Study On Soil Microbial Community Structure Changes And Driving Mechanism After Coal Mining Disturbance In Loess Plateau Area

Loess Plateau Area is an important coal production base in China.The local ecosystem,especially the soil environment,has been seriously interfered by coal mining disturbance.Soil microorganism is an important representation of soil productivity and active function,which is widely concerned by academia.Therefore,it is necessary to study the systematically scientific problem of soil microbial community structure changes and driving mechanism after coal mining disturbance in Loess Plateau Area.This study would provide new ideas for monitoring soil-plant system changes in mining area,and provide scientific basis for exploring new technologies for microbial restoration of damaged mine ecological environment.In this study,the typical characteristics after coal mining disturbance in Loess Plateau Area,besides the land cracks area of Dongping Coal Mine in Shanxi Province,land subsidence area of Daliuta Coal Mine in Shaanxi Province,and land reclamation area of Heidaigou Coal Mine in Inner Mongolia,were selected as the research object.Soil physicochemical properties,containing soil water,temperature,pH,electric conductivity,organic matter,nitrate nitrogen,ammonium nitrogen,available phosphorus,were determined as the basic environmental indicators.Using 16 S rRNA high-throughput sequencing technique to determine the soil microbial community structure,the genetic information of soil bacteria at different classification levels were obtained.Then using Alpha and Beta diversity to analyse the composition of soil microbial communities,and using the molecular ecological network for sketching the internal network of soil microbial communities.Based on the associated network with soil physicochemical properties,using the method of space-time interchange,the changes of soil microbial community structure were compared before and after coal mining disturbance.Finally,the driving mechanism of soil microbial community structure changes was probed,and ecological restoration strategy of soil microbial application after coal mining disturbance was put forward.The major results were as follows:(1)Most values of soil physicochemical properties were decreased,and soil microbial community structure and its network interactions tended to be complicated due to land cracks after coal mining disturbance.First,there was a partial loss of soil nutrients.The content of soil temperature,pH,organic matter,available phosphorus and available potassium was significantly reduced.Second,soil microbial community structure richness and uniformity increased by about 50% due to land cracks.The relative abundance of phylum,more than 90%,were Proteobacteria,Actinobacteria,Acidobacteria,Chloroflexi,Gemmatimonadetes,Planctomycetes,Nitrospirae,and Bacteroidetes.Cupriavidus,Haliangium,Lysobacter,as dominant species,presented in land cracks area.Third,soil microbial molecules ecological network connection tended to be more complicated after coal mining cracks due to land cracks.Moreover,the relationship between network connections and interactions was strengthened.Forth,the difference of soil microbial community structure composition was caused by soil nutrient loss due to land cracks.The relationship between soil physicochemical properities and modules has changed.However,the significant positive correlation between soil organic matter and the module has not changed.In addition,it was found that Skermanella was closely related to the value of pH and water.Soil microbial community has changed in order to adapt to land cracks after coal mining disturbance.(2)Most values of soil physicochemical properties were decreased,and the soil microbial community structure and its network interactions tended to be complicated due to land subsidence after coal mining disturbance.First,soil nutrients were lost due to land subsidence.The content of soil temperature,organic matter,available phosphorus,available potassium,nitrate nitrogen and ammonium nitrogen were significantly reduced.Second,the richness and uniformity of soil microbial communities decreased by about 20% available due to land subsidence.The relative abundance of phylum,more than 90%,included Actinobacteria,Proteobacteria,Acidobacteria,Chloroflexi,Gemmatimonadetes,Planctomycetes,Armatimonadetes,Bacteroidetes,and Streptomyces.Streptomyces and Acidibacter,as the dominant species,appeared in the land subsidence area.There was not an obvious classification of soil microbes between land subsidence area and control area.The transition of various species in land subsidence area was stronger than in the control area.Third,due to land subsidence after coal mining disturbance,the connection of soil microbial molecular ecological network tended to be more complex,the network concentration was increased,the connection between networks increased,the positive correlation was increased,the number of network connections and the interaction relationship was strengthened.Forth,a certain difference in soil microbial community structure composition was caused by the loss of soil nutrients due to land subsidence,while this relationship was not very obvious.Except for the content of soil electric conductivity and nitrate nitrogen,the negative correlation between the network connection and other physicochemical factors has been strengthened.In addition,it was found that there was a negative correlation between Variibacter and pH,electric conductivity and nitrate nitrogen,while which was positively correlated with soil temperature and ammonium nitrogen.(3)Most values of soil physicochemical properties have been improved,while the soil microbial community structure and its networks were relatively simplistic due to land reclamation after coal mining disturbance.First,the content of soil physicochemical properties improved obviously after land reclamation.Soil moisture,pH,electric conductivity,organic matter,available phosphorus,available potassium,nitrate nitrogen and ammonium nitrogen content increased significantly,while soil temperature showed a significant downward trend.Second,the diversity of soil microbial community structure increased after land reclamation,which was about 1.63 times of the control area.The relative abundance of phylum,more than 90%,included Proteobacteria,Actinobacteria,Chloroflexi,Acidobacteria,Planctomycetes,Bacteroidetes,Gemmatimonadetes,and Nitrospira.Geodermatophilus,Microvirga,Phycicoccus and Pseudonocardia,as dominant species,appeared in the land reclamation area.Third,due to land reclamation,soil microbial community structure tended to be more diversified,while the degree of contact was weakened.The positive cooperative relationship between the strains was strengthened,which tends to cooperate.Forth,the change of soil microbial community structure diversity was affected by the improvement of soil nutrient level after land reclamation.There was obvious clustering in various points in the land reclamation area.Moreover,there existed a significant positive correlation between soil microbial community and available phosphorus and nitrate nitrogen at OTU level in land reclamation area.In addition,it was found that there was a negative correlation between Solirubrobacter and organic matter and available potassium.(4)Constructing the changes of soil microbial community structure and the driving mechanism of soil environmental factors in three types of land cracks,land subsidence and land reclamation after coal mining disturbance.Then,the changes of soil microbial community structure and the mutual feeding mechanism of soil environmental factors after coal mining disturbance were sketched out based on the spatiotemporal interchange.That is,after the land cracks,land subsidence and land reclamation caused by coal mining disturbance,soil microbial community and soil environmental factors interacted,and the first step of soil restoration was taken by soil microbiome with adaptive changes.Furthermore,other potential factors affecting soil microbial community structure were analysed and discussed.For example,the geographical location of mining areas,local meteorological conditions,seasonal changes,the intensity of coal mining work disturbances,post-harvest reclamation projects,and other potential factors.(5)Putting forward the enlightenment of ecological restoration in the mining area based on the change of microbial community structure.Every destination is different,developing the potential new species applicable to the local region.Prevention-oriented,supervising the coal mining disturbance during the whole life cycle.Soil microbial recovery first,promoting multiple strategies jointly.Introducing a new soil microbial molecular ecological network monitoring system.