| In this paper,three plots of Pennisetum sp.were planted in the Pisha sandstone area of Erdos,Inner Mongolia.The dynamic changes of soil microbial amounts and soil enzyme activity in five periods were studied,and the correlation analysis was carried out according to the basic physical-chemical properties of the soil to explore the relationship between soil microbial amounts,enzyme activity and basic physical-chemical properties in Pisha sandstone area.rDNA-ITS molecular biological method was used to classify and identify dominant fungi in soil.Illumina MiSeq sequencing method was used to identify the dominant bacteria.The diversity of soil bacterial community after planting Pennisetum sp.in sample areas was studied in order to make a comprehensive and thorough study on the Pisha sandstone ecosystem in the future.The research in this paper lays a theoretical foundation.The main research results are as follows:1.The dynamic change of basic physical-chemical propertiesPlanting Pennisetum sp.can significantly improve the status of soil organic matter in Pisha sandstone area.In three sample plots,soil organic matter was higher than that in the early planting period.The soil water content was different in different periods,but the soil water content decreased first and then increased with the growth of Pennisetum sp.in the three plots.The change trend of soil pH was not obvious during the whole growth period.2.The dynamic change of soil enzyme activityDuring the growth stages of Pennisetum sp.,the activities of urease,alkaline phosphatase and catalase in the hilltop were higher than those in the other two plots.The change trend of polyphenol oxidase and sucrase activity was the same,and the activity decreased gradually with the growth of Pennisetum sp..The activities of urease and sucrase in farmland were higher than those in early planting period.The activities of urease,polyphenol oxidase,alkaline phosphatase and catalase in the flood land were lower than those in the other two plots.3.The dynamic change of soil microorganismThe amounts of three major microorganisms and the total amountsof microorganism showed obvious dynamic changes in different periods.The amounts of bacteria in the three plots was significantly higher than that before planting.In the early planting period,the amounts of soil fungi was higher in the hilltop and flood land.With the growth of Pennisetum sp.,the change trend of fungi in the hilltop and flood land was the same,which increased first and then decreased.In the three plots,the actinomycetes in the soil of the hilltop were higher than those in the other plots,and the actinomycetes in the farmland was the lowest,and the difference was significant.The total amounts of microorganism varied greatly,in 9.49×106～1.289×107 CFU/g dry soil,the rank is farmland>flood land>hilltop.The bacteria was account for the majority of the amount,which took up 82.44～93.38%.Actinomycetes was the second largest microorganism,which accounted for 5.89～17.41%.Fungi had the smallest amounts,which accounted for 0.09～0.16%.4.The correlation analysisThere was a positive correlation between the amounts of three microborganisms and the content of organic matter.There was a significant negative correlation between the amount of fungi and pH.Five kinds of soil enzymes had different correlations with three kinds of soil microorganisms.Polyphenol oxidase had a significant negative correlation with bacteria,urease and alkaline phosphatase were positively correlated with actinomycetes significantly.There is also a correlation between different soil enzymes.Among them,the correlation between urease,sucrase and alkaline phosphatase reached significant level.There was a significant positive correlation between catalase and urease,sucrase,alkaline phosphatase.5.The main fungi colonyThe fungi were isolated from the soil of three sample plots at tillering stage of Pennisetum sp.planted in Pisha sandstone area by using dilution plate method,and identified 21,15,30 strains of soil fungi respectively from flood land,farmland and hilltop land by using ITS-PCR molecular identification method.Mortierella spp.,Aspergillus spp.and Penicillium spp.took up the majority of the microorganism.6.The Illumina MiSeq sequencing results of bacteriaAccording to the results of Illuminna MiSeq high-throughput sequencing technology,in three plots of soil samples at 5 periods,dominant bacteria obtained at phylum level are the Actinobacteria,Proteobacteria.The abundance of Actinobacteria and α-Proteobacteria were highest at class level.At genus level,the highest abundance is unidentified.The results showed that there are abundant microbial resources in the soil of the sample land in Pisha sandstone area.The analysis of the Alpha and composition abundance of the bacterial community showed that the bacterial diversity and species abundance in three plots were higher than those before planting.The analysis of OTU level showed that there was significant difference in community composition with the growth of Pennisetum sp.in flood land,and the community composition of the sample was similar in hilltop land,while the species composition of farmland were different before and after planting Pennisetum sp..It is helpful to understand the correlation between soil ecological factors and soil microbial characteristics and their relationship with soil enzyme activity and basic physical-chemical properties.It provides the basic data for the improvement of Pisha sandsone soil by planting Pennisetum sp.. |
