不同人工恢复措施下高寒矿区煤矸石山植被和土壤恢复效果研究

Effectiveness of different artificial restoration measures for soil and vegetation recovery on coal mine tailings in an alpine area

高寒矿区露天煤矿开采对当地生态环境造成巨大破坏,通过采取不同人工恢复措施,并对其植被和土壤的恢复效果进行评估和比较,对于指导煤矸石山生态恢复实践活动具有重要意义。通过设置人工建植、人工建植+覆土、人工建植+施肥3种恢复措施,经过5年恢复,比较不同恢复措施对植被群落组成、植物生长、土壤性质的影响。结果表明,3种恢复措施均能够形成人工草地群落,但草地群落组成差别较大,植被盖度、高度、密度及地上生物量等植物生长特征差异显著(P<0.05),3种恢复措施均显著提高了土壤有机质含量(P<0.05),但与原始群落相比,短期人工恢复对土壤肥力及pH值的改善作用依然有限。植物生长指标与土壤全氮、有机质特别是全磷之间相互促进。单纯的人工建植方式不利于生态修复,采取人工建植+覆土或人工建植+施肥的组合方式,是恢复高寒矿区煤矸石山生态系统的有效途径。从减少经济投入的角度出发,可考虑通过施肥替代人工覆土,实现煤矸石山人工草地生态系统的稳定发展。

Opencast coal mining causes major damage to the local ecological environment in alpine coal mining regions. It is important to evaluate the effectiveness of different artificial restoration options for revegetation and soil reclamation of coal mine tailings, in order to optimize the ecological restoration process. In this study, three restoration measures [revegetation of untreated mine tailings(R), revegetation with soil replacement(R-S), and revegetation and fertilization(R-F)] were implemented. Differences in vegetation community composition, plant growth and soil parameters under the different restoration measures, undisturbed grassland(UG) and untreated coal mine tailings(CK) were monitored and compared after 5 years. The main results were: The artificial grasslands that were developed under R, R-S, and R-F treatments differed in their botanical species composition, and there was significant variation in plant growth characteristics, including vegetation ground cover, height, density and above-ground biomass(P<0.05). Soil organic matter content increased significantly(P<0.05) in R, R-S, and R-F treatments, compared to CK. Compared with natural undisturbed grassland, the three artificial restoration treatments R, R-S, and R-F had inferior soil quality including soil fertility and pH value, at the end of the 5 year study period. Plant growth parameters were positively correlated with soil total nitrogen, soil organic matter, and especially with soil total phosphorus. Thus, synergistic promotion should be developed between the soil and plants. A single method such as artificial revegetation used alone is not conducive to ecological restoration. The combined use of artificial revegetation in conjunction with soil replacement or fertilization, proved to be effective for ecological restoration of coal mine tailings at this alpine site. From the perspective of effective vegetation restoration and cost reduction, treatments that include fertilizer, especially organic fertilizer are likely to perform better than replaced topsoil treatments. Using these cost-effective synergies arising from plant-soil interactions, reclamation of coal mine tailings and grassland ecosystem restoration would be facilitated.