| The extensive mining of ion-type rare earth ore leads to a large amount of tailings accumulation,water and soil erosion,water pollution and other major ecological and environmental problems.At present,the ecological restoration mode of rare earth tailings is simple,which cannot solve the soil and water loss problem on the surface,especially in the tailing area and the mining area.The biological soil crust(BSCs)can form a stable cover on the surface of these arid or degraded habitats,which can lay a foundation for the ecological reconstruction of the tailing area.At present,the diversity of soil crust biological groups(bacteria,fungi and algae)and their relationships during the early succession of ionic rare earth tailings are not clear,and the mechanism of BSCs formation is not clear.Therefore,this paper takes the soil BSCs of ionic rare earth ore tailings in southern Jiangxi as the research object,and adopts field investigation,laboratory analysis and identification,and high-throughput sequencing methods.Tail mining area of bare soil is studied,the algal crust,algae,moss crust,lichen crust,lichen,moss crust and moss crust and herbaceous vascular plants the succession of 7kinds of soil crust type of bacteria,fungi and algae diversity status,combined with the soil physics and chemistry,topography and vegetation parameters,to reveal the relationship between the coexistence of bacteria,fungi and algae,and probes into the construction of soil crust mechanism,it provides a theoretical basis for the remediation of ionic rare earth tailings.The main conclusions are as follows:(1)Soil crusts significantly improve the soil physical and chemical properties of ionic rare earth tailings.The contents of soil water content,total nitrogen,total phosphorus,total organic carbon,microbial biomass carbon and ammonium nitrogen increased significantly in the later stage of crust succession.(2)With the succession of soil crust,the diversity and abundance of microbial community increased significantly.The abundance of Proteobacteria and Acidobacteria in the bacteria gradually increased.The abundance of Chloroflexi and Actinobacteria decreased with succession.The abundance of Ascomycota in mossy crusts and herbaceous vascular plants was the lowest and significantly lower than that in bare soil,but with the development of BSCs,the abundance of Basidiomycota tended to increase.(3)The succession of BSCs promoted the interaction between species in bacterial and fungal communities,and their community structure tended to be stable.The interaction between species was strongest in the lichen-moss skin stage of the bacterial network.The interaction between species in the herbaceous vascular plant stage of fungi was the strongest and the structure was the most stable.(4)During the early succession of ionic rare earth tailings,39 species of freshwater algae were identified by BSCS,belonging to 37 genera(2 species of Chlorella and 2 species of Synechococcus).Chlorophyta had a maximum of 17 genera,followed by Cyanophyta 11 genera,Bacillariophyta 6 genera,Euglesophyta 2 genera,and Xanthophyta 1 genera.There were significant differences in the number of algal species among different types of BSCs,and the similarity between the two adjacent stages was at a high level.The species richness and biomass of algae increased and then decreased,and the algae diversity was the most abundant at the stage of algal crusting.(5)Microhabitats play an important role in the succession process of BSCs from bare soil to algal crusting,but in the subsequent succession stage of algal crusting,it is likely that environmental stress and soil resource competition combined to drive the succession process.(6)The abundance of bacterial community had a positive effect on the abundance of fungi and algae communities,especially fungi.The abundance of the fungal community has a negative effect on the abundance of algae.Bacterial plays a leading and fundamental role in the process of soil crust succession. |
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