| Huaibei coal mining area has formed large-scale coal mining subsidence area,which seriously damaged the ecological environment of the coal mine and its surroundings.In order to understand the effects of different reclamation modes on soil physical and chemical properties and microbial communities,this study was conducted on reclaimed soils from coal mining subsidence areas after deep-digging and shallowfilling and fly ash filling.The changes of soil physical and chemical properties in different reclamation years and different vegetation treatments were investigated.The genetic information of soil bacteria at different taxonomic levels was obtained by Illumina Miseq high-throughput sequencing technology.The relationship between soil fertility level and bacterial community composition and biodiversity in different reclamation years and different vegetation treatments was clarified.The conclusions were as follows:(1)At the beginning of deep-digging and shallow-filling,total nitrogen,available nitrogen and other indicators were at low level.The soil physical and chemical properties were improved with the increase of reclamation years.After 13 years of deepdigging and shallow-filling,total nitrogen,available phosphorus and organic matter were recovered to the same level as the unreclaimed soil basically.The level of total potassium was higher than unreclaimed soil.Based on principal component analysis,a comprehensive evaluation of soil fertility in 0～20 cm soil layer with different reclamation years was conducted.It was found that the soil quality index(SQI)values in different reclamation years were as follows: 13a> 8a> 1a,The SQI value of reclaimed soil after 13 years was similar to that of unreclaimed soil.The results indicated that soil fertility had recovered to the level of unreclaimed soil after 13 years of reclamation.(2)The bacterial community composition of soil was similar between different years of deep-digging and shallow-filling.Proteobacteria,Actinobacteria and Acidobacteria were the top 3 dominant bacteria in soil of this study area,and Proteobacteria accounted for the largest proportion with the relative abundance of22.77%～40.88%.The relative abundance of Proteobacteria and Bacteroidetes in reclaimed soils was 0.39%～18.12% and 0.09%～7.61% higher than that in unreclaimed soils.The richness and evenness of soil bacterial community were low at the beginning of reclamation,but gradually recovered to the same level as unreclaimed soil after 8and 13 years of reclamation.The bacterial richness of the surface soil was higher.Compared with the unreclaimed soil,Chao1 index and ACE index of surface soil increased significantly by 8.56% and 8.10% after 13 years of reclamation.New and independent microbial communities were formed in reclaimed soil,but the bacterial communities were similar to those in unreclaimed soil.The results of redundancy analysis showed that available nitrogen,total nitrogen,and available phosphorus were the main factors affecting soil SQI values in different reclamation years.Actinomycetes and Chlorobacteria were affected by soil fertility factors.(3)There were significant differences in available phosphorus,total potassium,total nitrogen,available nitrogen and organic matter with different vegetation reclamation treatments in the mode of fly ash filled.Total potassium was over standardⅢ,and available potassium was over standard Ⅰ.The results of principal component analysis showed that the fertility level of surface soil in different vegetation reclamation treatments were as follows: cultivated land > forest > orchard.The SQI value of 0～20cm soil layer was higher than that of 20～40 cm soil layer.The SQI value of reclaimed soil was 1.32～3.65 lower than that of unreclaimed soil.Soil fertility was still lower than that of unreclaimed soil after 20 years of fly ash filling.(4)There was no significant effect of different vegetation treatments on the distribution of dominant bacterial community in reclaimed soils.Proteobacteria,Acidobacteria and Actinobacteria were the top 3 dominant bacteria in fly ash filled soil.The proportion of Proteobacteria in surface soil of reclaimed cultivated land was the largest,which was 16.25% and 16.92% higher than that of forest and orchard.The richness and evenness of bacteria in surface soil had no significant difference of each treatment after reclamation,which was similar to that of unreclaimed soil.There were differences in bacterial community composition between 0～20 cm and 20～40 cm soil layers,reclaimed soil and unreclaimed soil also had differences.The bacterial community composition was different in different vegetation reclaimed soils,however,the soil bacterial communities of forest and orchard were highly similar.The results of redundancy analysis showed that there was negative correlation between soil p H and soil SQI values,Acidobacteria and Bacteroidetes had obvious responses to soil fertility factors.(5)Based on the changes of soil fertility and soil bacterial community structure,the soil quality had recovered to unreclaimed level after 13 years under the mode of deep-digging and shallow-filling.Cultivated land was the best reclamation direction under the mode of fly ash filling.The research results can provide theoretical support for soil quality improvement of reclaimed soil in Huaibei mining areas.Figures [47] Tables [18] References [164]... |
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