Effects of soil compactness and litter covering on soil water holding capacity and water infiltration ability in urban forest

  Objective  This study analyzed the effects of human interference on physical properties such as soil bulk density, porosity, and compactness, and revealed that soil compactness and litter covering determined the soil water holding capacity and water infiltration ability in urban forest, so as to provide reference for scientific management of urban forest litter and trampling intensity.

  Method  Taking forest in the Olympic Forest Park, a typical urban forest park in Beijing, as the research object, we measured the properties of water holding and infiltration in the surface soil layer under human disturbance in terms of different trampling intensities (mild, moderate, severe) , different litter accumulation (0−4 t/ha, 4−8 t/ha, 8−12 t/ha), different coverage of grass plants (0, 0−50%, 50%−100%). And the effects of soil compactness and litter covering on soil water holding capacity and water infiltration ability were analyzed.

  Result  (1) Different trampling intensities and litter accumulation had significant effects on soil water holding capacity (P < 0.05) and water infiltration ability, while grass coverage had no significant effect on both (P > 0.05). With the trampling intensity decreasing, soil aeration, water holding capacity, and infiltration capacity increased significantly. (2) Soil water holding capacity and soil infiltration rate were significantly positively correlated with soil porosity, and significantly negatively correlated with soil bulk density. It indicated that human disturbance affected the water holding and infiltration capacity by changing the degree of soil aeration and compactness. (3) With the increase of soil compactness, water holding capacity and water infiltration ability of urban forest soil decreased significantly; while with the increase of litter accumulation, soil water holding capacity and water infiltration ability changed not obviously. (4) Soil water holding capacity increased with soil compactness decreasing and litter accumulation increasing, both of which had a synergistic effect; soil water infiltration capacity increased with soil compactness decreasing, while litter covering had little effect on it.

  Conclusion  Soil compactness and litter covering determine the soil water holding capacity and water infiltration ability of urban forest soil. Reducing human trampling intensity and proper retention of litter can improve soil water holding capacity and water infiltration ability in urban forest, and then reduce surface runoff.