Studies On Recovery Ecology Of The Degraded Phragmites Australis Wetland In Yinchuan Plain

This paper takes Phragmite saustralis wetland in Yinchuan plain (in Ningxia) as the research object, makes a study on the general characteristics of the Phragmite saustralis community, the comparative of the characteristics of the degradation and non-degraded Phragmite saustralis community, the relationship of Phragmite saustralis community and environmental factors, the influence of Phragmite saustralis growth under the different harvesting and moisture management by using field survey, sentinel surveillance, simulation cultivation and methods of indoor comprehensive analysis. On this basis, the causes of degradation and the thinking of recovery about Phragmite saustralis wetland in Yinchuan plain are clarified. The details are as follows:(1) Phragmite saustralis community in Yinchuan plain which consisted of four community associations that includes single Phragmite saustralis association, Phragmite saustralis+Typhaorientalis association. Phragmite saustralis+Scirpustabernaemontani association and Phragmite saustralis+other phreatophyte association. Phragmite saustralisis constructive and dominant species of the wetland in Yinchuan plain, Its relationship with Typhaorientalisis fierce competition exclusion and its relationships with other plants are relatively stable.However,the interspecific relationship of Phragmite saustralis wetland in Ningxia was loose and community is not stable, so it is easy to be changed by environmental impact.(2) The stratification of degraded Phragmite saustralis community is more and its diversity index ishigher than non-degraded Phragmite saustralis community, but the biomass and coverage is opposite to all varies of those. Total fresh weight, plant height and stalk diameter can be used to characterize the growth condition of the Phragmite saustralis. It showed different degree of negative correlation between the densityof Phragmite saustralis with other indicators (except coverage). The ratio of reproductive modules biomass for Phragmites australis increased was a protective mechanism within populations.The density of degraded Phragmite saustralisis higher than non-degraded,at the same time, the life cycle has shortened. These show that the density increases is not only the important degradation performance of Phragmite saustralis community, but also an important reproductive strategy that called "r-reproductive strategy".(3)0～50cm soil layer of the wetland in Yinchuan plain were alkaline soil.The total salt, organic matter, total nitrogen and alkaline hydrolysis nitrogen variation lawsaremore consistent and showed " table cohesion". In0～20cm soil layer, soil moisture content has a significant positive correlation with the Biomass weight of fresh leaf. In0～30cm soil layer,the content of nitrogen has a significant positive correlation with total biomass. The accumulation of soil nutrients and salt can causeecological index changes of Phragmite saustralis but these changes does not directly cause the Phragmite saustralis wetland degradation, it also shows that the accumulation or losses of soil nutrients and salt has not exceeded their growth threshold even for the degradation Phragmite saustralis community.(4) Fire treatment with warming effect can promote growth and development for Phragmite saustralis in good time,because it makes soil to warming and further thawing and breaks the dormancy of winter bud and germinated in finally. The surface of the litter must be removed inharvest processing.lt is good for growth of Phragmite saustralis by the means of thatbecause of havingmore space to compete the water, fertilizer,gashot and the other resources for aboveground vegetation. Stable flooded environment is more conducive to Phragmite saustralis growth, but wetting-drying alternation also can satisfy basic growth needs,which proves that water-saving is certainly feasible reed wetland.(5)The habitat changes directly causethe degradation to Phragmite saustralis wetland in Yinchuan plain, however,human activity is the primary causes. Phragmite saustralis wetland plays an important ecological effect in Ningxia.To restore and protect Phragmite saustralis wetland is very urgent. As follows suggest:in the process of recovery and protection must follow the law of nature.The mode of management for Phragmite saustralis wetlandmust be optimized. The new ways of sustainable utilization of resources must be opened up. Establishing and perfecting the legal system for wetland must be established and encourage and mobilize people to participate.