A short period of revegetation and fertilization increased the nutrients, enzyme activities, and bacterial community diversity in backfill soils

Abstract

The ecosystem stability of abandoned mines can be restored using vegetation restoration methods. In the present study, we aimed to investigate the variations in the physicochemical and biochemical properties of backfill soils at a quarry mining slope platform with a 1-year period of revegetation and fertilization in Anhui Province, East China. We collected backfill and native soils in different periods and analyzed their nutrients, enzyme activities, and bacterial communities. Two fertilization cycles increased the nutrients in revegetation backfill soils significantly (p < 0.05), including the available nitrogen (AN) (47.35 ± 9.40 mg/kg vs 134.23 ± 42.37 mg/kg), total phosphorus (TP) (0.38 ± 0.06 g/kg vs 0.78 ± 0.04 g/kg), available phosphorus (AP) (3.99 ± 0.84 mg/kg vs 17.23 ± 7.86 mg/kg), total potassium (TK) (14.33 ± 1.16 g/kg vs 30.74 ± 3.50 g/kg), available potassium (AK) (56.77 ± 7.33 mg/kg vs 339.26 ± 95.67 mg/kg), and soil organic matter (SOM) (13.13 ± 6.12 g/kg vs 19.60 ± 1.06 g/kg); however, the TN and SOM in revegetation and fertilization backfill soils were still much lower than those in native soils. Compared to the initial backfill soils with no revegetation, the activities of sucrase (SUC) and urease (URE) in revegetation and fertilization backfill soils increased from 2.79 ± 0.55 mg/(g·d) to 6.17 ± 3.19 mg/(g·d) and 0.12 ± 0.02 mg/(g·d) to 0.16 ± 0.02 mg/(g·d), respectively; however, they were still much lower than those in native soils. The bacterial community in backfill soils was stable during revegetation and fertilization, similar to that in native soils, with the dominant phyla being Actinobacteria, Proteobacteria, Chloroflexi, and Acidobacteria. The relative abundance of Proteobacteria in backfill soils decreased from 46.12 % to 22.94 % during revegetation and fertilization, whereas those of Actinobacteria, Chloroflexi, and Acidobacteria increased from 22.2 % to 45.14 %, from 6.24 % to 15.18 %, and from 4.76 % to 24.12 %, respectively. Revegetation and fertilization improved the evenness (Simpsoneven index) and diversity (Shannon index) of bacterial community in backfill soils. The bacterial community structure in backfill soils during revegetation and fertilization approached that of the native soils. The results of redundancy analysis indicated that the bacterial communities in revegetation and fertilization backfill soils were influenced by AK, AN, SOM, URE, and SUC, whereas those in native soils were influenced by TN, SOM, and SUC. Our study indicated that only a short period of revegetation and fertilization improved physicochemical properties and enzyme activities and stabilized the structure of the bacterial community in backfill soils.