How Do Vegetation Patterns Control Gravity Erosion in Slope–Gully Systems Under Heavy Rainfall on the Loess Plateau of China?

ABSTRACT Understanding how vegetation patterns control gravity erosion, such as avalanches, landslides, and mudflows in slope–gully systems under heavy rainfall, remains a key challenge on the Loess Plateau of China. To address this issue, five 1‐h simulated rainfalls were conducted at an intensity of 1.4 mm/min on each experimental plot. The plot had a 3° gentle slope and a 70° gully sidewall, and the plot was covered with vegetation. The experimental results show that high‐coverage herbaceous vegetation on the gentle slope effectively reduced avalanche magnitude. The plot with 85% grass coverage had the lowest average avalanche volume at 109.6 cm 3 , across the five rainfall experiments. Conversely, the excessive restoration of woody vegetation, or planting woody vegetation near the gully shoulder line, markedly increased landslide scale. Across the five rainfalls, the average landslide volume was 1202.7 cm 3 in the plot with 85% tree coverage and 983.3 cm 3 in the plot with 60% shrub coverage along the gully shoulder line—both nearly triple that of bare land. Mudflow volumes in most of the plots accounted for less than 10% of the total gravity erosion. Avalanche and landslide volumes were significantly correlated with root mass density, silt content, bulk density, and organic matter content, with all correlation coefficients exceeding 0.45. In addition, gravity erosion intensified the water erosion. The volumes of the two erosion processes had correlation coefficients of 0.95 and 0.98 for the bare land and shrubland plots, respectively. Consequently, implementing high‐coverage herbaceous vegetation on gentle slope is one of the most effective strategies for mitigating gravity erosion on gully sidewall.