Study On Characteristics Of Vegetation Restoration And Distribution Of Soil Organic Carbon In Dump Of Open-pit Coal Mine In Typical Steppe

The opencast coal mine is usually mined after stripping or digging the land,and a large number of dump sites will be produced in the mining process,which has a great impact on the surrounding grassland ecosystem.Phytoremediation and reconstruction of the dump is an important means to reduce the ecological pressure of the mine and deal with environmental protection problems.In the long run,the change of soil organic carbon in the process of phytoremediation may affect the stability and sustainability of phytoremediation.Grassland ecosystem is a major component of carbon cycle and carbon pool on land,and the change of soil organic carbon is also critical for vegetation restoration in mining areas.However,the general experimental research methods are mostly short-time research results,and do not pay attention to the long-term lasting effect of dump restoration and the long-term dynamic characteristics of vegetation restoration.In this study,the Wulantuga germanium open-pit coal mine in Xilingol typical grassland was taken as the research object to observe the vegetation restoration characteristics and soil organic carbon changes of the dump under different measures,different slope directions and different restoration years under the same basic conditions.The main results are as follows:(1)compared with 2011,the number of species in sand barrier and willow fence treatment areas increased,the average density and total coverage of sand barrier management area also increased,and the average density of Liuyuan management area increased,but the total coverage decreased.Compared with the sand barrier restoration area,the soil bulk density of the willow fence restoration area is closer to the control area,the soil water content is higher than the sand barrier restoration area,the p H is lower than the sand barrier restoration area,and the soil organic carbon content is higher than that of the sand barrier restoration area.(2)the proportion of annual and biennial plants in shady,sunny and semi-sunny slopes was larger,the proportion of perennial herbs in shady slopes was relatively small,and that of shrubs was relatively large,while the contents of soil water content,organic carbon and easily oxidizable organic carbon in the middle sunny slopes of the three slopes were the highest,but there was no significant difference in soil bulk density,p H and soil dissolved organic carbon among the three slopes.During artificial restoration,different plants can be planted according to different slope directions,shrubs such as Caragana Caragana and Caragana microphylla can be planted on semi-sunny and shady slopes,and herbs such as brassica,Elymus and rhinoceros can be planted on sunny slopes.(3)long-term dynamic observation showed that during the 14 years,with the increase of restoration years,the height,coverage,density and aboveground biomass of dump slope increased at first and then decreased,and the coverage and density were the highest in the12 th year of restoration.Height and aboveground biomass were the highest in the 10 th year.The dump is suitable for planting Caragana microphylla,Caragana Caragana,Magnolia,Brassica and other plants,but it is necessary to stubble the shrubs and semi-shrubs such as Caragana microphylla and Caragana Caragana when restoring for 6-8 years.With the increase of restoration years,soil p H basically showed a downward trend,while soil organic carbon content and storage showed an upward trend.