Effects Of Open-pit Coal Mining On Soil Environment And Ecosystem Stability Of Typical Grassland

Large-scale open-pit coal mining affects soil structure,vegetation diversity and ecosystem stability.In this study,Shengli Coal and Electricity Base of North Electricity Company is taken as the research object,and the enclosed and non-enclosed areas of the west line outside the mine,the north line outside the mine,the South dumping site,the North dumping site and the bare dumping site are taken as the main research areas.And the indicators of plant community,soil factors,soil microorganisms(AM fungi,etc.),ecosystem health assessment and stability are determined and analyzed.This paper expounds the influence of open-pit coal mining on grassland ecosystem,and provides theoretical and data basis for ecological health assessment and ecological restoration of mining area.The research results are as follows:(1)Mining disturbance changed the composition and growth index of plant community.Stipa grandis and Cleistogenes caespitosa were dominant species in the original sample plot outside the mine.The dominant species in the South dumping site are Medicago sativa planted artificially and so on.Artemisia plants which represents degraded plants are dominant in the North dumping site.The plantdiversity,species evenness and biomass of the original sample plot outside the mine are significantly higher than those of the dumping site(p < 0.05).(2)It can be seen from the results of soil physical and chemical properties in the study area.Mining disturbance reduces soil water content,available potassium and total nitrogen content in the study area.The available potassium content in soil increased significantly with the distance from the mine(p < 0.05).(3)The results of soil enzyme activity in the study area:The activities of enzymes in all kinds of dump sites caused by mining disturbance are significantly lower than those in original dumping sites outside the mine.And its urease,invertase and alkaline phosphatase showed a significant upward trend with the increase of distance from the mine(p < 0.05).(4)A total of 31 species of AM fungi belonging to 9 genera and 6 families is isolated from the study area: Among them,9 species belonged to one genera in Acaulosporaceae,16 species belonged to four genus in Glomeraceas,2 species belonged to one genus in Entrophpsporoceae,2 species belonged to one genera in Claroideogomeraceae,1 specie belonged to one genus in Gigasporaceae,1 specie belongs to one genus in Diversisporaceae.The dominant species are G.reticulatum?G.deserticola?G.macrocarpum?A.sp1 and A.gedanessis.Discovery of endemic species A.sp.5 in N2 plot;discovery of endemic species G.diaphanum in S3 plot.(5)The diversity indices of AM fungi in the study area are as follows: Spore density is 39.742-389.273/20 g,species richnes is 4.376-10.051/20 g,Shannon-Weiner index is 0.609-2.003,Simpson index is 0.666-0.985.The diversity index of AM fungiin out-of-mine primary plots is significantly higher than that in dumping sites(p <0.05).(6)Based on 18 S rRNA,16 S rRNA and ITS high-throughput sequencing,the results showed that the total 13 identified phyla of soil bacteria OTU subgenus belong to Actinobacteria?Proteobacteria?Acidobacteria?Chloroflexi?Gemmatimonadetes and so on.Total 6 identified phyla of soil fungus OTU subgenus belong to Scomycota?Basidiomycota?glomeromycota?Chytridiomycota?olpidiomycota and Mortierellomycota and so on.The results showed that the OTU of soil AM fungi belong to Septoglomus? Rhizophagus? Claroideoglomus? Glomus and Kamienskia belong to 5 phylum.The diversity of soil microorganisms varies with the disturbance of open pit mining,but the trend is not obvious.(7)According to the health evaluation system of VOR and CVR comprehensive index,the results are as follows: Four sample plots in the original sample area outside the mine are in the "warning" level,while the rest are in the "unhealthy" level.Four plots in the sample area of the South dump site all show "warning" grade,two plots in the North dump site are in "warning" grade,and the rest are in "unhealthy" grade.The number of samples in the dump site at the "warning" level is higher than that in the original sample area outside the mine.(8)According to the diversity-stability evaluation system,the results are as follows: the South dumping site exhibits higher stability,and the diversity and stability of plant species on the south side of the dumping site and on the flat plate are higher than those on the North side.The enclosed area shows higher stability than thenon-enclosed area.From the interference gradient,it is found that the stability increases with the increase of the interference distance.It can be seen that the stability of the original sample plot outside the mine is higher than that in the dumping site.(9)The diversity of microorganisms(AM fungi)is taken as an evaluation index,and the correlation results showed that: The diversity of AM fungi is positively correlated with the baseline index and stability,which can be used as an index for evaluating the stability of mining areas.Coal open-pit mining affects the soil microbial diversity of grassland,and the impact decreases with the increase of distance from the mining center.Microbial diversity index can be used as an important index to evaluate the stability of soil environment and ecosystem in mining area.