| The upper reaches of Heihe River is located in the northern foothills of the Qinghai Tibet Plateau,with abundant rainfall,humid climate and little evaporation.It belongs to the Qilian Mountains and rivers conservation area.The water conservation capacity of the upper reaches of Heihe River largely supports the sustainable development of the ecological environment and social economy of the whole basin.In order to further explore the interaction mechanism between water cycle and environmental factors in the upper reaches of the Heihe River Basin under the background of global climate change,microorganisms were introduced to study the internal mechanism of nutrient transfer and transformation in the process of water cycle on the environmental impact,so as to further study the response of ecological environmental factors in the Heihe River Basin,for providing theoretical support for the Heihe River Basin to better play its ecological function.In this paper,based on the use of distributed hydrological model to divide the precipitation-elevation zone of the basin,the field soil and microbial investigation and experiment were carried out in the study area.The characteristics of soil and microbial community in the study area were analyzed under the macrogenomics technology and conventional soil detection technology,so as to study the distribution pattern of soil nitrogen and microbial in different zones of the upper reaches of Heihe River,and further discussed the study area.The main conclusions are as follows:(1)Evolution trend and driving factor identification of runoff in the upper reaches of Heihe RiverAccording to the analysis of meteorological data,the precipitation,temperature and runoff in the upper reaches of Heihe River are increasing,and the climate in the study area is becoming warm and humid.The correlation between runoff and climate factors shows that precipitation is the main driving factor of runoff in the upper reaches of Heihe River.(2)Distribution characteristics of soil nitrogen and microbial community in different regions of the upper reaches of Heihe RiverUsing the distributed hydrological model to divide the two-dimensional divisions of precipitation and altitude,five divisions are finally obtained.The results showed that the soil moisture content was larger in the area with more precipitation,and was positively correlated with the depth in the area with middle altitude;the total nitrogen content was higher in the area with less precipitation than more precipitation area,and the total nitrogen contents shows that low altitude area is higher than middle altitude area and high altitude area.Proteobacteria,Actinobacteria and Bacteroidetes have the highest abundance of microorganisms.(3)Response relationship between soil moisture and microbial communities in different regions of the upper reaches of Heihe River under climate changeHigh-throughput sequencing was used to analyze the microbial diversity in different regions,and redundancy analysis was used to study the correlation between soil microbial categories and environmental factors.The results showed that precipitation,soil water content and TN were the main factors affecting the characteristics of microbial community in the watershed,and the low altitude area was the most sensitive to the change of soil water content.(4)Prediction of the relationship between soil microorganism and water content in WatershedBased on the CCSM4 climate model of RCP4.5 scenario,the soil water content in the upper reaches of Heihe River will increase in the next 30 years as a whole.When the precipitation increases in the future,the microbial community in the low and middle altitude areas will change most significantly,and the abundance of Acidobacteria in the low altitude areas will increase,and the abundance of Bacteroidetes in the middle altitude areas of low precipitation will increase,and the abundance of Germmationades will increase.Actinobacteria is less affected by climate change. |
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