Response Of Soil Microbial Community Structure And Function To Water Condition Change In Wetland

Wetland ecosystem has unique hydrological history and biology characteristics,has high ecological diversity,species diversity and biological productivity.And hydrological processes are the key factors that affect the stability and degradation of wetland ecosystem,which has important influence on the material circulation and energy conversion of wetland ecosystem.Soil microbial is the decomposition of wetland ecosystem,but the knowledge and study of how soil microbial community structure and functional activity response to the change of water condition is still lack.In this study,the surface soil of Poyang lake wetland which the domain vegetation at this site was Carex cinerascens was collected to set a greenhouse experiment and set five water status:?1?control with no any process?ND?,?2?keep moisture at 30% soil water content?KM?,?3?flooding 0 cm?OF?;?4?flooding 10 cm?SF?;and?5?flooding 100cm?DF?.Using 16 S rDNA high throughput sequencing,DGGE and Biolog-ECO to analysis the soil properties,microbial biomass,bacterial community structure,extracellular enzyme activity and carbon source metabolic activity.Studying the response of soil microbial community structure and metabolic function to different water condition in Poyang Lake wetland,so that to provide scientific theory for the protection and improvement of wetland ecosystem.The main results were:The flooding conditions can significantly increase the content of soil organic carbon?TOC?,ammonium nitrogen?NH4+-N?,and pH,while the KM and OF treatment have higher content of Nitrate nitrogen?NO3--N?.Soil physichemical factors reached a stable state on the 72 th day.At the same time,the effects of different flooding depth on soil physichemical factors were consistent,except the content of NO3--N.The soil microbial biomass was highest in the KM treatment,followed by the flooding treatments?OF,SF,DF?,and lowest in the ND treatment.And there were no significant difference among different flooding depths.Under different water conditions,the bacterial community structure of wetland soil changed drastically before the first 21 days,and then tended to a stable.The soil bacterial community structure of the flooding treatments?OF,SF,DF?were significantly different from ND and KM treatment.In 21 st days,it was found that the ND treatment had higher relative abundance of Acidobacteriaceae_Subgroup1and Micrococcaceae,KM had higher relative abundance of Oxalobacteraceae and Xanthomonadaceae while Clostridiaceae₁ was higher in the flooding treatment.But the depth of flooding had no significant effect on the soil bacteria community structure composition.Soil enzyme activity did not change on the first 21 days,then the change was significantly.The soil enzyme activity was lowest in the ND treatment.The activities of ?-glucosidase?Bglu?was higher in the KM treatment,and the phenoloxidase?PERO?and peroxidase?PHOX?had higher value under flooding treatment than ND and KM treatment.And there were also no significant difference among different flooding depths.The soil microbial biomass in the wetland soils decreased significantly under different water status,and tend to stable after 21 days.The soil biomass was highest in KM treatment,followed by the flooding treatments?OF,SF,DF?and lowest in ND treatment.There was no significant difference among the flooding depth.The analysis of utilization of carbon sources using Biolog Eco-plates in ND,KM and DF treatment showed that the utilization of carbon sources of wetland soil of wetland soil changed drastically before the first 21 days,and then tended to a stable.It showed that the utilization of carbon sources was highest in the KM treatment,followed by DF treatment,and lowest in the ND treatment.Meanwhile the further studies shown that the ND treatment has a higher utilization of Polymer and Carbohydrates than the other treatments,the DF treatment were more inclined to utilization of Amino acid,while the KM treatment had higher utilization of six kinds of carbon sources.In summary,the moist soil environment is benefit to the growth and metabolism of wetland soil microbial.The flooding conditions significantly change the soil physichemical properties,and bacteria community structure composition,while the dry soil environment significantly decreased the soil enzyme activity and carbon source metabolism.The results of this study confirm the response of soil physichemical properties and soil microbial community to different water condition in Poyang Lake wetland,and further reveal the influence of hydrological processes on wetland ecosystem,which provides a scientific theory basis for wetland environmental protection and improvement.The results suggest that maintaining a large area of Chau beach wetland is essential for the protection of wetland ecosystems,The future wetland protection should not only pay attention to the flooding depth of wetland soil,but also pay attention to wetland flood area and flood time.