黄土高寒区典型植被类型土壤入渗特征及其影响因素

为了研究黄土高寒区典型植被在不同坡位下土壤入渗性能差异及其影响因素,采用恒定水头法测定了不同植被类型的土壤入渗过程,并分析了土壤孔隙状况、机械组成、水稳性团聚体等与渗透速率的相关性。结果表明:(1)初渗速率和稳渗速率均表现为青海云杉祁连圆柏华北落叶松荒草地,且差异性显著;同一植被类型的土壤入渗速率沿坡面向下逐渐增大,但差异性不显著;(2)对不同植被类型的土壤入渗过程模拟发现Horton模型拟合效果最好,决定系数均在0.8以上,通用经验模型拟合精度较差,决定系数在0.614—0.982之间;(3)土壤入渗性能与孔隙状况、水稳性团聚体质量分数、有机质含量均有极显著相关性;0.25 mm团聚体质量分数是影响稳渗速率的主要决策因素;总孔隙度是影响初渗速率的最主要的决策因素,而毛管孔隙度是主要的限制因子。为高寒地区土壤入渗模拟以及植被配置等提供了科学依据。

Soil infiltration characteristics and its influencing factors of typical vegetation type in Loess Alpine region

In order to study the difference of soil infiltration performance and its influencing factors in different slopes of typical vegetation in Loess Alpine region, the infiltration process of different vegetation types was measured by constant head method. Soil porosity, soil particle-size distribution, organic matter and water-stable aggregates were also analyzed. The results showed that:(1) there were significant differences in infiltration rates among different vegetation types. The initial and stable infiltration rates changed in the order of Picea crassifolia > Sabina przewalskii > Larix principis-rupprechii > barren grassland. The soil infiltration rate increased with the increase of soil porosity, aggregate content and the decrease of bulk density along the slope. (2) The fitting effect of Horton was the best on different slope positions and vegetation types, and the general accuracy for the lower slope is better than that for the upper slope, while the general empirical model and Kostiakov model are poor in fitting effect. (3) Soil infiltration capability was significantly correlated with soil porosity, organic matter and water-stable aggregates, among which the main factors affecting the stable infiltration rate were bulk density, > 0.25 mm aggregate, and total porosity. The main factors affecting the initial permeability rate were > 0.25 mm aggregate, total porosity and capillary porosity. Path analysis shows that total porosity is the main decision variable affecting the initial infiltration rate, while capillary porosity is a limiting factor; >0.25 mm water-stable aggregate mass fraction is the main decision factor affecting the steady infiltration rate. This paper provides a scientific basis for soil infiltration simulation and vegetation allocation in Loess Alpine region.