland shelterbelts during spring wind hazards. Thirty-five-year-old Mongolian Scots pine (Pinus sylvestris var. mongolica) shelterbelts (healthy, slightly, moderately, and severely degraded) along the southern margin of Horqin Sandy Land were selected for the study, along with open areas as controls (CK). The wind speed parameters were monitored at 1 m and 2 m heights within a protective distance of -4 to 4 H (where H is the mean tree height) on the windward and leeward sides from March to May. The parameter values were combined with soil-particle size analysis to determine the windbreak efficiency and soil anti-erosion mechanisms. It was found that (1) healthy shelterbelts significantly reduced the near-surface wind speeds (mean reduction: 49.63%±14.14%) between -4 H and 4 H, decreased the leeward fine sand (50-250 μm) content by 12.22%-32.37% from that of CK, and increased the coarse sand (250-1000 μm) content by 18.57%-42.83% from that of CK, forming a dual protective “fine-particle interception and surface coarsening” mechanism. (2) The windbreak efficiency decreased with increasing degradation severity and the moderately and severely degraded shelterbelts provided no effective protective zone from -4 to 4 H. The wind stability of severely degraded belts was higher at 2 m height than at 1 m height (ΔE_2 m-1 m= 1.12%), with canopy fragmentation disproportionately impairing the near-surface (≤1 m) protection. (3) The coarsening indices (coarse/fine sand ratios) on the leeward side were 0.71-0.94 and 0.89-1.09 lower, respectively, in the moderately and severely degraded belts than in CK. The wind erosion intensity reached extreme levels (> 5000 t·km^-2) across all areas. In summary, healthy farmland shelterbelts suppress the wind erosion dynamics through multi-layer energy dissipation, whereas moderately/severely degraded shelterbelts lack an effective protective distance, lose their anti-erosion functionality, and trigger accelerated erosion. To reconstruct the near-surface (≤1 m) stand structure, we recommend the priority reconstruction of moderately degraded shelterbelts (deadwood ratio: 11%-39%; gap ratio: 30%-49%; wind erosion modulus >5000 t·km^-2) through structural optimization (e.g., by adding shrub layers). This approach will enhance the turbulence control capacity and inhibit the selective loss of fine sand particles (50-250 μm). This study provides theoretical and technical support for defining the restoration sequence of degraded farmland shelterbelts and controlling wind erosion in semiarid regions.