| The Shenfu-Dongsheng mining area is rich in coal resources and is the world's first modern production base with a capacity of 200 million tons of coal.The mining area is located in the arid and semi-arid ecologically fragile areas in western China.Due to large-scale and high-intensity coal mining activities,a series of ecological and environmental problems is inclined to occur,such as soil structure destruction,loss of soil moisture and nutrients,root system damage of vegetation,and reduction of plant and microbial diversity.Artificial vegetation construction by the use of different types of plants in the coal subsidence area is an important measure for ecological restoration in the mining area.While our knowledge of the secondary disturbance of the ecological control measures(transplanting and afforestation project)to the regional ecological environment in the coal subsidence area,especially to the diversity of environmental soil microorganism and the soil factors is insufficient.With the Shendong coal mine subsidence area and its artificial planting area in the semi-arid steppe area as the research areas,the regional plant communities are investigated and the soil physical and chemical properties were determined,and then soil microbial diversity and ecological distribution characteristics under thedisturbance of mining subsidence and afforestation were discussed.The main conclusions of this study are as follows:(1)there are 4 families,9 genera and 10 species of native plants in the Shendong coal mine area and the native plants are primarily perennial herbs with a few biennial herbs.Leguminous plants and gramineous plants are the major native plant species,accounting for 60% of the total native plant species.There is no significant difference in the plant diversity of the native herbaceous vegetation community under the reclaimed vegetation,there is no significant difference in the Shannon Wiener index and Simpson index of the herb community(P>0.05),and the natural restoration biomass is significantly increased(P<0.05).(2)In the coal mining induced subsidence areas,For the actinomycetes,their number decreased significantly(significance level<0.05)and the genetic diversity indexes,including Sobs,Shannon,Ace and Chao1,decreased significantly(significance level<0.05).For the fungal,the genetic diversity indexes,including Sobs,Ace and Chao1,decreased significantly(significance level<0.05).The species richness of AM fungal decreased significantly(significance level<0.05)and AM fungal genetic diversity indexes,including Sobs,Shannon and Chao1,decreased significantly(significance level<0.05).Total carbon content increased significantly(significance level<0.05);Urease content decreased significantly(significance level<0.05).The subsidence lowered the genetic diversity of soil microorganisms more markedly.(3)5664 bacterial OTUs were detected in the study area and can be annotatedto 40 phyla,99 classes,188 families,357 orders,626 genera,1329 species.Most of them belong to Actinobacteria,Proteobacteria,Chloroflexic and Acidobacteria.The impact of transplantation types on the total quantity and abundance variation range of soil bacterial is small.2038 fungal OTUs were detected and can be annotated to7 phylum,31 phyla,88 classes,192 families,408 genera and 671 species.The main phylum is Ascomycota,Basidiomycotac and Zygomycota.The transplanting species population have a greater variation range influence on the abundance of Ascomycota and Basidiomycota phylum in the soil fungal community,and on the abundance characteristics of Metarhizium and Mortierella are quite different,and the genetic diversity of fungi is more responsive to reclaimed vegetation.(4)16 species of 4 families,7 genera of AM fungi were separated and identified in the study area.In the molecular genetic diversity detection,216 OTUs were detected and annotated to 1 phylum,1 class,5 orders,9 families,9 genera,and46 species.Glomus are the dominant genus.Compared with the native control,AM fungus spore density,species richness,Sobs,Shannon index in Populus simonii forest land decreased significantly(significance level<0.05).(5)There are different correlations between soil microbial diversity and soil factors in the study area.Significantly positive correlations exist between the number of bacteria and acid phosphatase,catalase and ammonia nitrogen,respectively(significance level<0.05).And the number of fungi is significantly positively correlated with neutral phosphatase,sucrase and pH(significance level<0.05).The number of nematodes is significantly positively correlated withneutral phosphatase and catalase(significance level<0.05).The Simpson index of soil bacterial genetic diversity is significantly positively correlated with soil water content and ammonia nitrogen(significance level<0.05).Shannon index is significantly negatively correlated with the amount of plant biomass(significance level<0.05);the Sobs index,Shannon index,Ace index and Chao1 index of fungal genetic diversity were significantly negatively correlated with soil pH(significance level<0.05).The Simpson index was significantly positively correlated with soil pH,available phosphorus and total phosphorus(significance level<0.05),respectively.The influence of soil microbial distribution of plant communities composed of reclaimed vegetation is significantly correlated with soil factors to varying degrees,especially enzyme activity,ammonia nitrogen,and pH.(6)The spore density of AM fungal was significantly positively correlated with the number of actinomycetes and soil water content(significance level<0.05),and the species richness of AM fungal was extremely significantly correlated with the number of actinomycetes(significance level<0.01).The Shannon index of AM fungi genetic diversity distribution is extremely significantly correlated with Sobs,Ace,Chao1 index of bacterial genetic diversity(significance level<0.01).The Shannon index is significantly positively correlated with fungal genetic diversity Sobs index(P <0.01).There was a significant positive correlation(significance level<0.01)between Shannon index and Ace index,Chao1 index,and soil water content,respectively.The Sobs index of soil AM fungus has an extremely high correlation with plant biomass(significance level<0.01),The diversity of AM fungiin the soil of reclaimed vegetation plant communities was significantly correlated with soil microbial diversity,soil water content,and plant biomass.The number of actinomycetes,soil water content,microbial genetic diversity index,and plant organisms amount is more obvious.To sum up,In the semi-arid grassland coal mine subsidence area,the response to soil microbial diversity is different under the interference of subsidence and artificial reclamation,Quite different interactions exist between microbial populations,numbers,species diversity,molecular diversity and soil factors.The outcomes of this research can provide a basis for further exploration of the ecological restoration of the coal subsidence area in the semi-arid grassland area and can promote the coordinated development of coal resource development and environmental protection of the mining area. |
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