黄土塬边坡植被类型对土壤孔隙的影响

黄土塬边坡植被建设以固坡为目的,不同植被的土壤孔隙结构有利于增加降水入渗,从而减少坡面产流的水蚀危害。本研究以长武塬黄土塬边坡的侧柏(Platycladus orientalis)林地、沙棘(Hippophae rhamnoides)灌丛、草地和农地4种植被为研究对象,采集0–30 cm的原状土柱,利用CT扫描和图像处理技术,对其土壤孔隙度、孔隙数目、孔隙成圆率和孔隙分形维数进行定量分析,结合土层样品的理化性质,研究影响土壤孔隙结构的主要因素。结果表明,农地、侧柏孔隙的孔径大小分异不大,而草地、沙棘自身根系互动穿插生成的根孔扩展了孔径分布范围,不仅增加了孔隙度和大孔隙数目,也降低了孔隙成圆率。草地、沙棘有利于降水入渗,是固坡的优先选择。土壤有机质、粘粒含量等性质与孔隙参数之间具有极显著(P<0.001)或显著(P<0.05)相关关系,它们的改变对土壤孔隙特征变化和提高蓄水保土能力具有重要影响。

The influence of Loess Tableland slope vegetation type on soil pore characteristics

Vegetation was planted on the Loess Tableland slope with the aim of solidifying the slope.The soil pore structure under the influence of vegetation can help increase rainfall infiltration and reduce water erosion hazards caused by slope runoff.In this project,four types of vegetation located on the Changwu Loess tableland slope were chosen as research objects.Undisturbed soil columns were collected from the 0–30 cm soil layer.Quantitative analysis of soil porosity,pore number,pore rounding rate,and pore fractal dimension was carried out using computerized tomography scanning and imageprocessing techniques.The main factors affecting the structure of the soil pores were analyzed in combination with the physicochemical properties of the soil layer samples.The results showed that pore size did not differ significantly between cropland and Platycladus orientalis vegetation types.Grassland and Hippophae rhamnoides roots increased porosity and pore number and reduced pore-rounding rates.Grassland and Hippophae rhamnoides vegetation types are therefore favorable for rainfall infiltration,making these the preferred choices for creating solid slopes.There was a significant(P<0.001)or(P<0.05)correlation among soil organic matter and clay content and pore parameters,and changes in these parameters had an important effect on soil pore characteristics.