黄土丘陵区典型植被群落坡面土壤优先流特征及其影响因素

以黄土丘陵区3种典型植被群落(白羊草、铁杆蒿和杠柳)为研究对象,并以退耕1年的撂荒地作为对照(CK),采用原位染色示踪和实验室分析相结合,对比分析不同植被群落斑块格局下的土壤优先流特征,探究植物根系、土壤理化性质对优先流的影响。结果表明:相较CK,植被恢复提高了优先流发育程度;对于各植被斑块,铁杆蒿植被斑块具有最高的染色面积比(45.62%)、最大染色深度(30.30 cm)、优先流比(39.76%)和长度指数(475.90%),杠柳次之,白羊草最小;而对于同一植被群落,除白羊草群落外,其他群落优先流发育程度表现为植被斑块大于裸地斑块;通过结构方程模型发现,优先流染色面积比主要受到土壤总孔隙度、团聚体稳定性、根系生物量密度和有机质含量的直接影响,解释方差可达70%。因此,植被的自然恢复通过其根系发育影响土壤性质,进而改善土壤优先流发育程度,提高土壤入渗能力。

Characteristics and Influencing Factors of Soil Preferential Flow on Slope of Typical Vegetation Communities in Loess Hilly Region

Taking three typical vegetation communities (Bothriochloa ischaemum, Artemisia gmelinii and Periploca sepium) in the loess hilly region as research objects, and the abandoned land for one year as the control (CK), the characteristics of soil preferential flow under different vegetation community patch patterns were analyzed based on in-situ dye-tracer and laboratory experiment methods, and the effects of plant roots and soil physicochemical properties on preferential flow were explored. The results showed that vegetation restoration improved the development of preferential flow in comparison with the CK. For each vegetation patch, the highest dye coverage (45.62%), maximum staining depth (30.30 cm), preferential flow proportion (39.76%) and the length index (475.90%) were found in A. gmelinii vegetation patch, followed by P. sepium and B. ischaemum. For the same vegetation community, the development degree of preferential flow was higher in vegetation patches than that in bare patches, except for the B. ischaemum community. Furthermore, the structural equation model indicated that the dyeing area ratio of preferential flow was directly affected by soil total porosity, aggregate stability, root mass density and soil organic matter content, and which could explain 70% of the total variance. Therefore, the natural vegetation restoration could affect soil properties through roots development, thereby improving the development degree of soil preferential flow and soil infiltration capacity.