Study On Plant Restoration Model And Soil Remediation Effect Around Light Rare Earth Tailings Pond

Due to the long-term pollution of light rare earth in the surrounding area of Baotou light rare earth tailings reservoir,the surface soil is black,the physical and chemical properties of the soil deteriorate,the stability of the protophytic community deteriorates,showing a trend of retrograde succession,and a large number of artificially constructed trees and shrubs die.In view of the above problems,based on the study of plant diversity and plant community characteristics,this paper selected different plant communities to restore soil effects,screened light rare earth enrichment tolerant plants,made plant-mycorrhizal environmental protection basins,plant community evaluation and systematically studied the existing community model optimization,with a view to providing scientific guidance for soil restoration and improving artificial vegetation restoration.The effect provides strong support.The main conclusions of this study are as follows:1 Investigation of plant diversity and floristic distribution within 1 km of LRE tailings reservoir shows that there are 101 species belonging to 70 genera and 30 families in this area,accounting for 31.58%,18.42%,11.98%and 9.97%,2.06%and 0.32%of the total seed plant families,genera and species in Baotou City and China.Area S5 and area S5 are artificial plant communities,and the succession level of plant communities is at a lower stage.2 Soil physical properties showed that all the five research areas did not meet the soil restoration standard,and the ratio of non-capillary porosity to capillary porosity was the highest in S5 area after restoration,with the ratio of 0.21,0.25 and 0.30 as the soil layer gradually deepened;soil bulk density ranged from 1.62 to 1.81 g.cm-3,exceeding the limit value of 1.40 g.cm-3.Chemical properties showed that the soil pH value decreased to slightly alkaline soil in the five study areas,while the nitrogen,potassium and phosphorus elements were at a low level.Soil fertility evaluation showed that plant diversity>plant number>vegetation coverage>community structure>bare land.Rehabilitation of light rare earth plants in soil showed that shrubs were better than trees.3 Lespedeza heterophylla L.has a strong ability to transfer and absorb lanthanum and cerium in soil.It is a plant enriched with lanthanum La and cerium Ce light rare earth elements.The transfer coefficients of Haloxylon ammodendron and Nitraria spinosa are more than 1,which can be used as tolerant plants of lanthanum and cerium light rare earth elements to plant Lespedeza.I.lilacina and Pinus tabulaeformis had the highest inoculation rate in soil experiments collected in NW3 area,with La 34.16%and Ce 24.13%.Plant uptake of La increased by 1.03-2.66 times and Ce increased by 1.03-2.61 times,which effectively increased Pinus tabulaeformis uptake.The inoculation rates of R.intraradices and Lespedeza were the highest in soil samples collected from NW3 area,with 88.54%La and 74.81%Ce,1.33-1.62 times more La and 1.32-1.37 times more Ce uptake by plants.4 Analytic Hierarchy Process(AHP)was used to evaluate the ecological restoration characteristics of plant communities.The results showed that the order of community stability was S4>S5>S3>S2>S1.According to the evaluation results,the existing plant community model was optimized,including the restoration of light rare earth pollution model,landscape effect model,economic benefit model and disaster prevention model.