The Research Of Microbial Diversity In The Wetland Of Sanjiang Plain

As an important role in the wetland ecosystem, soil microbial promotes the energy and material cycle of the ecosystem, and also maintains the ecosystem working orderly. It's very important to research soil microorganisms to understand the diversity of soil microbial and to investigate the wetland ecosystem structure and function deeply. In order to learn the population structure and diversity of soil microbial under different wetlands ecosystems in Sanjiang Plain, under the laboratory conditions, the number of bacteria, fungi and actinomycetes, the microbial genetic diversity of the bacterial communities and microbial metabolism of carbon sources were studied under different wetlands ecosystems. The results are as follows:The results of plate culture of microbial showed that, there are many differences between the wetland ecosystems (Calamagrostis angustifolia, turn farmland into grass and Carex lasiocarpa) and farmland ecosystems (dry field and paddy field) in the soil microbial community. During the three seasons in 2007 and 2008, the number of soil bacterial was the largest, followed by the actinomycetes, and the fungi was the least in the different ecological system, it showed that the bacteria was the main groups of the soil microbial in sanjiang plain wetland. The number of bacteria, actinomycetes and fungi were all the largest in the district of turn farmland into grass of spring, showed that the abundance of vegetation affected the changes of soil microbial communities. in summer, the number of bacteria, actinomycetes and fungi were relatively higher than others in the dry field, the number of soil microbial had dropped a little in the fall, it showed that the increase of the content in soil organic matter affected the changes of soil microbial communities significantly. The number of soil microbial of the district of the Carex lasiocarpa and the paddy field were relatively less than others.The results of the number of soil microbial were different between the 2008 year and the 2007 year in different wetland ecosystems. the number of soil microbial of the dry field were all higher than others in spring and summer, and in the autumn, the highest number of soil microbial is the turning farmland into grass. It showed that the climate of wetlands, soil temperature, the vegetation cover, soil organic matter content and soil aeration status of the wetland will have a greater impact on the populations and structure of soil microorganisms .The results of using DGGE to analyze the diversity of soil bacterial showed that, during the three seasons in 2007 year and 2008 year, the wetland ecosystem which was covered the plants had a relatively higher diversity than that of farmland soil microbial, indicated that man-made land reduced soil microbial diversity. In the studied of two years, the soil microbial community structure of Calamagrostis angustifolia and the turning farmland into grass have a high similarity, indicated that grassland vegetation in the farmland for the restoration of wetlands in good condition after; and agro-ecosystem and soil samples is similar to the other three relatively low, that man-made farming soil microbial community structure can affect change, and the agro-ecosystem and the other three soil samples are relatively low similarity to illustrate the changes of the impact of man-made farming soil microbial community structure. The shannon diversity index of soil microorganisms of different ecosystems had a clear upward trend in the summer, the other two seasons are relatively low and little change in shannon diversity index, while there also had relatively low similarity between the agro-ecosystem and the other three soil samples. It indicated that farming can affect the structure of soil microbial community. It may be due to the thriving of plant growth, and the increase of root exudates made the H' value of the soil bacteria increased, there had a significant increase in the area of paddy field. It showed that the vegetation form and the soil temperature had a greater impact on the soil microbial in the wetland of Sanjiang plain, the extent of the impact due to the number and types of the vegetation and the vary of vegetation coverage. In the autumn, the diversity index of soil microbial decreased because of the declined of the abundance of microbial populations in agro-ecosystem.The technical of Biolog micro-plate to analyze the soil microbial functional diversity of wetlands, the results show that, the soil microbial average well color development (AWCD value) of the dry field were the highest, Shannon diversity and evenness index of soil microorganism were the highest in the area of the dry field, the Carex lasiocarpa area was minimum, because of collecting soil samples in the summer, the agro-ecosystem as a result of the impact of fertilizer application, soil organic matter content increased, the studies have showed that fertilization can significantly promote the growth of microbial communities. the utilization of six types of carbon sources was the highest in the dry field, Carex lasiocarpa is minimum, the soil samples of microbial communities is the main use of other types of carbon carbon and carboxylic acid carbon.principal component analysis had a similar results to the analysis of the Shannon diversity index, principal component analysis results showed that the sugars, acids and carbon source is the main use of carbon sources whch soil microbial communities utilized under different ecosystems.