Background In order to explore the suitable vegetation types for improving the soil quality of open-pit abandoned land, four forest-grass composite types of Cynodon dactylon (G), Ziziphus jujuba + C. dactylon (SG), Z. jujuba + Vitex negundo + C. dactylon (SJG), and Ailanthus altissima + Ulmus pumila + Z. jujuba + C. dactylon (CYSG) were used as the dominant plants in Jinshan mining area of Dongping county, Tai′an city.

Methods Based on the 4 typical shrub-grass communities with the bare land in the same section as a control, and 3 soil samples of 0-20 cm soil layer using 5-point method were collected in eachplot. Physical parameters such as soil bulk, porosity, moisture content and soil nutrient indexes such as organic carbon, available nitrogen, total phosphorus and total potassium were determined. Correlation analysis was conducted to explore the interaction among soil factors in different vegetation type. Principal component analysis was conducted and fuzzy mathematical affiliation function method was used to evaluate the potential effects of different vegetation types on soil improvement.

Results 1) Vegetation cover significantly improveed soil quality, and different vegetation types had different effects on soil quality. 2) Vegetation coverage significantly improved the soil physicochemical properties and increased the soil porosity and moisture content in the abandoned land of the open pit mine, with the highest soil saturated water-holding capacity was measured in the SJG model, which was 65.99% higher compared to the bare land. 3) Soil organic carbon, total phosphorus, available phosphorus, total potassium, available potassium and available nitrogen content significantly increased. Soil organic carbon and available nitrogen increased by 546.22% and 652.97%, respectively, in the SJG model compared to bare ground. Soil total phosphorus and available phosphorus content increased by 140.95% and 493.44%, respectively, in the CYSG model compared to bare ground. Soil total potassium and available potassium content were the highest in SJG model and CYSG model.

Conclusions The mixed forest-grass model was better than the bare ground and single vegetation restoration model in improving the soil moisture and physical and soil nutrients of abandoned mine land. The comprehensive improvement effect of different vegetation types on the abandoned land of open pit mine in Jinshan mine area of Dongping County was SJG>CYSG>SG>G.