Abstract:
Background The loess hill is known for its fragile ecological environment and severe soil erosion. Vegetation restoration has been widely adopted as a strategy to enhance soil stability and hydraulic properties. The objective of this study is to reveal the effects of different vegetation on the stability of soil aggregates and hydraulic properties in the slop region of Loess hilly area, and to explore the appropriate vegetation patterns.
Methods The wet and dry sieving method was used to study the distribution and stability of soil aggregates. The Wilcox and the ring knife head determination method were applied to study water-holding capacity (Fc) and saturated water conductivity (Ks) of the soil in the field. The relationships between the stability of soil aggregates and soil hydraulic properties with different vegetation types were investigated.
Results The results showed that the destruction rate of soil aggregates under different vegetation was in the order of bare land > shrub > herb. The mean weight diameter (MWD) of soil water stability aggregates at 0−10 cm was shrub > herb > bare land. At depth of 10−30 cm, the shrub > bare land > herb. At the same depth, the Ks of shrub and herb soils were greater than those of bare soil. At 10−30 cm, the Ks of shrubs and herbs increased significantly (P < 0.05). At the same depth, Fc were all herb > shrub > bare land.
Conclusions In the section of loess hilly slope, shrub and herb vegetation played crucial roles in improving soil aggregate stability and hydraulic properties. Shrub and herb increased the content of soil water-stabilized aggregates at 0−20 cm, and reduced the rate of aggregate destruction. Herb vegetation was affected by the alternation of dry and wet, so the particle size of soil aggregates decreased. With the increase of the Fc and the decrease of the MWD, shrub increased the Fc and MWD in the soil, which improved water conservation, preventing soil and water for long-term from leaching and losing.
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