Vegetation restoration in loess hilly areas effectively controls soil erosion. However, the impact mechanisms of vegetation canopy, litter, and roots on soil erosion under complex rainfall regimes remain uncertain. The typical sub‐shrub species (Artemisia sacrorum) set up four treatments (natural condition, NC; canopy + roots, CR; roots only, OR; and bare soil, BS) in 2015–2017. K value clustering analysis was used to classify three rainfall regimes: Regime‐I (short duration, small amount and medium intensity), Regime‐II (medium duration, amount and high intensity), and Regime‐III (long duration, large amount and low intensity). The results showed that the average runoff, soil loss and sediment concentration followed the order: BS treatment > OR treatment > CR treatment > NC treatment. The canopy accounted for more than 60% of the total contribution to soil loss and sediment concentration reduction. The litter had the lowest relative contribution to both runoff and soil loss reduction (29.76% and 4.19%, respectively). Roots accounted for the most contribution of 37.27% to reduce runoff, and just contributed 28.41% to reduce soil loss. Rainfall regimes significantly influenced the contribution of Artemisia sacrorum components to control soil erosion. Regime‐III showed the highest contribution of different treatments to runoff and soil loss reduction (51.5%–79.9% and 65.7%–99.1%, respectively), while the lowest contributions occurred in Regime‐II (14.4%–47.5%) and Regime‐I (6.89%–95.08%), respectively. The canopy accounted for the 180.02% of the total contribution to reduce soil loss in Regime‐II, but it instead had the minimum relative contribution of 6.81% in Regime‐III. The relative contribution of roots to runoff reduction reached 91.24% in Regime‐III, but just was 37.31% in Regime‐II. The litter and roots even had negatively relative contribution in Regime‐II or Regime‐III. Besides, contributions of canopy and roots showed increase and decrease responses to increasing I30, respectively, while the litter contribution only negatively related to rainfall duration. These findings indicated that the canopy was the most critical factor in controlling soil erosion, while the litter played the lowest function, and the roots had continuous effects. The functions of plant components would change with different regimes, which maybe not always beneficial for reducing soil erosion. This study provides new insights into the rainfall‐vegetation‐erosion relationship.

中文翻译：

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复杂降雨条件下植被冠层、凋落物和根系对土壤侵蚀的影响——以黄土丘陵区骶蒿为例


黄土丘陵地区的植被恢复可有效控制水土流失。然而，在复杂降雨条件下，植被冠层、凋落物和根系对土壤侵蚀的影响机制仍不确定。典型的亚灌木物种 （Artemisia sacrorum） 在 2015-2017 年建立了四种处理（自然条件，NC;树冠 + 根，CR;仅根，OR;裸土，BS）。K 值聚类分析用于对三种降雨状况进行分类：方案 I （短持续时间、小量和中等强度）、方案 II （中等持续时间、量和高强度）和方案 III （长持续时间、大量和低强度）。结果表明，平均径流、土壤流失和泥沙浓度依次为：BS 处理 > 或 > CR 处理 > NC 处理。冠层占土壤流失和沉积物浓度降低总贡献的 60% 以上。凋落物对减少径流和土壤流失的相对贡献最低（分别为 29.76% 和 4.19%）。根系对减少径流的贡献最大，为 37.27%，对减少土壤流失的贡献仅为 28.41%。降雨条件显著影响了蒿属成分对控制土壤侵蚀的贡献。方案 III 显示不同处理对减少径流和土壤流失的贡献最大 （分别为 51.5%–79.9% 和 65.7%–99.1%），而方案 II （14.4%–47.5%） 和方案 I （6.89%–95.08%） 的贡献最低。在方案 II 中，冠层占减少土壤流失的总贡献的 180.02%，但在方案 III 中，它的相对贡献最低为 6.81%。根系对径流减少的相对贡献达到 91。在制度 III 中为 24%，但在制度 II 中仅为 37.31%。凋落物和根系甚至在 Regime-II 或 Regime-III 中具有负相对贡献。此外，冠层和根系的贡献分别表现出对 I30 增加和减少的响应，而凋落物贡献仅与降雨持续时间呈负相关。结果表明，冠层是控制水土流失的最关键因素，凋落物的作用最低，根系具有持续效应。植物成分的功能会随着不同的制度而变化，这可能并不总是有利于减少土壤侵蚀。本研究为降雨-植被-侵蚀关系提供了新的见解。