宁夏荒漠草原不同林龄人工柠条林地土壤优先流研究

土壤优先流作为土壤中常见的水分流动方式，会造成土壤水分流失、地下水污染及坡面土体稳定性降低等问题。以位于宁夏盐池县的典型荒漠草原为研究区域，通过土壤水分入渗染色法、CT扫描法、图像处理技术相结合的分析方式，选取人工营造9、14、24、35年的柠条灌丛林地，以空白草地作为对照，探究不同恢复年限人工柠条林土壤优先流特征及其与土壤大孔隙与根系的关系。结果表明：(1)不同林龄柠条林地土壤优先流特征及大孔隙度具有显著差异，表现为随着种植年份的增加，土壤大孔隙度逐渐升高，土壤入渗染色深度随之加深，同时染色面积比随着柠条林林龄的增加而增大。(2)土壤基质流深度表现为随着种植年份的增加而增大，人工柠条林地的土壤优先流程度显著高于草地。(3)随着人工柠条林龄的增加，土壤根系数量增加，而灌丛生长发育过程中的根系活动使得灌丛林地土壤具有更多迂曲度低、连通性强的大孔隙，这些大孔隙是导致土壤水分优先迁移的主要因素。因此，植物根系和土壤大孔隙变化是影响荒漠草原人工柠条恢复过程中土壤水分分布的关键因素，合理配置人工林以改善根系及土壤结构特征，或可有效提高荒漠草原地区的土壤水分利用效率。

Study on preferential flow of soil of artificially planted caragana korshinskii shrubland in different years of desert grassland in Ningxia

Soil preferential flow is a common way of water flow in the soil, which causes soil water loss, groundwater pollution, and reduces slope soil stability. This paper takes a typical desert grassland as the research area in Yanchi County, Ningxia. And we selected artificially constructed shrubland (9, 14, 24, and 35 ages) as the research objects and used blank grassland as the control group, which explored the characteristics of soil preferential flow and its relationship with soil structure by soil water infiltration combining dyeing method, CT scanning method, and image processing technology. The results showed that:(1) there were significant differences in soil preferential flow characteristics and macroporosity. Soil macroporosity gradually and color depth of soil infiltration increased with the increase of planting years. Meanwhile, the ratio of dyeing area increased with the increase of Caragana korshinskii forest age. (2) The depth of soil matrix flow increased with the increase of vegetation planting years, and the soil priority degree of artificial Caragana korshinskii forest was significantly higher than that of grassland. (3) With the increase of the age of Caragana korshinskii plantation, the number of soil roots improved. The root activity in the process of shrub growth and development made the soil to have much lower tortuosity and stronger connectivity macropores, which were the main factors to lead to the preferential migration of soil water. Therefore, the changes of plant roots and soil macropores are the key factors to effect the soil water distribution in the process of artificial Caragana korshinskii restoration in desert steppe. The reasonable allocation of artificial forest plantation could improve soil water use efficiency in desert steppe effectively owing to its role in root system and soil structure characteristics modification.