应用Le Bissonnais法研究黄土丘陵区不同植被区及坡向对土壤团聚体稳定性和可蚀性的影响

论文通过Le Bissonnais法对黄土丘陵区森林、森林草原和草原三种植被区下的土壤团聚体分布特征、稳定性以及土壤可蚀性进行了分析研究。研究结果表明:1)在不同植被区表层土壤(0~20 cm)中,土壤的水稳性团聚体含量(R0.2)和平均重量直径(MWD)整体上表现为阳坡小于阴坡,土壤可蚀性因子K值则表现为阳坡大于阴坡,但是阴、阳坡差异均不显著;2)表层土壤的R0.2、MWD均表现为森林区森林草原区草原区,可蚀性因子K值则表现为草原区森林草原区森林区,土壤团聚体稳定性和抗侵蚀能力由高到低依次为森林区、森林草原区和草原区;3)扰动后湿润处理(WS)和快速湿润处理(FW)下的森林区与草原区土壤的稳定性和可蚀性指标差异显著,FW处理下二者差异尤为显著,而森林草原区土壤则居于前面两种土壤之间。总体来说,在黄土丘陵地带,植被区从北向南,由草原区向森林区变化过程中,土壤团聚体的稳定性和抗侵蚀性在不断提高,南部森林区的土壤团聚体稳定性比北部草原区更强,抗侵蚀能力更大。

Research on the Effect of Vegetation and Slope Aspect on the Stability and Erodibility of Soil Aggregate in Loess Hilly Region Based on Le Bissonnais Method

In this article, the distribution characteristics, stability and erodibility of soil aggregate in three zones of forest, forest-steppe and steppe on the Loess Plateau are studied with the Le Bissonnais (LB) method. The effect of vegetation and slope aspect on the characteristics and erodibility of soil aggregate is also discussed. The results show that: 1) for the surface soil (0-20 cm) in different vegetation zones, both the content of soil aggregate (R0.2) and the mean weight diameter (MWD) are less on sunny slopes than on shady slopes, while the soil erodibility factor K is a little bigger on sunny slopes than on shady slopes with no significance. This implies that both the stability and erodibility of soil aggregate are slightly higher on the shady slope than on the sunny slope in the three vegetation zones in hilly loess region, but the differences are not significant. 2) In the surface layer (0-20 cm) under different vegetation, R0.2 and MWD decrease as follows: forest > forest steppe > steppe, while soil erodibility factor K decreases in the following order: steppe> forest-steppe > forest. This suggests that the stability and anti-erosion ability of soil aggregate in the forest vegetation zone is the highest. 3) Under processes of WS (wet-stirring sieving method) and FW (fast-wetting sieving method), there are significant difference between samples in forest zone and in steppe zone in both the soil stability and the soil erodibility (R0.2, MWD, K value), especially under the process of FW. The stability and erodibility of soil in forest-steppe zone are in between. A conclusion can be drawn that in the hilly loess zone, the stability and the anti-erosion ability of soil aggregate is ever increasing from north to south. The stability and the anti-erosion ability of soil aggregate is significantly higher in the southern forest zone than in the northern steppe zone.