【目的】根系表皮的形态特征直接影响根系的抗拉拔特性,决定着根土界面摩擦力的大小,明确根皮形态对拉拔摩擦力的影响,有助于深入理解根系固土机制。【方法】以常见护坡灌木火棘(Pyracantha fortuneana)与紫穗槐(Amorpha fruticosa)为研究对象,用单根拉拔试验测定根土界面的摩擦力;采用分形维数(D)及轮廓算术平均偏差(Ra)刻画根系表皮特征,分析根系表皮特征对拉拔摩擦力的影响。【结果】火棘根系的拉拔摩擦力显著大于紫穗槐,火棘拉拔摩擦力增幅随径级增加而增大,而紫穗槐根系拉拔摩擦力增幅与径级无显著相关性,当径级为(3,4] mm时,拉拔摩擦力增幅最高。微观形态观察可知:火棘根皮轮廓起伏较大,紫穗槐根皮较为平整;形态参数Ra与D能很好地刻画植株的表皮特征,火棘根皮形态为裂隙形,以Ra表征效果最佳,其中Ra与拉拔摩擦力呈极强正相关,Ra越大,拉拔摩擦力越大。紫穗槐根皮为锯齿形,以D表征效果最佳,其中拉拔摩擦力增量与D呈极强正相关,D越大,拉拔摩擦力增量也越大。两植株拉拔过程存在区别,火棘为颗粒嵌入式摩擦,紫穗槐为根土界面接触摩擦,根皮内嵌入的土壤颗粒能在摩擦过程提供更大的摩擦阻力。【结论】本研究揭示了两种植物根表皮特征对根系拉拔摩擦的影响,为进一步了解根系微观特征对固土和摩擦机理作用提供依据。

【Objective】The epidermal morphology of plant roots critically determines their anti-pullout performance through root-soil interface friction modulation. Elucidating how root bark topography influences pullout resistance is fundamental for understanding vegetation-mediated slope stabilization mechanisms.【Method】Using Pyracantha fortuneana and Amorpha fruticosa as model slope-protection shrubs, we conducted single-root pullout tests to quantify frictional resistance. Fractal dimension (D) and contour arithmetic mean roughness (Ra) parameters were utilized to characterize root epidermis morphology, with subsequent correlation analysis between these descriptors and pulling resistance.【Result】P. fortuneana demonstrated significantly higher pullout resistance than A. fruticosa. The pulling resistance of P. fortuneana increased progressively with root diameter, whereas A. fruticosa exhibited no significant correlation between pulling resistance increment and root diameter, except for the highest resistance increase observed within the (3,4] mm diameter range. Microscopic analysis revealed distinct root bark morphologies: P. fortuneana displayed prominent undulating contours, while A. fruticosa maintained a relatively smooth surface. The morphological parameters Ra and D effectively characterized epidermal features. For P. fortuneana, fissured root bark morphology was optimally quantified by Ra values, which showed a strong positive correlation with pullout resistance—higher Ra values corresponded to greater resistance. In contrast, A. fruticosa’s serrated root bark morphology was best described by D values, with pullout resistance increment demonstrating a strong positive correlation with increasing D. Mechanistic divergence was evident: P. fortuneana generated resistance through a particle-embedded friction mechanism, while A. fruticosa relied on direct root-soil interface contact. The interlocked soil particles within P. fortuneana’s root bark contributed substantially to enhanced frictional resistance during pullout processes.【Conclusion】This study establishes quantitative relationships between root epidermal morphology and pullout resistance mechanisms, providing critical insights for optimizing slope-protection species selection based on root-surface architectural features.