Background Iron tailings have the characteristics of loose structure and poor water storage and fertilizer retention capacity, which seriously affect the growth and development of plants. At present, the study on vegetation configuration of iron tailings restoration is relatively simple, and there is a lack of evaluation of vegetation configuration on soil physical environment after mining area restoration. Therefore, it is essential to understand and evaluate the effect of vegetation configuration on soil physical property improvement in the ecological restoration process of iron tailings.

Methods We chose 14 iron tailings plots in the Zhangxuan mining area of Hebei province for vegetation investigation and soil sampling, analyzed the soil bulk density, porosity, water-holding capacity, and infiltration rate indexes. The weight was determined by the entropy weight method, and the TOPSIS method was applied to evaluate the effect of soil physical improvement under different vegetation types.

Results 1) Taking bare tailings as the control, the soil physical properties of iron tailings under different vegetation types were effectively improved by revegetation on the basis of soil preparation. The soil bulk density decreased by 1.50% - 27.84%, the total porosity increased by 13.50% - 63.28%, the capillary porosity increased by 32.93% - 82.87%, the saturated water-holding capacity increased by 26.83% - 131.68 %, and the field water-holding capacity increased by 40.40% - 230.51%. There were differences in soil physical properties under different vegetation types. 2)According to the results of entropy weight-TOPSIS Model, in the early stage of vegetation restoration, the shrub mixed of Amorpha fruticosa + Lespedeza bicolor had the best improvement effect on soil physical properties, and the overall performance was shrub mixed forest > arbor-shrub mixed forest > pure shrub forest > natural restoration herbs > arbor mixed forest ≈ pure arbor forest.

Conclusions It is suggested that the restoration of iron tailings should be based on engineering measures such as soil covering and local soil preparation, tree planting Pinus tabulaeformis, shrub planting A. fruticosa, L. bicolor, Hippophae rhamnoides mixed tree species and selection of Artemisia lavandulaefolia and other herbaceous plants. The results may provide theoretical basis for vegetation restoration measures and soil improvement of iron tailings.