Metagenomic analysis reveals the effect of revegetation types on the function of soil microorganisms in carbon and nitrogen metabolism in the open-cast mining area

Vegetation type is one of the most important contributing factors to changes in soil properties during the rehabilitation of mining areas. However, there is still insufficient awareness regarding the relationship between soil properties and the function of soil microbes in C/N metabolism in different revegetation types.

Plots were established in seven revegetation types that were established more than 30 years ago in the Pingshuo opencast coal mine (RP, Robinia pseudoacacia; PS, Pinus sylvestris; PA, Picea asperata; PC, Populus simonii Carr; UP, Ulmus pumila; PT, Pinus tabuliformis; LG, Larix gmelinii). Soil properties and enzyme activity were determined, and a metagenomic approach was used to analyse the potential mechanisms of soil microorganisms involved in carbon and nitrogen metabolism.

Total N and soil organic carbon in PT, PS, and UP were significantly higher than those in the other revegetation types. The genes COG0477, COG2133, β-glucosidase (EC 3.2.1.21), and argininosuccinate lyase (EC 4.3.2.1) were prominently present in the soils of all revegetation types, with significantly higher prevalence in RP, PS, and PT. The modification of soil properties owing to revegetation type affects soil microorganisms, thus influencing the C/N metabolism functions of the soil ecosystem.

Soil bacteria and fungi play a significant role in maintaining the soil C/N metabolism. Therefore, the impact of revegetation types on the function of soil microorganisms in C/N metabolism must be considered when formulating ecological restoration strategies. Robinia pseudoacacia, Pinus tabuliformis, and Pinus sylvestris could be excellent species choices for facilitating ecological rehabilitation in mining areas.