Gully erosion, considered as a type of intensive erosion, is the dominant source of sediment at small watershed scales in certain environments. Variation of vegetation may result in the changes in near soil surface characteristics, which likely further affect the resistance of gully systems to erosion. However, the potential effects of near soil surface characteristics of plant communities on resistance to erosion are still unclear in gully systems. This study was performed to investigate the variations in resistance of gully systems to erosion under different plant communities and to identify the dominant influencing factors leading to these variations on the Loess Plateau. Five typical plant communities (two grasses, two shrubs and one forest) that distributed on different gully systems were selected. Six hundred undisturbed soil samples collected from different sites of gully systems were subjected to detach by overland flow under six different shear stresses (6.66 to 15.02 Pa). The results showed that the mean soil detachment capacity of gully systems covered by grass and shrub communities was 0.15 and 0.37 times to that of gully system covered by forest. Compared to forest gully systems, rill erodibility reduced by 29.8% to 85.6% for the other four plant communities. The relative rill erodibility of different vegetation communities generally increased from grass to shrub and forest communities. The critical shear stress of forest gully system was 58.7% and 63.8% of gully systems covered by grass (6.22 Pa) and shrub (5.73 Pa) communities. Bulk density, soil cohesion, water stable aggregate, root mass density, and the thickness of biological soil crust were the dominant factors affecting the resistance of gully systems to soil erosion. Rill erodibility decreased logarithmically with increasing soil cohesion, water stable aggregate and root mass density. Critical shear stress increased with the increase of soil cohesion and root mass density as a power function, and linearly with the increase of water stable aggregate. These results show how vegetation can mitigate against the erosion induced by concentrated flow in relatively stable gully systems.

中文翻译：

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黄土高原不同植物群落下沟壑系统的土壤侵蚀抵抗力

沟渠侵蚀被认为是一种强烈侵蚀，是某些环境中小流域尺度沉积物的主要来源。植被的变化可能导致近土壤表面特征的变化，这可能进一步影响沟渠系统对侵蚀的抵抗力。然而，沟壑系统中植物群落近土壤表面特征对侵蚀抵抗力的潜在影响仍不清楚。本研究旨在调查不同植物群落下沟渠系统抗侵蚀能力的变化，并找出导致黄土高原这些变化的主导影响因素。选择分布在不同沟壑系统的5个典型植物群落（2种草、2种灌木和1种森林）。从沟壑系统不同地点收集的 600 个原状土壤样本在六种不同的剪切应力（6.66 至 15.02 Pa）下因地流而分离。结果表明，草丛和灌木群落覆盖的沟壑系统的平均土壤脱离能力分别是森林覆盖的沟壑系统的0.15和0.37倍。与森林沟壑系统相比，其他四种植物群落的细沟侵蚀性降低了29.8%至85.6%。不同植被群落的相对细沟侵蚀性一般从草丛到灌木和森林群落逐渐增加。森林沟壑系统的临界剪应力分别为草丛(6.22 Pa)和灌木(5.73 Pa)群落覆盖的沟壑系统的58.7%和63.8%。容重、土壤粘聚力、水稳团聚体、根系密度和生物土壤结皮厚度是影响沟壑系统抵抗土壤侵蚀的主导因素。随着土壤粘聚力、水稳定性团聚体和根质量密度的增加，细沟的侵蚀性呈对数下降。临界剪应力随土壤粘聚力和根质量密度的增加而增加，呈幂函数关系，并与水稳团聚体的增加呈线性关系。这些结果表明植被如何减轻相对稳定的沟壑系统中集中水流引起的侵蚀。