Objective To study the soil infiltration characteristics of four Caragana korshinskii forests in the loess hilly area of Inner Mongolia for providing a reference for reasonable local forest planting and vegetation restoration and construction.

Method The cutting ring knife was used for sampling and analyzing soil physical and chemical properties in Caragana korshinskii and Populus davidiana × Caragana korshinskii, Armeniaca sibirica × Caragana korshinskii, Pinus tabuliformis × Caragana korshinskii forests. The single ring soil column method was used to observe the undisturbed soil water infiltration, and the correlation between infiltration characteristics and soil physical and chemical properties was analyzed.

ResultsThe initial infiltration rate, steady infiltration rate, 5 h cumulative infiltration amount, and the rate of wetting front of the four forests were the largest in A. sibirica × C. korshinskii forest (8.60 mm · min⁻¹, 1.05 mm · min⁻¹, 279.83 mm, 2.5 mm · min⁻¹), followed by P. davidiana × C. korshinskii (5.6 mm · min⁻¹, 0.76 mm · min⁻¹, 255.65 mm, 2.2 mm · min⁻¹), P. tabuliformis × C. korshinskii (4.80 mm · min⁻¹, 0.73 mm · min⁻¹, 243.03 mm, 2.0 mm · min⁻¹), C. korshinskii（3.16 mm·min⁻¹, 0.53 mm·min⁻¹, 178.64 mm, 3.4 mm·min⁻¹）. After infiltration, the soil saturated moisture content and field water holding capacity were shown as follows: A. sibirica × C. korshinskii > P. davidiana × C. korshinskii, P. tabuliformis × C. korshinskii > C. korshinskii. Soil bulk density and porosity were the main factors affecting the infiltration capacity and water status of the four woodlands.

Conclusion Comparing with other forests, A. sibirica × C. korshinskii has better regulation and water conservation function, and can effectively reduce surface runoff and soil erosion.