Characteristics and differences of surface soil microbial population and enzyme activities in opencast mining area of Pingshuo

The mining area is one of the most severely damaged and degraded regions in the world. In the process of land reclamation and ecological reconstruction of opencast coal mine, not only should the surface vegetation and organisms be restored, but also the construction of underground soil microbial ecosystems should be paid attention to. However, the related researches at domestic and abroad are mainly focused on vegetation reconstruction and soil physical and chemical property monitoring. There are few studies on the use of soil microorganism and enzyme activities to reveal the status of soil reconstruction in mining areas. Through the sampling analysis of 24 soil profiles in 8 plots, the number of bacteria, actinomycetes, and fungus and the activity changes of sucrase, urease and phosphatase in the dump and 0-20 cm topsoil of Pingshuo mining area were studied by spatio-temporal substitution method and one-way analysis of variance, to analyze their characteristics and differences. The results showed that（1） From the microorganism population and enzyme activity characteristic, regardless of the time of reclamation, the number of bacteria was absolutely dominant among the three types of microorganisms, accounting for more than 99.20% of the total microorganisms, followed by actinomycetes. The number of fungus was the least; the urease activity was the highest among the three enzyme activities, followed by sucrase activity, and phosphatase one the lowest.（2） From the point of view of the changes of the number of microorganisms population and the density of enzyme activity, the change trend of the number of three kinds of microorganisms and the activity of three enzymes in 0-20 cm topsoil was consistent with the reclamation years, which followed an up-down manner in line with time changes in reclamation and then kept going upward as reclamation years increases.（3） In the 0-20 cm soil layer, the microbial numbers in the southern dump after 27 years of reclamation reached 189.33×105 cfu/g, 0.1312×105 cfu/g and 1.1463×105 cfu/g, and the reclamation effect reached 65.88%, 66.46% and 67.74% of the microbial numbers in the original landform, respectively. The activities of sucrase, urease and phosphatase reached 1.96 mg 100 g-1 h-1, 6.36 mg 100 g-1 h-1 and 1.45 mg 100 g-1 h-1, respectively, and the reclamation effects reached 83.40%, 86.30% and 86.85% of that from the original landform, respectively. Therefore, the relevant research on soil microorganisms and enzyme a