Selection Of Suitable Species For Vegetation Restoration In Grassland Open-cast Coal Mine

The mining of open-pit coal mines has brought extremely serious ecological and environmental problems to the originally ecologically fragile grassland areas.The dumps formed by stripped waste generated during the mining process occupy a large area of grassland,destroyed the vegetation landscape,and disturbed the ecology system.Therefore,it was necessary to select suitable plant species for the revegetation work of the dump.The Xilinhot Wu Coal Germanium Mine and the Xi’er Open-pit Coal Mine Dump in Shengli Coal Field were taken as the research objects.The vegetation reconstruction work began in2007.Based on many years of ecological restoration,the field investigation and indoor analysis and research had continued in September 2020.Plant height,frequency,density,coverage and biomass were investigated with plots on the directional orientation of slopes(East,West,South,North)and three treatments(bio-fence + artificial mixed seeding,Pure artificial mixed seeding,sand-protecting + mixed seeding)to analyze the succession degree,plant species survival status,diversity,niche,and interspecific associations of plant communities after vegetation reconstruction.At the same time,the vegetation conditions in10 directions of grasslands around the mining area were compared.The main results were as follows:1.The succession degree of plant communities in the dumping yard with different slope directions and different treatments was far lower than that of the top-level community,which belongs to the primary stage of succession.The plant coverage reached an average of 50%,and the east slope coverage was the largest.bio-fence + artificial mixed seeding>pure artificial mixed seeding>sand-protecting + mixed seeding,vegetation restoration improved the overall slope coverage of the dump site.2.The growth of artificial planting of shrubs and sub-shrubs(Caragana microphylla,Caragana korshinskii,Lespedeza daurica),perennial herbaceous plants(Medicago sativa,Astragalus adsurgens,Medicago sativa,Medicago ruthenica and Elymus dahuricus)as well as annual plant(Blassika kapestris)was relatively stable.Invasive species were dominant in one-two-year-old and perennial plants,and occupy a large proportion,mainly in Gramineae and Compositae.3.In the plant community on the dump site,the Shannon-Wiener diversity index was higher on the west slope,and there was no significant difference between the south slope,sand-protecting + mixed seeding treatment and the surrounding areas of the mining area;the west slope Margalef richness index was higher,and the east slope,south slope,There was no significant difference between the northern slope and the surrounding area of the mining area.The bio-fence + artificial mixed seeding,sand-protecting + mixed seeding treatment were higher;the Pielou uniformity index of the south slope was higher,and there was no significant difference between the three treatments and the surrounding mining area.4.There was a competitive relationship between plants with different slope directions and different treatments in the dump.The competition between perennial and annual plants was greater,and the competition between perennial and perennial plants was the second.On the west slope,south slope,north slope and 3 treatments,there was a negative but not significant correlation among plant species;there was a positive correlation among plant species on the east slope,and a significant positive correlation among plants around the mining area.5.On the slope surface of the dump site,choosing shrub Caragana microphylla,Caragana korshinskii,Lespedeza daurica,annual plant Blassika kapestris,Cosmos bipinnatus,Artemisia sieversiana,perennial plant Astragalus adsurgens,Melilotus officinalisi.Medicago sativa and Lespedeza daurica can be added to sand-protecting barrier measures.In the early stage of vegetation reconstruction,choosing to add griophyllum squarrosum and Avena chinensis for sowing.The coverage of bio-fence is conducive to the growth of artificial sowing plants in the early stage and provided a better living environment for the later invading plants.The planting proportion of plant species could be designed according to shrubs and semi-shrubs: perennial herbs: annual plant equal to 6﹕2﹕2,which performed well in the east slope.