| The rapid development of China's economy is closely related to coal consumption,which has been growing with the expansion of economy and industry.However,coal mining will break the balance of local ecological environment,causing a series of ecological and environmental problems.Mining activities cause degradation of soil quality,damage to regional ecosystems,and reduce biodiversity and land productivity.Human-induced changes in soil quality and biological characteristics have a profound impact on the healthy development of ecosystems,especially in arid and semi-arid ecologically fragile regions.How to improve soil nutrients,improve soil structure and finally improve soil quality is the key link of soil ecological restoration.The research shows that soil microorganism plays an important role in regulating a variety of ecological functions.Microbes take nutrients and habitats from the soil and affect soil quality.In view of the comprehensive role of microorganisms in energy migration,nutrient cycling and vegetation restoration,the relationship between different vegetation restoration conditions and soil microbial communities can be explored,which can provide important information for ecological restoration.Therefore,this research in the development of soil and vegetation condition,the influence of the mining area reclamation reconstructed soil physical properties under different vegetation configuration mode,through the study of the comprehensive evaluation of soil quality study the evolution law and determine the applicability of the different soil quality evaluation method,at the same time using high-throughput sequencing technologies to study the mining reclamation microbial diversity variation characteristics and impact factors of typical vegetation,as mine reclamation soil quality evaluation based on restoring effect.The main conclusions are as follows:?1?Vegetation restoration is helpful to improve physical,chemical and biological properties of reconstructed soil.Soil bulk density,pH,electrical conductivity and sodium adsorption ratio increased with the increase of soil depth in different sampling sties,and the change rule of soil particle composition was not obvious with the increase of soil depth,while the other soil chemical and biological properties decreased with the increase of soil depth,and the differences were significant.The surface soil properties of different soil layers were improved obviously.In the 0-20 cm topsoil,the bulk density was the lowest(1.28 g·cm-3)in both natural restoration land and reclamation shrubs+herbs,and the highest(1.35 g·cm-3)unreclaimed land;pH was lowest in natural restoration land?8.40?and highest in unreclaimed land?8.74?;the electrical conductivity was the lowest(87.45 mS·m-1)in the natural restoration land and the highest(100.31mS·m-1)in reclamation arbors+herbs;the organic matter content was the highest in the natural restoration land(22.08 g·kg-1)and the lowest in the unreclaimed land(9.3 g·kg-1);the total nitrogen content was the highest in the natural restoration land(0.63 g·kg-1),and the available nitrogen content was the highest in the reclamation shrub land(13.13 mg·kg-1),and the total nitrogen and available nitrogen were the lowest in the unreclaimed land(0.13 g·kg-1 and 4.59 mg·kg-1,respectively);the total phosphorus content was the highest(0.57 g·kg-1)in reclamation arbors+herbs,and the lowest(0.42 g·kg-1)in the unreclaimed land;the content of available phosphorus was the highest(12.48 mg·kg-1)in the reclamation herbs and the lowest(3.69 mg·kg-1)in the reclamation shrubs;the total potassium content was the highest in reclamation arbors+herbs(18.70 g·kg-1),the available potassium content was the highest in reclamation shrubs(162.50 mg·kg-1),and the total potassium and available potassium were the lowest in the unreclaimed land(5.79 g·kg-1 and 39.04 mg·kg-1,respectively);the cation exchange capacity was the highest in reclamation shrubs(18.51 cmol·kg-1)and the lowest in unreclaimed land(15.43 cmol·kg-1);the sodium adsorption ratio was the lowest?0.43?in reclamation shrubs+herbs and the highest?0.86?in unreclaimed land;catalase and urease were the highest in reclamation shrubs,with 6.53 mg·?g·24h?-1 and 2.01 mg·?g·24h?-1,respectively,and the lowest in unreclaimed land,with 2.85 mg·?g·24h?-1 and 0.04 mg·?g·24h?-1,respectively;alkaline phosphatase was the highest(0.86 mg·?g·24h?-1)in reclamation shrubs and the lowest(0.47 mg·?g·24h?-1)in reclamation arbors;sucrase was highest in natural restoration land(14.26 mg·?g·24h?-1),and lowest in unreclaimed land(1.51 mg·?g·24h?-1);microbial carbon content was the highest in natural restoration land(378.97 mg kg-1),and microbial nitrogen content was the highest in reclamation shrubs(83.39 mg kg-1),and the lowest in unreclaimed land(5.98 mg kg-1 and 15.22 mg kg-1,respectively).The selection of shrub vegetation type in this region is the main method for the rapid recovery of soil physical,chemical and biological properties of reconstructed soil,but after 20 years of vegetation restoration,the physical,chemical and biological properties of reconstructed soil is still not reached the level of original natural soil.It can be seen that the soil restoration is a long process?2?Four soil quality assessment methods?nonlinear soil quality index method,linear soil quality index method,nonlinear Nemero index method and linear Nemero index method?were used to evaluate the quality of the reconstructed soil.The minimum data sets of soil quality evaluation indexes in the study area were selected,including sand,alkaline phosphatase?ALP?,sodium adsorption ratio?SAR?and microbial biomass carbon?MBC?.The main limiting factors of soil quality are sand content,phosphorus availability,salinization and carbon activity.Vegetation restoration is beneficial to improve the soil quality of reconstructed soil.?3?The results of this study showed that vegetation restoration in the reconstructed soil of the Loess Plateau mining area could significantly improve the OTUs,bacterial community richness,diversity index and some of soil biochemical properties.However,despite the vegetation restoration for nearly 20 years,the structure of soil bacterial community did not change significantly.The results of redundancy analysis?RDA?and Pearson correlation coefficient showed that the bacterial community had no obvious response to biochemical properties,and the dominant bacteria were Proteobacteria,Actinobacteria and Acidobacteria.Shrubs are considered to be the best vegetation restoration type in this area because of its good biochemical characteristics,bacterial richness and diversity.The main influencing factors of soil biochemical properties on the soil bacterial community diversity are:soil organic matter?SOM?,available nitrogen?AN?,catalase?CAT?and sucrase?SUC?.?4?The correlation between soil quality comprehensive evaluation index and microbial diversity index was more significant than in single indicator under different vegetation types.This indicated that the soil quality comprehensive evaluation index could reflect the changes of microbial diversity better,and the soil quality index could be used as an indicator factor to evaluate the soil microbial diversity.On the contrary,the quality of soil can be influenced by the diversity of microbial.Vegetation restoration can significantly affect soil quality,which indirectly indicates that vegetation restoration has an impact on soil microbial diversity. |
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