Effects of land reclamation on soil bacterial community assembly and carbon sequestration function in coal mine subsidence area: taking Dongtan Mining Area as an example

Abstract

Although the reclamation activity could effectively promote the ecological service function of mining areas, the microbiological mechanism of functional reconstruction of reclaimed soil is still unclear. Clarifying how reclamation affects the characteristics, assembly mechanisms, and carbon sequestration functions of soil bacterial communities, is crucial for reshaping the ecological self-sustaining capacity of mining areas. To shed light on this purpose, combined with zero model analysis, MiSeq high-throughput sequencing and qPCR SmartChip technologies were used to explore the assembly processes and carbon sequestration functional variations of soil bacterial community in Dongtan mine area at four reclamation years (reclaimed 9 a, 12 a, 15 a, and 18 a). The results showed that: ① Reclamation activity and time presented significant impacts on soil physicochemical properties and enzyme activities. Soil pH, ammonium nitrogen (AN), catalase (CAT), and alkaline phosphatase (PO) showed the significant increasing trends with the incremental reclamation time (P<0.05), whereas organic carbon (SOC), available phosphorus (AP), nitrate nitrogen (NN), urease (UE), β-glucosidase (BG) and protease (PRO) appeared the opposite tendency (P < 0.05). ② The stochastic process dominated the assembly process of reclaimed soil bacterial communities, with the diffusion limitation contributing the most. ③ Organic carbon, nitrate nitrogen, ammonium nitrogen, available phosphorus, β-glucosidase and catalase were significantly correlated with the abundances of carbon cycle functional genes. Reclamation activities have enhanced the carbon sequestration function through ameliorating the soil physicochemical properties. ④ According to the result equation model, the increase in reclamation years directly affects the physical and chemical properties of the soil, which in turn indirectly affects the assembly process of soil microbial communities, which may be the main reason for changes in the abundance of carbon cycling functional genes. The research results could provide theoretical basis for improving the reclaimed soil productivity and elevating carbon sequestration functions in mining areas.

Keywords

• ecological restoration in mining area
• eastern mining area
• land reclamation
• soil microorganism
• carbon sequestration gene