黄土高原4种植被类型对土壤物理特征及渗透性的影响

以黄土高原丘陵沟壑区李家堡乡的荒草地、文冠果林地、沙棘林地和柠条灌丛为研究对象,采用野外采样与室内分析相结合的方法,研究了4种植被类型土壤的物理特征及其渗透特征。结果表明:随土层深度的增加,土壤容重大体呈增加趋势,而土壤各孔隙度和通气度呈下降趋势。4种植被类型中荒草地的土壤容重最大,孔隙度及通气度最小,而柠条灌丛的土壤容重最小,孔隙度及通气度最大。土壤水分物理特征值为柠条灌丛最大,文冠果林和沙棘林次之,荒草地最小;柠条灌丛0—40cm土层土壤最大持水量、毛管持水量、最小持水量、最大蓄水量、排水能力比荒草地分别高出了23.00%,22.51%,15.02%,12.76%,61.28%,且方差分析表明差异显著。4种植被类型的土壤水分入渗过程符合对数曲线,各土层土壤的渗透性系数R~2为0.937 9~0.986 9,且F检验均达到极显著水平(P0.001)。与荒草地相比,柠条灌丛的入渗速率和水源涵养功能显著高于荒草地,能更好地改变土壤物理特征,应该增加柠条灌丛林的营造。

Effects of Four Vegetation Types on Soil Physical Characteristics and Permeability in Loess Plateau

Taking the grassland, the Xanthoceras sorbifolia, the Hippophae rhamnoides and the Caragana korshinskii shrub in Lijiabao, the hilly-gully region in the Loess Plateau, as the research objects, the field sampling and the indoor analysis were used to study the soil physical characteristics and infiltration characteristics under four vegetation types. The results showed that with the increase of soil depth, soil bulk density increased generally, while soil porosity and aeration decreased. In the four vegetation types, the soil bulk density of grassland was the largest, with the smallest porosity and aeration, while the soil bulk density of Caragana korshinskii shrub soil was the smallest, with the highest porosity and aeration. The physical characteristics of soil water were the largest in Caragana korshinskii, the following was in Xanthoceras sorbifolia and Hippophae rhamnoides, and the lowest in grassland. The maximum water holding capacity, capillary holding capacity, minimum water holding capacity, maximum water storage capacity and drainage capacity of 0-40 cm soil layers in Caragana korshinskii shrub were 23.00%, 22.51%, 15.02%, 12.76% and 61.28% respectively higher than those in grassland, and the variance analysis showed significant difference. The logarithmic relationships were found for the soil moisture infiltration processed under the four vegetation types, the R² of soil permeability coefficient were between 0.937 9 and 0.986 9, and the F test reached the extremely significant level (P<0.001). The infiltration rate and water conservation capacity of Caragana korshinskii shrub were significantly higher than those of grassland, which could improve soil physical characteristics and increase the construction of Caragana korshinskii forest.