Study on the Soil Water Characteristics of R. pseudoacacia and P.orientalis in the West of Beijing

In order to understand the improvement of the soil under the different species plantations and to explore the different types of soil moisture conditions in Xishan area of Beijing,original soil samples were taken under R.pseudoacacia and Platycladus.Soil water characteristic curve was measured by using centrifuge dewatering experiment.Related parameters were obtained by fitting the curve,then soil moisture conditions were analyzed in the R.pseudoacacia forest and P.orientalis forest.Results showed that the soil texture of this area was coarse and plant utilization of water was really difficulty.Generally,the soil in P.orientalis plantation was more sufficient than the R.pseudoacacia in terms of water retention.And each plant species had different improving effect,and water retention of the upper soil was better than that the lower soil layer.In the R.pseudoacacia forest,the upper soil was stronger than the lower soil in terms of water retention.While in the P.orientalis forest,the upper soil was weaker than the lower in terms of water retention.With regard to soil water supply capacity,R.pseudoacacia was intenser than P.orientalis,and the topsoil was intenser than the subsoil under the same site conditions.Both in the R.pseudoacacia and P.orientalis forest,the boundary point of suction for readily available water and resistantly available water was 0.3 MPa.