Assessment of Artificial Forest Restoration by Exploring the Microbial Community Structure and Function in a Reclaimed Coal Gob Pile in a Loess Hilly Area of Shanxi, China

In this study, soil obtained from a reclaimed coal gob pile was expected to be rapidly improved with the use of artificial vegetation restoration practices, such as artificial forests, which increase the taxonomic variety in the soil microbial community and its functions. In order to successfully identify the effect of artificial forest restoration project on the soil’s quality, a field study was conducted on soil reclaimed from a coal gob pile in a loess hilly area located in Shanxi to assess the effects of five commonly used artificially restored coniferous forest species (i.e., Platycladus orientalis: PO, Sabina chinensis: SC, Pinus sylvestris: PS, Picea asperata: PA and Pinus tabuliformis: PT) on the soil’s physico-chemical properties, the bacterial community and functional gene attributes. The results showed that significant differences were observed in the bacterial community’s diversity and structure, as well as in functional genes, among the different artificial tree species. PS and PA presented lower pH and bulk density levels and higher soil alkaline protease (PRO), alkaline phosphatase (ALP) and urease (URE) activities, in comparison to other tree species. The bacterial community’s diversity and functional genes were noticeably higher in both PS and PA. In addition, soil bulk density and pH can directly affect the soil keystone bacteria and microbial functions and can indirectly affect the soil keystone genus and microbial functions by affecting the soil nutrient elements and enzyme activity. Moreover, soil bacterial keystone bacteria significantly affect these functions. Finally, compared to the other coniferous tree species, PS and PA presented a significantly higher integrated fertility index (IFI) score. Therefore, PS and PA might be more suited to the forest restoration project using reclaimed soil obtained from a coal gob pile located in Shanxi’s mining region. The present research contributes to the understanding of how various tree species affect microbial populations and functions in similar mining zones and/or hilly terrains.