Study On The Diversity Of Arbuscular Mycorrhizal Fungi And On The Population Characteristics Of Soil Microorganisms In Coal Mining Areas

Coal mining is one of the man-made activities which is harmful to the natural ecosystem. Open coal mining will directly destroy topsoil and vegetation while underground mining can cause strata collapse, which will lead to destruction of soil and vegetation. It also has a bad influence on the soil microorganisms and thus causing the disorder of ecosystem structure and function. Microorganisms are one of the most important biological components in the soil, and also an important environmental monitor. It can reflect the status of disturbance of the ecosystem and also can promot the restoration of vegetation in the disturbed ecosystem. Arbuscular mycorrhizal fungi(AMF) are important fungi which form symbiosis with higher plants. Their diversity directly influence the absorption of nutrients by plants and influence the growth as well as resistance of plants. They not only determine the vegetation diversity, distribution and productivity of natural ecosystem but also influence restoration of the ecosystem and reconstruction of vegetation. In this paper, the influences of coal mines exploitation to the soil AM fungi, the quantity of soil microorganisms, soil phosphatase content and physical and chemical properties of soil and their correlations based on the different exploitation methods(open mining and underground mining) and different exploitation life years of coal mining of Dzungar Inner Mongolia are studied. The paper aims to explore the extent of destructions of coal production to the soil microbial communities of grassland ecosystem and to explore the related factors and to provide the theoretical basis for the choosing of the infertility-resistant and interference-resistant AM fungi recourses in coal mining areas, and also for vegetation restoration and land reclamation in mining areas. The main conclusions are as follow:1. Coal mining in fluences vegetations of mining area, the most severely damaged is the mining area and the least is the undisturbed area. The vegetations were destroyed more serious in the open mining sample area than in the underground mining area. The vegetation coverage and plant density of the open mining area is lower than the underground mining area.2. Coal mining has disturbed the soil edaphic characteristics and the content of soil phosphatase. In the undisturbed area of the open mining position. pH value and the content of total phosphorus, hydrolytic nitrogen and phosphatase are higher than the mining area. But the content of available phosphorus, total nitrogen and organic matter in the transition area and mining area are higher than the undisturbed area. All the values except the hydrolytic nitrogen decrease with the increase of soil depth. In the undisturbed area of underground mining position, the content of total phosphorus, total nitrogen, hydrolytic nitrogen and phosphatase are higher than the mining area. Compared with the open mining area, the content of total phosphorus, available phosphorus, total nitrogen and hydrolytic nitrogen are lower than the underground mining area.3. In the study sites, the total bacterial amount is 8～50×103 per gram soil, the total fungi amount is 0-6 X 102 per gram soil and the total actinomyces amount is 0～16×104 per gram soil. The effect of mining method and exploitation life years to soil microorganisms is not obviously while Xiaoyugou coal mine which exploitation life years is the least in study areas has a higher amount of soil bacterial and fungal than other sample mining areas. Except the Xiaoyugou coal mine, the microorganism amount in study sites are as follow:the undisturbed area>the transition area>the mining area. Coal mining reduces the soil microorganism amount. The open mining area has a more serious situation than the underground mining area. The soil microorganism amount decreased with the increase of soil layer depth in all study sites and the order from high to low is 0-5cm,5-15cm,15-30cm.4. Thirteen species of AMF were isolated from the soil of the study area. Those 13 species belong to three genus, one belongs to Acaulospora, one belongs to Scutellospora and eleven belong to Glomus. Acaulospora sp. One of the 13 species is an unregistered specie. Glomus is the dominant genus of this sample area. Glomus mosseae.G. constrictum, D. versiforme, G. Deserticola are the dominant species in the sample area. AMF spore density in six sample plots are as follow:U1>U3>U5, S5>S10>S 15. The AMF species richness of Ul plot is higher than other sample plots. The AMF diversity in the underground mining is higher than in the open coal mining. The variation trend of AMF spore density and species richness in soil layer is as follow: 5-15cm>0-5cm>15-30cm. There are no significant differences between the Shannon-wiener index in 0-5cm and 5-15cm soil layer and both of them are higher than 15-30cm. The variation trend of AMF diversity in sample plot is as follow:the undisturbed position>the transition position>the coal mining position. The method and age of coal mining have different influences on soil microorganisms amount and AM fungi, the effect of the open mining is more serious than the underground mining and the long exploitation life years is more serious than short exploitation life years.5. The results of the correlation analysis show that:AMF spore density has very significant negative correlation with mining disturbance at p<0.01 and has significant negative correlation with soil depth at p<0.05; AMF species richness has very significant negative correlation with mining disturbance at p<0.01 and has significant negative correlation with soil depth and mining method at p<0.05; The Shannon-wiener index has significant negative correlation with mining disturbance and the way of exploitation at p<0.05. AMF spore density, species richness and the Shannon-wiener index have very significant positive correlation with the bacteria and actinomyces amount and soil phosphatase at p<0.01 and have significant positive correlation with fugal count at p<0.05. AMF spore density and the Shannon-wiener index have no significant correlation with soil factors. AMF species richness has significant positive correlation with soil pH value at p<0.05 and has significant negative correlation with soil organic matter at p<0.05. Soil microorganism amount has no significant correlation with the method and years of exploitation and has negative correlation with mining disturbance and soil depth. The content of soil phosphatase correlated significantly with the method and years of exploitation, mining disturbance and soil depth. It also has very significant positive correlation with soil microorganism quantity and AMF spore density, species richness and the Shannon-wiener index at p<0.01.6. The damage of the open coal mining is more serious than the underground coal mining and the bigger the coal mining scope,the greater the destructive effect. The ecological environment of the loess plateau region is fragile and the damage of coal mining is seriously.