Study On The Properties And Ecological Stoichiometry Of Different Restoration Models In Abandoned Areas Of A Coal Mine

Coal mining has caused severe damage to local environments, such as ecological degeneration and accumulation of coal wastes, resulting in serious environmental pollution and huge emission of CO2. Ecological restoration in abandoned areas of coal mine are essential for improvement of environment in coal mine areas. Focus on the restoration vegetation in the Malan coal mine in Shanxi province, soil physical and chemical properties of different restoration models and stages were analyzed by plot survey and lab measurement. Moreover,the characteristics of ecological stoichiometry were also studied. This research aims to provide some references for restoration in coal mine areas. The results showed that:Through three restoration methods, including artificial restoration by planting staghorn sumac and oriental arborvitae, and natural restoration, soil properties were improved significantly. Soil organic carbon and organic carbon storage increased with forest age. Soil total nitrogen, available phosphorus and available potassium contents showed the same change trends, increasingsignificantly. Soil p H and soil bulk density decreased gradually, which was helpful for the growth of plants.Vertically, the soil organic carbon, total N, available P, and K concentrated on the top soil layer, and gradually reduced with the increase of soil depth.Through vegetation restoration, soil nutrient contents increased in the order:oriental arborvitae plantation > staghorn sumac plantation > naturally recovered vegetation. The oriental arborvitae plantation showed the optimum performance on the accumulation of soil nutrients, and it improved soil properties significantly.Correlation analysis showed that soil organic carbon was negatively correlated with p H value, while it was positively correlated with total nitrogen,available phosphorus, and available potassium. The reduction of p H value facilitated the growth of roots, which was beneficial to the accumulation of soil organic carbon. The increase of total nitrogen and available phosphorus was also helpful for the accumulation of soil organic carbon. Organic carbon storage was negatively correlated with p H value, and it was positively correlated with total nitrogen, available phosphorus, and available potassium.The analysis of ecological stoichiometry at different stages of the three restoration models showed that soil C/N ratio of different soil depths was similar.The soil C/P and N/P were significantly higher than the average value of Chinese soils, mainly due to the lack of phosphorus, which suggested that phosphorus was a limiting factor for ecological restoration.Mining activities and gangue-hills caused damages to soil properties, and speeded up the decomposition of soil organic carbon. Although the soil nutrients accumulated through the three restoration methods, the contents of soil total nitrogen, available phosphorus and potassium were still lower than that of the native communities. Therefore, the improvement of soil properties was very limited.