国家自然科学基金项目(42067005).云南省农业联合专项面上项目（202101BD070001-075）.云南省基础研究计划面上项目（202001AT070136）.云南省青年人才专项（ YNWR - QNBJ -2019-215；YNWR-QNBJ-2019-226）.云南省自然生态监测网络项目(2022-YN-13)
Southwest Forestry University
National Science Fund Projects（42067005）. Agricultural Joint Special Project in Yunnan Province（202101BD070001-075）. Basic Research Project of Yunnan Province（202001AT070136）. Yunnan Young Talents Project（YNWR-QNBJ-2019-215；YNWR-QNBJ-2019-226）. Yunnan Natural Ecological Monitoring Network Project(2022-YN-13)
[目的]为探究金沙江干热河谷冲沟系统土壤团聚体结构对优先路径形成的影响，深化对冲沟系统土壤水分和溶质运移的认识。[方法]选取金沙江干热河谷活跃和稳定冲沟不同部位（集水区、沟头、沟床和沟底）为研究对象，基于染色示踪和形态学图像解析技术，提取土壤水平剖面优先路径。采用RDA、灰色关联和耦合协调度等分析方法探究土壤团聚体结构与优先路径的关系。[结果]（1）稳定冲沟土壤团聚体稳定性高于活跃冲沟。除个别土层外，活跃冲沟>0.25 mm机械稳定性团聚体（DR0.25）、水稳定性团聚体（WR0.25）、平均质量直径（MWD）含量均显著小于稳定冲沟（p<0.05），团聚体破坏率（PAD）和不稳定团粒指数（ELT）则呈相反趋势。冲沟系统由集水区向沟底延伸，土壤大团聚体占比减少，团聚体稳定性下降。（2）活跃冲沟优先路径数量和连通性优于稳定冲沟，冲沟系统由集水区向沟底延伸优先路径连通性变差。各部位以>10 mm优先路径为主要通道。活跃冲沟Simpson指数较稳定冲沟增加了3.12%，不同径级的优先路径丰富度高于稳定冲沟。（3）优先路径的形成和分布受土壤团聚体稳定性的影响， MWD和WR0.25与优先路径数量达到极强关联且影响最为显著（p<0.01）。（4）冲沟系统由集水区向沟底延伸，土壤团聚体结构与优先路径的耦合协调性降低。整体上表现为：沟头>集水区>沟底>沟床。 [结论]土壤团聚体结构是优先路径形成的重要驱动因素之一，优先路径的分布对干热河谷冲沟系统发育具有重要影响。
[Objective] To investigate the impact of soil aggregate structure on the formation of preferential pathways in the gully system of the dry-hot valley of the Jinsha River and enhance our understanding of soil moisture and solute transport in the gully system. [Method] We selected different sections (catchment area, gully head, gully bed, and gully bottom) of both active and stable gullies in the dry-hot valley of the Jinsha River as our research subjects. We used staining tracers and morphological image analysis techniques to extract the preferential pathways of the soil level profile. Moreover, we employed RDA, gray correlation, and coupled coordination analysis to explore the relationship between soil aggregate structure and preferential pathways. [Result] (1) Soil aggregates in stable gullies were more stable than those in active gullies. Except for specific soil layers, the contents of mechanically stable aggregates (>0.25 mm, DR0.25) and water-stable aggregates (>0.25 mm, WR0.25) and average mass diameter (MWD) in the four parts of the active gully were significantly lower than those in the stable gully (p < 0.05). The aggregate destruction rate (PAD) and unstable aggregate index (ELT) showed the opposite trend. As the gully system extends from the catchment to the bottom of the gully, the fraction of large soil, and the stability of aggregates all decreased. (2) The number and connectivity of preferential pathways in active gullies exceeded those in stable gullies. However, the connectivity of the preferential pathways in the gully system deteriorated as it extended from the catchment to the bottom of the gully. The preferential pathways with a diameter >10 mm served as the primary channel. The Simpson index of active gullies exhibited an increase of 3.12% compared to stable gullies, indicating a higher richness of preferential pathways across different diameter classes. (3) The stability of soil aggregates affected the formation and distribution of preferential pathways. Remarkably, there is a strong correlation between soil aggregate structure and the number of preferential pathways, with MWD and WR0.25 of showing the most substantial effect on the number of preferential pathways （p < 0.01）. (4) As the gully system extended from the catchment to the bottom of the gully, the coupling coordination between the soil aggregate structure and the preferential pathways decreased. Overall, the order of performance was as follows: gully head > catchment area > gully bottom > gully bed. [Conclusion] Soil aggregate structure is one of the important driving factors for the formation of preferential paths, and the distribution of preferential paths has a significant impact on the development of gully systems in dry-hot valleys.