[Soil Functional Genes of Carbon, Nitrogen, Phosphorus, and Sulfur Cycle at Different Restoration Stages of Ulmus pumila in Pingshuo Mining Area].

Open-pit coal mining has caused serious damage to the ecological environment, and vegetation restoration is a major management for ecological restoration in mining areas. The nutrient cycling mediated by soil microorganisms is closely related to the soil functional genes. Studying the effects of long-term vegetation restoration on soil carbon, nitrogen, phosphorus, and sulfur functional genes is of great significance for ecological restoration in mining areas. The reclamation of Ulmus pumila (UP) forest land in the Pingshuo open-pit coal mine was selected as the research object. Rhizosphere soil samples of UP with growth years of 5 a (UP5), 15 a (UP15), and 25 a (UP25) were collected to analyze the relationship between soil chemical properties and the abundance of carbon, nitrogen, phosphorus, and sulfur functional genes. The results showed that with the increase in restoration time, the nutrient content of the soil significantly increased (P < 0.05). The total abundance of functional genes related to the carbon, nitrogen, phosphorus, and sulfur cycles increased, and the nitrogen cycle was the main biochemical process in UP forest land. Among all carbon fixation genes, the acsA involved in the reducing acetyl CoA pathway had the highest abundance. The main biochemical process of the phosphorus cycle was organic phosphorus mineralization, and the sulfur oxidation process was stronger than the sulfur reduction process. When the growth period was 25 a, the diversity and stability of microbial functional genes were highest. Additionally, mutual promotion and cooperation among genes were the main mode of function genes activity. In the UP forest land, total carbon and available phosphorus were the primary factors for carbon cycling genes, while total carbon, total nitrogen, nitrate nitrogen, and available phosphorus were the primary factors for nitrogen cycling genes. The sulfur cycling genes were significantly positively correlated with soil chemical properties (P < 0.01). The results showed that the soil chemical properties, carbon, nitrogen, phosphorus, and sulfur functional genes diversity and stability in 25 a of UP were significantly higher than those in 5 a and 15 a, and soil quality has been improved. In a word, with the restoration time increasing, vegetation restoration impacted the abundance and diversity of functional genes by altering the soil chemical properties, ultimately promoting the restoration and stability of the ecosystem. These results are helpful to understand the influence of carbon, nitrogen, phosphorus, and sulfur-related functional genes in the process of vegetation restoration and to provide genetic scientific basis for ecological restoration in the mining areas.