Effects of Taproot‐Type and Fibrous‐Root‐Type Grass Cover Structures on Runoff and Sediment Yield Processes on Slopes in the Loess Hilly and Gully Region

ABSTRACT Vegetation effects on slope runoff and sediment yield depend on plant types and vertical structures, yet underlying mechanisms remain insufficiently quantified. We conducted simulated rainfall experiments (60, 90, 120 mm h −1 ) on a taproot‐type grass ( Coronilla varia ) and a fibrous‐root‐type grass ( Juncus effusus ) to assess canopy and root contributions to runoff and soil loss control. The results indicated that both species significantly reduced erosion, with sediment reduction exceeding runoff reduction. The mechanisms by which the canopies and root systems of different vegetation types reduce runoff and sediment exhibited marked differences. Compared with bare slopes, C. varia and J. effusus reduced runoff by 18%–69% and sediment yield by 67%–100% under different treatments. Roots dominated the control effect, contributing 73%–92% for runoff and 55%–87% for sediment. J. effusus roots and canopy achieved mean runoff reduction effectiveness of 53% and 5%, markedly higher than C. varia (18% and 3%). In sediment reduction effectiveness, the root system of J. effusus excelled at 90 mm h −1 (83%), while C. varia performed better at 60 mm h −1 (54%). Although the overall sediment reduction effectiveness of C. varia was lower, its canopy exerted a stronger regulatory influence on sediment reduction under high rainfall intensity conditions. Both species decreased soil erodibility ( J. effusus 93%, C. varia 83%) and increased critical shear stress (216% and 153%). These results highlight the superior runoff and erosion control of fibrous‐root‐type species, though dense roots may pose slope‐failure risks under prolonged heavy rainfall. This study provides practical guidance for vegetation‐based slope stabilization and soil conservation in China's Loess Hilly and Gully Region.