Develop a Soil Quality Index to Study the Results of Black Locust on Soil Quality below Different Allocation Patterns

Mining areas are currently a typical ecosystem that is severely destroyed within the world. Over the years, mining activities have caused serious soil damage. Therefore, the soil restoration of abandoned mines has become a vital sustainable development strategy. The ecological environment within the hilly area of the Loess Plateau is extremely fragile, with serious soil erosion; Robinia pseudoacacia is the most popular tree species for land reclamation in mining areas within the Loess Plateau. To review the different various effects of Robinia pseudoacacia on soil quality below different configuration modes, this paper has chosen two sample plots within the southern dump of the Pingshuo mining area for comparison. The first plot is a Robinia pseudoacacia-Ulmus pumila-Ailanthus altissima broadleaf mixed forest, and the second plot is a locust tree broadleaf pure forest. The vegetation indicators and soil physical and chemical properties of the four stages in 1993, 2010, 2015, and 2020 were investigated. Principal component analysis is employed to develop the Soil Quality Index to perceive the changes within the Soil Quality Index over time. It is calculated that the Soil Quality Index of Plot I rose from 0.501 in 1993 to 0.538 in 2020, and Plot II rose from 0.501 to 0.529. The higher the SQI, the higher the reclamation of the mining area. It is found that Robinia pseudoacacia within the Robinia pseudoacacia-Ulmus pumila-Ailanthus altissima broadleaf mixed forest has higher soil quality improvement than the pure genus Robinia pseudoacacia broadleaf forest. This article can demonstrate the changes in the quality of reclaimed soil in the mining area, and can also provide a reference for the selection of reclaimed vegetation in other mining areas.