Effects of regenerated periods and vegetation modes on soil microbial functional diversity in regenerated land of opencast coal mine

Abstract: Understanding the effect of regenerated land conditions on soil microbes is essential for estimating the extent of ecological restoration. In this study, we employed the Biolog ECOTM method to evaluate the restoration effects of different regeneration periods and vegetation patterns on the soil microbial characteristics in restoration fields of the Antaibao opencast coal mine in Shanxi Province, China. The representative indicators describing soil microbial functional diversity were then screened from soil physicochemical properties (bulk density, pH value, soil organic carbon, total nitrogen, available nitrogen, available phosphorus, and available potassium), and biological properties (soil microbial biomass carbon and microbial biomass nitrogen). First, our results showed that both the land regeneration period and vegetation pattern markedly impacted the soil microbial functional diversity of this area. The soil microbial communities in the plots that were restored earlier have higher total activity and evenness. In the case of relatively long regeneration periods, the microbial functional diversity of restored land is mainly affected by the vegetation mode. Second, from the standpoint of the metabolic functional diversity of soil microbes, the best single-plant reclamation pattern was exhibited by Apricot (Armeniaca vulgaris Lam.), Elm (Ulmus pumila) and korshinsk peashrub (Caragana korshinskii); the optimized configuration sequence of mixed forest was korshinsk peashrub × locust (Robinia pseudoacacia). Third, the content of soil microbial biomass carbon was negatively correlated with microbial diversity indices of Shannon-Wiener index (ρ = -0.69, P < 0.01) and McIntosh index (ρ = -0.69, P < 0.05), and it may be used as a representative biodiversity indicator for the regenerated land to a certain extent. These findings contribute to improve the determination of reasonable regeneration approaches and support soil restoration in opencast coal mines.