Abstract: Long-term and large-scale Pinus tabuliformis pure plantations have many ecological problems. Choosing tree species with harmonious interspecific relationships is the key for successful stand conversion from pure forests to mixed forests. To provide scientific support for the rational configuration of tree species and sustainable forest management, we explored soil physical properties in different mixed stand types, including P. tabuliformis pure forests, P. tabuliformis and Quercus wutaishansea mixed forests, and P. tabuliformis and P. armandii mixed forests in South Shanxi. Results showed that (1) tree species mixture changed soil bulk density and soil porosity. The mixture ofP. tabuliformis and Q. wutaishansea significantly reduced soil bulk density and increased total soil porosity, capillary porosity, and non-capillary porosity, whereas such changes were negligible in the P. tabuliformis and P. armandii mixed forest. (2) Tree species mixture changed soil water retention characteristics. The maximum moisture capacity, capillary moisture capacity, and field water-holding capacity increased dramatically in the P. tabuliformis and Q. wutaishansea mixed forests, but not for P. tabuliformis and P. armandii mixed forests. (3) Tree species mixture had greater effects on physical properties of topsoil than deeper soil layer, including soil bulk density, porosity, and water holding characteristics. (4) Tree species mixture did not change the vertical patterns of soil properties. With increasing soil depth, soil bulk density increased, whereas total porosity, capillary porosity, non-capillary porosity, maximum moisture capacity, capillary moisture capacity, and field water-holding capacity reduced across different mixed forests.

Key words: Pinus tabuliformis, mixed forest, soil bulk density, soil porosity, soil water-holding capacity.