Soil Insect Community And Soil Microorganism And Their Relativity In Meadow Of Zhalong Wetland

Wetland ecological system is called the three ecosystems together with the forest and the sea in the world, and it is an ecosystem with the most rich biological diversity and productivity in nature. It is known as "the cradle of mankind","gene bank" and "the kidney of the nature" because of its huge production function and ecological environmental benefits. Zhalong wetland is a wetland ecosystem, and it is preserved most entirely and primordially in the northern of China, and it plays an important role in supplying water resource, controlling flood, purifying water quality, regulating weather and protecting the biodiversity. Therefore, people pay more and more attention to the protection of Zhalong wetland. At present, a comprehensive review on the research advance of soil insect community structure and soil microorganism and their relativity in meadow of Zhalong Wetland has not been reported. Relying on the interspecific relationship of soil insect and soil microorganism, this study based on the study of soil microbial properties and soil insect population dynamics to reveal the relativity of soil insect community and soil microorganisms and the main environmental interaction factors. They have great practical guiding significance for the ecological regulation of Zhalong wetland. Furthermore, they can provide basic data and theoretical basis for further study on indicative function of soil insects’ effect on soil quality changes.In this study, we took the meadow habitat in Zhalong wetland as the research object, adopted the research methods of field investigation and laboratory test, selected4sites (Tumutai, Guanliju, Yangtongtun, Yuweichang) in Zhalong wetland, conducted the system research on the soil insect community, soil microorganisms and their relationships in May, July, September and November, in the year2011. Synthesizing all the results, we draw the following conclusions:1. The study on soil microbial properties in meadow of Zhalong wetland.Throughout the sampling period, soil bacteria accounted for absolute advantage in different seasons and sample plots. It was the main decomposer in meadow ecosystem in Zhalong wetland. The quantity of soil actinomycetes was next to soil bacteria. The quantity of soil fungi was in the lowest. Spatio-temporal dynamics of soil microbial community in meadow of Zhalong wetland was significant. The basic rule of horizontal dynamic of the quantity of the total microorganism, bacteria, fungi of soil and their proportion was Tumutai> Guanliju> Yantongtun> Yuweichang, that of actinomyces was Tumutai> Yuweichang> Guanliju> Yantongtun, the quantity and proportion of soil microorganism group were the highest in Tumutai plot. The basic rule of vertical dynamic of the total microorganism, bacteria, fungi of soil and their proportion wss0-10cm>10-20cm>20-30cm and soil microbial number decreased with the increase of soil depth. Their basic rules of seasonal dynamics were different, that of the total microorganism was November> September> July> May; that of bacteria was September> July> November> May; that of fungi was November> May> July> September; that of actinomyces was November> May> September> July.2. The study on the population dynamics of soil insect in meadow of Zhalong wetland.This study captured soil4974insects belonging to13orders,82families (or groups)134species, including1224large soil insects belonging to6orders,51families and75species, and small and medium-sized soil insects3750belonging to13orders,50families and59species. Diptera, Coleoptera and Collembola took the advantage, Community characteristic index of Coleoptera was the maximum and that of Collembola was the minimum. Total diversity index values of soil insect community in meadow of Zhalong Wetland was Higher, the general characteristics of horizontal distribution of the communities showed diversity index and evenness index were the highest in Yuweichang, the richness index was the biggest in Yantongtun, in which3index of the large soil insects were the highest Tumutai, that of small and medium-sized soil insect showed were the highest in Yuweichang, but those of the insect community administration to were the lowest. Seasonal dynamics of soil insect community characteristics showed that the diversity index, the evenness index and richness index of insect community were positively correlated, showed the same variation trend, and the community structure was stable. Combining the species-abundance analysis, soil insect community in Guanliju, Yantongtun, Yuweichang conformed to the lognormal distribution model, that in Tumutai had a development trend to the lognormal distribution model, and that illustrated overall community structure of soil insect in meadow Zhalong wetland was stable. But the common species ratio of soil insect community in Tumutai had a trend to decrease, the dominant species and rare species ratio had a tend to increase, and the stability of community structure had a tend to be weaken.3. The study on the insect community and soil microorganism and their relativity.(1) Temporal and spatial dynamic of soil enzyme activity in meadow of Zhalong wetland varied significantly. The horizontal dynamic of soil enzyme activity was Tumutai> Guanliju> Yantongtun> Yuweichang; seasonal dynamic was May> July> Autumn> November; vertical dynamic of soil enzyme activity in the soil profile was0-10cm>10-20cm>20-30cm, and soil enzyme activity gradually reduced with the increase of vertical depth.(2) Temporal and spatial dynamic of soil physical-chemical factor in meadow of Zhalong wetland was significant. The horizontal dynamic of organic matter, total nitrogen and available nitrogen, total phosphorus and available phosphorus, total potassium and available potassium was Tumutai> Guanliju, Yuweichan> Yantongtun; seasonal dynamic of that was November> May> July> Autumn; vertical dynamic of soil physical-chemical factor in the soil profile was0-10cm>10-20cm>20-30cm, soil physical-chemical factor gradually reduced with the increase of vertical depth. The horizontal distribution of soil bulk density, temperature, pH had less significant difference; vertical dynamic showed significant difference; seasonal dynamics was not obvious. The soil in4study areas was alkaline soil, in which soil pH value were among9.01-10.50. (3) Soil microorganism and soil insect community in meadow of Zhalong wetland was closely related. The annual and seasonal relativity of them showed some differences. Throughout the year, Soil bacteria, fungi and actinomycetes were more closely related with soil insect community, and polyphenol oxidase, soil temperature and soil available phosphorus were the key interaction factors of them. In spring, the relationship between soil actinomycetes and soil insect community was most closely, and β-glucosidase, alkaline phosphatase and polyphenoloxidase, soil pH value were the key interaction factors of them. In summer, soil bacteria and fungi and soil insect community were more closely related, and alkaline phosphatase, soil organic matter, total phosphorus and total potassium were the key interaction factors of them. In autumn, soil actinomycetes was more closely related to soil insect community, and soil urease, soil total nitrogen were the key interaction factors of them. In winter, soil actinomycetes and bacteria influenced the changes of structure community of soil insect jointly. Soil actinomycetes was more closely related to soil insect community and P-glucosidase, catalase, polyphenol oxidase, and soil bulk density were the key interaction factors of them.This study took a wetland of international importance-Zhalong wetland as the background and focused on the international frontier research in the same field. From the perspective of quantitative and chemical ecology, this study further discussed the relativity of soil insect community and soil microorganism and the main soil environmental factors completing their relativity. Study on this aspect can enrich and expand the research field of interspecific interaction in wetland ecological system. In our country, the research on the relativity of soil insect community and soil microorganisms in wetland was less. Studying the research field had great theoretical significance to regional and national ecological environment and economic development.