Characteristics Of Soil Microbial Carbon And Nitrogen In Poyang Lake Wetland And Their Responses To Soil Temperature And Water Change

Soil microbes are an important part of the ecosystem,directly involved in the decomposition of organic matter,the formation of humus,the conversion and recycling process of nutrient,such as nitrogen and phosphorus.It plays an important role in promoting the energy and material circulation of ecosystems and maintaining the normal functioning of ecosystems.Strengthening the study of soil microbial biomass in wetland is of great significance for further understanding of wetland ecosystem structure and function.The study selected four typical wetlands in Wucheng,Xingzi,Poyang,Nanji nature reserve of Poyang Lake.Collecting the rhizosphere soil of common plant species to determine the microbial biomass carbon and nitrogen.At the same time,we collected different depths of surface soil?0-10cm and 10-30cm?under three kinds of vegetation—Triarrhena lutarioriparia L Liu.,Carex cinerascens Kükenth.and Hydrilla verticillata.The microbial biomass C and N were analyzed after a short-term?2-weeks?incubation of different temperatures and water treatments.Through the above study,we try to explore the distribution characteristics of soil microbial biomass carbon and nitrogen in typical wetlands of Poyang Lake and the response to water and temperature,so as to provide basic data for further illuminating the impact of climate change on soil carbon pool in Poyang Lake wetland and provide basic data.The results were as follows:?1?Soil MBC and MBN in Poyang Lake wetland showed large variations.MBC ranged from 5.43 to 394.87 mg·kg^-1 and MBN ranged from 0.45 to 43.96 mg·kg^-1,respectively.The average of MBC and MBN were 105.84 mg·kg^-1 and 17.68 mg·kg^-1,respectively.MBC/MBN ranged from 0.32 to 43.05.The mean MBC:MBN ratio was7.463,which was concentrated in the range of 6.54 to 13.07 and 13.07 to 19.61.?2?There were significant differences in soil MBC and MBN contents under different vegetation types.Even under the same vegetation type,there was a large variation in soil MBC and MBN?3?The correlation analysis showed the wetland soil MBC was significantly correlated with MBN,MBC/MBN and SOC?P<0.01?.The soil MBN had an significant correlation with MBC,but no correlation with TN,MBC/MBN and SOC?4?The temperature and soil water had an extremely significant correlation with MBC,MBN?P<0.01?;The temperature increased from 18?to 28?,the average content of soil MBC and MBN increased to 51.96 mg·kg^-1?4.65 mg·kg^-1.?5?Under the environment of low temperature of 18?,the soil MBC showed that increased first and then decreased with the increase of soil water content.Soil MBN content increased with the increase of soil water,MBN content increased first and then decreased and then increased.The content of MBN in the surface soil varied with the water level.Under the environment of high temperature of 28?,The contents of MBC in the surface soil and the bottom soil increased with the soil water then decreased,decreased with the soil water,respectively.and the content of MBN in the surface soil increased-decreased-increased with the increase of soil water,The bottom soil decreased first and then increased.