Objective  The effects of three land use patterns (urban green space, plain afforestation and plant nursery) on soil salinization were studied, so as to provide a scientific basis for rational selection of afforestation and afforestation types, effective genetic control of soil salinization and sustainable development of land use.

  Methods  In the spring of 2022, 54 urban green space, plain afforestation and plant nursery with common tree species were selected in Tongzhou District of Beijing, and 324 soil samples were collected from 0 ~ 20 cm and 20 ~ 40 cm soil layers, respectively. The total salt content, major anion content and composition, and alkalization index of soil in each soil layer were determined. The single factor analysis of variance, correlation analysis and Kriging interpolation method were used to analyze the soil saline-alkali characteristics under different land use patterns, and to explore the reasons for their formation.

  Results  The soil in the study area is generally alkaline, with a pH range of 8.39 ~ 8.53, suggesting a moderate or lower degree of salinization and alkalization. Different land use types resulted in changes in soil total salt content, ion composition, and distribution. The soil salt distribution in urban green space is "surface aggregation" and the overall salt content, Cl⁻, Na ⁺, Mg^{2 +} concentrations were much higher than that of plain afforestation and nursery. In the study area, the fluctuation coefficient of soil Na ⁺ was the highest, while that of Ca^{2 +} was the lowest. Except for Na ⁺ , the fluctuation coefficients of all ions in urban green space soil were higher than these in afforestation and nursery soil. The spatial distribution of soil total salt content and salinization degree in the 0 ~ 20 cm layer was largely consistent in terms of spatial distribution characteristics. The salinization degree was relatively high in the northern section of the research area and gradually declines from north to south.

  Conclusion  Land use types in the study area leaded to variation of soil salinization characteristics. Urban green soil was prone to secondary salinization, while afforestation and nursery management measures and litter return ratio in plain soil may reduce secondary salinization by changing soil salt content, composition and alkalinity degree.