Researches On The Mid-infrared Spectrogram Of Organic Matters And Spatial-temporal Distribution Of Soil Carbon And Nitrogen In Community Succession Under Different Water Levels Of Poyang Lake

Poyang Lake was the largest freshwater lake in China.As an important wetland in the world,Poyang Lake wetland was one of the first wetlands listed in Ramsar Convention on Wetlands.The Nanjishan wetland and Wuchen wetland of Poyang Lake was selected as the study area and its different water periods?normal season,dry season and wet season?as well as different community types?Naked mudflat,Zizania caduciflora,Carex cinerascens,Triarrhera lutarioriparia and Phragmites australis?were selected as the variables in this research.Under those variables,the author made a research on the carbon and nitrogen contents,the soil physical and chemical properties,characteristics of carbon and nitrogen content distribution and labile organic matter and influence factor.The paper studied on structural features of soil organic matter which in different places,different water periods,different community succession by Flourier transformation infrared spectroscopy.Major findings are as follows:The soil physical and chemical properties in five types of different comnunity under different water periods of Poyang Lake were different.There have not significant difference about soil physical and chemical properties in different places.The physical and chemical properties of soil have little difference in different places and the soil water content of Nanjishan wetlands is at a higher degree of 58.21%.As for the soil of Zizania caduciflora type in different community successions,the highest degree of soil water content is 130.89% while the lowest degree of temperature and PH value is 8.60? and 4.72 respectively.The highest soil temperature of the Triarrhera lutarioriparia is 17.67?.The lowest degree of soil water content of Phragmites australis is 37.94%.The highest value of PH in naked mudflat is 6.76.Generally speaking,the temperature rankings of different water periods are as follows: wet season > normal season> dry season;PH are as follows:dry season > wet season> normal season;soil water content are as follows:normal season > wet season > dry season.The contents of soil carbon,nitrogen and active organic matter vary in different places and water levels as well as the different periods of community succession.There's no significant difference in the contents of soil carbon and nitrogen in different places but the differences are significant in the active organic matter content of naked mudflat soil in two places?p<0.05?.In different successions of communities,the contents of soil carbon,nitrogen and active organic matter in the zizania caduciflora community are the highest among all the communities,which respectively are 23.21 mg/g and 2.19 mg/g and 7.27 mg/g,showing a significant difference?p<0.05?.The significant differences in the contents of soil total carbon and nitrogen under different water levels are shown as follows: normal season>dry season>wet season.Generally speaking,the content of active organic matter in the normal and dry season is higher than that in wet season.The contents of soil carbon,nitrogen and active organic matter have a significant negative correlation with the PH value?p<0.01?and the temperature?p<0.05?,but a high positive correlation with the soil water contents?p<0.01?.The content of soil active organic matter has a significant positive correlation with the content of soil total carbon and nitrogen?p<0.01?.The infrared spectrum types of soil in different communities are nearly the same while the characteristic peak intensities of soil organic matter are different in community succession.The infrared peak of various wetland soil is about 3696cm^-1 ?3622cm^-1?3422 cm^-1?2920 cm^-1?2840 cm^-1?1633 cm^-1?1380 cm^-1?1033 cm^-1?913 cm^-1?798 cm^-1?780 cm^-1?694 cm^-1,which means that the soil of five wetlands contains hydroxyl,C=C of aromatic structure,or the amide linkage,aliphatic ethylene,xylogen,aliphatic compound,siliceous clay minerals and olefin.The seasonal water level variations of Poyang Lake have an effect on the composition and structure of soil organic matter of different communities in Nanjishan Wetland.The soil infrared spectrograms of different wetlands in Nanjishan and Wucheng are similar for their same soil perssads.The peak intensities of second derivative infrared spectrograms of Nanjishan wetland soil around 539 cm^-1?479 cm^-1 are strong than those of Wucheng Wetland,which implies that the soil structures and compositions of Nanjishan Wetland and Wucheng Wetland are different and the content of siliceous clay minerals in Nanjishan Wetland is higher than that in Wucheng Wetland.