Distribution Characteristics of Soils Microbial Community in Natural Salt Marshes and Restored Salt Marshes in the Yellow River Delta

In order to explore the ecological effects that resulted from recovery project on the soil microbial community in the Yellow River Delta, research soil samplings which were respectively taken from natural tidal salt marshes and recovery regionsand the phospholipid fatty acid ( PLFA ) analysis were used to study the characteristics of four kinds soil microbial community (Bacteria, Fungi, Arbuscular mycorrhizal fungi and Actinomycete) in 0-30 cmsoil layer from the two regions, and the difference in different vegetation conditions (Phragmitesaustralis, Suaeda salsaandBare land ) weredistinguished. The results showed that soil total PLFA content was in the scale of 4.25~32.71 nmol.g-1, which were dominated by bacteria community. According to the PLFA content, theabundance of the four microbial groups was ordered as : bacteria (8.47±4.66 nmol.g-1) >fungi (1.28±2.11 nmol.g-1) >actinomycetes (0.98±0.68 nmol.g-1) > arbuscular mycorrhizal fungi (0.29±0.27 nmol.g-1) . The PLFA content results showed that in recovery region the soil PLFA content was higher than that in the natural tidal region, with bacterial PLFA increasing by 39.63% in average, fungia PLFA by 63.56% in average, actinomycetes PLFA by 65.14% in average, and arbuscular mycorrhizal fungi PLFA by 69.22% in average, which may be caused by soil pH value decreased, and soil organic carbon increased after the recovery project by freshwater pumping in and therefore plant especially the large biomass plant–reed development.Comparing three vegetation conditions, PLFA content of four microbial groups was in the order of Phragmitesaustralis (7.43~32.71 nmol.g-1) >Suaeda salsa (4.87~16.58 nmol.g-1) > bare land (4.25~7.54 nmol.g-1). Six kinds of PLFA in soil samples ordered as Phragmitesaustralis in recovery area (17.70~32.71 nmol.g-1) >Suaeda salsa in recovery area (10.71~15.44 nmol.g-1) >Phragmitesaustralis in tidal area (7.43~12.23 nmol.g-1) > bare land in recovery area (5.93~7.54 > nmol.g-1) >Suaeda salsa in tidal area (4.87~6.50 nmol.g-1) > bare land in tidal area (4.25~5.02 nmol.g-1). The total PLFA content and the relative abundanceof fungi PLFA in Phragmitesaustraliscommunity in recovery region increasedmore than othersbecause of the Phragmitesaustralisgrowthleading to the increasedsoil organic matter and decreasedpH value.Compared withthe other three kinds of microbial groups, fungi had larger response amplitude toreed development and freshwater pumping into the salt marshes. It confirmed that the important role of soil fungi in the decomposition of plant litter and the transformation of plant carbon into soil carbon. An increase of PLFA contentin salt marshsoilsdemonstrated that the freshwater supplementation significantly increased the biomass of soil microorganisms in Phragmitesaustralis community which may be mostly due to the simulated microbial proliferation involved into the reed litter decomposition processes.However, the microbial biodiversity and biogeochemical processes, even theecosystem structure and function of salt marshes after freshwater supplement need to be further monitored and evaluated systematically and comprehensively.